Patent Abstract:
Apparatus and method of replacing old fluid in a transmission system by feeding clean fluid into the system from a clean fluid tank using a pump and draining the old fluid into a waste tank and using a processor to monitor the clean fluid pressure in the clean tank and the old fluid pressure in the waste tank and adjusting the pump&#39;s speed using the processor such that the old fluid is drained at substantially the same rate as the clean fluid is fed.

Full Description:
This application is a continuation of application Ser. No. 09/184,621, now U.S. Pat. No. 6,062,275, filed on Nov. 2, 1998, the disclosure of which is incorporated fully herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention relates generally to vehicular maintenance and, more particularly, to systems and methods for replacing transmission fluid. 
     For the past several years, substantial attention has been directed to the field of transmission fluid changers. Such systems are useful, for example, in draining the oil from a vehicle transmission system in order to replace the transmission filter and/or to completely replace the old transmission fluid with new fluid. Existing transmission fluid changers such as those described in U.S. Pat. Nos. 5,447,184, 5,472,064, 5,318,080 and 5,370,160 require substantial human intervention during the fluid exchange process. 
     However, there is an intense need within the industry to provide a more efficient, less time consuming and a more user-friendly system for transmission fluid replacement that substantially reduces human intervention. 
     In view of this necessity, it is believed that those skilled in the art would find automated systems and methods for draining, filling and changing of transmission fluid to be quite useful. 
     SUMMARY OF THE INVENTION 
     In a first separate aspect, the present invention is directed to an apparatus for replacing waste fluid with clean fluid. The apparatus includes a waste tank for receiving the waste fluid from a first port, a clean tank containing the clean fluid, a processor coupled to first and second sensors, and a pump coupled to the processor for pumping the clean fluid into a second port. The processor measures the waste fluid level via the first sensor and measures the clean fluid level via the second sensor. Based on these measurements, the processor controls the pump&#39;s speed. 
     In a second separate aspect, the apparatus of the first separate aspect may also include a solenoid switch that includes first and second ports and a plurality of paths for transferring the clean and waste fluids. 
     In a third separate aspect of the invention, the paths in the solenoid switch of the second separate aspect may be selected via the processor by measuring the fluid pressure at each solenoid switch port. 
     In a fourth separate aspect, the apparatus of the first separate aspect may also include a disposal pump coupled to the processor for pumping the waste fluid from the waste tank into a disposal tank. 
     In a fifth separate aspect, the present invention is directed to a method of replacing waste fluid with clean fluid. The method comprises the step of providing a waste tank for receiving the waste fluid from a first port and a clean tank containing the clean fluid. The method further includes the step of coupling a processor to a first sensor, a second sensor and a pump for pumping the clean fluid into a second port. The method also includes the steps of measuring the waste fluid via the first sensor using the processor and measuring the clean fluid via the second sensor using the processor. And the method includes the step of controlling the pump using the processor based on the measuring steps. 
     In a sixth separate aspect, the present invention is directed to a method of replacing waste fluid in a system with clean fluid. The method includes the steps of draining a portion of the waste fluid from the system into a waste tank, measuring the amount of the drained fluid with a processor, and replacing the drained fluid with clean fluid from a clean tank using a pump that is controlled by the processor. 
     In a seventh separate aspect, the method of the sixth separate aspect may include the steps of withdrawing the remaining portion of the waste fluid plus the clean fluid in the system into the waste tank, gauging the amount of the withdrawn fluid using the processor, feeding the system with the clean fluid using the pump, gauging the amount of fluid in the feeding step using the processor, and controlling the pump such that the withdrawing step proceeds at substantially the same rate as the feeding step. 
     In an eighth separate aspect, the method of the seventh separate aspect may include the step of terminating the process when the clean fluid reaches a low level in the clean tank. 
     In a ninth separate aspect, the method of the seventh separate aspect may include the step of pumping an extra amount of the clean fluid into the system. 
     Accordingly, it is an object of the present invention to provide apparatus and method of replacing one fluid with another in a system, such as a vehicle transmission system. 
