JPH01169103A - Rodless cylinder - Google Patents

Abstract

PURPOSE:To stabilize extension-contraction movement of bellows by forming a shape retention guide supported and guided with a support member always located in an inside recess of the bellows in the shape of an ellipsoid. CONSTITUTION:A shape retention guide 29, as it moves, engages with the inside recess of bellows 26, 27 and slides, while retaining the regularity of the wavy shape of the bellows, on support shafts 22, 23. The shape retention guide 29 is ellipsoidally formed with the distance between two guide holes 30, namely a pitch direction, as a major axis. The shape retention guide 29 engages with every several recesses of the bellows 26, 27, for example every one, two or three recesses. This makes it possible to increase the width in the axial direction of the shape retention guide 29 without shortening the effective stroke of a piston 24.

Description

Detailed Description of the Invention <Field of Industrial Application> The present invention provides a rod that can withstand relatively large changes in internal pressure and can flexibly expand and contract while maintaining a regular waveform and correct expansion and contraction direction. Regarding the less cylinder.

<Prior Art> In general, a rodless cylinder uses a piston as an actuating member that is moved in the direction of negative pressure due to the pressure difference between the left and right fluid chambers, and outputs the actuating force at the side of the cylinder during the reciprocating movement of the piston. It is.

There are two methods of output in this case:

That is, a magnetic piston is placed inside a cylinder made of a non-magnetic material, and an output member, which is a donut-shaped actuating body, is slidably fitted to the outer periphery of the cylinder, facing the piston, thereby coupling the two using a magnetic coupling method. The one that connects with.

A flexible steel belt is inserted into belt holes drilled in the cylinder wall near the ends of the left and right fluid chambers, and its ends are fixed to the piston, allowing the steel belt to slide longitudinally around the outer circumference of the cylinder. It is designed to go back and forth.

However, in the former method, the piston and the external output member are not mechanically connected but magnetically connected, so there is not enough coupling force to withstand a large load.Therefore, a stronger coupling force is required. In order to produce this, extremely expensive rare earth magnets must be used as materials for the piston and output member.

Moreover, when the output member slides, the cylinder and the large a! Therefore, wear powder from one or both of them will be scattered around, making it completely unsuitable for use in, for example, a clean room factory.

In the latter method, there is a belt hole in the wall of the fluid chamber, and airtightness cannot be maintained, resulting in malfunction or lack of accuracy in operation. Moreover, since the sliding friction of the steel belt in the belt hole is large, there is a drawback that the hole diameter gradually increases due to wear.

Therefore, in order to solve these conventional problems, the present applicant has proposed a rodless cylinder that utilizes the expansion and contraction of bellows (see Japanese Patent Application No. 142433/1982).

Such a rodless cylinder is constructed as shown in FIG. 5, and its operation is as follows.

That is, air is supplied under pressure from the air supply/discharge hole 62 to put the right fluid chamber 5 of the cylinder into the pressurization mode, and at the same time, the air supply/discharge hole 6
1 is opened to put the left fluid chamber 4 of the cylinder into a degassing mode, the piston 1 slides on the support shaft 10.11 and is moved to the left fluid chamber 4 side where the pressure is negative. As the piston moves, the bellows 2a on the right fluid chamber 5 side expands, and the bellows 2b on the left fluid chamber 4 contracts. Therefore, the right fluid chamber 5 and the left fluid chamber 4 are capable of moving the piston 1 while maintaining independent sealed chambers, and furthermore, the piston 1 and the workpiece 7, which is the actuated object, can be moved by the piston 1. It can be mechanically fixed via the outer peripheral member 17.

At this time, the shape-retaining guides 12 are engaged with all the concave portions of the bellows waveform in the movement direction inside both fluid chambers 4.5, so that the bellows waveform causes changes in depth and shallowness due to expansion and contraction. Even if the waveform is
It can extend and contract linearly in the stroke direction.

In particular, even if a large internal pressure is applied to the fluid chamber on the side that is in pressurization mode, the bellows body will not shift or curve in the direction perpendicular to the axis, maintaining the correct posture and waveform. It can be expanded and contracted linearly in the stroke direction.

<Problems to be Solved by the Invention> However, in such a rodless cylinder, the shape-retaining guide 12 is formed into a substantially perfect circular shape that matches the bellows shape with a circular cross section, and all recesses of the bellows waveform are formed. Because of this structure, the following problems are likely to occur.

That is, the shape-retaining guide 12 is formed with a pair of slide holes into which the support shaft 10° 11 is slidably inserted, but if the pitch of the pair of slide holes, that is, the distance between the holes is small, When the shape-retaining guide 12 moves, it tends to tilt with respect to the support shaft 10.11, and the shape-retaining guide 12
will move (stick-slip) while creating stickiness between the inner circumferential surface of the slide hole and the outer circumferential surface of the support shaft 10°11.

As a result, the smooth movement of the shape-retaining guide 12 is hindered, the predetermined regular bellows waveform is disturbed, and there is a possibility that the bellows will not be able to extend and contract linearly in the stroke direction. In addition, the bellows body is curved and 7
There is a risk of damage to the bellows.

