JP6982158B2 - Hydraulic machine control device - Google Patents

Description

The present invention relates to a control device used in a hydraulic oil supply system for a hydraulic actuator for driving a hydraulic machine such as an excavation swivel work machine.

Conventionally, it is a hydraulic oil supply system for a hydraulic actuator for driving a hydraulic machine such as an excavation turning work machine as shown in Patent Documents 1 and 2, and is a variable capacity type via a directional control valve. It is known that the hydraulic oil discharged from the hydraulic pump of the above is configured to be supplied to the hydraulic actuator.

In the system disclosed in each of the above patent documents, the control mechanism of the discharge oil amount of the variable displacement hydraulic pump uses a load sensing valve to supply the discharge pressure of the hydraulic pump and the secondary side of the directional control valve (of the hydraulic actuator). The amount of oil discharged from the hydraulic pump is adjusted so that the difference from the load pressure on the inlet port side (hereinafter simply referred to as "differential pressure") is constant, while the hydraulic pressure in the directional control valve. The opening area of the meter-in throttle that narrows the flow path from the pump to the hydraulic actuator is changed according to the amount of operation of the manual operating tool. As a result, the hydraulic actuator is supplied with the required amount of hydraulic oil corresponding to the operating speed of the actuator set by the manual operating tool from the directional control valve, that is, a supply of substantially the same amount as the required flow rate of the actuator. Since the flow rate can be realized, the operating efficiency of the hydraulic oil supply system can be improved.

Further, Patent Documents 1 and 2 disclose a technique for adjusting a target differential pressure set by a load sensing valve. That is, the control pressure adjustable by the controller is applied to the discharge pressure of the hydraulic pump against the load pressure in the load sensing valve.

On the other hand, as shown in Patent Document 2, in the conventional excavation turning work machine, a pair of traveling devices such as a pair of left and right crawler traveling devices are separately driven in the plurality of hydraulic actuators. A pair of traveling hydraulic motors for the purpose is provided.

Patent Document 2 lowers the target differential pressure in the load sensing valve when only the hydraulic motor for traveling is driven among the hydraulic actuators, that is, when it is detected that the vehicle is set to travel. As a result, a technology for reducing the discharge amount of the hydraulic pump has been disclosed, so that the hydraulic pump for driving a traveling hydraulic motor, which requires a smaller load pressure than other hydraulic actuators for work, can be used. It is intended to reduce the loss of the discharge amount and improve the operating efficiency of the hydraulic actuator.

Further, as shown in Patent Document 3, it is a traveling hydraulic motor provided with a movable swash plate as a capacity changing means, and is movable in two positions, a high-speed position with a small tilt angle and a low-speed position with a large tilt angle. It is known that the tilt angle of the plate can be switched. Assuming that the amount of oil discharged from the hydraulic pump is constant, if the movable swash plate is set to the high speed position, the capacity of the hydraulic motor will become smaller and the hydraulic motor will be rotationally driven at high speed. Its capacity increases and it is driven to rotate at low speed.

In Patent Document 3 above, the switching of the movable swash plate position of the hydraulic pump is performed by manual operation of a lever or the like provided near the driver's seat of the vehicle, and the operator can voluntarily drive the vehicle on the road, for example. If you want to make it run at a high speed, set it to a low speed position, and if you want to run it at a low speed while working, set it to a low speed position.

Japanese Unexamined Patent Publication No. 2-76904 Japanese Unexamined Patent Publication No. 2011-247301 Japanese Unexamined Patent Publication No. 10-338947

In a hydraulic machine such as an excavation turning work machine equipped with a traveling hydraulic motor capable of shifting in two stages as shown in Patent Document 3, the movable swash plate of the traveling hydraulic motor is set to a high-speed position (small capacity setting position). There are many requests for the vehicle to have a higher running speed when the hydraulic pressure is increased (hereinafter referred to as "high-speed setting state"). On the other hand, regarding the traveling speed of the vehicle when the movable swash plate of the traveling hydraulic motor is set to the low speed position (hereinafter referred to as "low speed setting state"), the traveling speed is the same as before in order to maintain reliable work accuracy. It is considered good.

One way to increase the running speed of the vehicle in the high-speed setting state is to increase the engine speed, but when switching to the low-speed setting state at the same engine speed, the running speed in the low-speed setting state also increases. Therefore, the above-mentioned running speed in the low speed setting state does not meet the conventional demand.

Here, in Patent Document 3, the traveling speed is lowered by reducing the maximum discharge flow rate of the variable displacement hydraulic pump when the low speed setting state is set. However, this technique simply reduces the maximum tilt angle position of the hydraulic pump by a certain angle in accordance with switching to the large capacity setting position of the traveling hydraulic motor, and this technique is as shown in Patent Document 1. When combined with a pump control system using a load sensing valve, the flow rate from the hydraulic pump to the hydraulic actuator is adjusted according to the operation amount of manual operation in the operation amount range that is not affected by the reduction of the maximum discharge flow rate. However, when the operation amount reaches the area corresponding to the reduction of the maximum discharge flow rate, even if the manual operation amount is increased from there to the maximum operation amount, the flow rate to the actuator cannot be adjusted in the saturated state, and the operation is performed. A situation can occur in which the sex is significantly reduced.

If the hydraulic motor is changed to one with a changed configuration (changed speed ratio) of a two-stage switching type capacity changing means such as a movable swash plate, the above request can be met, but a mechanical design change can be made. It is necessary, disadvantageous in terms of sharing parts, etc., and leads to high cost.

The invention according to the present application uses the following means in order to solve the above problems.

That is, the control device according to the present application is a control device for a hydraulic machine provided with a plurality of hydraulic actuators driven by discharge oil from a variable displacement hydraulic pump driven by an engine, and the control device is a control device. The required flow rate of each hydraulic actuator is controlled by controlling the flow rate of the discharge oil of the hydraulic pump when the hydraulic actuators are driven, and by controlling the flow rate of the discharge oil of the hydraulic pump according to the change in the engine rotation speed. It is configured to correct the target value of the ratio of the supply flow to.

With the control device of the hydraulic machine as described above, the ratio (speed ratio) of the output speed of the hydraulic motor for traveling to the output speed when the large capacity is set and the output speed when the small capacity is set can be changed. That is, assuming that the operating amount of the directional control valve for the hydraulic motor is constant at a constant engine speed, the output speed difference due to the switching of the capacity is specified by the standard of the hydraulic motor. It can be different from the value.

Therefore, for example, when a high-speed engine is provided in order to increase the road traveling speed of the hydraulic machine, the high idle rotation speed (maximum engine rotation speed) increases, so that the hydraulic motor for the traveling is provided. When the small capacity is set, it is possible to increase the road running speed by high speed engine rotation, while when the large capacity is set, the work is not affected by the increase in high idle speed due to the high engine rotation. The output speed of the hydraulic motor can be kept low so that the conventional running speed is easy.

The speed ratio can be changed by changing the set position of the movable swash plate of the hydraulic motor, but in this case, the design of the complicated mechanism for positioning the movable swash plate is forced to be changed, and the cost is high. May lead to. However, the control device according to the present application is an existing load sensing type pump control system that corrects a target value of a differential pressure between a discharge pressure and a load pressure, as described as the first aspect. It is only necessary to adopt the structure adopted in the above when switching the capacity of the hydraulic motor for traveling. For example, as described as the second aspect, the structure is such that two or more maps corresponding to each capacity setting of the hydraulic motor are stored. Therefore, it is possible to provide a control device that achieves the above-mentioned effects at low cost.

Further, since the correction of the target value of the differential pressure is to control the flow rate of the discharge oil of the hydraulic pump, the correction of the ratio of the supply flow rate to the required flow rate is applied not only to the hydraulic motor for traveling but also to all the actuators. Will be done. In this case, if the output speed of the traveling hydraulic motor at the time of setting a large capacity is suppressed to a low level as described above, not only the traveling speed can be suppressed to a low level, but also the driving speed of other actuators can be controlled by the traveling hydraulic motor. As the capacity is switched to the larger capacity setting, the drive speed becomes lower and the work efficiency drops.

