JPS6367041B2 - - Google Patents

Abstract

1. A pressure fluid cylinder comprising a longitudinally slotted cylinder tube (1) closed at its ends and enclosing a piston (5) provided therein in sealed relationship and for longitudinal displacement, which pistons carries a load transmission element (9) projecting outwardly through the longitudinal slot (3), the longitudinal slot (3) of the cylindrical tube (1) being sealed in the longitudinal direction of the cylinder by a sealing strip which is provided in the interior (2) of the cylinder tube, passes in the zone of the piston underneath the load transmission element (9) and is retained in contact, on both sides of the piston (5), with a sealing face (22, 25) of the cylinder tube wall, and being covered on the outside of the cylinder tube by a flexible cover strip (27) passing in the zone of the load transmission element (9) over or through the latter and being retained on the outer cylinder wall on both sides of the load transmission element (9), characterized in that the sealing strip (18) is held by the cover strip (27) in contact with the associated sealing face (22, 25) on both sides of the piston (5), through coacting releasable connection elements (26, 30) passing through the longitudinal slots (3) and extending over the length of the strip and that the connection elements (26, 30) are continuously released, in response to the longitudinal movement of the piston (5), in front of that end of the piston which faces the diminishing cylinder space (19 or 20) and engaged on the opposite side of the piston.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a piston-cylinder device, and particularly to a piston-cylinder device in which a piston does not have a piston rod extending in the axial direction, but a cylinder has a slit along the axial direction to transmit force or motion. The present invention relates to a piston-cylinder device in which a motion transmitting member attached to a piston extends laterally through a slit thereof. In such a piston-cylinder device, measures are taken to prevent pressure fluid from escaping from the axially extending slit during movement of the piston.

This piston rod-less type of device has, among other things, the following advantages: This arrangement thus requires little longitudinal space and, in addition, avoids the problems associated with piston rods extending from the cylinder. For example, the piston rod may bend due to impact applied to it. In addition, the force applied to the piston by a pressure fluid such as hydraulic oil or gas is directly guided by the piston through a slit along the longitudinal direction of the cylinder and transferred to a motion transmission element extending outward. Directly transmitted.
Here, the slit through which the motion transmission element projects must be sealed. The pressure space inside the cylinder is sealed between the piston and the inner surface of the cylinder by a seal ring or a seal sleeve formed on the piston. Further, the slit in the longitudinal direction of the cylinder is sealed by a band-shaped sealing member. The sealing member is guided between the sealing part of the piston and the motion transmission element in a pressure-free region.

There are various types of longitudinal slit seal structures. West German Patent Publication No. 843482 proposes the use of a sealing member having a rectangular cross section. The sealing element is placed in an internal longitudinal groove, which groove forms a lateral guide surface for the sealing element. When pressure is applied within the cylinder, the sealing member is pressed against the engagement surface. However, in practice, it is difficult to avoid that the sealing member hangs down inside the pressure chamber when no pressure is applied. This results in an initial leak when pressurized fluid enters.

Another type of cylinder arrangement is shown in German Patent Publication No. 846 493. Here, a sealing member having a generally U-shaped cross section is used. The flanges of this sealing member are mounted in corresponding recesses in the inner wall of the cylinder. Such a configuration improves the sealing effect of the pressure space and also increases the resistance to expansion of the diameter of the cylinder when pressure is applied. However, such structures are extremely expensive, multiple, and difficult to manufacture due to the following facts. That is, the piston must have a very special construction in order to guide the sealing member while the flange of the sealing member is placed in the corresponding recess of the cylinder.

West German Patent Publication No. 21162572 proposes a simple cylinder made of non-magnetic material. Here, the cylinder has a magnetic material in a region of the wall parallel to the slit along the longitudinal direction, and the sealing member made of the magnetic material cooperates with the magnetic material to be attracted by the magnetic force of the magnetic material. It's summery. Since such a sealing member is made of metal, slight leakage cannot be avoided in practice. Therefore, this type of cylinder seal structure can hardly be used for liquids.
In practice it can only be used in the case of compressed air. In addition, in practice, the magnetic member used to hold the sealing member adsorbs extraneous iron-containing materials such as pieces of iron. Therefore,
This may impair the proper positioning of the sealing member, or even interfere with its operation. The sealing member used is a very thin metal tape or web that is not laterally guided by a magnetic member. Therefore, in certain operating conditions, the metal tape could move laterally and explode into dislodgement when pressure was applied, creating a dangerous operating condition.

