JPS62171505A - Piston-cylinder device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a cylinder whose axial end is closed with an end cap; a piston that slides in the axial direction within the cylinder body; The present invention relates to a piston and cylinder device having a piston rod extending longitudinally slidably through a rod seal in at least one end cap.

(Prior Art and its Problems) Experimental, development and manufacturing laboratories, for example in biochemistry laboratories or microchip development or manufacturing clean rooms in the computer industry, often have operations within them that are exposed to airborne contaminants. A dust-free, clean, and sterile environment is required to avoid being affected by

For this reason, the above-mentioned type of piston-cylinder device is
It was rarely put to practical use in such fields or operations. First, there was no guarantee that the fluid drive medium would never leak from the seal ring used in the cap, where the piston rod extends out of the cylinder.

For example, if the medium is a hydraulic medium, the thin film leaks from the □ ring along the piston rod and thus comes into contact with the external environment, thus contaminating the air with the medium. Since the seal ring gradually wears out, this phenomenon becomes more pronounced as the equipment ages.

Moreover, if the piston/cylinder device is pneumatically driven,
If there is a leak, it will jet out of the cylinder and create a continuous swirling motion of the surrounding air, further increasing the risk of contamination. Additionally, this escaping air is generally mixed with particles of lubricating oil so that the oil is discharged into the environment in suspension. The air is therefore contaminated to the point that it no longer meets industrial clean room standards.

SUMMARY OF THE INVENTION In view of the above, it is an object of the present invention to provide a piston-cylinder device of the above-mentioned type, which can eliminate the adverse effects of contamination on the immediate surroundings and which can be used in industrial clean rooms.

(Means for Solving the Problems) In order to achieve the objects of the present invention stated in this specification, the present apparatus includes a cylinder body, first and second end caps that close both axial ends of the cylinder body, and an axially slidable piston disposed within and connected to the piston with a predetermined portion of its length passing through the first end cap;
a piston rod extendable with a sealing ring therebetween; and a sealing ring that wraps around the piston on the outside of said cylinder body, said sealing ring having a sealing ring that extends between said piston rod at least a portion of said piston rod outside said body around its entire periphery. an airtight peripheral wall surrounding the cylinder with a radial clearance, the peripheral wall being fixed at one axial end to the shell;
The other axial end is hermetically engaged with the piston rod to limit an annular header space between the header and the piston rod, and a duct for discharging fluid from the header space into the receiving space.

In the above configuration, the position at which the piston rod protrudes from the cylinder or cylinder cap.

It is directly connected to a sealed header space which receives the leakage drive fluid and the substances contained therein, so that the fluid and its contents do not escape into the immediate surroundings of the piston-cylinder arrangement.

In fact, such escaping fluids (particularly air) and contaminants are carried via openings in the header space and ducts exiting the openings to a position where they can be blown into the environment outside the space, where the piston-cylinder arrangement is installed. will be installed. The escaping air in the outlet end of the evacuation duct is therefore generally at high pressure and leaves the evacuation duct via the path of least resistance, advantageously not requiring separate evacuation means.

The piston-cylinder arrangement according to the invention can therefore be used in spaces where a high degree of cleanliness is required, where the air meets the highest standards.

Other advantageous developments of the invention are described in the claims.

Corresponding to such a development of the invention, the peripheral wall end adjacent to the piston rod is fixed to the piston rod, the peripheral wall extending completely circumferentially and being extensible or elastic in the length direction of the piston rod. The ends of the circumferential wall are provided with one or more sections that are flexible or have elastomeric properties, and are fixed to the cylinder on the one hand and completely sealingly fixed to the piston rod on the other hand, so that the ends of the circumferential wall are Accordingly, they can approach and separate from each other.

In this feature of the invention, the sealing circumferential wall of the header space is fixed on the one hand to the piston cylinder and on the other hand to the piston rod.

Completely sealed at both axial ends. The absence of relative movement between the rigid jacket and the cylinder and between the jacket and the piston rod ensures an inherently more reliable seal than in designs with gland seals between the jacket and both cylinder elements. 6 Seal efficiency can also be maintained at a constant high level during the service life of the load, as long as the attachment points between the peripheral wall and the cylinder and between the seal and the piston rod do not wear out. During actuation of the piston rod, the end of the circumferential wall is dragged along with it, if possible, by the above-mentioned telescopic or elastic section running in the circumferential direction of the circumferential wall.

According to a further development of the invention, the device is configured in such a way that when the piston rod extends and retracts in and out of the cylinder, the volume of the header space is alternately increased and decreased, producing a pumping effect.

