JPS6014909B2 - fuel injector - Google Patents

Description

[Detailed description of the invention] The present invention relates to improvements in fuel injection systems for internal combustion engines.

FIG. 1 shows a conventional fuel injection system for a multi-cylinder engine.

It is a multi-cylinder engine with an in-line injection pump that integrates the fuel injection pumps for each cylinder, and an injection system that connects the fuel injection valves of each cylinder and the injection pump with high-pressure pipes. In the figure, 1 is the engine body, 2 is the fuel injection pump, 31 to 34 are fuel injection valves for each cylinder, 41 to 44 are high-pressure injection pipes connecting pump 2 and injection valves 31 to 34, and 5 is fuel Reference numeral 61 indicates a fuel supply pipe connecting the filter 5 and the pump 2, 21 a fuel supply inlet joint, and 62 a fuel supply pipe connecting the filter 5 and the fuel tank (not shown). Fuel is supplied to the filter 5 from a fuel tank (not shown) through a fuel supply pipe 62 using its water head or a fuel supply pump.

Next, the fuel passes through the fuel supply pipe 61 and is supplied to the fuel supply chamber of the injection pump 2 from the fuel supply inlet joint 21. In the injection pump, the fuel supply chamber is common to the injection pump elements of each cylinder. In the injection pump 2, the injection pump element of the cylinder at the appropriate time pressurizes the fuel and releases it from the high pressure injection pipe 31 to 34.
Pressure feed to any of the following. Next, the fuel is fed under pressure to the corresponding fuel injection valve 41 to 44, and the fuel is supplied to the combustion chamber of that cylinder to cause combustion. This conventional device has the following drawbacks.

Generally, the length of the injection pump 2 is much shorter than that of the engine body 1.

The injection pump 2 is driven by gears or a chain from the crankshaft, and therefore the injection pump 2 is installed at the front or rear end of the engine where a gear train can be installed. For this reason, for example, in an engine with a gear train at the front end of the engine, the distance between the injection pump element of each cylinder of the injection pump 2 and the corresponding fuel injection valve may be shorter for the cylinder at the front end of the engine, or the distance between the cylinder at the rear end of the engine Now it's going to be long. On the other hand, it takes a certain amount of time for the pressure wave to propagate from the injection pump end to the injection valve end of the injection pipe, as shown below.

Now, the sound speed is a=1200/s, and the injection pipe length is lp=6.
Assuming that the engine rotation speed is 0 and the engine speed N8 is 300 pm,
This time is the crankshaft, a, ag = harm x 36oX equipment.

X6 willow. 0=90 Therefore, in order to make the injection timings of each cylinder the same, it is necessary to make the injection pipe lengths the same.

In order to match the lengths of the injection pipes, it is necessary to match the length of the injection pipes with the longest one in this engine's configuration. As mentioned above, since it takes a certain amount of time for pressure to propagate from the injection pump end to the injection valve end, there is a certain time delay from when the injection pump starts pressure feeding until actually injecting.

This is called injection delay, but since the speed at which pressure waves propagate, that is, the speed of sound, is unrelated to the rotational speed, when expressed in terms of crank angle, as shown in FIG. 2, the higher the rotation, the greater the injection delay. In addition, in the figure, CA indicates a crank angle. On the other hand, in order to obtain better efficiency, combustion should occur at an appropriate time near top dead center, but the crank angle from when fuel is injected until it ignites (referred to as ignition delay) also increases as the rotation speed increases. Generally, the higher the rotation, the earlier the optimum injection timing (Figure 3).

In other words, demands and reality tend to be opposite. Therefore, a device (autotimer) that detects the engine rotation speed using centrifugal force and advances the phase of the injection pump cam at high rotation speeds has been considered, but it is expensive and is not suitable for agricultural machinery, etc., which should be inexpensive. It is difficult to use. That is, engines without an autotimer have the disadvantage that optimal timing can only be obtained at a specific rotation speed.

An object of the present invention is to provide a fuel injection device that improves the characteristics of injection delay in a fuel-injected internal combustion engine and can obtain better performance from low rotation to high rotation. , its characteristics are '1
1. Shorten the distance between the fuel injection pump and fuel injection valve, shorten the length of the cylinder's high-pressure injection pipe, and (1) refuel the injection pump from the side of the cylinder where the high-pressure injection pipe is long.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 4 is an explanatory diagram showing one embodiment of the fuel injection device according to the present invention.

