JPH0126884Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a fluid pressure actuator with a damper function.

[Prior Art] In a fluid pressure actuator in which fluid chambers are defined at both ends by a piston fitted in a cylinder, when pressurized fluid is supplied to one fluid chamber, the speed of the piston gradually increases, and at the end of the stroke, the speed of the piston increases. The piston hits the end wall of the fluid chamber hard and stops.
In devices operated by fluid pressure actuators, such as automatic transmissions in automobiles, such impacts impact the operating parts of the synchronized mesh mechanism, producing abnormal noise and affecting the durability of the synchronized mesh mechanism. .

[Problems to be solved by the invention] The purpose of the invention is to solve the above-mentioned problems.
To provide a fluid pressure actuator in which the amount of fluid discharged is automatically throttled near the end of a piston's stroke, and the piston is gently stopped at a fixed position.

[Means for Solving the Problem] In order to achieve the above object, the configuration of the present invention includes an outlet port on the peripheral wall of the fluid chamber of the cylinder partitioned by the piston, and an end wall of the fluid chamber that allows flow into the fluid chamber. Each of the fluid chambers has an inlet port equipped with a check valve, and a passage opening in the end wall of the fluid chamber communicates with a buffer chamber whose volume increases against the force of a spring.

[Operation] When the piston is pushed by the pressurized fluid supplied to one end chamber, when the outlet port of the other end chamber is closed by the peripheral wall of the piston, the fluid in the end chamber is confined, and the speed of the piston is reduced. becomes lower.

The fluid in the end chamber enters the damping chamber of the damper 27 through the passage 24 and causes the damping piston to retract against the force of the spring. As a result, the piston slowly comes into contact with the end wall and stops at a predetermined position.

Whether the fluid is compressible or incompressible, a gentle stopping motion of the piston without impact can be obtained.

[Embodiment of the invention] The invention will be described based on an example of a three-position actuator that operates a gear shift lever in an automatic transmission of an automobile. As shown in FIG. 1, a large diameter cylinder 3 and a small diameter cylinder 4 are concentrically constructed in the main body 2, a hollow large diameter piston 6 is arranged in the large diameter cylinder 3, and a large diameter stepped piston 5 is arranged in the small diameter cylinder 4. The small diameter portion 5a of the stepped piston 5 is fitted into the cylindrical portion 6a of the large diameter piston 6.

A fluid chamber 40 is defined in the large diameter cylinder 3 by a large diameter piston 6 fitted with a seal ring 8, and a stepped piston 5 similarly fitted with a seal ring 9.
A fluid chamber 41 is defined in the small diameter cylinder 4 by this. Piston rod 7 connected to stepped piston 5
protrudes outward from the end wall of the main body 2 and is connected to the gear shift lever. A seal ring 10 attached to the peripheral wall of the piston rod 7 provides a seal at the fitting portion with the main body 2.

Note that the chambers 12 of the stepped portions 11 of the large diameter cylinder 3 and the small diameter cylinder 4 are connected to a fluid tank (at atmospheric pressure) through a passage 14.

According to the present invention, an outlet port 15 is provided on the end circumferential wall of the fluid chamber 40, and an inlet port 16 is provided on the end wall with a check valve 30 that allows pressurized fluid to flow into the fluid chamber 40. Similarly, fluid chamber 4
1 is also provided with an outlet port 13 on the end circumferential wall and an inlet port 17 with a check valve 31 on the end wall. Passage 2 opening in the end wall of the fluid chamber 40
4 and the passage 25 opening in the end wall of the fluid chamber 41 are connected to buffer chambers at both ends of the buffer 27, respectively.

The shock absorber 27 has a pair of pistons 35 equipped with a seal ring 37 fitted inside a cylinder 34, and connects the intermediate chamber to a fluid tank or the atmosphere through a passage 26. A spring 36 is inserted between the pair of pistons 35. It is said that the configuration is such that the A projecting wall 39 as a stopper is provided in the intermediate chamber of the cylinder 34,
It is configured to prevent the piston 35 from moving too far. As mentioned above, each piston 35 and cylinder 3
Passages 24, 25 are connected to the chambers between the end walls of 4, respectively.

Next, the operation of the device of the present invention will be explained. When pressurized fluid is supplied to the fluid chambers 40 and 41 from ports 16 and 15 and ports 17 and 13, respectively, the large diameter piston 6 is moved to the stepped portion 11 between the small diameter cylinder 4 and the large diameter cylinder 3 due to the fluid pressure in the fluid chamber 40. collide,
In addition, the stepped piston 5 is moved by the fluid pressure in the fluid chamber 41.
collides with the end of the large diameter piston 6, resulting in the neutral position shown in FIG.

