WO2013189026A1

WO2013189026A1 - Vehicle instrument cluster assembly and method of manufacturing the same

Info

Publication number: WO2013189026A1
Application number: PCT/CN2012/077145
Authority: WO
Inventors: Stephane SCHULER; Yannick FEDER; Pascal BEQUIN
Original assignee: Johnson Controls (China) Investment Co., Ltd
Priority date: 2012-06-19
Filing date: 2012-06-19
Publication date: 2013-12-27

Abstract

A vehicle instrument cluster (10) includes a printed circuit board assembly (12), a front portion (14) and a back portion (16) with the front portion (14) and the back portion (16) integrally formed to provide an encapsulating structure (18) enclosing the printed circuit board assembly (12). The encapsulating structure (18) of the vehicle instrument cluster (10) is provided by insert molding of low density polymers. A method of manufacturing a vehicle instrument cluster (10) is also provided, which comprises the step of encapsulating a printed circuit board assembly (12) with low density polymers to form an encapsulating structure (18) by insert molding.

Description

VEHICLE INSTRUMENT CLUSTER ASSEMBLY AND METHOD OF

MANUFACTURING THE SAME

Technical Field

The invention relates to an instrument cluster for automobiles. The invention also relates to a method of manufacturing an instrument cluster for automobiles.

Background Art

An instrument cluster assembly, also known as instrument panel, for automobiles such as vehicles is typically used for displaying operation information such as vehicle speed, engine rotation speed (RPM), engine temperature, fuel level, distance travelled or other information of the vehicle components during operation. A typical vehicle instrument cluster is shown in Figure 1, which usually consists of a display panel for displaying information, a raised top cover or maybe also side covers for easy viewing of the information regardless of the lighting condition of the operating environment, a printed circuit board (PCB) with various components assembled thereon (i.e. a printed circuit board assembly (PCBA)) connects to the vehicle computer to control the displayed information, a housing or a frame for adapting the instrument cluster to the vehicle dash board, which is usually by means of fasteners to secure the housing to the vehicle. In addition, an instrument cluster assembly usually consists of a rear cover for protecting the backside of the PCB. The rear cover, which is typically made with non-conducting materials such as polypropylene, protects the PCB and thus the instrument cluster from electrostatic discharge. The rear cover may also carry additional fastening means such as screws, clips or the like to secure the instrument cluster to the vehicle.

The display panel of the instrument cluster may display information in analog or digital readings. An analog display panel usually comprises a faceplate having gauges with numbers and graduations as indicia, and pointers caused to sweep angularly across the indicia by electromechanical movements. The faceplate is usually made with white or reflective materials such as acrylonitrile butadiene styrene (ABS). Alternatively, a digital display panel usually comprises a electronic screen, such as a liquid crystal display (LCD), showing a digital readout of the parameters of the operating vehicle. The display panel may also be provided with light-emitting diode (LED) as indicating lights or to serve other optical functions. It is known that conventional instrument cluster assemblies are usually heavy and bulky, with the assembling usually involves handling of a number of parts and installation steps which could be difficult, troublesome and time consuming. It is therefore an object of the present invention to provide a vehicle instrument cluster, in which the aforesaid shortcoming is mitigated, or at least to provide a useful alternative to the public.

Summary of the Invention

According to one aspect of the invention there is provided a vehicle instrument cluster. The instruction cluster comprises a printed circuit board, a front portion and a back portion. The front and the back portions are integrally formed to provide an encapsulating structure enclosing the printed circuit board.

According to another aspect of the invention there is provided a method of manufacturing a vehicle instrument cluster. The method comprises the step of encapsulating a printed circuit board with a low density polymer to form an encapsulating structure by insert molding.

Brief Description of the Drawings

Figure 1 shows a perspective view of an instrument cluster of the prior art.

Figure 2 shows a perspective view of an instrument cluster in accordance with an embodiment of the present invention.

Figure 3 shows a plan side view of the instrument cluster in Figure 2.

Figure 4 shows a side cross-sectional view of the printed circuit board when introduced in a mold cavity during the encapsulating process in accordance with an embodiment of the present invention.

Detailed Description of Preferred Embodiments

Figures 2 and 3 show a vehicle instrument cluster 10 in accordance with an embodiment of the present invention. The instrument cluster 10 comprises a printed circuit board assembly (PCBA) 12. A printed circuit board assembly (PCBA) is a printed circuit board (PCB) with various electrical components assembled thereon. For the purpose of a vehicle instrument cluster, these electrical components may include but not limited to switches, lighting devices, motors, or display screens etc.

