JP3407443B2 - Air intake sensor for internal combustion engines - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an intake air amount sensor for an internal combustion engine which measures the amount of intake air flowing through an intake passage of the internal combustion engine, and particularly to intake air amount not only for forward flow but also for reverse flow. The present invention relates to an intake air amount sensor for an internal combustion engine, which can measure the amount.

[0002]

2. Description of the Related Art Conventionally, as an intake air amount sensor for an internal combustion engine, there is, for example, a device disclosed in Japanese Patent Laid-Open No. 4-105018, "Intake air amount detecting device". This device has 2
Two heat rays or heat films are arranged close to each other at a predetermined interval in the intake passage, and the flow direction is determined by the temperature difference between these two heat sensitive resistors.

[0003]

However, according to the above-mentioned conventional technique, although the flow direction can be discriminated by the temperature difference between the two thermosensitive resistors arranged at a predetermined interval, the two thermosensitive resistors are detected. It is said that there is a time lag in the measurement of the flow direction of the intake air depending on the interval, the velocity of the intake air flowing through the intake passage, and the temperature of the intake air, which causes an error in the measurement value and leads to a decrease in measurement accuracy. There was a problem.

Here, the above problems will be specifically described.
FIG. 7 shows a waveform of the intake air amount of a 4-cylinder engine which is an internal combustion engine. 7 (a) is, 800 r the engine speed of a four-cylinder engine. p. m and the throttle valve for controlling the flow rate of the intake air is fully opened, the signal waveforms of the high response thermal resistance element and the low response thermal resistance element are shown. In the figure, the solid line 801 indicates the high response thermal resistance element. The solid line 802 is the waveform measured by the thermal resistance element, and the solid line 802 is the waveform measured by the low-resistivity thermal resistance element. Further, a broken line 803 shows a signal of a true value of the estimated instantaneous intake air amount.

Further, FIG. 7 (b) shows that the engine speed of a four-cylinder engine is 1600 rpm. p. m and the throttle valve for controlling the flow rate of the intake air is fully opened, the signal waveforms of the high response thermal resistance element and the low response thermal resistance element are shown. In the figure, the solid line 804 indicates the high response. The solid line 805 is the waveform measured by the thermal resistance element, and the solid line 805 is the waveform measured by the low response thermal resistance element. Also, a broken line 806
Indicates the signal of the estimated true value of the instantaneous intake air amount.

As shown in the figure, the point at which the flow of intake air changes from the forward direction to the reverse direction according to the response of the thermal resistance element which is the flow rate detecting element, that is, the flow of the intake air changes from the forward direction to the reverse direction. The time to cross the zero flow rate that changes to is different.
For example, in the case of the low response thermal resistance element indicated by the solid lines 802 and 805, a large time delay occurs in the time when the zero flow rate is crossed. This time delay is a major factor that causes an error in the measured flow rate. On the other hand, in the case of the high-resistivity thermal resistance element shown by solid lines 801 and 804, there is little time delay in crossing the zero flow rate, and the error of the flow rate measurement value is 8
Compared with 02,805, values closer to broken lines 803,806 are shown.

The present invention has been made by paying attention to such a conventional problem, and enhances the responsiveness to the change in the flow direction of the intake air and reduces the time delay of the measurement of the flow direction of the intake air. This aims to improve the measurement accuracy.

[0008]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides an intake air amount sensor for an internal combustion engine according to claim 1, wherein the intake air amount sensor gradually increases from the inlet side of the intake passage toward the central side. A throttle passage portion having a reduced inner diameter, an enlarged passage portion having a gradually increasing inner diameter from the central portion side of the intake passage toward the outlet side, a slot portion communicating the throttle passage portion and the enlarged passage portion, and the slot. Two honeycomb rectifiers of the same shape arranged substantially symmetrically at the upstream end and the downstream end of the slot part with the central part of the part as a plane of symmetry, and at the central part of the slot part. A heater element arranged and a flow rate detection unit composed of two hot wire elements arranged on the upstream side and the downstream side so as to be symmetrical with respect to the heater element and close to the heater element. Be prepared.

