Patent Publication Number: US-2013233283-A1

Title: Bimetallic thermostatic flow valve for diesel fuel systems

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Patent Application No. 61/608,868 filed on Mar. 9, 2012, the disclosure of which is hereby incorporated by reference. 
    
    
     TECHNICAL FIELD 
     This invention relates to a fuel system for a diesel engine and, more particularly, to a bimetallic thermostatic flow valve for such systems. 
     BACKGROUND 
     In a conventional diesel engine, the fuel system provides excess or surplus fuel to the engine. This excess fuel is heated during the engine operation and then may be returned to the fuel tank. It is known that when diesel fuel is below certain low temperatures, paraffin wax crystals will solidify in the fuel. When the crystals begin to appear, they can accumulate on the fuel filter. Additionally, if too much heat builds up in the fuel flowing to the engine, the system may not perform at an optimum level. Current systems use a wax element in a flow valve to direct hot or cool return fuel as desired. 
     SUMMARY 
     A fuel system for a diesel engine is provided that includes a fuel supply tank module for storing fuel. The fuel supply tank module includes a fuel pump module reservoir which has an in-tank low pressure lift pump and a bimetallic thermostatic flow valve inside the fuel pump module reservoir. The fuel system also includes a fuel filter module connected to the in-tank low pressure lift pump for filtering fuel pumped from the fuel supply tank module, a high pressure pump connected to the fuel filter module for pumping fuel from the fuel filter module, a diesel engine connected to the high pressure pump for receiving fuel from the high pressure pump, and a fuel return line connected from the diesel engine to the bimetallic thermostatic flow valve for returning fuel to the bimetallic thermostatic flow valve. The bimetallic thermostatic flow valve includes a bimetallic element, which is in thermal communication with the returning fuel. The returning fuel flows through the bimetallic thermostatic flow valve causing the bimetallic element to deflect in response to the thermal communication so that fuel flows to at least one of the fuel pump module reservoir and the in-tank low pressure lift pump. Thus, when the temperature of the returning fuel is below a predetermined temperature range, the bimetallic element deflects so that fuel flows to the in-tank low pressure lift pump, and undesirable effects of cold fuel can be reduced. Additionally, when the temperature of the returning fuel is above the predetermined temperature range, the bimetallic element deflects so that fuel flows to the fuel pump module reservoir, and excessive heat can be dissipated. 
     In a first and a second embodiment, the bimetallic thermostatic flow valve has a valve body including a fuel return port, a fuel pump module reservoir port, a fuel supply port, and a fuel chamber connected to the fuel return port and through which returning fuel flows. The bimetallic element extends into the fuel chamber and is in thermal communication with the returning fuel. The returning fuel causes the bimetallic element to deflect in response to the thermal communication so that fuel flows to at least one of the fuel pump module reservoir port and the fuel supply port. The bimetallic element directs fuel by deflecting or lengthening in response to a temperature of fuel flowing through the fuel return port. When the temperature of the returning fuel is within a predetermined temperature range, the bimetallic element does not deflect fully so the return fuel is directed to be split between both the fuel supply port and the fuel pump module reservoir port depending on the amount of the deflection. When the temperature of the returning fuel is below the predetermined temperature range, then the bimetallic element deflects sufficiently to direct the returning fuel to the fuel supply port. When the temperature of the returning fuel is above the predetermined temperature range, then the bimetallic element deflects sufficiently to direct the returning fuel to the fuel pump module reservoir port. 
     In another embodiment, a bimetallic thermostatic flow valve includes a generally cylindrical valve body having a bend and having at least one aperture. The generally cylindrical valve body has a fuel return port and a fuel supply port for directing returning fuel flow. The aperture has a bimetallic element covering it. The bimetallic element deflects away from the at least one aperture in response to a predetermined temperature of returning fuel flowing through the generally cylindrical valve body. 
     The above features and advantages and other features and advantages of the present invention are readily apparent from the following detailed description of the best modes for carrying out the invention when taken in connection with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic illustration of a fuel system for a diesel engine including a bimetallic thermostatic flow valve constructed in accordance with the teachings of the present invention. 
         FIG. 2  is a cross-sectional illustration of a first embodiment of the bimetallic thermostatic flow valve of the present invention with a bimetallic element in a deflectable plate form in a neutral design position. 
         FIG. 3  is a cross-sectional illustration showing the fuel flow through the bimetallic thermostatic flow valve with the bimetallic element in a deflectable spring form in the neutral design position of  FIG. 2 . 
