PRESSURE BALANCED PORTS FOR HYDRAULIC VALVES

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

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 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

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.

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

The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein:

FIG. 1 is a top plan view of a valve body with a valving arrangement prior to the present invention;

FIG. 2 is a sectional view taken along lines 2-2 of FIG. 1;

FIG. 3 is a perspective view of a second port in the valve body shown in FIG. 1;

FIG. 4 is a valve body according to the present invention;

FIG. 5 is a sectional view taken along line 5-5 of FIG. 4; and

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

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.

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.

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.

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.

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.

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.

Claims

1. A valving arrangement including a valve body mounting a spool valve, said spool valve being movable along a first axis to fluidly connect a first fluid port of said valve body with a second fluid port of said valve body through a generally cylindrical valve port in said valve body connecting said first fluid port and said second fluid port, said valve body second fluid port having a spatial shape including: symmetrically spaced longitudinal flow plenums extending generally in a plane perpendicular to said first axis, said plenums being transversely joined by a transverse flow chamber, said second port having a blind end and a throttled end with outlet ports for said plenums.

2. A valving arrangement as described in claim 1 wherein a distance from said cylindrical valve port to said second port blind end is equal or greater than a distance from said cylindrical valve port to said second port throttled end.

3. A valving arrangement as described in claim 1 wherein said plenums have a larger dimension along said first axis than said transverse flow chamber.

4. A valving arrangement including a valve body mounting a metered out spool valve with a generally cylindrical block valve head, said spool valve being movable along a first axis to fluidly connect a first valve body fluid port with a second valve body fluid port through a generally cylindrical port in said valve body connecting said first fluid port and said second fluid port, said valve body second fluid port having a spatial shape including: symmetrically spaced apart circular cross-sectional tubular spatial plenums extending generally in a plane perpendicular to said first axis, said plenums being transversely joined by an elongated transverse flow chamber having a dimension along said first axis less than the diameter of said plenums, said transverse flow chamber being connected with generally symmetrical flow notches, said second port having a blind end and a throttled end with outlets for said plenums and wherein a distance from said blind end to said cylindrical port is equal or greater to a distance from said cylindrical port to said throttle end and where said plenums are reduced to a smaller diameter by said outlets.