JPS6231661Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to the structure of a hot air shroud that covers an exhaust manifold of an internal combustion engine for an automobile.

In internal combustion engines for automobiles, a hot air shroud is installed around the exhaust manifold to improve the vaporization of the air-fuel mixture, and air (hot air) warmed by exhaust gas is pumped through the exhaust manifold wall. Warm-up control is performed by drawing air into the intake system, such as an air cleaner. The role of hot air is especially important during cold starting, and if the hot air does not rise to a sufficient temperature, the moisture in the atmosphere sucked into the carburetor will be rapidly cooled by the heat of vaporization of gasoline in the carburetor, and the throttle valve will be heated. There is a risk that ice may form on the air, causing problems such as the air flow rate becoming too low or the mixing ratio becoming too high, resulting in over-contamination.

The structure of a conventional hot air shroud was such that it uniformly covered all ports of the exhaust manifold, and also sucked air from the entire area around the exhaust manifold. In such a structure, the air warmed by the exhaust manifold wall is dammed up on the port side of the exhaust manifold where the heat control valve is installed and is heated quickly, so the heat control valve is heated quickly. The air sucked in from around the port side where the There was a problem that it took time for the temperature of the hot air to rise.

The purpose of the present invention is to speed up the temperature rise time of hot air and improve startability in cold conditions.

In order to achieve this purpose, in the hot air shroud of the present invention, an exhaust manifold heat control valve is provided in the hot air shroud to reduce the space between the hot air shroud and the exhaust manifold. A partition plate is provided to separate the space around the side port from the other space, and hot air is taken out from the space around the heat control valve side port. Additionally, the gap between the hot air shroud and the exhaust manifold has been made smaller than before. With this structure, hot air that is warmed by the outer wall of the exhaust manifold's heat control valve side port is mainly sent to the intake system, but when the air is cold, the opening of the heat control valve becomes smaller and air is sent to the heat control valve side. The residence time of the exhaust gas flowing through the port increases, and the flow inside the port is blocked by the heat control valve and becomes turbulent, improving the heat exchange rate between the exhaust gas and the air around the port through the port wall. As a result, the air around the port is warmed in a short period of time, allowing smooth starting even in cold conditions and achieving the desired purpose.

Preferred embodiments of the hot air shroud of the present invention will be described below with reference to the drawings.

Figures 1 to 5 show a case where a hot air shroud according to an embodiment of the present invention is applied to a four-cylinder engine, and Figure 1 shows the disassembled state before installation, and Figures 2 to 5 show the case where the hot air shroud is applied to a four-cylinder engine. indicates the state after installation. As shown in FIG. 1, the hot air shroud 1 is of a two-piece type, consisting of a first hot air shroud 2 and a second hot air shroud 3, and is formed by press forming a thin plate.
The first hot air shroud 2 is located above the exhaust manifold 4, that is, on the intake manifold 5 installation side of the exhaust manifold 4, and is arranged between the exhaust manifold 4 and the intake manifold 5 so as to cover the exhaust manifold 4 with a gap between them. It is clamped and installed. The second hot air shroud 3 is installed below the exhaust manifold 4, that is, on the exhaust gas discharge side of the exhaust manifold 4 and on the side where the catalytic converter 6 is installed, so as to cover the exhaust manifold 4 with a gap. is,
It is supported at its edges by the first hot air shroud 2.

The second hot air shroud 3 is connected to the exhaust manifold 4 as shown in FIGS. 2 and 3.
Port 8 on the heat control valve 7 installation side
(Ports #3 and #4 in this embodiment). The shaded area in FIG. 2 indicates the mounting plane of the second hot air shroud 3.

