GB2319750A

GB2319750A - Impact absorbing nudge bar

Info

Publication number: GB2319750A
Application number: GB9623458A
Authority: GB
Inventors: William Fortune
Original assignee: BREED MANUFACTURING Ltd
Current assignee: BREED MANUFACTURING Ltd
Priority date: 1996-11-09
Filing date: 1996-11-09
Publication date: 1998-06-03
Anticipated expiration: 2016-11-09
Also published as: GB2319750B; GB9623458D0

Abstract

A resiliently mounted bull or nudge bar comprises a frame 1 and one or more resilient mounting means 4 allowing angular deflection of the frame. The mounting means may comprise two pivotally connected housings 10, 11 linked by a block 13 or plastic or rubber material. The bars of the frame may be formed of moulded semi rigid self skinning foamed polyurethane incorporating strengthening insert strips formed of metal or plastics or a combination of the two. The insert strips may be graduated in strength, the weakest being in the furthest forward bars.

Description

Shock-absorbing nudge bar Field of Invention This invention relates to shock-absorbing nudge bars, particularly for use on the front of vehicles.

Background to the invention Nudae bars for Drotectina the front of vehicles are often Drovided on crnqs-

country vehicles such as "Land Rovers% and "Range Rovers These are typically provided to protect both the vehicle and passengers during accidents involving collision with animals or other obstacles in the road.

Traditionally, nudge bars have been made from steel bars or other strong materials which although they have been effective for protecting the vehicle body are often hazardous to pedestrians and others who may be involved in a collision with the vehicle.

A continuing problem is that nudge bars need to have improved ability to absorb impact forces during a collision. The nudge bar should also prevent the object colliding with the vehicle from impacting with the car body. This can cause severe damage not only to the person or animal colliding with the vehicle body but also to the vehicle itself.

The applicant is aware of types of nudge bars, e.g. as described in GB 2187142, and GB 1569052, all of which are fixed to the front of a vehicle and which do not have sufficient ability to absorb impact forces during a collision and as a consequence can be hazardous to pedestrians and others. Attempts have been made to absorb some of the impact forces by using nudge bars formed as mouldings of resilient plastics or rubber material with metal inserts as described in the Applicant's earlier patent GB 2236081. However, even with this type of nudge bar it is desired to improve performance and safety.

It is accordingly an object of the present invention to provide a nudge particularly suitable for use with vehicles which overcomes or at least mitigates one or more of the problems noted above.

Summary of invention According to a first aspect of the present invention, there is provided a shock absorbing vehicle nudge bar comprising a frame assembly adapted to be mounted to a vehicle body by way of one or more resilient mounting means interposed between the frame assembly and the vehicle body such that in use when the nudge bar is subject to an impact the frame assembly is adapted to absorb some or all of the impact by undergoing angular deflection relative to the vehicle body whilst being adapted to revert to substantially its original position after the impact. In this way it is possible for the nudge bar to absorb substantial impact forces during a collision to protect both the vehicle and the pedestrian or other object which collides with the vehicle.

In a preferred embodiment, the resilient mounting means comprises a first housing adapted to be mounted onto the frame assembly; a second housing adapted to be attached to the vehicle either directly or indirectly and a resiliently deformable means linking the first and second housing. Preferably, the resiliently deformable means is a block of plastics material or rubber. This has the advantage that the block of material can be compressed in any direction to take up the impact forces during the collision.

Advantageously, the first and second housings are pivotally connected. This gives the advantage that a robust and long lasting shock absorber is formed so that the nudge bar can pivot against the shock absorbing material and regain its rest position after the collision.

In a preferred embodiment, the first and second housings are pivotally connected by means of a pivot bolt which passes through the first and second housings and the resiliently deformable means whilst still allowing the top and bottom housings to move relative to one another. This has the advantage that it is simple to manufacture the nudge bar and an effective and strong pivoting action is produced.

Preferably, the lower surface of the first housing co-operates with the inner lower surface of the second housing such that in use the housings may move relative to one another.

