JP2008115835A - Fuel supply system for engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To avoid waste of power consumption by maintaining the motor load of a fuel pump to a moderate condition while enabling the fuel pump to cope with the maximum fuel required rate of an engine, in a fuel supply system for the engine driving and controlling the fuel pump by a control means. <P>SOLUTION: In this fuel supply system for the engine ensuring a fuel injection amount according to a required fuel flow rate of the engine while feedback controlling the driving of the fuel pump 3A so that an electronic control unit 10 maintains a predetermined fuel injection pressure, a connection gear 30A for connecting the motor rotating shaft 31a of the fuel pump 3A to a pump shaft 34a thereof is configured to a multistage speed changeover system, and the electronic control unit 10 performs control to change over the connection gear according to the required flow rate of the engine. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an engine fuel supply device, and more particularly, to a fuel supply device that is disposed in an engine fuel injection system and that supplies fuel to an engine by pumping fuel with an electric fuel pump.

  2. Description of the Related Art Conventionally, fuel supply devices that pressurize liquid fuel stored in a fuel tank using a fuel pump driven by an electric motor, inject it from an injector disposed at the end of a fuel supply pipe, and supply the fuel to an engine have been widely used. Yes. The fuel discharge flow rate in such a fuel supply device is proportional to the rotational speed of the fuel pump.

  Therefore, for example, as in the fuel injection system shown in FIG. 3 presented in Japanese Patent Laid-Open No. 11-229924, the electronic control unit 10 detects the operating state of the engine, in addition to the temperature sensor 11 and the pressure sensor 12. The fuel temperature / pressure is detected by the above, and an instruction value corresponding to the required fuel flow rate of the engine is output to the motor driver of the fuel pump 3B, whereby the fuel is arranged at the end of the fuel supply pipe 2 while controlling the rotation of the motor. It is known that an optimal fuel flow rate (injection amount) is realized by injection from the fuel.

  In this case, as shown in the longitudinal sectional partial view of the fuel pump 3B in FIG. 4, the rotation of the rotating shaft 31a of the motor 31 is transmitted to the pump shaft 32a via the connecting gear 30B, and the gear by the connecting gear 30B. The ratio is set by considering the torque curve of the motor 31 in anticipation of the maximum flow rate of the engine, that is, the maximum flow rate discharge of the fuel pump 3B.

However, as can be seen in the graph showing the distribution of the required fuel flow rate of the engine in the general usage state of the automobile (ordinary passenger car) shown in FIG. 2, most of them are concentrated in the “relatively low flow rate” band. It can be seen that the ratio of the “maximum required flow rate” zone is extremely small. For this reason, the fuel pump 3B in which the gear ratio is set in anticipation of the maximum required fuel flow rate of the engine is used for the fuel supply of a small flow rate for the most part of the operation, and the motor load is large and the power consumption is wasted. In addition, the fuel efficiency of the vehicle was also deteriorated.
Japanese Patent Laid-Open No. 11-229924

  The present invention is intended to solve the above-described problems, and in an engine fuel supply device that controls the drive of a fuel pump by a control means, the engine load of the engine is maintained while maintaining the motor load of the fuel pump in an appropriate state. The problem is to be able to cope with the maximum required flow rate.

  Accordingly, the present invention provides an electronic control unit that controls the rotational speed of the fuel pump and the opening and closing of the injector to maintain the predetermined fuel injection pressure, while controlling the fuel pump drive in response to the engine required fuel flow rate. In the fuel supply system for an engine that secures the fuel injection amount, a connecting gear for connecting the motor rotation shaft and the pump shaft of the fuel pump is a multi-stage speed switching system, and the electronic control unit responds to the engine required flow rate. The control for switching the connecting gear is executed.

  In this way, the multi-stage speed switching system that switches the connecting gear according to the engine required flow rate by the electronic control unit makes it a low rotation gear suitable for relatively small flow rates that normally occupies most of the engine operation. However, during high-power operation, the gear can be switched to a high-speed gear, and the motor load can be greatly reduced.

  Further, if the speed change of the connecting gear by the electronic control unit is performed based on a predetermined threshold value set in advance in the electronic control unit, an increase in processing load in the electronic control unit is minimized, A reliable gear change can be performed.

