GB2346082A

GB2346082A - Height-adjustable seat for a vehicle

Info

Publication number: GB2346082A
Application number: GB0001732A
Authority: GB
Inventors: Rolf Mintgen; Holger Loring
Original assignee: Stabilus GmbH
Current assignee: Stabilus GmbH
Priority date: 1999-01-27
Filing date: 2000-01-27
Publication date: 2000-08-02
Also published as: DE19903147A1; FR2788736A1; JP2000211408A; GB0001732D0; ES2182626A1; ES2182626B1; BR0000888A

Abstract

Height adjustment in a vehicle seat is derived from a main force applying device 11 (eg a gas spring) between the seat 3 and underframe 5 and an additional force applying device 19 (eg another gas spring) whose force is superimposed on that of device 11, whereby sufficient force to adjust the height can be obtained for users of all weights. The additional device can be operated independently of the main device and be connected to the seat by a lever linkage via a disengageable bearing which transmits only vertical forces. It may take the form of a slave cylinder controlled by a master. The mechanism may include a spring whose load is pre-adjusted by the main device 11.

Description

2346082 ADJUSTABLE HEIGHT SEAT The invention relates to an adjustable

height seat of the kind comprising a seating surface with an underframe, the underframe having a height- adjusting means. The invention is particularly suitable for use as a vehicle seat.

DE A 22 52 999 describes an adjustable height seat of the kind set forth, of which the seating surface has an underframe which is secured to the floor of a vehicle. The underframe is in the form of a gearing linkage which has a gas spring as the height-adjusting means. On an extension movement of the gas spring the coupling members of the gearing linkage are pivoted in such a way that the resulting movement of the seating surface adjusts its height. As a rule the gas spring is set to a mean body weight, for example 75kg. This arrangement of the gas spring has the consequence that the user of the height adjustment must lift himself up within the vehicle if his body weight lies above the stated reference weight. This situation is just about acceptable for the driver's seat as the driver can hold on to the steering wheel to raise himself. However, there is generally nothing to get hold of or use for support around the passenger seat to help in raising oneself. Consequently this kind of height adjustment is only of limited acceptability.

It is an aim of the present invention to achieve an adjustable height seat in which the height adjustment is as convenient as possible.

According to the present invention, In an adjustable height seat of the kind set forth, the height- adjusting means has an associated additional force-applying device for adjusting the height of the seat, the adjusting 2 forces of the height- adjusting means and of the additional forceapplying device being superimposed.

As in the state of the art, the height-adjusting means may comprise a gas spring, but it could be a mechanical spring which provides a basic force for the height adjustment. The additional force-applying device provides an additional force which assists the height-adj u sting means in adjusting the height. The additional force means that it is not necessary for the user to raise himself awkwardly within the vehicle. For people of lighter weight there is the advantage that when lowering the seating surface it is only the force of the height- adjusting means which has to be overcome.

In one embodiment the additional force-applying device comprises a lever linkage including an actuating device in conjunction with a transmission lever on the seat. The actuating device can comprise a simple pivoted lever which has a force-input lever arm and a force-output lever arm. The force-input lever arm is made significantly longer that the forceoutput lever arm so as to introduce a leverage ratio. When the forceoutput lever arm engages over a transmission lever on the seat and the height-adjusting means operates, then a rotary movement of the actuating device results in movement of the lever arm which assists the heightadjusting movement of the seating surface.

In this arrangement the lever linkage of the additional force-applying device may engage the seat independently of the height- adj u sting means.

Alternatively, the lever linkage of the additional force-applying device may engage a portion of the underframe on which the height- adj u sting means acts.

3 In one embodiment the force -transmitting path from the transmission lever to the seat includes a disengageable loose bearing, which transmit only perpendicular forces. This has the advantage that the heightadjusting means can operate completely separately from the force-appIying device.

Only when the loose bearing is engaged is the additional force applied through the actuating device.