Also, in order to cover the slit along the longitudinal direction,
It has been proposed to use a metal band-shaped covering member. This covering member was arranged on both sides of the motion transmitting member on the outside of the cylinder. This covering member is used to cover the slit outwardly and prevents dirt and the like from entering. Such a metal covering member can be held by a magnetic member. However, it is expensive to hold such elements magnetically within the cylinder or outside the cylinder. This is because special steel parts must be used, they must be precisely machined to fit the cylinder, and the surfaces must be coated or sealed.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a method in which a motion transmitting element connected to a piston extends through a longitudinal slit, and the remaining exposed slit is sealed with a simple sealing structure, yet effectively and inexpensively. The object of the present invention is to provide a piston/cylinder device that can achieve the desired results.

In order to achieve the above object, in the piston cylinder device of the present invention, a seal is provided by a pair of flexible sealing members, and these sealing members are made of mutually engaging long lengths of projections and grooves. and an elongated protrusion formed on the seal member disposed inside the piston and an elongated protrusion formed on the seal member disposed inside the piston. It consists of a long groove formed in the seal member. These sealing members can be made of synthetic resin and are mounted in the following manner with respect to the actuating member mounted on the piston. That is, upon movement of the piston, the actuating member separates the two sealing members from each other on one side and closes again the protrusion and groove of the engagement means on the other. The slit is thus sealed continuously and effectively in the pressure region or pressure chamber of the cylinder.

Embodiments of the present invention will be described below with reference to the drawings.

A cylinder chamber 2 is formed in the cylinder 1 in an eccentric manner. This cylinder chamber 2 is
It has an axis 2a (FIG. 1) eccentric to the axis of symmetry 1a of the cylinder 1. The cylinder 1 has a flat upper end surface 1b and a lower end surface 1c that are parallel to each other.
is formed. A slit 3 is formed in this cylinder along the longitudinal direction. Further, both ends of the cylinder 1 are closed by end covers 4. This cover 4 is sealed with a pressure-resistant seal. The piston 5 is slidable within the cylinder 1 and has ring-shaped sealing sleeves 6, 7 on both end faces thereof. These sleeves 6 and 7 provide a seal against the inner circumferential wall surface of the cylinder chamber 2. A region 8 between the piston heads formed with an enlarged diameter at both ends of the piston 5
is formed into a rod shape with a small diameter. Further, as shown in FIG. 2, a motion transmitting element 9 for transmitting force and motion is provided in the small diameter region 8 of the piston, for example.
It is fixed with screws etc. The element 9 is
It protrudes outward through the slit 3 with some play in the lateral direction with respect to the slit, and the outwardly protruding portion is configured as a rib 10, and a yoke 11 is connected to the outer end of the rib. ing. The yoke 11 extends laterally to surround the upper region of the cylinder 1. The yoke 11 is integrally provided with a pair of flanges 12 spaced parallel to each other,
Through this flange 12 the element 9 and the piston 5
is connected to an external device (not shown). A pressure chamber 19 is formed between the cover 4 at both ends and the end surface of the piston head surrounded by the sleeves 6 and 7, and when pressure fluid is introduced into the pressure chambers 19 and 20, the piston 5 slides. The motion is transmitted via the motion transmission element 9 and the flange 12 to an external device. Note that this piston has a double head type structure.

The yoke 11 has a substantially U-shaped cross section, and a band-shaped guide member 14 is attached to each leg portion 13 hanging down from both sides of the yoke 11 . These guide members 14 are connected to guide grooves 16 that are formed on the outer wall of the cylinder and constitute guide rails.
and are adapted to slide within these grooves. The position of the guide member 14 is adjusted by a retaining screw 15 constituting an adjusting means. As a modification, the pair of leg portions 13 may be configured to further extend toward the lower end surface 1c, as shown by chain lines in FIG. 2. Since this is a modification, only one leg 13 is shown together with the guide member 14a and the screw 15 in FIG. The extension 17 carries a guide member 14a, which is held by a screw 15. The left and right guide members 14 or, in the case of a variant, an additional guide member 14a guide the movement transmission element 9 in parallel movement and at the same time move the cylinder 1 in the event of pressure acting on the cylinder 1. It also serves to prevent slit 3 from expanding due to expansion of slit 1.

