EP3825558A1 - Piston / cylinder unit with locking - Google Patents

Abstract

The present invention relates to a piston / cylinder unit comprising a cylinder (1) and at least one piston (2), the piston (2) dividing the cylinder (1) into a first cylinder chamber (3) and a second cylinder chamber (4) , the first cylinder chamber (3) has a connection (5) for an operating medium and the piston (2) can be moved in a first direction (6) by feeding the operating medium into the first cylinder chamber (3) and against the first direction (6) can be acted upon or acted upon by a force independent of the operating medium in a second direction (7) and the piston (2) is movable in a release position in the first direction (6) and in the second direction (7) in the cylinder (1), the movement of the piston (2) in a locking position in the second direction (7) being restricted, for which purpose the piston / cylinder unit has at least one radially projecting switching cam (8) and a link guide (10) for the at least one scarf tnocken (8), wherein the at least one switching cam (8) and the link guide (10) are rotatably mounted relative to one another.

Description

The present invention relates to a piston / cylinder unit and in particular to a pneumatic cylinder, comprising a cylinder and at least one piston, the piston dividing the cylinder into a first cylinder chamber and a second cylinder chamber, the first cylinder chamber and preferably also the second cylinder chamber (each) Have connection for an operating medium and the piston can be moved in a first direction by feeding the operating medium into the first cylinder chamber and can be acted upon or acted upon by a force independent of the operating medium in a second direction and the piston is in a release position in the first direction Direction and is movable in the second direction in the cylinder.

In order to keep the piston in an end position against the force, it is necessary that the operating medium is continuously supplied to the first cylinder chamber. A relatively high expenditure of energy is therefore required to hold the piston in one position.

The object of the present invention is therefore to at least partially solve the problems described with reference to the prior art and in particular to specify a piston / cylinder unit with which the energy consumption is reduced in order to move the piston in one position against the force independent of the operating medium to keep.

The object is achieved by a piston / cylinder unit with the features of the independent claim. Advantageous further developments of the piston / cylinder unit are specified in the dependent claims and in the description, with individual features of the advantageous further developments being able to be combined with one another in a technically meaningful manner.

The object is achieved in particular by a piston / cylinder unit with the features mentioned at the beginning, in which the movement of the piston is restricted in a locking position in the second direction, for which purpose the piston / cylinder unit has at least one, preferably at least two radially projecting (n ) Comprises switching cams and a link guide for the at least one switching cam, wherein the at least one switching cam and the link guide are rotatably mounted relative to one another and are designed and arranged in such a way that switching between the release position and the locking position is effected by a specific movement generated by the operating medium can be introduced in the first direction, the switching cam interacting with the link guide during the switchover and in the locking position, the at least one switching cam and the link guide also being designed and arranged in such a way that the piston is also not ready osition of the operating medium is held in the locking position by the force acting against the first direction due to the interaction of the at least one switching cam with the link guide.

The basic idea of the invention therefore provides that the piston / cylinder unit has a locking unit comprising the at least one switching cam and the link guide, the piston being caused by a targeted pressure increase in the first cylinder chamber with which the piston moves over a travel path that is customary in the release position is moved out, can be brought into the locking position. In the locked position, the force on the piston that is independent of the operating medium, the piston being prevented / limited from moving in the second direction by the interaction between the at least one switching cam and the link guide. In order to transfer the piston from the locking position to the release position, a targeted pressure increase is again necessary, with which the piston is moved in the first direction. In this switchover, too, the at least one switching cam interacts with the link guide. Thus, no supply of an operating medium is necessary in the locking position and the switchover between the release position and the locking position can be carried out solely with the aid of the operating medium, so that no further control / regulation for locking needs to be provided in addition to the usually existing control / regulation of the operating medium.

The piston / cylinder unit can be designed as a rodless cylinder in which no piston rod is connected to the piston. In these cases, the piston can have a lateral load take-off through a slotted cylinder tube. However, it can also be provided that the piston has a piston rod on one or both sides. The specific design of the piston or the piston rod (s) is therefore not important for the implementation of the invention.

