JP5966839B2 - Flow measuring device - Google Patents

Description

  The present invention relates to a flow rate measuring device for measuring a fluid flow rate, and relates to a technique suitable for use in a vehicle AFM (air flow meter) or the like.

The flow rate measuring device is used by being mounted on an attachment object.
Below, it demonstrates using AFM as a specific example of a flow measuring device.
The AFM is used in a state where it is mounted on an attachment object such as an air cleaner or an intake pipe.

As a means for improving the accuracy of the AFM, there is known a technique for adjusting the output of the AFM so that a predetermined sensor output is obtained by supplying a known intake air flow rate with the AFM mounted on an attachment target (for example, Patent Document 1).
Specifically, the “adjustment value after assembly (correction data for adjustment)” obtained in a state of being mounted on the attachment target is stored in an internal memory mounted on the AFM.
Then, the adjustment means mounted on the AFM corrects the unadjusted output (raw data) obtained by the flow sensor unit (detection unit) and generates an adjusted output (processed data).

(Problem 1)
When some trouble occurs in the AFM, it is necessary to specify the trouble part for the purpose of repair or improvement development.
However, in the prior art, it cannot be specified whether the defective part is in the AFM or in a different part from the AFM.

(Problem 2)
The AFM is assembled to the assembly object without adjustment. Then, “AFM characteristic error” and “characteristic change due to attachment object” overlap.
As a result, the adjustment range becomes large and fine adjustment cannot be performed, so that the AFM cannot be adjusted with high accuracy.

(Problem 3)
In the technique of Patent Document 1, an adjustment terminal for writing “adjustment value after assembly” in the internal memory of the AFM is inside the cover (a member that covers the internal part).
For this reason, it is necessary to attach the cover to the AFM after adjustment, and there is a concern that the output characteristics change before and after the cover is attached.

JP 2003-14520 A

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a flow rate measuring apparatus that can specify a defective portion and can perform high-precision adjustment when a certain problem occurs.

The flow rate measuring device of the present invention adjusts the sensor output in a state where it is mounted on an attachment object, but it also adjusts the sensor output even in a single state. Then, single data (such as “elementary data” of the single characteristic or “single adjustment value” for adjusting the raw data) when the sensor output is adjusted in the single state is stored.
For this reason, when some trouble occurs, the trouble portion can be easily identified by comparing with the stored “single data”.
Moreover, the adjustment range in the state assembled | attached to the attachment target object can be made small by adjusting a sensor output in a single-piece | unit state. As a result, fine adjustment can be performed, and a highly accurate flow rate measuring device can be provided.

It is the schematic of an engine intake system. It is sectional drawing of an air cleaner. It is principal part sectional drawing of AFM. It is the schematic of the control circuit mounted in AFM.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the invention will be described in detail with reference to the drawings.

  The examples disclosed below are specific examples of the present invention, and it goes without saying that the present invention is not limited to the examples.

[Example 1]
A first embodiment will be described with reference to FIGS.
As shown in FIG. 1, an AFM (an example of a flow rate measuring device) 1 is disposed in the middle of an intake passage 3 that guides intake air to an engine 2 for traveling a vehicle.

As a specific example, the AFM 1 of this embodiment is assembled into an air cleaner 4 as shown in FIG. 2, and is mounted at the outlet of the air cleaner 4.
The air cleaner 4 has a filter (filter element) 4c disposed between an upstream cleaner case 4a and a downstream cleaner case 4b, and the AFM 1 is assembled to an outlet duct 4d formed in the downstream cleaner case 4b. Is.

An example of the AFM 1 will be described with reference to FIGS.
The AFM 1 of this embodiment is a thermal air flow meter that measures the intake air flow (intake amount) sucked into the engine 2,
An AFM housing (passage forming member) 5 assembled to the air cleaner 4;
A flow rate sensor 6 for detecting the intake flow rate,
A control circuit 7 that converts the intake air flow detected by the flow sensor 6 into a digital signal and outputs it;
It is configured with.

The AFM housing 5 is formed of, for example, a resin material. In the AFM housing 5, a bypass passage 5a and a sub-bypass passage 5b through which a part of the intake air flowing through the outlet duct 4d of the air cleaner 4 passes are provided. It is formed.
The outlet duct 4d of the air cleaner 4 described above is formed with an AFM mounting hole penetrating inside and outside. Then, after the main part of the AFM housing 5 (portion where the bypass passages 5a and 5b are formed) is inserted and arranged in the outlet duct 4d from the outside of the AFM mounting hole, the AFM housing 5 is connected to the outlet duct 4d with a tapping screw or the like. By fixing, the AFM 1 is assembled to the air cleaner 4 and assembled.

  The flow sensor unit 6 generates a voltage signal (unadjusted output) corresponding to the intake flow rate, and may employ a chip type (substrate type), or a bobbin type resistor (single type) A resistor may be used.

The control circuit 7 is electrically connected to an ECU (abbreviation of engine control unit) 9 mounted on a vehicle part different from the AFM 1 via a connector 8 formed on the AFM housing 5.
Specifically, the connector 8 includes a resin coupler 8a and a plurality of terminal terminals 8b arranged in the coupler 8a.

  Although the configuration of the connector 8 is not limited, a specific example will be described with reference to FIG. The connector 8 shown in FIG. 3 is a so-called male connector, which is a coupler 8a formed into a female shape, and a plurality of terminal terminals 8b (in this embodiment, power supply terminals, protruding from the bottom surface of the coupler 8a into the coupler 8a). Earth terminal, flow rate output terminal, temperature output terminal).

