Abstract:
An apparatus and method of providing a continuous flow of discharge transmission fluid from a torque converter to a cooler of a vehicle transmission such that oil flow to the cooler begins at engine start up and wherein the apparatus includes a safety bypass valve that directs discharge from the torque converter directly to a lube circuit other, than the cooler circuit, in the event pressure within the cooler circuit rises above a predetermine pressure due to a gelling of lubricant oil or other clogging of the cooler circuit.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention is directed to the field of vehicle transmissions and more particularly to an apparatus and method of providing a continuous flow of discharge transmission fluid from a torque converter to a cooler of the transmission such that oil flow to the cooler begins at engine start up and wherein the apparatus includes a safety bypass valve that directs discharge from the torque converter directly to a lube circuit other than the cooler circuit in the event pressure within the cooler circuit rises above a predetermine pressure due to a gelling of lubricant oil or other clogging of the cooler circuit. 
     2. Brief Description of the Related Art 
     In some models of vehicles, lubricant oil flow through an automatic transmission is controlled such that, until a temperature of the oil or transmission fluid reaches a predetermined temperature after vehicle start up, the oil is allowed to bypass a cooler circuit associated with the automatic transmission. By way of example, transmissions of the Ford® 5R55 series such as the W, S and N models, are provided with a cooler bypass valve controlled by a thermostatic switch as original operating equipment. Such a thermostatically controlled valve is a directional flow control valve having a valve body that moves so as to either prevent or allow flow of oil from a transmission torque converter to the cooler circuit. Essentially, the thermostatic switch includes a piston which shifts the valve from a first position, to block flow to the cooler circuit when the temperature of the oil is below a predetermine temperature so that all oil is directed to a lube circuit of the transmission, to a second position when the oil temperature is above the predetermined temperature so that the oil is directed toward the cooler circuit. At low temperatures, the bypass valve is urged by a spring to close an outlet to prevent flow to the cooler circuit, however, as the temperature rises to approximately 160° F., the thermostat urges the valve against the spring pressure such that heated oil is directed to the cooler circuit. 
     It has been determined that the thermostatic bypass valve assembly may fail to operate to open the bypass valve until temperatures of the transmission fluid or oil become damagingly high causing failure or lock up of the gears of the transmission. In the event of failure of the bypass valve to open in a proper manner, the overdrive sun and planet gears are normally the first gears to be adversely effected as they generally receive the least amount of oil flow during engine operation. 
     In addition to the foregoing, under normal operating conditions, the Ford® transmissions identified above are designed to provide maximum flow of approximately 0.7 gallons of lubricant in 20 seconds to the cooling circuit when the bypass valve is opened to direct flow to the cooling circuit. As only a small amount of the cooled lubricant is directed to the overdrive planetary gears, any overheating caused by failure of the cooler bypass valve or a delay in opening of the cooler bypass valve to the cooler circuit will have a generally immediate effect on such gears. 
     In view of the foregoing, there is a need to prevent potential damage that may be caused to vehicle transmissions due to failure or faulty operation of thermostatically controlled bypass valves. There is also a need to increase the quantity of lubrication fluid flow to the overdrive sun and planetary gears to ensure that such gears are not easily damaged upon heat build up. 
     SUMMARY OF THE INVENTION 
     The present invention is directed to a continuous cooler flow and safety bypass valve system that replaces thermostatically controlled cooler circuit bypass valves associated with vehicle transmissions such as the Ford® 5R55 transmissions including the W, S and N models. The safety bypass valve system includes a stationary sleeve having first and second end portions separated by a intermediate of central portion. The sleeve includes at least one open flow channel for continuously supplying oil or transmission fluid being discharged from the torque converter to the transmission cooler circuit so that the cooler circuit is not bypassed at low operating temperatures, as is the case with the conventional transmissions. In addition, the first end portion includes a valve chamber in which a safety blow-off valve is reciprocally movable relative to a flow passage opening in the intermediate portion of the sleeve. The safety valve is normally biased to close the flow passage opening to prevent flow into the valve chamber. The sleeve also includes at least one and preferably a plurality inlet openings for communication fluid with the flow passage opening. Upon build up of pressure within the inlet openings, the safety valve is forced open allowing flow into the valve chamber. The fluid within the valve chamber is exhaust through discharge of openings in the sleeve by way of which oil being discharged from the converter clutch is directed to the lube circuit in the event the liquid in the cooler circuit gels under extremely low ambient temperatures or the cooler circuit otherwise becomes partially or totally blocked. 
