WORKING CYLINDER WITH CUSHIONED END-STROKE

Abstract

A working cylinder has a cushioned end-stroke. The piston unit has a piston main part and a ring body. The exterior of the ring body receives a piston ring with a piston ring gap, and the ring opening of the ring body receives a guiding pin of the piston main part. A ring gap is formed between the ring body and the guiding pin, and the ring body has axial and radial play relative to the piston main part. The ring body has an axial ring surface on the piston main part side, and the piston main part has an axial counter ring surface on the ring body side opposite the axial ring surface. The piston unit is constructed so that during an inward movement into the cushioning zone, the piston ring passes axially over the pressure medium connection and the piston unit encloses a damping pressure medium volume. The piston unit is in a first operating state during an inward movement and a second operating state during an outward movement. In the first operating state, the axial ring surface and the axial counter ring surface lie against each other and define a seal plane the piston ring gap is configured for a throttled outflow of the damping pressure medium volume. In the second operating state, the axial ring surface and the axial counter ring surface have an axial gap for a pressure medium inflow.

Claims

1-6. (canceled)

7. A working cylinder with cushioned end-stroke, comprising: a cylinder having a cylinder tube with an inner cylinder wall, a first closure part and a second closure part, the cylinder tube having a first cylinder tube end and a second cylinder tube end, the first closure part being arranged at the first cylinder tube end and the second closure part being arranged at the second cylinder tube end, the cylinder tube and the closure parts defining a cylinder interior with an axial boundary, the cylinder having a damping zone at one of the tube ends, the cylinder having at least one laterally arranged pressure medium connection associated with the damping zone and being axially spaced the axial boundary; a piston unit having a piston main part with a guiding pin, the piston unit having a ring body with a radial outer lateral surface, a ring opening, and a piston main part side with an axial ring surface and, on an opposite side, the piston main part having an axial counter ring surface on a ring body side, the ring body having a circumferential inner ring groove on the radial outer lateral surface, the ring body receiving the guiding pin in the ring opening; a ring gap being defined between a radial inner lateral surface of the ring body and the guiding pin, the ring body having an axial play and a radial play with respect to the piston main part, the piston unit slidingly passing through the first closure part and defining at least one working chamber in the cylinder interior, the piston main part being guided in an axially displaceable manner by a guide in the cylinder interior; a piston ring disposed in the inner ring groove, the piston ring resting resiliently against the inner cylinder wall and having a piston ring gap; the piston unit constructed for axially passing over the pressure medium connection with the piston ring during an inward movement into the damping zone and enclosing a damping pressure medium volume in a damping zone space in the damping zone, the piston unit constructed for being in a first operating state within the damping zone during an inward movement and in a second operating state during an outward movement; in the first operating state, the axial ring surface and the axial counter ring surface abutting against each other and defining a sealing plane, the damping pressure medium volume having an overpressure compared to the pressure medium connection, and the piston ring gap being configured for a throttled outflow of the damping pressure medium volume; in the second operating state, an axial gap exists between the axial ring surface and the axial counter ring surface, the axial gap and the ring gap defining a pressure medium inlet channel configured for an inflow of a pressure medium into the damping zone space.

8. The working cylinder with cushioned end-stroke according to claim 7, wherein the axial play of the ring body is limited axially by a circlip.

9. The working cylinder with cushioned end-stroke according to claim 7 wherein the guiding pin has an axial groove which defines a part of the pressure medium inlet channel.

10. The working cylinder with cushioned end-stroke according to claim 7, wherein the cylinder includes a position sensor configured to record a position of the ring body.

11. The working cylinder with cushioned end-stroke according to claim 7, wherein the inner cylinder wall is tapered in the damping zone and, in the first operating state, the piston ring is constructed to narrow the piston ring gap when inward movement progresses.

12. The working cylinder with cushioned end-stroke according to claim 7, comprising a second damping zone axially opposite the first damping zone, the cylinder including a second laterally arranged pressure medium connection, the second pressure medium connection being associated with the second damping zone and being axially spaced from a second axial boundary of the cylinder interior opposite the axial boundary; the piston unit including a second ring body axially opposite the ring body, the piston main part having a second guiding pin axially opposite the guiding pin; during an inward movement into the second damping zone, the piston unit constructed for axially passing over the second pressure medium connection with a second piston ring and enclosing a further damping pressure medium volume in a second damping zone space in the second damping zone, the piston unit constructed for having a third operating state within the second damping zone during an inward movement and a fourth operating state within the second damping zone during an outward movement; with respect to the second damping zone, the third operating state being characterized by the features of the first operating state and the fourth operating state being characterized by the features of the second operating state.

