GB2122551A

GB2122551A - Vehicle bumper assembly

Info

Publication number: GB2122551A
Application number: GB08303747A
Authority: GB
Inventors: Frederick John Charles Hope; James Malcolm Pigney
Original assignee: HOPE TECH DEV Ltd; HOPE TECHNICAL DEVELOPMENTS Ltd
Current assignee: HOPE TECH DEV Ltd; HOPE TECHNICAL DEVELOPMENTS Ltd
Priority date: 1982-06-28
Filing date: 1983-02-10
Publication date: 1984-01-18
Also published as: GB2122551B; GB8303747D0

Abstract

A beam 1 is supported by two arms 2 from the rear, front or sides of the vehicle so that, on impact, the beam is displaceable from its rest position (shown) in a direction X. A spring 7 is associated with each of the arms 2 for biasing the beam 1 towards the rest position where it is held by holding means 15 which prevent the beam from being displaced in the opposite direction Y unless the beam is subjected to a predetermined force. In an example, the bumper is positioned beneath the rear of a lorry, coach, bus or van; displacement in direction X occurs if another vehicle strikes the beam 1 (or the beam strikes an object during reversing) and displacement in direction Y occurs if the beam 1 strikes an obstruction such as the ground at the junction of two inclined surfaces such as when leaving a ferry. <IMAGE>

Description

SPECIFICATION Bumper assembly This invention relates to a bumper assembly for a road vehicle such as a rigid or articulated lorry, a passenger coach, a bus or a van.

Because of accidents involving vehicles with high ground clearance, it has been recommended practice to fit a rigid bumper bar to such vehicles so as to prevent smaller vehicles such as passenger cars from being forced underneath the large vehicles in an accident.

Legislation will shortly be enacted to require vehicles of a certain minimum weight to be fitted with such rigid bumper bars at a specified height beneath the rear of the vehicle.

Unfortunately, such rigid bumper assemblies often cause damage when the driver is manoeuvring the vehicle in restricted spaces.

There is, therefore, a need for a bumper assembly which both meets the coming legal requirements and at the same time, does not increase the risk of accidental damage during operation of the vehicle.

A proposed road vehicle bumper assembly comprises a beam which is supported by a pair of arms from the vehicle in such a manner that the beam is displaceable from a rest position in a direction towards or beneath the vehicle in the event of contact with an obstacle. Springs are provided for biasing the beam towards its rest position. The bumper assembly includes sensors for detecting displacement of the beam and activating a warning device.

One disadvantage of this proposed bumper assembly is its susceptibility to damage when the vehicle moves over surfaces of changing incline. In particular, when a vehicle leaves a ferry it travels down an inclined ramp and then up and inclined road surface. At the junction of the two inclined surfaces, the bumper assembly tends to hit the ground, and this can damage the bumper assembly.

The aim of the invention is to provide a bumper assembly for a road vehicle which can prevent under-running of smaller vehicles, and which has a reduced chance of accidental damage during operation of the vehicle.

The present invention provides a road vehicle having a bumper assembly fitted thereto, the bumper assembly comprising a beam which is pivotally supported by an arm from the vehicle so that the beam is displaceable from a rest position in a first direction towards or beneath the vehicle in the event of contact with an obstacle, spring means for biasing the beam towards its rest position, and means for holding the beam in its rest position, the holding means being such as to prevent the beam being displaced in a direction opposed to said first direction, unless the beam is subjected to a predetermined force.

Preferably, the bumper assembly further comprises sensing means for detecting displacement of the beam and activating a warning device.

Thus, when the vehicle is being manoeuvred in restricted conditions, the bumper assembly is likely to be the first part of the vehicle which touches an obstacle; and, after being displaced a short distance (which will not damage the obstacle or the vehicle), a audible or visual warning will be activated so that the driver will be immediately aware that his vehicle is in contact with an obstacle.

In general, the beam will be displaceable through a predetermined distance. Thus, in the event of collision with another vehicle, there will be a deceleration effect during which the spring means of the bumper assembly will absorb some of the energy of impact.

