JPH0118259B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an intake pipe heating device for an internal combustion engine that heats the intake pipe using exhaust heat.

(Prior art) The intake pipe is heated for the purpose of promoting the atomization of the air-fuel mixture within the intake pipe and shortening the warm-up time. There are some that use heat.

In this type of conventional technology, there is a technique in which an intake pipe (intake manifold) and an exhaust pipe (exhaust manifold) are arranged close to each other vertically.
This type of engine can only be applied to so-called reverse-flow type engines, in which the intake pipe and exhaust pipe are located on the same end face of the cylinder head, and is virtually impossible to apply to cross-flow type engines. It was hot.

In this cross-flow type engine, when heating the intake pipe using exhaust heat, it is possible to form an exhaust gas circulation passage for heating the intake pipe separately from the exhaust pipe, but in this case, heating The passage must be disposed across a large member such as a cylinder head, which is extremely disadvantageous in terms of structure and cost. In particular, modern automobile internal combustion engines are equipped with a variety of equipment for purposes such as exhaust gas purification measures, making it increasingly difficult to secure sufficient space in the engine compartment. Therefore, a solution to the above problems is urgently desired.

(Problems to be Solved by the Invention) The present invention has been made with the aim of solving the above-mentioned problems, and involves performing EGR (exhaust gas recirculation) as a measure to purify exhaust gas in modern internal combustion engines. Focusing on the fact that there are many
It is used as an exhaust gas circulation path for heating the intake pipe, and the flow of exhaust gas can be controlled according to the temperature of the engine.

(Means for Solving the Problems) As a means for solving the above problems, the present invention provides an exhaust gas outlet in the exhaust system path and an exhaust gas return port on the downstream side of the exhaust gas outlet. Then, the EGR passage whose one end is connected to the exhaust gas outlet is branched into two, and the EGR valve is connected in the middle of one of the branched passages, which becomes the main passage, and the tip is connected to the intake system passage. The other branched passage that is connected and serves as a bypass passage is arranged so that the exhaust gas flowing therein heats the intake system passage, and its tip is connected to the exhaust gas return port, and the other branch passage serves as a bypass passage. A valve mechanism is provided between the gas outlet and the exhaust gas return port to control the flow rate of the exhaust gas to the bypass path by controlling the pressure difference between them.

(Function) If it is configured like this, it will be divided into two branches.
The main EGR passage controls the amount of exhaust gas recirculated to the intake system by opening and closing the EGR valve, and the bypass passage heats the intake system passage with the exhaust gas flowing inside it, and then releases the exhaust gas. It will be returned to the exhaust gas return port. The flow rate of exhaust gas to the bypass path is controlled by controlling the pressure difference between the exhaust gas outlet and the exhaust gas return port in the exhaust system path.

(Embodiment) Hereinafter, an embodiment of the present invention will be described with reference to the drawings. First, the underlying technology will be explained with reference to FIG. 1. 1 is a cylinder, 2 is a cylinder head, 3 is a piston, 4 is a combustion chamber, 5 is an intake port, 6 is an exhaust port, 7 is an intake pipe, 8 is an exhaust pipe, and 9 is a carburetor. The illustrated engine is a so-called cross-flow type engine in which an intake pipe 7 and an exhaust pipe 8 are located on one side and the other side of the cylinder head 2. One of the features of the present invention is that a valve is provided between an exhaust gas outlet and an exhaust gas return port in the exhaust pipe to control the flow rate of exhaust gas to the bypass path by controlling the pressure difference between them. This point is that a mechanism is provided, but this point will be described later with reference to separate drawings.

The exhaust pipe 8 is provided with an expansion chamber 10, and a throttle portion 11 is formed downstream of the expansion chamber 10. The expansion chamber 10 has an exhaust gas outlet 1.
2 is open, and the expansion chamber 10 has an exhaust gas return port 13.
is open. EGR is installed at the exhaust gas outlet 12.
One end of the passage 14 is connected. This EGR passage 14 straddles the cylinder head 2 and passes near the carburetor 9, and then branches into two. this
One of the two branched paths of the EGR passage 14 serves as the main path 14a of the EGR passage, which is connected to the intake pipe 7 via the EGR valve 15 as in the conventional case. The other branch road is EGR
It serves as a bypass path 14b for the passage, and is connected to the intake pipe 7.
The exhaust gas return port 13 is connected to the exhaust gas return port 13 through a heating chamber 16 formed in the bottom wall of the exhaust gas return port 13 .

