GAS STRUT, METHOD FOR PRODUCING THE GAS STRUT, DRIVE FOR A FLAP WITH THE GAS STRUT

Abstract

Provided is a gas strut, including: an outer working space arranged radially to the stroke axis between the working cylinder and the equalizing cylinder, the outer working space being connected to the inner working space in a gas-conducting manner; an equalizing piston enclosing the working cylinder radially to the stroke axis, the equalizing piston) being mounted displaceably along the stroke axis, delimiting the outer working space on one side transversely to the stroke axis and being subjected to a pressure of the working medium and a pressure of the equalizing medium so as to increase the volume of the outer working space; and a restoring medium arranged in a restoring space radially to the stroke axis between the working cylinder and the equalizing cylinder, the equalizing piston being subjected to a pressure of the restoring medium so as to decrease the volume of the outer working space.

Claims

1. A gas strut, comprising: a. a working cylinder which encloses an inner working space filled with a working gas; b. a working piston mounted displaceably along a stroke axis in the inner working space; c. an equalizing cylinder which encloses the working cylinder at least over a partial length of the working cylinder along the stroke axis; d. an equalizing medium which expands upon an increase in temperature, arranged in an equalizing space radially to the stroke axis between the working cylinder and the equalizing cylinder; e. wherein an outer working space arranged radially to the stroke axis between the working cylinder and the equalizing cylinder; i. wherein the outer working space is connected to the inner working space in a gas-conducting manner by a number of openings through a lateral wall of the working cylinder; f. an equalizing piston enclosing the working cylinder radially to the stroke axis, wherein the equalizing piston i. is mounted displaceably along the stroke axis; ii. delimits the outer working space on one side transversely to the stroke axis, and iii. is pressurized by a pressure of the working medium and a pressure of the equalizing medium so as to increase the volume of the outer working space; and g. a restoring medium arranged in a restoring space radially to the stroke axis between the working cylinder and the equalizing cylinder, wherein the equalizing piston is pressurized by a pressure of the restoring medium so as to decrease the volume of the outer working space.

2. The gas strut according to claim 1, wherein the equalizing piston is arranged completely in the equalizing cylinder.

3. The gas strut according to claim 1, wherein the outer working space is arranged along the stroke axis between the equalizing space and the restoring space.

4. The gas strut according to claim 1, wherein a tappet which can be expelled out of the equalizing space along the stroke axis towards the equalizing piston by the pressure of the equalizing medium, wherein the tappet has a smaller cross-sectional area transversely to the stroke axis than the equalizing piston.

5. The gas strut according to claim 1, wherein the equalizing cylinder forms along the stroke axis at least one excess length over the working cylinder, wherein the at least one excess length contains a partial of the restoring space.

6. The gas strut according to claim 4, wherein a piston rod fastened to the working piston and mounted displaceably along the stroke axis in the working cylinder, wherein the excess length is arranged at that end of the working cylinder which is remote from the piston rod along the stroke axis.

7. The gas strut according to claim 1, wherein the outer working space has a smaller diameter transversely to the stroke axis than the equalizing space and/or the restoring space.

8. The gas strut according to claim 7, wherein the equalizing cylinder encloses the equalizing space, the outer working space and the restoring space radially to the stroke axis, wherein a diameter of the equalizing cylinder measured transversely to the stroke axis is widened in a region of the equalizing space and/or of the restoring space relatively to a region of the outer working space.

9. The gas strut according to claim 1, wherein the restoring medium is a gas, the working gas.

10. The gas strut according to claim 1, wherein a. the restoring space contains a multiplication piston mounted displaceably along the stroke axis; b. wherein the multiplication piston divides the restoring space into a liquid space in contact with the equalizing piston and a gas space separated in a gas-tight manner from the equalizing piston; c. wherein the liquid space is filled with a hydraulic fluid and the gas space with the restoring medium, which is in the form of a gas; and d. wherein a cross-sectional area of the multiplication piston transversely to the stroke axis is larger than a cross-sectional area of the equalizing piston transversely to the stroke axis.

11. A method for producing the gas strut according to claim 1, comprising: a. arranging the working cylinder of the gas strut in the equalizing cylinder of the gas strut; b. filling the restoring medium, the equalizing piston and the equalizing medium of the gas strut in a space between the working cylinder and the equalizing cylinder after the arranging; c. introducing the working piston and the working gas of the gas strut into the working cylinder after the step of arranging; and d. gas-tight closing of the working cylinder and the equalizing cylinder after the steps of filling and introducing.

12. The method according to claim 11, comprising: a. simultaneous introducing of the working gas into the inner and outer working space and filling of the working gas as restoring medium into the restoring space of the gas strut, through a non-return valve from the working space to the restoring space; and b. letting off part of the working medium from the inner and outer working space after the introducing and filling.

