JPH0454081B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a valve that supplies pressure oil to a work machine actuator that drives a work machine such as a construction machine.

For example, a spool is slidably provided on the valve body,
A pilot-operated valve is used that uses a spring force to hold this spool in a neutral position that does not supply pressure oil from the hydraulic pump to the work equipment actuator, and uses pilot pressure oil supplied to the oil chamber to slide the spool to the pressure oil supply position. It is being

[Problem to be solved by the invention]

If the valve is of such a pilot operated type,
By switching and operating a small pilot valve, the spool of the valve can be slid, reducing operating force, and switching operations can be performed by remote control. However, on the other hand, the pilot hydraulic pressure is required to supply pilot pressure oil to the oil chamber. Pumps are wasteful because their discharge pressure oil is only supplied to the oil chamber and cannot be used for other purposes.

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

[Means and actions for solving the problem]

The valve body 98 includes a main pressure oil supply side chamber 65, a tank side chamber 51, and a first chamber 35 of the work machine actuator.
and two chambers 50 on the work machine actuator side are opened in spool holes 99, and a spool 18 for communicating and blocking each chamber is inserted into the spool hole 99 of the valve body 98, and this spool 18 is connected to a spring. The spool 18 is held in a position where each chamber is shut off by force, and the spool 18 is communicated with the chamber 65 on the main pressure oil supply side and the first chamber 35 on the work machine actuator side using the pressure oil in the first oil chamber 41. and the second one on the work equipment actuator side.
The first position communicates the chamber 50 on the tank side with the chamber 51 on the tank side, and the pressure oil in the second oil chamber 47 communicates the chamber 65 on the main pressure oil supply side and the second chamber 50 on the work machine actuator side. And the first one on the work equipment actuator side
A first chamber 32 on the pilot pressure supply side and a second chamber 73 on the pilot pressure supply side are formed in the valve body 98. , the first chamber 32 on the pilot pressure supply side is communicated with the first chamber 35 on the work machine actuator side via a constriction part, and the first chamber 32 on the pilot pressure supply side communicates with the first chamber 35 on the work machine actuator side through the constriction part.
The first chamber 35 on the work machine actuator side communicates with the first oil chamber 41, and the first chamber 35 on the work machine actuator side communicates with the second oil chamber 41.
The second chamber 73 on the pilot pressure supply side is communicated with the second chamber 50 on the work machine actuator side via a constriction part, and the pilot pressure supply side A valve in which a second chamber 73 side of the valve is connected to the second oil chamber 47, and a second chamber 50 side of the working machine actuator side is connected to the first oil chamber 41.

As a result, the pressure oil supplied to the first or second chamber 32, 73 on the pilot pressure supply side flows through the constriction part to the first or second chamber 35, 50 on the work machine actuator side, and the constriction A differential pressure is generated before and after the spool 18, and the differential pressure is supplied to the first or second oil chamber 41, 47 of the spool 18, and the spool 18 is in the first or second position, and the main pressure oil supply side is chamber 65 and the first or second chamber 35 on the work machine actuator side,
50 communicates with each other, and the second or first chamber 50, 35 on the work machine actuator side communicates with the chamber 51 on the tank side, and the pressure oil and pilot pressure supply side are supplied to the main pressure oil supply side chamber 65. the first or second chamber 32,
The pressure oil supplied to the work machine actuator 73 merges to form a valve that can effectively utilize the pilot pressure oil that switches the spool 18 supplied to the work machine actuator by supplying it to the work machine actuator.

In addition, pilot pressure oil is supplied to the chamber 32 or 73 on the pilot pressure oil supply side, and the spool 18 is switched to the chamber 35 on the work machine actuator side.
Or, if the work equipment actuator is actuated by an external load and the return flow rate to the chamber 50 or 35 on the other work equipment actuator side increases while pressure oil is being supplied to the work equipment actuator from the spool 18. Since the pressure difference between the first and second oil chambers 41 and 47 can be ensured by the pressure difference before and after the throttle part on the chamber 32 or 73 side on the pilot pressure oil supply side, the spool 18 does not vibrate and the work machine Actuator hunting can be prevented.

Furthermore, even when main pressure oil and pilot pressure oil are not generated, by communicating the second chamber 73 on the pilot pressure supply side with the tank, the work equipment actuator can be lowered slowly by an external load, and the tank By increasing the communication area to the constriction part, a pressure difference is generated before and after the throttle part, and the spool 18 can be switched and the work machine actuator can be lowered rapidly.

〔Example〕

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

In Fig. 3, 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 unloading valve, 17 is a main valve which is a valve according to the present invention, and 55 is a shuttle valve. . The first control valve 3 and the unload valve 6 constitute 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 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.

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 valve 40 communicates with chamber 102 via passage 39, port 40b of shuttle valve 40 communicates with chamber 80 via passage 90, and port 40c communicates with chamber 102 via passage 90'.
It leads to 1.

