JPH024783B2 - - Google Patents

Description

[Detailed description of the invention]

[Field of Application of the Invention] The present invention relates to a fuel injection device for an internal combustion engine.
In particular, the present invention relates to a fuel injection device suitable for reducing engine torque fluctuations. [Prior Art] For example, as shown in FIG. 1, a fuel injection injector 3 is provided in the intake pipe 2 of the engine 1, and fuel is supplied to the injector 3 from a fuel tank 4 via a fuel filter 5, a fuel pump 6, etc. The fuel is supplied through the supply pipe 7 and injected through the injector 3, for example, in the
It is well known from Publication No. 5133. Further, a fuel pressure regulator 8 is provided in the middle of the fuel supply pipe 7,
This fuel pressure regulator 8 controls the injector 3.
It is also known to keep the fuel pressure supplied to the engine constant. By the way, fuel pressure regulator 8
includes a control chamber 10 of the overpressure fuel spill type, generally separated by a diaphragm 9;
A pressure receiving chamber 11 that sets pressure in the control chamber 10 via
It has The diaphragm 9 has a seat part 9
A is provided in the control room 10, and an overflow pipe 10A is provided in the control room 10, which comes into contact with and leaves the seat portion 9A relatively. The diaphragm 9 connects the seat portion 9A to the overflow pipe 10.
A is pressed at a predetermined pressure by a compression coil spring 12, and the control chamber 10 is connected to the fuel tank 4 via an outlet 10B by a return pipe 13 to recover overpressure fuel into the fuel tank 4. It's like this. Further, the pressure receiving chamber 11 communicates with the atmosphere through, for example, a communication port 11A, and is configured to allow deformation of the diaphragm 9. By the way, in the case of the fuel pressure regulator 8 of the type in which the pressure receiving chamber 11 is communicated with the atmosphere, there is a problem that when the diaphragm 9 is damaged, fuel is released from the control chamber 10 to the atmosphere via the pressure receiving chamber 11. As shown in the figure, the pressure receiving chamber 11 is connected to the ventilation pipe 11B.
Therefore, it has been considered to take measures to connect the leaked fuel to the intake pipe 2 of the engine so that the leaked fuel can be supplied to the engine side. In addition, this ventilation pipe 11B
In order to prevent excessive negative pressure from acting, it is desirable to communicate with the throttle valve 14 upstream of the throttle valve 14, that is, between the throttle valve 14 and the air cleaner 15.
Reference numeral 16 in FIG. 2 indicates an air flow meter for controlling the amount of fuel supplied. Therefore, in the fuel injection device shown in FIG. 2, due to the characteristics of the compression coil spring 12 of the fuel pressure regulator 8, the vent pipe 11B, etc., the fuel supply pressure P ₁ to the injector 3 via the fuel pressure regulator 8 and the intake air The differential pressure (P ₁ −Pm) between the intake pressure and the negative pressure Pm in the pipe 2 is controlled to be substantially constant.
For example, as shown in the table below, this control value tends to be such that the supplied fuel pressure _P1 increases according to the opening degree of the throttle valve, and the intake pressure Pm decreases according to the opening degree of the throttle valve, and when the throttle valve is fully opened, Since the intake pressure Pm is approximately equal to atmospheric pressure, the fuel supply pressure P ₁ is finally set by the elastic pressing force of the compression spring 12.

【table】

[Purpose of the invention]

