Claims:We claim:

1. An energy absorbing bracket for rear bumper of vehicles for safety during low-speed rear impact, wherein the bracket comprises less number of parts, is dimensioned to be compact and made of a low-weight, low-cost material, such as plastics for ease of packaging, assembly and servicing thereof to facilitate excellent energy absorption during low-speed rear impacts.

2. Energy absorbing bracket as claimed in claim 1, wherein the bracket is made of polyoxymethylene (POM) or Acetal.

3. Energy absorbing bracket as claimed in claim 1, wherein the bracket comprises an initial crash zone and a secondary crash zone to facilitate excellent energy absorption during low-speed rear impacts.

4. Energy absorbing bracket as claimed in claim 3, wherein the initial crash zone and secondary crash zones are configured by incorporating cylindrical ribs and complex rib structure made of POM or acetal for efficiently dissipating the impact energy in low-speed rear-impacts.

5. Energy absorbing bracket as claimed in claim 4, wherein the cylindrical ribs are reinforced by means of the complex profiled hollow rib structure connected thereto.

6. Energy absorbing bracket as claimed in claim 5, wherein the cylindrical ribs and the profiled hollow rib structure is configured depending on the distance between the bumper’s rear-most surface and the tail-lamp starting surface.

7. An energy absorbing bracket for rear bumper of vehicles for safety during low-speed rear impact, and having less number of parts and made of polyoxymethylene (POM) or Acetal to be compact for ease of packaging, assembly and servicing thereof to facilitate excellent energy absorption during low-speed rear impacts, the bracket comprising:

• an initial crash zone;
• a secondary crash zone;
• cylindrical ribs; and
• complex rib-structure for reinforcing both the crash zones;

wherein the cylindrical ribs are reinforced by means of the complex profiled hollow rib structure connected thereto.

8. Energy absorbing bracket as claimed in claim 7, wherein the cylindrical ribs are connected by means of the thin profiled ribs of a complex structure depending on the distance between the bumper’s rear-most surface and the tail-lamp starting surface.

9. Energy absorbing bracket as claimed in any one of the claims 1 to 8, wherein the dimensions of the bracket are configured smaller, preferably 170 x 230 x 150 mm, by using a complex profiled hollow rib structure reinforcing the cylindrical ribs by unique geometry thereof and the sharing of crash energy strategy therebetween.

10. Energy absorbing bracket as claimed in any one of the claims 1 to 9, wherein a single bracket is used on each side of the rear-bumper for substantially reducing the material cost by using polyoxymethylene (POM) or Acetal, preferably the cost-reduction is almost one-fourth the cost of PP foam bracket.

Dated: this 30th day of June 2017. SANJAY KESHARWANI
APPLICANT’S PATENT AGENT
FOR: MAHINDRA & MAHINDRA LTD. , Description:FIELD OF INVENTION

The present invention relates to front and rear protection devices in vehicles complying with ECE R42 regulations. In particular, the present invention relates to front and rear protection devices in vehicles, which are effective against low-speed impacts as per ECE R42 regulations. More particularly, the present invention relates to rear protection devices, such as rear bumpers for vehicles made in plastics, which are light, low-cost and compact as well as effective against low-speed impacts.

BACKGROUND OF THE INVENTION

The other hard type absorbers consist of a rigid reinforcing beam support to meet ECE Regulation No. 42, entitled: Uniform Provisions Concerning the Approval of Vehicles with regard to their Front and Rear Protective devices (Bumpers etc.), which applies to the behavior of certain parts of the front and rear structure of passenger cars when involved in a collision at low speed.

The object of this regulation is to assure an exterior protection by protective devices which are essentially elements located at the front and rear ends of vehicles and effective against low-speed contacts and/or impacts without causing any serious damage.

