JPH0326263Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an internal combustion engine equipped with a supercharger such as an exhaust turbo supercharger.

[Conventional technology]

Internal combustion engines with a supercharger are equipped with an intercooler for cooling supercharged air and a surge tank for eliminating pulsation in the supercharging passage from the supercharger such as an exhaust turbo supercharger to the carburetor. Utility development as a technology in 1987-
It is described in Publication No. 17224.

In this way, the meaning of providing a surge tank for eliminating intake pulsation in the supercharging passage from the supercharger to the carburetor in a supercharged internal combustion engine is that the combustion supply amount in the carburetor fluctuates due to the intake pulsation. In addition, the purpose of providing an intercooler to cool the supercharged air in the intake passage from the supercharger to the intake manifold is to reduce the amount of air intake into the engine. This is to avoid reducing the effectiveness of supercharging due to a decrease in the filling efficiency of air to the engine due to the temperature rising due to compression in the supercharger. The supercharged air is passed through the intercooler even in the low engine load range, regardless of the engine load.

[Problem that the invention attempts to solve]

However, passing the supercharged air from the supercharger through the intercooler even in the low load range of the engine means that the supercharger, such as the exhaust turbo supercharger, will not operate sufficiently in the low load range of the engine. Therefore, since the temperature rise of the intake air due to the operation of the supercharger is low and the amount of intake air is small, the cooling of the intake air in the intercooler becomes excessive and the vaporization of the fuel supplied from the carburetor is reduced. Especially when the engine temperature or ambient air temperature is low, icing would occur in the carburetor.

In this way, when an intercooler and a surge tank are installed in the supercharging passage from the supercharger to the intake manifold, the present invention allows supercharged air to flow without passing through the intercooler in the low engine load range. By allowing the fuel to flow directly into the surge tank, the above-mentioned problems can be solved, and the filling efficiency in a high load range can be improved and the surge tank can be made smaller.

[Means for solving problems]

For this reason, the present invention provides an air-cooled intercooler for cooling supercharged air and a surge tank for eliminating pulsation in the supercharging passage from the supercharger to the carburetor, so that the intercooler is located upstream of the surge tank. In a supercharged internal combustion engine, a bypass passage for the intercooler is branched and connected to the supercharging passage upstream of the intercooler, and the bypass passage is connected to the surge tank; A supercharging switching valve is provided at a branch connection of the bypass passage to the supercharging passage, and the supercharging switching valve is arranged to allow supercharging air to pass through the bypass passage when the engine load is low. The inner diameter of the supercharging passage to the tank is larger than the inner diameter of the supercharging passage to the intercooler, and the inner diameter of the bypass passage is smaller than the inner diameter of the supercharging passage to the intercooler. It is.

[Functions and effects of the idea]

With this configuration, the supercharged air from the supercharger is cooled through the intercooler during high and low engine load ranges, enters the surge tank, and is then introduced into the combustion chamber of each cylinder via the carburetor. However, in the low load range of the engine, the supercharging is switched by the supercharging switching valve so that the charge goes directly from the bypass passage to the surge tank without passing through the intercooler. Supercooling caused by the supply air passing through the intercooler can be avoided.

The volume of the surge tank for eliminating intake pulsation is proportional to the amount of intake air to the engine, so the surge tank must be able to eliminate intake pulsation in high load ranges where there is a large amount of intake air to the engine. However, as mentioned above, in high engine load ranges, the supercharged air is guided to the surge tank via a long path passing through the intercooler, and in low engine load ranges, the supercharged air is routed through the bypass passage without passing through the intercooler. By short-circuiting to the tank and directing it, the intake pulsation in the high load range of the engine will be reduced.
It will be erased to some extent in the intercooler and then in the surge tank,
In other words, it will be eliminated by both the intercooler and the surge tank.

In this case, supercharging air in the high engine load range is guided to the surge tank via a long path passing through the intercooler, but the inner diameter of the supercharging passage from the intercooler to the surge tank is the same as that of the supercharging passage to the intercooler. By making the diameter larger than the inner diameter, it is possible to reduce the flow resistance of the supercharging air in the high load range, so it is possible to improve the charging efficiency in the high load range of the engine.

