阅读说明：本技术 活塞-气缸单元 (Piston-cylinder unit ) 是由 马丁·肯里奇 于 2019-01-10 设计创作，主要内容包括：一种活塞-气缸单元,包括气缸壳体(1)和活塞(3),该气缸壳体具有气缸内腔(2),该活塞布置在所述气缸内腔(2)中,从该活塞伸出活塞杆(4),该活塞杆穿过开口从所述气缸壳体(1)伸出,并且在此借助于布置在所述气缸壳体(1)上的活塞杆密封件(12)相对于所述气缸壳体(1)密封。在所述活塞杆(4)上设置了随同所述活塞杆(4)一起运动的由塑料构成的滑动套筒(11),所述活塞杆密封件(12)贴靠在该滑动套筒上。(A piston-cylinder unit comprising a cylinder housing (1) having a cylinder interior (2) and a piston (3) which is arranged in the cylinder interior (2), from which a piston rod (4) projects which projects from the cylinder housing (1) through an opening and is sealed off from the cylinder housing (1) by means of a piston rod seal (12) arranged on the cylinder housing (1). A sliding sleeve (11) made of plastic is arranged on the piston rod (4) and moves together with the piston rod (4), and the piston rod seal (12) is attached to the sliding sleeve.)

1. A piston-cylinder unit having a cylinder housing (1) with a cylinder interior (2) and a piston (3) which is arranged in the cylinder interior (2), from which a piston rod (4) projects, which emerges from the cylinder housing (1) through an opening and is sealed off from the cylinder housing (1) by means of a piston rod seal (12) arranged on the cylinder housing (1), characterized in that a sliding sleeve (11) made of plastic, which moves together with the piston rod (4), is provided on the piston rod (4), against which sliding sleeve the piston rod seal (12) bears.

2. Piston-cylinder unit according to claim 1, in which the sliding sleeve (11) has a sealing section (11a) in the region of which the piston rod seal (12) bears against the sliding sleeve (11) and a guide section (11b) in the region of which a sliding guide is formed between the sliding sleeve (11) and the cylinder housing (1), wherein the sealing section (11a) and the guide section (11b) are located in different sections of the longitudinal extension of the sliding sleeve (11).

3. Piston-cylinder unit according to claim 2, in which the outer diameter of the sliding sleeve (11) is smaller in the region of the sealing section (11a) than in the region of the guide section (11 b).

4. Piston-cylinder unit according to one of claims 1 to 3, characterised in that the cylinder housing (1) has an outwardly projecting, pipe-shaped section (9a) which forms an opening through which the piston rod (4) emerges from the cylinder interior (2) and which forms a radial bearing for the sliding sleeve (11), wherein the cylinder housing (1) and the pipe-shaped section (9a) are of a plastics material and at least a part of the cylinder housing (1) and the pipe-shaped section (9a) are of a material-integral construction with one another.

5. The piston-cylinder unit as claimed in one of claims 1 to 4, characterized in that the cylinder housing (1) has a base body (6) and a sliding sleeve (7) made of plastic arranged inside the base body (6), on which sliding sleeve a piston seal (5) arranged on the piston (3) is applied for sealing between the piston (3) and the cylinder housing (1).

6. A piston-cylinder unit according to any one of claims 1 to 5, characterised in that in the retracted end position of the piston (3) a section of the piston seal (5) or a further seal (29) arranged on the piston (3) bears against a sealing surface (7b, 30) of the cylinder housing (1) and lifts off from the sealing surface (7b, 30) when the piston (3) travels towards the forwardly projecting end position, wherein the sealing surface (7b, 30) is inclined at least 45 ° with respect to a direction parallel to the longitudinal centre axis (8) of the cylinder housing (1).

7. Piston-cylinder unit according to claim 6, in which the sealing surface (7b) is formed by an end section (7a) of the sliding sleeve (7) which projects in the direction of the central longitudinal mid-axis (8) of the cylinder housing (1).

8. Piston-cylinder unit according to one of claims 1 to 8, characterised in that the piston and the piston rod (4) have a plastic material and are constructed integrally of one another.

9. Piston-cylinder unit according to claim 8, in which the piston rod (4) has a first section (4a) of plastic material which is constructed integrally with the plastic material of the piston (3) and a second section (4b) of metal from which projects a projection (4c) which is made of metal and is embedded in the plastic material of the first section (4 a).

