Abstract:
The configuration switch array for motor vehicle instrument panels provides for the free substitution and replacement of switches without rewiring of the instrument panel. Each switch assembly in the switch array includes a plurality of identification fingers projecting from the bottom of a switch assembly housing. The pattern and number of the identification fingers indicate the function the switch assembly is to invoke.

Description:
BACKGROUND OF THE INVENTION 
   1. Technical Field 
   The present invention relates to switch arrays for motor vehicle instrument panels and more particularly to a switch array allowing free substitution and replacement of switches without rewiring of the panel. 
   2. Description of the Problem 
   A large number of two and three position electrical switches are mounted on the instrument panel of contemporary motor vehicles, particularly heavy duty vehicles such as trucks. Typically these switches are mounted in arrays which accommodate as many as six switches. The particular functions controlled by these switches are dependent upon the options and accessories installed on a truck, which may be subject to change depending upon different uses to which the truck is put, or even depending upon the type of trailer pulled by the truck. In the past, once a switch was installed on a dash or instrument panel, it has been difficult to mount new switches, remove switches, or to change the position of switches to suit the preferences of the driver/operator due to the need to rewire the instrument panel. 
   U.S. Pat. No. 6,140,593 to Bramesfeld et al., teaches a switch array which allows two-position switches to be added to, removed from, or moved in a switch pack array. The switch array taught by Bramesfeld provided a housing having a number of bores extending from a front face of the housing through to the rear face. A resilient switch card is positioned on the rear face of the housing having contact areas aligned on the plurality of bores through the housing. Switch caps are moveably (and removably) positioned in the bores for sliding movement in the bores. One or more pins projects from each switch cap and is brought into contact with contact areas on the switch card upon depression of the switch cap. Because the arrangement of the pins is unique to particular loads, the combination of contact areas impinged upon depression of the switch cap generates a unique signal indicating the load to be activated. 
   Since depression of the switch cap is required before identification of the switch type is made, the switch array of Bramesfeld does not conveniently provide for three position switches. Nor does Bramesfeld allow identification of switches to be made when the switch is not closed. 
   SUMMARY OF THE INVENTION 
   According to the invention there is provided a configurable switch array for use in motor vehicle instrument panels. Switches are freely positionable in, movable on and removable from the instrument panel with identification of the intended functionality of the switch assembly being determined upon the positioning of the switch assembly in the switch array. Each switch assembly includes a housing. Associated with each housing are identifying indicia having a pattern uniquely associated with a particular vehicle function. A circuit board underlying the switch array housing includes indicia identifying features allowing an identifying number to be generated for the switch assembly. Typically the identifying indicia are a plurality of identification fingers projecting from the bottom of a switch assembly housing. The pattern and number of the identification fingers indicate the function the switch assembly is to invoke and impinge against identification contact areas on the circuit board upon installation of a switch assembly. 
   Additional effects, features and advantages will be apparent in the written description that follows. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The novel features believed characteristic of the invention are set forth in the appended claims. The invention itself however, as well as a preferred mode of use, further objects and advantages thereof, will best be understood by reference to the following detailed description of an illustrative embodiment when read in conjunction with the accompanying drawings, wherein: 
       FIG. 1  is a cut away perspective view of truck illustrating the location of a vehicle electronic control system; 
       FIG. 2  is a high level block diagram of the vehicle electronic control system; 
       FIG. 3  is a detailed block diagram of switch array control arrangements from the vehicle electronic control system of  FIG. 2 ; 
       FIG. 4  is a perspective view of a switch array; 
       FIG. 5  is an exploded perspective view of the switch array of  FIG. 4 ; 
       FIG. 6  is a perspective view of circuit board for the switch array; and 
       FIG. 7  is a perspective view of rocker housing for a switch from the switch array. 
       FIG. 8  is a cross sectional view of a portion of a switch and circuit board. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Referring now to the figures and in particular to  FIG. 1  there is illustrated a vehicle electrical system  10  installed on a vehicle  13 . Vehicle electrical system  10  comprises a body controller  30  which manages a number of vocational controllers distributed about vehicle  13  by communication over data transmission links. Most vehicle electrical components are directly controlled by one of a group of vocational controllers or by the body controller  30 . Included among the vocational controllers are a gauge cluster controller  14 , an engine controller  20 , and transmission controller  16 , an anti-lock brake system controller  22  and the special case of the body controller  30 . An instrument and switch bank  12  is under the control of the gauge cluster controller  14 . These vocational controllers are generally supplied by suppliers of the related components. For example, the engine controller  20  is supplied with an engine by an engine manufacturer. Control signal protocols for these controllers are both standardized and public as part of the SAE J1939 standard. The vocational controllers are linked to one another using a J1939 data link  18 . A diagnostic port  36  is provided for connection of an external diagnostic computer, which may be attached to the data link  18  as a temporary network node. 
   A second serial data bus  42 , also constructed in accordance with the SAE J1939 standard, provides for proprietary data transmission among control modules  40  installed on vehicle  13  by the vehicle&#39;s manufacturer. Control modules  40  may be provided to control any manner of specialized devices on a vehicle such as motors for water pumps on a fire fighting truck or blowers for HVAC units on busses. 