  Furthermore, in the engine fuel supply apparatus described above, if the switching of the connecting gear is performed in two stages, a low speed gear and a high speed gear, it is sufficient to meet the required engine flow rate while minimizing the complexity of the apparatus. Smooth speed switching can be easily achieved if the connection gear is switched via a clutch mechanism that is operated by a predetermined actuator that is driven and controlled by the electronic control unit. it can.

  According to the present invention in which the electronic control unit switches the connection gear according to the engine required flow rate, the motor load of the fuel pump can be maintained in an appropriate state while being able to cope with the maximum required flow rate of the engine. .

  The best mode for carrying out the present invention will be described below with reference to the drawings.

  FIG. 3 shows a layout diagram of a fuel injection system in which a fuel supply device for an engine according to the present embodiment having a configuration almost in common with the above-described conventional fuel supply system is arranged. The fuel tank 1 is filled with fuel, a fuel supply pipe 2 is extended from a fuel pump 3A attached to the fuel tank 1, and an injector 5 is provided at the tip thereof to supply fuel to an engine (not shown). To do.

  Further, a pressure sensor 11 for detecting the pressure of the fuel immediately before the injection and a temperature sensor 12 for detecting the fuel temperature are disposed in the vicinity of the injector 5 of the fuel supply pipe 2, and the electronic control unit 10 outputs an output signal from these sensors. It is designed to detect continuously. The injector 5 is controlled to open and close at a predetermined duty cycle by the electronic control unit 10 to realize a fuel injection amount corresponding to the engine required fuel flow rate.

  Referring to the longitudinal sectional view of the fuel pump 3A in FIG. 2 centering on the connecting gear 30A portion, the fuel pump 3A is driven by an electric motor 31, and the electronic control unit 10 sends a control signal to a motor driver (not shown). Is output to control its driving. The motor shaft 31a is connected to a clutch mechanism 32e, a low-speed pinion gear 32c, a low-speed driven gear 32d, and a pump shaft 34a extending from a pump unit (not shown) via a joint 32h, and transmits driving force to the pump unit. Is done.

  In addition to this, the motor shaft 31a is connected in the order of the high-speed pinion gear 32a, the high-speed driven gear 32b, and the pump shaft 34a. It is possible to switch between two stages: a gear for high speed and a gear for high speed.

  On the extension line of the motor shaft 31a, an electromagnetic solenoid 32g for operating the clutch mechanism 32e so that the drive unit comes into contact with the end surface of the motor shaft 31a is arranged so that the rod 32i can be pressed against the clutch mechanism 32e via the pressing spring 32f. And the electronic control unit 10 connected to the electronic control unit 10 controls the driving of the connecting gear 30A between the low speed and the high speed via the clutch mechanism 32e. This is a characteristic part of the present invention.

  That is, in the storage unit of the electronic control unit 10, a “threshold value” of the fuel flow rate for maintaining the load of the motor 31 within an appropriate range is set in advance, and the fuel flow rate indicated by the electronic control unit 10 However, the switching control is executed so that the connecting gear 30A is a low-speed gear if it is less than this “threshold value” and the high-speed gear is used while the “threshold value” is exceeded.

  Next, the operation of the fuel supply device for the engine according to the present embodiment will be described. The fuel discharge flow rate of the fuel pump 3A is proportional to the rotational speed of the motor 31, and the flow rate increases as the rotational speed increases, and the flow rate decreases as the rotational speed decreases. In addition, an instruction value for ensuring a fuel injection amount corresponding to the engine required fuel flow rate is output from the electronic control unit 10 to a motor driver (not shown) of the fuel pump 3A to discharge the fuel. During the normal output operation of the engine, the fuel pressure immediately before injection is detected by the pressure sensor 11 and the fuel pressure value for normal operation is maintained to avoid vaporization of the fuel in the pipe, while maintaining a predetermined fuel pressure (injection). Feedback control is performed to ensure pressure.

  Further, the electronic control unit 10 continuously detects the fuel temperature detected by the temperature sensor 11 disposed in the fuel supply pipe 2, and the detected fuel temperature data is detected to detect the throttle opening, etc. The fuel flow rate to be output to the injector 5 and injected is determined by taking into account the engine required fuel flow rate data.

  The electromagnetic solenoid 32g is controlled so as to maintain the state of the high-speed gear while it is determined that the fuel flow rate exceeds the preset and stored "threshold value". The "threshold value" is assumed to be coincident with the gear switching timing that is an appropriate timing based on the fuel flow rate of the engine and the load / power consumption data applied to the motor 31 based on a plurality of experimental results. You just have to decide.