Description

[0092] The invention is described as an exemplary embodiment in more detail by means of the following figures. They show:

[0093] FIG. 1 Working cylinder with cushioned end-stroke as a differential cylinder with cushioned end-stroke on one side (sectional view)

[0094] FIG. 2 Working cylinder with cushioned end-stroke as a differential cylinder with cushioned end-stroke on one side (enlarged detail in sectional view)

[0095] FIG. 3 Working cylinder with cushioned end-stroke as a differential cylinder with cushioned end-stroke on both sides (sectional view)

[0096] FIG. 4 Working cylinder with cushioned end-stroke as a synchronized cylinder with cushioned end-stroke on both sides (sectional view)

[0097] FIG. 5 Working cylinder with cushioned end-stroke as a differential cylinder with cushioned end-stroke on both sides in the first operating state (enlarged detail in sectional view)

[0098] FIG. 6 Working cylinder with cushioned end-stroke as a differential cylinder with cushioned end-stroke on both sides in the second operating state (enlarged detail in sectional view)

[0099] FIG. 7 Piston unit (isometric view).

[0100] FIG. 1 shows an overview of a first embodiment of the differential working cylinder with cushioned end-stroke. In this embodiment, it is a differential working cylinder with cushioned end-stroke on one side. In this embodiment, the cushioned end-stroke is provided at the end position associated with the second closure part 5. It is a cushioned end-stroke at the piston crown which damps the inward movement.

[0101] The working cylinder with cushioned end-stroke has a cylinder 1 and a piston unit 2.

[0102] The cylinder 1 consists of the cylinder tube 3, the first closure part 4 and the second closure part 5. The cylinder tube 3 and the two closure parts 4, 5 are connected to each other in such a way that they enclose a cylinder interior 8. The first closure part 4 is associated with the first cylinder tube end 6, and the second closure part 5 is associated with the second cylinder tube end 7. In this embodiment, the inside of the second closure part 5 forms an axial boundary 11, and the inside of the first closure part 5 forms a further axial boundary 27 which limits the axial movement space of the piston unit 2 arranged in the cylinder interior space 8. The axial boundaries 11, 27 are designed as stop surfaces for the piston unit 2 which moves axially during operation.

[0103] On the cylinder tube 3, the pressure medium connection 10 is arranged at the second cylinder tube end 7, and the further pressure medium connection 26 is arranged on the first cylinder tube end 6.

[0104] The piston unit 2 has a piston main part 12 and a ring body 13. In the exemplary embodiment, the piston unit 2 is composed of a piston rod and a piston, which are firmly connected to each other. In the embodiment, the piston main part and the ring body together form the piston.

[0105] In this embodiment, the piston rod of the piston unit 2 is guided through the first closure part 4 and slidably mounted therein.

[0106] The ring body 13 is pushed onto the guiding pin 18, which is designed as a taper on the piston main part 12.

[0107] The piston main part 12 is guided in the cylinder tube 3 by means of a guide 14.

[0108] FIG. 2 shows an enlarged detail of FIG. 1 in the area of the second closure part 5. Furthermore, the piston main part 12 is in an end position so that the piston main part 12 rests with its guiding pin 18 against the axial boundary 11.

[0109] In this Figure, the arrangement and design of the ring body 13 are shown in more detail. In this embodiment, the ring body 13 is designed as a metal ring which has an inner ring groove 15 on its outer lateral surface 13c, in which the piston ring 16 is inserted. The inner ring groove 15 is designed such that the piston ring 16 has a larger play in the radial direction so that it can deform elastically in the radial direction. The elastic piston ring has a piston ring gap 16a (see FIG. 7 in particular) and is tensioned against the inner cylinder wall 17.

[0110] The ring body 13 is pushed onto the guiding pin 18 and rests with an axial ring surface on the piston body side 13d against the counter ring surface on the ring body side 12a of the piston main part 12. Axially opposite, the axial play of the ring body 13 is limited by a circlip 22.

[0111] Furthermore, the ring opening 13a of the ring body is designed in such a manner that it exceeds the diameter of the guiding pin 18 so that the ring body has a radial play with respect to the guiding pin 18.

[0112] The damping zone 9 is an axial section and extends from the pressure medium connection 10 to the end position of the piston ring 16 in front of the second closure part 5. When the piston unit 2 moves inward, a damping effect is caused in the damping zone 9 and is directed opposite to the inward movement of the piston unit 2 and slows it down. This is described in more detail in conjunction with FIG. 5.

[0113] FIG. 3 shows a second embodiment. This is a differential working cylinder with cushioned end-stroke in both end positions. For this purpose, an additional ring body 28 is provided. The further ring body 28 has a design identical to that of the ring body 13 and is pushed onto a further guiding pin 29 and fixed there by a further circlip 30. Both ring bodies 13, 28 and both guiding pins 18, 29 are positioned axially opposite each other on the piston main part 12.

[0114] The further ring body additionally produces a damping effect in the further damping zone 25 correspondingly to the damping zone 9. The further damping zone 25 extends between the further pressure medium connection 26 and the end position of the further piston ring 31 in front of the further axial boundary 27 at the first closure part 4.

[0115] Moreover, the differential working cylinders in FIG. 1 and FIG. 3 have an identical basic design.

[0116] FIG. 4 shows a synchronized working cylinder that has also cushioned end-strokes on both sides. The difference to the differential working piston in FIG. 3 is that the piston rod section of the piston main part 12 is guided through both closure parts 4, 5 and slidably mounted. Therefore, the second closure part 5 is also designed as a guide closure part in this embodiment. The piston main part 12 is similarly designed to that in FIG. 3, however, it differs in that the piston rod passes through it. Also here, both sections of the piston unit 2 are firmly connected to each other.

