Abstract:
A Lube Regulated Pressure Regulator Valve including an internal check valve that passes transmission fluid from the hydraulic pump in an amount sufficient to fill the torque converter in the Park gear range and at low engine speeds is disclosed. The internal check valve opens at a substantially lower line pressure than is required to open the original equipment manufacture pressure regulator valve to ensure the torque converter is operational at engine startup. As engine speed increases and sufficient line pressure builds up within the torque converter charge circuit, the internal check valve is closed and the pressure regulator valve opens as it would normally to feed line pressure to the torque converter directly. When the engine is shut off, the internal check valve is biased to a closed position preventing automatic transmission fluid from draining back from the torque converter through the pressure regulator valve to the fluid sump.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the benefit under 35 U.S.C. §119(e) of U.S. Provisional Patent application No. 60/327,859 filed Oct. 5, 2001 entitled Lube Regulated Pressure Regulator Valve. 
    
    
     BACKGROUND OF INVENTION 
     The present invention relates to automatic transmission systems and, more particularly to an improved pressure regulator valve for Chrysler A518, 46RA, 46RE, A500, 40RH, 42RE, and 42RH transmission (hereinafter “Chrylster transmissions”). 
     Automatic transmission systems of the prior art have a hydraulic circuit subsystem which includes at least a hydraulic pump, a valve body having fluid conducting passages or circuits, input and exhaust ports formed within the fluid circuits, and a plurality of spool valves so-called because of their resemblance to sewing thread type spools. Such valves are comprised of cylindrical pistons having control diameters or lands formed thereon, which alternately open and close the ports to regulate the flow and pressure of automatic transmission fluid (hereinafter “ATF”) within the fluid circuits to actuate various components of the transmission. It will be understood that in describing hydraulic fluid circuits, ATF usually changes names when it passes through an orifice or control valve in a specific circuit. 
     Pumps in automatic transmission systems are generally positive displacement pumps driven by the engine of the vehicle wherein the transmission is installed. A positive displacement pump is one, which has the same output per revolution regardless of pump speed or pressure already developed in the system. Thus, it is necessary to regulate ATF pressure so it does not get too high and damage other components. A basic pressure regulator valve employs a piston and a spring that compresses at a specific pressure to allow some ATF to flow back to the pump reservoir or sump bypassing the hydraulic circuit and reducing pressure. By using a pressure regulator valve with a compression spring calibrated to a pressure lower than the pump&#39;s output, a constant ATF pressure can be maintained in the system during operation. 
     When the engine of the vehicle is turned off, ATF contained within the torque converter during operation gradually drains back to the fluid sump. At initial engine start-up this can result in an insufficient fluid level in the torque converter to operate the vehicle. Further, the original equipment manufacture (hereinafter “OEM”) pressure regulator valve does not send sufficient line pressure from the pump output circuit into the torque converter charge circuit in the Park gear range or at idle speed to refill the torque converter to permit instant operation of the vehicle with engine start-up. 
     Thus, the present invention has been developed to resolve this problem and other shortcomings of the prior art. 
     SUMMARY OF THE INVENTION 
     Accordingly, the present invention is a Lube Regulated Pressure Regulator Valve including an internal check valve that opens in the Park gear range and at low engine speeds to pass line pressure to the torque converter in response to a substantially lower hydraulic fluid pressure than is required to open the pressure regulator valve in its factory specified operating range. As engine speed increases and sufficient line pressure is built up within the torque converter charge circuit, the internal check valve is again closed and the pressure regulator valve opens as it would normally to feed line pressure to the torque converter directly. When the engine is shut off, the internal check valve is biased to a closed position preventing ATF from draining back through the valve to the fluid sump eliminating the aforementioned converter drain back problem. 
