EP2455620A1 - Fluid operated linear motor with cushioning means - Google Patents

Abstract

The drive (1) has a drive unit (14) comprising a drive piston (12), and an end position damping device (35) comprising a locking unit with a sealing lip (45). The damping device has a throttle channel (52) that provides a fluid connection between a working chamber (22) and a control channel (28). The locking unit has base and side walls (42, 43). The side wall is locally broken for forming the throttle channel, and forms a supporting section (55) that encloses an inner area that is opened on a front side turned away from the piston. A throttle channel aperture runs into the inner area.

Description

The invention relates to a fluid - operated linear drive, with a housing and a linearly displaceable in this regard by Fluidiebeaufschlagung drive unit, wherein the drive unit has a arranged inside the housing and there two working chambers from each other dividing drive piston, which during an attenuation phase when approaching a first end wall of the opposite Housing is braked by a Endlagendämpfungseinrichtung the linear drive, wherein the Endlagendämpfungseinrichtung one on the first end wall facing side of the drive piston arranged on the drive unit closure member having an annular sealing lip, which arranged on the first end wall control channel mouth of a controlled fluid loading between the drive piston and the first end wall arranged arranged first working chamber control channel, in which the closure member currency during the damping phase so that the sealing lip sealingly cooperates with the wall of the control channel by means of a sealing surface, and wherein the end position damping device further comprises at least one throttle channel, which provides a throttled fluid connection between the first working chamber and the control channel during the damping phase.

Such a linear drive is in the EP 2 047 116 B1 described in connection with the figure 9 there. The known linear drive includes a drive piston and a piston rod having a drive unit, wherein the drive piston in a housing divides two working chambers from each other, each communicating with a frontally opening control channel. The linear drive is equipped with two responsible for one of the two possible stroke directions of the drive unit Endlagendämpfungseinrichtungen, each having a drive piston upstream of the sealing ring with radially projecting sealing lip. When the drive unit approaches one of its two stroke end positions, the closure member dips into the control channel opposite it and closes it. This begins a damping phase, during which the previously displaced by the drive piston through the control channel through pressure medium can flow only through a throttle channel smaller cross section through which is formed in the case of the known linear drive of a plurality formed in the wall of the flow channel longitudinal grooves. Due to the resulting reduction of the pressure medium available Abströmquerschnittes, a back pressure builds up in the downstream working chamber, which leads to a slowing down of the drive unit and thus to a muffled impact of the same when reaching the Hubendlage. Although the known linear drive provides effective cushioning, it appears to be in need of improvement in terms of manufacturing cost. The realization of the throttle channel defining longitudinal grooves need for their production a relatively large technological effort.

A working in relation to the end position damping according to a similar principle linear drive is also from the DE 10 2009 014 817 A1 known. There is mentioned that the throttle channel may alternatively be integrated into the wall of the housing of the linear drive.

The DE 102 61 412 A1 describes a pneumatic cylinder with damping means, in which the drive piston itself acts as a means to limit the outflow cross section for the displaced pressure medium. The throttle channel is integrated in this case in the piston body of the drive piston.

At one of the US 2,642,845 known linear actuator includes the Endlagendämpfungseinrichtung a balgähnlich designed, axially compressible damping element, which rests under fluid-tight shutting off a control channel to the front side of a cover of the housing when the drive unit approaches the Hubendlage. The throttle channel is again formed in the housing of the linear drive in this design.

According to a comparable principle, the end position damping device of the works from EP 1 041 293 A2 known pneumatic cylinder. As a member for closing the downstream control passage, a relatively displaceable relative to the drive piston sealing ring is provided here, which is resiliently biased.

It is the object of the present invention to provide a fluid-actuated linear drive with a simple and inexpensive to implement end position damping device.

To achieve this object, the invention provides that the at least one throttle channel is formed in the closure member and thereby penetrates the closure member such that he - viewed in the damping phase - bypassing the cooperating with the wall of the control channel sealing surface of the sealing lip opens on the one hand with a first throttle channel mouth into the first working chamber and on the other hand with a second throttle channel mouth into the control channel.

In this way, the throttle channel is an immediate part of the sealing lip also having the closure member. The production measures for realizing the sealing lip and the throttle channel are thus concentrated on a single component, namely the closure body, which allows a rational production. Since on the housing side can be dispensed with a throttle channel to ensure the damping function, the invention favors the retrofitting of existing linear actuators and makes it possible to use for the production of equipped with or without Endlagendämpfungseinrichtung linear actuators on a cost-producible, throttle-less housing. Since the closure element according to the invention can be realized with very small length dimensions despite the multiple function combined in it, inter alia sealing function and throttling function, linear drives equipped therewith can have very compact dimensions if required.

In the linear drive according to the invention, the slowing down of the lifting movement of the drive unit initiating damping phase begins with the entry of the sealing lip of the axially fixed immovably fixed to the drive unit closure member in the opposite control channel mouth. The control channel is shut off in this way and separated from the working chamber upstream it. However, this separation is not hermetically sealed, but leaves a throttled fluid flow through the closure member passing through at least one throttle channel through. Thus, a throttled bypass flow can form, which bypasses the effective sealing surface of the sealing lip and expediently the sealing lip in its entirety. Depending on the size of the selected cross section of the throttle channel, the throttling intensity and thus the attenuation intensity can be specified as required. Although it is usually sufficient to provide only a single, appropriately sized throttle channel, the closure member could also be equipped with a plurality of functionally parallel throttle channels.