In a further embodiment, said frame assembly comprises at least one bar formed as a moulding of resilient plastics or rubber material said bars incorporating an insert strip adapted to strengthen the moulding, the insert strip is graduated in strength being weakest in the bar furthest from said resilient mounting means. In this way a graduated absorption of the impact forces can be achieved by graduating the strength of the insert strips inside the nudge bar frame.

Preferably, as described in the Applicant's previous patent GB 2236081, the mouldings are of a semi-rigid, self skinning, foamed polyurethane. This enables different curved and other shapes of nudge bar to be formed and gives the nudge bar a pleasing appearance. Also the moulding has a shock absorbing function acting to take up some of the impact forces during a collision.

Advantageously, the insert strips are formed either from metal or plastics material or a combination of metal and plastics material. In this way a gradation in the strength of the insert strips can be achieved.

According to a second aspect of the invention there is provided a vehicle nudge bar comprising a frame assembly adapted to be attached to a vehicle body, said frame assembly comprising at least one bar formed as a moulding of resilient plastics or rubber material, said bars incorporating an insert strip adapted to strengthen the moulding, the insert strip is graduated in strength being weakest in the bar furthest from said resilient mounting means.

Description of the drawings The invention will be further described, by way of example, with reference to the accompanying drawings in which: Figure 1 is an exploded view of a nudge bar with the shock absorbers arranged horizontally.

Figure 2 is an exploded view of a nudge bar with the shock absorbers arranged vertically.

Figure 3 is an exploded view of a shock absorber.

Figure 4 is a cross section through the shock absorber.

Figure 5 is a cross section through the shock absorber showing two positions of the top housing.

Figure 6 is a perspective view of the shock absorber.

Description of preferred embodiments Embodiments of the present invention are described below by way of example only. These examples represent the best ways of putting the invention into practice that are currently known to the Applicant although they are not the only ways in which this could be achieved.

As shown in Figure 1 the nudge bar provides a frame assembly 1 and two shock absorbing units 4. The nudge bar is mounted onto the front of a vehicle via the shock absorbing units. These units contain a hinged or pivoted joint. When an object impacts the frame assembly this is forced backwards toward the vehicle body and pivots about the shock absorbing units. The shock absorbing units contain resilient material and as a result both of the pivotal movement against this resilient material and the shock absorbing abilities of the frame assembly itself a gradual collapse of the nudge bar is obtained. In this way substantial impact forces can be absorbed and the likelihood of the nudge bar breaking and allowing the colliding object to come into contact with the vehicle body is reduced.

Once the collision is over and the impact forces are removed the frame assembly tends to be pushed back up into its rest position as the blocks of resilient material in the shock absorbing units expand back to their original form. Provided no damage to the nudge bar itself has been sustained during the collision the nudge bar will return to its normal position.

In this example, the frame assembly 1 is formed from two vertical bars 2 that are spaced apart and a horizontal bar 3 connected to the tops of the two bars.

As shown in Figures 1 and 2 the bar 3 is connected to the front of the bars so that it forms the forward most part of the nudge bar. Side parts 5 that are C shaped may also be fixed to the sides of the bars 2 as shown in Figures 1 and 2. These C shaped parts 5 extend around the sides of the vehicle.

It is not essential that the frame assembly is formed in the shape shown.

Other possible forms could be used, for example, the forward-most part of the nudge bar could be provided by vertical struts and other strengthening bars could be added.

Ideally the frame parts are moulded from a resilient plastics or rubber material, preferably a semi-rigid, self skinning, foamed polyurethane. A metal or thermo-plastics insert strip extends through each moulding to strengthen it and to facilitate joining and fixing. Alternatively, the frame can be made from metal or other plastics material or a combination of both types of material. Ideally the whole nudge bar frame is assembled and then put in a mould and coated with foamed polyurethane. This gives the advantage that a great variety of shapes can be created with curved surfaces and which have a good appearance and provide a protective surface for the front of the vehicle. Also, the foamed polyurethane coating provides resilient material to aid in the shock absorbing function of the nudge bar.

