JPH0470482B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a regeneration and priority hydraulic control device used in, for example, a power shovel, in which a single pump drives a plurality of actuators. For example, in a power shovel, the present invention relates to a device that preferentially drives a swing motor and, when a counter load acts on an arm cylinder, regenerates hydraulic oil on the return side of the cylinder to the supply side.

(Prior Art) In conventionally known devices of this type, the amount of regeneration for the arm cylinder is constant, and the amount of regeneration cannot be controlled in accordance with the amount of operation input to the swing motor. Ta.

(Problems to be Solved by the Present Invention) In the conventional device as described above, when the swing motor is driven while the arm cylinder is in operation, the hydraulic fluid is supplied preferentially to the swing motor, and The supply flow rate becomes insufficient, but at this time, the regeneration flow rate cannot be increased to compensate for the shortage in the supply flow rate. Therefore, when the swing motor was driven, there was a problem in that the operating speed of the arm cylinder changed drastically.

Further, when the arm cylinder is operated while the swing motor is being driven, there is also a problem in that the speed of the swing motor changes significantly.

In the case of a power shovel in which a swing motor and an arm cylinder are driven by one pump, this invention has a structure in which the amount of regeneration of the arm cylinder increases as the amount of operation for the swing motor increases, and the regeneration amount of the arm cylinder increases. The purpose of the present invention is to provide a device in which speed changes in both actuators are reduced.

(Means for Solving Problems) In order to achieve the above object, the present invention connects one actuator and the other actuator in parallel, and when these actuators are operated simultaneously, one actuator is given priority. A pilot switching valve for controlling one of the actuators, and a pilot switching valve for controlling the switching valve. A pilot operating mechanism that controls the pilot pressure applied to the chamber according to the amount of operation, and a switching valve that is connected in parallel to the pilot switching valve and controls the other actuator, and controls the other actuator. The main body of the switching valve has a pair of actuator ports connected to the other actuator, a supply flow path connected to the pump via a parallel passage, a return flow path that is constantly in communication with the tank, and a switching position. Either one of the actuator ports communicates with the supply flow path and the other actuator port communicates with the return flow path depending on the spool, and a regeneration flow path formed in the axial direction of the spool. A back pressure valve opens under pressure action on the return side of one of the actuator ports and communicates the regeneration flow path with the return flow path, and the load pressure of the actuator acts as back pressure, and the pressure inside the regeneration flow path A check valve that opens under the action of pressure and communicates this regeneration flow path to the other actuator port, and a passage that leads the pilot pressure of the pilot switching valve to the spring chamber of the back pressure valve are formed.

(Operation of the present invention) Since the present invention is configured as described above, when the other actuator is operated alone, if the pressure on the return side is lower than the pressure set by the back pressure valve,
The returned oil is recycled from the regeneration flow path to the supply side via the check valve.

Further, since the load pressure of the other actuator acts as back pressure on the check valve, if the load pressure of the actuator becomes high, this check valve remains closed. Therefore, the return oil opens the back pressure valve and flows into the return passage.

When both actuators are operated simultaneously, the pilot pressure of the pilot switching valve that controls one of the actuators acts on the spring chamber of the back pressure valve. Furthermore, since this pilot pressure changes depending on the amount of operation input to the one actuator, the pressure in the spring chamber of the back pressure valve also changes depending on the amount of operation input.

Therefore, if the amount of operation for one actuator is increased, the amount of regeneration for the other actuator will also be increased. When one actuator is fully operated, the entire amount of return oil from the other actuator is regenerated.

In addition, in this way, the pressure in the spring chamber is controlled according to the amount of operation input to one actuator, and the pressure increase in the spring chamber is increased accordingly.
Since the pressure on the return side of the other actuator also increases, the starting pressure of the one actuator can be ensured.

(Effects of the present invention) In this way, the regeneration amount of the other actuator changes in proportion to the amount of operation of one actuator, so when switching from single operation to simultaneous operation, or from simultaneous operation to individual operation. In either case, the speed change of the actuator is reduced.

Further, since the pressure in the spring chamber of the back pressure valve changes in proportion to the amount of operation of one actuator, it is possible to maintain the circuit pressure for prioritizing the operation of the one actuator.