In another embodiment, the additional force-applying device comprises a master cylinder controlled by an actuating device and operatively connected to a slave cylinder, with the slave cylinder applying the additional height-adjusting force. As with the previous embodiment, a lever linkage can be used as the actuating device, acting on the master cylinder with a force determined by the leverage ratio of the force-input and force-output lever arm. Preferably the slave cylinder comprises a pneumatic spring in conjunction with a variable fluid pressure reservoir. An increase in the fluid pressure supply alters the force of the pneumatic spring to provide the additional force. The master cylinder may be constructed with a hydraulic conversion ratio or leverage in the form of a stepped piston arrangement. In the stepped piston arrangement the crosssectional area of the slave cylinder piston is greater than the area of the master cylinder so that with a constant pressure in the connection between the master and slave cylinders in conjunction with the different piston areas exposed to pressure, a pressure Conversion ratio is achieved.

In order to be able to place the actuating device in an optimum position on the seat for the application of the force and ease of use, the actuating device includes a Bowden cable for transmitting the additional applied force, allowing a very flexible layout.

4 The height-adjusting means is preferably formed by a spring of which the pre-loaded length is adjustable by means of the force-applying device. Preferably the height- adj u sting means comprises a gas spring, most preferably a lockable gas spring. Preferably this spring is actuated by means of a Bowden cable so that a single actuating device operates the spring and actuates the force-applying device.

Conveniently a first Bowden cable is provided for the locking function of the gas spring and a second Bowden cable is provided for altering the preloading of the gas spring. The second Bowden cable acts in the tension length against the direction of extension of the piston rod, whereby the pre-loaded length can be altered. Alternatively a transmission linkage is arranged in the direction of the force of the height- adjusting means, by which the effective length of the height- adjusting means can be altered.

The transmission linkage may comprise at least two members, with a slide device between them which alters the spacing of the members, Thus the slide device can comprise a wedge connection between a control wedge and at least one wedge surface on one of the members. Alternatively the transmission linkage can comprise a control cam, by the angular position of which the effective length of the transmission linkage and thereby the pre-loaded length of the spring can be altered.

The transmission linkage may instead comprise a parallelogram linkage, in which at least two opposed pivot points are connected by adjusting means to vary the diagonal length of the parallelogram linkage, and thereby of the transmission linkage.

It is also possible for the height- adj u sting means to have an additional spring of which the pre-load can be altered by means of the force-applying device. The additional spring may for example comprise a coil spring which acts between two abutments, at least one abutment being movable by means of the force-applying device. The additional effective force can then be calculated from the spring rate of the additional spring and the displacement travel of the abutment.

In a further embodiment, the additional force-applying device is arranged so that the direction of its force is opposed to the direction of the force of the height- adjusting means. The height- adjusting means is designed with an excess of force which ensures reliable adjustment of the height in all circumstances. This excess force is at least compensated by the additional force-applying device. The additional force-applying device may have tension means which lower the seat.

Various embodiments of the invention are illustrated by way of example in the accompanying drawings, in which:

Figures I to 4 illustrate the principle of an adjustable height seat with a height-adjusting means and a direct mechanical force applying device; Figures 5 to 8 show a master/slave cylinder as the additional force applying device; Figures 9 to 11 show a force-applying device in which the effective length of the transmission lever is variable; Figures 12 and 13 show a height-adj u sting means in the form of a spring of variable pre-load; and 6 Figure 14 shows a height- adjusting device with an additional spring of variable pre-load.

Figure 1 shows a vehicle seat 1 of adjustable height with a seating surface 3 which is mounted on an underframe 5. The underframe has coupling links 7, 9, of which a first end is pivotally mounted on the underframe 5. The links 7, 9 are connected through a height- adjusting means 11 in the form of a spring, in this actual example a gas spring.

