JPH041447A - Acceleration detecting type air flow sensor - Google Patents

Abstract

PURPOSE:To detect the displacement value and direction of an air flow by composing such a signal as conformed to an air flow rate in each setup position of respective thermal elements in paying regard to a fact that the air flow in a bypass passage of an air flow rate sensor is displaced at a time when an automobile is accelerated. CONSTITUTION:An acceleration detecting type air flow sensor 21 is installed at the upstream side of an intake passage 3, leading to an internal combustion engine from an air cleaner, and a main intake passage 7 and a bypass passage 15 are branchingly formed in a casing part 6 forming a part of the intake passage 3. A throttle hole 16 is formed in this bypass passage 15, and four heating coils 17 - 20 serving as a thermal element are concentrically installed at the downstream side of this throttle hole 16. Now, when acceleration is added to a vehicle, these heating coils 18 and 20 come to the equal flow rate, but the flow rate of the heating coil 17 comes to such smaller than that of the heating coil 19. Therefore the acceleration of the vehicle and the accelerating direction are all calculable owing to the composed result of output voltages V1 - V4 out of a control circuit part 13.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention This invention relates to an air flow sensor that detects the intake air flow rate of a vehicle internal combustion engine by utilizing heat dissipation from a linear or foil-shaped heating element.

Conventional technology In automobiles, for example, a still ball position detection type acceleration sensor is used to detect the acceleration of the automobile in the vertical, horizontal, horizontal, forward, and backward directions, and based on this detected acceleration, the operation of, for example, a hydraulic actuator is controlled to improve steering stability, etc. There is a system designed to improve this.

Further, in automobiles, a bypass type hot wire type air flow sensor is known that detects the intake air flow rate of an internal combustion engine in order to perform air-fuel ratio control, ignition timing control, etc. of the internal combustion engine.

FIG. 3 is a diagram showing the configuration of the above-described bypass type hot wire air flow sensor, and FIG. 4 is a sectional view taken along the line IV--IV in FIG. 3.

In the figure, 1 is an internal combustion engine, 2 is an air cleaner, and 3 is an intake passage leading from the air cleaner 2 to the internal combustion engine 1. A throttle valve 4 is interposed in this intake passage 3.
An air flow sensor 5 is interposed on the upstream side of the throttle valve 4.

The air flow sensor 5 has a casing 6 that constitutes a part of the intake passage 3, and within the goose song 6, a main intake passage 7 and a bypass passage 8 are branched. The main intake passage 7 has a substantially circular cross section. Further, the bypass passage 8 has a substantially rectangular cross section, and is set to have a smaller cross-sectional area than the main intake passage 7.

In the center of the bypass passage 8, one heat wire 9 made of platinum wire, Ni foil, or the like is disposed as a heat-sensitive element. Reference numeral 10 denotes a control circuit section that controls the temperature of the hot wire 9 to be kept at a constant temperature and outputs an output voltage V corresponding to the flow rate 1, and this control circuit section 10 is attached to the upper surface of the casing 6.

Further, 12 is a control unit that calculates the air flow rate from the output voltage V of the control circuit section 10.

The control unit 12 utilizes, for example, a micro pump computer, and is configured to perform air-fuel ratio control, ignition timing control, etc. of the internal combustion engine 1 based on the detected air flow rate.

Problems to be Solved by the Invention By the way, in order to detect the acceleration in the vertical, horizontal, forward, and backward directions of a car using the acceleration sensor described above, it is necessary to install a large number of acceleration sensors in various parts of the car, such as the right side of the dash and the floor control. They had to be installed inside the left and right rear fenders, etc., which required a large number of parts and the installation work was troublesome.

Means for Solving the Problems Therefore, the present invention was made by focusing on the fact that when an automobile is accelerated, the air flow in the bypass passage of the air flow sensor is displaced due to its inertia I. A main intake passage that forms part of the intake passage of an internal combustion engine, a bypass passage that is branched from the main intake passage, and a throttle hole that is provided within the bypass passage and has a substantially circular cross section that forms an axial air flow. and at least three heat-sensitive elements arranged in the bypass passage on the downstream side of the throttle hole, and a control circuit unit that outputs one signal corresponding to the air flow rate at the arrangement position of each heat-sensitive element. The present invention is characterized by comprising a calculation unit that calculates the acceleration and acceleration direction of the vehicle and the intake air amount of the internal combustion engine based on the output signal from the control circuit unit.

Operation: By combining signals corresponding to the air flow rate at the positions where each heat-sensitive element is arranged, the amount and direction of displacement of the air flow can be detected. Therefore, the acceleration of the vehicle is calculated from the amount of displacement of the airflow, and the acceleration direction is calculated from the direction of displacement of the airflow. Further, the intake air amount to the internal combustion engine is calculated from the sum or average of the signals corresponding to the air flow rate at the arrangement position R/R of each heat-sensitive element.

Embodiment FIG. 1 is a diagram showing an embodiment of the acceleration detection type air flow sensor according to the present invention, and FIG.
It is a sectional view along the I line.

