GB2097248A

GB2097248A - A seat

Info

Publication number: GB2097248A
Application number: GB8133493A
Authority: GB
Original assignee: Bremshey AG
Current assignee: Bremshey AG
Priority date: 1981-02-21
Filing date: 1981-11-06
Publication date: 1982-11-03
Also published as: IT1140475B; DE3106513A1; ES269277U; IT8124904A0; FR2500382A1; BR8107222A; ES269277Y; SE8106567L; FR2500382B3

Abstract

A seat includes a guide mechanism 6 which supports the upper seat member 1, 2 in a pivotal manner relative to a lower member 3, with said mechanism comprising a hydraulic-pmeumatic or pneumatic suspension means 8, e.g. a roller bellows, which cushions seat vibrations and whose volume for influencing the natural seat frequency is increased by an additional volume of an additional pressure vessel 9 associated with a pressure cylinder 8a of the suspension means 8: said additional pressure vessel is formed by a hollow body 4, 5, 1b or 2b of seat component connected to the cylinder 8a by hoses 10, or by a flat vessel extension of cylinder 8a and located in a space 3a beneath the seat. <IMAGE>

Description

SPECIFICATION A seat The present invention relates to a seat, especially a driver's seat, including a guide mechanism which supports an upper seat portion in a pivotal manner relative to a lower portion, with said guide comprising hydro-pneumatic or pneumatic suspension means, which cushions seat vibrations and whose volume for influencing the natural seat frequency is increased by the volume of an additional pressure vessel associated with the pressure cylinder of the suspension means.

Some arrangements for such seats are already known. Beacause of the additional volume which is co-ordinated separately with the pressure cylinder of the hydro-pneumatic or pneumatic suspension, the pressure cylinder may have smaller volumetric dimensions, including the components which co-operate directly with the pressure cylinder in order to achieve a simple and trouble-free installation (especially in "flat" seat designs), without reducing the overall volume of the suspension system required to achieve a lower spring characteristic- a low rise in pressure and a smaller frictional value.In addition, a low neutral frequency of the seat is ensured, whereby this frequency is adjustable so that it is sufficiently remote from the natural frequencies of the vehicle shell or body and so that the main excitation or resnance frequency of the vehicle body does not increase substantially further. Although in the long run, despite the use of a small-volume suspension system by means of separate additional volumes, a frequency stabilization is achieved to improve the seat comfort, the additional volume nevertheless at least necessitates the extra expenditure on an appropiate additional pressure vessel requiring a further suitable installation space at another location on the seat. Consequently, a seat of such a design whilst having a low structure, is nevertheless still relatively bullky, heavy and generally expensive.

It is an object of the invention to provide a seat of the above-described type wherein the pressure vessel which is required for the additional volume does not constitute any additional effective expenditure. or at least does not require more installation space than is necessary for a seat without such an additional volume for the hydro-pneumatic or pneumatic suspension system.

According to the present invention there is provided a seat including a guide mechanism which supports the upper seat member in a pivotal manner relative to a lower member, with said mechanism comprising a hydraulicpneumatic or pneumatic suspension means which cushions seat vibrations and whose volume for influencing the natural seat frequency is increased by an additional volume of an additional pressure vessel associated with a pressure cylinder of the suspension means, said additional pressure vessel being formed by a hollow body of an existing seat component or is disposed and/or shaped so as to match an existing hollow or free space in the seat framework.

In this manner, a seat of the above-described construction is provided wherein already existing free installation space, which was inaccessible in the past for the direct suspension elements, or the already existing hollow space in existing components of the seat is utilized in order to obtain the additional volume for the hydro-pneumatic or pneumatic suspension system.Since effectively no additional installation space is required therefor in the substructure or at another location on the seat, and since it is even possible that an actual pressure vessel for the additional volume can be eliminated, a seat having a hydropneumatic or pneumatic suspension with such an additional volume is not only less bulky and less costly and lighter compared with such known seat designs, but it is also correspondingly superior to the seat constructions having large full-volume, hydro-pneumatic or pneumatic suspension, without such an additional volume.

