JPH01206180A - Flow control valve - Google Patents

Abstract

PURPOSE:To enhance the responsiveness of a flow control valve and to enable sensible flow control by providing a variable orifice in a flow passage, and by providing an orifice valve in a first pilot circuit for the variable orifice. CONSTITUTION:A variable orifice 11 adapted to be moved by a pilot pressure in a first pilot chamber 12 and the force of a spring 13 in a direction in which an input port 14 and an output port 15 are closed, and adapted to be moved by pilot pressures in second and third pilot chambers 16, 17 in a direction in which the input port 14 and the output port 15 are communicated, is provided in a flow passage 10, and an orifice valve 25 is disposed in a first pilot circuit 20 connected to the first pilot chamber 12. With this arrangement, the flow passage may be simplified while the attaching area may be reduced, and it is sufficient to throttle a slight flow rate of fluid, thereby it is possible to enhance the responsiveness, and to control the flow of fluid at a slight value.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a flow control device used in a hydraulic circuit of a construction machine or the like.

[Conventional technology]

Construction machinery, such as power excavators, has an arm pivoted to the vehicle body that can be moved up and down by an arm cylinder, and a boom is pivoted to the arm so that it can be moved up and down by a boom cylinder, and packets are moved up and down by a packet cylinder to the boom. Equipped with a rotatably attached two-arm work machine.

For example, as shown in FIG. 3, the hydraulic circuit of such an arm-operating machine includes an arm valve 2, a boom valve 3, and a packet valve 4 in the discharge path 1a of the pump 1, and the arm cylinder 5, boom cylinder 6 , a hydraulic circuit that supplies pressure oil discharged from the pump 1 to the packet cylinder 7 is known.

In such a hydraulic circuit, when the arm cylinder 5 and boom cylinder 6 are operated simultaneously, the pressure oil of the pump 1 is supplied to the cylinder with a light load. A valve 8 and a check valve 9 are provided in series, and when the arm cylinder 5 and boom cylinder 6 are operated simultaneously, the flow rate restricting valve 8 is controlled and the flow rate flowing to the arm valve 2 is restricted, and the flow rate between the arm cylinder 5 and boom cylinder 6 is controlled. is operated at the same speed regardless of the magnitude of the load, and the check valve 9 prevents backflow from the arm valve 2 side.

[Problem to be solved by the invention]

In such a hydraulic circuit, a flow rate restricting valve 8 and a check valve 9 are provided in the flow path for controlling the flow rate, that is, the inlet side flow path 2a of the arm valve 2.
Since these are installed in series, the flow path is complicated and the mounting area is large, and since a control signal is input to the flow rate restricting valve 8 to control the flow rate flowing through the flow path, not only does the responsiveness deteriorate, The control signal may have a value large enough to control the flow rate restricting valve 8 that controls a large flow rate, and may not be able to control the flow rate minutely.

Therefore, an object of the present invention is to provide a flow rate control device that can solve the above problems.

[Means and effects for solving the problem] The pressure of the second pilot chamber 16 acts in the flow path 10 in the direction of increasing the communication area between the upstream side and the downstream side of the flow path 10, and the pressure of the first pilot chamber 12 increases. A variable throttle 11 is provided which operates in a direction to block the upstream and downstream sides of the flow path 10 by pressure, and which throttles the auxiliary pilot circuit 21 connected to the upstream side of the flow path 10. A check valve 24 is provided to prevent flow from the downstream side to the upstream side of the flow path 10, and its auxiliary pilot circuit 21 is connected to the first pilot circuit 20 connected to the first pilot chamber 12,
The first pilot circuit 20 is connected to the downstream side of the flow path 10 via a controllable throttle valve 25, and the second
Connecting the pilot chamber 16 to the upstream side of the flow path 10,
By controlling the flow rate of the first pilot circuit 20 with the throttle valve 25, the flow rate from the upstream side to the downstream side of the flow path 10 can be controlled.

