Pressure balanced ports for hydraulic valves

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.

FIELD OF THE INVENTION

The present invention relates to valve arrangements, especially valve arrangements utilized in electronically controlled vehicle automatic transmissions.

BACKGROUND OF THE INVENTION

Until the late 1940's and early 1950's, virtually all automotive vehicles were provided with manually controlled transmissions. In the late 1940's and early 1950'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'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.

Referring toFIGS. 1, 2 and 3a prior art valve arrangement17is shown. In the prior art valve arrangement17, there is a spool valve19with metering cylindrical block valve head lands27and14operating within a first portion41of a valve body. The valve lands27and14are joined by a valve groove or stem13The valve body first portion41has a generally cylindrical hole43that provides a metering orifice between a first supply port opening23and a second control port opening21. To connect a first supply port opening23with a second control port opening21, the spool valve19is moved in a direction that the metering land27passes out of the cylindrical hole43and thereby enters the second control port opening21, allowing hydraulic communication from said first supply port opening23to said second control port. Fluid initially enters the second control port opening21at two shaped control edges39oriented 180 degrees from each other. As the metering land27enters further into the second control port opening21, eventually, fluid may enter along the full 360 degree perimeter of the metering land27. Fluid flowing into the second control port opening21, exits the control port at an outlet end35of the second control port opening21. In the port opening geometry of prior art, the fluid metering 180 degrees opposite of the outlet end35(towards the semi-circular blind end31) must flow all the way around the valve while fluid metering directly in front of the outlet end35has an unimpeded exit flow. The result is that at high metering flows, pressure can build up 180 degrees from the outlet end35creating 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 valve19which may lead to excessive friction and wear between the spool valve19and valve body first position41. 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

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 opening 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.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring toFIGS. 4, 5 and 6, a valving arrangement107according to the present invention is provided.FIG. 4illustrates a sector of a first portion141of a valve body108. Valve body108is 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 body108. The valve body108has a first fluid three dimensional port opening110. Typically, the port opening110is 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 body108has a second fluid three dimensional port opening112. The boundaries of the second fluid port opening are formed by the first portion of the valve body. The valve body108mounts a spool valve114. The spool valve114is axially movable along a first axis116. The spool valve114has a metering land128for metering fluid between the first fluid port opening110and the second fluid port opening112through a cylindrical hole121. To connect a first fluid port opening110with a second control port opening112, the spool valve114is moved in a direction that the metering land128enters the second fluid port opening gradually opening hydraulic communication from said first fluid port opening to said second fluid port opening. Fluid initially enters the second fluid port opening112at two shaped control edges134oriented 180 degrees from each other. As the metering land128enters further into the second fluid port opening112, eventually, fluid may enter along the full 360 degree perimeter of the metering land128.

FIG. 6is an enlargement of the spatial second fluid port opening112, formed by the first portion of the valve body. The second fluid port has two symmetrically spaced longitudinal flow plenums130. The plenums extend generally in a plane perpendicular to the first axis116of the spool valve. The plenums130are transversely connected by an elongated transverse flow chamber132, formed in the first portion of the valve body. The plenums are lateral of and laterally separated from one another by the land128of the valve spool. The transverse flow chamber132has a dimension131along the first axis which is typically less than the diameter of the plenums130. The transverse flow chamber132is connected with a generally symmetrical metering flow notch134. The plenums130extend significantly beyond the cylindrical hole121to a second fluid port opening blind end180.

The second port has a throttled end142. A distance143from the blind end140to the generally cylindrical port121is generally equal to or slightly greater than a distance145from the port121to the throttled end142. A covering plate144forms most of the throttled end having outlets146with a slightly smaller diameter than that of the plenums130. The plate144causes all the fluid (within the second fluid port opening112) to exit out of the plenums130from the second port in a common direction intersecting a common plane defined by the plate. The plenums130are 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 outlets146, fluid metering at any angular orientation of the metering edge of the land128must flow transversely to the plenums130.

With the inventive valving arrangement shown, pressure in the second fluid port opening112is much more balanced around the spool valve114as it slides within the valve body108and therefore excessive friction and wear is greatly diminished or eliminated.