WO1999063632A1

WO1999063632A1 - Backplate assembly with seal

Info

Publication number: WO1999063632A1
Application number: PCT/US1999/011727
Authority: WO
Inventors: Spencer D. Flora; Gregory G. Karns; Kurt A. Begue; John A. Forish
Original assignee: Federal-Mogul Corporation
Priority date: 1998-06-03
Filing date: 1999-05-27
Publication date: 1999-12-09
Also published as: AU4211199A

Abstract

An automotive backplate (100) having a seal (155) is formed by injecting a first material into a mold to define a substantially rigid structure in the automotive backplate. An elastomeric material then is injected into the mold to define a seal (155) of the automotive backplate (100).

Description

BACKPLATE ASSEMBLY WITH SEAL TECHNICAL FIELD The invention relates to forming a backplate assembly for automotive lighting.

BACKGROUND Backplate assemblies can accommodate multiple lamps and are used, for example, in tail lights of automobiles or other vehicles. A backplate assembly allows efficient preassembly of an automobile lamp assembly. The lamp assembly can then be installed as a single unit into a vehicle under construction and electrically connected to the wiring harness of the vehicle using a single connector socket.

One type of backplate assembly includes two substantially rigid panels. The panels include apertures which are aligned with each other. Conductors are disposed between the panels and include contact pads which extend into the apertures. The panels are interconnected so that the conductors are sealed between the panels and only the contact pads are exposed to the exterior of the backplate assembly. Multiple lamp socket assemblies may be inserted into the apertures of the backplate assembly. The backplate assembly, including all of the lamp socket assemblies, may be attached to a lighting assembly, such as a tail light lens, of a motor vehicle.

An elastomeric seal may be secured between the backplate assembly and the lighting assembly to provide a water tight seal between them. To this end, the backplate assembly may be molded to include a perimeter groove. During manufacture or installation of the backplate assembly, a molded elastomeric seal is inserted into the groove. The seal may be held in place by adhesive or by a friction fit.

In another approach to installing the elastomeric seal, a liquid material is poured into the perimeter groove of the backplate assembly. The liquid material is then cured to form the elastomeric seal. SUMMARY

The invention provides a backplate assembly having an elastomeric seal formed in the same molding process used to produce the backplate assembly. In general, the molding process is a two-shot process in which a hard plastic material for use in forming the backplate is injected into the mold, with the hard plastic material being followed by an elastomeric material for use in forming the seal. Similar techniques may be used to form seals on lamp socket assemblies. The techniques promise to provide substantial time and cost savings in the production of backplate assemblies. The backplate assembly and the elastomeric seal, both of which are formed from thermoplastic polymers, are chemically or molecularly bonded together during the molding process. In general, materials used in forming the assembly and the seal are selected so as to form a chemical or molecular bond during the molding process without the use of adhesives or other materials. The materials are further selected to have properties required for backplate assemblies, such as compression set and thermal properties. Suitable materials for the backplate may include acrylonitrile butadiene styrene ("ABS"), reinforced polypropylene, and nylons (poly amides). Suitable materials for the seal may include silicone rubber, thermoplastic rubbers, such as santoprene, and thermoplastic olefins. In one general aspect, an automotive backplate assembly having a seal is formed by using an injection molding machine to inject a first material into a mold to produce a lower body plate. The injection molding machine then is used to inject a second, elastomeric material into the mold to form an elastomeric seal. Finally, circuitry is positioned on top of the lower body plate and covered by an upper body plate to form the finished backplate assembly.

Embodiments may include one or more of the following features. The mold may be altered to form a seal cavity after injecting the first material into the mold. For example, when the mold includes first and second halves, altering the mold may include replacing the second mold half with a third mold half, or translating the first mold half to mate with the third mold half. Altering the mold also may include withdrawing at least a portion of the second mold half from the first mold half to form the seal cavity. The second material may be injected before the first material is cured. In another general aspect, an automotive backplate having a seal is formed using an injection molding machine. Electrical backplate circuitry is positioned in a mold of the injection molding machine, and the injection molding machine is operated to inject a first material into the mold. The first material contacts the circuitry and defines a substantially rigid structure of the automotive backplate. The injection molding machine then is operated to inject a second, elastomeric material into the mold. The elastomeric material defines a seal of the automotive backplate.

In another general aspect, an automotive backplate assembly includes a substantially rigid housing and an elastomeric seal defined around a perimeter of the housing. The elastomeric seal is bonded to the housing by forming the housing and the elastomeric seal using a two-step injection process in which an injection machine injects a first material into the mold to define the housing, and then injects a second, elastomeric material into the mold to define the elastomeric seal. The backplate assembly also includes electrical circuitry sealed within the housing and having exposed contacts extending from the housing, and an electrical socket connector for o connecting the electrical circuitry to the wiring harness of an automobile.

