GB2070919A - A height-adjustable seat - Google Patents

Abstract

This invention provides a height-adjustable seat (e.g. for vehicles) comprising a fixed or fixable base (1) and a sitting portion frame (8) mounted thereon by four parallel links in pairs (9, 10), two at the front and two at the back, themselves pivotably mounted about respective transverse axes (6, 7) on the base and (11, 12) on the frame, and a device for adjusting the height of the frame comprising a control hand lever (M) angularly movable about a transverse axis through at most 180 DEG and a mechanism for irreversibly transforming angular movements of the hand lever into angular movements of at least one of the links, this mechanism comprising a plate (13) integral with the hand lever and revolving in a complementary housing (14) of transverse axis (O) in the base or frame, a bearing surface (15) (axis O') integral with and offset (e) relative to the plate, an eccentric (16) of revolution revolving in or on said bearing surface, and at least one rigid member (19) (20) connecting this eccentric to at least one point (17, 18) of the said one link (9, 10) so that rotation of the eccentric about the axis (O) of the flat plate (13) due to the angular movement of the hand lever (M) causes irreversible angular movement of the said one link (9, 10). In one modification, the front and rear links are not parallel. In a further modification, the eccentric is mounted directly on one of the links. <IMAGE>

Description

SPECIFICATION A height-adjustable seat The invention relates to adjusting the height of a seat, e.g. for a motor vehicle, parallel or substantially parallel to itself, this seat comprising a base and a sitting portion mounted on this base by means of four parallel links in pairs, i.e. two at the front and two at the rear, themselves pivotably mounted respectively about transverse axes on the base and on the sitting portion so as to form in particular two parallelograms.

It relates particularly, among these adjustable seats, to those which are controlled in an irreversible way by the angular movement of a hand lever whose total travel is at most equal to 180 and which include for this purpose a mechanism adapted to transform the angular movements of the hand lever into angular movements of at least one of the links which may be designated the "main link".

Known seats of this kind generally use complex linkages or toothed wheels having a complicated profile.

The present invention provides a seat comprising a fixed or fixable base and a sitting portion frame mounted thereon by four parallel links in pairs, two at the front and two at the back, themselves pivotably mounted about respective transverse axes on the base and on the frame, and a device for adjusting the height of the frame comprising a control hand lever angularly movable about a transverse axis through at most 180 and a mechanism for' irreversibly transforming angular movements of the hand lever into angular movements of at least one of the links, this mechanism comprising a plate integral with the hand lever and revolving in a complementary housing of transverse axis in the base or frame, a bearing surface integral with and offset relative to the plate, an eccentric of revolution revolving in or on said bearing surface, and a rigid member connecting this eccentric to at least one point of the said one link so that rotation of the eccentric about the axis of the flat plate due to the angular movement of the hand lever causes irreversible angular movement of the said one link, the eccentricity between the plate and the bearing surface being less than (R + r),u where R and r are the radii of the plate and bearing surface respectively and y is the coefficient of friction between the sliding parts.

Adjustable seats in accordance with the invention can also be essentially characterised in that their mechanisms adapted for transforming the angular movements of the hand lever into angular movements of the main link comprise a flat or pancake-shaped plate, cylindrical in revolution, integral with the hand lever and revolving in a complementary housing, with transverse horizontal axis, of the base or sitting portion frame, a bearing surface cylindrical in revolution offset by a "small" distance in the sense specified hereafter with respect to the flat plate and integral with this latter, an eccentric of revolution revolving in or on said bearing surface, and a rigid member connecting this eccentric to at least one point of the main link so that the rotations of said eccentric about the axis of the flat plate due to the angular movements of the hand lever cause irreversible angular movements of the main link.

