JP7081809B2 - Control method in ground construction machine and ground construction machine - Google Patents

Description

The present invention relates to a ground construction machine that rotationally drives tools such as an auger screw and a stirring tool to perform excavation and ground improvement work on the ground, and a control method in the ground construction machine. In a ground construction machine equipped with a hydraulic motor that can be changed, the upper and lower limits of the drive torque of the tool can be set, and control is performed so that the optimum drive torque is obtained between the upper and lower limits. The present invention relates to a ground construction machine capable of appropriately controlling the number of blade cuttings of a stirring tool in a predetermined section of a predetermined length so as not to fall below a target value, and a control method in the ground construction machine.

A ground construction machine that rotationally drives an auger screw to excavate the ground or rotationally drives a stirring tool to improve the ground has been conventionally used. For example, when excavating the ground, it is necessary to set the drive torque and rotation speed of the tool (auger screw) to appropriate values according to the condition of the ground to be excavated (soft, hard, etc.).

Ground improvement by a ground construction machine is to create a columnar improvement pile in the ground. First, a columnar excavation is performed on the ground with a stirring tool that excavates and stirs the ground, and a ground improving agent such as cement milk is injected into the ground from the stirring tool and the ground is stirred to form a columnar shape. It is intended to create columnar improved piles. The solidification of these columnar improved piles greatly increases the strength of the ground.

In the ground construction machine, multiple gears with different relationships between the drive torque of the tool and the rotation speed are set, and the operator selects and sets the most appropriate gear from those gears according to the condition of the ground. Something like that has been known for some time. Further, a ground construction machine that automatically shifts such a shift stage is also known. In Patent Document 1 below, there is a ground construction machine that uses a variable displacement hydraulic motor that can change the push-out volume, sets multiple shift stages, and automatically selects the shift stage. Have been described.

In the ground improvement by the ground construction machine, the number of blade cuttings per unit length of the columnar improved pile is an important index related to the strength and uniformity of the columnar improved pile. Here, the number of times of blade cutting represents the number of times that the stirring blade of the stirring tool passes, and is obtained by multiplying the number of rotations of the stirring tool by the number of blades. When constructing columnar improved piles, a target value for the number of blade cuttings per unit length is set.

A ground improvement construction method for controlling the number of blade cuttings so as to match a target value is known. In Patent Document 2 below, the number of blade cuttings is calculated when the stirring tool is lowered in a section of a predetermined length at a certain depth, and the difference between the calculated value and the target value is calculated as the number of insufficient blade cuttings. A ground improvement construction method is described in which the ascending speed of the stirring tool when ascending is determined and controlled based on the number of insufficient blade cuttings.

Japanese Patent No. 6310239 Japanese Patent No. 3430148

In a ground construction machine such as Patent Document 1, the upper limit value and the lower limit value of the drive torque of the tool can be set, and the optimum drive torque is stably and smoothly set between the upper limit value and the lower limit value. Shift control can be performed. In addition, the optimum shift stage can be automatically selected according to the condition of the ground, and the ground can be efficiently constructed without depending on the advanced judgment and technique of skilled workers.

Further, in the ground improvement by the ground construction machine, the target value of the number of blade cuttings per unit length of the columnar improved pile is set in order to ensure the quality of the columnar improved pile. In order to achieve the target value for the number of blade cuttings of the stirring tool, it is useful to perform the control as described in Patent Document 2 described above. In the control of Patent Document 2, the number of insufficient blade cuttings is calculated when the stirring tool is lowered in a section of a predetermined length at a certain depth, and the ascending speed when the stirring tool is raised is determined based on the number of insufficient blade cuttings. It is a thing, and once the ascending speed is determined, the ascending speed is instructed throughout the section.

Therefore, if there is non-uniformity of the ground composition in the section, the rotation speed of the stirring tool may fluctuate, and the number of blade cuttings in the section may not reach the target value. Further, when the ground construction machine that automatically controls the shift as described in Patent Document 1 is controlled so that the number of blade cuttings in such a predetermined section surely reaches the target value, Patent Document 2 There is a problem that the control method such as is not applicable as it is. This is because in the ground construction machine that automatically controls the speed change, the rotation speed of the stirring tool may be changed by the speed change control at any time, so the ascending speed of the stirring tool in the predetermined section was always set to a constant value. Then, there is a possibility that the number of blade cuttings does not reach the target value.

Therefore, according to the present invention, in a ground construction machine equipped with a hydraulic motor capable of continuously changing the push-out volume, the upper limit value and the lower limit value of the drive torque of the tool can be set, and the optimum upper limit value and the lower limit value can be set. A ground construction machine that can control the drive torque and appropriately control the number of blade cuttings of the stirring tool in a predetermined section of a predetermined length of the columnar improved pile so that it does not fall below the target value. Regarding the control method in the ground construction machine.

In order to achieve the above object, the control method in the ground construction machine of the present invention includes a stirring blade and a spout for a ground improving agent, and a stirring tool for creating a columnar columnar improving pile in the ground, and the above. The hollow tubular rod in which the stirring tool is fixed to the lower end, the elevating drive unit that drives the stirring tool in the descending or ascending direction with respect to the ground, and the push-out volume can be continuously changed, and the stirring tool can be used. Ground construction equipped with a rotary-driven hydraulic motor, a rotation detector for detecting the rotational position or rotational speed of the stirring tool, and a pressure detector for detecting the pressure of the fluid supplied to the hydraulic motor. A procedure for setting an upper limit value and a lower limit value of a drive torque actually used for rotationally driving the stirring tool within a range of the drive torque that can be generated by the hydraulic motor, which is a control method in the machine, and the lower limit value. Within the range above and below the upper limit value, a procedure for setting a plurality of drive torques including the lower limit value and the upper limit value, and a plurality of push-out volumes of the hydraulic motor corresponding to the set drive torques are obtained. The procedure, the procedure for setting the reference value of the pressure for shifting from the push-out volume other than the lower limit volume corresponding to the lower limit value to the push-out volume one step smaller for each push-out volume as the lower reference value, and the upper limit. A procedure for setting a reference value of the pressure for shifting from the push-out volume other than the upper limit volume corresponding to the value to a push-out volume one step larger for each push-out volume as an upper reference value, and adjacent to the push-out volume. A procedure for setting a reference time for shifting to the push-out volume for each shift, and a state in which the hydraulic motor is in a predetermined push-out volume other than the lower limit value and the pressure is equal to or lower than the lower reference value. The procedure for shifting to a push-out volume one step smaller when is continuous for a reference time or longer, and the state where the hydraulic motor is in a predetermined push-out volume other than the upper limit value and the pressure is equal to or higher than the upper reference value. In the procedure of shifting to a one-step larger push-out volume when the volume is continuous for a reference time or longer, and in the stirring lowering step of stirring while lowering the stirring tool, the stirring tool of the stirring tool in a predetermined section of a predetermined length of the columnar improved pile. In the procedure of counting and storing the number of blade cuttings and the stirring ascending step of performing stirring while raising the stirring tool, the current position of the stirring tool, the number of blade cuttings during ascending in the predetermined section, and the stirring tool. From the current rotation speed of A procedure for calculating and setting the ascending speed in the remaining section of the predetermined section of the stirring tool so that the total number of the stirring lowering step and the stirring raising step of the number of blade cuttings of the stirring tool does not fall below the target value. It has.

Further, in the control method in the above-mentioned ground construction machine, the procedure for calculating and setting the ascending speed of the stirring tool is that the total number of the stirring lowering step and the stirring ascending step of the number of blade cuttings of the stirring tool in the predetermined section is set. When the value exceeds the target value, it is preferable that the ascending speed of the stirring tool is not changed.

Further, in the control method in the above-mentioned ground construction machine, the procedure for calculating and setting the ascending speed of the stirring tool is that the total number of the stirring lowering step and the stirring ascending step of the number of blade cuttings of the stirring tool in the predetermined section is set. When it is determined that the current ascending speed is equal to or higher than the target value, it is preferable that the ascending speed of the stirring tool is not changed.