         FIG. 4  is a cross-sectional illustration of the first embodiment of the bimetallic thermostatic flow valve of the present invention with the bimetallic element in the deflectable plate form in a hot start design position. 
         FIG. 5  is a cross-sectional illustration showing the fuel flow through the bimetallic thermostatic flow valve with the bimetallic element in the deflectable spring form in the hot start design position of  FIG. 4 . 
         FIG. 6  is a cross-sectional illustration of the first embodiment of the bimetallic thermostatic flow valve of the present invention with the bimetallic element in the deflectable plate form in a cold start design position. 
         FIG. 7  is a cross-sectional illustration showing the fuel flow through the bimetallic thermostatic flow valve with the bimetallic element in the deflectable spring form in the cold start design position of  FIG. 6 . 
         FIG. 8  is a cross-sectional illustration of a second embodiment of the bimetallic thermostatic flow valve of the present invention with the bimetallic element in a deflectable plate form in a neutral design position. 
         FIG. 9A  is a cross-sectional illustration of the second embodiment of the bimetallic thermostatic flow valve of the present invention with the bimetallic element in the deflectable plate form in a hot start design position. 
         FIG. 9B  is a cross-sectional view of the second embodiment taken along lines  9 B- 9 B of  FIG. 9A  to show the shaped deflected bimetallic element. 
         FIG. 10  is a cross-sectional illustration of the second embodiment of the bimetallic thermostatic flow valve of the present invention with the bimetallic element in the deflectable plate form in a cold start design position. 
         FIG. 11  is cross-sectional illustration of a third embodiment of the bimetallic thermostatic flow valve having a bimetallic element in the deflectable plate form of the present invention. 
         FIG. 12  is a schematic illustration of a bimetallic element in the deflectable plate form mounted on a support material suitable for use in the third embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     Referring to the drawings, wherein like numbers refer to like components throughout the several views,  FIG. 1  shows a fuel system  50  for a diesel engine  30 . Diesel fuel is supplied into a fuel supply tank module  10  through a fuel supply tank fill tube  12 . Fuel is pumped from the fuel supply tank module  10  by an in-tank low pressure lift pump  20  located inside a fuel pump module reservoir  38  inside the fuel supply tank module  10 . Fuel enters the in-tank low pressure lift pump  20  through a fuel pump module inlet strainer  34 , which generally is a screen mesh material, and in-tank low pressure lift pump inlet port  36 . Fuel moves through the in-tank low pressure lift pump outlet port  22  into a fuel feed supply line  24 . The fuel feed supply line  24  connects to a fuel filter module  26  which may include a fuel filter, water separator, and/or heater. The heater in fuel filter module  26  may heat the fuel when it is below a predetermined temperature. A low pressure supply line connects the fuel filter module  26  with a high pressure pump  28  which is mounted on the diesel engine  30 . A high pressure supply line connects the high pressure pump  28  with the diesel engine  30 . The diesel engine  30  includes a rail with injectors and several other components which are not shown but are well known. Excess fuel not used in the operation of the diesel engine  30  returns to the fuel supply tank module  10  through fuel return line  32 . This excess fuel has been heated by the diesel engine  30 . 
     In accordance with the present invention, excess fuel returns through the fuel return line  32  to a fuel return port  120  of a bimetallic thermostatic flow valve  100  located in the fuel pump module reservoir  38  inside the fuel supply tank module  10 . As described in more detail in the following description and shown in  FIGS. 2 ,  3 ,  4 ,  5 ,  6  and  7 ; this excess fuel (called returning fuel throughout this description) flows through the bimetallic thermostatic flow valve  100  causing a bimetallic element  130  or  131  to deflect in response to a temperature of the returning fuel from the fuel return line  32 . This bimetallic thermostatic flow valve  100  directs the returning fuel to either one or both of a fuel pump module reservoir port  140  (leading to the fuel pump module reservoir  38 ) and a fuel supply port  150  (leading to the in-tank low pressure lift pump  20 ). As shown in  FIGS. 2 ,  4 ,  6 ,  8 ,  9 A,  9 B,  10 ,  11  and  12 , the bimetallic element may be in the form of a deflectable plate. As shown in  FIGS. 3 ,  5  and  7 , the bimetallic element may be in the form of a deflectable spring. 
