JPS6333561B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a pump control hydraulic closed circuit, and particularly to a pump control hydraulic closed circuit for a hydraulic excavator.

FIG. 1 is a diagram showing a hydraulic circuit of a conventional hydraulic excavator. In the figure, 1 is a tank, 2 is a hydraulic pump, 3 and 4 are hydraulic cylinders and hydraulic motors connected to the hydraulic pump 2, respectively, and 5 and 6 are installed between the hydraulic pump 2, the hydraulic cylinder 3, and the hydraulic motor 4, respectively. control valve. That is, conventional hydraulic excavators employ an open circuit.

In this hydraulic circuit, the speed and operating direction of the hydraulic cylinder 3 and hydraulic motor 4 are determined by operating the control valves 5 and 6 with levers, and the actuator can be easily controlled. 5 and 6 perform speed control and pressure control using the shibori effect, so there is a large energy loss when driving the lever in an intermediate position, and when the hydraulic cylinder 3 and hydraulic motor 4 are driven by a load, the control Since all the work is absorbed as heat generated by the oil due to the shibori action of the valves 5 and 6, energy cannot be used effectively.

For this reason, it has been proposed to make the hydraulic circuit of the hydraulic excavator a closed circuit. In a conventional closed circuit, one hydraulic pump drives one actuator, but a hydraulic excavator has a large number of actuators, and it is difficult to install the same number of hydraulic pumps as actuators. As such, multiple actuators are attached to one hydraulic pump. In FIG. 2, 7 is a double tilting hydraulic pump, 8 is a swash plate control device for the hydraulic pump 7,
Reference numeral 9 indicates an operating lever for the swash plate control device 8, 10 indicates a switching valve provided between the hydraulic pump 7, the hydraulic cylinder 3, and the hydraulic motor 4, 11 indicates a switching pedal for operating the switching valve 10, and 12 indicates a charge pump. , 13
14 is a check valve, 15 is a flushing valve, and 16 is a relief valve. Then, by operating the switching valve 10 with the switching pedal 11, the actuator is selected, and by operating the swash plate control device 8 with the operating lever 9, the speed and operating direction of the actuator are controlled.

In this hydraulic circuit, energy can be used more effectively than in the open circuit described above, but when the operating lever 9 is operated, the switching pedal 1
When the switching valve 10 is switched in step 1, the actuator that was operating suddenly stops, and the actuator that had been stopped suddenly starts operating, making the operation of the hydraulic excavator jerky. That is, if the switching valve 10 is switched using the switching pedal 11 while the hydraulic cylinder 3 is operating at a speed corresponding to the amount of operation of the operating lever 9, the pipe line connected to the hydraulic cylinder 3 is cut off. The speed of the hydraulic cylinder 3 immediately changes from the speed corresponding to the amount of operation of the operating lever 9 to 0.
On the other hand, since the hydraulic motor 4 is connected to the hydraulic pump 7, the speed of the hydraulic motor 4 immediately changes from 0 to a speed corresponding to the operating amount of the operating lever 9. Furthermore, if the switching valve 10 is switched using the switching pedal 11 while the hydraulic motor 4 is operating at a speed corresponding to the operating amount of the operating lever 9, the pipe line connected to the hydraulic motor 4 is cut off. The speed of the hydraulic motor 4 immediately changes from the speed corresponding to the amount of operation of the operating lever 9 to 0, and on the other hand, since the hydraulic cylinder 3 is connected to the hydraulic pump 7, the speed of the hydraulic cylinder 3 immediately changes from 0 to 0 depending on the operating amount of the operating lever 9. The speed corresponds to the amount of operation. Further, for example, when the hydraulic cylinder 3 is operating at a speed corresponding to the amount of operation of the operating lever 9, if the switching valve 10 is switched using the switching pedal 11 without operating the operating lever 9, the hydraulic motor 4 is activated by the operator. It may operate in the opposite direction to the intended direction. In addition, in the open circuit shown in FIG. 1, the hydraulic cylinder 3 and the hydraulic motor 4 are operated independently with two levers, whereas in this closed circuit, the actuator is switched with the switching pedal 11.
Since the speed and operating direction of the actuator are controlled by the operating lever 9, when a person who has operated a conventional hydraulic excavator operates a closed-circuit hydraulic excavator, it becomes difficult to operate the hydraulic excavator, and the operator has difficulty learning the actuator.

