EP1703144A1 - Linear fluid actuator - Google Patents

Abstract

The actuator has a locking mechanism (53) locking a drive unit such that the unit is prevented against a driving out movement. The mechanism has a latch unit (74) that is arranged with the locking surface such that the latch unit is moved into a locking position in stroke end positions that are adjustable in different manner. An axial distance exists between the surface and the unit based on the end positions.

Description

The invention relates to a fluid-operated linear drive, comprising a drive housing and a drive unit for driving in and out of linear drive motion, wherein the drive unit has at least one drive piston arranged in the drive housing and a piston rod arrangement protruding from the drive housing connected to the drive piston, and with a controllably operable on the drive housing locking device which is able to lock the retracted drive unit according to requirements such that it is prevented from an extension movement, wherein the locking means comprises a locking member, transversely to the direction of the drive movement of a movement the drive unit not disabling release position is movable into a locking position in which it protrudes in front of an oriented in the extension direction locking surface of the drive unit.

At one of the EP 0639120 B1 known linear actuator includes fluid displacement by the drive housing relative to the adjustable drive unit except a drive piston and a piston rod assembly projecting from the back of the piston rod bolt-like part., Which has a trained like an annular groove locking recess with dovetailed cross-section. Takes the drive unit their stroke end position in the retracted position, the locking recess is located at the same axial height with a transverse to the longitudinal axis of the drive unit movable latch member arranged on the drive housing, controlled operable locking device. By the locking device can be made a housing-fixed locking the drive unit during downtime of a machine equipped with the linear drive to prevent unintentional operation, for example, in connection with setup or maintenance and to provide a defined basic position of the drive unit for the new commissioning , A disadvantage of the known linear drive is the lack of possibility of a variable Hubvorgabe the drive unit and in particular the occupied in the retracted position Hubendlage. A variation of the stroke end position assumed by the retracted drive unit in at least a small frame would be desirable in order to be able to individually adapt the linear drive to the local conditions during installation on site.

Measures for stroke adjustment are as such, for example, from EP 0868965 B1 known. The drive unit of the linear drive described therein has a connected to the piston rod assembly, outside of the drive housing linearly slidably guided slide and is equipped with effective between the drive housing and the slide Hubbegrenzungsmitteln that allow, inter alia, a variable specification of the retracted Hubendlage. In this linear drive, however, lacks the possibility of locking the retracted drive unit.

In another known to the Applicant, but not documented by letter linear drive, the drive unit is also displaceable with an outside of the drive housing equipped carriage, wherein additionally a housing-fixed locking device is present, which engages for locking the retracted stroke end position of the drive unit in a bore which is formed on a arranged at the rear end portion of the carriage additional part. This linear drive in turn does not have means for variable specification of the retracted stroke end position of the drive unit.

It is the object of the present invention to provide a linear drive of the type mentioned, which can be adapted while maintaining the possibility of locking the drive unit flexible to the particular application.

To solve this problem adjustable stroke limiting means are provided in the linear drive, with which the stroke end position assumed by the retracted drive unit can be variably predetermined. In connection therewith, the locking surface and the locking member of the locking device are arranged relative to each other such that the locking member is displaceable at different set Hubendlagen the drive unit in the locking surface upstream locking position, in which case depending on the respective adjusted stroke end a different sized axial distance between the Arresting surface and the locking member is present.

The invention is based on the finding that only the stroke end position of the retracted drive unit represents a relevant variable for continuous operation, while the locking measures essentially serve only safety and comfort purposes, the requirements are met even when the drive unit in the locked state has slight movement play with respect to the drive housing in the direction of the drive movement. The design and position of locking member and locking surface are therefore coordinated so that the locking member can be brought not only at a single specific stroke end position of the drive unit in the locking position, but in different Hubendlagen that can be specified by the adjustable Hubbegrenzungsmittel and where the drive unit moved far different in the drive housing. In this way, the retracted stroke end position can be varied while maintaining the possibility of locking, which facilitates flexible adaptation of the linear drive to the circumstances of the respective application.

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

The locking surface is expediently located on the piston rod assembly. This has the advantage that the locking forces act symmetrically with respect to the possibly acting on the drive unit fluid forces and consequently no adverse bending moments occur. Also, very high holding forces can be exercised in this way.

In conjunction with an embodiment in which the drive unit additionally has a slide guided on the outside of the drive housing in a linearly displaceable manner, the locking surface provided on the piston rod arrangement has the advantage that the connection measures between the piston rod arrangement and the slide are not stressed by the holding forces. This would be the case if the interlocking measures interacted with the carriage.

