GB2097459A - Fastening for seat backs - Google Patents

Abstract

A fastening is provided to permit plates 14 to be held in any one of a number of angles with respect to the framework 11, 12, 24. Each plate 14 has a series of recesses 20 on an arc of a circle 19, centred at 15, the pivot point of each plate. Section 22 of each rod 23 engages a selected recess 20 to hold the plate where required. Spring 32 biases each rod to the fastening position from which it may be released by lifting end 31, causing both rods to pivot about studs 28. A seat back is intended to be fitted across plates 14, being attached at each end to flanges 16; the fastening will then hold the back at a selected angle of rake. <IMAGE>

Description

SPECIFICATION A locking device The present invention relates to a locking device for releasably locking two mutually movable members of a vehicle chair of other chair in selectable, stepwise adjustable positions relatively to each other.

More particularly, the invention relates to such a locking device of the kind comprising two parallel rows of recesses, located in spaced apart positions on one of said members, and two locking means, adapted to cooperate with respective ones of said rows of recesses and located each on one arm of a respective one of two double-armed levers which are swingably supported by the other member, each lever being swingable between a locking position, in which its locking means may extend into a recess in the corresponding row of recesses for locking engagement with wall portions of said recess, and a release position, in which said locking means is out of engagement with said row of recesses, the two levers being spring-biased towards their locking positions from which they may be swung together to their release positions by means of a common operating means, connected to one of said levers, when an adjustment of the relative positions of the two members is to be effected.

An object of the invention is to provide a new and improved locking device of said kind which is suited especially for releasably locking two mutually swingable members of a chair in adjustable positions with respect to each other.

However, it should be noted that the invention may be favourably applied also on devices for releasably locking members arranged for rectilinear displacement relatively to each other.

According to the invention, for said object, there is provided a locking device of the kind initially specified which is characterized primarily in that the two levers extend substantially in line with each other and after each other between the two rows of recesses, said locking means being located at the outer arms of the two levers, while the inner arms of the two levers have adjacent cooperating end portions through which a movement from the locking position to the release position of the lever connected to said operating means may be transmitted to the other lever to cause the latter simultaneously to move from its locking position to its release position.

Further characteristics of the invention will appear from the claims and the following detailed description, in which, by way of example only, the invention will be described in further detail with reference to the accompanying diagrammatic drawings, in which: Figure 1 shows a front view, partially in section, of an upper portion of a support for the backrest of a vehicle chair and two mountings for the backrest which are swingably connected to the support, and a locking device for releasably locking the two backrest mountings in stepwise adjustable positions relatively to the support; and Figure 2 shows a side elevation, in section, taken along line Il-Il in Figure 1.

In the drawings, reference numeral 10 generally designates a support for a backrest of a vehicle chair. Said support comprises two parallel upright posts 11 which suitably may consist of tubes of squared or rectangular cross-section. A transverse beam 1 2 is rigidly secured to posts 11 at their upper ends. Said transverse beam 1 2 consists of a U-profile member having, at each end thereof, a forwardly extending tongue 13, formed by a bent end portion of the web of said member.

Each tongue 1 3 carries a plate 14 which is swingably connected to the tongue 1 3 by means of a pivot pin formed by a rivet 1 5. The two plates 14 are provided with bent-out flanges 1 6 which extend perpendicularly to the parallel flat main portions of said plates. As diagrammatically illustrated in dash-dotted lines in Figure 2, a rigid body portion 17 of a backrest may be secured to flanges 16, for instance by means of threaded bolts extending through bores 1 8 in flanges 1 6.

When body portion 17 has been secured to flanges 16, the two plates 14, which serve as mountings for the backrest, will be rigidly connected to each other. Hereby they will be forced to swing in unison around pivot pins 1 5.

A locking device is provided for releasably locking the backrest in a selected stepwise adjustable inclination with respect to support 1 0.

Said locking device comprises on the one hand a row of recesses 20 in each plate 14. Within each row, said recesses 20 are located along a circular arc 1 9 and they are separated from each other by teeth 21. On the other hand, the locking device also comprises two locking means adapted to cooperate each with one of said rows of recesses 20. Each such locking means is formed by one arm 22 of a lever 23 which is swingably mounted in support 10 in a manner to be described more in detail below.

Reference numeral 24 designates a tubular member of rectangular cross-section serving as a supporting means for the two levers 23. Said tubular member 23 is rigidly secured to the two posts 11 of support 1 0 and extends horizontally and parallel to transverse beam 1 2 between the two plates 14, the free ends of which are located at a short distance from the corresponding ends of member 24. Along the major portion of their length, the two levers 23 are received within tubular member 24. More particularly, said levers 23 extend generally in line with each other and after each other along the longitudinal axis 25 of member 24. At the transition between its outer arm 22, which acts as a locking means, and its inner arm 26, each lever 23 has a V-shaped portion 27.Each lever is swingably mounted within tubular member 24 my means of said portion 27 which has its tip, or apex, received between an outer bearing means, formed by one of the shorter side walls 24' of member 24, and an inner bearing means formed by a pin 28, extending between the two broader side walls 24" of member 24 which serve as guiding surfaces for levers 23. Said pin 28 may for instance consist of a rivet mounted in walls 24". At their adjacent free ends, the inner arms 26 of the two levers 23 have overlapping end portions 29 provided with flat contact surfaces 30 facing each other. When levers 23 are in the position shown in Figure 1, the two contact surfaces 30 are located at a short distance from each other whereby a small free clearance is formed between them.The outer arm 22 of lever 23 located to the right according to Figure 1 is provided with an integral extension 31 forming a manual operating means.

