Abstract:
The present invention provides a system for controlling speed of the fuel pump. The system includes a fuel pump, a controller, and a field modification module. The fuel pump is configured to receive a driving signal causing the fuel pump to pump fuel. The controller is configured to determine a desired fuel pump speed and generate a control signal based on the desired fuel pump speed. The field modification module is located proximate the fuel pump and is in communication with the controller to receive the control signal. The field modification module generates a flux in response the control signal thereby controlling speed and torque of the fuel pump.

Description:
BACKGROUND  
       [0001]     1. Field of the Invention  
         [0002]     The present invention generally relates to a system for controlling the speed of the fuel pump.  
         [0003]     2. Description of Related Art  
         [0004]     Automotive fuel pump systems have been widely used though out the automotive industry. Typically most fuel pumps run at the highest pressure and maximum flow rate at all times to reduce the amount of fuel vapor for vehicle hot restart and provide sufficient fuel in a wide open throttle condition. However, running at the highest fuel pressure and flow is not efficient and negatively affects the life of the fuel pump.  
         [0005]     In fuel pump applications, it is desirable to vary the amount of fuel provided from the fuel pump depending on the engine performance requirements. For instance, a vehicle at full throttle may require 90 liters of fuel per hour, while at idle the vehicle may consume only 3 liters of fuel per hour. There are a number of problems associated with the return of fuel from the high pressure, high temperature engine area to the relatively low pressure and low temperature fuel tank area. In an idle condition, the high pressure and temperature of the fuel being returned to the fuel tank causes substantial amounts of fuel vapor to be generated. The vapor must be vented from the fuel tank area which may, additionally, raise environmental issues.  
         [0006]     One solution is controlling the amount of fuel delivered to supply only the amount of fuel used. The amount of fuel delivered is dependent on the fuel pressure generated by the fuel pump. Generally, the fuel pressure is related to the speed of the pump.  
         [0007]     One method used to vary pump speed to control fuel pressure uses a voltage drop resistor. The resistor is selectively connected to the fuel pump voltage supply to control the voltage provided to the pump motor thereby changing the pump speed. Although this method reduces fuel pump wear, little energy is saved as the additional voltage is dissipated across the voltage drop resistor. Further, the additional heat energy created by the voltage drop resistor must be dissipated.  
         [0008]     Another method used to vary pump speed thereby affecting fuel pressure includes modulating the driving signal. A pulse width modulator can be used to vary the duty cycle of the pump driving voltage thereby changing the pump speed. Although this method also reduces fuel pump wear and some energy is saved, the power and frequency of pulses required to drive the pump cause radio frequency interference problems for other vehicle components. Further, the use of a pulse width modulator in the control circuit increases system complexity and cost.  
         [0009]     In view of the above, it is apparent that there exists a need for an improved system for controlling the speed of the fuel pump.  
       SUMMARY  
       [0010]     In satisfying the above need, as well as overcoming the enumerated drawbacks and other limitations of the related art, the present invention provides a system for controlling speed of the fuel pump. The system includes a fuel pump, a controller, and a field modification module. The fuel pump has a motor configured to receive a driving signal causing the fuel pump to pump fuel. The controller is configured to determine a desired fuel pump speed and generate a control signal based on the desired fuel pump speed. The field modification module is located proximate the fuel pump and is in communication with the controller to receive the control signal. The field modification module alters a magnetic field of the motor in response the control signal thereby controlling speed and torque of the fuel pump.  
         [0011]     In another aspect of the present invention, the system includes a sensor in communication with the controller. The sensor is configured to sense fuel system characteristics, such as, fuel pressure and temperature. Further, the controller is configured to receive a signal from the sensor corresponding to the fuel system characteristics and determine the desired fuel pump speed based on the signal.  
