Patent Publication Number: US-2019178406-A1

Title: High flow high pressure hydraulic solenoid valve for automatic transmission

Description:
BACKGROUND OF INVENTION 
     1. Field of Invention 
     The present invention relates generally to automatic transmissions and, more specifically, to a high flow high pressure hydraulic solenoid valve for an automatic transmission. 
     2. Description of the Related Art 
     Conventional vehicles known in the art typically include an engine having a rotational output that provides a rotational input into a transmission such as an automatic transmission for a powertrain system of the vehicle. The transmission changes the rotational speed and torque generated by an output of the engine through a series of predetermined gearsets to transmit power to one or more wheels of the vehicle, whereby changing between the gearsets enables the vehicle to travel at different vehicle speeds for a given engine speed. 
     In addition to changing between the gearsets, the automatic transmission is also used to modulate engagement with the engine, whereby the transmission can selectively control engagement with the engine so as to facilitate vehicle operation. By way of example, torque translation between the engine and the automatic transmission is typically interrupted while the vehicle is parked or idling, or when the transmission changes between the gearsets. In conventional automatic transmissions, modulation is achieved via a hydrodynamic device such as a hydraulic torque converter. However, modern automatic transmissions may replace the torque converter with one or more electronically and/or hydraulically actuated clutches (sometimes referred to in the art as a “dual clutch” automatic transmission). Automatic transmissions are typically controlled using hydraulic fluid, and include a pump assembly, one or more hydraulic solenoid valves, and an electronic controller. The pump assembly provides a source of fluid power to the solenoid valves which, in turn, are actuated by the controller so as to selectively direct hydraulic fluid throughout the automatic transmission to control modulation of rotational torque generated by the output of the engine. The solenoid valves are also typically used to change between the gearsets of the automatic transmission, and may also be used to control hydraulic fluid used to cool and/or lubricate various components of the transmission in operation. 
     One type of automatic transmission is known as a continuously variable transmission (CVT). In general, such transmissions take the form of two adjustable pulleys, each pulley having a sheave which is axially fixed and another sheave which is axially displaceable or movable relative to the fixed sheave. A flexible belt of metal or elastomeric material or a chain is used to intercouple the pulleys. The interior faces of the pulley sheaves are beveled or chamfered so that, as the axially displaceable sheave is moved, the distance between the sheaves and thus the effective pulley diameter is adjusted. The displaceable sheave includes a fluid-constraining chamber for receiving fluid to increase the effective pulley diameter, and when fluid is exhausted from the chamber, the pulley diameter is decreased. Generally, the effective diameter of one pulley is adjusted in one direction as the effective diameter of the second pulley is varied in the opposite direction, thereby effecting a change in the drive ratio between an input shaft coupled to an input pulley and an output shaft coupled to an output pulley. As a result, the drive ratio between the shafts is variable in a continuous, smooth manner. The solenoid valves are also typically used to actuate the pulleys of the continuously variable automatic transmission, and may also be used to control hydraulic fluid used to cool and/or lubricate various components of the transmission in operation. 
     The design or function feasibility of variable force solenoid (VFS) valves used in hydraulic controls for automatic transmissions in automotive vehicles are often constrained by the available packaging space, battery voltage, pressure range, and required flow rates. For example, there are VFS valves with medium pressure (˜20 bar) and medium flow (˜15 lpm) for transmission clutch direct acting controls, VFS valves with low pressure (&lt;10 bar) and low flow (&lt;10 lpm) for two-stage (pilot) controls, and VFS valves with high pressure (&gt;40 bar) and low flow (˜10 lpm) for clean and low viscous fluid environment. 
     In addition, these solenoid valves have a valve body disposed in a valve bore of a valve housing. The valve bore has a generally single diameter circular cross-section to receive the valve body. The valve housing has a generally rectangular flow path to the valve body and the valve body has two generally arcuate and opposed sides. The existing valve body and valve housing design do not provide large annulus flow area around a spool valve and causes excessive side-load onto the spool valve or valve member in high pressure and high flow applications, which is undesired. 