Advantageous developments of the invention will become apparent from the dependent claims.

The closure member is expediently formed separately with respect to the drive unit, wherein it can be releasably or permanently fixed to the drive unit.

The throttle channel is suitably formed in the closure member such that it passes next to the sealing lip, so this does not interspersed. This favors the life of the sealing lip, which usually undergoes a radial deformation, in particular by elastically reversible bending when alternately entering and leaving the control channel.

The closure body is expediently provided with a support section which carries the radially projecting sealing lip in this respect. Between these two components is expediently a cohesive connection, which can be produced efficiently and which promises a secure connection.

If the closure body is provided with a support section having the sealing lip, the throttle passage expediently extends exclusively in the support section. The throttle channel may have a linear course or an angular course. The straightforward design is particularly easy to implement.

Preferably, the support portion is annular, in particular, a sleeve shape is recommended, so a design with in relation to the axial length of low wall thickness. The sealing lip is arranged in this case preferably in the region of the drive piston opposite axial end face of the support portion. The annular support section is in particular placed coaxially with respect to the drive piston.

With its annular support section, the closure member expediently encloses an interior which is open on the drive piston axially opposite side. To the drive piston out of this interior is closed, either by a corresponding design of the closure body itself or by the drive unit. Both closure measures can also be combined.

Especially in connection with the aforementioned measure, it is advantageous if the throttle passage penetrates the closure body in such a way that its first throttle passage opening is arranged on the side of the sealing lip facing the drive piston on the outer circumferential surface of the carrier section and the second throttle channel mouth is located on the inner circumferential surface of the carrier section , In this way, during the damping phase, the throttled fluid flow can pass through the wall of the support section and over that of the support section flowed over the interior from the first working chamber into the control channel.

Particularly simple can be realized a throttle channel, which passes through the wall or the annular body of the annular support portion radially.

Regardless of the course of the throttle channel, it is in any case advantageous if both throttle channel mouths are arranged on the drive piston side facing a root portion of the sealing lip, with which the sealing lip is fixed to the support portion.

The interior space enclosed by the annular support section is preferably an annular space. This annulus results from the fact that in the support portion, preferably coaxially, protrudes axially projecting from the drive piston extension of the drive unit, which can pass through the entire closure member axially and on the drive piston opposite axial side can also protrude from the closure member.

If the drive unit is provided with a piston rod protruding from the housing, this piston rod can directly form the aforementioned extension itself. In this case, the closure member is installed on that side of the drive piston on which the piston rod is located.

The drive unit may have a drive piston mounted on the rear side of the piston rod, a fastening device being arranged on the axial side of the drive piston opposite the piston rod, which fastening device serves to fix the drive piston to the piston rod. This fastening device For example, may include a threaded extension of the piston rod passing through the drive piston and a fastening nut screwed onto this threaded extension. If the closure member is arranged on the same side as the fastening device on the drive piston, the fastening device can protrude into the annular support section to form said extension.

By thus resulting axial overlap or nesting of the annular support portion and the projecting from the drive piston extension, the closure member can be integrated in a manner in the drive unit that selbige claimed despite equipment with a Endlagendämpfungseinrichtung no longer axial installation space within the linear drive as without Endlagendämpfungseinrichtung ,

The support section carrying the sealing lip is preferably a component of a fastening body of the closure member, with the aid of which the closure member on the drive unit is preferably detachably fixed or fixable.

The fastening body is suitably of annular shape. In particular, it can have a disc-shaped, centrally perforated attachment section, to which the support section adjoins coaxially on one side, so that a pot-like structure results. With the help of the attachment portion, the closure member can be fixed to the drive unit, for example, by being plugged by means of its central hole on the piston rod and is clamped between the drive piston and either the piston rod or a fastener.

It is advantageous if the closure member is designed overall pot-shaped and has a suitably perforated bottom wall and a sleeve-like designed, the sealing lip-bearing side wall. The side wall forms the support section and the bottom wall the attachment section. The side wall is expediently locally broken to form the at least one throttle channel.

An advantageous construction of the closure member provides that it has a support body made of a rigid material, on which the sealing lip is integrally formed, in particular in the context of a two-component injection molding. The support body consists for example of a deep-drawn metal part, which may be encapsulated with the sealing lip-forming elastomeric plastic material. In order to ensure a secure hold for the sealing lip in spite of the stress occurring during operation, the support body may have a radially projecting support projection which engages behind the sealing lip in a root area of the same.

The linear drive according to the invention can be equipped with only one or with two end position damping devices. If an end position damping is to be realized only in one direction of movement of the drive unit, a single end position damping device is sufficient. For damping in both directions of movement of the linear drive is equipped with two Endlagendämpfungseinrichtungen, which expediently have identically designed closure members.