However, it is necessary that the piston can be moved in a targeted manner in the first direction by feeding the operating medium into the first cylinder chamber. For this purpose, the first cylinder chamber has a connection for an operating medium (fluid such as compressed air, for example). However, it can also be provided that the second cylinder chamber opposite the first cylinder chamber also has a connection for an operating medium, so that in particular the pressure of the operating medium in the second cylinder chamber can be adjusted by discharging or supplying operating medium.

The force acting in the locking position, independent of the operating medium and acting in the second direction, is provided in particular by a spring which is preferably arranged in the cylinder and which acts directly or indirectly on the piston at least in the locking position. However, the force can also be provided by a weight force or other external force acting on the piston. It is only necessary that the second force acts on the piston in the locking position in the second direction.

For simple production, the at least one switching cam can be designed, for example, on an inside of the cylinder as a radially inwardly protruding projection. Alternatively, the at least one switching cam can be formed on the piston, a piston rod connected to the piston or another element that can be moved jointly with the piston, in which case the switching cams are in particular formed as radially outwardly protruding projections. Preferably at least two, particularly preferably at least four, switching cams are formed. The number of switching cams essentially depends on the diameter of the cylinder. 6 or 8 switching cams can also be provided, especially if the diameter of the cylinder is in the range of 40 mm. Preferably a maximum of 16, particularly preferably a maximum of 12, switching cams are provided. Two switching cams can for example also be formed by a rod which passes through the piston or preferably the piston rod and forms the two switching cams with its ends.

The link guide, on the other hand, is formed either on the piston, on a piston rod connected to the piston or on another element that can be moved together with the piston. Alternatively, the link guide can be formed on the cylinder or an element connected to the cylinder.

To develop the relative rotatability between the at least one switching cam and the link guide, for example an annular sleeve can be provided on which either the at least one switching cam or the link guide is formed. The sleeve is either rotatable (about the axial axis of the piston), but axially immovable on / in the cylinder. Alternatively, the sleeve can be rotatably but axially immovable on the piston, a piston rod or an element movable with the piston. Theoretically, however, the piston itself could also be mounted rotatably relative to the cylinder.

While it is sufficient for the implementation of the invention that the piston can, for example, only be held in one end position by means of the locking unit without supplying an operating medium, in a preferred embodiment it is provided that the piston is additionally held in the other end position by means of the locking unit can. For this purpose, for example, a second group of at least one switching cam can be provided, which is formed on the other end position section of the cylinder. This second group of switching cams can then interact with a second link guide which is immovably connected to the piston in the axial direction. Alternatively, a second link guide can be formed in the area of the second end position section, which either interacts with the same switching cams that also interacts with the first link guide, or which interacts with a second group of switching cams.

The (respective) slide guide preferably comprises a first slide track and a second slide track. The first slide track is in particular that slide track which preferably has a continuous configuration in the circumferential direction and is arranged in the first direction. The second link guide is arranged offset from the first link guide in the second direction and is preferably not formed continuously.

The first link guide is designed in such a way that it is temporarily in contact with the at least one switching cam during the switchover, the first link track being shaped such that the link guide and the at least one switching cam perform a relative rotary movement during the switchover. For this purpose, the first slide track has at least one first run-up flank, which is aligned such that either the slide guide or the at least one switching cam (possibly together with the sleeve) perform a rotary movement in the circumferential direction, especially if there is a continuous axial relative movement in the first direction. A first stop surface, by means of which the relative rotational movement is (initially) stopped, preferably adjoins the first starting flank. This first stop surface is associated with a first maximum of the first slide track, which protrudes in the direction of the second slide track.

In turn, the first maximum is followed in particular by a second starting flank, which is designed such that when there is interaction with a cam, a (further) relative rotational movement is generated if there is a continuous axial relative movement in the first direction. A second stop surface, through which the relative rotational movement is terminated, adjoins this second starting flank. This second stop edge is associated with a second maximum.

The above-described formation of the first slide track can continue repetitively in the circumferential direction.

The second slide track preferably has several congruent sections which are separated from one another by openings.

In particular, each section of the second slide track has a receptacle which forms a minimum of the second slide track. A switching cam comes to rest in the locking position in this receptacle, with the force independent of the operating medium pressing the switching cam into the receptacle.

In the relative direction of rotation in front of the receptacle, in particular each section of the second slide track has a first run-off slope which is arranged in the axial direction below / above the first stop surface and / or the first maximum of the first slide track. The first run-off slope is designed so that the switching cam (in the case of a continuous axial relative movement in the second direction) reaches the receptacle by a relative rotary movement to the link guide.