Now, when the fluid chamber 40 is connected to the fluid tank and pressurized fluid is supplied to the fluid chamber 41, the stepped piston 5
As a result, the large diameter piston 6 is pushed to the left, and its speed gradually increases. When the circumferential surface of the large-diameter piston 6 closes the outlet port 15, the pressurized fluid in the fluid chamber 40 passes through the passage 24 and enters the buffer chamber on the left side of the buffer 27, causing the piston 35 to move to the right against the spring 36. push. Due to the drag force of the spring 36 and the fluid resistance of the passage 24,
Near the end of the stroke, the outflow speed of the fluid in the fluid chamber 40 is suppressed, the speed of the large diameter piston 6 is reduced as shown by line e in FIG. 2, and the impact at the end of the stroke is alleviated.

When the large diameter piston 6 is moved back from the state where it is in contact with the end wall of the fluid chamber 40, that is, when it is moved to the right, pressurized fluid is supplied from the inlet port 16, and the inlet port 16 Since they are provided on the end wall, the large diameter piston 6 and the stepped piston 5 are quickly pushed to the right, the large diameter piston 6 hits the stepped portion 11, and is returned to the neutral position shown in FIG.

Next, when the outlet port 13 is connected to the fluid tank, the stepped piston 5 is moved by the fluid pressure in the fluid chamber 40.
When only the shock absorber 27 is pushed to the right and the outlet port 13 is closed by the circumferential surface of the large diameter portion 5b, the fluid in the fluid chamber 41 enters the buffer chamber on the right side of the shock absorber 27 from the passage 25, causing the piston 35 to engage the spring 36. Move it to the left against resistance. Due to the drag force of the spring 36 and the fluid resistance of the passage 25, the outflow speed of the fluid in the fluid chamber 41 is suppressed near the end of the stroke, and the speed of the stepped piston 5 is reduced as shown by line e in FIG. The impact at the end of the stroke is reduced.

In a conventional hydraulic actuator, the piston moves at a constant speed until it hits the end wall of the cylinder, as shown by line bc in FIG. This impact applied to the synchronized mesh mechanism through the gear shift lever operated by the piston rod.

[Effects of the invention] As described above, the present invention has an outlet port on the circumferential wall of the fluid chamber of the cylinder partitioned by the piston, and an inlet port equipped with a check valve on the end wall of the fluid chamber that allows flow into the fluid chamber. A passage opening in the end wall of the fluid chamber is connected to a buffer chamber whose volume increases against the force of the spring, and the piston speed is reduced at the end of the stroke.
This eliminates the problem that occurs in conventional fluid pressure actuators where an impact is applied to the meshing portion of gears of a fluid pressure operated device, such as a synchronized mesh mechanism, at the end of the stroke. Therefore, generation of abnormal noise is prevented, and wear of the operating portion due to impact is reduced.

Since ports are simply arranged in the cylinder as described above, processing is simple and costs are reduced.

In the fluid pressure actuator of the present invention, even when the piston closes the outlet port when the piston moves forward, the fluid is not trapped in the fluid chamber.
Since it flows into the buffer chamber of the shock absorber through the passage and moves the buffer piston backward against the force of the spring, the piston always stops at a position where it abuts against the end wall, and the stopping position of the piston is constant.

[Brief explanation of the drawing]

FIG. 1 is a side sectional view of a fluid pressure actuator according to the present invention, and FIG. 2 is an operating characteristic diagram comparing the fluid pressure actuator according to the present invention with a conventional one. 3...Large diameter cylinder, 4...Small diameter cylinder, 5
...Stepped piston, 6...Large diameter piston, 7...
Piston rod, 13, 15...Exit port, 1
6, 17...Inlet port, 27...Buffer, 3
0, 31...Check valve, 34...Cylinder, 35...
...Piston, 36...Spring, 40, 41...Fluid chamber.

Claims (1)

[Scope of utility model registration request] An outlet port is provided on the circumferential wall of the fluid chamber of the cylinder partitioned by the piston, an inlet port is provided on the end wall of the fluid chamber and is equipped with a check valve that allows flow into the fluid chamber, and a passage opens in the end wall of the fluid chamber. A fluid pressure actuator characterized in that the fluid pressure actuator is connected to a buffer chamber whose volume increases against the force of a spring.