GAS PRESSURE SPRING

Abstract

A gas pressure spring comprising a housing having a gas-filled interior, a longitudinal axis, a closed housing end and an open housing end which is situated opposite the closed housing end. The gas pressure spring additionally includes a piston rod which is displaceable along the longitudinal axis and is guided out of the housing in a sealed manner through the open housing end, a piston unit which is fastened on the piston rod and a damping unit for damping the displacement of the piston unit.

Claims

1. A gas pressure spring comprising a. a housing (2; 2a) having i. a gas-filled interior (5), ii. a longitudinal axis (3), iii. a closed housing end (6), iv. an open housing end (7) which is situated opposite the closed housing end (6), b. a piston rod (4) which is displaceable along the longitudinal axis (3) and is guided out of the housing (2; 2a) in a sealed manner through the open housing end (7), c. a piston unit (14) which is fastened on the piston rod (4), d. a damping unit for damping the displacement of the piston unit (14).

2. A gas pressure spring according to claim 1, wherein the damping unit comprises a damping element (22; 22a).

3. A gas pressure spring according to claim 1, wherein the damping unit comprises a damping element (22; 22a), wherein a damping channel (21; 21a) is arranged between the damping element (22; 22a) and the housing (2; 2a) with reference to the longitudinal axis (3).

4. A gas pressure spring according to claim 2, wherein the damping element (22; 22a) comprises at least one through-opening (23) which is closable.

5. A gas pressure spring according to claim 2, wherein the damping element (22; 22a) comprises at least one through-opening (23) which is closable by means of the piston unit (14).

6. A gas pressure spring according to claim 1, wherein the damping unit provides damping of the displacement of the piston unit (14) in dependence on the position of the piston unit (14).

7. A gas pressure spring according to claim 1, wherein the damping unit provides damping of the displacement of the piston unit (14) in dependence on the position of the piston unit (14), wherein in a non-damped state, damping-free displacement of the piston unit (14) is effected and in a damped state, damped displacement of the piston unit (14) is effected.

8. A gas pressure spring according to claim 1, comprising a spring element (20) for exerting a resetting force on the damping unit.

9. A gas pressure spring according to claim 8, wherein the damping unit is arranged along the longitudinal axis (3) between the spring element (20) and the piston unit (14).

10. A gas pressure spring according to claim 8, wherein the damping element (22; 22a) is arranged along the longitudinal axis (3) between the spring element (20) and the piston unit (14).

11. A gas pressure spring according to claim 3, wherein the damping channel (21; 21a) is oriented, with reference to the longitudinal axis (3), at least one of radially and tangentially at least in portions.

12. A gas pressure spring according to claim 3, wherein the damping channel (21; 21a) is oriented, with reference to the longitudinal axis (3), at least one of in a spiral manner, a meandering manner and a helicoid manner.

13. A gas pressure spring according to claim 3, wherein the damping channel (21; 21a) comprises a cross-sectional damping area which is smaller than a piston flow surface.

14. A gas pressure spring according to claim 13, wherein the cross-sectional damping area is variable along the longitudinal axis (3).

15. A gas pressure spring according to claim 3, wherein the damping channel (21) is realized in the housing (2) as an indentation.

16. A gas pressure spring according to claim 3, wherein the damping channel (21a) is incorporated in the damping element (22a).

17. A gas pressure spring according to claim 3, wherein the damping channel (21a) is incorporated on a cylinder outside wall.

18. A gas pressure spring according to claim 1, wherein the damping unit is arranged along the longitudinal axis (3) between the closed housing end (6) and the piston unit (14).

19. A gas pressure spring according to claim 2, wherein the damping element (22; 22a), is arranged along the longitudinal axis (3) between the closed housing end (6) and the piston unit (14).

20. A gas pressure spring according to claim 1, wherein the damping unit is arranged along the longitudinal axis (3) between the open housing end (7) and the piston unit (14).