With reference to Figures 2 and 3, the instrument cluster 10 includes a front portion 14 and a back portion 16, with the front 14 and the back portions 16 being integrally formed to provide an encapsulating structure 18 enclosing the PCBA 12. The PCBA 12 is to be encapsulated, that is to say, to be sealingly enclosed by the integral encapsulating structure 18 with minimal void space, preferably no void space, in between the PCBA 12 and the encapsulating structure 18. This allows the instrument cluster 10 to be formed and operated as a single element. The encapsulation is provided by an insert molding process.

In addition to serving the function of providing mechanical protection to the PCBA 12, the encapsulating structure 18 is made with light- weighted materials, for example, low density polymers or polyurethane foams for their relatively low processing temperature, light weight and flexibility. The low density polymers can be thermoplastic or thermosetting polymers. They can be non-conductive for insulating purpose. They can be optical grade polymers adaptable to tailor light transmission for decorative and functional purposes. Alternatively, they can also be opaque or reflective to allow light reflection. Preferably, the instrument cluster is made with expanded polymers such as expanded polystyrene or expanded polypropylene which are non-expensive, extremely light weight, flexible and are relatively easy and cheap to process. This allows a more user-friendly assembly, with significantly less tools or instruments required and the number of steps and procedure of assembly can be much reduced and simplified. The non-conductive nature of the encapsulating structure reduces the risk of electrostatic discharge of the PCB, and also helps improving the electromagnetic compatibility performance of the instrument cluster.

The encapsulation of the PCBA 12 by the insert molding process renders the PCBA 12 to be snugly sandwiched between and enclosed by the encapsulating structure 18, with minimal or preferably no void space in between the PCBA 12 and the encapsulating structure 18. This allows the PCBA 12 to be tightly held and located within the encapsulating structure 18 in one piece during assembly and operation. The encapsulating structure 18 is preferably impermeable to gases, moisture and dusts, to provide moisture and dust proof protection to the PCBA 12. In addition, the encapsulation may significantly help reducing the noise generated during operation as the rigid and tight enclosure of the PCBA 12 within the encapsulating structure 18 helps keeping vibrations to minimal.

The front portion 14 consists of at least one indication means, for example, a gauge 20, a digital device 22 or a lighting device (not shown). The gauges can be in the form of a speedometer, tachometer, or meter indicating fuel-level, oil pressure, oil temperature or tire pressure etc. The gauges are marked with numbers and/or graduations as indicia which can be illuminated by a lighting device. The numbers and/or graduations can also be provided in the form of recesses or protrusions which are integrally formed with the encapsulating structure 18. Alternatively, the gauge can be replaced by a digital device comprising a digital display such as a liquid crystal display (LCD). The lighting device can be any illuminating means such as a laser light source, a focused light-emitting diode (LED) light source, or other kind of light sources provided on the PCB. The lighting device not only serves the purpose of indication but also illumination of the front portion 14 of the instrument cluster 10. The front portion 14 also consists of at least one opening 24 adapted to connect at least one pointer 26 to the printed circuit board for an electromechanical movement. The pointer 26 is connectable to the motor controller 28 such as a stepper motor by means of a shaft, and is rotatable to sweep angularly across the indication means such as the gauge 20. The pointer can also be virtually formed such as by electrical means in the form of an illuminated pointer. The at least one opening may also allow adaption of the lighting device, for example, a LED light source from the PCB. Furthermore, the at least one opening 24 may also be adapted to allow operation of other components of the instrument cluster 10 by the driver such as a reset knob or switches or buttons to serve other functions. Alternatively, the front portion 14 can be covered by a mask plate 30 for decoration or other functional purposes.

The back portion 16 consists of at least one opening adapted to electrically connect the instrument cluster 10 to a vehicle. The back portion 16 may also consist of at least one fixing means adapted to fix the instrument cluster 10 to or with or within a vehicle dash board. In one embodiment the at least one fixing means can be integrally formed with the encapsulating structure 18 during the insert molding process. Alternatively, the at least one fixing means can be formed separately and is releasably engageable to the encapsulating structure 18. The fixing means can be in the form of clips, bolts, screws or by snap fittings.

The encapsulating structure 18 of the instrument cluster 10 may help minimising potential pollutions resulted from the assembling process of the PCB with an instrument cluster. Standard PCB assembling process generates by-products which can be in the form of environmental pollutants, for example, solder balls during the soldering of the PCB with the instrument cluster, or PCB dust during the milling of the PCB. The encapsulation of the PCB as embodied in the present invention simplifies the assembling process and therefore minimises the production of such pollutants. At the same time, the encapsulating structure 18 prevents any movement of the encapsulated PCB A 12 which would potentially damage the PCB A 12, create appearance issues to the instrument cluster 10, or even result in electrical shorts of the PCB. In addition, since there is minimal or no void space between the encapsulated PCBA 12 and the encapsulating structure 18, better positioning of the parts relative to the instrument cluster 10 during the assembling process is allowed, and therefore improving the precision of assembly and thus the efficiency of the process. For example, the process for inserting the pointer 26 to the PCBA 12 via the opening 24 of the instrument cluster 10 can be significantly improved when compared to the conventional construction of an instrument cluster.

