WO1999041511A1

WO1999041511A1 - Resilient bracket

Info

Publication number: WO1999041511A1
Application number: PCT/SE1999/000106
Authority: WO
Inventors: Birger Larsson
Original assignee: Birger Larsson
Priority date: 1998-02-17
Filing date: 1999-01-27
Publication date: 1999-08-19
Also published as: SE9800446D0; SE519900C2; AU2647399A; SE9800446L

Abstract

The present invention relates to an automatically resilient bracket (1) for rear-view mirrors, work lighting, etc. The bracket (1) has two parts (9, 13) with sides facing towards one another which display arcuate grooves (11, 14). The grooves (11, 14) receive one or more balls (10) and the width and depth of the grooves (11, 14) are reduced gradually towards the ends of the grooves. The one bracket part (9) is non-rotationally connected to a shaft (4) which passes through the centre of the bracket (1), while the other bracket part (13) does not accompany the shaft (4) in its pivotal movement. A spring (17) is provided for pretensioning the above mentioned bracket parts (9, 13) towards one another. If the arm (2) is dislodged out of its position by an external force, the co-operation between the balls (10) and the configuration of the grooves (11, 14) result in the upper bracket part (9) being lifted upwards. When the exernal force subsequently no longer acts on the arm (2), the bracket (1) is returned to its original position thanks to the spring (17).

Description

RESILIENT BRACKET

The present invention relates to a resilient bracket according to the preamble to appended Claim 1.

In many contexts, it is desirable that anything dislodged out of its position is automatically returned to its original position. This applies, for example, to the external mirrors mounted on different types of vehicles and machinery, but also to work l ghting mounted on such vehicles and machinery.

For example, the outer rear-view mirrors of tractors, lorries and other similar vehicles must project out a distance from the sides of the ve- hide in order to be effective. As a consequence, the rear-view mirrors are exposed to the risk of striking trees, buildings, other vehicles etc. in narrow passages. In order that, in such instance, the mirrors are_ not damaged, they are supported on the vehicle in such a manner that they pivot away on impact, whereafter they must be returned to their original position in order once again to fulfil their intended function. In this case, it is not practical to have to leave the vehicle every time such an event happens. In other contexts, it may be even more impractical. If, for example, the work lighting mounted on a crane gantry or arm is moved out of its position, it may be necessary to climb out on the gantry or arm in order to adjust the lighting if it does not automatically return to its initial position.

There are previously known systems in the art in which the return movement takes place of, for example, a mirror whose position has been dis- lodged only a relatively slight angle. These systems generally are based on co-operation between spring-biased parts where the one part displays some type of a tipped shape which co-operates with a corresponding depression. Such a coupling often functions satisfactorily when it is new, but because of its form the tip is often worn down relatively quickly, with the result that there is a risk that the play in the coupling increases and the mirror no longer has a stable, set position. As a result, the mirror becomes sensitive to vibration. More- over, if the mirror has been moved through a larger angle, this type of apparatus is not capable of returning the mirror to its initial position.

From Swedish patent specification 457 941 it is previously known to provide an electric motor and a worm gear to return a mirror which has been dislodged out of its position. In this instance, the driver adjusts the position of the mirror from inside the vehicle by driving the electric motor in one or the other direction. However, this solution is relatively complicated and expensive.

One object of the present invention is therefore to realise a bracket which, in a reliable manner, automatically returns a mirror, work lighting etc. to its original position.

This object is attained by means of a bracket as described in the charaterizing clause of appended Claim 1.

Another object to the present invention is that the bracket be rela- tively economical to manufacture and that it be capable of being retrofitted into existing equipment.

A further object of the present invention is that it will function regardless of whether the mirror has been moved a short or long distance from its original, correct position.

Further objects and advantages with the present invention will be apparent from the following description of preferred embodiments, with reference to the accompanying Drawings. In the accompanying Drawings:

Fig. 1 is a sectional view through one embodiment of a bracket according to the present invention;

Fig. 2 is a sectional view taken along the line II-II in Fig. 1;

Fig. 3 is a sectional view taken along the line III-III in Fig. 2; Fig. 4 is a sectional view corresponding to Fig. 1 of an alternative embodiment;

Fig. 5 is one example of how the bracket according to the invention is interconnected with a mirror;

Fig. 6 is a top plan view of a bracket for a mirror mounted on a tractor; and

Fig. 7 is an exploded view of the apparatus of Fig. 1.

