JPH07119529A - Intake air quantity detection device - Google Patents

Abstract

PURPOSE:To offer an intake air quantity detection device capable of measuring an accurate quantity of flow without accompanying any pressure loss with regard to a flow velocity distribution where flow deflection exists. CONSTITUTION:An intake air quantity detection device 11, which is provided inside an intake air pipe arranged with a curved portion 29 on its upper course and a throttle valve 27 arranged on its lower course, draws intake air from an inlet 22 of an L-pipe shaped detection passage 12 and discharges the intake air through a discharge outlet 23 after exposing the intake air to a heating coil resistance element 24. When the cross section of the intake air pipe is divided into quarters by a central angle of 90 deg., the inlet 22 and the discharge outlet 23 are positioned in mutually opposing 1/4 cross sections and, furthermore, the inlet 22 is positioned within the 3/4 cross section forming a central angle of 135 deg. each equally on the right and left sides centering a maximum line of curvature of the curved portion 29 of the intake piping.

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 detecting device for measuring an intake air amount to be supplied to an automobile engine, and more particularly to a heat ray intake device suitable for an electronic fuel injection type automobile engine. The present invention relates to an air amount detection device.

[0002]

2. Description of the Related Art In recent years, NOx and S contained in exhaust gas
In order to reduce Ox, an electronic fuel injection type automobile engine which measures an intake air amount and supplies an amount of fuel adapted to the intake air amount is used. Here, conventionally, the amount of intake air supplied to the automobile engine is detected by a flapper rotatably installed on a pipe about a spindle. That is, since the flapper rotates in proportion to the air flow, the intake air amount is measured by detecting the rotation angle. However, the intake air amount detecting device using the flapper needs a damper chamber for the balancer of the flapper to move in and out, which causes a problem that the volume becomes large. In order to solve this, an intake air detecting device and a heat ray type intake air amount detecting device using a Karman vortex have been put into practical use.

On the other hand, the heat ray type intake air amount detecting device measures the flow velocity of the intake air in principle and calculates the flow amount from the flow velocity. Therefore, if the flow velocity changes from the predetermined distribution in the cross section of the pipe, the accurate flow rate cannot be measured. Therefore, various proposals have heretofore been made for the purpose of making the flow velocity have a predetermined distribution. For example, a conventional hot-wire intake air amount detection device disclosed in Japanese Patent Laid-Open No. 3-179222 is shown in FIG. An L-shaped detection channel 102 is formed on the inner surface of the body 101 that also serves as a pipe. The detection channel 102 has an inlet 1 that is opened near the inner wall of the body 101 and that introduces the intake air F into the detection channel 102.
03, and an exhaust port 10 for discharging the introduced air
7 are formed. In addition, the inlet 1 of the detection channel 102
A heat ray resistance element 104 and a temperature compensation element 105 are provided so as to project from a straight line from 03. Further, upstream of the detection flow channel 102, there is formed a throttle 108 for reducing the air flow area to smooth the flow velocity unevenly. A mesh member 109 is attached to the center of the diaphragm 108.

The body 101 having the above structure was directly attached to the outlet of the air cleaner. This is because when the heat ray type intake air amount detecting device is attached to the engine, the acceleration of vibration of the engine is as large as 40 to 50 G,
This is because the control device of the hot-wire intake air amount detection device was likely to be damaged. On the other hand, since the air cleaner is attached to the body of the vehicle, the acceleration of vibration is 4 to 5 G, which is about 1/10 of that of the engine, and the detection device of the heat ray intake air amount detection device may be damaged. Is small. Also, the air cleaner has a large volume, and in general, an intake air amount detection device is attached in series with the air cleaner, and it is connected to a throttle body equipped with a throttle valve by a pipe with a right-angled bend. is doing. Therefore, the conventional intake air amount detection device is connected in series to the air cleaner, and the drift of the flow velocity of the intake air, which is a problem in Japanese Patent Laid-Open No. 3-179222, is different in the structure and the mounting method of the air cleaner. That is what is generated by.

