Abstract:
A hydraulic manifold assembly includes a manifold containing a plurality of hydraulic channels that direct fluid to a centralized location and a package disposed at the centralized location to measure fluid pressure at pressure ports corresponding to the hydraulic channels. The manifold assembly directs fluid to the single package rather than scattering fluid outputs to multiple sensor locations, simplifying the overall assembly configuration.

Description:
TECHNICAL FIELD  
       [0001]    The present invention relates to manifolds for routing fluid, and more particularly to a manifold assembly having sensors for measuring fluid pressure in the manifold. 
       BACKGROUND OF THE INVENTION  
       [0002]    Electronically controlled solenoid operated valves provide improved shifting capabilities for the transmission compared to hydro-mechanical shift control and, in particular, permits staged or progressive release and application of clutches, such as band clutches and/or plate clutches, for effecting smoother speed changes in the transmission. In currently-known production transmissions, these valve assemblies are mounted internally on the transmission valve body and supplied with pressurized fluid from a pump disposed in the transmission. Shifting is performed using open loop control of the valves, which requires time-consuming and costly calibration of each valve in the transmission system. However, as the valves wear over time and as the viscosity of the transmission fluid changes due to age and contamination, the transmission system moves away from its initial calibration conditions, reducing the shifting performance of the transmission. 
         [0003]    Closed loop control of solenoid operated valves has been proposed as a way to obviate the need for precise calibration of the solenoid pilot and regulating valves used for clutch engagement and line pressure regulation in an automatic speed change transmission. Preferably, closed loop control includes providing a feedback signal that indicates the torque transmitted by a particular shifting clutch band or plate to the solenoid valve. U.S. Pat. No. 6,807,472 describes a system that allows closed loop control of a transmission system by using pressure sensors to sense the hydraulic pressure to each clutch actuator and provide an electrical signal to a transmission control unit (TCU) corresponding to the sensed pressure. The TCU then determines the difference between the actual sensed pressure and a target pressure corresponding to the desired output pressure to the actuators. The TCU controls the current level or the duty-cycle sent to either a linear or pulse-width-modulated (PWM) solenoid-operated valve to control the clutch regulator valve or the clutch actuator directly until the actual pressure reaches the target pressure. This closed loop feedback ensures that the shift actuators provide smooth transmission shifting operation, even with temperature changes, valve wear, and transmission fluid contamination. 
         [0004]    Piezoelectric pressure transducers are often a preferred choice in many sensing applications because of their low cost, but they pose numerous design challenges due to their non-linear response, low output signal strength, and temperature sensitivity. Thus, using piezoelectric pressure transducers requires signal amplification and correction for non-linearities. Corrections may be carried out by, for example, mixed-signal ASICs. Further, the pressure transducers must be positioned so that current can be carried from the TCU to the solenoid valves and that signals can be carried from the pressure transducers back to the TCU to effect control of valves based on the pressure transducer signals. 
         [0005]    Placing discrete, isolated, single transducers in a transmission system having a signal communication interface, such as a lead frame, stamped metal traces, flex-circuits, plated circuits, a wire harness, wireless means, etc. to carry current and signals between the TCU, solenoid valves, and transducers increases the overall complexity of the system and also exposes the transducers to current spikes from the solenoids in the valves. Because the transducers output low-level signals, the noise generated by the current spikes will create unacceptable signal errors. 
         [0006]    There is a desire for a manifold structure that incorporates low-cost pressure transducers while reducing noise sensitivity and complexity. There is also a desire for a manifold that allows pressure monitoring to be conducted at a centralized location on the manifold. 
       SUMMARY OF THE INVENTION  
       [0007]    The invention is generally directed to a hydraulic manifold assembly containing a plurality of hydraulic channels that direct fluid to a centralized location and a package disposed at the centralized location to measure fluid pressure within the hydraulic channels. In one embodiment, the package includes one or more pressure transducers and a microprocessor, microcontroller, or state-machine incorporated into a single package, making it attachable to the manifold in one step instead of requiring individual linking of each pressure transducer from a remote location to the manifold. The package may be configured to have its own ports that align with pressure ports associated with the hydraulic channels in the manifold to form fluidic paths between the manifold and the transducer. 
         [0008]    The manifold itself is designed to direct fluid to the package rather than scatter fluid outputs to multiple locations. In one embodiment, the hydraulic channels are closed by a top plate and a gasket. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0009]      FIGS. 1A and 1B  are block diagrams of a closed loop transmission control system in which a package according to one embodiment of the invention can be used; 
           [0010]      FIGS. 2A and 2B  are representative top and bottom views of a package to be used in a manifold assembly according to one embodiment of the invention; 
           [0011]      FIG. 3  is a representative top perspective view of a sub-package to be used in a package in a manifold assembly according to another embodiment of the invention; 
           [0012]      FIG. 4  is a representative top perspective view of a package incorporating the sub-package shown in  FIG. 3 . 
           [0013]      FIG. 5  is an exploded view of the manifold assembly according to one embodiment of the invention; and 
           [0014]      FIG. 6  is an assembled view of the system in  FIG. 5 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0015]      FIGS. 1A and 1B  are representative block diagrams illustrating a closed-loop pressure control system  10  for a vehicle transmission in which a manifold assembly according to the invention can be used. Note that these figures are for illustrative purposes only to describe one possible application for the inventive package and are not meant to limit the scope of the invention in any way. Those of ordinary skill in the art will understand that the inventive system may be used in other applications without departing from the scope of the invention. 
         [0016]    The system  10  may include a plurality of solenoid operated valves  12  supplied with pressurized hydraulic fluid from a pump  11 , which may be driven by a transmission input shaft Each valve  12  supplies pressurized fluid along a conduit to a hydraulic control valve  18 , and the output of each hydraulic control valve  18  is applied through a conduit to a hydraulically actuated clutch  22 , as for example, a band clutch or plate clutch, for controlling torque transmission upon a speed (gear) change. 
