JPH02566B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a hydraulic circuit for operating at least two actuators with one pump, and a control valve used in the hydraulic circuit.

A typical hydraulic circuit of this type is a hydraulic circuit for a power shovel.

Hydraulic circuits for power shovels usually use two pumps, but since each pump flows oil separately into its own circuit system, it is essentially like operating multiple actuators with one pump. It will be the same thing.

A swing motor and an arm cylinder are usually connected as actuators to one circuit system of the power shovel.

In this circuit system, for example, if the swing motor and the arm cylinder are operated simultaneously, various problems arise.

For example, when an arm is operated by the extension and contraction motion of an arm cylinder, the load is extremely low when the arm is lowered.
Therefore, if the swing motor and arm cylinder are operated simultaneously when the arm is lowered, the oil from the pump will flow preferentially to the arm cylinder with lower load pressure, and the speed of the swing motor will become extremely slow. There was a problem.

As a solution to this problem, a hydraulic circuit and a control valve shown in FIGS. 1 and 2 are conventionally known.

FIG. 1 shows a hydraulic circuit in which an upstream control valve 1 controls a swing motor, and a downstream control valve 2 controls an arm cylinder.

When both control valves 1 and 2 are in the neutral position, oil from the pump 3 returns to the tank 5 through the neutral flow path 4.

Also, if the downstream control valve 2 that controls the arm cylinder is switched to the left position alone,
The oil that has passed through the upstream control valve 1 is
The load check valve 6 is pushed open through the neutral flow path 4, and the flow flows from the control valve 2 into the arm cylinder.

When the control valve 2 is switched to the right position, the oil from the pump 3 is transferred to one parallel passage 7.
It enters the control valve 2 through it and from there flows into the arm cylinder.

Therefore, as long as the control valve 2 is operated alone, the oil from the pump 3 will smoothly flow into the arm cylinder.

On the other hand, when both control valves 1 and 2 are operated simultaneously, the passage relationship is as follows.

That is, when the upstream control valve 1 is switched to either the left or right side and the downstream control valve 2 is switched to the left position, the pump 3
Oil enters the control valve 1 through either of the parallel passages 7, 8 and from there into the swing motor. Further, oil enters the control valve 2 on the downstream side through the parallel passage 8 and the throttle 9, and from there flows into the arm cylinder.

Therefore, in the above case, throttling resistance is applied to the oil supplied to the arm cylinder, and the oil from the pump 3 flows preferentially to the swing motor. In other words, if the supply passage on the side of the downward movement of the arm is configured in the above switching state, the speed of the swing motor will not be slowed down.

When the control valve 2 on the downstream side is switched to the right position, oil from the pump 3 enters the control valve 2 through the parallel passage 7, and from there flows into the arm cylinder. In other words, in the right-hand position, a supply passage is formed on the arm's upward movement side.

FIG. 2 specifically shows the control valve in the circuit diagram of FIG. 1.

The drawback of this conventional method is that the neutral flow path 4 that connects both control valves 1 and 2 in tandem
and the parallel passage 8 that connects them in parallel, and the load check valve 6 must be inserted between the neutral flow passage 4 and the parallel passage 8.

In other words, in the conventional case described above, the passage configuration is special, and considering that the arrangement of the control valves of the arm cylinder and the control valves of the swing motor is not necessarily constant, it is particularly difficult to standardize the casting.

The present invention aims to reduce costs by simplifying the circuit configuration itself, and by making it possible to use the control valve in the circuit configuration by slightly improving the conventional control valve.

This will be explained below with respect to each of the illustrated embodiments.

FIG. 3 shows a first embodiment of the hydraulic circuit, in which each control valve 10 to 13 controls the corresponding actuator and switches the oil flow path from the pump 14.

And each of the above control valves 10 to 13
When in the illustrated neutral position, their neutral channels 15-18 are connected in tandem. In this state, oil from the pump 14 passes through the neutral passages 15 to 18 of each valve and returns to the tank 20 from the tank passage 19 connected to the neutral passage 18 of the most downstream control valve 13.

In each of the above valves, when the upstream control valve is switched to either the left or right position as shown in the figure, oil flows into the neutral flow path of the downstream control valve from the switched control valve. First, oil from the pump 14 reaches the parallel passage 21.

In this embodiment, the control valve 12 controls the swing motor 22, and the control valve 13 controls the arm cylinder 23, and the following description will focus on both of them.