Preferably, the locking surface is arranged coaxially to the at least one piston rod having piston rod assembly and thereby formed in particular annularly closed in itself. Thereby, the desired locking function can be ensured even if the drive unit is not secured against rotation with respect to the drive housing.

The locking surface may be provided on a belonging to the piston rod assembly bush, which is mounted coaxially on the piston rod and fixed relative to this immovable axially. The bushing is preferably provided on the outer end region of the piston rod which is axially opposite the drive piston.

In a preferred embodiment, the drive housing has a fluid-impingable working chamber defining end wall, which is penetrated by the piston rod assembly under seal, wherein the locking surface is provided at the lying outside the working chamber end portion of the piston rod assembly. The interlocking measures can thus take place outside of the pressurized medium during operation and do not require special sealing measures.

In a particularly compact design, the locking device is designed as a structural unit, which is inserted in a cartridge-like manner in a corresponding receptacle of the drive housing.

It is advantageous if, in the locking position, the locking member cooperates with the locking surface on at least two regions which are diametrically opposed relative to the longitudinal axis of the piston rod. As a result, the emergence of bending moments is prevented when the locking surface is biased by a fluid loading of the drive piston against the locking member. Appropriately, it is provided that extends the contact surface between the locking member and the locking surface in the locking position along a circular arc with an arc length of about 180 °.

For direct cooperation with the locking surface, the locking member is expediently provided with a fork-like locking portion, the opening of the piston rod facing and which is adjustable transversely to the longitudinal axis of the piston rod assembly, wherein it engages in the locking position of the locking surface upstream region of the piston rod assembly like a rider.

A particularly expedient embodiment provides that the locking member has an opening penetrated by the piston rod arrangement, which has a larger cross-sectional area enabling the passage of the locking surface and an adjoining smaller cross-sectional area defining the fork-like locking portion. The latch member is then selectively positionable such that either the larger cross-sectional area or the fork-like latch portion defined by the smaller cross-sectional area is effective. In the effective state of the larger cross-sectional area, the piston rod assembly can freely perform their linear movement. If the smaller cross-sectional area is effective, the drive unit is prevented from extending.

The locking member may in particular be formed flat slide-like and in particular the shape of a plate having an interspersed by the piston rod assembly opening.

The locking device preferably has a sleeve-like housing, which is penetrated by the piston rod assembly and in the region of the piston rod assembly has two opposing guide slots in which the locking member is mounted in a displaceably guided manner to be moved between the release position and the locking position can. It is advantageous if the locking member passes through the interior of the housing according to the course of a secant eccentrically.

The piston rod assembly passing through the sleeve-like housing can be used to axially retain the locking unit inserted in a cylindrical receptacle of the drive housing and at the same time to prevent it from rotating relative to the drive housing. This can then expediently be dispensed with even further fastening means.

Conveniently, the drive unit includes a motion-coupled to the outer end portion of the piston rod assembly carriage, which is outwardly guided linearly adjustable on the drive housing and is suitably equipped with fastening means by which a load to be moved to the drive unit can be fixed. The interaction of the carriage with a linear guide ensures that absorbed by the coupled load, not coincident with the direction of the drive movement forces absorbed by the drive housing and wear-promoting loads are kept away from the piston rod assembly and the drive piston.

The stroke limiting means responsible for specifying the end position of the retracted drive unit are expediently effective between the drive housing and the carriage, In particular, they are associated with the rear end portion of the carriage and thus are easily accessible for any adjustment.

Fig. 1

eine bevorzugte erste Bauform des Linearantriebes in einer perspektivischen Rückansicht bei in die entsprechende Hubendlage eingefahrener Antriebseinheit,

Fig. 2

den Linearantrieb aus Fig. 1 in einer entsprechenden Darstellung bei ausgefahrener Antriebseinheit,

Fig. 3

die Anordnung aus Fig. 1 im Längsschnitt gemäß Schnittlinie III-III und teilweise aufgebrochen,

Fig. 4

die Anordnung aus Fig. 2 im Längsschnitt gemäß Schnittlinie IV-IV und teilweise aufgebrochen,

Fig. 5

einen Schnitt durch den Linearantrieb gemäß Schnittlinie V-V im Bereich der Verriegelungseinrichtung, wobei nur die Verriegelungseinrichtung und die Kolbenstangenanordnung abgebildet sind und wobei das Riegelglied die Verriegelungsstellung einnimmt,

Fig. 6

die Anordnung aus Fig. 5 bei in der Freigabestellung befindlichem Riegelglied,

Fig. 7 und 8

die Anordnungen aus Fig. 5 und 6 in perspektivischer Darstellung, wobei das Gehäuse der Verriegelungseinrichtung nicht abgebildet ist,

Fig. 9

einen Ausschnitt des Linearantriebes gemäß Fig. 4 im Bereich der Verriegelungseinrichtung mit einer Stirnansicht auf die von der Kolbenstange durchsetzte Verriegelungseinrichtung mit Blickrichtung gemäß Pfeil IX aus Fig. 4 und 10 und

Fig. 10

eine Einzeldarstellung der Kolbenstangenanordnung und der dieser zugeordneten Verriegelungseinrichtung.