In order to solve these problems, it is necessary to increase the axial support width of the shape-retaining guide 12, increase the length of the slide hole, and increase the pitch between the pair of slide holes as much as possible. However, if the axial width of the shape-retaining guide 12 is increased, 1. Since the total integrated width of the shape-retaining guides on the bellows contraction side also increases, the effective stroke of the piston becomes shorter, resulting in a problem that the range of application as a rodless cylinder becomes limited.

In addition, in order to make the pitch between the pair of slide holes as large as possible, it is necessary to increase the external size of the shape-retaining guide 12, but this also requires increasing the external size of the bellows, which increases the size of the cylinder body. Causes problems.

Therefore, in view of the above-mentioned conventional circumstances, the present invention aims to improve the arrangement position and shape of the shape-retaining guide to enable smooth movement of the shape-retaining guide and stabilize the expansion and contraction movement of the bellows. purpose.

Means for Solving the Problems〉 Therefore, the present invention has the following features: 1. A rodless cylinder whose operating member is a piston that is moved in the direction of negative pressure by a pressure difference between left and right fluid chambers, comprising two or more mutually parallel support members disposed between both end members of the cylinder; A piston supported and guided by a member and disposed to be reciprocating, and a bellows disposed between the piston and the end member,
It has left and right independent fluid chambers, and a shape-retaining guide that is always located in the inner recess of the bellows and is supported and guided by a support member so as to be able to reciprocate while holding the bellows (7).
, and the shape-retaining guide is formed in an elliptical shape with its long axis in the direction connecting the contact points with both support members, and is disposed in every few recesses of the bellows waveform. Let's say it's a rodless cylinder.

<Operation> In such a configuration, when the piston is moved to the side of one fluid chamber with negative pressure by sliding on the support member, the bellows on the side of the other fluid chamber expands as the piston moves, and the bellows on the side of the movement direction expands. The bellows of the fluid chamber contracts. Therefore, the piston can move while both fluid chambers maintain independent sealed chambers. In this case, as a result of forming the shape-retaining guide in an elliptical shape with the long axis being the distance between the guide holes, that is, the pitch direction, it is possible to increase the pitch of the slide holes, and it is necessary to increase the external shape of the shape-retaining guide. Therefore, it is possible to prevent the bellows from increasing in size, and by extension, the cylinder body from increasing in size. In addition, by engaging the shape-retaining guides in every few recesses of the bellows waveform, the total length of the shape-retaining guides when they are brought together closely on the contraction side can be minimized, without shortening the effective stroke of the piston. It becomes possible to increase the width of the shape-retaining guide in the axial direction. Furthermore, smooth movement of the shape-retaining guide can be realized, and the predetermined regular bellows waveform is not disturbed, so the bellows can extend and contract linearly in the stroke direction, and the curve of the bellows body can be adjusted. This prevents damage to the bellows due to

<Example> Next, embodiments of the present invention will be described based on the drawings.

In FIG. 1, S is a rodless cylinder according to the present invention, 20.21 is an end member for airtightly closing both ends of the cylinder S, and 22.23 is a pair of support shafts as support members. The end members 20 and 21 are fixed facing each other at a predetermined interval, and are slidably supported through the piston 24. 25 is a gasket for fluid sealing loaded inside the piston 24, and 26 and 27 are flexible and strong pressure-resistant bellows, one end of which is connected to the end member 20 as shown in the figure.
．． 21, and a piston 24 is airtightly attached to the end on the substantially central side thereof. 28 is a reinforcing ring member attached to the corrugated recess on the outer periphery of the bellows 26 and 27, and is necessary to maintain a regular bellows waveform against changes in internal pressure and expansion and contraction in the axial direction. It should be installed accordingly.

29 is a guide hole 30 for inserting the support shaft 22.23.
Shape-retaining guides are disposed on the support shafts 22, 23 so as to be able to freely slide independently, and as they move, they engage with the inner recesses of the bellows 26, 27. It slides on the support shafts 22 and 23 while maintaining the regularity of the bellows waveform. This shape-retaining guide 29 is formed in an elliptical shape whose major axis is the interval between the two guide holes 30, 30, that is, the pitch direction.

That is, as shown in FIGS. 2 and 3, the shape-retaining guide 29 has a shape in which an elliptical plate portion 29a and elliptical convex portions 29b concentric with the plate portion 29a are integrally formed on both sides of the plate portion 29a. A pair of guide holes 3o are formed in the long axis direction of the ellipse. Note that this guide hole 30 penetrates through the plate portion 29a while being partially opened at the periphery of the convex portion 29b.

Reference numeral 31 denotes a pair of fluid circulation holes formed opposite to each other in the short axis direction of the ellipse of the shape retaining guide 29.

The shape-retaining guide 29 has a bellows 26.2.
For example, one every few recesses of No.7.

Every two or three pieces are engaged.

In this embodiment, the air supply hole is provided using the support shafts 22 and 23.