When the control valve 12 is now switched to either of the illustrated positions, oil from the pump 14 passes through the control valve 12 from the parallel passage 21 and flows into the swing motor 22. The return oil from the swing motor 22 is transferred to the control valve 12.
From there, it returns to the tank 20 through the tank passage 19.
A shuttle valve 26 is provided between the flow passages 24 and 25 leading to the swing motor 22, so that the high pressure on the supply side of the flow passages 24 and 25 flows to the pilot passage 27.

Further, the arm cylinder 23 connects its rod side chamber 28 and piston side chamber 29 to flow passages 30, 31.
The arm is connected to the control valve 13 through the rod side chamber 28, and the arm rises when pressure oil is supplied to the rod side chamber 28, and descends when pressure oil is supplied to the piston side chamber 29. There is. A pilot passage 32 is connected to a flow passage 30 communicating with the rod side chamber 28.

The two pilot passages 27 and 32 mentioned above are
The pilot operating valve 33 is connected to pilot chambers 34 and 35 on opposite sides, respectively, and the construction of the pilot operating valve 33 is as follows.

That is, the pilot operating valve 33 is located in the parallel passage 21 on the downstream side of the branch point to the control valve 12, and has two positions: a free flow passage position 36 and a throttle passage position 37. As shown, the free flow passage position 36 is usually aligned with the parallel passage 21.

When the control valve 13 is operated independently and switched to either the left or right side, the swing motor 22 side is maintained at a low pressure, so the pilot operating valve 33 maintains the free flow path position 36 shown in the figure.

On the other hand, when the control valve 12 is switched to either the left or right side, and the control valve 13 is also switched to the right position as shown in the figure, oil from the pump 14 flows into the swing motor 22 and drives it, and the oil from the rod side chamber of the arm cylinder 23 It also flows into 28 and raises the arm. At this time, the load pressure of the arm cylinder 23 is
, the pilot operated valve 33 maintains the free flow path position 36 shown.

Next, when the control valve 13 is switched to the left side position in the drawing, oil from the pump 14 flows into the piston side chamber 29 of the arm cylinder 23, causing the arm to descend. At this time, the pressure in the flow path 30 becomes the tank pressure, so the pressure in the pilot chamber 35 becomes lower than that in the pilot chamber 34, and the pressure in the pilot operating valve 3
3 is switched to the throttle passage position 37 by the pilot pressure on the swing motor 22 side.

When the pilot operating valve 33 is switched to the throttle passage position 37, the throttle 38 applies throttle resistance to the oil supplied to the piston side chamber 29.

Therefore, even if the load pressure on the arm cylinder 23 becomes low when the arm is lowered, oil preferentially flows to the arm cylinder 23 and the swing motor 22
There is no need to slow down the speed.

The second embodiment of the hydraulic circuit shown in FIG. 4 is similar to the first embodiment except that the pilot passage of the pilot operating valve 39 is slightly different from the first embodiment.

That is, the pilot operated valve 3 of this second embodiment
9 connects one pilot chamber 40 and the parallel passage 21 near the control valve 13 through a pilot passage 41, and connects the other pilot chamber 42 to the shuttle valve 26 via a pilot passage 43.
It is connected to.

Therefore, when both control valves 12 and 13 are operated simultaneously and the arm cylinder 23 has a low load pressure, the supply pressure of the parallel passage 21 also decreases, so the load pressure of the swing motor 22 is relatively high. Become. Therefore, the pilot operating valve 39 is switched to the throttle passage position due to the differential pressure, and performs the same function as the first embodiment.

FIG. 5 shows a first embodiment of a control valve which opens its neutral flow path 46 when a spool 45 provided within the valve body 44 is in the neutral position shown. When the spool 45 is switched to either the left or right side, this neutral flow path 46 is closed, and either one of the actuator ports 4
7 or 48 communicates with a communication passage 49, and the other actuator port 48 or 47 communicates with one of the tank passages 50 or 51.

The spool 45 and the arch-shaped communication passage 4
A parallel passage 52 is provided between the parallel passage 52 and the communication passage 49, and a pilot operated valve P of the present invention is provided between the parallel passage 52 and the communication passage 49.The specific configuration of the pilot operated valve P is as follows.

That is, this pilot operating valve P has a load check poppet 53 and a piston 54 as its main components.
The cylindrical portion 55 is slidably fitted into the housing 56, and the poppet portion 58 is normally brought into contact with the seat portion 59 by the action of a spring 57 interposed between the cylindrical portion 55 and the piston 54. I'm letting you do it. This seat portion 59 is formed at the opening of the communication passage 49 in the parallel passage 52, and therefore, from the parallel passage 52 to the communication passage 49.
Only the flow of oil to 9 will be allowed.

