JPS628363Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for highly accurately detecting the amount of intake air necessary for appropriately controlling the air-fuel ratio of the air-fuel mixture supplied to an internal combustion engine.

For example, an electronic fuel injection amount control system used as a fuel supply device for automobile gasoline engines uses an air flow sensor to control the air flow rate in order to supply a mixture with an appropriate air-fuel ratio depending on the driving conditions. The air flow rate is either directly detected or indirectly calculated based on the suction negative pressure and engine rotation speed using a suction negative pressure sensor. Also, in recent years,
A method has also been proposed in which the opening degree of the intake throttle valve is detected and the air flow rate is calculated based on the opening degree of the intake throttle valve and the engine speed (August 1978, published by Nissan Motor Co., Ltd., NISSAN Service Bulletin No. (See excerpt from No. 360 (Z-11).) However, in cases where the ratio between the minimum flow rate and the maximum flow rate of intake air is extremely large, such as in automobile engines, the accuracy of intake air amount detection is finely adjusted to cover all areas. Since it is difficult to detect air flow rate with high precision over a wide range of conditions, if an air flow sensor is used over the entire operating range, even if the detection accuracy is met in the high-speed, high-load range, there will actually be slight fluctuations. The detection accuracy of air flow rate near idling has become very poor, and conversely, if the detection accuracy is matched in the low speed and low load area, the detected amount in the high speed and high load area will be excessive, which may easily cause damage or reduce the measurement ability. If this value is exceeded, the measurement accuracy will deteriorate or the measurement ability will become too sensitive and pick up noise. For example, if the air flow sensor is a passage resistance type air flow meter, overshoot is likely to occur due to changes in excessive air flow, and if the air flow sensor is a Karman vortex type air flow meter, the Karman vortex generation frequency is extremely high, so the Karman vortex detection capability is must be made highly accurate,
In the case of a hot wire airflow meter, there is a risk of overcooling, and a structure that eliminates these disadvantages would be too expensive.

Furthermore, when the engine is provided with an exhaust gas recirculation device, the suction negative pressure varies depending on the amount of exhaust gas recirculated, so there is a drawback that it is difficult to apply a suction negative pressure sensor. On the other hand, as seen in Japanese Patent Laid-Open No. 49-58224, in which a throttle opening sensor is used, the intake air amount fluctuation with respect to the throttle valve opening near idling is extremely larger than in the high load region. If the angle changes by 1°, the amount of air passing through the throttle valve doubles, so it is necessary to use a throttle valve opening sensor with extremely high precision angle detection capability. However, since the air flow rate fluctuates widely due to the influence of the exhaust gas recirculation amount and variations in the valve clearance of the throttle valve, it is not possible to detect the intake air amount with high accuracy.

The present invention was developed in view of the above, and uses an air flow sensor installed in the primary passage to accurately detect the amount of intake air in a narrow area in the low speed and low load area, and also detects the amount of intake air in the exhaust recirculation and throttle valve. In high-speed, high-load areas where the effects of clearance variations, etc. are reduced, the intake throttle valves installed in the primary passage and secondary passage are connected via an interlocking mechanism, and the amount of intake air is determined from the opening degree of one of the intake throttle valves. Through indirect detection, the intake air amount can be detected with high precision over the entire operating range of the engine through the combination of these methods, which improves the control accuracy of the air-fuel ratio of the air-fuel mixture and improves the output characteristics of the engine and the exhaust gas. The aim is to improve characteristics, fuel consumption rate, etc.

The present invention will be described below with reference to illustrated embodiments.

1 to 3, the inside of a throttle body 5, which connects the clean side of an air cleaner 1 and a collector 4 of an intake manifold 3 provided in an engine 2, is divided into a primary passage 6 and a secondary passage 7. The primary passage 6 is equipped with a throttle valve 8 that operates in substantially the entire operating range of the engine in conjunction with an accelerator pedal (not shown), and the secondary passage 7 is equipped with a throttle valve that operates in the high-speed, high-load range of the engine. 9 will be provided.

Here, the throttle valve 8 provided in the primary passage 6 and the throttle valve 9 provided in the secondary passage 7 are interlocked via an interlocking mechanism as shown in FIG. That is, a drive lever 8b is fixed to the shaft 8a of the throttle valve 8 provided in the primary passage 6, and an operating lever 10 provided with contact parts 10a and 10b with this lever 8b is loosely attached to the shaft 8a. Further, an interlocking lever 9b is fixed to a shaft 9a of a throttle valve 9 provided in the secondary passage 7, and the interlocking lever 9b and the operating lever 10 are pivotally connected via a connecting rod 11.