〔Example〕

As shown in FIG. 1, a variable throttle 11 is provided in the flow path 10, and this variable throttle 11 is directed in a direction that blocks the inlet boat 14 and the outlet port 15 by the pilot pressure of the first pilot chamber 12 and the force of the spring 13. At the same time, the pilot pressure in the second and third pilot chambers 16 and 17
4 and the outlet boat 15, and the second pilot chamber 16 is connected to the flow path 10 by the second pilot circuit 18.
The upstream pressure P1 is supplied, and the third pilot chamber 1
7, the third pilot circuit 19 controls the downstream pressure P2 of the flow path 10.
is supplied to the first pilot chamber 12, the downstream pressure P2 of the flow path 10 is supplied to the first pilot chamber 12 through the first pilot circuit 20, and the upstream pressure P2 of the flow path 10 is supplied through the auxiliary pilot path 21.

The auxiliary pilot path 21 is connected to the upstream side of the flow path 10 via the auxiliary outlet boat 22 of the variable throttle 11, the auxiliary inlet port 23, and the check valve 24, and is connected to the downstream side through the auxiliary pilot circuit 21. In order to prevent the pressure P2 from flowing back to the upstream side, the auxiliary inlet port 23 and the auxiliary outlet port 24 are sometimes slightly communicated and greatly constricted when the inlet port 14 and the outlet port 15 are blocked, and the inlet port 14 and the outlet port 15 are successively communicated with each other, the communication area increases successively.

The first pilot circuit 20 is provided with a throttle valve 25, which is an electromagnetically controllable throttle valve that operates to throttle in proportion to the magnitude of the current value supplied to the solenoid 25a.

Note that the check valve 24 may be provided on the auxiliary pilot circuit 21 side.

Therefore, when the solenoid 25a is not energized, the throttle valve 25 does not throttle, and the communication area is maximized.
The pressure P1 on the upstream side of the flow path 10 is the second pilot circuit 18
It is supplied to the second pilot chamber 16 from the auxiliary pilot circuit 21 and the first pilot chamber 12 from the auxiliary pilot circuit 21 and the first pilot circuit 20. However, as mentioned above, since the communication area of the throttle valve 25 is the largest, Since the pressure P1 flows downstream of the flow path 10, the variable throttle valve 11 is connected to the inlet boat 14.
The outlet boat 15 moves to a position where the communication area is maximized, and a large amount of pressure oil flows from the upstream side to the downstream side of the flow path 10.

At the same time, the auxiliary inlet port 23 and the auxiliary outlet boat 22
The communication area increases, and the upstream pressure P1 flowing into the first pilot circuit 20 increases.

When the solenoid 25a is energized and the throttle valve 25 is throttled, the communication area decreases, the pressure in the first pilot circuit 20 increases, and the pressure in the first pilot chamber 12 becomes high, which causes the variable throttle 11 to close at the inlet. Boat 14 and exit boat 1
5, the pressure oil flowing from the upstream side to the downstream side of the flow path 10 is reduced.

At the same time, the auxiliary entrance boat 23 and the auxiliary exit boat 22
As a result, the upstream pressure P1 flowing into the first pilot circuit 20 decreases.

Further, since the check valve 24 is provided in the auxiliary pilot circuit 21, the downstream pressure P2 is equal to the upstream pressure P.

Even if the pressure becomes higher, the downstream pressure P2 does not act on the upstream side via the auxiliary pilot circuit 21, and the variable throttle 11 is at a position where the pressure in the first pilot chamber 12 and the spring 13 block the inlet port 14 and the outlet boat 15. Because the water moves from the downstream side to the upstream side, there is no backflow.

FIG. 2 is a sectional view specifically showing the aforementioned flow rate control device, and the details thereof will be explained below.

The valve body 30 has an inlet hole 31, a large diameter hole 32, and a spool hole 33.
, the through holes 34 are continuously drilled on the same center, and the inlet holes 31
is communicated with the upstream port 35, an outlet hole 36 is bored in the large diameter hole 32, a poppet 37 is inserted, and the conical surface 37a of the poppet 37 is pressed against the seat seat 38 to connect the artificial hole 31 and the large diameter hole. 32 and forms a first chamber 39.