     In the preferred embodiment, the at least one inlet opening and the at least one discharge opening are separated by a land that blocks direct communication between the inlet and outlet. Further, the inlet and outlet openings may be made in the intermediate portion of the sleeve. The safety blow-off valve may be in the form of a cylindrical piston or ball valve which is continuously urged by a spring or other resilient member to a closed position to block flow to a lube circuit under normal operating conditions. However, should pressure within the converter out/cooler circuit rise above a predetermined level, such as 60 psi, the bypass valve will be forced against the resilient member to open flow from the torque converter directly to the lube circuit of the transmission. 
     In the embodiments shown, the fluid inlets and discharge outlets are formed with annual flow passage recesses formed in spaced relation with one another and preferably within the intermediate portion of the sleeve. 
     To further facilitate the operation of the transmission using the cooler circuit valve system of the invention, it is recommended that other components of the transmission be altered. Such alterations or modifications to the transmission include removal of the conventional dump ball valve to provide increased and parallel lubricant flow to the three lube circuits of the transmission including the rear, center and front lube circuits which will result in up to a 300% increase in lubricant flow to the cooler circuit. In addition, an orifice in the converter control valve which normally supplies converter discharge lubricant to a converter back pressure valve should be plugged so as to maintain pressure and flow within the lube circuits. 
     Another modification to the transmission that should be made upon installation of the valve system of the present invention is to enlarge a front lube cup orifice in a pump stator of the transmission in order to increase lubricant flow through the pump. Also, drilling holes in the overdrive sun gear drive plate to direct lubricant flow directly to the overdrive planetary carrier will facilitate the supply of lubricant to the overdrive planetary gears so as to prevent burn out damage to the planetary gears which are the most susceptible to damage when temperatures within the lube circuits increase to an above normal operating temperature due to valve or other components failures within the transmission. 
     It is the primary object of the present invention to overcome the problems associated with lockup or other damage to components and gears within a transmission and especially the overdrive sun and planet gears of transmissions due to failure of thermostatically controlled converter/cooler circuit flow valves by providing a valve system which replaces the thermostatic element and valve member of such valves with a combination stationary sleeve and cooler circuit bypass valve which functions to normally provide a continuous flow of converter discharge lubricant to the cooler circuit even at start up low temperatures but which will automatically open to bypass the discharge flow directly to the lube circuits of the transmission in the event liquid in the cooler circuit thickens or gels due to extremely low ambient temperatures or otherwise becomes blocked. 
     It is another object of the present invention to increase lubricant supply to the sun and planet gears within a vehicle transmission by modifying components of the transmission and specifically providing holes in the overdrive sun gear drive plate to direct lubricant flow directly to the planetary carrier and to enlarge the front lube cup orifice in the pump stator to increase front lube circuit flow. 
     It is also an object of the invention to maximize flow within the three lubrication circuits of the transmission by removing the conventional dump ball valve and blocking an orifice in the converter control valve which normally supplies converter discharge lubricant to a converter clutch back pressure valve which flow is normally necessary to maintain pressures in the lube circuit above zero when the conventional thermostatically controlled valve opens to the cooler circuit by which is no longer necessary with the continuous flow to the cooler circuit of the present invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A better understanding of the invention will be had with reference to the accompanying drawings wherein: 
         FIG. 1  is a flow diagram showing a torque converter, thermostatically controlled bypass valve assembly and cooler circuit of a conventional Ford® 5R55 transmission showing transmission fluid flow prior to opening of flow between the torque converter to the cooler circuit; 
         FIG. 2  is a flow diagram similar to  FIG. 1  showing transmission fluid flow to the cooler circuit from the torque converter upon opening of the bypass valve; 
         FIG. 3  is a flow diagram showing generally continuous transmission fluid flow between the torque converter and the cooler circuit through a continuous feed sleeve when a safety bypass valve associated with the sleeve is closed in accordance with the teachings of the present invention; 
         FIG. 4  is an enlarged top plan view of one embodiment of continuous flow directing stationary sleeve and safety bypass valve of the present invention having an end plug removed; 