In the figure, 2J is an acceleration detection type air flow sensor, and this acceleration detection type air flow sensor 21 is interposed on the upstream side of the intake passage 3 leading from the air cleaner to the internal combustion engine. This acceleration detection type air flow sensor 20 is
What is the casing part 6 that forms part of the intake passage 3?A main intake passage 7 and a bypass passage 15 are provided within this casing part 6.
and are branched. This bypass guy lol! 15 is set to have a smaller cross-sectional area than the cross-sectional area of the main intake passage 7. In this bypass passage 15, a throttle hole I6 having a substantially circular cross section and a smaller cross-sectional area than the air cleaner side opening is formed on the downstream side of the air cleaner side opening. A side axial air flow is formed.

Further, in this bypass passage 15, on the downstream side of the throttle hole 16, four hot wires 17, 18, 19, 20 made of platinum wire, N+ foil, etc., which serve as heat-sensitive elements, are arranged concentrically with the throttle hole 16. has been done. As shown in FIG. 2, the hot wires I7 and I9 are vertically aligned with each other in the figure. The two heating wires 1B and 20 are arranged to face each other in the left-right direction in the figure. I3 controls the temperature of the hot wires 17 to 20 to be kept at a constant temperature, and connects each #Ill wire 17 to
The control circuit section 13 is a control circuit section that outputs output voltages V, -V4 according to the air flow rate at each arrangement location detected by the control circuit section 20, and this control circuit section 13 is attached to the upper surface of the casing 6. Further, 14 is a calculation unit that calculates the acceleration of the vehicle in one acceleration direction and the intake air flow rate to the internal combustion engine from the output voltages v1 to v4 from the control circuit 1113.

Now, in the above-described configuration, when no acceleration is applied to the vehicle, the air flow downstream of the throttle hole 16 becomes as shown by the solid arrow in FIG. becomes the flow rate. Therefore, the output voltages V, -V from the control circuit section 13.

are equal to each other. Then, in the arithmetic unit 14, it is calculated that the vehicle acceleration is zero based on the result of combining the output voltages V, ~v4, and based on the addition result or average value calculation result of the output voltages V, -V, the intake of the internal combustion engine is calculated. Air flow rate is calculated.

In addition, in Fig. 1, when acceleration is applied to the vehicle from the lower side of the figure to the upper side, the air flow downstream of the throttle hole I6 is directed downward due to the inertia of the air, as shown by the broken line arrow. become. In this case, the hot wires 18 and 20 have the same flow rate, but the flow rate of the hot wire 17 is smaller than the flow rate of the hot wire 19. Then, the control circuit section I3
The acceleration and acceleration direction of the vehicle are calculated from the result of combining the output voltages V, . Further, the intake air amount of the internal combustion engine is calculated based on the addition result or the average value calculation result of the output voltages V, ~v4.

In the same way, even if acceleration is applied in a direction other than those mentioned above, the acceleration, acceleration direction, and intake air amount can be calculated. except).

According to the example shown in FIG. 1 described above, since the acceleration detection type air flow sensor can detect the amount of intake air to the internal combustion engine as well as the acceleration and acceleration direction of the vehicle, for example, the steel ball position detection type The number of acceleration sensors attached to a vehicle can be significantly reduced.

In the above-described example in FIG. 1, the four heat wires (heat-sensitive elements) 17 to 20 are arranged concentrically with the aperture hole I6, but the three heat-sensitive elements are arranged concentrically with the aperture hole 16. You can do it like this.

Effects of the Invention As is clear from the above explanation, according to the present invention, there is a throttle hole provided in the bypass passage and having a substantially circular cross section that forms an annular air flow, and a bypass passage downstream of the throttle hole. At least three heat-sensitive elements disposed inside, a control circuit section that outputs a signal corresponding to the air flow rate at the arrangement position of each heat-sensitive element, and an output signal J from this control@tread section.
Based on this, the calculation unit calculates the acceleration and acceleration direction of the vehicle and the intake air amount of the internal combustion engine. Because it was strained, is it separate? The number of acceleration sensors installed between two vehicles can be significantly reduced.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram of the configuration showing one embodiment of the present invention, Fig. 2 is a sectional view taken along line 1 of Fig. 1, and Fig. 3 is an explanatory diagram of the configuration of a conventional hot wire type air flow sensor. , FIG. 4 is a sectional view taken along the line IV--IV in FIG. 3. 7... Main intake passage, 13... Control circuit section, 14...
- Arithmetic unit, 15... Bypass passage, 16... Throttle hole, 17-20... Heat wire, 21... Acceleration detection type air flow sensor. Fig. 1 7 Main intake passage 13-control circuit section 15/bypass passage

Claims (1)

[Claims] (1) A main intake passage that forms part of the intake passage of a vehicle internal combustion engine; A bypass passage that is branched from the main intake passage; A cross-sectional diagram provided in the bypass passage that forms an axial air flow. a circular throttle hole; at least three heat-sensitive elements disposed in the bypass passage on the downstream side of the throttle hole; and a control circuit unit that outputs a signal corresponding to the air flow rate at the position where each heat-sensitive element is disposed. An acceleration detection type air flow sensor comprising: a calculation section that calculates the acceleration and acceleration direction of the vehicle and the intake air amount of the internal combustion engine based on the output signal from the control circuit section.