PRIOR ART

Current bumper collision system uses several separate components assembled together and the sizes of the reinforcement components are usually large. Typically, these components include a soft energy absorber which must undergo an iterative designing and testing process and the cost of the material is high as compared to other materials. Other hard type absorbers consist of a rigid reinforcing beam support to meet the ECE R42 impact regulations. The energy absorber component can be mounted close to the steel or aluminum rigid support beam to strengthen the thermoplastic resin member or a polypropylene foam piece.
Bumper assembly typically includes a reinforcing beam, which is configured to be connected to the car beam (an energy absorber) and may be connected to an energy absorbing decorative panel on the car.

Normally, the bumpers fitted in 2 ton vehicles running at low speed, i.e. under 2.5 kmph should be strong enough to absorb impact energy on hitting any solid body. These energy absorbers can be mounted close to the steel or aluminum rigid support beam to strengthen the thermoplastic resin member or a polypropylene (PP) foam piece.

As per the prevailing ECE R42 regulations concerning front and rear protective devices low-speed makes it mandatory that the bumper contact area should be strong enough and the deflection of bumper must be within a prescribed limit to prevent any serious damage to the systems as summarized below:

S. No. Regulatory requirement ECE R42 CAE Target to meet ECE R42
1 Lighting and signaling devices shall continue to operate correctly and to remain visible. Check the head lamp and fog lamp deformation and plastic strains of the components below failure strain limit.
2 Vehicle's hood and doors shall operate in the normal manner. Side doors of the vehicle shall not be able to open during the impact. Check the hood and doors deformation at latch locations.
3 Vehicle fuel and cooling systems shall have no leaks nor constricted fluid passages. Check the fuel and cooling system deformation.
4 Vehicle propulsion, suspension, steering and braking systems shall remain in adjustment and shall operate in the normal manner. Check the suspension, steering and breaking deformation.
5 Vehicle exhaust system shall not suffer any damage or its normal function. Check the exhaust system deformation.

Moreover, the slow-speed impact is applicable on the sides of the vehicles with spare wheel mounted on the tail-door.

DISADVANTAGES WITH THE PRIOR ART

The existing rear bumpers discussed above have the following disadvantages:
• Rigid PP Foam material used.

• Larger bracket size.

• Heavier construction.

• Uses higher no. of components.

• PP Foam material costs higher.

• Packaging is challenging due to larger bracket size.

• Fixing of conventional PP Foam rear bumper is difficult.

• Locating the bracket before fixing is difficult, so accuracy cannot be maintained.

• Detachment of bracket from the bumper is difficult, so poor to service.

OBJECTS OF THE INVENTION

Some of the objects of the present invention - satisfied by at least one embodiment of the present invention - are as follows:

An object of the present invention is to provide an energy absorbing bracket for safety during low-speed rear impact on vehicles.

Another object of the present invention is to provide a low-weight and low-cost energy absorbing bracket made of plastics.

Still another object of the present invention is to provide a compact energy absorbing plastic bracket, which are easy from packaging point of view.

Yet another object of the present invention is to provide an energy absorbing plastic bracket, which are easy to assemble and service.

A further object of the present invention is to provide an energy absorbing plastic bracket, which has less number of parts.
These and other objects and advantages of the present invention will become more apparent from the following description, when read with the accompanying figures of drawing, which are however not intended to limit the scope of the present invention in any way.

SUMMARY OF THE INVENTION

In accordance with an embodiment of the present invention, there is provided an energy absorbing bracket for rear bumper of vehicles for safety during low-speed rear impact, wherein the bracket comprises less number of parts, is dimensioned to be compact and made of a low-weight, low-cost material, such as plastics for ease of packaging, assembly and servicing thereof to facilitate excellent energy absorption during low-speed rear impacts.

Typically, the bracket is made of polyoxymethylene (POM) or Acetal.

Typically, the bracket comprises an initial crash zone and a secondary crash zone to facilitate excellent energy absorption during low-speed rear impacts.