  During normal operation, the motor 31 and the pump section are rotated in the state of a low speed gear in which the motor shaft 31a, the joint 32h, the clutch mechanism 32e, the low speed pinion gear 32c, the low speed driven gear 32d, and the pump shaft 34a are connected in this order. (Torque) is transmitted, and the motor 31 is operated with a relatively small load. At this time, the high speed driven gear 32a arranged on the pump shaft 34a is rotated, and the high speed pinion gear 32b is also rotated (but idle).

  On the other hand, when the required flow rate of the engine is relatively large and a flow rate that cannot be compensated by the setting of the low speed gear is required, the “threshold value” of the fuel flow rate set in the storage unit of the electronic control unit 10 ”, The electronic control unit 10 outputs a command signal to the electromagnetic solenoid 32g and slides the clutch position of the clutch mechanism 32c to switch to the high speed gear. In addition, since the gears are switched through the clutch mechanism in this way, the switching operation becomes smooth.

  Thus, the motor shaft 31a, the joint 32h, the clutch 32e, the high-speed pinion gear 32a, the high-speed driven gear 32b, and the pump shaft 34a are connected in this order to transmit torque, and the motor 31 is in a relatively heavy load state. It is driven by. At this time, the low speed driven gear 32d arranged on the pump shaft 34a is rotated, and the low speed pinion gear 32c is also rotated (however, idling).

  As described above, the fuel supply device for the engine of the present embodiment is configured so that the motor 31 is normally used in accordance with the actual condition that the high load condition is extremely small and the time is short in the engine required flow rate as shown in the graph of FIG. In some cases, driving is performed under a condition with a small load, and switching to driving under a high load condition is possible only when necessary. For this reason, waste of power consumption is eliminated, and rebound to fuel efficiency can be stopped to a minimum source.

  In the above description, the switching of the connecting gear has been described as a two-stage switching method for low speed and high speed, but is not limited to this, and the three stages for low speed, medium speed, high speed, etc. Other multi-stage switching methods may be used. Moreover, although the case where an electromagnetic solenoid is used as the actuator of the switching mechanism of the clutch mechanism has been described, the present invention is not limited to this, and other linear motions such as a hydraulic rod and a pneumatic actuator are used. Can be similarly implemented.

  As described above, the engine fuel supply device that controls the fuel pump by the control means can maintain the motor load of the fuel pump in an appropriate state while being able to cope with the maximum required flow rate of the engine according to the present invention. As a result, waste of power consumption can be minimized and fuel consumption can be improved. Furthermore, reducing the motor load leads to a longer life of the fuel pump.

The longitudinal section fragmentary view of the fuel pump of the fuel supply device of the embodiment in the present invention. The graph which shows the engine required fuel flow volume of the motor vehicle (normal passenger car) by the general use in a prior art example. The layout of the fuel supply system common to embodiment of this invention and a prior art example. The longitudinal cross-section fragmentary view of the fuel pump in the fuel supply apparatus of a prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fuel tank, 2 Fuel supply piping, 3A Fuel pump, 5 Injector, 10 Electronic control unit, 11 Pressure sensor, 12 Temperature sensor, 30A Connection gear, 31 Motor, 32a High speed pinion gear, 32b High speed driven gear, 32c Low speed pinion gear , 32d Low speed driven gear, 32e Clutch mechanism, 32f Press spring, 32g Electromagnetic solenoid, 32h Joint, 32i Rod

Claims (4)

  An electronic control unit controls the rotation speed of the fuel pump and the opening and closing of the injector to ensure a fuel injection amount corresponding to the required fuel flow rate while feedback controlling the drive of the fuel pump so as to maintain a predetermined fuel injection pressure. In the engine fuel supply device, the electronic control unit switches the connection gear according to the engine required flow rate by using a connection gear for connecting the motor rotation shaft and the pump shaft of the fuel pump as a multistage speed switching method. A fuel supply apparatus for an engine characterized by   2. The engine fuel supply apparatus according to claim 1, wherein the speed change of the connecting gear is performed based on a predetermined threshold value set in advance in the electronic control unit.   The engine fuel supply device according to claim 1 or 2, wherein the switching of the connecting gear is performed in two stages of a low speed gear and a high speed gear. 4. The engine fuel supply apparatus according to claim 1, wherein the connection gear is switched through a clutch mechanism that is operated by a predetermined actuator that is driven and controlled by the electronic control unit.

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