JPH01206182A - flow control valve - 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 flow control valve 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. 2, 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 installation area is large, and the flow rate flowing through the flow path is controlled by inputting a control signal to the flow rate restricting valve 8, which not only deteriorates responsiveness. In some cases, the control signal has a value large enough to control the flow rate restricting valve 8 that controls a large flow rate, making it impossible to control the flow rate minutely.

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

[Means and actions for solving the problem] In the valve body 30,
A poppet 37 that connects the inlet hole 31 and the outlet hole 36 and a first chamber 39 that moves the poppet 37 in a direction that blocks the inlet hole 31 and the outlet hole 36 are provided. A throttle valve that increases or decreases the communication area of the inlet hole 3 according to an external signal is provided at the axis of the poppet 37.
1 and the first chamber 39 and whose communication area increases or decreases depending on the stroke of the poppet 37, and a needle valve 48 and a spring 49 are provided in this communication path to connect the first chamber 39 to the first chamber 39. As a check valve that prevents flow from the inlet hole 31 side, a poppet 37 provided in the valve body 30 is stroked by controlling a throttle valve provided in the valve body 30 to prevent flow from the inlet hole 31 to the outlet hole 36. This allows the flow rate to be controlled.

〔Example〕

The valve body 30 has an inlet hole 31, a large diameter hole 32, and a spool hole 33.
, through-holes 34 are continuously drilled on the same center, and the entrance hole 31 is
is connected to 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 inlet 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 38 is inserted into the spool hole 38 with the flange 44 of this spool 43. The oil passage 45, the constriction 46, and the notch 47 are formed in the spool 43 to form a communication passage that communicates the first chamber 39 and the inlet hole 31, and the small diameter A needle valve 48 is pressed against the hole 40 by a spring 49 to form a check valve that shuts off the small diameter hole 40 and the large diameter hole 41, and a spool 50 is fitted into the spool hole 33 to form a second chamber 51. The spool 50 is moved downward by the spring 52 and comes into contact with the proportional solenoid 53. Furthermore, a drilled hole 54 is bored in the spool 50 that communicates the second chamber 51 with the through hole 34, and a second
A passage 55 communicating the chamber 51 and the outlet hole 36 is perforated.

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 44a, the second chamber 51, and the passage 55 to 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 P1 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 moves upward against 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 up due to the balance between the upstream pressure P1×pressure receiving area A and the first chamber pressure pl×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 up, the communication area between the inlet hole 31 and the outlet hole 36 becomes a value commensurate with the amount of current applied 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 when the flow rate flowing into the second chamber 51 increases, a larger fluid force acts on the spool 50 due to the force (jet) of the flow. , due to this fluid force, the spool 5
0 is moved upward to reduce the communication area A3, the pressure P3 in the first chamber 39 increases, pushing up the poppet 37 and reducing the communication area between the inlet hole 31 and the outlet hole 36, thereby reducing the communication area A3. can maintain a constant flow rate.

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.

Although the communication area between the second chamber 51 and the passage 55 is controlled by stroking the spool 50 with the proportional solenoid 53, the spool 50 may be stroked using pilot pressure.

In other words, a throttle valve that increases or decreases the communication area between the first chamber 39 and the outlet hole 36 based on an external signal may be provided.

〔Effect of the invention〕

A poppet 37 and a throttle valve are provided in the valve body 30, and the throttle valve is controlled by an external signal to allow the flow from the inlet hole 31 to the outlet hole 36.
Since the inlet hole 3L can be connected to the upstream side of the flow path and the outlet hole 36 can be connected to the downstream side of the flow path, the flow path can be simplified and the installation area can be reduced.

In addition, since the flow rate of the outlet hole 36 is controlled by controlling the small amount of flow that flows from the communication hole of the poppet 37 to the outlet hole 36 via the first chamber 39 with a throttle valve, responsiveness is improved and the small external It can be controlled by signals and the flow rate can be minutely controlled.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an embodiment of the present invention, and FIG. 2 is a conventional circuit diagram. 30 is a valve body, 31 is an inlet hole, 36 is an outlet hole, 37 is a poppet, 39 is a first chamber, and 48 is another poppet. Applicant Komatsu Manufacturing Co., Ltd. Representative Patent Attorney Masaaki Yonehara

Claims (1)

[Claims] The valve body 30 includes a poppet 37 that disconnects the inlet hole 31 and the outlet hole 36, and a poppet 37 that connects the inlet hole 31 and the outlet hole 3.
A first chamber 39 that moves in a direction to block the opening of the poppet 37 is provided, and a throttle valve that increases or decreases the communication area between the first chamber 39 and the outlet hole 36 according to an external signal is provided at the axis of the poppet 37. A communication path is formed which communicates the hole 31 with the first chamber 39 and whose communication area increases or decreases depending on the stroke of the poppet 37, and another poppet 48 and a spring 49 are provided in the communication path. Entrance hole 31 from chamber 39
A flow control valve characterized in that it is a check valve that prevents flow to the side.