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

Fig. 1

a preferred first design of the linear drive in a perspective rear view when retracted into the corresponding stroke end drive unit,

Fig. 2

1 in a corresponding representation when the drive unit is extended,

Fig. 3

the arrangement of Figure 1 in longitudinal section along section line III-III and partially broken,

Fig. 4

the arrangement of Figure 2 in longitudinal section along section line IV-IV and partially broken,

Fig. 5

a section through the linear drive according to section line VV in the region of the locking device, wherein only the locking device and the piston rod assembly are shown and wherein the locking member assumes the locking position,

Fig. 6

the arrangement of FIG. 5 in befindlichem in the release position latch member,

FIGS. 7 and 8

the arrangements of Figures 5 and 6 in perspective view, wherein the housing of the locking device is not shown,

Fig. 9

a section of the linear drive of FIG. 4 in the region of the locking device with an end view of the interspersed by the piston rod locking device with viewing direction according to arrow IX of FIG. 4 and 10 and

Fig. 10

an individual view of the piston rod assembly and the associated locking device.

The exemplary linear drive shown in its entirety in FIGS. 1 to 4 has an elongated drive housing 2 with a longitudinal axis 3, a transverse axis 4 perpendicular thereto and a vertical axis 5 which is in turn perpendicular to the two aforementioned axes. The three axes mentioned thus span a Cartesian system ,

The drive housing 2 has by way of example a substantially U-shaped profiled cross section with a perpendicular to the vertical axis 5 extending bottom wall 8 and two spaced apart starting from the bottom wall 8 in the direction of the vertical axis 5 towering first and second side walls 6, 7. The two side walls 7 and the bottom wall 8 together define a housing recess 12 open on the longitudinal side opposite the bottom wall 8.

The previously explained components of the drive housing 2 are expediently part of a one-piece, preferably produced by extrusion profile part 11th

At its rear side, the channel-like housing recess 12 is delimited by a rear end wall 14 of the drive housing 2 attached to the rear end face of the profile part 11. On the other hand, the housing recess 12 is open toward the opposite front side.

In the interior of the drive housing 2, a preferably cylindrical contoured, longitudinal cavity is formed, which is referred to below as the drive chamber 16. It runs in the embodiment in the respect to the second side wall 7 a greater thickness having first side wall 6 and is also closed by the end wall 14 back.

The drive space 16 is formed by a longitudinal portion of a bore-like housing channel 17, which passes through the profile part 11 over its entire length and opens at the front end face 13 with an opening 15.

Through the opening 15 through a plug-like closure cap 18 is inserted a little way into the housing channel 17 and fixed axially immovable. He is in sealing contact with the wall of the housing channel 17 and limits the drive space 16 at the end wall 14 opposite front.

The linear drive also includes a drive unit 23, which is under the execution of a clarified by a double arrow drive movement 22 in the direction of the longitudinal axis 3 relative to the drive housing 2 and retractable.

The drive unit 23 includes a drive piston 16 slidably disposed in the drive piston 24, the drive space 16 under sealing in a closure lid 18 associated front working chamber 25 and one of the end wall 14 associated rear working chamber 26 divided. In each working chamber 25, 26 opens a separate fluid channel 27a, 27b, through which a fluidic pressure medium can be fed or discharged to control the drive piston 24 controlled so that it linearly displaced under execution of an extension movement or retraction. The fluid supply takes place via fluid hoses, not shown, which can be connected in the embodiment in the region of the end wall 14 to the fluid channels 27a, 27b.

On the drive piston 24, a piston rod assembly 28 is attached. This extends through the front working chamber 25 and penetrates under sealing the closure cap 18, so that it protrudes in the region of the front with an outer end portion 32 of the drive housing 2.

The outer end portion 32 engages in a tensile and pressure-resistant manner to a connecting yoke 33, which is part of an outside of the drive housing 2 linearly adjustable in the direction of the longitudinal axis 3 guided slide 34. The carriage 34 thus forms together with the piston rod assembly 28 and the drive piston 24, the only uniformly movable drive unit 23. An axial displacement of the drive piston 24 by appropriate fluid loading thus has the simultaneous synchronous displacement of the carriage 24 to the episode.