Further, the ground construction machine of the present invention is provided with a stirring blade and a spout for a ground improving agent, and a stirring tool for creating a columnar columnar improving pile in the ground and the stirring tool are fixed to the lower end portion. A hollow tubular rod, an elevating drive unit that drives the stirring tool in a descending or ascending direction with respect to the ground, a hydraulic motor that can continuously change the push-out volume and rotationally drives the stirring tool, and the stirring. A rotation detector for detecting the rotation position or rotation speed of the tool, a rotation drive unit for transmitting the rotation output of the hydraulic motor to the stirring tool, and a pressure of a fluid supplied to the hydraulic motor are detected. The stirring tool is lifted and lowered via the pressure detector, the drive control unit that controls the push-out volume of the hydraulic motor to drive and control the hydraulic motor to generate an appropriate drive torque, and the lift drive unit. The drive control unit includes an elevating control unit that controls movement, and the drive control unit is provided with a storage means for storing information, and the storage means is within a range of drive torque that can be generated by the hydraulic motor. A plurality of drive torques including the lower limit value and the upper limit value are stored in the range of the lower limit value or more and the upper limit value or less while storing the upper limit value and the lower limit value of the drive torque actually used for the rotary drive of the stirring tool. Is stored, a plurality of push-out volumes of the hydraulic motor corresponding to each of the set drive torques are stored, and a reference for the pressure for shifting from the push-out volume other than the lower limit value to a push-out volume one step smaller. The value is stored as a lower reference value for each push-out volume, and the reference value of the pressure for shifting from the push-out volume other than the upper limit value to a push-out volume one step larger is used as an upper reference value for each push-out volume. The reference time for shifting from the push-out volume to the adjacent push-out volume is stored for each shift, and further, in the drive control unit, the hydraulic motor is other than the lower limit value. When the pressure is below the lower reference value continuously for a reference time or more while being in the predetermined push-out volume, the procedure for shifting to the push-out volume one step smaller and the hydraulic motor is other than the upper limit value. When the pressure is continuously equal to or higher than the upper reference value for a reference time or longer while being in the predetermined push-out volume, the procedure for shifting to the push-out volume one step larger is executed, and the elevating control unit performs the procedure. In the stirring lowering step of stirring while lowering the stirring tool, the columnar In the procedure of counting and storing the number of blade cuttings of the stirring tool in a predetermined section of a predetermined length of the improved pile and the stirring raising step of stirring while raising the stirring tool, the current position of the stirring tool and the above. From the number of blade cuttings during climbing in the predetermined section and the current rotation speed of the stirring tool, the total number of the stirring lowering steps and the stirring rising steps of the number of blade cuttings of the stirring tool in the predetermined section is less than the target value. The procedure for calculating and setting the ascending speed in the remaining section of the predetermined section of the stirring tool is executed so as not to cause the above.

Further, in the above-mentioned ground construction machine, in the procedure for calculating and setting the ascending speed of the stirring tool, the total number of the stirring lowering step and the stirring ascending step of the number of blade cuttings of the stirring tool in the predetermined section is equal to or more than the target value. In the case of, it is preferable that the ascending speed of the stirring tool is not changed.

Further, in the above-mentioned ground construction machine, in the procedure for calculating and setting the ascending speed of the stirring tool, the total number of the stirring lowering step and the stirring ascending step of the number of blade cuttings of the stirring tool in the predetermined section is currently increased. When it is determined that the speed exceeds the target value, it is preferable that the ascending speed of the stirring tool is not changed.

Since the present invention is configured as described above, the following effects are obtained.

Stable and smooth automatic transmission control is possible by considering not only the vertical relationship between the pressure of the pressure oil supplied to the hydraulic motor and the pressure reference value but also the time during which such a vertical relationship continues. In addition, it is possible to ensure that the number of blade cuttings by the stirring tool reaches the target value, and to create a high-quality columnar improved pile.

FIG. 1 is a schematic view showing the overall configuration of the ground construction machine 1 of the present invention. FIG. 2 is a schematic view showing the configurations of the hydraulic motor 81 and the rotary drive unit 8. FIG. 3 is a graph showing the relationship between the drive torque and the torque index on the output shaft of the hydraulic motor 81. FIG. 4 is a graph showing the relationship between the push-out volume of the hydraulic motor 81 and the drive torque on the output shaft. FIG. 5 is a diagram showing a pressure reference value P _s and a reference time _ts for automatic transmission control. FIG. 6 is a flowchart showing a processing procedure of automatic transmission control. FIG. 7 is a flowchart showing a processing procedure of the torque increase subroutine. FIG. 8 is a flowchart showing a processing procedure of the torque reduction subroutine. FIG. 9 is a flowchart showing a processing procedure of the torque setting subroutine. FIG. 10 is a block diagram showing a configuration for controlling the ascending / descending movement of the stirring tool 11. FIG. 11 is a diagram showing the up-and-down movement of the stirring tool 11 when performing the stirring step in the construction of the columnar improved pile. FIG. 12 is a diagram showing blade cutting securing control based on the divided unit intervals.

Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic view showing the overall configuration of the ground construction machine 1 of the present invention. The ground construction machine 1 has an endless track band ring 3 and is configured to be self-propelled. The leader 4 is a support for supporting and guiding the stirring tool 11. The leader 4 is capable of undulating from a state perpendicular to the ground to a horizontal state, and is configured to be able to turn together with the driver's cab 5. When moving / transporting the ground construction machine 1, the leader 4 is tilted horizontally and held horizontally on the upper part of the main body to move. The leader 4 is supported so as to be swingable around the fulcrum 9, and the hydraulic cylinder 6 is operated by the operation of the driver's cab 5 to perform the undulating operation of the leader 4.

A drive head 7 is provided so as to be movable in the vertical direction on the leader 4 with the leader 4 upright, and a hydraulic motor 81 (see FIG. 2) and a rotary drive unit 8 are fixedly arranged on the drive head 7. Has been done. The hydraulic motor 81 and the rotary drive unit 8 are for rotationally driving the rod 10 having the stirring tool 11 fixed to the tip side. The rod 10 is a hollow tubular member, and a ground improving agent or the like can be injected into the ground through the hollow portion inside. An excavator and a stirring tool 11 are fixed to the tip end side (lower side) of the rod 10.

The drive head 7 can move up and down on the reader 4 by a drive mechanism (not shown). When the drive head 7 is moved, the rod 10 and the stirring tool 11 are moved by the same amount together with the rotary drive unit 8. For example, a stirring tool 11 having an excavation portion on the lower end side and a stirring portion is used, and the rod 10 is lowered while being rotationally driven to perform excavation work and ground improvement work by stirring at the same time. At this time, the ground improving agent is ejected from the stirring tool and injected into the ground composition, and the ground composition is stirred to improve the ground. The ground improving agent is cement milk or the like, and is supplied through the hollow portion of the rod 10.

Further, the ground construction machine 1 may be attached with a tool dedicated to excavation such as an auger screw to perform only excavation work. In this way, when performing ground improvement work or excavation work with the ground construction machine 1, it is necessary to set the drive torque and rotation speed of the stirring tool 11 to appropriate values according to the state of the ground (soft, hard, etc.). be. For example, on hard ground, the drive torque of the stirring tool 11 must be increased (decrease in rotation speed), while on soft ground, the rotation speed must be increased (decrease in drive torque) to perform high-efficiency excavation work. Can be done.

FIG. 2 is a schematic view showing the configurations of the hydraulic motor 81 and the rotary drive unit 8. Here, the rotary drive unit 8 (see FIG. 1) includes a reduction mechanism 82, a spindle 83, and a chuck 84, and is for transmitting the rotational output of the hydraulic motor 81 to the rod 10 and the stirring tool 11 (see FIG. 1). Is. The speed reduction mechanism 82 decelerates the rotational output of the hydraulic motor 81 and transmits it to the spindle 83. The spindle 83 is rotatably supported with respect to the drive head 7.

A chuck 84 is fixed to the spindle 83, and the rod 10 can be gripped or released by the chuck 84. If the rod 10 is gripped by the chuck 84, the rod 10 is fixed to the spindle 83, and the rod 10 and the stirring tool 11 can be rotationally driven by the rotation of the spindle 83.

