JPH0454082B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for supplying pressure oil discharged from two pumps to one work machine actuator.

[Conventional technology]

The discharge pressure oil of the first pump is supplied to the work equipment actuator by the first valve, and the discharge pressure oil of the second pump is supplied to the work equipment actuator by two valves, so that the discharge pressure oil of the first and second pumps is combined into one. Methods for supplying work machine actuators are known.

[Problem to be solved by the invention]

With such a pressure oil supply method, it is necessary to switch between the first valve and the second valve, which makes the operation cumbersome.

Therefore, an object of the present invention is to provide a pressure oil supply method that can solve the above-mentioned problems.

[Means and actions for solving the problem]

The pressure oil discharged from the first pump 1 is supplied to one of the bottom side and the rod side of the work equipment actuator by the pilot-operated main valve 17, and the other pressure oil from the bottom side and the rod side flows out to the tank. The pressure oil discharged from the two pumps 2 is supplied via a throttle part to one of two circuits that communicate the output side of the main valve 17 with the bottom side and rod side of the work equipment actuator, using a manually operated control valve 5. , and the other of the two circuits is connected to the tank via a constriction part, and a pressure difference is created before and after the constriction part by the flow of pressure oil from this second pump 2, and the pressure difference is utilized. A pressure oil supply method in which the spool 18 of the main valve 17 is operated by switching.

As a result, when the control valve 5 is switched and the pressure oil discharged from the second pump 2 is supplied to the work equipment actuator, a pressure difference is generated due to the pressure oil flow, and this pressure difference is used to control the main valve 1.
7, the main valve 17 can be switched by switching one control valve 5 to supply the discharge pressure oil of the first and second pumps 1 and 2 to the work equipment actuator, and the pressure oil can also be supplied to the work equipment actuator. When the work equipment actuator is actuated by an external load and the return flow rate to the other circuit increases while supplying water, the main valve 17 is switched to the position using the differential pressure before and after the throttle part provided in one circuit. This prevents the main valve 17 from vibrating and prevents hunting of the work equipment actuator.Furthermore, the control valve 5 can be maintained even when main pressure oil and pilot pressure oil are not generated.
By switching the main valve 17, the work equipment actuator can be lowered slowly by an external load, and by increasing the communication area to the tank, a pressure difference is created before and after the throttle part, and the main valve 17 is switched. can descend rapidly.

〔Example〕

Hereinafter, the present invention will be explained with reference to FIGS. 1 to 3.

In Fig. 1, 1 and 2 are the first and second pumps, and 3
1 is a first control valve for the blade, 4 is a second control valve for tilting, 5 is a third control valve, 6 is an unload valve, 17 is a main valve, and 55 is a yettle valve. and,
First control valve 3 and unload valve 6
This constitutes a proportional control valve A with pressure compensation.

The third control valve 5 includes a valve body 91, and the valve body 91 has a spool hole 92.
is provided in the valve body 91, and a spool hole 9 is provided in the valve body 91.
Room 23, 30, 75, 77, 53, 2 leading to 2
2, 24, and 28 are provided. A spool 19 is fitted into the spool hole 92, and spring seats 94 and 95 are provided at the ends of the spool 19 in contact with their respective shoulders.
6 is provided. The chambers 22, 24 communicate with the chamber 28 via a passage 97, in which the check valve 27 is provided.

The passage 97, the check valve 27, the chamber 77, and the chamber 30 form an operating pressure circuit section E, and the passage 97 and the chamber 2
3, the passage 97, the chamber 24, and the chamber 53 form a pilot pressure circuit section F.

The main valve 17 includes a valve body 98, and the valve body 98 has spool holes 99, 10.
0,101 are provided.

The valve body 98 has a chamber 4 communicating with the spool hole 99.
Further, the valve body 98 is provided with chambers 32, 35 communicating with the spool hole 100, and the valve body 98 is provided with chambers 50, 73 communicating with the spool hole 101.

