JP2764861B2 - Multi-stage stroke cylinder - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fluid pressure cylinder whose stroke can be obtained in multiple stages.

[0002]

2. Description of the Related Art In a diesel engine, the degree of opening of an intake throttle valve is controlled in a stepwise manner, air is supplied in accordance with the load of the engine, and the engine is operated in an optimal state.
In order to achieve low fuel consumption and low noise, a cylinder using high-pressure air is suitable as an actuator that operates the intake throttle valve.However, a conventional multi-stage cylinder has a complicated structure and a long cylinder shaft. It is difficult to install in a limited space in an engine room. In addition, although a plurality of small cylinders can be used to control the valve opening in multiple stages by a link mechanism, this also has a drawback in that it does not have a compact configuration and increases the cost.

A multi-step stroke which solves such a problem is provided in Japanese Utility Model Laid-Open No. 3-219103.

[0004] This conventional structure will be described with reference to FIG. 1 is a cylinder and 2 is an end cap tightly fitted to the open end of the cylinder 1. At one end in the cylinder 1, a first stopper 1a is formed by a step portion having a surface perpendicular to the axis of the cylinder.

[0005] Reference numeral 3 denotes a sleeve which is slidably fitted in the cylinder 1 in the axial direction and strokes in a range in which it comes into contact with the first stopper 1a. A first piston 4 is fixedly mounted on one end of the sleeve 3 on the side opposite to the first stopper 1a, and a second piston 5 to be described later abuts on the other end.
A stopper 3a is formed. The first piston 4 has a projection 4a of a required length projecting toward the other end of the sleeve 3 at the center thereof.

Further, in the sleeve 3, the second piston 5 comes into contact with the projection 4a of the first piston 4 so that the first piston
An opposing gap 9 is formed between the piston 4 and the piston 4. The gap 9 is slidably inserted from this position in a stroke in contact with the second stopper 3a. The second piston 5 is constantly urged by a spring 6 in a direction in which it comes into contact with the projection 4a of the first piston 4. One end of an operating shaft 7 projecting out of the cylinder 1 is connected to the second piston 5.

The cylinder 1 has a first piston 4 and a second piston
A first port 8 for supplying and discharging air pressure to a gap 9 facing the piston 5 through a passage hole 10 formed in the sleeve 3, and a supply and discharge of air pressure to a gap 12 between the first piston 4 and the end cap 2. A second port 11 is provided. In addition, 1
Reference numeral 3 denotes an air vent hole.

In the operation of the above structure, in the original position, no air pressure is supplied from either the first port 8 or the second port 11, and the sleeve 3 is pressed by the compression spring 6 as shown in FIG. The second piston 5 is in a state of being located at the left end in FIG. 2 by the pressing force transmitted to the first piston 4 when the second piston 5 comes into contact with the projection 4a.

In this state, the air pressure from the first port 8 becomes the first pressure.
When supplied to the opposing gap 9 between the piston 4 and the second piston 5, the first piston 4 is pressed to the left,
Press to the right. As a result, the sleeve 3 maintains the original position, and the second piston 5 compresses the spring 6 and moves rightward until it contacts the second stopper 3a formed at the other end of the sleeve 3. The stroke of the second piston 5 alone is a first-stage stroke S1.

Next, when air pressure is supplied only from the second port 11 to the gap 12 between the first piston 4 and the end cap 2, the second piston 5 is brought into contact with the projection 4 a of the first piston 4. To move the sleeve 3 rightward until it comes into contact with the first stopper 1a provided on the cylinder 1. The rightward movement stroke of the sleeve 3 is the first stage stroke S1.
The second stage stroke S2 is larger.

Further, when air pressure is supplied from the first port 8 in this state, the first-stage stroke S1 of the second piston 5 is added to the second-stage stroke S2, and the third-stage stroke S3 of the maximum stroke is obtained. Can be

[0012]

In the above conventional structure,
When the sleeve 6 and the second piston 5 are returned by the spring 6 from the advancing end of the third stroke S3, which is a full stroke, to the original position of the retreating end by air, the second
The operating shaft 7 protruding from the piston 5 is the first piston 4
Contact the first piston 4 and the sleeve 3
To push. For this reason, the surface pressure acting on the protrusion 4a of the first piston 4 is large, the response is poor, and there is a problem in the early retreating operation to return to the original position. In addition, there has been a problem that the cylinder bore is made smaller and smaller due to restrictions such as a grounding space.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a multi-stage stroke cylinder capable of reducing the surface pressure when returning to the original position to speed up the response and enabling downsizing.

