Abstract:
A system and method for removing liquids from engines, the system including first and second liquid storage tanks that are disposed for serial flow therebetween, a pressure source, and a vacuum source. The first liquid storage tank is continuously connected to the vacuum source, while the second liquid storage tank is alternatively connected to either the vacuum source, during filling, or the pressure source, during draining. Opening and closing the valves is controlled in response to sensed liquid levels in the tanks.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a method and system for removing oil and gasoline from an engine. 
     2. Description of Related Art 
     It is common for small four stroke engines used in outdoor power equipment, such as lawn mowers, edgers, chippers, generators, and power washers, to be manufactured in dedicated factories that are remote from the final assembly plant. The completed engines are then periodically shipped to the final assembly plant. 
     Manufacturers of power equipment often require that the engines be started prior to shipment. This helps insure that the engines will work when they are ultimately assembled into the power equipment. Therefore, the engine manufacturer must include means for starting the engines prior to shipment, which entails filling the engine crankcase with oil and at least partially filling the fuel tank with gasoline. 
     Thereafter, in order to prevent spills and leaks, the engines must be drained of gasoline and oil before being packaged for shipment. Due to the viscosity of oil and the speed at which the engines must be drained, it has heretofore proven necessary to use a pump to evacuate oil and gasoline from the engines. The pumped-out oil and gasoline is directed toward an oil recovery tank and a gas recovery tank, respectively, for recycling and/or re-use. 
     In the past, oil and gas have been pumped out of the engine by pumps that are in the flow line between the crankcase and the oil recovery tank, in the case of oil, or in the flow line between the fuel tank and the gas recovery tank, in the case of gasoline. However, this prior art method and system has proven unreliable as the pumps have required relatively frequent maintenance and repair. It is believed that oil and gasoline damage the pump seals, resulting in leakage problems, frequent repair, and excessive downtime. 
     Therefore, there exists a need in the art for a method and system for quickly and reliably removing oil and gasoline from an engine. 
     SUMMARY OF THE INVENTION 
     The present invention is directed toward an improved method and system for removing oil and gasoline from an engine. 
     In accordance with the present invention, a system for removing liquid from an engine includes a first liquid storage tank, a second liquid storage tank, a return tank, a vacuum source, and a pressurized air source. Fluid communication between the tanks and the pressure and vacuum sources is controlled by a controller that actuates valves in response to sensed liquid levels in the first and second liquid storage tanks. 
     In further accordance with the present invention, a first conduit, which is adapted for insertion into an engine reservoir that contains liquid to be removed, provides liquid to the first liquid storage tank. A second conduit extends between and fluidly interconnects the first and second liquid storage tanks. A first control valve is disposed in the second conduit and serves to control fluid communication therethrough. 
     In further accordance with the present invention, the vacuum source establishes a vacuum or sub-atmospheric pressure in the first and second liquid storage tanks while the pressurized air source selectively communicates pressurized or over-atmospheric pressure air to the second liquid storage tank. Preferably, vacuum is continuously provided to the first liquid storage tank while pressurized air and vacuum are supplied to the second liquid storage tank in a mutually exclusive fashion. 
     In accordance with other aspects of the invention, sensors are provided for sensing liquid levels in the first and second liquid storage tanks. Also, a controller actuates the first and second valves and controls communication of pressurized air from said pressure source, in response to sensed liquid levels. 
     The present invention also teaches a method for removing liquids from an engine reservoir. The method includes communicating vacuum to the first and second liquid storage tanks and inserting a nozzle of a first conduit into the engine reservoir. The first conduit includes a nozzle valve for controlling communication of liquid from the engine reservoir to the first liquid storage tank via the first conduit. 
     In further accordance with the method, a first control valve is placed in a first position to permit liquid to flow from the first liquid storage tank to the second liquid storage tank. The level of liquid in the first and second liquid storage tanks is monitored. 
