JPH0567788B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an intake system for an engine, and particularly relates to a system that is equipped with a supercharger and a timing valve and intake flow rate detection means in the intake passage downstream of the supercharger. It is something.

(Prior Art) Conventionally, in an engine equipped with a supercharger, an intake device is known in which intake air flow rate detection means used in an electronically controlled fuel injection device is provided in an intake passage downstream of the supercharger. For example, in the device shown in Japanese Patent Application Laid-Open No. 55-156226, a supercharging passage equipped with a supercharger is provided separately from the main intake passage for naturally aspirated air, and a supercharging passage that is branched from the supercharging passage downstream of the supercharger is provided. In a device that is provided with a secondary air passage and a relief passage that relieves excess supercharging air from downstream to upstream of the supercharger, the main intake passage is provided with the first flow rate detection means, while the second flow rate detection means in the supercharging passage is A second flow rate detection means is provided further downstream from the branch point of the secondary air passage. In other words, this device increases charging efficiency by supplying supercharging air in addition to naturally aspirated air, and also uses part of the air sent from the supercharger as secondary air. By providing a second flow rate detection means downstream from the branch point,
The secondary air sent to the exhaust system is not measured, but only the air supplied to the combustion chamber of the engine is measured to ensure proper fuel control.

In addition, a timing valve for controlling the supply timing of supercharging air is installed in the intake passage downstream of the supercharger. For example, in addition to the structure shown in the above publication, the structure of There is a system in which a timing valve is provided in the supercharging passage downstream of the passage branching point, and this timing valve is opened at the end of the intake stroke to prevent supercharging air from blowing back into the main intake passage. In this structure, a second flow rate detection means may be provided in the supercharging passage between the secondary air passage branch point and the timing valve.

By the way, when a timing valve is installed downstream of a supercharger, supercharged air is supplied to the combustion chamber only during a period when both the timing valve and the intake port downstream of the timing valve are open, but outside of this period, supercharged air is supplied to the combustion chamber. However, pressure waves caused by the pulsation of the discharge pressure from the turbocharger, pressure waves generated by opening and closing of the relief valve in the relief passage, and reflected waves from the timing valve cause overload between the turbocharger and the timing valve. There are fluctuations in intake flow and pressure in the supply passage. In order to improve the accuracy of measuring the amount of intake air, it is desirable to take these points into consideration.

(Objective of the Invention) In view of the above circumstances, the present invention has been developed to measure the amount of intake air sent to the engine by detecting the intake air flow rate between the supercharger and the timing valve. An object of the present invention is to provide an engine intake device that can reliably prevent the effects of pressure fluctuations and the like outside of the period in which the intake air is supplied to the engine, and can significantly improve the accuracy of measuring the amount of intake air supplied to the engine.

(Structure of the Invention) The present invention provides an intake system for an engine in which a timing valve for opening and closing the intake passage in synchronization with the engine is provided downstream from the supercharger in an intake passage provided with a supercharger. A flow rate detection means for detecting the intake flow rate is provided in the intake passage between the feeder and the timing valve, and the output of the flow rate detection means is detected only during a period when both the timing valve and the intake port downstream thereof are open. The apparatus is provided with an intake air amount measuring means for measuring the intake air amount in the intake passage.
In other words, the intake air amount is measured only during the period when supercharging air is supplied to the engine, and pressure fluctuations and the like during other periods do not affect the measurement.

(Embodiment) Fig. 1 shows an embodiment of the device of the present invention. In this figure, 1 is an engine cylinder, and a combustion chamber 3 is formed above a piston 2 inside the cylinder. A crankshaft 4 is connected via a connecting rod. A main intake port 5, an intake port for supercharging (hereinafter referred to as supercharging port in the embodiment) 6, and an exhaust port 7 are opened in the combustion chamber 3. It is equipped with an intake valve 8, a supercharging intake valve 9, and an exhaust valve 10. The supercharging intake valve 9 is opened at the same time as the main intake valve 8 and is closed later than the main intake valve 8. And each port 5, 6, 7 above
, a main intake passage 11 for natural intake, and an intake passage for supercharging (hereinafter referred to as supercharging passage in the embodiment) 12.
and the exhaust passage 13 are connected. Upstream ends of the main intake passage 11 and the supercharging passage 12 are connected to an air cleaner 14 .