It is also possible to create weakened areas or regions in the metallplastics material struts within the frame. On impact of an object with the nudge bar, these weakened regions tend to be deformed and collapse first and in so doing absorb a substantial amount of the impact force. By careful positioning of the weakened regions within the frame it can be ensured that during a collision, the colliding object is protected from the body of the vehicle for as long as possible.

The nudge bar is fixed to the vehicle via the shock absorbing units 4 which may either be positioned horizontally as shown in Figure 1 or vertically as shown in Figure 2. This has the advantage that greater flexibility in modes of attaching the nudge bar to the vehicle is achieved. The shock absorbing units are connected directly to the vehicle using brackets or other conventional fixings. The units are typically connected at a low level on the front of the vehicle for example, at the level that a bumper would be placed. It is also possible to fix the nudge bar to a vehicle that already has a bumper by fixing the shock absorbing units onto the bumper or onto the vehicle body above or below the bumper.

Each shock absorbing unit is formed from a first or top housing 10 and a second or bottom housing 11 as shown in Figures 3 and 6. The nudge bar is mounted onto the top housing with part 12 in the Figures representing part of the nudge bar frame. The bottom housing is fixed to the vehicle and also holds the top housing nested within it as shown in Figure 6. These housings 10 and 11 are preferably made from plastics material or metal.

A block of shock absorbing material 13 is placed'inside the top and bottom housing as indicated in the Figures. This block of resilient material is preferably made from plastics material or rubber and has the advantage that it is able to compress and absorb forces that are applied to it from any direction.

The top and bottom housings and the block of resilient material contain holes that line up as shown when the unit is assembled. A bolt pivot 15 can then be threaded through the housings and block as indicated so that these parts are held together as shown in Figure 6. Using spacer washers 16 on the bolt pivot 15 as indicated in Figure 3 free movement is still allowed between the top and bottom housings. In this example, one pair of spacer washers 16 is placed between the outside of the top housing and the inside of the bottom housing and another pair between the outside of the bottom housing and the bolt head or nut 17.

As shown in Figure 3 the base of the top housing is shaped so that it can move or rock within the fixed bottom housing and about the pivot bolt. The lower surface of the top or first housing has curved corners 18 at the front and back of the housing and also the back of the housing is shallower than the front. The profile of the lower surface of this housing 10 is shown in Figure 4. The lower surface of the first or top housing co-operates with the inner bottom surface of the second or bottom housing. As long as these two surfaces, the lower surface of the first housing and the inner bottom surface of the second housing have a slightly different size or shape then the two housings can move relative to one another. In this example, the first housing can move with respect to the second housing to a certain extent as shown in the Figures. The extent of movement of the first housing is restricted by the shape and form of the two housings and the way they co-operate together although this could be achieved in other ways.

The block of resilient shock absorbing material 13 is shaped to fit between the two housings. In this example the block is rectangular so that it does not move substantially within the bottom housing but rather is compressed as the two housings move against each other.

When a load is applied to the nudge bar, for example as shown at 20 in Figure 5, the top housing 10 rocks backwards, pivoting about the bolt 15 and compressing the shock absorbing material 14. In this way the energy from the load applied to the nudge bar is absorbed as the material 14 is compressed. Loads applied to the nudge bar, during a collision or other impact can be absorbed in a gradual manner as the top housing pivots against the resilient material 14. It has been found that in this way a graduated collapsing point can be achieved and the de-acceleration rate of the nudge bar as it moves backwards and collapses is improved leading to enhanced performance of the nudge bar.

Two or more shock absorbing units can be used as shown in Figure 1. The units are positioned between the frame assembly and the vehicle body or chassis and by varying the number of shock absorbing units used as well as the type of shock absorbing material used the performance of the nudge bar can be altered.

