JPH0144921B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an actuator drive circuit included in a hydraulic machine, and particularly to an actuator drive circuit in which one actuator is driven in a closed circuit using a plurality of hydraulic pumps.

FIG. 1 is a circuit diagram showing an example of this type of conventional actuator drive circuit. In these figures, 1 and 2 are hydraulic pumps, such as variable displacement pumps, and 3 is an actuator, such as a hydraulic cylinder, driven by these variable displacement pumps 1 and 2. 7, 8, 9, and 10 are switching valves, of which switching valves 7 and 8 are provided in the middle of a circuit that connects the hydraulic cylinder 3 and the variable displacement pump 1; It is provided in the middle of a circuit that connects the cylinder 3 and the variable displacement pump 2. Note that 3a is a conduit connecting the circuit including the variable displacement pump 1 and the circuit including the variable displacement pump 2, and 3b
is a hydraulic power source connected to this pipe line 3a. Also,
Pistons 11 and 12 are pump control valves that control the moving direction of the pistons 13 and 14, respectively.

Further, 4 is an operating device that outputs a signal to drive the hydraulic cylinder 3, and its lever portion is movable in ten directions and in one direction as shown by an arrow 5. For example, this operating device 4 outputs a signal indicating "1" when driving the hydraulic cylinder 3,
When the hydraulic cylinder 3 is not driven, a signal indicating "0" is output. And 6 is
Convert the signal output from the operating device 4 as appropriate,
Switching valves 7, 8, 9, 10 and pump control valve 1
A conversion device that outputs signals 1 and 12, for example, comparison,
It is composed of a microcomputer that has an intermediate processing device with arithmetic functions, a storage device, an input device, and an output device. The above-mentioned operating device 4 and conversion device 6 constitute actuating means for actuating the pump control valves 11, 12 and the switching valves 7, 8, 9, 10.

In the actuator drive circuit configured in this manner, the drive of the hydraulic cylinder 3 is controlled, for example, in accordance with the procedure shown in FIG.

That is, first, as shown in step 20, the conversion device 6 determines whether the signal output from the operating device 4 is "1". If this judgment is not satisfied, it means that the hydraulic cylinder 3 is not intended to be driven, and the process returns to the beginning. If the above judgment is satisfied, this means that the hydraulic cylinder 3 is intended to be driven, and the process moves to step 21. In step 21, the conversion device 6 determines whether the signal value of the signal output from the operating device 4 is positive. If the judgment in step 21 is satisfied, the process moves to step 22, and if it is not satisfied, the process moves to step 23.

In step 22, the switching valves 7, 8,
9 and 10, a signal to open these switching valves 7, 8, 9, and 10 is output, and at the same time, the conversion device 6 outputs a signal to open the switching valves 7, 8, 9, and 10, and at the same time, the converter 6 outputs a signal to open the switching valves 7, 8, 9, and 10, and at the same time, the converter 6 outputs a signal to open the switching valves 7, 8, 9, and 10. A signal is output to switch to the right position. With this, the variable displacement pump 1,
2 and the hydraulic cylinder 3 are brought into communication with each other, and the pistons 13 and 14 each move to the left in FIG. 1. Therefore, the pressure oil led from the hydraulic source 3b is sucked by the variable displacement pumps 1 and 2 through the pipe line 3a, and the pressure oil discharged from these variable displacement pumps 1 and 2 are combined, It is supplied to the rod side of the hydraulic cylinder 3, thereby causing the hydraulic cylinder 3 to operate in the direction of contraction. Note that after step 22, the process returns to the beginning.

In addition, in step 23, the switching valve 7,
8, 9, 10, these switching valves 7, 8, 9, 1
A signal to open 0 is output, and at the same time, the converter 6
A signal for switching the pump control valves 11, 12 to the left position in FIG. 1 is output from the pump control valves 11, 12. As a result, the variable displacement pump 1,
2 and the hydraulic cylinder 3 are brought into communication with each other, and the pistons 13 and 14 each move to the right in FIG. 1, contrary to the above. Therefore, the pressure supplied from the hydraulic source 3b is sucked by the variable displacement pumps 1 and 2 through the pipe line 3a,
The pressure oils discharged from these variable displacement pumps 1 and 2 are combined and supplied to the bottom side of the hydraulic cylinder 3, thereby operating the hydraulic cylinder 3 in the direction of extension. Note that after step 23, the process returns to the beginning.

In this way, the hydraulic cylinder 3 can be expanded and contracted by merging the pressure oil discharged from the variable displacement pumps 1 and 2.

By the way, in the conventional actuator drive circuit configured as described above, the operating direction of the actuator, for example, in the case of the hydraulic cylinder 3 shown in FIG. There are cases where it is desired to cause the actuator to vibrate.
For example, in the case of a hydraulic excavator used as a construction machine, this may be necessary to remove mud that has adhered to the bucket from the bucket, or
This occurs when rock is crushed using a bucket.