Like a pump, this action, with alternating increases and decreases in header space volume, causes a contraction movement of the circumferential wall to expel leakage fluid that has accumulated in the header space through the discharge openings and ducts. This ensures that the header space is always cleaned, even when the piston-cylinder arrangement is operated at relatively low pressures6. It can take the form of a tube with circumferentially arranged folds. Also.

It is also possible to make the entire circumferential wall bellows-shaped.

Furthermore, the bellows-like portion of the circumferential wall can be composed of a material with elastomeric properties, ie a material with the elasticity of rubber.

Due to these features, the manufacturing costs of the peripheral wall are low and the wear of its flexible parts is low.

It is also possible for the bellows-shaped portion of the circumferential wall to be arranged continuously in the axial direction and constituted by a deformable, in particular metallic, annular element. This element is brought into close contact with its inner and outer diameters by means of soldering, brazing, welding, gluing, etc. suitable for forming the bellows. The annular element may be symmetrically interconnected in the shape of a bell or a cup with respect to the plane passing through its close portion.

This bellows configuration is particularly robust.

The circumferential wall can also be connected directly to an end cup having a piston rod passing therethrough as an axial extension, the outer diameter of the circumferential wall being generally equal to the diameter of the cap or cylinder body.

This allows for a compact arrangement according to the invention, which has the advantage of being exactly the same as the longitudinal dimensions of similar prior art devices.

A structure having a flexible or elastic longitudinal part, in particular a bellows-type peripheral wall closely fixed to the piston rod, adjacent to the end of the peripheral wall adjacent to the piston rod, has its axial end adjacent to the cylinder. are spaced and secured to a rigid sleeve-like longitudinal portion of the peripheral wall surrounding the piston rod.

This sleeve-like extension is closely fixed to the cylinder with its end cap having five penetrating piston rods.

This construction represents a particularly ingenious design of the peripheral wall, and at the same time provides a simple and reliable assembly.

The bellows portion may be releasably fastened to the axially articulated element and may include an annular ring at one or both of its axial ends for fitting into a suitable annular retaining groove on the sleeve element or section. Preferably, a retention bead is provided.

This makes the hermetic connection between the jacket wall and the cylinder or cylinder body particularly simple.

The ventilation openings are formed in the rigid part of the circumferential wall, in particular in its sleeve-like part.

As a result, even conventional piston/cylinder devices with old designs can be installed with the sealing device of the present invention.
can be improved without much problem.

(Example) FIG. 1 showing an embodiment of the piston/cylinder device according to the present invention shows the right axial end (
5), the cylinder body (6) is partially shown. Both ends of cylinder JAN (6) are covered with cylinder end caps (7).
(only one of which is shown). Inside this shell there is an axially sliding piston (8) connected to one axial end of a coaxial piston rod (9).
This is indicated by the dashed line.

The piston rod passes through the cylinder end cap (7) at an opening (10) and extends axially within a support bushing (14) mounted within the opening (lO). In addition, the opening (1
Since the rod/packing ring (15) is also installed in the inside of the bushing (15), the packing is attached to the bushing (15) when viewed from the piston.
4), while on the other side opposite the bushing (14) there is a wiper ring (16).

Both rings (15) (16) are the piston rod (9)
A 60-metre seal ring (15) surrounding and fitting closes the cylinder space (17) between the piston (8) and the cylinder end cap (7) from the outside, and
The wiper ring (16) prevents dust on the piston rod (9) from entering the cylinder.

There is a feed opening (18) extending into the cylinder interior through the cylinder end cap (7). This opening can be connected to a pressure line for supplying and discharging pressurized drive fluid.

At the left end of the cylinder, there is a supply port that connects to the second cylinder space, and includes a piston (8) and a piston rod (9).
) can reciprocate in the longitudinal direction of the cylinder body by supplying and discharging fluid.

In this example of the invention, only the piston rod extends through one of the cylinder end caps.

However, the invention is not limited to this example and is fully applicable to systems with piston rods passing through two cylinder end caps. In such case, there is an arrangement similar to that described above, as well as at the opposite end of the cylinder (not shown).

The upper piston-cylinder arrangement is intended for use in industrial cleanrooms for experiments or other operations that require a very strictly pure environment.

However, the rod/seal ring (15) and the wiper ring (16) are used as rings, and the cylinder (17) is directly surrounding or in the space (20) of the piston/cylinder device.
100% sealing is not guaranteed.