The piston 54 is slidably provided on the cylindrical portion 55 of the load check poppet 53, and the pilot chamber 60,
It is divided into 61 areas.

The pilot chamber 60 is common to the inside of the cylindrical portion 55, and the pressure of the communication passage 49, that is, the parallel passage 52, is introduced as pilot pressure through a small gap between the housing 56 and the outer periphery of the cylindrical portion 55.

Further, the pilot pressure of the swing motor 22 is introduced into the pilot chamber 61 via the pilot introduction hole 62, the pilot passage 43, and the shuttle valve 26.

However, when the spool 45 is moved rightward in FIG. 5, the actuator port 47 and the communication passage 49 communicate with each other, and the actuator port 48 and the tank passage 51 communicate with each other. Therefore, the pump 14
The oil passes through the parallel passage 52, pushes open the load check poppet 53, reaches the actuator port 47 through the communication passage 49, and from there flows into the rod side chamber 28 of the arm cylinder 23. Further, since the actuator port 48 communicates with the tank passage 51, the return oil in the piston side chamber 29 of the arm cylinder 23 returns to the tank 20, and the arm cylinder 23 operates in a direction to raise the arm.

When the arm rises in this way, the load pressure on the arm cylinder 23 becomes higher than the load pressure on the swing motor 22.

The high load pressure of the arm cylinder flows into one pilot chamber 60 as pilot pressure, and the low load pressure of the swing motor 22 flows into the other pilot chamber 60.
1.

In other words, a pressure difference occurs between the pilot chambers 60 and 61, and the piston 54 moves in accordance with the pressure difference. That is, in the above case, the piston 54 moves upwardly and is located away from the load check poppet 53. The farther the piston 54 is from the load check poppet 53, the more
The lift amount of the poppet 53 can be increased. The fact that the lift amount can be increased means that the opening of the poppet 53 becomes larger, the pressure loss during the flow process from the parallel passage 52 to the rod side chamber 28 is reduced, and the arm cylinder 23 can be operated with a large force.

In the above case, the arm cylinder 2
It is clear that 3 can be operated with great force.

Next, when the spool 45 is moved to the left in FIG.
The oil in the piston 8 returns to the tank 20, and the oil from the pump 14 flows into the piston side chamber 29, causing the arm to descend.

At this time, if the swing motor 22 is operated at the same time, its load pressure will be higher than the load pressure of the arm cylinder 23. Therefore, the piston 54 approaches the load check poppet 53, reducing its lift amount. When the lift amount decreases, the opening of the poppet 53 becomes smaller and the parallel passage 52
The throttling resistance between and the communication passage 49 increases,
There is no possibility that oil preferentially flows into the arm cylinder 23 and slows down the speed of the swing motor 22.

Furthermore, when the spool 45 is moved to the left and the swing motor 22 is not driven, no pressure is introduced into the pilot chamber 61, so a free flow occurs in the poppet 53.

The second control valve shown in Figures 6 and 7
In this embodiment, a so-called bank type control valve is provided with a pilot operating valve P substantially similar to that of the first embodiment.

That is, the load check poppet 63 of this embodiment has a hole 66 that guides the oil in the parallel passage 64 to one pilot chamber 65, and a pilot chamber 67 formed in the adjacent housing or spacer 68. The pilot pressure on the swing motor 22 side is introduced from the introduction hole 69.

The other functions are the same as those of the previous embodiment.

The third embodiment of the control valve shown in FIG. 8 is substantially the same as the first embodiment, but the construction of the load check poppet 70 is slightly different.

That is, the poppet portion 71 of the poppet 70 is provided with a protrusion 72, and the orifice 7 is attached to the protrusion 72.
3 was formed. And the poppet 7
The orifice 73 opens or the notch 74 at the end of the protrusion 72 opens depending on the lift amount of 0.

As is clear from the above description, the invention of claim 1 operates at least two actuators with one pump, and is provided with control valves corresponding to each of these actuators, and these control valves operate at least two actuators. In a hydraulic circuit in which the neutral flow paths are connected in tandem and also connected in parallel via a parallel path,
A pilot operated valve having a free flow passage and a throttle passage is provided in the parallel passage, and the operating pressure of the one actuator and the operating pressure of the other actuator are introduced as pilot pressure to the pilot operated valve, The valve is configured to be switched to either the free flow passage position or the throttle passage position according to the differential pressure between the two pilot pressures.