10. A vacuum valve with a valve opening (18) and a closure member (17) which is displaceable between an open position in which the valve opening (18) is open and a closed position in which the valve opening (18) is closed, characterized in that, for displacing the closure member between the open position and the closed position, the vacuum valve has a drive device which comprises a piston-cylinder unit according to any one of claims 1 to 9.

Technical Field

The invention relates to a piston-cylinder unit having a cylinder housing with a cylinder interior, and a piston which is arranged in the cylinder interior and from which a piston rod projects, which piston rod leads out of the cylinder housing through an opening and is sealed off from the cylinder housing by means of a piston rod seal arranged on the cylinder housing.

Background

Pneumatic piston-cylinder units made of plastic are known, which are used as drives for vacuum valves, for example. Generally, for a long-lasting work, lubrication with grease or engine oil is required. The disadvantage here is that lubricant drainage is virtually always present again, which can be problematic in sensitive environments, for example, in clean room conditions. The amount of lubricant to be introduced is always critical and it is not easy and involves high costs to apply this amount of lubricant precisely.

Lubricant-free working piston-cylinder units are also known, for example, from US 3,703,125 and US 3,286,737. For this purpose, a material containing at least one solid lubricating substance is used in the region of the cylinder wall. Thus in US 3,286,737 the cylinder liner is provided with an inner layer containing a lubricating substance which may be constituted by molybdenum disulphide, graphite, tungsten disulphide, tellurium disulphide, selenium disulphide, titanium disulphide or mixtures thereof.

Disclosure of Invention

The object of the invention is to provide an advantageous piston-cylinder unit of the type mentioned in the introduction which is distinguished in particular by a low level of particles released to the environment of the piston-cylinder unit, which is advantageous in particular in clean room conditions. According to the invention, this is achieved by a piston-cylinder unit having the features of claim 1.

In the case of the piston-cylinder unit according to the invention, which is in particular pneumatic, a sliding sleeve made of plastic is provided on the piston rod, which sleeve moves together with the piston rod, against which sliding sleeve a piston rod seal is applied, by means of which the piston rod is sealed off from the cylinder housing. By providing the piston rod with a sliding sleeve, a significant reduction of the generation of particles during the movement of the piston rod is achieved. Advantageously, the sliding sleeve may also be used for axially movable guiding of the piston rod relative to the cylinder housing. For this purpose, the sliding sleeve can have a guide section, in the region of which a sliding guide is formed between the sliding sleeve and the cylinder housing. It is particularly advantageous if the sliding sleeve has a sealing section and a guide section in different regions of the longitudinal extension of the sliding sleeve, in the region of which sealing section the piston rod seal bears against the sliding sleeve, i.e. the sealing section and the guide section do not overlap with respect to the axial direction of the piston rod. The guiding function and the sealing function can thus be separated from each other.

Advantageously, the sliding sleeve may contain a solid lubricating substance. This may be, for example, molybdenum disulfide, graphite, ceramic particles (e.g., glass spheres), finely distributed soft metals (e.g., aluminum, copper, lead), or plastics such as PTFE, or combinations thereof.

For axially guiding the sliding sleeve, the cylinder housing may advantageously have a tubular section which forms an opening through which the piston rod is guided out of the cylinder chamber, wherein the tubular section axially movably guides the sliding sleeve, i.e. forms a radial bearing for the sliding sleeve. In particular, the tube-shaped section can project from the top cover of the cylinder housing on the outside.

In an advantageous embodiment of the invention, the cylinder housing has a base body and a sliding sleeve made of plastic arranged inside the base body, on which sliding sleeve a piston seal arranged on the piston is applied for sealing between the piston and the cylinder housing. The static requirements for the cylinder housing and the requirements with respect to the contact surface with the piston seal can thereby be separated from one another. Advantageously, the sliding sleeve may contain a solid lubricating substance. This may be, for example, molybdenum disulfide, graphite, ceramic particles (e.g., glass spheres), finely distributed soft metals (e.g., aluminum, copper, lead), or plastics such as PTFE, or combinations thereof.

In a possible embodiment of the invention, in the retracted end position of the piston, a section of the piston seal or a further seal arranged on the piston rests against a sealing surface of the cylinder housing, which is inclined by at least 45 ° relative to a direction parallel to a longitudinal center axis (axial direction) of the cylinder housing, preferably perpendicular to the longitudinal center axis of the cylinder housing. As the piston travels towards the advanced end position, the section of the piston seal or another seal arranged on the piston lifts off the sealing surface. As a result, an additional sealing of the compressed air introduced into the cylinder chamber in the retracted end position of the piston can be achieved, as a result of which the compressed air consumption can be reduced.