The receptacle is arranged in the axial direction below or above the second run-up flank of the first slide track and is thus offset in the relative direction of rotation with respect to the first maximum of the first slide track.

In particular, each section of the second slide track has a second run-off slope offset in the direction of rotation relative to the receptacle, which is arranged above or below the second stop surface of the first slide track and / or below / above the second maximum of the first slide track. When the switching cam interacts with the second run-off slope, a relative rotary movement is again generated if there is a continuous axial relative movement in the second direction. The second bevels are aligned so that they slope towards the opening. Thus, the perforations are arranged offset in the relative direction of rotation to the second stop surface or the second maximum of the first slide track.

On the side facing away from the first gate track, the sections of the second gate track have in particular a design sloping towards the interruptions so that the switching cam moved from the release position is guided to the opening during an axial relative movement in the first direction.

In the release position, the at least one switching cam is preferably aligned with an opening in the second link path.

If the piston is now moved in the first direction by providing a switch-on pressure, the switching cam or cams come into contact with the first run-up flank of the first slide track through an opening in each case. If the switching cam is not aligned with the opening in the release position, the switching cam reaches the interruption by a relative rotation when the design is sloping towards the interruption on the side facing away from the first slide track and continuous movement in the first direction. Due to the design of the first leading edge, a relative rotary movement is generated during the further movement in the first direction until the switching cam (s) come into contact with the first stop surface, whereby the relative rotary movement (and the movement in the first direction) is ended.

If the supply of the operating medium in the first cylinder chamber is now terminated or at least reduced, the piston is moved in the second direction due to the force independent of the operating medium, the switching cam (s) coming into contact with the first incline of the second slide track, which in turn During the continued movement in the second direction, a relative rotary movement is carried out until the switching cam (s) is / are arranged in the receptacle of the second slide track. In this position, the locking position is reached, which prevents the piston from being able to be moved further in the second direction. The supply of the operating medium can thus be completely switched off.

If the piston is now to be moved into the release position, operating medium must be introduced into the first cylinder chamber, as a result of which the piston is moved in the first direction. During this movement, the switch cam (s) comes into contact with a second run-up flank of the first slide track, which generates a relative rotational movement until the switch cam (s) comes into contact with the second stop surface of the first slide track. If the pressure in the first cylinder chamber is now reduced, the piston moves in the second direction, whereby the switching cam (s) comes into contact with the second incline of the second slide track, which in turn generates a relative rotary movement until the switching cam (s) continues to move passes through the opening in the second direction.

Figur 1:

eine Schnittansicht durch einen Pneumatikzylinder in einer Freigabestellung,

Figur 2:

die Schnittansicht durch den Pneumatikzylinder in einer Arretierungsstellung,

Figur 3:

eine Kulissenführung und einen Schaltnocken am Anfang eines Umschaltvorgangs von der Freigabestellung in die Arretierungsstellung,

Figur 4:

die Kulissenführung und den Schaltnocken während des Umschaltvorgangs von der Freigabestellung in die Arretierungsstellung,

Figur 5:

die Kulissenführung und den Schaltnocken in der Arretierungsstellung,

Figur 6:

die Kulissenführung und den Schaltnocken während eines Umschaltvorgangs von der Arretierungsstellung in die Freigabestellung und

Figur 7:

die Kulissenführung und den Schaltnocken am Ende des Umschaltvorgangs von der Arretierungsstellung in die Freigabestellung.

The invention and the technical environment are explained below by way of example with reference to the figures. It show schematically

Figure 1:

a sectional view through a pneumatic cylinder in a release position,

Figure 2:

the sectional view through the pneumatic cylinder in a locking position,

Figure 3:

a link guide and a switching cam at the beginning of a switching process from the release position to the locking position,

Figure 4:

the link guide and the switching cam during the switching process from the release position to the locking position,

Figure 5:

the link guide and the switching cam in the locking position,

Figure 6:

the link guide and the switching cam during a switchover from the locking position to the release position and

Figure 7:

the link guide and the switching cam at the end of the switching process from the locking position to the release position.

