JPS6385220A - Suction air device for engine provided with supercharger - Google Patents

Abstract

PURPOSE:To prevent the generation of an air flow noise in the case where the opening degree of a control valve is small by providing a throttle member between the control valve and the communication part to the suction side of a supercharger, in a device where a by-pass passage installed with a control valve is so provided as to by-pass the supercharger in a suction air passage. CONSTITUTION:An air cleaner 7, an airflow meter 8, a throttle valve 9, a mechanical supercharger 10, a surge tank 11 and a fuel injection nozzle 12 are provided, from the upper stream side, in a suction air passage 5. And a by-pass passage 16 which bypasses the supercharger 10 is provided. In this by-pass passage 16, a control valve 17 which controls the air quantity passing through the passage 16 is provided and a throttle part 22 for controlling the cross area of the by-pass passage 16 to expand or contract is provided in the specified position, on the supercharger suction side, of this control valve 17. And the opening/closing control of the control valve 17, that is, the control of the negative pressure introduction quantity to an actuator 18 by negative pressure adjusting valve 21 on a negative pressure introduction passage 19 is carried out, together with the control of a fuel injection quantity and others, by a controller 31.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an intake system for a supercharged engine in which an intake passage is provided with a supercharger.

(Prior Art) In recent years, engines equipped with a supercharger in the intake passage have been put into practical use in order to increase the amount of air supplied to the combustion chamber and improve output. There are exhaust turbo superchargers that utilize exhaust energy and mechanical superchargers that are driven by the engine output shaft.

By the way, in this type of supercharger, the boost pressure changes depending on the engine load, and it is necessary that high boost pressure can be obtained especially at high loads when a large amount of air is required. However, since the above-mentioned mechanical supercharger is driven by the engine output shaft, the supercharging pressure depends on the engine rotation speed, and sufficient supercharging pressure is not necessarily obtained under high load. Therefore, as shown in Fig. 8, a bypass passage C@ is provided in the intake passage A to communicate the suction side and the discharge side of the supercharger B, and the amount of air passing through the bypass passage C is controlled. A control valve is provided, and the boost pressure is adjusted according to the load by adjusting the opening degree of the control valve (see Japanese Utility Model Publication No. 14591/1983). In other words,
When the load is low, the opening of the control valve is increased to perform supercharging [8
By increasing the amount of relief air that flows back through the bypass passage C from the discharge side to the suction side, unnecessary increases in boost pressure can be suppressed, and at high loads, the opening degree of the control valve can be reduced to provide relief. By reducing the amount of air m or fully opening the $ control valve to block the bypass passage C, the required supercharging pressure can be obtained.

(Problems to be Solved by the Invention) By the way, as described above, a control valve is provided in the bypass passage C that communicates the suction side and the discharge side of the supercharger 41B, and the valve is controlled to open and close according to the load. If you do so, the following problems will occur.

In other words, when the engine is under medium or high load,
When the opening degree of the control valve is small, in the bypass passage C, the pressure on the supercharger discharge side C1 of the control valve 1 is high;
The pressure on the turbocharger suction side C2 becomes low, and the pressure difference on both sides of the control valve increases, so that air flows from the turbocharger discharge side C1 to the suction side C2 through the passage narrowed by the control valve. The air flows at a high velocity, and at this time a harsh airflow noise is generated.

In addition, when the opening degree of the control valve suddenly changes, for example from a fully closed state to a fully open state, or from a fully open state to a fully open state, the supercharger suction side C2 in the bypass passage C
A large positive pressure wave or negative pressure wave is generated, and accordingly, a pressure fluctuation occurs in the intake passage A on the upstream side of the supercharger B. Therefore, as shown by the chain line in Fig. 8, when an air 70-meter E is installed upstream of the intake passage A to detect the air intake amount required for controlling the fuel supply base, the above-mentioned The pressure fluctuations affect the air flow meter E, causing it to malfunction and causing a disturbance in the control of the fuel supply m.

The present invention addresses the above-mentioned conventional problems, and provides a supercharged engine in which a control valve is provided in a bypass passage that communicates the suction side and discharge side of a supercharger in an intake passage. The purpose of this invention is to prevent or reduce the generation of air flow noise when the opening degree of a υ control valve is small, and to prevent malfunction of an air flow meter when the opening degree of the valve suddenly changes.

(Means for Solving the Problems) That is, in the intake system for a supercharged engine according to the present invention, the intake passage passes through a bypass passage that communicates the suction side and the discharge side of the supercharger in the intake passage. The present invention is characterized in that it includes a control valve that controls the amount of air, and that a throttle member is provided between the control valve and the communication portion to the supercharger suction side in the bypass passage.

