JPH0313441B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a proportional valve, and more particularly:
The present invention relates to a proportional valve for controlling a fluid path from a pressure source to at least one working port of a hydraulic device.

[Conventional technology]

Conventionally, several proportional valves for controlling fluid paths are known. These valves are used to control the volume and direction of fluid flow. The piston device is biased by a spring to resiliently hold the piston device movable within the bore of the housing in a central position. The piston device is part 2
When a control pressure is applied to one of the two end faces, it moves from the central position against the spring force. Both end surfaces of the piston device receive the above control pressure directly, or
Alternatively, the control pressure may be received via a pilot valve having a control piston operated by a proportional solenoid. Thereby, the piston arrangement of the proportional valve is expected to move in proportion to the electrical input signal.

However, the control pressure required to produce a predetermined stroke differs depending on the direction of movement of the piston device, resulting in the disadvantage that hysteresis exists in the operation of the valve.

[Problem to be solved by the invention]

The present invention attempts to reduce the hysteresis in the proportional valve as described above.

[Means to solve the problem]

According to the invention, a piston device slidably mounted in a bore of a housing and spring-loaded into a central position selectively applies a control pressure to one of its two end faces. In a proportional valve for controlling a fluid path from a pressure source to at least one actuating port, the piston device has a piston device movable from said central position by a compressor for movement in a first sliding direction thereof. elastically in said central position by a single spring acting as a spring and also acting as a compression spring by means of a tension rod having one end connected to the piston device for movement in the opposite second sliding direction. and the tension rod is provided with two stop members each having a hemispherical convex surface, respectively disposed at its free end and in the vicinity of said one end connected to the piston arrangement. , and the spring is clamped by two spring holders forming spring retaining means which are slidably mounted on the tension rod between the stops of the tension rod, the spring holders being pressed against the corresponding stops. When fitted, a proportional valve is obtained which is tiltable relative to the axis of the tension rod.

[Effect]

According to the invention, by the use of a single spring to elastically hold the piston arrangement in a central position,
In addition to the symmetrical elastic forces with respect to the two directions of movement of the piston device from the central position, the two spring holders that sandwich the single spring are tiltable relative to the axis of the tension rod. Therefore, the influence of the component of the spring force perpendicular to the moving direction of the piston device (ie, lateral spring force) on the piston device is reduced.

In one embodiment of the invention, the lateral forces acting on the piston arrangement may be further reduced by terminating the spring with at least two close-contact end turns at each end thereof. can.

〔Example〕

Embodiments of the present invention will be described below based on the accompanying drawings.

The proportional valve of the present invention has solenoids 11 and 12.
It consists of a pilot valve 10 with a piston arrangement 15 and a main valve 14 with a single spring 16.

In the neutral position shown, the piston device 15 is held in a central position by a spring 16. For example, when solenoid 11 is energized, control piston 18 of pilot valve 10
moves to the right side of the drawing. Then, fluid flows from the fluid source P through the pilot valve 10 to the control pressure chamber 19, the piston device 15 moves in proportion to the electrical input signal, the fluid passage with the throttle cross section having a gradual increase characteristic opens, and the fluid flows into the control pressure chamber 19. Flows from source P through port A to the load. On the other hand, the port B is connected to the port T which communicates with the reservoir through the throttle section of the piston device 15.

When the solenoid 12 is energized, the chamber 20
is subjected to a corresponding control pressure and the fluid passage is reversed. A single spring 1 acting on the piston device 15
6 is subjected to compressive stress regardless of the direction of movement of the piston device 15. The spring 16 is pressed between two spring holders 21 and 22 which form a spring holding means. These holders 21 and 22 are connected to the piston device 1
It is slidably attached to a tension rod 23 which has one end threaded into a hole formed in 5. In addition, these spring holders 21 and 22
are in contact with stop members 25 and 26 having hemispherical convex surfaces attached to the rod 23 so as to be tiltable relative to the axis of the rod 23. The stop member 25 is
The adjusting nut 27 is arranged so that its axial position can be adjusted, so that the degree of compression of the spring 16 can be changed or readjusted. Spring holders 21 and 22 are tension rods 2
3, so it can be freely tilted within predetermined limits. Therefore, in either of the two sliding directions of the piston device 15 which applies a compressive force to the spring, the piston device 15 can be moved from the spring 16 to the piston device 15.
The force applied to the axis acts almost exclusively in the axial direction. In this way, the tiltability of spring 16 acts to reduce the hysteresis of the valve. This equalizes the response of the piston device 15 in each of the two sliding directions. The influence of bending moments that increase the friction experienced by the piston device can be avoided. Each end of the spring 16 is in close contact with at least two
If the winding ends with the end winding, the piston device 1
The lateral force applied to 5 is further reduced.

The spring holding means arranged on the rod 23 is provided with a spacer sleeve 28 between the spring holders 21 and 22, which limits the axial movement of the spring in both directions of the piston device 15, so that the spring hysteresis is prevented. This also reduces the hysteresis of the valve.

〔Effect of the invention〕

Conventional valve systems that use two springs to elastically hold the piston system in a central position exhibit a stroke hysteresis of 6-8%, but the present invention reduces the hysteresis to approximately 3-8%.
It can be reduced to 4%.

[Brief explanation of drawings]

The figure shows a cross section of a proportional valve according to the invention. 10... Pilot valve, 11, 12... Solenoid, 15... Piston device, 16... Spring, 18... Control piston, 19... Control pressure chamber, 20... Chamber, 21, 22... Spring holder, 23...Tension rod, 25, 26...Stop member, 27...Adjustment nut, P...Fluid source.

Claims (1)

Claims: 1. A piston device slidably mounted within a bore of a housing and spring-forced to assume a central position, the piston device selectively applying a control pressure to one of its two end faces. In a proportional valve for controlling a fluid path from a pressure source to at least one actuating port, the piston device 15 has a piston device movable from said central position, said piston device 15 having a first sliding direction movement thereof; by means of a single spring 16 which acts as a compression spring for movement in the opposite second sliding direction and also acts as a compression spring by means of a tension rod 23 having one end connected to said piston arrangement. , elastically held in said central position, said tension rod 23 having a hemispherical convex portion disposed at each of its free end and in the vicinity of said one end connected to said piston arrangement. Two stop members 25, 26 are provided, said spring 16 forming a spring retaining means slidably mounted on said tension rod 23 between said stop members 25, 26 of said tension rod 23. Proportional valve, characterized in that it is sandwiched by two spring holders 21, 22, which spring holders are tiltable relative to the axis of the tension rod 23 when abutting the corresponding stop member. 2. A proportional valve as claimed in claim 1, characterized in that the spring holding means comprises a spacer sleeve 28 arranged on the tension rod between the spring holders. 3. A proportional valve as claimed in claim 1 or claim 2, characterized in that each end of the spring terminates in at least two tightly wound end turns.