     Other objects and features of the present invention will become apparent from consideration of the following description taken in conjunction with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a schematic diagram of an automated system for replacing transmission fluid; 
     FIG. 1A is an exploded view of a solenoid switch of the system of FIG. 1; 
     FIG. 2 is a pictorial view of a control panel of the system of FIG. 1; and 
     FIG. 3 is a pictorial view of the system of FIG.  1 . 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     Turning now to the drawings, FIG. 1 provides a schematic illustration of a fluid changer system  100  according to a preferred embodiment of the present invention. As shown, the system  100  includes a clean fluid tank  110 , a waste fluid tank  120 , a clean pump  130 , a waste pump  140 , a solenoid switch  160 , a disposal tank  170  and a printed circuit board (PCB)  150  with an on-board microprocessor (not shown), a clean tank pressure sensor  151  and a waste tank pressure sensor  152 . 
     The clean tank  110  contains fresh fluid that is supplied to a vehicle transmission system (not shown). The clean tank  110  also includes a clean tank tube  112  with one end inside the clean tank  110  and the other end extending out and being connected to a clean fluid pump  130 . As shown, the clean tank tube  112  includes a filter  116  for purifying the fresh fluid before reaching the clean pump  130 . 
     The clean pump  130  pumps the fresh fluid out of the clean tank  110  through the clean tank tube  112  and filter  116  into the clean pump outlet tube  132 . The clean pump outlet tube  132  transports the fresh and purified fluid to the solenoid switch  160 , the operation of which is discussed below. 
     Turning back to the clean tank  110 , the clean tank  110  further includes a port  115  for withdrawing fluid from or adding fluid to the clean tank  110 . The clean tank  110  also includes a clean sensor tube  114  that extends out of the tank  110  and is coupled to the PCB  150 , so the on-board microprocessor can measure the fresh fluid pressure in the clean tank  110 . 
     As illustrated, the PCB  150  also receives a waste sensor tube  124  from the waste tank  120  for the purpose of measuring the waste fluid pressure in the waste tank  120 . The waste tank  120  also includes a waste tank tube  122  which extends out of the waste tank  120  and a waste filter  126  to reach a waste pump  140  for pumping out the waste fluid. The waste fluid is passed through the filter  126  so to prevent the impurities of the waste fluid from interfering with the proper operation of the waste pump  140 . 
     As seen in FIG. 1, the waste pump  140  pumps the waste fluid out via the waste tube  122  and pumps the waste fluid into the disposal tank  170  via a disposal tube  145 . 
     Referring back to the waste tank  120 , the waste tank  120  receives the waste fluid through a waste inlet port  127  connected via a waste inlet tube  128  to the solenoid switch  160 . 
     In a preferred embodiment, the solenoid system  160  comprises three solenoid valves (not shown) that are controlled via the PCB  150  microprocessor in accordance with the modes of operation described below. The three solenoid valves are set or reset according to each mode of operation to create the desirable fluid paths, such as fluid paths  161 ,  163 ,  165 ,  166  and  167 , as shown in FIG.  1 A. 
     In addition to the clean pump outlet tube  132  and the waste inlet tube  128 , the solenoid switch  160  is also connected to a first hose  162  and a second hose  164  for receiving the waste fluid from the vehicle and replacing the waste fluid with fresh fluid from the clean tank  110 . Connected to the first hose  162  is a first hose pressure sensor  168  that is electrically connected to the PCB  150  via the first sensor wire  154 . Similarly, connected to the second hose  164  is a second hose pressure sensor  169  that is electrically connected to the PCB  150  via the second sensor wire  153 . 
     In a preferred embodiment, the cooler line (not shown) of the vehicle is disconnected and reconnected at one end through the first hose  162  and at the other end through the second hose  164 . For example, when the recirculating path  167  is established within the solenoid system  160 , the transmission fluid may flow from one end of the cooler line through the first hose  162  through the recirculating path  167  and the second hose  164  to reach the other end of the cooler line. While the vehicle engine is operating, the vehicle transmission pump (not shown) pumps the transmission fluid through the cooler line. The transmission fluid, depending upon the fluid flow direction, enters either from the first hose  162  or the second hose  164 . Regardless of the fluid direction, however, the vehicle&#39;s transmission fluid circulates through the path  167  and back to the vehicle system. 