Other features and advantages will be apparent from the following description, including the drawings, and from the claims.

DESCRIPTION OF DRAWINGS

Fig. 1 is a front view of a sealed backplate assembly. 5 Fig. 2 is a front view of a rear plate of the assembly of Fig. 1.

Figs. 3 and 4 are side and rear views of the rear plate of Fig. 2. Fig. 5 is a side view of a lamp socket assembly. Figs. 6A-6G, 7A-7E, 8A-8G, and 9A-9E are side views showing steps performed by injection molding systems.

DETAILED DESCRIPTION

Prior to describing techniques for forming a backplate assembly, a particular backplate assembly and lamp socket assembly for use in motor vehicles is described with reference to Figs. 1-5. This description is provided for illustrative purposes only, and is not intended to limit the type of backplate assembly to which the techniques of the invention may be applied. For example, while the described backplate assembly includes apertures configured to receive separate lamp socket assemblies, the described techniques are also applicable to backplate assemblies having integral lamp socket assemblies.

Referring to Figs. 1 and 2, a backplate assembly 100 includes four apertures 105. Each aperture 105 receives a lamp socket assembly 110 (Fig. 5), with each lamp socket assembly providing a lamp suitable for an illumination function, such as, for example, indication of braking, turn signal activation and backing up operations. Backplate assembly 100 includes circuitry for electrically interconnecting the lamp socket assemblies disposed in apertures 105 and for connecting backplate assembly 100 to an automobile wiring harness (not shown) with a single socket connector 115 (Fig. 2). Four clips 120 serve to secure the backplate assembly 100 to a vehicle lighting assembly (not shown). A similar backplate assembly and corresponding lamp socket assemblies are described in detail in U.S. Patent Nos. 5,529,535 and 5,536,175, both of which are incorporated by reference.

The backplate assembly 100 is formed by an upper body panel or cover 125 and a similarly shaped lower body panel or base 130. Upper and lower body panels 125 and 130 are preferably shell halves formed from a rigid insulative material. Lower body panel 130 is generally planar in overall configuration. In an alternate embodiment, panel 130 may include an offset region coinciding with the area in which backplate assembly 100 connects to the automobile wiring harness. Body panels 125 and 130 are molded from an electrically insulative material such as a suitable plastic. Although backplate assembly 100 is normally placed in the rear of an automobile with upper body panel 125 facing the rear of the automobile, body panel 125 is characterized as an upper panel while body panel 130 is characterized as a lower panel to facilitate explanation.

Electrical circuitry 135 is sealed between upper and lower body panels 125 and 130 so that the lamp socket assemblies 110 can be selectively energized. Electrical circuitry 135 is formed from stamped conductors. Conductors are stamped from a thin sheet of electrically conductive material, such as tin coated steel. Circuitry 135 is formed to closely conform to tracks in lower panel 130 formed by channels 140 between upper and lower body panels 125 and 130. Circuitry 135 includes contact pads 145 that conduct electricity from the vehicle's wiring harness through circuitry 135 to the lamp socket assemblies 110. As shown in Fig. 2, the front face of lower body panel 130 includes keyed apertures 150 shaped to receive locking lugs 155 (Fig. 5) of lamp socket assemblies 100. Keyed apertures 150 are disposed at various radial orientations within lower body panel 130 as required for the desired filament radial orientation. The aperture orientations are coordinated with the locations of contact pads 145. Lower body panel 130 also includes a connector socket 115 into which electrical circuitry 135 extends to mate with the wiring harness of the automobile (not shown).

An elastomeric seal 155 circles the perimeter of lower body panel 130 to provide a water tight seal between backplate assembly 100 and the vehicle to thereby prevent corrosion of the lamp socket assemblies and circuitry 135. Upper body panel 125 is fitted within the area encircled by seal 155 of lower body plate 130 and on top of circuitry 135.

As shown in Figs. 3 and 4, lower body panel 130 has a rear face 160 which includes downwardly projecting cylindrical sleeves 165. The inner surfaces of cylindrical sleeves 165 are structured to sealingly cooperate with axial seals 168 (Fig. 5) of the lamp socket assemblies 110. Cylindrical sleeves 165 define circular openings 170 through lower body panel 130. Electrical conductors 145 are exposed through circular openings 170 to allow for electrical connection with the terminals 175 (Fig. 5) of the lamp socket assemblies 110.