     In further accordance with the inventive method, when the liquid level in the second liquid storage tank reaches a first predetermined level, the first control valve is placed in a second position to prevent liquid flow from the first liquid storage tank to the second liquid storage tank, communication of vacuum sub-atmospheric pressure air to the second liquid storage tank is discontinued, and pressurized or over-atmospheric pressure air is communicated to the second liquid storage tank to force liquid therein to flow through the third conduit toward the return tank. 
     In accordance with another aspect of the method, when the liquid level in one of the first and second liquid storage tanks reaches a second predetermined level, the communication of over-atmospheric pressure air to the second liquid storage tank is discontinued, communication of sub-atmospheric pressure air to the second liquid storage tank is reestablished, and the first control valve is returned to the first position to permit liquid to flow from the first liquid storage tank to the second liquid storage tank. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     These and further features of the invention will be apparent with reference to the following description and drawings, wherein: 
     FIG. 1 is a schematic diagram of a system according to a first preferred embodiment of the present invention; 
     FIG. 2 is a schematic diagram of a system according to a second preferred embodiment of the present invention; 
     FIG. 3 is a flow chart illustrating operating steps using the first embodiment of the present invention; and, 
     FIG. 4 is a flow chart illustrating operating steps using the second embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     With reference to FIG. 1, a first preferred embodiment of a system according to the present invention is illustrated. The system includes a first liquid storage tank  10 , a second liquid storage tank  12 , a return tank  14 , a first control valve  16 , a second control valve  18 , a pressure source  20 , a vacuum source  22 , and a series of conduits  24 ,  26 ,  28 ,  30 ,  32 ,  34 . 
     The first liquid storage tank  10  is connected to an outlet  24   a  of a first conduit  24 , which serves as a liquid inlet and includes an inlet nozzle  24   b  having a manually-operated inlet nozzle valve (not shown). The first conduit  24  has a check valve  24   c  disposed therein to prevent reverse flow therethrough. The inlet nozzle  24   b  is designed for insertion into an engine reservoir, such as a crankcase or fuel tank, and the nozzle valve is opened and closed by a user to permit communication of suction to the inlet nozzle  24   b  and thereby withdraw liquids from the engine reservoir. Liquids flowing through the inlet conduit  24  are delivered to the first liquid storage tank  10 . 
     The first liquid storage tank  10  is fluidly connected to the second liquid storage tank  12  via a second conduit  26  and is connected to the vacuum source  22  via a first vacuum conduit  28 . Preferably, the second conduit  26  is connected, at opposite ends, to bottom ends of the first and second liquid storage tanks  10 ,  12 , respectively. The second conduit  26  has the first control valve  16  disposed therein to control liquid flow through the second conduit  26  from the first liquid storage tank  10  toward the second storage tank  12 . The first control valve  16  is movable between a first position establishing fluid communication between the first and second liquid storage tanks  10 ,  12  and a second position blocking fluid communication between the storage tanks  10 ,  12 . 
     The first vacuum conduit  28  is connected to a top of the first liquid storage tank  10 . A flow director or shield  10   a  is preferably provided within the first liquid storage tank  10  to prevent liquid from being drawn through the first vacuum conduit  28 . A first float-type switch  10   b  is secured to the first liquid storage tank  10  at a predetermined location between the top and bottom ends thereof. Naturally, it is considered apparent that means other than the first float-type switch  10   b  disclosed herein may be used with equal functionality without departing from the scope and spirit of the present invention. 
     The second liquid storage tank  12  is disposed vertically below the first liquid storage tank  10  and receives liquids from the first liquid storage tank  10  by means of the second conduit  26  and the first control valve  16 . The second liquid storage tank  12  is also connected to the return tank  14  by means of an outlet conduit  36 . Preferably, a check valve  36   a  is disposed in the outlet conduit  36 , as illustrated, to prevent reverse flow of liquid in the outlet conduit  36 . 
