Patent Application
20050178366
1. Field of the Invention
The present invention generally relates to a system for controlling the speed of the fuel pump.
2. Description of Related Art
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
Referring now to
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.
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.
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
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.
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.
Now referring to
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.
Now referring to
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.
Now referring to
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.
Now referring to
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.
Now referring to
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.
Now referring to
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.
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.
