JPS5838325A - Suction device for engine with supercharger - Google Patents

Abstract

PURPOSE:To check reverse flow of mixture gas to an auxiliary suction system, and to enable to improve an engine performance through the prevention of a drop in compression pressure, by installing a check valve, which checks a reverse flow from a combustion chamber, to an auxiliary suction system at a downstream of a supercharger. CONSTITUTION:In addition to a main suction system 8, an auxiliary suction system 9 is mounted, and a supercharger 18 is set to the auxiliary suction system 9. A check valve 33, which checks a reverse flow from a combustion chamber 4, is located at the downstream of the supercharger 18. A reverse flow of mixture gas to the combustion chamber 4 at a partial loading time is checked rapidly, and this permits the improvement of an engine performance through the prevention of a drop in a compression pressure. Additionally, this enables the improvement of durability of the supercharger and the simplification of the structure of the auxiliary suction system.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an intake system for a supercharged engine, and more particularly to a supercharged engine equipped with a main intake system that naturally takes in fresh air and an auxiliary intake system that supercharges the intake air. The present invention relates to an air intake device.

Conventionally, engines equipped with a supercharger have been known to have a turbo supercharger installed in a single intake system of the engine, and improve the output performance of the engine by supercharging the intake air into the engine. It is being

However, in this turbocharging method, a turbine rotated by the exhaust flow drives a blower, and the blower supercharges the intake air, so in the low engine speed range, the exhaust flow decreases, resulting in insufficient supercharging. However, there were problems in that the output performance could not be sufficiently improved and the responsiveness was poor.

Therefore, conventionally, as disclosed in Japanese Patent Publication No. 49-4081, an auxiliary intake system is provided in addition to the main intake system, and a supercharger is provided in the auxiliary intake system. While fresh air is supplied from the main intake system, when the set load of the engine is exceeded, supercharging air is supplied from the auxiliary intake system at least during the compression stroke in addition to the fresh air from the main intake system. A so-called partial supercharging type supercharger has been proposed, which allows intake supercharging to be performed with good responsiveness without causing insufficient supercharging even in the low rotational speed range of the engine.

However, with this partial supercharging method, during partial loads such as in the light load range of the engine, part of the air-fuel mixture in the combustion chamber flows back into the auxiliary intake system, causing the compression pressure to drop instead of rising.
Fuel flows into the supercharger, impairing engine performance.
There was a problem in that the supercharger deteriorated. ' Therefore, in view of the above, the present invention provides a partially supercharged supercharged engine as described above, with a check valve installed in the auxiliary intake system downstream of the supercharger to prevent backflow from the combustion chamber. By providing this, it is possible to improve engine performance by preventing a drop in compression pressure during partial load, and to improve the durability of the supercharger by preventing fuel from flowing into the supercharger. The present invention aims to provide an intake system for a supercharged engine.

Hereinafter, the present invention will be described in detail based on embodiments shown in the drawings.

In Figure 1, 1 is the engine, 2 is the cylinder, 6
41d is a combustion chamber defined by the cylinder 2 and the piston 5; and 5 is a crankshaft connected to the piston 5 via a connecting rod 6.

Further, 7 is an air cleaner, and 8 and 9 are a main intake system and an auxiliary intake system, respectively, which constitute the intake system of the engine 1. The main intake system 8 is composed of a main intake passage 1o whose upstream end is connected to the air cleaner 7 and whose downstream end is open to the combustion chamber 4.
A main throttle valve 11 is provided which is interlocked with the main air intake passage (not shown) and controls the amount of intake air from the main intake passage 10. Further, a fuel injection valve 12 is disposed upstream of the main throttle valve 11 in the main intake passage 10, and a measuring plate type air flow sensor 1!1 for detecting the total intake air amount is disposed further upstream. , the air flow sensor 15 is equipped with a potentiometer 1 that detects the rotation angle of the measuring plate.
4 is connected, and the output signal of the potentiometer 14 is inputted together with the engine rotational speed signal S to the control circuit 15 that controls the fuel injection amount of the fuel injection valve 12. Therefore, the intake air amount of the engine 1 is A fuel injection type fuel supply device 16 is constituted, which injects fuel in an amount corresponding to the engine speed from the fuel injection valve 12 and supplies it to the engine 1 via the main intake passage 10.