One particularly advantageous embodiment of the invention is achieved in that the hollow body, which serves as the additional pressure vessel, is formed by a hollow support component of the seat framework, for example, by the frame of the seat member or by the frame of the backrest.

Especially in the case of seats having a seat and/or back-rest member which is resistant to compression and is manufactured by the plastics blow-moulding method, it is advantageous, in accordance with a further embodiment for the hollow body, which serves as the additional pressure vessel, to be formed by a hollow, self-supporting body of the seat or back-rest member.

Scarcely accessible hollow or free space in the seat framework may advantageously be used to accommodate the additional pressure vessel in a trouble-free manner if the additional pressure vessel extends as a flat vessel extension of the pressure cylinder so as to match the hollow or free space between the longitudinal seat guides.

The spring characteristic and therewith the natural frequency of the seat may advantegeously be designed to be adjustable by changing the overall volume of the suspension, in that the volume in the additional pressure vessel is variable, for example, by means of a filler medium, a diaphragm-hose or pistonadjusting device which reduces the capacity of this vessel.

The invention will be described further, by way of example, with reference to the accom panying drawings, in which: Figure 1 is an elevational view of a seat viewed from the front; Figure 2 is a side-elevational view of the seat of Fig. 1; Figure 3 is a front-elevational view of a seat comprising a further embodiment of the invention; and Figure 4 is a side view of the seat of Fig. 3; A seat according to the invention is illustrated as comprising a driver's seat and has a seat member 1, a back-rest 2 and a plate-like lower member 3. The seat member 1 comprises a cushion or seat pad 1 a and a rectangular supporting frame 4 made of tubing. The back-rest 2 is provided with a support cushion pad 2a and has a U-shaped rest supporting frame 5 made of tubing. An armrest (not shown) may possibly also be provided and be made wholly or partially of tubing.The upper seat part comprising the seat member 1 and the back-rest 2, is supported in a pivotal manner relative to the lower member 3 by means of a guide mechanism 6 which may, for example, be a scissors lever mechanism known per se. In its lowermost position, such a mechanism can pivot in an extremely compact and flat manner, so that the seat as a whole requires less installation space and is also,therefore, very suitable for more restricted installation conditions. It is a seat of the socalled "low" or "flat" type of construction.

The entire seat is forwardly and backwardly displaceable by means of the lower member 3, which is connected to a pair of extensible longitudinal guide rails 7 known per se with the entire seat resting on these rails. The plate-like lower member 3 engages around the longitudinal guide rails 7, located on both sides thereof, in such a manner that the Ushaped hollow profile 3a of the lower member 3 is formed, as can be seen in Figs. 1 and 3, with profile being close to the floor.

A hydro-pneumatic suspension system (known per se), or a pneumatic suspension system is provided for cushioning the upper seat member. One of these systems may have a resilient or compression leg or, as shown, a roller bellows mechanism 8 which is secured, on the base side, to its pressure cylinder 8a in the hollow profile 3a on the lower member 3, while it is supported on the guide rod 6a of the guide mechanism 6 by means of its piston member 8c located on the top side on the roller bellows 8b. This type of pneumatic spring is supplied with compressed air by means of a pipeline via a valve 8ewhich is controlled in dependence upon the pivotal movements of the seat.

In order to accommodate the seat shown, the roller bellows mechanism 8 has such small volume dimensions that it does not impair the extremely advantageous installation features of the flat designs. Consequently, however, the pressure volume of the roller bellows mechanism 8 is also correspondingly small. This, therefore, also produces a higher spring characteristic, a higher rise in pressure and, finally, a higher overall friction of the pneumatic spring. Moreover, the natural frequency of the seat still also lies within the frequency spectrum of the vehicle body of modern motor vehicles. Even in the range af the main resonance or excitation frequency of these vehicles, a seat having such a natural frequency cannot absorb or reduce any vibrations, but instead increases these vibrations further.One possible, obvious counter measure to avoid this situation would be an intensive damping. This in turn would lead to a substantially poorer reduction of the overall vibrations, apart from the disadvantegeous expenditure for this damping.