On the other hand, by forming the inner diameter of the bypass passage through which supercharged air flows in the low load region of the engine to be smaller than the inner diameter of the supercharging passage to the intercooler, the supercharged air is throttled when passing through this small diameter bypass passage. As a result of this action, the intake pulsation in the supercharged air is reduced and then the intake pulsation is eliminated again in the surge tank. In other words, the intake pulsation in the low load range of the engine is eliminated by both the throttle action in the bypass passage and the surge tank.

Therefore, according to the present invention, in a supercharged internal combustion engine in which an intercooler and a surge tank for supercharged air are provided in the supercharging passage, supercooling of the supercharged air by the intercooler is achieved in the low load range of the engine. Although it is possible to prevent problems such as decreased fuel vaporization and the occurrence of icing caused by the engine, it is also possible to increase the engine output by improving the charging efficiency in the high load range of the engine, while reducing intake pulsation in the high load range. The ability to eliminate this by both the intercooler and the surge tank and the ability to eliminate intake pulsation in the low load range by both the bypass passage and the surge tank combine to have the effect of making the surge tank more compact.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. In the drawing, reference numeral 1 indicates an internal combustion engine comprising a cylinder head 3 fastened to the top surface of a cylinder block 2, and a cylinder head cover 4 fastened to the top surface of the cylinder head 3. A carburetor 6 is attached to an intake manifold 5 attached to one side of the cylinder head 3, and a surge tank 7 for eliminating pulsation is connected to the upper surface of the carburetor 6. Exhaust manifold 8 attached to the other side
An exhaust turbo supercharger 9 is installed in which an exhaust turbine 9a and a blower compressor 9b are directly connected.

In this case, although the internal combustion engine 1 is not shown, the exhaust turbo supercharger 9 is located at the front and the carburetor 6 is located at the rear in the front engine room of the vehicle with respect to the forward direction of the vehicle. It is installed horizontally.

The upper part of the cylinder head cover 4 has an inlet header 10a at one end and an outlet header 10 at the other end.
b, and an air-cooled intercooler 10 is provided in which the inlet header 10a and the outlet header 10b are connected by a plurality of flat cooling pipes with fins. The inlet header 10a of this intercooler 10 has an inlet pipe 11 for supercharging air.
The supercharging air inlet pipe 11 is connected to the supercharging passage 13 from the blower compressor 9b of the exhaust turbo supercharger 9, and the bypass outlet pipe 12 is connected to the bypass passage 14. is connected to the bypass inlet pipe 15 in the surge tank 7 via a supercharging air outlet pipe 16 in the outlet header 10b, while connecting a supercharging air outlet pipe 16 in the outlet header 10b to a supercharging inlet pipe 18 in the surge tank 7 via a supercharging line 17. .

In this case, the inner diameter D2 of the supercharging air outlet pipe 16 and the supercharging inlet pipe 18 is configured to be larger than the inner diameter D1 of the supercharging air inlet pipe 11, while the bypass outlet pipe 12 and the bypass inlet pipe 15 The inner diameter D3 is the inner diameter D1 of the supercharged air inlet pipe 11.
Configured with a smaller diameter. That is, D2>D1>D3
Configure.

Further, the supercharged air flowing in from the supercharged air inlet pipe 11 is passed through each finned flat cooling pipe in the intercooler 10 into the inlet header 10a of the intercooler 10, and is then sent to the outlet header 10a.
A supercharging switching valve 19 is provided for selectively switching the supercharging air flowing in from the supercharging air inlet pipe 11 to the bypass outlet pipe 12 without passing through the intercooler 11. ing.

This supercharging switching valve 19 is operated by a diaphragm type pressure operating mechanism 20, and this pressure operating mechanism 20 has a biasing function that biases the supercharging switching valve 19 in a direction to close the bypass outlet pipe 12. The throttle valve 23 is provided with a spring 21 configured as shown in FIG. When the intake pressure on the downstream side is a large negative pressure on the vacuum side, this negative pressure causes the supercharging switching valve 19 to switch to the bypass outlet pipe 1.
2 so that the supercharged air flowing in from the supercharged air inlet pipe 11 is guided from the bypass outlet pipe 12 to the surge tank 7 without passing through the intercooler 10. When the side intake pressure rises to approach atmospheric pressure, the supercharging switching valve 19 operates to close the bypass outlet pipe 12 with the spring 21, and the supercharging air inlet pipe 1
The supercharged air flowing in from 1 is made to pass into the intercooler 10.