In preferred embodiments, recourse may be had to one or more of the following arrangements: -the ratio between the diameter of the flat plate and that of the eccentric is less than 1.5 and preferably less than 1.4, -the eccentric is a disc projecting slightly from a small vertical plate, -the main link is integral with the eccentric or with the bearing surface in which the eccentric revolves and its pivotable mounting on the frame comprising the housing for the flat plate is ensured by means of a buttonhole also allowing vertical relative transverse sliding, -the member connecting the eccentric to the main link is a connecting arm integral with this eccentric, extending in a substantially horizontal direction and pivotably mounted on the main link, -in an adjusting device in accordance with the preceding paragraph, the main link is integral with a second bearing surface, cylindrical in revolution, having the same diameter as the preceding one and a second eccentric is provided revolving in this second bearing surface and a second connecting arm integral with this second eccentric, extending in a substantially horizontal direction and pivotably mounted on the second link situated on the same side of the seat as the main link, is also provided, -in an adjusting device in accordance with the preceding paragraph, the main link has the general form of a bell-crank lever with unequal arms whose bend is situated at the level of the pivoting axis of this kink on one of the two base or sitting portion frames, the small arm of this lever extending, in a substantially vertical direction, between this axis and the pivoting axis of the link on the corresponding connecting arm, and the end of the long substantially horizontal arm of said bell-crank lever being pivotably mounted on the other frame, -in an adjusting device in accordance with the preceding paragraph, the ratio between the respective lengths of the long arm and of the short arm of the bell-crank lever is of the order of 3, -in an adjusting device in accordance with the preceding paragraph, the distance between the axis of the flat plate and that of the eccentric is of the order of 5 mm and the vertical travel of the sitting portion is of the order of 30 mm, -in the embodiments in which the eccentric is connected respectively to two links by means of two connecting arms, the mounting of one of the links on the corresponding connecting arm or on the sitting portion is ensured by means of a buttonhole also allowing mutual transverse sliding in a substantially horizontal direction, +he connection between the eccentric and one at least of the links is ensured by means of an auxiliary flat plate and eccentric mechanism of the above kind controlled from an auxiliary lateral hand lever.

The invention comprises, apart from these principal arrangements, certain other arrangements which are used preferably at the same time and which will be more explicitly discussed hereafter.

In what follows, some preferred embodiments of the invention will be described with reference to the accompanying drawings, in a way which is of course in no wise limiting.

Figures 1 and 2 of these drawings show schematically in longitudinal section a heightadjustable vehicle seat constructed in accordance with the invention, in respectively the highest position of the seat and its lowest position.

Figure 3 is a transverse vertical section along Ill-Il of Fig. 1.

Figure 4 is a top view, with parts cut away, of the same seat for the highest position of the seat.

Figures 5 and 6 illustrate similarly to Fig. 1 two other variations of seats in accordance with the invention The seat whose height is to be adjusted comprises, in each illustrated case: -a fixed base 1 formed essentially from two parallel longitudinal angle-irons 2 which each have a horizontal flange 3 fixed to the floor of the vehicle, generaliy through a longitudinally adjustable slide 4 (Figs. 3 and 4) and a vertical flange 5, -a sitting portion frame which has been shown schematically by the dash-dot line 8 in Fig. 1, ---and four links slightly inclined with re specs to the horizontal connecting this frame 8 to base 1, i.e. two parallel rear links 9 and two parallel front links 10, each of these links being, on the one hand, interlocked at the bottom with a transverse tube 6 or 7 pivota bly mounted on the vertical flanges 5 of the two angle-irons and, on the other hand, pivotably mounted at the top to the frame 8 by means of pins 11, 1 2 forming pivots.

The mechanism for adjusting the height of this seat comprises: -a lateral control hand lever M, -a flat or pancake-shaped plate, cylindrical in revolution, 1 3 integral with this hand lever M and revolving in a complementary housing 14 of the corresponding vertical flange 5, the fixed axis 0 of this housing extending in a transverse horizontal direction, -an offset internal bearing surface 1 5, cylindrical in revolution, hollowed out in this flat plate 1 3 and whose transverse horizontal axis 0' is parallel to axis 0 and is offset from this axis by a distance or eccentricity e, -a crank plate or "eccentric" 1 6 revolving in this offset bearing surface 15, -and a rigid member connecting this eccentric 1 6 to one of the points of one of the two links 9 and 10 disposed on the side considered of the seat.

The whole is here mounted so that: -the hand lever extends substantially along the intersection of a longitudinal vertical plane extending by the sid of the seat and of the plane of axes 0 and 0', -the control handle of this hand lever is disposed on the same side of axis 0 as axis 0', -and its total angular travel about axis 0 is between 1 20 and 180 this travel extending substantially symmetrically with respect to the transverse vertical plane which contains axis 0, between a front endmost position (shown schematically in Fig. 1) corresponding to the highest condition of the seat and an endmost rear position (shown schematically in Fig. 2) corresponding to the lowest condition of the seat.

When hand lever M describes this angular path, axis 0' effects the same angular movement as the hand lever about axis 0.

It is the horizontal component of this movement of axis 0' which is transmitted to one of the links to cause its inclination to vary about the axis of the lower fixed tube 6 or 7 with which it is integral and thus to modify the height of seat 8.

