JP2006348818A - Fuel supply control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce fuel pressure in a fuel supply pipe after stopping the operation of an internal combustion engine without requiring much power consumption. <P>SOLUTION: An ECM 9 calculates the pressure reducing rate of fuel pressure in the fuel supply pipe 2 after stopping the operation of the internal combustion engine in accordance with a fuel temperature in the fuel supply pipe 2, sets the target opening of a relief valve 6 in accordance with the calculated pressure reducing rate, and feedback controls the opening of the relief valve 6 so that the opening of the relief valve 6 is the target opening. At the stage when the opening of the relief valve 6 reaches the target opening, the energization of the relief valve 6 is stopped to fix the opening of the relief valve 6. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a fuel supply control device that reduces fuel pressure in a fuel supply pipe after operation of an internal combustion engine is stopped.

Conventionally, after the operation of the internal combustion engine is stopped, the fuel in the fuel supply pipe is controlled by feedback control of the opening degree of the release valve that returns the fuel in the fuel supply pipe to the fuel tank based on the detection results of the fuel temperature sensor and the fuel pressure sensor. There is known a fuel supply control device that lowers temperature and fuel pressure (see Patent Document 1). According to such a fuel supply control device, it is possible to prevent the fuel from leaking from the injector and the occurrence of vapor in the fuel supply pipe after the operation of the internal combustion engine is stopped.
JP-A-9-42109

  However, since the conventional fuel supply control device is configured to reduce the fuel pressure in the fuel supply pipe by feedback control after the operation of the internal combustion engine is stopped, the ECM and the relief valve are not operated even after the operation of the internal combustion engine is stopped. Electric power needs to be supplied, and the burden on the battery is large. In addition, fuel efficiency deteriorates to supplement the power consumption of the ECM and relief valve. In order to solve such a problem, a method of separately providing a battery is conceivable. However, when this method is used, the cost of the internal combustion engine increases.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a fuel supply capable of reducing the fuel pressure in the fuel supply pipe after the operation of the internal combustion engine is stopped without consuming a lot of electric power. It is to provide a control device.

  In order to achieve the above object, a fuel supply control device according to the present invention calculates a pressure reduction ratio of a fuel pressure in a fuel supply pipe after the operation of the internal combustion engine is stopped based on at least a fuel temperature in the fuel supply pipe. The target opening of the relief valve is set based on the reduced pressure ratio, and the relief valve opening is feedback-controlled so that the relief valve opening becomes the target opening, and the relief valve opening reaches the target opening. At this stage, the opening of the relief valve is fixed by stopping energization of the relief valve.

  According to the fuel supply control device of the present invention, after the operation of the internal combustion engine is stopped, the fuel pressure in the fuel supply pipe is reduced with the minimum power consumption, and fuel leakage from the injector and generation of vapor in the fuel supply pipe are prevented. Can be prevented.

  Hereinafter, a configuration of a fuel supply control device according to an embodiment of the present invention will be described with reference to the drawings.

  As shown in FIG. 1, a fuel supply control device according to an embodiment of the present invention is stored in a fuel tank 1 in a fuel tank 1 for storing fuel supplied to an internal combustion engine and an injector 3 via a fuel supply pipe 2. A fuel pump 4 that supplies fuel, a relief pipe 5 that returns the fuel in the fuel supply pipe 2 to the fuel tank 1, and a relief valve 6 that can adjust the fuel flow rate in the relief pipe 5 stepwise or steplessly. A fuel temperature sensor 7 and a fuel pressure sensor 8 that detect the fuel temperature and fuel pressure in the fuel supply pipe 2, and an ECM 9 that controls the opening degree of the relief valve 6 with reference to the detection results of the fuel temperature sensor 7 and the fuel pressure sensor 8. With. The relief valve 6 is constituted by a valve such as a step motor capable of maintaining the current opening even when the power is off. The ECM 9 calculates a target fuel pressure according to the operating state of the internal combustion engine, and controls the operation of the fuel pump 4 based on the calculated target fuel pressure.

  In the fuel supply control apparatus having such a configuration, the ECM 9 executes the following fuel supply control process, so that the battery supply pipe 2 in the fuel supply pipe 2 is stopped after the operation of the internal combustion engine is stopped without placing a heavy burden on the battery. Reduce fuel pressure. The operation of the ECM 9 when executing this fuel supply control process will be described below with reference to the flowchart shown in FIG.

  The flowchart shown in FIG. 2 starts in response to the start of the internal combustion engine, and the fuel supply control process proceeds to step S1.

  In step S1, the ECM 9 determines whether or not the internal combustion engine stop condition is satisfied. Then, the ECM 9 advances the fuel supply control process to the process of step S2 when the internal combustion engine stop condition is satisfied.

  In the process of step S2, the ECM 9 detects the fuel temperature in the fuel supply pipe 2 by the fuel temperature sensor 7, and shows the relationship between the opening of the relief valve and the fuel temperature in the fuel supply pipe 2 as shown in FIG. With reference to the map, the target opening degree (reduction rate) of the relief valve 6 corresponding to the detected fuel temperature is calculated. Thereby, the process of step S2 is completed, and the fuel supply control process proceeds to the process of step S3.

