Abstract:
Disclosed herein are systems and methods of controlling the pressure in a modulation pressure circuit through transmission fluid through an orificed check valve supplementary or in substitution of a computer-controlled pressure regulation solenoid. Detailed information on various example embodiments of the inventions are provided in the Detailed Description below, and the inventions are defined by the appended claims.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
   This Application claims the benefit of the U.S. Provisional Application Ser. No. 60/576,254 filed Jun. 1, 2004, which is hereby incorporated by reference in its entirety. 

   BACKGROUND 
   The claimed inventions relate generally to systems that control line pressure in an automatic transmission by a modulation pressure, and more particularly to transmission modification kits that provide line pressure control as a substitute or supplement for computer-controlled line pressure through a modulation pressure circuit and solenoid. 
   For orientation, the operation of automatic transmissions will now be described. Shown in  FIG. 1  are conceptual elements of operation of most automatic transmissions. A pump  1  is configured to receive fluid, typically oil, from a reservoir or pan  4  passing through a filter  3 . Pump  1  is driven by rotation of an input shaft coupled to an engine, not shown. In most transmissions a positive displacement pump is used, which is a pump that generates a substantially constant volume per input shaft rotation, or a fluid flow substantially proportional to the rotation of the input shaft. Examples of positive displacement pumps are georotor, gear and vane type pumps. While the input shaft is being driven by rotation of the engine, pump  1  produces a flow of fluid that returns to the reservoir  4  except for a small portion needed for lubrication and to displace valves and servos. Fluid pressure is produced by a main regulator  2  by partially blocking the flow produced by pump  1 , which “line” pressure is distributed throughout the transmission through passages  5 . 
   The line pressure is typically provided at a pressure higher than needed by the operating transmission components, and is regulated down to lower operating pressures by auxiliary regulators  6   a  and  6   b . Those lower pressures are provided to the transmission components, in this example valves  7   a  and  7   b  and servos  8   a  and  8   b.  The arrangement shown in  FIG. 1  is merely conceptual; in practice many different configurations of regulators, valves and servos are be used, as is understood by one of ordinary skill in the art. 
   Fluid pressure may be applied to the several servos in the transmission to provide mechanical operation of the driven components. Those components ordinarily include several clutches and a torque converter, by which the several gears of the transmission are applied to the engine output. An accumulator is normally coupled to the input of a servo, which slows the engagement or disengagement of the servo. Although an accumulator might be implemented by a spring and piston in a bore, conceptually one operates as a balloon. If pressure is increased, an accumulator accepts fluid until an equalibrium is reached. Likewise, as pressure decreases, the accumulator discharges fluid to the new set pressure. The movement of fluid in or out of an accumulator is not instantaneous, but rather is slowed by the fluid passages of the transmission. An accumulator thereby functions to buffer input pressures and graduate the transitions of servo engagement and disengagement. 
   The gradual operation of servos tends to soften the shifts of the transmission. Sudden gear transitions are undesirable, because passengers feel a lurch or impact and because undue stress is applied to the engine and drive components. Gear shifts that are too soft, however, are also undesirable. During the transition from one gear to another, two clutches may be engaged for a time which increases wear and heat in the transmission. Soft shifts increase this transition time, which decreases the service life of the transmission. A great deal of research and design effort has been made to optimize the shifts in transmissions to balance this tradeoff. 
   It has been recognized that firm shifts are preferable in some driving circumstances, such as during hard acceleration. Soft shifts, on the other hand, are preferable under other circumstances, for example under light acceleration and coasting. One method of acheiving both hard and soft shifts in the same transmission is to vary the pressure applied to the servos and accumulators. A lower engagement pressure to a servo results in an increased transition time, as more time is required to “fill up” the accumulator. Likewise, a higher disengagement pressure may also be helpful to soften a shift. 
   One technique used to adjust fluid pressure to servos is through controlling line pressure. A higher line pressure will cause faster servo transition, at least to engagement. As a servo is to be engaged, its accumulator must first accommodate the new pressure. It does so by accepting an amount of fluid which the system must supply through the line pressure. This flow must pass through the various restrictions in the transmission passages, and can do so more rapidly if the head pressure is higher. Thus a higher line pressure will force a greater fluid flow through the transmission passages, which accordingly causes more rapid accumulator adjustment and firmer shifts. This technique also applies to the movement of valves, which also requires some amount of fluid to enter a chamber at the end of the valve bore. 