The slit 3 has a two-element seal arrangement, namely a first flexible inner seal member 18.
and a second flexible outer seal member 27 (see Figures 1, 3 and 4).

These seal members 18 and 27 are fixed to the end cover 4. The inner sealing element 18 seals the slot 3 in the region of the pressure chamber formed between the piston 5 and the respective end cover 4. Thus, when pressurized fluid enters chambers 19, 20, each chamber is completely sealed. The inner seal member 18 extends over the entire length of the cylinder 1. As shown in FIGS. 3 and 4, the sealing member 18 is connected to a guide body 21 having a substantially rectangular cross section that constitutes the guide body.
has. The guide body 21 is mounted at the base of a longitudinal groove forming a sealing surface 22 (FIG. 3) and is guided by a guide surface 23 formed in the groove. Seal member 1 facing the piston
An elastic sealing tongue piece 24 is integrally formed on the side of 8, and the tongue piece has a wedge-shaped inclined shape, the base end of the tongue piece is connected to the sealing member, and the tip end is connected to the cylinder chamber 2. The surface smoothly follows the wall surface 102. That is, the seal tongue piece 24
is connected to the root portion 25' of the guide body 21, and the entire sealing member is integrally molded from synthetic resin. The seal tongue piece 24 is connected to the wall 102 of the cylinder chamber 2.
It tightly engages a sealing surface 25 formed by mechanical pressure. Tongue piece 24 of seal member 18
It is desirable that the sealing surface 25 be engaged with the sealing surface 25 without any gap so as to be aligned with the circumference of the wall surface 102 of the cylinder chamber 2.

The upper side of the sealing member 18, that is, the guide body 2
A rib 26 is formed along the longitudinal direction in the central portion of the portion above 1, and the rib 26
are inserted into a longitudinal slit 3 in a symmetrical state with respect to a symmetry axis 2b extending longitudinally at the center of the cylinder chamber 2. Preferably, the rib 26 is constructed integrally with the seal member 18. Further, the outer side of the slit 3 is closed by a band-shaped cover 27 made of highly flexible elastic synthetic resin. The cover 27 is provided over the entire length of the cylinder 1 and is attached to the end cover 4 at both ends. The cover 27 has a substantially rectangular cross section and is accommodated in a groove 28 formed in the upper end surface 1b of the cylinder 1 and extending in the longitudinal direction. The slit 3 is formed downward from the bottom surface of the groove 28. The cover 27 integrally has a pair of legs 29 hanging downward, and a groove 30 having a U-shaped cross section along the longitudinal direction is formed between them, and the rib 26 of the sealing member 18 fits into this groove 30. There is. The rib 26 and the U-shaped groove 30 are formed over the entire length of the cover 27 and the seal member 18. These ribs 26, grooves 30 and legs 29
This constitutes an engaging means consisting of a protrusion and a groove.

The aspect of ribs 26 on inner seal member 18 is best understood from FIG. In FIG. 4, vertical side surfaces 31 are formed on both sides of a rib 26 that rises from a main body 21 that spreads laterally, and a wedge-shaped portion 32 that slopes outward from the upper end of the side surface is formed. has been done. Its wedge-shaped portion 32
Above, an upper end portion 23 having a generally trapezoidal cross section is provided.
is formed. Therefore, when viewed in cross-section as a whole, the rib 26 has an enlarged head portion and a chamfered upper end surface. This chamfered portion may be a flat surface or a rounded surface, as long as it serves to easily fit the rib 26 into the groove 30. Corresponding to the shape of this rib 26,
The groove 30 is formed in such a manner that the pair of hanging legs 29 are slightly enlarged inward at the lower end to close the opening of the groove 30. The lower ends of the legs 29 fit snugly around the enlarged head portions of the ribs 26 to grip them.

The rib 26 is connected to the cover 27 as shown in FIG.
Since the legs 29 of the holder 29 are elastically deformed in the lateral direction, they can be continuously pushed into the groove 30. Then, in the state where the rib 26 is fitted into the groove 30,
Since the wedge-shaped surfaces 34 on the legs 29 and the wedge-shaped surfaces 32 on the ribs 26 constitute a releasable fitting structure, the cover 27 and the sealing member 18 are securely connected without leakage. The chamfered portion 33 of the head of the rib 26 allows the rib 26 to fit into the groove 3 as described above.
It has the effect of making it easy to fit into the 0. The vertical side surface 31 of the rib 26 and the inner side surface 34a of the leg 29 engage with each other when mated to form the wedge-shaped portions 32, 34.
to maintain mutual engagement more reliably.