The gas spring is in the form of a lockable construction such as is known from DE 34 37 098. A piston rod 13 of the spring abuts against a fixed bearing on the underframe, the second end of the coupling link 7 also being pivotable on the fixed bearing. A cylinder 15 of the gas spring 11, displaceable with respect to the piston rod 13, engages the second end of the coupling link 9, which pivots at a central portion in a stationary bearing 17.

The underframe 5 also has a force-applying device 19 which includes an actuating device 21. The force-applying device 19 is in the form of a lever linkage which is held on a fixed pivot bearing 23. The actuating device to the right of the pivotal bearing 23 is in the form of a forceinput lever arm which is many times longer than a transmission lever 25 on the left hand side acting as a force-output lever arm. The seat has a bearing guide 27 for the transmission lever 25.

The gas spring can be operated at will through a Bowden cable 29. For this purpose the Bowden cable 29 is connected to the piston rod 13 of the gas spring 11. The other end of the Bowden cable is guided in the actuating device 21 and operated through a release button 31 on its end.

7 Starting from a lower seat height setting, in order to adjust the height of the seat the release button 31 is operated in order to release the gas spring 11, so that its pressure force operates. With the button pressed the actuating device 21 is turned manually about the pivot bearing 23 in a clockwise direction, the transmission lever being raised in the bearing guide 27 on the seat. Accordingly the forces of both the spring 11 and the force-applying device 19 are available during the height adjustment. Because of the leverage ratio in the actuating device 21 a multiple of the manual-applied force is applied to the seat. The important advantage of this seat height adjustment is that 4 single handle or actuating device operates both the height-adjusting means 11 and also the force-applying device 19.

Figure 2 shows a variant of Figure 1, in which instead of the bearing guide 27 in the form of a guiding slot, a simple abutment plate 28 is formed, against which the transmission lever 25 bears. The abutment plate 28 and the transmission lever 25 form a disengageable loose bearing 30 which only allows the transmission of force in a perpendicular direction. Constructionally the fixed bearing 17 for the coupling link 9 is combined with the pivotal bearing 23 for the actuating device 21, which gives a further advantage. Moreover a functional separation of the stroke force of the height-adjusting means 11 and the force-applying device 19 can be achieved. If the actuating device 21 is in a perpendicular position with respect to the lever arrangement with a horizontal transmission lever 25, then there is no contact between the abutment plate 28 and the transmission lever 25. When the height- adjusting means 11 is released then the seat moves into a high setting in which there is a balance between the force of the weight on the seat and the height- adj u sting means. In this case the actuating device remains stationary. If the seat is to be raised further, one can first guide the transmission lever 25 as far as the 8 abutment plate, overcoming the internal friction of the fixed bearing 17. Additional force is applied only by further rotary movement of the actuating device or transmission lever.

Figure 3 shows a modification of Figure I in which the transmission lever 25 of the actuating device 21 is bent round and engages the coupling link 9 directly. This is to accommodate known seat constructions which have no suitable force-engagement point in the region of the longitudinal bearing guide 27. The height- adjusting means as a gas spring and the 10 additional force-applying device can be used as in Figure 1. For the user there is no functional difference from Figure 1. In Figure 4 a forceapplying device 19 is used in which a Bowden cable 45 is secured to the coupling link 9 over a roller 47. The 15 attachment point of the Bowden cable to the coupling link 9 is spaced from the attachment point to the fixed bearing 17 so that a pulling movement on the Bowden cable exerts a torque on the coupling link 9 to assist the action of the heightadjusting means 11. 20 Figures 5 to 8 show modifications in which a master/slave cylinder arrangement 32;33 is used as the additional forceapplying device 19. In the embodiment shown in Figure 5 the master/slave cylinder assembly comprises a structural unit separate from the heightadjusting means 11. The transmission lever 25 of the actuating device 21 is pivotally 25 connected to a piston rod 39 of the master cylinder 32. A piston rod 35 of the slave cylinder 33 is pivotally connected underneath the seating surface 3. As shown in the drawing, the area of the master cylinder 32 is less than that of the slave cylinder 33, so that a hydraulic pressure conversion ratio is obtained between the master cylinder and the slave 30 cylinder, because pistons of different diameters are used.