The main intake passage 11 is provided with a throttle valve 15, a first air flow meter 16 for detecting the intake air flow rate upstream of the throttle valve 15, and a fuel injection valve 17 downstream of the throttle valve 15. .

On the other hand, a supercharger 20 consisting of a positive displacement air pump or the like is provided in the supercharging passage 12, and a check ball type relief valve 21 is provided between the upstream and downstream sides of the supercharger 20. A relief passage 22 for relieving excess supercharging air is connected thereto. In addition, part of the air sent from the supercharger 20 is used as secondary air in the exhaust purification device 2 of the exhaust passage 13.
A secondary air passage 24 that supplies upstream of the turbocharger 2
The secondary air passage 24 is connected to the supercharging passage 12 downstream of the secondary air passage 24, and a secondary air control valve 25 is provided in the secondary air passage 24.

The relief passage 22 and the secondary air passage 24
A second air flow meter 26 that detects the intake air flow rate is provided in the supercharging passage 12 downstream from the connection point of the supercharging passage 12, and further downstream thereof is a supercharging air control that controls the supercharging amount according to the engine load. A valve 27 and a timing valve 28 for adjusting supercharging timing are provided. As the air flow meter 26, any conventionally known type may be used, such as one that detects the intake air flow rate based on pressure detection, one that utilizes Karman vortices, or a hot wire type. The supercharging control valve 27 is closed when the load is low and opened when the load exceeds a predetermined load. Further, the timing valve 28 is constituted by a rotary valve, and is operatively connected to the crankshaft 4 via pulleys 29, 30 and a belt 31 so as to be opened at the end of the intake stroke.

The first and second air flow meters 1
Each detection signal from 6 and 26 is transmitted to the fuel injection valve 1.
The signal is input to a control unit 35 that controls the Further, for the crankshaft 4 and the timing valve 28, a crank angle sensor 36 for detecting the crank angle and a rotation angle sensor 37 for detecting the rotation angle of the timing valve 28 are provided. A signal is also input to the control unit 35. The crank angle sensor 36 detects the crank angle corresponding to the closing timing of the supercharging intake valve 9, and the rotation angle sensor 37 detects the rotation angle corresponding to the opening timing of the timing valve 28. .

The control unit 35 connects the main intake passage 11 and the supercharging passage 12 to the combustion chamber 3, respectively, in accordance with the outputs of the air flow meters 16 and 26.
A measuring means for measuring the amount of intake air supplied to the fuel injection valve 17 and a control means for controlling the amount of fuel injected from the fuel injection valve 17 according to the measured amount of intake air. In particular, in this control unit 35, the amount of intake air in the supercharging passage 12 according to the output of the second air flow meter 26 is measured based on each detection signal from the crank angle sensor 36 and the rotation angle sensor 37, and the timing valve 28 This is performed only during the period when both the supercharging intake valve 9 and the supercharging intake valve 9 are open. In other words, for example, in the case of a 4-cylinder 4-cycle engine, as shown in _FIG . The opening/closing timing is set for each cylinder so that it is in the open state _B1 from the latter half of the opening period of the supercharging intake valve 9 until after the supercharging intake valve 9 is closed. Then, the intake air amount is measured according to the output from the second air flow meter 26 for a period _T1 from the opening timing of the timing valve 28 to the closing timing of the supercharging intake valve 9 for each cylinder. It's summery.

According to the intake device configured in this way, the amount of intake air is measured according to the outputs of both the air flow meters 16 and 26, and in this case, the second air flow meter 26 is connected to the downstream side of the connection point of the secondary air passage 24. By being provided in the supercharging passage 12, the secondary air is not measured and is actually used in the combustion chamber 3.
The amount of intake air supplied to the engine is measured, and the amount of fuel injection is controlled accordingly.

