Abstract:
A flexible connection arrangement is provided which is useful in a pressure control device for a braking system, for example, and a pressure control device utilizing the flexible arrangement is described. The flexible connection arrangement eliminates the need of an interrupting conductor, thereby reducing the number of components required in a pressure control device and reducing manufacturing cost, complexity and the size of the device. The connection arrangement includes a flexible, elastic arm which may be integrated with a bobbin of a coil, and a lead wire terminal which may be embedded in an elastic arm and extend therefrom to directly electrically connect with a control circuit board. The flexibility of the elastic arm allows relative movement between the coil and the control circuit board without damaging the electrical connections therebetween.

Description:
TECHNICAL FIELD 
     This invention relates to a pressure control device suitable for hydraulic brake control of a motor vehicle in systems such as, anti-lock brake systems and traction control systems for example. 
     BACKGROUND OF THE INVENTION 
     Certain types of pressure control devices, such as some that are used in the automobile industry for antilock braking systems, include a plurality of solenoid valves. Each of these solenoid valves is equipped with a dome type valve body and a doughnut type coil. Each valve body is installed in a valve block which has brake fluid channels running therethrough. A cover, which protects an underlying control circuit board, is installed over the valve bodies and positioned adjacent the coils relative to the valve body. The cover is installed on the valve block, in a position such each valve body is surrounded by a corresponding coil. 
     With regard to the subassembly of the coil and valve body, a lead wire terminal extends directly above the coil and is electrically connected with the circuit board by soldering. Because the coil moves during operation, it is critical to interconnect the coil and the circuit board in a manner which will not disturb or stress the soldered electrical interconnect. To address this critical feature, it is known to provide an interrupting conductor which has some degree of flexibility so as to help present stressing of the electrical interconnect. Among the flexible components that may be included in such interrupting conductors are, e.g., bus bars, lead wires, or accordion bars, which are positioned between the coil and the control circuit board. The flexibility of the interrupting conductor helps to reduce the transmission movements of the coil to the circuit board and soldered electrical interconnect. This technology is disclosed in the Japanese Patent Application Publication Nos. 9-26773b, 9-263223, and 9-511964. 
     The conventional constructions as described above have the disadvantage that, in order to provide the desired flexibility, an additional part, such as an interrupting conductor is required, which leads to higher manufacturing and assembly costs, thereby making the component more expensive to the end user. The conventional arrangements are produced with the interrupting conductor embedded in a cover, which requires an installment tool to hold the parts during assembly. This also increases the cost of manufacturing and assembly, due to the additional tool required and the increased complexity of the assembly process. The interrupting conductor must be designed not to interfere with other components as well as be designed to be of a minimum length. One end of the interrupting conductor must be electrically connected to the lead wire terminal of the coil and the other end to the control circuit board. This, compared to a construction which directly connects the lead wire terminal of the coil to the control circuit board, this construction is considerably more complex and costly to manufacture. 
    
    
     DESCRIPTION OF THE FIGURES 
     The above and other objects and the attendant advantages of the present invention will become readily apparent by reference to the following detailed description when considered in conjunction with the accompanying drawings wherein: 
     FIG. 1 is a partial cross-sectional view of a pressure device according to the present invention; 
     FIG. 2 is an enlarged partial, cross sectional view showing an interrelationship between a solenoid valve, a circuit board, and the interconnection therebetween; 
     FIG. 3 is a cross-sectional view of FIG. 2 taken along the line III—III; and 
     FIG. 4 is a cross-sectional view of FIG. 3 taken along the line IV—IV. 
    