Every time a very small leak occurs between the seal and the piston rod, it leaks into the clean room.

External leakage is particularly troublesome when air is the fluid used to operate the piston-cylinder arrangement, where material deposited on the piston rod causes contamination.

This is because air generally contaminates the lubricant, such as oil, which is ejected into the space (20) and accumulates in the immediate vicinity of the piston-cylinder arrangement, causing trouble.

For this purpose, the cylinder end (21) and the cylinder end cap (7) with the piston rod passing therethrough are fitted with an external sealing device t (22), whereby the opening (10)
The space (20) surrounding the piston-cylinder arrangement is kept completely dust-free by trapping and collecting the leaking air passing through.

Next, this sealing device will be explained in detail.

The sealing device (22) comprises an airtight peripheral wall (23) which surrounds, with play, the entire length of the longitudinal part of the piston rod section (24) which projects through the piston-cylinder device (5) via the end cap (7). Equipped with. This peripheral wall (23) is connected at one axial end (25) thereof adjacent to the cylinder to the cylinder end cap (7) and at its other axial end (26) adjacent to the piston rod. and sealing mate.

It therefore forms an axial extension from the cylinder end cap (7) and circumvents the piston-cylinder arrangement (2).
annular header space (29) completely sealed from
is obtained. The header space can receive leakage fluid through the opening (10).

Header space (29) via outlet (30).

Discharge duct (31) in the form of a pipe or flexible conduit (31)
The free end (32) of the 6 discharge duct (31) is connected to the space (33), i.e. the cylinder device (5)
An external environment separated from the space (20) in which the
That is, it is installed so that it opens into the clean room. The flexible conduit (31) is therefore attached to the support bulkhead (34), as can be seen in FIG.

Air and dust trapped in the header space (29) can thus be led out of the exhaust duct (32) without escaping into the clean room. Moreover, for that purpose,
No special evacuation devices or pumps are required, and the leakage air can be reliably disposed of simply by the presence of a pressure gradient between spaces (29) and (33).

In addition, although no particular embodiment is listed, a completely rigid peripheral wall is provided, and a gland surrounding the piston rod portion (24) seals between one peripheral wall and the rond in the end portion (26), and the rond portion (24) is sealed. , it is also possible to make it possible to slide there.

However, such seals wear over time and a perfect seal can only be ensured by frequent replacement of the seal ring forming the gland.

Therefore, during the service life of the device, in order to obtain a perfect sealing effect, one circumferential wall (23) is installed between the cylinder and the piston rod, as shown in FIG.

The end (26) of the circumferential wall adjacent to the piston rod is also fixed to the piston rod portion (24), an arrangement that precludes relative movement between the parts.

Such static seals are easily obtained and, since there is no relative movement at the seal interface, the header space (
29) can be completely sealed from the immediate surroundings or space (20).

This design of the invention provides that during actuation of the piston-cylinder arrangement (5), the end (26) is connected to the piston rod (19).
It means to move back and forth in the axial direction.

One circumferential wall (23) can therefore extend along a longitudinal section along the wall, i.e. surrounding the piston rod (9) in the longitudinal direction. That is, the circumference j7i1 (23) has flexibility.

This part is best made of a material with elastomeric properties, but this is not essential.

As a result, while ensuring the sealing of the header space (29), both ends (25) and (26) of the peripheral wall (23) move toward and away from each other when the piston rod enters and exits the cylinder device (5). Therefore, the volume of the header space increases or decreases. Therefore, one peripheral wall (23) has a section (
35) As long as it expands and contracts within, it performs a pumping motion.

This pumping action prevents any drive air from leaking into the header space (29), into the external environment or into the space (3).
Even if the pressure is low compared to the outlet (3), the leaked air will flow through the outlet (3).
0) and to the outside via the duct (32), so that there is no need to use a separate scavenging pump.

It is clear that the circumferential wall (23) in the longitudinal direction can include a number of flexible sections or be completely flexible.

In the embodiment shown in FIG. 1, the extendable and collapsible section (35) is in the form of a bellows (36). This bellows is
It is directly adjacent to the right end (z6) fixed to the piston rod (9) and has radial play between it and the piston rod (9).

This bellows section ends before the cylinder end cap (7), and its circular bellows end (37) extends from the sleeve (3).
9) adjacent the longitudinally rigid section (38) of the circumferential wall. This sleeve-like section (38) has a bellows (36
) in a hermetically connected manner (the peripheral wall (23) has two parts in the embodiment of the present invention).