   Modulators capable of adjusting fluid pressure have included throttle valves with mechanical linkage and vacuum modulators. These have worked to increase transmission fluid pressure when the throttle is open, intending to cause firmer shifts under that condition. Most recently, modulators have been coupled to an automotive computer/controller that controls the transmission line pressure. Modem automobiles feed a number of sensor inputs into a computer, which then operates to control any number of operational parameters, such as the timing of fuel injectors and spark plug ignition timing. The computer is carefully designed to provide good performance, especially under average driving conditions. 
   Referring now to  FIG. 2A , a line pressure modulation system is shown capable of being controlled by an automotive computer. As in the system of  FIG. 1 , a pump draws fluid through a filter  3  and supplies fluid flow to a main regulator  5 , which provides regulated line pressure  5 . Main regulator  2  includes a modulation port by which the line pressure may be controlled, for example, in a modulation circuit at a pressure proportional to the modulation pressure in a given operating range. Restrictions  14  and  15  provide pressure isolation between the modulation port and the input port of the main regulator  2 . Restrictions  11  and  12  are conceptual in nature; in practice these restrictions might be provided by passages in the transmission, by regulators, or by other components that supply isolation between the two circuits. A solenoid or modulator  9  is coupled to the modulation pressure  13  providing relief whereby the modulation pressure may be controlled or regulated. A pressure relief valve  10  including a fluid exhaust port is provided to vent a damagingly high modulation pressure  13 , which may also limit the maximum line pressure  5  that can be developed in the system. When solenoid  9  in the example is inactive, no fluid flow occurs through the modulation passages under normal conditions. Solenoid  9  may be fully driven to acheive a low modulation pressure  13 , or may be partially driven to acheive a moderate modulation pressures through pulse-width modulation techniques, for example by an automotive computer. 
   The configuration shown in  FIG. 2  has two inherent failure conditions. First, if the solenoid should become disconnected from the computer, or if the solenoid became stuck “off,” the modulation pressure will rise to its maximum. This failure will result in hard shifts at all times, and may result in damage to transmission components, such as the pump, if line pressure is excessive. In some transmissions cooler and lubrication flow may be reduced or shut-off with excessive modulation pressure, as will be discussed below. Second, if the solenoid should become stuck “on”, the modulation pressure will stay low, resulting in soft slippery shifts at all times. This may cause overheating and failure of the transmission, especially for vehicles towing loads up grades. 
   That configuration has a third failure mode, which is failure of the computer to appropriately command line pressure. The designer of the system may have considered only limited circumstances of use, and designed the computer&#39;s program for only the “normal” operational use. For example, it is not uncommon for a single transmission model to be installed to both standard passenger and towing vehicles, despite the large potential difference in total weight. The transmission design may be optimized for a passenger car or a medium duty truck, and may be found to perform acceptably well in the heavy-duty towing vehicle such that an additional transmission model is not necessary to develop or maintain an assembly line for. Under actual use that transmission might be subjected to heavier loads than what the designer intended, because, for example, an operator finds the vehicle engine is sufficiently powered to tow a load up a certain grade. The vehicle&#39;s computer may not have a sensory input for the tow weight, and may command soft shifts where firm shifts are called for to avoid transmission overheating. Additionally, most automotive companies do not provide for any automotive computer reprogramming as a solution. 
   A fourth failure mode may be encountered with the failure of an engine or transmission sensor. It is not unknown for vehicle owners or drivers to continue to operate a vehicle even though the check-engine light is on, indicating that an automotive computer has discovered a problem and recorded a trouble code. Indeed, a vehicle operator may be unmotivated to have the vehicle diagnosed and repaired, due to an expected high cost. Furthermore, some older vehicles were designed only to check for electrical continuity of sensors, and not to detect and flag out-of-range conditions caused by failing sensors. A failed sensor may cause incorrect control of a transmission. For example, a faulty throttle position sensor may cause an automotive computer to erroneously recognize a full-throttle condition as a mid or low-throttle condition. The computer might then command low line pressure for softer shifts, increasing heat and wear. Many other undesirable effects may occur from the failure of other vehicle sensors. 