Connector socket 115 includes a protective sleeve 180 and alignment flanges 185 for aligning a mating electrical connector. Connector socket 115 also includes a primary locking tab 190 and secondary locking tabs 195 to secure connector socket 115 to a mating connector. Fig. 5 illustrates a side view of a lamp socket assembly 110 operationally installed to partially shown backplate assembly 100. Lamp socket assembly 110 includes a base or housing 500, a body 505, and a lamp 510. Assembly 110 also includes terminals 175 for electrical interconnection of the contacts with contact pads 145 of backplate assembly 100. When backplate assembly 100 is installed, and when lamp socket assembly 110 is fully inserted into and locked within one of keyed apertures 150, lamp 510 projects within the sealed tail light assembly as shown.

A ribbed axial seal 168 made from an elastomeric material such as silicon rubber is circumferentially disposed around a cylindrical portion of housing 500. Axial seal 168, which is seated on a radially extending mounting flange 515 of housing 500 and is axially retained by four radially extending prongs 520 spaced at 90° intervals. Seal 168 engages the inner surface 525 of cylindrical sleeves 165 to provide a moisture impermeable seal between lamp socket assembly 110 and backplate assembly 100 to prevent passage of moisture from the atmosphere into the interior of lamp housing. The ribs of seal 168 ensure a positive seal with backplate assembly 100.

Figs. 6A-6G illustrate production of backplate assembly 100 using a single machine with first, second and third mold halves, 605, 610 and 615 respectively. Backplate assembly 100 is formed by using a first injector nozzle 620 to inject a first resin into a cavity 625 formed by mold halves 605 and 610 as shown in Figs. 6A and 6B. Cavity 625 corresponds in shape to lower body plate 130. Next, second mold half 610 is replaced with third mold half 615 as shown in Fig. 6C. Third mold half 615 differs from second mold half 610 in that third mold half 615 defines a seal cavity 630 for the elastomeric seal 155. A second resin is then injected through an injector nozzle 635 into seal cavity 630 on top of lower body plate 130 as shown in Fig. 6D. This second resin, when cured, has the elastomeric properties needed to form an elastomeric seal.

Replacing second mold half 610 with third mold half 615 can be accomplished by translating first mold half 605 to mate with third mold half 615, or by replacing second mold half 610 with third mold half 615.

The combination of lower body plate 130 and seal 155 is removed from the injection mold device, as shown in Fig. 6E. Appropriate electrical circuitry 135 is then positioned on top of lower body plate 130 (Fig. 6F) and covered by upper body plate 125 (Fig. 6G) to make the final assembly 100. Body plate 175 may be secured to plate 130 using, for example, an adhesive or ultrasonic welding.

As illustrated in Figures 7A-7E, in an alternate approach, an assembly 100 having a seal 155 is formed using first, second and third mold halves 705, 710 and 715. First, electric circuitry 135 stamped from the appropriate conductive material is placed in a cavity 720 defined by mold halves 705 and 710. In Fig. 7 A, circuitry 135 is illustrated as floating above the bottom of cavity 720. This is achieved by sandwiching portions of the circuitry 135 corresponding to the contact pads 145 between the mold halves 705 and 710 so that the contact pads support the circuitry. As shown in Fig. 7B, a first resin is injected through injector nozzle 725 into cavity 720. The first resin envelopes circuitry 135 to form a single piece backplate 730. Next, second mold half 710 is replaced by third mold half 715 to form seal cavity 735 (Fig. 7C). A second resin is injected through injector nozzle 740 to form an elastomeric seal 745 around the perimeter of single piece backplate 730 (Fig. 7D).

As shown in Fig. 7G, single piece backplate 730 together with seal 745 is equivalent to the combination of upper body plate 125, lower body plate 130, circuitry 135 and seal 155 produced by the method illustrated in Figs. 6A-6G.

In another approach, a backplate assembly 100 can be formed using the system and method illustrated in Figs. 8A-8G. This alternate approach uses first and second mold halves, 805 and 810 respectively, as shown in Fig. 8 A. Backplate assembly 100 is formed by using injector nozzle 815 to inject a first resin into cavity 820 formed by mold halves 805 and 810. Cavity 820 corresponds in shape to lower body plate 130. Next, second mold half 810 is retracted as shown in Fig. 8C until a seal cavity 825 is formed between second mold half 810 and lower body plate 130. Then, a second resin is injected into seal cavity 825 to form the elastomeric seal 155 shown in Fig. 8D. The result is two distinct areas, lower body plate 130 and seal 155, each comprised of a different resin type.