Reference numeral 32 designates a leaf spring having a flat central portion 32' resting against the inner side of the lower wall 24' of member 24 and two end portions 32" which extend in inclined inward and upward directions from portion 32' and act against the lower side of the inner arms 26 of levers 23 at a short distance from end portions 29. Hereby, spring 32 tends to maintain the two levers 23 in their positions shown in the drawings, wherein portions 22' of the outer arms 22 of levers 23, located immediately outside the ends of tubular member 24 and acting as locking means, are received in a pair of corresponding recesses 20 in plates 14 and held in locking engagement with the walls of said recesses.

The two levers 23 are made from straight rods of circular cross-section which are subjected to mutually equal bending and forming operations to form the V-shaped portions 27 and end portions 29. As can be seen from Figure 1, levers 23 are mounted in member 24 in mutually inversed positions.

Above the row of recesses 20 and teeth 21 in each plate 14 there is provided a continuous slot 33 which extends along said row of recesses and teeth. Said slot 33 serves to receive the corresponding locking means 22' temporarily during an adjustment of the inclination of the backrest.

By means of operating means 31, the two locking means 22' may be moved from their locking positions shown in the drawings, in which they are located in locking engagement with a pair of corresponding recesses 20 in plates 14, to release positions, in which they are located within slots 33 and thus out of the way of teeth 21 which may pass freely below them. To move the locking means 22' from their locking positions to their release positions, it is sufficient to apply an upward force of sufficient magnitude on operating means 31. When the backrest and the plates 14 have been moved to the desired inclined position, operating means 31 is released, causing locking means 22' to return to their locking positions under the action of the forces applied from leaf spring 32. The small clearance existing between contact surfaces 30 when levers 23 are in their locking positions serves to ensure that both locking means 22' will be brought into firm contact with the bottom of the respective recesses 20 in plates 14.

The invention is not restricted to the embodiment above described and shown in the drawings. Thus, may modifications are feasible within the scope of the invention. For instance, instead of leaf spring 32, a helical spring threaded on adjacent end portions of the inner arms 26 of levers 23, not overlapping each other, may be used to spring-bias the two levers towards their locking positions. Said helical spring may also serve to transmit movement from the lever provided with the manual operating means to the other lever during the movement of both levers from their locking positions to their release positions.

Claims (10)

1. A locking device for releasably locking two mutually movable members of a vehicle chair of other chair in selectable, stepwise adjustable positions relatively to each other, said device comprising two parallel rows of recesses, located in space apart positions on one of said members, and two locking means, adapted to cooperate with respective ones of said rows of recesses and located each on one arm of a respective one of two double-armed levers which are swingably supported by the other member, each lever being swingable between a locking position, in which its locking means may extend into a recess in the corresponding row of recesses for locking engagement with wall portions of said recess, and a release position, in which said locking means is out of engagement with said row of recesses, the two levers being spring-biased towards their locking positions from which they may be swung together to their release positions by means of a common operating means, connected to one of said levers, when an adjustment of the relative positions of the two members is to be effected, characterized in that the two levers extend substantially in line with each other and after each other between the two rows of recesses, said locking means being located at the outer arms of the two levers, while the inner arms of the two levers have adjacent cooperating end portions through which a movement from the locking position to the release position of the lever connected to said operating means may be transmitted to the other lever to cause the latter simultaneously to move from its locking position to its release position.

2. A locking device according to claim 1, characterized in that, at their adjacent ends, the inner arms of the two levers are provided with overlapping end portions having contact surfaces facing each other and serving to transmit swivelling movement from one lever to the other lever.

3. A locking device according to claim 2, characterized in that, when the two levers are in their locking positions, said contact surfaces are located in slightly spaced apart positions to define a small free clearance therebetween.

4. A locking device according to any of the preceding claims, characterized in that the two levers are swingably supported between two opposite parallel wails of a supporting means, connected to said other member of the chair, to be able to swing around axes extending perpendicularly to said walls which define guide surfaces for opposite longitudinal portions of the two levers.

5. A locking device according to claim 4, characterized in that, at the transition between its two arms, each lever has a generally V-shaped portion by which the lever is swingably mounted in the supporting means by having the tip of said portion received between transversally extending outer and inner bearing means of the supporting means.

6. A locking device according to claim 5, characterized in that said supporting means is formed by a tubular member of rectangular crosssection, the broader side walls of which form said guide surfaces for the levers, while each shorter side wall forms the outer bearing means for the Vshaped portion of one of the two levers, the inner bearing means for each lever being formed by a pin extending transversally between the broader side walls of the tubular member.

7. A locking device according to any of the preceding claims, characterized in that the two levers are spring-biased towards their locking positions by means of a spring member acting on the inner arms of the two levers.

8. A locking device according to claim 7, characterized in that said spring member is formed by a leaf spring having a middle portion, resting against the inner side of one of the shorter side walls of the tubular supporting means, and two end portions which extend in inward inclined directions towards each other and which act each against one of the two levers.

9. A locking device according to any of the preceding claims, characterized in that the two levers have been made from two straight rods by subjecting said rods to equal forming operations.

10. A locking device for releasably locking two mutually movable members of a vehicle chair or other chair in selectable, stepwise adjustable positions relatively to each other, said device being constructed and arranged substantially as herein particularly described with reference to the accompanying drawings.