Figur 1

eine vorteilhafte Bauform des erfindungsgemäßen Linearantriebes im Längsschnitt bei Einnahme einer eingefahrenen Hubendlage der Antriebseinheit,

Figur 2

den Linearantrieb aus Figur 1 im Längsschnitt, wobei die Antriebseinheit eine ausgefahrene zweite Hubendlage einnimmt,

Figur 3

die bei dem Linearantrieb der Figuren 1 und 2 eingesetzte Antriebseinheit in einer isometrischen Einzeldarstellung,

Figur 4

das bei der Anordnung gemäß Figuren 1 bis 3 verwendete Verschlussglied in einer isometrischen Einzeldarstellung von der Vorderseite her gesehen,

Figur 5

das Verschlussglied aus Figur 4 in einer isometrischen Rückansicht, und

Figur 6

einen Längsschnitt durch das Verschlussglied gemäß Schnittlinie VI-VI aus Figur 5.

The invention will be explained in more detail with reference to the accompanying drawings. In this show:

FIG. 1

an advantageous design of the linear drive according to the invention in longitudinal section when taking a retracted stroke end position of the drive unit,

FIG. 2

off the linear drive FIG. 1 in longitudinal section, wherein the drive unit occupies an extended second stroke end position,

FIG. 3

in the linear drive of FIGS. 1 and 2 used drive unit in an isometric single view,

FIG. 4

in the arrangement according to FIGS. 1 to 3 used closure member in a single isometric view of the front seen

FIG. 5

the closure member FIG. 4 in an isometric back view, and

FIG. 6

a longitudinal section through the closure member according to section line VI-VI FIG. 5 ,

The designated in its entirety by reference numeral 1 fluid-actuated linear actuator is designed in particular for actuation by means of compressed air or another compressed gas, but can also be operated with a liquid pressure medium.

The interior of the housing 2 is an interior space 4, which is the end face of a first end wall 5 and a second longitudinal wall 3 spaced therefrom in the axial direction of the second end wall 6 of the housing 2 is closed , Between the two end walls 5, 6 extends a tubular body 7 of the housing 2, the inner surface of which forms a piston running surface 8 for a drive piston 12 arranged in the interior 4.

The end walls 5,6 are suitably designed as a lid, which are attached under sealing to the two end faces of the tubular body 7.

Each end wall 5, 6 has an inner wall surface 13 facing the drive piston 2, which acts as an abutment surface for the drive piston 12 by way of example in order to specify two possible stroke end positions of the drive piston 12. Alternatively, the inner wall surfaces 13 could also be preceded by a buffer element for forming the stop surface.

The drive piston 12 is part of a in the axial direction of the longitudinal axis 3 veschiebbaren relative to the housing 2 drive unit 14. This includes by way of example also a piston rod 15, which is combined with the drive piston 12 to form an assembly. The piston rod 15 protrudes from the drive piston 12 at the end face facing the second end wall 6 and passes through a wall opening 16 formed in the second end wall 6 at sealing. At 17, the piston rod 15 is fixed under the wall opening 16 at the second end wall 6 Seal enclosing sealing ring 17 shown. Outside the housing 2, the piston rod 15 has a Kraftabgriffsabschnitt 18, to which a component to be moved can be fastened in a particularly releasable manner.

By linear displacement, the drive unit 14 between a FIG. 1 apparent first stroke end position and one out FIG. 2 apparent second stroke end position to be moved. The first stroke end position can also be referred to as a retracted stroke end position, because here the drive unit 14 as far as possible is retracted into the housing 2. This retracted, first stroke end position 1 is defined by the fact that the drive piston 12 bears against the inner wall surface 13 of the first end wall 5.

The second stroke end position according to FIG. 2 can also be referred to as extended stroke end position, because here the drive unit 14 is extended as far as possible from the housing 2. This extended second stroke end position is defined by the fact that the drive unit 14 with its drive piston 12 comes into contact with the inner wall surface 13 of the second end wall 6.

The drive piston 12 divides the inner space 4 into a first working chamber 22 located on the side of the first end wall 5 and a second working chamber 23 located on the side of the second end wall 6. The subdivision is expediently fluid-tight, for which purpose the drive piston 12 in the region of its outer circumference carries an annular seal assembly 24 which bears dynamically sealingly against the piston tread 8. In order to obtain a high-quality linear guide, the drive piston 12 can also carry at least one guide ring 25 bearing on the piston running surface 8 at its outer circumference.

The sealing arrangement 24 expediently also functions as a buffer device which reduces the impact of the drive piston 12 in the stroke end positions. It has for this purpose one or more axially projecting rubber elastic buffer projections 26, with which the drive piston 12 comes into abutment in the Hubendlagen on the inner wall surfaces 13. These buffer projections 26 may also be formed independently of the sealing arrangement 24. In addition, these buffer projections 26 could also be located on end walls 5, 6.

To cause a linear lifting movement 27 of the drive unit 14, the two working chambers 22, 23 are controlled in a coordinated manner with a fluidic pressure medium to be applied. This controlled pressurization takes place by means of a first control channel 28 communicating with the first working chamber 22 and a second control channel 29 communicating with the second working chamber 23. On the other hand, both control channels 28, 29 open with a respective connection opening 32 to an outer surface of the housing 2. At each connection opening 32, a valve device, not shown, can be connected via a fluid line, which is switched into the connection to a pressure source and which is capable of selectively through the respective associated control channel 28, 29 through a pressure medium into the respectively connected working chamber 22, 23 feed or remove from this.