In this respect, as described as the third aspect, only when it is confirmed that the hydraulic motor is actually driven at the time of setting the large capacity of the hydraulic motor, is it used for setting the large capacity? By using the second map, other actuators can be driven at the drive speed corresponding to the small capacity setting of the hydraulic motor, regardless of the capacity switching of the hydraulic motor, and the traveling speed. It is possible to perform efficient work that is the same as when setting a small capacity, while keeping it low.

A side view of an excavation work machine as an example of a hydraulic machine. The hydraulic circuit diagram which shows the pressure oil supply system to a hydraulic actuator. Block diagram of a load-sensitive pump control system. Graph of the supply flow rate to the hydraulic actuator with respect to the engine speed by load-sensitive pump control when no control pressure is applied. Maps and graphs relating to load-sensitive pump control, FIG. 5 (a) is a map of control output values, FIG. 5 (b) is a graph of control pressure, and FIG. 5 (c) is a graph of target differential pressure. Graph of supply flow rate to hydraulic actuator with respect to engine speed by load sensing type pump control when control pressure is applied. Graph of supply flow rate to hydraulic actuator for operation amount by load sensing type pump control. Maps and graphs relating to load-sensitive pump control corresponding to capacity switching of the traction motor, FIG. 8 (a) is a map of control output values, FIG. 8 (b) is a graph of control pressure, and FIG. 8 (c). ) Is a graph of the target differential pressure. Graph of the supply flow rate to the hydraulic actuator with respect to the engine speed by load-sensitive pump control corresponding to the capacity switching of the traction motor. Graph of supply flow rate to hydraulic actuator for operation amount by load sensing type pump control corresponding to capacity switching of traction motor.

The schematic configuration of the excavation swivel work machine 10 as an embodiment of the hydraulic machine shown in FIG. 1 will be described. The excavation turning work machine 10 includes a pair of left and right crawler type traveling devices 11. Each crawler traveling device 11 supports the drive sprocket 11b and the driven sprocket 11c on the track frame 11a, and winds the crawler 11d between the drive sprocket 11b and the driven sprocket 11c. It is also conceivable that the traveling device is a foil type traveling device.

A swivel table 12 is mounted on the upper part of the pair of left and right crawler type traveling devices 11 so as to be rotatable around a vertical pivot with respect to both crawler type traveling devices 11, and the engine E and the pump unit PU are mounted on the swivel table 12. , The bonnet 13 for incorporating the control valve unit V and the like is mounted. A seat 14 for an operator is further arranged on the swivel table 12, and manual operating tools such as levers and pedals for operating each hydraulic actuator described later are arranged in front of and on the side of the seat 14. There is.

The swivel table 12 is provided with a boom bracket 15 that can rotate horizontally with respect to the swivel table 12, and the base end portion of the boom 16 is pivotally supported by the boom bracket 15 so as to be vertically rotatable. The base end portion of the arm 17 is pivotally supported at the tip end portion so as to be vertically rotatable, and the bucket 18 as a working machine is pivotally supported at the tip end portion of the arm 17 so as to be vertically rotatable. As another work machine, a blade 19 for soil removal is attached to a pair of left and right crawler type traveling devices 11 so as to be vertically rotatable.

As shown in FIG. 2, the excavation swivel work machine 10 is provided with a plurality of hydraulic actuators for driving each drive unit of the excavation swivel work machine 10 described above. FIG. 1 shows a boom cylinder 20, an arm cylinder 21, and a bucket cylinder 22, which are typical hydraulic actuators. The boom 16 rotates up and down with respect to the boom bracket 15 due to the expansion and contraction of the piston rod of the boom cylinder 20, and the arm 17 rotates up and down with respect to the boom 16 due to the expansion and contraction of the piston rod of the arm cylinder 21. The bucket 18 rotates up and down with respect to the arm 17 due to the expansion and contraction of the rod.

In addition to these, the excavation swivel work machine 10 includes a swing cylinder for horizontally rotating the boom bracket 15 with respect to the swivel base 12, which is not shown in FIG. 1, as a telescopic hydraulic actuator composed of a hydraulic cylinder. A blade cylinder or the like for rotating the blade 19 up and down with respect to the crawler type traveling device 11 is provided.

Further, in the excavation turning work machine 10, as a rotary hydraulic actuator composed of a hydraulic motor, the first traveling for driving the driving sprocket 11b of one of the left and right crawler type traveling devices 11 (not shown in FIG. 1). The motor 23 (see FIG. 2), the second traveling motor 24 for driving the other drive sprocket 11b of the left and right crawler type traveling devices 11 (see FIG. 2), and the swivel table 12 are left and right crawler type traveling devices. A swivel motor 25 (see FIG. 2) for swiveling with respect to 11 is provided.

The hydraulic pump discharge oil supply control system for each hydraulic actuator provided in the excavation turning work machine 10 will be described with reference to the hydraulic circuit diagram of FIG. The excavation turning work machine 10 is provided with a hydraulic pump 1 driven by the engine E. The hydraulic pump 1 supplies pressure oil to the boom cylinder 20, the arm cylinder 21, the traveling motors 23 and 24, and the swivel motor 25. In the hydraulic circuit diagram of FIG. 2, these are shown as typical hydraulic actuators, and other hydraulic actuators are omitted.

Each hydraulic actuator is provided with a separate directional control valve, and these directional control valves are combined to form the control valve unit V.

The position of each directional control valve is switched by the manual operation of each of the above-mentioned manual operating tools, and the oil supply direction is switched. Further, each directional control valve is provided with a meter-in throttle, and the opening degree of the meter-in diaphragm changes according to the amount of operation of each manual operating tool. As a result, in combination with the discharge flow control of the hydraulic pump 1 by the load sensing type pump control system 5 described later, the supply flow rate of the hydraulic oil to each hydraulic actuator can be adjusted to the required flow rate of each hydraulic actuator, and the work can be performed. It is possible to reduce the excess flow rate, which is returned to the tank without any loss, and to improve the operating efficiency of the hydraulic oil supply system to the hydraulic actuator. In other words, for each hydraulic actuator, the required flow rate is determined by the opening degree of the meter-in throttle set according to the operation amount of the directional control valve.

In FIG. 2, as the manual operation tools for the direction control valves 30, 31, 33, 34, and 35, the boom operation lever 30a, the arm operation lever 31a, the first travel operation lever 33a, the second travel operation lever 34a, and the turning Although it is drawn assuming that the operating lever 35a is provided, these manual operating tools may be pedals, switches, or the like in addition to the lever, or may be integrated as appropriate. For example, one lever may be rotated in one direction to control one directional control valve, and the rotation in the other direction may be used to control another directional control valve.

Further, the manual operation tool (lever 30a, 31a, 33a, 34a, 35a) is used as a remote control (pilot) valve, and the pilot pressure generated by the operation of the manual operation tool causes each direction control valve 30, 31, 33, 34, 35. It may be controlled.

Further, the excavation turning work machine 10 is provided with a speed change switch 26. The speed change switch 26 is linked to the movable swash plate 23a of the first traveling motor 23 and the movable swash plate 24a of the second traveling motor 24, which are variable displacement hydraulic motors, and the movable swash plate is operated by the operation of the speed change switch 26. 23a and 24a are tilted at the same time. The movable swashplates 23a and 24a of the traveling motors 23 and 24 may be operated by a manual operating tool other than the switch, such as a pedal or a lever.

In this embodiment, the speed change switch 26 is used as an ON / OFF changeover switch, and when the speed change switch 26 is turned on, the movable swash plates 23a and 24a are tilted at a small tilt angle for setting a high speed (normal speed) suitable for driving on the road. Arrange in the (small capacity) position, and by turning off the shift switch 26, arrange the movable swash plates 23a and 24a in the large tilt angle (large capacity) position for setting the low speed (working speed) suitable for work driving. It is supposed to be.

More specifically, the movable swash plates 23a and 24a are linked to the piston rods of the swash plate control cylinders 23b and 24b, which are hydraulic actuators, and open and close to supply hydraulic oil to both swash plate control cylinders 23b and 24b. A valve 27 is provided. When the speed change switch 26 is turned on, the on-off valve 27 opens due to the pilot pressure to supply hydraulic oil to the swash plate control cylinders 23b and 24b, and the swash plate control cylinders 23b and 24b move the movable swash plates 23a and 24a to the small tilt angle position. Push. On the other hand, when the speed change switch 26 is turned off, the on-off valve 27 returns the hydraulic oil from the swash plate control cylinders 23b and 24b, and returns the movable swash plates 23a and 24a to the large tilt angle position by the spring tension of the piston rod.