The piston-cylinder unit according to the invention can be used in combination with different devices to be driven. An advantageous application is, in particular, a vacuum valve with such a piston-cylinder unit, which forms the drive means of the vacuum valve or at least a part of the drive means of the vacuum valve, in order to displace the closing part of the vacuum valve between an open position, in which the valve opening is open, and a closed position, in which the valve opening is closed.

Drawings

Further advantages and details of the invention are described below with the aid of the figures.

Fig. 1 and 2 are oblique views from different viewing directions of an embodiment of a piston-cylinder unit according to the invention;

FIG. 3 is a side view;

FIG. 4 is a cross-sectional view taken along line AA of FIG. 3 (advanced end position of the piston);

FIG. 5 is a sectional view corresponding to FIG. 4 in the retracted end position of the piston;

fig. 6 is an oblique view of a vacuum valve with such a piston-cylinder unit;

FIG. 7 is a side view;

fig. 8 is a sectional view (closed position of the closure) taken along the line BB of fig. 7;

FIG. 9 is a cross-sectional view similar to FIG. 8 in the open position of the closure;

FIG. 10 is a cross-sectional view in a diagonally opposite direction (of two opposing set screws);

fig. 11 is a part of a sectional view of a piston-cylinder unit according to a modified embodiment of the present invention.

Detailed Description

In fig. 1 to 5, an exemplary embodiment of a piston-cylinder unit driven by compressed air according to the invention is shown. The piston-cylinder unit has a cylinder housing 1 with a cylinder interior 2. A piston 3 is arranged in the cylinder chamber 2. A piston rod 4 projects from the piston 3 and is guided out of the cylinder housing 1 through an opening.

The cylinder housing 1 has a longitudinal center axis 8. The longitudinal center axis 8 of the cylinder housing 1 and the longitudinal center axis of the piston rod 4 lie on a common straight line (or, in other words, overlap).

The piston 3 is made of plastic, in particular thermoplastic. For example, the piston may be constructed of PA. It is also possible to constitute from POM. The plastic of the piston may be fibre reinforced.

A piston seal 5 is arranged on the piston 3, which piston seal surrounds the piston in an annular manner and seals the piston with respect to the cylinder housing 1. In this exemplary embodiment, the piston seal 5 is designed as a lip seal with a sealing lip 5 a.

The piston seal 5 is typically constructed of an elastomeric material, such as a thermoplastic elastomer. For example, the piston seal may be constructed of TPU. In this embodiment, the piston seal 5 is injected onto the piston. For example, a groove may be provided in the piston 3, and an O-ring may be inserted into the groove.

The cylinder housing 1 has a pot-shaped base body 6 which is made of plastic, in particular thermoplastic. For example, the substrate 6 may be made of PA. It is also possible to constitute from POM. The plastic of the matrix 6 may be reinforced with fibres.

The pot-shaped base body 6 is closed by a cover 9. The head cover 9 has an opening through which the piston rod 4 exits from the cylinder interior 2. In order to seal the head cover 9 with respect to the remaining cylinder housing 1, an annular seal 10 is used. In this embodiment, this is an O-ring which is arranged in a groove in the cover 9 and which bears against the sealing surface formed by the sliding sleeve 7.

In order to fix the cover 9 and the pressure seal 10, fixing screws (not shown in fig. 1 to 5) can be used. By means of these fastening screws, it is also possible in particular to fasten the piston-cylinder unit to a device using the piston-cylinder unit as a drive, as described below in connection with the vacuum valve.

The cover 9 may be formed from the same plastic material as the base 6.

The cylinder housing 1 further comprises a sliding sleeve 7 which is arranged in the base body 6 and which bears against the base body 6 and radially delimits the cylinder interior 2. The piston seal 5 bears against the sliding sleeve 7. The sliding sleeve 7 is made of plastic, such as PA or POM. The sliding sleeve 7 is provided with a solid lubricating substance, such as small glass balls.

The jacket 1b of the cylinder housing 1 is thus formed by the jacket of the base body 6 and the sliding sleeve 7.

The inner surface of the sliding sleeve 7 facing the longitudinal center axis 8 thus forms a sealing surface for the piston seal 5, in this embodiment for the sealing lip 5a of the piston seal 5. The sliding sleeve 7 is preferably injected onto the base body 6.