However, in the conventional actuator drive circuit described above, in order to cause such vibrations in the actuator, for example, in the hydraulic cylinder 3 shown in FIG. 1, the pump control valves 11, 1
2, the moving direction of the pistons 13 and 14 is changed, and thereby the discharge direction of the variable displacement pumps 1 and 2 must be changed. In other words, the operation direction of the hydraulic cylinder 3 is changed. of,
This has to be carried out by supplying pressure oil to the hydraulic cylinder 3 through the movement of the pistons 13 and 14, and therefore, the responsiveness to the switching operation of the operating direction of the hydraulic cylinder 3 is poor. Unable to generate vibrations. Therefore, for example, in the case of a hydraulic excavator, it is impossible to remove mud from the bucket or crush rocks due to the vibrations described above.

The present invention has been made in view of the actual situation in the prior art, and an object of the present invention is to provide an actuator drive circuit that can ensure excellent responsiveness to the switching operation of the actuation direction of the actuator.

To achieve this objective, the present invention comprises a closed circuit having one actuator, a plurality of hydraulic pumps that drive this actuator, and a switching valve interposed between these hydraulic pumps and the actuator. , equipped with an operating means for operating the switching valve, and provided with a switching device connected to the operating means and outputting a signal,
The actuating means operates a switching valve in response to a signal output from the switching device, a circuit that connects a discharge port of one of the plurality of hydraulic pumps with one port of the actuator, and one of the plurality of hydraulic pumps. a circuit communicating between another one of the hydraulic pump discharge ports and another one of the actuator ports;
It is configured to operate so that communication and disconnection are repeated alternately.

Hereinafter, the actuator drive circuit of the present invention will be explained based on the drawings. FIG. 3 is a circuit diagram showing one embodiment of the present invention. In order to simplify the explanation, FIG. 3 is drawn to correspond to FIG. 1 described above, and the same equipment and members as shown in FIG. 1 are designated by the same reference numerals.

In FIG. 3, a switching device 15 is connected to the converting device 6 and outputs a signal to the converting device 6 when switched to the ON state. The storage device of the conversion device 6 stores the cross-sectional area S1 on the bottom side of the hydraulic cylinder 3 and the cross-sectional area _S1 on the rod side.
Minute times t ₁ and t ₂ corresponding to S ₂ are stored, that is, times t 1 and _{t 2} that satisfy the relationship t ₁ /S ₁ =t ₂ /S ₂ are stored. Further, the central processing unit of the conversion device 6 counts the time T and compares this time T with the above-mentioned times t ₁ and t ₂ .

In one embodiment configured in this way,
For example, by the procedure shown in FIG.
drive is controlled.

That is, as shown in step 24, first, it is determined whether the switching device 15 of the converter 6 is in the ON state or not.
That is, it is determined whether a signal is being output from the switching device 15 or not. If this judgment is not satisfied, it means that it is not intended to cause vibration in the hydraulic cylinder 3, and as described above, the judgment and operation are performed according to steps 20 to 23, and the hydraulic cylinder 3 has two variable displacements. The expansion and contraction operations are performed by merging the pressure oil discharged from the pumps 1 and 2.

Then, if the judgment in step 24 is satisfied,
This is a case where it is intended to cause vibration in the hydraulic cylinder 3, and the process moves to step 25. This step 25
In step 26, the conversion device 6 outputs a signal to switch the pump control valve 11 to the left position in FIG. 3, and outputs a signal to switch the pump control valve 12 to the right position in FIG. Move. In addition, in step 25, by switching the pump control valves 11 and 12 to the left position and the right position, respectively,
The pistons 13 and 14 move to the right and left,
As a result, the variable displacement pumps 1 and 2 are in a state of discharging pressure oil at a constant flow rate Q in the leftward and rightward directions in the drawing, respectively.

Next, as shown in step 26, a signal is output from the conversion device 6 to the switching valves 7 and 8, and these switching valves 7 and 8 are opened. This allows the discharge port of the variable displacement pump 1 to communicate with one port of the hydraulic cylinder 3, that is, the bottom side, and the suction port of the variable displacement pump 1 and another port of the hydraulic cylinder 3, that is, the rod side. communicate. Therefore, the variable displacement pump 1 is connected from the hydraulic source 3b through the pipe line 3a.
The hydraulic cylinder 3 is driven in the direction of expansion by the pressure oil sucked into the cylinder.

Further, at the same time as the switching valves 7 and 8 are opened in step 26, the process moves to step 27, where the conversion device 6 starts counting the time T, and this time T is compared with a pre-stored time _t1 . This time T
When becomes equal to time _t1 , the process moves to step 28.
The working distance of the hydraulic cylinder 3 during this time is
t ₁ Q/S ₁ .