The hydraulic pump 1, the relief valve 3 for preventing the discharge pressure of the hydraulic pump 1 from becoming excessive, and the load sensing type pump control system 5 are combined to form a pump unit PU. The load sensing type pump control system 5 is composed of a pump actuator 6, a load sensing valve 7, and a pump control proportional valve 8.

The pump actuator 6 is composed of a hydraulic cylinder, and its piston rod 6a is linked to the movable swash plate 1a of the first hydraulic pump 1. By expanding and contracting the piston rod 6a, the movable swash plate 1a is tilted at the same time. Change the tilt angle. Thus, changing the discharge oil amount Q _P of the hydraulic pump 1.

The supply / discharge port of the load sensing valve 7 communicates with the oil pressure chamber 6b for extending the piston rod of the pump swash plate actuator 6. The load sensing valve 7 is urged by the spring 7a in the direction of draining oil from the oil pressure chamber 6b of the pump swash plate actuator 6, that is, in the direction of contracting the piston rod 6a. The contraction direction of the piston rod 6a is the inclination angle increasing side of the movable swash plate 1a, that is, the discharge flow rate increasing side of the hydraulic pump 1.

A part of the oil discharged from the hydraulic pump 1 is introduced into the load sensing valve 7 as hydraulic oil to be supplied to the pressure oil chamber 6b of the pump swash plate actuator 6. Part thereof, as a pilot pressure based on the discharge pressure P _P of the hydraulic pump 1, it is added to the load sensing valve 7 against the spring 7a. Discharge pressure P _P as a pilot pressure to the load sensing valve 7, the direction for supplying oil to the oil chamber 6b of the pump swash plate actuator 6, i.e., to switch the load sensing valve 7 in a direction to extend the piston rod 6a Acts on.

Further, for the omnidirectional control valve, the maximum hydraulic pressure, that is, the maximum load, is out of all the hydraulic pressure on the secondary side through the meter-in throttle, that is, the hydraulic pressure of the oil supplied from each directional control valve to each hydraulic actuator. extracting pressure P _L, is added to the load sensing valve 7 as a pilot pressure against it to discharge pressure P _P.

Equation Here, the flow rate of oil supplied to the hydraulic actuators of the corresponding through the meter-in throttle of the directional control valves, i.e., the required flow rate Q _R of each hydraulic actuator is represented in the "number 1" below Is calculated by.

Therefore, assuming that the control pressure P _C to be described later is 0, the position of the load sensing valve 7, the pressure difference [Delta] P (uncontrolled differential pressure [Delta] P ₀ between the discharge pressure P _P and the maximum load pressure P _L ) it is switched depending on whether above or below the spring force F _S of the spring 7a. That is, the pressure difference ΔP is exceeds the spring force F _S, the piston rod 6a of the pump actuator 6 is extended, reducing the tilt angle of the movable swash plate 1a, to reduce the discharge flow rate Q _P of the hydraulic pump 1. When the spring force F _S exceeds the differential pressure [Delta] P, the piston rod 6a of the pump actuator 6 is contracted to increase the tilt angle of the movable swash plate 1a, increasing the discharge flow rate Q _P of the hydraulic pump 1.

From the above equation, if the differential pressure ΔP is constant, the required flow rate Q _R is proportional to the meter-in throttle of the cross-sectional area A (opening). The opening degree of the meter-in throttle is determined according to the amount of operation of the manual operating tool of the directional control valve. That is, the required flow rate Q _R is the amount determined regardless of changes in engine speed, long as it retains the operation amount constant, the required flow rate Q _R is kept constant.

Due to lack of oil discharged quantity Q _P from the hydraulic pump 1, the supply flow rate through the meter aperture in the directional control valve to the hydraulic actuator to be operated, if insufficient to the required flow rate Q _R of the hydraulic actuator, the differential pressure ΔP is reduced by less than the spring force F _S, the load sensing valve 7 operates in a direction to increase the inclination angle of the movable swash plate 1a, increasing the discharge flow rate Q _P of the hydraulic pump 1, the Increase the supply flow rate to the hydraulic actuator. As a result, the driving speed of the hydraulic actuator can be increased to the speed set by the manual operating tool.

On the other hand, when the discharge oil amount Q _P from the hydraulic pump 1 is excessive, and the differential pressure ΔP is increased, by exceeding the spring force F _S, the load sensing valve 7, reducing the tilt angle of the movable swash plate 1a operated in a direction to reduces the discharge flow rate Q _P of the hydraulic pump 1, the supply flow rate to the hydraulic actuator, is reduced to a value commensurate with the required flow rate Q _R. Thereby, the excess supply amount of the hydraulic oil can be reduced.

Here, for example, even if the operating amount of each lever (spool stroke of each direction control valve) is maximum (that is, the opening degree of the meter-in throttle of each direction control valve is maximum), it is required by the hydraulic actuator to be operated. there is a difference in the flow rate _{Q R.} For example, while the required flow rate of the boom cylinder 20 for rotating the boom 16 is high, the required flow rate of the swivel motor 25 for rotating the swivel table 12 is not so high.

Thus, even differ in required flow rate of each actuator, so that the differential pressure (target pressure difference) defined the differential pressure ΔP in the load sensing valve 7 as described above in the spring force F _S of the spring 7a By controlling the tilt angle of the movable swash plate 1a, the hydraulic pump 1 supplies a flow rate of oil corresponding to the required flow rate specified by each directional control valve. That is, for all actuators, the required flow rate Q ratio of the supply flow rate Q with respect to _R (Q / Q R) _(hereinafter referred to as "test main flow ratio") (hereinafter the goal of is 1, the target value " The target flow rate ratio Rq) and the tilt angle (pump capacity) of the movable swash plate 1a of the hydraulic pump 1 are controlled.

On the other hand, if the tilt angle of the movable swash plate 1a constant, the discharge flow rate Q _P of the hydraulic pump 1 is changed with a change in the engine speed N.

Here, the change in the engine speed is defined differential pressure [Delta] P ₀ where target differential pressure [Delta] P in the load sensing valve 7 regardless is defined by the spring force F _S (i.e., the entire engine speed range, For the drive of all actuators, the operation amount of the boom operation lever 30a is set on the premise that the movable swash plate 1a of the pump 1 is controlled with the target that the target required flow rate ratio Rq is 1 (Rq = 1). The supply flow rate characteristic in the case where the rotation of the boom 16 at the maximum and the rotation of the swash plate 12 at the maximum operation amount of the swivel operation lever 35a are alternately performed will be considered with reference to FIG.

FIG. 4 shows the characteristics of the supply flow rate Q of the hydraulic actuator over the entire region of the engine speed N set for the operation of the hydraulic actuator (here, the supply flow rate Qb to the boom cylinder 20 and the supply flow rate of the swivel cylinder 25). (Characteristics of Qs) are shown, and in this region of the engine flow rate N, the low idle speed N _L is the minimum value and the high idle speed N _H is the maximum value. Further, the tilt angle of the movable swash plate 1a, when the engine driving at high idle speed N _H (hereinafter referred to as "high idle rotation") as the theta _NH which is operated, the low idle speed N _{L Θ NL} is used when the engine is driven in (hereinafter referred to as “low idle rotation”).

4 shows, the maximum amount of pump discharge flow rate Q _P obtained when the movable swash plate 1a is in the maximum inclination angle position Q _{PMAX (hereinafter,} the maximum discharge flow rate Q _PMAX) of, over the engine speed range It shows a change. On the other hand, the supply flow rate Q is the flow rate actually supplied to each actuator via the directional control valve, and as long as each actuator is driven independently, the hydraulic pump is driven by the load sensing pump control system 5 for each drive. since the first discharge flow rate Q _P is controlled to meet the request flow Q _R, the discharge flow rate Q _{P =} supply flow rate Q is the result. The following description assumes this.

First, as long as the target differential pressure [Delta] P is defined in the defining differential pressure [Delta] P _0, as each actuator is operated, to supply oil discharged from the pump 1 so as to satisfy the required flow rate Q _R, i.e., The tilt angle of the movable swash plate 1a is controlled with the target required flow rate ratio Rq = 1.