This restricting member may be one that restricts or reduces the passage cross-sectional area of the bypass passage in a fixed manner, or may be one that can release the restriction as necessary.

The opening degree of the control valve is adjusted according to the engine load, and when the load is low, the amount of relief air flowing through the bypass passage from the turbocharger discharge side to the suction side is increased, and when the load is high, the amount of relief air is increased. However, when the engine is idling when the supercharger is not operating,
The control valve is fully opened to allow air to pass through the bypass passage from the supercharger suction side to the discharge side.

(Function) According to the above configuration, the opening degree of the control valve on the bypass passage is reduced at times of high load, etc., and the pressure on the turbocharger discharge side of the passage is accordingly high, causing the turbocharger to When the pressure on the suction side is low, an intermediate pressure region is formed between the control valve and the throttle member provided on the suction side of the supercharger, resulting in a pressure difference on both sides of the control valve. becomes smaller. Therefore, the flow velocity of the relief air flowing from the supercharger discharge side to the suction side through the control valve is reduced, and air flow noise is accordingly reduced.

In addition, even if positive pressure waves or negative pressure waves occur on the supercharger suction side of the control valve when the opening degree of the control valve suddenly changes, these pressure waves are attenuated by the throttle member, and the pressure is reduced. This prevents large pressure fluctuations from occurring on the upstream side of the supercharger in the intake passage due to waves. Therefore, when an air meter is provided in the upstream portion of the intake passage, malfunction of the air meter due to the above-mentioned pressure fluctuations can be prevented.

(Example) Examples of the present invention will be described below.

As shown in Fig. 1, the engine 1 includes intake and exhaust valves 2.3.
An intake passage 5 and an exhaust passage 6 are provided which communicate with the combustion chamber 4 through the intake passage 6, and in the intake passage 6, from the upstream side, an air cleaner 7, an air 70-meter 8, a throttle valve 9, a supercharging VA 10, A surge tank 11 and a fuel injection nozzle 12 are provided, and the exhaust passage 6 is provided with a catalyst device and a muffler, although not shown.

The supercharger 10 is a mechanical supercharger that is driven by the output shaft 13 of the engine 1 via a transmission mechanism 14 using a chain or belt, and an electromagnetic clutch 15 is provided in the middle of the drive path. Intervention is provided. Further, a bypass that bypasses the supercharger 10 is provided between the downstream part of the throttle valve 9 on the suction side of the supercharger 10 of the intake passage 5 and the surge tank 11 on the discharge side of the supercharger 10. A passage 16 is provided, and a control valve 17 is provided above the bypass passage 16 to control the amount of air passing through the passage 16, and the opening degree of this control valve 17 is controlled by IIJ! ! A negative pressure diaphragm type actuator 18 is provided. This actuator 18
is actuated by the intake negative pressure introduced through the check valve 20 and the negative pressure regulating valve 21 by the negative pressure passage 19 branched from the vicinity of the communication part to the supercharger suction side in the bypass passage 16, and The opening of the control valve 17 is increased in accordance with the increase in the amount of negative pressure introduced by the pressure regulating valve 21. As a feature of the present invention, a throttle section 22 is provided in the bypass passage 16 at a predetermined position on the supercharger suction side of the control valve 17 to narrow the cross-sectional area of the passage 16.

On the other hand, this engine 1 includes control of a fuel injector by the fuel injection nozzle 12, control of connection/disconnection of an electromagnetic clutch 15 interposed on the drive path of the supercharging member 10, and control of the negative pressure introduction passage 19. A controller 31 is provided that controls the amount of negative pressure introduced into the actuator 18 by the negative pressure regulating valve 21 above, that is, controls the opening and closing of the control valve 17. The amount signal a and the throttle opening signal from the sensor 32 that detects the opening of the throttle valve 9, the engine rotational speed signal C from the sensor 33 that detects the rotational speed of the engine output shaft 13, and the engine cooling water A water temperature signal d from a sensor 34 that detects temperature is input.