     The second liquid storage tank  12  is also connected to the vacuum source  22  and to the pressure source  20  by means of the second control valve  18 , a second vacuum conduit  32 , a first pressure conduit  30 , and a common conduit  34 . More specifically, and as illustrated in FIG. 1, the second vacuum conduit  32  and first pressure conduit  30  connect the vacuum and pressure sources  22 ,  20 , respectively, to inlets of the second control valve  18 , while the common conduit  34  extends from an outlet of the second control valve  18  to the second liquid storage tank  12 . The second control valve  18  is selectively movable between a first position establishing communication between the vacuum source  18  and the second liquid storage tank  12  and a second position establishing communication between the pressure source  20  and the second liquid storage tank  12 . 
     A second float-type switch  12   a  is secured to the second liquid storage tank  12  at a vertical location that is relatively between the top and bottom ends of the tank  12 . As noted hereinbefore, it is considered apparent that means other than the second float-type switch  12   a  disclosed herein may be used with equal functionality without departing from the scope and spirit of the present invention. 
     A controller  38  is provided to control operation of the first and second control valves  16 ,  18  in response to the volume of liquid in each of the first and second liquid storage tanks  10 ,  12  as sensed by the first and second float-type switches  10   b,    12   a.  The system of the present invention is intended for use as part of a manufacturing process wherein, following starting of the engines, the oil and gasoline therein must be evacuated to facilitate subsequent handling and shipment of the engine. In that light, and keeping in mind that the oil and gasoline evacuation systems are maintained separately, operation of the system will be described hereinafter with reference to the flow chart of FIG.  3  and the foregoing description of the system. 
     The description of the operation of the system presumes an initial condition wherein the first control valve  16  is in the first position establishing communication between the first and second liquid storage tanks  10 ,  12  and the second control valve  18  is in the first position establishing communication between the vacuum source  22  and the second liquid storage tank  12 . As such, under-atmospheric pressure is provided to the first and second liquid storage tanks  10 ,  12 . When an engine to be evacuated is brought to the system, the inlet nozzle  24   b  is inserted into the engine reservoir (i.e., crankcase or fuel tank) and the inlet nozzle valve is opened to draw the liquid through the first conduit  24  and into the first liquid storage tank  10 . The liquid subsequently flows, at least partly due to gravity, through the second conduit  26  and first control valve  16  and into the second liquid storage tank  12 , and begins filling the second liquid storage tank  12  (step  200 ). 
     This continues until, after a number of engine reservoirs are emptied, the second liquid storage tank  12  fills to the point that the second float-type switch  12   a  is actuated. This causes the controller  38  to move the first and second control valves  16 ,  18  from their first position to their second position. Moving the first control valve  16  to it&#39;s second position blocks communication between the first and second liquid storage tanks  10 ,  12 . Placing the second control valve  18  in its second position places the pressure source  20  in communication with the second liquid storage tank  12 , and thereby establishes an over-atmospheric pressure in the second liquid storage tank  12 . The pressure thus established above the liquid in the second storage tank  12  forces the liquid in the second storage tank  12  to flow through outlet conduit  36  and into the return tank  14 , emptying the second storage tank  12  (step  202 ). 
     While the second storage tank  12  is being emptied, under-atmospheric pressure is still communicated to the first liquid storage tank  10 , and the system continues to be used for evacuating engine reservoirs. Since the first control valve  16  is closed, the liquid evacuated from the engine reservoirs is retained in the first liquid storage tank  10 . After a number of engine reservoirs are emptied, the first float-type switch  10   b  is actuated, causing the controller  38  to move the first and second control valves  16 ,  18  from their second positions back to their first positions. Moving the second control valve  18  to the first position removes pressure from the second liquid storage tank  12 , and communicates under-atmospheric pressure or vacuum to the second liquid storage tank  12 . Moving the first control valve  16  to the first position reestablishes fluid communication between the first and second liquid storage tanks  10 ,  12 , and therefore permits liquid to again flow through the second conduit  26  and first control valve  16  (from the first liquid storage tank  10  to the second liquid storage tank  12 ; return to step  200 ). 