Further, in the intake air amount sensor for an internal combustion engine according to a second aspect of the present invention, the heater element includes a strip-shaped elongated ceramic thin plate, a resistance film formed on the surface of the ceramic thin plate, and the ceramic thin plate. An electrode film formed on both ends of the ceramic thin plate, the flow rate detecting unit having a support for fixing the heater element and two hot wire elements, and fixing both ends of the ceramic thin plate to the support. However, the hot wire element has a structure in which the hot wire element is fixed to the support by pressure bonding in the groove portion of the through hole provided in the support.

[0010]

In the intake air amount sensor for an internal combustion engine according to the present invention (claim 1), when the intake air flows in the forward direction, it passes through the throttle passage portion whose inner diameter is gradually reduced, so that the flow velocity of the intake air is increased. To be enhanced. The intake air with the increased flow velocity is rectified by the honeycomb rectifier in the slot part, and then the flow rate is detected by the flow rate detection part including the heater element and two hot wire elements arranged in the central part of the slot part. To be done. On the other hand, when the intake air flows in the opposite direction, first, the intake air passes through the enlarged passage portion whose inner diameter is gradually enlarged from the central portion side of the intake passage toward the outlet side. Since it flows in the direction, it gradually passes through the enlarged passage part whose inner diameter is reduced. Therefore, the flow velocity of the intake air is increased even in the enlarged passage portion by the same action as in the throttle passage portion. The intake air with the increased flow velocity is rectified by the honeycomb rectifier in the slot part, and then the flow rate is detected by the flow rate detection part including the heater element and two hot wire elements arranged in the central part of the slot part. To be done. Further, since the two hot wire elements, the throttle passage portion and the enlarged passage portion are symmetrically arranged with the heater element arranged in the central portion of the slot portion as a plane of symmetry, the flow in the forward direction and the reverse direction is prevented. It is detected under the same conditions.

Further, in the intake air amount sensor for an internal combustion engine according to the present invention (claim 2), a resistance film is formed on the surface of a strip-shaped elongated ceramic thin plate, and electrode films are further formed on both ends of the ceramic thin plate. To make a heater element,
The both ends of the ceramic thin plate of the produced heater element are fixed to a support body, and the hot wire element is fixed to the support body by crimping at the groove portion of the through hole provided in the support body,
A flow rate detector is manufactured. This makes it possible to obtain a flow rate detection unit having required mechanical strength and durability and high responsiveness.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An intake air amount sensor for an internal combustion engine according to the present invention will be described below in detail with reference to the drawings.

FIG. 1A shows the entire structure of an intake air amount sensor for an internal combustion engine of the present embodiment, and FIG.
FIG. 2A is a view of the arrow as seen from the rear of the arrow. As shown in the figure, the intake passage 101 through which the intake air flows and the intake passage 10 are shown.
It is composed of two honeycomb rectifiers 102a and 102b for rectifying the intake air flowing through No. 1 and a flow rate detection unit 103 for detecting the amount of intake air flowing through the intake passage 101.

The intake passage 101 is the intake passage 101.
Throttle passage 104 whose inner diameter is gradually reduced from the inlet side to the center side of the intake passage, enlarged passage portion 105 whose inner diameter is gradually increased from the center side of the intake passage to the outlet side, and the throttle passage portion 104 And a slot portion 106 that communicates with the enlarged passage portion 105.

Further, the honeycomb rectifiers 102a, 102b
Are arranged substantially symmetrically with respect to the upstream end and the downstream end of the slot portion 106 with the central portion of the slot portion 106 as a plane of symmetry, and have the same shape.

The flow rate detecting section 103 is arranged so that a heater element 203 (see FIG. 2) described later is located at the center of the slot section 106. In other words, the flow rate detection unit 103 is arranged in the central portion of the slot unit 106, and the honeycomb rectifier 102 is symmetrical to the left and right of the flow rate detection unit 103.
a and 102b are arranged.

Further, as a detailed configuration of this embodiment, the throttle passage portion 104 has a diameter of 70 mm on the inlet side and a diameter of 50 mm on the central portion side. The diameter of the enlarged passage portion 105 is 50 mm on the central side and 70 mm on the outlet side.
And The diameter of the slot portion 106 is 50 mm. Further, the honeycomb rectifiers 102a and 102b are arranged at positions apart from the front end and the rear end of the slot 106 by about 5 mm, which is a length of 10% of the tube diameter. Further, the flow rate detection unit 103 and the honeycomb rectifiers 102a, 1
The distance between 02b is 15 mm to 20 mm.