Note that various modifications can be made to the seal structure portion. For example, instead of providing only one rib 26 as shown, a plurality of ribs 26 may be provided parallel to each other, and a corresponding plurality of grooves 30 may also be provided. or,
Cover the ribs 27 with the ribs 26 and grooves 30 reversed.
The sealing member 18 may be provided with legs that form grooves on the sealing member 18, or in the opposite configuration, a plurality of ribs and grooves may be provided. Furthermore, a combination of ribs and grooves can be constructed by having a plurality of ribs protrude from both the sealing member 18 and the cover 27 and engaging with each other.

Furthermore, an opening 35 (FIGS. 1 and 2) is formed in the inner surface of the motion transmitting element 9 along the axial direction. The sealing member 18 and cover 27 are separated from each other in the area where this element 9 is present, the sealing member 18 extending axially through the opening 35, and the cover 27 extending axially through the opening 35. It extends in the axial direction between a pair of flanges 12 on the outer surface of. This movement transmission element 9 can therefore be moved in the axial direction while separating the sealing member 18 and the cover 27 and fitting them together again. A portion of this element 9 between its outer surface and the bottom surface of the opening 35 is wedge-shaped in a longitudinal section, forming an elongated double wedge-shaped body 36. The shaped body 36 has a central plane passing through the center of the element 9 (the first
It is symmetrical to the figure). This double wedge-shaped body 36 guides the cover 27 on its upper side. This wedge-shaped body 36 is passed between the separate sealing member 18 and the cover 27. Further, at the end of the element 9, as shown in FIG.
Press the cover 27 toward the groove 28 located at b.
This pressure member 37 is composed of a roller, a circular pin, or the like, and is preferably located above the head portions at both ends of the piston 5.

Operation description: Pressure chamber 1 on both sides of piston 5
In areas 9 and 20, the cover 27 constituting the outer seal member and the seal member 18 constituting the inner seal member are engaged as shown in FIG. in a state. That is, the inner seal member 18 is held by the outer cover 27 due to the engagement between the rib 26 and the groove 30 within the slit 3. In this state, the seal member 18 is engaged with the seal surface 25 of the wall surface 102 of the cylinder chamber 2. Further, the guide body 21 of this seal member 18 engages with the seal surface 22 formed on the bottom surface of the groove, and the guide surface 23 on the side of this groove prevents this seal member 18 from shifting laterally. We are guiding you.

Pressurized fluid is introduced into chamber 20 through a conventionally configured end connection end (not shown) formed in end cover 4 . The other chamber 19 opens to the discharge side. This pressurized fluid can be either liquid or gas. The introduced pressurized fluid moves the piston 5 to the left from the position shown in FIG. During this movement, the wedge-shaped body 36 moves at its left end, i.e. in the area 8 between the heads of the piston 5.
In the area where no pressure is applied, the cover 27 and the seal member 18 are separated from each other, and the rib 26 of the seal member 18 is separated from the groove 30 of the cover 27. In this case, as shown in FIG. 4, the pair of legs 29 are elastically deformed laterally. The left pressure member 37 is a piston ring or seal sleeve 6 mounted on the head of the piston 5.
The sealing member 18 and the cover 27 are sandwiched between the ribs 26 and the grooves 30 to prevent the fitting between the ribs 26 and the grooves 30 from being inadvertently released on the left side of the piston, that is, in the area of the pressure chamber 19.

In addition, in the region on the right hand side of the piston 5 in FIG. 1, the cover 27 and the seal member 18 are pressed between the seal sleeve 7 attached to the head of the piston 5 and the pressure member 37. In this right-hand region of the piston 5, the rib 26 fits into the groove 30. Since the sealing member and the cover are continuously separated and fitted together as the motion transmitting element 9 moves, the pressure chambers 19 and 20 are always maintained in a sealed state.

In the case of an operation opposite to that described above, i.e. when pressure is applied to chamber 19 and the other chamber 20 opens to the discharge side, the piston moves in a similar manner in the opposite direction to that described above, i.e. to the right. . In this case as well, leakage of unpressurized fluid from chamber 20 is avoided, as described above.

Preferably, the motion transfer element 9 is of single unit construction. Of course, the elements may be constructed separately for each of the component parts 10, 11, 12, 17 and connected together by screws or welded together.