The heating chamber 16 heats the intake pipe 7 (particularly the cooling water in the jacket 17 formed in the intake pipe 7) using the heat of the exhaust gas passing through the heating chamber 16. In order to increase the heat transfer surface area, Its upper wall is uneven. In this way, in order to heat the intake pipe 7 with the heat of the exhaust gas, it is also done at the branch part of the intake manifold that serves as the air-fuel mixture distribution part for each cylinder (if the engine has multiple cylinders). This is preferable in terms of supplying a sufficiently exposed air-fuel mixture to the air.

The operation of the structural parts described above will be explained. First, when the engine is started when the engine is cold and the engine temperature is low, the exhaust gas discharged into the exhaust pipe 8 enters the EGR passage 14 from the exhaust gas outlet 12 and heads to the branch part, but when the engine is cold, the EGR Since the valve 15 is closed, this exhaust gas flows through the main path 14.
It does not flow to the a side, but flows through the bypass path 14a to the heating chamber 16 formed in the bottom wall of the intake pipe 7, where the intake pipe 7 is heated. This heating promotes atomization of the air-fuel mixture. The exhaust gas after heating the heating chamber 16 is returned to the exhaust pipe 8 from the exhaust gas return port 13.

This heating of the intake pipe 7 by the exhaust gas promotes atomization from the carburetor 9 when the engine is cold, and also causes the cooling water temperature to rise quickly, thereby shortening the warm-up time. In this case, if there is a pressure difference between the exhaust gas outlet 12 and the exhaust gas return port 13, which is higher on the exhaust gas outlet 12 side, this pressure difference will cause
Exhaust gas easily flows into the bypass path 14b of the EGR passage 14, and if the pressure difference is small, it becomes difficult for the exhaust gas to flow. In the present invention, paying attention to this point, a valve mechanism is provided in this portion, which will be explained later. When the engine reaches a predetermined temperature during warm-up operation, the EGR valve 15 becomes easier to open, so as the EGR valve 15 opens and closes, the main passage 14a
Exhaust gas flows through the engine, and EGR is performed.

FIGS. 2 and 3 show the main parts of the system shown in FIG. 1, with some changes made. In the model shown in FIG. 2, the heating chamber 16 in the pipe wall of the intake pipe 7, which was provided in the model shown in FIG.
The bypass passage 14b of the passage 14 is passed through. On the other hand, in the one shown in FIG. 3, the stop plate 18 made of a high-quality conductive material such as aluminum substantially connects the bottom wall of the intake pipe 7 with the EGR.
The bypass passage 14b of the passage 14 is configured to further enhance the heating effect. Since the stall plate 18 is assembled from below in FIG. 3, the bottom wall of the bypass passage 14b in the EGR passage 14 is substantially constituted by the cover plate 19.

Referring to FIG. 4, a valve mechanism provided in the exhaust pipe 8, which is a major feature of the present invention, will be explained. As described above, the EGR passage 14 and the bypass passage 14b branched from the EGR passage 14 are connected to the exhaust pipe 8 at different positions, and a butterfly valve 20 serving as a valve mechanism is connected to the rotating shaft 20a between them. It is equipped with a rotatable mechanism. One end of a coiled bimetal 21 is fixed to the wall of the exhaust pipe 8, and the other end of the bimetal 21 is fixed to the rotating shaft 20a. This bimetal 2
According to No. 1, the opening degree of the butterfly valve 20 is small when the exhaust gas temperature is low and the engine is cold, and the opening degree becomes large after warm-up when the exhaust gas temperature is high.

FIG. 5 schematically shows the operation of the butterfly valve 20 shown in FIG. 4. To explain the operation at this time, when the engine is cold and the temperature of the exhaust gas is low, the opening degree of the butterfly valve 20 is small due to the bimetal 21, so the throttle action of the bimetal 21 causes the exhaust gas outlet 12 and the exhaust gas return port 13 to A pressure difference will occur between them. That is, since the opening degree of the butterfly valve 20 is small, the pressure inside the exhaust pipe 8 is higher on the exhaust port 6 side, where exhaust gas is continuously discharged, than on the front side of the butterfly valve 20, so that the exhaust gas is After flowing into the exhaust gas intake port 12 and heating the intake pipe 7 through the EGR passage 14 and the bypass passage 14b, the exhaust gas returns to the exhaust gas return port 13.
It is returned to the exhaust pipe 8. Intake pipe 7
The effect of heating is as described above. When the engine warms up, the opening degree of the butterfly valve 20 increases due to the action of the bimetal 21, so the exhaust gas is recirculated to the intake pipe 7 under the control of the EGR valve 15, and the EGR bypass path This means that almost no water flows to 14b.