     For high-pressure, high-flow, variable force solenoids, the force balance between feedback force, magnet force, spring force, and flow force is critical. Especially with large flow forces in both axial and radial directions, the magnet force is often needed to be larger than the packaging space available in the transmission. Thus, there is a need in the art to provide a high flow high pressure hydraulic solenoid valve that is capable of flowing high flow and regulating high pressure required for controlling the pulleys of the continuously variable automatic transmission. 
     SUMMARY OF THE INVENTION 
     The present invention provides a high flow high pressure hydraulic solenoid valve for use with an automatic transmission. The high flow high pressure hydraulic solenoid valve includes a proportional solenoid and a valve body connected to and operatively associated with the solenoid. The valve body has a valve bore extending axially and at least one fluid inlet port for fluid communication with the valve bore and with a source of pressurized hydraulic fluid and at least one fluid outlet port for fluid communication with the valve bore. The high flow high pressure hydraulic solenoid valve also includes a valve member axially and slidingly disposed within the valve bore. The valve member has a plurality of valve elements spaced axially along the valve member. At least one of the valve elements have a metering face adapted to control the pressure of pressurized fluid between the at least one fluid inlet port and the at least one fluid outlet port of the valve body. The metering face includes a flow force compensating annular void to meter out fluid flow from the at least one fluid inlet port to the at least one fluid outlet port to minimize hydraulic, steady state flow forces on the valve member during high-flow conditions. 
     One advantage of the present invention is that a new high flow high pressure hydraulic solenoid valve is provided for an automatic transmission such as a continuously variable automatic transmission that is capable of flowing high flow and regulating high pressure required for controlling pulleys in the continuously variable automatic transmission. Another advantage of the present invention is that the high flow high pressure hydraulic solenoid valve directly controls pulley pressure, unlike a conventional two-stage (pilot) control system used in pulley controls. Yet another advantage of the present invention is that the high flow high pressure hydraulic solenoid valve includes a valve member such as a spool valve having at least one metering edge which includes specific geometry to minimize hydraulic, steady-state flow forces on the spool valve in high-flow conditions. Still another advantage of the present invention is that the high flow high pressure hydraulic solenoid valve has a valve body with one or more hydraulic ports each having two openings located approximately 180 degrees from each other in the valve body and where the hydraulic ports are furthermore arranged to be 90 degrees from a control module port to balance pressure on the spool valve during high-flow conditions. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Other objects, features, and advantages of the present invention will be readily appreciated as the same becomes better understood after reading the subsequent description taken in connection with the accompanying drawings wherein: 
         FIG. 1  is a schematic view of a vehicle with a powertrain system including a high flow high pressure hydraulic solenoid valve, according to the present invention; 
         FIG. 2  is a cross-sectional view of one embodiment of the high flow high pressure hydraulic solenoid valve of  FIG. 1  with a valve member in a first operational position; 
         FIG. 3  is a view similar to  FIG. 2  illustrating the high flow high pressure hydraulic solenoid valve with the valve member in a second operational position; 
         FIG. 4  is a view similar to  FIG. 2  illustrating the high flow high pressure hydraulic solenoid valve with the valve member in a third operational position; 
         FIG. 5  is a view similar to  FIG. 2  illustrating the high flow high pressure hydraulic solenoid valve with the valve member in a fourth operational position; 
         FIG. 6  is a perspective view of the valve member of the high flow high pressure hydraulic solenoid valve of  FIG. 2 ; and 
         FIG. 7  is a sectional view taken along line  7 - 7  of  FIG. 2 . 
         FIG. 8  is a cross-sectional view of the valve member having a flow force compensating shape. 
         FIG. 9  is a perspective cross-sectional view of the high flow high pressure hydraulic solenoid valve of  FIGS. 1-5 . 
