JPH11193801A - Plural hydraulic circuits for pump actuator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide hydraulic circuits, which are connected in series with each other, in one of which bubbles mixed in oil are removed before the oil is supplied to the next circuit, which can prevent the damage to hydraulic equipment, which can prevent an occurrence of noise, which can reduce the quantity of oil circulating a tank and which can miniaturize the tank for cost reduction. SOLUTION: This hydraulic circuit is provided with tanks 1, etc., and a plurality of hydraulic circuits which are connected to the tanks 1, etc., and which uses each of pumps 2, 7a, 7b, etc., directional control valves 3, 8, etc., and actuators 4, 9, etc. In this case, respective circuits are connected in series with each other, and at the same time bubble removers 5, etc., are inserted in and between respective circuits so that the oil whose bubbles were removed is sucked by the pumps 7a, 7b, etc., in the next circuit.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plurality of hydraulic circuits of a pump / actuator, and more particularly, to a series connection between the circuits, removal of bubbles, supply of oil to the next circuit, and storage of a tank. The present invention relates to a configuration of a plurality of hydraulic circuits of a pump / actuator having a reduced tank and a reduced amount of circulating oil.

[0002]

2. Description of the Related Art Conventionally, in a hydraulic circuit having a plurality of circuits each comprising a set of a hydraulic pump and a hydraulic motor, as shown in FIG. In order to assemble the open circuits returned to the above, a large tank capacity corresponding to the sum of the discharge amounts of the pumps in each circuit was required. The hydraulic circuit of FIG. 6 includes a circuit S7 for driving the actuator 56 and a circuit S8 for driving the actuator 66. In the circuit S7, the oil sucked from the tank 1D through the suction pipe 51 by the hydraulic pump 52 is discharged to the pipe 53. This discharge oil is switched by a valve 54 during operation, enters an actuator 56 through a pipe 55, and drives the actuator 56. Return oil from the actuator 56 passes through a pipe 57, a valve 54, and a return pipe 58. Through the tank 1D. When not in operation, the valve 54 returns to the tank 1D through the return line 58. In the circuit S8, the oil sucked from the tank 1D through the suction pipe 61 by the hydraulic pump 62 is discharged to the pipe 63 just like the circuit S7. This discharge oil is switched by a valve 64 during operation, enters an actuator 66 through a pipe 65, and drives the actuator 66. Return oil from the actuator 66 passes through a pipe 67, a valve 64, and a return pipe 68. Through the tank 1D. When the work is not performed, the valve 64 returns to the tank 1D through the return line 68. In FIG. 6, for example, hydraulic pumps 52, 62
Flow rate (discharge rate) of 100 and 200 liters /
Minutes, the total flow through the tank is 300 liters / minute. Since the tank capacity is generally determined as an amount proportional to the total circulation flow rate, in this case, if the ratio of the total circulation flow rate to the tank capacity is, for example, 0.34, the tank capacity needs to be 102 liters.

[0003]

Recently, there has been an increasing demand for lighter and more compact construction machines in terms of high-speed running and higher efficiency. Hydraulic devices are no exception. In general, a plurality of sets of a hydraulic pump and a hydraulic motor are used in a construction machine in order to drive actuators such as a traveling machine, a working machine, and steering. In the conventional hydraulic circuit, since the hydraulic devices of each set form an open circuit, a large tank capacity corresponding to the sum of the discharge amounts of the pumps of each set is required, and there is a problem that the tank becomes large. Further, even if the tank capacity is increased, the amount of circulating oil increases and bubbles are generated, which causes a problem that hydraulic equipment such as a pump, a valve (directional switching valve), and a motor is damaged or noise is generated.

[0004] The present invention focuses on the above problems and provides a pump
In connection with multiple hydraulic circuits of the actuator, in particular, connect each circuit in series, remove bubbles, supply oil to the next circuit, prevent damage to hydraulic equipment, prevent noise generation, and It is another object of the present invention to provide a plurality of hydraulic circuits of a pump / actuator that reduce the amount of oil circulating in a tank and reduce the size and cost of the tank.