     Other features and technical advantages of the present invention will become apparent from a study of the following description and the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The novel features of the present invention are set forth in the appended claims. The invention itself, however, as well as other features and advantages thereof will be best understood by reference to the following detailed description of an illustrative embodiment when read in conjunction with the accompanying figures, wherein: 
     FIG. 1 is a partial schematic drawing of the hydraulic system in pertinent part, of the Chrysler transmission showing the location and hydraulic circuits associated with the Pressure Regulator Valve; 
     FIG. 2A is a diagrammatic view of an OEM Pressure Regulator valve labeled Prior Art and shown in a closed position within the valve body; 
     FIG. 2B is a diagrammatic view of the OEM pressure regulator valve of FIG. 2A labeled Prior Art and shown in an open position; 
     FIG. 3 is a partial sectional view of the Lube Regulated Pressure Regulator Valve of the present invention showing the components thereof; 
     FIG. 4A is an elevational view of the modified valve piston of the present invention; 
     FIG. 4B is a partial sectional view taken along the section line  4 B— 4 B of FIG. 4A showing further details of the present valve piston; 
     FIG. 5A is a diagrammatic view of the present Lube Regulated Pressure Regulator Valve in a closed position within the valve body and showing the internal check valve in a closed position; 
     FIG. 5B is a diagrammatic view of the present Lube Regulated Pressure Regulator Valve in a closed position within the valve body and showing the internal check valve in an open position; and 
     FIG. 5C is a diagrammatic view of the present Lube Regulator Pressure Regulator in an open position within the valve body and showing the internal check valve in a secondary closed position. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Prior to describing the present invention in detail it may be beneficial to review the function of a pressure regulator valve within the hydraulic system of the automatic transmission. Referring to FIG. 1 there is shown a schematic view of the relevant portion of the hydraulic system of the aforementioned Chrysler transmissions wherein the OEM pressure regulator valve, indicated generally at  200 , is illustrated. 
     The pressure regulator valve  200  is located in the valve body  201  of the transmission as shown in FIGS. 2A and 2B and functions to regulate line pressure in relation to vehicle operating conditions. In operation ATF at line pressure from the hydraulic pump  208  is delivered via pump outlet circuit  212  to the pressure regulator valve  200 . When line pressure guilds to the level of 60 to 75 pounds per square inch (psi), the OEM pressure regulator valve  200  opens routing ATF into the torque converter charge circuit as at  215 . To prevent excess line pressure, a portion of the pump&#39;s output is diverted to exhaust via the sump return circuit as at  214 . Converter charge circuit fluid is routed via switch valve  219  to both the torque converter  216 , cooler fluid circuit  217 , and into the lubrication circuit  220  (FIG. 1) depending on vehicle operating conditions. 
     As shown in FIGS. 2A and 2B, the OEM pressure regulator valve  200  comprises a spool valve including a cylindrical piston, indicated generally at  210 , having plurality of control diameters or spools  221 - 225 , a compression spring  202 , and an end plug  204  arranged coaxially within the valve body  201  shown in partial section. 
     In operation the force of the spring  202  acting on the piston  210  keeps the pressure regulator valve  200  substantially closed at low engine speed as shown in FIG.  2 A. As engine speed increases and line pressure increases, the force of spring  202  is overcome by line pressure reacting on spool  225  and the piston  210  is stroked to the position shown in FIG. 2B to open the converter charge circuit  215  to feed line pressure to the torque converter  216  and cooler fluid circuit  217  (FIG.  1 ). 
     When the engine is turned off ATF contained within the torque converter  216  during operation gradually drains back to the sump  211 . Thereafter, at initial engine start up this can result in an insufficient ATF level within the torque converter  216  to drive the vehicle because when the transmission is in Park or the engine is idling, the pressure regulator valve  200  will be nearly closed. Thus, the converter charge circuit  215 , which delivers ATF to the torque converter  216  does not receive sufficient line pressure to refill the torque converter  216  until the pressure regulator valve  200  opens at approximately 60 (psi) to send line pressure from the pump output circuit into the converter charge circuit  215 . 
     This problem is particularly evident in the Chrysler transmissions when the vehicle is not driven for a period of a few days or more and all the ATF in the torque converter  216  has drained back to the sump  211 . Thus, the present invention has been developed to provide a Lube Regulated Pressure Regulator Valve to correct this problem and will now be described. 
     Referring now to FIG. 3 there is shown therein a Lube Regulated Pressure Regulator Valve in accordance with the present invention, indicated generally at  10 , including a Lube Regulated piston, indicated generally at  25 , wherein the external configuration remains substantially unchanged from that of the OEM valve piston  210 . 
     However, in the present invention the OEM valve piston  210  has been redesigned to provide the present Lube Regulated piston  25  including an inner valve chamber  30  wherein an internal check valve, indicated generally at  50 , is installed. The internal check valve  50  functions to pass ATF at line pressure to the torque converter charge circuit  215  in the Park gear range or at engine idle speed as hereinafter explained in further detail. 
     As shown in FIG. 3 the present invention provides structures comprising bypassing means including, but not limited to, the structures shown for effectively bypassing the OEM pressure regulator when it is shut off at low engine idle speed. Such bypassing means include an internal check valve  50  comprised of a dowel pin  52 , a calibrated spring  54 , and a spring guide  56  arranged coaxially in the bore  30  and secured in place by a retaining clip  37 . 