This invention was made to solve the above-mentioned problems, and an object thereof is to provide a pump control hydraulic closed circuit with good operability.

In order to achieve this object, the present invention includes a double tilting hydraulic pump, a plurality of hydraulic actuators, and a switching system that connects the double tilting hydraulic pump and each of the plurality of hydraulic actuators independently in a closed circuit. In a pump control hydraulic closed circuit having a valve and an operating device that controls the operating speed and direction of each of the hydraulic actuators via a regulator of the double tilting pump, detecting the amount of tilting of the double tilting hydraulic pump. and a detection means for inputting an operation command signal from the operating device of each of the hydraulic actuators and a tilting amount signal from the detection means, and connecting the double tilting hydraulic pump and each of the hydraulic actuators set in advance. According to the priority order, when the operation command signal of the hydraulic actuator with a higher priority is input while the hydraulic actuator with a lower priority is being driven, or the operation command signal of the hydraulic actuator with a higher priority is stopped and the operation command signal of the hydraulic actuator with a lower priority is input. When driving the hydraulic actuator with priority, first output a command to return the tilting amount of the double tilting hydraulic pump to 0, and when the tilting amount of the double tilting hydraulic pump becomes almost 0, A control device is provided that outputs a signal for switching the switching valve and controls the amount of tilting of the double tilting hydraulic pump using an operation command signal for the currently driven hydraulic actuator.

FIG. 3 is a diagram showing a pump control hydraulic closed circuit according to the present invention. In the figure, 17a and 17b are operating levers, 18a and 18b are window comparator circuits, and the comparator circuits 18a and 18b output an output signal 0 when the operating amount of the operating levers 17a and 17b, that is, the absolute value of the operating signal is less than a predetermined value. However, when the absolute value exceeds the predetermined value, output signal 1 is output. 19a and 19b are flip-flop circuits, 20a to 20f are AND circuits,
21a to 21c are switch circuits, and the switch circuits 21a to 21c are closed when the command signal is 1, and open when the command signal is 0. 22 is an OR circuit; 23a to 23d are knot circuits; 24 is a displacement meter that detects the amount of tilting of the swash plate of the hydraulic pump 7;
8c outputs an output signal 0 when the output of the displacement meter 24, that is, the absolute value of the amount of tilting of the swash plate of the hydraulic pump 7 is less than a predetermined value, and outputs an output signal 1 when the absolute value exceeds the predetermined value. 25 is a swash plate controller.

Next, the operation will be explained. First, when only the operating lever 17a is operated, the output from the comparator circuit 18a becomes 1, and the switch circuit 21
Since the command signal of a becomes 1, the switch circuit 21
a is closed. At the same time, AND circuit 20b
Since the swash plate of the hydraulic pump 7 is in the neutral position at this time, the output of the comparator circuit 18c is 0, and the output of the not circuit 23c is 0.
The output of is 1. Therefore, the AND circuit 20
The output of b becomes 1, and the flip-flop circuit 19
Since the input to the S terminal of a becomes 1, the output from the Q terminal of the flip-flop circuit 19a becomes 1, and the switching valve 10 is switched from the n position to the a position. Further, the output of the comparator circuit 18a is 1, but since the output of the Q terminal of the flip-flop circuit 19b is 0, the output of the AND circuit 20f is 0, and the output of the NOT circuit 23d is 1, so the switch circuit 21c is closed. As a result, the output signal of the operating lever 17a is transmitted to the swash plate controller 25, and the swash plate controller 8 controls the swash plate of the hydraulic pump 7, thereby controlling the speed and operating direction of the hydraulic motor 4.

In this case, the swash plate of the hydraulic pump 7 is no longer in the neutral position, the output of the comparator circuit 18c becomes 1, and the output of the knot circuit 23c becomes 0, but the output of the Q terminal of the flip-flop circuit 19a is held at 1. , the switching valve 10 is held at position a.

