JPH08285651A - Air flow measuring device - Google Patents

Abstract

PURPOSE: To detect the air temperature with high accuracy by uniting an auxiliary air passage and a driving circuit module in a body, and disposing an intake air temperature detecting element in the auxiliary air passage of an air flow rate measuring device inserted in a main air passage where air supplied to an engine flows. CONSTITUTION: Intake air passes through a main air passage 1 and an auxiliary air passage 2 to be supplied to an engine. The passage 2 is integrated with a driving circuit module 3, and inserted in a body 4 for forming the passage 1. A heating resistor 5 for measuring the flow rate of intake air, a temperature sensitive resistor 6 for compensating intake air temperature and further an intake air temperature detecting element 7 are installed in the passage 2. The resistors 5, 6 are electrically connected to the driving circuit by a support pin to form the module 3. The element 7 is so constructed that a means for detecting the intake air quantity and a means for detecting the intake air temperature are separately provided not to be electrically connected by a support pin in the module 3, and the respective electric signals are input and output to and from the same connector 8.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air flow rate measuring device for detecting a flow rate of air supplied to an internal combustion engine, and more particularly to an air flow rate measuring device having a function of detecting an intake air temperature in another circuit.

[0002]

2. Description of the Related Art A conventional air flow rate measuring device is disclosed in JP-A-60-36.
As can be seen in Japanese Patent No. 916, the heating resistor for detecting the intake air flow rate and the temperature sensing resistor for compensating the intake air temperature have only the function of compensating the air temperature at the time of detecting the air flow rate. I didn't have the ability to on the other hand,
An air temperature element is indispensable for engine control of an internal combustion engine or the like, and at present, an air temperature detecting element is independently provided in an air cleaner or the like arranged upstream of the air flow rate measuring device.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to detect air temperature with high accuracy.

An object of the present invention is to purely measure only the intake air temperature with high accuracy, and the intake air temperature detecting element erroneously detects the temperature of the sensor body increased by the heat of the engine, or the heating resistor. It is necessary to prevent false detection of air containing heat that is generated.

[0005]

[Means for Solving the Problems] The following measures were taken to solve the above problems.

(1) When the heating resistor and the intake air temperature detecting element are provided in the same sub air passage, a concave portion is provided inside the sub air passage and the intake air temperature detecting element is provided therein. .

(2) A ventilation hole is provided separately from the sub air passage.

(3) The intake air temperature detecting element is installed in the ventilation hole having a high cooling effect, and the throttle and the cooling plate are further provided at the entrance of the ventilation hole.

[0009]

The present invention can improve the assembling workability by integrating the intake air temperature detecting element and the drive circuit module of the air flow rate measuring device, and the heating resistor can be provided in the same sub air passage. The structure can be simplified by providing the intake air temperature detecting element together.

Further, since the holder and the sub air passage constituting member can be cooled as a whole, the temperature difference between the intake air and the holder and the sub air passage constituting member can be reduced, and the intake air temperature detection accuracy can be improved.

[0011]

Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a plan view showing an embodiment of the present invention.

The intake air is supplied to the engine through the main air passage 1 and the sub air passage 2. The sub air passage 2 is integrated with the drive circuit module 3 and is inserted into the body 4 forming the main air passage 1. In the sub air passage 2, a heating resistor 5 for measuring the flow rate of the intake air, a temperature sensitive resistor 6 for compensating the intake air temperature, and an intake air temperature detecting element 7 for detecting the intake air temperature are installed. The heat generating resistor 5 and the temperature sensitive resistor 6 are electrically connected to the drive circuit by the support pins to form the drive circuit module 3. An electric current is applied to the heating resistor 5 by this drive circuit in order to heat it to a constant temperature. The heating temperature maintains a constant difference between the heating resistor 5 and the intake air temperature regardless of the amount of intake air, and the intake air temperature is corrected by the temperature sensitive resistor 6. That is, when a high flow rate flows through the air passage, a large current flows through the heating resistor 5, and when a low flow rate flows, a small current flows to maintain a constant temperature. There is a monotonically increasing function relationship between the current flowing through the heating resistor 5 and the air flow rate, and the air flow rate is detected by this. Further, the intake air temperature detecting element 7 is provided with a means for detecting the intake air amount by a support pin and a means for detecting the intake air temperature separately so as not to be electrically connected in the drive circuit module 3, and each of them is provided separately. It has a structure for inputting and outputting an electric signal from the same connector 8.