As can be seen in particular from FIGS. 3 and 4, the drive space 16 in the exemplary embodiment within the drive housing 2 assumes an eccentric position offset in the direction of the transverse axis 4 relative to the longitudinal axis 3. The center of the Drive space 16 is thus offset in the direction of the transverse axis 4 with respect to the cross-sectional center of the drive housing 2 to the edge of the housing.

On the other hand, the carriage 34 is located in the region of the channel-like housing recess 12. It has a plate-like carriage main part 35, which adjoins the connecting yoke 33 in the direction of the longitudinal axis 3 and whose plane of extent extends at right angles to the vertical axis 5.

The length of the carriage 34 corresponds substantially to that of the drive housing 2, wherein the carriage 34 extends with its main carriage part 35 in the region of the open longitudinal side of the channel-like housing recess 12 along the latter. It practically forms a cover for the open longitudinal side of the housing recess 12, wherein the covered length is variable and depends on the instantaneous relative position between the carriage 34 and the drive housing 2.

If the drive unit 23 is retracted as far as possible with respect to the drive housing 2, the retracted carriage position shown in FIGS. 1 and 3 results, in which the carriage 34 covers the channel-like housing recess 12 over virtually its entire length. If, on the other hand, the drive unit 23 is further extended out of the drive housing 2, then the carriage 34 projects further beyond the front end face 13 of the drive housing 2, so that the rear end section of the housing recess 12 is exposed.

Conveniently, the carriage body 35 is sunk in the direction of the vertical axis 5 in the channel-like housing recess 12 so that it is flanked on its two longitudinal sides by the two side walls 6, 7.

To guide and support the carriage 34 with respect to the drive housing 2, a guide device 36 is provided, which has two parallel and spaced-apart guide units 37a, 37b, which are placed in the direction of the transverse axis 4 between the main carriage part 35 and the drive housing 2. The two guide units 37a, 37b extend together in a direction perpendicular to the vertical axis 5 guide plane, which runs parallel to the plane of extension of the main carriage part.

Each guide unit 37a, 37b has a housing-side guide track 42 arranged on the inner side of the respective first and second side wall 6, 7 facing the other side wall. These guide tracks 42 on the housing side expediently extend over the entire length of the profile part 11. Each guide track 42 on the housing side lies in the direction of the transverse axis 4, a carriage-side guide track 43 opposite, which extends along the carriage main part 35. Between each pair of associated housing-side and carriage-side guideways 42, 43 is a bearing element arrangement 44, which is composed of sliding bodies or of a group of rolling bearing elements combined in a cage. If the drive unit 23 executes its drive movement 22, the bearing element arrangement 44 runs down on the guideways 42, 43 cooperating with it, so that a precise linear guide for the carriage 34 and thus the entire drive unit 23 is established.

Via the guide device 36, forces acting on the carriage 34 whose direction of action does not coincide with the longitudinal axis 3 are introduced into the drive housing 2. These forces may be due to any load imposed on the carriage 34 for the purpose of movement or positioning can be attached. This load may be, for example, a component of a machine or another linear drive. Attached to the carriage 34 fasteners 45, for example in the form of threaded holes, allow the detachable attachment of the respective load.

The linear drive is equipped with adjustable stroke limiting means 53, which enable a variable specification of at least the stroke end position assumed by the drive unit 23 in the retracted state relative to the drive housing 2. For simplicity, this stroke end position is referred to below as "retracted stroke end position". Due to the adjustability of the retracted stroke end position can be determined from case to case, how far the drive unit 23 is actually retracted in the retracted stroke end position in the drive housing 2 and how far it protrudes on the front end side of the drive housing 2. Such adjustability facilitates the adaptation of the linear drive to the local conditions during installation on site.

Expediently, the stroke limiting means 53 act between the drive housing 2 and the carriage 34. In this case, they are preferably associated with the rear end region of the carriage 34.

In the exemplary embodiment, the stroke limiting means 53 comprise an end stop 54 carried by the drive housing 2, which is preferably arranged on the rear end wall 14 and projects from there in the direction of the longitudinal axis 3 to the slide 34. His the slide 34 facing end surface defines a stop surface 55, which may be associated with a stop member 54 belonging to the buffer element 56, if necessary.

The abutment surface 55 is located opposite a counter-abutment surface 57, which is oriented in the retraction direction of the drive unit 23 and, in the exemplary embodiment, is arranged on the rear end face of the carriage main part 35. With this counter stop surface 57, the drive unit 23 can accumulate on the stop surface 55.