What is shown in FIG. 6 is another embodiment of the invention. In this embodiment, the butterfly valve 20 in the embodiment shown in FIG. 4 is driven by negative pressure in the intake pipe. That is, one end of the lever 22 is fixed to the rotating shaft 20a of the butterfly valve 20, and the tip of a rod 23b whose base end is fixed to the diaphragm 23a of the diaphragm type drive device 23 is connected to the other end of the lever 22. be. The negative pressure chamber 23c of this diaphragm type drive device 23 is connected to an intake pipe negative pressure generating section via a temperature-sensitive switching valve (BVSV) 24 that operates according to the engine cooling water temperature. In the case of this embodiment, when the engine is cold, the negative pressure chamber 23c is communicated with the intake pipe negative pressure generator, and the opening degree of the butterfly valve 20 is reduced, and after the engine is warmed up, the negative pressure chamber 23c is communicated with the atmosphere. As a result, the opening degree of the butterfly valve 20 increases.

What is shown in FIG. 7 is yet another embodiment of the present invention. In this embodiment, not only the intake pipe 7 is heated when the engine is cold, but also the intake pipe 7 is heated even during low load when the air-fuel mixture is likely to atomize, and the intake pipe 7 is heated only during high load. 7. Heating is not performed. That is, Figures 4 and 6
A negative pressure operated control valve 25 is provided as a valve mechanism at the position of the butterfly valve 20 shown in the figure, and the negative pressure chamber 25a of this control valve 25 is connected to the one-way valve 26 and BVSV connected in parallel with each other.
27 to the intake pipe negative pressure generating section.

In this example, when the engine is cold, BVSV
27 is closed, the control valve 25 which is under negative pressure control by the one-way valve 26 is closed, and the intake pipe is heated by the exhaust gas. Further, after the engine is warmed up, the BVSV 27 is opened, and the control valve 25 is controlled according to the magnitude of the intake pipe negative pressure. That is, when the load is low, the intake pipe negative pressure is large, so the control valve 25 is closed and the intake pipe is heated, and when the load is high, the control valve 25 is closed.
opens and stops heating the intake pipe.

(Effects of the Invention) With the configuration described above, the present invention uses exhaust heat to heat the intake pipe in a cross-flow internal combustion engine, and the EGR passage can be used as a passage to guide exhaust gas to the intake pipe. Since I used it,
A new passage (bypass passage) connecting the intake pipe to the exhaust pipe is used as an exhaust gas circulation passage for heating the intake pipe.
This means that it is only necessary to provide the following parts, and it becomes possible to make the configuration around the engine more compact. Since the valve mechanism installed in the exhaust system controls the pressure difference in the exhaust system to control the flow rate of exhaust gas, the opening and closing of this valve mechanism is controlled by the valve mechanism in the exhaust system. By controlling the engine according to temperature, intake pipe negative pressure, etc., it is possible to perform EGR in an appropriate state even if the engine has EGR.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional system diagram showing an embodiment of the present invention excluding only the valve mechanism installed in the exhaust pipe, and Figs. 2 and 3 are main part sectional views showing the part that heats the intake pipe with exhaust heat. , FIG. 4 is a cross-sectional view of the main part showing the valve mechanism part of the present invention, FIG. 5 is an operating characteristic diagram of the valve mechanism part of the present invention, and FIGS. 6 and 7 are bookmarks showing modifications of the valve mechanism part. FIG. 7 is a sectional system diagram of main parts of another embodiment of the invention. 1... Cylinder, 7... Intake pipe, 8... Exhaust pipe, 12... Exhaust gas outlet, 13... Exhaust gas return port, 14... EGR passage, 14a... Main path,
14b... Bypass path, 15... EGR valve,
20... Butterfly valve, 25... Control valve.

Claims (1)

[Claims] 1. An exhaust gas outlet was opened in the exhaust system path, and an exhaust gas return port was opened downstream of the exhaust gas outlet, and one end was connected to the exhaust gas outlet.
The middle part of the EGR passage is branched into two, and the EGR valve is connected in the middle of one branch passage, which becomes the main passage, and the tip is connected to the intake system passage, and the other branch passage becomes the bypass passage. The intake system path is arranged so as to be heated by the exhaust gas flowing therein, and its tip is connected to the exhaust gas return port, and between the exhaust gas outlet and the exhaust gas return port of the exhaust system path,
An intake pipe heating device for an internal combustion engine, comprising a valve mechanism that controls the flow rate of exhaust gas to the bypass path by controlling the pressure difference between them.