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 shuttle 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 discharge side of the first pump 1 is connected to the port 6a of the unload valve 6 via a branch point 63. It has been done. The chamber 51 of the main valve 17 communicates with the tank 111 via a pipe 70. Main valve 17 chamber 3
5 and 50 are connected to the ripper cylinder 16, which is the working machine actuator B, via pipes 36 and 68. In addition, the chambers 32 and 73 of the main valve 17
are connected to the chambers 30, 75 of the third control valve 5 via pipes 31, 74.

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.
11, the shuttle valve 55 is connected to the chamber 9 through the groove 8 cut out in the spool 12, and is connected to the tank 1 through the pilot pipe 13 from the shuttle valve 10 through 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 2 has second and third control valves 4,
5 through pipe 15 through unload valve 6
However, the unload valve 6 is connected to the second
As shown in the figure, the communication position is located on the port side, and the second pump 2 is also in an 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, the flow of the second pump 2 that has been flowing from the piping 20 from the chambers 22, 24 of the third control valve 5 through the constrictions 25, 26 of the spool 19 is reduced. At the same time, the flow pushes open the check valve 27 and flows from the chamber 28 to the spool 1.
It passes around the constriction 29 of 9 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 part 34 of the spool 33, and into the chamber 35. It flows into the bottom side of the ripper cylinder 16 through the conduit 36, and at the same time flows into the notch of the spool 33. The pressure on the high pressure side before passing through the spool 34 is passed through the through hole 37 made in the spool 33, through the chamber 102 of the spool 33, through the passage 39, and through the shuttle valve 40 to the spool 18 of the main valve 17.
It is led to a chamber 41 which is a pressure chamber at one end of the chamber. On the other hand, the pressure on the low pressure side after passing through the notch 34 of the spool 33 is guided through a chamber 43 at one end of the spool 33 to a chamber 47 which is a pressure chamber at the other end of the spool 18 through a hole 42 made in the spool 33. . 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.
The communication between the chamber 49 of the main valve 17 and the chamber 35 is closed or opened. Further, the relationship between the chamber 50 connected to the rod side of the ripper cylinder 16 and the chamber 51 which is the tank port of the main valve 17 is changed from the closed state to the 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, spool 1 of third control valve 5
When 9 is in the push position, the ripper cylinder 16
can be driven to the contraction side.

In addition, in the main valve 17, the chamber 35 is located 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 1 merges with the flow rate of the second pump 2. It's summery. Therefore, the flow rate of the first pump 1 joins the flow rate of the second pump 2 in the chamber 35, and the pressure in the chamber 35 increases the pressure in the divided chamber 32. 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, so the flow rate from the rod side of the ripper cylinder 16 to the chamber 50 > the flow rate from the chamber 35 to the bottom side of the ripper cylinder 16. In this case, the differential pressure is the pressure before and after the notch 72 of the spool 71, In other words, the pressure is determined by the pressure in the chamber 50 (upstream side) and the chamber 73 (downstream side), and the high pressure oil in the chamber 50 passes through the through hole 79, the chamber 80, and the passage 90 to the shuttle valve 40.
is led to the chamber 41 from the port 4c of the spool 1.
8 in a downward direction in FIG.

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 decreases, making it impossible to ensure a differential pressure across the notch 72, and the spool 18 is pushed back by the spring 47, reducing the opening area of the constricted portion 69 of the spool 18. 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 72 increases, pushing the spool 18 again, and this operation is repeated until the spool 18 is pushed. This will cause the ripper cylinder 16 to vibrate and cause hunting. but,
Since the minimum pressure difference between the oil chamber 41 and the oil chamber 47 of the spool 18 is secured by the pressure difference generated by the flow rate from the chamber 32 to the chamber 35 through the pipe line 31 from the second pump 2, the above-mentioned There is no vibration of the spool 18 and no hunting of the ripper cylinder 16.

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, and the ripper cylinder can operate smoothly. It becomes possible.

Also, the engine stopped and the first and second pumps 1 and 2
It is necessary to lower the work equipment to the ground even when there is no flow rate. 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 placed 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 71.
It passes through the notch 72 of the chamber 73, passes through the pipe 74 to the chamber 75 of the third control valve 5, and returns to the tank 111 through the constriction 76 of the spool 19, which is in the open state, from the chamber 77, which is the tank port, through the pipe 78. , due to the flow, the spool 71
A differential pressure is generated before and after the notch 72 of.

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 is small and the spool 18 will not switch. Since the flow rate on the rod side 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, while a vacuum is generated on the bottom side of the ripper cylinder 16, the ripper cylinder 1
6 descends.