The one in the Figures 1 and 2 The pneumatic cylinder shown comprises a cylinder 1 in which a piston 2 is movably mounted. The piston 2 divides the cylinder 1 into a first cylinder chamber 3 and a second cylinder chamber 4. An operating medium can be introduced into the first cylinder chamber 3 under pressure via a connection 5.

On the side opposite the connection 5, the cylinder 1 is closed by a cap 11 which, on a section protruding into the second cylinder chamber 4, has a link guide 10, which is described in more detail below.

The piston 2 has a piston rod 12 which is guided to the outside through the cap 11. A sleeve 9 is axially immovable, but rotatably connected to the piston 2, with a plurality of radially projecting switching cams 8 being formed on an outside of the sleeve 9.

The pneumatic cylinder also comprises a spring 13 with which the piston 2 is spring-pretensioned in a second direction 7.

By supplying an operating medium under pressure, the piston 2 can be moved in a first direction 6 counter to the spring force. As long as the switching cams 8 do not interact with the link guide 10, the piston 2 can be moved in the first direction 6 and the second direction 7 by supplying or discharging operating medium into / from the first cylinder chamber 3 within the scope of the dimensions specified by the cylinder 1. The piston 2 is therefore in a release position.

If, on the other hand, an interaction of the switching cams 8 with the link guide 10 is brought about by providing a switch-on pressure (see explanation below), the pneumatic cylinder is converted into an in Figure 2 Transferred locking position shown, in which the piston 2 is held even when the operating medium supply is switched off due to the interaction of the switching cams 8 with the link guide 10.

In the Figures 3 to 7 the slide guide 10 is shown with a first slide track 14 and a second slide track 15 in a developed representation. In addition, only one switching cam 8 is shown as an example.

The first slide track 14 has, in a repeating manner, a first run-on flank 21 which extends as far as a vertically extending first stop surface 24. At the end facing the second link path 15, the first stop surface 24 has a first maximum 17. A second stop flank 22 extends from the first maximum 17 to a vertically extending second stop surface 25. The end of the second stop surface 25 facing the second link path 15 forms a second maximum 19. A first leading edge 21 in turn extends from the second maximum 19.

The second gate track 15 is arranged offset in the second direction 7 to the first gate track 14 and has several sections that go through Breakthroughs 18 are separated from one another. On the side facing the first slide track 14, the sections of the second slide track 15 have a first run-off slope 23 which ends in a receptacle 16. A second slope 20 is formed offset from the receptacle 16.

In the release position, the switching cam 8 is arranged below the second slide track 15. If a switch-on pressure is applied, the switching cam 8 is moved linearly upwards together with the piston 2 and, if necessary, due to the bevels on the side of the second gate track 15 facing away from the first gate track 14, it passes through an interruption 8 (see Figure 3 ).

During the following further linear movement upwards, the switching cam 8 comes into contact with the first run-up flank 21 of the first slide track 14, the switching cam 8 executing a rotary movement together with the sleeve 9 during the continued movement in the first direction 6 due to its rotatable mounting, until the switching cam 8 comes into contact with the first stop surface 24 (see Figure 4 ).

If the pressure in the first cylinder chamber 3 is reduced after this intermediate position has been reached, the switching cam 8 moves downwards together with the piston 2 and comes into contact with the first run-off slope 23 of the second slide track 15. During the following further downward movement, the switching cam 8 leads in turn, a joint rotary movement with the sleeve 9 until the switching cam 8 reaches the receptacle 16 (see Figure 5 ). In this locking position, the switching cam 8 and thus also the piston 2, which is fixedly connected to the switching cam 8 in the axial direction, cannot perform any further downward movement in the second direction 7. The piston is thus locked in the second direction.

In order to move the piston 2 back into the release position, a switch-off pressure must be applied in the first cylinder chamber 3, whereby the piston 2 and thus also the switching cam 8 connected to the piston 2 via the sleeve 9 upwards in the figures, i.e. into the first direction 6 is moved (see Figure 6 ).

If the switching cam 8 comes into contact with the second run-up flank 22 of the first gate track 14, the switching cam 8 executes a rotary movement together with the sleeve 9 during the further upward movement until the switching cam 8 is in contact with the second stop surface 25 of the first gate track 14 got.