         FIG. 10  is a partial perspective view of a portion of the high flow high pressure hydraulic solenoid valve of  FIG. 9 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring now to the figures, where like numerals are used to designate like structure unless otherwise indicated, a vehicle is schematically illustrated at  10  in  FIG. 1 . The vehicle  10  includes an engine  12  in rotational communication with a continuously variable automatic transmission  14  of a powertrain system. The engine  12  generates rotational torque which is selectively translated to the continuously variable automatic transmission  14  which, in turn, translates rotational torque to one or more wheels, generally indicated at  16 . To that end, a pair of continuously-variable joints  18  translates rotational torque from the continuously variable automatic transmission  14  to the wheels  16 . It should be appreciated that the continuously variable automatic transmission  14  of  FIG. 1  may be of a type employed in a conventional “transverse front wheel drive” powertrain system for the vehicle  10 . It should also be appreciated that the engine  12  and/or continuously variable automatic transmission  14  could be of any suitable type, configured in any suitable way sufficient to generate and translate rotational torque so as to drive the vehicle  10 , without departing from the scope of the present invention. 
     The continuously variable automatic transmission  14  multiplies the rotational speed and torque generated by an output of the engine  12  through a pulley assembly  22 . In one embodiment, a forward-reverse gearset  20  is disposed between the engine  12  and the pulley assembly  22 . The pulley assembly  22  includes an input or primary pulley (not shown) having a fixed sheave (not shown) and a displaceable or movable sheave (not shown), with a primary sheave servo chamber (not shown) positioned to admit and discharge fluid and thus adjust the position of movable sheave. The pulley assembly  22  also includes a secondary or output pulley (not shown) having an axially fixed sheave (not shown) and an axially displaceable or movable sheave (not shown), with a secondary sheave servo chamber (not shown) positioned to admit and discharge fluid to change the effective diameter of the pulley. The pulley assembly  22  further includes a belt or chain (not shown) intercoupling the pulleys. The output of secondary pulley is passed to a differential assembly (not shown), which passes output drive to the joints  18 , in turn, to the wheels  16  of the vehicle. It should be appreciated that this drive train, from the engine  12  to the joints  18  is completed when fluid under pressure is admitted into the starting clutch servo chamber. 
     In addition, the continuously variable automatic transmission  14  is also used to modulate engagement with the engine  12 , whereby the transmission  14  can selectively control engagement with the engine  12  so as to facilitate vehicle operation. By way of example, torque translation between the engine  12  and the continuously variable automatic transmission  14  is typically interrupted while the vehicle  10  is parked or idling, or when the transmission  14  changes between gears of the gearset  20 . In the continuously variable automatic transmission  14 , modulation of rational torque between the engine  12  and transmission  14  is achieved via a hydrodynamic device such as a hydraulic torque converter (not shown, but generally known in the art). An example of a continuously variable (automatic) transmission (CVT)  14  is disclosed in U.S. Pat. No. 4,712,453 to Haley, the disclosure of which is hereby incorporated by reference in its entirety. It should be appreciated that the continuously variable automatic transmission  14  is adapted for use with vehicles such as automotive vehicles, but could be used in connection with any suitable type of vehicle. It should also be appreciated, in some CVTs, the torque converter is replaced and used with a starting clutch. 
     Irrespective of the specific configuration of the powertrain system, the continuously variable automatic transmission  14  is typically controlled using hydraulic fluid. Specifically, the continuously variable automatic transmission  14  is cooled, lubricated, and actuated, and modulates torque using hydraulic fluid. To these ends, the continuously variable automatic transmission  14  typically includes an electronic controller  24  in electrical communication with one or more hydraulic solenoid valves  26  (see  FIG. 1 ) used to direct, control, or otherwise regulate flow of fluid throughout the transmission  14 , as described in greater detail below. In order to facilitate the flow of hydraulic fluid throughout the continuously variable automatic transmission  14 , the vehicle  10  includes at least one or more pumps, generally indicated at  28 , to supply pressurized fluid to the transmission  14 . It should be appreciated that the pump  28  provides high flow high pressure hydraulic fluid to the solenoid valves  26 . 