Molding or printing of brand name or company label of the instrument cluster 10 can also be arranged on the back portion 16 of the encapsulating structure 18.

The encapsulating structure 18 of the instrument cluster 10 can also be molded to provide additional indentations or recesses 32, or protrusions 34 to allow adaption of the instrument cluster 10 to other components of the dash board of the automobile. In addition, the encapsulating structure 18 can be used to encapsulate any other components together with the PCBA 12.

The encapsulation of the PCBA 12 to form the automobile instrument cluster 10 in accordance with the present invention is provided by the steps of encapsulating a printed circuit board with low density polymers to form an encapsulating structure 18 by insert molding. Figure 4 shows the introduction of the PCBA 12 into a mold cavity 40. The mold cavity 40 is then injected or filled with polymer melt of a low density polymer. Upon cooling and curing of the polymer melt, the encapsulating structure 18 is formed and is releasable from the mold as the instrument cluster 10.

It should be understood that the present invention should not be limited to the application in automobile as vehicles. A person skilled in the art should understand that the present invention can be arranged in any kind of automobile such as an aircraft, a boat, a motor-bike or any other instrumentation clusters.

It should also be understood that the above only illustrates and describes examples whereby the present invention may be carried out, and that modifications and/or alterations may be made thereto without departing from the spirit of the invention. Certain features of the invention, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the invention which are, for brevity, described in the context of a single embodiment, may also be provided or separately or in any suitable subcombination.

Claims

1. A vehicle instrument cluster comprising a printed circuit board, a front portion and a back portion, wherein the front and the back portions are integrally formed to provide an encapsulating structure enclosing the printed circuit board.

2. The vehicle instrument cluster of claim 1, wherein the encapsulating structure is provided by insert molding of a low density polymer.

3. The vehicle instrument cluster of claim 1, wherein the front portion comprises at least one indication means.

4. The vehicle instrument cluster of claim 3, wherein the at least one indication means comprises a gauge.

5. The vehicle instrument cluster of claim 3, wherein the at least one indication means comprises a digital device.

6. The vehicle instrument cluster of claim 4, wherein the gauge is a speedometer.

7. The vehicle instrument cluster of claim 4, wherein the gauge is a tachometer.

8. The vehicle instrument cluster of claim 3, wherein the indication means comprises at least one lighting device.

9. The vehicle instrument cluster of claim 8, wherein the lighting device comprises a light-emitting diode

10. The vehicle instrument cluster of claim 1, wherein the front portion comprises at least one opening adapted to connect at least one pointer to the printed circuit board.

11. The vehicle instrument cluster of claim 1, wherein the back portion comprises at least one fixing means adapted to fix the instrument cluster to a vehicle dash board.

12. The vehicle instrument cluster of claim 11, wherein the at least one fixing means is integrally formed with the encapsulating structure by insert molding.

13. The vehicle instrument cluster of claim 11, wherein the at least one fixing means is releasably engageable to the encapsulating structure.

14. The vehicle instrument cluster of claim 1, wherein the back portion comprises at least one opening adapted to electrically connect the instrument cluster to a vehicle.

15. The vehicle instrument cluster of claim 2, wherein the low density polymer is an expanded polymer.

16. The vehicle instrument cluster of claim 2, wherein the low density polymer is a thermoplastic polymer.

17. The vehicle instrument cluster of claim 2, wherein the low density polymer is a thermosetting polymer.

18. The vehicle instrument cluster of claim 2, wherein the low density polymer is non-conductive.

19. The vehicle instrument cluster of claim 2, wherein the low density polymer is an optical grade polymer.

20. A method of manufacturing a vehicle instrument cluster, the method comprising the step of encapsulating a printed circuit board with a low density polymer to form an encapsulating structure by insert molding.

21. The method of claim 20 further comprising the step of providing at least one fixing means integrally formed with the encapsulating structure.

22. The method of claim 21 further comprising the step of connecting the vehicle instrument cluster to a vehicle dash board via the at least one fixing means.

23. The method of claim 20 further comprising the step of providing at least one indication means to the encapsulating structure.

24. The method of claim 20 further comprising the step of providing at least one opening to the encapsulating structure.

25. The method of claim 24 further comprising the step of connecting at least one pointer to the printed circuit board via the opening.

26. The method of claim 20, wherein the step of insert molding comprises the steps of introducing the printed circuit board into a mold cavity, injecting a polymer melt of the low density polymer into the mold cavity, cooling and curing of the polymer melt, and releasing the instrument cluster from the mold cavity.