On the other hand, the auxiliary intake system 9 has an upstream end connected to the main intake passage 1.
The auxiliary intake passage 17 communicates with the fuel injection valve 12 and the main throttle valve 11 downstream of the airflow sensor 15 of the engine 0 and opens into the combustion chamber 4 at its downstream end. A supercharger 18 consisting of a supercharging pump is provided. The supercharger 18 is drivingly connected via an electromagnetic clutch 19 to a pulley 21 which is transmitted to the crankshaft 5 by a belt 20. Further, the downstream side of the supercharger 18 in the auxiliary intake passage 17 is connected to the main throttle valve 11 via a linkage 22, and until the main throttle valve 11 is opened to a set opening degree, that is, the set load of the engine is The auxiliary throttle valve 2 remains closed in the following cases, but opens when the main throttle valve 1'1 opens beyond the set opening, that is, when the engine load exceeds the set load! The auxiliary throttle valve 25 detects the opening degree of the auxiliary throttle valve 25 and switches the electromagnetic clutch 19 to O.
An opening sensor 24 is connected to operate the N-〇FF, so when the auxiliary throttle valve 25 is opened (when the load is higher than the set load), the electromagnetic clutch 19 is turned on and the pulley 21 (that is, the engine 1 ) to operate the supercharger 18, while when the auxiliary throttle valve 2!1 is closed (when the load is below the set load), the electromagnetic clutch 19 is turned off to stop the operation of the supercharger 18. It is configured.

Further, the auxiliary intake system 9 has one end opened downstream of the supercharger 18 and upstream of the auxiliary throttle valve 26 in the auxiliary intake passage 17,
A bypass passage 25 is provided, the other end of which opens upstream of the supercharger 18 of the auxiliary intake passage 17.
A J IJ valve 26 is provided, and when the supercharger 18 is in operation (supercharging), when the pressure (supercharging pressure) in the auxiliary intake passage 17 downstream of the supercharger 18 exceeds the set pressure, Above IJ IJ
- By opening the valve 26, the pressure is transferred to the bypass passage 25.
The supercharging pressure is maintained at the set pressure by being released to the auxiliary airway 17 upstream of the supercharger 18 via the supercharger 18.

Furthermore, the opening of the main intake passage 10 and the auxiliary intake passage 17 to the combustion chamber 4 (intake port 10a).

17a) is offset from a straight line passing through the center of the combustion chamber 4 in a substantially plane plane, and
The air intake passages 10.17 are arranged to swirl the intake air from each intake passage 10.17 to form a swirling flow. The main intake passage 10
A main intake valve 27 is provided at the intake port 10a of the auxiliary intake passage 17, and an auxiliary intake valve 28 is provided at the intake port 17a of the auxiliary intake passage 17.The valve timings of both intake valves 27 and 28 are shown in FIG. As shown, from the end of opening of the main intake valve 27, that is, the latter half of the intake stroke, to the compression stroke,
-28 are set so that they overlap and open at one end. In addition, from the point of view of preventing backflow of intake air into each intake passage 10.17, it is preferable to set the auxiliary intake valve 28 to open after the main intake valve 27 is closed, that is, during the compression stroke, without overlapping the intake air. preferable.

As a result of the above, when the engine load is below the set load, the main intake system 8
While the air-fuel mixture as fresh air is supplied to the engine-1 through natural intake from the main intake passage 10, when the load exceeds the set load of the engine, the auxiliary intake system supplies fresh air from the main intake system 8 at least during the compression stroke. 9 (auxiliary intake passage 17)
A so-called partial supercharging system is configured in which pressurized air as supercharging air is supplied to the engine 1 by the operation of the supercharger 18. In addition, 29 is a valve operating mechanism that controls the pulp timing of the auxiliary intake valve 28, and 50 is an exhaust port whose one end opens into the combustion chamber 4. +1 is the exhaust port 50
This is an exhaust valve disposed at the opening (exhaust port 50a) to the combustion chamber 4. Further, in FIG. 2, reference numeral 62 denotes an ignition plug temporarily disposed in the combustion chamber 4 on the upstream side of the swirling flow from the main intake passage 10, and the exhaust port 50 of the exhaust port 50 is located downstream of the ignition plug.
a is placed.

In addition to the above structure, the present invention is characterized in that in the auxiliary intake system 9, downstream of the supercharger 18 and the auxiliary throttle valve 23 in the auxiliary intake passage 17, there is a reverse valve, for example, a reed valve, which prevents backflow from the combustion chamber 4. A stop valve '55 is provided. The check valve 55 is preferably disposed as downstream of the auxiliary intake passage 17 as possible, and is preferably disposed, for example, at the connection portion between the intake manifold forming the auxiliary intake passage 17 and the engine 1.

Therefore, in the above embodiment, during supercharging when the engine has a set load or more, the fresh air mixture supplied from the main intake passage 10 and forming a swirling flow is supplied from the auxiliary intake passage 17 in the combustion chamber 4. Since the pressurized air of the supercharged air is supercharged with good response, there is no lack of supercharging even in the low engine speed range, and good output performance is obtained. Good combustibility can be obtained due to the mixing effect caused by the swirling flow.

