JPH0229849B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an intake device for a supercharged engine equipped with a mechanical supercharger.

(Prior art) Conventionally, supercharged engines have been equipped with a turbo supercharger in a single intake system of the engine, and the output performance of the engine has been improved by supercharging the intake air into the engine. Things are known.
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. This caused problems in that the output performance could not be sufficiently improved and the responsiveness was poor.

Therefore, conventionally, a supercharging method using a mechanical supercharger is being adopted. As an example, as disclosed in Japanese Patent Application Laid-Open No. 55-137314,
The intake system of the engine is composed of a main intake system and an auxiliary air system, and a fuel supply device is provided in the main intake system, and a mechanical supercharger is provided in the auxiliary air system. While the air-fuel mixture is supplied from the intake system, when the set load of the engine is exceeded, pressurized air is supplied from the auxiliary intake system at least during the compression stroke in addition to the air-fuel mixture from the main intake system. A so-called mechanical partial supercharging type supercharger has been proposed, which can perform intake supercharging with good responsiveness without causing insufficient supercharging even in the low rotational speed range of the engine. There is.

(Problem to be Solved by the Invention) However, in such a mechanical supercharging system, for example, when transitioning from a non-supercharging region to a supercharging region, the intake air is The volume increases rapidly immediately. On the other hand, the amount of fuel from the fuel supply system also increases in accordance with the increase in the amount of intake air, but due to poor vaporization and atomization of the fuel, the fuel adheres to the walls of the intake passage, so the amount actually increases. Only a portion of the fuel will be supplied into the combustion chamber. In other words, at the start of supercharging, the followability of fuel supply deteriorates, resulting in a delay in fuel supply, resulting in a problem of torque shock. This tendency is particularly noticeable during transient operation such as when the engine suddenly accelerates at the start of supercharging. Another problem is that torque shock occurs when the clutch of a mechanical supercharger is engaged.

Therefore, the present invention has been made in view of such problems, and in the above-mentioned mechanical supercharging type supercharged engine, it is possible to add fuel to the amount of fuel supplied according to the amount of intake air at the start of supercharging. By increasing the amount of fuel at the start of supercharging, for example, the amount of fuel flowing into the combustion chamber is increased in accordance with the increase in the amount of intake air, compensating for a fuel supply delay due to deterioration in followability of fuel supply, for example. In this way, it is an object of the present invention to provide an intake device for a supercharged engine that prevents the occurrence of torque shock and improves drivability.

(Means for Solving the Problem) In order to achieve the above object, the solution taken by the present invention is to provide a supercharger equipped with a mechanical supercharger that supercharges pressurized air to the intake system of the engine. Targets engines. and a setting means for setting the amount of fuel supplied to the intake system of the engine based on a signal related to the intake air amount of the engine, and a supercharging start time detection for detecting when the supercharger starts supercharging. and an increasing means which is provided with an output of the supercharging start detection means and increases the amount of fuel supplied to the intake system at the start of supercharging by adding it to the fuel supply amount by the detection means. be.

(Function) As a result, in the present invention, at the start of supercharging when transitioning from a non-supercharger to a supercharging region, the amount of intake air supplied into the combustion chamber by supercharging pressurized air from the supercharger immediately and rapidly increases. increases to On the other hand, the fuel supply amount is set to be increased by the setting means in accordance with this increase in the intake air amount, but this increased amount of fuel is caused by fuel adhesion to the intake passage wall due to worsening of fuel vaporization and atomization. Therefore, it is not immediately supplied to the combustion chamber,
Only a portion of it will be supplied. In other words, the followability of fuel supply is poor and fuel supply is delayed. However, at that time, the amount of fuel flowing into the fuel chamber is increased by increasing the amount of intake air as the amount of fuel flowing into the fuel chamber is increased by operating the amount increasing means to compensate for this fuel supply delay. As a result, the air-fuel ratio in the fuel chamber becomes a proper air-fuel ratio. Further, the output increase due to the increase in fuel amount can suppress torque shock caused by clutch engagement, and therefore, torque shock at the start of supercharging can be reliably prevented.

(Example) Hereinafter, an example of the present invention will be described in detail based on the drawings.

FIG. 1 shows an embodiment in which the present invention is applied to a partially supercharged supercharged engine. In the same figure, 1
is the engine, 2 is the cylinder, and 3 is the cylinder 2
A combustion chamber 4 is defined by the cylinder 2 and the piston 3, and a crankshaft 5 is connected to the piston 3 via a connecting rod 6.

