Abstract:
There is provided methods for servicing a vehicle&#39;s transmission cooling system having inlet and outlet ports. An example method comprises the steps of pumping air into an inlet port of the transmission cooling system to cause transmission fluid to flow out of the outlet port of the transmission cooling system; cycling a solvent through the transmission cooling system, where the solvent enters through the inlet port and exits through the outlet port of the transmission cooling system; re-cycling the solvent exiting through the output port through the transmission cooling system; and pumping air into the inlet port to cause the solvent in the transmission cooling system to exit through the outlet port.

Description:
The present application is a divisional application of U.S. application Ser. No. 09/688,552, filed Oct. 16, 2000, now U.S. Pat. No. 6,539,958 which is hereby fully incorporated by reference in the present application. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to the field of vehicle maintenance and repair. More specifically, the invention is directed to servicing transmission cooling systems. 
     2. Related Art 
     It is common for vehicles with automatic transmissions to have a cooling system for the transmission fluid in order to keep the operating temperature of the transmission within a desired range. Most cars, especially larger models, have such a transmission cooling system. Most trucks and vans require a larger transmission cooling system to handle extra stress placed on the transmission by, for example, carrying heavy loads or towing trailers. A typical transmission cooling system is connected to the transmission in such a way that transmission fluid is circulated from the transmission to a transmission fluid cooler through one line, then circulated through the transmission fluid cooler, and returned to the transmission through a second line. 
     A transmission cooling system can include, for example, a transmission fluid cooler inside the vehicle&#39;s radiator, so that the transmission fluid cooler is immersed in the engine coolant inside the radiator. Thus, engine coolant, typically a combination of water and antifreeze, flows over the outside of the transmission fluid cooler while transmission fluid flows on the inside of the transmission fluid cooler. Heat is transferred from the transmission fluid circulating inside the transmission fluid cooler to the engine coolant circulating outside the transmission fluid cooler. Air flow over the outside of the radiator cools the engine coolant. Other cooling devices may also be used, for example, a called a “heat exchanger” may be used in conjunction with or instead of the transmission fluid cooler described above. The transmission fluid cooler is also sometimes referred to as a transmission “oil cooler.” A common design among all these devices is that each circulates fluid from the transmission through the device, in order to cool the fluid, and then returns the cooled fluid to the transmission. Thus, in a transmission cooling system, transmission fluid is circulated from the vehicle&#39;s transmission system, through a transmission fluid cooler which controls the temperature of the transmission fluid, and returns to circulate through the transmission, thereby keeping the transmission within desired operating temperature range. 
     For various reasons such as extended use of the vehicle or transmission failure, the transmission fluid can become “dirty” or contaminated with debris, for example, metal flakes from worn parts inside the transmission. Such debris can accumulate inside the transmission cooling system, in particular, inside the transmission cooler causing it to “clog” or become incapable of sufficient circulation of transmission fluid to provide adequate cooling. Occasionally, a transmission cooler becomes so clogged that it must be replaced. Transmission cooling system clogging can also lead to premature transmission failure. It is, therefore, crucial to clean the transmission cooling system as part of normal periodic transmission servicing. In addition, when a transmission is removed to be rebuilt or replaced with a new or rebuilt transmission, the transmission cooling system is typically cleaned to avoid contamination of the reinstalled transmission. 
     A number of conventional means are available for cleaning transmission cooling systems. One conventional means uses a pressurized container containing a liquid cleaner, for example, a can containing compressed solvent. Use of such means has many disadvantages. For example, the amount of cleaning that can be performed is limited by the amount of solvent and the can pressure, which may require the use and expense of extra cans. In addition, the cleaning liquid is only used once, which is wasteful because cleaning liquid is typically not completely dirty after only one use and can be used again. Disposing cleaning liquid which is capable of being reused is not only wasteful, but is also harmful to the environment. 
     Another disadvantage of using a compressed solvent can is that it does not provide a measure of the effectiveness of the cleaning. As a result, a transmission fluid cooler, which appears to have been cleaned may still be incapable of sufficient circulation of transmission fluid to provide adequate cooling, but may be reused and cause transmission overheating and damage. 
