Abstract:
An electro-hydraulic manifold assembly including integral pressure transducers for providing real time indication of the control pressure signal output of each electrically operated valve on the manifold. The transducer dies are adhesively attached to circuit boards and the leads ultrasonically attached to pads on the ends of conductive strips on the circuit boards. Upstanding electrical connectors are attached to the circuit boards and connected to the dies which are potted over with silicone potting compound and the circuit board attached to the manifold. An electrical lead frame commonly engages the solenoid terminals and the pressure transducer terminals in bayonet style connection through slots in the lead frame.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    The present invention relates to a fluid pressure manifold equipped with electrically operated valves for selectively providing pressurized fluid to individual outlet ports on the manifold. Electrically valved manifold assemblies of this type are employed in motor vehicle automatic shifting speed change transmissions where the electrically operated solenoid type valves are controlled by an electronic computer for controlling the flow of pressurized fluid to the transmission shift actuators, such as band clutch actuators, employed in the transmission shifting operations. The electronically controlled solenoid operated valves provide improved shifting capabilities for the transmission and in particular, permit staged or progressive release and application of the band clutches for effecting smoother speed changes in the transmission.  
           [0002]    Such manifold assemblies are, in current production mounted internally on the transmission valve body and supplied with pressurized fluid from a pump disposed in the transmission.  
           [0003]    In controlling the shifting of an automatic speed change power transmission, it has been found desirable to continuously monitor the fluid pressure to the band clutch actuators and to provide such information to the electronic controller on a real time basis in order that the controller can generate control signals for the solenoid operated valves to effect the desired pressure to the shift actuator and thus provide for smoother shifting or changing of the gears.  
           [0004]    Thus, it has been desired to provide pressure sensing devices in the manifold assembly to sense the pressure supplied by each of the electrically operated valves to the fluid pressure outlet for supplying fluid pressure to the respectively associated shift actuator. Furthermore, it has been desired to provide pressure indicators for each of the outlet ports of the respective solenoid valves on such a manifold assembly and to enable electrical connection to the valves without the need for additional wiring or wiring harness connectors and to be able to mount the manifold assembly interiorly of the transmission casing.  
         BRIEF SUMMARY OF THE INVENTION  
         [0005]    The present invention provides a simple and relatively low cost technique for fabricating pressure sensor or transducer assemblies for providing real time continuous electrical signals indicative of the pressure in sensing ports provided in an electrically valved manifold assembly. The pressure sensor assemblies of the present invention are fabricated on a circuit board and applied to a common surface of the manifold and retained thereon and electrically connected to a common lead frame provided for the solenoid operated valves and potted for protection against harsh environmental exposure. The present invention thus enables the addition of pressure sensors for real time closed loop electrical control of the solenoid valves for, as for example, controlling shifting in an automatic transmission.  
           [0006]    The pressure sensor assembly of the present invention employs a die having a pressure sensitive region disposed over a sensing orifice formed in the circuit board. The die is secured to the board adhesively and is electrically connected to strips on the circuit board, preferably by weldment of the die leads to pads on the strips, and potting compound is applied over the die for retaining and protecting the die in service. The circuit board and pressure sensor assembly may then be attached to the manifold with the sensing orifices located over corresponding pressure sensing ports in a common face of the manifold. The circuit board has electrical connector terminals extending outwardly therefrom for engagement by a common lead frame assembled over the electrical terminals on the solenoid operated valves. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0007]    [0007]FIG. 1 is a perspective view of the completely assembled electro-hydraulic manifold with the pressure sensors contained therein;  
         [0008]    [0008]FIGS. 2 a  and  2   b  are an exploded view of the assembly of FIG. 1 divided along separation line I-I;  
         [0009]    [0009]FIG. 3 is a section view taken along section indicating line  3 - 3  of FIG. 1;  
         [0010]    [0010]FIG. 4 is a section view taken along section indicating lines  4 - 4  of FIG. 1; and,  
         [0011]    [0011]FIG. 5 is a plan view of the circuit board pressure sensor subassembly of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0012]    Referring to FIGS. 1, 2 a  and  2   b,  the electro-hydraulic manifold assembly is indicated generally at  10  and includes a pair of pressure sensor assemblies indicated generally at  12 ,  14  with the sensor assembly  12  having a pair of pressure sensors or transducers  16 ,  18  respectively; and, the sensor assembly  14  includes three sensors or transducers denoted  20 ,  22 ,  24  respectively.  
