Die cast sleeve with stability enhancement features occupying a small package space

In a preferred embodiment, the present solenoid control valve is provided which has a valve sleeve having upper and lower feedback chambers which are connected to control pressure by an exterior surface longitudinal slot or slots.

FIELD OF THE INVENTION

The present invention relates to solenoid valves, especially solenoid valves useful in controlling clutches in an automatic vehicle transmission, especially dual clutch type transmissions.

BACKGROUND OF THE INVENTION

Automatic transmission initially employed fluid logic and a torque converter to effectuate the shifting of the transmission ratios automatically without operator input. To improve fuel efficiency to the control of various clutches utilized in shifting the gears in automatic transmission in combination with solenoid valves has been modified to use an electronic controller rather than relying upon the fluid logic. In many applications, the solenoid valves utilized are proportional type valves. Often, the solenoid valves must be shut on and off at very short intervals. This can often cause the valves to be unstable in their operation. It is also desirable to provide such solenoid valves in very compact packages. To provide a solenoid valve which is proportional operated and that which has a very stable operation and which can also be provided in a small package is highly desirable.

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 solenoid control valve which has metered out flow from the supply pressure to the control pressure and metered out flow from the control pressure and metered out flow from the control pressure to the exhaust. A valve sleeve is provided which has upper and lower feedback chambers. The feedback chambers are connected with the control pressure by exterior surface longitudinal slot or slots.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring toFIGS. 1A and 1B, a normally high version of a control valve7of the present invention is presented. The control valve7has a solenoid portion10. The control valve7also has a hydraulic portion12. The hydraulic portion12has a valve sleeve14. The valve sleeve14can be fabricated from a number of suitable metals or polymeric materials, but in most instances, it is typically preferable to be fabricated from a die cast and machined aluminum. The valve sleeve14has a central spool bore16. The spool bore16has a central axis18which is co-terminus with an axis of a stem bore20. The valve sleeve14has a series of radial passages which intercept the spool bore16. Passage22is connected with a control pressure passage17in a valve housing15(FIG. 1A) encircling the valve sleeve14. The control pressure (Pc) is typically that of a clutch (not shown) in an automatic transmission. Radial inlet passage24via housing passage23connects the valve sleeve14with a pressure supply source typically provided by a hydraulic pump25. Passages26and22are juxtaposed by radial passage24. Radial passage26is connected with the control pressure via housing passage27. Radial passage26typically acts as an inlet for control pressure. Radial passage22typically acts as an outlet for control pressure. Radial outlet passage28via housing passage29is typically utilized to connect a hydraulic exhaust or sump13with the spool bore16. Adjacent to the control and exhaust pressure passages22and28, the bore16has two annular enlargements30and32.

Valve sleeve14at its extreme end has an axial opening which is plugged by a cap34which fits into an annular enlargement36. The annular enlargement36connected with an annular enlargement38. The annular enlargement36,38along with the cap34form a lower feedback chamber40. The annular enlargement38is radially intersected by a radial orifice42. The ratio of the area of the orifice42to the volume of the feedback chamber40is small enough that the feedback chamber40provides a dampening function to movement of the valve spool60.

Towards an upper end (or closer to the solenoid portion10) of the spool bore16, the valve sleeve has an annular enlargement44. The annular enlargement44forms an upper feedback chamber. The upper feedback chamber46has a radial orifice48. The orifice48is typically larger than the orifice42. The radial orifice48is fluidly connected with a longitudinal slot50that extends along an outer radial surface of the valve sleeve14. Longitudinal slot50along its outer radial edge52contacts the housing15. The longitudinal slot50fluidly connects the lower feedback chamber40with the upper feedback chamber46. The longitudinal slot50is also fluidly connected with the valve spool bore16by a radial intermediate orifice54. Intermediate orifice54is positioned between the exhaust29and the radial inlet passage24.

Slidably mounted within the valve spool bore16is valve spool60. Valve spool60has a lower landing62, a middle landing64and an upper landing66. Separating the landings62and64is a reduced diameter portion or shank68. Separating the landings66and64is a shank70which is additionally exposed to the radial orifice54. At the top of the spool60is a stem72. The spool60also has a series of balancing annular grooves73. The spool60in the configuration shown has a metered out configuration for supply pressure to control pressure and a metered out configuration for control pressure to exhaust. Movement of the valve spool60downward from the position shown inFIG. 1causes fluid adjacent the spool shank68to be metered out from the supply pressure to the control pressure and thereafter exit the control pressure outlet passage22. A top portion of the valve sleeve14spreads out into an annular yolk76. The annular yolk76is intersected by a radial side bore78. The solenoid portion10has a can or housing80. The housing80has a central top aperture82. The housing80is crimped to the yolk76of the valve sleeve and also has a side opening84to allow for a connection within an electrical connector86. Positioned within the housing80is an annular bobbin88. The bobbin88supports a coil bundle90. Inside the bobbin88is a flux tube92. The flux tube92along its upper portion has on its outer radial surface a longitudinal annular groove94. Supported on the groove94by an interference fit is an alignment tube96. The alignment tube96is typically fabricated from a non-magnetic material like brass or stainless steel. The alignment tube positions an interference fitted pole piece98. The pole piece98has an annular groove for acceptance of the alignment tube96. The pole piece98has a central multi-dimensional bore100that has its extreme end closed by a cap102. The cap102acts as a retainer for a biasing spring104. The biasing spring104biases an armature120against the valve stem72. Positioned under the flux tube92is a ferro-magnetic flux washer106. When a housing peripheral portion108is crimped to the yolk76of the valve sleeve, the yolk76is in compression with the flux washer106, flux tube92, alignment tube96, pole piece98and the top cover portion112of the housing. When the coil90is energized, the flux loop includes the pole piece98, flux tube92, and flux washer106and the housing80.