  In the process of step S3, the ECM 9 adjusts the opening of the relief valve 6 so as to reach the target opening calculated by the process of step S2, and decreases the fuel pressure in the fuel supply pipe 2. Thereby, the process of step S3 is completed, and the fuel supply control process proceeds to the process of step S4.

  In the process of step S4, the ECM 9 determines whether or not the opening degree of the relief valve 6 has reached the target opening degree calculated by the process of step S2 by an opening sensor (not shown). As a result of the determination, when it is determined that the opening degree of the relief valve 6 has not reached the target opening degree, the ECM 9 returns the fuel supply control process to the process of step S3. On the other hand, when it is determined that the opening degree of the relief valve 6 has reached the target opening degree, the ECM 9 advances the fuel supply control process to the process of step S5.

  In the process of step S5, the ECM 9 turns off the power in the order of the fuel pump 4, the relief valve 6, and the ECM 9. Thereby, the process of step S5 is completed, and the fuel supply control process proceeds to the process of step S6.

  In the process of step S6, the opening degree of the relief valve 6 is maintained at the target opening degree even after the power is turned off, so that the fuel in the fuel supply pipe 2 returns to the fuel tank 1 through the relief pipe 5, and the fuel supply pipe The fuel pressure in 2 decreases in steps. For this reason, it is possible to prevent vapor from being generated in the fuel supply pipe 2 due to rapid pressure reduction under a high temperature condition. Thereby, the process of step S6 is completed and a series of fuel supply control processes are complete | finished.

  As is clear from the above description, according to the fuel supply control device according to the embodiment of the present invention, the ECM 9 is operated in the fuel supply pipe 2 after the operation of the internal combustion engine is stopped based on the fuel temperature in the fuel supply pipe 2. The pressure reduction ratio of the fuel pressure is calculated, the target opening degree of the relief valve 6 is set based on the calculated pressure reduction ratio, and the opening degree of the relief valve 6 is set so that the opening degree of the relief valve 6 becomes the target opening degree. In addition to feedback control, when the opening degree of the relief valve 6 reaches the target opening degree, the opening degree of the relief valve 6 is fixed by stopping energization of the relief valve 6. The fuel pressure in the fuel supply pipe 2 can be reduced with a minimum amount of power consumption, and fuel leakage from the injector 3 and the occurrence of vapor in the fuel supply pipe 2 can be prevented. Moreover, the oil tightness of the injector 3 can be improved by lowering the fuel pressure in the fuel supply pipe 2. In addition, since the fuel flow rate in the fuel supply pipe 2 is adjusted when the operation of the internal combustion engine is stopped and no feedback control is performed after the power is turned off, the power consumption can be minimized.

  In addition, according to the fuel supply control device according to the embodiment of the present invention, the ECM 9 stops energizing the ECM 9 after stopping energizing the relief valve 6. Stopping energization of the ECM 9 prevents the control signal output to the relief valve 6 from being stopped and the relief valve 6 from closing, and the relief valve 6 is opened after the energization is stopped. Can be maintained.

  As mentioned above, although the embodiment to which the invention made by the present inventor is applied has been described, the present invention is not limited by the description and the drawings that form part of the disclosure of the present invention according to this embodiment. That is, it should be added that other embodiments, examples, operation techniques, and the like made by those skilled in the art based on the above embodiments are all included in the scope of the present invention.

It is a schematic diagram which shows the structure of the fuel supply control apparatus used as embodiment of this invention. It is a flowchart figure which shows the flow of the fuel supply control process used as embodiment of this invention. It is a map figure which shows the relationship between the opening degree of a relief valve, and fuel temperature.

Explanation of symbols

1: Fuel tank 2: Fuel supply pipe 3: Injector 4: Fuel pump 5: Relief pipe 6: Relief valve 7: Fuel temperature sensor 8: Fuel pressure sensor 9: ECM

Claims (2)

A fuel supply control device for controlling a fuel pressure in a fuel supply pipe by controlling an opening degree of a relief valve provided in a fuel supply pipe for supplying fuel to an internal combustion engine,
Calculating means for calculating a reduction ratio of the fuel pressure in the fuel supply pipe after the operation of the internal combustion engine is stopped based on at least the fuel temperature in the fuel supply pipe;
Target opening degree setting means for setting a target opening degree of the relief valve based on the decompression ratio calculated by the calculating means;
Opening degree control means for feedback controlling the opening degree of the relief valve so that the opening degree of the relief valve becomes the target opening degree set by the target opening degree setting means;
A fuel supply control device comprising: an energization control unit that fixes the opening of the relief valve by stopping energization to the relief valve when the opening of the relief valve reaches the target opening. The fuel supply control device according to claim 1,
The fuel supply control device is a control unit including electronic parts, and the energization control unit controls the energization to the control unit to be stopped after the energization to the relief valve is stopped. Fuel supply control device.

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