Generally, the tubular sleeve (39) is arranged coaxially with the piston rod (9) and has a radial gap therebetween. Furthermore, the end remote from the bellows end (37) is attached to the cylinder end cap (7) by sealing fastening to a cylindrical extension (40) formed on the right side of the cylinder end cap (7).

This extension (40) extends in the longitudinal direction (19) towards the outer end (44) of the piston rod and coaxially surrounds it. The extension consists of the two rings (15) (16) mentioned above.
Also equipped.

The sleeve (39) is fitted with an extension (40), preferably by press-fitting.
) so that a gas-tight connection is obtained even in the absence of a sealing ring between the surface elements.

However, it goes without saying that there are other ways to attach the sleeve (39), for example by providing a radially projecting annular flange screwed onto the cylinder end cap (7) with a sealing ring in between.

The bellows (36) shown in FIG. 1 is entirely made of elastomer and is shaped into a bell shape from the beginning. The wall (45) is
Foldable or bendable in the longitudinal section, direction (1
9), the end (46) aligned with the radial plane has a central opening (47) for receiving the piston rod part (24). A sleeve-like end (26) is formed at the edge of the opening (47).

Fasten to the piston rod (9) with a band (48), preferably made of metal, crimped at the end (26). In this way, the bellows (36) is removably fixed to the piston rod (9) and therefore does not slide on the rod.

The bellows end (37) closest to the cylinder body (6) is also sleeve-shaped, and on its inner edge directed towards the piston rod (9) is a part of a reducing sleeve (39).
It has a peripheral bead (49) that fits into the peripheral groove (50). Therefore, even at maximum extension, the bellows slips (39)
It will not fall off.

The ends (37) of the bellows are also held with crimped rings (51) that ensure a positive sealing fit and fit.

The end (26) adjacent to the piston rod may be press-fitted into the piston rod (9), as shown in detail in FIG. In that case, the piston rod (9) has a peripheral groove (52
), and push the corresponding peripheral bead (53) at the end of the snake JIS [(36) into it and engage it.

The above-mentioned outlet (30) exits from the header space (29)
extends through the cylinder end cap (7) and at one outer end of the cylinder end cap and also into the header space (29).
) (not shown) may be opened at the other end.

However, the discharge port (30) is round '1! (23), which in the case of the design of FIG. 1 would be a sleeve-like section (38). Section (38
) extends axially for a portion of its length through an extension (40) towards the piston rod end (40) and has an outlet (40) therein.
30), preferably in the form of threaded holes aligned in the radial direction, into which a connecting threaded nipple is inserted and screwed to the flexible conduit (31).・The cylinder device also has the advantage of being able to be installed without requiring any deformation processing. Sealing equipment! Only (22) needs to be attached and tightened to the cylinder end cap.

In an alternative embodiment (not shown), the entire circumferential wall (23) is in the form of a bellows that is attached and sealed directly to the cylinder end cap as well as to the piston rod.

In all embodiments of the invention, one peripheral wall (23) is
It is directly connected by an axial extension to a cylinder end cap (7) having a penetrating piston rod (9), the outer diameter of the circumferential wall being substantially the same as the cylinder cap (7) and the cylinder body (6).
It is advantageous if it is equal to the outer diameter of

This results in a compact arrangement, so that at most the width of the piston-cylinder arrangement has to be increased somewhat. In this respect, it has the advantage that even older piston-cylinder devices without seals can be installed without taking up unnecessary volume of space.

FIG. 3 is a partial view of another type of bellows (36') used in the present invention, which consists of annular elements (54) (54') which are particularly elastic and are arranged successively in the axial direction (19). Both are alternately hermetically connected at their inner and outer edges (55) and (56), respectively. The connection is by soldering, brazing, welding or gluing, and the annular element is preferably made of metal.

Edges (55) and (56) have the divided welded parts in the third
It can be seen in the diagram. The welding may in particular be resistance welding or laser welding.

To ensure sufficient axial elasticity of the bellows (36'),
Preferably, another annular element is cup-shaped, with the key 1 of each pair (
54) (54') is its contact surface (57) (57'
) so that they are symmetrical to each other.

The bellows (36') shown in FIG.
9) If the gas escaping into the chamber is under high pressure, as occurs when the leakage through the opening (10) is large and the holes in the exhaust duct (32) are so small that the escaping gas cannot escape quickly at low pressure. is particularly advantageous. In this case, the bellows (36'), consisting of a metal element, is extremely strong and undamaged and does not undergo outward expansion or rupture.

Furthermore, the cylinder device (5) shown in FIG.
It is attached with a locking device (58) (not shown in detail).