That is, the pair of support shafts 22 and 23 are formed of hollow pipes and pipes, and one end of each is passed through the end member 21 and serves as connecting portions 22a and 23a with an external supply/discharge mechanism (not shown). There is. Then, the air supply hole 22b of one support shaft 22
is opened to the fluid chamber 32, and the air supply/discharge hole 23b of the other support shaft 23 is opened to the fluid chamber 33.

In this configuration, air is supplied under pressure from the connecting portion 22a of one of the support shafts 22 to the external supply/discharge mechanism to supply the air to the right fluid chamber 32.
When the left fluid chamber 33 is set to the pressurization mode and the connecting portion 23a of the other support shaft 23 with the external supply/discharge mechanism is opened to set the left fluid chamber 33 to the deaeration mode, the piston 24 slides on the support shafts 22 and 23. and is moved to the left fluid chamber 33 side where the pressure is negative. In this case, the air forced from the connecting portion 22a flows into the right fluid chamber 32 through the air supply/discharge hole 22b of the support shaft 22, and presses the piston 24 in the right fluid chamber 32.

The left fluid chamber 3 pressurized by the pressing movement of the piston 24
3 flows into the support shaft 23 through the air supply/discharge hole 23b and is discharged from the connecting portion 23a.

As the piston 24 moves, the bellows 26 on the left fluid chamber 33 side contracts, and the bellows 27 on the right fluid chamber 32 expands. Therefore, the shape-retaining guide 29 also moves, and the right fluid chamber 32
The piston 24 can be moved while the left fluid chamber 33 and the left fluid chamber 33 each maintain an independent sealed chamber.

According to this configuration, as a result of forming the shape-retaining guide 29 into an elliptical shape whose major axis is the pitch direction of the two guide holes 30, it becomes possible to increase the pitch of the guide holes 30, and the shape-retaining guide 29 Since it is not necessary to increase the size of the bellows 26, 27 while keeping it circular, it is possible to prevent the size of the bellows 26, 27 from increasing in size, and by extension, from increasing the size of the cylinder. Furthermore, by engaging the shape-retaining guide 29 in every few recesses of the bellows waveform, the axial width l of the shape-retaining guide 29 shown in FIG. 1 can be increased without shortening the effective stroke of the piston 24. becomes possible.

As a result, a stable posture of the shape-retaining guide 29 and smooth movement without stick-slip can be realized, and the predetermined regular bellows waveform is not disturbed, so that the bellows 26 and 27 extend and contract linearly in the stroke direction. The bellows 26 and 27 can be prevented from being damaged due to displacement and curvature of the bellows body.

In addition, as another embodiment, as shown in FIG.
End member 2 on the opposite side of the connection part with the external supply/discharge mechanism in 2.23
0 is provided with a communication hole 34 that communicates with the outside, and a seal member 35 made of rubber that normally closes the communication hole 34 is provided.

According to this configuration, the sealing member 35 is ruptured when the insides of each fluid chamber and the support hole become abnormal pressure due to air pressure control error, abnormal operation of the compressor as an external pressure supply mechanism, clogging of the circulation hole, etc. Since the internal air is discharged to the outside, damage to the bellows 26, 27, reinforcing ring 28, etc. can be prevented, and this can serve as a safety measure.

<Effects of the Invention> As explained above, according to the present invention, in the rodless cylinder that utilizes the expansion and contraction of the bellows, the shape-retaining guide is
Since the guide hole is formed into an elliptical shape with the long axis in the pinch direction, and the shape-retaining guide is engaged with every few recesses of the bellows waveform, the outer shape of the bellows becomes larger, and the cylinder body becomes larger. This makes it possible to increase the pitch of the slide holes while preventing this, and also increases the width of the shape-retaining guide in the axial direction without shortening the effective stroke of the piston, resulting in stable movement of the shape-retaining guide. This allows for smooth movement and prevents damage to the bellows.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing an embodiment of a rodless cylinder according to the present invention, Fig. 2 is a front view showing the structure of a shape-retaining guide in the same embodiment, Fig. 3 is a perspective view thereof, and Fig. 4 is a sectional view showing an embodiment of a rodless cylinder according to the present invention. A sectional view showing another embodiment, and FIG. 5 is a sectional view showing a conventional rodless cylinder. 22.23... Support shaft 24... Piston 2 [i, 27... Bellows 29... Shape retaining guide 30... Guide hole S...Rodless cylinder

Claims (2)

[Claims] (1) In a rodless cylinder whose operating member is a piston that is moved in the direction of negative pressure by the pressure difference between the left and right fluid chambers, two or more mutually parallel support members are arranged between both end members of the cylinder. , a piston supported and guided by the support member so as to be able to reciprocate; and a bellows disposed between the piston and the end member to form left and right independent fluid chambers; and a recess inside the bellows. a shape-retaining guide that is supported and guided by the support member and is arranged to be able to reciprocate while always holding the bellows; 1. A rodless cylinder characterized in that it is formed in an elliptical shape with a long axis at , and is disposed in every few recesses of the bellows waveform. (2) The rodless cylinder according to claim 1, wherein a reinforcing ring is disposed in the concave portion of the outer peripheral surface of the bellows.