A spool 18 is fitted into the spool hole 99, and the spool 18 is held neutrally by springs 48 and 48' at both ends thereof. 4
7, and these form the first valve part 1.

A spool 33 is fitted into the spool hole 100, and is held neutrally by a spring 38. Perforated holes 37 and 42 are formed in the spool 33, and these form a first valve portion G.

A spool 71 is inserted into the spool hole 101, and this spool 71 is held neutrally by a spring 38'.The spool 71 is also formed with drilled holes 79 and 91, which allow the second
A valve portion H is formed.

The valve body 98 is provided with shuttle valves 40 and 45.

Port 40a of shuttle 40 communicates with chamber 102 via passage 39, and port 40a of shuttle valve 40 communicates with chamber 102 via passage 39.
0b communicates with chamber 80 via passage 90, and port 40c communicates with chamber 41 via passage 90'.

Port 45a of shuttle valve 45 communicates with chamber 103 via passage 92, another port 45b communicates with chamber 43 via passage 44, and yet another port 45c communicates with chamber 47 via passage 46. I understand. A check valve 66 is provided in the passage 104 from the chamber 65 to the chamber 49.

The shaft valve 55 includes a valve body 7,
A spool hole 110 is provided in the valve body 7, and a plug 57 is fitted into the end of the spool hole 110. A spool 12 is provided in the spool hole 110, and a piston 56 is fitted into the end of the spool 12. The spool 12 is urged toward the plug 57 by a spring 58. The valve body 7 is provided with chambers 9, 59, 60 communicating with the spool hole 12.

The discharge side of the first pump 1 is connected to the chamber 65 of the main valve 17 via a pipe 64, and the first
The discharge side of the pump 1 is connected to the port 6a of the unload valve 6 via a branch point 63. The chamber 51 of the main valve 17 is connected to the tank 1 via piping 70.
It leads to 11. chamber 35 of main valve 17;
50 is connected to the ripper cylinder 16, which is the work machine actuator B, via pipes 36 and 68. Further, the chambers 32 and 73 of the main valve 17 are connected to the third control valve 5 through pipes 31 and 74.
It is connected to the chambers 30 and 75.

The discharge side of the second pump 2 is connected to the third pump via piping 20.
It is connected to the passage 97 of the control valve 5, and the other work machine actuator C is connected to this piping 20.
A second control valve 4 of the tilt cylinder 112 is provided. The chamber 23 of the third control valve 5 is connected to the port 6b of the unload valve 6 via the pipe 21, and the chamber 23
is connected to port 3a of first control valve 3 via piping 15.

The first control valve 3 operates the blade cylinder 113, which is another working machine actuator D. The chamber 77 of the third control valve 5 is connected to the tank 111 via a pipe 78.

The chamber 53 of the third control valve 5 is connected to the chamber 59 of the shuttle valve 55 via a pilot line 54, and the chamber 60 of the shuttle valve 55 is connected to the pilot port 6d of the unload valve 6 via a pilot line 62. It is connected to.

A throttle 11 is provided in this pilot conduit 62. A pilot line 115 branches off from the pipe 15, and this pilot line 115 is connected to a pilot port 6e of the unload valve 6.

The chamber 9 of the shuttle valve 55 is connected to the shuttle valve 10 via a pilot line 13.

Operation of the device of the embodiment When the engine is rotating and the first, second, and third control valves 3, 4, and 5 are in the neutral state as shown in FIG. Since it is in the closed state, the pilot pressure at the left end of the unload valve 6 increases, and the spring side pressure at the right end of the unload valve 6 decreases to the throttle 1.
1. It is connected to the chamber 9 through the groove 8 cut out in the spool 12 of the shuttle valve 55, and is connected to the tank 1 through the pilot pipe 13 from the shuttle valve 10 to the first control valve 3 through the drain passage 14.
11, the unload valve 6 is in the state shown in FIG. 2, and the first pump 1 is in the unload state at low pressure. On the other hand, the discharge side of the second pump 22 is connected to an unload valve 6 by a pipe 15 through the second and third control valves 4 and 5, but the unload valve 6 is connected to the port side as shown in FIG. The communication position is in the state, and the second pump 2 is also in the unloaded state at low pressure.