The hydraulic motor 81 can continuously change the push-out volume. The hydraulic motor 81 preferably has low rotational speed and high torque rotational output characteristics. As the hydraulic motor 81, for example, an eccentric radial piston motor can be used. In this eccentric radial piston motor, the central eccentric cylindrical cam and the output shaft are rotationally driven by pistons arranged radially with respect to the output shaft. If the eccentric amount of the eccentric cylindrical cam can be continuously adjusted, the push-out volume of the hydraulic motor can be continuously changed by changing the eccentric amount.

The drive control unit 85 supplies pressure oil from the hydraulic source to the hydraulic motor 81 to control the rotation of the hydraulic motor 81. The pressure P of the pressure oil supplied to the hydraulic motor 81 is detected by the pressure detector 86, and the detected value is sent to the drive control unit 85. The drive control unit 85 performs automatic shift control, that is, drive torque control of the stirring tool 11 according to the pressure P of the pressure oil supplied to the hydraulic motor 81.

Further, the drive control unit 85 can receive a signal from the encoder 87 to obtain the rotation speed of the output shaft of the hydraulic motor 81. The encoder 87 outputs a pulse signal according to the rotation angle of the output shaft of the hydraulic motor 81. That is, the encoder 87 can be used as a detector for the rotational speed of the hydraulic motor 81, and can also be used as a detector for the rotational position of the hydraulic motor 81. Further, since the stirring tool 11 is rotationally driven by the hydraulic motor 81, the rotation position and the rotation speed of the stirring tool 11 can be detected by the encoder 87.

The drive control unit 85 has a CPU 851 and a storage means 852 inside, and performs various information processing by the CPU 851. Further, the storage means 852 stores various data and programs necessary for drive control and information processing. Further, data and the like as a result of information processing are also stored in the storage means 852.

The drive control unit 85 can send an electric control signal to the hydraulic motor 81 to change and control the push-out volume of the hydraulic motor 81 to an arbitrary value within a predetermined range. The drive control unit 85 changes the push-out volume of the hydraulic motor 81 to control the change of the drive torque and the rotation speed of the output shaft. As a result, automatic shift control of the ground construction machine 1, that is, automatic control of changing and controlling the drive torque of the stirring tool 11 to an appropriate value is performed.

Next, the automatic shift control performed by the drive control unit 85 will be described. In the shift control method of the ground construction machine 1 of the present invention, the hydraulic motor 81 can continuously change the push-out volume. Therefore, as a shift control method, feedback control is also conceivable in which the push-out volume of the hydraulic motor 81 is continuously changed according to the load torque applied to the rod 10. However, in such a simple feedback control, due to a sudden torque fluctuation due to a change in the ground condition or the like, the push-out volume of the hydraulic motor is also largely changed and controlled, and the shift control may vibrate and become unstable. In addition, this may cause vibration in the tool itself, which may damage the tool and the ground construction machine.

Therefore, in the shift control method of the ground construction machine 1 of the present invention, the upper limit value and the lower limit value of the drive torque of the hydraulic motor 81 are set, and a plurality of drive torque values are set within the range including the upper limit value and the lower limit value. Then, the automatic shift control is performed by using those plurality of stepwise drive torque values. That is, in the shift control method of the present invention, instead of continuously changing the drive torque, a plurality of stepwise drive torque values are intentionally set for a continuous numerical range of the drive torque. Automatic shift control is performed using the stepwise drive torque value.

First, the storage means 852 inside the drive control unit 85 stores the maximum value T _max and the minimum value T _min of the drive torque of the hydraulic motor 81. This is the range of the drive torque obtained from the output characteristics of the hydraulic motor 81. The range of the drive torque of the hydraulic motor 81 that can be practically used is the section between the maximum value and the minimum value. That is, the value of the drive torque that can be normally used is not less than this minimum value T _min and not more than the maximum value T _max . The minimum value T _min and the maximum value T _max of the drive torque can be set in advance by the manufacturer of the ground construction machine 1. It may also allow the user to set or change their minimum T _min and maximum T _max .

Further, the drive torque of the hydraulic motor 81 is set to a limit value when the drive head 7 is located above the leader 4. Here, the upper part of the leader 4 means a position above a predetermined position above the leader 4. When the drive head 7 is located above the leader 4 at a predetermined position or higher, the drive torque of the hydraulic motor 81 is limited to a limit value or less.

This limit value is also stored in the storage means 852 inside the drive control unit 85. When the drive head 7 is located above the leader 4, if the drive torque of the hydraulic motor 81 becomes large, a large load is applied to the leader 4, the leader 4 is tilted, or in the worst case, the ground construction machine 1 falls over. There is also a risk that it will end up. Therefore, when the drive head 7 is located at a position equal to or higher than a predetermined position on the upper portion of the leader 4, it is desirable to limit the drive torque of the hydraulic motor 81 to a predetermined limit value or less.

This limit value is a value that enables safe construction work even when the drive head 7 is located above the leader 4. The limit is set by the manufacturer, but the user can change this limit. This limit value corresponds to the second upper limit value in the claims. That is, the limit value and the second upper limit value are the same.

The drive control unit 85 constantly monitors the position of the drive head 7, and when the drive head 7 is located above the leader 4, the drive torque of the hydraulic motor 81 is limited to this limit value (second upper limit value) or less. To. Even if the drive torque of the hydraulic motor 81 is changed by manual operation or automatic shift control, the drive torque increases only up to this limit value. When the drive head 7 is not in the upper position of the leader 4, the drive torque of the hydraulic motor 81 can be changed to a value exceeding this limit value.

Further, the upper limit value and the lower limit value of the drive torque when the automatic shift control or the manual setting of the drive torque is performed are stored in the storage means 852 inside the drive control unit 85. The automatic shift control and the manually set drive torque value are in the range between the lower limit value and the upper limit value (including the torque values at both ends). The lower limit value and the upper limit value of the drive torque are set by the user based on the condition and experience of the ground at the enforcement position. Naturally, the lower limit value and the upper limit value are set to the minimum value T _min or more and the maximum value T _max or less of the drive torque.

When the lower limit value and the upper limit value of the drive torque are set, the drive control unit 85 automatically divides the range of the lower limit value or more and the upper limit value or less into 10 equal parts and automatically obtains the drive torque value in 11 steps. Actually, the lower limit value of the drive torque is displayed as 0%, the upper limit value is displayed as 100%, and 11-step percentage display of 0%, 10%, 20%, 30%, 40%, ..., 100% is used. .. This percentage display will be called a torque index. At this time, assuming that the torque value whose torque index is displayed in x% is T (x), the _torque value T (x) is obtained by the following equation 1 with the lower limit value being _TL and the upper limit value being TU.

T (x) _{= TL +} (TU- _TL ) · x / 100 ... Equation 1
In the automatic shift control, an appropriate value of any of the 11 stages of drive torque values from 0% to 100% is automatically assigned according to the condition of the ground. The drive torque value of the hydraulic motor 81 is controlled so as to automatically transition to any of 11 stages of drive torque values according to the state of the ground. The specific procedure of automatic shift control will be described in detail later.

The upper limit value _{TU is a first upper limit value TU1 which} is a normal upper limit value, and a limit value of the drive torque of the hydraulic motor 81 when the drive head 7 is located above the leader 4. The second upper limit value T _U2 is stored. The second upper limit value T _U2 is usually set to a value smaller than the first upper limit value T _U1 .

When the drive head 7 is in a normal position, that is, a position lower than a predetermined position above the leader 4, the value of the first upper limit value _TU1 is set as the upper limit value _TU , and the above-mentioned 11-step drive torque value is obtained. When the drive head 7 is located above the leader 4, the value of the second upper limit value _TU2 is set as the upper limit value _TU , and the above-mentioned 11-step drive torque value is obtained.

FIG. 3 is a graph showing the relationship between the drive torque and the torque index on the output shaft of the hydraulic motor 81. The horizontal axis of the graph shows the torque index, and the vertical axis shows the drive torque. As shown in the graph, the lower limit value T _L and the upper limit value T _U of the drive torque are set between the minimum value T _min and the maximum value T _max of the drive torque.