Here, the required flow rate Qb _R of the boom cylinder 20 when the maximum operation amount of the boom operating lever 30a is about to be determined by the maximum opening area of the meter-aperture of the directional control valve 30 S _{MAX (see} FIG. 7), Since this required flow rate Qb _R is smaller than the pump maximum discharge flow rate Q _PHMAX during high idle rotation, the tilt angle Θb1 of the swash plate 1a when the boom 16 is driven during high idle rotation is equal to or less than the _{maximum tilt angle Θ MAX.} (In this embodiment, the tilt angle is smaller than _{Θ MAX).} That is, at the time of high idle rotation, the supply flow rate Qb to the boom cylinder 20 becomes the _{same Qb R as the required flow rate.} That is, during high idle rotation, the supply flow rate Qb to the boom cylinder 20 becomes the maximum value, and the drive speed of the boom 16 at this time becomes the maximum drive speed.

However, as long as the operation amount of the boom operating lever 30a is maintained at the maximum value, the required flow rate Qb _R of the boom cylinder 20 is constant, while the required flow rate Qb _R is the highest among all the actuators, so that the engine rotations. as the number N becomes lower than the high idle rotational speed _{N H,} the maximum discharge flow rate _{Q PMAX} is lowered, eventually (in FIG. 5, when the engine speed N becomes _{N 1),} the maximum discharge flow rate _{Q PMAX} itself boom cylinder It becomes the same as the required flow rate Qb _{R of 20.} While the engine rotational speed N is reduced from N _H to N _1, load sensing pump control system 5, in order to realize the target subjected main flow ratio Rq of the boom cylinder 20 (= 1), the tilting of the swash plate 1a increasing the angle, at the time of the engine speed N = N _1, the slant angle of the movable swash plate 1a, and thus reach the maximum angle theta _MAX.

Further, while the engine speed N falls _{below N 1} and drops to the low idle speed _NL , the maximum discharge flow rate Q _PMAX falls below the required flow rate Qb _R of the boom cylinder 20, resulting in a drop in engine speed. As a result, the supply flow rate Qb to the boom cylinder 20 _{overlaps with the maximum discharge flow rate Q PMAX} and is reduced. As the supply flow rate Qb decreases, the operating speed of the boom cylinder 20, that is, the driving speed of the boom 16 decreases.

On the other hand, the required flow rate Qs _R of the turning motor 25 in the case of the maximum operation amount of the revolving operation lever 35a is determined by the maximum opening area S _MAX of the throttle meter of the directional control valve 35 _(see FIG. 7), the requested flow In _{order to satisfy Qs R} , the movable swash plate 1a of the hydraulic pump 1 is arranged at the tilt angle Θs1 during high idle rotation, and the swivel cylinder 23 is operated at its maximum speed, that is, the swivel table 12 is swiveled at its maximum speed. .. Therefore, during high idle rotation, the boom cylinder 20 is driven by maximizing the operation amount of the boom operation lever 30a, and the swivel motor 25 is driven by maximizing the operation amount of the swivel operation lever 35a. , Both the boom 16 and the swivel base 12 rotate at their respective maximum drive speeds.

_{However, the required flow rate Qs R} of the swivel cylinder with the maximum operation amount of the swivel operation lever 35a _{is considerably lower than the required flow rate Qb R} of the boom cylinder 20 with the maximum operation amount of the boom operation lever 30a, and high idle rotation. Occasionally, the tilt angle ΘH of the movable slant plate 1a is considerably smaller than the tilt angle Θb1 when operating the boom cylinder 20 with the boom operating lever 30a as the maximum operating amount, up to the maximum tilt angle Θ _MAX. It has a considerable tilt tolerance.

Therefore, the pump of the load sensing type pump control system 5 in which the target required flow rate ratio Rq = 1 while the turning operation lever 35a is held at the maximum operating amount and the _{engine rotation speed N decreases from the high idle rotation speed NH.} By control, the tilt angle Θ of the movable swash plate 1a is tilted to the angle increasing side so that the supply flow rate Qs _{satisfies the required flow rate Qs R.} reduced to a few N _L, even in a state where the movable swash plate 1a has reached the slant angle Θs2 is tilted at an angle increasing side maximally still does not lead to a maximum tilting angle theta _MAX. Therefore, while the _{engine speed N drops to the low idle speed NL} , the supply flow rate Qb to the swivel motor 25 _{satisfies the required flow rate Qb R} , and the operating speed of the swivel motor 25 remains at the maximum speed. Yes, the turning speed of the turning table 12 remains at the maximum speed.

In this way, the drive speed of the boom 16 during low idle rotation is lower than that during high idle rotation, while the drive speed of the swivel table 12 during low idle rotation is maintained at the time of high idle rotation. In the situation of leaning, the operator rotates the boom 16 at the slow speed assumed by driving the _{engine E at the low idle speed NL, and then continuously rotates the swivel table 12.} When shifting to the operating industry, the rotation speed is faster than expected, making the work difficult. Further, even when the swivel table 12 is to be operated at a minute speed, the swivel speed of the swivel table 12 does not change when the engine speed is reduced, so that the speed can be adjusted only by adjusting the swivel operation lever 35a. It will be a machine that makes it difficult to perform fine turning operations.

Therefore, by reducing the target required flow rate ratio Rq for all actuators at a constant ratio so as to match the decrease in engine speed, and performing pump control by the load-sensing pump control system 5, each operation is performed. supply flow rate Q of the respective actuators in, regardless the size of the required flow rate Q _R, is reduced uniformly to meet the reduction amount of the engine speed N, accordingly, driving of the drive unit driven by the actuator The speed can be reduced uniformly.

For example, when the rotation of the boom 16 and the rotation of the swivel base 12 are alternately performed as described above, it is equivalent to that the rotation of the boom 16 is slower in the low idle rotation than in the high idle rotation. It is possible to slow down the rotation of the swivel table 12 with the same feeling, and it is possible to solve the problem that the rotation of the swivel table 12 is felt to be relatively faster than the rotation of the boom 16.

Further, due to such pump control, the drive speed of the swing motor 25 decreases as the engine speed decreases, so that it was impossible when the target required flow rate ratio Rq = 1 was fixed and the pump was controlled. It is also possible to finely adjust the position of the swivel table 12 by adjusting the speed of the swivel motor 25 by increasing or decreasing the engine speed.

As a means for lowering the target required flow rate ratio Rq of all actuators in response to the decrease in engine speed, the load-sensitive pump control system 5 is provided with an electromagnetic proportional valve as a pump control proportional valve 8. The oil from the pump control proportional valve 8 is supplied to the load sensing valve 7 as pilot pressure oil. Secondary pressure of the load sensing valve 7 having of this oil is the control pressure P _C to be added to the load sensing valve 7 to resist the maximum load pressure P _L.

Min plus control pressure P _C, the differential pressure between the discharge pressure P _P and the maximum load pressure P _L required to balance the spring force F _S, ie, the target differential pressure ΔP is reduced. Therefore, as the control pressure _CC is increased, the load sensing valve 7 acts on the tilt angle decreasing side of the movable swash plate 1a, and the discharge flow rate of the hydraulic pump 1 is reduced.

The control pressure _CC is determined by the current value applied to the solenoid 8a of the pump control proportional valve 8 which is an electromagnetic proportional valve. Let this be the control output value C. Therefore, for the direction control valve of each hydraulic actuator, the correlation of the required flow rate of the hydraulic actuator with the operating amount of the manual operating tool is assumed for each engine rotation speed, and the engine rotation speed is realized so as to realize the assumed correlation. By creating a correlation map of the control output value C corresponding to the above and storing this map in the storage unit of the controller that controls the control output value for the pump control proportional valve 8, as described above, the engine speed It is possible to control the required flow rate ratio of all hydraulic actuators in response to the change (that is, control that the drive speed of a plurality of actuators is reduced by the same ratio according to the engine rotation speed). Based on this map, the control for reducing the target value of the required flow rate ratio of all hydraulic actuators, which should originally be 1, according to the decrease in engine speed is referred to as "deceleration control", and will be described below. ..