   Automotive systems, and especially transmission systems, are operationally complex and require a great deal of knowledge and experience to diagnose and repair problems not frequently encountered. Problems with line pressure are not always perceptible with a vehicle “in the shop,” particularly if those problems occur only under special circumstances, for example towing a heavy load up a long and steep grade. Furthermore, it is uncommon for a mechanic or driver to observe transmission line pressure out of the shop because of the difficulty installing a gauge that can be seen from the safety of the inside of a moving vehicle, which might be the only way to directly observe certain transmission performance problems. Trained but inexperienced mechanics may follow the standard flowcharts and/or instructions and observe proper performance under normal conditions, but fail to understand the nature of a particular transmission failure. Furthermore, there has been deficit of understanding of the operational relationship between an automotive computer and a transmission in recent automobiles, which has allowed many transmission problems to continue without a solution for several years. Indeed, there has been a need for a way to provide reliable modulation pressure in a transmission independently of an automotive computer for some time. 
   BRIEF SUMMARY 
   Disclosed herein are systems and methods of controlling the pressure in a modulation pressure circuit through transmission fluid through an orificed check valve supplementary or in substitution of a computer-controlled pressure regulation solenoid. Detailed information on various example embodiments of the inventions are provided in the Detailed Description below, and the inventions are defined by the appended claims. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  shows conceptual elements of most automatic transmissions. 
       FIG. 2A  conceptually shows a line pressure modulation system controllable by an automotive computer. 
       FIG. 2B  conceptually shows a line pressure modulation system to that of  FIG. 2A  with an orificed check valve and with the solenoid made inactive. 
       FIGS. 3A ,  3 B and  3 C conceptually shows the operation and failure modes of a main regulator valve that controls line pressure through a modulation port. 
       FIG. 4  illustrates a pressure-relief check ball. 
       FIGS. 5A and 5B  show the operation of an orificed check valve. 
       FIG. 6  shows a relationship between pressure and transmission fluid flow through a modulation pressure circuit achievable through the use of an orificed check valve. 
       FIGS. 7A and 7B  show an exemplary orificed check valve suitable for a Ford E40D/4R100 transmission. 
       FIG. 8  shows a modification kit for a Ford E40D/4R100 transmission. 
       FIG. 9  depicts the PCS plug included in the kit of  FIG. 8 . 
       FIG. 10  depicts the PMV plug included in the kit of  FIG. 8 . 
       FIG. 11  depicts an AP stop included in the kit of  FIG. 8 . 
       FIG. 12  shows an installation procedure to the line pressure modulator valve assembly using the kit of  FIG. 8 . 
       FIG. 13  shows an installation procedure to a pump cover using the kit of  FIG. 8 . 
       FIG. 14  shows an EPC Solenoid Case Connector of a Ford E40D/4R100 transmission. 
       FIG. 15  shows a Solenoid Assembly of a Ford E40D/4R100 transmission. 
       FIG. 16  depicts the location of the EPC check ball against the valve-body plate of a Ford E40D/4R100 transmission. 
   

   Reference will now be made in detail to orificed check valves, kits for modifying a transmission to control line pressure and methods of using the same, which may include some more specific embodiments of the claimed inventions, examples of which are illustrated in the accompanying drawings. 
   DETAILED DESCRIPTION 
   Disclosed herein is a modification procedure for a Ford E40D or 4R100 type transmission. This design will now be discussed, by which advantages of modifications later described will become apparent. Referring first to  FIG. 3A , elements of the Main Regulator Valve  19  in the E40D/4R100 are conceptually illustrated in simple detail. Valve  19  includes a valve body  21  machined to receive a spool valve  22  and compression spring  29 . Valve body  21  includes several ports, including a pump inlet  23  and a line pressure outlet  25 . In this figure valve  19  is shown in a dry or startup state, with minimal or no line pressure. Also in this figure, no modulation pressure is yet being applied to modulation port  27 . An exhaust port  24  is provided to dump fluid to the pan in excess of that needed to regulate line pressure, which in this figure is closed pending pressure buildup. An open passage  28  vents pressure or vacuum as spool valve  22  moves in its chamber. Finally, a lubrication/cooling port  26  is provided to supply fluid to certain components or areas of the transmission under normal operating conditions. 