Loads applied to any part of the frame assembly of the nudge bar are transferred into pivotal movement and compression of the shock absorbing material.

This has the advantage that impacts on the side parts 5 of the frame are also absorbed.

Once the load is removed from the nudge bar, after the collision, the shock absorbing material expands back to substantially its original size. In so doing the first and second housings are forced back into the rest position, with the nudge bar frame assembly thus being pushed back into its original position provided that the nudge bar itself has not sustained any damage during the impact.

It is not essential that the shock absorbing unit has the form described above. It is also possible for example, to use top and bottom housings that have a different shape - these could take the form of plates with the shock absorbing material sandwiched between them. That is, the term housing includes structures such as plates which do not have a box-type form. For example a metallastic bush type structure could be used. Also, the shock absorbing units could be positioned at other points on the nudge bar frame. Similarly, instead of using a block of shock absorbing material other resilient means could be used for example springs.

When the nudge bar is subject to an impact the frame assembly is adapted to absorb some or all of the impact by undergoing angular deflection relative to the vehicle body. The term angular deflection is meant to include any type of bending, flexing, deforming or rotation of the frame assembly towards the vehicle body. It is not necessary that the nudge bar pivot about a pivot point or bolt other types of angular deflection of the frame assembly are encompassed in the invention.

The nudge bar comprises a frame assembly adapted to be mounted to a vehicle body by way of one or more resilient mounting means interposed between the frame assembly and the vehicle body. The resilient mounting means comprises a first and a second housing and a resiliently deformable means linking the first and second housing. As already described the resiliently deformable means can be for example, a block of foam plastics material or rubber. However, it is also possible to use other resiliently deformable means such as an air bag or fluid bag such as those used in shock absorbers typically found on lorries and other large vehicles.

The term linking is used to describe the relationship between the resiliently deformable means and the first and second housings. This term is intended to include situations where the resiliently deformable means is joined to each of the housings or simply rests between them. The resiliently deformable means does not necessarily have to touch the two housings.

According to a second aspect of the invention, the nudge bar frame assembly is formed from a structure of metal and/or plastics material that is moulded with a resilient plastics or rubber material. Preferably the outer moulding is made from a semi-rigid, self-skinning, foamed polyurethane as described in the Applicant's previous patent GB 2236081. The structure within the moulding acts to strengthen the frame and can be a single unit or may be comprised of two or more insert strips joined together. The structure itself may either be hollow or solid and the strengthening insert strips may take the form of bars that can be hollow.

The structure within the moulding is weaker in the parts of the frame that are furthest from the point where the nudge bar is mounted onto the vehicle. By doing this a graduated absorption of the impact forces can be achieved and the performance of the nudge bar improved.

The structure can be formed from two or more insert strips. The strengthening strips are made from either metal or plastics material or a combination of both. By using strengthening strips that are weaker in the parts of the frame assembly furthest from the mounting and stronger strips in the parts of the frame nearest the mounting it has been found that the performance of the nudge bar is improved. (The term mounting is used to refer to the point where the nudge bar is mounted onto the vehicle).

The parts of the nudge bar furthest from the mounting are weak and absorb a substantial part of the impact force. These parts collapse and break before the stronger parts of the frame nearer the point where the nudge bar is mounted onto the vehicle. These stronger parts of the frame also absorb part of the impact force and are able to continue doing so even after the weaker parts have collapsed. In this way a graduated absorption of the impact force can be achieved with the end result that a greater proportion of the impact force is absorbed overall.

Preferably the insert strips used in the parts of the frame assembly furthest from the mounting are made from plastics material with metal strips being used for the frame parts near the mounting. The metal and plastics material strips may be joined using any conventional means, for example, bonding, pinning and sleeve joints can be used. However, care must be taken if the strips become stronger around the joint region than at other places. If this happens it is possible to weaken the strips as necessary at the desired location. This can be done by narrowing the strips or using other conventional methods.