The end stop 54 is variably positionable in the direction of the drive movement 22 relative to the drive housing 2. This adjustment is realized in the embodiment in that the end stop 54 is formed as an external thread exhibiting screw member which is screwed into a provided with an internal thread axial opening 58 of the end wall 14 in the extension of the housing recess 12.

With an operating portion 62, the end stop 54 projects beyond the end wall 14 on the rear side. There, a torque can be introduced to cause a rotational movement, which also has the desired axial adjustment movement result. The introduction of the torque can take place manually without tools or with the aid of a screwing tool. For the latter purposes, the operating portion 62 may be equipped with a tool engagement portion 63.

The respectively set axial position of the end stop 54 can be fixed by an associated securing member 64 against unintentional adjustment. The securing member 64 may be, for example, a clamping element or a lock nut.

The retracted stroke end position of the drive unit 23 is defined by the contact of the counter stop surface 57 with the stop surface 55. Due to the adjustability of the end stop 54 thus also the stroke end position can be varied. In Fig. 4, this is illustrated by the fact that a possible changed stop position of the end stop 54 is indicated by dash-dotted lines. In addition, an adjustment range "s" is identified, which is available for possible variations of the retracted stroke end position and can be covered by appropriate adjustment of the end stop 54.

In addition to or instead of a buffer element 56, the stroke limiting means 53 may, if necessary, also have other shock-absorbing means in order to achieve a cushioning. The shock-absorbing means may include, for example, at least one fluidic shock absorber.

The piston rod assembly 28 is composed of several components in the embodiment. These components are on the one hand a piston rod 66 in the true sense and the other on the outer end portion of the same coaxially patch bushing 67. The bushing 67 is preferably only plugged, the Aufsteckmaß is determined by an annular collar 68 of the bushing 67, on the front side the piston rod 66 comes to rest. The attachment to the connecting yoke 33 is carried out by way of example by a fastening screw 72, which passes through the connecting yoke 33 from the front and is screwed into the piston rod 66 at the front side. In this case, the bush 67 is axially clamped in the region of its annular collar 68 between the connecting yoke 33 and the piston rod 66. The bush 67 is thus fixed axially immovable with respect to the piston rod 66.

The linear drive is further equipped with a drive housing 2 arranged on the controllable actuated locking device 65. This is capable of currently a retracted Hubendlage engaging drive unit 23 locked so fixed to the housing that it is prevented from an extension movement. For this purpose, the locking device 65 includes a locking member 74 which can be displaced transversely to the direction of the working movement 22 while carrying out an actuating movement 73, while a locking surface 75 oriented in the extension direction and therefore axially outwardly is provided on the piston rod assembly 28.

By the actuating movement 73, the locking member 74 can be selectively positioned in a release position resulting from FIGS. 4, 6 and 8 and a locking position shown in FIGS. 3, 5 and 7. While it comes to rest in the locking position in front of the locking surface 75 when the drive unit 23 assumes a retracted stroke end position, it is in the release position in a remote from the stroke of the locking surface 75 position, so that the piston rod assembly 28 and thus the entire drive unit 23 unhindered can extend.

An essential aspect in the mutual association of locking member 74 and locking surface 75 is that it is ensured that the locking member 74 in each retracted stroke end position of the drive unit 23, which is predetermined by the adjustment range "s", in the locking surface 75 upstream locking position displaced is. In this case, it is accepted that, depending on the respectively set stroke end position, a different sized axial distance "a" is present between the arresting surface 75 and the locking member 74. Since the interlocking measures no positioning of the drive unit 23 is intended, but only a safety purpose serving detent, a slight axial play in the respective Hubendlage does not adversely affect the operation of the linear drive.

FIG. 3 shows a set stroke end position, in which the drive unit 23 has been moved as far as possible into the drive housing 2. The axial distance "a" between the locking surface 75 and the locking member 74 in this case assumes a maximum. If, on the other hand, the drive unit 23 has retracted to a lesser extent due to a changed setting of the end stop 54 in the assigned stroke end position, the arresting surface 75 is located, for example, in a position which is further outward in FIG. 3 at 75 ', in which its distance from the locking member 74 is lower. The one arrestable stroke end position in which the drive unit 23 is retracted at least far is defined by the fact that the arresting surface 75 is axially directly adjacent to the locking member 74 placed in the locking position.

The locking surface 75 is expediently located on the piston rod assembly 28. This has the advantage, among other things, that the retaining forces to be applied by the locking device 65 when the fluid piston is applied axially outward of the drive piston do not stress the fastening measures present between the piston rod assembly 28 and the main carriage part 35. For example, if the locking surface were located on the carriage main part 35, the holding forces that would have to be transmitted would have to be transmitted by the fastening screw 72 as well as the fastening screws 72 'expediently used to connect the connecting yoke 33 and slide main part 35, which could result in overstressing.