Then, the torque index corresponding to the lower limit value _TL is set to 0%, and the torque index corresponding to the upper limit value _TU is set to 100%. Then, the range of the lower limit value or more and the upper limit value or less is divided into 10 equal parts, and 11-step torque indexes of 0%, 10%, 20%, 30%, 40%, ..., 100% are set. The operator of the ground construction machine 1 manually adjusts the drive torque and controls the automatic torque (automatic shift control) based on this torque index. The minimum value T _min and the maximum value T _max , the lower limit value _TL and the upper limit value _TU , the torque index, and the like of the drive torque are stored in the storage means 852 inside the drive control unit 85.

FIG. 4 is a graph showing the relationship between the push-out volume of the hydraulic motor 81 and the drive torque on the output shaft. The hydraulic motor 81 can continuously change the push-out volume, and the push-out volume is changed by a control signal from the drive control unit 85. When the pressure and the flow rate of the pressure oil supplied to the hydraulic motor 81 are substantially constant, the push-out volume of the hydraulic motor 81 and the drive torque have a substantially linear relationship as shown in the figure. If there is no leakage or loss of the hydraulic motor 81, the push-out volume is proportional to the drive torque.

The minimum value T _min and the maximum value T _max of the drive torque in the drive characteristics of the hydraulic motor 81 are determined by the minimum value Q _min and the maximum value Q _max of the push-out volume. The minimum value Q _min of the push-out volume corresponds to the minimum value T _min of the drive torque, and the maximum value Q _max of the push-out volume corresponds to the maximum value T _max of the drive torque. By continuously changing the push-out volume from the minimum value Q _min to the maximum value Q _max , the drive torque also continuously changes from the minimum value T _min to the maximum value T _max .

In order to change the drive torque of the hydraulic motor 81 to a desired value, the push-out volume corresponding to the drive torque may be obtained from the relationship shown in FIG. 4, and the push-out volume of the hydraulic motor 81 may be changed to the obtained value. The relationship between the drive torque and the push-out volume as shown in FIG. 4 is stored in the storage means 852 in the drive control unit 85 in the form of a calculation formula or a numerical table.

When the pressure and flow rate of the pressure oil supplied to the hydraulic motor 81 are maintained substantially constant, the drive torque of the output shaft of the hydraulic motor 81 is proportional to the push-out volume. Further, the rotation speed of the output shaft is inversely proportional to the drive torque. That is, even in a state where the pressure and the flow rate of the pressure oil are maintained substantially constant, the drive torque can be changed and controlled to an appropriate value by changing the push-out volume of the hydraulic motor.

As a supply source of the pressure oil supplied to the hydraulic motor 81, a pump driven by a prime mover such as an internal combustion engine is used. In general, it is desirable to use the prime mover in the vicinity of the most efficient rated output, and at this time, the pressure oil supply efficiency is also maximized. By performing the automatic torque control (automatic shift control) of the present invention, the pressure and flow rate of the pressure oil supplied to the hydraulic motor 81 can be kept substantially constant, and the prime mover of the pressure oil supply source can be operated with maximum efficiency. Therefore, the efficiency of tool drive can be improved.

Next, the automatic return control of the tool rotation in the present invention will be described. In the ground construction machine 1, the load from the ground may be too large and the rotation of the stirring tool 11 may be restrained and stopped. In this case, the rotation of the output shaft of the hydraulic motor 81 is also restrained and stops. At this time, even if the drive torque of the hydraulic motor 81 is increased to restart the drive of the stirring tool 11, the push-out volume of the hydraulic motor 81 may not change. The ground construction machine 1 of the present invention has a function of smoothly releasing the restrained state of the hydraulic motor 81 and returning it to the rotary drive state in such a case.

That is, when the rotation of the output shaft of the hydraulic motor 81 is restrained, it is detected and the supply of the pressure oil to the hydraulic motor 81 is automatically stopped for a certain period of time. Then, the push-out volume of the hydraulic motor 81 is changed to control the drive torque to be increased by one step. After that, the supply of the pressure oil to the hydraulic motor 81 is restarted, and the hydraulic motor 81 is returned to the rotational state. By changing the push-out volume while the pressure oil supply is stopped in this way, the push-out volume can be reliably changed.

It is considered that this is because by stopping the supply of the pressure oil, the excessive force acting on each part of the hydraulic motor 81 at the time of restraint is removed, and the push-out volume changing mechanism operates smoothly. By automatically returning the hydraulic motor 81 from the rotation restraint state to the rotation state in this way, the operator of the ground construction machine 1 automatically drives the rotation from the rotation restraint state to the normal rotation without performing complicated operations. It can be returned to the state.

Next, the automatic shift control and the automatic return control as described above in the present invention will be described more specifically. The drive control unit 85 performs automatic shift control according to the pressure P of the pressure oil supplied to the hydraulic motor 81. The drive control unit 85 stores a plurality of pressure reference values for performing automatic shift control as compared with the pressure P. That is, the pressure reference value (upper reference value) used to determine whether to increase the torque value and the pressure reference value (lower reference value) used to determine whether to decrease the torque value are used respectively. It is memorized according to the torque state. Further, the reference time, which is the reference time for the transition condition of the torque value to continue, is stored corresponding to each torque state.

The drive control unit 85 compares the pressure P with the pressure reference value (upper reference value), and increases the drive torque by one step when the state in which the pressure P is equal to or higher than the upper reference value continues for a reference time or longer. Further, the drive control unit 85 compares the pressure P with the pressure reference value (lower reference value), and reduces the drive torque by one step when the state where the pressure P is equal to or less than the lower reference value continues for the reference time or more. Let me. When the pressure P is larger than the lower reference value and smaller than the upper reference value, the drive torque is maintained in the current state.

FIG. 5 is a diagram showing an example of a set value of a pressure reference value P _s and a reference time _ts for automatic transmission control. The set values of the pressure reference value P _s and the reference time t _s are stored in the storage means 852 inside the drive control unit 85. In the automatic shift control, the drive torque of the hydraulic motor 81 is automatically selected from the torque values corresponding to the 11-step torque index and set so as to have an appropriate torque value. In addition, even if the ground condition changes during construction, the drive torque is automatically changed to an appropriate drive torque according to the ground condition.

Here, the index number n is defined for each of the torque indexes 0% to 100% in 11 stages of the drive torque. That is, a torque index of 0% is associated with an index number of 0, a torque index of 10% is associated with an index number of 1, and a torque index of 20% is associated with an index number of 2. Similarly, the number of indexes: 3 to 10 is associated with the torque index of 30% to 100%. The torque index of 100% corresponds to the number of indexes: 10.

Here, the operation of increasing the drive torque by one step is the same as shifting from the drive torque corresponding to the index number n to the drive torque corresponding to the index number n + 1. Further, the operation of reducing the drive torque by one step is the same as shifting from the drive torque corresponding to the index number n to the drive torque corresponding to the index number n-1.

The pressure reference value P _s and the reference time t _s are set for each of the drive torque transfer operations. When the current drive torque state is the torque value corresponding to the index number n, the pressure reference value (upper reference value) used for determining whether to increase the torque value is expressed as P _s (n, n + 1). .. Further, the reference time with respect to the pressure reference value is expressed as t _s (n, n + 1). The pressure reference value (lower reference value) used to determine whether to reduce the torque value is expressed as P _s (n, n-1). Further, the reference time with respect to the pressure reference value is expressed as t _s (n, n-1).

Here, the pressure reference value P _s (n, n + 1) and the reference time t _s (n, n + 1) are set for n = 0 to 9, and the pressure reference value P _s (n, n-1) and the reference time are set. t _s (n, n-1) is set for n = 1 to 10.

It should be noted that these pressure reference values P _s and reference time t _s are set for each of the 11-step drive torque values with respect to the first upper limit value _TU1 which is the upper limit value at the normal time, and at the same time, drive. It is also set for each of the 11-step drive torques with respect to the second upper limit value _TU2 , which is the upper limit value when the head 7 is located above the leader 4. That is, two types of tables as shown in FIG. 5 are stored and used properly according to the position of the drive head 7. The pressure reference value and reference time table as shown in FIG. 5 is stored in the storage means 852 in the drive control unit 85.