     Naturally, it is contemplated that a vent may be provided such that the second liquid storage tank  12  will be briefly vented to atmosphere when switched from the pressure source  20  to the vacuum source  22 . Moreover, it is contemplated that a brief time delay may be provided by the controller  38  wherein the second control valve  18  may return to it&#39;s first position shortly before the first control valve  16  returns to it&#39;s first position. 
     Following return of the control valves  16 ,  18  to their first positions, the second liquid storage tank  12  fills with liquid previously contained in the first liquid storage tank  10 , as well as liquid added to the system from subsequently evacuated engine reservoirs. The system thus continues filling the second liquid storage tank  12  and then, while draining the second liquid storage tank  12  into the return tank  14 , filling the first liquid storage tank  10 . As will be apparent to those skilled in the art, the available volumes of the first and second liquid storage tanks  10 ,  12  (i.e., the volumes available before the associated float-type limit switches  10   b,    12   a  are actuated) may be selected within wide limits and, for example, can be selected or tuned to the expected throughput of the system based upon the available space for the first and second liquid storage tanks  10 ,  12  in the manufacturing environment. Preferably, the tank sizes are selected such that, considering normal operating cycles, the second liquid storage tank  12  is completely emptied before the first liquid storage tank  10  is filled, and such that the available volume of the first liquid storage tank  10  may be completely received within the available volume of the second liquid storage tank  12 . 
     With reference to FIG. 2, a second preferred embodiment of the present invention is illustrated. The second preferred embodiment differs from the first embodiment described hereinbefore by providing dedicated control valves for controlling communication of vacuum or sub-atmospheric pressure and pressurized or over-atmospheric pressure air to the second liquid storage tank, as will be apparent from the following description. 
     The system according to the second embodiment includes a first liquid storage tank  110 , a second liquid storage tank  112 , a return tank  114 , a first control valve  116 , a second control valve  118 , a third control valve  119 , a pressure source  120 , a vacuum source  122 , and a series of conduits  124 ,  126 ,  128 ,  130 ,  132 ,  134 . 
     The first liquid storage tank  110  is connected to an outlet  124   a  of a first conduit  124 , which serves as a liquid inlet and includes an inlet nozzle  124   b  having an inlet nozzle valve (not shown). The first conduit  124  has a check valve  124   c  disposed therein to prevent reverse flow therethrough. The inlet nozzle  124   b  is designed for insertion into an engine reservoir, such as a crankcase or fuel tank, and the nozzle valve is opened and closed by a user to permit communication of suction to the inlet nozzle  124   b  and thereby withdraw liquids from the engine reservoir. Liquids flowing through the inlet conduit  124  are delivered to the first liquid storage tank  110 . 
     The first liquid storage tank  110  is fluidly connected to the second liquid storage tank  112  via a second conduit  126  and is connected to the vacuum source  122  via a first vacuum conduit  128 . Preferably, the second conduit  126  is connected at one end to a bottom of the first liquid storage tank  110  and, at the other end, to the top of the second liquid storage tank  112 , as illustrated. The second conduit  126  has a first control valve  116  disposed therein to control liquid flow through the second conduit  126  from the first liquid storage tank  110  toward the second storage tank  112 . The first control valve  116  is movable between a first position establishing fluid communication between the first and second liquid storage tanks  110 ,  112  and a second position blocking fluid communication between the storage tanks  110 ,  112 . 
     The first vacuum conduit  128  is connected to a top of the first liquid storage tank  110 . A first liquid level sensor  110   b  is associated with the first liquid storage tank  110  and serves to sense the level of liquid therein. In this embodiment the sensor is preferably a scale-type sensor that monitors the weight of the first liquid storage tank  110 . Such a sensor arrangement may be more reliable, over time, in challenging environments. Naturally, it is considered apparent that means other than the illustrated and preferred sensor may be used with equal functionality without departing from the scope and spirit of the present invention. 