Note that when the first control valve 3 and the third control valve 5 are operated simultaneously, the first control valve 3 is given priority. Therefore, the spool 12 of the shuttle valve 55 is pressed against the plug 57, and the unload valve 6 takes a position where it can supply oil from the first and second pumps 1 and 2 to the first control valve 3. But in this case,
Since the relationship between the first control valve 3 and the main valve 17 is a parallel circuit, the pump oil flows to the side with the lighter load. In the circuit shown in FIG. 1, it is practically rare to operate the first and third control valves 3 and 5 simultaneously, and no particular consideration is given to the flow distribution in that case.

In the shuttle valve 55, the spool 12 and the piston 56 are provided with a difference in area in order to give priority to the circuit of the first control valve 3 as described above.

When the spool 19 of the third control valve 5 is operated to the pulled state, water flows from the pipe 20 from the chambers 22 and 24 of the third control valve 5 through the constrictions 25 and 26 of the spool 19 to the second pump 2.
The flow is closed, and at the same time the flow opens the check valve 27 and flows from the chamber 28 to the spool 19.
It passes around the constriction 29 of and communicates with the chamber 30. It flows from the chamber 30 through the conduit 31, from the chamber 32 of the main control valve 17, through the notch 34 of the spool 33, into the chamber 35, and at the same time flows into the bottom side of the ripper cylinder 16 through the conduit 36. The pressure on the high pressure side before passing through the spool 33 is passed from the drilled hole 37 in the spool 33 through the chamber 102 of the spool 33 to the pipe 39 and the shuttle valve 40 to the chamber 41 which is a pressure chamber at one end of the spool 18 of the main valve 17. be guided. On the other hand, the pressure on the low pressure side after passing through the notch 34 of the spool 33 passes through a chamber 43 at one end of the spool 33 through a drilled hole 42 in the spool 33 and into a chamber 47 which is a pressure chamber at the other end of the spool 18. be guided. As a result, the spool 18 moves until the differential pressure between the pressure chambers 41 and 47 and the spring 48 in the chamber 47 are balanced.
Communication between chamber 49 and chamber 35 of main valve 17 is changed from closed to open. Also, the ripper cylinder 16
The chamber 50 connected to the rod side of the main valve 17 also changes its relationship with the chamber 51, which is the tank port of the main valve 17, from a closed state to an open state.

On the other hand, in response to a pull signal from the third control valve 5, the gap between the chambers 24 and 53 is changed from the closed state to the open state by the notched groove 52 cut out in the spool 19, and the pump pressure is controlled by the pilot pipe 54 to the shuttle valve. 55
acts on the piston 56 provided in the spool 12, which is held down by a plug 57,
The spool 12 is moved to the left by the spring 58,
The notch 8 that opened the chambers 60 and 9 is closed, and the chambers 59 and 60 are opened through the constriction 61 of the spool 12, leading to the spring chamber side of the unload valve 6 through the pilot pipe 62 and the throttle 11. It will be destroyed.
As a result, the pressure of the second pump 2 forces the unload valve 6, which was in the unload state shown in FIG. 2, into the on-load state shown in FIG. The chamber 6, which is the pump port of the main valve 17, passes through the pipe 64.
5, press the check valve 66 to open the chamber 49, pass through the constriction 67 of the open spool 18, merge with the flow rate of the second pump 2 in the chamber 35, and flow to the cylinder bottom side, extending the ripper cylinder 16 from the cylinder rod side. The return flow rate is returned from the pipe 68 to the chamber 50, through the constriction 69 of the spool 18 in the open state, and from the chamber 51, which is a tank port, to the tank 111 through the pipe 70.

Similarly, the spool 1 of the third control valve 5
The ripper cylinder 16 can also be driven to the contraction side when the lever 9 is in the push position.