Next, the operation of the intake air amount detecting device having the above structure will be described. Even if the flow velocity distribution of the intake air F exiting the air cleaner has a drift, the throttle 108 acts to suppress the influence of the drift that appears in the upstream on the downstream, and the mesh member 109 integrated with this throttle 108 throttles. It acts to regulate the turbulence of the air flow caused by. By the action, the flow velocity distribution of the air entering the heat ray type intake air amount detection device is adjusted, and the effect that the intake air amount can be accurately measured is exhibited. Further, the L-shaped detection flow path 102 is used, and the introduction port 103 and the exhaust port 10 are used.
7 and 7 are located at different positions in the cross section of the body 101, which is a pipe, the flow velocity of the intake air F flowing through the detection flow passage 102 is not determined only by the flow velocity at the inlet 103, but the flow velocity at the exhaust port 107. Is also affected by. Therefore, even if there is a drift, the flow velocity flowing through the detection flow channel 102 is corrected to the average flow velocity.

[0006]

However, the conventional intake air amount detecting device has the following problems. (1) The pressure loss of the intake air increases due to the action of the throttle. (2) Since the distance from the air cleaner to the engine is long, when the intake air amount detection device is attached to the air cleaner as in the conventional case, the measured intake air amount and the fuel injection amount may not match. Further, since the intake air amount detection device has one body, there is a problem that the size of the entire device increases.

The present invention has been made in order to solve the above problems, and in a flow velocity distribution in which a drift exists,
An object of the present invention is to provide an intake air amount detection device capable of measuring an accurate flow rate without pressure loss.

[0008]

In order to achieve this object, an intake air amount detecting device of the present invention is attached in an intake air pipe in which a bend portion is arranged upstream and a throttle valve is arranged downstream. The opening of one end of the L-shaped pipe-shaped detection flow path is attached at right angles to the flow of the intake air, the intake air is introduced into the detection flow path, and the intake air is applied to the heat wire stretched in the detection flow path. An intake air amount detection device for discharging the intake air from an opening formed near the other end of the detection flow path,
(1) When the cross section of the intake air pipe is divided into four equal parts with a central angle of 90 degrees, the inlet and outlet of the detection flow path are opposed to each other.
Be located in each of the four cross sections, and (2) the inlets should be evenly distributed on the left and right about the maximum curvature line of the bent portion of the suction pipe.
It is located in a 3/4 cross section forming central angles of 5 degrees.

Further, in the above intake air amount detecting device, the detection flow passage is attached to a throttle body to which the throttle valve is attached, and the throttle body is attached to an engine body. And Further, in the above-described intake air amount detection device, the distance from the bent portion arranged at the upstream side to the introduction port is within 5 times the diameter of the intake air pipe.

[0010]

Since the intake air amount detecting device of the present invention having such a structure is integrally attached to the throttle body provided with the throttle valve, when the opening degree of the throttle valve is changed by the accelerator. The change in intake air amount can be measured with high responsiveness. Therefore, the matching between the intake air amount and the fuel injection amount can be improved, and the engine can perform optimal combustion. At this time, since the detection circuit has the IC internal circuit directly attached to the board and soldered to the pattern formed on the board, it is not damaged even if the engine receives an acceleration of vibration of 40 to 50 G. . Since the intake air amount detection device is integrated with the throttle body, a bend is required in the intake air pipe immediately in front of the intake air amount detection device due to restrictions on the engine layout. Due to this curved portion, a drift of the flow velocity is generated.

The inlet of the detection channel is in a 3/4 cross section that forms a central angle of 135 degrees evenly on the left and right around the maximum curvature line, and the outlet is located in a position that is substantially point-symmetric with respect to the center. Therefore, the flow velocity flowing in the detection flow path is not affected by the drift. This is because the pressure near the discharge port acts. Therefore, the flow velocity of the intake air can be accurately measured by the heat ray resistance element for the flow velocity in the detection flow path. The temperature compensation element corrects the measurement value of the heat ray resistance element when the temperature of the intake air changes.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An intake air amount detecting device according to an embodiment of the present invention will be described below with reference to the drawings. FIG. 3 is a sectional view showing the configuration of the intake air amount detection device 11. The intake air amount detection device 11 is a device in which a hot-wire air amount measuring device is attached to a throttle body 31 to which a throttle valve 27 is attached. The mesh surface member 21 is stretched over the entire entrance of the throttle body 31. An L-shaped pipe-shaped detection channel 12 is provided downstream of the mesh face material 21. The detection channel 12 is shown in FIG. FIG. 4B is a BB sectional view of FIG. An inlet 22 is formed at one end of the detection flow passage 12 and is opened near the inner wall of the throttle body 31 to introduce intake air into the detection flow passage 12. The inlet area of the inlet 22 is spread over a predetermined area, and the amount of air passing through the inlet 22 can be calculated to calculate the amount of air supplied to the engine.