The guide grooves 16 formed along the longitudinal direction of the side wall of the cylinder are triangular in cross section with their vertices facing inward, and are provided parallel to each other over the entire length of the cylinder. Preferably, the band-shaped guide member 14 is configured to precisely engage the groove 16. The guide member 14 has a protruding portion having a triangular cross section corresponding to the triangular groove 16, has a generally prismatic shape as a whole, and is attached to a groove formed in a leg portion 13 formed in the yoke 11. The guide member 14 is made of a material with high strength and low friction, such as synthetic resin, preferably Teflon (trade name). By threading the screw 15, the position of the guide member 14 relative to the groove 16 can be adjusted.

Instead of using such a guide member 14, rollers or roller bearings can also be used in other configurations. Further, the guide member 14 is provided in the cylinder 1, and the guide groove 16 is provided in the leg portion 13 of the yoke 11.
A reverse configuration may also be used, such as providing the

The forces due to the movement of the piston 5 are transmitted directly to the movement transmission element 9. The lateral force or torque is
Since the piston 5 is received by the fitting between the guide groove 16 and the guide member 14, the movement of the piston 5 within the cylinder is not impaired and the slit 3 of the cylinder 1 does not open. The guide member 14 is preferably placed between the upper end surface 1b of the cylinder and the axis of symmetry 1a, and more preferably at a level that generally corresponds to the lower end position of the slit 3. When positioned as described above, the guide member 14 inside the yoke 11
However, since the cylinder 1 is pressed at the slit 3, expansion of the slit 3 is further suppressed. Therefore, the motion transmitting element 9 serves to maintain the dimensions of the cylinder and also to suppress expansion of the cylinder, since the guide member 14 engages in the groove 16 while the yoke 11 surrounds the cylinder 1.

The left and right guide grooves 16 formed in the cylinder 1 are
It has transverse surfaces (FIG. 2) that make an angle (α) of about 90 degrees to each other. Each of these planes therefore forms approximately 45 degrees with respect to the vertical axis of symmetry 2b. With such a configuration, the force in the radial direction of the motion transmission element 9 can be received evenly, and the guide groove 1 can be evenly applied.
6 can ensure accurate guidance.

The inner seal member 18 and the cover 27 constituting the outer seal member are always engaged with the corresponding seal surfaces 22, 25, 28 in the left and right regions of the piston 5, that is, in the pressure chambers 19, 20. The inner seal member 18 may hang down, the cover 2 may
7 is reliably prevented from buckling. This advantage is advantageous if the cylinder is fairly long. The longer the cylinder is, the more the problem becomes because the conventional structure requires the use of a longer piston rod, so the longer the cylinder, the greater the effect of the present invention.
Moreover, since the inner and outer seal members are directly fitted and fixed to each other via the slit 3, no separate holding member is required. Therefore, the production cost is also lower overall. In addition, the guide body 2 is attached to the inner seal member 18.
1 and the sealing tongue 24,
The sealing of the pressure chambers 19, 20 of the cylinder becomes more reliable and no leakage occurs even when working fluid at a considerable pressure is introduced. The left and right sealing tongues 24 have an elastic connection portion 25' between them and the main body 21 of the sealing member 18.
Since it has a high elasticity, the sealing tongue piece accurately fits the wall surface 102 of the cylinder chamber 2, so that a sufficient sealing effect can be obtained even if the diameter of the cylinder is considerably large.

It is desirable that the inner and outer seal members 18, 27 be made of highly elastic synthetic resin. The synthetic resin used is selected in consideration of mechanical strength and chemical influence on the fluid used. Also, instead of synthetic resin, a rubber material reinforced with fabric can also be used.

As described above, the present invention is not limited to the illustrated embodiments, but may include various modifications.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view taken along the axial direction to show an outline of a piston-cylinder device according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view of the piston-cylinder device taken along the line ``-'' in FIG. 1. The enlarged perspective view, Figure 3, shows the piston cut away along the - line in Figure 1.
A partially enlarged perspective view of the cylinder device, FIG.
FIG. 3 is a perspective view of a sealing structure portion explained in relation to the configuration of the cylinder and the guidance of the motion transmission means of the piston-cylinder device shown in the figure. 1... Cylinder, 3... Slit, 5... Piston, 9... Motion transmission element, 14... Guide member,
18... Inner seal member, 27... Outer seal member.

