Gas spring system having at least one gas spring

Abstract

The invention relates to a gas spring system having at least one gas spring (1) with a piston assembly (3) which is arranged in a displaceable manner in a cylinder. According to the invention, the piston assembly (3) is designed as a piston pack which is closed according to the direction, said piston pack being designed in a springless manner and having at least one annular sealing element (12), at least one annular sealing element (12) is provided for sealing between the holding region (10) of the cylinder (2) and the piston assembly (3) during an ejection movement of the gas spring (1), and wherein the sealing element (12) is arranged in a radially outer annular space (23) of the piston pack and can be displaced in the radially outer annular space of the piston pack, the sealing element (12) is designed such that the sealing element (12) can be pressed against the cylinder (2) with a first pressing force during a push-out movement of the gas spring (1) and can be pressed against the cylinder (2) with a second, smaller pressing force during a push-in movement of the gas spring (1).

Description

Technical Field

[0001] The present invention relates to a gas spring system, which has at least one gas spring, the at least one gas spring having: a cylinder closed at a first end; a piston assembly displaceably arranged in the cylinder, the piston assembly dividing the cylinder into a first working chamber close to the first end and a second working chamber away from the first end; and a piston rod arranged on one side of the piston assembly, the piston rod passing through the second working chamber and leading out of the cylinder concentrically with the longitudinal axis of the cylinder at a second end opposite to the first end, the second end being sealed by a seal and a piston rod guide. Background Art

[0002] Gas spring systems with gas springs are well known. Gas springs are used, in particular, for power support, but also for damping and locking. In addition to lifting, they can also be used to specifically damp movement at a defined speed. Gas spring systems are used, for example, in flap systems with two end positions, such as vehicle tailgates that need to be easily adjusted from a closed to an open position. Depending on the application, it may be desirable to limit the flap's opening angle or to provide different opening angles.

[0003] Known gas springs for these applications typically have a directionally acting piston valve with a piston seal. This piston valve is closed by spring force during the automatic extension movement of the gas spring and opens in the holding range due to a pressure-dependent force acting in the opening direction. Such piston seals with spring-loaded valves, such as those known from DE 33 01 544 A1, have proven disadvantageous, particularly with regard to frictional resistance and temperature dependence. The use of piston valves can also be disadvantageous with regard to noise emissions.

[0004] For example, a gas spring with a springless piston package is known from DE 25 13 302 A1. In this respect, the high friction of the sealing element has proven to be disadvantageous. Summary of the Invention

[0005] It is therefore the object of the present invention to provide a gas spring system which is improved in this respect and which has at least one gas spring of simple construction.

[0006] According to the present invention, this object is achieved by a gas spring system according to claim 1. The gas spring system according to the present invention comprises at least one gas spring having: a cylinder closed at a first end; a piston assembly displaceably arranged in the cylinder, the piston assembly dividing the cylinder into a first working chamber proximal to the first end and a second working chamber distal thereto; and a piston rod arranged on one side of the piston assembly, the piston rod extending through the second working chamber and exiting the cylinder concentrically with the longitudinal axis of the cylinder at a second end opposite the first end, the second end being sealed by a seal and a piston rod guide. The cylinder has at least one overflow channel that can be connected to the working space for the automatic extension movement of the gas spring, wherein at least one retaining region of the cylinder that interrupts the overflow channel is provided to limit the stroke of the piston assembly, and in this retaining region, the automatic extension movement is prevented. The piston assembly is designed as a directionally closed piston package. Furthermore, the piston pack is designed without a spring and has at least one annular sealing element, which is provided for sealing between the retaining area of ​​the cylinder and the piston assembly during the extension movement of the gas spring. The sealing element is arranged in a radially outer annular space of the piston pack and is displaceable in the radially outer annular space of the piston pack such that the sealing element can press against the cylinder with a first pressing force during the extension movement of the gas spring and with a second, smaller pressing force during the insertion movement of the gas spring.

[0007] In this case, the directionally closed piston pack means that no additional force (such as a spring force) is required to close the piston pack during the ejection movement. By eliminating the valve spring, the design of the piston pack can be significantly simplified, which optimizes the cost of the gas spring system and reduces the design effort due to the significantly simplified design.