[0014]

SUMMARY OF THE INVENTION To achieve the above object, the present invention comprises a sleeve which is slidably inserted in a cylinder at a constant stroke in an axial direction, and one end in the sleeve. The fixed first piston is in contact with the first piston with a distance between the first piston and the first piston, and slides in the sleeve with a constant stroke from the contact position to a forward end stopper surface provided at the other end of the sleeve. A second piston; and a spring for urging the second piston in a direction of constantly contacting the first piston. One end of an operating shaft projecting outside the cylinder is connected to the second piston, and the second piston is connected to the second piston. Multistage stroke cylinder provided with a first port for supplying and discharging pressure between opposed surfaces of a first piston and a second piston, and a second port for supplying and discharging pressure between the first piston and an inner end surface of the cylinder In the cylinder, a first stopper surface that regulates a retreating end of the sleeve and a second stopper surface that regulates an advancing end are provided to face the first stopper surface, and the sleeve has the other end moving forward. A retreating end stopper surface facing the end stopper surface is formed, and the second piston is provided with a flange portion abutting on the advancing end stopper surface and the retreating end stopper surface.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. In FIG. 1, reference numeral 20a denotes a first housing, and 20b denotes a second housing coupled to the first housing 20a.
20b forms a cylinder.

A sleeve 3 is inserted into the first housing 20a so as to be slidable in the axial direction.
Is constantly pressed and urged in the retreating direction of one end of the first housing 20a. A first piston 4 is fixed to one end of the sleeve 3 by a circlip 23.
The first piston 4 has a projection 4a of a required length projecting toward the other end of the sleeve 3 at the center thereof.

Further, a second piston 5 is slidably fitted in the sleeve 3. This second piston 5
The operating shaft 7 protruding outside the second housing 20b (FIG. 1)
Is connected to one end of a valve stem of the EGR. The second piston 5 is constantly pressed and urged in the direction of the first piston 4 by a spring 6a, and one end of the operating shaft 7 comes into contact with the projection 4a of the first piston 4 so as to be opposed to the first piston 4. 9 is formed.

The first housing 20a has a first port 8 for supplying and discharging air to a gap 9 between the first piston 4 and the second piston 5 through a passage hole 10 formed in the sleeve 3, A second port 11 for supplying and discharging air is provided in a gap 12 between the piston 4 and an end surface of the first housing 20a. Reference numeral 13 denotes an air vent hole opened in the second housing 20b.

A first stopper surface 21a for regulating the retreating end of the sleeve 3 is provided in the first housing 20a, and the first stopper surface 21a is provided in the second housing 20b.
And a second stopper surface 21b that regulates the forward end opposite thereto. The first stopper surface 21a and the second stopper surface 21b are formed in the form of a step at a plane perpendicular to the axis of the first housing 20a and the second housing 20b.

The sleeve 3 has a retreat end stopper surface 22a for regulating the retreat end of the second piston 5, and an advancing end stopper surface 22b for regulating an advancing end opposed to the retreat end stopper surface 22a. The second piston 5 is provided with a flange portion 5a that comes into contact with the backward end stopper surface 22a and the forward end stopper surface 22b. The retreat end stopper surface 22a and the forward end stopper surface 22b
This is also due to the form of a step portion on a plane perpendicular to the axis of the first housing 20a and the housing 3.

Next, the operation of the present invention will be described. In the original position, no air is supplied from either the first port 8 or the second port 11, and the sleeve 3 is formed by the spring 6b and the spring 6a pressing the second piston 5, as shown in FIG. A state in which the flange portion 5s of the second piston 5 is in contact with the retreat end stopper surface 22a, and the operating shaft 7 is in contact with the protrusion 4a of the first piston 4 and is located at the upper end (retreat end) in FIG. It is.