     Referring to  FIGS. 2 and 3 , a first embodiment of the bimetallic thermostatic flow valve  100  includes a valve body  102  having a fuel return port  120  which connects to fuel return line  32  of  FIG. 1 . The valve body  102  of the bimetallic thermostatic flow valve  100  has a valve body inner wall  112  and an insert member  104  has an insert member inner wall  106 . The valve body inner wall  112  and the insert member inner wall  106  form a fuel chamber  110 . The bimetallic element  130 ,  131  is attached to the insert member inner wall  106  at a respective first end  132 ,  133 . Each bimetallic element  130 ,  131  is composed of temperature responsive material which in effect senses the temperature of the returning fuel. 
     Referring again to  FIGS. 2 and 3 , a second end  134 ,  135  of the respective bimetallic element  130 ,  131  extends into the fuel chamber  110  of the bimetallic thermostatic flow valve  100  and is in thermal communication with or is free to respond as the temperature of fuel flowing through the fuel return port  120  and into the fuel chamber  110  causes the metals composing the bimetallic element  130 ,  131  to lengthen or deflect. The bimetallic element  130  in deflectable plate form is shaped to direct or stop the return fuel flow as desired. The bimetallic element  131  in deflectable spring form includes a first spring head  137  and a second spring head  139  shaped to direct or stop the return fuel flow as desired. A stop  136  may be attached to the valve body inner wall  112  of the bimetallic thermostatic flow valve  100  if needed for the bimetallic element  130  to deflect against. The temperature of fuel in (Fin) into the fuel return port  120  is such that the bimetallic element  130 ,  131  does not deflect fully and thus allows fuel out (Fout) to flow out through both the fuel pump module reservoir port  140  (leading to fuel pump module reservoir  38  shown in  FIG. 1 ) and through the fuel supply port  150  (leading to in-tank low pressure lift pump  20  shown in  FIG. 1 ) depending on the amount of the deflection. This is called a neutral design position for the bimetallic element  130 ,  131  and could occur when the temperature range of returning fuel is a predetermined temperature range, between 25 and 40 degrees Celsius, for example. 
     Referring to  FIGS. 4 and 5 , the first embodiment of the bimetallic thermostatic flow valve  100  having the valve body  102  is shown in which a temperature of fuel is above the predetermined temperature range. The valve body  102  of the bimetallic thermostatic flow valve  100  has the valve body inner wall  112  and the insert member  104  has the insert member inner wall  106 . The valve body inner wall  112  and the insert member inner wall  106  form the fuel chamber  110 . The bimetallic element  130 ,  131  is attached to the insert member inner wall  106  at the respective first end  132 ,  133 . Each bimetallic element  130 ,  131  is composed of temperature responsive material which in effect senses the temperature of the returning fuel. 
     Referring again to  FIGS. 4 and 5 , the second end  134 ,  135  of the respective bimetallic element  130 ,  131  extends into the fuel chamber  110  of the bimetallic thermostatic flow valve  100  and is in thermal communication with or is free to respond as the temperature of fuel flowing through the fuel return port  120  and into the fuel chamber  110  causes the metals composing the bimetallic element  130 ,  131  to lengthen or deflect. The stop  136  may be attached to the valve body inner wall  112  of the bimetallic thermostatic flow valve  100  if needed for the bimetallic element  130  to deflect against. The temperature of fuel in (Fin) into the fuel return port  120  is such that the bimetallic element  130 ,  131  deflects to block the passage or causes the second spring head  139  to block the passage through the fuel supply port  150  respectively, so most of the fuel in (Fin) entering into the bimetallic thermostatic flow valve  100  leaves through the fuel pump module reservoir port  140 . This situation occurs when the temperature of fuel in (Fin) is above the predetermined temperature range. By directing most of the fuel out (Fout) to the fuel pump module reservoir port  140 , the heated fuel is returned to the fuel pump module reservoir  38  (shown in  FIG. 1 ) and directed away from the diesel engine  30  (shown in  FIG. 1 ), to dissipate excess heat into the bulk fuel in normal vehicle operation. (The temperature above the predetermined temperature range may be above the 25 to 40 degrees Celsius temperature range for example.) 
     Referring to  FIGS. 6 and 7 , the first embodiment of the bimetallic thermostatic flow valve  100  having the valve body  102  is shown in which the temperature of fuel is below the predetermined temperature range. The valve body  102  of the bimetallic thermostatic flow valve  100  has a valve body inner wall  112  and an insert member  104  has an insert member inner wall  106 . The valve body inner wall  112  and the insert member inner wall  106  form a fuel chamber  110 . The bimetallic element  130 ,  131  is attached to the insert member inner wall  106  at the respective first end  132 ,  133 . Each bimetallic element  130 ,  131  is composed of temperature responsive material which in effect senses the temperature of the return fuel. 