The controller 31 performs the fuel injection amount control, the connection/disconnection control of the electromagnetic clutch 15, and the control of the negative pressure regulating valve 21 to the opening/closing valve 17, respectively, as follows. In other words, regarding fuel injection amount control, the air intake m per cycle into the combustion chamber 4 is determined based on the air intake amount signal a and the engine speed signal C, and the fuel supply amount is determined according to this intake amount. At the same time, it is detected and corrected according to the warm-up state of the engine 1 indicated by the water temperature signal 9d.
A fuel control signal e is outputted to the fuel injection nozzle 12 so that the injection (i) is achieved. Regarding the connection/disconnection control of the electromagnetic clutch 15, as shown in FIG. It is determined whether the current engine operating state is within the idle region O based on the throttle opening signal and the engine rotation speed signal C, and if the current engine operating state is within the idle region O, the electromagnetic clutch 15 is disconnected. If the engine is not in the idle region 0, that is, if it is in the normal operating region, a clutch control signal t is output to connect the clutch 15.

Furthermore, regarding the opening/closing control of the control valve 17, in the entire engine operating range shown in FIG. In addition to setting the load range (2), it is determined in which range the current operating state is based on the throttle opening signal and the engine rotational speed signal C. Then, when in the low load region, sufficient negative pressure is introduced into the actuator 18, and when in the high load region, the introduction of negative pressure to the actuator 18 is cut off (atmosphere is introduced). In addition, when in the medium load area ■, a negative pressure control signal 9 is output to each negative pressure regulating valve 21 so as to introduce negative pressure according to the load, and this causes the control valve 17 to be fully opened in low load area work. In the high load area (■), the valve 17 is fully closed, and in the medium load area (■), the control valve 17 is closed as the load increases.
control to reduce the opening degree.

Next, the operation of the above embodiment will be explained.

When the engine 1 is in a normal operating range other than the idle range O, the supercharger 10 provided in the intake passage 5 is connected to the transmission mechanism 14 and the electromagnetic shoe latch 1 by the engine output shaft 13.
5, the air cleaner 7
The air sucked in through the throttle valve 8 is pressurized by the supercharger 10 and then supplied under pressure from the surge tank 11 to the combustion chamber 4; The air pressure, that is, the supercharging pressure, is adjusted as follows depending on the load. That is, in low-load area work that does not require high boost pressure, sufficient negative pressure is introduced into the actuator 18 via the negative pressure regulating valve 21 operated by the negative pressure control signal g from the controller 31, and the bypass is activated. By fully opening the control valve 17 on the passage 16, a considerable portion of the air discharged from the supercharger 1° is transferred from the surge tank 11 to the bypass passage 16 as relief air.
This prevents the supercharging pressure from becoming higher than necessary. In addition, in the medium load region (■), the negative pressure regulating valve 21 is
By reducing the opening degree of the control valve 17 via the actuator 18 in accordance with the increase in load, the amount of relief air recirculated from the discharge side to the suction side of the supercharger 110 through the bypass passage 16 decreases in accordance with the increase in load. The boost pressure is increased as the load increases.

In the high load region (2), the control valve 17 is fully opened, thereby blocking the bypass passage 16, reducing the amount of relief air to zero, and raising the boost pressure to the required high pressure. In this way, the boost pressure is controlled according to the engine load, and accordingly, the amount of air supplied to the combustion chamber 4 is also precisely controlled according to the load.

In addition, in the idle region O, the electromagnetic clutch 15 is disconnected and the supercharger 10 is stopped, but in this case,
The control valve 17 is fully opened, and air necessary for idle operation is supplied to the combustion chamber 4 through the bypass passage 16.

However, when part of the air discharged from the supercharger 1o is recirculated to the suction side of the supercharger 10 through the control valve 17 through the bypass passage 16 as described above, especially when the opening degree of the control valve 17 is small. In this case, a bypass passage 16 is provided as shown in FIG.
Turbocharger discharge side passage (surge tank 11 side) 16 in
1 is high, and the pressure P2 of the supercharger suction side passage (throttle valve 9 side) 162 is low, resulting in a large pressure difference JP (-P+-P2). but,
Since a throttle section 22 is provided on the supercharger suction side of the control valve 17, an intermediate section 16 between the control valve 17 and the throttle section 22
3, the above pressure P1. A region having a pressure P3 between P2 and P2 is formed, and the pressure difference ΔP' on both sides of the control valve 17 is
becomes smaller than the pressure difference ΔP. Therefore, the flow velocity V' of the air passing through the control valve 17 corresponding to the pressure difference JP/ or the gradient of pressure change shown in FIG. This reduces air flow noise when the relief air passes through the control valve 17. In addition, by providing the constriction part 22, a new pressure difference ΔP" (-P3-
P2) will occur, but since this pressure difference Ap'' is also smaller than the pressure difference ΔP, no airflow noise will be generated.