[0005]

Means for Solving the Problems and Effects of the Invention To achieve the above object, a first invention of a configuration of a plurality of hydraulic circuits of a pump / actuator according to the present invention comprises a tank,
A pump connected to a tank and having a plurality of circuits using pumps, directional control valves, and actuators.
In the actuator hydraulic circuit, each circuit is connected in series, and a bubble removing device is inserted between the circuits so that the oil from which bubbles have been removed is sucked by a pump of the next circuit. According to the above configuration, the next set of pumps does not suck the oil in the tank, but instead uses the oil in the return circuit from the directional switching valve in the previous set through the bubble removing device to remove the oil from which bubbles have been removed. Since the suction is performed, the oil of one pump circulates, and the discharge oil of each pump does not circulate in the tank, and the amount of circulating oil decreases. Therefore, the tank capacity may be adjusted to the maximum pump discharge amount among the plurality of sets, and the tank capacity can be reduced. In addition, since the oil which the next set of hydraulic pumps sucks passes through the bubble removal device,
Without aeration, the pump can perform as well as before.

According to a second aspect of the present invention, in the configuration of the first aspect, a first pipe connected to the tank via a restriction between the previous circuit and the bubble removing device, and / or a first piping connected to the bubble removing device and the next circuit is provided. A second pipe connecting between the pump and the tank is provided. According to the above configuration, when the tank is connected to the tank via the throttle between the previous circuit and the bubble removing device, the back pressure is applied to the inlet of the bubble removing device, so that the performance of the bubble removing device is improved, Back pressure is also applied to the suction side of the next hydraulic pump, and the efficiency of the next hydraulic pump is improved. In addition, when the flow rate from the outlet of the bubble removing device is smaller than the suction rate of the next set of hydraulic pumps, the insufficient flow rate can be sucked from the tank through the suction line of the next set of hydraulic pumps. In addition, when the flow rate from the outlet of the bubble removing device is larger than the suction rate of the next set of hydraulic pumps, the surplus flow rate can be discharged to the tank through the suction line of the next set of hydraulic pumps. Therefore, even if the suction amount of the next set of hydraulic pumps is too large or small with respect to the flow rate exiting from the outlet of the bubble removing device, the next set of hydraulic pumps can always operate normally.

According to a third aspect of the present invention, in the configuration of the first aspect, a suction pipe of a pump having a large displacement in the previous circuit is connected to a pump having a smaller displacement than the pump in the preceding circuit and the bubble removing device. Two pipes and a third pipe connecting the suction pipe and the second pipe are provided. According to the above configuration, since the flow rate of the air discharged from the outlet of the bubble removing device is larger than the suction amount of the next set of hydraulic pumps, the excess flow rate can be sucked by the previous set of hydraulic pumps. As a result, the amount of oil circulating in the tank is one or less than one pump, and the amount of oil circulating is reduced. Therefore, the next set of hydraulic pumps sucks the flow rate that does not include the air bubbles that come out of the outlet of the air bubble removing device, so that damage to the hydraulic equipment and generation of noise can be prevented.

[0008]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a pump actuator according to an embodiment of the present invention; FIG. First, a first embodiment of the configuration of the hydraulic circuit will be described with reference to FIG. FIG. 1 is a hydraulic circuit diagram, which includes a circuit S1 for driving a traveling motor 4 of an actuator and a circuit S2 for driving a motor (cylinder) 9 for a working machine of the actuator.
In the circuit S1, oil sucked from the tank 1 through the suction pipe 11 by the traveling pump 2 driven by an engine (not shown) is discharged to the pipe 12. This discharged oil enters the traveling valve 3 which is a direction switching valve, and when the traveling valve 3 is in the neutral position, the traveling oil passes through the traveling valve 3 from the traveling pump 2, through the return line 14, into the tank 1. And enters the input port 5a of the bubble removing device 5 attached to the device. When the traveling valve 3 is switched by operating means (not shown), the discharge oil is supplied to the line 13a.
And enters the traveling motor 4 to drive the traveling motor 4. Return oil from the traveling motor 4 enters the traveling valve 3 through the line 13b, and enters the input port 5 of the bubble removing device 5 mounted in the tank 1 through the return line 14.
Enter a. The return oil from which bubbles have been removed by the bubble removing device 5 passes through the output port 15 from the output port 5b and enters the suction pipe 16 of the working machine pumps 7a, 7b described later. The bubbles removed by the bubble removing device 5 are discharged from the vent pipe 5c to the upper inside of the tank 1. In the circuit S2, the output line 15 of the bubble removing device 5 is used.
The oil from which air bubbles have been removed through the suction pipe 16 connected to the pump is sucked by two working machine pumps 7a and 7b driven by an engine (not shown), and
a and 17b. The discharged oil enters the work implement valve 8, and when the work implement valve 8 is at the neutral position, returns from the work implement valve 8 to the tank 1 through the return line 19. When the working machine valve 8 is switched by operating means (not shown), the discharge oil enters the working machine motor 9 through the pipe line 18a, and drives the working machine motor 9, thereby causing the working machine motor to rotate. The return oil from 9 enters the work implement valve 8 through a pipe 18b, and returns to the tank 1 through a return pipe 19. The suction pipe 11 of the traveling pump 2 and the suction pipe 16 of the working machine pumps 7a and 7b are connected to a communication pipe 16a.
And the traveling pump 2 having a large discharge capacity,
The difference between the suction amounts of the working machine pumps 7a and 7b having a smaller discharge capacity than the traveling pump 2 is adjusted.

