JPS6118216Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an exhaust gas recirculation (hereinafter referred to as EGR) device that recirculates a portion of exhaust gas to the intake system, and particularly relates to an EGR device for a diesel engine.

In diesel engines, it depends on the load.
It is considered desirable to control the amount of EGR, so in diesel engines with mechanical governors, the opening degree of the control lever of the fuel injection pump is usually detected and the amount of EGR is controlled accordingly.

However, the opening degree of the fuel injection pump control lever cannot be said to accurately represent the engine load condition, and therefore it cannot be said that the opening degree of the fuel injection pump control lever accurately represents the engine load condition.
It cannot be said that the amount of EGR is controlled.

For example, when a so-called distribution type fuel injection pump is used as a fuel injection pump, the position change of the spill ring is transmitted to the control lever via a complicated link mechanism, so the control lever opening degree accurately reflects the engine load condition. Not expressed in

Therefore, an object of the present invention is to provide an EGR device that is capable of accurately controlling EGR according to the load, has a simple structure, is easy to install, and has high practical value.

The present invention will be described below with reference to embodiments shown in the drawings.

In FIG. 1, an EGR pipe 2 opens in an intake pipe 1 of a diesel engine (not shown), and the opening is connected to an EGR pipe 2 rotatably installed in the intake pipe 1.
It is opened and closed by a control valve 3. The EGR control valve 3 is driven by an actuator 4, which includes a piston 42 that receives pressure in a piston chamber 41, a shaft 43 that connects the piston 42 to the EGR control valve 3, and a spring 44. On the other hand, the fuel pressure-fed from the first feed pump 5 driven by, for example, an electric motor is adjusted to a constant pressure (P ₁ ) by a pressure regulator 6 and then sent to the distribution-type fuel injection pump 7. It will be done.
This pump 7 has a built-in second feed pump 72, for example, a vane type, which is driven by a pump camshaft 71 that rotates in synchronization with the engine, and the engine from the first feed pump 5 is connected to a differential pressure valve 8 and an injection amount sensor. 9, the pressure becomes slightly lower (P ₂ ), and the fuel is sent to the suction side of the second feed pump 72.
The pressure (P ₄ ) is increased by an amount corresponding to the rotation speed. The fuel injection pump 7 distributes and pressure-feeds fuel to each cylinder of the engine using a distribution/pressure-feeding plunger (not shown) built therein. Note that 73 is a leak fuel pipe. The differential pressure valve 8 has first and second pressure chambers 82 and 83 formed by a diaphragm 81, one end of a nozzle 84 opens into the first pressure chamber 82, and a spring 85 opens into the second pressure chamber 82.
It is installed inside the pressure chamber 83. Then, the fuel from the first feed pump 5 reaches the injection pump 7 through the first pressure chamber 82, the injection amount sensor 9, and the second pressure chamber 83. Further, a part of the fuel flows from the first pressure chamber 82 to the piston chamber 41 of the actuator 4 via the nozzle 84 under a pressure (P ₃ ) according to the opening area of the nozzle 84, and then flows through the throttle 10 to the fuel. It is returned to tank 11. The injection amount sensor 9 includes a cylinder 91, a slider 92, and a spring 93, and the opening area of a slit 94 in the cylinder 91 is adjusted by one edge of a groove 95 in the slider 92. Also, a lower chamber 9 in which a spring 93 is installed
6, the suction side pressure (P ₂ ) of the second feed pump 72 is introduced, and the discharge side pressure (P ₄ ) of the second feed pump 72 is introduced into the chamber 97 formed on the upper end side of the slider 92. .

In the above configuration, since the second feed pump 72 is driven by the pump camshaft 71, the pressure difference (P ₄ - P ₂ ) between its front and back is proportional to the pump rotation speed and eventually to the engine rotation speed, as shown in FIG. The slider 92, which receives the pressures (P ₂ , P ₄ ), is displaced in accordance with the engine speed, and the opening area of the slit 94 also changes in accordance with the engine speed. Then, the differential pressure across the slit 94 (P ₁ −
P ₂ ) changes depending on the opening area of the slit 94 and the amount of fuel Q passing through the slit 94 (i.e., fuel consumption amount), but the fuel consumption amount Q is related to the engine speed and engine load, and therefore By controlling the opening area of the slit 94 according to the engine speed, the differential pressure (P ₁ -P ₂ ) becomes proportional to the load as shown in the first quadrant of FIG. 3.
As shown in the second quadrant _of FIG _.
In order to control the opening area of the piston 42, the pressure (P ₃ ) acting on the piston 42 is proportional to the differential pressure (P ₁ −P ₂ ), that is, the load, as shown in the third quadrant of FIG. The EGR control valve 3 can be operated according to the load as shown in the fourth quadrant of FIG. 4, and an EGR rate proportional to the load can be obtained as shown in FIG.
Note that the protrusion 31 provided on the EGR control valve 3 is
This valve was provided to adjust the relationship between the internal combustion engine area of the intake pipe 1 and the passage area of the EGR pipe 2 as the EGR control valve 3 rotates, thereby obtaining linear EGR characteristics as shown in Figure 4. It is something.

As mentioned above, the present invention adjusts the opening degree of the slit provided in the fuel flow path by introducing the discharge pressure of the second feed pump, which changes depending on the rotational speed of the internal combustion engine, into the injection amount sensor. Regardless of the engine speed, when the load is the same, the differential pressure across the slit is made the same, and this differential pressure is used to operate the EGR control valve. Therefore, EGR control can be performed accurately according to the load, and since the mechanism for detecting the load state of the internal combustion engine is a simple structure using hydraulic pressure, it can be installed in a part of the conventional hydraulic circuit to control the internal combustion engine. An excellent effect can be obtained in that it can be easily modified.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram showing an embodiment of the present invention;
FIGS. 2 to 4 are characteristic diagrams for explaining the operation. 1... Intake pipe, 3... EGR control valve, 5... First feed pump, 7... Fuel injection pump, 9...
...Injection amount sensor, 72...Second feed pump,
94... Injection amount sensor slit.

Claims (1)

[Scope of utility model registration request] a first feed pump that delivers fuel at a constant pressure; a fuel injection pump that injects fuel to an internal combustion engine supplied with fuel from the first feed pump;
An internal combustion engine equipped with a second feed pump whose discharge pressure increases approximately in proportion to an increase in the rotational speed of the internal combustion engine, wherein the amount of exhaust gas recirculated to the intake pipe of the internal combustion engine is controlled by an exhaust gas recirculation control valve. In the exhaust gas recirculation device, an injection amount sensor that changes the opening degree of the slit by introducing the discharge pressure of the second feed pump is provided in the fuel circuit that communicates the first feed pump and the fuel injection pump. . An exhaust gas recirculation device for an internal combustion engine, characterized in that the exhaust gas recirculation control valve is configured to operate in relation to the differential pressure across the slit.