The alignment tube96precisely locates the flux tube92to the pole piece98. Slidably mounted within the flux tube92is an armature120. The armature120outside diameter is plated or coated with a hard, low-friction, non-magnetic or semi-magnetic material such as nickel phosphorous or chrome in a thickness in approximately50micron. The plating or coating later serves a dual purpose of providing a hard, low friction bearing surface and maintaining a non-magnetic (or semi-magnetic) “air-gap”. The plated or coated armature outside diameter slides directly on the flux tube92inside diameter. The clearance between the armature120OD and the flux tube92ID is minimized to thus minimize the relative eccentricity of the tube components. By minimizing the relative eccentricity, magnetic slide-loading is also minimized which in turn minimizes friction and hysteresis. At the same time the magnetic return gap is also held to a very small distance (equal to the layer thickness; approximately 50 micron) so that solenoid efficiency is maximized. A non-magnetic washer105prevents the armature120from “locking” with the pole piece98.

A diaphragm130is located between the yolk76of the valve sleeve14and the solenoid portion10to prevent contaminated oil, typically found in automatic transmission fluid, from being transferred into the solenoid portion10. Typically the diaphragm130will be shaped such that volume displacement in the solenoid portion of the solenoid valve7will be minimized regardless of the position of the valve spool60.

As mentioned previously, the solenoid valve7is biased to be normally high. Therefore, in most situations, the spring104positions the armature120to position the valve spool60so that oil surrounding the annular groove68of the valve spool is being metered out from the supply inlet passage24to the control pressure outlet22. In the normal position, fluid exiting orifice54travels through slot50and then through orifice42to pressurize the feedback chamber40. The feedback chamber40acts against the full cross-sectional surface area of the valve spool along the surface132which is greater than the surface acted upon within the upper feedback chamber46due to the diameter of the stem20. Accordingly, there is upward biasing force acting upon the spool60which keeps the spool60in contact with the armature120. In an embodiment (not shown) the biasing force can be supplemented by a spring positioned within the chamber40pushing against the valve spool60. To reverse the position of the valve, the solenoid coil90is energized causing the armature120to be attracted against the force of the biasing of spring104to be attracted to the pole piece98thereby causing the fluid about the reduced diameter portion70to be metered out to the exhaust28when the fluid from the control pressure inlet26is connected therewith. When the fluid is flowing to the exhaust, the transient flow factors act upon the valve spool60in a direction to close, thus having a stability effect.

By using two feedback chambers40and46that act opposite of one another, the total volume of oil that is pumped in and out of the feedback chambers40and46is maximized. The larger feedback chamber46has an orifice42sized to balance damping for stability and cold response of the spool valve60. The size of orifice42can be customized for a given clutch or transmission application. Typically, the orifice48between the longitudinal slot50and the larger feedback chamber46is sized greater than the orifice42between the longitudinal slot50and the lower feedback chamber40.

Referring toFIG. 2, a normally low valve107according the present invention is provided. The valve107has a valve sleeve which is essentially very similar to or identical to the previously described valve sleeve14. The valve107has a valve spool160having landings66,64and62essentially similar or identical to valves previously described in relationship to the valve spool60. The valve spool160additionally has an indent162along its lower end which provides a retainer for a biasing spring165. Additionally, the valve spool160differs from the valve spool60in that it has a stem172which is somewhat more elongated. The positions of a flux tube192and pole piece198are essentially reversed as compared with the control valve7. Actuation of the coil90of the solenoid107causes an armature220to be pulled downward cutting off the connection of the control pressure inlet26with the exhaust28and causing a connection of the supply pressure24passage with the control pressure passage22. In an embodiment (not shown) the spring226can be eliminated.

FIG. 3is a partial view of an alternative preferred embodiment307of the present invention. The embodiment307can be utilized in normally open or normally closed configurations. Slidably mounted within valve sleeve314is a valve spool360essentially similar or identical to previously described valve spool60. Longitudinal slot353of the valve spool fluidly connects control outlet26with an upper chamber46. Longitudinal slot351fluidly connects through an orifice342a lower feedback chamber340with a control passage outlet22. A cap334closes off the lower feedback chamber340.

Referring toFIG. 4, an embodiment407if the present invention is provided. Control valve407has a sleeve414having a slot457which fluidly connects the upper chamber46with an interior of the valve sleeve414via an orifice454. This arrangement allows the upper feedback chamber46to fluidly connect with the control pressure while bypassing the more adjacent exhaust outlet28in a manner similar of that of longitudinal slot52shown inFIG. 1B.