A small diameter hole 40, a large diameter hole 41, and a shaft hole 42 are continuously drilled in the axial center of the poppet 37, and a spool 43 is inserted into the shaft hole 42, and the spool hole 33 is inserted into the spool hole 33 with the flange 44 of this spool 43. The oil passage 45, the constricted part 46, and the notch 47 are formed in the spool 43, and the needle valve 48 is pressed against the small diameter hole 40 by a spring 49 to separate the small diameter hole 40 and the large diameter hole 44a. A check valve that shuts off the diameter hole 41 is used, and a spool 50 is fitted into the spool hole 33 to form a second chamber 51.
is moved downward by a spring 52 and comes into contact with the proportional solenoid 53. Furthermore, a drilled hole 54 is bored in the spool 50 to communicate the second chamber 51 and the through hole 34, and a hole 54 is formed in the valve body 30 to connect the second chamber 51 and the outlet. A passage 55 communicating with the hole 36 is perforated.

In the above configuration, the inlet hole 31 and the outlet hole 3B constitute the flow path 10, the poppet 37 serves as the variable throttle 11, and the spool 50 and the proportional solenoid 53 constitute the throttle valve 25.
At the same time, the first chamber 39 becomes the first pilot chamber 12, the conical surface 37a of the poppet 37 becomes the second pilot chamber 16, and each type of hole bored in the axis of the poppet 37, the shaft hole 42, and the spool 43 constitutes the auxiliary pilot circuit 21.

Next, the operation will be explained.

When the proportional solenoid 53 is not energized.

Since the spool 50 is moved downward in the figure by the spring 52,
The communication area A3 between the second chamber 51 and the passage 55 determined by the spool 50 is maximized, and the first chamber 39 passes through the notch 44a1, the second chamber 51, the passage 55, and the outlet hole 36.
It will be communicated to.

For this reason, the pressure in the first chamber 39 becomes low and the poppet 3
7 is moved downward by the upstream pressure P acting on the conical surface 37a, the conical surface 37a is separated from the seat seat 38, and the pressure oil in the inlet hole 31 flows out to the outlet hole 36.

At this time, a part of the pressure oil in the inlet hole 31 pushes down the needle valve 48, and the small diameter hole 40, the large diameter hole 41, the notch 47, the constricted part 46,
Oil passage 45, first chamber 39, notch 44a1, second chamber 51
, flows from the passage 55 to the outlet hole 36, but since the poppet 37 moves downward and the opening area of the notch 47 and the large diameter hole 41 becomes large, the flow rate becomes maximum.

When the proportional solenoid 53 is energized.

The spool 50 is moved by the spring 52 by the thrust of the proportional solenoid 53.
, and the communication area A3 decreases.

For this reason, the pressure oil in the first chamber 39 becomes difficult to flow to the outlet hole 3B, the pressure P3 in the first chamber 39 increases, and the downward stroke of the poppet 37 is restricted. In other words, the second
The communication between the chamber 51 and the passage 55 is narrowed by the spool 50 and the first
Since the pressure P3 in the chamber 39 increases, the poppet 37 is pushed down due to the balance between the upstream pressure P, x pressure receiving area A, and the first chamber pressure pj x pressure receiving area A2.

At this time, the opening areas of the notch 47 and the large diameter hole 41 are reduced.

As a result, the communication area between the inlet hole 31 and the outlet hole 36 is determined, and the flow rate flowing from the inlet hole 31 to the outlet hole 36 becomes a value proportional to the amount of current supplied to the proportional solenoid 53.

In this state, the poppet 37 maintains the pressure P of the inlet hole 31,
When pressed down, the opening area of the notch 47 and the large diameter hole 41 increases, the flow rate flowing into the first chamber 39 increases, and the first chamber 3
Since the pressure P3 inside the proportional solenoid 53 increases and the poppet 37 is pushed down, the communication area between the inlet hole 31 and the outlet hole 36 becomes a value commensurate with the amount of current supplied to the proportional solenoid 53.