   Referring now to  FIGS. 2 and 3 , a more detailed illustration of vehicle control system  10  and the configurable switch array control circuitry is provided. In addition to the large bandwidth data links  18  and  42 , control system  10  includes a smaller bandwidth data link  52  constructed in accordance with the SAE J1708 standard over which body controller  30  communicates with one or more switch arrays  51 . Body controller  30  also provides signals to a plurality of discrete outputs  53  (including typically vehicle lamps among other devices) and receives signals from a plurality of discrete input sources  55 . As described above, data link  18  couples a plurality of vocational controllers, including a gauge controller  14 , an engine controller  20 , a transmission controller  16 , an ABS controller  22  and body controller  30 , and provides a connection point for a temporary diagnostic controller mode, e.g. diagnostic connector  36 . Customer data link  42  couples a second group of controllers  40 A-C, which are directed to vehicle specific functions, and body controller  30  which is the direct source of instructions to these controllers. Switches installed in switch arrays  51  may advantageously be used to direct body controller  30  to provide control signals to both discrete outputs  53  and to control modules  40 A-C. Switch arrays  51  may also be used to initiate control signals for transmission on data link  18 . 
   Switches in a switch array  51  are not directly connected to body controller  30 , but rather communicate with the body controller through a local switch array controller or microprocessor  32  which handles communications with the body controller over a J1708 bus  52 . Microprocessor  32  selects a particular switch location by switch location specific select signals to a multiplexor  34  which in turn couples particular switch locations in switch array  51  to microprocessor  32 . Multiplexor  34  is connected to contacts for each of the switch locations in a switch array  51  allowing both the identification code for a switch to be read as well as the switch&#39;s state (e.g. off, low, high). Microprocessor  32  determines the combination code associated with each switch present by selecting switch locations through the multiplexor  34  and transmits the combination code along with the switch state to body controller  30  which determines which control signal code to transmit on data link  18  or data link  42 , or whether to activate (or deactivate) a discrete output  53 . Body controller  30  is programmed to identify particular combination codes with particular devices or with the need to issue further instructions to yet another controller. One multiplexor  34  may be provided for each switch array  34 . 
   Microprocessor  32  is connected to a multiplexor  34  with six select lines  63 , eight identification lines  61  and three switch state lines  67 . Multiplexor  34  is connected to each switch location  51 A- 51 F in switch array  51  by eight identification lines  65  and three switch state lines  69 . Should microprocessor  32  have a large enough number of input pins, multiplexor  34  can be dispensed with. 
   Referring to  FIGS. 4 and 5 , a switch array assembly  61  implementing the invention is shown. Switch array assembly  61  comprises a housing  161  having a front face  149  in which are defined six switch assembly receptacles or receiving locations  151 A-F. Three switch locations  151 A,  151 C and  151 E are unused and the locations filled by closeout blanks  153 . Three switch locations  151 B,  151 D and  151 F are filled by rocker switch assemblies  151 B,  151 D and  151 F, respectively. Extending from the back of housing  161  are two connecting wire assemblies  145  and  147 . Appropriate resilient locking tabs as known in the art retain switch assemblies in the receptacles. 
   Switch array assembly  61  is constructed from a base housing  161  which is characterized by six switch assembly receptacles  151 A-F which pass from the front of the housing through to the back of the housing. The back of the housing is dosed by a circuit board  513  which has one face oriented toward the switch assembly receptacles  151 A-F closing the ends of the receptacles distal to front face  149 . As described below, circuit board  513  has contact points on the face oriented toward the housing and cooperating with switch assemblies for identifying the switch and determining its state. Electrical leads  145  and  147  depend from the ends of the circuit board  513 . Closeout blanks  153  are conventional, being shaped and sized to fit the receptacles and to lock into position with coming into contact with circuit board  513 . 
   A back cover  511  fits over circuit board  513  to close the back of housing  161 . Five twist lock lamps  514  may be fitted into and secured in circuit board  513  to provide illumination for the switches. Three rocker switch assemblies are illustrated, which are identical to one another except for modifications to the lead insertion end of the housings from each of which extend a plurality of identification fingers  200 . The number and pattern of identification fingers  200  indicates the function a rocker switch assembly is intended to implement. Otherwise each rocker switch assembly includes a rocker  531 , a biasing spring  529 , a push rod  527 , and an actuation cam  525 , all of which are fitted into each of the housings. As shown by a representative housing  528  in  FIG. 7 , up to eight identification fingers extend downwardly from the housing in two parallel rows of four fingers each, their position unaffected by the state of the switch of switch assembly  529 . For each functional application of a rocker switch a different combination of identification fingers  200  is removed or omitted providing a unique identifier for the function. This is illustrated in  FIG. 8  for one row of fingers  200 , where two of four fingers have been removed leaving two fingers in contact with identification area  202  on circuit board  513 . The function associated with the identification number is programmed into body controller  30 . Identification fingers  200  work by impinging against identification contact areas on circuit board  513 . It will no occur to those skilled in the art that alternative identifying indicia can be used instead of identification fingers. 
   Referring now to  FIG. 6 , circuit board  513  is shown illustrating the positioning of contact areas  202  associated with each switch location. Eight identification contact areas  202  are provided at each switch location allowing any rocker switch assembly to be located any location and still be identified. Centered in each set of eight identification contact areas  202  are sets of double switches  204  allowing determination as to which of three states a rocker switch is in. 
   The invention provides a configurable switch array in switch types can be identified without depression or closure of the switch. This allows one type of assembly for either two or three position switches and diagnostic routines to be run identifying which types of switches are present and provide readout of such to a diagnostic computer attached to the diagnostic port. 
   While the invention is shown in only one of its forms, it is not thus limited but is susceptible to various changes and modifications without departing from the spirit and scope of the invention.