[0008] Since the valve spring is eliminated, the gas spring system is also less temperature-dependent. In known gas springs with valve springs, the holding force decreases with increasing temperature. To compensate for this, a stronger valve spring is required, which in turn results in an increase in the actuating force at moderate temperatures, and especially at lower temperatures.

[0009] In the gas spring according to the invention with a piston pack, the push-out force increases with increasing temperature, but at the same time the retaining force of the piston pack increases, so that no compensation is necessary in this respect.

[0010] The reduced pressing force of the sealing element during the insertion movement also leads to a reduction in friction.

[0011] Due to the smaller fluctuation range of the adjustment force, the system according to the invention allows improved adjustment comfort, in particular in the medium and lower temperature ranges.

[0012] According to an advantageous embodiment of the invention, the piston package has a further sealing element which is provided for static sealing between the piston assembly and the piston rod.

[0013] The two annular sealing elements allow for a single-sided or double-sided static seal and a gas-tight design of the piston package, which results in a low friction sealing element.

[0014] A particularly simple construction of the piston package is preferably achieved in that the piston package has a piston and a stop disk, wherein the piston rests on the stop disk with a projection extending in the axial direction relative to the longitudinal axis, so that the radial outer annular space is formed.

[0015] The stop disk rests on a shoulder of the piston rod, wherein the piston rod extension passes through the piston package and fixes the piston package to the piston rod.

[0016] Preferably, the stop disk is substantially cylindrical and has a radial flange which bears against the shoulder of the piston rod and has at least one radially outer recess, wherein the piston bears with the projection on a side of the flange facing away from the piston rod.

[0017] Preferably, the piston has an annular recess for accommodating the further annular sealing element, which serves to seal the piston relative to the piston rod.

[0018] If, during the ejection movement, the piston reaches the holding region of the cylinder, which interrupts the at least one overflow channel, the seal between the piston and the piston rod or between the piston and the cylinder is thereby easily ensured.

[0019] The outer portion of the projection tapers, so that during the push-out movement, the sealing element is displaced toward the piston and ensures sealing contact with the retaining area of ​​the cylinder, which interrupts the overflow channel. During the push-in movement, the sealing element moves toward the flange of the stop disk, preventing overflow. The tapering of the projection advantageously reduces the pressing force of the sealing element on the cylinder and, therefore, reduces friction.

[0020] Preferably, the flange has a knob structure on the side facing away from the piston rod. On the one hand, these knobs facilitate overflow and ensure the pre-positioning of the sealing element in the direction of the piston. Flow through the recess of the stop disk can be easily ensured.

[0021] According to an advantageous embodiment of the present invention, the at least one overflow channel is designed as an axial groove, wherein the groove profile is configured to adapt to a stroke-dependent controllable ejection speed, for example, enabling a smooth start of the automatic ejection movement of the gas spring.

[0022] Preferably, at least two overflow channels are provided, and the at least two overflow channels are designed as axial grooves, wherein the holding area of ​​the cylinder interrupting the overflow channel is provided for adjusting the stroke limit. This allows for achieving several opening angles when used in a flap system.

[0023] According to an advantageous embodiment of the gas spring system, the gas spring system comprises a further gas spring. Depending on the application, the two gas springs can have piston packages of identical or different configurations or differ in the design of the overflow channels.

[0024] The gas spring system according to the present invention can be preferably used in a flap system, in particular a tailgate system. The gas spring system can also be used in a front hatch system. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Further advantages are illustrated in the following description of the drawings. The drawings illustrate embodiments of the invention. The drawings, the description, and the claims contain many combinations of features. Those skilled in the art will also advantageously consider these features individually and combine them into other advantageous combinations.

[0026] In the following example:

[0027] Figure 1 The gas spring of the gas spring system according to the invention is shown in longitudinal section;

[0028] Figure 2 Shown according to Figure 1 The push-out force characteristics of the gas spring. DETAILED DESCRIPTION

[0029] Figure 1 A detail of a gas spring 1 of a gas spring system according to the invention is shown in longitudinal section. The gas spring system can preferably be used in a flap system (not shown), in particular a tailgate system. The gas spring system can also be used in a front hatch system.