Furthermore, when only the operating lever 17b is operated, the output of the comparator circuit 18b becomes 1, and this signal is transmitted to the AND circuit 20e. At this time, since the operating lever 17a is neutral, the output of the comparator circuit 18a is 0, and the output of the NOT circuit 23a is 1, so all the inputs of the AND circuit 20e are 1, and the output of the AND circuit 20e is 1, so the switch is activated. The circuit 21b is closed. Further, the output 0 of the comparator circuit 18a is output from the AND circuit 20.
Since the signal is input to f, the output of the AND circuit 20f becomes 0, the output of the NOT circuit 23d becomes 1, and the switch circuit 21c is closed. Therefore, the hydraulic pump 7 can be controlled by the operating lever 17b. Further, since the output of the comparator circuit 18b is 1 and the output of the knot circuit 23a is 1, and the swash plate of the hydraulic pump 7 is initially neutral, the output of the comparator circuit 18c is 0 and the output of the knot circuit 23a is 1.
The output of c is 1. Therefore, AND circuit 2
All inputs of 0c become 1, and AND circuit 20c
The output from the flip-flop circuit becomes 1, and the flip-flop circuit 1
The output from the Q terminal of 9b becomes 1. Therefore, the switching valve 10 is switched to position b.

In this case, the swash plate of the hydraulic pump 7 is no longer in the neutral position, the output of the comparator circuit 18c becomes 1, and the output of the knot circuit 23c becomes 0, but the output of the Q terminal of the flip-flop circuit 19b is maintained at 1. , the switching valve 10 is held at position b.

Next, when the operating levers 17a and 17b are operated simultaneously, the output from the NOT circuit 23a is 0 and the output from the AND circuit 20e is 0, so the switch circuit 21b is opened and the output from the comparator circuit 18a is 1, the switch circuit 21a is closed. In addition, the knot circuit 23
Since the output of a is 0, the output of the AND circuit 20c is 0, and the output of the Q terminal of the flip-flop circuit 19b is 0, whereas the output of the AND circuit 20b is 0.
The output of the flip-flop circuit 19a is 1, and the flip-flop circuit 19a
Since the output of the Q terminal of is 1, the switching valve 10 is a
Switch to position. Therefore, the operation lever 17a
The hydraulic motor 4 can be operated by.

Further, when operating the operating lever 17a while operating the hydraulic cylinder 3 with the operating lever 17b, the output of the comparator circuit 18a becomes 1, so the switch circuit 21a is closed, and the output of the not circuit 23a becomes 0, and Since the output of the circuit 20e becomes 0, the switch circuit 21b is opened. Furthermore, at the moment when the operating lever 17a is operated, the swash plate of the hydraulic pump 7 is not in the neutral position.
The output of the NOT circuit 23c is 0, and the output of the Q terminal of the flip-flop 19a remains 0. Since the output of the Q terminal of the flip-flop circuit 19b is 1, the two inputs of the AND circuit 20f are 1, and the output of the NOT circuit 23d is 0, so the switch circuit 21c is opened, and as a result, the hydraulic pump 7 swashplate returns to neutral position. Therefore, since the output of the comparator circuit 18c is 0 and the output of the NOT circuit 23c is 1, the AND circuit 2
The output of 0b becomes 1, and flip-flop circuit 1
The output of the Q terminal of 9a becomes 1. Further, since the output of the OR circuit 22 becomes 1, the output of the Q terminal of the flip-flop circuit 19b becomes 0. For this reason,
When the switching valve 10 is switched from the b position to the a position, the output of the AND circuit 20f becomes 0, and the switch circuit 21c is closed, so that the operating lever 17a
The hydraulic pump 7 is controlled by the signal. Note that since the output of the Q terminal of the flip-flop circuit 19a is input to the OR circuit 22, the flip-flop circuit 19b is always reset when the switching valve 10 is in the a position.

