Abstract:
A valving arrangement is provided with a specially designed second fluid port which equalizes lateral forces induced upon a spool valve to greatly reduce or eliminate such forces and thereby virtually eliminate laterally induced ware upon the spool valve or a valve port.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to valve arrangements, especially valve arrangements utilized in electronically controlled vehicle automatic transmissions. 
       BACKGROUND OF THE INVENTION 
       [0002]    Until the late 1940&#39;s and early 1950&#39;s, virtually all automotive vehicles were provided with manually controlled transmissions. In the late 1940&#39;s and early 1950&#39;s, automatic transmissions were brought forth which utilize hydraulic logic controlled clutches and synchronizers along with a torque convertor to automatically make the gearing shifts needed when operating the vehicle. In the 1980&#39;s, many automotive transmissions were converted to being electronically controlled rather relying upon hydraulic logic controlled valves to operate the transmission to thereby provide more optimum shift points to increase vehicle mileage. With the utilization of electronic control, much of the hydraulic mechanisms controlling the transmission are operated by solenoid actuated valves. The solenoid actuated valves typically control a spool valve mounted within a valve body. The spool valve is manipulated in many applications to connect a control pressure (a port connected with a clutch or synchronizer) with a supply pressure (a port connected with a pump) or with an exhaust pressure (a port connected with a sump). Many of the solenoid valves utilized in a transmission are mounted within a common valve body. The valve body is typically a multi-passage member providing passages to and from the hydraulic supply, control and exhaust ports of a number of spool valves and solenoid valves for the control of various clutches, synchronizers or other hydraulic functions of the transmission. 
         [0003]    Referring to  FIGS. 1 ,  2  and  3  a prior art valve arrangement  17  is shown. In the prior art valve arrangement, there is a spool valve  19  with a metering land  27  operating within a valve body. To connect a first supply port  23  with a second control port  21 , the spool valve  19  is moved in a direction that the metering land enters the second control port opening hydraulic communication from said first supply port to said second control port. Fluid initially enters the second control port  21  at two shaped control edges oriented 180 degrees from each other. As the metering land  27  enters further into the second control port  21 , eventually, fluid may enter along the full 360 degree perimeter of the metering land  27 . Fluid flowing into the second control port  21 , exits the control port at an outlet end  35  of the second control port  21 . In the port geometry of prior art, the fluid metering 180 degrees opposite of the outlet end  35  must flow all the way around the valve while fluid metering directly in front of the outlet end  35  has an unimpeded exit flow. The result is that at high metering flows, pressure can build up 180 degrees from the outlet end creating and unbalance pressure profile around the valve. Although functionally the above noted design is sufficient, the pressure imbalances can impart lateral forces on the spool valve  19  which may lead to excessive friction and wear between the spool valve  19  and valve body. It is desirable to provide a valve arrangement wherein these lateral induced forces are minimized and therefore reduce or eliminate any laterally induced force wear upon the valving arrangement. 
       SUMMARY OF THE INVENTION 
       [0004]    To make manifest the above noted and other desires, a revelation of the present invention is brought forth. In a preferred embodiment, the present invention provides a valving arrangement with a specially designed second fluid port which equalizes the lateral forces induced upon the spool valve to greatly reduce or eliminate such forces and thereby virtually eliminate this laterally enforced induced wear upon the spool valve or the valve port. 
         [0005]    Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]    The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein: 
           [0007]      FIG. 1  is a top plan view of a valve body with a valving arrangement prior to the present invention; 
           [0008]      FIG. 2  is a sectional view taken along lines  2 - 2  of  FIG. 1 ; 
           [0009]      FIG. 3  is a perspective view of a second port in the valve body shown in  FIG. 1 ; 
           [0010]      FIG. 4  is a valve body according to the present invention; 
           [0011]      FIG. 5  is a sectional view taken along line  5 - 5  of  FIG. 4 ; and 
           [0012]      FIG. 6  is a perspective view of a second port according to the valving arrangement shown in the valve body of  FIG. 4 . 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0013]    The following description of the preferred embodiment(s) is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses. 
         [0014]    Referring to  FIGS. 4 ,  5  and  6 , a valving arrangement  107  according to the present invention is provided.  FIG. 4  and  FIG. 6  illustrate a portion of a valve body  108 . Valve body  108  is substantially larger than that shown having a plurality of spool valves mounted therein for controlling a plurality of clutches, synchronizers and other functions of the transmission. However, the present invention is shown in just one segment of the valve body  108 . The valve body  108  has a first fluid port  110 . Typically, the port  110  is fluidly connected with a source of pressurized hydraulic fluid to be metered out to a control pressure or is a control pressure to be metered out to an exhaust pressure. The valve body  108  has a second fluid port  112 . The valve body  108  mounts a spool valve  114 . The spool valve  114  is axially movable along a first axis  116 . The spool valve  114  has a metering land  128  for metering fluid between the first fluid port and the second fluid port. To connect a first fluid port  110  with a second control port  112 , the spool valve  114  is moved in a direction that the metering land enters the second fluid port gradually opening hydraulic communication from said first fluid port to said second fluid port. Fluid initially enters the second fluid port  112  at two shaped control edges oriented 180 degrees from each other. As the metering land  128  enters further into the second fluid port  112 , eventually, fluid may enter along the full 360 degree perimeter of the metering land  128 . 
         [0015]      FIG. 6  is an enlargement of the spatial second fluid port is  112 . The second fluid port has two symmetrically spaced longitudinal flow plenums  130 . The plenums extend generally in a plane perpendicular to the first axis  116  of the spool valve. The plenums  130  are transversely connected by an elongated transverse flow chamber  131 . The transverse flow chamber  131  has a dimension  132  along the first axis which is typically less than the diameter of the plenums  130 . The transverse flow chamber  132  is connected with a generally symmetrical metering flow notch  134 . 
         [0016]    The second port has a blind end  140  and a throttled end  142 . A distance  143  from the blind end  140  to the generally cylindrical port  121  is generally equal to or slightly greater than a distance  145  from the port  121  to the throttled end  142 . A plate  144  forms most of the throttled end having outlets  146  with a slightly smaller diameter than that of the plenums  130 . The plate  144  causes all the fluid to exit out of the plenums  130  from the second port. The plenums  130  are sized to be substantially unrestrictive to flow and therefore even at extreme flow rates, the pressure drop from one end of the plenum to the other is minimal. Because of the presence of the plate outlets  146 , fluid metering at any angular orientation of the metering edge  128  must flow transversely to the plenums  130 . 
         [0017]    With the inventive valving arrangement shown, pressure in the second fluid port  112  is much more balanced around the spool valve  121  as it slides within the valve body  108  and therefore excessive friction and wear is greatly diminished or eliminated. 
         [0018]    The description of the invention is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.