     Referring again to  FIGS. 6 and 7 , the second end  134 ,  135  of the respective bimetallic element  130 ,  131  extends into the fuel chamber  110  of the bimetallic thermostatic flow valve  100  and is in thermal communication with or is free to respond as the temperature of fuel flowing through the fuel return port  120  and into the fuel chamber  110  causes the metals composing the bimetallic element  130 ,  131  to lengthen or deflect. The stop  136  may be attached to the valve body inner wall  112  of the bimetallic thermostatic flow valve  100  if needed for the bimetallic element  130  to deflect against. The temperature of fuel in (Fin) into the fuel return port  120  is such that the bimetallic element  130 ,  131  deflects to block the passage or causes the first spring head  137  to block the passage through the fuel pump module reservoir port  140 , so most of the fuel in (Fin) entering into the bimetallic thermostatic flow valve  100  leaves through the fuel supply port  150 . This situation occurs when the temperature of fuel in (Fin) is below the predetermined temperature range. By directing most of the fuel out (Fout) to the fuel supply port  150 , the heated fuel is returned to the in-tank low pressure lift pump  20  (shown in  FIG. 1 ) and ultimately the diesel engine  30  (shown in  FIG. 1 ) so that the undesirable effects of cooler fuel may be mitigated. (The temperature below the predetermined temperature range may be below the 25 to 40 degrees Celsius temperature range for example.) 
     Referring to  FIG. 8 , a second embodiment of the bimetallic thermostatic flow valve  200  includes a valve body  202  having a fuel return port  220  which connects to a fuel return line (such as shown as the fuel return line  32  in  FIG. 1 ). The valve body  202  of the bimetallic thermostatic flow valve  200  has a valve body inner wall  212  and an insert member  204  has an insert member inner wall  206 . The valve body inner wall  212  and the insert member inner wall  206  form a fuel chamber  210 . The bimetallic element  230  is attached to the insert member inner wall  206  at a first end  232 . The bimetallic element  230  is composed of temperature responsive material which in effect senses the temperature of the returning fuel. A second end  234  of the bimetallic element  230  extends into the fuel chamber  210  of the bimetallic thermostatic flow valve  200  and is in thermal communication with or is free to respond as the temperature of returning fuel flowing through the fuel return port  220  and into the fuel chamber  210  causes the metals composing the bimetallic element  230  to lengthen or deflect. The temperature of the returning fuel into the fuel return port  220  is such that the bimetallic element  230  does not fully deflect and thus, allows fuel to flow out through a fuel pump module reservoir port  240  and through a fuel supply port  250  depending on the amount of the deflection. This is called a neutral design position for the bimetallic element  230  and could occur when the temperature of returning fuel is a predetermined temperature range, between 25 and 40 degrees Celsius, for example. 
     Referring to  FIGS. 9A and 9B , the second embodiment of the bimetallic thermostatic flow valve  200  having the valve body  202  is shown in which the temperature of fuel into the fuel return port  220  is above the predetermined temperature range. The valve body  202  of the bimetallic thermostatic flow valve  200  has the valve body inner wall  212  and the insert member  204  has the insert member inner wall  206 . The valve body inner wall  212  and the insert member inner wall  206  form the fuel chamber  210 . The bimetallic element  230  is attached to the insert member inner wall  206  at the first end  232 . The second end  234  of the bimetallic element  230  extends into the fuel chamber  210  of the valve body  202  of the bimetallic thermostatic flow valve  200  and is free to move as the temperature of returning fuel flowing through the fuel return port  220  causes the metals composing the bimetallic element  230  to lengthen or deflect. Since the returning fuel is above the predetermined temperature range, the bimetallic element  230  deflects to at least partially block the passage through the fuel supply port  250 . Most of the fuel entering into the valve body  202  of the bimetallic thermostatic flow valve  200  flows out through the fuel pump module reservoir port  240 . Due to the location of the mounting of the bimetallic element  230  in relation to the fuel pump module reservoir port  240 , the bimetallic element  230  should be shaped to allow return fuel to travel between the bimetallic element  230  and the inner wall  212  of the valve body  202  of the bimetallic thermostatic flow valve  200  so that more returning fuel goes through the fuel pump module reservoir port  240  than through the fuel supply port  250 . This shape as shown in  FIG. 9B  and described below allows the return fuel to flow around the bimetallic element near the first end  232  and out the fuel pump reservoir port  240 . This situation occurs when the temperature of fuel in is above a predetermined temperature. By directing most of the fuel out to the fuel pump module reservoir port  240 , the heated fuel is returned to fuel pump module reservoir  38  (shown in  FIG. 1 ) and directed away from fuel system components and the diesel engine  30  (shown in  FIG. 1 ), to dissipate excess heat into the bulk fuel in normal vehicle operation. Referring to  FIG. 9B , a cross-sectional view of the shaped deflected bimetallic element of  FIG. 9A  taken along lines  9 B- 9 B shows that returning fuel may flow between the bimetallic element  230  and the valve body inner wall  212  of valve body  202  so that more of the returning fuel goes through the fuel pump module reservoir port  240 . 