     Other conventional methods of cleaning transmission cooling systems may use air pressure. A source of such air pressure may be a pressurized system of air hoses commonly found in auto repair shops, typically referred to as “shop air,” typically at a pressure of 100.0 to 120.0 pounds per square inch (“psi”). Use of such methods is disadvantageous in that shop air may not be available at the location where the vehicle is to be serviced. Further, high air pressure can present safety concerns for the operators. In addition, shop air methods suffer from other disadvantages, such as using the cleaning liquid only once, which is wasteful because cleaning liquid is typically not completely dirty after only one use and can be used again. As stated above, such wastefulness is also harmful to the environment. 
     Accordingly, there is an intense need in the art for a new cooler flusher method and apparatus that can overcome the disadvantages and drawbacks in the conventional art; that can improve cost, efficiency, and safety; and that can remove environmental concerns. 
     SUMMARY OF THE INVENTION 
     In accordance with the purpose of the present invention as broadly described herein, there is provided method and apparatus for servicing a vehicle&#39;s transmission cooling system. 
     In one aspect of the present invention, a service apparatus, for servicing a vehicle&#39;s transmission cooling system, includes a source valve with inlet and outlet ports, a pump with inlet and outlet ports, and a return valve with inlet and outlet ports. The pump inlet is connected to the source valve outlet. The pump pumps fluid from the source valve inlet through the source valve outlet and the pump inlet to the pump outlet for servicing the transmission cooling system. The fluid returns from the return valve inlet to the return valve outlet and the pump then re-pumps the fluid into the transmission cooling system. 
     In another aspect, the service apparatus further includes a fluid source and a filter interposed between the fluid source and the source valve. In yet another aspect, the fluid returns to the fluid source prior to re-pumping the fluid. In one aspect, the service apparatus also includes a flowmeter interposed between the return valve and the fluid source and a filter interposed between the return valve and the flowmeter 
     In one aspect of the present invention, the source valve inlet may also function as an air inlet. In yet another aspect, the source valve includes an air inlet and the return valve includes a waste outlet. 
     The service apparatus of the present invention can be used to perform a service method comprising the steps of pumping air into an inlet port of transmission cooling system to cause transmission fluid to flow out of an outlet port of the transmission cooling system; cycling a solvent through the transmission cooling system, where the solvent enters through the inlet port and exits through the outlet port of the transmission cooling system; re-cycling the solvent exiting through the output port through the transmission cooling system; and pumping air into the inlet port to cause the solvent in the transmission cooling system to exit through the outlet port. 
     These and other aspects of the present invention will become apparent with further reference to the drawings and specification, which follow. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  illustrates a front view of a cooler flusher system according to one embodiment of the present invention; 
         FIG. 1B  illustrates a left side view of the cooler flusher system of  FIG. 1A ; 
         FIG. 1C  illustrates a right side view of the cooler flusher system of  FIG. 1A ; 
         FIG. 1D  illustrates an example control panel of the cooler flusher system of  FIG. 1A ; 
         FIG. 2  illustrates a fluid flow schematic diagram of the cooler flusher system of  FIG. 1A ; 
         FIG. 3  illustrates a flowchart of the steps used to service a transmission cooling system using the cooler flusher system of  FIG. 1A ; and 
         FIG. 4  illustrates an electrical schematic diagram of the cooler flusher system of FIG.  1 A. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The following description contains specific information pertaining to the implementation of the present invention. One skilled in the art will recognize that the present invention may be implemented in a manner different from that specifically discussed in the present application. Moreover, some of the specific details of the invention are not discussed in order to not obscure the invention. The specific details not described in the present application are within the knowledge of a person of ordinary skill in the art. 
     The drawings in the present application and their accompanying detailed description are directed to merely example embodiments of the invention. To maintain brevity, other embodiments of the invention which use the principles of the present invention are not specifically described in the present application and are not specifically illustrated by the present drawings. 
       FIG. 1A  shows a cooler flusher system according to one embodiment of the present invention.  FIGS. 1A ,  1 B, and  1 C show cooler flusher system  100  from the front and also from a left side view and a right side view for greater clarity. As shown in  FIG. 1A , cooler flusher system  100  includes pressure hose  102  for delivering solvent or air under pressure to a transmission cooling system (not shown). Pressure is supplied from a pump internal to cooler flusher system  100 , discussed in more detail below with reference to FIG.  2 . The solvent can be, for example, mineral spirits or commercially available biodegradable soap-like solution, or any other suitable cleaning fluid. Cooler flusher system  100  also includes return hose  104  for the return of fluid, either transmission fluid or solvent, from the transmission cooling system. The fluid returned from the transmission cooling system through return hose  104  can be directed to waste hose  106  or to fluid tank  108 . Contaminated fluid, for example, debris-laden transmission fluid, is directed through waste hose  106  to a receptacle for disposal. Reusable fluid, for example, solvent, is directed to fluid tank  108 . 
