JPH02225806A - Pressure oil supply control method for work equipment cylinders - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a pressure oil supply control method for supplying pump discharge pressure oil to a working machine cylinder of a construction machine.

[Conventional technology]

As a method of supplying pump discharge pressure oil to work equipment cylinders that move work equipment in the vertical direction, such as blade cylinders, ripper cylinders, arm cylinders, and boom cylinders of construction machinery, for example, the pump discharge pressure oil is pilot operated. A known method is to control the supply to the raising chamber and lowering chamber of a working machine cylinder using a valve.

[Problem to be solved by the invention]

This pressure oil supply control method reduces the operating force of the valve and allows remote control, but since the valve is switched by pilot pressure, the pump that generates the pilot pressure may break down, or the pump may If the engine driving the machine stops or pilot pressure is not generated, the valve cannot be switched and the work machine cylinder cannot be extended or contracted, causing the work machine to stop at an arbitrary position.

As described above, if the work machine is left stopped at an arbitrary position, for example, an upper position, the work machine may descend for some reason, which is very dangerous.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a pressure oil supply control method for a working machine cylinder that can solve the above-mentioned problems.

[Means and actions for solving the problem] The pump discharge pressure oil is supplied to the lifting chamber of the working machine cylinder by a pilot-operated main valve that is switched and operated by pilot pressure.
When the pilot pressure is not generated, the pressure oil in the lifting chamber of the work equipment cylinder is circulated to the tank side to generate a pressure difference, and the pressure difference is used to switch the main valve. This is a supply control method, whereby even if pilot pressure is not generated, the main valve can be switched and the pressurized oil in the lifting chamber of the working machine cylinder can be discharged to the tank side through the main valve.

〔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, 3 is the first control valve for the blade, 4 is the second control valve for tilting, 5 is the third control valve, 6 is the unload valve, 17 is a main valve, and 55 is a shuttle valve.

And 1. 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 is provided with a spool hole 92.
The valve body 91 also has a chamber 23.3 communicating with the spool hole 92.
0.75.77°53.22, 24.28 is the setting. One spool is inserted into the spool hole 92, and spring seats 94.95 are provided at the ends of the spool 19 in contact with the respective shoulders.
6 is a provision. 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, the chamber 23, and the passage 97
, chamber 24, and chamber 53 form a pilot pressure circuit section F.

The main valve 17 includes a valve body 98, and the valve body 98 is provided with a spool hole 99°100.101.

The valve body 98 is provided with a chamber 49.51 that communicates with the spool hole 99, the valve body 98 is provided with a chamber 32.35 that communicates with the spool hole 100, and the valve body 98 is provided with a chamber that communicates with the spool hole 101. The setting is 50°73.

A spool 18 is fitted into the spool hole 99, and this spool 18 is supported by springs 48, 48' at both ends.
Both ends of the spool hole 99 are formed into oil chambers 41 and 47, and these form the first valve part I.

A spool 33 is fitted into the spool hole 100, and is held neutrally by a spring 38. The spool 33 has drill holes 37 and 42 formed therein, and these form the first valve part 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 a shuttle valve 40,45.

The chamber 35 communicates with the chamber 51 via a suction valve 140.

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

The boat 45a of the shuttle valve 45 is connected to the chamber 1 through the passage 92.
03, another boat 45b communicates with the chamber 43 via the passage 44, and another boat 45c communicates with the chamber 43 via the passage 44.
6 into chamber 47. 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 spool hole 110.
A plug 57 is fitted into the end of the . Spool hole 11
0 is provided with a spool 12, and the spool 12
A piston 56 is fitted into the end of the cylinder. Spool 12
is urged toward the plug 57 by a spring 58.

The valve body 7 has a chamber 9,59°60 communicating with the spool hole 12.
is the provision.

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 boat 6 of the unload valve 6 via a branch point 63.
It is connected to a.