     Referring to  FIG. 10 , the second embodiment of the bimetallic thermostatic flow valve  200  having the valve body  202  is shown in which the temperature of fuel into the fuel return port  220  is below the predetermined temperature range. The valve body  202  of the bimetallic thermostatic flow valve  200  has the valve body inner wall  212  and the insert member  204  has the insert member inner wall  206 . The valve body inner wall  212  and the insert member inner wall  206  form the fuel chamber  210 . The bimetallic element  230  is attached to the insert member inner wall  206  at the first end  232 . The second end  234  of the bimetallic element  230  extends into the fuel chamber  210  of the body  202  of the bimetallic thermostatic flow valve  200  and is free to move as the temperature of returning fuel flowing through the fuel return port  220  causes the metals composing the bimetallic element  230  to lengthen or deflect. As shown in  FIG. 10 , the temperature of returning fuel into the fuel return port  220  is such that the bimetallic element  230  deflects to at least partially block passage through the fuel pump module reservoir port  240 . This situation occurs when the temperature of returning fuel in is below the predetermined temperature range. By directing the returning fuel out to the fuel supply port  250 , the heated fuel is returned to in-tank low pressure lift pump  20  (shown in  FIG. 1 ) and ultimately the diesel engine  30  (shown in  FIG. 1 ) so that the undesirable effects of cooler fuel may be mitigated. 
     Referring to  FIG. 11 , a third embodiment of the bimetallic thermostatic flow valve  300  is shown in which a standard pipe or generally cylindrical member comprises a valve housing or generally cylindrical valve body  318 . The generally cylindrical valve body  318  has a bend  314  and at least one bimetallic element  330  covering at least one aperature  340 . If applicable or desired, another bimetallic element  360  covers another aperature  340  and first ends  332  and  362  of the two bimetallic elements  330  and  360  respectively are attached to an exterior wall  316  of the generally cylindrical valve body  318  to cover apertures  340  in the generally cylindrical valve body  318  at cooler returning fuel temperatures. In this third embodiment, the apertures  340  function corresponding to the fuel pump module reservoir ports  140  and  240  in the first and second embodiments of the present invention. When the temperature of the fuel into a fuel return port  320  is below a predefined temperature, fuel flows out of a fuel supply port  350 . When the temperature of the returning fuel into the fuel return port  320  becomes great enough (for example over 40 degrees Celsius), second ends  334  and  364  of the bimetallic elements  330  and  360  respectively deflect away from the exterior wall  316  of the generally cylindrical valve body  318  or a stop  336  attached to the exterior wall  316 . Thus heated returning fuel is able to flow directly into fuel pump module reservoir  38  (shown in  FIG. 1 ) as the heated returning fuel does not tend to flow through the bend  314  of the generally cylindrical valve body  318  since a straighter flow path has been opened due to the deflection of the bimetallic elements  330  and  360 . This deflection allows returning fuel to flow through the apertures  340  which are functioning as fuel pump module reservoir ports in this embodiment. As shown in  FIG. 12 , to provide more structure to the bimetallic element  360 , the bimetallic element may be mounted on a support material  338  such as a piece of plastic, metal or the like as long as the support material deflects with the bimetallic element in response to the temperature of the returning fuel. 
     The bimetallic portions of the bimetallic elements used in the present invention may include metals which in combination will deflect at a temperature between 15 degrees Celsius and 80 degrees Celsius or other temperatures as system requirements dictate. It is noted that the bimetallic portions of the bimetallic elements may be mounted on additional material which is deflected along with the bimetallic portions when in the presence of heated or cooled fuel. It is further noted that the bimetallic portions should not introduce material into the system which might lead to lower system performance. 
     While the best modes for carrying out the invention have been described in detail, those familiar with the art to which this invention relates will recognize various alternative designs and embodiments for practicing the invention within the scope of the appended claims.