         [0012]     In another aspect of the present invention, the field modification module includes a coil. The coil receives a control signal to generate a magnetic flux that modifies a magnetic field generated by the fuel pump thereby controlling speed and torque of the fuel pump. Further, the fuel pump includes a flux carrier and the field modification module includes a return guide. The coil may be wrapped around the return guide where the return guide is connected to two sides of the flux carrier. Alternatively, the return guide and a flux carrier may cooperate to form a cavity and the coils may be located in the cavity between the flux carrier and the return guide.  
         [0013]     In another aspect of the present invention, the field modification module includes a coil this located inside the flux carrier. As previously discussed, the coil generates a flux to alter the magnetic field of the fuel pump. The fuel pump further includes magnets and the coil may be wrapped around the magnets, located adjacent to the magnets, located between the magnets, or embedded inside the magnets.  
         [0014]     In another aspect of the present invention, the coil may be configured to generate a flux having a polarity matching the magnetic field thereby decreasing the speed the fuel pump. Alternatively, the coil may be configured to generate a flux having a polarity opposite the magnetic field thereby increasing the speed of the fuel pump.  
         [0015]     Further objects, features and advantages of this invention will become readily apparent to persons skilled in the art after a review of the following description, with reference to the drawings and claims that are appended to and form a part of this specification. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0016]      FIG. 1  is a block diagram of a system for controlling the speed of a fuel pump in accordance with the present invention;  
         [0017]      FIG. 2  is cross-sectional view of an embodiment of the system having external coil in accordance with present invention;  
         [0018]      FIG. 3  is a cross-sectional view of an embodiment of the system having a coil between the flux carrier and return guide in accordance with present invention;  
         [0019]      FIG. 4  is a cross-sectional view of an embodiment having a coil wrapped around the magnets of the fuel pump in accordance with present invention;  
         [0020]      FIG. 5  is a cross-sectional view of an embodiment having a coil adjacent to the magnets of the fuel pump in accordance with present invention; and  
         [0021]      FIG. 6  is a cross-sectional view of an embodiment of having the coil embedded in the magnets of the fuel pump in accordance with present invention.  
         [0022]      FIG. 7  is a cross-sectional view of an embodiment of a motor with a supplemental flux carrier in accordance with present invention. 
     
    
     DETAILED DESCRIPTION  
       [0023]     Referring now to  FIG. 1 , a system embodying the principles of the present invention is illustrated therein and designated at  8 . The system  8  includes a field modification module (FMM)  11  coupled to a motor  12  of a fuel pump  10  where the FMM  11  is configured to alter a magnetic field to control the speed of the motor  12 . The FMM  11  can be powered in parallel or series with the motor  12 .  
         [0024]     As a vehicle enters a run state an ignition signal  16  is activated. A fuse  22  is provided to protect vehicle components in the event the ignition signal  16  is shorted. The ignition signal  16  is provided to the fuel relay  24 , pump control relay  26  is indicated by a line  28 .  
         [0025]     The fuel relay  24  is connected to the battery  20  and inertia switch  32 . The fuel relay  24  provides a driving signal  34  to generate rotation of the motor  12 . The inertia switch  32  is provided to interrupt the driving signal  34  in the event of a vehicle collision thereby stopping fuel flow. The driving signal  34  flows through the field windings of the motor  12  to create an magnetic field. The magnetic field creates a rotation of the motor  12  which is used to pump fuel through the fuel lines  42 .  
         [0026]     The pump control relay  26  is connected to the battery  20  and the pump control module  36 . As the pump control relay  26  receives the ignition signal  16 , the pump control relay  26  activates the pump control module  36 . The fuel relay  24  is also connected to the battery  20  and the pump control module  36 . As the fuel relay  24  receives the ignition signal  16 , the active signal  30  is provided from the fuel relay  24  to the pump control module  36 . The pump control module  36  monitors the motor driving signal  34  as indicated by line  38 . The pump control module  36  provides a control signal  40  to the FMM  11  to control the speed of the motor  12   
         [0027]     In this embodiment, the FMM  11  is shown as two coils  14  located proximate motor  12 . Control signal  40  travels through the coils  14  and a magnetic flux is created altering the magnetic field driving the motor  12 . The magnetic flux may be generated in the same polarity as the magnetic field generated by the motor  12 , thereby increasing motor torque as the magnitude of the control signal  40  increases. Alternatively, the magnetic flux may be generated in the opposite polarity as the magnetic field generated by the motor  12 , thereby increasing motor speed as the magnitude of the control signal increases.  
