GAS PRESSURE SPRING AND METHOD FOR PRODUCING THE GAS PRESSURE SPRING

Abstract

A gas pressure spring is provided including a working cylinder which, together with a slidably mounted compensating piston, encloses a working chamber filled with a working medium. A slidably mounted working piston is fastened to a working rod. In the event of a temperature increase, a compensating medium in a compensating chamber expands. The compensating piston is acted upon by the pressure of the working medium and the pressure of the compensating medium) such that the volume of the working chamber is increased. The temperature dependency of the gas spring force should be reduced by a design which is as simple as possible. For this purpose, the compensating chamber is at least partially surrounded by the working rod. Thus, the compensating medium can be compactly accommodated, and the assembly of the gas spring is simplified.

Claims

1. A gas pressure spring comprising: a) a working cylinder which, together with a compensating piston mounted so that it is slidable relative to the working cylinder, encloses a working chamber filled with a gaseous working medium; b) a working rod protruding into the working chamber through an opening of the working cylinder and mounted so that it is slidable along a stroke axis; c) a working piston fastened to the working rod and mounted in the working chamber so that it is slidable along the stroke axis; d) a compensating medium disposed in a compensating chamber and expanding in the event of a temperature increase; e) wherein the compensating piston is acted upon by the pressure of the working medium and the pressure of the compensating medium such that the volume of the working chamber increased; wherein f) the compensating chamber is at least partially surrounded by the working rod; g) wherein the gas pressure spring comprises a compensating container having an inner chamber, fastened to the working piston, and mounted in the working cylinder so that it is slidable along the stroke axis; h) wherein the compensating piston divides the inner chamber into an inner working chamber conductively connected to the working chamber for the working medium and a return chamber sealed with regard to the working chamber; i) wherein the gas pressure spring comprises a return medium disposed in the return chamber; j) wherein the compensating piston is acted upon by the return medium such that the volume of the inner working chamber is reduced; k) wherein the return medium the gaseous working medium; and l) wherein the gas pressure spring comprises a check valve between the working chamber and the return chamber for simultaneously filling the working chamber and the return chamber with the working medium.

2. The gas pressure spring according to claim 1, wherein a) the working rod comprises a tappet which can be driven out of the working rod by the pressure of the compensating medium; and b) the tappet applies the pressure of the compensating medium to the compensating piston such that the volume of the inner working chamber is increased.

3. A method for producing a gas pressure spring according to claim 1, wherein a) providing the working cylinder for the gas pressure spring; b) providing the working rod having a compensating chamber the gas pressure spring; c) filling the compensating medium into the compensating chamber; d) mounting the working rod in the working cylinder; e) simultaneously filling the working chamber the return chamber of the gas pressure spring through the check valve of the gas pressure spring between the working chamber the return chamber with the gaseous working medium, and f) discharging part of the working medium from the working chamber after filling.

4. The method according to claim 3, wherein fastening the tappet and/or the compensating container to the working rod prior to mounting.

5. A drive system for a flap including: a) a gas pressure spring according to claim 1 for supporting the flap, and b) an electromechanical drive for driving the flap.

Description

BRIEF DESCRIPTION

[0032] Some of the embodiments will be described in detail, with references to the following Figures, wherein like designations denote like members, wherein:

[0033] FIG. 1 shows an embodiment of a gas pressure spring according to embodiments of the invention in a first position of the compensating piston; and

[0034] FIG. 2 shows the embodiment of FIG. 1 in a second position of the compensating piston.

DETAILED DESCRIPTION

[0035] In FIGS. 1 and 2, a first embodiment of a gas pressure spring 50 according to embodiments of the invention is illustrated which comprises a working cylinder 1 which, together with a compensating piston 10 mounted so that it is slidable relative to the working cylinder 1, encloses a working chamber 1a filled with a working medium 1M. Here, a working rod 6 mounted so that it is slidable along a stroke axis H protrudes into the working chamber 1a through an opening of the working cylinder 1.

[0036] On the working rod 6, a working piston 2 mounted in the working chamber 1a so that it is slidable along the stroke axis H is fastened. The working piston 2 comprises a ring-shaped seal 4 (e.g., an O ring) towards the radially inner wall of the working cylinder 1 so that, when the working piston 2 is shifted, the working medium 1M cannot flow around the working piston 2. A shift of the working piston 2 will therefore first result in a change in the pressure in the working chamber 1a. However, the working piston 2 may comprise a throttle bore (not illustrated), and/or the radially inner wall of the working cylinder 1 may have a longitudinal groove along the stroke axis H of the working piston 2 for pressure compensation.