Further, the other end of the pipe of the detection flow path 12 is closed, and as shown in FIG. 4B, the exhaust air for exhausting the introduced air is discharged to the left and right side surfaces of the closed other end. An outlet 23 is formed. A hot-wire type flow meter 13 shown in FIG. 5 is attached near the inlet 22 of the detection flow path 12. That is, the heat ray resistance element 24 and the temperature compensation element 2
5 are stretched by a pair of conducting wires. The heat ray resistance element 24 and the temperature compensation element 25 are provided in the throttle body 3.
1 is connected to a detection circuit 26 attached to the outside. The throttle shaft 28 is provided below the throttle body 31.
A throttle valve 27 is attached so as to be rotatable around.

The throttle body 31 is attached such that the end surface on the side to which the throttle valve 27 is attached contacts the engine (not shown). When the throttle valve 27 controls the amount of air supplied to the engine in proportion to the amount of depression of the accelerator, the throttle body 31 may be directly attached to the engine in order to quickly transmit the change in the accelerator to the engine. Because it is necessary. Here, since the acceleration of vibration of the engine is as large as 40 to 50 G,
In the conventional detection circuit, trouble such as disconnection of bonding in the IC package has occurred. In order to prevent this, in the detection circuit 26 of this embodiment, the IC internal circuit is directly attached to the substrate without using the IC package, and is connected to the pattern formed on the substrate by soldering.

By configuring the detection circuit 26 as described above, the intake air amount detection device 11 can be integrated with the throttle body 31 and directly attached to the engine. Since the intake air amount detection device 11 is integrated with the throttle body 31 and directly attached to the engine, the piping connecting the air cleaner and the intake air amount detection device 11 is restricted by the layout of the engine room.
There is no choice but to have a bend. In many cases, a bent portion is arranged immediately before the intake air amount detection device 11. At this time, a drift caused by the bent portion flows into the intake air amount detection device 11, which is a problem. As means for solving the problem, the intake air amount detecting device 11 of the present invention
Then, the detection channel 12 is arranged as follows.

That is, as shown in FIG. 2, (1) the cross section of the bent portion 29 of the intake air pipe has a straight line A and a straight line B.
When the central angle α is 90 degrees, the inlet 22 and the outlet 23 of the detection flow path 12 are located in each of the opposing ¼ cross sections. That is, when the inlet 22 is located at (a) in FIG. 2, the outlet 23 is located at (c). In addition, (2) the inlet 22 forms a central angle of θ = 135 degrees evenly on the left and right about the maximum curvature line 29a of the bent portion 29 of the intake air pipe shown in FIGS.
It is located in four cross-section areas. In other words, the inlet 22 is
It is located in any one of the areas (a), (b), and (d) in FIG. When the inlet 22 is in (a), the outlet 23 is in the area (c),
Is in (b), the outlet 23 is in the area (d), and when the inlet 22 is in (d), the outlet 23 is in the area (b).

Next, the operation of the intake air amount detecting device 11 having the above structure will be described. The intake air F that has passed through the air cleaner passes through the bent portion 29 of the intake air pipe and passes through the mesh surface material 21. At this time, the flow velocity of the intake air F is biased as indicated by S in FIG. 1 due to the influence of the bent portion 29 of the intake air pipe. In the mesh surface material 21, fine turbulence is smoothed, but the flow velocity does not change, so that the drift flows as it is to the detection flow channel 12. Here, the operation of the detection channel 12 will be described. First, FIG. 6 shows measurement data of the intake air amount detection device 11 when the drift S shown in FIG. 1 flows through the detection flow path 12. The horizontal axis represents the flow rate of the intake air passing through the intake air amount detection device 11, and the vertical axis represents the flow rate error that occurs in the intake air amount measured by the intake air amount detection device 11.