Within the bracket 1 according to the illustrated embodiment, a shaft 4 is provided. The upper portion of the shaft 4 is passed into a recess in an arm 2, the arm 2 in its turn supporting a mirror 23 or constitut- ing a part of a larger frame which supports the mirror 23. The shaft 4 and the arm 2 are fixed to one another in a suitable manner, for example by means of a locking pin 3 which passes through apertures 16, 5 in the shaft 4 and the arm 2, respectively. A person skilled in the art will readily perceive that this locking feature may be realized in many different ways, and also that the shaft and the arm may constitute a unitary part. But since the exact interconnection does not constitute a germane part of the invention itself, it will not be described in detail here.

The bracket 1 has an upper portion 9 which, in a suitable manner, is fixed to the shaft 4 or the arm 2 such that the upper portion 9 accompanies the shaft 4 in any possible rotational movement. In the illustrated embodiment, the fixing of the upper portion 9 takes place by means of pins (projections) 6 which are accommodated in recesses 7 in the arm 2. The upper portion 9 has a central aperture through which the shaft 4 passes when the bracket is mounted. In certain embodiments (not shown), the upper portion 9 is an integral part of the arm 2.

On its lower surface, the upper portion 9 of the bracket has at least one groove 11 which is intended to co-operate with a ball 10 tensioned in between the upper bracket portion 9 and a lower bracket portion 13. The groove 11 is arcuate and has a depression 12 in order to receive the ball 10. Normally, two grooves 11 are provided on the lower surface and two balls 10 are tensioned in between the two bracket portions 9, 13.

The lower bracket portion 13 displays, on its upper side facing towards the upper bracket portion 9, grooves 14 provided with a depression 15. The grooves 14 on the lower bracket portion 13 have the same form as the grooves in the upper bracket portion 9 and the ball 10 runs in the grooves 11, 14 on both portions 9, 13.

For the desired function, the lower bracket portion 13 is held rotational ly fixed in relation to the shaft 4, i.e. the shaft 4 may rotate without affecting the lower bracket portion 13. This may be made in connection with securing the bracket 1 to a frame or the like. Since this does not constitute any germane part of the present invention, it will not be described in greater detail here.

The lower bracket portion 13 has a central aperture for passage of the shaft 4. The lower bracket portion 13 further has a recess 26 for re- ceiving a spring 17. The recess 26 is open from that side opposite the side which co-operates with the ball 10, and the recess 26 further has a bottom wall 27 against which the spring 17 is tensioned. The shaft 4 passes through a part of the recess 26 and is surrounded by the spring 17. The spring 17 is tensioned between the bottom wall 27 of the recess 26 and a piston 18 which is held in tension against the lower portion of the shaft 4 by means of a pin 8. The pin 8 is threaded in both ends and has a washer-like projection in its middle. The one end of the pin 8 is screwed into the shaft end, the piston 18 being tensioned in between the projection of the pin 8 and the end of the shaft.

The piston 18 absorbs any possible lateral forces which may be exercised on the shaft 4 in that it has but slight play to the inner walls of the recess 26. As a result, the piston 18 will have a stabilizing effect.

In the illustrated embodiment, there is also an arcuate springed washer 19 between the projection pin 8 and a nut 20 threaded on the free end of the pin 8. This spring washer 19 is provided to damp the return movement in that its outer edge abuts against the inner wall of the recess. In the bottom of the recess 26, a sealing arrangement 21 is provided. In view of the environment which the contemplated machinery normally operates in, it is important to make the bracket as tight as possible in order to avoid problems with penetrating dirt, dust, etc. To this end, seals are also provided which seal the space between those parts which pivot mutually. These seals may be designed in many different ways such as downwardly projecting, overlapping portions 28 (sketched in Fig. 7), rubber bushings, 0-rings, etc.

Normally, two balls 10 are disposed in the grooves 11, 14 in the upper and lower bracket portions 9, 13. Each groove 11, 14 has the same configuration, with a depression 12, 15 which gives a relatively stable position for the ball 10. On each side of the depression 12, 15, the groove is extended almost 90° in the circu ferencial direction. Both the groove width and groove depth decline gradually in the direction from the depression 12, 15 to each respective groove end.

A person skilled in the art will perceive that the number of balls and co-operating grooves need not be as shown on the Drawings. Technically, it is possible to employ any number of balls whatever, but this however influences the maximum pivotal movement for the bracket 1 for this to be able to return the arm 2 to its original position. With two balls, the maximum pivotal movement will be close on 90°, with three balls, close on 60°, etc.

Fig. 4 shows an alternative embodiment in which an intermediate portion 22 is disposed between the upper and lower bracket portions 9, 13. The intermediate portion 22 has a central aperture for receiving the shaft 4, and grooves corresponding to the upper bracket portions 9, 13, for co-operation with balls 10 placed between the different parts 9, 13, 22. As a result of the arrangement with the intermediate portion 22, it is possible to increase the angle which the arm 2 may be pivoted and still be returned by the bracket 1 to its original position. If required, a block may be provided at the end of each groove so that the ball 10 is prevented from passing any of the ends of the co-operating grooves.

A person skilled in the art will further perceive that the blocks for preventing the ball 10 from passing the ends of the grooves 11, 14 may be designed in many different manners. In one embodiment, a pin (not shown) is fixed in the regions between the groove ends in one of the bracket portions 9, 13. In other embodiments, there is only one pin provided. In order to receive the pin, a groove is provided in the op- posing bracket portion.

Figs. 5 and 6 show one example of an arrangement in which the bracket 1 according to the present invention is employed in a mirror frame on a tractor. In such instance, the mirror 23 is secured on an arm 2 which, in certain embodiments, is telescopic. The lower portion 13 of the bracket 1 is tensioned in at a bow handle in the illustrated example. A person skilled in the art will perceive that the bracket 1 may be secured in many different ways.

The function of the bracket 1 according to the present invention is as follows. When the arm 2, by the action of an external force, is moved out of its position, the upper bracket portion 9 is rotated. On this rotation, the earlier position between the balls 10 and the cooperating grooves 11, 13 is altered. In such instance, the ball 11 de- parts from at least the one depression 12, 15. Given that the depth and width of the grooves 11, 13 is reduced in a circumferencial direction, the upper bracket portion 9 will here be urged upwards against the action of the spring 17. When the external force no longer acts on the arm 2, the spring 17 - thanks to the balls 10 and the configuration of the co-operating grooves - moves the shaft 4 and the arm 2 back to their original positions. This original position is that where the balls 10 lie in each respective depression 12, 15.

Thanks to the balls 10, depressions 12, 15 and the configuration of the grooves 11, 14, the bracket 1 displays a stable normal position. As a result, an external force of a certain magnitude is therefore required to move the arm 2. Depending upon the spring constant of the spring 17, how powerfully the spring is tensioned, the dimensions of the balls 10 in relation to the depressions and the grooves, and also the friction in the balls and the grooves, the stability of the arm (or in other words its vibration sensitivity) may be adjusted. One method of modify- ing the tensioning of the spring 17 is to place washers or shims between the spring 17 and the bottom wall 27.

In that the gooves are provided on both sides of the depression, the bracket 1 can absorb rotational movement both forwards and backwards of the arm 2. In the embodiment according to Figs. 1-3, the bracket 1 is capable of absorbing a pivotal movement of up to 90° and still move the arm 2 back to its original position. If the balls 10 move over from one pair of grooves to the next, the bracket 1 will assume a new stable position (if possible.) pivoted through 180° in relation to the original position.

In embodiments which have a plurality of levels with co-operating balls 10 and grooves 11, 14, the bracket is capable of absorbing greater pivotal movement than 90° and still return the arm back to its original position. In the embodiment illustrated in Fig. 4, it is appropriate to provide blocks which prevent the mutual pivoting between the upper bracket portion 9 and the intermediate portion 22 and between the intermediate portion 22 and the lower bracket portion 13, respectively, becoming greater than approx. 90°. If, in an ideal case, the mutual pivoting first takes place between the upper bracket portion 9 and the intermediate portion 22, the blocks between these portions will engage when the arm 2 has been pivoted close to 90°. On continued pivoting of the arm 2 in the same direction, the pivoting changes so as to take place between the lower bracket portion 13 and the intermediate portion 22. By such means, the total pivotal movement of the arm 2 may amount to almost 180° and the arm 2 is still returned to its original position. In practice, it is not certain that the pivoting takes place at one interface at a time, for which reason it is possible that a certain rotation takes place at both of the interfaces simultaneously already from the start. By providing a plurality of levels with balls 10 and cooperating grooves 11, 14, as well as a plurality of intermediate por- tions 22, pivoting movements of up to almost 360° may be absorbed and the arm 2 still be returned to its original position.