Therefore, in a low speed, low load region where the throttle valve 8 of the primary passage 6 reaches a predetermined opening degree (for example, 34 degrees) from the so-called fully closed position, the primary passage 6
Only the throttle valve 8 operates. Further, when the throttle valve 8 of the primary passage 6 is opened to the predetermined opening degree or more, that is, in a high-speed, high-load region where the secondary throttle valve 9 is opened, the drive lever 8b is moved to the contact portion 1 of the operating lever 10.
Contact with 0b. Then, the operating lever 10 moves together with the drive lever 8b and operates the interlocking lever 9b via the connecting rod 11, so that the throttle valve 9 in the secondary passage 7 also begins to open.
By selecting the respective lever ratios, both throttle valves 8 and 9 are simultaneously fully opened.

Also, the shaft 8 of the throttle valve 8 provided in the primary passage 6
In a, the opening of the throttle valve 8 is detected by interlocking the potentiometer 12, which serves as a throttle valve opening sensor and whose resistance value changes according to the throttle valve opening, and also detects the acceleration state, deceleration state, etc. of the engine. It is also possible to detect idle states and full load states. Furthermore, upstream of the throttle valve 8 in the primary passage 6, a Karman vortex air flow meter 13 as an air flow sensor is provided to detect the air flow rate passing through the primary passage 6.

A control circuit 1 controls the fuel injection valves 14 provided toward each intake port of the engine 2.
The output signals from the potentiometer 12 and the air flow meter 13 are respectively input to 5, and the flow rate of fuel injected from the injection valve 14 is appropriately controlled based on these signals.

In the above configuration, in the region until the drive lever 8b operates the operating lever 10, that is, in the low speed and low load region of the engine, the throttle valve 8 of the primary passage 6
The throttle valve 9 of the secondary passage 7 is kept fully closed. Therefore, the signal from the air flow meter 13 directly represents the amount of air taken into the engine. Therefore, the control circuit 15 may use the signal from the air flow meter 13 to drive the fuel injection valve 14 so as to obtain a mixture having an appropriate air-fuel ratio. In this case, since acceleration, deceleration, and idling of the engine can be detected by the potentiometer 12 as a throttle valve opening sensor, acceleration and increase in amount may be performed based on the output signal of the potentiometer 12.

When the throttle valve 8 of the primary passage 6 is opened to the position where the drive lever 8b presses the operating lever 10, that is, when the engine reaches a high speed load region, the throttle valve 9 of the secondary passage 7 begins to open. At this time, the control circuit 15 stores the throttle opening degree at which the throttle valve 9 of the secondary passage 7 starts to open, so the throttle valve 9 of the secondary passage 7 is opened via the potentiometer 12 linked to the throttle valve 8 of the primary passage 6. It is automatically detected that the throttle valve 9 in the passage 7 begins to open, and the output of the potentiometer 12 is used to calculate the amount of air.

That is, if the opening degree of the throttle valve 8 provided in the primary passage 6 is αp, and the air flow rate detected by the air flow meter 13 is Qp, it can be calculated as a function of the suction negative pressure downstream of the throttle valve αp and Qp. . Assuming that this suction negative pressure is Δp and the opening degree of the throttle valve 9 of the secondary passage 7 is αs, the air flow rate Qs passing through the secondary passage 7 is calculated as a function of Δp and αs.

Further, since αs and αp are in a geometric positional relationship of the interlocking mechanism of both throttle valves 6 and 8, αs is determined as a function of αp. Therefore, the intake air amount of the engine (Q
= Qp + Qs) is the amount of air passing through the primary passage 6
It is given as a function of Qp and the opening degree αp of the throttle valve in the passage 6. In the embodiment, the opening degree of the throttle valve 9 in the secondary passage 7 is detected from the opening degree of the throttle valve 8 in the primary passage 6, but the opening degree of the throttle valve 9 in the secondary passage 7 can be detected directly. It may also be detected.

Furthermore, when the throttle valve 9 of the secondary passage 7 starts to open, the change in air flow rate for an opening angle of 1° is 20%.
This is very small compared to about 100% in the vicinity of conventional idle. Therefore, compared to a conventional opening sensor that detects the entire range from near idle to maximum output, the accuracy of flow rate detection is low even when using a less accurate throttle valve opening sensor. can be increased.