In particular, since the amount of intake air in the supercharging passage 12 is measured only during the period _T1 when both the timing valve 28 and the intake valve 9 for supercharging are open, the amount of intake air is accurately measured. In other words, from the supercharging passage 12 to the combustion chamber 3
Although supercharging air is supplied only during the above period _T1 , it can also be used during other periods, such as due to pulsations in the discharge pressure when a positive displacement air pump is used in the supercharger 20, or when the relief valve 21 Pressure fluctuations caused by the opening and closing of the timing valve 28, reflected waves from the timing valve 28, etc. act on the second air flow meter 26, and therefore the output of the second air flow meter 26 changes even when supercharged air is not being supplied to the combustion chamber 3. may change. Therefore, by not measuring the change in the output of the second air flow meter 26 during such a period in which supercharging air is not supplied, measurement errors can be reliably prevented from occurring.

FIG. 3 shows another embodiment of the device according to the invention. In this embodiment, a supercharger 120 is provided upstream of the throttle valve 115 in a single intake passage 111 communicating with the intake port 105, and between downstream and upstream of the supercharger 120 in this intake passage 111, Relief passage 12 with relief valve 121
2 is connected to the intake passage 111 downstream of these, and a pressure sensor 1 as a flow rate detection means is connected to the intake passage 111 downstream of these.
26 and a fuel injection valve 117 are provided, and a timing valve 128 is further provided downstream thereof. In the device of this embodiment, in order to reduce intake resistance and pumping loss, the timing valve 128 is closed earlier than the intake valve 108 and the intake period is controlled by the timing valve 128, so that the throttle valve 115 is closed in advance. The amount of intake air can be adjusted by increasing the opening of the valve or by omitting it.

In this device as well, the control unit 13
5 receives detection signals from the pressure sensor 126, the crank angle sensor 136, and the rotation angle sensor 137 of the timing valve 128, and measures the amount of intake air only during the period when both the timing valve 128 and the intake valve 108 are open. , the amount of fuel injected from the fuel injection valve 117 is controlled according to the measured amount of intake air. In other words, this intake system is a 4 cylinder 4
In the case of a cycle engine, as shown in Figure 4,
The intake valves 108 of each cylinder are sequentially kept in the open state A ₂ for a predetermined period, and the timing valve 128 is kept in the open state B ₂ from a time before the intake valve 108 is opened until a time in the middle of the intake valve open period. In contrast, the intake air amount measurement period T ₂ is the period from the opening timing of the intake valve 108 to the closing timing of the timing valve 128.

In the case of this embodiment as well, the amount of intake air is measured only during the period when intake air is supplied to the combustion chamber 3, and even if pressure fluctuations etc. act on the pressure sensor 126 during other periods, this is not measured accurately. This embodiment is similar to the first embodiment in that the intake air amount is detected in the second embodiment.

(Effects of the Invention) As described above, the present invention provides a method for measuring the intake air amount by the output of the flow rate detection means provided in the intake passage between the supercharger and the timing valve. The above measurement is performed only during the period when both the intake ports of the
This eliminates the influence of pressure fluctuations during periods other than the period in which supercharging air is supplied to the engine via the timing valve, making it possible to accurately measure the amount of intake air.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an embodiment of the device of the present invention;
Fig. 2 is an explanatory diagram showing the relationship between the opening/closing timing of the supercharging intake valve and timing valve and the metering period in this embodiment, Fig. 3 is a schematic diagram showing another embodiment, and Fig. 4 is this embodiment. FIG. 3 is an explanatory diagram showing the relationship between the opening/closing timing of the intake valve and the timing valve and the metering period in FIG. 12,111...Intake passage equipped with a supercharger, 2
0,120...Supercharger, 26,126...Flow rate detection means, 28,128...Timing valve, 35,135
...control unit.

Claims (1)

[Claims] 1. In an engine intake system that is provided with a timing valve that opens and closes the intake passage in synchronization with the engine, downstream from the supercharger in the intake passage equipped with a supercharger, between the turbocharger and the timing valve. A flow rate detection means for detecting the intake flow rate is provided in the intake passage, and the amount of intake air in the intake passage is measured by the output of the flow rate detection means only during a period when both the timing valve and the intake port downstream thereof are open. An intake device for an engine, characterized in that it is equipped with an intake air amount measuring means.