The present invention has been made in view of the above circumstances, and is intended to prevent pressure fluctuations in the intake pipe due to intake air interference from acting on the fuel pressure regulator, thereby reducing the range of fluctuations in the air-fuel ratio, and thereby reducing the fluctuation range of the air-fuel ratio. It is an object of the present invention to provide a fuel injection device that can reduce torque fluctuations and improve driving performance. [Summary of the Invention] In order to achieve the above object, the present invention includes a vent pipe that communicates the pressure receiving chamber of the fuel pressure regulator with the intake pipe, and a connection portion of the vent pipe to the intake pipe for transmitting pressure fluctuations to the pressure receiving chamber of the fuel pressure regulator. The structure is equipped with a pressure absorption pipe line for prevention. Specifically, the pressure absorption pipe is constructed by a small diameter bypass pipe which is arranged in parallel with the intake pipe with both ends thereof communicating with each other. Alternatively, the pressure absorption pipe line may be constituted by a surge tank section formed by expanding a part of the ventilation pipe over a certain length. [Embodiment of the Invention] An embodiment of the present invention will be described below with reference to FIG. It should be noted that the same components as those of the conventional fuel injection device are designated by the same reference numerals as in FIGS. 1 and 2, and the explanation thereof will be omitted. The pressure receiving chamber 11 of the fuel pressure regulator 8 and the intake pipe 2 are communicated with each other through a ventilation pipe 11B.
In this device, a pressure absorption pipe line 17 is provided at the connection portion of the ventilation pipe 11B to the intake pipe 2 to prevent pressure fluctuations such as vibrations due to intake air interference transmitted from the intake pipe 2 to the pressure receiving chamber 11 of the fuel pressure regulator 8. I'm trying to get comfortable. This pressure absorption pipe line 17 is connected to the intake pipe 2.
It is constructed by small-diameter bypass pipes 18 arranged in parallel with both ends communicating with each other. That is, the bypass pipe 18 is formed to be located between the throttle valve 14 of the intake pipe 2 and the air cleaner 19. For example, the bypass pipe 18 is formed to be located between the throttle valve 14 of the intake pipe 2 and the air cleaner 19. The bottom part and the side wall part of the intake pipe 2 are communicated with each other.
A ventilation pipe 11 is installed approximately in the middle of this bypass pipe 18.
B is connected. Note that the passage cross-sectional area of the bypass pipe 18 is set to, for example, 1/25 of that of the intake pipe 2. In addition, the length l ₁ between the upper and lower communication ports of the bypass pipe 18 is
This bypass pipe 18 is set to be smaller than the entire length l ₂ of the upstream side of the intake pipe 2 from the lower communication port. According to such a configuration, the fuel pressure regulator 8
For example, when the air-fuel ratio is set to 15, the air-fuel ratio fluctuation range is ±0.1 to 0.2% compared to the case where the ventilation pipe 11B directly communicates with the intake pipe 2.
It was confirmed that the fluctuation range can be reduced compared to 0.5%. In addition, torque fluctuation is reduced to 0.05%, which is significantly reduced compared to the conventional 0.2%.
It was found that the drivability was also good. That is, theoretically, the pulsations in the intake pipe 2 due to intake air interference due to the vertical movement of the engine piston are not directly transmitted to the fuel pressure regulator 8, and as a result, the displacement of the diaphragm 9 is stabilized, and the fuel supply pressure to the injector 3 is increased. It is thought that this is based on the fact that it is also stable. In the above embodiment, the bypass pipe 18 communicates the bottom surface of the air horn 20 with the side wall surface of the intake pipe 2, but the same effect as described above can be obtained even if the bypass pipe 18 is implemented in a type without the air horn 20. Of course you can. Further, in the embodiment described above, the pressure absorption pipe line 17 was configured by the bypass pipe 18, but the present invention is not limited to this, and for example, as shown in FIG.
It can also be configured by a surge tank section 21 formed by expanding a part of the ventilation pipe 11B over a certain length. For example, the inner diameter of the surge tank section 21 is set to 15/42 of the inner diameter of the intake pipe 2, and the length _l3 of the surge tank section 21 is about 50 mm. It was confirmed that even with such a configuration, the same effects as those of the above embodiment can be achieved. It goes without saying that modifications such as adopting a configuration in which the surge tank section 21 and the bypass pipe 18 are used in combination are also possible. [Effects of the Invention] As described in detail in the above embodiments, the present invention includes a pressure absorbing pipe line for preventing pressure fluctuations from being transmitted to the pressure receiving chamber of the fuel pressure regulator at the connection part of the ventilation pipe to the intake pipe. This prevents pulsations in the intake pipe from being transmitted to the pressure receiving chamber of the fuel pressure regulator, stabilizes the displacement of the diaphragm, and significantly reduces fluctuations in the air-fuel ratio and engine torque, resulting in stable driving. This is extremely effective in ensuring performance.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram showing a conventional example, FIG. 2 is a schematic configuration diagram showing a different conventional example, FIG. 3 is a sectional view of essential parts showing an embodiment of the present invention, and FIG. FIG. DESCRIPTION OF SYMBOLS 1... Engine, 2... Intake pipe, 3... Injector, 4... Fuel tank, 8... Fuel pressure regulator, 9... Diaphragm, 10... Control room, 1
1... Pressure receiving chamber, 11b... Ventilation pipe, 17... Pressure absorption pipe line, 18... Bypass pipe, 21... Surge tank section.

Claims (1)

[Scope of Claims] 1. A fuel injection device for injecting fuel into an intake pipe of an engine through an injector, the fuel supply pipe from the fuel tank to the injector being equipped with a fuel pressure regulator, the fuel pressure regulator being a pressure-sensitive type. It has an overpressure fuel overflow type control chamber separated by a diaphragm and a pressure receiving chamber that sets pressure in the control chamber via the diaphragm, and this pressure receiving chamber is communicated with the intake pipe via a vent pipe. In this device, the difference between the fuel pressure and the intake pipe internal pressure is controlled to be constant by A fuel injection device characterized by comprising a conduit. 2. The fuel injection device according to claim 1, wherein the pressure absorption pipe is constituted by a small-diameter bypass pipe arranged in parallel with the intake pipe, with both ends communicating with the intake pipe. 3. The fuel injection device according to claim 1, wherein the pressure absorption pipe is constituted by a surge tank portion formed by expanding a part of the ventilation pipe in diameter over a certain length.