         [0028]     Based on the pressure generated from the motor  12  the fuel travels through the fuel lines  42  to fuel filter  46 . The fuel filter  46  filters any contaminants from the fuel prior to fuel injection at the fuel rail  48 . The fuel rail  48  includes sensors  52  to measure various parameters  50 , such as fuel pressure and temperature that affect proper fuel injection.  
         [0029]     Now referring to  FIG. 2 , the system  60  is provided with the FMM  11  being external to the motor  12  in accordance with present invention. The motor  12  includes an armature  62 , field windings  66 , magnets  64  and a flux carrier  68 . The armature  62  is configured to rotate and is located inside the flux carrier  68 . The armature  62  has field windings  66  wrapped around portions of a rotor  63 . As the driving signal  34  is provided to the field windings  66  a first magnetic flux is generated. The magnets  64  are located proximate the field winding  66  and generate a second magnetic flux. The first and second magnetic flux cooperate to form a magnetic field that causes a rotation of the armature  62 . The flux carrier  68  encloses the magnets  64  and field windings  66  and directs the magnetic field around the motor  12  to complete the magnetic circuit. The strength of the magnetic field in the air gap  69  controls the speed and torque characteristics of the motor  12 . By changing the magnitude of the magnetic field, the speed and torque characteristics of the motor  12  are also changed. Increasing the strength of the magnetic field will increase the torque at a given current through the armature  62 . With all other variables held constant, the speed of the motor  12  will decrease. Alternatively, decreasing the strength of the magnetic field will increase the speed of the motor  12  and produce less torque with all other variables held constant.  
         [0030]     A guide return  70  is attached to the flux carrier  68  at two ends. The coil  74  is wound around an opening  72  formed in the guide return  70  and acts as an electromagnet creating a third magnetic flux that travels through the guide return  70  and across the flux carrier  68  altering the magnetic field generated by the motor  12  as the magnetic field is returned through the flux carrier  68 . Based on the winding direction coil  74  and the direction of current flow, the coil  74  can generate flux that has a polarity opposite the magnetic field thereby negating the magnetic field and causing the motor increase speed. Alternatively, the coil  74  can generate flux with a polarity matching the magnetic field thereby supplementing the magnetic field causing the motor to decrease speed and increase torque. Further, it is apparent from the discussion above that the FMM  11  can be applied to brushed or brushless motors.  
         [0031]     Now referring to  FIG. 3 , another embodiment of the system  80  is provided with the FMM  11  being external to the motor  12  in accordance with present invention. The motor  12  includes an armature  82 , field windings  86 , magnets  84  and  85 , and a flux carrier  88 . The armature  82  is configured to rotate and is located inside the flux carrier  88 . The armature  82  has field windings  86  wrapped around portions of a rotor  83 . As the control signal  40  is provided to the field windings  86 , a first magnetic flux is generated. The magnets  84 , 85  are located proximate the field windings  86  and generate a second magnetic flux. The first and second magnetic flux cooperate to form a magnetic field that causes a rotation of the armature  82 . The flux carrier  88  directs the magnetic field around the motor  12  to complete the magnetic circuit. The strength of the magnetic field in the air gap  89  controls the speed and torque characteristics of the motor  12 . By changing the magnitude of the magnetic field, the speed and torque characteristics of the motor  12  are also changed.  
