JPS6329076B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a depth detection device that is attached to a pit excavator such as an earth drill or a bucket-type continuous wall machine in which the excavation tool is supported by a wire rope.

For earth drills and bucket type wall machines,
In order to make this repetitive work easier, since a pit is excavated by repeatedly taking earth and sand into a bucket, pulling it up to the ground, and discharging it,
As shown in FIG. 1 for an earth drill, a system is adopted in which a bucket 3 is supported by a crane 1 with a wire rope 2. Note that the bucket 3 is attached to the lower end of the Kelly bar 4, and the Kelly bar 4 is connected to the Kelly bar drive device 6 installed on the front frame 5.
The upper end is connected to the wire rope 2 via a swivel joint 7, and the kelly bar 4 and bucket 3 (i.e., excavation tool) are rotated by operating the kelly bar drive device 6. It's summery. Further, the wire rope 2 is hung on a sheave 9 at the upper end of the boom 8,
The bucket cart 3 is raised and lowered by being extended and retracted by the winch 10.

In such a pit excavator, the lowering of the bucket is controlled by the brake of the winch 10 so as to reduce the time required for vertical movement of the bucket to take in and discharge soil into the bucket 3. This is often done by a so-called free-haul operation in which the excavator is released and the clutch is released to release the power transmission and the excavator is lowered by its own weight. However, when lowering the bucket through this free hole operation, if the free hole operation was performed continuously until the bucket reached the bottom 11a of the hole 11, the bucket would violently collide with the bottom 11a of the hole, damaging the drilling tool. There is a risk of causing Therefore, conventionally, a depth indicator is provided in the operator's cab to display the depth of the drilling tool, and the operator knows the depth of the drilling tool by looking at the value displayed on the depth indicator, and the operator approaches the hole bottom 11a. At times, the brakes are applied to prevent the drilling tool from colliding violently with the bottom of the hole.

Conventional depth detectors use methods such as rotary encoders, proximity switches, or photoelectronic switches to detect the amount of rotation of the sheave 9, which rotates in proportion to the amount of payout of the wire rope 2 that supports the excavation tool. It is being However, these methods had the following drawbacks. In other words, in the case of a rotary encoder, it is necessary to provide a mechanical transmission mechanism to extract the rotation of the sheave, which poses problems in that care must be taken in maintenance to prevent wear and tear, and the mechanism becomes complicated. It was hot.

Further, in the case of a proximity switch, since pulses are generated by cutting off the magnetic field generated by the switch by a proximity body, it is necessary to attach the proximity body as a protrusion to the outer periphery of the sheave.
Therefore, since the installation diameter is larger than the outer diameter of the sheave, the rope stopper, which is installed with a slight gap from the outer diameter of the sheave, must be modified to prevent the rope from jumping out of the groove of the sheave. It was impossible. In order to avoid this, it is possible to install a ring on the side of the sheave and attach the proximal object on this ring, but in this case, it is necessary to separate the proximal object from the side of the sheave to a position where it will not be affected by the sheave. Therefore, the width of the sheave including the proximate object becomes large, and there is a risk of interference with the adjacent sheave. Furthermore, the detection surface of the proximity switch is in an environment where iron powder and chips are likely to adhere, which may lead to malfunction. Furthermore, proximity switches generally have a slow response speed and are said to be unable to follow responses of 300 CPS or more, so in order to cope with the fast rotation of the sheave during freehaul, the distance between the proximity switches must be widened to reduce the amount of pulse generation. It was necessary to hold it down, which caused a problem in detection accuracy.

In addition, in the case of a photoelectronic switch, holes are drilled in the sheave at equal intervals, and the emitter and receiver are placed on both sides of the sheave, which limits installation.In addition, the number of holes drilled in the sheave is limited in order to improve detection accuracy. If it increases, there is a drawback that the strength of the sheave decreases.

SUMMARY OF THE INVENTION In view of the above drawbacks, it is an object of the present invention to provide a depth detection device for a pit excavator that has a detection means that is advantageous in terms of maintenance, installation, detection accuracy, etc.

