JPH11229884A - Engine supercharging structure and supercharging method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce intake noise of a supercharger while maintaining good response thereof. SOLUTION: This supercharging structure is provided with a natural intake airflow duct 3 through which air is inducted to a supercharger 1, a supercharging airflow duct 5 which communicates the supercharger 1 with an engine and which supercharges the air to the engine, a bypass flow duct 11 which communicates the natural intake airflow duct 3 with the supercharging airflow duct 5, and a downstream throttle valve B, which is installed in the middle of the supercharging airflow duct 5 on the engine side from the communicating position of the supercharging airflow duct 5 and the bypass flow duct 11, and which opens and closes the supercharging airflow duct 5 to adjust the amount of air supplied to the engine. In this case, this supercharging structure has an upstream throttle valve A, which is installed in the middle of the natural intake airflow duct 3 on the air intake side from the communicating position of the natural intake airflow duct 3 and the bypass flow duct 11, which opens and closes the natural intake air flow duct 3 to adjust the amount of air supplied to the supercharger 1 and the bypass flow duct 11. Together with this, the upstream throttle valve A is opened prior to the downstream throttle valve B when intake air is supercharged to the engine.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a mechanical supercharging structure and a supercharging method for an engine.

[0002]

2. Description of the Related Art As a conventional supercharging structure of this type, for example, a structure schematically shown in FIG. 4 is known.

In FIG. 4, a roots type supercharger 101 is mechanically driven from a crankshaft of an engine (not shown). The intake air is sucked into the supercharger 101 through the air cleaner 103 and the natural intake passage 105, and the supercharged air pressurized through the supercharger 101 passes through the supercharge passage 107, the throttle valve 109, and the intake manifold 111. Supplied to the cylinder. A bypass passage 113 is provided for communicating the supercharged passage 107 and the natural intake passage 105, and a bypass valve 115 is provided in the bypass passage 113.

Since supercharging is not required during low-speed, low-load operation of the engine, the bypass valve 115 is opened and intake air is drawn into the cylinder through the bypass passage 113. During high-speed high-load operation of the engine, the bypass valve 115 is closed, and the intake air is supercharged into the cylinder via the supercharger 101. The opening and closing of the bypass valve 115 controls the supercharging pressure of the engine.

[0005]

However, in this supercharging structure, since the suction side of the supercharger 101 is open to the atmosphere, the sound of the intake of the supercharger 101 leaks out, which is annoying. Further, since the suction side of the supercharger 101 is at the atmospheric pressure, there is a problem that a larger supercharger driving force is required than in the case of a negative pressure, and fuel efficiency is deteriorated.

Accordingly, an object of the present invention is to suppress the intake noise of the supercharger while maintaining good responsiveness of the supercharged air.

[0007]

According to a first aspect of the present invention, there is provided a natural air intake passage through which air is sucked into a supercharger, and a communication between the supercharger and an engine. A supercharging passage for supercharging air to the engine, a bypass passage for communicating the natural intake passage and the supercharging passage,
A first opening / closing means which is provided in the middle of the supercharging flow path on the engine side from the communication position between the supercharging flow path and the bypass flow path and opens and closes the supercharging flow path to adjust the amount of air supplied to the engine; A supercharging structure of an engine comprising: a natural intake flow path that is provided in the middle of a natural intake flow path closer to the atmosphere than the communication position between the natural intake flow path and the bypass flow path. A second opening / closing unit that opens and closes to adjust the amount of air to the supercharger and the bypass passage, and that is opened prior to the first opening / closing unit when the intake air to the engine is supercharged. Features.

Therefore, the leakage of the intake noise of the supercharger is suppressed by the flow restricting action of the second opening / closing means provided in the natural intake flow path on the air intake side with respect to the supercharger and the bypass flow path. Is done.

Further, since the second opening / closing means is opened prior to the first opening / closing means at the time of opening, the responsiveness of the supercharged air (supercharging pressure) during rapid acceleration of the engine is good.

According to a second aspect of the present invention, there is provided a naturally-aspirated flow path through which air is sucked into a supercharger, a supercharged flow path through which the supercharger communicates with an engine to supercharge air to the engine, A bypass passage communicating the natural intake passage and the supercharged passage, and a supercharged passage provided in the middle of the supercharged passage on the engine side from a communication position between the supercharged passage and the bypass passage. The first to open and close the air flow path and regulate the amount of air supply to the engine
The opening / closing means of the engine, wherein the natural intake flow path is provided in the natural intake flow path on the air intake side from the communication position between the natural intake flow path and the bypass flow path. The second opening / closing means for opening / closing the road is opened prior to the first opening / closing means when the intake air to the engine is supercharged.

Therefore, the same effect as that of the first aspect can be obtained.