In this state, when air is supplied from the first port 8 to the opposing gap 9 between the first piston 4 and the second piston 5, the second piston 5 is pressed downward. As a result, the sleeve 3 holds the original position (retracted end), and the second piston 5 compresses the spring 6 and moves forward until it contacts the forward end stopper surface 22b formed on the sleeve 3. The stroke of the second piston 5 alone is a first-stage stroke S1.

Next, when air is supplied from the second port 11 only to the gap 12 between the first piston 4 and the end face of the first housing 20a, the second piston 5 comes into contact with the projection 4a of the first piston 4. In the contact state, the sleeve 3 moves downward (moves forward) until it contacts the second stopper surface 21b provided on the second housing 20b. The downward movement (forward movement) stroke of the sleeve 3 is a second stage stroke S2 larger than the first stage stroke S1.

Further, when air pressure is supplied from the first port 8 in this state, the second piston 5 moves forward until it comes into contact with the forward end stopper surface 22b formed on the sleeve 3, and the first stage stroke S1 Is added to the second-stage stroke S2 to obtain a maximum-stage third-stage stroke S3.

Therefore, the air supplied to the gaps 9 and 12 is discharged from the forward end state of the third stroke S3 of the maximum stroke, and the sleeve 3 and the second piston 5 are returned to their original positions at the retracted ends. When returning by the force of 6b, the flange portion 5a of the second piston 5 comes into contact with the retreat end stopper 22a formed on the sleeve 3, and at the same time, the operating shaft 7 also comes into contact with the projection 4a of the first piston 4. The two contact portions push the sleeve 3 and the second piston 5, which are integral with the first piston 4, so that the surface pressure is reduced and the reciprocating member is quickly moved backward, so that quick response is obtained.

Further, a stopper structure for regulating the stroke end of the second piston 5 between the retreat end and the advance end is provided with a retreat end stopper surface 22a for regulating the retreat end to the sleeve 3, and an advance end opposed to the retreat end stopper surface 22a. The second piston 5 is provided with a flange portion 5a that comes into contact with the retreat end stopper surface 22a and the forward end stopper surface 22b. The housing 20a, that is, the cylinder bore, the sleeve 3, the first piston 4 and the second piston 5
Can be reduced in diameter, thereby enabling downsizing.

[0027]

As described above, according to the present invention, different three-stage strokes can be obtained by a short cylinder shaft length and a small-diameter cylinder bore, enabling downsizing. Reduce the pressing surface pressure,
Responsiveness is obtained quickly, and it has an optimum effect as an intake throttle valve, an exhaust brake valve, an exhaust recirculation device, etc. of an engine or an actuator for controlling a machine tool.

[Brief description of the drawings]

FIG. 1 is a sectional view of the present invention.

FIG. 2 is a conventional sectional view.

[Explanation of symbols]

 Reference Signs List 3 sleeve 4 first piston 4a protrusion 5 second piston 5a flange 6a spring 6b spring 7 operating shaft 8 first port 9 gap 10 passage hole 11 second port 12 gap 13 air vent hole 20a first housing 20b second housing 21a First stopper surface 21b Second stopper surface 22a Retreat end stopper surface 22b Forward end stopper surface

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI F15B 15/24 F15B 15/24

Claims (1)

(57) [Claims] 1. A sleeve which is slidably fitted in a cylinder with a constant stroke in an axial direction, a first piston fixed to one end of the sleeve, and a distance between the first piston and the first piston. And a second piston that slides in the sleeve with a constant stroke from this contact position to a forward end stopper surface provided at the other end of the sleeve, and the second piston always contacts the first piston. A spring that presses and biases the piston in one direction, one end of an operating shaft projecting out of the cylinder is connected to the second piston, and pressure is supplied to and discharged from the cylinder between opposing surfaces of the first piston and the second piston. And a second port for supplying and discharging pressure between the first piston and the inner end surface of the cylinder. 1
A second stopper surface for restricting the stopper surface and the forward end is provided opposite to the first stopper surface, and the sleeve has a retreat end stopper surface facing the other end of the forward end stopper surface; A multi-stage stroke cylinder, wherein a piston is provided with a flange portion that comes into contact with the forward end stopper surface and the backward end stopper surface.