S1 is the data when the inlet 22 is located at (a), S2 is the data when the inlet 22 is located at (b), and S4 is the data when the inlet 22 is at (d). )
It is the data in the case of. In addition, S3 is the inlet 22
Is data when is located in (c). As can be seen from this data, when the inlet 22 is located at (a), (b) or (d), the flow rate error is plus or minus 3
It was found to be within%. Further, when the inlet 22 is located at (c), the flow rate error may exceed 15%, and it has been found that the inflow air amount cannot be accurately measured. When the inlet 22 is located at (a), (b) or (d) when there is a drift shown by S in FIG. 1, the flow rate error is small because the flow velocity between the inlet 22 and the outlet 23 is small. It is thought that this is due to averaging. In addition, the inlet 22 is (C)
The reason why the flow rate error is large in the case of being located at is probably because the difference in the flow velocity is amplified.

In this embodiment, since the inlet 22 is located at (a) and the outlet 23 is located at (c),
The flow velocity of the intake air flowing into the inlet 22 is high, but the flow velocity near the outlet 23 is low and the pressure is high. Therefore, the inlet 22
The amount of intake air that flows into is reduced. Thereby, the flow velocity is averaged. In the present embodiment, the intake air amount detection device 11
Since the valve is integrated with the throttle body 31, it is necessary to dispose the bent portion 29 of the intake air pipe between the air cleaner and the intake air amount detection device 11. Here, it has been confirmed by experiments that the drift generated by the bent portion 29 of the intake air pipe is significantly present up to a distance of 5 times the diameter of the intake air pipe. Therefore, the arrangement of the detection channel 12 described above is effective when the distance between the inlet 22 and the bent portion 29 of the intake air pipe is within 5 times the diameter of the intake air pipe.

The heat ray resistance element 24 has a predetermined temperature (about 200 degrees Celsius) from the intake air temperature measured by the temperature compensation element 25.
It is controlled by the detection circuit 26 so that it becomes higher. That is, when the intake air flows into the introduction port 22, the heat ray resistance element 24 is cooled and falls below a predetermined temperature. The detection circuit 26 supplies and controls a current amount so as to keep the heat ray resistance element 24 at a predetermined temperature. This heat ray resistance element 24
The amount of current for keeping the temperature at a predetermined temperature is proportional to the flow velocity of the intake air. Therefore, the flow velocity of the intake air flowing through the detection flow path 12 can be calculated from the value of the current flowing through the heat ray resistance element 24.
Furthermore, since the cross-sectional area of the throttle body 31 is constant,
The amount of intake air is calculated by multiplying the flow velocity by the cross-sectional area.

Here, the temperature of the intake air is -30 degrees to 8 degrees.
It is expected to change in the range of 0 degree. The temperature of the intake air is measured by the temperature compensation element 25, and the flow velocity is corrected by the detection circuit 26 to remove the influence of the temperature.
The flow velocity data measured by the detection circuit 26 is sent to an engine control device that controls combustion of the engine. The engine control device supplies the engine with fuel adapted to the intake air amount. Here, when the opening degree of the throttle valve 27 changes due to the depression of the accelerator and the intake air amount changes, the intake air amount detection device 11 causes the throttle body 3 to move.
Since the throttle valve 27 is integrally attached to the No. 1 unit, the change in the intake air amount can be quickly measured.
Therefore, the matching between the intake air amount and the fuel is improved,
The amount of NOx and SOx generated can be reduced.

As described in detail above, according to the intake air amount detecting device 11 of the present embodiment, (1) when the cross section of the intake air pipe is divided into four equal parts at the central angle of 90 degrees, the detection flow path 12
The inlet 22 and the outlet 23 are located in each of the opposing ¼ cross sections, and (2) the inlet 22 is evenly distributed around the maximum curvature line 29a of the bent portion 29 of the suction pipe. Since it is located in the 3/4 cross section forming the central angle of θ = 135 degrees, that is, in the area of (a), (b) or (d) of FIG. The effect of uneven flow can be corrected, and the accurate flow rate of intake air can be measured.