Thereafter, the beam will meet a stop position on the vehicle, which will prevent a smaller vehicle from penetrating beneath the larger vehicle.

In a preferred embodiment, the sensing means is a magnetic Reed switch which comprises a permanent magnet, a sensing device responsive to the magnetic field of the permanent magnet, and a shield which is positionable between the magnet and the sensing device to prevent the sensing device being influenced by the magnetic field of the magnet, wherein the magnet and the sensing device are fixed to a stationary part of the assembly, and the shield is fixed to a movable part of the assembly. Advantageously, the shield is arranged to pivot with the arm as the beam is displaced from its rest position.

The arm may be pivotally supported from the vehicle by a mounting channel fixed to the vehicle and a pivot pin which is fixed to the mounting channel, the arm being pivotally mounted on the pivot pin. In this case, the shield may be fixed to the arm for rotation therewith. Preferably, the shield is a sectorshaped member made of magnetic material.

Advantageously, a hollow rubber spring constitutes the spring means. The hollow rubber spring may be fixed to an internal flange of the arm, in which case the mounting channel may provide an abutment for the hollow rubber spring.

In a preferred embodiment, the holding means is constituted by a latch assembly, the latch assembly being such as to prevent the beam being displaced in a direction opposed to said direction, unless the beam is subjected to a predetermined force. Thus, if the bumper assembly catches on an obstruction, the whole assembly can pivot away from the vehicle upon the latch assembly being released.

Advantageously, the hollow rubber spring is mounted on a rod and positioned between a pair of retaining plates. Preferably, one of the retaining plates is fixed to the arm, the other retaining plate being pivotally connected to the arm by means of a pivot bolt which also constitutes the pivotal connection between the arm and the vehicle. Conveniently, the latch assembly is constituted by a spring-biased plunger mounted on the vehicle and by the other retaining plate.

In another preferred embodiment, the holding means is constituted by a second spring means, the second spring means being positioned so as to bias the beam towards its rest position in the opposite direction from that in which the first spring means biases the beam towards its rest position.

Advantageously, the second spring means is pre-loaded so that, when the beam is in its rest position, the first-mentioned spring means is subjected to a compressive load. The second spring means may be a hollow rubber spring which is positioned within the arm between a flange fixed within the arm and a retaining plate.

Preferably, a transmission element is detachably fixed to the pivot pin for rotation therewith, and the retaining plate is provided with a link which is pivoted to the transmission element.

Advantageously, the warning device is a bleeper unit. Preferably, the sector-shaped shield is such that the bleeper unit is activated when the beam is displaced from its rest position in said first direction through a first predetermined angle, and whenever the beam is displaced from its rest position in a second direction opposed to said first direction through a second predetermined angle. In a preferred embodiment, the sector-shaped shield is such that said first predetermined angle is substantially 2" and said second predetermined angle is substantially 74 .

Two forms of bumper assembly, each of which is constructed in accordance with the invention, will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a part-sectional elevation of a first form of bumper assembly, and shows part of the rear of a road vehicle to which the bumper assembly is attached; Figure 2 is a view, partly in section, in the direction of the arrow II in Fig. 1; and Figure 3 is a part-sectional elevation of a second form of bumper assembly, and shows part of the rear of a road vehicle to which the bumper assembly is attached.

Referring to the drawings, Fig. 1 shows a bumper assembly comprising a longitudinal beam 1 which is supported by two arms 2 (only one of which can be seen in Fig. 1) on the chassis 3 of the vehicle. Each arm 2 is pivotally supported by a respective mounting channel 4 fixed to the chassis 3. The beam 1 is arranged to extend substantially across the entire width of the vehicle. As can be seen best in Fig. 2, each of the arms 2 is pivotally mounted on a respective pivot pin 5 by means of a pair of tubular collars 6. The collars 6 of each arm 2 are welded to that arm so as to constitute aligned bearing sleeves. Each pivot pin 5 is supported in its mounting channel 4.