Here, the control when the drive head 7 is located above the leader 4 is performed by setting the drive torque in 11 steps with the upper limit value of the drive torque as the second upper limit value. It is not limited to the control. When the drive head is located above the reader, the drive torque may simply not be set to a value exceeding the limit value.

Next, specific control procedures for automatic shift control and automatic return control will be described with reference to the flowcharts of FIGS. 6 to 9. The flowcharts of FIGS. 6 to 9 show the contents of the program executed by the drive control unit 85. FIG. 6 is a flowchart showing a processing procedure of automatic transmission control. When the operation to start the rotary drive of the stirring tool 11 is performed while the shift control mode of the ground construction machine 1 is set to the automatic shift mode, the procedure shown in the flowchart of FIG. 6 is started.

In step 101, the rotary drive of the hydraulic motor 81 is started. When the construction of the ground is started by this, the automatic shift control is executed by repeating the processes from the procedure 102 to the procedure 106. That is, the drive torque of the hydraulic motor 81 is changed and controlled to an appropriate value according to the state of the ground and the load on the stirring tool 11.

Further, in the procedure 101, the initial torque of the automatic shift control is set. The initial torque is the initial value of the drive torque at the start of automatic transmission control. The operator can set an arbitrary initial value from the torque index of 0% to 100%. If the operator has not set an initial value, a torque value corresponding to a torque index of 50% is set as a default value. Then, the value of the index number corresponding to the initial value is substituted into the variable n representing the index number of the current drive torque. For example, when the initial value is a torque index of 50%, 5 is substituted for the variable n representing the number of current drive torque indexes.

In step 102, the position of the drive head 7 on the reader 4 is detected. Next, in step 103, the drive torque and the torque index are set, and the pressure reference value and the reference time are set. In these settings, either the first upper limit value _TU1 or the second upper limit value _TU2 is set as the upper limit value _TU according to the position of the drive head 7 on the reader 4, and thereby corresponds to each torque index. The drive torque value in 11 steps is obtained. Further, the pressure reference value and the reference time corresponding to the position of the drive head 7 are set to be used.

Further, in the procedure 103, when the position of the drive head 7 changes from the normal position to the upper position, or when the position changes from the upper position to the normal position, the index number is corrected. This is because the value of the drive torque corresponding to the number of indexes differs between the case where the position of the drive head 7 is the normal position and the case where the position is the upper position. When the position of the drive head 7 is changed between the normal position and the upper position, first, the drive torque corresponding to the number of indexes before the position change is obtained, and the drive torque closest to the drive torque is 11 after the position change. Select from the drive torques of the stages. Then, the number of indexes corresponding to the selected drive torque is assigned to the variable n. The variable n represents the number of indexes of the current drive torque.

The next step 104 performs a process of calling the torque increase subroutine. The torque increase subroutine executes the processing procedure shown in FIG. 7, and performs processing for increasing the drive torque according to each condition in the automatic transmission control. This torque increase subroutine will be described in detail later.

After returning to the caller from the torque increase subroutine, the next step is step 105. Step 105 performs a process of calling the torque reduction subroutine. The torque reduction subroutine executes the processing procedure shown in FIG. 8, and performs processing for reducing the drive torque according to each condition in the automatic transmission control. This torque reduction subroutine will be described in detail later. After returning from the torque reduction subroutine to the caller, the process proceeds to step 106.

In step 106, it is determined whether or not to continue the automatic shift control. When the shift control mode of the ground construction machine 1 is changed to the manual shift mode, or when the ground construction is completed and the rotary drive of the stirring tool 11 is stopped, the process proceeds from step 106 to the "No" side and the automatic shift control is terminated. do. If there is no such end operation of the automatic shift control, the process proceeds from step 106 to the “Yes” side, returns to step 102, and repeats the processes of steps 102 to 106.

FIG. 7 is a flowchart showing a processing procedure of the torque increase subroutine. The torque increase subroutine performs a process of increasing the drive torque of the hydraulic motor 81 according to each condition in the automatic transmission control. When the torque increase subroutine is called, first, in step 201, it is determined whether or not the value of the currently set index number n of the drive torque is 10. When the value of the index number n is 10, the index number n = 10 corresponds to the upper limit value of the drive torque, and the drive torque cannot be increased any more. Therefore, the processing of the torque increase subroutine is terminated and the caller returns. ..

If the value of the index number n is not 10 (in the case of 0 to 9), the process proceeds from step 201 to step 202. In step 202, the timer built in the drive control unit 85 is reset and the time measurement is started. This timer measures the time during which the pressure P of the pressure oil supplied to the hydraulic motor 81 continues to be equal to or higher than the pressure reference value P _s (n, n + 1).

Next, in step 203, the detected value of the pressure P of the pressure oil supplied to the hydraulic motor 81 is compared with the pressure reference value P _s (n, n + 1). As the pressure reference value P _s (n, n + 1), the one corresponding to the index number n of the current drive torque is selected from the table as shown in FIG. If the pressure P is equal to or greater than the pressure reference value P _s (n, n + 1), the process proceeds to the next step 204. If not, the processing of the torque increase subroutine is terminated and the caller returns.

In the next procedure 204, the time t being measured by the timer is compared with the reference time t _s (n, n + 1). As the reference time t _s (n, n + 1), the one corresponding to the index number n of the current drive torque is selected from the table as shown in FIG. If the time t is equal to or greater than the reference time t _s (n, n + 1), the process proceeds to the procedure 205, otherwise the process returns to the procedure 203, and the procedure 203 to the procedure 204 are repeated.

After all, in the procedure 203 and the procedure 204, it is determined whether or not the state in which the pressure P is the pressure reference value P _s (n, n + 1) or more continues for the reference time t _s (n, n + 1) or more. If it continues for the reference time t _s (n, n + 1) or more, it proceeds to step 205, and if it does not continue, it ends the processing of the torque increase subroutine and returns to the caller. That is, the drive torque is not increased unless the state in which the pressure P is equal to or higher than the pressure reference value P _s (n, n + 1) continues for the reference time t _s (n, n + 1) or longer.

In step 205, a value (n + 1) is assigned to the variable m representing the number of indexes. Since the drive torque of the hydraulic motor 81 is set by the value of this variable m, this substitution indicates that the drive torque is increased by one step. The next step 206 performs a process of calling the torque setting subroutine. The torque setting subroutine executes the processing procedure shown in FIG. 9, and performs processing for setting the drive torque of the hydraulic motor 81 by the value of the variable m. This torque setting subroutine will be described in detail later. When the caller returns from the torque setting subroutine, the processing of this torque increase subroutine is terminated and the caller returns.

FIG. 8 is a flowchart showing a processing procedure of the torque reduction subroutine. The torque reduction subroutine performs a process of reducing the drive torque of the hydraulic motor 81 according to each condition in the automatic transmission control. When the torque reduction subroutine is called, first, in step 301, it is determined whether or not the value of the currently set index number n of the drive torque is 0. When the value of the index number n is 0, the index number n = 0 corresponds to the lower limit value of the drive torque, and the drive torque cannot be reduced any more. Therefore, the processing of the torque reduction subroutine is terminated and the caller returns.

If the value of the index number n is not 0 (1 to 10), the process proceeds from step 301 to step 302. In step 302, the timer built in the drive control unit 85 is reset and the time measurement is started. This timer measures the duration of time that the pressure P of the pressure oil supplied to the hydraulic motor 81 is equal to or less than the pressure reference value P _s (n, n-1).

Next, in the procedure 303, the detected value of the pressure P of the pressure oil supplied to the hydraulic motor 81 is compared with the pressure reference value P _s (n, n-1). As the pressure reference value P _s (n, n-1), the one corresponding to the index number n of the current drive torque is selected from the table as shown in FIG. If the pressure P is equal to or less than the pressure reference value P _s (n, n-1), the process proceeds to the next step 304. If not, the process of the torque reduction subroutine is terminated and the caller returns.