     To utilize the system  100  for replacing the waste fluid, the vehicle cooler line is disconnected while the vehicle&#39;s engine is off. The cooler line is connected to the first hose  162  at one end and the second hose  164  at the other end. At this point, the system  100  is powered on. The default setting for the solenoid system is the recirculating path  167 . Accordingly, when the vehicle engine starts, the transmission fluid is pumped through the solenoid system  160 . 
     Now, referring to FIG. 2, a computer control panel  200  of a preferred embodiment is shown. In a preferred method of replacing the waste fluid, the process may begin by pressing the drain button  220 . The drain pan function drains the waste fluid from the vehicle so the vehicle transmission pan (not shown) can be dropped in order to change the transmission filter (not shown). 
     By pressing the drain button  220 , the on-broad microprocessor begins the process by turning on the drain LED  222  to indicate that the drain process has begun. If the vehicle&#39;s engine is off, the on/start LED  212  blinks to indicate that the engine must be turned on so the vehicle&#39;s transmission pump starts pumping the waste fluid through the solenoid system  160 . Once the engine is turned on, the on/start LED  212  stops blinking and stays on continuously. 
     At this point, the on-board microprocessor determines the transmission fluid direction in the first and second hoses  162  and  164  in order to set up the solenoid valves and select the proper path inside the solenoid system  160 . This task is accomplished by sensing the fluid flow in the first and second hoses  162  and  164  via their respective pressure sensors  168  and  169 . According to the sensed pressures, the microprocessor determines the waste fluid circulation direction in the cooler line. Also, based upon the pressures sensed from the pressure sensor tubes  114  and  124 , the microprocessor determines the amount of fluid in each tank. The waste tank  120  being substantially empty has a lower fluid pressure than the clean fluid tank  110  containing fresh fluid to be pumped in. 
     Having determined the fluid flow direction and the location of the tanks  110  and  120 , the solenoid valves are set such that the proper path is taken. For example, if the fluid enters the solenoid system  160  through the first hose  162 , the path  161  is set up such the waste fluid is directed into to the waste tank  120  through the waste inlet tube  128  through the waste inlet port  127 . On the other hand, if the fluid flow direction is from the second hose  164 , the solenoid switch is set up such that the path  166  is selected. 
     Before directing the waste fluid to the waste tank  120 , using the pressure sensor  152  the present fluid level of the waste tank  120  is captured by the microprocessor for future determination of the amount of drained waste fluid. In a preferred embodiment, the fluid pressure in the waste tank  120  is checked every seven seconds to determine whether the waste fluid is flowing and whether the waste tank  120  is being filled. If the waste tank  120  is not being filled, the drain LED  222  goes off, the solenoid switch valves are set to assume the recirculate path  167 , the engine off/stop LED  214  turns on, the engine on/start LED  212  flashes, and the sounder sounds until the stop button  270  is pressed. 
     However, if these error conditions do not occur, the transmission fluid is sufficiently drained so the vehicle&#39;s transmission pan (not shown) can be dropped. The solenoid valves are set such that no more fluid flows from the first and second hoses  162  and  164 , and the low vehicle fluid LED  224  is turned to indicate that the drain process is complete. 
     At this step, the vehicle transmission pan may be dropped and the transmission filter may be changed without transmission fluid flowing from the transmission system. After the filter has been replaced and the drain pan is placed in its original position, the drained waste fluid may be replaced by pressing the fill button  240  on the control panel  200 . 
     At the fill step, the PCB  150  determines the volume of the drained waste fluid based on the captured fluid level in the waste tank  120  at the start of the drain process and the current fluid level in the waste tank  120 . Those of ordinary skill recognize that the fluid level may be calculated based on the sensed pressure via the pressure sensor  152 . Knowing the drained volume, the PCB  150  activates the clean fluid pump  130  to pump an equal volume of fresh liquid from the clean fluid tank  110  to the transmission system. In other words, enough clean fluid is pumped out such that pressure sensors  151  and  152  reach the same pressure balance as before the drain process started. 