It is not essential that insert strips of different materials be used in order to achieve a gradation in the strength of the strips and hence the structure within the moulding. Several strips of different thicknesses may be used or alternatively, individual strips which become narrower towards one end. It is also possible to place weakened regions in some strips or at one end of an individual strip. The interval between weakened regions can be varied in order to achieve a graduation in strength.

In one example, a frame assembly as shown in Figure 1 is used. The horizontal bar 3 is formed using plastics material insert strips with polyurethane foam moulding. The two vertical bars 2 have plastic insert strips near the top of these bars and metal insert strips near the bottom. When an object collides with the horizontal bar 3 this takes a substantial amount of the impact force by bending backwards towards the vehicle. The tops of the vertical bars 2 also bend backwards but with the bases of these bars bending less. In this way a graduated absorption of the impact force is achieved. Preferably the metal and plastics material strips are hollow bars that are joined using conventional methods to form a D shaped frame which is then moulded with a self-skinning polyurethane foam. In this example, the forward-most parts of the frame assembly which are most likely to come into contact with a colliding object first, are also the parts of the frame assembly furthest from the mounting. However, this is not essential.

Nudge bar frame assemblies in which the strengthening strips are graduated in strength in this way can also be used in conjunction with shock absorbing units as described in the first aspect of the invention. In this case, the forward-most parts of the frame assembly which are most likely to come into contact with a colliding object first, are also the parts of the frame assembly furthest from the mounting.

Claims

1. A shock absorbing vehicle nudge bar comprising a frame assembly adapted to be mounted to a vehicle body by way of one or more resilient mounting means interposed between the frame assembly and the vehicle body such that in use when the nudge bar is subject to an impact the frame assembly is adapted to absorb some or all of the impact by undergoing angular deflection relative to the vehicle body whilst being adapted to revert to substantially its original position after the impact.

2. A nudge bar as in claim 1 wherein the resilient mounting means comprises a first housing adapted to be mounted onto the frame assembly; a second housing adapted to be attached to the vehicle either directly or indirectly and a resiliently deformable means linking the first and second housing.

3. A nudge bar as in claim 2 wherein the resiliently deformable means is a block of plastics material or rubber.

4. A nudge bar as claimed in any of claims 2 and 3 wherein the first and second housings are pivotally connected.

5. A nudge bar as claimed in claim 4 wherein the first and second housings are pivotally connected by means of a pivot bolt which passes through the first and second housings and the resiliently deformable means whilst still allowing the top and bottom housings to move relative to one another.

6. A nudge bar as claimed in any of claims 2 to 5 wherein the lower surface of the first housing co-operates with the inner lower surface of the second housing such that in use the housings may move relative to one another.

7. A nudge bar as claimed in any preceding claim wherein said frame assembly comprises one or more bars, at least the front part of one or more bars being formed as a moulding of resilient plastics or rubber material, some or all of said bars incorporating an insert strip adapted to strengthen the moulding; characterised in that the insert strip(s) are graduated in strength being weakest in the bar(s) whose front surface(s) provide the most forward part of the nudge bar.

8. A nudge bar as in claim 7 wherein the moulding(s) is of a semi-rigid, self skinning, foamed polyurethane.

9. A nudge bar as claimed in claim 7 or claim 8 wherein the insert strips are formed either from metal or plastics material or a combination of metal and plastics material.

10. A vehicle nudge bar comprising a frame assembly adapted to be attached to a vehicle body, said frame assembly comprising one or more bars, at least the front part of one or more bars being formed as a moulding of resilient plastics or rubber material, some or all of said bars incorporating an insert strip adapted to strengthen the moulding; characterised in that, the insert strip(s) are graduated in strength being weakest in the bar(s) whose front surface(s) provide the most forward part of the nudge bar.

11. A nudge bar as in claim 10 wherein the moulding(s) is of a semi-rigid, self skinning, foamed polyurethane.

12. A nudge bar as claimed in claim 10 or claim 11 wherein the insert strips are formed either from metal or plastics material or a combination of metal and plastics material.