[0030] The gas spring 1, shown in a partially inserted state, comprises a cylinder 2 sealed at a first end (not shown) and a piston assembly 3 displaceably arranged in the cylinder 2. The piston assembly divides the cylinder 2, which is filled with compressed gas, into a first working chamber 5 near the first end and a second working chamber 6 further away from the first end. At a second end 4, opposite the first end, a piston rod 7, arranged on one side of the piston assembly 3 and extending through the second working chamber 6, emerges from the cylinder 2 concentrically with the longitudinal axis L of the cylinder 2 or gas spring 1. This second end is sealed by a seal 8 and a piston rod guide (not shown in detail). The cylinder 2 has at least one overflow channel 9, which can be connected to the working chambers 5 and 6, to facilitate the automatic extension movement of the gas spring. If the piston assembly 3 is located in this area of ​​the cylinder 2, the overflow results in dynamic damping of the extension movement. If, during its movement, the piston assembly 3 reaches a holding area 10 in the cylinder 2 that interrupts the overflow channel 9, the automatic extension movement of the piston assembly 3 is prevented. In other words, the holding region 10 of the cylinder 2 , which is indicated by means of two dashed lines, is provided for limiting the stroke of the piston assembly 3 .

[0031] If, as shown, a further overflow channel 21 is provided, then during the further course of the ejection movement the holding region 10 is followed by a second region with an automatic ejection movement.

[0032] The piston assembly 3 is designed as a springless, directionally closed piston pack. This directionally closed piston pack means that no additional force (such as a spring force) is required to close the piston pack during the ejection movement. By eliminating the known valve spring, the design of the piston pack can be significantly simplified, which optimizes the costs of the gas spring system and reduces the design effort due to the significantly simplified design. Similarly, the elimination of the valve spring makes the gas spring system even less temperature-dependent, resulting in an overall improved adjustment comfort due to a smaller fluctuation range in the adjustment force, particularly in the medium and lower temperature ranges.

[0033] As from Figure 1 As can be seen in the figure, the piston package has an annular sealing element 12 and a further sealing element 11, which are arranged in the retaining area 10 of the cylinder 2, interrupting the overflow channel 9, 21, during the ejection movement, for sealing between the cylinder 2 and the piston package and between the piston package and the piston rod 7. The piston package comprises a piston 13 and a stop disk 14, wherein the stop disk 14 rests on a shoulder 15 of the piston rod 7, and a piston rod extension 16 passes through the piston package and additionally fixes the piston package to the piston rod 7, for example by riveting. The piston rod 7, together with the piston assembly 3, forms a piston-piston rod unit.

[0034] The piston 13 may advantageously be made of a plastic material.

[0035] As from Figure 1 As can be seen in FIG, the stop disk 14 is essentially cylindrical and has a radial flange 17, which abuts against a shoulder 15 of the piston rod 7 and has at least one radially outer recess 18. The piston 13 abuts against the flange 17 on the side facing away from the piston rod 7 with a projection 19 extending in the axial direction (relative to the longitudinal axis L of the gas spring 1 or cylinder 2).

[0036] Furthermore, the piston 13 has a radially inner annular recess 20 for accommodating a further annular sealing element 11, which serves to seal the piston 13 relative to the piston rod 7 or the piston rod extension 16, and the piston 13, with its projection 19 and the flange 17 of the stop disk 14, forms a radially outer annular space 23 for accommodating the annular sealing element 12. If the piston package reaches the holding region 10 of the cylinder 2, which interrupts the overflow channel 9, 21, during the ejection movement, the seal between the piston 13 and the piston rod extension 16 or between the piston 13 and the cylinder 2 is thus ensured in a simple manner.

[0037] The sealing element 12 is arranged in the radially outer annular space 23 and is displaceable therein such that it can press against the cylinder 2 with a first pressing force during the extension movement of the gas spring 1 and with a second, smaller pressing force during the insertion movement of the gas spring 1. The first pressing force is significantly higher, for example at least twice as high as the second pressing force.

[0038] For this purpose, the projection 19 tapers on its outside so that the sealing element 12 is displaced in the direction of the piston 13 during the ejection movement and ensures sealing contact with the retaining area 10 of the cylinder interrupting the overflow channel 9, 21. Figure 1 As can be seen in FIG, the sealing element 12 bears against the radial piston surface 24 and the axial piston surface 25 of the piston 13 with a high contact pressure.

[0039] During the pushing movement, the sealing element 12 is displaced in the direction of the collar 17 of the stop disk 14, so that overflow from the working chamber 5 through the sealing element 12 in the direction of the working chamber 6 is possible. Since the sealing element 12 no longer bears sealingly against the radially formed piston surface 24 and the axially formed piston surface 25, gas can flow between the piston 3 and the sealing element 12 and into the working chamber 6 via the recess 18.

[0040] By displacing the sealing element 12 in the direction of the stop disk 14 , the pressing force of the sealing element 12 on the cylinder 2 is reduced, so that the friction is significantly reduced.

[0041] On the one hand, the knob structure having knob 22 on the side of flange 17 facing away from piston rod 7 allows for easy flow and ensures pre-positioning of sealing element 12 in the direction of piston 13. In other words, knob 22 prevents excessive displacement of sealing element 12 in the direction of stop disk 14. Sealing of recess 18 can be reliably prevented.

[0042] In the illustrated embodiment, the overflow channels 9, 21 are designed as axial grooves, the groove shape being adapted to a stroke-dependent, controllable discharge velocity. This allows, for example, a smooth start of the automatic ejection movement of the gas spring 1. Other groove profiles (not shown) are also conceivable within the scope of the present invention. By providing the two overflow channels 9, 21 with, for example, an intermediate retaining region 10 that interrupts the overflow channels 9, 21, two opening angles of the flap system can be achieved.

[0043] Figure 2 The push-out force characteristic of a gas spring 1 is shown. At the first point 1 of the characteristic curve, the piston rod 7 is pushed in together with the piston pack, i.e., in the right-hand end position in the diagram. In this state, for example, a tailgate hinged to the gas spring is closed. When the tailgate is opened, the piston pack is initially located in the area of ​​the first overflow channel 9, and gas flows from the second working chamber 6 into the first working chamber 5 through the grooves in the first overflow channel 9. Because the filling pressure is selected so that the weight of the tailgate is overcome, the gas spring 1 is automatically pushed out. The push-out force Faus decreases linearly until the piston pack reaches the holding area 10, where the first opening angle of the tailgate is reached. In this area, the piston pack is statically sealed, ensuring the holding or stopping function of the tailgate. Due to the gas compression, the push-out force Faus drops to a minimum.

[0044] If the tailgate is to be opened further, the gas spring 1 or its piston-piston rod unit can usually be manually introduced into the area of ​​the second overflow channel 21 with an adjustable release force, so that the piston rod 7 is automatically pushed out again until it reaches the left end position shown as point 2 in the figure, in which the second opening angle of the tailgate is reached.

[0045] The gas spring 1 and the corresponding gas spring system exhibit significantly improved temperature behavior. In order to overcome the triggering force or overpressure, the piston-piston rod unit must be displaced against the pressure cushion formed in the second working chamber 6 until the sealing element 12 reaches the area of ​​the second overflow channel 21 and the pressure cushion above it can be reduced.

[0046] As the piston pack moves, the second working chamber 6 in front of the pack shrinks, and the pressure continues to rise. This increase corresponds to the ratio of the volume upon reaching the holding zone 10 to the volume at the end of that zone. If the starting pressure increases due to rising temperature, the absolute pressure increase at the end will be greater than at a lower starting pressure. This effect counteracts the reduced overpressure at higher temperatures by increasing the extension force, thus neutralizing this undesirable effect.

[0047] The gas spring system according to the invention can include the described gas spring 1 and a further gas spring. The further gas spring can be constructed identically to the gas spring 1. Alternatively, the further gas spring can be constructed differently from the gas spring 1 and, for example, have a non-static seal and / or a reduced groove cross section and / or only stroke-dependent damping.

[0048] To improve friction resistance, this further gas spring can have a piston pack with piston rings that have improved sliding properties. For example, PTFE rings can be used here. In this case, the holding function will be ensured solely by the aforementioned gas spring 1.

Claims

1. A gas spring system, comprising at least one gas spring (1), the at least one gas spring comprising: a cylinder (2) closed at a first end; a piston assembly (3) displaceably arranged in the cylinder, the piston assembly dividing the cylinder (2) into a first working chamber (5) close to the first end and a second working chamber (6) remote from the first end; and a piston rod (7) arranged on one side of the piston assembly (3), the piston rod passing through the second working chamber (6) and leading out of the cylinder (2) concentrically with the longitudinal axis (L) of the cylinder (2) at a second end (4) opposite to the first end, the second end being sealed by a seal (8) and a piston rod guide, wherein the cylinder (2) has at least one overflow channel (9) which can be connected to the working chambers (5, 6) for an automatic push-out movement of the gas spring (1), wherein the interruption of the cylinder (2) interrupts the overflow channel At least one retaining area (10) of (9) is provided for limiting the stroke of the piston assembly (3), in which the automatic pushing-out movement is prevented, wherein the piston assembly (3) is designed as a piston pack closed according to direction, wherein the piston pack is designed in a springless manner and has at least one annular sealing element (12), which is provided for sealing between the retaining area (10) of the cylinder (2) and the piston assembly (3) during the pushing-out movement of the gas spring (1), and wherein the sealing element (12) is arranged in a radially outer annular space (23) of the piston pack and can be displaced in the radially outer annular space of the piston pack so that the sealing element (12) can be pressed against the cylinder (2) with a first pressing force during the pushing-out movement of the gas spring (1) and can be pressed against the cylinder (2) with a second, smaller pressing force during the pushing-in movement of the gas spring (1).

2. The gas spring system according to claim 1, wherein: The piston package has a further annular sealing element (11) which is provided for static sealing between the piston assembly (3) and the piston rod (7).

3. The gas spring system according to claim 2, wherein: The piston pack comprises a piston (13) and a stop disk (14), wherein the piston (13) abuts against the stop disk (14) with a projection (19) extending in the axial direction relative to the longitudinal axis (L), so that the radially outer annular space (23) is formed.

4. The gas spring system according to claim 3, wherein: The stop disk (14) rests on a shoulder (15) of the piston rod (7), wherein a piston rod extension (16) passes through the piston package and fixes the piston package to the piston rod (7).

5. The gas spring system according to claim 4, characterized in that The stop disk (14) is essentially cylindrical and has a radial flange (17) which rests on the shoulder (15) of the piston rod (7) and has at least one radial outer recess (18), wherein the piston (13) rests with the projection (19) on the side of the flange (17) facing away from the piston rod (7).

6. The gas spring system according to claim 5, characterized in that The piston (13) has an annular recess (20) for accommodating the further annular sealing element (11), which serves to seal the piston (13) relative to the piston rod (7).

7. The gas spring system according to claim 6, wherein: The flange (17) has a knob structure (22) on the side facing away from the piston rod (7).

8. The gas spring system according to claim 7, wherein: The at least one overflow channel (9) is designed as an axial groove, wherein the groove profile is provided for adapting a stroke-dependent controllable ejection speed.

9. The gas spring system according to claim 8, wherein: At least two overflow channels (9, 21) are provided, which are designed as axial grooves, wherein the retaining region of the cylinder (2) interrupting the overflow channels (9, 21) is provided for adjusting the stroke limitation.

10. The gas spring system according to any one of the preceding claims 1 to 9, characterized in that The gas spring system includes another gas spring.

11. The gas spring system according to claim 10, wherein: The gas spring system comprises a further gas spring, wherein the gas spring (1) has a piston package of the same or different construction.

12. The gas spring system according to claim 10 or 11, characterized in that The gas spring system comprises a further gas spring, wherein the gas spring (1) has overflow channels (9, 21) of different designs.

13. The gas spring system according to any one of the preceding claims 1 to 12, which is used in a flap system, in particular a tailgate system.

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