The chamber 51 of the main valve 17 is connected to the tank 1 via piping 70.
It leads to 11. The chamber 35.50 of the main valve 17 is connected to the ripper cylinder 1B, which is the work implement actuator B, via a pipe 36.68. Further, the chamber 32.73 of the main valve 17 is connected to the third chamber 32.73 via the pipe 31.74.
It is connected to chamber 30.75 of control valve 5.

The discharge side of the second pump 2 is connected to the passage 97 of the third control valve 5 via a pipe 20.
Tilt cylinder 1, which is the other work equipment actuator C,
Twelve second control valves 4 are provided. The chamber 23 of the third control valve 5 is connected to the boat 6b of the unload valve 6 via a pipe 21, and the chamber 23 is connected to the boat 3a of the first control valve 3 via a pipe 15. .

1st control valve 3! This is to operate 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 the pilot pipe 5
The chamber 60 of the shuttle valve 55 is connected to the pilot boat 6d of the unload valve 6 via a pilot line 62.

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

Chamber 9 of shuttle valve 55 is connected to shuttle valve 10 via pilot line 13.

Operation of the device of the embodiment When the engine is rotating and the first, second and third control valves 3, 4.5 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 is connected to the chamber 9 through the throttle 11 and the groove 8 cut in the spool 12 of the shuttle valve 55. , pilot line 13
from the shuttle valve 10 through the first control valve 3
Since it is connected to the tank 111 through the drain passage 14, 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 is connected to an unload valve 6 by a pipe 15 through the second and third control valves 4 and 5, and the unload valve 6 is in a position communicating with the boat side as shown in FIG. 'WS2 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, spool 1 of shuttle valve 55
2 is in a pressed state against the plug 57, and the unload valve 6 supplies the first and second control valves 3 to the first control valve 3.
Take a position where oil can be supplied to pumps 1 and 2. However, in this case, the first control valve 3 and the main valve 17
Since the relationship between the two is a parallel circuit, the oil will flow to the one with the lighter load. In the circuit shown in FIG. 1, it is practical to operate the first and third control valves 3 and 5 simultaneously, and no particular consideration is given to flow rate 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 prioritize 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 was flowing from the pipe 20 from the chamber 22.24 of the third control valve 5 through the constriction 25.26 of the spool 19 is At the same time, the check valve 27 is forced open, and the flow passes from the chamber 28 around the waist 29 of the spool 19 to the chamber 30.
Leads to. 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 and into the chamber 35, and at the same time flows into the lowering chamber of the ripper cylinder 16 through the conduit 36.
The pressure on the high pressure side before passing through the passage 39 passes through the chamber 102 of the spool 33 through the drilled hole 37 made in the spool 33.
, through the shuttle valve 40 to a chamber 41 which is a pressure chamber at one end of the spool 18 of the main valve 17. On the other hand, the pressure on the low pressure side after passing through the notch 34 of the subur 33 is guided from a drilled hole 42 in the spool 33 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. . As a result, the spool 18 moves until the differential pressure between the pressure chambers 41 and 47 is balanced with the spring 48 in the chamber 47, and the communication between the chamber 49 and the chamber 35 of the main valve 17 is changed from the closed state to the open state. . Also, ripper cylinder 1
The chamber 50 connected to the raising chamber 6 is also connected to the main valve 17.
The relationship with the chamber 51, which is a tank boat, is changed 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 notch groove 52 cut out in the spool 19 changes the state between the chamber 24 and the chamber 53 from closed to open, and the pump pressure is increased by the pilot pipe 5.
4 acts on the piston 56 provided in the spool 12 of the shuttle valve 55, which is held down by the plug 57, so that the spool 12 moves to the left against the spring 58, opening the chambers 60 and 9. The notch 8 that had been opened is closed, and the chambers 59 and 60 are opened through the constriction 61 of the spool 12, and are led to the spring chamber side of the unload valve 6 through the pilot pipe 62 and the throttle 11. 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 check valve 66 is pushed open from the chamber 65 which is the pump boat of the main valve 17 through the piping 64, passes through the constriction 67 of the open spool 18 into the chamber 49, joins the flow rate of the second pump 2 in the chamber 35, and flows into the cylinder. Flow ripper on the bottom side
The return flow from the cylinder rod side after extending the cylinder 16 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 tank boat chamber 51 through the pipe 70 to the tank 111.