Here, referring to FIGS. 2 (a) and 2 (b),
The configuration of the flow rate detection unit 103 will be specifically shown. Flow rate detector 1
03 is a support member 2 made of a glass / epoxy resin substrate
01, two hot wires 202a and 202b attached to the support member 201, and a ceramic heater 203 attached to the support member 201.

The supporting member 201 is provided with a groove portion 2 having a through hole for crimping the hot wires 202a and 202b.
04, a support pin 205 for fixing the ceramic heater 203 to the support member 201, and a groove portion 206 with a through hole for crimping the support pin 205.

As shown, the hot wire 202
a and 202b sandwich the ceramic heater 203,
They are arranged on the upstream side and the downstream side of the intake air flowing direction, respectively. Further, FIG. 2B is an arrow view seen from the arrow direction of FIG.

Next, the shape of the support member 201 will be described in more detail with reference to FIGS. FIG. 3B shows a cross section taken along the line AA of FIG.
A notch for arranging the ceramic heater 203 is formed in the center of 01. Further, FIG. 3C shows a cross section taken along the line BB of FIG.
4, 206 are respectively formed with holes penetrating the supporting member 201.

Subsequently, the supporting member 201 having such a shape
A method of crimping the hot wires 202a and 202b to the above will be described with reference to FIGS. 4 (a) to (d) and FIGS. 5 (a) to (d). First, as shown in FIG. 4A, the support member 201 is set so that the through-hole grooves 204 and 206 face upward, the wire clamp 402 is opened, and the wire clamp 403 is closed. That is, the wire clamp 403 holds the wire 401 and moves the wire clamp 403 to a predetermined position below the support member 201,
The tip of the wire 401 is brought to the groove portion 204 with a through hole.

Next, as shown in FIG.
With the clamp 403 and the wire clamp 402 opened, the wire 401 is allowed to have a degree of freedom, and compressed air is jetted from the bottom of the support member 201 through the compressed air from the nozzle 404 of the compressed air. Through the groove portion 204 with a through hole. At this time, the compressed air nozzle 4
No. 04 is arranged so that the injected compressed air passes through the groove portion 204 with a through hole.

Next, as shown in FIG.
The clamp 403 is moved to grip the wire 401 on the groove portion 204 with a through hole, the wire clamp 403 is moved to a predetermined position, and the tip of the wire 401 is brought to a position above the groove portion 206 with a through hole. .

Then, as shown in FIG. 4 (d), the wire clamp 403 is opened again to give the wire 401 a degree of freedom, and the compressed air nozzle 404 is opened to allow compressed air to pass through the groove portion 206. The wire 401 is jetted downward from above and the compressed air jets the wire 401 through the groove portion 20 with a through hole.
Pass from top to bottom.

As explained above, the wire 401 is
After passing through the groove portion 204 with a through hole from above, the groove portion 206 with a through hole passes from above to below, that is, the support member 2
The wire 401 passes over 01.

After passing the wire 401 over the supporting member 201, as shown in FIG. 5 (a), the end of the wire 401 is pressed against the groove portion 206 with a through hole using a pressure contactor 405 to fix the wire 401. To do.

Next, as shown in FIG. 5 (b), the tensioner 4
06 is used to pull the portion of the wire 401 below the through-hole groove portion 204. As a result, the wire 401 on the support member 201 is stretched with a preset tensile force.

Then, as shown in FIG. 5 (c), the pressure welding device 405 is used again to connect the wire 401 to the groove portion 2 with a through hole.
It is pressed against 04 and fixed.

Using the above method, two wires 401
When the supporting member 201 is pressed against the supporting member 201, the hot wires 202a and 202b are attached to the supporting member 201 as shown in FIG.
Will be installed.

FIGS. 6A to 6F are explanatory views showing the production of the ceramic heater 203. First, FIG.
As shown in (a), width 0.35 mm, thickness 1.15 m
m of alumina 601 is produced.