Next, the function and effect will be described. In the first embodiment, for example, the flow rate (discharge amount) of the traveling pump 2 is set to 2
When the flow rate (discharge rate) of each of the working machine pumps 7a and 7b is 97 liters / minute and the total flow rate (discharge rate) is 194 liters / minute, the traveling pump 2 moves from the tank 1 to 194 liters. / Min., Suctioning 36 liters / min. From the return oil of the traveling pump 2 through the communication line 16a,
The working machine pumps 7a and 7b suck the total amount of 194 liters / minute from the return oil of the traveling pump 2 through the suction line 16. Therefore, the total flow circulating in the tank is 19
Assuming that the ratio of the total circulation flow rate to the tank capacity is 0.34, which is the same as the conventional case, the tank capacity is 6 liters / minute.
Can be 6 liters. If the first embodiment described above is constituted by a conventional hydraulic circuit, the flow rate (discharge rate) of the traveling pump 2 is 230 l / min, and the working machine pumps 7a and 7
Since the total flow rate (discharge rate) of b is 194 liters / minute, the total flow rate circulating in the tank is 424 liters / minute. If the ratio of the total circulating flow rate to the tank capacity is 0.34, the tank capacity is 145 liters. Liters. Therefore, according to the first embodiment, the tank capacity can be reduced by 79 liters as compared with the conventional circuit, and the tank can be downsized. Further, since the air bubble removing device 5 is built in the tank 1, the hydraulic system is compact. In addition, since the difference between the suction amounts of the traveling pump 2 and the working machine pumps 7a and 7b is adjusted via the communication conduit 16a, the flow rate of the air discharged from the outlet of the bubble removing device can be effectively used.

Next, a second embodiment of the construction of the hydraulic circuit is shown in FIG.
This will be described below. This embodiment is different from the first embodiment in that
The air bubble removing device 5 is provided outside the tank 1.
That is, in FIG. 2, the oil from the traveling valve 3 or the return oil from the traveling motor 4 passes through the pipe 13b, the traveling valve 3, and the return pipe 14A, and the bubbles attached to the outside of the tank 1A. Enter the removal device 5A. The return oil from which the bubbles have been removed by the bubble removing device 5A passes through the output line 15A, and the suction lines 16 of the working machine pumps 7a and 7b.
Is to enter. The bubbles removed by the bubble removing device 5A are discharged from the vent pipe 5d to the upper inside of the tank 1A. Except for installation of the bubble removing device 5A outside the tank, it is completely the same as the first embodiment, and the description is omitted.

According to the second embodiment, the location of the bubble removing device 5A is not restricted, and the bubble removing device 5A is easy to install and easy to maintain.

Next, a third embodiment of the configuration of the hydraulic circuit is shown in FIG.
This will be described below. This embodiment is different from the first embodiment in that
A work machine pump 7b is provided by branching and adding a circuit S3 for driving another work machine motor 9a from the circuit S2. That is, in FIG. 3, the output line 1 of the bubble removing device 5 passes through the suction line 16 by the work machine pump 7 b.
The oil sucked from 5 is discharged to the pipeline 17b. This discharged oil enters the working machine valve 8a, and the working machine valve 8a
When a is at the neutral position, the work implement valve 8a returns to the tank 1B through the return line 19a. When the working machine valve 8a is switched by operating means (not shown), the discharged oil enters the working machine motor 9a through the pipe 18c, and drives the working machine motor 9a. Return oil from 9a is line 18d
Through the working machine valve 8a through the return line 19
a to return to the tank 1B. Circuit S
Other than 3 is exactly the same as the first embodiment, and the description is omitted.

According to the third embodiment, the number of actuators that can be driven with the same tank capacity as the first embodiment can be increased.