(Embodiment of the present invention) The embodiment shown in FIG. 1 is a pilot switching valve a for controlling a swing motor m as one actuator of the present invention, and a pilot switching valve a for controlling an arm cylinder s as the other actuator. The switching valves a and b are connected in tandem through a center bypass passage 1 and also connected in parallel through a parallel passage 2.

The pilot switching valve a connects the pilot chambers 3 and 4 at both ends to the proportional pressure reducing valves 5 and 6, which function as the pilot operating mechanism of the present invention, via channels 7 and 8, and Pressure reducing valves 5 and 6 are connected to tank T and pilot pump 9. Such proportional pressure reducing valves 5, 6
normally communicates with the tank T, but when the operation parts 5a and 6a are operated, the degree of communication opening with the pilot pump 9 increases in proportion to the amount of operation input, increasing the secondary pressure by that amount. . Therefore, the greater the amount of operation, the higher the pilot pressure acting on the pilot chambers 3, 4.

Now, when the pilot switching valve a is in the neutral position shown in the figure, the swing motor m is connected to the tank T to maintain the stopped state.

When the switching valve a is switched to either the left or right side, the swing motor m rotates forward or reverse, and the flow rate supplied to the swing motor m is proportional to the switching amount of the pilot switch valve a. In other words, a supply flow rate proportional to the operation amount of the proportional pressure reducing valve 5 or 6 is ensured.

The pilot switching valve b that controls the arm cylinder s has a pair of actuator ports 11 and 12 formed in its main body 10, and one actuator port 11 is communicated with the rod side chamber 13 of the arm cylinder s. , the other actuator port 12 is connected to the bottom chamber 14 .

A spool 15 is installed inside the main body 10, and both ends of the spool 15, into which plugs 26 and 29 are fitted, are made to face the pilot chambers 18 and 19.
, the spring receivers 16 and 17 are slidably covered, and the neutral springs 20 and 2 are mounted on these spring receivers 16 and 17.
1 is acting.

The spool 15 is hollow along its axial direction, and seat parts 22 and 23 are formed on both sides of the hollow part. A back pressure valve 24 is brought into pressure contact with one seat part 22, and the other seat part is in pressure contact with the back pressure valve 24. 23 is operated by a check valve 25.

In other words, a spring chamber 27 is formed between this back pressure valve 24 and the plug 26, and by the action of the spring 28 provided in this spring chamber 27, the back pressure valve 24 is moved to one seat portion 2 as described above.
It is made to press against 2.

A spring chamber 30 is also provided between the check valve 25 and the plug 29, and a spring 31 provided in the spring chamber 30 presses the check valve 25 against the other seat portion 23.

Of the hollow part of the spool 15 thus constructed,
The portion where the back pressure valve 24 and the check valve 25 face each other is defined as a regeneration flow path 32.

The pilot chambers 18 and 19 have flow paths 33 and 34.
The proportional pressure reducing valves 35, 36 are connected to the proportional pressure reducing valves 35, 36 via the operating section 3.
This is similar to the proportional pressure reducing valves 5 and 6 described above, in that the secondary pressure is increased in proportion to the amount of operation of the valves 5a and 36a.

When the spool 15 is in the neutral position shown, it closes the supply passage 38 connected to the parallel passage 2 via the check valve 37, while opening the center bypass passage 1 to the tank T.

When the spool 15 moves to the left in the drawing, the center bypass passage 1 closes, and the supply passage 38 and the actuator port 11 communicate with each other via the first annular groove 39 formed in the spool 15. and the other actuator port 1
2 communicates with a return flow path 41 via a third annular groove 40 .

Conversely, when the spool 15 is moved rightward in the drawing, the supply channel 38 communicates with the other actuator port 12 via the second annular groove 42;
The regeneration channel 32 is connected to the regeneration channel 32 through communication holes 43 and 44 formed in the
communicate with.

At this time, the pressure on the other actuator port 12 side is applied to the spring chamber 30 through a through hole 45 formed in the spool 15 and a small hole 46 formed in the check valve 25.
and acts as a back pressure on the check valve 25.