The control channels 28, 29 pass through the wall of the housing 2. Expediently, the first control channel 28 extends exclusively in the first end wall 5 and the second control channel 29 extends exclusively in the second end wall 6.

Each control channel 28, 29 opens via an inner control channel mouth 33 in the associated working chamber 22, 23 a. The inner control channel mouth 33 is located for the first working chamber 22 at the first end wall 5 and for the second working chamber 23 at the second end wall 6. Each inner control port mouth 33 is the drive piston 12 coaxially opposite. For this purpose, it is arranged, for example, centerline on the associated inner wall surface 13.

In the course of one or both control channels 28, 29, a flow restricting cross section 34 may be turned on, the specifies the maximum possible flow rate of pressure medium. This allows a limitation of the stroke speed of the drive piston 12 to a desired level.

In order to operate the drive unit 14, if necessary, with very high lifting speeds, the linear drive 1 is equipped with at least one end position damping device. By way of example, a double equipment is provided, namely with a first end-position damping device 35 for damping to achieve the first end-of-travel position and a second end-position damping device 36 for damping upon reaching the second end-of-travel position. The two end position damping devices 35, 36 are preferably designed mirror-inverted, so that the further description is based primarily on the first end position damping device 35. The relevant statements also apply accordingly to the second end-position damping device 36, unless otherwise specified.

If an end position damping is to be effected only in a single stroke direction, one of the end position damping devices can also be dispensed with.

Each end position damper 35, 36 causes the lift speed of the drive unit 14 to decrease during the process between the two stroke end positions as the drive unit 14 approaches a stroke end position. The thereby effective phase of the end position damping device is referred to as damping phase. This damping phase is limited to one of the respective stroke end position immediately preceding portion of the maximum stroke of the drive unit 14th

The first end-position damping device 35 is operative when the drive unit 14, starting from the extended second end-of-travel position, approaches the first end wall 5 and thereby moves into the retracted first end-of-stroke position, executing a first stroke movement 27a entering in the exemplary embodiment. The second end-position damping device 36 is effective in the reverse stroke direction of the drive unit 14, that is, when the same approaching the second firing wall 6 under execution of a second stroke 27b to ultimately reach the extended second Hubendlage.

Each Endlagendämpfungseinrichtung 35, 36 has as an integral part of a closure member 37, which is a fixed to the drive unit 14 and in this respect in particular separate component. The FIGS. 4 to 6 show this closure member 37 in a single representation.

The closure member 37 of the first Endlagendämpfungseinrichtung 35 is located on the first end wall 5 facing side of the drive piston 12. The closure member 37 of the second Endlagendämpfungseinrichtung 36 lies on the opposite, the second end wall 6 facing side of the drive piston 12. In the embodiment of the drive piston 12 is thus axially Flanked on both sides by a respective closure member 37. Each closure member is a respect to the drive piston 12 and the optionally existing piston rod 15 independent component.

At this point it should be noted that the drive unit 14 can also have a so-called continuous piston rod, which completely penetrates the housing 2 in the axial direction and, unlike the embodiment, passes not only through the second end wall 6 but also through the first end wall 5. Likewise, the linear drive 1 also be of the rodless type and have an externally arranged on the housing 2 Kraftabgriffsteil, which is without movement of the piston rod and, for example, purely magnetic or by means of a longitudinal slot of the tubular body 7 penetrating driver with the drive piston 12 is coupled.

In the particularly advantageous design of the embodiment, the closure member 37 is at least substantially cup-shaped. It has in this case a provided in the central region with a through hole 38 and thus perforated bottom wall 42, which preferably has the shape of an annular disc. In addition, it has a sleeve-like side wall 43 which is arranged coaxially with the bottom wall 42 and adjoins the outer edge of the bottom wall 42, from where it protrudes in the axial direction of the longitudinal axis 44 in one direction from the bottom wall 42.

The closure member 37 also has a concentric with the longitudinal axis 44 annular sealing lip 45 which is disposed on the side wall 43, and suitably on the bottom wall 42 axially opposite end portion of the side wall 43. The sealing lip 45 is arranged and formed so that it protrudes radially outward from the side wall 43, but expediently with a superimposed axial component. Accordingly, the sealing lip 45, starting from a radially inner root region 46, with which it is arranged on the side wall 43, via a radially outward and at the same time axially backward toward the bottom wall 42 oriented oblique course, finally to a root area 46 opposite free outer end portion 47 to end, which has a radially outwardly facing, to the longitudinal axis 44 concentrically annular sealing surface 48.

Consequently, the radial distance between the sealing lip 45 and the side wall 43, starting from the root region 46, increases toward the outer end region 47.

The sealing lip 45 is elastically reversibly deformable in the radial direction. It can thus be bent radially inwards in the direction of the side wall 43 and returns after removal of a corresponding force automatically back into the maximum distance of the side wall 43 spread back home position.

