JP2007187058A - Fuel injection type engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a novel structure capable of inhibiting increase of manufacturing cost in a dual injection type engine. <P>SOLUTION: Fuel pressurized to mutually same pressure by a common fuel pump 12 is supplied to a cylinder injection valve 8 and a port injection valve 9 without installing a high pressure pump for cylinder injection. Since it is not necessary to provide a structure supplying fuel of different pressure to the cylinder injection valve 8 and the port injection valve 9 and it is not necessary to individually control a high pressure pump and a fuel pump, control can be simplified. Consequently, increase of manufacturing cost can be inhibited by using a fuel supply path and control in common. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a fuel injection engine having a port injection valve and an in-cylinder injection valve.

  Conventionally, a dual injection type engine in which fuel injection valves are installed in both an intake port and a combustion chamber has been put into practical use (see, for example, Patent Document 1). In this type of engine, for example, both port injection and in-cylinder injection are operated in a low and medium load range to form a homogeneous air-fuel mixture, thereby stabilizing combustion and reducing emissions and improving fuel consumption. On the other hand, in the high load region, the port injection is stopped and only the in-cylinder injection is performed, thereby improving the charging efficiency by the intake air cooling effect, suppressing knocking, increasing the high compression ratio, and improving the output.

JP 2005-139922 A

  In such a dual injection type engine, a low pressure pump common to the port injection valve and the in-cylinder injection valve is provided for fuel supply, while a high pressure is provided in the fuel supply path to the in-cylinder injection valve. A pump and a delivery pipe are provided so that fuel is supplied to the in-cylinder injection valve at a pressure higher than that of the port injection valve.

  However, this configuration requires the use of a plurality of pumps in order to supply different fuel pressures to the two types of fuel injection valves, and there is a problem that the manufacturing cost becomes very high.

  Accordingly, an object of the present invention is to provide a novel configuration capable of suppressing the manufacturing cost in a dual injection engine.

  A first aspect of the present invention is a fuel injection type engine including an in-cylinder injection valve that supplies fuel to a combustion chamber, and a port injection valve that supplies fuel to an intake port. A fuel injection engine comprising a fuel supply means for supplying fuel pressurized to the same pressure to the port injection valve.

  In the first aspect of the present invention, fuel pressurized to the same pressure is supplied to the in-cylinder injection valve and the port injection valve. Therefore, fuels of different pressures are supplied to the in-cylinder injection valve and the port injection valve. There is no need to provide a structure, and the manufacturing cost can be reduced by sharing the fuel supply path and control.

  According to a second aspect of the present invention, the fuel supply means includes a delivery pipe for accumulating pressure, and the in-cylinder injection valve and the port injection valve are connected to the common delivery pipe. Expression engine.

  In the second aspect of the present invention, since the delivery pipe is shared by the port injection valve and the in-cylinder injection valve, the manufacturing cost can be further suppressed by simplifying the structure.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In FIG. 1, a bi-fuel engine 1 to which the present invention is applied has a cylinder block 2 and a cylinder head 3, and a piston 4 is slidably installed in the cylinder block 2. The cylinder head 3 is formed with an intake port 5, an exhaust port 6 and a combustion chamber 7.

  An in-cylinder injection valve 8 is installed in the cylinder head 3 toward the combustion chamber 7. A port injection valve 9 is installed in the intake port 5. A spark plug 10 is installed at the top of the combustion chamber 7. Although FIG. 1 shows the structure for one cylinder, the engine 1 has four cylinders, each of which has a similar structure.

  As shown in FIG. 2, the vehicle according to the present embodiment includes a fuel tank 11 and an electric fuel pump 12 for supplying fuel from the fuel tank 11 to the engine 1. The fuel pipe 13 on the discharge side of the fuel pump 12 branches in two directions from the middle, and has an in-cylinder fuel pipe 13a and a port fuel pipe 13b. The in-cylinder fuel pipe 13a is connected to the in-cylinder fuel delivery pipe 14a. The port fuel pipe 13b is connected to the port fuel delivery pipe 14b. A plurality of in-cylinder injection valves 8 are connected to the in-cylinder fuel delivery pipe 14a, and a plurality of port injection valves 9 are connected to the port fuel delivery pipe 14b, respectively, according to the number of cylinders.

  In a normal in-cylinder injection engine, a high-pressure pump is provided in addition to a low-pressure pump that supplies feed pressure in a fuel pipe that is directed to the in-cylinder injection valve. The pressure on the discharge side of the high-pressure pump is, for example, 12 MPa. However, in this embodiment, no high-pressure pump is provided, and the discharge pressure (feed pressure) from the fuel pump 12 is higher than the conventional feed pressure and lower than the conventional feed pressure, for example, 2 MPa. And

  A pump drive circuit (EDU) 21 for driving the fuel pump 12 is connected. The in-cylinder injection valve 8 and the port injection valve 9 are connected to an injection valve drive circuit (EDU) 22 for individually driving them. These EDUs 21 and 22 are connected to an electronic control unit (ECU) 30, and drive the fuel pump 12, the in-cylinder injection valve 8, and the port injection valve 9 in accordance with output signals from the ECU 30.