In order to obviate these disadvantages and yet be able to use the small-volume pneumatic spring without impairing the advantegeous installation features of the flatly constructed seat types, the volume of this pneumatic spring or of the pneumatic-hydraulic spring which may possibly be provided, is increased by the additional volume of an additional pressure vessel 9 associated with the pressure cylinder 8a. Consequently, therefore, the volume of the roller bellows mechanism 8 is increased as a whole, with the result that the spring characteristic is lower, the rise in pressure is low, the overall friction of this mechanism is lower, the natural seat frequency is adjustable sufficiently remotely from the natural frequency of the vehicle body or shell, and lastly the supension behaviour of the seat itself is stabilized and comfortable.

The additional pressure vessel 9 may be formed by an existing hollow body of the seat, preferably by one of the supporting, hollow seat components which are tightly self-contained such as, for example, by the supporting frame 4 of the seat member 1, this frame being made of tubing, by the supporting frame 5 of the rest or by a hollow, compression-resistant body 1 b, 2b of the seat member 1 or of the backrest cushion 2a. A compression-resistant and self-supporting body of this type is used especially for seats manufactured by the plastics blow-moulding method. Because of the above-described utilization of the hollow cavities in existing seat components, there is a considerable saving of installation space and component costs. Flexible, compression-resistant hoses 10 are provided for the compressed-air connection between the pressure cylinder 8b of the pneumatic spring and the seat component 4, 5, 1 b or 2b which is used as the additional pressure vessel 9.

However, the additional pressure vessel 9 may also be disposed, for example, so as to utilize the installation space or room for movement which remains free between the scissors system 6 and pneumatic spring 8 and which is identical to the freely-remaining hollow space in the hollow profile 3a. In this case, the additional pressure vessel may comprise a flat vessel extension 11 of the pressure vessel 8a of the roller bellows mechanism 8.This flat vessel extension 11 is directly attached to the pressure cylinder 8a or is connected to this cylinder by a conduit and, in addition, is so installed in the hollow space or in the hollow profile 3a and, as can be seen from Fig. 4, is so moulded in said hollow space that, on the one hand, it can absorb the necessary, additional compressed-air volume but, on the other hand, it only occupies the space which, even in the lowest deflection position of the guide mechanism 6 or with scissors which swing flatly one into the other, does not hinder the pivotal movement thereof.

Moreover, the volume in the additional pressure 1 b, 4, 5 or 11 may also be of a variable form, for example, by means of filler media and/or diaphragms, blowers or hoses so as to change the volume in the hollow cavities of the members 1 b, 2b, 4, 5 or 11. In this connection, there is shown in Fig. 2 a piston 12, which is adjustable by means of a screw spindle 1 2a, in the additional pressure vessel formed by the supporting frame 4 of the seat.

Claims

1. A seat including a guide mechanism which supports the upper seat member in a pivotal manner relative to a lower member, with said mechanism comprising a hydraulicpneumatic or pneumatic suspension means which cushions seat vibrations and whose volume for influencing the natural seat frequency is increased by an additional volume of an additional pressure vessel associated with a pressure cylinder of the suspension means; said additional pressure vessel being formed by a hollow body of an existing seat component or is disposed and/or shaped so as to match an existing hollow or free space in the seat framework.

2. A seat as claimed in claim 1, in which the hollow body which serves as the additional pressure vessel is formed by a hollow support component of the seat framework.

3. A seat as claimed in claim 2, in which the hollow support component is the frame of the seat member or the frame of the backrest of said seat.

4. A seat as claimed in claim 1, in which the hollow body, which serves as the additional pressure vessel is formed by a hollow self-supporting body of the seat or backrest member.

5. A seat as claimed in claim 1, in which the additional pressure vessel extends between the longitudinal seat guides as a flat vessel extension of the pressure cylinder so as to match the existing hollow or free space.

6. A seat as claimed in any of claims 1 5, in which the effective volume in the additional pressure vessel is adjustable.

7. A seat as claimed in claim 6, in which the effective volume in the additional pressure vessel is adjustable by means of a filler medium, or a diaphragm, hose- or piston-adjusting device which is capable of reducing the capacity of this vessel.

8. A seat substantially as herein described with reference to and as illustrated in Figs. 1 and 7 or Figs. 3 and 4 of the accompanying drawings.