[0037] A compensating medium 16M is disposed in a compensating chamber 16 and expands in the event of a temperature increase. The compensating piston 10 is acted upon by the pressure of the working medium 1M and the pressure of the compensating medium 16M such that the volume of the working chamber 1a is increased.

[0038] Here, FIG. 1 shows a high temperature situation while FIG. 2 shows a low temperature situation.

[0039] The compensating chamber 16 is partially surrounded by the working rod 6 here. In particular, the compensating chamber 16 is surrounded by the working rod 6 and a tappet 110.

[1] The gas pressure spring 50 comprises a compensating container 120 which has an inner chamber 121, is fastened to the working piston 2, and mounted in the working cylinder 1 so that it is slidable along the stroke axis H. The compensating piston 10 divides the inner chamber 121 into an inner working chamber 122 conductively connected to the working chamber 1a for the working medium 1M, and a return chamber 15 sealed with respect to the working chamber 1a. For this purpose, the compensating piston comprises a circumferential seal 11, e.g., an O ring.

[0040] For connecting the working chamber 1a to the inner working chamber 122, e.g., a hole 124 is provided in a connecting member 123 connecting the compensating container 120 to the working rod 6. The working medium 1M may flow through between the compensating container 120 and the working cylinder 1 (e.g., through a space between compensating container 120 and working cylinder 1 radial to the stroke axis H or through at least one longitudinal groove along the stroke axis H in an inner wall of the working cylinder 1 or an outer wall of the compensating container 120).

[0041] The working rod 6 comprises the tappet 110 which can be driven out of the working rod 6 by the pressure of the compensating medium 16M. The tappet 110 applies the pressure of the compensating medium 16M to the compensating piston 10 such that the volume of the inner working chamber 122 is increased.

[0042] Driving the tappet 110 out of the working rod 6 in the event of a temperature increase will then lead to a shift of the compensating piston 10 relative to the compensating container 120 along the stroke axis H (upwards in the drawing). In this way, the inner working chamber 122 and therefore the entire working chamber 1a available to the working chamber 1M is enlarged. As compared to FIG. 1, FIG. 2 shows a state at a low temperature and with the tappet 110 contracted further into the working rod 6.

[0043] The compensating medium 16M is, for example, an expanding material, such as an expanding wax which particularly comprises at least a liquid phase and at least a solid phase in an entire operating temperature range of the gas pressure spring 50.

[0044] The gas pressure spring 50 comprises a return medium 15M disposed in the return chamber 15, the compensating piston 10 being acted upon by the return medium 15M such that the volume of the working chamber 1a such as the inner working chamber 122, is reduced. In this way, it can be ensured in the simplest possible manner that, in the event of a contraction of the compensating medium 16M at dropping temperatures (FIG. 1->FIG. 2), the compensating piston 10 is also returned to the initial position, i.e., that a reversible operation is ensured. With the reduction of the volume of the compensating medium 16M, the return medium 15M will then provide for a corresponding reduction of the volume of the compensating chamber 16. For supporting the return medium 15M, the gas pressure spring 50 may additionally also comprise a return spring in the return chamber 15 (not shown in the illustrated embodiment).

[0045] In an embodiment, the return medium 16M is a gas, particularly the working medium 1M. This facilitates the production of the gas pressure spring 50 since only one medium or gas is used.

[0046] In FIG. 1, as compared to the situation in FIG. 2, the working medium 1M is thus disposed in a larger working chamber 1a (particularly a larger inner working chamber 122) in the same position of the working piston 2. Therefore, the temperature-related increase in the pressure of the working medium 1M can be partly or even fully compensated by the increase in the volume of the inner working chamber 122. Thus, the gas pressure spring 50 provides for a significantly less temperature-dependent spring force than conventional art.

[0047] Although the invention has been illustrated and described in greater detail with reference to the preferred exemplary embodiments, the invention is not limited to the examples disclosed, and further variations can be inferred by a person skilled in the art, without departing from the scope of protection of the invention.

[0048] For the sake of clarity, it is to be understood that the use of “a” or “an” throughout this application does not exclude a plurality, and “comprising” does not exclude other steps or elements.

LIST OF NUMERALS

[0049] 1 Working cylinder [0050] 1a Working chamber [0051] 1M Working medium [0052] 2 Working piston [0053] 4 Seal [0054] 10 Compensating piston [0055] 11 Seal [0056] 15 Return chamber [0057] 15M Return medium [0058] 16 Compensating chamber [0059] 16M Compensating medium [0060] 50 Gas pressure spring [0061] 110 Tappet [0062] 120 Compensating container [0063] 121 Inner chamber [0064] 122 Inner working chamber [0065] 123 Connecting member [0066] 124 Hole [0067] H Stroke axis