     Referring now to  FIG. 2 , one embodiment of a high flow high pressure hydraulic solenoid valve  26 , according to the present invention, is shown in connection with the automatic transmission  14 . The solenoid valve  26  includes a sleeve or valve body  30  disposed in a bore  31   a  of a valve housing  31   b.  The valve body  30  has a valve bore  32 . The valve bore  32  has a biasing end  34  and an actuating end  36 . The valve body  30  also includes at least one inlet  38  and at least one outlet  40  adapted to provide fluid communication with a source of pressurized hydraulic fluid and a return to the source of pressure such as the pump  28 . Specifically, the valve body  30  includes a first pressure control port  38   a,  a second pressure control port  38   b,  a pressure supply port  38   c , and an exhaust port  40   a.  The operative connections of the ports will be discussed subsequently. 
     The solenoid valve  26  also includes a valve member  42  or a spool valve (i.e., hydraulic control valve) slideably disposed within the valve bore  32  of the valve body  30 . The valve member  42  has a plurality of valve elements, generally indicated at  44 . The valve elements  44  are adapted to control the flow of pressurized hydraulic fluid between the ports of the valve body  30 . In one embodiment, the valve elements  44  are three valve elements  44   a,    44   b,  and  44   c  operatively separated by first and second areas of reduced diameter,  46  and  48 , respectively. The valve member  42  further includes a biasing end  50  and an actuating end  52 . The valve member  42  also includes a cavity  49  extending axially into the biasing end  50  and a control module port  49   a  fluidly communicating with the cavity  49  and the valve bore  32  of the valve body  30 . It should be appreciated that the valve member  42  is integral, unitary, and one-piece. It should also be appreciated that the control module port  49   a  is configured to be ninety degrees from at least one fluid port to balance pressure on the valve member  42  during high flow conditions. 
     The solenoid valve  26  further includes a biasing return spring  54  disposed in the valve bore  32  between the biasing end  50  of the valve member  42  and the biasing end  34  of the valve bore  32 . The solenoid valve  26  includes an end member  53  disposed in the biasing end  34  of the valve bore  32  and a guide pin or rod  55  extending from the end member  53  and into the cavity  49  of the valve member  42 . It should be appreciated that the end member  53  and guide rod  55  are fixed and the valve member  42  moves axially along and relative to the guide rod  55 . 
     The solenoid valve  26  also includes an electronically controlled solenoid  56  for actuating the valve member  42  to control hydraulic fluid pressure between the first control pressure port  38   a,  the second pressure control port  38   b,  the pressure supply port  38   c,  and the exhaust port  40   a.  The solenoid  56  includes a bobbin  58  and a housing  60  enclosing the bobbin  58 . The bobbin  58  has a primary electromagnetic coil  62  wound thereon to create a magnetic field when energized. The solenoid  56  also includes a terminal  64  for connecting with the electromagnetic coil  62  and to ground (not shown). It should be appreciated that the terminal  64  receives a continuous variable, digital control signal from a primary driver (not shown) such as the electronic controller  24 . 
     Accordingly, the electromagnetic coil  62  is independently controlled by respective continuous variable, digital control signals. The electronic controller  24  is connected to a pair of contacts (not shown) that is attached to the housing  60  of the solenoid  56 . When engine conditions require clutching of the transmission  14 , the electronic controller  24  inputs a control signal to the solenoid  56  via the contacts and the terminal  64 . The electronic controller  24  automatically controls actuation during automatic shifts. It should be appreciated that the electronic controller  24  could also be used for the vehicle  10  stopped on hills or the like. It should also be appreciated that the electronic controller  24  can function to sense the occurrence of a manual shift and send a signal to the solenoid  56  for actuating the solenoid valve  26 . 
     The solenoid  56  further includes an internal diameter or aperture  66  extending through the longitudinal axis of the bobbin  58 . The actuating end  36  of the valve body  30  is disposed in the channel  66 . The solenoid  56  includes an armature  68  co-axially disposed within the valve bore  32  and an actuator rod  70  is disposed through and slides co-axially with the armature  68 . The solenoid  56  further includes an armature spring  72  located at an end of the armature  68  opposite the valve member  42 . The armature spring  72  biases the armature  68  in a generally outward direction towards the valve member  42 . It should be appreciated that a fastener  74  is connectable to the armature spring  72  and allows for mechanical adjustment of the force exerted by the armature spring  72  on the armature  68 . It should also be appreciated that when the electromagnetic coil  62  is energized, the magnetic field moves the armature  68 . 