However, the invention is not limited to piston-cylinder devices involving such devices.

[Brief explanation of drawings]

FIG. 1 is a partial longitudinal sectional view of a piston-cylinder arrangement with a sealing device according to the invention. FIG. 2 is an enlarged view of the connecting portion between the peripheral wall and the piston rod according to the present invention. FIG. 3 shows an advantageous form of the bellows. (5) Piston/cylinder device (6) Cylinder body (7)
Cylinder end cap (8) Piston (9) Piston rod (10) Opening (14) Support bushing (15) Rod ring (16) Wiper ring (18) Supply port (17) Cylinder
(22) Sealing device (23) Peripheral wall
(30) Discharge port (31) Discharge duct

Claims (20)

[Claims] (1) A first block that closes the cylinder body and both axial ends thereof.
a second end cap, a piston disposed within said cylinder body and slidable in the axial direction thereof, connected to said piston, a predetermined portion of its length passing through said first end cap, with a seal therebetween; an extensible piston rod, and a seal sealing around the piston on the outside of the cylinder body, the seal sealing between at least a portion of the piston rod outside the cylinder around its entire periphery. An airtight peripheral wall surrounding the piston rod with a radial clearance (one axial end of this peripheral wall is hermetically attached to the shell, and the opposite axial end is hermetically engaged with the piston rod). an annular header space between them) and a duct for discharging fluid from said header space into a receiving space. (2) The piston-cylinder device according to claim (1), wherein the receiving space is selected from the group including a space outside an enclosure with a peripheral wall, a receiving container, and outside air. (3) One end of the peripheral wall is fixed to the piston rod, and at least a portion of the length of the peripheral wall is expandable and retractable in the axial direction of the peripheral wall in the direction of movement of the piston rod, so that both ends of the peripheral wall (one side is and the other fixed to the piston rod) can approach and separate from each other when the piston rod extends from the shell and returns to the shell. The piston/cylinder device according to item (2). (4) The piston-cylinder device according to claim (3), wherein a longitudinal portion of the peripheral wall is flexible and has elastomeric properties. (5) The piston according to claim 3 or 4, wherein when the piston rod moves in and out of the cylinder body, the volume of the header space increases or decreases to produce pumping activity. cylinder device. (6) Any one of claims (3) to (5), wherein at least a portion of the length of the peripheral wall that allows the peripheral wall to expand and contract in the axial direction is bellows-shaped when the piston rod moves inside and outside the body. The piston/cylinder device described in . (7) Claim No. (3) in which the entire circumferential wall has a bellows shape.
The piston/cylinder device according to any one of items (6) to (6). (8) The piston-cylinder device according to claim (7), wherein the bellows is made of a material with elasticity similar to rubber. (9) Claim (7) wherein the bellows consists of annular elements whose inner and outer edges are alternately sealed and connected by a connection method selected from soldering, brazing, welding, gluing, etc.
The piston/cylinder device according to item (8) or item (8). (10) The piston-cylinder device according to claim (9), wherein the annular element that forms the bellows by connection is made of an elastic metal material. (11) The annular elements are arranged in pairs in a bell-shaped configuration, such that the members of each pair are symmetrical with respect to a plane passing through the joint joining the members to each other. The piston/cylinder device described in . (12) Claims (1) to (1) in which the peripheral wall, as an axial extension thereof, directly adjoins the first end cap.
11) The piston/cylinder device according to any one of items 11). (13) The piston and cylinder device according to claim (12), wherein the peripheral wall has a diameter equal to the diameter of the first end cap and the barrel. (14) Claims (1) to (13) include a rigid sleeve having play adjacent to the first end cap and surrounding the piston rod that is sealingly coupled to one end of the shell and peripheral wall. The piston/cylinder device according to any one of the above. (15) The piston and cylinder device of claim (14), wherein the sleeve is connected to the barrel by a first end cap. (16) The piston/cylinder device according to claim (14), wherein the end of the peripheral wall and the joint between the piston rod and the body are removable. (17) A piston-cylinder device according to claim (16), wherein at least one of the couplings comprises a retaining bead on the circumferential wall and means for defining an annular groove receiving the bead. (18) The piston and cylinder device of claim (14), wherein the coupling is press-fitted into a male portion of the first end cap that extends into the sleeve. (19) The piston-cylinder device according to claim (1), wherein the duct has an opening in the first end cap. (20) The piston according to claim (14), wherein the duct has a radial opening extending through the sleeve.
cylinder device.