GB2229513A

GB2229513A - Gas spring

Info

Publication number: GB2229513A
Application number: GB9003204A
Authority: GB
Inventors: Hans-Peter Bauer; Hans-Jurgen Bauer; Ludwig Stadelmann
Original assignee: Fritz Bauer and Sohne OHG
Current assignee: Fritz Bauer and Sohne OHG
Priority date: 1989-02-17
Filing date: 1990-02-13
Publication date: 1990-09-26
Also published as: GB9003204D0; DE3904866A1; FR2643432A1; JPH02248731A; ES2020623A6

Description

1 A Gas Spring, for use as a LiftinF-1 Aid for HinEed Panels, such as a

Vehicle Luggage Boot Lid The invention relates to a gas spring with end position damping, for use as an aid to lifting, for example, a hinged panel such as the boot lid of a motor vehicle luggage compartment and comprising a substantially cylindrical housing filled partly with pressurised gas and partly with oil, in s,;hich a coaxially disposed piston rod is sealingly displaceable through one end of the housing, on the inner end of the piston there are disposed a piston which closes sealingly on the outward of the housing and opens on the inward displacement, and a longitudinal channel bridging the piston connecting together the partial inner spaces of the housing situated on both sides of the piston, said longitudinal channel being connected by means of a throttle channel with the partial inner space situated between the piston and the piston rod output side end, and there being provided at the piston rod output side end a device for damping an outward movement of the piston rod in the region of the end of its outward movement In a gas spring of this type known from German Auslegeschrift AS 29 05 30 there is arranged at the piston rod output end a chamber into which the throttle channel plunges on the outward run of the piston rod. The piston itself exerts a so-called drawing action onto the oil present in the inner space of the housing and therefore takes this along on the outward run of the piston rod in front of the latter's output side end. Here, a throttling port is provided through which the oil flows into the chamber producing a considerable additional damping. The oil then flows through the throttle channel and the longitudinal hole in the piston rod into the partial inner space of the housing situated opposite the piston rod output side end. So that this end damping remains effective on each outward run of the displacement of the piston rod out 1) 2 piston rod, it is necessary that preliminarily the piston rod should be again fully driven into the housing so that the oil can again flow against gravity in the partial inner space facing the piston rod output side end. This gas spring is used in such a manner that the piston rod is always upwardly driven out.

The present invention seeks to provide a gas spring of the abovedescribed type in such a manner that a reliable end damping is achieved with simple means and also when the piston rod is driven out downwards when the gas spring is used.

According to the invention, there is provided a gas spring with end position damping, comprising a substantially cylindrical housing filled partly with pressurised gas and partly with oil, in which a coaxially disposed piston rod is sealingly displaceable through one end of the housing, on the inner end of the piston there are disposed a piston which closes sealingly on the outward displacement of the piston rod out of the housing and opens on the inward displacement, and a longitudinal channel bridging the piston connecting together the partial inner spaces of the housing situated on both sides of the piston, said longitudinal channel being connected by means of a throttle channel with the partial inner space situated between the piston and the piston rod output side end, and there being provided at the piston rod output side end a device for damping an outward movement of the piston rod in the region of the end of its outward movement, wherein the device for damping the outward movement of the piston rod is formed by a throttle bush into which the throttle channel extends in the region of the end of the outward displacement of the piston rod out of the housing, a throttle annular space being provided between the piston rod and the throttle bush.

The throttling port of the longitudinal channel plunges at the end of its outward run into the throttle bush and produces an additional hydraulic damping.

In one embodiment of the invention, the throttle bush is stationarily mounted in the housing. In another embodiment 3 of the invention, the throttle bush is connected with the piston by means of a tractive connection.

In a further embodiment of the invention, the throttle bush is connected with the piston by means of a helical spring and the throttle channel, when the helical spring is released, opens out into the partial inner space between the piston and the throttle bush. In yet another embodiment of the invention, the throttle bush delimits, with the inner wall of the housing, a throttling channel. These aspects of the invention make it possible, with relatively reduced expenditure, to achieve a multi-step end damping without the throttle bush having to be specially long for the purpose.

The invention further provides for the utilisation of a gas spring as a lifting aid for a hinged panel mounted on and able to be upwardly pivoted around a joint, the piston rod being downwardly directed in all pivoting positions of the hinged panel with respect to the housing.