The piston 3 is movable in the cylinder chamber 2 between a retracted end position (fig. 5) and an advanced end position (fig. 4). In this embodiment, the movement from the advanced end position to the retracted end position takes place with compressed air which is introduced via a port 13 into a pressure chamber between the top cover 9 and the piston 3. The movement between the retracted end position and the extended end position is performed by means of a spring which is integrated into the device driven by the piston-cylinder unit, as will be described in connection with fig. 6-10. The space between the piston 3 and the bottom 1a is ventilated via a ventilation hole 14 in the bottom 1 a.

It can also be provided that: by means of compressed air between two end positions, or by means of compressed air between a retracted end position and an advanced end position, and by means of a spring in the opposite direction.

The sliding sleeve 7 has an end section 7a which projects in the direction of the longitudinal center axis 8 and which rests against the base body 6 in the region of the bottom 1a of the cylinder housing 1. The end portion 7a forms a sealing surface 7b, against which the portion 5b of the piston seal 5 rests in the retracted end position of the piston (fig. 5). In this exemplary embodiment, this sealing surface 7b for the section 5b of the piston seal 5 is at right angles to the axial direction of the cylinder housing (i.e. at right angles to the longitudinal center axis 8). In other embodiments, the sealing surface may be inclined with respect to this direction, wherein the sealing surface is inclined with respect to a direction parallel to the longitudinal mid-axis 8 by at least 45 °.

If the piston is moved from the retracted end position (fig. 5) towards the advanced end position (fig. 4), the section 5b of the piston seal 5 lifts off the sealing surface 7b of the sliding sleeve.

A sliding sleeve 11 is provided on the piston rod 4. The sliding sleeve is connected immovably with the piston rod 4 in relation to the piston rod 4 and thus moves along with the piston rod 4. A piston rod seal 12, which surrounds the sliding sleeve 11 in an annular manner, is applied to the sliding sleeve 11 and serves to seal the piston rod 4 with respect to the cylinder housing 1. The piston rod seal 12 thus surrounds the opening through which the piston rod 4 exits from the cylinder interior 2. In this embodiment, the piston rod seal 12 is arranged, preferably injected, on the cover 9. Retention in the groove of the top cover 9 is also conceivable and possible.

The piston rod seal 12 is made of an elastomeric material, such as a thermoplastic elastomer. The piston rod seal 12 may be made of TPU, for example.

The piston rod seal 12 is preferably designed as a lip seal with a sealing lip 12a which bears against the outer surface of the sliding sleeve 11.

The piston rod seal 12 bears against the sliding sleeve 11 in the region of a sealing section 11a of the sliding sleeve 11, along which it is moved during the piston displacement between the extended end position and the retracted end position of the piston 3. Furthermore, the sliding sleeve 11 has a guide section 11b which is connected to the sealing section 11a in the axial direction of the piston rod 4. The piston rod 4 is guided movably in the axial direction of the piston rod 4 relative to the cylinder housing 1 by means of the guide section 11 b. For this purpose, the cover 9 has a tubular section 9a which projects from the cover 9 in the direction away from the cylinder interior 2 and forms an opening through which the piston rod 4 is guided out of the cylinder interior 2. The tubular section 9a can be made of the same plastic material as the top cover 9 and is constructed integrally with the top cover 9.

The inner surface of the tubular section 9a forms a guide surface which interacts with the outer surface of the sliding sleeve 11 in its guide section 11b, thus forming a radial bearing for the sliding sleeve 11.

The outer diameter of the sliding sleeve is smaller in the region of the sealing section 11a than in the region of the guide section 11 b. This makes it possible to achieve a defined separation between the sealing function and the guiding function.

The sliding sleeve 11 is made of plastic, for example PA or POM. The plastic of the sliding sleeve 11 is provided with a solid lubricating substance, such as glass beads.

The sliding sleeve 11 is preferably injected onto the piston rod 4. It is also conceivable and possible to arrange the sliding sleeve by pressing or to hold it by gluing the sliding sleeve 11 to the piston rod 4.

Next to the end of the sliding sleeve 11 facing the cylinder chamber 2, a sealing material 15 is applied, for example injected, onto the outer surface of the piston rod 4. The sealing material may continue to the surface of the piston as shown. By means of the sealing material 15, an additional security against compressed air being discharged via possible gaps between the piston rod 4 and the sliding sleeve 11 is to be achieved. The sliding sleeve 11 preferably bears against the piston rod 4 without play.

The first section 4a of the piston rod 4 connected to the piston 3 comprises a plastic material, which is preferably formed integrally (material-integrated) with the plastic material of the piston 3. In which plastic material the protruding portion 4c of the second section 4b of the piston rod is embedded. The projection 4c and the second section 4b are made of metal and are preferably constructed integrally with one another. The second section 4b is used for connection of the piston 3 to a part of the device to be driven by the piston-cylinder unit. This makes it possible to form a connection that is stable in permanent operation.

