JPS6114612Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to an idling noise reduction device that uses an exhaust gas recirculation device to reduce the idling noise of a diesel engine during idling.

Diesel engines produce a unique idle noise at low speeds and low loads. This is because the temperature around the pre-chamber decreases in low speed and low load areas, unlike in high load areas, so the period until the injected fuel ignites, that is, the ignition delay period, becomes longer, and as a result, the amount of fuel accumulated by the time of ignition increases. This is because the injected fuel burns all at once, increasing the rate of pressure rise within the cylinder and increasing the medium to high frequency noise level accompanying the combustion.
Therefore, to reduce idle knock, increase the temperature of each part around the subchamber and the air temperature at the compression end,
All you have to do is improve the ignition delay. As a specific method, for example, an exhaust gas recirculation device provided in a diesel engine may be used to introduce high-temperature exhaust gas into the intake stroke.

However, in the case of conventional exhaust gas recirculation equipment,
Because the mounting device for the recirculation pipe that recirculates exhaust gas was installed at a considerable distance from the mounting surface of the manifold to the cylinder head, the temperature of the recirculated gas decreased and the air temperature at the compression end could not be raised sufficiently. Therefore, there were problems in that the effect of improving ignition delay was small and the effect of reducing combustion noise at low speeds and low loads was small (see, for example, Japanese Patent Application Laid-Open No. 53-92019).

This idea was devised by focusing on the above-mentioned problem, and a through hole is formed in the port part of the cylinder head where the manifold is attached at a position corresponding to each port, and the intake port and exhaust port are communicated with each other. Attach the plate-shaped exhaust recirculation device body (hereinafter referred to as the EGR body) with an exhaust gas recirculation passage formed as shown in the figure above, and attach the manifold to the
Connected to the cylinder head via the EGR body,
At idle, the control valve installed in the middle of the recirculation passage is opened and the exhaust gas is recirculated to the intake port, thereby increasing the temperature of each part around the subchamber and the air temperature at the compression end, thereby reducing the ignition delay. The aim is to improve this and reduce idle noise at low speeds and low loads.

Embodiments of this invention will be described below based on the drawings. In the figure, 1 is the cylinder block of a diesel engine, 2 is the cylinder head, 3 is the intake pipe, and 4 is the cylinder block of the diesel engine.
is the exhaust pipe, and the intake pipe 3 and exhaust pipe 4 will be described later.
It is connected to the port section of the cylinder head 2 via the EGR main body 5. Then, the intake pipe 3
The inside is divided into an intake passage 3a and a bypass intake passage 3b, and a throttle valve 6 is installed in the main intake passage 3a. This throttle valve 6 is connected via links 7 and 8 to a control lever 1 of a fuel injection pump 9.
Connected to 0. In addition, the above EGR main body 5
As shown in FIG. 2, two plates 5a,
5b are joined, and each plate 5
Through holes 11 and 12 are formed in a and 5b at positions corresponding to the intake port and exhaust port of the cylinder head 2, respectively. Furthermore, each plate 5
As shown in FIG. 3, the joint surfaces of a and 5b have a groove 13 for communicating between the through hole 11 corresponding to the intake port and the through hole 12 corresponding to the exhaust port.
is formed, and an exhaust gas recirculation passage is constructed by joining the plates 5a and 5b.
Further, the EGR main body 5 is equipped with a pressure-operated control valve 14 that opens and closes the exhaust gas recirculation passage in the middle of the exhaust gas recirculation passage, and a negative pressure chamber 14a of the control valve 14 is provided with an engine operating state detection device ( A vacuum pump is communicated via an electromagnetic valve 15 driven by a motor (not shown) (see FIG. 1).

Next, the operation of the above configuration will be explained.

In FIG. 1, during idling operation, the control lever 10 of the fuel injection pump 9 is at the idling position, and the throttle valve 6 is fully closed via the links 7 and 8, thereby blocking the intake passage 3a. Therefore, in the idling state, air is supplied to the engine from the intake passage 3b. In this way, during idling, the intake passage is constricted, so negative pressure develops in the intake passage. On the other hand, during idling, a "1" level signal is supplied to the electromagnetic valve 15 from an operating state detection device (not shown), the electromagnetic valve 15 is switched, and the vacuum pump is pumped into the negative pressure chamber 14a of the control valve 14, which is in communication with the atmosphere. A negative pressure is introduced, and the valve 14b rises to open the exhaust gas recirculation passage. Then, the high-temperature exhaust gas passing through the exhaust port is pulled by the negative pressure on the intake passage side and is recirculated to the intake port through the exhaust gas recirculation passage. Note that the amount of exhaust gas recirculated to each cylinder can be adjusted by changing the diameter of the exhaust gas recirculation passage or by arranging an orifice in the passage. When the engine is not in idle mode, a "0" level signal is sent to the P terminal of the solenoid valve 15, so the control valve 14 blocks the exhaust gas recirculation passage.

Next, FIG. 4 shows another embodiment of the present invention, which differs from the previous embodiment in that exhaust ports 16a, 1
Grooves 13a and 13b for exhaust gas recirculation passages are provided so as to recirculate exhaust gas from 6b as well.

In addition, in the above embodiment, a plate-shaped
Although the EGR main body 5 is configured to be attached to the cylinder head 2, the exhaust gas recirculation system (EGR) can also be configured integrally with the cylinder head 2.

As explained above, this idea is based on a plate-shaped exhaust gas recirculation passageway that communicates the intake port and exhaust port in the port section of the cylinder head.
The EGR main body is installed, and the intake pipe and exhaust pipe are connected through this EGR main body, and a control valve is provided in the middle of the above exhaust recirculation passage, and during idling operation, the above control valve is used to direct exhaust gas to the intake port. Since the structure is configured to allow the air to flow back to the diesel engine, the temperature of each part around the pre-chamber of the diesel engine and the air temperature at the compression end are raised, improving ignition delay and reducing idle noise at low speeds and low loads. be able to. Furthermore, a throttle valve is installed in the intake passage in the intake pipe, and this throttle valve throttles the intake passage during idling to increase intake negative pressure, allowing smooth recirculation of exhaust gas from the exhaust port to the intake port. It will be held in

[Brief explanation of the drawing]

Figure 1 is a schematic front view of a diesel engine equipped with an idle noise reduction device according to the present invention;
The figure is a perspective view showing an example of the EGR main body, Figure 3 is an end view cut along the line A-A in Figure 1, and Figure 4 is
FIG. 3 is a cross-sectional view taken along the line A-A showing another example of the structure of the EGR main body. 1... Diesel engine, 2... Cylinder head, 3... Intake pipe, 3a, 3b... Intake passage, 4
...Exhaust pipe, 5...EGR body, 6...throttle valve,
11, 12...Through hole, 14...Control valve.

Claims (1)

[Scope of utility model registration request] A plate-shaped EGR main body is attached to the ports of the cylinder head, in which through holes are formed corresponding to each port, and an exhaust recirculation passage is formed to communicate between the intake port and the exhaust port. A control valve is installed in the middle of the passageway to open and close the passageway under the control of an operating state detection device.
Idle noise reduction in a diesel engine, characterized in that the intake pipe and the exhaust pipe are connected to the cylinder head through the EGR main body, and the control valve is opened during idling operation to recirculate exhaust gas to the intake port. Device.