According to a third aspect of the invention, there is provided the method of supercharging an engine according to the second aspect, wherein the opening speed of the second opening / closing means is faster than the opening speed of the first opening / closing means. And the ratio of the opening speeds of the first and second opening / closing means is set to a predetermined constant value according to the degree of opening of the first opening / closing means.

Therefore, the same effect as the invention of claim 2 can be obtained, and the opening speed of the second opening / closing means is faster than that of the first opening / closing means, and the ratio of the opening speeds is the first opening / closing means. Can be set to a constant value (a straight line relationship) in accordance with the opening degree range of, so that it is easy to select the response of the supercharged air at the time of rapid acceleration of the engine.

[0014]

1 and 2 show an embodiment of the present invention.
This will be described below. FIG. 1 schematically shows a supercharging structure according to the present embodiment, and FIG. 2 is an operation explanatory view.

A roots-type mechanical supercharger 1 is used in this supercharging structure, and the supercharger 1 is constantly driven mechanically from a crankshaft of an engine (not shown). An upstream throttle valve (second opening / closing means) A is provided in the natural intake passage 3 on the suction side of the supercharger 1, and a downstream throttle valve ( First opening / closing means)
B is provided.

The intake air is sucked into the supercharger 1 through the air cleaner 7, the upstream throttle valve A, and the natural intake passage 3,
The supercharged air on the discharge side of the supercharger 1 is supplied to the cylinder through the supercharged air flow path 5, the downstream throttle valve B, and the intake manifold 9. Upstream throttle valve A in natural intake passage 3
A bypass passage 11 is provided at an intermediate portion between the turbocharger 1 and the supercharger 1 to communicate the supercharged air passage 5. A bypass valve 13 is provided in the bypass passage 11, and the bypass valve 13 opens and closes the bypass passage 11.

The upstream throttle valve A and the downstream throttle valve B open and close the natural intake passage 3 and the supercharged passage 5, respectively. FIG. 2 shows the ratio of the opening speeds of the two throttle valves A and B. The horizontal axis in FIG. 2 shows the opening of the downstream throttle valve B. The opening range of the opening of the downstream throttle valve B from fully closed to almost half open is a partial load region of the engine, and is substantially from half open to full open. The opening range is the full load range of the engine. The vertical axis in FIG. 2 indicates the opening of the upstream throttle valve A.

A broken line 25 in FIG. 2 indicates a case where the opening speeds of both throttle valves A and B are equal (when the opening speed ratio = 1). In the partial load region of the engine shown in FIG. 2, the opening speed of the upstream throttle valve A is set so that the minimum intake air amount that can maintain a predetermined engine output can be taken in and the responsiveness of the intake air amount during acceleration can be kept good. Is set to speed. As a result, the opening speed of the upstream throttle valve A is set to be higher than that of the downstream throttle valve B, and the ratio of the opening speeds of the throttle valves A and B is set to a predetermined constant value indicated by a straight line 21. ing.

When the downstream throttle valve B is almost half-open, the upstream throttle valve A reaches the full open state, and in the full load region of the engine, the upstream throttle valve A is kept at the full open state. That is, in the full load range of the engine, the ratio of the opening speeds of the two throttle valves A and B is set to 0 indicated by the horizontal line 23. Thereby, the responsiveness of the intake air amount is in the highest state, and a sufficient boost pressure is obtained. Note that FIG.
A hatched portion 27 in the middle indicates a preceding open area of the upstream throttle valve A.

Next, the operation of the supercharging structure, that is, the supercharging method will be described with reference to FIG.

In the idling state of the engine, both the throttle valves A and B are almost in the fully-closed state, the turbocharger 1 stops operating, the bypass valve 13 is opened, and the intake air flows through the bypass passage 11. Pass through and be sucked into the engine.

When the engine is accelerated, both throttle valves A and B are opened. However, since the opening speed of the upstream throttle valve A is faster than the opening speed of the downstream throttle valve B, the ratio indicated by the straight line 21 in FIG. (1 or more), the upstream throttle valve A is opened before the downstream throttle valve B, and is fully opened and held first. Thereafter, the downstream throttle valve B on the horizontal axis is opened from a substantially half-open state to a fully open state.

When the engine is operating steadily in the partial load region, the upstream throttle valve A is opened first, but the upstream throttle valve A throttles the natural intake passage 3 so that the intake air of the turbocharger 1 is reduced. Sound is prevented from leaking out of the air cleaner 7.

In the full load range, the upstream throttle valve A
Is maintained in a fully open state, and the supercharged air is supplied with good responsiveness to the opening degree of the downstream throttle valve B. When the supercharging pressure is excessively increased, the supercharging pressure is appropriately controlled by opening the bypass valve 13 and returning the supercharged air to the suction side of the supercharger 1 through the bypass passage 11.