In an advantageous aspect of the invention, the central longitudinal axis of the gas spring, when the hinged panel has been pivoted upwardly, encloses an angle in a vertical plane which is less than 650 and in another aspect of the invention, the centre of gravity of the hinged panel, on the upward pivoting thereof, is pivoted through a vertical plane passing through the joint of the panel. In still a further aspect of this invention, the throttle channel extends into the throttle bush when the centre of gravity of the hinged panel is pivoted through the vertical plane.

In yet another aspect of the invention, the housing is filled with an amount of oil such that the partial inner space situated between the piston and the piston rod output side end of the housing is at least substantially filled with oil if the throttle channel extends into the throttle bush.

The invention further provides for the utilisation of a gas spring with end position damping, comprising a substantially cylindrical housing filled partly with pressurised gas and partly with oil, in which a coaxially disposed piston rod is sealingly displaceable through one end of the housing and on the inner end of the piston there are 4 disposed a piston which closes sealingly on the outward displacement of the piston rod out of the housing and opens on the inward displacement, and a longitudinal channel bridging the piston connecting together the partial inner spaces of the housing situated on both sides of the piston, said longitudinal channel being connected by means of a throttle channel with the partial inner space situated between the piston and the piston rod output side end, and there being provided at the piston rod output side end a device for damping an outward movement of the piston rod in the region of the end of its outward movement, wherein the device for damping the outward movement of the piston rod is formed by a throttle bush into which the throttle channel extends in the region of the end of the outward displacement of the piston rod out of the housing, a throttle annular space being provided between the piston rod and the throttle bush.

The invention additionally provides a motor vehicle having a compartment closable by means of a hinged panel which is upwardly pivotable about a joint assisted by a gas spring with end position damping, comprising a substantially cylindrical housing filled partly with pressurised gas and partly with oil, in which a coaxially disposed piston rod is sealingly displaceable through one end of the housing, on the inner end of the piston there are disposed a piston which closes sealingly on the outward displacement of the piston rod out of the housing and opens on the inward displacement, and a longitudinal channel bridging the piston connecting together the partial inner spaces of the housing situated on both sides of the piston, said longitudinal channel being connected by means of a throttle channel with the partial inner space situated between the piston and the piston rod output side end, and there being provided at the piston rod output side end a device for damping an outward movement of the piston rod in the region of the end of its outward movement, wherein the device for damping the outward movement of the piston rod is formed by a throttle bush into which the throttle channel extends in the region of the end of the I.

outward displacement of the piston rod out of the housing, a throttle annular space being provided between the piston rod and the throttle bush.

Two embodiments of the invention will now be described, by way of examples and with reference to the accompanying drawings, in which:

Fig. 1 is the back of a motor vehicle which shows the use of a gas spring of the invention; Fig. 2 is a gas spring of the invention in longitudinal section, and Fig. 3 is a modified embodiment of a gas spring of the invention in longitudinal section.

As shown in the Figures, a gas spring 1 has a substantially cylindrical housing 2 on the one gas-tight end of which a knuckle eye 3 is mounted as securing element.

Out of the other end of the housing 2 a piston rod 4 is led out which is mounted concentrically with the central longitudinal axis 5 of the housing 2 in slidable manner. The gas spring 1, together with its knuckle eye 3, is articulated at a joint 6 on a lid 7 of a motor vehicle 8 constructed as a boot lid.

The free end of the piston rod 4 also has a knuckle eye 9 acting as a securing element, by means of which it is articulated in a joint 10 in the boot 11 of the motor vehicle 8. The deck lid 7 is, for its part, articulated on the boot 11 by means of a joint 12.

As will be seen in Fig. 1 the boot lid 7 is so articulated that its upper side 13, when the boot 11 is closed, is situated in a substantially horizontal position, as shown in a dash-dot line in Fig. 1. Its centre of gravity 14 is here still under the joint 12. As Fig. 1 further shows, the centre of gravity 14, when the boot lid 7 is open, and seen from its closed position, is behind a vertical plane 15 through the joint 12. The angle a between this vertical plane 15 and a connecting line 16 through the centre of joint 12 is, for example, between about b between the axis 5 of the gas when gravity 14 and the and 30o. The angle spring 1 and a vertical plane 17 through the joint 6 the boot lid 7 is open is for example between about 500 to 650. As Fig. 1 furthermore shows, the angle -c between the axis 5 and the vertical plane 17 when the boot lid is closed is even greater; it is about 700 to 800.