Fig. 6 to 10 show an exemplary embodiment of a vacuum valve with a drive consisting of the previously described piston-cylinder unit. The vacuum valve has a valve housing 16 with a closure member 17 arranged in the valve housing 16. The closure member 17 is displaceable between a closed position (fig. 8), in which it closes the valve opening 18 in the valve housing 16, and an open position (fig. 9), in which the valve opening 18 is open. In this exemplary embodiment, the vacuum valve is embodied in the form of an angle valve, i.e. the valve housing 16 has a connecting socket 16a and a connecting socket 16b at right angles thereto, the connecting socket 16a having a valve opening 18 and the connecting socket 16b having a further opening.

In order to displace the closure 17 between the closed position and the open position, a piston-cylinder unit according to the illustrations in fig. 1 to 5 is used. For this purpose, the closure 17 is fastened to the piston rod 4, for example, by means of an external thread arranged on the end section of the piston rod 4, which can be screwed into an internal thread of the closure 17.

In order to additionally seal the piston rod 4 in the valve housing (for which only the piston rod seal 12 is not sufficient), a diaphragm bellows 19 is used. One end of the diaphragm bellows is connected vacuum-tightly to the closure member 17, for example by welding. On the other end of the diaphragm bellows 19 an end piece 20 is arranged, for example welded. This plate-shaped end piece 20 closes off the insertion opening 21 in the valve housing 16. A sealing ring 22 is provided between the end piece 20 and the valve housing for a vacuum-tight connection. The sealing ring 22 is pressed between the end piece 20 and the valve housing 16 by means of screws 23. These screws also pass through holes in the cylinder housing 1 and the top cover 9 and are screwed into threaded holes in the valve housing 16. By means of the screws 23, the piston-cylinder unit is thus also connected to the valve housing 16, wherein the top cover 9 is held together with the cylinder housing 1 and presses the seal 10.

If the closure element 17 is to be removed from the valve housing 16 for maintenance purposes, the screw 23 can be screwed out.

Furthermore, a support 25 is held on the spindle 4 by means of a tension ring 24. A helical spring 26 is arranged between the support 25 and the step of the nipple-shaped section 9 a. If the space between the piston 3 and the cover 9 is vented, the seal 17 is pressed by the coil spring 26 against the sealing surface 28 surrounding the valve opening 18 when the sealing ring 27 provided on the seal 17 is pressed, and the vacuum valve is closed (i.e. the sealing position of the seal 17).

By applying pressure to the space between the piston 3 and the cap 9, the closure 17 is lifted off the sealing surface 28 and travels to its open position.

Fig. 11 shows a slightly modified embodiment of a piston-cylinder unit according to the invention. In particular, the difference from the preceding exemplary embodiment is that an additional sealing element 29 is provided on the piston 3, which in the retracted end position of the piston 3 rests against a sealing surface 30 of the cylinder housing 1. An additional seal is thereby formed in the retracted end position of the piston, preventing compressed air from being discharged via the vent hole 14.

Various other modifications to the described embodiments of the invention are contemplated and possible without departing from the scope of the invention.

The vacuum valve driven by the piston-cylinder unit according to the invention can also be designed in other ways in the form of an angle valve. The displacement of the closure between the open position and the closed position can also take place, for example, in the manner of an L-valve, wherein the two movement components of the closure can be brought about by a single piston-cylinder unit (as is known, by corresponding guide elements), or there can also be two separate piston-cylinder units for the two movement components, which are preferably designed in the manner according to the invention.

List of reference numerals

1 Cylinder housing

1a bottom

1b case

2 cylinder inner cavity

3 piston

4 piston rod

4a first section

4b second section

4c protruding part

5 piston seal

5a sealing lip

5b segment

6 base body

7 sliding sleeve

7a end section

7b sealing surface

8 longitudinal central axis

9 Top cover

9a connecting tube section

10 seal

11 sliding sleeve

11a seal segment

11b guide section

12 piston rod seal

12a sealing lip

13 port

14 vent hole

15 sealing material

16 valve housing

16a connecting pipe

16b connecting pipe

17 closure member

18 valve opening

19 diaphragm bellows

20 end piece

21 insertion opening

22 sealing ring

23 screw

24 tension ring

25 support piece

26 helical spring

27 sealing ring

28 sealing surface

29 seal

30 sealing surface