Abstract:
A pump-priming device configured to fit within the pump inlet circuit formed in the valve body of an automatic transmission is disclosed. The present pump priming device comprises a fluid-conducting structure having a fluid inlet and a fluid outlet, which is fabricated from sheet metal or flexible tubing and is designed to be installed within the original equipment manufacture valve body as a drop-in-place component. The present pump priming device diverts the flow of automatic transmission fluid (i.e. regulator exhaust fluid) released by the pressure regulator valve, which under normal operating conditions would flow from the pressure regulator valve back to the sump, and to redirect such flow of regulator exhaust fluid back to the pump inlet. Such redirection of regulator exhaust fluid pressurizes the pump inlet circuit and raises the output of the pump to provide adequate transmission fluid flow within the hydraulic system at low engine speeds.

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. 60/647,373 filed Jan. 27, 2005 entitled Automatic Transmission Pump Priming Device. 
    
    
     BACKGROUND OF INVENTION 
     The present invention relates to automatic transmissions for land vehicles and, more particularly, to a pump-priming device for an automatic transmission fluid pump. 
     Fluid 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 hydraulic pressure already developed in the system. Thus, it is necessary to regulate automatic transmission fluid (hereinafter “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 system pressure. By using a pressure regulator valve with a spring calibrated to a pressure lower than the pump&#39;s output, a generally constant pressure can be maintained in the hydraulic system during operation. Of course, given the continuous flow requirements of the hydraulic system, a consistent flow of ATF from the sump to the pump is critical to the proper function and lubrication of the transmission. 
     CHRYSLER automatic transmissions such as the series 727, 904, and 42 to 47RE transmissions (hereinafter “CHRYSLER transmissions”) utilized in rear wheel drive vehicles are known in the transmission repair industry to exhibit characteristic malfunctions, which are related to insufficient automatic transmission fluid (hereinafter “ATF”) flow to the pump at low engine speeds. The resulting service complaints in CHRYSLER vehicles include engine stall on transmission engagement, slow torque converter charge at engine idle, buzzing sounds from hydraulic valves, and pump noise. 
     Thus, the present invention has been developed to resolve these problems and other shortcomings of the prior art. 
     SUMMARY OF THE INVENTION 
     Accordingly, the present invention is an ATF pump priming device, which is configured to fit within the pump inlet circuit formed in the valve body of the transmission. The present pump priming device comprises an auxiliary ATF channel structure or duct fabricated from sheet metal or other suitable material such as flexible tubing, which is designed for installation within the original equipment manufacture (hereinafter “OEM”) valve body as a drop-in-place aftermarket component. 
     The present pump priming device functions to divert the flow of ATF (i.e. regulator exhaust fluid), which under normal operating conditions would flow from the pressure regulator valve back to the sump, and to redirect such flow of regulator exhaust fluid back to the pump inlet. This redirection of regulator exhaust fluid pressurizes the pump inlet circuit and raises the output of the pump to ensure adequate ATF flow to the hydraulic system at low engine speeds. 
     Thus, there has been outlined, rather broadly, the important features of the invention in order that the detailed description thereof that follows may be better understood, and in order that the present contribution to the art may be better appreciated. There are additional features of the invention that will be described hereinafter and which will form the subject matter of the claims appended hereto. 
     Those skilled in the art will appreciate that the conception upon which this disclosure is based may readily be utilized as a basis for the designing of other structures, methods, and systems for carrying out the purposes of the present invention. It is important, therefore, that the claims be regarded as including such equivalent constructions insofar as they do not depart from the spirit and scope of the present invention. 
     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 an enlarged view of a pertinent part of the hydraulic system of a CHRYSLER transmission and is labeled Prior Art; 
         FIG. 2  is a diagrammatic view of a pressure regulator valve for the CHRYSLER transmission and is labeled Prior Art; 
         FIG. 3  is a partially cutaway, plan view of a fixed displacement Gerotor type pump as installed within the pump body of a CHRYSLER transmission and is labeled Prior Art; 
         FIG. 4  is a perspective view of an embodiment of a pump priming device in accordance with the present invention; 
         FIG. 5  is a plan view of an embodiment of a blank member utilized to form the pump priming device of the present invention; 
         FIG. 6A  is a plan view of a half-section of the valve body of a CHRYSLER transmission showing the pump priming device installed in its functional position; 
         FIG. 6B  is a plan view of the valve body of  FIG. 6A  showing a separator plate installed thereon to retain the pump priming device in its functional position; 
         FIG. 7  is a perspective view of an alternative embodiment of the present pump priming device; and 
         FIG. 8  is a partially cutaway plan view of a half-section of a valve body of a CHRYSLER transmission showing the alternative embodiment of the pump priming device shown in  FIG. 7  installed in its functional position. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Prior to describing the present invention in detail it may be beneficial to briefly review the function of the pressure regulator valve and the ATF pump within the hydraulic system of the CHRYSLER transmissions. Referring to  FIG. 1  there is shown a partial schematic of the hydraulic system of the aforementioned Chrysler transmissions wherein a pressure regulator valve, indicated generally at  200 , is illustrated. The pressure regulator valve  200  is located within the valve body  201  ( FIG. 2 ) of the transmission and regulates line pressure in relation to vehicle operating conditions. In operation ATF at line pressure (i.e. 160-270 psi) from the hydraulic pump  208  enters the pressure regulator valve  200  via pump output circuit  212 . The pressure regulator valve  200  routes ATF into both the converter charge circuit  215  and the sump return circuit  214  as shown in  FIG. 1  depending on engine speed and operating conditions. 
     As seen more clearly in  FIG. 2 , the pressure regulator valve  200  comprises a spool valve including a cylindrical piston, indicated generally at  210 , having a plurality of concentric 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 view). 
     At engine idle the force of the spring  202  acting on the piston  210  keeps the pressure regulator valve  200  closed as shown in  FIG. 1  and a substantial quantity of the ATF discharged by pump  208  flows back to the sump  211 . This excess quantity is known as pressure regulator valve exhaust (i.e. regulator exhaust fluid). As engine speed increases ATF at line pressure moves the piston  210  against spring force as shown in  FIG. 2  to open the converter charge circuit  215  to feed ATF to the torque converter. Under such operating conditions an increased volume of the pump output flowing to the pressure regulator valve  200  is released into the converter charge circuit  215  and a reduced volume is diverted to the sump  211  via the sump return circuit  214  ( FIG. 1 ) depending on fluid pressure demands within the hydraulic system. 
     A positive displacement pump of the Gerotor type, indicated generally at  125  and illustrated in  FIG. 3 , is utilized in the CHRYSLER transmissions. However, other types of positive displacement pumps such as gear pumps and vane pumps may be utilized with the present invention. In the Gerotor type pump  125  as the inner rotor  128  turns each of its teeth maintains continuous line contact with a tooth of the outer rotor  129 , the point of contact shifting from the flanks of the teeth  130  at full mesh to the tops of the teeth upon rotation as indicated by the directional arrow  135 . In this way a pumping action is developed. 
     Suction port  127  and discharge port  126  are located in the pump body  140  to carry ATF into the suction side and away from the discharge side of the pump  208  respectively for delivery to the hydraulic system. Rotation of the pump  208  at engine speed generates vacuum within the suction port  127 , which draws ATF from the sump  211 . 
     Thus, the sump  211  must have sufficient ATF at all times to keep the pump  208  ready for operation (i.e. primed) in order to prevent air from being drawn into the pump. If the pump intake is exposed and air is permitted to enter the pump  208 , line pressure may drop enough to cause engine stall on transmission engagement, slow torque converter charge at engine idle, and other transmission malfunctions. 
     Thus, the present invention has been devised to resolve the aforementioned service complaints in the CHRYSLER transmissions resulting from insufficient ATF flow to the pump  208  at low engine speeds. The present invention provides structures comprising pump-priming means including, but not limited to, the following structures. Referring to  FIG. 4  there is shown an embodiment of a pump-priming device in accordance with the present invention, indicated generally at  10 . In this embodiment it can be seen that the pump priming device  10  is a channel structure configured to drop-in-place within the valve body  201  during assembly without the need for fasteners or adhesives as hereinafter explained in further detail. 
     The pump priming device  10  effectively provides a pump-priming circuit, which functions to divert regulator exhaust fluid flowing through the OEM sump return circuit  214  and route it directly back to the pump suction port  127  to keep the pump  208  primed at low operating speeds. 
     Referring to  FIG. 5  the details of the construction of the pump priming device  10  will now be described. In the embodiment shown the pump priming device  10  is fabricated from a single blank member (hereinafter “blank”), indicated generally at  25 , of a bendable material such as sheet metal or other suitable material. Blank  25  includes at one edge thereof a bottom wall section  12  connected to an adjacent longitudinal edge of a sidewall section  14  along a fold line  40 , where the blank  25  is folded 90° and connects the bottom wall section  12  to the sidewall section  14 . Fold line  40  is coincident with a cut line  50  extending inwardly from a first lateral end  25   a  of blank  25  and terminating at fold line  44  and delineating a ramp section  18 . Bottom wall section  12  also includes a triangular cutout section  45  in proximity to a second lateral end  25   b  of blank  25 . Cutout section  45  defines a 90° included angle and extends across the width of the bottom wall section  12 . The apex of the 90° included angle which defines cutout section  45  is coincident with a fold line  46 , which extends across the width of sidewall section  14 , where blank  25  is folded 90° and connects sidewall section  14  to an end wall section  19  forming an inlet end  10   a  ( FIG. 4 ) of the pump priming device  10 . 
     The opposing longitudinal edge portion of sidewall section  14  is integrally connected to an adjacent longitudinal edge of a top wall section  16  along fold line  42   a , where blank  25  is folded 90° and connects the sidewall section  14  to the top wall section  16  such that bottom and top wall sections  12 ,  16  are disposed in generally parallel relation and symmetrically disposed about a center plane -P- as seen in  FIG. 4 . 
     Top wall section  16  also includes a triangular cutout section  55  in proximity to the first lateral end  25   a  of blank  25 , which defines a 60° included angle and extends across the width of the top wall section  16 . The apex of the 60° included angle, which defines cutout section  55 , is coincident with a fold line  42   b , which extends to the first lateral end  25   a , where blank  25  is folded 180° onto itself to provide a reinforcing tab  20 , which delineates, in part, an opening  30  at the outlet end  10   b  ( FIG. 4 ) of the pump priming device  10 . 
     To complete the construction of pump priming device  10 , the ramp section  18  is integrally connected to an adjacent lateral end of bottom wall section  12 , where blank  25  is folded 30° inwardly toward the top wall section  16 . Ramp section  18  is also folded along fold line  48 , where the ramp section is folded 180° outwardly onto itself forming a flap section  18   a  further delineating opening  30  formed in the outlet end  10   b  of the priming device  10 . When so constructed, it will be appreciated that opening  30  which extends through outlet end  10   b  is oriented at a 90 degree rotated angle in relation to plane -P- as more clearly shown in  FIG. 6A . 
     In an alternative embodiment the pump-priming device is a tubular construction, indicated generally at  10 ′ and illustrated in  FIG. 7 . In this embodiment the pump priming device  10 ′ is fabricated from a bendable tubing material such as steel, aluminum, copper, heat resistant plastic or other material suitable for this purpose. The functional aspects of the pump priming device  10 ′ are the same as those described hereinabove for the pump priming device  10 . Pump priming device  10 ′ is also configured for installation within the valve body  201  ( FIG. 8 ). 
     The pump priming device  10 ′ includes a tubular body member  15 ′ having an inlet end  10   a ′ and an outlet end  10   b ′ as shown in  FIG. 7 . It can be seen that the openings defined by inlet end  10   a ′ and outlet end  10   b ′ are formed at an oblique angle -A- to a transverse plane -P′-, which extends through a longitudinal axis -X- of body member  15 ′. In a preferred embodiment angle -A- measures in the range of 20 to 40 degrees. When so constructed, both inlet end  10   a ′ and outlet end  10   b ′ define openings having a maximum cross-sectional area to increase the flow of ATF through the pump priming device  10 ′. As in the previous embodiment, it will be appreciated that opening  30 ′ which defines outlet end  10   b ′ is oriented at a 90 degree rotated angle about axis -X- relative to the plane -P′- as shown in  FIG. 7 . Further, it can be seen that a terminal segment  15   a ′ of pump priming device  10 ′ is offset at an oblique angle to axis -X- of body member  15 ′ to position outlet end  10   b ′ for delivery of fluid to the pump inlet. In a preferred embodiment axis -X′- of terminal segment  15   a ′ is offset in the range of 5 to 15 degrees to axis -X- of body member  15 ′. 
     In practical use the pump priming device  10 ,  10 ′ is installed in the valve body half-section  201  as shown in  FIGS. 6A-6B  and  FIG. 8  at a location wherein the sump return circuit  214  is accessible. In this position the pump priming device  10 ,  10 ′ is disposed in fluid communication with the pump suction port  127  and also with the regulator exhaust port  131 . More particularly, the pump priming device  10 ,  10 ′ is positioned such that the inlet end  10   a ,  10   a ′ thereof receives ATF flowing from the pressure regulator valve  200  (i.e. regulator exhaust fluid) en route to the sump via the regulator exhaust port  131  and diverts it (as shown by directional arrows  150  in  FIG. 6B ) directly back to the pump suction port  127  via outlet end  10   b ,  10   b ′ to keep the pump  208  primed at all operating speeds. It will be noted that the pump  208  continues to draw ATF from the sump  211  via suction port  127  as in normal operation. 
     The pump priming device  10 ,  10 ′ is retained in position in the valve body  201  upon installation of a separator plate  230  ( FIGS. 6A-6B ) in the standard assembly procedure for the CHRYSLER transmission. 
     The pump priming device  10 ,  10 ′ of the present invention has been demonstrated to resolve the aforementioned service complaints based on road testing of various vehicles utilizing the CHRYSLER transmissions, which have been modified by installation of the pump priming devices disclosed herein. 
     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 Automatic Transmission Pump Priming Device 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.