In the embodiment, the locking surface 75 is a coaxial with the piston rod 66, axially outwardly oriented annular surface. This could be provided directly on the piston rod 66, but in the present case is located on the end face on the piston rod 66 seated sleeve 67th

The bushing 67 has a ring circumferential, annular groove-like constriction 76, from the two flanks of the axially outwardly facing the locking surface 75 forms. Consequently, the locking surface 75 is located on the drive piston 24 opposite the outer end portion of the piston rod assembly 28th

The locking surface 75 is placed so that it is always outside the drive chamber 16 regardless of the axial position of the piston rod assembly 28.

Preferably, the closure lid 18 acting as the end wall of the front working chamber 25 is placed at an axial distance from the end face 13 in the housing channel 17 so that an outer channel section 77 of the housing channel 17 remains between the end face 13 and the closure lid 18, within which the arresting surface 75 at each adjusted retracted stroke end position is. The drive housing 2 thus protrudes beyond the closure cover 18 with an end section defining the outer channel section 77. At this end portion and the locking device 65 is arranged.

More precisely, the locking device 65 is seated in the embodiment in the manner of a cartridge in a preferably circular cylindrical contoured receptacle 78 which is formed in the region of the closure cover 18 outside vorgelagerten end portion of the drive housing 2 with perpendicular to the longitudinal axis of the piston rod assembly 28 extending longitudinal axis 79. The receptacle 78 crosses the outer channel section 77.

The assembly of the locking unit 65 is effected by a simple plug-in assembly. This is facilitated by that the components of the locking device 65 are combined to form a cartridge-like unit.

The locking device 65 has a sleeve-like, preferably substantially hollow-cylindrical housing 83, in which a positioning piston 84, which is displaceable in the direction of the longitudinal axis 79, is displaceably arranged under sealing. The direction of displacement corresponds to the direction of the actuating movement 73 desired for the locking member 74.

Together with the housing 83, the actuating piston 84 delimits an application chamber 85, which is connected to a control channel 86, to which a control line 87 leading to a fluid source (FIG. 1) can be connected by means of connecting means (not shown). The loading chamber 85 is associated with the piston rod 66 opposite the outer end portion of the housing 83.

A on the Beaufschlagungskammer 85 axially opposite side of the actuating piston 84 arranged between the control piston 84 and the housing 83 supporting return spring 88 acts on the control piston 84 constantly in the direction of FIG. 3 and 5 resulting starting position in which the volume of the Beaufschlagungskammer 85th has a minimum.

The actuating piston 84, together with the loading chamber 85, the return spring 88 and the associated housing portion to an actuating portion 89 of the locking device 65 which projects at least for the most part laterally from the drive housing 2 when inserted into the receptacle 78 locking device 65. At this operating portion 89 is axially closed a fully recessed in the receptacle 78 working portion 93 of the locking device 65, which is traversed transversely by the piston rod assembly 28.

The housing 83 has in the region of the working portion 93 two diametrically opposed and mutually aligned first and second openings 94a, 94b, through which the piston rod assembly 28 extends therethrough. The end face 13 adjacent second opening 94 b has a sufficiently large cross-section to pass the sleeve 67 with the locking surface 75. The closure opening 18 adjacent first opening 94 a has only a slightly larger cross section than the piston rod 66th

The housing 83 passing through the piston rod assembly 28 holds the locking unit 65 in the receptacle 78 so that there is no need for further fastening means for anchoring the locking device 65. This simplifies the assembly. At the same time, the interaction of the piston rod 66 with at least the first opening 94a effects an anti-rotation lock of the locking device 65 with respect to the drive housing 2.

The working portion 93 of the locking device 65 takes in the embodiment also still the advantageous function of an axially outside of the closure cover 18 projecting securing element which fixes the only inserted closure cap 18 in the housing channel 17. Axially opposite the closure cap 18 is blocked by protruding into the housing channel 17 housing fixed stop means 95.

In which the perforations 94a, 94b having inner housing portion 96 of the housing 83 is the above-mentioned locking member 74. It is flat slide-like in the embodiment formed with a right angle to the longitudinal axis of the piston rod assembly 28 expansion plane. Directly, or as in the embodiment with the interposition of a connecting member 97, the locking member 74 is in such a fixed connection with the actuating piston 84 that it participates directly in each case the piston movement.