For the bracket 1 according to the present invention, there are actu- ally a number of counteractive requirements. In order to retain a mirror, work lighting or the like as stable as possible in normal operation, a relatively large retentive force must be exercised on the arm 2. However, this retentive force may not be so great that the mirror, work lighting, etc. risks being broken because the arm is not rotated from its original position.

By employing the curved, arcuate washer 19, a damped return action of the arm will be obtained. This is realized thanks to the configuration of the washer 19. When the arm 2 is pivoted away, the shaft 4 is, as was disclosed above, moved upwards in relation to the lower bracket portion 13. When the arm 2 is subsequently moved back, the washer 19, because its edges abut against the inner wall of the recess 26, will generate a counteracting force which results in the return movement being damped somewhat. This damping action may be adjusted by altering the position of the nut 20 on the pin 8 whereby the radius of curvature of the washer 19 is altered and thereby the force with which the spring washer 19 abuts against the inner wall of the recess 26.

In one alternative embodiment, grooves 11 are only provided on one of the two opposing surfaces, for which reason the ball 10 will constantly lie in a depression on that side which has no grooves. In the same manner as previously, each groove 11 has a depression 12 for giving a relatively stable position when the arm 2 is in the desired, unaffected position. In this embodiment, the grooves which are provided have the same configuration as previous grooves.

Expressions such as upper and lower and the like have been employed in the body of this description only in relation to the Drawings to which reference is made. A person skilled in the art will readily perceive that the orientation of the bracket in space is of no importance for its desired function.

Claims

1. A resilient bracket (1) which takes up pivotal movements and automatically returns to its original position, c h a r a c t e r - i z e d in that the bracket (1) has at least two mutually pivotal and axially displaceable parts (9,13), where a spring (17) pretensions said parts axially towards one another, that at least one ball (10) is disposed in the interface between the two parts (9,13) and co-operates with a groove (11,14) in at least one of the parts (9,13), that a depression (12,15) is disposed in each groove

(11,14) to receive the ball (10), and that the groove (11,14) is extended almost 90┬░ in both circumferencial directions counting from the depression (12,15).

2. The bracket as claimed in Claim 1, c h a r a c t e r i z e d in that each groove (11,14) is arcuate, and that an arm (2) or the like is fixedly connected to one of the rotary parts (9)^

3. The bracket as claimed in Claim 2, c h a r a c t e r i z e d in that two grooves (11,14) are disposed on the surfaces of the parts

(9,13) facing towards one another, and that two balls (10) are disposed between the parts (9,13).

4. The bracket as claimed in Claim 2 or 3, c h a r a c t e r i z e d in that the width and depth of each respective groove (11,14) is reduced gradually in the direction from the depression (12,15) to the ends of the grooves.

5. The bracket as claimed in any of Claims 2 to 4, c h a ra c - t e r i z e d in that, in the normal, unaffected position of the bracket (1) each respective ball (10) lies in the depressions (12,15) of the grooves (11,14).

6. The bracket as claimed in any of the preceding Claims, c h a - ra cte r i z e d in that an intermediate portion (22) is provided between the two mutually rotary parts (9,13), said intermediate portion (22) displaying grooves in the surfaces facing towards 10

each respective part (9,13).

7. The bracket as claimed in any of the preceding Claims, c h a ra c t e r i z e d in that the spring (17) is tensioned in be- tween the bottom wall (27) of a recess (26) in the one part (13) and a piston (18), and that washers are placed between the bottom wall (26) and the spring (17) for adjusting the pretensioning of the spring (17), and that a shaft (4) is disposed centrally in the bracket (1) .

8. The bracket as claimed in Claim 7, c h a r a c t e r i z e d in that the shaft (4) is rotational ly fixedly connected to the one part (9), that the shaft (4) is surrounded by the spring (17), that the piston (18) is held by a screw union (8,20) at the one end of the shaft (4), and that the piston (18) displays slight play to the inner wall of the recess (26).

9. The bracket as claimed in any of Claim 7 or 8, c h a ra ct e r- ^~ i z e d in that an arcuate washer (19) is disposed tensioned at the shaft (4), that the edges of the washer (19) abut against the inner wall of the recess (26) for damping the axial return movement of the bracket (1), and that the radius of curvature of the washer (19) is variable.

10. The bracket as claimed in any of the preceding Claims, c h a r a c t e r i z e d in that the grooves (11,14) are provided with blocks to prevent the balls (10) from leaving the grooves (11,14).