     The PCB  150  also sets up the solenoid valves such that the fluid carried via the clean pump outlet tube  132  is routed correctly. If the first hose  162  was determined to be the in-hose—as determined at the beginning of the draining process—the solenoid system  160  is set up to select path  165  so the clean fluid reaches the first hose  162  and from there into the transmission. On the other hand, if the second hose  164  is the in-hose, the path  163  is taken so the clean fluid reaches the second hose  164 . 
     When the fill button  240  is pressed, the fill indicator LED  242  goes on indicating that a fill process is in progress. If the fill button  240  is pressed only once, an amount equal to the drained fluid volume is pumped back into the transmission system. However, each additional time that the fill button  240  is pressed the system is instructed to pump an extra half a quart of fluid into the transmission system. 
     Accordingly, if the fill button  240  is pressed twice instead of once, the +½ LED in box  246  comes on indicating that an extra half a quart will be pumped into the transmission system. If the fill button  240  is pressed three times, the +1 LED in box  246  comes and one extra quart is pumped in. If the fill button is pressed eight times, the three LEDs +½, +1 and +2 in box  246  come on and 3.5 extra quarts of fluid will be pumped in. The fill indicator LED  242  goes off when the fill process is complete. 
     The next step of the process may begin by pressing the change fluid button  230  on the control panel  200 . At this step, the system  100  pumps clean fluid into the vehicle at substantially the same rate as pumping waste fluid out of the transmission system. Before the change fluid button  230  is pressed the first and second hoses  162  and  164  must be connected to the cooler line of the vehicle. The solenoid system is in its default state, i.e., the recirculation path  167  is in effect. 
     Once the change fluid button  230  is pressed, the change fluid process starts. If the clean fluid level in the clean tank  110  is low, the low clean fluid LED  244  starts flashing and the sounder starts sounding until the stop button  270  is pressed. Also, if the waste tank  120  is over ¼ full, the empty waste LED  260  starts flashing and the sounder sounds until the stop button  270  is pressed. If the preliminary conditions are correct, the fluid levels in the clean tank  110  and the waste tank  120  are measured via the pressure sensors  151  and  152 , respectively. In case the low clean fluid LED  244  is on, the clean fluid tank must be filled. 
     According to the flow direction-sensing process explained above, the system  100  determines the in-hose and the out-hose directions between the first and second hoses  162  and  164 , and also determines the clean pump outlet tube  132  and the waste inlet tube  128  via pressure sensors  168 ,  169 ,  151  and  152 , respectively. Once the flow direction is determined the solenoid valves in the solenoid system  160  are properly set to pump in the clean fluid and receive the waste fluid. For example, if the second hose  164  is the out-hose, path  163  is selected so that clean fluid flows from the clean fluid outlet tube  132  to the second hose  164  and into the transmission system. In this case, path  161  is also selected so the waste fluid being pumped by the vehicle engine flows from the first hose  162  through path  161  into the waste inlet tube  128  and the waste inlet port  127 . 
     However, if the first hose  162  is the out-hose, path  165  is selected so the clean fluid flows from the clean fluid outlet tube  132  into the first hose  162  and into the transmission system. Naturally, path  166  is also selected so the waste fluid flows from the second hose  164  to the waste inlet tube  128  and into the waste tank  120 . 
     Once the proper paths are selected, the clean fluid pump  130  pumps out clean fluid from the clean fluid tank  110  via the clean fluid tube  112  and through the clean fluid filter  116 . From there, clean fluid is pumped through the clean pump outlet tube  132  into the solenoid switch  160  and into the transmission system through the pre-selected path. As for the waste fluid, the vehicle transmission pump (not shown) also pumps the transmission fluid as the engine is running. Waste fluid flows from either the first hose  162  or the second hose  164  and takes the pre-selected path to reach the waste inlet tube  128  and the waste tank  120 . 