     The solenoid valve  26  of the present invention includes flow force compensation with a meter-out configuration. The transmission  14  of the present invention includes the solenoid valve  26  having a meter-out configuration that provides stability in response to transient flow forces and further includes flow force compensation that provides stable and accurate pressure regulation by overcoming the effects of the steady state flow forces, as well. 
     To achieve flow force compensation, the valve member  42  of the present invention further includes a flow force compensating shape as illustrated in  FIGS. 2 through 6 . More specifically, the valve member  42  includes at least two of the valve elements  44  having a metering face  76 . The valve element  44   a  has a metering face  76   a  adapted to control the flow of the pressurized hydraulic fluid between the first pressure control port  38   a  and the exhaust port  40   a . The valve element  44   c  has a metering face  76   c  adapted to control the flow of the pressurized hydraulic fluid between the second pressure control port  38   b  and the pressure supply port  38   c . The metering face  76   a  includes a flow force compensating annular void  78   a  and the metering face  76   c  includes a flow force compensating annular void  78   c  opposing the flow force compensating annular void  78   a.  It should be appreciated that the flow force compensating shape may be similar to that disclosed in U.S. Pat. No. 7,431,043 to Xiang et al., the disclosure of which is hereby expressly incorporated by reference. 
     In  FIG. 2 , the solenoid valve  26  is shown in a first operational position. In this position, the valve element  44   a  of the valve member  42  closes the exhaust port  40   a  and the valve element  44   c  of the valve member  42  partially opens the second pressure control port  38   b.  As illustrated in  FIG. 3 , the solenoid valve  26  is shown in a second operational position. In this position, the valve element  44   a  of the valve member  42  closes the exhaust port  40   a  and the valve element  44   c  of the valve member  42  closes the second pressure control port  38   b.  As illustrated in  FIG. 4 , the solenoid valve  26  is shown in a third operational position. In this position, the valve element  44   a  of the valve member  42  partially opens the exhaust port  40   a  and the valve element  44   c  of the valve member  42  closes the second pressure control port  38   b.  As illustrated in  FIG. 5 , the solenoid valve  26  is shown in a fourth operational position. In this position, the valve element  44   a  of the valve member  42  fully opens the exhaust port  40   a  and the valve element  44   c  of the valve member  42  closes the second pressure control port  38   b.  It should be appreciated that the hydraulic supply pressure is further communicated to the various control and actuating components such as the pulleys of the transmission  14 . It should also be appreciated that the valve member  42  is constantly moving with pressure changes and between the positions illustrated. 
     One approach relates to a valve member and port interaction that is known as a “meter-in” configuration, in which the valve member is designed to move across and meter the line pressure on its line (inlet) port with the return or suction port of the valve open and unrestricted. A meter-in configuration provides good control over the steady state flow but is generally unstable in regulating transient flow force. The other approach is known as a “meter-out” configuration. With a meter-out configuration, the valve member is designed to move across and meter the line pressure on the suction (outlet) port with the line inlet port of the valve open and unrestricted. A meter-out configuration provides good control during transient flow force conditions, but offers less stable control of the steady state flow force. It be further appreciated that flow path is a meter-out flow path whereas the inlet port  38   a  is open and the first valve element  44   a  meters the flow across the outlet port  40   a  or the inlet port  38   c  is open and the first valve element  44   a  meters the flow across the outlet port  38   b.  It should also be appreciated that the meter-out configuration is better adapted to provide good valve stability during changes in transient flow forces. 
     Referring to  FIGS. 2 and 7 , a portion of the valve body  30  and valve element  42  is shown. The valve member  42  is disposed in the valve bore  32  and axially movable along an axis. Typically, the pressure supply port  38   c  is fluidly connected with a source of pressurized hydraulic fluid to be metered out to a control pressure port  38   a,    38   b  or is a control pressure to be metered out to an exhaust pressure port  10   a.  The valve member  42  has a valve element  11  for metering fluid between the second pressure control port  38   b  and the pressure supply port  38   c.  To connect the second pressure control port  38   b  with the pressure supply port  38   c,  the valve member  42  is moved in a direction that the valve element  44   c  enters the second control pressure port  38   b  gradually opening hydraulic communication from the pressure supply port  38   c  to the second pressure control port  38   b.  It should be appreciated that fluid from the first pressure control port  38   a  flows into the control module port  49   a  and fills up the cavity  19  to create feedback to balance pressure on the valve member  42  during high flow conditions and provide stability in response to transient flow forces. 