The locking member 74 is stabilized by the inner housing portion 96 in its position and slidably guided. For this purpose, the inner housing portion 96 is eccentrically provided with two opposite guide slots 98 which pass through the housing each radially and extend axially, where they expediently open to the inner end face of the housing 83.

The locking member 74 dips with its opposite longitudinal edge portions 99 in each case one of the guide slots 98 slidably and thereby passes through the interior of the housing 83 off-center according to the course of a secant. Conveniently, the locking member 74 is on the front side 13 facing side of the longitudinal axis 79th

The locking member 74 is rounded at the narrow sides of the two edge portions 99 corresponding to the contour of the cylindrical receptacle 78. As a result, a surface contact with the inner surface of the receptacle 78 is possible. In the locking position by the abutment surface 55 forces exerted on the latch member 74 forces are thereby introduced directly and relatively large area in the drive housing 2. The housing 83 and the other components of the locking device 65 are thereby relieved and are only very little stress.

The locking member 74 has a transverse to its extension plane through opening 100. This is aligned with the two openings 94a, 94b of the housing 83 and is penetrated by the piston rod assembly 28.

The aperture 100 has two in the direction of the actuating movement 73 consecutive and directly merging into each other cross-sectional areas of different sizes. A larger cross-sectional area 101 is sized large enough to pass the locking surface. A subsequent smaller cross-sectional area 102, however, is so narrow that it prevents the passage of the locking surface 75.

By a correspondingly controlled fluid admission of the actuating piston 84, this and thus also the locking member 74 can be driven to the actuating movement 73 in order to position the locking member 74 either in the locking position or in the release position. In the release position according to FIGS. 4 and 6, the locking member 74 is displaced axially inwards, so that the larger cross-sectional area 101 is aligned with the piston rod assembly 28 and an unobstructed mobility of the drive unit 23 is given. The pressure medium fed into the admission chamber 85 for activation displaces the actuating piston 84 counter to the restoring force of the restoring spring 88 which compresses in the process.

In order to lock a retracted stroke end position, the pressure medium is discharged from the loading chamber 85, so that the locking member 74 is displaced axially outwardly by the return spring 88, so that the smaller cross-sectional area 102 reaches into the region of the piston rod, resulting in the locking position.

As actuating fluid for the locking device, as well as for the actuation of the drive unit 16, in particular compressed air is provided. However, operation with another gaseous medium or hydraulic medium would also be possible.

The locking position results from the fact that a fork-like locking portion 103 delimiting the smaller cross-sectional area 102 assumes a position in which it engages over the area of the piston rod arrangement 28 which is axially upstream of the arresting surface 75 in a rider-like manner and thereby comes to rest in front of the arresting surface 75. The contact surface between the locking member 74 and the locking surface 75 extends over a circular arc 104 with an arc length of about 180 °.

The fork-like configuration of the locking portion 103 has the advantage that in the locking position inter alia, an effective support takes place per se with respect to the longitudinal axis of the piston rod assembly 28 diametrically opposite regions of the piston rod assembly 28. Thus, the locking forces are symmetrically introduced into the piston rod assembly 28, and there are no bending stresses.

The additional arcuate contact also causes a large-scale power transmission resulting in reduction of the specific stress.

In the embodiment, an active loading of the actuating piston 84 with pressure medium is necessary to hold the latch member 74 in the release position. The locking position, however, is only guaranteed mechanically by the return spring 88. This is the maintenance of the locking position independent of the fluid supply. Nevertheless, of course, a reverse drive would be realized.

In one embodiment, not shown, the locking device 65 is equipped with electrical actuating means and can be operated purely electrically and without fluid support.

Claims (22)