Next, a fourth embodiment of the construction of the hydraulic circuit is shown in FIG.
This will be described below. In FIG. 4, this hydraulic circuit is a circuit S4 for driving actuators 26, 36 and 46, respectively.
, S5 and S6. In the circuit S4, the oil sucked from the tank 1C through the suction line 21 by the hydraulic pump 22 is discharged to the line 23. When the valve 24 is at the neutral position, the oil discharged from the valve 24 is Most of the air enters the bubble removing device 5B through the return line 28, and the bubbles are removed by the bubble removing device 5B.
It passes through the output line 15B and enters the suction line 31 of the next hydraulic pump 32. Also, the valve 24
Is operated, the actuator 26 is driven through the valve 24 and the line 25, and most of the return oil from the actuator 26 passes through the line 27, the valve 24 and the return line 28, and the bubble removing device 5B Enter the air bubble removal device 5
B removes air bubbles and passes through the output line 15B to enter the next suction line 31 of the hydraulic pump 32. The suction line 31 is open to the tank 1C. If the amount of the outflow from the bubble removing device 5B exceeds or exceeds the suction amount of the hydraulic pump 32, the tank 1C is connected to the suction line 31 via the suction line 31. The adjustment of the suction and discharge is performed between these steps. The air bubbles removed by the air bubble removing device 5B are discharged from the vent pipe 5e to the upper inside of the tank 1C. Also,
Part of the oil from the valve 24 or the return oil from the actuator 26 passes through the return line 28 and
9 to the tank 1C. In the circuit S5, the suction line 31 is
The oil sucked from the output line 15B of the air bubble removing device 5B (and also sucked from the tank 1C if it is insufficient)
The liquid is discharged to the pipe 33. When the valve 34 is in the neutral position, the discharged oil enters the bubble removing device 5C from the valve 34 through the return line 38, and the bubbles are removed by the bubble removing device 5C. Pump 42
Into the suction pipe 41. Also,
When the valve 34 is operated, the valve 34, the line 35
, And most of the return oil from the actuator 36 enters the bubble removing device 5C through the line 37, the valve 34, and the return line 38, and the bubbles are removed by the bubble removing device 5C. , Through the output line 15C to enter the suction line 41 of the hydraulic pump 42. The suction line 41 is open to the tank 1C. If the amount of the fluid discharged from the air bubble removing device 5C exceeds or exceeds the suction amount of the hydraulic pump 42, the tank 1C is connected to the tank 1C via the suction line 41. The adjustment of the suction and discharge is performed between these steps. The air bubbles removed by the air bubble removing device 5C are discharged from the vent pipe 5f to an upper inside of the tank 1C.
A portion of the oil from the valve 34 or the return oil from the actuator 36 passes through a return line 38 and restricts 39.
Through the tank 1C. Circuit S
In S6, as in S5, the oil sucked from the output line 15C of the air bubble removing device 5C by the hydraulic pump 42 through the suction line 41 (and also suctioned from the tank 1C if insufficient) is supplied to the line 43. Is discharged. The discharged oil flows from the valve 44 to the tank 1C through the return line 48 when the valve 44 is at the neutral position. When the valve 44 is operated, the valve 4
4. The actuator 46 is driven through the conduit 45.
The actuator 46 is driven through the valve 44 and the pipe 45, and the return oil from the actuator 46 flows to the tank 1C through the pipe 47, the valve 44, and the return pipe 48. In the above description, the return pipe 28a connecting the return pipe 28 or the suction pipe 31 to the tank 1C and the suction branch pipe 31a may be provided in any one of them. Similarly, it may be arranged in one of the return line 38 and the suction line 41.

According to the fourth embodiment, the stop 2
The back pressure is applied to the inlets of the bubble removing devices 5B and 5C by 9 and 39, so that the performance of the bubble removing devices 5B and 5C is improved, and the suction pipes 31 of the hydraulic pumps 32 and 42 are
Since the back pressure is also applied to 41, the efficiency of the hydraulic pumps 32 and 42 is improved. The suction pipes 31 and 41 are open to the tank 1C. If the amount of suction from the hydraulic pumps 32 and 42 is too large or too small from the bubble removal devices 5B and 5C, the suction pipes are used. Since the suction and discharge are adjusted between the tank 1C and the hydraulic pumps 31 and 41, the hydraulic pumps 32 and 42 can always operate without abnormality.
In the fourth embodiment, for example, the hydraulic pumps 22, 32,
The flow rate (discharge rate) of each was 100 liters / minute,
150 liter / min, 200 liter / min,
If the amount of oil flowing from the throttles 29 and 39 to the tank 1C is neglected, the total flow circulating in the tank is 200 liters / min, and the ratio of the total circulation flow to the tank capacity is 0.34, which is the same as the conventional circuit. The tank volume can be 68 liters. If this is configured with a conventional hydraulic circuit, the total flow rate circulating in the tank is 450 liters / minute, and the tank capacity is 153 liters when the ratio of the total circulation flow rate to the tank capacity is 0.34. Therefore, in the fourth embodiment, the tank capacity can be reduced by as much as 85 liters, and the tank can be significantly reduced in size.