Further, 7 is an air cleaner, and 8 and 9 are a main intake system and an auxiliary air system, respectively, which constitute the intake system of the engine 1. The main intake system 8 has an upstream end connected to the air cleaner 7 and a downstream end connected to the intake port 10.
It is constituted by a main intake passage 10 that opens into the combustion chamber 4 via a. A main throttle valve 11 is disposed in the main intake passage 10 and is operated in conjunction with an accelerator pedal (not shown) to control the amount of intake air from the main intake passage 10 . Further, a fuel injection valve 12 is provided upstream of the main throttle valve 11 in the main intake passage 10, and a measuring plate type air flow sensor 13 for detecting the total amount of intake air is provided further upstream of the fuel injection valve 12. A potentiometer 14 for detecting the rotation angle of the measuring plate is connected to the air flow sensor 13.
The output signal No. 4 is inputted together with the engine rotational speed signal S to a control circuit 15 that controls the fuel injection amount of the fuel injection valve 12. Therefore, an amount of fuel is injected from the fuel injection valve 12 according to the intake air amount of the engine 1 and the engine rotation speed, and the main intake passage 10
A fuel injection type fuel supply device 16 is configured to supply fuel to the engine 1 via the fuel injection device. Also,
The control circuit 15 constitutes a setting means for setting the amount of fuel supplied to the engine based on a signal related to the intake air amount of the engine.

On the other hand, the auxiliary intake system 9 has an upstream end communicating with the fuel injection valve 12 and the main throttle valve 11 downstream of the air flow sensor 13 of the main intake passage 10, and a downstream end communicating with the combustion chamber 4 via the intake port 17a. It is constituted by an auxiliary intake passage 17 that is open. A mechanical supercharger 18 made of, for example, a vane pump type supercharging pump is disposed in the middle of the auxiliary intake passage 17. The supercharger 18 is connected via an electromagnetic clutch 19 to
It is drivingly connected to a pulley 21 which is transmitted to the crankshaft 5 by a belt 20. Also,
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. An auxiliary throttle valve 23 is provided, which remains closed at times, but opens when the main throttle valve 11 is opened beyond a set opening, that is, when the engine load exceeds a set load. Further, the opening degree of the auxiliary throttle valve 23 is detected and the electromagnetic clutch 19 is activated.
An opening sensor 24 for ON-OFF operation is provided. Therefore, when the auxiliary throttle valve 23 is opened (when the engine load is higher than the set load), the electromagnetic clutch 19 is turned on and the supercharger 18 is operated by the pulley 21 (that is, the engine 1), while the auxiliary throttle valve is opened. When the valve 23 is closed (when the engine load is below the set load), the electromagnetic clutch 19 is
It is configured to turn off and stop the operation of the supercharger 18.

Further, the auxiliary intake system 9 has one end opened downstream of the supercharger 18 in the auxiliary intake passage 17 and upstream of the auxiliary throttle valve 23 , and the other end opened in the auxiliary intake passage 17 downstream of the supercharger 18 and upstream of the auxiliary throttle valve 23 .
8 is provided with a bypass passage 25 that opens upstream,
A relief valve 26 is provided in the bypass passage 25. Therefore, when the supercharger 18 is in operation (supercharging), if the pressure (supercharging pressure) in the auxiliary intake passage 17 downstream of the supercharger 18 exceeds the set pressure, the relief valve 26 is opened to reduce the pressure. Bypass passage 2
5 to the auxiliary intake passage 17 upstream of the supercharger 18 to maintain the supercharging pressure at the set pressure.

Furthermore, a main intake valve 27 is provided at the opening of the main intake passage 10 to the combustion chamber 4 (intake port 10a).
Further, auxiliary intake valves 28 are provided at the openings (intake ports 17a) of the auxiliary intake passages 17 into the combustion chamber 4, respectively. The valve timing of both intake valves 27 and 28 is as shown in FIG.
The auxiliary intake valves 28 are set to open partially overlapping each other from the end of the valve opening, that is, from the latter half of the intake stroke to the compression stroke. From the point of view of preventing backflow of intake air into the air passages 10 and 17, it is preferable to open the auxiliary intake valve 28 after the main intake valve 27 is closed, without overlapping, that is, during the compression stroke. .

As described above, when the engine's set load is below, the air-fuel mixture is supplied to the engine 1 through natural intake from the main intake system 8 (main intake passage 10), while when the engine's set load is above, the air-fuel mixture is supplied from the main intake system 8. In addition, at least during the compression stroke, the auxiliary intake system 9
Pressurized air is supplied to the engine 1 from the (auxiliary intake passage 17) by the operation of the supercharger 18,
A so-called partial supercharging system is configured.
In addition, 29 is a valve operating mechanism that controls the valve timing of the auxiliary intake valve 28, 30 is an exhaust passage whose one end opens into the combustion chamber 4, and 31 is the combustion chamber 4 of the exhaust passage 30.
This is an exhaust valve disposed at the opening (exhaust port 30a) to the exhaust port 30a. Further, the auxiliary throttle valve 23 performs supercharging control as described above, and also prevents the intake air in the combustion chamber 4 from flowing back into the auxiliary intake system 9, particularly the supercharger 18 when the auxiliary intake valve 28 is opened. In order to fulfill the role of a check valve, it is preferable to arrange it as downstream of the auxiliary intake passage 17 as possible, for example, at the connection between the intake manifold forming the auxiliary intake passage 17 and the engine 1.

In addition to the above configuration, as a feature of the present invention, 32
is a supercharging start time detection device as a supercharging start time detection means that detects the opening degree of the main throttle valve 11 and outputs a supercharging start time signal when the main throttle valve 11 is opened beyond a set opening degree. , 33 is a timer that holds the supercharging start timing signal of the supercharging start timing detection device 32 for a predetermined period of time, and inputs the supercharging start timing signal to the control circuit 15 during that time. By this timer 33 and control circuit 15, when the main throttle valve 11 is opened beyond the set opening degree, that is, when supercharging is started, the timer 3
The control circuit 15 receiving the output from the fuel injection valve 12 increases the amount of fuel injected into the main intake passage 10 from the fuel injection valve 12 for a predetermined period of time by adding it to the fuel supply amount set based on the intake air amount. This constitutes a quantity increasing means 34 designed to do so. Said increasing means 3
The amount of fuel supplied according to No. 4 is set to be increased in addition to the amount of increase required to maintain a constant air-fuel ratio due to an increase in the amount of intake air in the supercharging region.

Therefore, in the above embodiment, when the engine is under the set load and is not supercharged, the auxiliary intake passage 1
Pressurized air is not supplied from the main intake passage 10, and only the air-fuel mixture from the main intake passage 10 is supplied into the combustion chamber 4. In that case, the increasing means 34 does not operate, and the fuel supply device 16 supplies fuel to the main intake passage 10 according to the amount of intake air and the engine speed, so that good engine performance can be achieved like in a normal engine. can be secured.

On the other hand, when the engine is supercharged above the set load,
In the combustion chamber 4, the air-fuel mixture supplied from the main intake passage 10 is supercharged with pressurized air from the auxiliary intake passage 17 with good responsiveness, so there is no lack of supercharging and good output performance is achieved. is obtained.

Here, at the start of supercharging when transitioning from the non-supercharging region to the supercharging region, the amount of intake air supplied into the combustion chamber 4 due to the supercharging of pressurized air from the auxiliary intake passage 17 immediately and rapidly increases. On the other hand, in response to this increase in intake air amount, the main intake passage 10 is
Although the amount of fuel injected into the main intake passage 10 is increased, this increased amount of fuel is caused by the low flow rate of intake air due to natural intake in the main intake passage 10 and the deterioration of fuel vaporization and atomization caused by this low flow rate. Due to its adhesion to the walls of the passage 10, it is not immediately supplied to the combustion chamber 4, but only partially. In other words, followability of fuel supply is required, and a delay in fuel supply occurs. However, at this time, due to the operation of the fuel increasing means 34, the injection width of the fuel injection valve 12 of the fuel supply device 16 is increased to compensate for this fuel supply delay, and the fuel injection width is increased from the fuel injection valve 12 to the main intake passage 10. Since the amount of fuel that flows into the combustion chamber 4 is increased for a predetermined period of time, the amount of fuel that actually flows into the combustion chamber 4 increases in accordance with the increase in the amount of intake air, and as a result, the air-fuel ratio in the combustion chamber 4 is maintained at an appropriate air-fuel ratio. becomes. Therefore, torque shock at the start of supercharging can be reliably prevented, and good drivability can be ensured even during transient operation such as sudden acceleration.

It should be noted that the present invention is not limited to the above-mentioned embodiments, but also includes various other modifications. For example, in the above embodiment, a fuel injection system was described as the fuel supply system 16 provided in the main intake system 8, but the present invention is also applicable to a carburetor system. However, in the case of this vaporizer method,
Main intake passage 1 through which all intake air flows as fuel is sucked by the negative pressure of the intake air flow
It is necessary to provide a carburetor at a position upstream of the upstream end opening of the auxiliary intake passage 17 of the engine 0, and therefore there is a risk that fuel may flow into the supercharger 18 of the auxiliary intake passage 17 and contaminate the supercharger 18. Therefore, the fuel injection method as in the above embodiment is suitable.

Further, in the above embodiment, the main throttle valve 11 is used as the increasing means 34 for increasing the amount of fuel by adding to the fuel supply amount set according to the intake air amount at the start of supercharging.
a timer 33 that holds the output of the supercharging start timing detection device 32 for a predetermined period of time, which detects when the opening is more than a set opening degree, and a control circuit 1 that inputs the output during that time.
5, and the control circuit 15 receiving the output from the timer 33 increases the fuel injection amount from the fuel injection valve 12 of the fuel supply device 16 by adding it to the fuel supply amount corresponding to the intake air amount. However, an increase fuel injection valve separate from the fuel injection valve 12 is provided in the main intake system 8, and when supercharging is started, the fuel injection valve 12 injects an amount corresponding to the amount of intake air and the engine speed. of fuel may be injected, and an additional amount of fuel may be injected and supplied from the separate increase fuel injection valve. Further, in the case of a carburetor system, a fuel pump for increasing the amount of fuel may be provided in the main intake system 8.

Further, the supercharging start timing detecting device 32 serves as a supercharging start detection means, which detects when the main throttle valve 11 is opened to a preset opening degree or more. The start of supercharging may be detected based on the opening operation of 23. However, when the opening degree of the main throttle valve 11 is detected as in the above embodiment, the amount of fuel can be increased slightly before the actual start of supercharging, which has the advantage of more reliably preventing torque shock. be.

Furthermore, in the above embodiment, the timer 33 is provided to increase the amount of fuel for a predetermined period of time when starting the supercharger by adding it to the amount of fuel supplied according to the amount of intake air. It is also possible to increase the amount of fuel in the entire fuel supply range, that is, in the high load operating region of the engine. In this case, it is effective in that the output can be improved during high load.

In addition, in the above embodiment, the supercharger 18 is connected via the electromagnetic clutch 19 to the pulley 21 that rotates coaxially with the engine 1, and is driven only during supercharging. The turbocharger 1 is directly connected to the turbocharger 1 and driven at all times, and a control valve is provided in the bypass passage to open the control valve when not supercharging.
The supercharged air from 8 is relieved through the bypass passage, while the supercharged air is supplied to the engine 1 through the auxiliary intake passage 17 by substantially operating the supercharger 18 during supercharging. good.

Furthermore, in the above embodiment, the auxiliary throttle valve 23
The electromagnetic clutch 19 is ON-OFF controlled by the output of the opening sensor 24 that detects the opening of the turbocharger 18.
The operation of the main throttle valve 1 which is linked to the auxiliary throttle valve 23 is controlled by the opening sensor 24.
The operation of the supercharger 18 may be controlled by detecting the opening degree of 1, or the operation of the supercharger 18 may be controlled according to the amount of intake air, boost pressure, or the like.

(Effects of the Invention) As explained above, according to the present invention, in a mechanically supercharged engine with a supercharger, at the start of supercharging when transitioning from a non-supercharging region to a supercharging region, the air is supplied to the intake system. The amount of fuel to be supplied is added to the fuel supply amount set according to the amount of intake air to increase the amount of fuel, and the amount of fuel that actually flows into the combustion chamber is increased in accordance with the increase in the amount of intake air to achieve an appropriate air-fuel ratio. As a result, torque shock at the start of supercharging can be reliably prevented, and drivability can be improved.

[Brief explanation of drawings]

The drawings illustrate embodiments of the invention.
The figure is an overall schematic diagram, and FIG. 2 is an explanatory diagram showing valve timings of the main intake valve and the auxiliary intake valve. 1...Engine, 4...Combustion chamber, 8...Main intake system, 9...Auxiliary intake system, 10...Main intake passage, 1
1... Main throttle valve, 15... Control circuit, 16... Fuel supply device, 17... Auxiliary intake passage, 18... Supercharger, 23... Auxiliary throttle valve, 27... Main intake valve,
28... Auxiliary intake valve, 32... Supercharging start timing detection device (supercharging start detection means), 33... Timer,
34...Means for increasing the amount.

Claims (1)

[Claims] 1. In a supercharged engine equipped with a mechanical supercharger that supercharges pressurized air into the engine intake system, the engine intake system a setting means for setting a fuel supply amount to be supplied to the supercharger; a supercharging start detection means for detecting when supercharging is started by the supercharger; 1. An intake system for a supercharged engine, comprising: increasing means for increasing the amount of fuel supplied to the intake system by adding the amount of fuel supplied to the intake system to the amount of fuel supplied by the setting means.