[0117] In FIG. 5, the first operating state, which is the damping operating state, and in FIG. 6, the second operating state, which is the outward movement operating state are shown during the operation of the working cylinder with cushioned end-stroke. These Figures are used to illustrate the manner in which damping functions.

[0118] In FIG. 5, the piston unit executes an inward movement, and the piston ring 16 in the inner ring groove 15 of the ring body 13 has just passed over the pressure medium connection 10 and encloses a damping pressure medium volume in the damping zone space 20. The pressure in the damping pressure medium volume is greater than the pressure at the pressure medium connection 10. Consequently, the ring body 13 is pressed with its axial ring surface on the piston main part side 13d against the axial counter ring surface on the ring body side 12a so that an annular sealing plane is formed there.

[0119] The pressure medium from the damping pressure medium volume can now only flow back to the pressure medium connection 10 via the piston ring gap 16a in the piston ring 16, and thus the inward movement of the piston unit 2 is counteracted by a damping force effect. The inward movement is slowed down until the piston unit 2 reaches the axial boundary 11.

[0120] FIG. 6 shows the second operating state.

[0121] In this second operating state, the piston unit 2 executes an outward movement. This movement is caused by the pressure medium flowing from the pressure medium connection 10 into the damping zone space 20 (as soon as the pressure at the pressure medium connection 10 is greater than that in the damping pressure medium volume).

[0122] As soon as the pressure at the pressure medium connection 10 is greater than that in the damping pressure medium volume, the ring body 13 is displaced axially and pressed against the circlip 22. As a result, an axial gap 21 between the axial counter ring surface on the ring body side 12a and the axial ring surface on the piston main part side 13d is opened.

[0123] Moreover, the ring body 13 has a radial play. This is provided by a ring gap 19 between the inner lateral surface 13b and the guiding pin 18. The axial gap 21 and the ring gap 19 form a continuous pressure medium inlet channel for the pressure medium flowing into the damping zone space 20. In this embodiment, an axial groove 24 in the guiding pin additionally enlarges the flow cross-section of the pressure medium inlet channel.

[0124] This allows the pressure medium to flow into the damping zone space 20 with low pressure loss and the outward movement is hardly slowed down.

[0125] In an embodiment with cushioned end-stroke on both sides, the mode of operation shown in FIGS. 5 and 6 corresponds to the interaction of the third and fourth operating states in the further damping zone 25 by means of the further ring body 28.

[0126] The piston unit is in the third operating state during the inward movement into the further damping zone 25, and in the fourth operating state during the outward movement out of the further damping zone 25. In the further end position, the third operating state is the damping operating state and the fourth operating state is the outward movement operating state.

[0127] In addition, FIG. 5 and FIG. 6 show a position sensor 23 arranged on the cylinder tube.

[0128] FIG. 7 shows the piston unit 2 of an embodiment of a differential working cylinder with cushioned end-stroke on both sides in an oblique view.

[0129] The ring body 13, the piston ring 16 with its piston ring gap 16a, the circlip 22, the guide 14 and the axial groove 24 are shown. Furthermore, axially opposite the piston main part, 12 the further ring body 28 and the further piston ring 31 arranged there with its further piston ring gap 31a are shown. The piston rings 16, 31 and the circlip 22 are each designed as an elastic metal ring. The further circlip and the further guiding pin are hidden and, therefore, they do not have reference numerals in FIG. 7.

[0130] The ring body 13 receives the piston ring 16 in the inner ring groove 15 and is fixed on the guiding pin 18 by the circlip 22. The same applies to the further ring body 28 and the further piston ring 31 as well as the further circlip and the further guiding pin.

[0131] The guide 14 is arranged in a groove of the piston main part 12.

REFERENCE NUMERALS

[0132] 1 cylinder [0133] 2 piston unit [0134] 3 piston tube [0135] 4 first closure part [0136] 5 second closure part [0137] 6 first cylinder tube end [0138] 7 second cylinder tube end [0139] 8 cylinder interior [0140] 9 damping zone [0141] 10 pressure medium connection [0142] 11 axial boundary [0143] 12 piston main part [0144] 12a axial counter ring surface on the ring body side [0145] 13 ring body [0146] 13a ring opening [0147] 13b inner lateral surface [0148] 13c outer lateral surface [0149] 13d axial ring surface on the piston main part side [0150] 14 guide [0151] 15 inner ring groove [0152] 16 piston ring [0153] 16a piston ring gap [0154] 17 inner cylinder wall [0155] 18 guiding pin [0156] 19 ring gap [0157] 20 damping zone space [0158] 21 axial gap [0159] 22 circlip [0160] 23 position sensor [0161] 24 axial groove [0162] 25 further damping zone [0163] 26 further pressure medium connection [0164] 27 further axial boundary [0165] 28 further ring body [0166] 29 further guiding pin [0167] 30 further circlip [0168] 31 further piston ring [0169] 31a further piston ring gap