The excavation turning work machine 10 is configured with a hydraulic actuator control system as shown in FIG. First, the storage unit 51 included in the controller 50 stores a correlation map of the control output value C corresponding to the engine speed N for all actuators.

A map of the control output value C for the engine speed N stored in the storage unit 51 is prepared for each work mode that can be set in the excavation turning work machine 10. In this application, as shown in FIG. 8A, only the standard map M1 selected when the normal mode is set and the low speed driving map M2 selected when the low speed driving mode is set are taken up, but other than this. It is conceivable that the excavation turning work machine 10 can be set to a fuel saving mode or the like that lowers the high idle rotation speed than in the normal case, and the map of the control output value C used when this is set is also available. It is conceivable to include it in the above-mentioned map group.

An engine rotation speed detection signal and an ON / OFF signal of the speed change switch 26 are input to the controller 50 from the engine rotation speed detection unit 52. Further, from the travel detection means 53, a travel detection signal indicating whether or not the excavation turning work machine 10 is actually traveling (that is, whether or not the traveling motors 23 and 24 are driven) is transmitted to the controller 50. Entered. The travel detection means 53 may be configured to detect the operation amount of the travel operation levers 33a / 34 (for example, when the operation amount of both levers 33a / 34 is 0, it is determined that the vehicle is not traveling).

The ON / OFF signal of the speed change switch 26 and the travel detection signal from the travel detection means 53 relate to whether the standard map M1 or the low-speed travel map M2 is selected. In addition to these, for example, the above-mentioned In connection with the selection of the map for the fuel consumption mode, it is conceivable that a signal or the like from a switch that is turned ON when the fuel consumption mode is set is input to the controller 50.

The controller 50 determines the setting mode based on these input signals, and selects a map corresponding to the setting mode from the correlation map group of the control output value C with respect to the engine speed N stored in the storage unit 51. Then, the target value of the control output value C is determined by applying the engine rotation speed N based on the input signal from the engine rotation speed detection unit 52 to the selected map.

How one of the standard map M1 and the low-speed traveling map M2 is selected based on the above-mentioned signal input will be described in detail later with reference to FIGS. 8 to 10.

Based on this determination, the controller 50 applies a current of the determined control output value C to the solenoid 8a of the pump control proportional valve 8 in the load sensing type pump control system 5, and from the pump control proportional valve 8 to the load sensing valve 7. _{, Pilot pressure oil having the control pressure CC} generated by the addition of the control output value C is supplied, whereby the tilt angle of the movable swash plate 1a of the hydraulic pump 1 via the pump actuator 6, that is, It controls the discharge flow rate of the hydraulic pump 1.

5 to 7, a map of the control output value C and a mode of pump control based on the map will be described with respect to “deceleration control”.

FIG. 5A shows a map M1 showing a change in the control output value C as the engine speed N is _{lowered from the high idle speed N H} to the low idle speed N _L. Here, the configuration of a typical standard map M1 in the map group prepared for each of several modes that can be set in the excavation turning work machine 10 as described above will be described.

Map M1 is a control output value C at high idle speed and the minimum value C _{0 (value} secondary pressure (the control pressure P _C) and 0 of the pump control proportional valve 8), control output in low idle rotation C is set as the maximum value C _MAX, and the control output value C is increased as the engine speed N is lowered from the high idle speed _NH to the low idle speed N _L.

5 (b) and 5 (c) show that the control output value C (current value applied to the solenoid 8a) of the pump control proportional valve 8 is changed in response to the change in the engine speed N based on the map M1. cases, there is shown a variation of the pressure on the load sensing valve 7, FIG. 5 (b), the secondary pressure of the engine control proportional valve 8, i.e., shows the change in the control pressure P _C, 5 ( c) shows the target value of the differential pressure [Delta] P between the control pressure P _P and the maximum load pressure P _L, that is, the target differential pressure [Delta] P.

Since the control output value C is the minimum value C ₀ during high idle rotation, the control pressure _CC is 0. Therefore, the target differential pressure [Delta] P is defined differential pressure [Delta] P ₀ equal to the spring force F _S of the load sensing valve 7. As the engine speed N decreases from the high idle speed N _H to the low idle speed N _{L , the control pressure CC} increases due to the increase in the control output value C, and the target differential pressure ΔP decreases by that amount. The target differential pressure ΔP during low idle rotation is defined as the minimum target differential pressure ΔP _MIN .

FIG. 6 is a diagram showing the effect of "deceleration control" that appears in the supply flow rate characteristics to the hydraulic actuator in response to changes in the engine rotation speed, and is a diagram showing two hydraulic actuators having different required flow rates (here, a boom cylinder). It assumes a working state in which 20 and the swivel motor 25 are operated alternately (that is, each independently), and a graph of the pump supply flow rate Qb when driving the boom cylinder 20 having a high required flow rate and the required flow rate. The graph of the supply flow rate Qs when driving the swing motor 25 with a low flow rate is shown. Further, as in FIG. 4, _{a graph of the maximum discharge flow rate Q PMAX} is drawn. The operation amount of the operation levers 30a and 35a is maximized (the spool stroke S of each direction control valve 30 and 35 is the maximum value _SMAX ), that is, the required flow rates Qb _R and Qs _{R, respectively.} Is the maximum. Further, as described above, the tilt angle of the movable swashplate 1a is Θ _{NH for the high idle rotation and Θ NL} for the low idle rotation.

First, during high idle rotation (N = _NH ), the control output value C of the pump control proportional valve 8 is set to the minimum value C _{0, and the control pressure CC} is not applied to the load sensing valve 7 (that is, the specified differential pressure). Since ΔP ₀ is the target differential pressure ΔP), the movable swash plate 1a is controlled with the target required flow rate ratio Rq = 1 for each actuator. Therefore, as in the case of high idle rotation described with reference to FIG. 4, when the boom cylinder 20 is driven, the movable swash plate 1a reaches the tilt angle Θb1 and the supply flow rate Qb _H satisfies the required flow rate Qb _{R (Qb H} = Qb). _R ), while the boom 16 is driven at its maximum speed, the movable swash plate 1a reaches the tilt angle Θs1 when the swivel motor 25 is driven, and the supply flow rate Qs _H satisfies the required flow rate Qs _{R (Qs H} = Qs _R ). The swash plate 12 is swiveled at its maximum speed.

On the other hand, during low idle rotation _(N = N _L), a large _{C MAX} becomes also the control output value C is below the minimum value _{C 0} of the pump control proportional valve 8, it takes the control pressure _{P C} to the load sensing valve 7, the target differential pressure [Delta] P is defined differential pressure [Delta] P 0 _- become a control pressure [Delta] P _C, decreases than at high idle speed. As a result, the target required flow rate ratio Rq of each actuator is set to a value smaller than the target value 1 at the time of high idle rotation. Here, when the target required flow rate ratio Rq at the time of low idle rotation is RqL, RqL = N _L / _NH . Therefore, when the boom cylinder 20 is driven, the tilt angle Θ _NL of the movable swash plate 1a is suppressed to Θ b2, and the supply flow rate Qb _{L of} rotation is reduced to Qb _R × _NL / _NH , while driving the swivel motor 25. Occasionally, the tilt angle Θ _NL of the movable swash plate 1a is suppressed to Θ s 3 which is smaller than Θ s 2 where it can be tilted to Θ s2 without deceleration control, and the supply flow rate Q s _L is reduced to Q s _R × _NL / _NH . do. In this way, as the engine speed decreases from the high idle speed to the low idle speed in both the boom cylinder 20 and the swing motor 25, the supply flow rate Q decreases at the same ratio, and the drive speeds thereof are also the same. It decreases in proportion.

Furthermore, when the engine E is driven at an arbitrary rotational speed N _M between the high idling speed N _H and a low idle speed N _L is the target subjected main flow ratio Rq when the actuator drive N _M / Let it be _NH . Any number of revolutions N _M is a numerical value as smaller closer to the low idle rotation speed N _L, therefore, the target subjected main flow ratio at the time of each actuator drive as the engine rotational speed N decreases toward the low idle rotation speed N _L Rq decreases.