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 becomes large, creating a through hole 79 in the spool 71 on the high pressure side, which is led to the pressure chamber 41 of the spool 18 through a chamber 80, a passage 90, and the shuttle valve 40, and a through hole 79 in the spool 71 on the low pressure side. 91 is led to a chamber 47 which is a pressure chamber of the spool 18 via a passage 92 and a shuttle valve 45. 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 head 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. Par cylinder 16 can be lowered rapidly. At this time, a vacuum is generated on the bottom side of the ripper cylinder 16. As described above, even when the engine is stopped, by operating the spool 19 of the third control valve 5, the ripper cylinder 16 can be slowly lowered, and the spool 18 of the main valve 17 can be lowered slowly.
The ripper cylinder 16 can be lowered rapidly by switching to allow the work equipment to fall suddenly, which is required for construction equipment, and the cutting edge can be dug into the ground by the work equipment's own weight (emergency braking when the engine is stopped). It is.

(Effect of the invention) The first or second chamber 32 on the pilot pressure supply side,
The pressure oil supplied to the spool 73 flows through the constriction part to the first or second chamber 35, 50 on the work machine actuator side, and a pressure difference is generated before and after the constriction part. 1 or 2nd oil chamber 41, 47
The spool 18 is in the first or second position, and the chamber 65 on the main pressure oil supply side communicates with the first or second chamber 35, 50 on the work equipment actuator side, and the spool 18 is in the first or second position. second or first
The chambers 50, 35 communicate with the chamber 51 on the tank side, and the pressure oil supplied to the chamber 65 on the main pressure oil supply side and the pressure supplied to the first or second chamber 32, 73 on the pilot pressure supply side. The oil is combined and supplied to the work machine actuator.

Therefore, the valve can supply the pilot pressure oil from the spool 18 to the working machine actuator and utilize it effectively.

Further, since the first and second chambers 32 and 73 on the pilot pressure oil supply side communicate with the first and second chambers 35 and 50 on the work machine actuator side through the throttle part, one pilot When pilot pressure oil is being supplied to the chamber 32 or 73 on the pressure oil supply side and the spool 18 is being switched to supply pressure oil to the work implement actuator from the chamber 35 or 50 on the work implement actuator side, the work implement actuator is When the return flow rate to the chamber 50 or 35 on the other working machine actuator side increases due to actuation by an external load, the first and second oil chambers 41, 4 of the spool 18
7 pressure difference between one pilot pressure oil supply side chamber 3
Since this can be ensured by the differential pressure before and after the throttle part on the 2 or 73 side, the spool 18 does not vibrate, and hunting of the work machine actuator can be prevented.

Furthermore, even when main pressure oil and pilot pressure oil are not generated, by communicating the second chamber 73 on the pilot pressure supply side with the tank, the return flow rate from the work equipment actuator flows to the tank through the throttle part.
The work equipment actuator can be lowered slowly by an external load, and by increasing the communication area to the tank, a large differential pressure is created before and after the throttle part, and by switching the spool 18, the work equipment actuator can be lowered slowly. Since a large amount of return flow flows into the tank from the tank-side chamber 51, the working machine actuator can be lowered rapidly by an external load.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, with FIG. 1 being an explanatory diagram of the configuration, and FIGS. 2 and 3 being explanatory diagrams of the operation of the unload valve. 18 is a spool, 32 and 73 are chambers on the pilot pressure supply side, 41 and 47 are oil chambers, 35 and 50 are chambers on the work machine actuator side, and 65 is a chamber on the main pressure oil supply side.

Claims (1)

[Claims] 1 In the valve body 98, a chamber 65 on the main pressure oil supply side, a chamber 51 on the tank side, a first chamber 35 on the work machine actuator side, and a second chamber 50 on the work machine actuator side are opened in the spool hole 99, respectively. A spool 18 is inserted into the spool hole 99 of the valve body 98 to connect and shut off each chamber.
is held in a position that blocks each chamber by spring force,
The spool 18 is connected to the main pressure oil supply side chamber 65 and the first chamber 35 on the work machine actuator side using the pressure oil in the first oil chamber 41, and connects the second chamber 50 on the work machine actuator side to the tank. This is the first position where the side chamber 51 is communicated with, and the pressure oil in the second oil chamber 47 communicates between the main pressure oil supply side chamber 65 and the second chamber 50 on the work equipment actuator side, and the work equipment actuator. The first chamber 35 on the side and the chamber 51 on the tank side communicate with each other, and the valve body 98 has a first chamber 32 on the pilot pressure supply side and a second chamber 32 on the pilot pressure supply side. 73, and communicates the first chamber 32 on the pilot pressure supply side with the first chamber 35 on the work machine actuator side via a constriction part,
The first valve on the pilot pressure supply side with this constriction as a boundary
The chamber 32 side communicates with the first oil chamber 41, the first chamber 35 side on the work machine actuator side communicates with the second oil chamber 47, and the second chamber on the pilot pressure supply side communicates with the first chamber 41. 73 is communicated with the second chamber 50 on the work machine actuator side through a constriction part, and with this constriction as a boundary, the second chamber 73 on the pilot pressure supply side is communicated with the second oil chamber 47. , and a portion near the second chamber 50 on the work machine actuator side is communicated with the first oil chamber 41.