JPH0450428Y2 - - Google Patents

Description

[Detailed description of the invention] [Field of industrial application] The present invention is an internal combustion engine with a mechanical supercharger that uses a mechanical supercharger that is constantly driven by the internal combustion engine to supercharge the internal combustion engine. It is about institutions.

[Conventional technology and its problems]

Supercharging an internal combustion engine using a positive displacement supercharger that is constantly driven by the internal combustion engine is disclosed in, for example, Japanese Patent Application Laid-Open No. 105626/1983 as a prior art.
It is well known as described in the publication No.

However, when a positive displacement supercharger is used as a mechanical supercharger, air compression by the supercharger is intermittent, which causes pulsations in the intake system downstream of the supercharger. The noise becomes louder,
In particular, when a throttle valve is provided downstream of the supercharger to improve acceleration response in an internal combustion engine, it becomes extremely difficult to adjust air by the throttle valve due to intake pulsation, and the internal combustion engine There is also a problem in that the distribution of air to each cylinder of the engine is uneven due to intake pulsation.

Therefore, for example, as described in Japanese Patent Application Laid-Open No. 59-147820, it is considered to provide a surge tank downstream of the positive displacement supercharger and reduce the pulsation using the surge tank. However, the pulsation in a positive displacement turbocharger is much larger than that in a centrifugal turbocharger, and to reduce pulsation with a surge tank alone, the volume of the surge tank must be increased, so In addition to significantly increasing the overall size of the surge tank, the rigidity of the wall plates constituting the surge tank decreases, causing membrane vibration of the wall plates, which actually increases noise generation.

The present invention aims to reliably reduce pulsation in a positive displacement supercharger without increasing the size of the surge tank or increasing the flow resistance of supercharging air.

[Means for solving problems]

In order to achieve this objective, the present invention provides a positive displacement supercharger that is constantly driven by the internal combustion engine in the intake system from the air cleaner to the internal combustion engine, and a In an internal combustion engine with a mechanical supercharger, the internal combustion engine is provided with a carburetor with a throttle valve, and further includes a surge tank between the supercharger and the carburetor in the intake system. A rectifying element is provided in a portion of the discharge passage leading to the tank where the discharge passage opens into the surge tank, so that an outlet surface of the rectification element is exposed inside the surge tank.

[Functions and effects of the idea]

In this way, if a rectifying element is provided in the discharge passage leading from the turbocharger to the surge tank, the supercharged air compressed by the turbocharger passes through the rectifying element in the discharge passage leading from the turbocharger to the surge tank. After that,
When the air is taken into the internal combustion engine through the surge tank and passes through the rectifying element, it is rectified from a turbulent flow state to a laminar flow state, and fine eddies are eliminated.

On the other hand, by configuring the rectifying element so that the outlet surface of the rectifying element is exposed in the surge tank, the supercharged air passes through the rectifying element and immediately flows into the surge tank having a wide cross-sectional area. , the air is opened all at once to cause a large adiabatic expansion, so the resistance when the supercharged air passes through this rectifying element is greater than if the rectifying element was installed in the middle of the discharge passage to the surge tank. As a result, the pulsations in the supercharged air can be reliably attenuated by the synergistic action of the rectifying element and the surge tank without increasing the flow resistance of the supercharged air. .

Therefore, according to the present invention, since there is no need to increase the size of the surge tank, the entire internal combustion engine can be made smaller and lighter, and an increase in noise due to an increase in the size of the surge tank can be avoided.

〔Example〕

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings, reference numeral 1 indicates a multi-cylinder internal combustion engine having an intake manifold 2 provided with a carburetor 3 with a throttle valve 4, and reference numeral 5 indicates a roots type, a movable vane type, etc. , a screw type or a reciprocating type, and the displacement type supercharger 5 has a mechanism in which the rotation of the internal combustion engine 1 is doubled by a belt-type electric mechanism 6 or the like. It is constantly communicated. In this case, the discharge capacity of the positive displacement supercharger 5 is set so that the engine can be supercharged over the entire operating range of the engine.

In the figure, reference numeral 7 indicates a surge tank connected to the carburetor 3, and reference numeral 8 indicates an air cleaner, and an intake passage 9 extending from the clean side of the air cleaner 8 is connected to the suction side of the positive displacement supercharger 5. On the other hand, connecting the surge tank 7 and the air cleaner 8 via a leak passage 10,
A control valve 11 is provided in the leak passage 10, and the control valve 11 is connected to the throttle valve 4 of the carburetor 3 so that when the throttle valve 4 is closed, the control valve 11 is fully open and the throttle valve 4 is The interlocking mechanism 12 is configured so that the regulating valve 11 is fully opened when the valve is opened to the desired opening degree.
Configure it to work together via .