To achieve this object, the present invention provides a depth detection device for a pit excavator in which a drilling tool is supported by a wire rope, in which a side surface of a sheave rotated by the movement of the wire rope is made of magnetic material. A ring is integrally provided, and a plurality of permanent magnets are disposed at equal intervals in the circumferential direction by embedding a part of the permanent magnets in the outer circumference of the ring, and the The present invention is characterized in that a wire rope movement amount detector and a movement direction detector, which are comprised of switches that are activated by the proximity of a permanent magnet, are mounted at a distance from the permanent magnet.

An embodiment of the present invention will be described below with reference to the drawings.
FIG. 2 shows the overall configuration of the detection device including the depth display device, 13 is a movement amount detector for detecting the amount of movement of the wire rope 2, and 14 is a movement amount detector for detecting whether the wire rope 2 is being paid out or not. A moving direction detector 15 is a discrimination circuit that receives a signal from the moving direction detector 14 and determines whether the wire rope 2 is let out or retracted. 16 is a calculation device that calculates the depth of the excavation tool; 3
Reference numeral 1 denotes a unit length setting device constituted by a digital switch that can arbitrarily set the amount of movement of the wire rope 2 per pulse interval of the movement amount detector 13; 13
an on-off digital signal from the discriminator circuit 15, a signal from the discrimination circuit 15, and the unit length setter 31.
The device is configured to calculate the depth of the excavating tool in response to signals from the excavator. 20 is a reset button for setting the value of the detection device 16 to zero in order to clarify the depth measurement reference point.

The indicator for displaying the depth of the excavation tool may be provided with either a digital indicator or an analog indicator, but in this embodiment, a digital indicator that receives a signal from the calculation device 16 and displays a numerical value is used. Total 17
and a digital-to-analog converter 1 that converts the digital signal from the arithmetic unit 16 into an analog signal.
8 and an analog display 19 that receives an analog signal from the digital-to-analog converter 18 and displays the depth.Depth can be recognized by the analog display 19 during free hole, and when the excavation tool is stationary, the digital The display meter 17 allows accurate depth reading.

In addition, in this embodiment, in order to reduce the burden on the operator in recognizing the depth of the drilling tool during freehole, the brake operation is performed when the brake operation is required, that is, just before the drilling tool reaches the bottom of the hole, or when the When a type kelly bar is used, a device 25 is provided which issues an alarm immediately before each stage kelly bar is fully extended and the retaining protrusions collide with each other, or immediately before the outermost kelly bar (outer kelly bar) collides with the upper part of the kelly bar drive device. We are prepared.

To explain the device 25 for issuing the alarm, 32a, 32b, and 32c are depth setters for setting arbitrary depths such as the depth of the hole bottom and the unit Kelly bar length, and 33a, 33b, and 33c are the depth setters 32a, Comparators 34a, 34b, and 34c receive signals from each comparator and compare whether the depth has become shallower by an appropriate depth l set in consideration of brake operation than the depth L set by 32b and 32c. When the depth of L-l) is reached, the lamps 35a, 35b, 3 corresponding to each depth are turned on.
The buzzer/lamp drive circuit instructs the lamps 5c to blink and sounds the buzzer 36, and also instructs the lamps 35a, 35b, 35c corresponding to each depth to turn on when the depth reaches L, and instructs the buzzer 36 to stop. It is.

Therefore, the feature of the present invention is the configuration related to the movement amount detector 13 and the movement direction detector 14, in which the wire rope 2 is hung as shown in FIGS. 1, 3, and 4. A ring 50 made of magnetic material is attached to the side of the sheave 9 at the tip of the boom 8.
be provided integrally. As for the structure in which the ring 50 is provided, in addition to the structure in which it is integrally molded with the sheave 9 or the structure in which it is welded as shown in the illustrated example, various structures such as a structure in which it is attached with bolts or a structure in which it is fitted can be adopted. A plurality of permanent magnets 24 are disposed on the outer periphery of the ring 50 at equal intervals in the circumferential direction and partially embedded (except for the surface). The movement amount detection switches 13a, 1 are activated when the permanent magnet 24 approaches.
3b, and movement direction detection switches 14a, 14b.
Attach the sheave to the non-rotating part near the sheave with a gap between them so that they do not come into contact with the permanent magnet.