  The ECU 30 is configured as a well-known digital computer having a one-chip microprocessor, and is a ROM (read only memory), a RAM (random access memory), and a CPU (microprocessor) that are connected to each other via a bidirectional bus. A B-RAM (backup RAM) that is always connected to a power source, an input port, an output port, an A / D converter, a D / A converter, and the like are provided. Sensors (not shown) for detecting various physical quantities indicating the state of the vehicle are connected to the input port of the ECU 30 via an A / D converter. Such sensors are, for example, in the vicinity of the crankshaft. A crank angle sensor that detects the engine speed, an accelerator pedal sensor that detects the amount of depression of the accelerator pedal, a throttle sensor that detects the opening of the throttle valve, and an air flow meter that detects the intake air amount And an engine water temperature sensor for detecting the engine water temperature. The output ports of the ECU 30 are connected to the spark plug 10, the in-cylinder injection valve 8, the port injection valve 9, the fuel pump 12 and the like via the corresponding D / A converter and the drive circuits such as the above-described EDUs 21 and 22, respectively. Has been.

  In the present embodiment configured as described above, the pump EDU 21 is controlled by the control output from the ECU 30, and the fuel pump 12 is controlled so that its feed pressure matches a predetermined value (for example, 2 MPa). As a result, fuel is supplied to both the in-cylinder injection valve 8 and the port injection valve 9 by the feed pressure from the fuel pump 12.

  The injection valve EDU22 is controlled by the control output from the ECU 30 based on the detection value of each sensor, and the in-cylinder injection valve 8 and the port injection valve 9 are driven at a predetermined timing. As a result, for example, by operating both port injection and in-cylinder injection in the low and medium load ranges, the formation of a homogeneous mixture can stabilize combustion, reduce emissions, and improve fuel efficiency. In the region, the port injection is stopped and only the in-cylinder injection is performed, so that the charging efficiency can be improved by the intake air cooling effect, knocking can be suppressed, the high compression ratio, and the output can be improved.

  As described above, in this embodiment, the high pressure pump is not installed, and the fuel pressurized to the same pressure by the common fuel pump 12 is supplied to the in-cylinder injection valve 8 and the port injection valve 9. It is not necessary to provide a structure for supplying fuel of different pressures to the in-cylinder injection valve 8 and the port injection valve 9, and it is not necessary to individually control the high-pressure pump and the fuel pump, thereby simplifying the control. it can. That is, in this embodiment, the manufacturing cost can be suppressed by sharing the fuel supply path and control.

  In addition, since the conventional high pressure pump is not used, fuel is supplied to the in-cylinder injection valve 8 and the port injection valve 9 at a lower pressure (2 MPa) than the discharge pressure (for example, 12 MPa) of the conventional high pressure pump. A desired fuel pressure can be obtained quickly even immediately after starting, such as during cold starting. Further, since the injection pressure by the port injection valve 9 is higher than the conventional feed pressure (for example, 0.3 to 0.4 MPa), the atomization of fuel in the intake port 5 is good. Therefore, in the present embodiment, it is possible to suppress a decrease in engine performance caused by the injection pressure of the in-cylinder injection valve 8 being lower than before.

  Next, a second embodiment will be described. In FIG. 3, in the vehicle according to the second embodiment, the in-cylinder injection valve 8 and the port injection valve 9 are connected to a common delivery pipe 114. A fuel pipe 113 from a common fuel pump is connected to the delivery pipe 114. In addition, since the remaining structure in 2nd Embodiment is the same as that of the said 1st Embodiment, the same code | symbol is attached | subjected to the same member and the detailed description is abbreviate | omitted.

  Therefore, in the second embodiment, since the delivery pipe 114 is shared by the port injection valve 9 and the in-cylinder injection valve 8, the manufacturing cost can be further suppressed by simplifying the structure.

  In each of the above embodiments, the feed pressure from the fuel pump 12 is 2 MPa. However, the value of the feed pressure from the fuel pump 12 is not limited to this, and preferably 1 to 3 MPa. Particularly good injection from the in-cylinder injection valve 8 can be executed. In each of the above embodiments, the feed pressure from the fuel pump 12 is a fixed value, but the feed pressure from the fuel pump 12 may be variable.

  In the above embodiment, an example in which gasoline is used as the fuel has been described. However, hydrocarbons such as isooctane, hexane, heptane, light oil, and kerosene as fuel, or carbon such as butane and propane that can be stored in a liquid state. Needless to say, hydrogen or methanol can be used.

It is sectional drawing which shows the principal part of the engine of the dual injector system which concerns on 1st Embodiment of this invention. It is a conceptual diagram which shows schematic structure of 1st Embodiment. It is a conceptual diagram which shows schematic structure of 2nd Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Engine 8 In-cylinder injection valve 9 Port injection valve 11 Fuel tank 12 Fuel pump 13, 113 Fuel piping 13a In-cylinder fuel piping 13b Port fuel piping 14a In-cylinder fuel delivery pipe 14b Port fuel delivery pipe 30 Electronic control unit (ECU)
114 Delivery pipe

Claims (2)

A fuel injection type engine comprising: an in-cylinder injection valve that supplies fuel to a combustion chamber; and a port injection valve that supplies fuel into an intake port;
A fuel injection engine comprising: fuel supply means for supplying fuel pressurized to the same pressure to the cylinder injection valve and the port injection valve. The fuel injection engine according to claim 1,
The fuel supply means includes a delivery pipe for accumulating pressure, and the in-cylinder injection valve and the port injection valve are connected to the common delivery pipe.

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