The pilot operated valve of the present invention guides the operating pressure in one actuator and the operating pressure in the other actuator as pilot pressures, and uses the differential pressure between the two pilot pressures to control the valve at either the free flow passage position or the throttle passage position. For example, when one actuator with a large load starts operating, hydraulic oil is preferentially supplied to that actuator. When this actuator starts to move due to inertia and the load becomes small, the priority state is canceled and sufficient hydraulic oil is supplied to the other actuator. Therefore, this other actuator can be operated efficiently.

Furthermore, since the circuit of the present invention has a pilot operated valve in the parallel passage, unlike the conventional circuit shown in FIG. 1, there is no need to specially provide a parallel passage, and the circuit configuration is simplified accordingly.

Further, the invention of claim 2 provides that the valve body has a neutral flow path connected in tandem with another valve, a parallel passage connected in parallel with another valve, and a spool moving through the parallel passage. The control valve is provided with a communication passage that communicates with the actuator port according to the control valve, a load check poppet that allows only flow from the parallel passage to the communication passage, and a back pressure acting side end of the load check poppet. A pilot operated valve is provided in the valve body, and includes pistons facing each other and pilot chambers formed on both sides of the piston, and one pilot chamber receives pilot pressure from the parallel passage. The pilot pressure of the actuator controlled by another control valve is introduced into the other pilot chamber, and the movement position of the piston is determined according to the differential pressure between the two pilot chambers, The lift amount of the load check poppet is controlled by the piston position.

The invention set forth in claim 2 is configured as described above, so that the movement position of the piston is determined according to the differential pressure in the pilot chamber, and the lift amount of the load check poppet is determined depending on the piston position. controlled.

Therefore, in this case as well, when one actuator with a larger load starts operating, hydraulic oil is supplied preferentially to that actuator. When this actuator starts to move due to inertia and the load becomes small, the priority state is canceled and sufficient hydraulic oil is supplied to the other actuator.

[Brief explanation of drawings]

Figures 1 and 2 are conventional circuit diagrams and cross-sectional views,
FIG. 3 is a circuit diagram showing the first embodiment of the hydraulic circuit of the present invention, FIG. 4 is a circuit diagram also showing the second embodiment, and FIG. 5 is a cross section showing the first embodiment of the control valve of the present invention. Figures 6 and 7 are also the second
A sectional view showing the embodiment, FIG. 8 is a sectional view of the third embodiment. 10-13...control valve, 14...
Pump, 15-18... Neutral flow path, 21, 52,
64...Parallel passage, 33...Pilot operating valve, 44...Valve body, 46...Neutral flow path, 47,
48...actuator port, 49...communication passage, P...pilot operation valve, 53, 63, 70
...Load check poppet, 54...Piston, 60, 61, 65, 67...Pilot chamber.

Claims (1)

[Claims] 1. One pump operates at least two actuators and is provided with a control valve corresponding to each actuator, and these control valves connect their neutral flow paths in tandem, while connecting their neutral flow paths in tandem. In a hydraulic circuit that is also connected in parallel through a hydraulic circuit, a pilot operated valve having a free flow passage and a throttle passage is provided in the parallel passage, and the pilot operated valve has an operating pressure in the one actuator and an actuator in the other actuator. The hydraulic circuit is configured to introduce the operating pressure of the actuator as a pilot pressure, and to switch to either the free flow passage position or the throttle passage position according to the differential pressure between the two pilot pressures. 2. In the valve body, a neutral passageway connected in tandem with the other valve, a parallel passageway also connected in parallel with another valve, and a communication passageway that communicates this parallel passageway with the actuator port according to the movement of the spool. A control valve equipped with a load check poppet that allows flow only from the parallel passage to the communication passage, a piston provided opposite to a back pressure acting side end of the load check poppet, and a control valve that includes the piston. A pilot operating valve is provided in the valve body and has pilot chambers formed on both sides of the valve, and one pilot chamber is configured to introduce pilot pressure from the parallel passage, and the other pilot chamber is configured to introduce pilot pressure from the parallel passage. is configured to introduce the pilot pressure of the actuator controlled by another control valve, and the moving position of the piston is determined according to the differential pressure between the two pilot chambers, and the position of the piston is determined by the position of the load check poppet. A control valve used in a circuit configured to control the amount of lift.