     Cooler flusher system  100  further includes filters  112  and  114 . Filter  112  filters solvent before it is delivered to pressure hose  102 . Filter  112  can be a relatively fine filter, i.e. one which traps all particles greater than some small size, such as a paper filter or a fine screen mesh. Filter  114  filters solvent after it is returned through return hose  104 . Filter  114  can be a relatively coarse filter, i.e. one which traps particles of greater size than the paper filter is designed for, such as a screen filter. The purpose of filter  114  is to provide a filter that is less susceptible to clogging and which, therefore, needs cleaning or replacing less often. Further, filter  114  filters out larger size particles from the solvent stream that passes through filter  112 . Filters  112  and  114  will keep the solvent clean for longer use and prevent premature failure of cooler flusher system  100 . Cooler flusher system  100  also includes power cables  116  for supplying power to the pump. Cooler flusher system  100  also includes front panel  120 . 
     Referring now to  FIG. 1D , front panel  120  of  FIG. 1A  is shown in more detail. As seen in  FIG. 1D , front panel  120  includes source valve  122  for directing flow to pressure hose  102  from either of fluid tank  108  or an air inlet check valve (not shown in FIG.  1 D). Source valve  122  is also provided with an “off” position which prevents flow through source valve  122 . Front panel  120  also includes return valve  124  for directing flow from return hose  104  to either of waste hose  106  or fluid tank  108 . Return valve  124  is also provided with an “off” position which prevents flow through return valve  124 . Front panel  120  also includes flow meter  128  for measuring flow of fluid through the transmission cooling system.  FIG. 1D  also shows that control panel  120  includes power switch  132 , indicator light  134 , and circuit breaker  136 . Power switch  132 , indicator light  134 , and circuit breaker  136  are discussed in more detail below with reference to FIG.  4 . 
     Flow diagram  200  of  FIG. 2  illustrates pressure hose  202  of cooler flusher system  100  connected to transmission cooling system  201  via, hydraulic connector  203 . Return hose  204  of cooler flusher system  100  is connected to transmission cooling system  201  via hydraulic connector  205 . Hydraulic connectors  203  and  205  can be standard connectors as known in the art or other means such as hoses and clamps. Pressure hose  202  can be any hose capable of supporting the pressure delivered by pump  238 . For example, typical pressure is in the range of approximately 15.0 psi (pounds per square inch) to 50.0 psi. Return hose  204  may be any suitable hose for returning transmission fluid or solvent from transmission cooling system  201 . 
     Return hose  204  delivers fluid to return valve  224  for directing flow from return hose  204  to either of waste hose  206  or fluid tank  208 . For example, return valve  224  can be a three-way valve with an “off” position, an “evacuate” position, and a “flush” position. In one embodiment, the three-way valve may include one inlet port and two outlet ports. As shown, the inlet port of return valve  224  may receive fluid from transmission cooling system  201 , which fluid may then flow out of either of the outlet ports depending on the position of return valve  224 . The “off” position can be used to prevent all flow through valve  224 ; the “evacuate” position can be used to direct flow from return hose  204  to waste hose  206  when removing transmission fluid from transmission cooling system  201 ; and the “flush” position can be used to direct flow from return hose  204  to fluid tank  208  when pumping solvent from fluid tank  208 , through transmission cooling system  201 , and back to fluid tank  208 . Waste hose  206  can be any suitable hose for delivering transmission fluid from return valve  224  to a waste or recycling receptacle. Fluid tank  208  can be any suitable container for holding the solvent or other cleaning fluid used to clean transmission cooling system  201 . 
     In one embodiment, filter  214  and flow meter  228  are interposed between return valve  224  and fluid tank  208 . For example, filter  214  can be a screen filter for filtering coarse size particles from the solvent as discussed above. Flow meter  228  can be any device capable of measuring the flow of solvent through transmission cooling system  201  and providing a satisfactory read out to an operator. 