   Referring now to  FIG. 3B , as line pressure builds, pressure in chamber  30  compresses spring  29  and forces spool valve  22  to move to the left. At the position shown in the figure, exhaust port  24  opens, which causes a circuit of fluid through the pump, inlet  23 , exhaust port  24  and pan. Lubrication/cooling port  26  also becomes unobstructed and provides lubrication. Modulation pressure may be provided at chamber  31 , which presses the valve to move to the right. Spool valve  22  then reaches a new position in equalibrium slightly to the right with higher pressures at both chamber  30  and line pressure outlet  25 . 
   Shown in  FIG. 3C  is valve  19  in a position of failure caused by excess modulation pressure. As shown spool valve  22  is positioned so far to the right as to close off exhaust port  24 . In this state, line pressure will rise excessively high, especially at higher engine RPMs. In the example of  FIG. 3C , lubrication/cooling port  26  is closed off, and little or no oil is supplied to the bearings, bushings and planetaries which are in danger of failure. This condition might be encountered in a vehicle towing a heavy load, with the throttle open fully accelerating from a stop or pulling the load up a steep grade, causing line pressures exceeding about 170 to 200 psi. This condition might also be encountered if a pressure-relieving solenoid valve is disconnected or stuck off. If this condition is continued for more than a few seconds, overheating or failure of the bearing surfaces may result in the total failure of the transmission. 
   Referring back now to  FIG. 2A , a pressure relief valve  10  may be incorporated in the modulation pressure circuit preventing a cascading transmission failure. In the E40D/4R100 transmission this is implemented with a check ball  40 , as shown in  FIG. 4 . Check ball  40  is maintained against seat  42  by compression spring  41  under normal pressure. When pressure P exceeds a limit, the force supplied by spring  41  is overcome and fluid escapes around ball  40  in the direction shown by the arrows. That check ball can be replaced by an orificed check valve  50 , as shown in seated position in  FIG. 5A . 
   With valve  50  seated, pressure P produces a flow F through passage or orifice  51 , which flow is returned to the transmission reservoir or pan. Valve  50  includes a spring fitting for receiving compression spring  52 . Valve  50  is pressed against seat  42  so long as the force supplied by compression spring  52  is greater than the force of pressure against valve head seating portion  53 . Valve  50  also acts as a pressure relief valve, in that excess pressure P will cause fluid to flow around valve head  53  as shown in  FIG. 5B . 
     FIG. 6  depicts the resulting flow F to pressure P relationship of an orificed check valve system. With large flow generally above a threshold value, the pressure is limited as shown on the curve at  62 . At a smaller range of flows  61 , pressure P has a linear relationship with flow. If unregulated flow is supplied by a positive displacement pump, such as a georotor or vane pump, pressure P has a linear relationship with input shaft rotation. The higher modulation pressures P produced by higher engine rotation translates into higher line pressures and firmer shifts. The slope of the curve at  61  depends on the size of the orifice and the flow entering the modulation pressure circuit. A proper orifice size may be determined by installing to a test transmission and observing the line pressure at a line pressure tap at various engine RPMs. 
   Provided that downshift timing is provided by factors other than only engine or input shaft rotation, such as a throttle valve, vacuum modulator or computer algorithm, the result will generally be soft shifts under light throttle and firm shifts under acceleration, due to the operation of the transmission system to hold out downshifts to higher engine RPMs under increased throttle. Indeed, in a modification procedure described below, computer control of line pressure is eliminated entirely in favor of the linear pressure to flow relationship provided by the orificed check valve, which removes any variation introduced by the computer that might be incorrect for a towed load. If the modulation pressure is provided through a regulator in a particular transmission design, an orificed check valve or other component may still provide a flow to pressure relationship if the regulator is restricted or disabled. 