In use, each of the arms 2 is displaceable from the position shown in Fig. 1 in a clockwise direction. Radial movement of each of the arms 2 is restricted by a respective hollow rubber spring 7 such as one manufactured by Aeon Limited. One end of each spring 7 is fixed to an internal flange 2a of the respective arm 2 by means of a nut 8 and a bolt 9. The other end of each spring 7 bears against the inside underneath surface 4a of the respective mounting channel 4.

A respective transmission element 10 is fixed to the pivot pin 5 of each arm 2 for rotation therewith, a respective grub screw 11 being provided for this purpose. One end of a respective link 1 2 is pivotally attached, at 13, to each of the transmission elements 10. The other end of each link 1 2 is welded to a respective compression plate 14. A respective, preloaded, hollow rubber spring 1 5 (such as one manufactured by Aeon Limited) is positioned beneath each compression plate 14 and a respective internal flange 2b provided within the associated arm 2. As shown in Fig.

1, the internal flanges 2a and 2b of each arm 2 form part of a single component which is welded within that arm. A respective guide rod 16 is fixed to each of the compression plates 14, each of these rods passing through the corresponding spring 1 5 and through a respective aperture 2c in the corresponding flange 2b.

A respective magnetic Reed switch 1 7 is associated with the transmission element 10 of each arm 2. Each magnetic reed switch 1 7 has a permanent magnet 1 7a, and a component 1 7b which can be influenced by the magnetic field of the magnet to open and close an electrical circuit 18 (only part of which can be seen in the drawings). Each of the switches 1 7 is also provided with a sectorshaped shield 1 9 which is fixed to one of the collars 6 of the respective arm 2 for rotation therewith.Each shield 1 9 is positioned so that its plane of rotation lies between the magnet 1 7a and the component 1 7b of the associated switch 1 7. Each of the shields 1 9 is made of magnetic material so that, when positioned between the magnet 1 7a and the component 1 7 b of its switch 17, magnetic flux is prevented from reaching the component 1 7 b so that the associated electrical circuit 1 8 remains open. On the other hand, when each of the shields 1 9 is not positioned between the magnet 1 7a and the component 1 7b of the associated switch 17, magnetic flux from the magnet can reach said component and open the associated electrical circuit 1 8. Each of the switches 1 7 is connected to a bleeper unit 20 by its electrical circuit 18, the bleeper unit constituting an audible warning device for indicating whenever one of the shields 1 9 is not positioned between the magnet 1 7a and the component 1 7b of its switch 1 7.

The pre-loaded springs 1 5 are effective to hold the bumper assembly in is normal working (rest) position, this position being shown in Fig. 1. Each of the springs 1 5 is pre-loaded in the following manner. Firstly, each. spring 1 5 is positioned within its arm 2 in the unloaded condition. The associated mounting channel 4 is then located over each of the arms 2, and the associated pivot pin is slid into position through the respective tubular collars 6. The link 12 of each spring 1 5 is then attached to the associated transmission element 10 (which has already been loosely fitted around its pivot pin 5). The grub screws 11 are then screwed into position to lock the transmission elements 10.to their pivot pins 5.The springs 1 5 are then pre-loaded by turning the pivot pins 5 through approximately 75o, after which the pivot pins are bolted tightly to their mounting channels 4.

The degree of pre-loading of the springs 1 5 is sufficient to compress the main springs 7 by a slight amount.

In use, if another vehicle strikes the beam 1 (or if the beam strikes an object during reversing), that is to say when the beam is subjected to a force in the direction of the arrow X shown in Fig. 1, the bumper assembly will pivot in a clockwise direction (as seen in Fig.