In the next procedure 304, the time t being measured by the timer is compared with the reference time t _s (n, n-1). As the reference time t _s (n, n-1), the one corresponding to the index number n of the current drive torque is selected from the table as shown in FIG. If the time t is equal to or longer than the reference time t _s (n, n-1), the process proceeds to the procedure 305. If not, the process returns to the procedure 303, and the procedure 303 to the procedure 304 are repeated.

After all, in steps 303 and 304, it is determined whether or not the state in which the pressure P is equal to or less than the pressure reference value P _s (n, n-1) continues for the reference time t _s (n, n-1) or more. To. If it continues for the reference time t _s (n, n-1) or more, the process proceeds to step 305, and if it does not continue, the processing of the torque reduction subroutine is terminated and the caller returns. That is, the drive torque is not reduced unless the state in which the pressure P is equal to or less than the pressure reference value P _s (n, n-1) continues for the reference time _ts (n, n-1) or more.

In step 305, the value (n-1) is assigned to the variable m representing the number of indexes. Since the drive torque of the hydraulic motor 81 is set by the value of this variable m, this substitution indicates that the drive torque is reduced by one step. The next step 306 performs a process of calling the torque setting subroutine. The torque setting subroutine executes the processing procedure shown in FIG. 9, and performs processing for setting the drive torque of the hydraulic motor 81 by the value of the variable m. When the caller returns from the torque setting subroutine, the processing of this torque reduction subroutine is terminated and the caller returns.

FIG. 9 is a flowchart showing a processing procedure of the torque setting subroutine. This torque setting subroutine performs a process of setting the drive torque of the hydraulic motor 81 by the value of the variable m representing the number of indexes. In addition, this torque setting subroutine also incorporates a procedure for automatic return control from the rotation restraint state to the rotation state. Note that this torque setting subroutine is used not only for automatic shift control in the automatic shift mode, but also for manual setting of the drive torque value in the manual shift mode.

When the torque setting subroutine is called, first, in step 401, it is determined whether or not the automatic return control from the rotation restraint state to the rotation state is turned on. If the automatic return control is on, the process proceeds to step 402, and if the automatic return control is off, the process proceeds to step 410. That is, when the automatic return control is turned off on the operation panel, the automatic return control is not performed, and the drive torque of the hydraulic motor 81 is simply set according to the value of the variable m.

In step 410, in order to set the drive torque corresponding to the value of the variable m representing the number of indexes, first, the push-out volume corresponding to the drive torque is obtained from the relationship of FIG. Then, the push-out volume of the hydraulic motor 81 is set to the obtained volume. Further, at the same time as setting the push-out volume of the hydraulic motor 81, the value of the variable m is substituted into the variable n representing the index number of the current drive torque. As a result, the number of indexes of the changed drive torque is set in the variable n. After step 410, the processing of the torque setting subroutine is terminated and the caller returns.

In step 401, if the automatic return control is on, the process proceeds to step 402, and it is determined whether or not the value of the variable m is larger than the value of the variable n. If the value of the variable m is larger, the drive torque is increased, and the process proceeds to step 403 to set the drive torque accompanied by the automatic return control. If this is not the case, the drive torque is not increased, so the process proceeds to step 410, and the drive torque of the hydraulic motor 81 is simply set according to the value of the variable m without performing the automatic return control. That is, the automatic return control is performed only when an instruction to increase the drive torque is given.

In step 403, the timer built in the drive control unit 85 is reset and the time measurement is started. By this timer, the rotation speed R of the output shaft of the hydraulic motor 81 is equal to or less than the predetermined restraint reference speed R _r , and the pressure P of the pressure oil supplied to the hydraulic motor 81 is equal to or higher than the restraint pressure reference value P _r . Measure how long the condition lasts.

Here, the restraint reference speed R _r is a reference value of the rotation speed of the output shaft of the hydraulic motor 81 for determining that the stirring tool 11 is in the rotation restraint state. Further, the restraint pressure reference value _Pr is a reference value of the pressure of the pressure oil supplied to the hydraulic motor 81 for determining that the stirring tool 11 is in the rotation restraint state. That is, a predetermined state is that the rotation speed R of the output shaft of the hydraulic motor 81 is equal to or less than the restraint reference speed R _r , and the pressure P of the pressure oil supplied to the hydraulic motor 81 is equal to or higher than the restraint pressure reference value P _r . If it is continuous for the restraint reference time _tr or more, it is determined that the stirring tool 11 is in the rotation restraint state.

First, in procedure 404, it is determined whether or not the rotation speed R of the output shaft of the hydraulic motor 81 is equal to or less than the restraint reference speed R _r . If it is the restraint reference speed R _r or less, the process proceeds to the procedure 405. If not, the process proceeds to the procedure 410, and the automatic return control is not performed and the drive torque of the hydraulic motor 81 is simply set according to the value of the variable m. Information on the rotation speed R of the output shaft of the hydraulic motor 81 is obtained from the detection signal from the encoder 87. The actual value of the restraint reference speed R _r is about 1 [rotation / minute]. The value of this constraint reference speed R _r can also be set by the user.

Next, in the procedure 405, it is determined whether or not the pressure P of the pressure oil supplied to the hydraulic motor 81 is equal to or higher than the restraint pressure reference value _Pr . If it is the restraint pressure reference value _Pr or more, the process proceeds to the procedure 406. If not, the process proceeds to the procedure 410, and the automatic return control is not performed and the drive torque of the hydraulic motor 81 is simply set according to the value of the variable m. The restraint pressure reference value P _r is set to a value close to the maximum value of the pressure oil supplied to the hydraulic motor 81. When rotation is constrained, the near maximum value of the pressure oil supply pressure is detected.

Next, in step 406, the time _t being measured by the timer is compared with the constraint reference time tr. The actual value of this constraint reference time _tr is about 1 second. The value of this constraint reference time _tr can also be set by the user. If the time _t is equal to or greater than the constraint reference time tr, the process proceeds to the procedure 407, otherwise the process returns to the procedure 404, and the procedure 404 to the procedure 406 are repeated.

After all, in steps 404 to 406, the rotation speed R of the output shaft of the hydraulic motor 81 is equal to or less than the restraint reference speed R _r , and the pressure P of the pressure oil supplied to the hydraulic motor 81 is the restraint pressure reference value P. It is determined whether or not the state of _r or more continues for the restraint reference time _tr or more. If it continues for the restraint reference time _tr or more, it proceeds to the procedure 407, and if it does not continue, it proceeds to the procedure 410, and the drive torque of the hydraulic motor 81 is simply set according to the value of the variable m without performing the automatic return control. That is, if the rotation restraint state does not continue for the predetermined restraint reference time _tr or more, the automatic return control is not performed.

In step 407, the supply of the pressure oil to the hydraulic motor 81 is stopped, and the rotary drive of the hydraulic motor 81 is turned off. The stop time of this rotation drive is a predetermined time set in advance, and specifically, it is about 0.1 second. The value of this downtime is also user-configurable. After turning off the rotary drive of the hydraulic motor 81 in step 407, immediately proceed to step 408 to set the drive torque, and when the predetermined stop time elapses, turn on the rotary drive of the hydraulic motor 81 again in step 409. ..

In step 408, in order to set the drive torque corresponding to the value of the variable m representing the number of indexes, the push-out volume corresponding to the drive torque is obtained, and the push-out volume of the hydraulic motor 81 is set to the obtained value. Further, at the same time as setting the push-out volume of the hydraulic motor 81, the value of the variable m is substituted into the variable n representing the index number of the current drive torque. As a result, the number of indexes of the changed drive torque is set in the variable n.

In the next step 409, the rotary drive of the hydraulic motor 81 is turned on again after the predetermined stop time has elapsed. After step 409, the processing of the torque setting subroutine is terminated and the caller returns. In the above torque setting subroutine, the drive torque of the hydraulic motor 81 is set by the value of the variable m representing the number of indexes, and if the automatic return control is on, the automatic return control from the rotation restraint state to the rotation state is performed. With the automatic return control, it is possible to automatically return from the rotation restraint state to the rotation state without the operator performing a particularly complicated operation.