     FIG. 7A  shows an enlarged side view of a dimensioned orificed check valve suitable for installation to an EPC blowoff exhaust port on a Ford E40D/4R100 transmission, replacing the standard 0.25 inch check ball.  FIG. 7B  shows a corresponding sectional view. The valve has a mushroom-like shape, including a near half-spherical seating portion  70  having a similar curvature to that of the check ball it will replace and a shaft portion  71  including a spring fitting. The curvature may be varied provided that a seal is maintained providing a linear flow to pressure relationship throughout an operational flow range. The half-spherical portion has a diameter  75  of 0.31 inch, with a total length  74  of 0.21 inch, and is shaped to seat against the EPC exhaust port. The shaft portion  71  is cylindrical dimensioned at a diameter  78  of 0.17 inch and 0.315 inch in length  73 . Those shaft dimensions are suitable to accept the original factory check ball compression spring, and may be varied to suit other springs or positioning devices as desired. An orifice  77  passes through spherical portion  70  and shaft portion  71 , having an inside diameter chosen with the desired pressure to flow ratio described above. For the Ford E40D/4R100 transmissions, good results may be obtained by selecting a diameter between about 0.073 inches (for heavy-duty towing vehicles) to 0.091 inches (light duty passenger vehicles.) These particular orificed check valves can be conveniently fashioned from modulated release cartridges for A4LD type transmissions, or can be machined from any durable metal. Finally, a taper  76  at the orifice inlet may be formed to enhance fluid flow. 
   In addition to the installation of the orificed check valve, other modifications can be made. First, any modulator in the modulation pressure circuit may be deactivated, disconnected or replaced with a dummy insert. Optionally, a substitutionary component for any modulator may be used to present a device of similar characteristics to a present automotive computer. For the Ford E40D/4R100 transmission, this may be accomplished by disconnecting the EPC solenoid from the powertrain control module (PCM) and by substituting an electrically resistive load with a similar resistance to an EPC solenoid, so as to avoid setting any trouble codes in operation. Other transmission designs may indicate other deactivations or disconnections. If the modulation pressure circuit is designed to be regulated, the regulator may be modified to produce a flow sourced to the circuit, advantageously rising with greater input shaft rotation. It may also be desired to replace compression springs and other force-providing components to adjust the accumulators and valves operation for any changes to line pressure. 
   EXEMPLARY MODIFICATION KIT 
   Depicted in  FIG. 8  is an exemplary modification kit for conversion of a Ford E40D/4R100 transmission to orificed check valve operation. That kit includes three orificed check valves  80   a,    80   b  and  80   c  of the design described for  FIGS. 7A and 7B , having three different orifice diameters, for example 0.094 (normal driving) 0.065 (towing) and 0.101 (smooth shifting) inches. Inner and outer springs  81  and  82  are provided as substitutes to adjust the performance of the main pressure regulating valve, or merely as replacements as part of good maintenance practices. Replacement accumulator springs are also provided (three sets for the three accumulators), which installed in each accumulator include an inner spring  83  and an outer spring  84   a  or  84   b.  These accumulator springs are adapted or tuned to the line pressures produced by the other components of the kit. The exemplary kit includes outer springs for two variants of the E40D/4R100 transmissions, the first of which was manufactured from 1989-94 and the second from 1995 on. The kit also includes one PCS plug  86 , one PMV plug  87  and two AP stops  85 . Also included is a 5 ohm resistor  88  to electrically replace the EPC solenoid as seen by the PCM, so no trouble codes are produced. The PCS plug is fashioned to be a cylinder 0.804 inches in diameter and 1.55 inches long, with a groove  89 , shown in  FIG. 9 , set from one end 0.39 inches, which groove is 0.12 inches wide and 0.14 inches deep. Looking to  FIG. 10 , the PMV plug is a cylinder 0.494 inches in diameter and 1.500 inches long. The AP stops are also cylinders 0.31 inch in diameter and 1.60 inches long. The plugs and stops may be conveniently machined in aluminum, or in any other sufficiently wear-resistant and hard material. 