21. A gas pressure spring according to claim 2, wherein the damping element (22; 22a), is arranged along the longitudinal axis (3) between the open housing end (7) and the piston unit (14).

22. A gas pressure spring according to claim 2, wherein the damping unit comprises two damping elements (22; 22a).

23. A gas pressure spring according to claim 2, wherein the damping unit comprises two damping elements (22; 22a), wherein the piston unit (14) is arranged along the longitudinal axis (3) between the damping elements (22; 22a).

Description

BRIEF DESCRIPTION OF THE DRAWING

[0022] FIG. 1 shows a longitudinal section of a gas pressure spring according to the invention with the piston rod extended,

[0023] FIG. 2 shows an enlarged representation of the detail II in FIG. 1,

[0024] FIG. 3 shows a cross section through the housing of the gas pressure spring according to FIG. 1,

[0025] FIG. 4 shows an enlarged detailed representation of the detail IV in FIG. 1,

[0026] FIG. 5 shows a schematic representation of a force-path diagram for the gas pressure spring according to FIG. 1,

[0027] FIG. 6 shows a representation corresponding to FIG. 1 of a gas pressure spring according to a second exemplary embodiment,

[0028] FIG. 7 shows an enlarged detailed representation of the detail VII in FIG. 6,

[0029] FIG. 8 shows an enlarged detailed representation of the detail VIII in FIG. 6,

[0030] FIG. 9 shows an enlarged representation corresponding to FIG. 6 of the gas pressure spring with the damping unit in a damped state.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0031] A gas pressure spring 1 shown in FIGS. 1 to 4 comprises a housing 2 having a longitudinal axis 3 and a piston rod 4 which is displaceable along the longitudinal axis 3 in relation to the housing 2. The housing 2 surrounds an interior 5 which is filled with gas. The housing 2 comprises a closed housing end 6 which is shown on the right-hand side in FIG. 1. The housing 2 is closed in a gas-tight manner at the closed housing end 6. An open housing end 7 is arranged opposite the closed housing end 6. The piston rod 4 is guided out of the housing 2 through the open housing end 7. A guide element 8 and a sealing element 9 are provided for this purpose. The piston rod 4 is guided out of the housing 2 in a sealed manner. The displacement of the piston rod 4 along the longitudinal axis 3 is effected in a guided manner.

[0032] A housing fastening element 13 is provided on the end face in the region of the closed housing end 6. The housing fastening element 13 is realized as a threaded pin. The housing 2 can be fastened directly to a component to be connected thereto by way of the housing fastening element 13. It is also possible for a ball-shaped head receiving means to be fastened, for example, on the threaded pin of the housing fastening element 13.

[0033] An intermediate element 10, which is fixed axially on the housing 2, is additionally arranged in the region of the open housing end 7. The intermediate element 10 serves as a stop for a maximum extension movement of the piston rod 4. The axial fixing of the intermediate element 10 on the housing 2 is effected by means of exterior impressions 11 in the housing 2 which engage in recesses 12 of the intermediate element 10 which are provided for this purpose. The intermediate element 10 is held in a positive locking manner on the housing 2. Several substantially circular or line-groove-shaped impressions can be provided along the exterior periphery of the housing 2. It is also conceivable to realize the impression 11 along the entire exterior periphery, that is to say as a ring-shaped groove.

[0034] The piston rod 4 is arranged with a first end inside the housing 2. A piston unit 14 is fastened on the piston rod 4 at said piston-rod-side end. The piston unit 14 includes a piston element 15, a piston ring 16 which abuts in a sealing manner against the inside surface of the housing 2 and a retaining disc 17 to hold the piston ring 16 axially on the piston element 15. The retaining disc 17 is fixed axially on the piston rod by means of an integrally moulded attachment 18. The attachment 18 is in particular imprinted. The attachment 18 forms the end-face end of the piston rod 4. The piston element 15 is held axially on an abutment shoulder of the piston rod 4. The piston unit 14 is fastened on the piston rod 4. Displacement of the piston rod 4 along the longitudinal axis 3 directly brings about a displacement of the piston unit 14. A piston rod fastening element 19, which is realized as a threaded pin in a manner corresponding to the housing fastening element 13, is arranged on an exterior end of the piston rod 4 which is located opposite the interior end of the piston rod 4.

[0035] A spring element 20 is provided on an interior end face of the closed housing end 6. The spring element 20 is realized as a helical spring.

[0036] The gas pressure spring 1 comprises a damping unit with a damping channel 21. The damping channel 21 is realized as a longitudinal groove incorporated in the housing 2. According to the exemplary embodiment shown, precisely one longitudinal groove is provided. It is conceivable to provide several damping channels along the interior periphery of the housing 2. The damping channels can be arranged on the housing 2, for example, in each case parallel to the longitudinal axis 3 and in particular at identical spacings. According to the exemplary embodiment shown, the damping channel 21 has a damping channel length LD which corresponds to at least 80% of the housing length L.sub.G. The following applies in particular: L.sub.D≧0.85×L.sub.G and in particular L.sub.D≧0.9×L.sub.G. The damping unit additionally comprises a damping element 22. The damping element 22 is realized as a ring-cylindrical sleeve. The damping channel 21 is realized as a lumen which is delimited both in the radial and in the tangential direction with reference to the longitudinal axis 3 by the damping element 22 and the housing 2.

[0037] The damping element 22 comprises an outside diameter which corresponds substantially to the inside diameter of the cylindrical housing 2. The damping element 22 is displaceable in the housing 2 along the longitudinal axis 3. The damping element 22 comprises a through-opening 23. The through-opening 23 enables gas to flow through. The through-opening 23 can be closed as a result of abutting the piston unit 14 against the damping element 22. An inside diameter d.sub.i of the through-opening 23 is at least half of the inside diameter d.sub.ai of the housing 2. The following applies in particular: d.sub.i≧0.6×d.sub.ai, in particular d.sub.i≧0.65×d.sub.ai, in particular d.sub.i≧0.7×d.sub.ai, in particular d.sub.i≧0.75×d.sub.ai and in particular d.sub.i≧0.8×d.sub.ai.

[0038] The damping element 22 comprises a damping element length L.sub.DE along the longitudinal axis 3. The damping element length L.sub.DE fixes the length of the respectively active damping channel The damping channel that is active for the damping action is fixed between an external cylinder surface of the eye-shaped damping element 22 and the groove-shaped indentation on the inside surface of the housing 2. The longer the damping element length L.sub.DE, the longer the damping channel 21 and the greater the damping action of the gas pressure spring 1. Elongation of the damping channel 21 of the gas pressure spring 1 can also be achieved as a result of not realizing the damping channel in a linear manner and realizing it, in particular, in a spiral or meandering manner on the external cylinder surface of the damping element 22.

[0039] The following applies in particular L.sub.DE≦0.2×L.sub.G, in particular L.sub.DE≦0.15×L.sub.G, in particular L.sub.DE≦0.1×L.sub.G and in particular L.sub.DE≦0.08×L.sub.G.

[0040] The spring element 20 is relaxed in an initial position of the gas pressure spring 1. In said relaxed arrangement, the spring element 20 comprises an initial length L.sub.F. The initial length LF of the spring element 20 fixes the position of the damping element along the longitudinal axis 3. The damping element 22 abuts against the spring element 20. The spring element 20 serves for positioning the damping element 22. The positioning of the damping element 22 fixes from which point on the path of retraction the damping of the gas pressure spring 1 is activated.

[0041] The function of the gas pressure spring 1 is explained in more detail below by way of FIGS. 1 to 5. Proceeding from the arrangement according to FIG. 1 in which the piston rod 4 is pulled out of the housing 2 as far as possible, retraction of the piston rod 4 along the longitudinal axis 3, that is to say in the direction of retraction 24, causes the retraction force to increase in a linear manner The piston unit 14 is displaced axially along the longitudinal axis 3 by way of the piston rod 4. The piston unit 14 is displaceable in a sealed manner along the housing 2 on account of the sealing abutment of the piston element 15 against the inside surface of the housing 2. The gas arranged in the interior 5 is compressed by the displacement of the piston. The compressed gas is able to flow through the through-opening 23 of the damping element 22.

[0042] As soon as the piston unit 14 has been retracted to such an extent that it abuts against the damping element 22, further traversing of the through-opening 23 is prevented. In particular, the piston unit abuts in a sealing manner against the damping element 22. In particular, the piston unit 14 abuts in a sealing manner by way of the retaining disc 17 against the end face of the damping element 22. In said arrangement, which is the damped arrangement, gas is only able to flow exclusively through the damping channel 21. Compared to the through-opening 23, the damping channel 21 comprises a reduced cross-sectional damping area. In particular, the cross-sectional damping area of the damping channel 21 is a maximum of 10% of the cross-sectional area of the through-opening 23, in particular a maximum of 8%, in particular a maximum of 5% and in particular a maximum of 3%. The cross-sectional area of the through-opening 23 is defined as a piston flow surface.

[0043] The gas flow is damped. As a result, the displacement of the piston rod 4 with the piston unit 14 is additionally damped. This produces a further, in particular linear increase in force from the switching point x.sub.1. x.sub.1 characterizes the depth of retraction of the piston rod along the longitudinal axis 3 until the piston unit 14 abuts in a sealing manner against the damping element 22.

[0044] When the piston rod 4 is actuated in a direction of extension 25, which is opposite the direction of retraction 24, the damping element 22 is first of all pressed with its end face against the piston unit 14 as a result of the resetting force caused by the spring element 20. This means that, proceeding from a maximum retracted position of the piston rod 4, the through-opening 23 is first of all damped. As soon as, when the piston rod 3 is displaced further in the direction of extension 25, the spring element is fully relaxed, no further resetting force is exerted on the damping element 22. The damping element 22 remains in the initial position fixed by the spring element 20 according to FIG. 1. Said position corresponds to the path of retraction x.sub.1. When the piston rod 4 is pulled out further in the direction of extension 25, the through-opening 23 is opened. The compressed gas is able to flow through the through-opening 23. The displacement of the piston rod 3 is effected without additional damping. Said context is shown schematically in the force-path diagram according to FIG. 5. Overall, the gas pressure spring 1 has a damping range B.sub.D. The following applies in particular B.sub.D≧0.8×L.sub.G, in particular B.sub.D≧0.9×L.sub.G.

[0045] A second exemplary embodiment of the invention is described below with reference to FIGS. 6 to 9. Structurally identical parts receive the same reference symbols as in the case of the first exemplary embodiment, reference hereby being made to the description of said first embodiment. Structurally different, but functionally similar parts receive the same reference symbols followed by the letter a.

[0046] The essential difference in relation to the first exemplary embodiment consists in that the damping channel 21a is realized incorporated on the damping element 22a. The damping element 22a is realized in a non-round manner, in particular in the form of a flattening on the external cylinder surface of the damping element 22a. The damping channel 21a is produced as an edge gap between the damping element 22a and the cylindrical housing 2a. The damping channel 21a is arranged along the longitudinal axis 3 between the damping element 22a and the housing 2a. The housing 2a is realized in an uncomplicated manner.

[0047] It is particularly advantageous that a gas pressure spring known per se in the prior art is able to be fitted with a spring element 20 and a damping element 22 or 22a to form a gas pressure spring 1, la according to the invention with a damping function. It is possible to provide a gas pressure spring with a damping function in an uncomplicated manner.