     In one embodiment, among others, dowel pin  52  is fabricated of hardened, alloy steel to predetermined dimensions and provides a slip fit within the valve chamber  30  wherein it resides. Spring  54  has a low spring rate designed to fully open the check valve  50  at a fluid pressure in the range of 1 to 5 pounds per square inch (psi). 
     As more clearly shown in FIGS. 4A and 4B, it can be seen that valve chamber  30  includes at least two orifices  32 ,  34  formed in fluid communication therewith and extending radially outward to the exterior surface of the piston  25 . Valve chamber  30  is configured in sections of increasing diameter including a secondary bore  30   a,  a primary bore  30   b,  and a counterbore  30   c  having a retaining clip groove  35  formed therein, which receives the retaining clip  37  (FIG. 3) to secure the present internal check valve  50  in its functional position. 
     In one manufacturing method of the present invention, among others, the original equipment manufacture (OEM) pressure regulator valve piston  210  is modified to produce the present pressure regulator valve  10 . It will be appreciated by those skilled in the art that the valve chamber  30  as most clearly shown in FIGS. 4A and 4B including secondary bore  30   a,  primary bore  30   b,  counterbore  30   c,  retaining clip groove  35 , and orifices  32 ,  34  are machined into the OEM valve piston  210 . Thereafter, the dowel pin  52 , spring  54 , and spring guide  56  are arranged coaxially within the valve chamber  30  and retained in position by retaining clip  37  to complete the conversion to the present Lube Regulated Pressure Regulator Valve  10  (FIG.  3 ). 
     FIGS. 5A-5C illustrate the range of operating positions of the present Lube Regulated Pressure Regulator valve  10  including the internal check valve  50  within the valve body  201  in relation to vehicle conditions and/or engine speeds. FIG. 5A shows the present valve  10  when the vehicle engine is shut off. In this position it will be noted that the valve  10  is in a closed position within the valve body  201  and that internal check valve  50  is also in a closed position wherein dowel pin  52  is spring-biased in closing relation to the orifice  34 , which prevents ATF within the torque converter charge circuit  215  from draining back through the valve  10  to the sump. 
     FIG. 5B shows the present valve  10  at initial engine startup and/or low engine speed. In this position it will be noted that the present valve  10  is still in a closed position within the valve body  201  because line pressure has not built up sufficiently to overcome the force of OEM spring  202 , but the internal check valve  50  is in an open position and dowel pin  52  has been stroked (i.e. to the left in the drawing) against the lesser force of spring  54  permitting the flow of ATF in Park gear or at low engine speed to pass through the orifices  32 ,  34  into the torque converter charge circuit as at  215 . Thus, ATF flows to the torque converter  216  at engine idle in an amount sufficient to permit instantaneous operation of the vehicle at startup. 
     FIG. 5C shows the present valve  10  at high engine speed. In this position it will be noted that the pressure regulator valve  10  is in an open position and internal check valve  50  is shut down as orifice  34  has moved into closing relation with an adjacent land  201   a  in the valve body. At high speed some ATF is diverted to exhaust via the sump return circuit  214  to maintain line pressure in the torque converter charge circuit  215 , cooler circuit  217  and lube circuit  220  below a factory specified level for the transmission. 
     Thus, it can be seen that the present Lube Regulated Pressure Regulator Valve is a direct replacement for the OEM pressure regulator valve, which includes an internal check valve that provides increased ATF flow into the torque converter charge circuit at initial engine startup. After sufficient line pressure in built up and the present pressure regulator valve opens to feed line pressure to the torque converter charge circuit directly, the internal check valve is closed and the present valve operates in accordance with factory specifications duplicating all of the functions of the OEM valve. When the engine is shut off, the present internal check valve also prevents ATF from draining back from the torque converter through the pressure regulator valve eliminating the converter drain back problem described hereinabove. 
     Although not specifically illustrated in the drawings, it should be understood that additional equipment and structural components will be provided as necessary and that all of the components described above are arranged and supported in an appropriate fashion to form a complete and operative Lube Regulated Pressure Regulator Valve incorporating features of the present invention. 
     Moreover, although illustrative embodiments of the invention have been described, a latitude of modification, change, and substitution is intended in the foregoing disclosure, and in certain instances some features of the invention will be employed without a corresponding use of other features. Accordingly, it is appropriate that the appended claims be construed broadly and in a manner consistent with the scope of invention.