In this embodiment, switches 13a, 13
b, 14a, 14b attached to the bracket 40 is pivotally connected to the shaft 37 of the sheave 9, and the bracket 40 is
0 is attached to a screw seat 38 welded to the boom 8 by fixing it with a bolt 39.
Such switches 13a, 13b, 14a, 1
4b mounting structure, the gaps between these switches and the permanent magnet 24 are inevitably fixed, so errors in assembly are less likely to occur, and the bracket 4
Even if the bolt 39 fixing the switch 0 loosens, the bracket 40 is pivotally attached to the shaft 37, so the permanent magnet 24 and switches 13a, 13b, 14a, 14b
There is no deviation in the gap between the two switches and the relative positions of these switches, and there is no problem with depth detection.

Further, as in this embodiment, the outer diameter of the ring 50 is
By making the sheave 9 or the sheave 9' attached coaxially with the sheave 9' to be equal to or smaller than the sheave 9, there is no need to modify the retainer 41 of the rope hanging thereto into a special shape.

As mentioned above, if the structure is such that the permanent magnet 24 is embedded in the ring 50 made of magnetic material and the switch is operated by the permanent magnet, the magnetic field is
Since it only occurs in the vicinity of In this embodiment, in order to obtain higher detection accuracy, permanent magnets 24 are arranged in two rows on the outer periphery of a ring 50 provided on one side of the sheave 9. Note that one row of permanent magnets may be arranged on each side of the sheave 9. Furthermore, although the mounting intervals of the permanent magnets 24 in the same row are equal, the mounting intervals of the permanent magnets in different rows are relatively shifted by half a pitch to prevent mutual interference between the permanent magnets in different rows. The switches 13a and 13b for detecting the amount of movement are arranged in different columns, and when the switches 13a and 13b are on one permanent magnet 24 in one column, the switches 13a and 13b are arranged in different columns.
b, 13a are attached to the bracket 40 so as to be located between the two permanent magnets in the other row. Therefore, as shown in FIG.
The switches 13a and 13b are operated alternately by wrapping the operating time _T1 , and the switches 13a and 13b
The total number of pulses obtained by the operation of the wire rope becomes a signal indicating the amount of movement of the wire rope.

On the other hand, the switches 14a and 14b constituting the moving direction detector 14 are mounted on the bracket 40 so that one of them operates earlier than the other depending on the direction of rotation of the sheave 9. That is, when the sheave 9 rotates clockwise (wire rope payout direction) in FIG. 3, one switch 14 is turned off as shown in FIG. 6A.
The other switch 14b operates with a delay in response to the operation of switch a, and after a time lapse of _T2 , switch 14a
operation stops. When the sheave 9 rotates in the counterclockwise direction (wire rope retracting direction) in FIG. 3, switch 1 is turned
The switch 14a is activated with a delay with respect to the activation of the switch 4b, and after a time lapse of _T2 , the operation of the switch 14b is stopped. In this way, the switches 14a, 1
The moving direction of the wire rope is determined depending on which of the wire ropes 4b is activated first.

Therefore, the discriminating circuit has switches 14a and 14.
It is determined whether there is a time lapse in the operation of the switch and switch b, and a comparison is made to see which switch operates faster, and the output signal is changed based on the comparison result.

Further, as shown in FIG. 7, the arithmetic device 16 is composed of an integrating circuit 16a and an arithmetic circuit 16b, and when the output signal of the discriminating circuit 15 indicates wire rope payout, the integrating circuit 16a detects the movement amount detector 13 Each time a pulse is applied, 1 is added to the value stored up to that point; on the other hand, when the output signal of the discrimination circuit 15 represents wire rope renormalization, the value is added every time a pulse is applied. It is configured to perform an operation of subtracting 1. Note that the discrimination circuit 15 incorporates a pulse chattering prevention circuit with a large time constant. The arithmetic circuit 16b is a unit length setter 3.
In response to the value of the wire rope movement amount s per pulse set by 1, a calculation is performed to convert the value of the integration circuit 16a into the depth of the excavation tool.
The depth L is calculated using the following formula.

L=p×n×s/m Where, p: Amount of pulse generation per one revolution of sheave 9 n: Amount of rotation of sheave 9 s: Amount of wire rope movement per one pulse s=πD/p [D: Sheave 9 pitch circle] (Refer to Figure 3) m: Wire rope multiplier The digital display meter 17 and analog display meter 19 that display the calculated value are displayed in the wire rope feeding direction with respect to the zero scale position. The direction of renormalization is displayed as - and + as the direction of renormalization. Normally, the setting is zero when the excavation tool 3 such as a bucket is located on the ground surface, so the depth of the excavation hole is displayed as -, and the height when the excavation tool is lifted above the ground is displayed as +. Therefore, the display range of the analog display meter 19 is wider for - than for +.