If the pressure in the first cylinder chamber 3 is subsequently reduced, the switching cam 8 moves together with the piston 2 in the second direction (downward in the figures) until the switching cam 8 is in contact with the second incline 20 of the second slide track 15 got. During the subsequent further downward movement, the switching cam 8 executes a rotary movement together with the sleeve 9 until the switching cam 8 passes through the opening 18 (see FIG Figure 7 ). The pneumatic cylinder is then back in its release position.

List of reference symbols

1

cylinder

2

piston

3

first cylinder chamber

4th

second cylinder chamber

5

connection

6th

first direction

7th

second direction

8th

Switch cams

9

Sleeve

10

Scenery guide

11

cap

12th

Piston rod

13th

feather

14th

first slide track

15th

second slide track

16

admission

17th

first maximum

18th

Breakthrough

19th

second maximum

20th

second slope

21

first leading edge

22nd

second leading edge

23

first slope

24

first stop surface

25th

second stop surface

Claims (9)

Piston / cylinder unit, comprising - a cylinder (1) and - At least one piston (2), wherein • the piston (2) divides the cylinder (1) into a first cylinder chamber (3) and a second cylinder chamber (4), • the first cylinder chamber (3) has a connection (5) for an operating medium and • The piston (2) can be moved in a first direction (6) by feeding the operating medium into the first cylinder chamber (3) and can be acted upon or acted upon by a force independent of the operating medium in a second direction (7) counter to the first direction (6) is and • the piston (2) can be moved in a release position in the first direction (6) and in the second direction (7) in the cylinder (1), characterized in that the movement of the piston (2) is restricted in a locking position in the second direction (7), for which purpose the piston / cylinder unit - At least one radially projecting switching cam (8) and - comprises a link guide (10) for the at least one switching cam (8), wherein the at least one switching cam (8) and the link guide (10) are rotatably mounted relative to one another and are designed and arranged in such a way,
that a switchover between the release position and the locking position can be initiated by a targeted movement in the first direction (6) generated by the operating medium, the switching cam (8) interacting with the link guide (10) during the switchover and in the locking position, and
that the piston (2) is held in the locking position by the force acting against the first direction (6) even without the operating medium being made available. Piston / cylinder unit according to claim 1, wherein the slide guide (10) comprises a first slide track (14) and a second slide track (15), the first slide track (14) temporarily in contact with the at least one switching cam (8) during the switchover and is shaped in such a way that the link guide (10) and the at least one switching cam (8) temporarily perform a relative rotary movement during the switchover. Piston / cylinder unit according to one of the preceding claims, wherein the slide guide (10) comprises a first slide track (14) and a second slide track (15), the second slide track (15) having at least one receptacle (16) in which the A switching cam (8) is arranged in the locking position. Piston / cylinder unit according to claim 2 and 3, wherein the first slide track (14) has at least one first maximum (17) axially aligned in the direction of the second slide track (15), the first maximum (17) being a receptacle (16) of the second Slide track (15) is assigned and the first maximum (17) is arranged offset in the direction of rotation to the receptacle (16). Piston / cylinder unit according to claim 3 or 4, wherein the second slide track (15) has several receptacles (16) for one switching cam (8) each and the second slide track (15) has an opening (18) between adjacent receptacles (16), through which the switching cam (8) is guided during the switchover in order to get into or out of the release position. Piston / cylinder unit according to claim 5, wherein the first slide track (14) has a plurality of second maxima (19) axially aligned in the direction of the second slide track (15), the second maxima (19) each having an opening (18) in the second slide track ( 15) are assigned and are arranged offset in the direction of rotation to the respective opening (18). Piston / cylinder unit according to claim 6, wherein the second link path (15) between the receptacles (16) each has a drainage slope (20) aligned with the opening (18), the drainage slopes (20) each having a second maximum (19) first slide track (14) are assigned in the axial direction. Piston / cylinder unit according to one of the preceding claims, wherein the link guide (10) is axially immovable, but rotatably coupled to the piston (2) and the at least one switching cam (8) is formed on an inside of the cylinder (1). Piston / cylinder unit according to one of claims 1 to 7, wherein the at least one switching cam (8) is axially immovable but rotatably coupled to the piston (2) and the link guide (10) is connected to a section of a cap (11) protruding into a cylinder chamber ) is trained.

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