Furthermore, if the pressure of the return oil that has flowed into the regeneration channel 32 from the communication holes 43 and 44 is higher than the set pressure of the back valve 24 as described above, it pushes open the back pressure valve 25 and flows through the communication hole 47. It flows into the return flow path 41.

And the spring chamber 27 of the back pressure valve 25
is connected to a shuttle valve 50 via a passage 49 provided with a throttle 48, and this shuttle valve 50 selects the higher pilot pressure for the pilot switching valve a. Therefore, when the pilot switching valve a is switched by operating the proportional pressure reducing valve 5 or 6 in order to drive the swing motor m, the pilot pressure at that time acts on the spring chamber 27.

On the other hand, an oil hole 51 is communicated with the actuator port 12 so that the pressure on the actuator port 12 side acts on the pilot piston 52 of the swing priority release relief valve v through the oil hole 51. I have to.

When the pressure inside the actuator port 12 becomes higher than the set pressure of the relief valve v, the pressure action pushes the pilot piston 52 and pushes the poppet 53 open against the spring 54, causing the surroundings of the plug 26 to be pushed open. The spring chamber 27 of the back pressure valve 24 is communicated with the tank T through the gap.

Thus, when either the proportional pressure reducing valve 35 or 36 is operated, a pilot pressure proportional to the operating input acts on either the pilot chamber 18 or 19.

Now, for example, if the proportional pressure reducing valve 36 is operated to apply pilot pressure to the pilot chamber 19,
As the spool 15 moves to the left in the drawing, the supply channel 38 and one actuator port 11 communicate with each other via the first annular groove 31, and the other actuator port 12 and the return channel 41 communicate with each other via the first annular groove 31. communicate with each other via the third annular groove 40.

When the spool 15 is switched as described above,
Pressure oil from the main pump p is supplied to the rod side chamber 13 of the arm cylinder s, and return oil from the bottom side chamber 14 returns to the tank T, so that the arm cylinder s contracts.

Also, when the proportional pressure reducing valve 35 is operated to apply pilot pressure to the pilot chamber 18, the spool 1
5 moves rightward in proportion to the pilot pressure, the other actuator port 12 and the supply flow path 38 communicate with each other via the second annular groove 42, while the communication holes 43 and 44 of one It opens to the actuator port 11. However, depending on the amount of movement of the spool 15, only the communication hole 43 may be opened.

Therefore, pressure oil from the main pump p is supplied to the bottom side chamber 14 of the arm cylinder s, and return oil from the rod side chamber 13 is supplied to the communication hole 4.
3 and 44 into the regeneration channel 32.

At this time, a counter load acts on the arm cylinder s, and the pressure inside the bottom side chamber 14 becomes
When the pressure is lower than the set pressure determined by the back pressure valve 24, the return oil flowing into the regeneration flow path 32 pushes open the check valve 25 and is regenerated to the other actuator port 12 side via the through hole 45. .

Further, when a sufficient load is applied to the arm cylinder s, the pressure inside the bottom side chamber 14 also increases, but the pressure at that time propagates to the spring chamber 30 via the through hole 45 and the small hole 46, This acts as a back pressure on the check valve 25.

Therefore, in this case, the check valve 25 remains closed and the back pressure valve 24 opens, so that the regeneration channel 3
2, the return oil flows through the circulation hole 47 and the return flow path 4.
Return to Tank T via 1.

Note that when the arm cylinder is operated independently as described above, the spring chamber 27 of the back pressure valve 24 is connected to the flow path 55 → passage 49 → shuttle valve 50 →
It communicates with the tank T via either a proportional pressure reducing valve 5 or 6. Therefore, in this case, the set pressure of the back pressure valve 24 is determined only by the spring force within the spring chamber 27.

When the arm cylinder s and the swing motor m are operated simultaneously, the arm cylinder operates as described above.

In addition, the pilot switching valve a is connected to the proportional pressure reducing valves 5 and 6.
The rotation motor m is switched in proportion to the operating amount of
However, the pilot pressure at this time propagates to the spring chamber 27 via the shuttle valve 50 → passage 49 → throttle 48 and acts on the back pressure valve 24 as back pressure, so the set pressure of the back pressure valve 24 is This is the sum of the spring force of the spring 28 and the pilot pressure.