Similarly, the spool 19 of the third control valve 5 was placed in the pressed position. In this case, the ripper cylinder 16 can also be driven to the contraction side.

In addition, in the main valve 17, the chamber 35 is
Even when the flow rate of the first pump 1 merges with the flow rate of the second pump 2, if the ripper cylinder 16 is extended, it is on the downstream side with respect to the chamber 32. 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.

In addition, since it uses the differential pressure caused by the flow of oil, the ripper
It is not affected by the load pressure of the 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. 1, then the flow rate from the rising chamber of the ripper cylinder 16 to the chamber 50 can be greater than the flow rate from the chamber 35 to the lowering chamber of the ripper cylinder 16.

In this case, the differential pressure is between chamber 50 (upstream side) and chamber 73 (downstream side).
The high pressure oil in the chamber 50 is determined by the pressure in the through hole 79 and the chamber 8.
0, is led from the boat 4C of the shuttle valve 40 to the chamber 41 via the passage 90, and moves the spool 18 downward in FIG.

The oil of the first pump 1 thus flows into the chamber 35 and into the lowering chamber of the ripper cylinder 16.

Furthermore, even when the engine is stopped and there is no flow rate from the first and second pumps 1゜2, it is necessary to lower the working machine to the ground. For example, if we consider the case where the ripper cylinder 16 is pushed by its own weight, , when the spool 19 of the third control valve 5 is placed in the pull position, the return flow rate of the raising chamber of the ripper cylinder 16 is from the piping 68 through the chamber 50, through the notch 72 of the spool 71, and from the chamber 73 through the piping 74. 3 to the chamber 75 of the control valve 5, passes through the constriction 76 of the spool 19 in the open state, and returns to the tank 111 from the chamber 77, which is a tank boat, through a pipe 78. At the same time, the pressure difference generated before and after the notch 72 of the spool 71 due to the flow leads to the pressure chamber 41 of the spool 18 through the through hole 79 of the high pressure side spool 71, through the chamber 80, the passage 90, and the shuttle valve 40, and is guided to the pressure chamber 41 of the spool 18 on the low pressure side. is spool 7
1 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 chambers 50 and 5
The relationship No. 1 changes from closed to open, and the return flow rate from the raising chamber of the ripper cylinder 16 passes through the constriction 69 of the spool 18 and returns to the tank 111 via the pipe 70 to the tank 111. In this case, since the chamber 51 and the chamber 35 communicate with each other via the suction valve 140, when the ripper cylinder 16 is extended, the chamber 51 communicating with the tank 111 flows into the chamber 35 via the suction valve 140. supply. For this purpose, oil is supplied to the lowering chamber of the ripper cylinder 16. In this case, even if the engine is stopped as described above, the spool 18 of the main valve 17 can be switched by operating the third control valve 5. Emergency braking (when stopped) is possible.

〔Effect of the invention〕

Pressure oil in the lifting chamber of the work equipment cylinder flows under its own weight, generating a differential pressure, and using this differential pressure, the main valve 17 is switched and the pressure oil in the lifting chamber is discharged through the main valve 17 to the tank side. It is safe because the work machine cylinder can be lowered by its own weight when pilot pressure is not generated, such as when the pump that generates pilot pressure breaks down or the engine that drives the pump stops.

[Brief explanation of the drawing]

The drawings are configuration explanatory diagrams showing an example of a hydraulic system for carrying out the method of the present invention, and FIGS. 2 and 3 are explanatory diagrams of the operation of an unload valve.

Claims (1)

[Claims] The pump discharge pressure oil is controlled to be supplied to the lifting chamber of the working machine cylinder by a pilot-operated main valve 17, and when the pilot pressure is not generated, the pressure oil in the lifting chamber of the working machine cylinder is circulated by its own weight. A pressure oil supply control method for a working machine cylinder in which a pressure difference is generated and the main valve 17 is switched using the pressure difference.