         [0017]    The pressure supplied to each clutch ( FIG. 1A ) or to each control valve ( FIG. 1B ) along the clutch&#39;s respective conduit  20  is sensed by a pressure transducer  24 , which provides an electrical indication of the sensed pressure, as shown by a dashed line in  FIGS. 1A and 1B , to an electronic transmission control unit (TCU)  26 . The TCU  26  also receives an input in the form of a command pressure signal from a powertrain computer  28  that is programmed to provide the desired shift characteristics for the particular vehicle and engine-transmission combination. The pressure transducers  24  may comprise any appropriate pressure sensor, such as a piezoelectric sensor. 
         [0018]    In the inventive structure, one or more pressure transducers  24  are incorporated into a unitary package  30  that can be easily incorporated into the transmission system  10  (e.g., by attachment to the TCU  26  or the manifold). Possible configurations for the package  30  itself are described in commonly assigned, co-pending U.S. patent application Ser. No. 11/235,614 entitled “Pressure Transducer Package for a Manifold,” the disclosure of which is incorporated herein by reference in its entirety. 
         [0019]      FIGS. 5 and 6  show a manifold assembly  32  incorporating the package  30  on a manifold  34 . In one embodiment, the package  30  may be manufactured separately from the manifold  34  and can be connected to the manifold  34  by a harness, lead frame, flex-circuit, or any other connector. Referring to  FIG. 5 , the manifold  34  includes a body portion  38  having a plurality of hydraulic channels,  38 . The hydraulic channels  38  are configured so that they route fluid to a central location  42  at which the package  30  is to be attached to the manifold  34 . 
         [0020]    The manifold  34  may also include a gasket  44  disposed on top of the body portion  36  to act as a seal. The gasket  44  includes a plurality of openings  46  that corresponding generally to the hydraulic channels  38  in the body portion  36 . A top plate  48  closes off the manifold  34  and is attached to the body portion  36  with a plurality of bolts  50 . The top plate  48  also includes a cluster of openings at the central location  42  to form pressure ports  52  corresponding to the hydraulic channels  38 . By routing the hydraulic channels  38  and clustering the pressure ports  52  in this manner, sensors in the package  30  can monitor the pressure in multiple channels  38  without requiring the sensors to be disposed in remote locations. 
         [0021]    In one embodiment, each pressure port  52  corresponds to one of the hydraulic channels  38 . If desired, the top plate  48  may include counterbores  54  that accept O-ring seals  55  for sealing the pressure ports  52  and form fluid-tight paths between the pressure ports  52  in the manifold  34  and corresponding pressure ports  52 a ( FIG. 2B ) in the package  30 . Note that the package  30  can be sealed against the top plate  48  using gaskets or any other component as well. 
         [0022]      FIGS. 2A through 4  show possible transducer arrangements in the package  30 . Note that invention Is not limited to these configurations and that other configurations are possible without departing from the scope of the invention. 
         [0023]      FIGS. 2A and 2B  illustrate a package  30  configuration where the package  30  includes transducers  24  that are arranged roughly in a circular or hexagonal shape on their respective substrates  61 . The transducers  24  and a processor  62  are housed in a package housing  64 . Optional dams  66  or filler material may be included in the package  30  to stabilize the transducers  24  and the processor  62  to prevent damage and protect them from corrosive environments. The package housing  30  may also include a bolt hole  74  to allow the package  30  to be attached easily to the top plate  48  of the manifold  34  with a single bolt. 
         [0024]    Because the transducers  24  and processor  70  are grouped together in a single package  30 , only a minimum number of connection lines  90  are needed to connect the transducers  24  to a TCU (not shown). This reduces the overall length of the traces between the processor  62  and the transducers  24  and reduces the total number of connections to the TCU, making the overall pressure sensing system more noise-resistant. Further, the package  30  acts as a modular component that can be easily attached to the manifold  34  to form the inventive manifold assembly  32 . 
         [0025]      FIGS. 3 and 4  illustrate another embodiment where the package  30  includes one or more sub-packages  100 .  FIG. 3  shows one embodiment of the sub-package  100 . The sub-package  100  includes two or more of the transducers  24  and its own associated sub-package lines  102  and sub-package housing  104 . As shown in  FIG. 5 , two or more of the sub-packages  100  are disposed in the package housing  64  to form the complete package  30 . The sub-package lines  102  are coupled to package traces  106 , which are in turn connected to the connection lines  90 . In the example shown in  FIG. 4 , each sub-package  100  has its own data and clock connection lines, and the two sub-packages share power and ground lines. In this example, the package housing  31  includes two bolt holes  74  for attaching the package  30  to the manifold  34 . Note that the sub-packages  100  may be calibrated before they are assembled into the package  30 . This makes it possible for different entities to manufacture the sub-package  100  and the finished package  30 . 
         [0026]    The specific package  30  configuration is not critical to the inventiveness of the manifold assembly  32 . The arrangements described above are simply illustrative examples of possible embodiments. Those of ordinary skill In the art will understand that the package can have different configurations without departing from the scope of the Invention. Further, although the above examples focus on a transmission manifold, those of ordinary skill in the art will see that the inventive system can act as a fluid pressure sensing system in any application. 
         [0027]    By incorporating one or more transducers and a processor into a single package and by configuring the manifold so that the hydraulic channels direct fluid to pressure ports at a central location, the invention provides fluid pressure monitoring and control capabilities without requiring multiple sensors at multiple locations. Instead, multiple sensors can be attached to the manifold as a single unit, reducing manufacturing costs and simplifying the overall system. 
         [0028]    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.