Typically, the initial crash zone and secondary crash zones are configured by incorporating cylindrical ribs and complex rib structure made of POM or acetal for efficiently dissipating the impact energy in low-speed rear-impacts.

Typically, the cylindrical ribs are reinforced by means of the complex profiled hollow rib structure connected thereto.

Typically, the cylindrical ribs and the profiled hollow rib structure is configured depending on the distance between the bumper’s rear-most surface and the tail-lamp starting surface.

In accordance with another embodiment of the present invention, there is provided an energy absorbing bracket for rear bumper of vehicles for safety during low-speed rear impact, and having less number of parts and made of polyoxymethylene (POM) or Acetal to be compact for ease of packaging, assembly and servicing thereof to facilitate excellent energy absorption during low-speed rear impacts, the bracket comprising:

• an initial crash zone;
• a secondary crash zone;
• cylindrical ribs; and
• complex rib-structure for reinforcing both the crash zones;

wherein the cylindrical ribs are reinforced by means of the complex profiled hollow rib structure connected thereto.

Typically, the cylindrical ribs are connected by means of the thin profiled ribs of a complex structure depending on the distance between the bumper’s rear-most surface and the tail-lamp starting surface.

Typically, the dimensions of the bracket are configured smaller, preferably 170 mm x 230 mm x 150 mm, by using a complex profiled hollow rib structure reinforcing the cylindrical ribs by unique geometry thereof and the sharing of crash energy strategy therebetween.

Typically, a single bracket is used on each side of the rear-bumper for substantially reducing the material cost by using polyoxymethylene (POM) or Acetal, preferably the cost-reduction is almost one-fourth the cost of PP foam bracket.

DESCRIPTION OF THE INVENTION

The rear bracket configured in accordance with the present invention can absorb the low-speed impact energy during contacts and/or impacts of crash without the use of any of the additional parts, e.g. rigid reinforcing beam support of made PP foam, energy absorber (car beam), decorative panel on vehicle. The geometry of this rear bracket is dimensioned for maximum energy absorption during collapse. This rear bracket configuration is also optimized for reducing the bracket size to limit the weight and costs thereof.
The dimensions of this bracket are smaller than the conventional rear bracket (252 x 175 x 243 mm for PP foam and 1080 x 153 x 180 mm for PP) due to its unique geometry and the sharing of crash energy strategy.

The metal body does not require any special/additional reinforcement brackets for absorbing a portion of the impact force as was necessary with the conventional PP foam brackets.

The cost saving is also substantial, because the conventional PP foam material costs about INR 500/kg, whereas polyoxymethylene (POM) or acetal used in accordance with the present invention costs only about INR 130/kg, which is just about 26% of the PP foam material.

The rear bracket of the present invention bracket is also much smaller (preferably 170 mm x 230 mm x 150 mm) than the conventional PP foam bracket. This compactness is achieved by using a complex profiled hollow rib structure reinforcing the cylindrical ribs by it unique geometry and by sharing the crash energy strategy therebetween The POM bracket is very easy to be located by fastening, e.g. positive screwing, for attaching the bracket parts on the body. This also facilitates assembly and service thereof.

Moreover, the bracket functionally meets the requirement of ECE R42 regulation same as in the conventional PP foam bracket. The new polyoxymethylene (POM) or acetal rear bracket includes a complex rib structure which successfully passed in CAE analysis.

Energy absorption capacity of bracket is more important to get the results. This is achieved by with balancing the design geometry between strength and collapsibility. By doing more iteration of CAE analysis, the bracket’s energy absorption capacity can be improvised.

Wherever the ribs are weak, more deflection occurs and the load is transferred to the other part. These ribs need to be improvised by increasing the height and width thereof.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

The present invention will be briefly described with reference to the accompanying drawings, wherein:

Figure 1a shows a conventional rear bumper in a vehicle.

Figure 1b shows the stress diagram for rear bumper deflection analysis of the zone X-D encircled in Fig. 1a.