In this way, when the operating lever 17a is further operated while the operating lever 17b is being operated, a command is output to return the swash plate of the hydraulic pump 7 to the neutral position, and the swash plate of the hydraulic pump 7 is returned to the neutral position. After returning and the speed of the hydraulic cylinder 3 becomes 0, the switching valve 10 goes to the a position and the hydraulic motor 4 operates, but the hydraulic pressure does not change until the command to return the swash plate of the hydraulic pump 7 to the neutral position is output. Since it takes 0.2 to 0.5 seconds for the swash plate of the pump 7 to return to the neutral position, the speed of the hydraulic cylinder 3 is controlled by the operating lever 17.
0 between 0.2 and 0.5 seconds from the speed according to the operation amount of b
Therefore, compared to the conventional case where the speed of the hydraulic cylinder 3 immediately changes from the speed corresponding to the operation amount of the operating lever 9 to 0, the speed change of the hydraulic cylinder 3 is gradual, and the hydraulic pump With the swash plate 7 returned to the neutral position, the hydraulic motor 4 is connected to the hydraulic pump 7, and a command is output to set the amount of tilting of the hydraulic pump 7 to a value corresponding to the amount of operation of the operating lever 17a. Since it takes 0.2 to 0.5 seconds for the amount of tilting of the hydraulic pump 7 to reach a value corresponding to the amount of operation of the operating lever 17a, the speed of the hydraulic motor 4 will vary from 0 to 0.2 to 0.5 seconds. Operation lever 1
Since the speed corresponds to the operation amount of the operating lever 7a, the speed of the hydraulic motor 4 changes more quickly than the conventional case where the speed of the hydraulic motor 4 immediately changes from 0 to the speed corresponding to the operation amount of the operating lever 9. is gradual. Furthermore, since the hydraulic motor 4 is connected to the hydraulic pump 7 with the swash plate of the hydraulic pump 7 returning to the neutral position, the hydraulic motor 4 will not operate in the opposite direction to the direction intended by the operator. .

Furthermore, if the operating lever 17b is operated while the hydraulic motor 4 is being operated using the operating lever 17a, the output of the comparator circuit 18b becomes 1, but the output of the knot circuit 23a remains 0. , the outputs of the AND circuits 20e and 20c remain at 0. Therefore, the switch circuit 21b remains open, the switching valve 10 is not switched, and the hydraulic motor 4 having a higher priority is driven as it is.

Further, when the operating levers 17a and 17b are simultaneously operated and the operating lever 17a is returned to the neutral position, the swash plate of the hydraulic pump 7 returns to the neutral position in response to the operation of the operating lever 17a. In this case, the output of the comparator circuit 18a is 0, the output of the not circuit 23a is 1, and the output of the comparator circuit 18c is 0, and the output of the not circuit 23a is 0.
Since the output of c becomes 1, the output of the AND circuit 20a becomes 1, and the Q of the flip-flop circuit 19a becomes 1.
When the output of the terminal becomes 0, the AND circuit 20
The output of c becomes 1, and the flip-flop circuit 19
Since the output of the Q terminal of b becomes 1, the switching valve 10 is switched from the a position to the b position. On the other hand, when the operating lever 17a is in the neutral position, the output of the comparator circuit 18a becomes 0, so the switch circuit 21a becomes open, the output of the knot circuit 23a becomes 1, and the output of the AND circuit 20e becomes 1. , the switch circuit 21b is closed, and the output of the AND circuit 20f becomes 0 and the output of the NOT circuit 23a becomes 1, so the switch circuit 21c remains closed. Therefore, the hydraulic pump 7 is controlled by the signal from the operating lever 17b. Therefore, the speed and operating direction of the hydraulic cylinder 3 are controlled by the signal from the operating lever 17b. In this way, when the operating lever 17a is returned to the neutral position from the state in which the operating levers 17a and 17b are being operated simultaneously, a command is output to return the swash plate of the hydraulic pump 7 to the neutral position, and the swash plate of the hydraulic pump 7 is returned to the neutral position. After the plate returns to the neutral position and the speed of the hydraulic motor 4 becomes 0, the switching valve 10 moves to the b position and the hydraulic cylinder 3 operates, but the command to return the swash plate of the hydraulic pump 7 to the neutral position is not received. Since it takes 0.2 to 0.5 seconds for the swash plate of the hydraulic pump 7 to return to the neutral position after the output, the speed of the hydraulic motor 4 changes from the speed corresponding to the operation amount of the operating lever 17a to 0.2 to 0.5 seconds. Therefore, the speed change of the hydraulic motor 4 is gradual compared to the conventional case where the speed of the hydraulic motor 4 immediately becomes 0 from the speed corresponding to the operation amount of the operating lever 9. In addition, with the swash plate of the hydraulic pump 7 returning to the neutral position, the hydraulic cylinder 3 is connected to the hydraulic pump 7, and a command is issued to set the amount of tilting of the hydraulic pump 7 to a value corresponding to the amount of operation of the operating lever 17b. is output, the tilting amount of the hydraulic pump 7 becomes the operating lever 1.
It takes 0.2 to 7b to reach the value corresponding to the amount of operation.
Since it takes 0.5 seconds, the speed of the hydraulic cylinder 3 changes from 0 to a speed corresponding to the amount of operation of the operating lever 17b within 0.2 to 0.5 seconds. Operation lever 9
The speed change of the hydraulic cylinder 3 is gradual compared to the case where the speed changes according to the operation amount. Furthermore, since the hydraulic cylinder 3 is connected to the hydraulic pump 7 with the swash plate of the hydraulic pump 7 returning to the neutral position, the hydraulic cylinder 3 will not operate in the opposite direction to the direction intended by the operator. .