    
     DESCRIPTION OF THE INVENTION 
     FIG. 1 shows one example of a pressure control device. A valve block  10  is provided with channels  9  which may be opened to allow flow/pressure communication, or closed to prevent communication, by opening or closing a respective dome type valve body  21 . Valve bodies  21  extend from surface  11  of valve block. Valve bodies  21  are shown in their closed positions, and are movably downward from the positions shown to open communication. A cap cover  30  is provided to enclose the valve body arrangements. The cap cover includes side plates  31  and top board  32 . Cap cover  30  is mounted by fixing side plates  31  to the surface  11  of the valve block by, e.g., bolts, screws or the like. 
     A cushioning member  40 , which may be made of rubber or resin, or the like, for example, is placed between an inner surface of top board  32  cover  30  and the solenoid valves  20 , and particularly between the doughnut type coils  22  of the valves  20  and the top board  32 . A curb frame  33  is provided to interact with each respective coil  22 , to contain the respective coil  22  within certain radial and axial limits. A control circuit board  50  is fixed on the outer or top side of top board  32  and is electrically connected to the coils  22  as described below. An electronic circuit is printed on the control circuit board  50  and a control chip is installed on the control circuit board  50 . The control circuit board  50  is protected by an end cover  34  installed on the cover  30 . 
     A window opening  35  is provided through the top board  32  to allow electrical interconnections between the solenoid valves  20  and circuit board  50  to pass therethrough. Lead wire TERMINAL  23 , which is electrically connected to coil  22  on one side of top board  32 , passes though window hole  35  and is electrically connected to circuit board  50  on the opposite side of top board  35 . A potting material  36 , such as a soft resin, seals the window hole  35  around the lead wire terminal  23 . 
     Each coil  22  is equipped with a resin bobbin  24 , a solenoid coil  25  rolled over the bobbin  24 , and a permeable case  26 . The lead wire terminal  23  is provided at and electrically connected with each end of the solenoid coil  25 . 
     FIGS. 2 and 3 each show an enlarged partial view of a pressure control device, with particular attention paid to an electrical connection between a solenoid valve  20  and control circuit board  50 . A pair of flexible, elastic arms  27 ,  27  are integrally formed on the upper portion of bobbin  24 , and extend radially away from bobbin  24 , as shown in FIG.  2 . Alternatively, one elastic arm  27  may be formed on one bobbin  24 , and a pair of the lead wire terminals  23 ,  23  may share one elastic arm  27 . Known solenoid valves have connection terminals which extended upwardly (or axially) from the coil to be connected with the control circuit board. The present invention, with its radially extending elastic arms  27 , allows more flexibility in design positioning of the lead wire terminal  23 . That is, providing a directional elastic arm  27  (the direction, shape and length of which may be varied) many different designs and relative positioning of the components are possible, thereby allowing not only more reliable connections, but more flexibility in designing the arrangements to be compact. Thus, various designs in positioning the electrical connection between the pair of lead wire terminals  23 ,  23  and the control circuit board  50  become possible. 
     For example, in FIG. 2, the respective lead wire terminal  23 , is arranged along elastic arm  27  or is embedded in the elastic arm  27  (e.g., see FIG. 4) and further extends vertically upward from an end portion of elastic arm  27 . The lead wire terminal  23  passes through window opening  35 , as described above, and through control circuit board  50 . The end of the lead wire terminal which passes through the control circuit board  50  is soldered or welded  42  to the top side of the control circuit board  50  (e.g., see FIG.  2 ). This structure allows relative movement of the lead wire terminal  23  between the coil  20  and the control circuit board  50 , without breaking or otherwise disrupting the solder connection of the lead wire terminal to the control circuit board  50 . 
     The control circuit board  50  may have a variety of chips mounted on it, and the chips are often concentrated centrally on the board  50 , with the peripheral portion of the control circuit board  50  tending to comprise mainly dead space. Thus, it is advantageous to take advantage of the dead space by locating the lead wire terminals  23 ,  23  there and forming the solder joints on the peripheral portion. The present invention facilitates such peripheral placement of the lead wire terminals  23 , 23  thereby freeing up the central region of the control circuit board  50  for maximum usage by placement and arrangement of circuits thereon. This enables further minimization/miniaturization of the size of the control circuit board  50 . Alternatively, the flexibility provided by the designs of the present application would also allow central placement of the lead wire terminals on the control circuit board, should it be advantageous to do so, due to a particular circuit design, for example. 
     Due to the flexibility of the elastic arms  27 , movement of the solenoid valve  20  (and particularly the coil  22 ) in an axial direction can be tolerated without disrupting or breaking the electrical connection between the coil  20  and the control circuit board  50 . The elastic arms  27  provide some capacitance by bending or flexing during the axial movements of the coil, thereby reducing or eliminating stresses on the electrical connections at both ends of the lead wire  23  which would otherwise occur during such movements. The elasticity of the elastic arms enables the arms  27  to return to their normal configuration at such time that the coil returns to its starting position. In the same manner, elastic arms  27  also allow torquing (radial) or tilting motions of the coil to take place, while protecting the integrity of the electrical connections. The lead wire terminal  23  may be designed in a corrugated, or accordion folded configuration (e.g., see FIG.  3 ), to allow movements of the coil and to extend with the elastic arm  27  as it flexes, without pulling at either terminal end of the lead wire  23 , so as not to disturb the electrical connections. 
     Although the elastic arms  27  may be formed to extend straight in a radial direction away from the coils  22 , as shown in FIG. 2, it is noted that the present invention is not limited to straight configurations. For example, in addition to forming the lead wires  27  to have an accordion-folded shape, the elastic arms may be similar configured to have an accordion shape, thereby providing further capacitance or “slack” to be taken up by movements of the coil with respect to the control circuit board. In this example, the lead wires can have conforming accordion bends, allowing the lead wires  23  to be embedded in the respective elastic arms  27 , or the wires can be run externally of the elastic arms. The previous embodiments explain the case when the elastic arms  27 ,  27  are integrally formed with the bobbin  24 . However, for example, individual and separate elastic arms  27 ,  27  may be pressed fit with the bobbin  24  or may be fixed with the bobbin  24  by traditional fixing means such as adhesion and heat welding. 
     Due to the flexibility of elastic arms  27 , the present invention eliminates the need to provide an additional part, such as an interrupting conductor, which is commonly used in current pressure control devices. Because no interrupting conductor or other additional part is necessary, the direct connection of the conductor of the coil with the control circuit board allows greater ease of manufacturing pressure control devices, and a reduction in their cost. Since the elastic arm(s) may be integrally formed with the bobbin, no additional manufacturing process for the formation is necessary, thereby facilitating the manufacturing process. 
     Setting the protruding direction and length of the elastic arm allows the location of the electrical connection between the elastic arm and the control circuit board to be custom designed. Advantageously, any dead space on the control circuit board may be used to locate the lead wire terminal connection, which enables a minimized control circuit board. Since the elastic arms are multidirectionally flexible, they effectively allow the movement of the coil in any direction, while preventing stress on the electrical connection between the control circuit board and the lead wire terminal, as well as on the connection between the coil and the lead wire terminal. Even if the cover is pressed on the valve block, the movement of the coil is allowed by the lead wire terminal without transmitting the movement energy, thereby giving a higher sealing effect. 
     It should be understood that the specific form of the invention here in above described is intended to be representative only, as certain modifications within the scope of these teachings will be apparent to those skilled in the art. Accordingly, reference should be made to the following claims in determining the full scope of the invention.