     In a preferred embodiment, every seven seconds during the change fluid process, the microprocessor on the PCB  150  monitors the flow rate based on pressure values obtained from the waste tank pressure sensor  152  and the clean tank pressure sensor  151 . The change in pressure in the clean tank  110  is calculated by simply subtracting the current pressure from previous pressure. The change in pressure in the waste tank  120  is calculated by subtracting the previous pressure from the current pressure. 
     If the change in pressure in the waste tank  120  is higher than the change in pressure in the clean tank  110 , it means that the waste tank  120  is being filled more quickly than the clean tank  110  is being emptied. In that case, the clean pump&#39;s  130  speed must be increased by a value proportionate to the difference in pressure changes in the clean tank  110  and the waste tank  120 . 
     However, if the change in pressure in the clean tank  110  is higher than the change in pressure in the waste tank  120 , it means that the waste tank  120  is being filled less rapidly than the clean tank  110  is being emptied. Accordingly, the clean pump&#39;s  130  speed must be reduced by a value proportionate to the difference in pressure changes in the clean tank  110  and the waste tank  120 . 
     The automatic flow rate control and its timing are important features since pumping the clean fluid faster than the vehicle&#39;s transmission pump is pumping the waste fluid will cause a fluid overflow in the transmission system. On the other hand, slow pumping of the clean fluid would cause a fluid underflow in the transmission system which may damage the vehicle and would also require the vehicle&#39;s engine be stopped from time to time to allow the clean tank pump  130  to catch up with the vehicle&#39;s transmission pump&#39;s faster speed. Therefore, those of ordinary skill in the art would appreciate such properly timed flow control that substantially eliminates human intervention during the change fluid process. 
     If the clean tank  110  becomes empty during the fluid change process, the sounder starts sounding and the solenoid system  160  reverts back to its default recirculating path  167 . In such event, more fluid may be added to the clean fluid tank  110  providing the waste tank level is below ¼ tank full and the change fluid button  230  may be pressed so the system  100  restarts the process from the last point. If LED  162  is lit, waste fluid must be emptied before proceeding. 
     In a preferred embodiment, once the fluid level in the clean fluid tank  110  reaches the low-level line  111 , the change process is complete and the complete LED  252  comes on to indicate the end of process. At the completion of the fluid change process, the solenoid system reverts to its default recirculating path  167  and the transmission fluid circulates through the solenoid switch. 
     At this point, the system  100  may be used to add extra fluid to the transmission system by pressing the fill button  240 , as explained above. 
     At the final stage, the vehicle engine is stopped and the cooler line is disconnected from the first and second hoses  162  and  164  and reconnected in its original form. Pressing the empty waste button  260  on the control panel  200  may also empty the waste tank  120 . 
     Once the empty waste button  260  is pressed, the empty waste LED  262  comes on indicating that the waste tank  120  is being emptied out into the disposal tank  170 . The waste fluid is pumped out the waste tank  120  using the waste fluid pump  140  and via the waste fluid tube  122 , through the waste fluid filter  126  and from there to the disposal tube  145  and the disposal tank  170 . Once the waste tank  120  is emptied, the empty waste LED  262  turns off. The process may also be stopped at any time by pressing the stop button  270 . 
     Turning to FIG. 3, a pictorial representation of a transmission service system  10  is shown. As shown, the service system  10  includes the fluid changer system  100  and the control panel  200 . In addition, the service system includes a fluid port  12  corresponding to the clean tank port  115  for adding or draining fresh fluid. The service system  10  also includes a clean fluid level meter  16  and a waste fluid level meter  14  for visually determining the fluid level in the clean fluid tank  110  and the waste fluid tank  120 , respectively. 
     Those skilled in the art will appreciate that, while the system  100  provides for processes such as draining, filling, changing fluid and emptying waste fluid, it would be possible in accordance with the present invention to design a system that allows for only one or more of the above-described processes. 
     While the present invention is susceptible to various modifications and alternative forms, specific examples thereof have been shown in the drawings and are herein described in detail. It should be understood, however, that the invention is not to be limited to the particular forms or methods disclosed, but to the contrary, the invention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the appended claims.

Technology Classification (CPC): 5