   The springs may be dimensioned as follows. Springs  81  and  82  may be identical to the factory springs, if desired. Accumulator inner springs  73  may be fashioned from 0.052 inch wire with a 0.460 inch diameter and 2.275 inches long. Accumulator outer springs  74   a  may be made from 0.063 inch wire with a 0.632 inch diameter and 2.645 inches long. Alternate accumulator outer springs  74   b  can be made from 0.072 inch wire with a 0.660 inch diameter and 2.425 inches long. In any event, a kit may include a tuned set of accumulator springs for a transmission as modified by the kit, providing a predetermined shift performance. Likewise, accumulator stops or other accumulator components may be included in a kit for further accumulator shift performance if desired. 
   EXEMPLARY MODIFICATION PROCEDURE 
   The installation procedure of the exemplary kit requires a partial disassembly of the transmission, the extent of which will be apparent to one of ordinary skill in the art. In the accumulator body  90 , shown in  FIG. 12 , the line pressure modulator valve assembly is removed and discarded, including the line pressure modulator valve  95 , outer spring  96 , spring and retainer assembly  97 , line pressure modulator plunger valve  98 , and line pressure modulator sleeve  99 . In the now empty line pressure modulator bore the PMV and PCS plugs are inserted, the PMV plug oriented grove first, followed by the PCS plug. Installing the PMV and PCS plugs renders the line pressure modulator inoperative by blocking potential fluid flow. The retainer  100  removed during removal of this valve assembly may be re-used to secure the plugs. Next, the 1-2 accumulator assembly is removed, replacing the factory springs with the kit-supplied springs as noted above. That assembly is re-inserted into bore  91 . Next, in each of the 2-3 and 3-4 accumulators the factory inner and outer springs are replaced with the springs included in the kit, noted above. Within each of these accumulator assemblies, one of the AP stops is placed inside the springs to reduce the accumulator piston travel by approximately 0.20 inch. In each of these accumulator assemblies the factory control valve springs may be re-used if they are in good condition. After insertion into their respective bores  93  and  94 , 1/16 inch holes are drilled into the center of the end caps of all three accumulators to permit any fluid that may be deposited behind the pistons to be ejected into the pan. 
   Next, in the pump housing  101 , shown in  FIG. 13 , the main pressure regulator valve is removed from its bore  102  and the springs replaced. Note that this step is optional, and may be omitted if a full transmission rebuild is not undertaken. Next, the EPC solenoid is disconnected and resistor  78  is substituted as a load for the PCM. The EPC signals are delivered to pins  11  and  12 , shown by the same numbers in  FIG. 14 , of the EPC solenoid case connector  103 . The solenoid case connector mates to connector  105  of solenoid case  104 , which case includes EPC solenoid at  106  shown in  FIG. 15 . One way to make this substitution is to unsolder both of the EPC solenoid terminals on the bottom of the EPC solenoid at the printed circuit board junction, and solder the resistor in its place across the terminals. The resistor may be secured by a wire tie or other fastener as desired. 
   The final step is to replace the factory EPC check-ball with one of the three orificed check valves selected for the type of vehicle use. The location of the EPC exhaust port in relation to the valve-body plate is shown in  FIG. 16 , which is the installation location of the orificed check valve. The factory EPC spring may be re-used with the new orificed check valve. Now the above installation procedure need not be performed exactly, but rather any convenient order may be used. 
   The orificed check valves shown and described, and modification kits containing the same may be fashioned for other transmissions utilizing a positive displacement pump, including Ford models AXODE, AX4S, AX4N, 4F50N, 4R44E, 4R55E, 5R55E, 5R55N and 5R55W, General Motors models 4T65E, 4T40E, 4T45E, 4L60E, 4L65E, 4L80E, 4L80EHD and transmissions of other auto-makers, by following the principles and techniques described above. Additionally, new transmissions may be manufactured to include a flow-controlled pressure modulation circuit, utilizing a check valve including an orifice or locating an orifice at another location in the circuit, with or without a computer-controlled pressure modulator. And while orificed check valves, kits for modifying a transmission to control line pressure and methods of using the same have been described and illustrated in conjunction with a number of specific configurations and methods, those skilled in the art will appreciate that variations and modifications may be made without departing from the principles herein illustrated, described, and claimed. The present invention, as defined by the appended claims, may be embodied in other specific forms without departing from its spirit or essential characteristics. The configurations described herein are to be considered in all respects as only illustrative, and not restrictive. All changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope.