JPS6139493B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in an intake system for a supercharged engine.

Conventionally, as an intake system for a supercharged engine, in addition to a main intake system that supplies fresh air using the engine's intake negative pressure, a supercharger driven by the engine and a system installed downstream of the supercharger have been used. An auxiliary intake system equipped with an auxiliary throttle valve is provided, which supplies fresh air from the main intake system below the engine's set load, and supplies fresh air from the main intake system at least during the compression stroke at or above the engine's set load. A supercharged engine in which supercharging air is supplied from the auxiliary intake system is known, for example, as shown in Japanese Patent Laid-Open No. 137314/1983.

However, the auxiliary intake system is provided with an auxiliary throttle valve to supply supercharging air according to load fluctuations, but the supercharger is driven by the engine,
Since the discharge pressure simply changes depending on the engine speed regardless of the engine load condition, for example, when the turbocharger is operating and the auxiliary throttle valve opening is small, the auxiliary intake system The boost pressure (the boost pressure between the supercharger and the auxiliary throttle valve) increases. This tendency is noticeable in operating conditions where the opening of the auxiliary throttle valve is small and the supercharger is driven at high revolutions (when the engine load is relatively small and the engine revolutions are high). As a result, the driving resistance (driving torque) of the supercharger increases, the engine load increases, and fuel efficiency deteriorates, and the supercharger overheats, which has a negative impact on durability. This has the disadvantage that the engine shock occurs due to increased driving resistance at the beginning of the feeder drive.

The present invention has been made in view of the above problems, and provides an intake system for a supercharged engine that improves the driving efficiency of the supercharger and prevents the engine from experiencing shock during the early stages of driving the supercharger. The purpose is to

In order to achieve the above object, the present invention provides, in addition to the main intake system, an auxiliary intake system that includes a supercharger driven by the engine and an auxiliary throttle valve provided downstream of the supercharger. Fresh air is supplied from the main intake system when the engine's set load is below, and supercharging air is supplied from the auxiliary intake system at least during the compression stroke in addition to fresh air from the main intake system when the engine's set load is higher than the set load of the engine. The supercharged engine is characterized by being provided with a control device that increases the supercharging pressure between the supercharger and the auxiliary throttle valve in accordance with an increase in the opening of the auxiliary throttle valve.

Embodiments of the present invention will be described below with reference to the drawings. In FIG. 1, 1 is an engine, 2 is a main intake system that supplies fresh air to the engine 1 through a main intake port 4 that opens into the combustion chamber 3 of the cylinder head 1a of the engine 1, and 5 is the combustion chamber 3. 7 is an auxiliary intake system that supplies supercharging air to the engine 1 through an auxiliary intake port 6 that opens into the combustion chamber 3, and an exhaust system that discharges exhaust gas from the engine 1 through an exhaust port 8 that also opens into the combustion chamber 3. be.

In the main intake system 2, 9 is a main intake valve that opens and closes the main intake port 4 at predetermined timing, 10 is a main throttle valve that is interposed in the middle of the main intake passage 11 and controls the intake flow rate, and 12 is a main throttle valve 10 A fuel injection nozzle 13 injects fuel upstream of the fuel injection nozzle, and 13 is an injection control device that controls the fuel injection amount.

The injection control device 13 includes an air flow meter 1
receiving the intake air amount signal detected by 4 and the engine rotation speed signal detected by rotation sensor 15;
Based on these signals, a fuel injection amount according to the operating state of the engine 1 is calculated, and a control signal is issued to the fuel injection nozzle 12 to inject a predetermined amount of heating material into the main intake system 2.

In the auxiliary intake system 5, 16 is an auxiliary intake valve that opens and closes the auxiliary intake port 6 at predetermined timing (see Fig. 2) by a timing cam 17, and 18 is a vane type air pump interposed in the middle of the auxiliary intake passage 19. This is a supercharger.

The supercharger 18 is driven by the engine 1 via an electromagnetic clutch 20. That is, due to the reciprocating movement of the piston 21 in the engine 1, the connecting rod 2
The supercharger 18 is rotationally driven by the driving force of the crankshaft 23, which is rotationally driven through the crankshaft 23, transmitted through the drive device 24, and the supercharger 18 is driven by connecting and disconnecting the electromagnetic clutch 20. Stopping is controlled.

The electromagnetic clutch 20 is connected or disconnected depending on the load of the engine 1, and is connected to or disconnected from the main throttle valve 1, for example.
It is controlled according to the opening degree of 0 or intake negative pressure, etc.
When the load on engine 1 exceeds the set value,
When the electromagnetic clutch 20 is connected, the supercharger 18
It is configured to drive.

Reference numeral 25 denotes an auxiliary throttle valve installed in the auxiliary intake passage 19 downstream of the supercharger 18. The auxiliary throttle valve 25 is linked to the main throttle valve 10 by a link mechanism or the like, so that the main throttle valve 10 In conjunction with the opening to a predetermined opening degree or more, a linked operation is performed to open from the closed state.

Furthermore, 26 is a relief passage that bypasses the supercharger 18, and 27 is a relief valve as a pressure control valve provided in the relief passage 26, and the relief pressure (set pressure) of the relief valve 27 is controlled by the auxiliary throttle. Controlled according to the opening degree of the valve 25,
The relief valve 27 and the auxiliary throttle valve 25 cooperate to form a control device 28 that increases the supercharging pressure between the supercharger 18 and the auxiliary throttle valve 25 in accordance with an increase in the opening degree of the auxiliary throttle valve 25. has been done.

In the relief valve 27, 27a is a valve body that opens and closes the relief passage 26, and 27b is a valve body 27.
A first spring receiver 27c is connected to the first spring receiver 27b, a second spring receiver 27c is slidably inserted into the first spring receiver 27b, and 27d is compressed between the spring receivers 27b and 27c to support the valve body 27a. This is a spring that biases the valve in the valve closing direction. The second spring receiver 27c of this relief valve 27 is connected to the link mechanism 2.
linked to the opening/closing mechanism of the auxiliary throttle valve 25 via 9;
As the opening degree of the auxiliary throttle valve 25 increases, the second
The spring receiver 27c is the first spring receiver 27
The spring 27d is configured to move in the direction b to increase the biasing force of the spring 27d.

That is, the set pressure (relief pressure) of the relief valve 27 increases as the opening degree (engine load) of the auxiliary throttle valve 25 increases, and the amount of air returned through the relief passage 26 decreases, thereby preventing excess pressure. A variable set pressure device is configured so that the discharge pressure of the feeder 18 increases accordingly.

On the other hand, in the exhaust system 7, 30 is the exhaust port 8
An exhaust valve 31 opens and closes at a predetermined timing, and 31 is an exhaust passage communicating with the exhaust port 8.

The relationship between the opening and closing timings of the main intake valve 9 and the auxiliary intake valve 16 is as illustrated in FIG.
6 opens from the end of the intake stroke to the compression stroke,
It closes at a later time than the main intake valve 9,
Supercharging air is supplied from the auxiliary intake system 5 at least during this compression stroke.

Next, to explain the operation of the above embodiment, when the engine 1 is under low load, the supercharger 18 is not driven, and fresh air is supplied to the combustion chamber 3 only from the main intake system 2 by natural intake. Ru. At this time, the auxiliary throttle valve 25 closes the auxiliary intake passage 19.

When the load on the engine 1 increases and the main throttle valve 10 is opened wide, the electromagnetic clutch 20 becomes sustained and the supercharger 18 is driven, pressurized air is discharged from the supercharger 18, and the main The auxiliary throttle valve 25 opens in conjunction with the opening operation of the throttle valve 10, and supercharged air is supplied from the auxiliary intake system 5 to the combustion chamber 3 in addition to fresh air from the main intake system 2.

At that time, due to the action of the control device 28, the supercharger 1
8, that is, the supercharging pressure between the supercharger 18 and the auxiliary throttle valve 25 increases as the opening degree of the auxiliary throttle valve 25 increases, that is, as the load on the engine 1 increases, and the load state of the engine 1 increases. Appropriate supercharging air is supplied to the combustion chamber 3 according to the condition.

FIG. 3 shows a modification of the control device 32, in which a diaphragm 33a is used to control the relief pressure of the relief valve 33, which compares the passage pressures upstream and downstream of the auxiliary throttle valve 25 in the auxiliary intake passage 19. , a valve body 3 is attached to a diaphragm 33a that partitions a first chamber 33b into which passage pressure is introduced upstream of the auxiliary throttle valve 25 and a second chamber 33c into which passage pressure is introduced downstream.
3d is supported, and the valve body 33d is biased in a direction to close the relief passage 26 by a compression spring 33e.

In the above modification, when the opening degree of the auxiliary throttle valve 25 (that is, the engine load) is small, the pressure upstream of the auxiliary throttle valve 25 is significantly larger than the pressure downstream, so that the valve closing force of the spring 33e is reduced. Relief pressure becomes low. In addition, the auxiliary throttle valve 25
As the valve opens, the pressure difference between the two decreases, the reduction effect of the valve closing force of the spring 33e decreases, and the relief pressure increases. As a result, the discharge pressure of the supercharger 18 increases as the engine load increases. will increase.
In FIG. 3, 33f is an orifice that eliminates pulsation in the auxiliary intake passage 19.

In addition, in the above embodiment, the control devices 28, 3
2, the operating pressure of the relief valves 27, 33 is controlled according to the opening degree of the auxiliary throttle valve 25, but instead of this, the operating pressure of the relief valves 27, 33 is controlled mainly in the operating range of the supercharger 18. Control may be performed according to the opening degree of the throttle valve 10, or a control device may be employed that controls the driving rotation speed of the supercharger 18 according to the engine load.

Further, in the above embodiment, fuel is supplied only to the main intake system 2, but fuel may also be supplied to the auxiliary intake system 5 in addition to the main intake system 2. Instead of the nozzle 12, a fuel supply device using a carburetor may be used.

Further, in addition to reciprocating engines, the above-mentioned intake device can also be applied to, for example, rotary piston engines.

Therefore, according to the present invention as described above, the supercharging pressure between the supercharger and the auxiliary throttle valve is increased in accordance with the increase in the opening degree of the auxiliary throttle valve, so that the supercharging pressure is increased. It changes in response to the engine's demand and can always supply the appropriate amount of supercharging air, preventing engine shock during the early stages of turbocharger operation, and improving the drive efficiency of the supercharger. Furthermore, overheating of the supercharger can be avoided, and the desired supercharging effect by the main intake system and the auxiliary intake system can be favorably exerted.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention; FIG. 1 is an overall configuration diagram of a supercharged engine, FIG. 2 is a curve diagram showing valve opening/closing timing, and FIG. 3 is a main part showing a modification of the control device. FIG. DESCRIPTION OF SYMBOLS 1...Engine, 2...Main intake system, 5...Auxiliary intake system, 18...Supercharger, 28...Control device, 3
2...Control device, 27, 33...Relief valve, 2
9...Link mechanism, 33a...Diaphragm.

Claims (1)

[Scope of Claims] 1. In addition to the main intake system, an auxiliary intake system is provided that includes a supercharger driven by the engine and an auxiliary throttle valve provided downstream of the supercharger, and the system is equipped with a In this supercharging system, fresh air is supplied from the main intake system, and when the engine load exceeds the set load of the engine, 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 supercharged engine characterized in that the turbocharged engine is provided with a control device that increases supercharging pressure between the supercharger and the auxiliary throttle valve in accordance with an increase in the opening of the auxiliary throttle valve. Intake device. 2 A control device is provided between the supercharger and the auxiliary throttle valve, and includes a pressure control valve that relieves a part of the boost pressure when it exceeds a set pressure, and a control device that controls the set pressure of the pressure control valve by controlling the set pressure of the pressure control valve. An intake system for a supercharged engine according to claim 1, comprising a variable set pressure device that increases the set pressure in accordance with an increase in the opening degree of the valve.