Incidentally, any engine speed to a target subjected main flow ratio Rq corresponding to N _M and N _{M /} N _H, a reduction aspects of the supply flow rate Q of with decreasing target engine speed N when the drive of the actuators Is an example for adjusting to the decrease in the engine speed, and a numerical value different from this may be used. What is important is that the _{target required flow rate ratio Rq decreases as the target engine speed N decreases from the high idle speed NH} , and for all actuators, the engine speed decreases each time each actuator is operated. In addition, the effect of reducing the target required flow rate ratio Rq can be obtained.

_{Here, as described with reference to FIG. 4, for the boom cylinder 20 having a large required flow rate Qb R} in a state where the operation amount of the boom operation lever 30a is maximized, the target differential pressure ΔP is changed regardless of the change in the engine speed. If not (maintaining the target required flow rate ratio Rq = 1), the decrease in the supply flow rate Qb due to the decrease in the engine speed N is mostly due to the decrease in the maximum discharge flow rate Q _{PMAX due to the decrease in the engine speed N.} It has become. Then, referring to FIG. 6, the supply flow rate Qb of the boom cylinder 20 of the maximum operation amount of the boom operating lever 30a, and Qb _R × _N M / _{N H} in response to any engine speed _{N M} In this case, it can be seen that the mode of decrease in the supply flow rate Qb with the decrease in the engine speed is generally in line with the mode of decrease in the _{maximum discharge flow rate Q PMAX.}

_{On the other hand, for the swivel motor 25 in which the required flow rate Qs R} is small in the state where the operation amount of the swivel operation lever 35a is maximized, the target differential pressure ΔP does not change regardless of the change in the engine rotation speed, as described in FIG. In the case of (maintaining the target required flow rate ratio Rq = 1), the supply flow rate Qs satisfies the _{required flow rate Qs R} over the entire range of the engine speed _{N from the high idle speed NH} to the low idle speed _NL. When held, referring to FIG. 6, the supply flow rate Qs of the swing motor 25 in the operation amount of the swing operating lever 35a to set to the maximum, in response to any engine speed N _M Qs _R × N _M / By _{setting it to NH} , it can be seen that as the engine speed decreases, the supply flow rate Qs decreases as the engine speed decreases.

As described above, the effect of reducing the target required flow rate ratio Rq by increasing the control output value C shown in FIG. 5A as the engine speed decreases is apparently for an actuator having a small required flow rate. The supply flow rate, which has been held so as to satisfy the required flow rate even at low engine speeds, is reduced, so the effect is remarkable. For actuators with a large required flow rate, the engine speed is reduced. Since the mode of reducing the supply flow rate _{is similar to that due to the decrease in the maximum discharge flow rate QPMAX} , the effect is not clearly shown, but it can be seen in FIGS. 5 (a) to 5 (c). control output value C, the control pressure P _C, and the target differential pressure ΔP for the effect of control in response to changes in engine speed, also obtained large hydraulic actuators required flow as the boom cylinder 20 However, that is, for all the actuators, the effect of reducing the drive speed by reducing the target required flow rate ratio Rq corresponding to the engine rotation speed can be obtained at the time of each drive.

As a result, for all actuators, in a situation where the lever position is not changed, the drive speed decreases in a uniform manner (for example, as the engine speed decreases) as the engine speed decreases, and the engine speed decreases. It avoids the situation where the drive of one of the actuators is felt faster than the other actuators under the engine drive by the number of revolutions.

Further, in the case of an actuator having a small required flow rate such as the swivel motor 25, the fine speed adjustment of the actuator by changing the engine speed, which was impossible when the target required flow rate ratio Rq = 1, was fixed. Is possible.

In relation to deceleration control in response to changes in engine speed, in FIG. 7, the lever operation amount for certain hydraulic actuator, i.e., the required flow rate Q _R and the supply of the spool stroke S of the directional control valve The characteristics of the flow rate Q are shown. Required flow rate _{Q R} is increased as the spool stroke S increases, the maximum value _{Q RMAX} at the maximum stroke _{S MAX.} As at high idle speed, when there is no control output by the deceleration control as long as the required flow rate Q _R does not exceed the maximum discharge flow rate Q _PMAX of the pump, subjected main flow ratio becomes 1, the supply flow rate Q _H required to match the flow rate _{Q R.} On the other hand, the supply flow rate QL during low idling rotation by the effect of the deceleration control, the required flow rate Q _R, the amount multiplied by the (N _{L /} N H in the foregoing _embodiment) fixed ratio of less than 1. That is, when the spool stroke S of the maximum stroke _{S MAX,} the _{Q LMAX = Q RMAX × N L} / N H. This correspondence is maintained regardless of the state of the operation amount (spool stroke S), and even when the deceleration control is applied, the supply flow rate QL of the pump during low idle rotation increases as the lever operation amount increases. However, the operating speed of the actuator also increases.

Further, in the excavation turning work machine 10, in relation to the deceleration control, as described above, the standard map M1 or the low speed traveling map M2 shown in FIG. 8A is selected based on the selection of the normal mode or the low speed traveling mode. The map.

Here, to explain with reference to FIG. 3, in the controller 50, the movable diagonal plates 23a and 24 of the traveling motors 23 and 24 are positioned at a small tilt angle (small capacity) based on the signals from the speed change switch 26 and the traveling detection unit S2. When it is determined that the vehicle is in the (normal speed position), the excavation turning work machine 10 is set to the normal mode regardless of whether the traveling motors 23 and 24 are actually in the driving state (traveling state). The standard map M1 is selected from the map group stored in the storage unit 51.

On the other hand, when it is determined that the movable swash plates 23a and 24a of the traveling motors 23 and 24 are in the large tilt angle (large capacity) position (low speed position), the controller 50 determines that the traveling motors 23 and 24 are in the driving state (traveling state). If not, the standard map M1 is selected as the one that sets the excavation swash machine 10 to the normal mode. Then, when it is determined that the traveling motors 23 and 24 are actually in the driving state (traveling state), the excavation turning work machine 10 is set to the low-speed traveling mode, and the map group stored in the storage unit 51 is selected. Select the low-speed driving map M2. That is, the low-speed travel map M2 is selected only when the traveling motors 23 and 24 with the movable swashplates 23a and 24a in the low-speed position are actually driven.

In the standard map M1, the control output value C at the time of high idle rotation is set to the minimum value C ₀ (control output value where the control pressure _CC is 0), and the control output value C is increased as the engine speed N is decreased. , The control output value C at the time of low idle rotation is set to _CMAX . On the other hand, in the low-speed running map M2, the control output value C at the time of high idle rotation _{is set to a value C W} larger than the _{minimum value C 0} , and the control output value C is increased as the engine speed N is lowered, and the low idle rotation is performed. The control output value C at the time is the same _CMAX as when the normal mode is set.

That is, the standard map M1 increases the control output value C from the minimum value C ₀ to the maximum value C _{MAX as the engine speed N decreases from the high idle speed NH} to the low idle speed N _L. On the other hand, the low-speed running map M2 sets the control output value C to the minimum value C _{0 as the engine speed N decreases from the high idle speed NH} to the low idle speed N _L. It is set to increase from a larger C _W to a maximum value C _MAX at a smaller increase rate than the control output value C of the standard map M1.

8 (b) and 8 (c) show that the control output value C (current value applied to the solenoid) of the pump control proportional valve 8 is changed according to the change of the engine rotation speed N based on the maps M1 and M2. cases were, there is shown a variation of the pressure on the load sensing valve 7, the change in the control pressure P _C at the time of the graph P _{C 1} is the normal mode set in FIG. 8 (b), the graph P _{C 2} is low speed shows the change in the control pressure P _C of the mode is set, a change in the target differential pressure ΔP in the graph ΔP1 is normal mode is set in FIG. 8 (c), the graph ΔP2 is the change in the target differential pressure ΔP of setting the low-speed traveling mode show.

In the high idle rotation, when the normal mode is set, the control output value C is the minimum value C ₀ , so that the control pressure _CC is 0. Therefore, the target differential pressure ΔP becomes the maximum target differential pressure ΔP ₀ . On the other hand, also during high idling rotation, low speed running mode is set by a large C _W than the minimum value C ₀ of the control output value C, the control pressure P _C of the large value P _CW is generated than 0 .. By applying this control pressure P _CW , the target differential pressure ΔP becomes ΔPW smaller than the _{maximum target differential pressure ΔP 0.}

That is, during high idle rotation, the control pressure _CC is set to 0 when the normal mode is set, deceleration control is not performed, and the control pressure P _CW is added when the low speed running mode is set, and deceleration control (that is, target) for all actuators is performed. (Reduction of the required flow rate ratio Rq) is to be performed.