Figure 2 shows the side view of the vehicle rear portion fitted with the rear bumper.

Figure 3 shows a schematic representation of the rear bumper for calculating bumper deflection limitation along the cross-section B-B of the bumper and reinforcement bracket.

Figure 4 shows the rear bumper with complex rib-structure of the reinforcement bracket for reducing the deflection of the rear-bumper across the cross-section thereof.

Figure 5 shows a front view of the vehicle rear bumper configured in accordance with the present invention and made of polyoxymethylene (POM) or acetal.

Figure 6 shows a front cross-sectional view of the rear-bumper of Figure 4a depicting the cylindrical ribs configured according to the present invention.

Figure 7 shows a perspective sectional view of the rear-bumper of Figure 4a depicting the complex rib-structure configured in accordance with the present invention.

DETAILED DESCRIPTION OF THE ACCOMPANYING DRAWINGS

In the following, the rear bumper made of plastic with a complex rib structure configured in accordance with the present invention will be described in more details with reference to the accompanying drawings without limiting the scope and ambit of the present invention in any way.

Figure 1 shows a rear bumper in a vehicle. The bumper’s deflection zone should be calculated before making the reinforcement bracket, which depends on the vehicle model. In some vehicles, solid members like spare wheel are required to be mounted on tail door (e.g. Ford Eco-sport, Mahindra TUV300, Tata Sumo). It should be ascertained whether the center impact could be avoided by using a solid member at the center. If so, the focus should be only on the side face of the bumper. Here, a tail door 10 is shown fitted with a spare wheel 20. The rear bumper 30 has a pendulum impact zone 40. This encircled zone marked X-D is analyzed further for analyzing deflection thereof (Fig. 1b).

Figure 1b shows the stress diagram for rear bumper deflection analysis of the zone X-D encircled in Fig. 1a. The X-displacement values in zones A1 (-62.55 to -73.80) and A2 (-51.50 to 62.550 is the highest under low-speed impact analysis in CAE, after analyzing the results of the rear bumper without having any structural bracket behind the bumper.

Figure 2 shows the side view of the vehicle rear portion depicted with the rear bumper indicating the initial crash zone CZ1 and secondary crash zone CZ2.

Figure 3 shows a schematic representation of the rear bumper for calculating bumper deflection limitation along the cross-section B-B of the bumper and reinforcement bracket 80. The tail lamp 50 is fitted on top of the bumper 60. A cross-section B-B is marked for subsequent calculations of the bumper deflection.

Figure 4 shows the rear bumper with complex rib-structure of the reinforcement bracket 80 for reducing the deflection of the rear-bumper across the cross-section thereof. The major regions for these calculations are the tail lamp starting surface 62, bumper rear-most surface 64 touched by the pendulum, initial pendulum hitting area 66 and secondary pendulum hitting area 68. In addition, the BIW panel 70 and reinforcement bracket 80 are also marked herein. The distance d1 from bumper rear-most surface 64 and tail lamp starting surface 62 is considered for bumper deflection limitation during an impact. The tail lamp 50 is considered, which is the only component applicable under ECE R42 regulation for the vehicle of interest. If the impact deflection is more than the measured value, the pendulum hits the tail lamp 50 and there is a higher probability of the tail lamp breakage. Therefore, the plastic bracket should be designed to reduce the bumper deflection.

Figure 5 shows a front view of the vehicle rear bumper 80 configured in accordance with the present invention and made of polyoxymethylene.

Figure 6 shows a front cross-sectional view of the rear-bumper 80 of Figure 4a depicting the cylindrical ribs 82 and complex rib-structure 84 configured in accordance with the present invention.

Figure 7 shows a perspective sectional view of the rear-bumper 80 of Figure 4a depicting the cylindrical ribs 82 and complex rib-structure 84 configured according to the present invention.