9 As in the embodiments of Figures 1 to 4, the gas spring 11 is unlocked by the release button 31 and pivots the coupling link 9 about the bearing 17 and thereby exerts a first force on the seat 3. When the actuating device 21 is rotated in a counter- clockwise direction the piston rod 39 moves into the master cylinder 32 and the piston rod 35 of the slave cylinder 33 moves out so that the additional force for adjusting the height of the seat is applied by the master/slave cylinder assembly.

In Figure 6 the master cylinder 32 is arranged parallel to the slave cylinder 33 and to the gas spring 11. The piston rod 39 is driven by the transmission lever 25 and in this embodiment they are arranged with their axes parallel. The pressure fluid is displaced from the master cylinder 32 through a line 41 into the slave cylinder 33 which is connected in parallel with the height- adjusting means 11. The height- adj u sting means 11 and the slave cylinder 33 turn the coupling link 9 about the fixed bearing 17 and thereby move the seat.

Figure 7 shows a modification of the force-applying device 19 of Figure 5 with a master/slave cylinder assembly 32;33 combined into one unit, a hydropneumatic spring of the height- adjusting means 11 with a variable fluid pressure reservoir 43 acting as the slave cylinder. The gas preloading in the height-adjusting means or hydropneumatic spring 11 is increased in proportion to the pressure fluid fed into the reservoir 43 through the line 41 from the slave cylinder 33. The amount of fluid leaving the slave cylinder 33 depends on the amount leaving the master cylinder 32 as a result of operation of the actuating device 21. Increasing the gas pre-loading in the spring 11 increases the force available for adjusting the height of the seat 1.

Figure 8 shows a modification of Figure 7. Instead of the hydraulic pressure converter of Figure 7 there is a mechanical force conversion in the form of a loose roller 47 working on the principle of a block and tackle within a second Bowden cable 45. The master cylinder 32 is attached to the loose roller 47, and its piston rod 35 is attached to the coupling link 9. One end of the second Bowden cable 45 is attached to the transmission lever 25 of the actuating device 21 and it passes around the free roller 47 to the coupling link 9 and is secured on it. When the actuating device 21 is turned in a counter-clockwise direction about the pivot bearing 23, the second Bowden cable 45 shortens between the roller 47 and the coupling link 9 and pulls the loose roller 47 in the direction of the coupling link 9, whereby the piston rod 35 is pushed into the master cylinder 33 and pressure fluid is displaced into the variable fluid pressure reservoir 43 in the hydropneumatic spring 11. In addition to the conversion ratio of actuating device/transmission lever, use is made in addition of the halving of the force employed at the master cylinder 32 through the loose roller 47.

Figure 9 shows another embodiment, in which the effective length of the transmission lever is variable. In Figure 9 the height- adjusting means 11 comprises a gas spring, the gas spring having in the, direction of the force a transmission rod 49 of variable length. The transmission rod 49 has a pivoting cam 51 controlled by the actuating device 21. The effective length of the cam 51 determines the length of the transmission rod 49, the alteration in length of the transmission rod 49 causing an alteration in the spring length and thereby an alteration in the spring pre-loading of the height-adj u sting means 11. This embodiment can also be arranged so that the height-adjusting means 11 is sufficient for a normal heightadjustment range and in that case the piston rod 13 is at maximum extension. For a further adjustment of the height the cam 51 is turned, it being assumed I I that the seat is not to be lowered. The cam 51 turns the coupling link 9 about the fixed bearing 17 and thereby raises the seating surface 3.

Figure 10 shows a similar embodiment. In Figure 10 the transmission rod 49 comprises two members 49a;49b, between which there is arranged a slide device 53 which determines the spacing between the two members.