         FIG. 5  is a top plan view of an end plug of the stationary sleeve of  FIG. 4 ; 
         FIG. 6  is a fluid circuit including a top plan view having portions broken away of the stationary sleeve and safely bypass valve with the valve being open to direct discharge toward the rear lube circuit when pressures within the cooler circuit rise above a predetermined level; 
         FIG. 7  is a cross section taken through the safety valve shown in  FIGS. 3 and 6 ; 
         FIG. 8  is an enlarged front perspective view of a front lube orifice in a cup plug of the inside of a pump stator of the transmission of  FIG. 1 ; and 
         FIG. 9  is a top view showing a plurality of holes made in the overdrive direct drum to planetary sun gear drive plate to promote lubricant flow to the planetary carrier. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     With particular reference to  FIGS. 1 and 2 , portions of the fluid circuit diagrams of a conventional Ford® 5R55 series transmission are shown. These portions show a main regulator valve section  7 , a torque converter and converter control valve section  8  and a cooler/filter section  9 . The main regulator valve section includes a main regulator bypass valve  10  which discharges to a bypass  11  to a rear lube circuit  12  including a sump  13 . The sump  13  is also connected to receive lubricant cooling oil, or transmission fluid, through a one way ball check valve  14  from a fluid line or channel  15  that connects to an outlet  16  of a thermostatically operated cooler bypass valve  17  of a converter control valve assembly  18  and to the transmission center and front lube circuits  19  and  20  which are connected to supply another sump  21 . Transmission fluid from the sump  21  is drawn through a filter  22  and forwarded by a pump  23  to a flow control valve  24  to the center and front lube transmission circuits. The converter control valve assembly  18  controls flow of transmission fluid to and from a transmission torque converter  25  through channels  26  and  27 . At low transmission fluid operating temperatures below approximately 160° F., the discharge from the converter  25  is directed through the control valve assembly  18  to channels  28  and  29  to the thermostatic cooler bypass valve  17  where the fluid exits outlet  16  and flows into channel  15  toward the rear sump  13  and/or the center and front lube circuits  19  and  20 . However, as the temperature of the transmission fluid rises above approximately 160° F., a piston  30  of a thermostat  32  of the cooler bypass valve assembly, see  FIG. 2 , extends outwardly and urges valve  17  to a second position so as to block flow to the discharge  16  of the valve and instead directs fluid discharging from the converter to a cooler  34 . Discharge from the torque converter  25  is thus discharged to an inlet of the converter control valve  18  through line  26  and then from an outlet of the converter control valve to line  33  and channel or line  35 . It should be noted that the one way ball check valve  14  is provided to permit fluid flow from the thermostatic cooler bypass valve  17  to the rear lube circuit but prevent flow from the exhaust from the main regulator valve  10  toward the thermostatic cooler bypass valve  17 . 
     As set forth above with respect to the conventional thermostatic bypass valve assemblies, often the thermostat element fails to operate until the transmission fluid heats up to as much as 300° F. which can result in damage throughout the transmission and especially to the overdrive sun and planet gears thereby locking up the transmission. Thus there is a need to replace such conventional thermostatic valves. 
     With specific reference to  FIGS. 3 to 7 , a continuous cooler sleeve and safety bypass flow valve assembly  36  of the present invention is shown and its operating characteristics are set forth herein. In accordance with the invention and as shown in  FIG. 3 , the continuous cooler sleeve and safety bypass valve assembly  36  replaces the thermostat  32  and cooler bypass valve  17  and thus is compatible in size and dimension to seat within the fluid circuit of the transmission in place of the conventional bypass valve  17  and thermostat  32 . The continuous cooler sleeve and safety bypass flow control valve  36  is structured to connect or communicate the discharge side of the torque converter  25  at all times with the cooler  34  such that transmission fluid is conducted to the cooler even at low operating temperatures below 160° F. The continuous cooler feed circuit is shown in  FIG. 3  wherein no flow is directed to the discharge circuit  16  to line  15  communicating with the rear lube circuit. The flow through the cooler sleeve and safety bypass valve assembly  36  will always be as shown in  FIG. 3  unless pressures within the fluid circuit increase above a predetermined pressure due to gelling of the transmission fluid at extremely low ambient temperatures or due to some other problem in the cooler circuit. If the pressure does rise, a safety pass valve associated with the cooler sleeve and safety bypass valve assembly will open to direct fluid flow to the rear lube circuit through discharge line  16 , as is shown in  FIG. 6 . 
     With reference to  FIGS. 4 ,  5  and  7 , the continuous cooler sleeve and safety bypass valve assembly  36  include a generally cylindrical stationary sleeve including first and second portions  37  and  38  which extend from a central portion  39  including a recessed annular fluid inlet  40  and a recessed annular fluid outlet  41  which are separated by an outwardly extending land or annular flange  42 . Sleeve portion  37  is hollow defining a valve chamber  43  in which a safety bypass valve  44  is seated. The bypass valve is shown as being a hollow cylindrical valve, see  FIG. 7 , which is closed at one end from which a central post  45  extends toward the central portion of the assembly. The open end of the sleeve portion  37  partially closed by a plug member  46  shown in  FIG. 5 . The plug member has a through opening  47  formed there through to allow fluid pressures to be adjusted within the valve chamber  43 . The plug  46  includes two spaced outwardly extending annular flanges  48  and  49  having a recessed annular groove  50  formed there between. After the safety bypass valve  44  is placed within the valve chamber, a spring, such as coil spring  51  is placed within the chamber to continuously urge the safety bypass valve  44  toward a closed position wherein the post  45  seats within and closes a central opening  53  formed through the central portion of assembly  36 . With the spring in place, the plug  46  is sealed such that land  49  is mounted within the hollow portion of the first portion of the continuous cooler sleeve and safety bypass valve assembly  36 . The recessed annular groove  50  is designed to receive a u-shaped locking spring, not shown, for securing the valve assembly  36  within a transmission housing. 
     The annular fluid inlet  40  has at least one and preferably a plurality of spaced openings  55  therein through which transmission fluid may flow through the opening  53  in the central portion of the assembly  36  and into the safety valve chamber  43  when pressure exceeds a predetermined pressure in the cooler fluid circuit. The reduced diameter fluid inlet  40  forms a continuously open fluid flow path  56  by way of which discharge fluid from the torque converter  25  flows to the channels  33  and  35 , see  FIG. 3 , by way of which the continuous cooler sleeve and safety bypass flow control valve  36  connects to the cooler. 
     The annular fluid outlet  41  has at least one and preferably a plurality of spaced fluid outlets or discharge openings  60  formed through the annular wall for communicating the inner valve chamber  43  with the fluid outlet  16  to the lube circuit or channel  15 . 
     The bypass valve  44  acts as a bypass member to channel discharge fluid from the converter directly to the fluid channel  15  of the transmission in the event pressure of the discharge fluid rises above a predetermined pressure, such as above 60 psi. Under normal operation, the central post  45  of the valve  43  seats within and plugs the opening  53  through the central portion thus preventing fluid flow from the annular inlet  40  of the central portion to the valve chamber  43  of the first sleeve portion of the continuous cooler sleeve and safety bypass valve  36 . The fluid circuit and valve position are shown in  FIG. 3 . 
     However, with reference to  FIG. 6 , should the pressure rise above the predetermined pressure in the cooler circuit or converter discharge or should the cooler or cooler flow channels become plugged, such as may occur at very low ambient temperatures wherein the transmission fluid may become gelled, the valve  44  is forced against the biasing spring  51  such that the valve post  45  opens the opening  53  in the central portion  39 . Under these conditions, the transmission fluid will pass from the discharge of the torque convert  25  into the valve chamber  43  of the first sleeve portion and flow outwardly through the outlet openings  60  to the discharge circuit  16  toward the transmission rear lube circuit. Once pressure within the continuous cooler sleeve and safety bypass valve  36  drops below the predetermined pressure, valve  44  will be urged to its closed position by the spring  51  such that the post  45  thereof plugs the opening  53  in the central portion and flow to the cooler is immediately returned. It should be noted that a ball valve may be used as opposed to the cylindrical valve with post to open and close the opening  53 . 
     It should be noted that the plug  55  that closes the open end of the first sleeve portion may be formed as one piece with the first sleeve as opposed to being joined to the first sleeve portion. 
     When replacing the conventional thermostatic cooler bypass valve with the continuous cooler sleeve and safety bypass flow control valve  36 , and in order to balance operating pressures within the transmission lube circuits, the check ball valve  14  is removed such that transmission oil may flow in both directions through the valve housing. In addition, an input orifice  90  in the converter control valve assembly  18  which normally supplies converter discharge lubricant to a converter back pressure valve  92  is plugged so as to maintain pressure and flow within the lube circuits. Also, with reference to  FIG. 8 , a front lube orifice  70  within the convention cup plug  72  of the pump stator  73  of the transmission should be enlarged using a ⅛ th  inch drill bit so as to further promote movement of oil to the overdrive components. In addition, a plurality of holes, such as four 3/32 nd  Inch Diameter Holes  76 , should be drilled through the overdrive drum to planetary sun gear drive plate  80 , see  FIG. 9 , in order to facilitate transmission fluid flow to the overdrive planetary gears. By making the foregoing modifications to the other parts of the Ford 5R55 series transmissions, it is estimated that up to approximately four times the oil supply to the overdrive planetary gears is achieved over the originally equipped transmissions thereby preventing planetary burnout in the overdrive gearing.