As shown in Fig. 8E, the combination of lower body plate 130 and seal 155 is removed from the mold. Appropriate electrical circuitry 135 is then positioned on top of lower body plate 130 (Fig. 8F) and covered by upper body plate 125 (Fig. 8G) to form the final backplate assembly 100. In a further variation of the method and system just described, as illustrated in Figs. 9A-9E, the assembly 100 is formed using first and second mold halves 905 and 910. First, electric circuitry 135 stamped from the appropriate conductive material is placed in cavity 915 (Fig. 9A). Then, a first resin is injected through injector nozzles 920 into cavity 915. The first resin envelopes circuitry 135 to form a single piece backplate 925 as shown in Fig. 9B. Next, second mold half 910 is withdrawn until a seal cavity 930 is formed. A second resin is injected through injector nozzles 920 into seal cavity 930 to form an elastomeric seal 935 around the perimeter of single piece backplate 925, shown in Fig. 9C and 9D. Single piece backplate 925 and seal

- 8 - 135 (Fig. 9E) are equivalent to the combination of upper body plate 125, lower body plate 130, circuitry 135 and seal 155 produced by the method illustrated in Figs. 6A- 6G.

Other embodiments are within the scope of the following claims. For example, the techniques described above also may be used to produce other types of backplate assemblies, such as assemblies in which the lamp sockets and the backplate assembly are defined as a unitary piece.

What is claimed is:

Claims

L A method of forming an automotive backplate having a seal using an injection molding machine, the method comprising: using the injection molding machine to inject a first material into a mold to produce a lower body plate; altering the mold to create a seal cavity along the perimeter of the lower body plate; using the injection molding machine to inject a second, elastomeric material into the seal cavity to form an elastomeric seal; positioning electrical circuitry on top of the lower body plate; and positioning an upper body plate on top of the circuitry within the perimeter formed by the elastomeric seal.

2. The method as recited in claim 1 further comprising altering the mold after injecting the first material into the mold.

3. The method as recited in claim 2 wherein the mold comprises a first mold half and a second mold half and altering the mold comprises replacing the second mold half with a third mold half.

4. The method as recited in claim 2 wherein the mold comprises a first mold half and a second mold half and altering the mold comprises of translating the first mold half to mate with a third mold half.

5. The method as recited in claim 2 wherein altering the mold comprises withdrawing at least a portion of the second mold half from the first mold half to form the seal cavity.

6. The method as recited in claim 1 wherein the second material is injected before the first material is cured.

7. The method as recited in claim 1 wherein the first material is one of the group consisting of ABS, reinforced polypropylene and nylon.

8. The method as recited in claim 7 wherein the second material is one of the group consisting of silicone rubber, santoprene and thermoplastic olefins.

9. A method of forming an automotive backplate having a seal using an injection molding machine, the method comprising: positioning backplate circuitry in a mold of the injection molding machine; operating the injection molding machine to inject a first material into the mold, the first material contacting the circuitry and defining a substantially rigid structure of the automotive backplate; and operating the injection molding machine to inject a second, elastomeric material into the mold, the elastomeric material defining a seal of the automotive backplate.

10. The method as recited in claim 9 further comprising altering the mold after injecting the first material into the mold.

11. The method as recited in claim 10 wherein the mold comprises a first mold half and a second mold half and altering the mold comprises replacing the second mold half with a third mold half.

12. The method as recited in claim 10 wherein the mold comprises a first mold half and a second mold half and altering the mold comprises of translating the first mold half to mate with a third mold half.

13. The method as recited in claim 10 wherein altering the mold comprises withdrawing at least a portion of the second mold half from the first mold half to form the seal cavity.

14. The method as recited in claim 9 wherein the second material is injected before the first material is cured.

15. The method as recited in claim 9 wherein the first material is one of the group consisting of ABS, reinforced polypropylene and nylon.

16. The method as recited in claim 15 wherein the second material is one of the group consisting of silicone rubber, santoprene and thermoplastic olefins.

17. An automotive backplate assembly comprising: a substantially rigid housing, electrical circuitry sealed within the housing, the circuitry including exposed contacts extending from the housing, an electrical socket connector for connecting the electrical circuitry to the wiring harness of an automobile, and an elastomeric seal defined around a perimeter of the housing, wherein, the elastomeric seal is bonded to the housing by forming the housing and the elastomeric seal using a two step injection process in which: an injection machine injects a first material into the mold, the first material defining the housing, and the injection machine injects a second, elastomeric material into the mold, the second material defining the elastomeric seal.

18. The backplate assembly of claim 17, wherein the injection machine injects the elastomeric material into the mold before the first material cures so that the two materials cure together.

19. The backplate assembly of claim 17, wherein the housing is formed around the electrical circuitry.

20. The backplate assembly of claim 17, further comprising a cover, wherein the electrical circuitry is sealed between the cover and the housing.

21. The backplate assembly of claim 17, wherein the first material is one of the group consisting of ABS, reinforced polypropylene and nylon.

22. The backplate assembly of claim 17, wherein the second material is one of the group consisting of silicone rubber, santoprene and thermoplastic olefins.