The slide device 53 comprises a wedge connection formed by a control wedge 56 with respective wedge faces 55 engaging the members 49a;49b.

The wedge connection is coupled to the actuating device 21 through a setting rod 57. When the actuating device 21 is turned in a counter clockwise direction the setting rod 57 and the control wedge 56 move in and out of the wedge connection, whereby a transverse movement is transmitted to the members 49a;49b of the transmission rod 49. This transverse movement causes an alteration of the installed length of the gas spring 11 and thereby an alteration in the pre-load on the spring, which can be regarded as the application of the additional force.

Figure 11 simply shows the height-adjusting means 11 in conjunction with a parallelogram linkage 59. The linkage 59 has, in a mirror symmetrical fashion, respectively a pivot point 61 on the cylinder 15 and a pivot point 63 on the piston rod 13 of the height-adjusting means 11. Links 65 and 67 have outer ends pivotally mounted on the points 61 and 63 respectively, and inner ends pivotally mounted on a knuckle pivot 69 to which there is attached as the adjusting means a Bowden cable extension 45a;45b, guided over direction-reversing rollers 71.

When the displacement force of the height-adjusting means is no longer sufficient for a further extension movement of the piston rod, a tension force on the Bowden cable 45 can be used to reduce the spacing between the knuckle pivots 69 whereby the piston rod 13 is drawn out of the 12 cylinder 15 and a further stroke travel is covered, causing an adjustment of the height of the seat (not shown).

Figure 12 shows a modification in which the Bowden cable 45 forming part of the force-applying device is secured at one end to the coupling link 9 of the underframe and is guided over a roller 47 of the height adjusting means 11. The height-adjusting means 11 is arranged so that the pressure force can always raise a person together with the seat 3. The seat height adjustment is such that a desired height is achieved exactly or possibly exceeded. If the seat is too high, then a pull exerted on the Bowden cable 45 by means of the actuating device 21 (not shown) causes the piston rod 13 to be moved back into the cylinder 15 and thereby allows the desired height setting to be reached.

Figure 13 shows an embodiment similar to that of Figure 12. In Figure 1.3 an additional spring 73 with an abutment 75 on the piston rod 13 is influenced through the Bowden cable 45. The additional spring abuts against the cylinder 15 on a fixed abutment 77. By a pull on the Bowden cable 45 the additional spring 73 and the height setting are shortened, so that the seat is lowered. In this case the additional forceapplying device acts in opposition to the height-adjusting means. Accordingly the additional spring 73 and the height- adjusting means deliver a large force which ensures that even in the case of a very heavy person the upper position of the seat can be reached without the application of any additional force. As a result, the additional force must be introduced in order to lower the seat.

In the embodiment of Figure 14 an additional spring 73 is used. The spring 73 has an axially displaceable abutment 79. The abutment is displaced by a fork 81 guided on the cylinder 15 of the height-adj u sting 13 means 11. The fork 81 is connected to the actuating device 21 at the pivot bearing 23. Between the fork 81 and the abutment 79 there is a mechanical connection which converts the pivotal movement of the fork 81 into a guided axial movement of the abutment 79, for example through a pin working in a curved slot. The force of the additional spring is added to the force of the height- adjusting means 11.

In the embodiments described above with the additional spring 73 the additional force is obtained from the altered spring pre-loading of the 10 additional spring.

Claims

14 CLAIMS

1 An adjustable height seat of the kind set forth, in which the heightadjusting means has an associated additional force-applying device for adjusting the height of the seat, the adjusting forces of the heightadjusting means and of the additional force-applying device being superimposed.

2. An adjustable height seat as claimed in claim 1, in which the additional force-applying device comprises a lever linkage including an actuating device in conjunction with a transmission lever on the seat.

3. An adjustable height seat as claimed in claim 2, in which the lever linkage of the additional force-applying device engages the seat independently of the height- adjusting means.

