JPH0571377A - Air flow measuring device - Google Patents

Abstract

(57) [Summary] [Structure] In the main flow path and the sub flow path provided in the intake air passage body, a heating resistor and a temperature sensitive resistor for measuring the intake air amount are arranged in the sub flow path, and Is electrically connected to the sensor unit 7. Further, the engine control unit 8 is mounted on the body as a separate member. The sensor unit 7 and the control unit 8 are the harness 10
Is electrically connected by the connector 11 via. [Effect] Since the engine control unit and the sensor unit are separate from the intake air passage body, they can be replaced individually even if one fails, improving maintainability. Moreover, the flow can be rectified by the straight pipe part in front of the detection part, and the measurement accuracy is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air flow measuring device for measuring intake air of an internal combustion engine, and more particularly to an air flow measuring device integrated with an engine control device for controlling fuel injection valves of an engine.

[0002]

2. Description of the Related Art Japanese Utility Model Laid-Open No. 57-66719 is known as a system in which an engine control device and an intake air flow rate measuring device are integrated. However, in this known example, the flow rate measuring device and the engine control device are integrally configured, and the structure is not removable.

[0003]

In the above-mentioned known example, the flow rate measuring device and the engine control device are integrally formed and mounted on the intake air passage body in a non-detachable structure. If a problem occurs in either the flow rate detection unit, the flow rate signal processing circuit, or the engine control unit, there is a problem that it is necessary to convert the entire product.

[0004]

In order to solve the above problems, the present invention provides a sensor unit including a flow rate detection unit and an engine control unit as separate members from an intake air passage body,
It was mounted near the intake air passage body with screws or the like.

[0005]

[Operation] Since the engine control unit and the sensor unit composed of the flow rate detecting unit for measuring the intake air flow rate of the engine and the detection signal processing circuit are separately mounted in close proximity to one intake air passage body, either When a problem occurs in the unit or the body, the unit or the body conductor can be removed and replaced, so that the maintainability is excellent.

[0006]

Embodiments of the present invention will be described below with reference to FIGS.

The intake air is divided into a main flow path 2 and a sub flow path 3 provided in an intake air passage body (hereinafter referred to as a passage body) 1, and a sub flow path 3 has a heating resistor for measuring the intake air amount. 4 and a temperature sensitive resistor 5 for measuring the air temperature are arranged and electrically connected to the sensor unit 7 by a terminal 6. The heating resistor 4 and the temperature-sensitive resistor 5 are, for example, a hollow ceramic bobbin wound with a platinum wire, or a platinum bobbin formed into a film shape and spirally trimmed with a laser or the like. A control current is applied to the heating resistor 4 so that the temperature difference ΔT with the temperature-sensitive resistor 5 is constant. Since this control current changes according to the amount of intake air, this amount of change in current is detected as a flow rate signal, appropriate temperature compensation and amplification are performed, and this is passed to the engine control unit 8 as an output signal.
The sensor unit 7 including the detection portion composed of the heating resistor 4 and the temperature sensitive resistor 5 and the detection signal processing circuit is a integrally molded member and is fixed to the passage body 1 with the mounting screw 9 or the like. It is installed. The engine control unit 8 is also composed of one member in the same manner, and is fixedly attached to the passage body with a mounting screw. Sensor unit 7 and engine control unit 8
Are electrically connected by a connector 11 via a harness 10. Since the sensor unit 7 and the engine control unit 8 are configured as separate members from the passage body 1, they can be replaced even if one of the units fails. The sub-flow passage 3 is provided on the main flow passage outlet side so that a straight pipe having a diameter of at least the main flow passage is provided between the sub-flow passage 3 in which the heating resistor 4 is arranged and the inlet of the main flow passage 2. Therefore, since straightening is performed by the straight pipe portion in front of the sub flow path 3, the measurement accuracy can be improved. 3 and 4 show another embodiment. The passage body 1 and the sensor unit 7 are integrally formed. A sampling tube 12 having a heating resistor 4 and a temperature sensitive resistor 5 inside is also integrally formed with the passage body 1. Others are the same as in the previous embodiment, and similar effects can be obtained. 5 and 6 show another embodiment. In this embodiment, the compact sensor unit 13 is integrated with a connector that can be directly connected to the engine control unit 8 without a harness, and has a compact structure. The other is
The same effect as the above example can be obtained.

[0008]

According to the present invention, the following effects can be expected.

1. Since the engine control unit and the sensor unit are separate from the intake air passage body, even if any of the units fails, they can be replaced individually, which improves maintainability.

2. Since the flow rate detecting section is provided on the outlet side of the intake air passage, a straight pipe section having a diameter of the main flow path or more can be secured between the inlet side and the detecting section, so that the flow can be rectified and the measurement accuracy can be improved.

[Brief description of drawings]

FIG. 1 is a sectional view of an embodiment of the present invention.

FIG. 2 is a side view of FIG.

FIG. 3 is a sectional view of another embodiment of the present invention.

FIG. 4 is a side view of FIG.

FIG. 5 is a sectional view of another embodiment of the present invention.

FIG. 6 is a side view of FIG.

[Explanation of symbols]

1 ... Intake air passage body, 2 ... Main flow passage, 3 ... Sub flow passage, 4
… Heating resistors, 5… Thermal resistors, 6… Terminals, 7…
Sensor unit, 8 ... Engine control unit, 9 ... Mounting screw, 10 ... Harness, 11 ... Connector, 12 ... Sampling tube, 13 ... Small sensor unit.

Claims (6)

[Claims] 1. An intake air passage body constituting an intake air passage of an engine, a flow rate detecting section comprising a heating resistor and a temperature sensitive resistor installed in the air passage for measuring an air flow rate of the intake air passage, and In an air flow rate measuring device composed of a sensor unit having a detection signal processing circuit, a control unit accommodating an engine control circuit for controlling a fuel injection valve and the like is attached as a separate member to the outer peripheral portion of the air passage body. An air flow rate measuring device characterized by the above. 2. The air flow measuring device according to claim 1, wherein the sensor unit and the intake air passage body are integrated or separated. 3. The air flow rate measuring device according to claim 1, wherein the flow rate detecting section of the sensor unit is provided in the air passage near the outlet side of the air passage body, and the flow rate detecting section is provided directly between the inlet of the air passage body and the flow rate detecting section. An air flow measuring device, characterized in that the pipe length is provided at least about 1 to 2 times the inner diameter of the air passage. 4. An intake air passage body which constitutes an intake passage of an engine, and a flow rate detecting section which is provided in the air passage for measuring the air flow rate of the intake air passage and comprises a heat-generating resistor and a temperature-sensitive resistor. In the air flow rate measuring device, the circuit required for air flow rate detection signal processing is also incorporated into the engine control unit device that houses the circuit for controlling the fuel injection valve, etc. An air flow measuring device characterized by being attached. 5. An air flow rate measuring device, comprising an A / D conversion circuit for a detection signal in a flow rate output part of the air flow meter according to claim 4. 6. An air flow rate measuring device comprising a signal amplifying circuit for a detection signal in a flow rate output part of the air flow meter according to claim 4.