Furthermore, if the opening degree of the control valve 17 suddenly changes from a fully closed state to a fully open state or in the opposite direction, for example, at the time of transition of the operating region between the low load region and the high load region (2),
A pressure wave Xo as shown in FIG. 4 is generated on the supercharger suction side of the control valve 17 in the bypass passage 16, and this wave propagates to the supercharger upstream side (suction side) of the intake passage 5. In that case, since the constriction section 22 is provided on the propagation path of this pressure wave Xo, the attenuation rate becomes larger compared to the case where the constriction section shown by the symbol x1 in FIG. 4 is not provided. , a significantly small pressure wave X when propagated to the intake passage 5 side.
It becomes 1'. Therefore, pressure fluctuations in the upstream portion of the intake passage 5 caused by this pressure wave Xo are also weak. As a result, the air 7 installed in the upstream part of the intake passage 5
This prevents a malfunction in which the 0-meter 8 is erroneously operated due to large pressure fluctuations, and the fuel injection ffi MI20 based on the air intake group signal a from the air flow meter 8 is performed correctly.

Here, as shown in FIG. 5, an expansion space 23' is provided between the control valve 17' and the throttle part 22' in the bypass passage 16'.
By providing this, pressure waves such as those described above will be more effectively attenuated, and malfunctions of the air flow meter can be more reliably prevented.

In the above embodiment, the bypass passage 16.16' is provided with a constriction part 22.22' that fixedly constricts the cross-sectional area of the passage, but as shown in FIG. Part 2
2.22' may be replaced by a throttle member 22'' with a variable throttle amount.In other words, a negative pressure adjusted according to the load is introduced into this throttle member 22'' by a negative pressure regulating valve 21''. It is actuated by the actuator 24'', and as shown in FIG. 7, similarly to the control valve 17'', it is controlled so that the opening degree becomes smaller (the amount of throttling becomes larger) as the load increases. Therefore, this aperture member 22
'', the necessary throttling action can be obtained in the medium to high load range, air flow noise is reduced as in the above embodiment, and malfunction of the air flow meter due to pressure waves or pressure fluctuations is prevented. At the same time, in the low load flA region where the control valve 17 is fully open, the throttle member 22'' is also fully opened or approximately fully open, improving the relief ability.

(Effects of the Invention) As described above, according to the present invention, a control valve is provided in the bypass passage that communicates the supercharger suction side and the discharge side in the intake passage, and the load is increased by adjusting the opening degree of the control valve. In the intake system for a supercharged engine, which is configured to obtain a supercharging pressure corresponding to Therefore, when the opening degree of the control valve is small and the engine is under high load, the pressure difference between both sides of the control valve becomes small, and the flow velocity of the relief air passing through the valve is slowed down. This will prevent or reduce the generation of air flow noise caused by passing at high speed. In addition, even if a large pressure wave occurs when the opening of the control valve mentioned above suddenly changes,
This pressure wave is attenuated by the throttle portion, thereby preventing pressure fluctuations from occurring on the upstream side of the supercharger in the intake passage. As a result, when an air flow meter is installed upstream of the intake passage, the meter is prevented from malfunctioning due to the pressure fluctuation, and fuel injection control is performed based on the output signal of this air 70-meter. This will be done with high precision.

[Brief explanation of the drawing]

1 to 4 show a first embodiment of the intake device according to the present invention, FIG. 1 is a control system diagram of the intake device, FIG. 2 is a region diagram showing the control region of the control valve, and FIG. Figure 4 is a pressure distribution diagram at each part in the bypass passage showing the effect, and an explanatory diagram of the attenuation state of pressure waves. Furthermore, FIG. 5 is a block diagram of main parts showing a second example of actual droplets of the present invention, FIG. 6 is a block diagram of main parts showing a third embodiment, and FIG. 7 is a control valve and throttle member in the third embodiment. FIG. Further, FIG. 8 is a schematic diagram of an intake device shown as a conventional example. 5...Intake passage, 1o...Supercharger, 16.16'.
...Bypass passage, 17.17', 17''...control valve, 22.22', 22''...throttle member.

Claims (1)

[Claims] (1) An intake system for an engine equipped with a supercharger in an intake passage, wherein a bypass passage is provided in the intake passage to communicate the suction side and the discharge side of the supercharger, and a bypass passage is provided on the bypass passage. A supercharged engine comprising a control valve that controls the amount of air passing through a passage, and a throttle member provided between the control valve and a communication part to the suction side of the supercharger in the passage. intake device.