In the figure, numerals 1, 2, 5, 21, 31 to 34, 41 to 44, and 61, 62 indicate the same members as in FIG. 1.

The fuel injection valve 31 is farthest from the fuel injection pump 2, and the fuel injection valve 34 is the closest, but correspondingly, the high-pressure injection pipe 41 is the longest and the high-pressure injection pipe 44 is the shortest.

Moreover, the position of the oil supply inlet joint 21 is installed on the side of the pump element corresponding to the longest high-pressure injection pipe 41.

The high-pressure injection pipes 41 to 44 are connected in the order of their length from the pump element on one end of the fuel injection pump 2 to the pump element on the other end. The functions and effects of the above configuration will be described.

The process by which fuel is supplied from the fuel tank to the engine combustion chamber is almost the same as in the conventional system, but the injection delay characteristics are different as follows. The longest cylinder with high pressure injection pipe is the first cylinder 1.
For short, they are called the second cylinder D, the third cylinder m, and the fourth cylinder N, in order.

The engine temperature is generally high and the temperature of the fuel injection pump is also much higher than the fuel being supplied.

Therefore, the fuel supplied to the fuel injection pump is heated. In this structure, fuel is supplied to the fuel injection pump from the first cylinder 1 side and is then guided to the second and third cylinders 0 and melon side, but during this time it is heated as described above, so that the fuel injection pump is supplied to the fuel injection pump. The fuel oil temperature becomes higher in the cylinder. Therefore, from the high pressure pipe 41, 44
The temperature of the fuel that is pumped to cylinders 1, 2, 2, and so on increases in that order. On the other hand, it is known that the higher the fuel temperature, the lower the speed of sound in fuel.

For example, the relationship between fuel oil temperature and injection delay is
It will look like the figure. That is, in this structure, in the first cylinder 1, the high-pressure injection pipe is long, but the fuel temperature is low, so the injection delay is short.In the fourth cylinder W, the fuel temperature is high, but the high-pressure injection pipe is short. So, the injection delay is short. That is, the injection delay is shortened for all cylinders. In addition, by appropriately selecting the pipe length, the injection delays of all cylinders can be made uniform.

In this way, as shown in FIG. 6, it is possible to improve the injection delay characteristics. According to the present invention as described above,
Compared to conventional engines, the injection delay is shortened and the timing is closer to optimal at all revolutions, significantly improving engine performance.

[Brief explanation of drawings]

Figure 1 is an explanatory diagram showing a conventional fuel injection system, Figure 2 is a diagram showing the relationship between injection delay and engine speed, Figure 3 is a diagram showing the optimum injection timing with respect to engine speed, and Figure 4 is a diagram showing the optimal injection timing with respect to engine speed. The figure is an explanatory diagram showing a device according to one embodiment of the present invention, Figure 5 is a green diagram showing the relationship between injection delay and fuel temperature, and Figure 6 is a comparison of injection delays between the conventional system and the system of the present invention. FIG. 1... Engine body, 2... Fuel injection pump,
21... Oil supply inlet joint, 31, 32, 33, 3
4... Fuel injection valve, 41, 42, 43, 44.
...High pressure injection pipe, 5...Fuel filter,
61, 62... Oil supply pipe. 4 figures, 2 figures, 3 figures, 4 figures, 5 figures, 6 figures

Claims (1)

[Claims] 1. A high-pressure pump that connects a row-type fuel injection pump integrally formed with each fuel injection pump element corresponding to each cylinder of the engine, and each pump element of the fuel injection pump that corresponds to the fuel injection valve of each cylinder. In the fuel injection device having an injection pipe, the high-pressure injection pipe is formed to have a short length in a cylinder where the distance between the fuel injection pump and the fuel injection valve is small, and to be long in a cylinder where the distance is large, and to Each pump element of the fuel injection pump is connected from the valve to the other end in order of length, and the fuel inlet of the fuel injection pump is located near the pump element to which the longest high-pressure injection pipe is connected. A fuel injection device characterized by being provided.