In addition, in the main valve 17, the chamber 35 is on the downstream side with respect to the chamber 32 when the ripper cylinder 16 is extended even when the flow rate of the first pump merges with the flow rate of the second pump 2. ing.
Therefore, the flow rate of the first pump 1 merges with the flow rate of the second pump 2 in the chamber 35, and the pressure in the chamber 35 increases.
Increase the pressure in step 2. Because of this, the pressure difference is maintained.

Furthermore, since the differential pressure caused by the flow of oil is utilized, it is not affected by the load pressure of the ripper cylinder 15 or the direction of the load.

That is, if the extension side of the ripper cylinder 16 is the natural fall side in FIG. The cylinder 16 moves to the extension side due to the weight of the ripper, and the volume on the bottom side increases faster than the supply flow rate, and the supply flow rate to the bottom side becomes insufficient and a vacuum is generated, and the ripper cylinder 16
operates on the extension side, the flow rate from the rod side of the ripper cylinder 16 to the chamber 50 may be greater than the flow rate from the chamber 35 to the bottom side of the ripper cylinder 16.

In this case, the differential pressure is determined by the pressure before and after the notch 72 of the spool 71, that is, the pressure in the chamber 50 (upstream side) and the chamber 73 (downstream side). Shuttle valve 40 via 90
The spool 18 is guided to port 4c or chamber 41 of
is moved downward in Figure 3, therefore,
The oil of the first pump 1 flows into the chamber 35 and enters the bottom side of the ripper cylinder 16.

At this time, when the opening area from the chamber 50 to the chamber 51 determined by the stroke of the spool 18 increases, most of the return flow from the ripper cylinder 16 passes from the chamber 50 to the chamber 51 through the constriction 69 of the spool 18. As a result, the flow rate from the chamber 50 to the chamber 73 through the notch 72 is reduced, and the differential pressure across the notch 72 is no longer ensured.The spool 18 is pushed back by the spring 47, and the opening area of the constricted portion 69 of the spool 18 is reduced. As a result, the flow rate from the chamber 50 to the chamber 73 through the notch 72 increases, and the differential pressure across the notch 722 increases, pushing the spool 18 again, and this operation is repeated until the spool 18 vibrates, causing the ripper cylinder 16 to hunt. However, through the conduit 31 from the second pump 2
Since the minimum differential pressure between the oil chamber 41 and the oil chamber 47 of the spool 18 is ensured by the differential pressure generated in the device from 2 to the chamber 35, the spool 18 does not vibrate as described above, and the ripper cylinder 16 does not hunt. Nor. In this way, by providing the throttles that communicate with the chambers 35 and 50 connected to the ripper cylinder 16, a stable differential pressure can be obtained over the entire stroke of the spool 18, allowing smooth operation of the ripper cylinder. .

Also, the engine stopped and the first and second pumps 1 and 2
Even when there is no flow rate, it is necessary to lower the work equipment to the ground, for example, due to its own weight, the ripper cylinder 16
If we consider the case where the
When the spool 19 of the control valve 5 is in the pulled position, the return flow rate on the rod side of the ripper cylinder 16 flows from the pipe 68 through the chamber 50 to the spool 7.
1 through the notch 72 of the chamber 73 and the piping 74 to the chamber 75 of the third control valve 5, and through the constriction 76 of the spool 19 in the open state and from the chamber 77 which is the tank port through the piping 78 to the tank 111. The flow returns to spool 7.
A differential pressure is generated before and after the notch 72 of 1.

If the operation stroke of the spool 19 to the pulled position is small and the opening areas of the chambers 75 and 77 are small, the differential pressure across the notch 72 will be small and the spool 18 will not be switched. Since the flow rate on the rod side of the spool 16 flows into the tank 111 only through the notch 72 of the spool 71, the flow rate is small and the ripper cylinder 16 slowly descends. At this time, the ripper cylinder 16
The ripper cylinder 16 descends while a vacuum is generated on the bottom side.