Next, a fifth embodiment of the structure of the hydraulic circuit will be described with reference to FIG.
This will be described below. The fifth embodiment has substantially the same configuration as the first embodiment. In the first embodiment, the circuit S1 drives only one travel motor 4 of the actuator. However, the circuit S1A of the fifth embodiment has travel motors 4a, 4b,. Although two are shown in the figure, three or more may be driven. The traveling valve 3a may be distributed by one switching valve to drive the traveling motors 4a, 4b,... At the same time. ,... May be driven separately. Other configurations are the same as those of the first embodiment. Therefore, description of the operation is omitted.

Further, by appropriately combining the hydraulic circuits of the first to fifth embodiments, circuit characteristics suitable for the circuits can be further improved.

[Brief description of the drawings]

FIG. 1 is a hydraulic circuit diagram showing a first embodiment of the configuration of a hydraulic circuit according to the present invention.

FIG. 2 is a hydraulic circuit diagram showing a second embodiment of the configuration of the hydraulic circuit according to the present invention.

FIG. 3 is a hydraulic circuit diagram showing a third embodiment of the configuration of the hydraulic circuit according to the present invention.

FIG. 4 is a hydraulic circuit diagram showing a fourth embodiment of the configuration of the hydraulic circuit according to the present invention.

FIG. 5 is a hydraulic circuit diagram showing a fifth embodiment of the configuration of the hydraulic circuit according to the present invention.

FIG. 6 is a conventional hydraulic circuit diagram.

[Explanation of symbols]

1A, 1B, 1C, 1D Tank 2, 7a, 7b, 22, 32, 42, 52, 62 Hydraulic pump 3, 8, 8a, 24, 34, 44, 54, 64 Valve 4, 9, 9a, 26, 36 , 46, 56, 66 Actuator 5, 5A, 5B, 5C Bubble removal device 5c, 5d, 5e, 5f Vent pipe 11, 16, 21, 31, 41, 51, 61 Suction pipe (suction pipe) 14, 14A 19, 19a, 28, 38, 48, 5
8, 68 Return line 15, 15A, 15B, 15C Output line 16a Communication line (third line) 28a First line 29, 39 Restrictor 31a Second line

Claims (3)

[Claims] A tank (1, 1A, 1B, 1C) and a tank (1,
1A, 1B, 1C) and pumps (2, 7a, 7b, 2
2, 32, 42, 52, 62) and directional control valves (3, 8, 8a, 24, 3
4, 44, 54, 64) and actuators (4, 9, 9a, 26, 3
6, 46, 56, 66) In a hydraulic circuit for a pump / actuator having a plurality of circuits using the devices described in
(5, 5A, 5B, 5C). A plurality of hydraulic circuits for a pump / actuator, wherein oil from which air bubbles have been removed is sucked by the pumps (7a, 7b, 32, 42) of the next circuit. 2. A first pipe (28a) connected to a tank (1C) via a throttle (29, 39) between a previous circuit and a bubble removing device (5B, 5C) and / or a bubble removing device. Equipment (5B, 5
C) and the pump (32, 42) in the next circuit and the tank (1C)
2. A plurality of hydraulic circuits for a pump / actuator according to claim 1, further comprising a second pipe (31a) connecting the pump and the actuator. 3. A plurality of hydraulic circuits of a pump / actuator according to claim 1, wherein a suction pipe (11) of a pump (2) having a large discharge capacity of a previous circuit and a pump (2) of a previous circuit. Small capacity pump (7a, 7b) and bubble removal device
(5) a second pipe (16) connecting the suction pipe (11) and the second pipe (16).
A plurality of hydraulic circuits for a pump / actuator, wherein a third pipe (16a) for connecting to the pipe (16) is provided.