1) about the pivot pins 5. As the arms 2 pivot, the hollow rubber springs 7 are compressed between their flanges 2a and surfaces 4a, the compression of these springs resisting the pivotal movement of the arms. The springs 7 are, therefore, effective to absorb the energy of slow-speed heavy impacts. This pivotal movement of the arms 2 continues until the upper end portions 2d of the arms 2 abut against the surfaces 4a of the mounting channels 4.

if the beam 1 strikes an obstruction so that a force is applied thereto in the direction of the arrow Y (see Fig. 1), the whole assembly will try to pivot in an anti-clockwise direction about the pivot pins 5. If the force applied in the direction of the arrow Y is greater than the combined force resulting from the weight of the beam 1 and the biasing force of the springs 15, the beam will pivot in an anticlockwise direction about the pivot pins 5. As the beam 1 is pivoted in this manner, each of the pre-loaded springs 1 5 resists this movement until its link 1 2 moves over centre, that is to say until the longitudinal axis of that link moves across the line joining the centre of the associated pivot pin 5 and pivotal axis 1 3.

The beam 1 can pivot in this manner until the upper surfaces of the arms 2 are substantially horizontal. In this position, the links 1 2 lie at an angle of about 16 to the horizontal. From this position, the bumper assembly can return to its normal working position owing to the weight of the beam 1. This return movement is assisted by the pre-loading of the springs 1 5 once the links 1 2 have again passed over centre.

Each of the sector-shaped shields 1 9 is such that the associated switch 1 7 closes the respective electrical circuit 1 8 whenever the beam 1 has rotated from its rest position in a clockwise direction through an angle of 2", and whenever the beam has rotated in an anti-clockwise direction to such an extent that the arms 2 are horizontal. In practice, the beam 1 should return naturally to its normal working (rest) position under the action of gravity and the fqrce of the springs 15, so that the bleeper unit 20 will only be activated momentarily. If, however, the beam 1 remains in the horizontal position, the bleeper unit 20 will continue to be activated, thereby warning the driver of the situation.

The pre-loading of the springs 1 5 is effective not only to hold the assembly in its rest position, but also substantially reduces rebound of the assembly following return movement from the position in which the beam 1 is horizontal. Thus, as the beam 1 returns from the horizontal position, it comes down fairly heavily owing to the combined action of gravity and the springs 1 5. The pre-loading of the springs 1 5 substantially prevents rebound of the assembly which would otherwise occur following the compression- of the main springs 7 caused by the return movement of the assembly. Moreover, because the main springs 7 are not subjected to pre-loading, the assembly is extremely sensitive to forces tending to move the beam 1 in the direction of the arrow X.

Instead of the Reed switches 17, solid state switches such as "Hall Effect" switches may be used. A "Hall Effect" switch is a semiconductor proximity switch which utilises the "Hall Effect" to give a variable output proportional to the strength of a magnetic field to which the switch is subjected.

Also, instead of the bleeper unit 20, the warning device may be a horn. In this case, the horn is connected to an air reservoir by a line containing a pneumatic valve which is controlled by the switches 1 7 or their equivalent. In this case, it is preferable to include a further valve in the line leading from the air reservoir, so that the pressure in the air reservoir cannot drop below a predetermined minimum pressure of say 80 p.s.i.

Fig. 3 shows a rear bumper assembly which comprises a longitudinal beam 21 which-is supported by two arms 22 (only one of which can be seen in the drawing) from a mounting channel 23 fixed to the chassis 24 of the vehicle. The beam 21 is arranged to extend substantially across the entire width of the vehicle. Each of the arms 22 is pivotally connected to the mounting channel 23 by means of a respective pivot bolt 23. Each of the arms 22 is provided with a forwardlyextending flange 26 which carries a lower retaining plate 27. An upper retaining plate 28 is associated with each of the lower retaining plates 27, each pair of retaining plates sandwiching a hollow rubber spring 29, such as one manufactured by Aeon Limited.Each of the upper retaining plates 28 is provided with a pair of upwardly-extending flanges 28a by means of which the retaining plate is pivotally attached to the associated arm 22 by means of the corresponding pivot bolt 25.

Each of the upper retaining plates 28 is also provided with a pair of upwardly-extending flanges 28b. The flanges 28b constitute a stop defining the normal working position of the bumper assembly. In this position, in which the arms 22 and the beam 21 are shown in full lines in the drawing, the flanges 28b rest against the underneath side of the mounting channel 23.