     The second liquid storage tank  112  is disposed vertically below the first liquid storage tank  110  and receives liquids from the first liquid storage tank  110  by means of the second conduit  126  and the first control valve  116 . The second liquid storage tank  112  is also connected to the return tank  114  by means of an outlet conduit  136  that extends from a bottom of the tank  112 . Preferably, a check valve  136   a  is disposed in the outlet conduit  136 , as illustrated, to prevent reverse flow of liquid in the outlet conduit  136 . 
     The second liquid storage tank  112  is also connected to the vacuum source  122  and to the pressure source  120 . More specifically, and as illustrated in FIG. 2, the vacuum source  122  is connected to the second liquid storage tank  112  by means of the second control valve  118 , a second vacuum conduit  132 , and a common conduit  134  while the pressure source  120  is connected to the second liquid storage tank  112  by means of the third control valve  119 , a pressure conduit  130 , and the common conduit  134 . 
     The second and third control valves  118 ,  119  are dedicated to controlling communication from the pressure and vacuum sources  120 ,  122 , respectively. However, as will be appreciated from the following description, the second and third control valves  118 ,  119  are operated by the controller  138  in a synchronous fashion. As such, the second control valve  118  is movable between a first position wherein the vacuum source  122  is in communication with the second liquid storage tank  112  and a second position wherein the vacuum source  122  is not in communication with the second tank. Similarly, the third control valve  119  is movable between a first position wherein communication of pressurized air from the pressure source  120  to the second liquid storage tank  112  is prevented and a second position wherein the pressure is communicated to the second liquid storage tank  112 . When the second control valve  118  is in it&#39;s first position the third valve  119  is in it&#39;s first position and, when the second control valve  118  is in it&#39;s second position the third valve  119  is in it&#39;s second position. 
     The second liquid storage tank  112  also has a scale-type sensor/transducer  112   a  wherein the level of liquid in the tank is correlated to the weight of the tank. As noted hereinbefore, it is considered apparent that means other than the scale-type sensor  112   a  may be used with equal functionality without departing from the scope and spirit of the present invention. 
     A controller  138  is provided to control operation of the first, second, and third control valves  116 ,  118 ,  119  in response to the volume of liquid in each of the first and second liquid storage tanks  110 ,  112  as sensed by the sensors  110   b,    112   a.  Operation of the system will be described hereinafter with reference to the flow chart of FIG.  4  and the foregoing description of the system. 
     The description of the operation of the system presumes an initial condition wherein the first control valve  116  is in the first position establishing communication between the first and second liquid storage tanks  110 ,  112 , the second control valve  118  is in the first position establishing communication between the vacuum source  122  and the second liquid storage tank  112 , and the third control valve  119  is in the first position preventing communication between the pressure source  120  and the second liquid storage tank  112 . As such, under-atmospheric pressure is provided to the first and second liquid storage tanks  110 ,  112 . When an engine to be evacuated is brought to the system, the inlet nozzle  124   b  is inserted into the engine reservoir (i.e., crankcase or fuel tank) and the inlet nozzle valve is opened to draw the liquid through the first conduit  124  and into the first liquid storage tank  110 . The liquid subsequently flows, at least partly due to gravity, through the second conduit  126  and first control valve  116  and into the second liquid storage tank  112 , and begins filling the second liquid storage tank  112  (step  300 ). 
     After a number of engine reservoirs are emptied in the aforementioned manner, the second liquid storage tank  112  fills to the point that the scale-type sensor/transducer  112   a  is actuated, indicative of a predetermined volume/weight of liquid in the second tank  112 . The controller  138  actuates the first, second, and third control valves  116 ,  118 ,  119  to move from their first positions to their second positions. Moving the first control valve  116  to it&#39;s second position blocks fluid communication between the first and second liquid storage tanks  110 ,  112 . Placing the second control valve  118  in its second position disconnects the vacuum source  122  from the second liquid storage tank. Moving the third control valve  119  to the second position places the pressure source  120  in communication with the second liquid storage tank  112 , and thereby establishes an over-atmospheric pressure in the second liquid storage tank.  112 . The pressure thus established above the liquid in the second storage tank  112  forces the liquid in the second storage tank  112  to flow through outlet conduit  136  and into the return tank  114 , emptying the second storage tank  112  (step  302 ). 