In the embodiment of Figs. 1 to 4, each of the two links 9 and 10 has the form of a triangle or bell-crank lever and these two links are parallel to each other.

The section of each bell-crank lever which extends between its respective pivots on the base (6 and 7) and the sitting portion (11 or 12) forms the substantially horizontal long arm of said lever, its short arm extending, in a substantially vertical direction, from the lower fixed tube 6 or 7 to an upper pivot 17 or 18.

The eccentric 1 6 is here connected to the rear link 9 by means of a connecting arm 1 9 integral with this eccentric and pivotably mounted on the upper pivot 1 7 of this link.

Furthermore, a second connecting arm 20, similar to connecting arm 1 9, provides a similar connection between the eccentric system and the upper pivot 1 8 of the front link 10, which is obtained in the following way: eccentric 1 6 is formed by a circular disc forming a slight projection on a small metal plate forming connecting arm 1 9 (see Fig. 4), this disc being formed by partial stamping of this small plate which creates at the same time on the other face of said small plate a circular cavity 21 having the same diameter as the disc, i.e. the same diameter as above bearing surface 15, and there is provided on connecting arm 20 a second disc 22, identical to disc 16, which is jointingly housed in cavity 21 so as to cause it to revolve therein.

The whole or parts 13, 1 6 and 22 are assembled axially together by means of a bolt 23-nut 24-resilient washer 25 system having axis 0' (Fig. 4).

This construction allows the eccentric-offset cylindrical bearing surface pair to be split into two and one eccentric of such a pair to be interlocked with each of the above upper pivots 17 and 18.

It allows furthermore the two connecting arms to be formed by identical parts, which simplifies the manufacture thereof.

The whole must be arranged so that the controls of the mechanism are irreversible in this sense that only the angular movements of hand lever M mustcause the angular movements of connecting arms 9 and 10, and not the reverse, under the effect for example of a high vertical stress exerted downwards or upwards on the sitting portion.

To obtain this result, the eccentricity e is given a relatively "small" value, i.e. less than the maximum value eM given by the formula = = (R + r)y, where R and r are respectively the radii of the flat plate 1 3 and of the eccentric 1 6 and where p is the coefficient of friction between the sliding parts (respectively 13-14, 15-16 and 21-22).

It can be seen that, for given values of this coefficient of friction and of radius R, the maximum value eM is larger the greater radius r.

Furthermore, the vertical adjustment travel of the mechanism is substantially equal to Ke, in which expression the letter K designates the ratio between the substantially horizontal long arm and the substantially vertical short arm of lever 9, i.e. the ratio between the distance separating the axes of parts 6 and 11 and the distance separating the axes of parts 6 and 17.

It is then advisable to give to eccentricity e the highest value possible, compatible of course with the condition of irreversibility expressed above.

This is why the radius r of each eccentric (16, 22j is given a relatively high value with respect to that of flat plate 13, the ratio between the second and the first being therefore relatively small.

This ratio is generally less than 1.5 and preferably less than 1.4.

The ratio K, as far as it is concenred, is advantageously of the order of 3 so that, if the eccentricity e is of the order of 5 mm, the vertical adjustment travel is of the order of 30 mm.

Under these conditions, the radius R is advantageously of the order of 50 to 60 mm and the radius r of the order of 35 to 40 mm.

There can further be seen in the drawings: -a compensation spring 26 (Fig. 4) adapted to constantly urge the sitting portion upwards so as to compensate for the average weight of a person sitting in the seat, this spring being advantageously of helical tension type, fastened at one of its ends to a lug 27 welded to the horizontal flange 3 of the angleiron concerned 2 and at its other end to a lug 28 interlocked with link 9 by respectively welding these two latter elements to tube 6, at 29 and 30, -an aperture 31 provided in vertical flange 5 of angle-iron 2 for allowing movements of pin 12, -apertures 38, 39 similarly provided in said vertical flange 5 for receiving the extensions of pivots 1 7 and 18, these pivots and their extensions being themselves capped by lock washers or similar 40, 41 at their ends so as to ensure the relative axial positioning of the three parts through which they pass (9, 19, 5 or 20, 10, 5), -and a substantially horizontal buttonhole 32 or 33 provided at the level of pivot 1 8 (in lever 10) or at the level of pin 1 2 (in sitting portion frame 8) so as to make possible the slight variations of the horizontal distance between the ends of the deformable V formed by the two connecting arms 1 9 and 20 during operation of the mechanism.

Tubes 6 and 7 interlock in pairs therebetween links 9 and 1 0 on the two sides of the seat so that the whole may be controlled from a single mechanism situated on one side of this seat.