On the other hand, during low idle rotation, as described above, in _{order to reduce the target supply flow rate ratio Rq to N L} / _{NH (<1) when the normal mode is set, the maximum value C MAX of the} control output value C on the map M1. _Is determined, the control pressure _CC is set to the maximum value P CMAX, and the target differential pressure ΔP is set to the minimum target differential pressure ΔP _MIN . Therefore, during this low idle rotation, the target supply flow rate ratio Rq is common (that is, Rq = _NL / _NH ) even when the low-speed running mode is set, and the low idle rotation number _NL on the map M2 is set. Like the C _MAX corresponding control output value C, the control pressure P _C to the maximum value P _CMAX, the target differential pressure [Delta] P as a minimum target differential pressure [Delta] P _MIN, are the normal mode setting and performs a common deceleration control ..

At the time of low idle rotation, the control output value C (= C _MAX ) on the standard map M1 and the control output value C on the low speed travel map M2 may be different values. In this case, the control output value C may be different. By switching the mode between the two modes during low idle rotation, the control pressure _CC changes, the target differential pressure ΔP changes, and the target required flow rate ratio Rq changes.

FIG. 9 is a diagram showing the effect of driving the traveling motors 23 and 24 on the supply flow rate Q to the traveling motors 23 and 24 by switching the mode between the normal mode and the low speed traveling mode. In any mode, it is assumed that the operation amount of the traveling operation levers 33a and 34a is set to the maximum (the spool stroke S of the directional control valves 33 and 34 is set to the maximum value _SMAX).

At the time of high idle rotation, in the normal mode, _{the target differential pressure ΔP MAX} in the load sensing valve 7 is achieved in the _{state where the control pressure CC} is not applied (that is, the state where the “deceleration control” is not performed) based on the standard map M1. That is, the tilt angle of the movable swash plate 1a is determined with the target required flow rate ratio Rq = 1, and the movable swash plates 23a and 24a are set to the normal speed position (small capacity position) to the traveling motors 23 and 24. The supply flow rate Qn of the above _{satisfies the required flow rate Qt R} for the traveling motors 23 and 24 (Qn = Qt _R ).

Similarly, in the high idle rotation mode, in the low speed running mode, the control output value C is set to C _{W , the control pressure P CW} is applied to the load sensing valve 7, and the target differential pressure ΔP is the control pressure P _C. It becomes ΔPW lower than the specified differential pressure ΔP _{0 in the} absence of, and the value of the target required flow rate ratio Rq is set to a value Rqw _H (<1) smaller than the value 1 in the normal mode, and this target required flow rate ratio Rqw. _The movable swash plate 1a is tilted so as to satisfy H, and the supply flow rate Qw to the traveling motors 23 and 24 becomes _{Qw H} (= Qt _R × Rqw _H ) smaller than _{Qt R when the normal mode is set.}

Low speed map M2 is determining the control output value _{C (C 0 <C <C} MAX) in response to any engine speed _{N M} between the high idling speed _{N H} and a low idle speed _{N L} has become one of the target subjected main flow ratio Rq obtained by the control pressure P _C is generated by the control output value C is in the normal mode, the target engine speed (optional engine speed at that time Moreover the reduced value _{Rqw (<N M / N H} ) from the value _N M / _{N H} obtained in accordance with the N _M). The movable swash plate 1a is tilted so as to satisfy this target required flow rate ratio Rqw, and the supply flow rate Qw to the traveling motors 23 and 24 is the supply flow rate Qn (corresponding to the engine rotation speed N when the normal mode is set). = from _{Qt R × N M / N H} ), further decreases, and Qn × RQW.

The target subjected main flow ratio Rqw = N L _/ N _H becomes at the time of low idle rotation, depending switching between the normal mode and the low speed mode (switching capacity of the travel motor 23, 24) as the supply flow rate QL is not changed There is.

In this way, switching from the standard map M1 to the work travel map M2 originally corresponds to an arbitrary engine speed N as an effect appearing on the supply flow rate characteristics of the hydraulic actuators (particularly the travel motors 23 and 24). The value obtained by correcting the target required flow rate ratio Rq, which is 1, using the standard map M1 (that is, by deceleration control), is further corrected (deceleration control) by using the work travel map M2. Means. At the time of high idle rotation, since the target required flow rate ratio Rq = 1 when the standard map M1 is used, as a result, it seems that "deceleration control" is performed for the first time by using the work driving map M2. Yes, during low idle rotation, the target required flow rate ratio Rq becomes a common value ( _NL / _NH ), and as a result, when switching from the standard map M1 to the work travel map M2, further deceleration control is possible. It will not be done.

The deceleration control (correction of the required flow rate ratio for the traveling motors 23 and 24) accompanying the mode switching to the low-speed traveling mode is performed by the traveling motor 23 with the operation amount of the traveling operation levers 33a and 34a and the same engine speed. -It has the effect of increasing the speed ratio (or the speed difference between the two traveling speeds) of the traveling speed when the movable diagonal plates 23a and 24a of the 24 are set to the normal speed position to the traveling speed when the movable diagonal plates 23a and 24a are also set to the low speed position. Further, this expansion of the speed ratio becomes remarkable in the region where the engine speed is high, and becomes maximum in the high idle speed.

Therefore, for example, when a high-speed engine is provided in order to increase the road traveling speed of the excavation turning work machine 10, in _{the engine high-speed range near the high idle speed NH} , the movable diagonal plate is set in the normal mode. Regarding the drive of the traveling motors 23 and 24 with the 23a and 24a set to the normal speed position (small capacity setting), deceleration control is not performed (target required flow rate ratio Rq = 1), or the rate of decrease in the target required flow rate ratio Rg is set. By keeping it small, the drive speed of the drive sprocket 11b can be increased (running speed is increased) by the amount of increase in the engine rotation speed in this region, while in the low-speed running mode, the low-speed position of the running motors 23 and 24 is set. In addition to the decrease in output speed due to switching to (large capacity setting), deceleration control, that is, by correcting the target required flow rate ratio Rq so that it is even lower than that in the normal mode setting, the hydraulic pump Since the control is performed to switch the tilt angle of the movable swash plate 1a of 1 to the decreasing side, the increase in engine rotation speed and the increase in hydraulic pump capacity are offset, and the excavation turning work machine at low speed makes it easy to work as before. 10 can be run.

The movable diagonal plates 23a and 24a of the traveling motors 23 and 24 are used as the traveling motors 23 and 24 in order to increase the difference between the traveling speed when the traveling speed is set to the normal speed position and the traveling speed when the traveling motors 23 and 24 are set to the low speed position. It is conceivable to change the angle difference between the low-speed position and the normal speed position of the movable swash plate 23a / 24a of the hydraulic motor, but the movable slop plate of the hydraulic motor is designed according to a certain standard, and both positions If you want to change the angle difference, you need to change the setting, which is costly. In this respect, the deceleration control only needs to change the map related to the control output value C by using the existing pump control proportional valve 8, so that the cost does not increase.

Note that the deceleration control is for changing the tilt angle of the movable swash plate 1a of the hydraulic pump 1 by adding a control pressure P _C to the load sensing valve 7 to increase side, as described above, for all the actuators, It has the effect of lowering the required flow rate ratio.

Here, regardless of whether the movable diagonal plates 23a / 24a are in the normal speed position or the low speed position, the traveling motors 23/24 are not in the driving state based on the traveling detection signal from the traveling detecting means 53 described above. If it is determined, the excavation swivel work machine 10 is set to the normal mode, so that the drive of other hydraulic actuators while the excavation swivel work machine 10 is stopped, that is, the boom cylinder 20, the arm cylinder 21, and so on. Regarding the drive of the bucket cylinder 22 and the like, the supply flow rate is controlled by the control of the control output value C based on the standard map M1 according to the engine rotation speed.