When the operation stroke of the third control valve 5 to the pulled position of the spool 19 is large, the notch 7 of the spool 71 is
The differential pressure generated before and after increases and is led to the pressure chamber 41 of the spool 18 through the through hole 79 of the spool 71 on the high pressure side, through the chamber 80, the passage 90, and the shuttle valve 40. It is led from there through a passage 92 and a shuttle valve 45 to a chamber 47 which is a pressure chamber of the spool 18. As a result, the spool 18 is pushed down and the chamber 5
0 and the chamber 51 changes from closed to open, and a large amount of the return flow from the rod side of the ripper cylinder 16 passes through the constriction 69 of the spool 18, returns to the tank 111 via the piping 70 to the tank 111, and returns to the tank 111 in large quantities. 16 can descend rapidly. At this time, a vacuum is generated on the bottom side of the ripper cylinder 16. As mentioned above, even if the engine is stopped, the
By operating the spool 19 of the control valve 5, the ripper cylinder 16 can be lowered slowly, or by switching the spool 18 of the main valve 17, the ripper cylinder 16 can be lowered rapidly, which is necessary for construction machinery. It is possible to cause the work equipment to fall suddenly and use its own weight to dig the cutting edge into the ground (emergency brake when the engine is stopped).

〔Effect of the invention〕

When the control valve 5 is switched and operated to supply the discharge pressure oil of the second pump 2 to the work equipment actuator, a pressure difference is generated due to the pressure oil flow, and the main valve 17 is switched and operated using the pressure difference. Therefore, by switching one control valve 5, the main valve 17 can be switched to supply the discharge pressure oil of the first and second pumps 1 and 2 to the work machine accruator, and the operation becomes simple.

Further, the pressure oil discharged from the second pump 2 is supplied to one of the circuits connecting the bottom side and rod side of the work equipment actuator and the output side of the main valve 17 through the throttle part by the control valve 5, and the other circuit is connected to the output side of the main valve 17. Since the control valve 5 communicates with the tank, when the work equipment actuator is actuated by an external load while supplying pressure oil to the work equipment actuator and the return flow rate to the other circuit increases, the return flow rate to the other circuit increases. Since the main valve 17 can be secured in the switching position by the differential pressure before and after the throttle portion provided, the main valve 17 will not operate, and hunting of the work machine actuator can be prevented.

In addition, even when main pressure oil and pilot pressure oil are not generated, by switching the control valve 5, the rod side and the tank are communicated, and the return flow from the work equipment actuator flows to the tank through the throttle part, so the work equipment actuator can be lowered slowly by an external load, and by increasing the communication area to the tank, a large pressure difference is created before and after the throttle part, and the main valve 17 is switched to control the return flow rate from the work equipment actuator to the main flow rate. The valve 17 allows a large amount of water to flow into the tank, allowing the work implement actuator to be lowered rapidly by an external load.

[Brief explanation of drawings]

The drawings show embodiments of the present invention, and FIG. 1 is a configuration explanatory diagram showing an example of an apparatus for carrying out the method of the present invention.
FIGS. 2 and 3 are explanatory views of the operation of the unload valve. 1 is a first pump, 2 is a second pump, 5 is a control valve, 17 is a main valve, and 18 is a spool.

Claims (1)

[Scope of Claims] 1. The pressure oil discharged from the first pump 1 is supplied to one of the bottom side and the rod side of the work equipment actuator by a pilot-operated main valve 17, and the pressure oil is supplied to the bottom side and the rod side of the work equipment actuator. flows into the tank, and the pressure oil discharged from the second pump 2 is connected to one of two circuits that communicate the output side of the main valve 17 with the bottom side and rod side of the work equipment actuator using a manually operated control valve 5. supplying the oil through a constriction part, and connecting the other of the two circuits to the tank via the constriction part, and creating a pressure difference before and after the constriction part by the flow of pressure oil from the second pump 2, A pressure oil supply method characterized in that the spool 18 of the main valve 17 is switched and operated using the pressure difference.