WORKING OF THE INVENTION

The invention involves the developing an energy dissipating method in low-speed rear-impact by using plastic brackets. The impact energy generated during the crash is controlled by using innovative initial and secondary crash zones A1, A2 as shown in Fig. 2. The initial pendulum impact is on the bumper mounting sheet metal bracket, which absorbs a part of the energy. This is called as the initial crash zone A1. The pendulum then makes contact with the plastic bracket which absorbs the rest of the impact energy limiting the pendulums intrusion into the tail lamp 50. This crash zone is called as the secondary crash zone A2.

This innovative strategy of splitting the impact into two zones A1, A2 helps this plastic bracket to effectively absorb and dissipate the remaining crash energy. This division of crash zones also helps in optimizing the plastic bracket size to a minimum limit as opposed to the conventional brackets.

Further, the plastic bracket geometry is subdivided into the initial 66 and secondary 68 pendulum impact zones and reinforced as per the energy dissipation requirements using the CAE tool.

The complex ribbing structure on the plastic bracket is derived after several iterations of CAE to have an optimal energy absorption capability. After the impact, a 7.0 mm clearance was determined with the tail lamp starting surface in order to successfully complying with the regulation ECE R42.

TECHNICAL ADVANTAGES AND ECONOMIC SIGNIFICANCE

The rear-bumper with a complex rib-structure configured in accordance with the present invention has the following technical and economic advantages:

• Low material cost and overall low-cost.

• Light-weight.

• Compact in size.

• Easy packaging.

• Facilitates assembly and service.

• Excellent energy absorption during low-speed impacts.

• Less number of components/parts.

The exemplary embodiments described in this specification are intended merely to provide an understanding of various manners in which this embodiment may be used and to further enable the skilled person in the relevant art to practice this invention. The description provided herein is purely by way of example and illustration.
Although, the embodiments presented in this disclosure have been described in terms of its preferred embodiments, the skilled person in the art would readily recognize that these embodiments can be applied with modifications possible within the spirit and scope of the present invention as described in this specification.

Accordingly, the skilled person can make innumerable changes, variations, modifications, alterations and/or integrations in terms of materials and method used to configure, manufacture and assemble various constituents, components, subassemblies and assemblies, in terms of their size, shapes, orientations and interrelationships without departing from the scope and spirit of the present invention.

While considerable emphasis has been placed on the specific features of the preferred embodiment described here, it will be appreciated that many additional features can be added and that many changes can be made in the preferred embodiments without departing from the principles of the invention. These and other changes in the preferred embodiment of the invention will be apparent to those skilled in the art from the disclosure herein, whereby it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the invention and not as a limitation.

Many of the fastening, connection, processes and other means and components utilized in this invention are widely known and used in the field of the invention described, and their exact nature or type is not necessary for an understanding and use of the invention by a person skilled in the art and they will not therefore be discussed in significant detail.

The numerical values given of various physical parameters, dimensions and quantities are only approximate values and it is envisaged that the values higher or lower than the numerical value assigned to the physical parameters, dimensions and quantities fall within the scope of the disclosure unless there is a statement in the specification to the contrary.

Throughout this specification the word “comprise”, or variations such as “comprises” or “comprising”, shall be understood to implies including a described element, integer or method step, or group of elements, integers or method steps, however, does not imply excluding any other element, integer or step, or group of elements, integers or method steps.

The use of the expression “a”, “at least” or “at least one” shall imply using one or more elements or ingredients or quantities, as used in the embodiment of the disclosure in order to achieve one or more of the intended objects or results of the present invention.

Also, any reference herein to the terms ‘left’ or ‘right, ‘up’ or ‘down, or ‘top’ or ‘bottom’ are used as a matter of mere convenience, and are determined by standing at the rear of the machine facing in its normal direction of travel.

Furthermore, the various components shown or described herein for any specific application of this invention can be widely known or used in the art by persons skilled in the art and each will likewise not therefore be discussed in significant detail. When referring to the figures, like parts are numbered the same in all of the figures.