FIG. 2 is a sectional view of FIG. 1 showing an embodiment of the present invention. The intake air temperature detecting element 7 is integrally formed with a holder 9 that constitutes the drive circuit module 3, and is inserted into the body 4 together with the sub air passage 2. At this time, the body 4 and the holder 9 are sealed by the O-ring 10. As described above, by integrating the intake air temperature detecting element 7 with the drive circuit module 3, the degree of freedom of the mounting position is increased, the detachability is facilitated, and the maintainability in the market is improved. Further, the wiring resistance can be reduced by directly connecting to the connector portion, and the air temperature can be detected with high accuracy.

FIG. 3 is a sectional view showing a second embodiment of the present invention. The holder 9 which is a mounting portion of the intake air temperature detecting element 7 installed in the sub air passage 2 and the sub passage constituent member 1
1 is provided with a recess, and the intake air temperature detecting element 7 is installed in the recess. As a result, when the intake air temperature detecting element 7 is installed in the downstream portion of the heat generating resistor 5 because it is separated from the mainstream portion of the sub air passage 2, it is possible to avoid the heat effect of the heat generating resistor 5. The air temperature can be detected with accuracy.

FIG. 4 is a plan view showing a third embodiment of the present invention. A ventilation hole 12 is provided which penetrates the holder 9 and the sub-passage forming member 11. As a result, the temperatures of the holder 9 and the sub-passage forming member 11 can be lowered to suppress the temperature difference from the intake air temperature, and the air temperature can be detected with high accuracy.

FIG. 5 is a sectional view showing a fourth embodiment of the present invention. A vent hole 12 penetrating the holder 9 and the sub-passage forming member 11 is provided, and the intake air temperature detecting element 7 is installed in the vent hole 12. As a result, the intake air temperature detecting element 7 is installed in the portion of the holder 9 and the sub-passage forming member 11 where the cooling effect is high, so that the structure can be made less susceptible to the wall surface temperature.

FIG. 6 is a sectional view showing a fifth embodiment of the present invention. A ventilation hole 12 penetrating the holder 9 and the sub-passage forming member 11 is provided, and a throttle 13 is provided at an inlet portion of the ventilation hole 12. As a result, the flow velocity of the air flowing through the ventilation hole 12 can be increased, and since the intake air temperature detecting element 7 is installed in a portion having a higher cooling effect, the structure can be made less susceptible to the wall surface temperature.

FIG. 7 is a sectional view showing a sixth embodiment of the present invention. The holder 9 and the sub-passage forming member 11 are provided with a vent hole 12 penetrating therethrough, and the sub-passage forming member 11 is also provided with a plurality of heat radiation plates 14 for cooling. Thereby, the sub-passage forming member 1
The cooling effect of No. 1 can be further improved, and since the intake air temperature detecting element 7 is installed in a portion having a higher cooling effect, the structure can be made less susceptible to the wall surface temperature.

[0019]

According to the present invention, it is possible to provide an air flow rate measuring device with high accuracy in detecting the intake air temperature.

[Brief description of drawings]

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

FIG. 2 is a sectional view of FIG.

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

FIG. 4 is a side view showing a third embodiment of the present invention.

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

FIG. 6 is a sectional view showing a fifth embodiment of the present invention.

FIG. 7 is a sectional view showing a sixth embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Main air passage, 2 ... Sub air passage, 3 ... Drive circuit module, 5 ... Heating resistor, 6 ... Temperature sensitive resistor, 7 ... Intake air temperature detecting element, 8 ... Connector, 10 ... O ring, 11
... Sub passage constituent member.

Claims (6)

[Claims] 1. A main air passage in which an auxiliary air passage having therein a heating resistor for measuring an air flow rate and a temperature sensitive resistor for measuring an air temperature is integrated with a drive circuit module so that air supplied to an internal combustion engine flows. An air flow measuring device inserted into the air flow measuring device, wherein an intake air temperature detecting element is installed in the sub air passage. 2. The air flow measuring device according to claim 1, wherein a concave portion is provided in a portion where the intake air temperature detecting element is arranged, and the intake air temperature detecting element is arranged in the concave portion. 3. The air flow rate measuring device according to claim 1, wherein a ventilation hole is opened in the holder and the sub air passage constituting member separately from the sub air passage. 4. The air flow rate measurement according to claim 1, wherein an intake air temperature detection passage is opened in the holder and the sub air passage constituent member separately from the sub air passage, and the intake air temperature detecting element is installed. apparatus. 5. The air flow rate measuring device according to claim 4, wherein a throttle is provided at the inlet of the intake air temperature detection passage. 6. The air flow measuring device according to claim 5, wherein the sub air passage constituting member is provided with a plurality of cooling heat radiating plates.