         [0013]    A manifold block  26  has a plurality of cavities along one side thereof denoted by reference numerals  28  through  38  with each cavity having an outlet port denoted respectively  40  through  50  which communicates with ports (not shown) on the undersurface of manifold block  26 .  
         [0014]    Manifold block  26  further includes a pair of valving cavities  52 ,  54  disposed between cavities  34  and  36 . The cavities  52 ,  54  each have a solenoid operated valve respectively  56 ,  58  received therein for providing valving to other outlet ports such as the port  60  shown in cavity  54  in FIG. 2 b.    
         [0015]    Manifold block  26  has a plurality of pressure sensing ports denoted respectively  62  through  70  which are disposed along the upper surface of the manifold block in spaced arrangement, with each of the ports  62  through  70  communicating with one of the valving cavities  28  through  38 . Each of the valving cavities  28  through  38 , has received therein a solenoid operated valve denoted respectively  72 ,  74 ,  76 ,  78 ,  80 ,  82  for individually controlling flow to the outlets  40  through  50  respectively. Valves  72 ,  74 ,  76 ,  78  are each secured in their position in the respective cavities  28  through  34  by slots  84  through  90  formed on a generally right-angle bracket  92 , which slots engage annular grooves provided in the body of each of the valves  72 ,  74 ,  76   78 . In FIG. 2 b  the grooves in the body of each of the valves  72 ,  74 ,  76 ,  78  are denoted by reference numerals  73 ,  75 ,  77 ,  79  respectively. Bracket  92  has apertures  94  through  98  formed in the horizontal surface thereof, which provide clearance for pressure sensors  20  through  24  as will be hereinafter described; and, it will be understood that bracket  92  is secured to the top surface of the manifold by suitable fasteners  100 ,  102 .  
         [0016]    Similarly a right angled bracket  104  has slots  106 ,  108  formed therein which engage annular grooves  81 ,  83  provided in the body of the valves  80 ,  82  for retaining the valves in cavities  36 ,  38  respectively. Bracket  104  is retained on the upper surface of manifold  26  by suitable fasteners  110 ,  112 . Bracket  104  has apertures  114 , 116  formed on the upper or horizontal surface thereof which provide clearance for the pressure sensors  16 ,  18  as will hereinafter be described.  
         [0017]    Each of the valves  72 ,  74 ,  76 ,  78 ,  80 ,  82  has a pair of vertically upwardly extending connector terminals denoted respectively  118  through  140 . Valves  56 ,  58  each have vertically extending connector terminals denoted respectively  142  through  148  for external connection thereto as will hereinafter be described.  
         [0018]    Referring to FIGS. 2 b,    3 ,  4  and  5 , the pressure sensor assembly  12  includes circuit board  150  having a sensing aperture  152  formed therein which is appropriately located on board  150  to communicate with the sensing port  70  (see FIG. 2 b ) in the upper surface of the manifold  26 . Circuit board  150  has sensors  16 ,  18  thereon as shown in FIG. 5, and electrically conductive strips denoted by reference numerals  154  through  164  respectively, which strips  154 ,  162 ,  164  terminate in pads for connection to the sensor  18 ; and, strips  156 ,  158 ,  160  terminate in pads for connection to the sensor  16 .  