         [0032]     The FMM  11  includes a first coil  94 , a second coil  96 , and guide returns  90 . The guide returns  90  are attached to the flux carrier  88  at opposite ends. The guide returns  90  cooperate with the flux carrier  88  to form passages  92 . A first and second coil  94 ,  96  are located in each of the passages  92 . The first coil  94  generates a third magnetic flux that alters the magnetic field by the field windings  86  and the first magnet  84 . Similarly, the second coil  96  generates a fourth magnetic flux that alters the magnetic field generated in cooperation with the second magnet  85 . Based on the direction of the winding of the first and second coil  94 ,  96  and the direction of current flow, the first and second coil  94 ,  96  can generate flux that has a polarity opposite the magnetic field thereby negating the magnetic field and causing the motor to increase speed. Alternatively, the first and second coil  94 ,  96  can generate flux with a polarity matching the magnetic field thereby supplementing the magnetic field causing the motor to decrease speed and increase torque.  
         [0033]     Now referring to  FIG. 4 , another embodiment of the system  100  is provided with the FMM  11  being internal to the motor  12  in accordance with present invention. The motor  12  includes an armature  102 , field windings  106 , magnets  104  and  105 , and a flux carrier  108 . The armature  102  is configured to rotate and is located inside the flux carrier  108 . The armature  102  has field windings  106  wrapped around portions of a rotor  103 . As the control signal  40  is provided to the field windings  106  a first magnetic flux is generated. The magnets  104 ,  105  are located proximate the field windings  106  and generate a second magnetic flux. The first and second magnetic flux cooperate to form a magnetic field that causes a rotation of the armature  102 . The flux carrier  88  directs the magnetic field around the motor  12  to complete the magnetic circuit. The strength of the magnetic field in the air gap  109  controls the speed and torque characteristics of the motor  12 . By changing the magnitude of the magnetic field, the speed and torque characteristics of the motor  12  are also changed.  
         [0034]     The FMM  11  includes a first coil  110 , and a second coil  112 . The first and second coil  110 ,  112  are located inside the flux carrier  108 . The first coil  110  is wound around the first magnet  104  and generates a third magnetic flux that alters the magnetic field generated by the field windings  106  and the first magnet  104 . Similarly, the second coil  112  is wound around the second magnet  105  and generates a fourth magnetic flux that alters the magnetic field generated in cooperation with the second magnet  105 . Based on the direction of the winding of the first and second coil  110 ,  112  and the direction of current flow, the coil can generate flux that has a polarity opposite the magnetic field thereby negating the magnetic field and causing the motor to increase speed. Alternatively, the first and second coil  110 ,  112  can generate flux with a polarity matching the magnetic field thereby supplementing the magnetic field causing the motor to decrease speed and increase torque.  
         [0035]     Now referring to  FIG. 5 , another embodiment of the system  120  is provided with the FMM  11  being internal to the motor  12  in accordance with present invention. The motor  12  includes an armature  122 , field windings  126 , magnets  124  and  125 , and a flux carrier  128 . The armature  122  is configured to rotate and is located inside the flux carrier  128 . The armature  122  has field windings  126  wrapped around portions of a rotor  123 . As the control signal  40  is provided to the field windings  126  a first magnetic flux is generated. The magnets  124 ,  125  are located proximate the field windings  126  and generate a second magnetic flux. The first and second magnetic flux cooperate to form a magnetic field that causes a rotation of the armature  122 . The flux carrier  128  directs the magnetic field around the motor  12  to complete the magnetic circuit. The strength of the magnetic field in the air gap  129  controls the speed and torque characteristics of the motor  12 . By changing the magnitude of the magnetic field, the speed and torque characteristics of the motor  12  are also changed.  
         [0036]     The FMM  11  includes a first coil  130 , a second coil  132 . Contained inside the flux carrier  128 , the first and second coil  130 ,  132  are located adjacent to and between the first and second magnets  124 ,  125 . The first and second coil  130 ,  132  generate a third magnetic flux that alters the magnetic field generated by the field windings  126  and the first and second magnet  124 ,  125 . Based on the direction of the winding of the first and second coil  130 ,  132  and the direction of current flow, the first and second coil  130 ,  132  can generate flux that has a polarity opposite the magnetic field thereby negating the magnetic field and causing the motor to increase speed. Alternatively, the first and second coil  130 ,  132  can generate flux with a polarity matching the magnetic field thereby supplementing the magnetic field causing the motor to decrease speed and increase torque.  