As a further special feature, the closure member 38 is provided with a fluid passage acting as throttle passage 52. In principle, the closure member 37 may be equipped with a plurality of such throttle channels 52, but it has in the embodiment of only a single such throttle channel 52. This throttle channel 52 is located conveniently in the side wall 43 which is broken to realize the throttle channel 52 locally in the radial direction. Regardless, however, in which region of the closure member 37 of the throttle channel 52 is placed, the throttle channel 52 is in any case a component of the closure member 37 and formed in the closure member 37, wherein it passes through the closure member 37.

The structure composed of the bottom wall 42 and the side wall 43 on the one hand serves for fastening the closure member 37 to the drive unit 14 and on the other hand assumes a shut-off function to be explained during the damping phase. In the following, therefore, this structure will also be referred to as shut-off and fastening body 54.

Within the shut-off and fastening body 54, the side wall 43 forms a supporting portion 55 carrying the sealing lip 45 and the bottom wall 42 mainly for attachment Since the support section 55 also assumes a shut-off function during the damping phase in the exemplary embodiment, it can also be referred to as the shut-off section. In other words, the side wall 43 in the embodiment advantageously acts as a combined shut-off and support section.

Accordingly, in the depicted preferred design of the closure member 37 results in a constellation in which an annular and preferably sleeve-like support portion 55 is provided, on whose the attachment portion 56 axially opposite end portion or end face, the sealing lip 45 is fixed with its root portion 46.

Each closure member 37 is mounted to the drive unit 14 in coaxial alignment. The longitudinal axes 44 of the closure members 37 thus coincide with the longitudinal axis 3. The closure members 37 are aligned so that their bottom wall 42, so therefore the back of the closure member 37, the drive piston 12 faces. The bottom wall 42 axially opposite front end portion 57 of the closure member 37 has axially away from the drive piston 12. In this way, the front end portion 57 of the closure member 37 of the first end-position cushioning device 35 faces the first end wall 5, and the front end portion 57 of the closure member 37 of the second end-position cushioning device 36 projects toward the second end wall 6.

Due to this arrangement, it follows that each sealing lip 45 is disposed upstream of the drive piston 12 at an axial distance. The "pot openings" of the cup-shaped closure members 37 are each away from the drive piston 12. Preferably, the closure members 37 are mounted so that they rest with the sealing lip 45 axially facing away from the rear surface 58 of its bottom wall 52 and its attachment portion 56 on the respectively facing end face 62 of the drive piston 12.

Due to the existing passage opening 38, the closure members 37 can be attached during assembly to the piston rod 15 and axially immovable clamp between the piston rod 15 and the drive piston 12.

The piston rod 15 is expediently stepped in its longitudinal direction and has a arranged in the interior 4 rod end portion 63, which is followed in the direction of the Kraftabgriffsabschnitt 18 via an annular step 65, a rod main section 64 of larger diameter. The annular step 65 forms a rod end portion 63 facing annular contact surface 65a.

The two closure members 37 and the drive piston 12 are attached to the rod end portion 63, said rod end portion 63, the through holes 38 of the closure members 37 and also passes through a central opening 66 of the drive piston 12. In this case, the closure member 37 of the second Endlagendämpfungseinrichtung 36 with the rear surface 58 axially opposite front surface of the mounting portion 56 on the contact surface 65a of the annular step 65 and it also support both closure members 37 with their back surfaces 58 on the opposite end faces 62 of the drive piston 12 from , These abovementioned components are clamped to the piston rod 15 by a fastening device 67 which, in the manner of an extension, starting from the drive piston 12, is coaxial in the locking device 37 of the first end position damping device 35 enclosed interior 68 protrudes. In the exemplary embodiment, the fastening device 67 includes a threaded section 72 formed by a longitudinal section of the rod end section 63 and provided with an external thread and a fastening nut 73 screwed onto the threaded section 72. Optionally, at least one washer 74 can also be provided between the fastening nut 73 and the fastening section 56 of the closure element 37 be arranged.

The fastening nut 73 is sufficiently tightened to cause the two attachment portions 56, together with the drive piston 12, to be clamped between the abutment surface 65a of the annular step 65 and the attachment nut 73 in an axially immovable manner with respect to the piston rod 15.

Characterized in that the fastening means 67 projects into the interior of the closure member 37, the support portion 55 has a larger inner diameter than the outer diameter of the fastening means 67, results in a radially concentric between the support portion 55 and the fastening means 67 lying annular space 75, which is to the Drive piston 12 axially opposite side is open.

A corresponding annular space 75 is located concentrically between the support portion 55 of the closure member 37 of the second end-position damping device 36 and the rod main portion 64 of the piston rod 15 coaxially passing through this closure member 37.

In summary, it can be said that both the fastening device 67 and the rod main section 64 are each form an extension which projects into the interior 68 of the associated closure member 37, so that the mentioned annular space 75 results.

Through the throttle passage 52 therethrough, a permanent fluid connection between the annular space 75 and the lying radially outside of the closure member 37 portion of that working chamber 22, 23, in which the closure member 37 is arranged. The throttle channel 52 has a first throttle channel orifice 76, which is located on the outer circumference of the side wall 43 and the support portion 55 by way of example, and a second throttle channel orifice 77, which is arranged on the inner surface of the shut-off and fastening body 54 and preferably on the inner circumference of the side wall 43 and ., Of the support portion 55 is located. Preferably, the throttle channel extends exclusively in the support portion 55, wherein it expediently passes through the annular body of this support portion 55 in respect of the longitudinal axis 44 radial direction.