         [0019]    A pair of upstanding connector terminals  166 ,  168  are disposed in attachment on board  150  in spaced parallel arrangement respectively on opposite sides of the sensor  16  with conductive strip  158  connected to terminal  166  and strip  154  connected to terminal  168 . Similarly, a pair of upstanding electrical connecting terminals  170 ,  172  are disposed in attachment on board  150  in spaced parallel arrangement respectively on opposite sides of the sensor  18  with terminal  170  connected to conductive strip  164  and terminal  172  connected to conductive strip  162 .  
         [0020]    It will be understood that the sensor  16  and the arrangement of connector terminals  166 ,  168  is typical of that for the sensor  18  and the sensors  20 ,  22 ,  24  mounted on a separate circuit board  174 . Board  174  is positioned with sensors  20 ,  22 ,  24  positioned over the sensing ports  62 ,  64 ,  66  respectively on the manifold; and, it will be understood that the construction of the assembly for the sensor  12  described hereinafter is representative of that of the sensor assembly  14  and sensors  20 ,  22 ,  24 . Circuit board  174  has a pair of upstanding connector terminals attached thereto and disposed in spaced parallel relationship on opposite sides of each of the sensors  20 ,  22 ,  24  respectively, which connector terminals are denoted respectively by reference numerals  176  through  186  in FIG. 2 b.    
         [0021]    Referring to FIGS. 3, 4 and  5 , sensors  16 ,  18  each include respectively a die  188 ,  190  each having a region of pressure sensitivity for varying the electrical impedance, preferably resistance, thereof and disposed respectively over the sensing orifices  152 ,  153  and secured thereover by suitable adhesive attachment, as for example, by use of epoxy material. In the presently preferred practice, the dies are preferably of the type commercially available from Sentir Semiconductor, Inc., Santa Clara, Calif. and bearing manufacturer&#39;s designation APD301 Series 5000 Ohm Medium Pressure Sensor Die. However, other types of dies may be employed which are designed to sense pressures in the same range, and have similar electrical impedance properties and are sufficiently robust to operate at temperatures of up to 140° C. while exposed to transmission fluid.  
         [0022]    Each of the dies  188 ,  190  respectively has leads extending therefrom which are attached to the pads respectively for the conductive strips  156 ,  158 ,  160  for die  188  and the pads on leads  164 ,  154 ,  162  for the leads from die  190 . In the presently preferred practice of the invention, the die leads are attached to the respective pads for the conductive strips by suitable weldment, as for example, by ultrasonic welding; however, other techniques may be employed such as soldering.  
         [0023]    After adhesive attachment to the board over the respective sensing orifices  152 ,  153  the dies  188 ,  190  and their leads are potted over with suitable resilient hydraulic fluid resisting potting material, as for example, an elastomeric material such as a fluorosilicone potting material. A retaining wall is employed around each of the dies  188 ,  190  in the form of rings  192 ,  194  respectively for retaining the fluorosilicone elastomeric potting compound over the die and attachment leads and tabs.  
         [0024]    The elastomeric potting compound disposed over the dies is denoted respectively for sensors  16  and  18  in FIGS. 3 and 4 by reference numerals  212 ,  214 .  
         [0025]    The sensor assembly  12  is retained on the manifold  26  by fasteners  196  through  202  received through apertures in the circuit board and threadedly engaging bores in the top of the manifold as shown in FIG. 2 b.  Similarly sensor assembly  14  is retained by fasteners  204  through  210  received through apertures in the board and threadedly engaging bores  174  in the top surface of the manifold.  
         [0026]    Referring to FIGS. 1, 2 a,    3  and  4 , an electrical lead frame  216  is received over the sensor assemblies and manifold and has covers  218 ,  220  formed integrally therein for covering the solenoid valves  56 ,  58  respectively.  
         [0027]    Lead frame  216  has a receptacle shell  222  formed on one end thereof which has a plurality of electrical terminals, six of which are shown and denoted by reference numerals  224  through  232 , it being understood that a second row of terminal connectors is provided therein but are not visible in the view of FIG. 2 a . The covers  218 ,  220  each have slots formed in the upper surface thereof which expose the edges of electrical strips (not shown) embedded in the lead frame and which connect to one of the terminal strips such as  224  through  232 . Cover  218  has slot  234 ,  236  which have terminals  142 ,  144  from solenoid  56  received therein as shown in FIG. 1 for making electrical connection therewith. Similarly, cover  220  has slots  238 ,  240  formed therein with electrical terminals  146 ,  148  from solenoid  58  received respectively therethrough and making electrical connection thereto.  