13. The method according to claim 11, comprising: widening a diameter of the equalizing cylinder measured transversely to the stroke axis in a region of the equalizing space and/or of the restoring space relatively to a region of the outer working space.

14. A drive system for a flap comprising: a. the gas strut according to claim 1 for supporting the flap; and b. an electromechanical drive, a spindle drive, for driving the flap.

Description

BRIEF DESCRIPTION

[0064] Some of the embodiments will be described in detail, with references to the following Figures, wherein like designations denote like members, wherein:

[0065] FIG. 1 shows a schematic longitudinal section through a gas strut according to embodiments of the invention; and

[0066] FIG. 2 shows a schematic longitudinal section through a further gas strut according to embodiments of the invention along its stroke axis.

DETAILED DESCRIPTION

[0067] FIG. 1 shows a schematic longitudinal section through a gas strut 50 according to embodiments of the invention along its stroke axis H.

[0068] The gas strut 50 comprises a working cylinder 1 which encloses an inner working space 1a filled with a working gas, not illustrated, e.g., nitrogen. The working cylinder 1 is for example formed substantially hollow-cylindrically and arranged coaxially to the stroke axis H. The working cylinder 1 has for example a length along the stroke axis H of 230 mm and transversely to the stroke axis an internal diameter of 16 mm and an external diameter of 19 mm.

[0069] The gas strut 50 comprises a working piston 2 mounted displaceably along a stroke axis H in the inner working space 1a. The working piston 2 is for example formed substantially cylindrically and arranged coaxially to the stroke axis H.

[0070] The working piston 2 subdivides the interior 1a of the working cylinder 1 into a first working chamber 3 and a second working chamber 4, which lie one behind the other along the stroke axis H. The working piston 2 may have an in particular annular seal 9 from an inner lateral surface of the working cylinder 1, so that the working medium cannot flow around the working piston 2 upon displacement of the working piston 2 along the stroke axis H.

[0071] The working piston 2 may have a restriction bore 5 connecting the first working chamber 3 to the second working chamber 4, in order to make controlled equalisation of pressure between the first working chamber 3 and the second working chamber 4 possible.

[0072] To the working piston 2 there is fastened a piston rod 6 which is brought out along the stroke axis H through the second working chamber 4 and, for example through a closure element 14 which closes the working cylinder 1, out of the gas strut 50.

[0073] The gas strut 50 comprises an equalizing cylinder 12 which encloses the working cylinder 1 over a partial length of the working cylinder 1 along the stroke axis H. The equalizing cylinder 12 may be formed substantially rotationally symmetrically to the stroke axis H. The equalizing cylinder 12 may enclose the working cylinder 1 over the entire length of the working cylinder 1 along the stroke axis H and additionally along the stroke axis H, in particular may form an excess length 12b over the working cylinder 1 at an end of the working cylinder 1 which is remote from the piston rod 6. The excess length may for example have a length of 20 mm along the longitudinal axis.

[0074] The gas strut 50 comprises an equalizing medium (not illustrated) arranged in an equalizing space 16a radially to the stroke axis H between the working cylinder 1 and the equalizing cylinder 12, which medium expands upon an increase in temperature. The equalizing medium fills the equalizing space. The equalizing medium is for example an expansion wax. The equalizing space 16a is formed for example substantially rotationally symmetrically to the stroke axis H. The equalizing space 16a has for example a length of 113 mm along the stroke axis.

[0075] The gas strut 50 comprises an outer working space 12a arranged radially to the stroke axis H between the working cylinder 1 and the equalizing cylinder 12, the outer working space 12a being connected in a gas-conducting manner to the inner working space 1a, in particular to the first working chamber 3, for example by a number of openings 1b through a lateral wall of the working cylinder 1. The outer working space 12a is formed for example substantially rotationally symmetrically to the stroke axis H.

[0076] The gas strut 50 comprises an equalizing piston 10 enclosing the working cylinder 1 radially to the stroke axis H, the equalizing piston 10 being mounted displaceably along the stroke axis H, delimiting the outer working space 12a on one side transversely to the stroke axis H and being pressurized by a pressure of the working medium and a pressure of the equalizing medium so as to increase the volume of the outer working space 12a. The equalizing piston 10 is for example formed substantially hollow-cylindrically and arranged coaxially to the stroke axis H. The equalizing piston is for example displaceable over an equalizing distance of 84 mm along the stroke axis H.

[0077] The gas strut 50 comprises a restoring medium (not illustrated) arranged in a restoring space 15a radially to the stroke axis H between the working cylinder 1 and the equalizing cylinder 12, the equalizing piston 10 being pressurized by a pressure of the restoring medium so as to decrease the volume of the outer working space 12a. The restoring medium is for example a gas, in particular the working gas.