Next, as shown in step 28, the conversion device 6 outputs a signal to the switching valves 7, 8 to close these switching valves 7, 8, and the conversion device 6 outputs a signal to the switching valves 9, 10 to close these switching valves 7, 8. A signal to open the valves 9, 10 is output. As a result, the circuit connecting the discharge port of the variable displacement pump 1 to the bottom side of the hydraulic cylinder 3 and the circuit connecting the suction port of the variable displacement pump 1 to the rod side of the hydraulic cylinder 3 are cut off. On the other hand, the discharge port of the variable displacement pump 2 and another port of the hydraulic cylinder 3, that is, the rod side, communicate with each other, and a circuit connecting the suction port of the variable displacement pump 2 with the bottom side of the hydraulic cylinder 3 communicates with each other. Therefore, the hydraulic cylinder 3 is driven in the direction of contraction by the pressure oil sucked into the variable displacement pump 2 from the hydraulic source 3b via the conduit 3a. Further, at the same time as the switching valves 9 and 10 are opened in step 28, counting of time T starts, and this time T is compared with a pre-stored time _t2 . When this time T becomes equal to time _t2 , the process returns to the beginning. Note that the working distance of the hydraulic cylinder 3 during this time is t ₂ Q/S ₂ . Thereafter, similar operations are performed continuously during a short period of time.

In this way, in the above-mentioned embodiment, when it is intended to cause the hydraulic cylinder 3 to vibrate, the variable displacement pumps 1 and 2 are always in a state where they can discharge a constant amount, and the hydraulic cylinder 3 The switching operation of the operating direction is performed without intervening movement of the pistons 13 and 14, that is, in a very short period of time required to switch the switching valves 7 and 8 or the switching valves 9 and 10 for switching the operating direction of the hydraulic cylinder 3. Therefore, during the travel distance t ₁ Q/S ₁ = t ₂ Q/S ₂ , the hydraulic cylinder 3
It alternately contracts and expands to generate the desired vibration.

Therefore, when this embodiment is applied, for example, to a drive circuit for a bucket cylinder that rotates a bucket of a hydraulic excavator, it is possible to prevent the removal of mud attached to the bucket or the crushing of rocks by the bucket. This can be achieved by causing the cylinder to vibrate.

In the above embodiment, when generating vibration in the hydraulic cylinder 3, the conversion device 6 outputs a signal to switch the pump control valves 11 and 12 to the left position and the right position, respectively. The valves 11 and 12 may output signals for switching to the right and left positions, respectively.

Furthermore, in the above embodiment, the case was described in which the flow rate Q of the pressure oil discharged from the variable displacement pumps 1 and 2 was always constant. Therefore, the flow rate of pressure oil supplied to the bottom side of the hydraulic cylinder 3 is
Q ₁ , the flow rate of pressure oil supplied to the rod side is Q ₂ , the minute time t stored in advance in the storage device of the converter 6 is always constant, and tQ ₁ /S ₁ = tQ ₂ /S ₂
It may be configured to satisfy the relationship.

Furthermore, in FIG. 3, the system connecting the operating device 4, the converting device 6, the switching valves 7, 8, 9, 10, and the pump control valves 11, 12 is shown by an electrical system. Part of the system can also be constructed by transmitting hydraulic signals.

Further, in the above embodiment, as shown in FIG. 3, vibration is generated in the hydraulic cylinder 3 by the two variable displacement pumps 1 and 2.
The variable displacement pump 1 may be replaced with a plurality of hydraulic pumps, and the variable displacement pump 2 may be replaced with a plurality of hydraulic pumps.

Further, in the above embodiment, the hydraulic cylinder 3 was cited as an example of the actuator, but the present invention is not limited to this hydraulic cylinder 3, and the present invention is applicable not only to construction machines such as hydraulic shovels but also to various hydraulic machines. Applicable to

Since the actuator drive circuit of the present invention is configured as described above, it is possible to ensure excellent responsiveness to the switching operation of the actuating direction of the actuator, and therefore, it is possible to generate the desired vibration in the actuator. This has the effect of improving the workability of a hydraulic machine equipped with this actuator.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing an example of a conventional actuator drive circuit, FIG. 2 is a flowchart showing an example of a control procedure performed in the conventional actuator drive circuit shown in FIG. Circuit diagram showing one embodiment of the actuator drive circuit, No. 4
This figure is a flowchart showing an example of a control procedure carried out in the embodiment of the present invention shown in FIG. 1, 2... Variable displacement pump, 3... Hydraulic cylinder (actuator), 4... Operating device, 6...
Conversion device, 7, 8, 9, 10... switching valve, 11,
12... Pump control valve, 13, 14... Piston, 15... Switching device.

Claims (1)

[Claims] 1 Consisting of a closed circuit having one actuator, a plurality of hydraulic pumps that drive this actuator, and a switching valve interposed between these hydraulic pumps and the actuator, and an actuating means that operates the switching valve. In the actuator drive circuit capable of driving the actuator by the confluence of pressure oil discharged from the plurality of hydraulic pumps, a switching device connected to the actuation means and outputting a signal is provided, and the actuation means a circuit that connects the switching valve in response to a signal output from the switching device between a discharge port of one of the plurality of hydraulic pumps and one port of the actuator; An actuator drive circuit characterized in that the circuit connecting the discharge port of another one of the hydraulic pumps and the other one port of the actuator is operated so that communication and disconnection are repeated. .