     Referring to  FIGS. 7, 9, and 10 , an enlargement of the spatial fluid control pressure port  38   b  is shown. As illustrated, the valve body  30  has a relatively large and general “tombstone” shape. The fluid port  38   b  has two symmetrically spaced flow openings or plenums  82  in the valve body  30  oriented one hundred eighty (180) degrees from each other. The openings  82  are generally semi-circular in shape and extend generally in a plane perpendicular to an axis of the valve member  42 . Fluid initially enters the second pressure control port  38   b  at the openings  82  and contacts two shaped control edges  80  oriented one hundred eighty (180) degrees from each other. As the valve element  44   c  enters further into the second pressure control port  38   b , eventually, fluid may enter along the full 360 degree perimeter of the valve element  44   c.  It should be appreciated that the openings  82  are sized to be substantially unrestrictive to flow and therefore even at extreme flow rates, the pressure drop from one end of the opening  82  to the other is minimal. It should also be appreciated that the fluid port  38   b  is much more balanced around the valve member  42  as it slides within the valve body  30  and therefore excessive friction and wear is greatly diminished or eliminated. 
     As illustrated in  FIG. 8 , to achieve flow force compensation, the valve member  42  of the present invention further includes at least one valve element  44   a,    44   c  having a flow force compensation void, only one of which will be described in detail. The valve element  44   a  has an outer diameter  75   a  and a metering face  76   a.  The metering face  76   a  is adapted to control the flow of the pressurized hydraulic fluid between the fluid inlet port  38   a  and the fluid outlet port  40   a.  The metering face  76   a  includes a flow force compensating annular void  78   a  disposed adjacent the outer diameter  75   a  of the valve element  44   a  and defined by a lead angle “α” measured between the outer diameter  75   a  and a line intersecting the outer diameter  75   a  and tangential to the annular void  78   a . To provide an appreciable effect, the lead angle α is less than ninety (90) degrees, preferably between fifteen (15) degrees and seventy (70) degrees depending on optimization compensation of pressure versus temperature, more preferably less than forty-five (45) degrees. The metering face  76   a  has a radial thickness greater than 0.5 millimeters. It should be appreciated that it is desirable to form the metering face  76   a  as a knife edge, but to due to manufacturing processes, the metering face  76  must not be less than 0.5 millimeters. 
     It has also been found that providing any lead angle α less than 90 degrees provides some decrease in the flow force effects on the valve member  42 . However, the flow forces acting upon the valve member  42  decay monotonically with respect to the decrease in lead angle α. Therefore, the smaller the lead angle α and the deeper the annular void  78   a  in the metering face  76   a,    76   c,  the greater the reduction in flow force. It should be appreciated that manufacturing limitations and costs may impact the lead angle chosen in the production of the solenoid valve of the present invention. Specifically, while the flow forces may be completely compensated for, in theory, by providing a lead angle α as close to possible to 0 degrees, the monotonically decaying improvement in compensation provides diminishing improvements at the smaller lead angles and may prove more costly or impractical to manufacture. It should be appreciated that the lead angle α employed in the preferred embodiment will be continually reduced as manufacturing techniques and processes improve and make smaller lead angles more economically feasible. Thus, the solenoid valve of the present invention includes flow force compensation that provides high valve stability and accurate and stable fluid flow with regard to the flow force effects upon the valve member  42  during both steady state and transient regulating conditions. 
     The present invention has been described in an illustrative manner. It is to be understood that the terminology which has been used is intended to be in the nature of words of description rather than of limitation. 
     Many modifications and variations of the present invention are possible in light of the above teachings. Therefore, within the scope of the appended claims, the invention may be practiced other than as specifically described.