On the other hand, during non-supercharging, when the engine is at a partial load below the set load, intake air (pressurized air) from the auxiliary intake passage 17 is not supercharged, and fresh air from the main intake passage 10 enters the combustion chamber 4. (mixture) is supplied. At that time, the auxiliary intake system 9
Due to the stop of supercharging from
However, this backflow is reliably prevented by a check valve provided in the auxiliary intake passage 17 downstream of the supercharger 18 and the auxiliary throttle valve 25. As a result, it is possible to prevent the compression pressure from dropping during the compression stroke, ensuring good engine performance similar to that of a normal engine, and preventing fuel from flowing into the supercharger 18. Therefore, deterioration of the supercharger 18 can be prevented and its durability can be improved. In particular, if the check valve 55 is provided as downstream of the auxiliary intake passage 17 as possible, the dead volume can be reduced as much as possible, which is effective in preventing the compression pressure from dropping.

Moreover, due to the arrangement of the reverse valve 55, the auxiliary throttle valve 23
Since the auxiliary throttle valve 23 only performs the supercharging control function, the auxiliary throttle valve 23 can be placed at any suitable position in the auxiliary intake passage 17 for easy linkage with the main throttle valve 11 in terms of structure and space. , which has the advantage of increasing the degree of freedom in its arrangement.

Furthermore, in the case of the type in which the supercharger 18 is activated when the auxiliary throttle valve 23 is opened, as in the above embodiment, the opening timing of the auxiliary throttle valve 28 and the activation timing of the supercharger 18 must be precisely matched. At least there is no problem, and
Since strict sealing performance is not required for the auxiliary throttle valve 23, the structure can be simplified, which is advantageous.

゛ Note that the present invention is not limited to the above-mentioned embodiment, but also includes various other modifications. For example, in the above-mentioned embodiment, the fuel supply device 1 provided in the main intake system 8
Although the fuel injection system has been described as No. 6, the present invention is also applicable to a carburetor system. However, in the case of this carburetor system, since the fuel is sucked in by the venturi negative pressure caused by the intake air flow, the fuel is vaporized at a position upstream of the opening at the upstream end of the auxiliary intake passage 17 of the main intake passage 10 through which all the intake air flows. This method is suitable for the fuel injection method as in the above embodiment, since fuel needs to be installed in the auxiliary intake passage 17 and there is a risk that fuel will flow into the supercharger 18 in the auxiliary intake passage 17 and contaminate the supercharger 18. Further, the fuel supply device 16 is connected to the main intake system 8
Of course, it may also be provided in the auxiliary intake system 9 as well.

Further, in the above embodiment, the supercharger 18 is connected to the pulley 21 that rotates synchronously with the engine 1 via the electromagnetic clutch 19, and is driven only during supercharging. In addition to being directly connected to and constantly driven, by providing a control valve in the bypass passage, the supercharged air from the supercharger 18 is passed through the bypass passage by operating the control valve when not supercharging, while Supercharger 18 during supercharging
The supercharged air may be supplied to the engine 1 via the auxiliary intake passage 17.

Furthermore, the electromagnetic clutch 19 is turned on and off by the output of the opening sensor 24 that detects the opening of the auxiliary throttle valve 2S.
However, it is 0N depending on the opening degree of the main throttle valve 11 linked with the auxiliary throttle valve 2S or the amount of intake air.
-OFF control may of course be used.

As explained above, according to the present invention, in a partially supercharged supercharged engine, it is possible to reliably prevent the air-fuel mixture in the combustion chamber from flowing back into the auxiliary intake system during partial load. It is possible to improve engine performance by preventing a drop in compression pressure, and also to improve the durability of the supercharger and simplify the structure of the auxiliary intake system.

[Brief explanation of drawings]

The drawings illustrate embodiments of the present invention, and FIG. 1 is a general schematic diagram, FIG. 2 is a schematic plan view of a combustion chamber, and FIG. 3 is an explanatory diagram showing valve timing of the main and auxiliary intake valves. be. 1. Engine, 4. Combustion chamber, 8. Main intake system, 9.
- Auxiliary intake system, 10... Main intake passage, 11... Main throttle valve, 16... Fuel supply device, 17... Auxiliary intake passage, 18
...Supercharger, 2'5...Auxiliary throttle valve, 27...Main intake valve, 28...Auxiliary intake valve, 55...Check valve.

Claims (1)

[Claims] [11 In addition to the main intake system, an auxiliary intake system is provided, and a supercharger is provided in the auxiliary intake system. When the load is below the set load of the engine, fresh air is supplied from the main intake system, while when the load is above the set load of the engine, the main intake system is In a supercharged engine that supplies supercharging air from the auxiliary intake system at least during the compression stroke in addition to fresh air from the intake system, backflow from the combustion chamber to the auxiliary intake system downstream of the supercharger is provided. An intake system for a supercharged engine, characterized in that it is provided with a check valve that prevents.