In addition, in the above-mentioned embodiment, the case of a pump control hydraulic closed circuit of a hydraulic excavator was explained.
The present invention can also be applied to pump control hydraulic closed circuits for hydraulic equipment other than hydraulic excavators. Furthermore, although the above-mentioned embodiment has been described with reference to the case where there are two actuators, the present invention can also be applied to a case where there are three or more actuators. Furthermore, although electronic elements are used in the above embodiments, it goes without saying that a digital computer may be used for control instead of the electronic elements.

As explained above, in the pump control hydraulic closed circuit according to the present invention, if an interrupt from a high priority actuator occurs while a low priority actuator is being driven, the high priority hydraulic actuator is activated. When the operation command signal is stopped and a hydraulic actuator with a lower priority is driven, first issue a command so that the tilting amount of the double tilting hydraulic pump becomes 0, and when the tilting amount becomes close to 0. Since the switching valve is switched and the amount of tilting of the double tilting hydraulic pump is controlled by the command signal of the actuator currently being driven, there is no need to switch the switching valve using the switching pedal as in the conventional method, and the actuator operates suddenly. Since it never stops, operability is significantly improved. As described above, the effects of this invention are remarkable.

[Brief explanation of the drawing]

1 and 2 are diagrams showing a hydraulic circuit of a conventional hydraulic shovel, respectively, and FIG. 3 is a diagram showing a pump control hydraulic closed circuit according to the present invention. 3...Hydraulic cylinder, 4...Hydraulic motor, 7...
...Double tilting hydraulic pump, 8... Swash plate control device, 17
a, 17b...operation lever, 18a-18c...
Window comparator circuit, 19a, 19b...
Flip-flop circuit, 20a-20f...AND circuit, 21a-21c...switch circuit, 22...
...OR circuit, 23a-23d...Knot circuit, 2
4...Displacement meter, 25...Swash plate controller.

Claims (1)

[Claims] 1. A double tilting hydraulic pump, a plurality of hydraulic actuators, a switching valve that independently connects the double tilting hydraulic pump and each of the plurality of hydraulic actuators to a closed circuit, and an operating speed of each of the hydraulic actuators. and an operating device for controlling the operating direction of the double tilting hydraulic pump via the regulator of the double tilting hydraulic pump, a detection means for detecting a tilting amount of the double tilting hydraulic pump, and a detection means for detecting a tilting amount of the double tilting hydraulic pump, inputting an operation command signal from the operating device and a tilting amount signal from the detecting means;
According to the preset connection priority order between the double tilting hydraulic pump and each of the hydraulic actuators, when an operation command signal for the hydraulic actuator with a higher priority is input while driving the hydraulic actuator with a lower priority. Alternatively, when the operation command signal of the hydraulic actuator with a higher priority is stopped and the hydraulic actuator with a lower priority is driven, first output a command to return the tilting amount of the double tilting hydraulic pump to 0; When the tilting amount of the double tilting hydraulic pump becomes almost 0, a signal is output to switch the switching valve, and the tilting amount of the double tilting hydraulic pump is controlled by the operation command signal of the currently driven hydraulic actuator. A pump control hydraulic closed circuit characterized by comprising a control device for controlling the pump.