In other words, only when the movable swash plates 23a and 24a are set to the low speed position and the traveling motors 23 and 24 are actually driven to drive the excavation turning work machine 10 at low speed, the supply flow rate to the traveling motors 23 and 24 is low. It is controlled by the travel map M2, and all other actuators are driven by the standard map M1 unless the travel motors 23 and 24 are driven while the other actuators are driven during the low-speed travel. It is controlled by the supply flow rate and operates at the operating speed assumed in the normal mode.

In relation to the deceleration control corresponding to the capacity switching of the traveling motors 23 and 24, in FIG. 10, the lever operating amount of the traveling motors 23 and 24 (the operating amount of the traveling operation levers 33a and 34a) during high idle rotation is shown. _{That is, the characteristics of the required flow rate Qt R} and the supply flow rate Q with respect to the spool stroke S of the direction control valves 33 and 34 are shown. Required flow rate Qt _R is increased as the spool stroke S increases, the maximum value _{Q RMAX} at the maximum stroke _{S MAX.} In the normal mode in which the movable swash plates 23a and 24a are set to the small tilt angle (small capacity) position (normal speed position), the required flow rate ratio is 1 because there is no deceleration control, and the supply flow rate Qn is the required flow rate Qt _R. Match. On the other hand, in the low-speed running mode in which the movable swash plates 23a and 24a are set to the large tilt angle (large capacity) position (low-speed position), the required flow rate Qt _R has a constant ratio of less than 1 due to the effect of deceleration control (described above). In the embodiment, the amount is multiplied by _{Rqw H).} That is, when the spool stroke S of the maximum stroke _{S MAX,} the _{Qw MAX = Q RMAX × Rqw H} . This correspondence is maintained regardless of the state of the operation amount (spool stroke S), and even when the deceleration control is applied, the supply flow rate Qw of the pump in the low speed running mode increases as the lever operation amount increases. , The operating speed of the traveling motors 23 and 24, that is, the rotational speed of the drive sprocket 11b also increases.

As described above, the excavation turning work machine 10 according to the present application is a hydraulic machine provided with a plurality of hydraulic actuators driven by the oil discharged from the variable displacement hydraulic pump 1 driven by the engine E. pump control system 5 of the control device, at the time of driving the respective hydraulic actuators, to control the flow rate of the oil discharged from the hydraulic pump 1 so as to satisfy the required flow rate Q _R of the hydraulic actuator, and the change in the engine speed N in response, it is configured to correct the target value Rq ratio (Q / Q _R) of the supply flow rate Q with respect to the required flow rate Q _R of the hydraulic actuators. The plurality of hydraulic actuators include traveling motors 23 and 24 which are hydraulic motors for traveling of the excavation turning work machine 10 and whose capacities can be switched and set to at least two different capacities. Pump controller 5, in addition to the change in the engine rotational speed N, in accordance with the switching capacity of the travel motor 23, 24, the target ratio of the supply flow rate Q (Q / Q _R) for the required flow rate Q _R of the hydraulic actuators It is configured to correct the value Rq.

The plurality of hydraulic actuators, through the meter-aperture directional control valve provided in each separate, which discharge oil from the hydraulic pump 1 is supplied, the required flow rate Q _R of each actuator, each directional control It is defined by the opening degree of the meter-in throttle of the valve. Load sensing pump control system 5 (load sensing) where, for the differential pressure ΔP between the load pressure P _L the discharge pressure P _P and supply oil to the respective hydraulic actuators oil discharged from the hydraulic pump 1 has possessed total A common target value is set for the actuators, and the flow rate of the discharge oil of the hydraulic pump is controlled so as to achieve the target value of the differential pressure ΔP for all hydraulic actuators. By correcting the target value of the differential pressure [Delta] P, the correction of the target values Rq of said ratio in response to changes in the engine rotational speed N (Q / Q _R), and, in the switching capacity of the travel motor 23, 24 and corrects the target value Rq of the ratio of the response to _(Q / Q _R).

The load-sensitive pump control system 5 generates a control pressure _CC for changing the target value of the differential pressure ΔP by the secondary pressure of the pump control proportional valve 8 which is an electromagnetic proportional valve. A plurality of maps are stored as a correlation map of the control output value C as the current value applied to the pump control proportional valve 8 with respect to the engine rotation speed N. The plurality of maps include two or more maps M1 and M2 corresponding to each of the at least two-step capacity settings of the traveling motors 23 and 24.

The two or more maps M1 and M2 include a standard map M1 corresponding to a small capacity setting of the traveling motors 23 and 24, and a low-speed traveling map M2 corresponding to a large capacity setting of the traveling motors 23 and 24. When it is confirmed that the traveling motors 23 and 24 are actually driven at the time of setting the large capacity of the traveling motors 23 and 24, the discharge oil of the hydraulic pump 1 using the low speed traveling map M2 is used. The flow rate is controlled, and other than that, the flow rate of the discharged oil of the hydraulic pump 1 is controlled by using the standard map M1.

With the pump control system 5 of the excavation turning work machine 10 as described above, the ratio (speed ratio) of the output speed of the traveling motors 23 and 24 when the large capacity is set and the output speed when the small capacity is set can be changed. That is, assuming that the operation amount (spool stroke S) of the directional control valves 33 and 34 for the traveling motors 23 and 24 is constant at a constant engine speed, the output speed difference due to the switching of the capacitance is obtained. , The value may be different from the value specified by the standard of the hydraulic motor as the traveling motor 23/24.

Therefore, for example, when a high-speed engine is provided in order to increase the road traveling speed of the excavation turning work machine 10, the high idle rotation speed (maximum engine rotation speed) increases, so that the traveling motor 23・ When setting a small capacity of 24, it is possible to realize a high speed on the road by rotating the engine at high speed, while when setting a large capacity, work without being affected by the increase in high idle rotation speed due to the increase in engine rotation. The output speed of the hydraulic motor can be kept low so as to have a conventional running speed that is easy to control.

The speed ratio can be changed by changing the set positions of the movable swash plates 23a and 24a of the traveling motors 23 and 24. In this case, the complicated mechanism for positioning the movable swash plates 23a and 24a is used. There is a possibility that the design will be changed and the cost will be high. However, the pump control system 5 according to the present application, that corrects the target value of the differential pressure ΔP between the discharge pressure P _P and the load pressure P _L, the structure adopted in the existing load sensing pump control system , It only needs to be used when switching the capacity of the traveling motors 23 and 24. For example, the structure is such that two or more maps corresponding to each capacity setting of the traveling motors 23 and 24 are stored. Therefore, it is possible to provide a pump control system 5 that achieves the above-mentioned effects at low cost.

Also, correction of the target value of the differential pressure ΔP is, so controls the flow rate of the oil discharged from the hydraulic pump 1, not only the travel motors 23, 24, for all the actuators, the supply flow rate Q with respect to the required flow rate Q _R so that the correction of the target value Rq ratio _(Q / Q _R) is applied. In this case, if the output speed of the traveling motors 23 and 24 when the large capacity is set is suppressed to a low level as described above, not only the traveling speed can be suppressed to a low level but also the driving speeds of the other actuators are controlled by the traveling motors 23 and 24. As the capacity is switched to the larger capacity setting, the drive speed becomes lower and the work efficiency drops.

In this regard, when the large capacity of the traveling motors 23 and 24 is set, the low speed traveling map M2 for the large capacity setting is used only when it is confirmed that the traveling motors 23 and 24 are actually driven. As a result, other actuators can be driven at the drive speed corresponding to the small capacity setting of the travel motors 23 and 24, regardless of the capacity switching of the travel motors 23 and 24, and only the travel speed. While keeping it low, it is possible to perform efficient work that is the same as when setting a small capacity.

INDUSTRIAL APPLICABILITY The present invention is applicable not only to the excavation and turning work machine described above, but also as a control device for any hydraulic machine in which a load-sensing hydraulic pump control system is adopted.

Claims (1)

A control device for hydraulic machines equipped with multiple hydraulic actuators driven by oil discharged from a variable displacement hydraulic pump driven by an engine.
The control device controls the flow rate of the discharge oil of the hydraulic pump when each of the hydraulic actuators is driven, and at the same time, the discharge oil of the hydraulic pump is supplied according to the assumed flow rate of the hydraulic actuator for each engine rotation speed. A control device for a hydraulic machine, characterized in that the target value of the ratio of the supply flow rate to the required flow rate of each hydraulic actuator is corrected by controlling the flow rate.

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