The operation of this mechanism is the following.

At the beginning, it is assumed that the seat is in its high position, hand lever M being disposed at its frontmost position as shown in Fig. 1: eccentric 1 6 is then also disposed at the front end of its travel and the same goes for pivots 1 7 and 1 8 of connecting arms 9 and 10.

If hand lever M is urged in the direction of arrow F, i.e. upwards and rearwards, eccentrics 1 6 and 22 also move upwards and rearwards about axis 0 and the backward motion component of this movement is transmitted by connecting arms 1 9 and 20 to pivots 1 7 and 18, as shown by arrow H, which causes these connecting arms to rotate while lowering pins 11 and 1 2 in the direction of arrow V; sitting portion 8 is then lowered parallel or practically parallel to itself according to the choice which has been made of buttonholes 32 or 33.

This control may be continued to the rear end of the travel of hand lever M, which position has been shown in Fig. 2 and which corresponds to the maximum low position of the seat.

It may also be interrupted at any intermediate position of the hand lever, each of these positions corresponding to a stable equilibrium, whatever the weight of the person seated, owing to the irreversibility of the mechanism.

The raising of the seat may be controlled just as simply by a simple angular movement of hand lever M in the reverse direction to the preceding one.

Without departing from the scope of the invention, numerous variations of such a parallel type raising may be imagined, controlled like the preceding one from a lateral hand lever by means of an irreversible-effect eccentric mechanism.

Two of these variations have been shown in Figs. 5 and 6, in which the parts identical with or comparable to those already described above have been given the same reference numbers as previously.

The variation of Fig. 5 differs essentially from the preceding one in that the two bellcrank levers 9 and 10 are no longer parallel to one another: rear lever 9 has again an orientation comparabie to the preceding one, i.e. with the fixed tube 6 at the bottom, pivot 1 7 at a short distance above this tube, and pin 11 disposed horizontally rearwardly of pivot 17; but the orientation of the front lever 10 is reversed with respect to the preceding one, fixed tube -7 being here disposed at the top, pivot 1 8 at a short distance beiow this tube, and pin 1 2 horizontally in front of fixed tube 7.

When the sitting portion is in its high position shown in Fig. 5, the two short arms of levers 9 and 10 converge slightly upwardly, at a point situated in the vertical transverse plane which contains axis 0.

This slight convergence is advantageously chosen so that it gives place to a parallelism of the two short arms in question in the middle of the adjusting travel and to a slight divergence of these short arms for the maxi mllm low position of the seat, the maximum opening angies being practically the same for the above slight convergence and slight diver gence.

This variation of Fig. 5 allows the assembly zones of the sitting portion on pins 11 and 1 2 to be placed horizontally outside base 1.

Moreover, because this variation has like the preceding one two connecting arms acting directly and similarly on the two links situated on the same side of the seat, it ensures a good distribution of the control stresses in front of and behind the sitting portion.

In the variation of Fig. 6. eccentric 1 6 is mounted directly on triangular lever 9 in place of pivot 1 7 of the first variation above, instead of being connected to this latter by means of a connecting arm.

In this case, lever 9 is placed in front of the seat and is pierced with a buttonhole 34 which jointingly fits round tube 7 while allowing transverse sliding of said lever on this tube in a substantially vertical direction.

Here pins 11 and 1 2 of the two levers or links 9 and 10 are connected horizontally together by means of a rigid stringer 35, which may form part of the sitting portion frame.

This variation is advantageous in constructions in which the space available for receiving the adjusting mechanism and its control hand lever is in particular located in front of the sitting portion.

In all cases, means may be provided for, on the one hand, giving to control hand lever M a relatively large length during adjustment operations so as to reduce the effort required for these operations and, on the other hand, to retract this hand lever to the maximum outside operating periods, for example by providing a hand lever which is foldable or telescopically extendable.

The seat according to the invention can have advantages, e.g. simplicity of manufacture, and robustness, resulting in long operating life and economy.