A discharge passage 1 from the positive displacement supercharger 5
3 to the surge tank 7, and the portion of the discharge passage 13 where the discharge passage 13 opens into the surge tank 7 is made of metal, synthetic resin, or ceramic, for example, as shown in FIG. A small hole 14 is formed in a cylindrical body 14a made of an appropriate material such as
A rectifying element 14 formed by forming a countless number of b in the axial direction.
is inserted into the surge tank 7 so that the outlet surface of the rectifying element 14 is exposed inside the surge tank 7.

Note that this rectifying element 14 is not limited to the one shown in FIG. 2, but may be honeycomb-shaped or foam-shaped. Further, the surge tank 7 is provided with a safety valve 15 that prevents the pressure from increasing by releasing supercharged air when the pressure inside the surge tank 7 increases above a certain value. There is.

In this configuration, when the throttle valve 4 in the carburetor 3 is closed or at a low opening, the supercharged air from the supercharger 5 is passed from the surge tank 7 to the carburetor 3 and the intake manifold 2 to each cylinder in the internal combustion engine 1. At the same time, since the regulating valve 11 in the leak passage 10 is fully open, the supercharger 5
Excess of the supercharged air from the supercharger 5 is returned to the air cleaner 8 or the like upstream of the supercharger 5 through the leak passage 10.

When the opening degree of the throttle valve 4 in the carburetor 3 increases, the other intake passage 1
By fully closing the regulating valve 11 in the internal combustion engine 1, all of the supercharged air from the supercharger 5 is taken into each cylinder in the internal combustion engine 1 from the surge tank 7 via the carburetor 3 and the intake manifold 2. .

When the supercharged air from the supercharger 5 passes through the rectifying element 14 in the discharge passage 13, it is rectified from a turbulent flow state to a laminar flow state, and after fine vortices are eliminated, the supercharged air immediately spreads over a wide cross-sectional area. Since the supercharged air is released into the surge tank 7, the pulsation of the supercharged air increases the flow resistance of this supercharged air due to the synergistic effect of the rectifying element 14 and the surge tank 7. Instead, it is rapidly attenuated.

In order to confirm the effect of this pulsation damping, the present inventor used a three-cylinder internal combustion engine with a displacement of 550 c.c. as the internal combustion engine 1 in the above embodiment, and set the internal volume of the surge tank 7 to 1500 c.c. In this case, the sound pressure level for each rotation speed of the internal combustion engine is determined by comparing the sound pressure level for each rotation speed of the internal combustion engine with the case where the rectifying element 14 is not used in the discharge passage 13, and the case where the rectifying element 14 with a length of 50 mm is used in the surge tank 7 of the discharge passage 13. The results of the measurements were as shown in FIG.

That is, the sound pressure level in the case where the rectifying element 14 is not provided in the discharge passage 13 is the dotted line curve A, whereas the sound pressure level in the case where the rectifying element 14 is not provided in the discharge passage 13 is the same as that in the case where the rectifying element 14 is not provided in the discharge passage 13. When the rectifying element 14 is provided, the sound pressure level becomes as shown by a solid curve B, and the rectifying element 1 is provided in the discharge passage 13.
4, it was possible to considerably reduce the sound pressure level and thus the intake pulsation.

In addition, the length of the discharge passage 13 is 50 mm.
Even when using a rectifying element 14, if this rectifying element 14 is provided in the middle of the discharge passage 13, the effect of reducing intake pulsation will be reduced if the rectifying element 14 is installed in the discharge passage 13. surge tank 7
The flow resistance of the supercharging air was significantly lower than that when the supercharging air was provided at the opening, and the flow resistance of the supercharging air was considerably increased.

In addition, although the above embodiment was a case where the carburetor 3 was used to supply fuel, the present invention is applicable not only to the case where the carburetor 3 is used but also to the case of a fuel injection type internal combustion engine. be.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an embodiment of the present invention, FIG. 2 is a perspective view of a rectifying element, and FIG. 3 is a diagram showing the relationship between rotation speed and sound pressure level. 1...Internal combustion engine, 2...Intake manifold, 3
... Carburetor, 4 ... Throttle valve, 5 ... Supercharger, 7 ... Surge tank, 8 ... Air cleaner,
9... Intake passage, 13... Discharge passage, 14... Rectifying element.

Claims (1)

[Scope of utility model registration request] A positive displacement supercharger that is constantly driven by the internal combustion engine is provided in the intake system from the air cleaner to the internal combustion engine, and a carburetor with a throttle valve is provided downstream of the supercharger, and further, In an internal combustion engine with a mechanical supercharger, in which a surge tank is provided between the supercharger and the carburetor in the intake system, the discharge passage from the turbocharger to the surge tank. 1. An internal combustion engine with a mechanical supercharger, characterized in that a rectifying element is provided at a portion of the rectifying element that opens into the surge tank so that an outlet surface of the rectifying element is exposed into the surge tank.