By performing the automatic shift control by the processing procedure as shown in FIGS. 6 to 9, the stability of the automatic shift control can be significantly improved. That is, stable and smooth automatic transmission control is possible by considering not only the vertical relationship between the pressure of the pressure oil supplied to the hydraulic motor and the pressure reference value but also the time during which such a vertical relationship continues. ing. In addition, the number of gears can be arbitrarily increased as needed while using only one hydraulic motor, which also enables stable and smooth automatic transmission control.

Further, the upper limit value and the lower limit value of the drive torque of the tool can be arbitrarily set, and the construction can be carried out safely and appropriately according to the condition of the ground and the construction contents. In addition, by performing the automatic shift control as described above, the pressure and flow rate of the pressure oil supplied to the hydraulic motor can be kept almost constant, and the prime mover of the pressure oil supply source can be operated with maximum efficiency. The efficiency of driving can be improved.

Then, even if the rotation of the tool is constrained and the rotation is constrained, it is possible to automatically return from the rotation restraint state to the rotation restraint state. Furthermore, since stable and smooth automatic transmission control is possible with only one hydraulic motor, the manufacturing cost of the ground construction machine can be significantly reduced.

Next, the ascending / descending movement control of the stirring tool 11 will be described. FIG. 10 is a block diagram showing a configuration for controlling the ascending / descending movement of the stirring tool 11. The drive head 7 (see FIG. 2) is driven by the elevating drive unit 70 and can move up and down on the reader 4. When the drive head 7 is moved, the rod 10 and the stirring tool 11 are moved by the same amount together with the rotary drive unit 8. The elevating control unit 71 controls the elevating drive unit 70 to set and adjust the elevating position and elevating speed of the stirring tool 11.

FIG. 11 is a diagram showing the up-and-down movement of the stirring tool 11 when performing the stirring step in the construction of the columnar improved pile. The vertical axis shows the depth [m] from the ground surface, and the horizontal axis shows the time [s]. The stirring tool 11 is rotationally driven and descends from a depth of 0 m at a predetermined descending speed while stirring. When the deepest position of the stirring step (position at a depth of 5 m in FIG. 11) is reached, the movement of the stirring tool 11 starts to rise, and the stirring tool 11 is raised at a predetermined rising speed.

For columnar improved piles, a target value for the number of blade cuttings is set for each unit length. Here, the number of times of blade cutting represents the number of times that the stirring blade of the stirring tool passes, and is obtained by multiplying the number of rotations of the stirring tool by the number of blades. In order to ensure the quality of columnar improved piles, it is important that the number of blade cuttings reaches this target value. In the ground construction machine 1 of the present invention, it is possible to perform blade cutting securing control so that the number of blade cuttings reliably reaches the target value.

The operator of the ground construction machine 1 can select whether or not to perform the blade cutting securing control, and the blade cutting securing control is switched on and off on the operation panel of the ground construction machine 1. When the blade cutting securing control is off, the control for reaching the target value for the number of blade cuttings is not performed, and the stirring tool 11 is moved up and down according to a preset moving speed. When the blade cutting securing control is on, the ascending movement speed of the stirring tool 11 is controlled so that the number of blade cuttings reaches the target value. The specific contents of the blade cutting securing control will be described below.

As shown in FIG. 11, the columnar improved pile is divided into unit sections for each unit length, and a target value for the number of blade cuttings is set for each unit section. The target value may be different for each unit interval or may be the same value. In the example shown in FIG. 11, each unit interval is a numerical value of depth [0 to 1.0], [1.0 to 2.0], [2.0 to 3.0], [3.0 to 4. It is 0] and [4.0 to 5.0].

In the ground construction machine 1 of the present invention, each unit section is divided into four sections having a length of 0.25 m in order to more accurately execute various controls such as blade cutting securing control, and the divided unit sections are divided into four sections. Control is performed based on. FIG. 12 is a diagram showing blade cutting securing control based on the divided unit intervals. FIG. 12 shows an enlarged unit section having a depth [2.0 to 3.0], and this unit section is a divided unit section divided into four as described above.

Here, it is assumed that the stirring tool 11 is in the ascending process and is in the section of the depth [2.50 to 2.75], and the current position of the stirring tool 11 is X. For generalization, the upper end position of this section is H and the lower end position is L. The number of blade cuttings when the stirring tool 11 passes through this section [HL] in the descending step is counted and stored by the elevating control unit 71. The number of blade cuttings = the number of rotations of the stirring tool x the number of blades.

The number of blade cuttings in the descending process in this section is Kd, and the number of blade cuttings up to the current position in the ascending process is Kx. The target value for the number of blade cuts in a unit interval is evenly distributed to each division unit interval. That is, the target value of the division unit interval is 1/4 of the target value of the unit interval. The target value of this division unit interval is Km. Assuming that the remaining number of blade cuttings required by the stirring tool 11 in the remaining ascending step of this section is Kz, Kz is expressed by the following equation.
Kz = Km-Kd-Kx ... Equation 2

Assuming that the rotation speed of the stirring tool 11 corresponding to the remaining number of blade cuttings Kz is Nz and the number of blades of the stirring tool 11 is h, Nz is expressed by the following equation.
Nz = Kz / h
Further, assuming that the rotation speed of the current stirring tool 11 is R and the time required for the stirring tool 11 to rotate at the rotation speed Nz is t, t is expressed by the following equation.
t = Nz / R

The remaining distance in this section of the ascending step of the stirring tool 11 is (XH). Assuming that the ascending speed of the stirring tool 11 required for the number of blade cuttings to reach the target value is Vz, Vz is expressed by the following equation.
Vz = (X-H) / t ... Equation 3
That is, if the ascending speed of the stirring tool 11 is set to the speed Vz calculated by the equation 3, the number of blade cuttings in this section reaches the target value.

However, when the speed Vz calculated by Equation 3 is larger than the current rising speed, it is desirable to continue the stirring step at the current speed without changing the rising speed. This is because if the ascending speed is increased, the number of blade cuttings decreases, so it is judged that the number of blade cuttings exceeds the target value even at the current ascending speed. Even if the number of blade cutting exceeds the target value, there is no particular problem, and it is preferable that the ascending speed is not changed because the control is stable.

Similarly, even when the remaining number of blade cuttings Kz is 0 or a negative value in the calculation of Equation 2, it is desirable to continue the stirring step at the current speed without changing the ascending speed. When Kz is 0, it indicates that the number of blade cuttings has reached the target value, and when Kz is a negative value, it indicates that the number of blade cuttings has already exceeded the target value. In this case as well, there is no particular problem, and the stirring process without changing the ascending speed may be continued.

When the blade cutting securing control is on, the elevating control unit 71 performs the following operations. When the stirring tool 11 is in the stirring / lowering step, the ascending / descending control unit 71 counts and stores the number of blade cuttings in each of the division unit sections. When the stirring tool 11 shifts to the stirring ascending process, the elevating control unit 71 performs calculations such as those in the above equations 2 to 3 for the stirring tool 11 in the current section, and the target number of blade cuttings is performed at the current ascending speed. If it is determined that the value is not reached, the ascending speed of the stirring tool 11 is changed to the speed Vz calculated by the equation 3 so that the number of blade cuttings can reach the target value.

The elevating control unit 71 repeats the above calculation in each division unit interval, and constantly determines whether or not the number of blade cuttings reaches the target value. Therefore, even if there is a non-uniform layer in the section or the rotation speed of the stirring tool 11 changes due to automatic shifting, a new climbing speed is calculated based on those fluctuations and the climbing speed is changed. It is possible to ensure that the number of blade cuttings reaches the target value.

As described above, according to the present invention, stable and smooth automatic transmission control is possible, and by arbitrarily setting the upper limit value and the lower limit value of the drive torque of the tool, the condition of the ground and the construction contents Therefore, the construction can be carried out safely and appropriately. Then, the number of blade cuttings by the stirring tool can be surely reached the target value, and a high quality columnar improved pile can be created.