The first hot air shroud 2 includes the upper surface of the exhaust manifold 4, the #3 and #4 ports 8,
#1, #2 port 9 curved passage outer surface, #3,
#4 port 8, #1, #2 port 9 gathering part 10
It is formed in a shape that covers the engine and the outer surface on the opposite side with a gap between them. The part that covers the top surface of the exhaust manifold 4 has a tongue-like piece that protrudes toward the engine body (not shown) along the top surface of the #1, #2 ports 9, #3, and #4 ports 8. Projections 11 and 12 are extended. At the upper center of the first hot air shroud 2, there is a tightening seat 14 that corresponds to the intake manifold 5 mounting seat 13 of the exhaust manifold 4, and a tightening seat 14 that corresponds to the bottom heating opening 15 of the intake manifold 5 of the exhaust manifold 4. An opening 16 is formed. The front and back surfaces of the tightening seat 14 are coated with a gasket agent to seal the tightening portion between the exhaust manifold 4 and the intake manifold 5. On the #3 and #4 port sides of the first hot air shroud 2, there is a space formed by the first hot air shroud 2, the second hot air shroud 3, and the outer wall surface of the exhaust manifold 4. A cylindrical hot air outlet 17 for taking out hot air is provided, and although not shown, the hot air outlet 17 is connected to an intake system, such as an air cleaner, etc., by a pipe. The opening 18 is for the first hot air shroud 2 mounting bolt 19 provided on the exhaust manifold 4, and the opening 20 is for an oxygen sensor (not shown) mounted on the exhaust manifold 4.

The second hot air shroud 3 is #3, #4
The port 8 is formed in a shape that covers the bottom surface of the port 8 at intervals, and the edges thereof are caulked together with the bottom edge of the corresponding first hot air shroud 2, thereby closing the first hot air shroud 2. Fixed. At the end of the riser part 10 of the exhaust manifold 4 of the second hot air shroud 3,
#3, #4 so as to surround the curved passage part of port 8,
A substantially triangular partition plate 21 facing upward, that is, towards the intake manifold 5 side, is formed by bending a plate forming the second hot air shroud. The edge of the partition plate 21 is formed in a shape that follows the inner surface of the first hot air shroud 2, and this partition plate 21 allows the separation between the first hot air shroud 2 and the second hot air shroud 3. The space formed by the outer wall surface of the exhaust manifold 4 and the space formed by the other portion of the first hot air shroud 2 and the outer wall surface of the exhaust manifold 4 are separated from each other. It's getting old. An appropriate number of ribs 22 are formed on the bottom surface of the second hot air shroud 3 and the partition plate 21 to increase rigidity.

The space formed by the first hot air shroud 2, the second hot air shroud 3, the outer wall surface of the exhaust manifold 4, and the partition plate 21 is
As shown in Figures 1 and 5, the gap D between the hot air shroud 1 and the exhaust manifold 4 is 3mm±1.5, except for the area near the slope where the hot air outlet 17 is provided. Appropriate dimensions are set within the mm range.

In the hot air shroud of the present invention having the above configuration, the first hot air shroud 2, the second hot air shroud 3, and the partition plate 21 connect the exhaust manifold 4 to #3,
A thin space is formed around the #4 port 8, that is, the port 8 on the side of the heat control valve 7, and hot air is sucked out from this space through the hot air outlet 17. Hot air warmed by the outer wall of port 8 is sent. heat control valve 7
The valve operates so that it is in position A in Figure 3 during a cold start, and in position B after warming up, and the exhaust gas flowing through #3 and #4 ports 8 is transferred to the heat control valve during a cold start. 7 and is discharged to the catalytic converter 6 while bypassing the upper side of the heat control valve 7 , that is, the bottom side of the intake manifold 5 . Therefore, #3,
Exhaust gas flowing in #4 port 8 is #1, #2
The residence time in the port becomes longer than that on the port 9 side, and the flow in the port is dammed by the heat control valve 7, resulting in turbulence and a complicated flow. Therefore, the heat transfer efficiency from the exhaust gas inside the port to the #3, #4 port 8 wall increases, and the amount of heat transfer increases, so the #3, #4 port 8
The temperature of the wall rises faster than the #1 and #2 port 9 walls, and the temperature becomes high. As a result, the air around the outer wall surfaces of #3 and #4 ports 8 is heated to a higher temperature in a shorter time than other parts. Since the space around the outer wall of #3 and #4 ports 8 is separated from the space in other parts, the hot air heated in a short time by the outer wall of #3 and #4 ports 8 will be absorbed by the other parts. It is efficiently sent to the intake system while maintaining a sufficient temperature without being mixed with air whose temperature has not risen and being lowered in temperature. Since the hot air sent to the intake system reaches a sufficient temperature in a short period of time, good fuel vaporization is achieved even during a cold start, resulting in a smooth start.