In addition, in the embodiment, a potentiometer is used as a throttle valve opening sensor and a Karman vortex air flow meter is used as an air flow sensor, but other types of opening sensors or other types of air flow sensors may be used. (For example, a hot wire type air flow meter) etc. may be used.

FIG. 3 shows a case where the present invention is implemented in a single point injection system. In this embodiment, a fuel injection valve 17 is provided on the riser 16 of the intake manifold gathering portion, and fuel is distributed and supplied to each cylinder through the intake manifold in the form of a spray. In this way, if the primary passage 6 and the secondary passage 7 were made vertical, the overall height would tend to increase, but in the present invention, an air flow meter 13 is provided as an air flow sensor that measures only the amount of air in the primary passage 6. Therefore, the air flow meter 13 can be made smaller. For this reason, the overall height can be reduced, which improves the mountability of the engine.

In addition, with such a single point injection system, there is a risk that fuel may adhere to the wall of the intake manifold and flow, resulting in dilution during sudden acceleration and over-concentration during sudden deceleration. Sudden acceleration detected by the degree sensor
Since the air-fuel ratio can be corrected according to the deceleration signal, the above-mentioned phenomenon can also be offset. Therefore, it is desirable that the throttle valve opening sensor is linked to the primary throttle valve.

As explained above, according to the present invention, the intake passage is divided into two systems, the primary passage and the secondary passage, and the primary passage includes a throttle valve that operates over almost the entire operating range of the engine, and a throttle valve that operates over substantially the entire operating range of the engine. An air flow rate sensor that detects the amount of air passing through the engine in a low speed, low load region where the secondary side does not operate is provided, and a throttle valve that operates in the high speed, high load region of the engine is provided in the secondary passage; With an extremely simple configuration that includes a throttle valve opening sensor that detects the opening of at least one throttle valve by interlocking the throttle valves installed in the primary passage, when only the throttle valve in the primary passage is open, the air flow The air flow rate is directly and accurately detected by the sensor, and when the throttle valve in the secondary passage opens, the air flow rate is calculated using the output of the air flow rate detection sensor and the throttle valve opening detection sensor. This is what I did. Therefore, in the low-speed, low-load range, the air flow rate range detected by the air flow sensor is narrower, which means that an air flow sensor with excellent disassembly performance can be used without fear of damage, and it also reduces fluctuations in throttle valve clearance and exhaust gas recirculation. Since the air amount can be directly detected regardless of the air flow rate, the air flow rate measurement accuracy in the relevant area is significantly improved. In addition, in the high-speed, high-load range, the change in air amount relative to the throttle valve opening becomes small, and the variation in throttle valve clearance and the fluctuation in the exhaust gas recirculation amount become relatively small. can be raised. As described above, the air amount calculation accuracy is improved over the entire operating range, and the air-fuel ratio of the air-fuel mixture supplied to the engine can be controlled with high precision.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view showing an embodiment of the present invention;
Fig. 2 is a front view showing an example of an interlocking mechanism between the throttle valve provided in the primary passage and the throttle valve provided in the secondary passage, and Fig. 3 is a schematic cross-sectional view of main parts showing another embodiment of the present invention. It is. 2... Internal combustion engine, 3... Intake manifold, 4... Collector, 5... Throttle body, 6... Primary passage, 7... Secondary passage, 8... Throttle valve, 9... Throttle valve, 12... Potentiometer (throttle valve opening sensor), 13...Air flow meter (air amount detection sensor).

Claims (1)

[Scope of Claim for Utility Model Registration] (1) A primary passageway equipped with a throttle valve that operates over substantially the entire operating range of the engine and a secondary passageway equipped with a throttle valve that operates in the high-speed, high-load range of the engine are arranged in parallel. an air flow sensor is provided upstream of the throttle valve in the primary passage, and the throttle valves in the primary passage and the secondary passage are connected via an interlocking mechanism to form an intake passage, and an air flow sensor is provided upstream of the throttle valve in the primary passage. A throttle valve opening sensor is provided to detect the opening, and the air flow rate sensor is used in low speed and low load areas, and the throttle valve opening sensor is used in high speed and high load areas to detect the air flow rate. Intake air amount detection device for internal combustion engines. (2) The throttle valve opening degree sensor is configured to detect the opening speed of the throttle valve and also issue a signal for increasing fuel acceleration. Air amount detection device.