As shown in FIG. 8, the digital display meter 17 and the analog display meter 19 are installed on the same panel surface of one case 21, and the case 21
It is installed in the instrument panel of the driver's cab as shown at 30 in the figure. The case 21 also includes a power on switch 22.
, the power lamp 23, and the reset button 2.
0, depth setters 32a, 32b, 32c, lamps 35a, 35b, 35c, and a buzzer 36 are attached, and the arithmetic unit 16, the discrimination circuit 15,
Digital-analog converter 18, unit length setter 31, comparators 33a, 33b, 33
c. Buzzer/lamp drive circuit 34a, 34b, 3
4c is built into the case 21.

Next, the operation of this embodiment will be described.

When the excavating tool is lowered by free hole operation, the operating time relationship of the switches 14a and 14b of the movement direction detector is as shown in FIG.
a, the integration circuit 16a performs an operation of increasing the value by a (-) value ((-) addition operation) using the pulse from the movement amount detector 13, and the arithmetic circuit 1
6b converts the integrated value into depth, and the digital value is displayed on the digital display meter 17, and at the same time, the analog quantity obtained by the digital-to-analog converter 18 is displayed on the analog display meter 19.
In this case, the value displayed on the digital display meter 17 fluctuates rapidly and is difficult to read, but the depth can be read using the analog display meter 19.
Therefore, in the case of an earth drill like this example, the drilling tool is lowered at high speed without applying any brake until it reaches the bottom of the hole, and when the drilling tool approaches the bottom of the hole, the brake is applied to stop it. You can easily land it on the bottom of the hole. This will be explained in detail below. In other words, to determine whether or not the bottom of the hole has been approached, if the previous excavation depth is set in the depth setter 32C, the lamp 35C will flash at a depth that is shallower than this by a preset depth l.
You can tell because the buzzer 36 starts sounding. On the other hand, in the case of a bucket type continuous wall machine, the lamp 3
When 5C flashes and the buzzer 36 starts to sound, apply the brake to temporarily stop the descent of the excavating tool to avoid unnecessary impact to the bottom of the hole, and then drop the excavating tool again using free hole operation to lower the bucket. Dig your nails into the bottom of the hole. In either case, when the bucket is filled with earth and sand, it is lifted to the ground, and the value of the depth setter 32C is changed to the depth at this time.

In addition, in the case of an earth drill or a Kelly type bucket wall machine, the Kelly bar 4 is usually a multi-stage telescoping type, so as each Kelly bar extends, the protrusions provided on each Kelly bar may catch on each other and sometimes fall out. On the other hand, if it is dropped in a free hole, it may collide violently with the protrusion, causing cracks and damage. For this reason, if the operator does not have a depth gauge, he or she applies the brake by checking the amount of unwinding of the winch rope, and even if the operator has a depth gauge, he or she must memorize the depth that is slightly shallower than the engagement part. In addition, there was a risk of misremembering, leading to operational errors. However, since the positions where these protrusions engage are determined, the engagement positions of each stage are set in advance by the depth setters 32a, 32.
If set in b, the lamp 35a will blink at a depth l shallower than the engaging portion, as explained above.
Since the buzzer 36 starts sounding, it is possible to lower the robot slowly while applying the brake, thereby alleviating the impact at the time of engagement. After being engaged, the mode is switched to free hole again, but at this time the lamp 35a turns on to indicate that the initially set depth has been passed, and the buzzer 36 stops sounding. Similarly, even at the depth set by the depth setter 32b, the lamp 3
5b and the buzzer 36 operate.

When the excavating tool is pulled up to the ground, the operating time relationship of the switches 14a and 14b of the moving direction detector is as shown in FIG. Therefore, the integration circuit 16a performs an operation of subtracting the value by a (-) value ((-) subtraction operation) using the pulse from the movement amount detector 13.