         [0028]    Lead frame  216  has a separate set of slots disposed in spaced pairs and denoted by reference numerals  242  through  252  and having received therein terminals  176  through  186  respectively providing electrical connection for the sensors  20 ,  22 ,  24  as shown in FIG. 1. It will be understood that slots  244  through  252  have exposed edges of conductors embedded in the lead frame  216  which are unshown in FIG. 2 a  but which are also connected to certain ones of the connector terminals such as  224  through  232 .  
         [0029]    Lead frame  216  has another set of four pairs of slots denoted by reference numerals  254  through  268  which have therein exposed edges of conductor strips (not shown) and which have received therein the connector terminals  118  through  132  respectively for the solenoids  72 ,  74 ,  76 ,  78 . Thus the slots  254  through  268  provide electrical connection through strips (not shown) in the lead frame which connect the aforesaid solenoids to certain ones of the terminals such as  224  through  232  in connector  222 .  
         [0030]    An additional set of two pairs of slots are formed in the lead frame  216  between the covers  218 ,  220  and the receptacle  222  as denoted by reference numerals  270  through  276  and which have received therein respectively connector terminals  166  through  172  for the sensors  16 ,  18 , with the connection shown in FIG. 1. It will be understood that the slots  270  through  276  have exposed therein edges of electrical strips (not shown) which are embedded in the lead frame  216  and which are connected to ones of the terminal strips in the receptacle shell  222 .  
         [0031]    An additional set of two pairs of slots are disposed between cover  220  and connector shell  222  on the lead frame  216 , which slots are denoted by reference numerals  278  through  284  and which have received therein connector terminals  134  through  140  respectively for electrically connecting to solenoids  80 ,  82 . It will be understood that slots  278  through  284  expose therein edges of electrical conductive strips (not shown) which are embedded in the lead frame  216  and which connect to ones of the terminals in receptacle shell  222 .  
         [0032]    In operation, each of the solenoid valves  56 ,  58 ,  72 ,  74 ,  76 ,  78  and  80 ,  82  are preferably of the three port pressure bleed type wherein a moveable valve member bleeds fluid pressure from the inlet to an exhaust port, thereby controlling the pressure at an intermediate pressure control port which provides the desired control pressure to the individual control pressure outlets such as ports  40  through  46 ,  48 ,  50  and  60 . The solenoids are sealed in their respective cavities by O-rings disposed about the body thereof for isolating the control pressure port from the inlet and exhaust ports in a manner well known in the art and which will not be described herein in detail. In the present practice of the invention, in one application for an electro-hydraulic manifold assembly employed in controlling the shifting of a motor vehicle automatic transmission, solenoid  56  may operate as an arming solenoid for the other solenoids  72 ,  74 ,  76 ,  78  and  80 ,  82 . In such an application, solenoid  56  may be connected to the internal passages so as to act as an on/off valve for the entire assembly. It will be understood that the supply ports for the manifold may comprise channels (not shown) formed in the undersurface of the manifold for attachment to a ported distribution plate or deck connected fluidically to the pump pressure circuit in the automatic transmission.  
         [0033]    The present invention thus provides a unique electro-hydraulic manifold having electrically operated valves for controlling the pressure supplied to individual control ports with integrally mounted pressure sensors for providing an electrical signal in real time indicative of the pressure supplied to the control port and which manifold assembly and pressure sensors are sufficiently compact and robust to be mounted within the transmission and exposed to the hydraulic fluid therein.  
         [0034]    Although the invention has hereinabove been described with respect to the illustrated embodiments, it will be understood that the invention is capable of modification and variation and is limited only by the following claims.