Fluid-actuated linear drive, with a drive housing (2) and a drive unit (23) which can be driven in and out for linear drive movement, wherein the drive unit (23) has at least one drive piston (24) arranged in the drive housing (2) and one with the drive piston (24) connected, frontally from the drive housing (2) protruding piston rod assembly (28), and arranged on the drive housing (2), controllably operable locking device (65) which is able, the retracted drive unit (23) as required fixed to the housing so as to be prevented from extending, said locking means (65) having a latch member (74) movable transversely to the direction of drive movement from a release position not obstructing movement of the drive unit (23) to a latching position it in front of an oriented in the extension direction locking surface (75) of the drive unit (23) protrudes, characterized in that adjustable stroke limiting means (53) are provided, with which the stroke of the retracted drive unit (23) assumed variable stroke is predetermined, and that the locking surface (75) and the locking member ( 74) are arranged relative to each other such that the locking member (74) at different adjusted Hubendlagen the drive unit (23) in the locking surface (75) upstream locking position is displaceable, depending on the respective set stroke end position a different size axial distance between the locking surface (75) and the locking member (74) is present. Linear drive according to claim 1, characterized in that the locking surface (75) is located on the piston rod assembly (28) Linear drive according to claim 2, characterized in that the locking surface (75) is arranged coaxially to the piston rod assembly (28) and expediently ring-shaped closed in itself. Linear drive according to claim 2 or 3, characterized in that the piston rod assembly (28) has a piston rod (66) and a particular at the outer end portion thereof axially immovable on the piston rod (66) seated bushing (67), wherein the locking surface (75) the bush (67) is formed. Linear drive according to one of claims 2 to 4, characterized in that the locking surface (75) on the drive piston (24) opposite the outer end portion of the piston rod assembly (28). Linear drive according to one of claims 2 to 5, characterized in that the piston rod assembly (28) passes through a sealing a fluidbeaufschlagbare working chamber (16) delimiting end wall (16) of the drive housing (2), wherein the locking surface (75) outside the working chamber (75) 16) lying end portion of the piston rod assembly (28) is assigned. Linear drive according to claim 6, characterized in that the drive housing (2) with an end portion over the from the piston rod assembly (28) interspersed end wall (18) protrudes and at this end portion carries the locking device (65). Linear drive according to one of claims 2 to 7, characterized in that the locking device (65) is designed as a cartridge-like in a receptacle (78) of the drive housing (2) used assembly. Linear drive according to one of claims 2 to 8, characterized in that the locking member (74) cooperates in the locking position at least two mutually with respect to the longitudinal axis of the piston rod assembly (28) diametrically opposite areas with the locking surface (75). Linear drive according to claim 9, characterized in that extending the contact surface between the latch member (74) and locking surface (75) in the locking position along a circular arc of about 180 °. Linear drive according to one of claims 2 to 10, characterized in that the locking member (74) with its opening of the piston rod assembly (28) facing the fork-like locking portion (103) which is movable transversely to the longitudinal axis of the piston rod assembly and in the locking position of the locking surface (75) engages upstream region of the piston rod assembly (28) like a rider. Linear drive according to claim 11, characterized in that the locking member (74) has an opening (100) penetrated by the piston rod arrangement (28), which allows a larger passage through the locking surface (75) Cross-sectional area (101) and an adjoining, the fork-like locking portion (103) defining smaller cross-sectional area (102), wherein the locking member (74) is selectively positionable so that either the larger cross-sectional area (101) or the smaller cross-sectional area (102 ) defined fork-like locking portion (103) is effective. Linear drive according to one of claims 2 to 12, characterized in that the locking member (74) is formed flat slide-like. Linear drive according to one of claims 2 to 13, characterized in that the locking device (65) has a sleeve-like housing (83) which is penetrated by the piston rod assembly (28) and in the region of the piston rod assembly (28) two opposite, leading to Receiving the locking member (74) serving guide slots (98), wherein the locking member (74) expediently passes through the interior of the housing (83) in accordance with the course of a secant eccentrically. Linear drive according to claim 14, characterized in that the housing (83) is rotatably inserted into a cylindrical receptacle (78) of the drive housing (2) and held axially by the piston rod arrangement (28) passing through it and at the same time secured against rotation. Linear drive according to claim 14 or 15, characterized in that the locking member (74) at its the two guide slots (98) associated edge portions (99) of the contour of the cylindrical receptacle (78) is correspondingly rounded and with these edge portions (99) directly to the wall of the cylindrical receptacle (78) can be supported. Linear drive according to one of claims 14 to 16, characterized in that the housing (83) of the locking device (65) includes a movement-coupled with the locking member (74) actuating piston (84) by at least one also in the housing (83) arranged return spring (88) is biased into a corresponding initial position of the locking position, from which it can be displaced by fluid loading in an activated position corresponding to the release position. Linear drive according to one of claims 1 to 17, characterized in that the drive unit (23) has a with the outer end portion of the piston rod assembly (28) connected outside of the drive housing (2) linearly guided guided slide (34), which expediently with for attachment a fastening means (45) suitable for moving load is provided. Linear drive according to claim 18, characterized in that the Hubbegrenzungsmittel (53) between the drive housing (2) and the carriage (34) are effective. Linear drive according to claim 19, characterized in that the Hubbegrenzungsmittel (53) are associated with the rear end portion of the carriage (34). Linear drive according to claim 19 or 20, characterized in that the Hubbegrenzungsmittel (53) has a the slide (34) rearwardly projecting end stop (54) which is variably positionable in the direction of the drive movement relative to the drive housing (2). Linear drive according to claim 21, characterized in that the end stop (54) is an adjustable by a rotary screw member.

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