The first throttle channel opening 76 is located on the outer circumference of the support portion 55 axially between the drive piston 12 and the root portion 46 of the sealing lip 45. Expediently, both throttle channel mouths 76, 77 lie on the drive piston 12 side facing this root region 46. Regardless of the configuration of the closure member 37 is advantageous if the throttle channel 52 does not pass through the sealing lip 45, but the sealing lip 45 is bypassed by the throttle channel 52 in its entirety. It can also be said that the throttle channel 52 is arranged next to or outside the sealing lip 45 in the closure member 37.

The already mentioned damping phase begins when, during a stroke movement 27, the drive piston 12 axially leading sealing lip 45 by coaxial with her opposite inner control channel mouth 33 passes through into the associated control channel 28, 29. This immersion is associated with the fact that the sealing lip 45 comes with its annular sealing surface 48 in sealing contact with the peripheral wall 78 of the respective control channel 28, 29 and slides while maintaining this sealing contact on this peripheral wall 78 in the axial direction of the longitudinal axis 3.

The sealing lip 45 is in particular designed so that its diameter in the region of the sealing surface 48 as long as the sealing lip 45 assumes its basic position outside the control channel 28, 29, is greater than the inner diameter of the control channel 28, 29 in the region of preferably formed without grooves peripheral Wall 78. This has the consequence that the sealing lip 45 when retracted into a control channel 28, 29 is acted upon radially on the outside of the peripheral wall 78 and concentrically deformed radially inward. This counterforce building up in this case leads to the sealing surface 48 being pressed against the peripheral wall 78 with sufficient sealing force.

A typical end position damping process runs in the linear drive of the embodiment in the manner explained below, it being assumed that the drive unit 14 initially in the off FIG. 2 apparent second Hubendlage is located.

In order to cause the drive unit 14 from the second stroke end position to its first stroke 27a, is ensured by corresponding actuation of the control channels 28, 29 connected valve device (s) that through the second control channel 29 through atmospheric pressure under pressure medium in the second working chamber 23 is fed while simultaneously the first working chamber 22 pressure moderately relieved or vented over the communication with her first control channel 28 away. Due to the pressure difference between the two working chambers 22, 23 forming in this case, the drive unit 14 moves in the direction of the first end wall 5 while carrying out the first lifting movement 27a; in the process, it moves into the housing 2. In this first stroke 27a pushes the drive piston 12 so far still in the first working chamber 22 befindliches pressure medium through the unobstructed control channel 28 through.

The consequence of this is that the drive unit 14 approaches the first end wall 5 at a relatively high nominal lifting speed.

However, before the drive piston 12 abuts against the inner wall surface 13 of the first end wall 5, the sealing lip 45 of the drive piston 12 vorseilenden closure member 37 of the first Endlagendämpfungseinrichtung 35 reaches the inner control port mouth 33 of the first control channel 28 and begins to submerge in the latter. This is the beginning of the already mentioned damping phase.

As soon as the sealing lip 45 is in sealing contact with the peripheral wall 78 of the longitudinal section adjoining the interior 4 in coaxial extension of the first control channel 28, the first control channel 28 is shut off from the first working chamber 22. As the sole connection between the first control channel 28 and the first working chamber 22, the throttle channel 52 remains. This has the consequence that the now displaced by the drive unit 14 from the first working chamber 22 pressure medium only a greatly reduced Ausströmquerschnitt is available, namely through the throttle channel 52 provided cross section. The episode this is the construction of a back pressure in the first working chamber 22, which exerts a braking force opposite the first stroke 27a on the drive unit, so that selbige now greatly slowed their movement continues until reaching the first stroke end position.

Starting from the second stroke end position which is now present, the drive unit 14 can be extended into the second stroke end position by feeding pressurized medium through positive control of the control channels 28, 29 into the first control channel 28 and the second working chamber 23 via the second control channel connected thereto 29 relieved of pressure. In this case, the closing member 37, which first still dips into the first control channel 28, moves out of the first control channel 28 again. However, a large-area fluid loading of the first end wall 5 facing side of the drive unit 14 is guaranteed from the outset, because the pressure medium is able to bend the sealing lip 45 radially inward and lift off the peripheral wall 78, so that adjusts an annular gap through which the pressure medium can flow past the sealing lip 45 into the first working chamber 22. The sealing lip 45 thus preferably also has a non-return function.

The above-mentioned shut-off function of the shut-off and fastening body 54 stems from the fact that it forms with its support portion 55 from dipping the sealing lip 45 into the control channel 28 a partition which separates the first working chamber 22 from the first control channel 28.

The throttled through the throttle passage 52 passing fluid flow passes from the first working chamber 22 initially in the space enclosed by the closure member 37 interior 68 and annular space 75 and from there axially into the adjoining first control channel 28.

During the damping phase, therefore, the annular space 75 of the closure element 37 currently involved in the cushioning is always fluidly connected via its open end side to the adjoining first or second control channel 28, 29.