Next, as shown in FIG. 6 (b), platinum paste 602 is applied to the central portion of alumina 601 to a thickness of 30 μm, and is baked as shown in FIG. 6 (c) to form the resistance film 60.
2a is obtained. The resistance film 602a has a thickness of 10 to 15
μm.

Next, as shown in FIG. 6D, the silver-platinum paste 603 is applied to the end of the alumina 601 to a thickness of 50 μm.
The electrode film 6 is applied and baked as shown in FIG.
03a is obtained. The thickness of this electrode film 603a is 20 to 2
It becomes 5 μm. The alumina heater 601 having the resistance film 602a and the electrode film 603a thus formed is the ceramic heater 203 of this embodiment.

Finally, a tin-plated copper wire is soldered to the ceramic heater 203 formed by the above method as a support pin 205 for fixing to the support member 201, as shown in FIG. 6 (f).

The operation of the above configuration will be described. When the intake air flows in the intake passage 101 in the forward direction,
First, the intake air passes through the throttle passage portion 104. At this time, the pressure of the intake air gradually increases due to the throttle passage portion 104 whose inner diameter is gradually reduced.
The flow velocity of the intake air flowing from 04 to the slot 106 gradually increases. The intake air having the increased flow velocity is supplied to the honeycomb rectifier 102a at the slot 106.
After being rectified by, the flow rate is detected by the flow rate detection section 103 having the ceramic heater 203 and the two hot wires 202a and 202b arranged in the central portion of the slot section 106.

On the other hand, when the intake air flows in the reverse direction through the intake passage 101, the intake air first passes through the enlarged passage portion 105. At this time, since the intake air flows in the opposite direction in the enlarged passage portion 105, the intake air passes through the passage (enlarged passage portion 105) whose inner diameter is gradually reduced.
Since the pressure of the intake air gradually increases as in the case of passing through, the flow velocity of the intake air flowing from the enlarged passage portion 105 into the slot portion 106 gradually increases. The intake air having the increased flow velocity is rectified by the honeycomb rectifier 102b in the slot portion 106, and then the ceramic heaters 203 and 2 arranged in the central portion of the slot portion 106.
The flow rate is detected by the flow rate detection unit 103 having the individual hot wires 202a and 202b.

That is, since the two hot wire elements, the throttle passage portion and the enlarged passage portion are symmetrically arranged with the heater element arranged in the central portion of the slot portion as a plane of symmetry, the forward and reverse directions The flow rate in the flow is detected under the same conditions.

As described above, according to this embodiment, the flow velocity of the flow rate detector 103 can be made higher than that at the inlet of the intake passage 101, and the responsiveness of the flow rate detector 103 can be enhanced. Here, since the inlet diameter of the flow rate detection unit 103 is 70 mm and the diameter of the slot unit 106 is 50 mm, the flow velocity of the slot unit 106 can be double the flow velocity of the flow rate detection unit 103.

Further, in the present embodiment, the honeycomb rectifier 10
Arrangement positions of 2a and 102b are about 5 mm from the front end and the rear end of the slot 106 (10% of the pipe diameter).
Since the positions are separated, the pressure loss due to the arrangement of the rectifier can be suppressed. Further, generally, the intake air that has passed through the rectifier has a rectifying effect at a position separated by 10 mm or more from the rear end portion of the intake air flowing into the honeycomb rectifier 102a, and at a position separated by 30 mm or more, the rectifying effect gradually increases. Getting worse. Therefore, the distance of 15 mm to 20 mm from the end of the honeycomb rectifier 102b has the greatest rectification effect. In the present embodiment, since the flow rate detection unit 103 is arranged at a distance of 15 mm to 20 mm from the end of the honeycomb rectifier 102b, the flow rate can be detected at the position where the rectification effect of the intake air is maximized.

Further, since the honeycomb rectifier 102b is arranged in the slot portion 106, the vortex generated in the enlarged passage portion 103 and the disturbance of the flow velocity distribution affect the flow on the upstream side of the throttle passage portion 104, and the flow velocity distribution is disturbed. Is effective in preventing the occurrence of. In addition, when the honeycomb rectifier 102a flows in the reverse direction, the honeycomb rectifier 102a in the forward direction flows.
Works like b. Furthermore, the honeycomb rectifier 102
When the flow rate detecting unit 103 is arranged at a distance of 15 mm to 20 mm from the front end of b, the honeycomb rectifier 1
It is possible to maximize the rectification effect of 02b.