Furthermore, when the current applied to the proportional solenoid 53 increases, the spool 50 further strokes upward and further narrows the communication area A3, so that the pressure inside the first chamber 39 is P
3 becomes higher, the poppet 37 is further pushed up, and the communication area between the inlet hole 31 and the outlet hole 36 is further reduced.

In this way, the flow rate flowing into the outlet hole 36 can be controlled depending on the magnitude of the current to the proportional solenoid 53.

Furthermore, when the pressure P2 in the outlet hole 36 is higher than the pressure P1 in the inlet hole 31, the pressure oil in the outlet hole 36 flows through the passage 55 and into the second chamber 5.
1. Notch 44a1, first chamber 39, oil passage 45, constriction 4
6. Inlet hole 3 from notch 47, large diameter hole 41, and small diameter hole 40
1, but since the flow from the large diameter hole 41 to the small diameter hole 40 is blocked by the needle valve 48, the aforementioned flow does not occur, and moreover, the pressure P2 of the outlet hole 36 acts on the first chamber 39. Since the poppet 37 is pushed up and the conical surface 37a is brought into pressure contact with the seat seat 38, the pressure oil in the outlet hole 36 does not flow back into the inlet hole 31.

Further, when the pressure difference between the pressure P of the inlet hole 31 and the pressure P2 of the outlet hole 36 increases, the flow rate flowing into the first chamber 39 increases,
The flow rate flowing from the first chamber 39 to the outlet hole 36 is throttled by the spool 50, but if the flow rate flowing to the second chamber 51 increases, the force of the flow (jet) causes a greater fluid force to act on the spool 50. The fluid force moves the spool 50 upward and reduces the communication area A3, so the pressure P3 in the first chamber 39 increases and the poppet 37
By pushing up the flow rate, the communication area between the inlet hole 31 and the outlet hole 36 can be reduced, and the flow rate of the outlet hole 36 can be maintained constant.

That is, it has a pressure compensation function that keeps the flow rate of the outlet hole 36 constant even if the differential pressure between the inlet hole 31 and the outlet hole 36 changes.

〔Effect of the invention〕

Since it is only necessary to provide the variable throttle valve 11 in the flow path 10, the flow path is simple and the installation area can be reduced.

Furthermore, since the throttle valve 25 is provided in the first pilot circuit 20, the received flow can be throttled by the throttle valve 25, which not only improves responsiveness, but also allows the control signal for the throttle valve 25 to be set to a small value. This allows for minute flow control.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing an embodiment of the present invention, FIG. 2 is a sectional view of a specific example, and FIG. 3 is a conventional circuit diagram. 10 is a flow path, 11 is a variable throttle, 12 is a first pilot chamber, 16 is a second pilot chamber, 20 is a first pilot circuit, 21 is an auxiliary pilot circuit, 24 is a check valve, and 25 is a throttle valve. Figure 2

Claims (1)

[Claims] The pressure in the second pilot chamber 16 acts to increase the communication area between the upstream and downstream sides of the flow path 10 , and the pressure in the first pilot chamber 12 acts to increase the communication area between the upstream and downstream sides of the flow path 10 . A variable throttle 11 is provided that operates in a direction to block the flow and throttles an auxiliary pilot circuit 21 connected to the upstream side of the flow path 10, and the auxiliary pilot circuit 21 is operated from the downstream side of the flow path 10 to the upstream side. A check valve 24 is provided to prevent the flow of water, and the auxiliary pilot circuit 21 thereof is connected to a first pilot circuit 20 connected to the first pilot chamber 12, and a throttle valve 25 capable of controlling the first pilot circuit 20 is provided. A flow rate control device characterized in that the second pilot chamber 16 is connected to the downstream side of the flow path 10 via the flow path 10, and the second pilot chamber 16 is connected to the upstream side of the flow path 10.