A rod 30 passes through each of the springs 29, one end of each rod being pivotally attached to the associated pair of flanges 28b by means of a pivot bolt 31. Each of the rods passes through respective apertures in the corresponding upper and lower retaining plates 28 and 27, and the free end thereof projects beneath the lower retaining plate. The free end of each of the rods 29 is screwthreaded, so that the springs 29 can be pretensioned by means of nuts 32.

The front edge of each of the upper retaining plates 28 forms part of a respective latch assembly, the latch assemblies being used to hold the bumper assembly in its normal working position unless a large force is applied to the beam 21 in the direction of the arrow A.

Each of the latch assemblies is completed by means of a respective plunger assembly (only one of which is shown in the drawing). Each plunger assembly has a mounting bracket 33 which houses a plunger 34. Each plunger 34 is biased towards the rear of the vehicle by means of a respective spring 35, and each plunger is provided with a guide-pin 36, which engages within a guide slot 37 formed in the respective mounting bracket 33. The rear portion of each of the plungers 34 is formed with a pair of converging faces 34a and 34b which are engageable by the front edge of the associated upper retaining plate 28.

In use, if another vehicle strikes the beam 21 (that is to say the beam 21 is subjected to a force in the direction of arrow B), the bumper assembly will pivot in a clockwise direction (as seen in the drawing) about the pivot bolts 25. As the arms 22 pivot, the hollow rubber springs 29 are compressed between their retaining plates 27 and 28, the compression of the springs resisting the pivotal movement of the arms. This pivotal movement of the arms 22 continues until the lower retaining plates 27 abut against the lower surface of the mounting channel 23.

If the beam 21 strikes an obstruction so that a force is applied thereto in the direction of the arrow A, the whole assembly will try to pivot in an anti-clockwise direction about the pivot bolts 25. If the force applied in the direction of the arrow A is sufficiently large, the upper retaining plates 28 will exert a sufficiently large force on the inclined face 34a of the associated plunger 34 to force that plunger towards the front of the vehicle against the biasing force of its spring 35. This will free the upper retaining plates 28, so that the whole assembly can pivot in an anticlockwise direction. This position is shown in dash-dot lines in the drawing. In order to reset the bumper assembly, it is necessary only to press-the beam 21 in the direction of the arrow B. This causes the upper retaining plates 28 to engage the inclined faces 34b of the plungers 34, thus forcing the plungers towards the front of the vehicle, and permitting the upper retaining plates to return to their original positions.

Obviously, the bumper assembly described above with reference to Fig. 3 could be provided with a sensor for detecting displacement of the beam and activating a warning device, and such a sensor and warning device arrangement could be any of the types described above with reference to the embodiment of Figs. 1 and 2.

Although each of the bumper assemblies described above is positioned at the rear of the vehicle concerned, it will be apparent that it could equally well be positioned at the front or the sides of the vehicle.

Claims

1. A road vehicle having a bumper assembly fitted thereto the bumper assembly comprising a beam which is pivotally supported by an arm from the vehicle so that the beam is displaceable from a rest position in a first direction towards or beneath the vehicle in the event of contact with an obstacle, spring means for biasing the beam towards its rest position, and means for holding the beam in its rest position, the holding means being such as to prevent the beam being displaced in a direction opposed to said first direction, unless the beam is subjected to a predetermined force.

2. A road vehicle as claimed in claim 1, wherein the bumper assembly comprises sensing means for detecting displacement of the beam and activating a warning device.

3. A road vehicle as claimed in claim 2, wherein the sensing means is a magnetic Reed switch.

4. A road vehicle as claimed in claim 3, wherein the Reed switch comprises a perma nent magnet, a sensing device responsive to the magnetic field of the permanent magnet, and a shield which is positionable between the magnet and the sensing device to prevent the sensing device being influenced by the magnetic field of the magnet, wherein the magnet and the sensing device are fixed to a stationary part of the assembly, and the shield is fixed to a movable part of the assembly.