         [0037]     Now referring to  FIG. 6 , another embodiment of the system  140  is provided with the FMM  11  being internal to the motor  12  in accordance with present invention. The motor  12  includes an armature  142 , field windings  146 , magnets  144  and  145 , and a flux carrier  148 . The armature  142  is configured to rotate and is located inside the flux carrier  148 . The armature  142  has field windings  146  wrapped around a rotor  143 . As the control signal  40  is provided to the field windings  146  a first magnetic flux is generated. The magnets  144 ,  145  are located proximate the field windings  146  and generate a second magnetic flux. The first and second magnetic flux cooperate to form a magnetic field that causes a rotation of the armature  142 . The flux carrier  148  directs the magnetic field around the motor  12  to complete the magnetic circuit. The strength of the magnetic field in the air gap  149  controls the speed and torque characteristics of the motor  12 . By changing the magnitude of the magnetic field, the speed and torque characteristics of the motor  12  are also changed.  
         [0038]     The FMM  11  includes a first coil  150 , a second coil  152 . The first and second coil  150 ,  152  are located inside of the flux carrier  148 . The first coil  150  is embedded in the first magnet  144  and generates a third magnetic flux that alters the magnetic field generated by the field windings  146  and the first magnet  144 . Similarly, the second coil  152  is embedded in the second magnet  145  and generates a fourth magnetic flux that alters the magnetic field generated in cooperation with the second magnet  145 . Based on the direction of the winding of the first and second coil  150 ,  152  and the direction of current flow, the coil can generate flux that has a polarity opposite the magnetic field thereby negating the magnetic field and causing the motor to increase speed. Alternatively, the first and second coil  150 ,  152  can generate flux with a polarity matching the magnetic field thereby supplementing the magnetic field causing the motor to decrease speed and increase torque.  
         [0039]     Now referring to  FIG. 7 , another embodiment of the system  160  is provided with the FMM  11  being external to the motor  12  in accordance with present invention. The motor  12  includes an armature  162 , field windings  166 , magnets  164 , and a flux carrier  168 . The armature  162  is configured to rotate and is located inside the flux carrier  168 . The armature  162  has field windings  166  wrapped around a rotor  163 . As the control signal  40  is provided to the field windings  166  a first magnetic flux is generated. The magnets  164  are located proximate the field windings  166  and generate a second magnetic flux. The first and second magnetic flux cooperate to form a magnetic field that causes a rotation of the armature  162 . The flux carrier  168  directs the magnetic field around the motor  12  to complete the magnetic circuit. The strength of the magnetic field in the air gap  169  controls the speed and torque characteristics of the motor  12 . By changing the magnitude of the magnetic field, the speed and torque characteristics of the motor  12  are also changed.  
         [0040]     The FMM  11  includes a supplementary flux carrier  170  and an actuator  172 . The supplementary flux carrier  170  is located proximate to the flux carrier  168 . The flux carrier  168  has a portion with a reduced thickness such that the magnetic field escapes through the thin portion  171  of the flux carrier  168 . The actuator  172  is attached to the supplementary flux carrier  170  and is configured to move the supplementary flux carrier  170  relative to the thin portion  171  of the flux carrier  168 . As the supplementary flux carrier  170  moves closer to the thin portion  171  of the flux carrier  168 , the supplementary flux carrier  170  acts to contain the magnetic field thereby increasing the strength of the magnetic field inside the motor  12 . Alternatively, as the supplementary flux carrier  170  moves away from the thin portion  171  of the flux carrier  168 , more of the magnetic field escapes thereby decreasing the strength of the magnetic field inside the motor  12 .  
         [0041]     As a person skilled in the art will readily appreciate, the above description is meant as an illustration of implementation of the principles this invention. This description is not intended to limit the scope or application of this invention in that the invention is susceptible to modification, variation and change, without departing from spirit of this invention, as defined in the following claims.