Normally, the zero reference point for depth is placed on G and L, but when the drilling tool is pulled up from the bottom of the hole and passes through the zero reference point, the internal calculation is a (-) subtraction operation. , the digital display meter 17, and the analog display meter 19 apparently perform a (+) addition operation. For example, if the voltage value when a pulse corresponding to 100 m in absolute value is generated is 10V, if the generated voltage is not returned to 0V when the reset button 20 is pressed, but the base voltage value is set to 2V. A voltage of 0 V is generated at a depth of (+) 20 m, and a voltage of 10 V is generated at a depth of (-) 80 m, making it possible to display as described above.

Also, if the zero reference point of depth is placed on G and L,
For example, with wire rope 2 stretched, bucket 3
When the machine is lowered to the ground, check whether the value displayed on the digital display meter 17 is out of order due to slippage between the wire rope 2 and the sheave 9. If an error has occurred, press the reset button 20 and reset the arithmetic unit. 16
Reset.

Furthermore, if the value of φD, which is the PCD of the sheave 9 shown in FIG.

As described above, according to the present invention, a plurality of permanent magnets are partially embedded in the outer periphery of a ring made of magnetic material that is integrally provided on the side surface of a sheave, and are arranged at equal intervals in the circumferential direction. However, a movement direction detection switch and a movement amount detection switch that are activated by the proximity of the permanent magnet are attached to the non-rotating part near the sheave, and since the magnetic field is generated only in the vicinity of the permanent magnet, the permanent magnet They can be mounted close to each other, and even if some iron powder or chips adhere to the permanent magnet, it will have less effect on switch operation than in the case of a proximity switch, resulting in high detection accuracy. Non-contact detection becomes possible.
Further, according to the present invention, since the switch is actuated by a permanent magnet, the response speed is excellent, and the switch can be fully adapted to free-haul operation. Further, in the present invention, since the rotation of the sheave, that is, the amount of movement of the wire rope can be detected in a non-contact manner without using a mechanical transmission mechanism, there is no need for maintenance to prevent wear and tear on the transmission mechanism.

In addition, in the present invention, the permanent magnet is embedded in the outer periphery of the ring that is integrally provided on the side of the sheave, so it is possible to prevent the permanent magnet from being damaged when the sheave is attached and detached, and it is also possible to permanently Since the outer diameter of the magnet attachment part can be reduced, there is also the advantage that there is no need to modify the rope stopper to have a special shape. Furthermore, since the present invention operates the switch using a permanent magnet, the overall width of the sheave is smaller than that using a proximity switch, and the strength of the sheave is reduced compared to a switch that uses a proximity switch. It has the advantage that it can be implemented without deterioration.

[Brief explanation of drawings]

Fig. 1 is an overall side view of an earth drill to which the present invention is applied, Fig. 2 is a block diagram showing an embodiment of the present invention, and Fig. 3 is an example of a movement amount detector and a movement direction detector of the embodiment. Layout diagram showing , Figure 4 is the 3rd
5 is a pulse waveform diagram illustrating the operation of the movement amount detector of this embodiment, and FIG. 6 is a pulse waveform diagram illustrating the operation of the movement direction detector of this embodiment. , FIG. 7 is a block diagram showing an example of the configuration of the arithmetic unit and discrimination circuit in this embodiment, and FIG.
The figure is an external view of the display section of this embodiment. 2...Wire rope, 3...Bucket, 4...Kerry bar, 9...Sheave, 13...Movement amount detector, 13a,
13b...Switch, 14...Movement direction detector, 14
a, 14b...Switch, 24...Permanent magnet, 50...
ring.

Claims (1)

[Scope of Claims] 1. In a depth detection device for a pit excavator in which a drilling tool is supported by a wire rope, a ring made of a magnetic material is integrally attached to the side surface of a sheave that is rotated by the movement of the wire rope. A plurality of permanent magnets are disposed at equal intervals in the circumferential direction by embedding a part of a plurality of permanent magnets in the outer circumference of the ring, and a plurality of permanent magnets are disposed in the non-rotating part near the sheave in the vicinity of the permanent magnet. 1. A depth detection device for a pit excavator, characterized in that a wire rope movement amount detector and a movement direction detector, each consisting of a switch operated by a wire rope, are mounted at a distance from a permanent magnet. 2. The depth detection device for a pit excavator according to claim 1, wherein the outer diameter of the ring is equal to or smaller than the outer diameter of the sheave.