Further, since the detection flow passage 12 is attached to the throttle body 31 to which the throttle valve 27 is attached, and the throttle body 31 is attached to the engine body, the change of the intake air amount by the throttle valve 27 is changed. Since the intake air amount detection device 11 can quickly measure, the intake air amount and the fuel are matched well,
The amount of NOx and SOx generated can be reduced. Here, in order to attach the detection flow passage 12 to the throttle body 31, due to the restriction of the layout of the engine room, the bent portion 29 of the intake air pipe is provided immediately before the detection flow passage 12.
Are often provided. The intake air amount detection device 11 of the present embodiment solves this problem by the above means,
The detection channel 12 can be integrated with the throttle body 31. In addition, the intake air amount detection device 11
Since the throttle body 31 is integrated with the throttle body 31, the intake air amount detection device 11 can be made compact.

Although the present invention has been described with reference to some embodiments, the present invention is not limited to the above embodiments, and various modifications and improvements can be made without departing from the spirit of the present invention. . That is, in this embodiment, the bent portion 29 of the intake air pipe is a right-angled portion, but it is the same as long as the pipe has a bent portion having an angle at which uneven flow occurs.

[0025]

As is apparent from the above description, according to the intake air amount detecting device 11 of the present invention, (1) it is detected when the cross section of the intake air pipe is divided into four equal parts at the central angle of 90 degrees. The inlet port and the outlet port of the flow path are located in each of the opposing ¼ cross sections, and (2) the inlet port is arranged 135 degrees left and right evenly around the maximum curvature line of the bent portion of the suction pipe. Since it is located within the 3/4 cross section that forms the central angle of the intake air, it is possible to correct the influence of the drift of the flow velocity generated by the curved pipe without generating pressure loss, and to obtain an accurate flow rate of the intake air. Can be measured.

Further, since the detection flow passage is attached to the throttle body to which the throttle valve is attached, and the throttle body is attached to the engine body,
Since the intake air amount detection device can quickly measure the change in the intake air amount by the throttle valve, it is possible to improve the matching between the intake air amount and the fuel and reduce the generation amounts of NOx and SOx.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a state in which an intake air amount detection device according to an embodiment of the present invention is used.

FIG. 2 is an explanatory view showing a cross section of a pipe to which a detection flow path of the intake air amount detection device is attached.

FIG. 3 is a cross-sectional view showing a configuration of an intake air amount detection device.

FIG. 4 is a cross-sectional view showing a configuration of a detection channel.

FIG. 5 is a side view showing a configuration of a hot wire type flow meter.

FIG. 6 is an experimental data diagram showing the relationship between the position of the detection channel and the flow rate.

FIG. 7 is a sectional view showing a configuration of a conventional intake air amount detection device.

[Explanation of symbols]

 11 Intake Air Quantity Detection Device 12 Detection Flow Path 13 Hot Wire Flowmeter 22 Inlet 23 Outlet 24 Heat Wire Resistance Element 25 Temperature Compensation Element 26 Detection Circuit 27 Throttle Valve 29 Bent Part of Intake Air Pipe 29a Maximum Curvature Line 29b Minimum Curvature Line 31 Throttle body

Claims (3)

[Claims] 1. An intake air pipe in which a bend is arranged upstream and a throttle valve is arranged downstream, and L is attached.
Inlet air is introduced into the detection channel by attaching the opening at one end of the detection pipe in the shape of a pipe at a right angle to the flow of the intake air.
In an intake air amount detection device which applies the intake air to a heat wire stretched in a detection flow path and discharges the intake air from an opening formed near the other end of the detection flow path, (1) the intake air pipe When the cross section of 4 is equally divided into four at a central angle of 90 degrees, the inlet and the outlet of the detection channel are located in each of the opposing ¼ cross sections, (2) the inlet is 135 around the maximum curvature line of the bent part of the suction pipe evenly
The intake air amount detecting device is located within a 3/4 cross section that forms a central angle of each degree. 2. The method according to claim 1, wherein the detection flow passage is attached to a throttle body to which the throttle valve is attached, and the throttle body is attached to an engine body. Intake air amount detection device. 3. The device according to claim 1 or 2, wherein the distance from the bent portion disposed upstream to the inlet is within 5 times the diameter of the intake air pipe. Characteristic intake air amount detection device.