From the described operation it is clear that the throttle channel 52 should be formed in the closure member 37, that in the damping phase, bypassing the cooperating with the peripheral wall 78 of a control channel 28, 29 sealing surface 48 on the one hand with its first throttle channel orifice 76 in the order the closure member 37 arranged around working chamber 22 and 23 opens and on the other hand, with the second throttle channel mouth 77 directly or indirectly opens to the associated control channel 28, 29 out. Indirect discharging here means, in particular, the design realized by way of example, in which the second throttle channel orifice 77 communicates directly with the annular space 75 and only through this annular space 75, with the adjoining control channel 28, 29.

In principle, however, a different course of the throttle channel 52 would be possible. In particular, it could run in such an angled manner within the annular body of the support section 55 that its second throttle channel orifice 77 lies on the end face of the support section 55 remote from the drive piston 12. However, realized in the embodiment design of a support portion 55 radially passing through throttle channel 52 is manufacturing technology much easier to implement.

When the drive unit 14 executes the extending second stroke 27b, an end position damping takes place in the same way as just described, as soon as the sealing lip 45 of the closure member 37 of the second end position damping device 36 advances into the inner control channel mouth 33 of the second control channel 29. This inner control channel orifice 33, unlike that of the first control channel 28, is not circular but ring-shaped because it is arranged concentrically around the piston rod 15 passing through the second end wall 6.

So that no undesired leakage currents can occur between a closure member 37 and the drive piston 12, the closure member 37 is expediently provided in the region of its rear side with an axially projecting sealing bead 79, which is concentric with respect to the longitudinal axis 44. The same is located in particular in the transition region between the bottom wall 42 and the side wall 43. In the clamped with the drive piston 12 state of the closure member 37 of the sealing bead 79 is pressed under sealing against the facing end face 62 of the drive piston 12. Alternatively, another type of sealing would be possible.

Advantageously, the closure member 37 consists of two cohesively interconnected components. One component is a support body 82 consisting of a rigid material, the other component is an elastomeric body 83, which is fastened to the support body 82 in a material-locking manner and which also includes the sealing lip 45.

The support body 82 consists for example of a hard plastic material or metal. Preferably, it may be made of steel by deep drawing. He has an example of a substantially cup-shaped shape with a to the bottom wall 42 belonging to disk portion 84 and a belonging to the support portion 55 sleeve portion 85. The bottom wall 42 of the closure member 37 is suitably formed solely by the centrally expediently perforated disc portion 84. The side wall 43 and the support portion 55 consists of the sleeve portion 85 of the support body 82 and a Hüllabschnitt 86 of the elastomer body 83, which expediently completely encloses or envelops the sleeve portion 85 at its radially outwardly oriented outer periphery. The sealing bead 79 is preferably also an integral part of the elastomer body 83.

The throttle channel 52 expediently passes through both the elastomer body 83 and the support body 82.

At the front end region 57 of the closure member 37, the elastomer body 83 has the integrated therein, obliquely radially outwardly and rearwardly projecting sealing lip 45. The root region 46 is expediently an integral part of the elastomer body 83.

The elastomer body 83 is expediently integrally formed by injection molding on the support body 82. This is expediently carried out in a two-component injection molding process in which the prefabricated support body 82 has been inserted into the injection mold before the casting process.

Preferably, the support body 82 has in the region of the sealing lip 45 via an annular projecting from the sleeve portion 85 radially outward annular support projection 87. This support projection 87 engages behind the sealing lip 45 on the drive piston 12 axially opposite side and thus acts in particular axial direction supporting the Sealing lip 45 a. In this way, increased security created in such a way that the elastomer body 83 does not detach from the support body 82 due to the frequent frictional contact between the sealing lip 45 and the wall 78 of the control channel 28, 29 or due to the acting buffer pressure.

Reducing wear in relation to the sealing lip 45 also has an effect when the end wall 5, 6 in the area of the control channel mouth 33 is rounded.

The above-described sealing bead 79 also prevents, among other things, that the back pressure or buffer pressure building up during the damping phase in the associated working chamber 22, 23 does not pass between the closure member 37 and the drive piston 12. This ensures a very high fatigue strength of the closure member 37.

Conveniently, the flow cross section available to the outflowing pressure medium during the damping phase is made available exclusively by the at least one throttle channel 52. It is expediently no further, outside the closure member 37 placed and formed, for example, in the wall of the housing 2 throttle channel available. Also, the drive unit 14 is expediently interspersed by no relevant for the end position damping throttle channel. Thus, the possibility is provided to provide linear drives 1 with or without end position damping device 35, 36 which are identical in construction and differ only in that at least one closure element 37 is installed or not.

The FIGS. 1 and 2 make it clear that by equipping the drive unit 14 with one or two closure members 37 neither the maximum stroke nor the length dimensions of the housing 2 change. Thus, the described damping measures are also ideal for retrofitting existing linear drives. In particular, so-called short-stroke cylinders, which have a relatively short stroke length, can advantageously be equipped with one or two end-position damping devices 35, 36.

In the closure member 37, at least three functions are expediently integrated, namely a shut-off function blocking off the associated control channel, a sealing function realized by means of the sealing lip 45 and finally the throttling function realized by the at least one throttle channel 52, wherein the outflowing pressure medium passes through the closure member 37 becomes. Thus formed results in only a small manufacturing and assembly costs.