[0078] The restoring space 15a is formed for example substantially rotationally symmetrically to the stroke axis H. The restoring space 15a may be arranged partially in an excess length 12b of the equalizing cylinder 12 along the stroke axis H beyond the working cylinder 1. The restoring space 15a may for example at maximum displacement of the equalizing piston 10 towards the restoring space 15a have a minimum length of 60 mm along the stroke axis H.

[0079] In an embodiment, the equalizing space 16a, the outer working space 12a and the restoring space 15a are arranged one behind the other along the stroke axis H, with in particular the restoring space 15a possibly being arranged at that end of the gas strut 50 which is remote from the piston rod 6, the equalizing space 16a at that end of the gas strut 50 at which the piston rod 6 is brought out of the gas strut 50, and the outer working space 12a between the restoring space 15a and the equalizing space 16a.

[0080] The equalizing space 16a and the restoring space 15a may have a greater diameter transversely to the stroke axis than the outer working space 12a. For example, the equalizing space 16a may have an external diameter of 30 mm, the restoring space 15a an external diameter of 25 mm to 30 mm and the outer working space 12a an external diameter of 25 mm.

[0081] The equalizing space 16a and the restoring space 15a may be sealed off from the outer working space 12a with at least one seal 9 in each case, for example with at least one O-ring in each case.

[0082] The equalizing space 16a may be closed at an end which is remote from the outer working space 12a with a closure element 14, in particular with a closing disc. The working cylinder 1 and the equalizing space 16a may be closed in particular with a common closure element 14.

[0083] The gas strut 50 comprises a tappet 110 which can be expelled out of the equalizing space 16a along the stroke axis H towards the equalizing piston 10 by the pressure of the equalizing medium. The tappet 110 is for example formed substantially hollow-cylindrically and arranged coaxially to the stroke axis H. The tappet 110 may lead out of the equalizing space 16a through the outer working space 12a up to the equalizing piston 10 and in particular be fastened to the equalizing piston 10 or formed in one piece therewith.

[0084] In FIG. 1, the gas strut 50 is shown at a low temperature, at which the outer working space 12a has a small volume. Upon warming of the gas strut 50, the equalizing medium expands in the equalizing space 16a and thereby displaces the equalizing piston 10 along the stroke axis H such that the volume of the outer working space 12a is increased (downwards in FIG. 1). As a result, a pressure increase, brought about by the warming, of the working gas in the inner working space 1a and outer working space 12a can be compensated.

[0085] Upon cooling of the gas strut 50, the equalizing medium contracts in the equalizing space 16a, so that the pressure of the restoring medium in the restoring space 15a displaces the equalizing piston 10 such that the volume of the outer working space 12a is reduced (upwards in FIG. 1). As a result, a pressure reduction, brought about by the cooling, of the working gas in the inner working space 1a and outer working space 12a can be compensated. FIG. 2

[0086] FIG. 2 shows a schematic longitudinal section through a further gas strut 50 according to embodiments of the invention along its stroke axis H.

[0087] Features of the gas strut 50 already shown in FIG. 1 are provided with the same reference numerals as in FIG. 1 and may be configured just as described in relation to FIG. 1.

[0088] The restoring space 15a of the gas strut 50 shown in FIG. 2 contains a multiplication piston 17 mounted displaceably along the stroke axis H, the multiplication piston 17 dividing the restoring space 15a, for example with the aid of a seal 9, into a liquid space 18a in contact with the equalizing piston 10 and a gas space 19a separated in a gas-tight manner from the equalizing piston 10.

[0089] In this configuration, the liquid space 18a is filled with a hydraulic fluid and the gas space 19a with the restoring medium, which is in the form of a gas.

[0090] A cross-sectional area of the multiplication piston 17 transversely to the stroke axis H is greater than a cross-sectional area of the equalizing piston 10 transversely to the stroke axis H, so that the multiplication piston 17 with the equalizing piston 10 and the hydraulic fluid arranged therebetween forms a hydraulic multiplication.

[0091] The multiplication piston 17 has for example a greater external diameter transversely to the stroke axis H than the equalizing piston 10.

[0092] The multiplication piston 17 is for example of disc-shaped configuration, with a disc plane oriented transversely to the stroke axis H and arranged along the stroke axis H before that end of the working cylinder 1 which is remote from the piston rod 6.

[0093] 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.

[0094] 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 reference numerals

[0095] 1 working cylinder

[0096] 1a inner working space

[0097] 1b opening

[0098] 2 working piston

[0099] 3 first working chamber

[0100] 4 second working chamber

[0101] 5 restriction bore

[0102] 6 piston rod

[0103] 9 seal

[0104] 10 equalizing piston

[0105] 12 equalizing cylinder

[0106] 12a outer working space

[0107] 12b excess length

[0108] 14 closure element

[0109] 15a restoring space

[0110] 16a equalizing space

[0111] 17 multiplication piston

[0112] 18a liquid space

[0113] 19a gas space

[0114] 50 gas strut

[0115] 110 tappet

[0116] H stroke axis