The pressure transmission passage 25 is connected to the temperature of the engine, the temperature inside the engine room, or the temperature of atmospheric air when these temperatures are high. A temperature switching valve 27 is provided which operates to cut off communication of the pressure transmission passage 25 and to communicate the pressure chamber 22 with the atmospheric passage 26 when the temperature is low.

Therefore, when the temperature of the engine, the temperature inside the engine room, or the temperature of the atmospheric air is high, in a low load range where the opening degree of the throttle valve 23 in the carburetor 6 is small, the intake pressure downstream of the throttle valve 23 Since a large negative pressure is generated on the vacuum side, the supercharging switching valve 19 operates to open the bypass outlet pipe 12 as shown by the solid line in FIG. The supply air is guided from the supercharged air inlet pipe 11 to the surge tank 7 from the bypass outlet pipe 12 having a small diameter D3 without passing through the intercooler 10.

In a high load range where the opening degree of the throttle valve 23 of the carburetor 6 is large, the intake pressure on the downstream side of the throttle valve 23 increases to approach atmospheric pressure, so that the supercharging switching valve 19 As shown by the two-dot chain line in FIG. 3, the bypass outlet pipe 12 is closed, so that the supercharged air flowing in from the supercharged air inlet pipe 11 passes through each flat cooling pipe in the intercooler 10, and then passes through each flat cooling pipe in the intercooler 10. The supercharged air inlet pipe 11 is led to the surge tank 7 through a supercharged air outlet pipe 16 having a larger diameter D1.

In other words, the supercharged air from the exhaust turbocharger 9 is transferred to the intercooler 1 in the low engine load range.
By directly flowing into the surge tank 7 from the bypass outlet pipe 12 with a small diameter D3 relative to 0, overcooling caused by passing through the intercooler 10 can be prevented in a low load range, and the intake pulsation can be suppressed through the bypass outlet pipe 12 with a small diameter D3. This can be eliminated by both the throttling action of the engine and the surge tank 7, and in the high load range of the engine, it flows into the surge tank 7 through the intercooler 10, reducing supercharging in this high load range. Air intercooler 10
In addition, the intercooler 10 and surge tank 7
Further, by forming the supercharged air outlet pipe 16 and the supercharged inlet pipe 18 to have a large diameter D2, the flow resistance of the supercharged air can be reduced.

Note that by forming the bypass outlet pipe 12 to have a small diameter D3, it is thought that the flow resistance of the supercharging air in the low load region of the engine increases and the acceleration response in the low load region decreases. The supercharged air in the low load range of the engine is supplied to the intercooler 10.
Since the length of the path leading to the surge tank 7 is shortened without passing through the bypass outlet pipe 12 and the resistance is reduced accordingly, it is possible to avoid a decrease in acceleration response caused by forming the bypass outlet pipe 12 to have a small diameter D3. .

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, and FIG. 1 is a plan view of an internal combustion engine with a supercharger, and FIG.
The side view and FIG. 3 are partially cutaway plan views of the intercooler and surge tank. 1...Internal combustion engine, 2...Cylinder block, 3
... Cylinder head, 4 ... Cylinder head cover, 5 ... Intake manifold, 6 ... Carburetor, 7
...Surge tank, 8...Exhaust manifold, 9
...Exhaust turbo supercharger, 11...Supercharged air inlet pipe, 12...Bypass outlet pipe, 13...Supercharging passage, 14...Bypass passage, 16...Supercharging air outlet pipe, 17... Supply pipe line, 19... supercharging switching valve,
20... Pressure operation mechanism, 23... Throttle valve,
25...Pressure transmission passage.

Claims (1)

[Scope of utility model registration request] An air-cooled intercooler for cooling supercharged air and a surge tank for eliminating pulsation are provided in a supercharging passage from a supercharger to a carburetor so that the intercooler is located upstream of the surge tank. In the internal combustion engine with a supercharger, a bypass passage for the intercooler is branched and connected to the supercharging passage upstream of the intercooler, and this bypass passage is connected to the surge tank, and the supercharging passage of the bypass passage is connected to the surge tank. A branch connection to the passage is provided with a supercharging switching valve that allows supercharging air to pass through the bypass passage when the engine load is low in relation to the engine load, while a supercharging passage from the intercooler to the surge tank is provided. An internal combustion engine with a supercharger, characterized in that the inner diameter of the bypass passage is larger than the inner diameter of the supercharging passage leading to the intercooler, and the inner diameter of the bypass passage is smaller than the inner diameter of the supercharging passage leading to the intercooler.