5. A road vehicle as claimed in claim 4, wherein the shield is arranged to pivot with the arm as the beam is displaced from its rest position.

6. A road vehicle as claimed in any one of claims 1 to 5, wherein the arm is pivotally supported from the vehicle by a mounting channel fixed to the vehicle and a pivot pin which is fixed to the mounting channel, the arm being pivotally mounted on the pivot pin.

7. A road vehicle as claimed in claim 6 when appendant to claim 5, wherein the shield is fixed to the arm for rotation therewith.

8. A road vehicle as claimed in claim 7, wherein the shield is a sector-shaped. member made of magnetic material.

9. A road vehicle as claimed in any one of claims 1 to 8, wherein a hollow rubber spring constitutes the spring means.

10. A road vehicle as claimed in claim 9, wherein the hollow rubber spring is fixed to an internal flange of the arm.

11. A road vehicle as claimed in claim 10 when appendant to claim 6, wherein the mounting channel provides an abutment for the hollow rubber spring.

1 2. A road vehicle as claimed in any one of claims 1 to 9, wherein the holding means is constituted by a latch assembly, the latch assembly being such as to prevent the beam being displaced in a direction opposed to said direction, unless the beam is subjected to a predetermined force.

13. A road vehicle as claimed in claim 12 when appendant to claim 9, wherein the hollow rubber spring is mounted on a rod and positioned between a pair of retaining plates.

1 4. A road vehicle as claimed in claim 13, wherein one of the retaining plates is fixed to the arm, the other retaining plate being pivotally connected to the arm by means of a pivot bolt which also constitutes the pivotal connection between the arm and the vehicle.

1 5. A road vehicle as claimed in claim 14, wherein the latch assembly is constituted by a spring-biased plunger mounted on the vehicle and by said other retaining plate.

16. A road vehicle as claimed in any one of claims 1 to 11, wherein the holding means is constituted by a second spring means, the second spring means being positioned so as to bias the beam towards its rest position in the opposite direction from that in which the first spring means biases the beam towards its rest position.

1 7. A road vehicle as claimed in claim 16, wherein the second spring means is preloaded so that, when the beam is in its rest position, the first-mentioned spring means is subjected to a compressive load.

18. A road vehicle as claimed in claim 16 or claim 17, wherein the second spring means is a hollow rubber spring.

19. A road vehicle as claimed in claim 18, wherein the hollow rubber spring constituting the second spring means is positioned within the arm between a flange fixed within the arm and a retaining plate.

20. A road vehicle as claimed in claim 1 9 when appendant to claim 6, wherein a transmission element is detachably fixed to the pivot pin for rotation therewith, and the retaining plate is provided with a link which is pivoted to the transmission element.

21. A road vehicle as claimed in claim 2 or in any one of claims 3 to 20 when appendant to claim 2, wherein the warning device is a bleeper unit.

22. A road vehicle as claimed in claim 21 when appendant to claim 8, wherein the sector-shaped shield is such that the bleeper unit is activated whenever the beam is displaed from its rest position in said first direction through a first predetermined angle, and whenever the beam is displaced from its rest position in a second direction opposed to said first direction through a second predetermined angle.

23. A road vehicle as claimed in claim 22, wherein the sector-shaped shield is such that said first predetermined angle is substantially 2" and said second predetermined angle is substantially 74 .

24. A road vehicle as claimed in any one of claims 1 to 23, wherein the beam is supported by a pair of arms, a respective firstmentioned spring means being associated with each of the arms.

25. A road vehicle as claimed in claim 24 when appendant to claim 2, wherein a respective sensing means is associated with each of the arms.

26. A road vehicle as claimed in either of claims 24 and 25 when appendant to claim 16, wherein a respective second spring means is associated with each of the arms.

27. A road vehicle bumper assembly substantially as hereinbefore described with reference to, and as illustrated by, Figs. 1 and 2 of the accompanying drawings.