In the above description of the embodiment, the range between the lower limit value and the upper limit value of the drive torque in the automatic transmission control is divided into 10 equal parts to set the drive torque value in 11 steps. The drive torque value may be set to any number of stages, not limited to the stage. For example, it is possible to set a drive torque of 21 steps, 41 steps, or the like. Further, the number of driving torque steps may be less than 11 steps.

According to the present invention, a ground construction machine capable of producing high-quality columnar improved piles by executing stable and smooth automatic shift control and ensuring that the number of blade cuttings by a stirring tool reaches a target value is provided. Can be provided.

1 Ground construction machine 3 Track band ring 4 Leader 5 Driver's cab 6 Hydraulic cylinder 7 Drive head 8 Rotation drive unit 9 Support point 10 Rod 11 Stirring tool 70 Elevation drive unit 71 Elevation control unit 81 Hydraulic motor 82 Deceleration mechanism 83 Spindle 84 Chuck 85 Drive Control unit 86 Pressure detector 87 Encoder 851 CPU
852 Memory means

Claims (6)

A stirring tool (11) equipped with a stirring blade and a spout for a ground improving agent for creating a columnar columnar improving pile in the ground, and a stirring tool (11).
A hollow tubular rod (10) to which the stirring tool (11) is fixed to the lower end,
An elevating drive unit (70) that drives the stirring tool (11) in a descending or ascending direction with respect to the ground.
The hydraulic motor (81), which can continuously change the push-out volume and rotationally drives the stirring tool (11),
A rotation detector (87) for detecting the rotation position or rotation speed of the stirring tool (11), and
It is a control method in a ground construction machine provided with a pressure detector (86) for detecting the pressure of a fluid supplied to the hydraulic motor (81).
A procedure for setting an upper limit value and a lower limit value of the drive torque actually used for the rotary drive of the stirring tool (11) within the range of the drive torque that can be generated by the hydraulic motor (81).
A procedure for setting a plurality of drive torques including the lower limit value and the upper limit value in the range of the lower limit value or more and the upper limit value or less, and
A procedure for obtaining a plurality of push-out volumes of the hydraulic motor (81) corresponding to a plurality of set drive torques, and a procedure for obtaining a plurality of push-out volumes.
A procedure for setting a reference value of the pressure for shifting from a push-out volume other than the lower limit volume corresponding to the lower limit value to a push-out volume one step smaller for each push-out volume as a lower reference value, and a procedure.
A procedure for setting a reference value of the pressure for shifting from the push-out volume other than the upper limit volume corresponding to the upper limit value to a push-out volume one step larger for each push-out volume as an upper reference value, and a procedure.
A procedure for setting a reference time for each transition from the push-out volume to an adjacent push-out volume, and
A procedure for shifting to a one-step smaller push-out volume when the hydraulic motor (81) is in a predetermined push-out volume other than the lower limit value and the pressure is continuously below the lower reference value for a reference time or longer. When,
A procedure for shifting to a one-step larger push-out volume when the hydraulic motor (81) is in a predetermined push-out volume other than the upper limit value and the pressure is continuously equal to or higher than the upper reference value for a reference time or longer. When,
A procedure for counting and storing the number of blade cuttings of the stirring tool (11) in a predetermined section of a predetermined length of the columnar improved pile in the stirring lowering step of stirring while lowering the stirring tool (11).
In the stirring ascending step of agitating while raising the stirring tool (11), the current position of the stirring tool (11), the number of blade cuttings during ascending in the predetermined section, and the current stirring tool (11). From the rotation speed, the predetermined section of the stirring tool (11) so that the total number of the stirring lowering step and the stirring rising step of the number of blade cuttings of the stirring tool (11) in the predetermined section does not fall below the target value. A control method in a ground construction machine having a procedure for calculating and setting the ascending speed in the remaining section of . The control method for the ground construction machine according to claim 1.
In the procedure for calculating and setting the ascending speed of the stirring tool (11), the total number of the stirring lowering step and the stirring raising step of the number of blade cuttings of the stirring tool (11) in the predetermined section is equal to or more than the target value. In this case, the control method in the ground construction machine that does not change the ascending speed of the stirring tool (11). The control method for the ground construction machine according to claim 2.
In the procedure for calculating and setting the ascending speed of the stirring tool (11), the total number of the stirring lowering step and the stirring ascending step of the number of blade cuttings of the stirring tool (11) in the predetermined section is targeted at the current ascending speed. A control method in a ground construction machine that does not change the ascending speed of the stirring tool (11) when it is determined that the value is equal to or higher than the value. A stirring tool (11) equipped with a stirring blade and a spout for a ground improving agent for creating a columnar columnar improving pile in the ground, and a stirring tool (11).
A hollow tubular rod (10) to which the stirring tool (11) is fixed to the lower end,
An elevating drive unit (70) that drives the stirring tool (11) in a descending or ascending direction with respect to the ground.
The hydraulic motor (81), which can continuously change the push-out volume and rotationally drives the stirring tool (11),
A rotation detector (87) for detecting the rotation position or rotation speed of the stirring tool (11), and
A rotary drive unit (82 to 84) for transmitting the rotational output of the hydraulic motor (81) to the stirring tool (11), and
A pressure detector (86) for detecting the pressure of the fluid supplied to the hydraulic motor (81), and
A drive control unit (85) that controls the push-out volume of the hydraulic motor (81) to drive and control the hydraulic motor (81) to generate an appropriate drive torque.
It has an elevating control unit (71) that controls the elevating movement of the stirring tool (11) via the elevating drive unit (70).
The drive control unit (85) is provided with a storage means (852) for storing information.
The storage means (852) is
Within the range of the drive torque that can be generated by the hydraulic motor (81), the upper limit value and the lower limit value of the drive torque actually used for the rotary drive of the stirring tool (11) are stored, and the lower limit value or more and the said Within the range below the upper limit value, a plurality of drive torques including the lower limit value and the upper limit value are stored.
The plurality of push-out volumes of the hydraulic motor (81) corresponding to the plurality of set drive torques are stored.
The reference value of the pressure for shifting from the push volume other than the lower limit value to the push volume one step smaller is stored as a lower reference value for each push volume, and 1 from the push volume other than the upper limit value. The reference value of the pressure for shifting to a step larger push-out volume is stored as an upper reference value for each push-out volume, and is stored.
The reference time for transitioning from the push-out volume to the adjacent push-out volume is stored for each shift.
Further, the drive control unit (85)
A procedure for shifting to a one-step smaller push-out volume when the hydraulic motor (81) is in a predetermined push-out volume other than the lower limit value and the pressure is continuously below the lower reference value for a reference time or longer. When,
A procedure for shifting to a one-step larger push-out volume when the hydraulic motor (81) is in a predetermined push-out volume other than the upper limit value and the pressure is continuously equal to or higher than the upper reference value for a reference time or longer. Is what you do
The elevating control unit (71)
A procedure for counting and storing the number of blade cuttings of the stirring tool (11) in a predetermined section of a predetermined length of the columnar improved pile in the stirring lowering step of stirring while lowering the stirring tool (11).
In the stirring ascending step of agitating while raising the stirring tool (11), the current position of the stirring tool (11), the number of blade cuttings during ascending in the predetermined section, and the current stirring tool (11). From the rotation speed, the predetermined section of the stirring tool (11) so that the total number of the stirring lowering step and the stirring rising step of the number of blade cuttings of the stirring tool (11) in the predetermined section does not fall below the target value. A ground construction machine that executes the procedure of calculating and setting the ascending speed in the remaining section of . The ground construction machine according to claim 4.
In the procedure for calculating and setting the ascending speed of the stirring tool (11), the total number of the stirring lowering step and the stirring raising step of the number of blade cuttings of the stirring tool (11) in the predetermined section is equal to or more than the target value. In this case, the ground construction machine does not change the ascending speed of the stirring tool (11). The ground construction machine according to claim 5.
In the procedure for calculating and setting the ascending speed of the stirring tool (11), the total number of the stirring lowering step and the stirring ascending step of the number of blade cuttings of the stirring tool (11) in the predetermined section is targeted at the current ascending speed. A ground construction machine that does not change the ascending speed of the stirring tool (11) when it is determined that the value is equal to or higher than the value.

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