JPS595787B2 - Starting aid for multi-cylinder diesel engines - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a starting assist device for a multi-cylinder diesel engine having an EGR device.

Both diesel engines equipped with a starting heater and diesel engines equipped with an EGR device are known.

It is not difficult for the parties concerned to provide both of these. However, if a diesel engine equipped with both a starting heater and an EGR device is normally employed, it would appear as shown in FIG.

That is, the starting heater 3 is provided upstream of the distribution section 2 of the intake manifold 1, and the starting heater 3 is provided upstream of the distribution section 2 of the intake manifold 1, and
An EGR intake port 6 is provided downstream.

According to the above method, the following runners-up occur.

Since the heat generated energy of the starting heater 3 is distributed evenly to all cylinders, the temperature rise of the intake air is low. Therefore, a starting heater with a large heat generating capacity is required, but there is a limit depending on the loaded battery. Deterioration in startability is inevitable. SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a starting assist device for a multi-cylinder diesel engine that improves the above-mentioned drawbacks, improves starting characteristics using a relatively small-capacity starting heater, and improves the intake air heating effect by EGR gas. We aim to provide the following.

This will be explained in detail below with reference to the drawings.

Referring to FIG. 2, a diesel engine 11 has six cylinders in this example, and has an intake manifold 12 and an exhaust manifold 13.

The intake manifold 12 includes a first distribution section 14, a second distribution section 15, and six branch pipes 161 to 161 branched from the distribution section 15.
It has 166. Each branch pipe 161-166 supplies intake air to each cylinder 1T1-1T6. The exhaust manifold 13 has a first collecting part 18, a second collecting part 19, and a first collecting part 18.
It has six branch pipes 201 to 206 branched from the gathering part 18. Each branch pipe 201 to 206 corresponds to each cylinder 1.
Receives exhaust from T1 to 1T6. The present invention heats intake air only in a predetermined cylinder and uses exhaust gas from the predetermined cylinder as EGR gas.

For example, in the case of a 6-cylinder engine, when ignition occurs during cranking, if 2 to 3 cylinders are completely burned, the remaining unignited cylinders will continue to ignite and explode, so as shown in Figure 2, the branch pipe 16
A starting heater 21 (usually an electric heater is often used) is provided immediately upstream of the second distribution part 15 where the parts 1 and 162 diverge. Therefore, only cylinders 171 and 172 are subjected to intake air heating. Furthermore, the EGR passage 22 has an inlet 24 opened in the intake passage 23 on the one hand;
On the other hand, the EGR outlet 25 is located upstream of the second collecting portion 19 of the exhaust manifold 13 and at a position corresponding to the cylinders 171 and 172 where the intake air heating has been performed, that is, the branch pipe 201.
, 202.

The above configuration of the present invention operates as follows.

Intake air flowing through the intake passage 23 flows from the first distribution section 14 to the second distribution section 15, and is sent to each cylinder 171-176 via each branch pipe 161-166.

The intake air branched into branch pipes 161 and 162 is connected to the starting heater 2.
1, the intake air to cylinders 171 and 172 is sufficiently heated to ensure cold startup ignition.The intake air supplied to 0 cylinders 173 to 176 is not heated, so it is heated at the time of startup. Ignition is uncertain, but in a six-cylinder engine, if two or three cylinders are reliably ignited, there is no problem in transitioning from startup to self-rotation.

Furthermore, the cylinders 171 and 172 are definitely ignited, and the temperature of the exhaust gas is high.

Only this high-temperature exhaust gas is taken in from the EGR gas intake port 25 and passed through the EGR passage 22 from the inlet to the intake passage 23.
Inject into. This EGR gas heats the intake air, making cold starting even better. The above is one embodiment of the present invention, and the present invention is not limited to the above embodiment. For example, the number of cylinders for heating the intake air during cold start and the selection of the cylinders are appropriately set to 0. Furthermore, the present invention is not limited to a six-cylinder diesel engine, and can be applied to any multi-cylinder engine.

The effects of the present invention constructed and operated as described above are as follows.

First, cold starting characteristics are improved without using a large-capacity starting heater.

Further, since only the exhaust gas from the cylinder that has been reliably ignited is used as EGR gas, the effect of heating the intake air by the EGR gas is improved, and cooling and contamination of the starting heater by the EGR gas are prevented.

Furthermore, the structure does not have any negative effect on the EGR system.

[Brief explanation of drawings]

Fig. 1 is a layout diagram showing an example of a commonly used starting assist device, and Fig. 2 is a layout diagram showing an embodiment of the present invention. ...exhaust manifold, 14...first distribution section, 161
~166...branch pipe, 171~176...
・Cylinder, 18...First gathering part, 19...
...Second gathering part, 201-206...Branch pipe.
．． 21...Starting heater, 22...E
GR passage, 23...Intake passage, 25...
・EGR gas intake.

Claims (1)

[Claims] 1. In a multi-cylinder diesel engine that has an intake manifold and an exhaust manifold, and is equipped with a starting heater and an EGR device, the starting heater is placed downstream of the first distribution section of the intake manifold so as to heat the intake air only in predetermined cylinders. starting a multi-cylinder diesel engine, characterized in that the EGR gas intake port is opened at a position upstream of the second collecting part of the exhaust manifold and corresponding to the cylinder in which the intake air heating is performed. Auxiliary equipment.