     Continuing with  FIG. 2 , flow diagram  200  shows source valve  222  for directing flow to pump  238  from either of fluid tank  208  or check valve  240 . For example, source valve  222  can be a three-way valve with an “off” position, an “air/recover” position, and a “flush” position. In one embodiment, the three-way valve may include two inlet ports and an outlet port, where one inlet may provide air and the other provide liquid or fluid. As shown, the outlet port of source valve  222  is connected to an inlet of pump  238 , which can pump fluid or air from inlet of pump  238  to an outlet of pump  238 . The “off” position can be used to prevent all flow through source valve  222 ; the “air/recover” position can be used to direct air flow from check valve  240  to pump  238  when removing transmission fluid from transmission cooling system  201 ; and the “flush” position can be used to direct liquid flow from fluid tank  208  to pump  238  when pumping solvent from fluid tank  208 , through transmission cooling system  201 , and back to fluid tank  208 . Check valve  240  can be any suitable one-way flow device for allowing a flow of air into source valve  222  and preventing any backflow of fluid from source valve  222  and out of cooler flusher system  100 . Thus, the “air/recover” position of source valve  222  can be used to direct a flow of air from check valve  240  to pump  238  when removing transmission fluid from transmission cooling system  201 . In an alternative mode of operation, the “flush” position of source valve  222  can be used to direct a flow of solvent from fluid tank  208  to pump  238  when removing larger amount of transmission fluid from transmission cooling system  201 . 
     Flow diagram  200  further shows pump  238  for supplying pressure for flow of air or fluid through cooler flusher system  100  and transmission cooling system  201 . In one embodiment, filter  212  is interposed between fluid tank  208  and source valve  222 . For example, filter  212  can be a paper filter for filtering fine size particles from the solvent as discussed above. 
       FIG. 3  shows flowchart  300  for describing example steps for cleaning a transmission cooling system  201  using cooler flusher system  100 . Certain details and features, which are apparent to a person of ordinary skill in the art, have been left out of flowchart  300 , for example, a step may consist of one or more sub-steps or may involve specialized tools, as known in the art. 
     As shown in  FIG. 3 , step  302  of flowchart  300  comprises disconnecting transmission cooling system  201  from a vehicle&#39;s transmission. For example, the transmission fluid lines may both be disconnected at the oil cooler of transmission cooling system  201 . Subsequent to step  302 , inlet and outlet ports of transmission cooling system  201  are available for connecting to pressure hose  102  and return hose  104  of cooler flusher system  100 . 
     Step  304  of flowchart  300  comprises connecting cooler flusher system  100  to transmission cooling system  201 . Pressure hose  202  may be connected to either inlet port or outlet port of transmission cooling system  201  using hydraulic connector  203 . Return hose  204  is connected to the other port of transmission cooling system  201  using hydraulic connector  205 . Thus, subsequent to step  304 , transmission cooling system  201  has its inlet port connected to pressure hose  202  and its outlet port connected to return hose  204  of cooler flusher system  100 . 
     Next, in step  306 , cooler flusher system  100  is connected to a source of electrical power and waste hose  206  is directed to a suitable receptacle. For example, power cables  116  of cooler flusher system  100  shown in  FIG. 1A  can be connected to the vehicle&#39;s battery. Power cables  116  may also be connected, for example, to any automobile battery or power source. The free end of waste hose  206  can be placed, for example, in an auto service shop&#39;s hydraulic fluid recycling receptacle. Subsequent to step  306  of flowchart  300 , then, cooler flusher system  100  is connected to a source of power for pump  238  of cooler flusher system  100 , waste hose  206  is properly placed for collection of transmission fluid, and cooler flusher system  100  is connected to transmission cooling system  201  so that cleaning of transmission cooling system  201  may commence. 
     Step  308  of flowchart  300  comprises setting source valve  222  and return valve  224  to configure cooler flusher system  100  for evacuating transmission fluid from transmission cooling system  201 . Return valve  224  is set to the “evacuate” position to direct flow from return hose  204  to waste hose  206 . Source valve  222  is then set to the “air/recover” position to direct a flow of air into pressure hose  202 . Power switch  132 , shown in  FIG. 1D , is then set to the “on” position to start pump  238  of cooler flusher system  100 . The pump can be run for a sufficient length of time to remove substantially all the transmission fluid from transmission cooling system  201 . For example, waste hose  206  can be made of a transparent material suitable for viewing whether transmission fluid or air is flowing through waste hose  206 . When it is clear that substantially all transmission fluid has been removed from transmission cooling system  201 , power switch  132  is set to the “off” position to stop pump  238  of cooler flusher system  100 . 