Claims (1)

[Claims] 1. A long tubular cylinder 1 with both ends closed.
a long piston 5 that is slidable within the cylinder; a slit 3 formed through the wall 102 of the cylinder in the longitudinal direction with respect to the axis of the cylinder; motion transmitting elements 9, 12 extending outwardly of said wall 102 for transmitting the relative motion between the piston and the cylinder to an external device;
and a sealing means provided over the entire length of the slit for elastically sealing the slit so as to close it in the area of the pressure chambers 19 and 20 formed in the cylinder, the sealing means being provided over the entire length of the cylinder. an inner seal member 18 placed on the inside of the cylinder and an outer seal member 27 placed on the outside of the cylinder.
a pair of flexible sealing members comprising a pair of flexible sealing members, sealing surfaces 22, 25 formed inside the cylinder and engaging said inner sealing members, and extending through said slit 3 and said inner and outer sealing members; an engagement means formed on opposing surfaces of the piston and a groove that can be elastically deformed and separated in the longitudinal direction, and the engagement means is related to the movement of the piston and the motion transmission element. the sealing members are separable on one side of the piston, and the sealing members are connected to each other in a region defining a pressure chamber on the other side of the piston to close the slit, and the sealing members are separated when the piston moves. separable from each other and recombinable, thereby continuously sealing the slit and sealing the pressure chamber, the length of which changes continuously in the axial direction by movement of the piston, and Piston-cylinder device, characterized in that the sealing members are separated from each other in the region where the piston is present, allowing movement of the motion transmitting element through the slit. 2. The engaging means comprises a rib 26 formed on the inner seal member 18 and an elastically deformable side wall 29 formed on the outer seal member 27 and forming a groove 30 having a U-shaped cross section. The piston/cylinder device according to item 1. 3. The rib 26 and the groove 30 have wedge-shaped portions 32 and 34 in cross-section, and these wedge-shaped portions keep the rib in a fitted state within the groove when the rib is engaged with the groove. 3. A piston-cylinder device according to claim 2, wherein the piston-cylinder devices are engaged with each other in a holding manner. 4 Said side wall 2 forming said rib 26 and groove
9 has parallel portions 31, 34a extending perpendicularly from the corresponding sealing member and adjacent to the wedge-shaped portions 32, 34, these corresponding parallel portions providing sealing engagement between the rib and the side wall. A piston-cylinder device according to claim 3. 5 The rib 26 has a chamfered head portion 33.
4. A piston-cylinder arrangement as claimed in claim 3, in which the piston-cylinder arrangement is formed with a groove, thereby facilitating insertion into the groove. 6. The inner seal member 18 is formed with a guide body 21 extending transversely to the longitudinal axis 2a of the cylinder chamber 2, and in order to positively guide the guide body 21 with respect to the slit. According to claim 1, guide surfaces 22, 23 are formed extending in a plane parallel to and intersecting the longitudinal axis, and the protrusion of the engaging means extends from the guide body. piston cylinder device. 7 A seal tongue piece 24 is provided which extends from the guide body and is elastically deformable with respect to the guide body, and a seal surface 25 that engages with the seal tongue piece is provided on the inner wall 102 of the cylinder chamber 2. 7. A piston-cylinder device according to claim 6, which is formed by: 8. The piston/cylinder device according to claim 7, wherein the seal tongue piece and the wall surface portion adjacent thereto are continuous so as to form a smooth peripheral surface. 9. The piston-cylinder device according to claim 7, wherein the seal tongue piece 24 is wedge-shaped in cross section, and a wider wedge-shaped portion is attached to the guide body 21 so as to be elastically deformable. 10 The motion transmission element has a wedge body 36 with a double wedge surface having a thick middle part and pointed ends, and the pointed ends of the wedge body are connected to the two sealing members. 2. The piston-cylinder device according to claim 1, wherein the piston-cylinder device is positioned between the seal members and enters between the seal members as the piston moves to separate the seal members. 11 A pressure member 37 is provided which is attached to the motion transmitting element 9 and engages with the outer seal member so as to press the seal member, and the piston is formed with a piston head which is movable in a sealing state within the cylinder. 11. A piston and cylinder device as claimed in claim 10, wherein said wedge body has pointed ends positioned generally in alignment with a piston head. 12. The piston/cylinder device according to claim 1, wherein the sealing member is made of elastic synthetic resin.