When supercharging is not required during low-speed, low-load operation of the engine, the driving force of the supercharger 1 is reduced by the negative pressure in the natural intake passage 3 narrowed by the upstream throttle valve A. Fuel efficiency is improved.

As described above, according to this embodiment, the upstream throttle valve A is provided in the natural intake passage 3 closer to the air cleaner 7 than the turbocharger 1 and the bypass passage 11, so that the natural intake by the upstream throttle valve A is performed. Due to the throttle action of the flow path 3, leakage of the intake sound of the supercharger 1 is suppressed.

Since the opening speed of the upstream throttle valve A is set to be faster than that of the downstream throttle valve B, the upstream throttle valve A opens before the downstream throttle valve B when the engine is accelerated. In addition, the response of the supercharging air (supercharging pressure) at the time of engine acceleration is good due to the appropriately selected opening speed ratio.

Further, at the time of low load operation, the driving force of the supercharger 1 is reduced by the negative pressure of the natural intake passage 3 narrowed by the upstream throttle valve A, and the fuel efficiency is improved accordingly.

In the above-described embodiment, the case where the ratio of the opening speeds of the throttle valves A and B is set to change linearly as shown in FIG. 2 has been described. The ratio of the opening speeds of the two throttle valves A and B is electrically controlled so that, for example, as shown in FIG. It is also possible to set. When such opening control is performed mechanically,
For example, it can be set by making the cross-sectional shape of the flow path of the downstream throttle valve B section circular and the cross-sectional shape of the flow path of the upstream throttle valve A section elliptical.

As a result, the degree of freedom in selecting the response of the supercharging when the engine is rapidly accelerated is expanded.

[0031]

As is clear from the above description, according to the first aspect of the present invention, the second opening / closing provided in the natural intake passage on the air intake side with respect to the supercharger and the bypass passage. The leakage of the intake sound of the turbocharger is suppressed by the throttle action of the flow path by the means.

Since the second opening / closing means is opened prior to the first opening / closing means at the time of opening, the responsiveness of the supercharged air (supercharging pressure) during rapid acceleration of the engine is good.

According to the invention described in claim 2, according to claim 1
The same effect as that of the invention is obtained.

According to the invention described in claim 3, according to claim 2
And the opening speed of the second opening / closing means is faster than that of the first opening / closing means, and the ratio of the opening speeds is constant according to the degree of opening of the first opening / closing means. (Relationship of a straight line), it becomes easy to select the response of the supercharged air at the time of rapid acceleration of the engine.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a supercharging structure according to an embodiment of the present invention.

FIG. 2 is an operation explanatory view of one embodiment.

FIG. 3 is a diagram illustrating a modification of the operation of the embodiment.

FIG. 4 is a schematic diagram showing a conventional supercharging structure.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 mechanical supercharger 3 natural intake flow path 5 supercharged flow path 11 bypass flow path 13 bypass valve A upstream throttle valve (second opening / closing means) B downstream throttle valve (first opening / closing means)

Claims (3)

[Claims] A natural intake passage through which air is sucked into a supercharger; a supercharged passage through which the supercharger communicates with an engine to supercharge air to an engine; A bypass passage communicating with the supercharged passage, and a bypass passage provided in the middle of the supercharged passage on the engine side from a communication position between the supercharged passage and the bypass passage to open and close the supercharged passage to the engine. And a first opening / closing means for adjusting an air supply amount of the natural intake passage, wherein a natural intake passage closer to the air intake side than a communication position between the natural intake passage and the bypass passage. Is provided in the middle of
The natural intake passage is opened and closed to adjust the amount of air to the supercharger and the bypass passage, and the second opening is opened prior to the first opening / closing means when the intake air to the engine is supercharged.
An engine supercharging structure characterized by having opening and closing means. 2. A naturally-aspirated flow passage through which air is sucked into a supercharger, a super-charged air passage that communicates the supercharger with an engine and supercharges air to an engine, A bypass passage communicating with the supercharged passage, and a bypass passage provided in the middle of the supercharged passage on the engine side from a communication position between the supercharged passage and the bypass passage to open and close the supercharged passage to the engine. A first opening / closing means for adjusting an amount of air supplied to the engine, comprising: a natural intake passage on an air intake side from a communication position between the natural intake passage and the bypass passage. A second opening / closing means provided in the middle of the first opening / closing means for opening / closing the natural intake passage is opened prior to the first opening / closing means when the intake air to the engine is supercharged. How to pay. 3. The method for supercharging an engine according to claim 2, wherein an opening speed of the second opening / closing means is set to be faster than an opening speed of the first opening / closing means. First
A ratio of the opening speed of the second opening / closing means to a predetermined constant value according to the opening degree of the first opening / closing means.