     If, during step  308  of flowchart  300 , it becomes apparent that the flow of pressurized air is insufficient to satisfactorily evacuate transmission fluid from transmission cooling system  201 , an alternative mode of operation of cooler flusher system  100  may be followed. Observation of whether flow of pressurized air is insufficient to satisfactorily evacuate transmission fluid from transmission cooling system  201  is illustrated in flowchart  300  by decision step  310 . The alternative mode of operation is shown in flowchart  300  as step  312 . At step  310 , if it is observed that flow of pressurized air is sufficient to satisfactorily evacuate transmission fluid from transmission cooling system  201 , then cleaning of transmission cooling system  201  proceeds with step  314  directly after step  308 . If, at step  310 , it is observed otherwise that flow of pressurized air is insufficient to satisfactorily evacuate transmission fluid from transmission cooling system  201 , then cleaning of transmission cooling system  201  can proceed with step  312  directly after step  308 . 
     Step  312  of flowchart  300  comprises setting source valve  222  to the “flush” position to direct a flow of solvent into pressure hose  202 . It should be noted that return valve  224  is already set to the “evacuate” position to direct flow from return hose  204  to waste hose  206  as part of step  308 . Power switch  132  is then set to the “on” position to start pump  238  of cooler flusher system  100 . Pump  238  can be run for a sufficient length of time to remove substantially all the transmission fluid from transmission cooling system  201 . When it is observed, for example, by viewing through transparent waste hose  206 , that substantially all transmission fluid has been removed from transmission cooling system  201 , power switch  132  is set to the “off” position to stop pump  238  of cooler flusher system  100 . Accordingly, after step  308 , or alternatively, after steps  308  and  312 , transmission cooling system  201  has been substantially cleared of transmission fluid and is ready for cleaning. 
     Step  314  of flowchart  300  comprises setting source valve  222  and return valve  224  to configure cooler flusher system  100  for cleaning transmission cooling system  201  by flushing it with solvent. Return valve  224  is set to the “flush” position to direct flow from return hose  204  to fluid tank  208 . Source valve  222  is then set to the “flush” position to direct a flow of fluid from fluid tank  208  to pressure hose  202 . Power switch  132  is then set to the “on” position to start pump  238  of cooler flusher system  100 . Solvent is then continuously cycled through transmission cooling system  201  and fluid tank  208  of cooler flusher system  100 . Pump  238  of cooler flusher system  100  can be run for a sufficient length of time to remove substantially all contamination and blockage from transmission cooling system  201 . For example, a period of 5 to 10 minutes has been determined to be sufficient in most cases to adequately clean a typical transmission cooling system. An alternative to using a predetermined period of time for running pump  238  of cooler flusher system  100  is to measure the flow of solvent through flow meter  228  and stop pump  238  according to various methods utilizing such measurement. For example, one method is to measure improvement in the flow through flow meter  228 . As long as flow is improving, i.e. increasing, solvent is cycled through transmission cooling system  201 . When improvement of flow slows substantially or stops, that is taken as an indication that no more improvement is to be had, and therefore, transmission cooling system  201  has been cleaned. Another method, for example, may be to measure the numerical value of flow of solvent through flow meter  228  and compare that value to a specification for the particular transmission cooling system at hand. Typical specification values for flow through transmission cooling systems are in the range of approximately 1.0 to 2.0 gallons per minute. If flow is below the specification, then solvent is cycled through transmission cooling system  201 . If flow is satisfactorily close to the specification, then that is taken as an indication that transmission cooling system  201  has been cleaned. Thus, measurement of the flow of fluid through transmission cooling system  201  can provide indications, for example, of how much time is required to clean transmission cooling system  201 , whether transmission cooling system  201  is adequately clean, or whether portions of transmission cooling system  201 , such as the oil cooler, need to be replaced. When it has been decided that transmission cooling system  201  has been cleaned or, alternatively, that transmission cooling system  201  cannot be adequately cleaned and needs to be replaced, power switch  132  is set to the “off” position to stop pump  238  of cooler flusher system  100 . Subsequent to step  314  of flowchart  300 , transmission cooling system  201  contains solvent which should be recovered to fluid tank  208  of cooler flusher system  100 . 