In addition, the gap between the hot air shroud 1 and the exhaust manifold 4 in the partitioned space is 3.
Since it is set to a small value of mm±1.5 mm, only the hot air near the 4th wall of the exhaust manifold whose temperature rises quickly can be efficiently taken out, and the flow velocity of the hot air flowing through the gap is increased to increase the flow rate between the 4th wall of the exhaust manifold and the hot air. The heat exchange rate of the air is improved and the heating time of the hot air is accelerated. Further, by making the gap small, it is possible to prevent a large amount of cold air from flowing in, which would be an obstacle to the rapid temperature rise of hot air. Therefore, by making the gap smaller, the temperature increase of the hot air is further promoted.

By reducing the gap between the hot air shroud 1 and the exhaust manifold 4 and increasing the flow velocity of the hot air flowing through the gap, the wind pressure load applied to the hot air shroud 1 increases. The second hot air shroud 3 is provided with suitable ribs 22 to increase the rigidity of the plate and prevent vibrations.

The first hot air shroud 2 not only forms a space with the second hot air shroud 3, but also shields heat from the exhaust manifold 4 to the carburetor provided above the intake manifold 5 during normal operation. Needless to say, it fulfills its purpose.

As described above, when using the hot air shroud of the present invention, the space around the port on the side where the heat control valve is installed, which heats up faster than other parts of the exhaust manifold, is separated from other spaces. Since hot air is taken out from the intake system, the air around the port on the side where the heat control valve is installed, where the temperature rises in a short time, can be efficiently taken out as hot air, and hot air at the appropriate temperature can be delivered to the intake system in a short time even when it is cold. Since it is possible to supply a large amount of fuel to the engine, it is possible to perform a quick and smooth start-up when the engine is cold.

Furthermore, by appropriately reducing the gap between the hot air shroud and the exhaust manifold, smooth starting performance in cold conditions can be further facilitated.

[Brief explanation of the drawing]

Fig. 1 is a perspective view showing a state before installation of a hot air shroud according to an embodiment of the present invention, Fig. 2 is a plan view of the device shown in Fig. 1 after installation, and Fig. 3 is a view of the device shown in Fig. 2. The front view of the device, Figure 4 is the same as the device shown in Figure 2.
A sectional view taken along the line, FIG. 5 shows the device shown in FIG.
It is a cross-sectional view along the line. 1...Hot air shroud, 2...First hot air shroud, 3...Second hot air shroud, 4...Exhaust manifold, 5...
Intake manifold, 6...catalytic converter,
7... Heat control valve, 8... #3 and #4 ports as ports on the heat control valve installation side, 9... #1, #2 ports, 1
0...Aggregation part, 11, 12...Protrusion part, 17...
Hot air outlet, 21...partition plate, 22...rib.

Claims (1)

[Scope of Claim for Utility Model Registration] (1) A hot air shroud that covers the exhaust manifold of an internal combustion engine with a gap between the first hot air shroud that covers the intake manifold installation side of the exhaust manifold and the exhaust manifold. a second hot air shroud that covers the exhaust gas discharge side and the port side on the heat control valve installation side, and the second hot air shroud is formed by the hot air shroud and the exhaust manifold. A partition plate is installed to divide the space into the space around the heat control valve side port and other spaces.
A hot air shroud characterized in that a hot air outlet is provided in a portion of the first hot air shroud that defines a space around the heat control valve side port. (2) A request for utility model registration in which the gap between the first and second hot air shrouds defining the space around the heat control valve side port and the exhaust manifold is within the range of 3 mm ± 1.5 mm. A hot air shroud according to item 1. (3) The hot air shroud according to claim 1, wherein ribs are formed on the second hot air shroud.