     While the second storage tank  112  is being emptied, under-atmospheric pressure is still communicated to the first liquid storage tank  110 , and the system continues to be used for evacuating engine reservoirs. Since the first control valve  116  is closed, the liquid evacuated from the engine reservoirs is retained in the first liquid storage tank  110 . After a number of engine reservoirs are emptied, the first scale-type sensor/transducer  110   b  is actuated, indicative of a predetermined volume/weight of liquid in the first tank, and thereby causes the controller  138  to move the first, second, and third control valves  116 ,  118 ,  119  from their second positions back to their first positions. Moving the third control valve  119  to the first position disconnects pressure from the second liquid storage tank  112 , while moving the second control valve  118  to the first position communicates under-atmospheric pressure or vacuum from the vacuum source  122  to the second liquid storage tank  112 . Moving the first control valve  116  to the first position re-establishes fluid communication between the first and second liquid storage tanks  110 ,  112 , and therefore permits liquid to again flow through the second conduit  126  and first control valve  116  (from the first liquid storage tank  110  to the second liquid storage tank  112 ; return to step  300 ). 
     As with the first embodiment, it is contemplated that a vent may be provided such that the second liquid storage tank  112  will be briefly vented to atmosphere when switched from the pressure source  120  to the vacuum source  122 . Moreover, it is contemplated that a brief time delay may be provided by the controller  138  wherein the second control valve  118  may return to it&#39;s first position shortly before the first control valve  116  returns to it&#39;s first position. 
     Following return of the control valves  116 ,  118  to their first positions, the second liquid storage tank  112  fills with liquid previously contained in the first liquid storage tank  110 , as well as liquid added to the system from subsequently evacuated engine reservoirs. The system thus continues filling the second liquid storage tank  112  and then, while draining the second liquid storage tank  112  into the return tank  114 , filling the first liquid storage tank  110 . As will be apparent to those skilled in the art, the available volumes of the first and second liquid storage tanks  110 ,  112  (i.e., the volumes available before the associated float-type limit switches  110   b,    112   a  are actuated) may be selected within wide limits and, for example, can be selected or tuned to the expected throughput of the system based upon the available space for the first and second liquid storage tanks  110 ,  112  in the manufacturing environment. Preferably, the tank sizes are selected such that, considering normal operating cycles, the second liquid storage tank  112  is completely emptied before the first liquid storage tank  110  is filled, and such that the available volume of the first liquid storage tank  110  may be completely received within the available volume of the second liquid storage tank  112 . 
     Moreover, although actuation of the control valves  116 ,  118 ,  119  by the controller  138  has been described hereinbefore as being in response to both the first and second scale-type sensors/transducers  110   b,    112   a,  it is contemplated that it could instead be in response to only the second sensor  112   a,  and the first sensor  110   b  could be provided as a fail-safe to prevent overflow of the first liquid storage vessel  110 . 
     The present invention has been described herein with particularity, but it is noted that the scope of the invention is not limited thereto. Rather, the present invention is considered to be possible of numerous modifications, alterations, and combinations of parts and, therefore, is only defined by the claims appended hereto. For example, it is contemplated that, with reference to the first embodiment, instead of using the first float-type switch to control the valves, a third float-type switch may be provided in the second liquid storage tank to sense absence of liquid in the second tank, which is indicative of the second tank&#39;s availability to receive liquid from the first liquid storage tank. In this case, the first float-type switch would be used as a system shut-down upon threatened overflow of the first liquid storage tank, as may occur during a problem in draining of the second tank or malfunction of the third float-type switch.