Claims (17)

Fluid-actuated linear drive, comprising a housing (2) and a drive unit (14) which can be displaced linearly by applying fluid, wherein the drive unit (14) has a drive piston (12) arranged inside the housing (2) and separating therefrom two working chambers (22, 23) ) which is braked during a damping phase when approaching a first end wall (5) of the housing (2) lying opposite it by an end-position damping device (35) of the linear drive (1), wherein the end-position damping device (35) engages on the first end wall ( 5) facing side of the drive piston (12) on the drive unit (14) arranged closure member (37) having an annular sealing lip (45) having a at the first end wall (5) arranged control channel mouth (33) of a controlled fluid loading between the Drive piston (12) and the first end wall (5) arranged first working chamber (22) facing control channel (28), in which the closure member (37) can immerse during the damping phase such that the sealing lip (45) by means of a sealing surface (48) with the wall (78) of the control channel (28) sealingly cooperates, and wherein the End-position damping device (35) further comprises at least one throttle channel (52), which during the damping phase provides a throttled fluid connection between the first working chamber (22) and the control channel (28), characterized in that the at least one throttle channel (52) in the closure member (37) is formed and the closure member (37) passes through such that it - viewed in the damping phase - bypassing the sealing surface (48) of the sealing lip cooperating with the wall (78) of the control channel (28) ( 45) opens on the one hand with a first throttle channel mouth (76) in the first working chamber (22) and on the other hand with a second throttle channel mouth (77) in the control channel (28). Linear drive according to Claim 1, characterized in that the closure member (37) is a separate component with respect to the drive unit (14). Linear drive according to claim 1 or 2, characterized in that the at least one throttle channel (52) has a sealing lip (45) in its entirety immediate and not interspersed course. Linear drive according to one of claims 1 to 3, characterized in that the closure body (37) has a sealing lip (45) carrying support portion (55), which is suitably materially connected to the sealing lip (45). Linear drive according to claim 4, characterized in that the throttle channel (52) extends exclusively in the support section (55). Linear drive according to claim 4 or 5, characterized in that the support portion (55) is annular and expediently sleeve-shaped, wherein the sealing lip (45) is advantageously arranged in the region of an axial end face of the annular Tagabschnittes (55). Linear drive according to claim 6, characterized in that the sealing lip (45) with a root region (46) on the support portion (55) is fixed, wherein both throttle channel mouths (76, 77) on the drive piston (12) facing side of the root portion (46 ) are arranged. Linear drive according to claim 6 or 7, characterized in that the first throttle channel mouth (76) on the drive piston (12) facing side of the sealing lip (45) on the outer peripheral surface and the second throttle channel mouth (77) on the inner peripheral surface of the annular support portion (55). is arranged. Linear drive according to one of claims 6 to 8, characterized in that the at least one throttle channel (52) passes through the annular body of the annular support portion (55) radially. Linear drive according to one of claims 6 to 9, characterized in that the annular support portion (55) of the closure member (37) encloses an interior space (68) which is open on the drive piston (12) axially facing away from the end face and in the expediently the second Throttling channel mouth (77) opens. Linear drive according to one of claims 6 to 10, characterized in that the annular support portion (55) coaxially surrounds an axially projecting from the drive piston (12) extension of the drive unit (14) with a radial distance, such that between the annular support portion (55). and the extension is an annular space (75) constantly communicating with the throttle passage (52) and fluidly connected to the associated control passage (28) during the throttle phase. Linear drive according to claim 11, characterized in that an extension of the drive unit (14) immersed in the closure member (37) is fastened by a piston rod (15) or by a fastening device (67) serving to fix the drive piston (12) to a piston rod (15). is formed. Linear drive according to one of claims 4 to 12, characterized in that the support portion (55) of the closure member (37) part of a for fixing the closure member (37) on the drive unit (14) and for shutting off the control channel (28) during the damping phase serving Shut-off and fastening body (54). Linear drive according to claim 13, characterized in that the shut-off and fastening body (54) is annular and expediently a disk-shaped, centrally perforated and for fixing to the drive unit (4) serving mounting portion (56) and the one-sided coaxially adjoining support portion ( 55). Linear drive according to one of claims 1 to 14, characterized in that the closure member (37) is pot-shaped and has a suitably perforated bottom wall (42) and a sleeve-shaped and the sealing lip (45) supporting the side wall (43), wherein the side wall (43) is locally broken to form the at least one throttle channel (52). Linear drive according to one of claims 1 to 15, characterized in that the closure member (37) has a rigid material consisting of supporting body (82) to which the sealing lip (45) and expediently the sealing lip (45) having elastomeric body (83) cohesively is formed, wherein the support body (82) expediently a root portion (46) of the sealing lip (45) supporting axially behind engaging support projection (87). Linear drive according to one of claims 1 to 16, characterized in that it comprises two mutually opposing sides of the drive piston (12) arranged Endlagendämpfungseinrichtungen (35, 36), each having a one of two control channels (28, 29) cooperating closure member (37 ) and in each one of the two possible axial directions of movement of the drive unit (14) are effective.

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