The invention is of course not limited to the specific embodiments above but includes variations thereof, e.g.: those where the bearing surface, cylindrical in revolution, connected to the flat plate and coacting with the eccentric are external instead of being internal, defining then for example the outside of a circular body integral with the flat plate, the eccentric then not having the form of a disc, but that of a ring or circular recess through which this bearing surface or body jointingly pass, such a recess being able to be directly provided in connecting arms 1 9 and 20 of the first two embodiments described above or in the triangular lever 9 of the third embodiment;; those where an additional mechanism, using advantageously also an irreversible eccentric system such as defined above, is provided for modifying individually the inclination of one at least of the links, preferably the front link, and so the overall inclination of the sitting portion, by being mounted in place of pivot 1 7 or 1 8 above, the "pancake-shaped" flat plate 36 of this mechanism (shown exclusively in Fig. 4 so as not to obscure Figs. 1 and 2), integral with a control hand lever M', then revolving in the link considered and its eccentric" 37 being "connected" to the corresponding connecting arm, preferably by being mounted so as to revolve in a circular opening provided in this connecting arm; ; those where the housing 1 4 for each flat plate 1 3 is provided on the sitting portion frame instead of being provided on the base frame, a solution which allows hand lever M to rise and descend at the same time as the sitting portion; and those where the control handle of the hand lever M is disposed, in relation to the axis 0, on the side opposite that where axis O' is to be found.

Claims (11)

1. A seat comprising a fixed or fixable base and a sitting portion frame mounted thereon by four parallel links in pairs, two at the front and two at the back, themselves pivotably mounted about respective transverse axes on the base and on the frame, and a device for adjusting the height of the frame comprising a control hand lever angularly movable about a transverse axis through at most 1 80 and a mechanism for irreversibly transforming angular movements of the hand lever into angular movements of at least one of the links, this mechanism comprising a plate integral with the hand lever and revolving in a complementary housing of transverse axis in the base or frame, a bearing surface integral with and offset relative to the plate, an eccentric of revolution revolving in or on said bearing surface, and a rigid member connecting this eccentric to at least one point of the said one link so that rotation of the eccentric about the axis of the flat plate due to the angular movement of the hand lever causes irreversible angular movement of the said one link, the eccentricity between the plate and the bearing surface being less than (R + r)y where R and r are the radii of the plate and bearing surface respectively and IL is the coefficient of friction between the sliding parts.

2. A seat according to claim 1 in which the ratio between the diameter of the plate and that of the eccentric is less than 1.5.

3. A seat according to claim 2 in which the ratio between the diameter of the plate and that of the eccentric is less than 1.4.

4. A seat according to any one of claims 1 to 3 in which the eccentric is a disc projecting slightly from a plate.

5. A seat according to any one of the preceding claims in which the said one link is integral with the eccentric or with the bearing surface in which the eccentric revolves and is pivotably mounted on the part providing the housing for the plate by means of a buttonhole also allowing relative sliding upwards and downwards.

6. A seat according to any one of the preceding claims in which the rigid member is a connecting arm integral with the eccentric, extending substantially parallel to the base and pivotably mounted on the said one link.

7. A seat according to claim 6 in which the connecting arm is integral with a second bearing surface having the same diameter as the first-mentioned one, there being a second eccentric revolving in this second bearing surface and a second connecting arm integral with this second eccentric, extending substantially parallel to the base and pivotably mounted on a second link situated on the same side of the seat as the said one link.

8. A seat according to claim 7 in which the said one link has the general form of a bell-crank lever with unequal arms whose bend is situated adjacent to the pivoting axis of this link on one of the base and frame, the short arm of this lever extending substantially perpendicular to the base between this axis and the pivoting axis of the link on the corresponding connecting arm, and the end of the long arm of said bell-crank lever being pivotably mounted on the other of the base and frame.

9. A seat according to claim 8 in which the ratio between the lengths of the long and short arms of the bell-crank lever is of the order of 3.

10. A seat according to claim 9 in which the distance between the axes of the plate and associated eccentric is of the order of 5 mm and the travel of the frame is of the order of 30 mm. in height.

11. A seat according to any one of claims 7 to 10 in which the mounting of one of the links on the corresponding connecting arm or on the frame is by means of a buttonhole also allowing relative sliding substantially parallel to the base.

1 2. A seat according to any one of the preceding claims in which an auxiliary circular plate and circular eccentric mechanism controlled by an auxilliary hand lever are interposed in the connection between the first eccentric and one at last of the links so as to allow the independent adjustment of the inclination of this link and hence of the inclination of the frame.

1 3. A height-adjustable seat substantially as hereinbefore described with reference to Figs. 1-4 of the accompanying drawings.

1 4. A height-adjustable seat substantially as hereinbefore described with reference to Fig. 5 of the accompanying drawings.

1 5. A height-adjustable seat substantially as hereinbefore described with reference to Fig. 6 of the accompanying drawings.

1 6. A vehicle provided with a seat according to any one of claims 1 to 1 5.