4. An adjustable height seat as claimed in claim 2, in which the lever linkage of the additional force-applying device engages the underframe of the seat.

5. An adjustable height seat as claimed in claim 2, in which the forcetransmission path from the transmission lever to the seat includes a disengageable loose bearing which transmits only perpendicular forces.

6. An adjustable height seat as claimed in claim 1, in which the additional force-applying device comprises a master cylinder controlled by an actuating device and operatively connected to a slave cylinder with the slave cylinder applying the additional height-adjusting force.

7. An adjustable height seat as claimed in claim 6, in which the slave cylinder comprises a gas spring in conjunction with a variable fluid pressure reservoir.

8. An adjustable height seat as claimed in claim 6 or claim 7, in which the master cylinder has a hydraulic- pre s sure conversion arrangement in the form of a stepped piston arrangement.

9. An adjustable height seat as claimed in any of claims 6 to 8, in which the actuating device includes a Bowden cable for transmitting the additional applied force.

10. An adjustable height seat as claimed in any preceding claim, in which the height-adjusting means comprises a spring of which the pre- loaded length is adjustable by means of the force-applying device.

11. An adjustable height seat as claimed in claim 10, in which the adjustable-length spring comprises a gas spring.

12. An adjustable height seat as claimed in claim 11, in which the gas spring is lockable.

13. An adjustable height seat as claimed in any of claims 10 to 12, in which the adjustable-length spring is actuated by means of a Bowden cable.

14. An adjustable height seat as claimed in claim 13, in which the Bowden cable is controlled by means of the actuating device.

16

15. An adjustable height seat as claimed in claim 12, in which a first Bowden cable is provided for the locking function of the gas spring and a second Bowden cable is provided for altering the pre-loaded length of the gas spring.

16. An adjustable height seat as claimed in claim 10, in which a transmission linkage is mounted in the direction of the force of the heightadjusting means, by which the effective length of the heightadjusting means is altered.

17. An adjustable height seat as claimed in claim 16, in which the transmission linkage comprises at least two members with a slide device between them which alters the spacing of the members.

18. An adjustable height seat as claimed in claim 17, in which the slide device comprises a wedge connection between a control wedge and at least one wedge surface on one of the members.

19. An adjustable height seat as claimed in claim 16, in which the transmission linkage comprises a control cam, by the angular position of which the effective length of the transmission linkage is altered.

20. An adjustable height seat as claimed in claim 16, in which the transmission linkage comprises a parallelogram linkage in which at least two opposed pivot points are connected by adjusting means to vary the diagonal length of the parallelogram linkage.

21. An adjustable height seat as claimed in any preceding claim, in which the height- adjusting means has an additional spring of which the pre-load is adjusted by means of the force-applying device.

17

22. An adjustable height seat as claimed in claim 21, in which the additional spring comprises a coil spring acting between two abutments, at least one abutment being movable by means of the force-applying device.

23. An adjustable height seat as claimed in any preceding claim, in which the additional force-applying device is arranged so that the direction of its force is opposed to the direction of the force of the heightadjusting means.

24. An adjustable height seat as claimed in claim 23, in which the additional force-applying device has tension means which lower the seat.

25. An adjustable height seat of the kind set forth substantially as described herein with reference to and as illustrated in Figures 1 to 4 of the accompanying drawings.

26. An adjustable height seat of the kind set forth substantially as described herein with reference to and as illustrated in Figures 5 to 8 of the accompanying drawings.

27. An adjustable height seat of the kind set forth substantially as described herein with reference to and as illustrated in Figures 9 to 11 of the accompanying drawings.

28. An adjustable height seat of the kind set forth substantially as described herein with reference to and as illustrated in Figures 12 and 13 of the accompanying drawings.

18

29. An adjustable height seat of the kind set forth substantially as described herein with reference to and as illustrated in Figure 14 of the accompanying drawings.