     Step  316  of flowchart  300  comprises setting source valve  222  and return valve  224  to configure cooler flusher system  100  for recovering solvent from transmission cooling system  201 . Return valve  224  is set to the “flush” position to direct flow from return hose  204  to fluid tank  208 . Source valve  222  is set to the “air/recover” position to direct a flow of air into pressure hose  202 . Power switch  132  is set to the “on” position to start pump  238  of cooler flusher system  100 . Pump  238  can be run for a sufficient length of time to recover substantially all the solvent from transmission cooling system  201 . When it is clear that substantially all solvent has been recovered from transmission cooling system  201 , power switch  132  is set to the “off” position to stop pump  238  of cooler flusher system  100 . Subsequent to step  316  of flowchart  300 , transmission cooling system  201  has been cleaned or it has been decided that transmission cooling system  201  is no longer fit for service. In either case, cooler flusher system  100  is disconnected from transmission cooling system  201 , and from the vehicle&#39;s battery if that was used. If transmission cooling system  201  is fit for service, a further step may be taken, for example, of flushing a small amount of transmission fluid through transmission cooling system  201  to remove residual solvent, which may be present after completion of step  316  of flowchart  300 , before reconnecting transmission cooling system  201  to the transmission on the vehicle. Thus, after completion of step  316  of flowchart  300 , transmission cooling system  201  is reconnected to the vehicle or a replacement transmission cooling system is provided. 
     Referring now to  FIG. 4 , electrical schematic diagram  400  is shown for one embodiment of the present invention. Electrical schematic diagram  400  shows electrical connections of components for supplying electric power to the pump of cooler flusher system  100  according to one embodiment of the present invention. 
     As shown in  FIG. 4 , power cables  416  in electrical schematic  400  are connected to a source of electrical power suitable for operating pump  438  at the desired operating capacity. For example, the source of electrical power can be a car battery, as discussed above. Electrical schematic  400  also shows power switch  432  for controlling pump  438 . Thus, pump  438  can be started by moving the position of switch  432  from “off” to “on” or stopped by moving the position of switch  438  from “on” to “off.” Diagram  400  also shows indicator light  434  wired in series with switch  432  so that indicator light  434  is lit whenever switch  432  is in the “on” position. Indicator light  434  provides a safety feature for the operator to know whether power is connected when switch  432  is in the on position. Indicator light  434 , for example, can be a very low power amber lamp. Switch  432  is isolated from pump  438  by relay  435  in a standard manner. Thus, switch  432  can be, for example, a toggle switch capable of handling enough power to power relay  435  and indicator light  434 . Relay  435  can be, for example; a simple relay capable of handling enough power to power pump  438 . Electrical schematic  400  also shows circuit breaker  436  wired in series with the source of electrical power in order to protect all electrical components of electrical schematic  400 . Circuit breaker  436 , for example, can be a fuse of a proper rating or a standard switch type circuit. 
     Thus, according to one embodiment of the present invention, cooler flusher system  100  provides a means for cleaning transmission cooling systems in which the cleaning fluid or solvent can be repeatedly and continuously flushed through the transmission cooling system in order to ensure adequate cleaning. Because of the cycling of solvent, cooler flusher system  100  provides flexibility in that the amount of cleaning can be adjusted to each particular transmission cooling system by adjusting the amount of time, that solvent is cycled through a transmission cooling system. For example, a dirtier transmission cooling system may require, and can receive, more cleaning by cycling solvent for a longer period of time. Moreover, because of cycling the solvent, cooler flusher system  100  provides more economical cleaning in that the same solvent can be effectively used for many vehicles. Cycling of solvent also avoids other disadvantages of using the cleaning liquid only once, for example wastefulness. Using the cleaning liquid only once can be wasteful because cleaning liquid is typically not completely dirty after only one use and can be used again. Reuse of cleaning fluid through cycling of solvent avoids premature disposal of cleaning fluid, which is beneficial to the environment. 
     Various techniques may be used for implementing the concepts of the present invention without departing from its scope. While the present invention has been described with specific reference to certain embodiments, a person of ordinary skills in art would recognize that changes can be made in form and detail without departing from the spirit and the scope of the invention. The described embodiments are to be considered in all respects as illustrative and not restrictive. It should also be understood that the invention is not limited to the particular embodiments described herein, but is capable of many rearrangements, modifications, and substitutions without departing from the scope of the invention.