At the piston rod output side end of the housing 2 a guide bush 18 is provided, (Figure 2), which guides the piston rod 4 coaxially; this guide bush is a bead 19 of the housing 2. Applying bush 18 is a seal 20 which lies on the against the inner wall 21 of the housing hand sealingly against the piston spring is closed off in gas-tight manner output side end.

Towards the inner space 22 of the housing 2 there connects onto the seal 20 a holding ring 23 which is axially held by a bead 25 rolled into the housing 2 and engaging into a corresponding circumferential groove 24 of the holding ring 23.

Mounted on the end of the' piston rod 4 which is situated in the housing 2 is a so-called damping piston 26 which has an annular space 27 open towards the inner wall 21 of the housing 2 in which there is disposed a damping ring 28 bearing against the inner wall 21 and which is in a highly wear-resistant plastic, e.g polytetrafluorethylene (PTFE). The annular space 27 is delimited in the axial direction by two limiting surfaces extending radially towards the axis 5 and acting as stop faces 29, 30, the distance of which in the direction of the axis 5 is to some extent greater than the extension of the damping ring 28 in this direction, so that the damping ring 28 is able to move in the direction of the axis 5 slightly relative to the piston 26.

Radially inside the damping ring 28 there is the annular space 27 duct 32 opens out into situated between the output side end of the and the inner wall 21 is formed which connects the free rod 4, held outwardly by against this guide one hand sealingly 2 and on the other so that the gas at its piston rod 4 formed in a free space 31 into which a passage the partial annular space 22' which is damping piston 26 and the piston rod gas spring 1. Between the piston 26 of the housing 2 an annular channel 33 c ane 31 with the - artial 7 inner space 22' facing away from the partial inner space 22" when the damping ring 28 does not apply sealingly against the stop face 29.

Formed in the piston rod 4, coaxially with the axis 5-, is a longitudinal channel 34 opening out into the p,-rtial inner space 22', which is constituted by a blind hole. This longitudinal channel 34 is connected in the region of its bottom 35 via a throttle channel 36 extending transversely to the axis 5 with the partial inner space 22. The distance 1 of this throttle channel 36 from the facing side 37 of the piston 26 is, for exampl---, between 10 and 20 rim.

Mounted on the holding ring 23 is a throttle bush 38 which relative to the piston rod 4 delimits a throttle innular gap 39, the radial O.lmm, preferably 0.04 throttle bush 38 is at distance 1, so that the the throttle bush 38 when extension e of which is 0.02 to to 0.07 mm. The length 1' of the least slightly greater than the throttle channel 36 is also inside the piston rod 4 has moved as far as possible out of the housing 2, when, therefore, the piston 26 applies with its side 37 delimiting the partial inner space 22' against the throttle bush 38, as shown in Fig. 2.

The throttle bush 38 is in a particularly precisely injectable plastic, e.g, a polyamide.

The inner space 22 with compressed gas 40 and of the housing 2 is filed partly partly with oil 41.

When the piston rod 4 together with the piston 26, on the closing of the boot lid 7, is pushed into the housing 2 with the additional compression of the pressurised gas 40 present in the inner space 22 correspondingly to the pushing position 42 into the housing 2, then the damping ring 28 applies against the stop face 30 of the partial inner space 22" is then freely annular channel 33, the free space 31 and with the partial inner space 22', so that 41 and then the gas 40 can flow in a manner from the partial inner space 22" inner space 22'. The extent to which place is dependent upon the cross-sections piston 26. The connected via the the passage duct 32 initially the oil slightly throttled into the partial a throttling takes of the throughflow 8 regions mentioned which are selected correspondingly to the requirements dictated by the particular application.

Additionally, oil 41 flows thorough the longitudinal channel 34, the throttle channel 36 and pos sible the annular groove 39 into the partial inner space 22'. The closing of the boot lid 7 is thus effected against the compressing'force -of the gas spring 1 which is increasing as a result of the compression of the pressurised gas 40, and indeed in a slightly damped form.

When, on the other hand, the boot lid 7 is opened, the piston rod 4 travels in the pushing position 43 out of the housing 2. In this case, the damping ring 28 applying with light pressure against the inner wall 21 of the housing 2 lies closely against the stop face 29 of the piston 26, so that there is no connection between the free space 31 and the annular channel 33. Thereby there is thus no connection between the partial inner spaces 22' and 22". The only connection is that of the longitudinal channel 34 with the throttle channel 36. At the initial phase of the exhaust movement compressed gas 40 is delivered from the partial inner space along the longitudinal channel 34 and the throttle channel 36 into the partial inner space 22", i.e, the damping is not very pronounced.

When on the further outward displacement of the piston rod 4, therefore with increasing raising of the boot lid 7, the throttle channel 36 communicates with the oil 41, oil is then pressed along the latter and the longitudinal channel 34 into the partial inner space 22". with the result that from this moment on there occurs an increasing of the damping of the outward movement of the piston rod 4. When the throttle channel 36 on a further outward displacement of the piston rod 4 out of the housing 2 plunges into the throttle bush 38, there occurs an additional hydraulic throttling in the annular gap 39 which increases with the further outward movement of the piston rod 4, as the relative length of the annular gap 39 becomes greater as the insertion of the throttle channel 36 into the throttle bush 38 increases. The dimensioning should be such that the throttle channel 36 9 plunges into the throttle bush 38 at centre of gravity 14 of the boot lid 7 over the vertical plane 15. From this spring 1 is released, longer bears upon it forces are exerted on mush take place a the latest when the is pivoted inwards moment on, the gas as the weight of the boot lid 7 no because from this moment on pulling the gas spring. Consequently, there particularly intensive damping of the outward movement of the piston rod 4.

From the above comments it follows that there must be at least sufficient oil in the inner space 22 so that on the plunging of the throttle channel 38 into the throttle bush 38 the partial inner space 22' is fully filled with oil 41, in order that it may be ensured that this end damping is purely hydraulic. As will be seen from the above comments the throttle bush can protrude as far as the inner wall 21 of the housing 2. Therefore, it may also be designed with a very much thicker wall than is shown in Fig. 2.

The embodiment of the invention illustrated in Fig. 3 largely agrees with that of Fig. 2, the application-being effected in a manner similar as that shown in Fig. 1. Therefore, all identical parts are denoted by identical figures, and all parts constructionally similar and functionally identical are denoted by the same reference figures with an upper prime, without a renewed description being required with respect to them.

In this arrangement the throttle bush 38' is not rigidly connected with the holding ring 23, but designed as an additional piston. It is connected by means of a helical spring 44 with the damping piston 26' which is secured on the one hand to a projection 45 of the piston 26' delimiting the side 37Y and, on the other hand, on the facing end of the throttle bush 38' Thus, there is a tractive connection between the piston 26' and the throttle bush 3P. Between the throttle bush 38' and the inner wall 21 of the housing 2 a throttling annular channel 46 is formed. When the helical spring 44 is released, and therefore when the throttle bush 38' is not applied against the holding ring 23, the throttle channel 36 opens out freely between the side 37' and the facing end 47 of the throttle bush 38' into the partial inner space 2P.

When the piston rod 4 is pulled out the throttle bush 38' plunges initially into the oil 41, as a result of which a first throttling is effected in the annular channel 46.

Subsequently, the throttle bush 38' comes to rest on the holding ring 23, as a result of which, on the further outward extension of the piston rod 4, the spring 44 is counter-force producing a damping. The mutually facing faces 48, 49 of the throttle bush 38' and of the holding ring 23 should in this case lie one on the other substantially in a fluid-tight manner. Subsequently to this, the throttle channel 36 plunges into the throttle annular gap 39 of the throttle bush 38', as a consequence of which the same damping forces are produced as were described above.

1 comnressed below a 1

Claims

CLAIMS:

1. A gas spring with end position substantially cylindrical housing pressurised gas and disposed piston rod of the housing, on disposed a piston displacement of the damping, comprising a filled partly with partly with oil, in which a coaxially is sealingly displaceable through one end the inner end of the piston there are which closes sealingly on the outward piston rod out of the housing and opens on the inward displacement, and a longitudinal channel bridging the piston connecting together the partial inner spaces of the housing situated on both sides of the piston, said longitudinal channel being connected by means throttle channel with between the piston and there being provided device for the region device for formed by a throttle extends in the region of the end of the outward displacement of the piston rod out of the housing, a throttle annular space being provided between the piston rod and the throttle bush.

01 a the partial inner space situated the piston rod output side end, and at the piston rod output side end a damping an outward movement of the piston rod in of the end of its outward movement, wherein the damping the outward movement of the piston rod is bush into which the throttle channel 2. A gas spring according to claim 1, wherein the throttle bush is stationarily mounted in the housing.

3. A gas spring according to claim 1, wherein the throttle bush is connected with the piston by means of a tractive connection.

4. A gas spring according to claim 3, wherein the throttle bush is connected with the piston by means of a helical spring and the throttle channel, when the helical spring is released, opens out into the partial inner space between the piston and the throttle bush.

12 5. A gas spring according to claim 3 or 4, wherein the throttle bush delimits with the inner wall of the housing, a throttling channel.

6. Utilisation of a gas spring according to any one of claims 1 to 5 as a lifting aid for a hinged panel mounted on a motor vehicle and able to be upwardly pivoted around a joint, the piston rod being downwardly directed in all pivoting positions of the hinged panel with respect to the housing.

7. Utilisation of a gas spring according to claim 6, wherein the central longitudinal axis of the gas spring, when the hinged panel has been pivoted upwardly, encloses an angle in a vertical plane which is less than 650.

8. Utilisation of a gas spring according to claim 6 or 7, wherein the centre of gravity of the hinged panel, on the upward. pivoting thereof, is pivoted through a vertical plane passing through the joint of the panel.

9. Utilisation of a gas spring according to claim 8, wherein the throttle channel extends into the throttle bush when the centre of gravity of the hinged panel is pivoted through the vertical plane.

10. Utilisation of a gas spring according any to one of claims 6 to 9, wherein the housing is filled with an amount of oil such that the partial inner space situated between the piston and the piston rod output side end of the housing is at least substantially filled with oil if the throttle channel extends into the throttle bush.

11. The utilisation of a gas spring with erLd position clamping, comprising a substantially cylindrical housing filled partly with pressurised gas and partly -with oil, in which a coaxially disposed piston rod is sealingly displaceable through one end of the housing and on the inner end of the piston there are disposed a piston which closes sealingly on the outward displacement of the piston rod out of the housing and opens on the inward displacement, and a longitudinal channel bridging the piston connecting together the partial inner spaces of the housing situated on both sides of the piston, said longitudinal channel -being connected by means of a throttle channel with the partial inner space situated between the piston and the piston rod output side end, and there being provided at the piston rod end a device for damping an outward movement of the piston rod in the region of the end of its outward movement, wherein the device for damping the outward movement of the piston rod is formed by a throttle bush into which the throttle channel extends in the region of the end of the outward displacement of the piston rod out of the housing, a throttle annular space being provided between the piston rod and the throttle bush.

output side 12. A motor vehicle having a compartment closable by means of a hinged panel which is upwardly pivotable about a joint assisted by a gas spring with end position damping, comprising a substantially cylindrical housing filled partly with pressurised gas and partly with oil, rod is sealingly displaceable on the inner end of the piston there are disposed a piston which closes sealingly on the outward displacement of the piston rod out of the housing and opens on the inward displacement, and a longitudinal channel bridging the piston connecting together the partial inner spaces of the housing situated on both sides of the piston, said longitudinal channel being connected by means of a throttle channel with the partial inner space situated between the piston and the piston rod output side end, and there being provided at the piston rod output side end a device for damping an outward movement of the piston rod in the region of the end of its outward movement, wherein the device for damping the outward movement of the piston rod is formed by a throttle bush into which the throttle channel piston through one end of the housing, coaxially disposed in which a 14 extends in the region of the end of the outward displacement of the piston rod out of the housing, a throttle annular space being provided between the piston rod and the throttle bush.

13. A gas spring, substantially as hereinbefore described and with reference to the accompanying drawings.

14. The utilisation of a gas spring, substantially as hereinbefore described and with reference to the accompanying drawings.

15. A motor vehicle having a gas spring, substantially as hereinbefore described and with reference to the accompanying drawings.

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