[0041]

[0042]

As described above, the intake air amount sensor for an internal combustion engine according to the present invention (claim 1) includes a throttle passage portion whose inner diameter is gradually reduced from the inlet side of the intake passage toward the central portion side. , An enlarged passage portion whose inner diameter is gradually enlarged from the central portion side of the intake passage toward the outlet side, a slot portion communicating the throttle passage portion and the enlarged passage portion, and a central portion of the slot portion as a symmetry plane. , Two honeycomb rectifiers of the same shape arranged substantially symmetrically at the upstream end and the downstream end of the slot portion, and the heater element and the heater arranged at the central portion of the slot portion The flow direction of the intake air is provided because the flow rate detection unit is provided with two hot wire elements arranged on the upstream side and the downstream side so as to be symmetric with respect to the heater element in the vicinity of the element. High responsiveness to changes in Te, reduced the time delay measurement in the flow direction of the intake air, it is possible to further improve the measurement accuracy.

Further, in the intake air amount sensor for an internal combustion engine according to the present invention (claim 2), the heater element includes a strip-shaped elongated ceramic thin plate, a resistance film formed on a surface of the ceramic thin plate, and An electrode film formed on both ends of the ceramic thin plate, and the flow rate detecting unit has a support for fixing the heater element and the two hot wire elements to each other. Since it has a structure in which it is fixed to the body by being fixed to the body by pressing the hot wire element in the groove portion of the through hole provided in the body, the hot wire element has necessary mechanical strength and durability, and A flow rate detector having high responsiveness can be obtained.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an intake air amount sensor of an internal combustion engine of the present invention.

FIG. 2 is a configuration diagram showing a flow rate detection unit of the present embodiment.

FIG. 3 is an explanatory view showing a support member.

FIG. 4 is an explanatory view showing a method of crimping a hot wire onto a support member.

FIG. 5 is an explanatory diagram showing a method of crimping a hot wire onto a support member.

FIG. 6 is an explanatory diagram showing the production of a ceramic heater.

FIG. 7 is an explanatory diagram showing a waveform of an intake air amount of a 4-cylinder engine which is an internal combustion engine.

[Explanation of symbols]

Reference Signs List 101 Intake passages 102a, 102b Honeycomb rectifiers 103, 701 Flow rate detection unit 104 Throttling passage unit 105 Enlarged passage unit 106 Slot unit 201 Support members 202a, 202b Hot wire 203 Ceramic heaters 204, 206 Through hole groove 205 Support pin 601 Alumina 602 Platinum paste 602a Resistance film 603 Silver-platinum paste 603a Electrode film

Claims (2)

(57) [Claims] 1. A throttle passage portion whose inner diameter is gradually reduced from the inlet side of the intake passage toward the central portion side, and an enlarged passage portion whose inner diameter is gradually enlarged from the central portion side of the intake passage toward the outlet side. A slot portion that connects the throttle passage portion and the enlarged passage portion, and a central portion of the slot portion as a plane of symmetry, and the slots are arranged so as to be substantially symmetrical with respect to the upstream end portion and the downstream end portion of the slot portion. Two honeycomb rectifiers of the same shape, a heater element arranged in the central portion of the slot portion, and a forward flow side and a backward flow side so as to be symmetrical with respect to the heater element close to the heater element. An intake air amount sensor for an internal combustion engine, comprising: a flow rate detection unit composed of two hot wire elements arranged at and. 2. The heater element comprises a strip-shaped elongated ceramic thin plate, a resistance film formed on the surface of the ceramic thin plate, and electrode films formed on both ends of the ceramic thin plate. The detection unit has a support for fixing the heater element and the two hot wire elements to each other. Both ends of the ceramic thin plate are fixed to the support, and the hot wire element is provided on the support. The intake air amount sensor for an internal combustion engine according to claim 1, wherein the intake air amount sensor has a structure in which it is fixed to the support body by being crimped at a groove portion of a through hole.