Therefore, if the pilot pressure is increased by increasing the operating amount of the proportional pressure reducing valve 5 or 6 in order to increase the operating amount of the swing motor m, the back pressure acting on the back pressure valve 24 will also increase, so that the regeneration channel More of the return oil from the rod side chamber 13 that has flowed to the rod side chamber 32 is recycled to the actuator port 12 side, which is the supply side. Moreover, as the regeneration flow rate increases in this manner, the pressure difference between the rod side chamber 13 and the bottom side chamber 14 decreases, and the circuit pressure increases accordingly, so that the rotation priority pressure of the rotation motor m can also be secured.

Furthermore, when the swing motor m is operated while the arm cylinder s is being operated, the regeneration flow rate is controlled according to the operating amount of the swing motor m, so that changes in the operating speed of the arm cylinder s are reduced. In other words, even if hydraulic oil is constantly supplied to the swing motor m, the regeneration flow rate increases in proportion to the supplied amount, so that the speed change of the arm cylinder s is also reduced.

After all, if the required flow rate for the swing motor m increases, the regeneration flow rate for the arm cylinder s will be increased accordingly, which will reduce the speed change of both actuators. The same applies if you do.

In addition, in such a power shovel,
Excavation work is sometimes carried out with the arm pressed against the side of a cliff, etc. In this case, the swing motor m only needs to exert a pressing force, so the motor m and the arm cylinder s Simultaneous operation is different from the passage conditions described above.

Therefore, in such a case, the priority operation of the swing motor m is canceled. That is,
When the arm cylinder s is operated while the swing motor m is stopped and the pressing force is maintained as described above, the bottom side chamber 1 of the arm cylinder s
4 pressure increases. When the pressure exceeds the set pressure of the swing priority release relief valve v, the relief valve v opens to communicate the spring chamber 27 with the tank T, and the pilot pressure for the swing motor is unloaded. As a result, the pressure on the return side of the arm cylinder s is reduced to the same value as when the arm cylinder is operated alone, and the bottom side chamber 1
Excavation work can be performed by effectively using the pressure 4, and the pressure in the bottom side chamber 14 acts on the swing motor m, so that the pressing force described above is exerted.

In the above embodiment, the switching valve b for controlling the arm cylinder is also switched by the pilot pressure, but the switching valve b may be operated manually.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention, in which only the other switching valve b that controls the arm cylinder is shown in a detailed cross-sectional view. m...Swivel motor as one actuator, s...Arm cylinder as the other actuator, a...Pilot switching valve, b...Switching valve, 2
...Parallel passage, 3, 4...Pilot compartment, 5, 6
...proportional pressure reducing valve as a pilot operating mechanism, 10
...Body, 11, 12...Actuator port, 1
5... Spool, 24... Back pressure valve, 25... Check valve, 27... Spring chamber, 32... Regeneration channel, 38
...supply channel, 49...passage, p...pump, T...tank.

Claims (1)

[Claims] 1 When one actuator and the other actuator are connected in parallel and these actuators are operated simultaneously, one actuator is driven preferentially and the load pressure of the other actuator is below the set pressure, A device for regenerating hydraulic oil on the return side to the supply side includes a pilot switching valve that controls one of the actuators, and a switching valve that is connected in parallel to the pilot switching valve and controls the other actuator. The main body of the switching valve that controls the other actuator is provided with a pair of actuator ports connected to the other actuator, a supply channel connected to the pump via a parallel passage, and a supply channel that is constantly communicated with the tank. a return flow path, a spool that selectively communicates either the actuator port with the supply flow path or the return flow path depending on the switching position, a regeneration flow path formed in the axial direction of the spool, and the actuator. A back pressure valve opens under pressure action on the return side of the port and connects the regeneration flow path to the return flow path, and a back pressure valve opens under pressure action in the regeneration flow path and connects the regeneration flow path to the other actuator. A regeneration and priority hydraulic control device comprising a check valve that communicates with the engine port, and a passageway that leads the pilot pressure of the pilot switching valve to the spring chamber of the back pressure valve.