  Further, as shown in FIG. 3, an adjustment terminal 8c for output adjustment is exposed and provided in the inner part of the coupler 8a. That is, in the completed AFM 1, the adjustment terminal 8c is provided so as to be exposed to the outside.

The control circuit 7 of this embodiment converts the “unadjusted output (voltage signal in this embodiment)” generated by the flow sensor unit 6 into a digital signal, corrects it, and outputs it to the ECU 9.
Specifically, as shown in FIG.
An A / D converter 11 that digitizes a voltage signal (analog signal) of the flow sensor unit 6;
A digital adjustment means 12 for adjusting the detection value (digitized unadjusted output) of the flow sensor unit 6 converted into a digital signal by correction;
A frequency modulation means 13 for frequency-modulating the “adjusted output” adjusted by the digital adjustment means 12;
-An internal memory 14 (EEPROM etc.) for storing various data,
It is configured with.

Next, a technique for adjusting the AFM 1 will be described.
The AFM 1 of this example is
・ `` Sensor output is adjusted in a single unit ''
・ "Sensor output is adjusted while mounted on air cleaner 4".
The adjustment value (data used for adjustment) in the single unit state is called “single adjustment value (primary adjustment value)”, and the adjustment value in the state mounted on the air cleaner 4 is “adjustment value after assembly (secondary adjustment value)”. Called.

  The “single adjustment value” and “adjustment value after assembly” in this embodiment are set at 3 or more points (specifically, 8 points, 16 points, etc.) for different flow rates. The digital adjustment unit 12 performs adjustment using linear approximation in which the set points of each adjustment value are connected by a straight line.

(Primary adjustment)
A method for adjusting the AFM 1 in a single state will be described.
First, a single AFM 1 is attached to a rectifier pipe (adjustment reference pipe) through which rectified air flows.
Then, different known intake flow rates are caused to flow through the rectifying pipe, and “elementary data (characteristic values obtained from the terminal terminal 8b)” corresponding to the different intake flow rates is obtained.

Subsequently, for each different known intake flow rate, a “single adjustment value (primary adjustment value)” used to convert “elementary data” into “specified sensor output” is obtained.
Subsequently, the “single adjustment value” obtained for each flow rate is written in the internal memory 14 using the adjustment terminal 8 c in the coupler 8 a described above.
With the above operation, the adjustment setting operation of the sensor output of the AFM 1 as a single unit is completed.

(Secondary adjustment)
Next, a method for adjusting the AFM 1 attached to the air cleaner 4 will be described.
This adjustment method is basically the same as the “primary adjustment” described above.
First, different known intake flow rates are passed through the air cleaner 4 to which the AFM 1 is attached, and “sensor output before secondary adjustment (value obtained from the terminal terminal 8b)” corresponding to the different intake flow rates is obtained.

Subsequently, for each different known intake flow rate, a “secondary adjustment value” used to convert “sensor output before secondary adjustment” to “specified sensor output” is obtained.
Subsequently, the “secondary adjustment value” obtained for each flow rate is written into the internal memory 14 using the adjustment terminal 8 c in the coupler 8 a described above, and the adjustment value in the internal memory 14 is set to “adjustment value after assembly (single adjustment”). Value + secondary adjustment value) ”.
With the above operation, the adjustment setting operation of the sensor output of the AFM 1 in a state where it is mounted on the air cleaner 4 is completed.

(Effect 1 of an Example)
The single data (“raw data” or “single adjustment value”) obtained by the above “primary adjustment” is stored for a long time in the computer of the AFM1 manufacturer (manufacturer) for each AFM1 (ie, for each serial number). Is done.
As a result, when some trouble occurs in the AFM 1 mounted on the vehicle and the AFM 1 is returned to the manufacturer, the output characteristics of the returned AFM 1 are measured, and this “measurement data” and “ It is possible to compare with “Oita single data”.

Whether or not the defective portion is not AFM 1 can be specified based on whether or not the “returned measurement data of AFM 1” and “single data stored in the manufacturer's computer” substantially match.
That is, when the “returned AFM1 measurement data” and the “single data stored in the manufacturer's computer” substantially match, the AFM1 is normal and the defective part exists in a different part from the AFM1. Can be identified. Conversely, if the “measured data of the returned AFM 1” and the “single data stored in the manufacturer's computer” do not substantially match, it is possible to specify that the defective part is the AFM 1.
As described above, by adopting this embodiment, it is possible to easily identify a defective portion that was difficult in the prior art.

(Effect 2 of Example)
The sensor output of the AFM 1 of this embodiment is adjusted before being mounted on the air cleaner 4, that is, in a single state.
As a result, when the adjustment is performed while being mounted on the air cleaner 4, since “the characteristic error of the AFM 1 itself” has already been reduced, only the “characteristic change due to the air cleaner 4” can be adjusted. As a result, the adjustment range can be reduced and fine adjustment can be performed, so that the accuracy of the AFM 1 can be increased.

(Effect 3 of Example)
In this embodiment, the “single adjustment value” or “adjustment adjustment value” for adjusting the sensor output is stored in the internal memory 14 of the AFM 1, so that the characteristic error for each individual AFM 1 is small.
For this reason, it is not necessary to mount the characteristic data for each individual of the AFM1 on the vehicle independently of the AFM1, and the cost can be suppressed.

(Effect 4 of Example)
In this embodiment, writing of “single adjustment value” and “adjustment value after assembly” is performed via an adjustment terminal 8 c provided in the coupler 8 a.
For this reason, the adjustment can be performed after the cover (the member that covers the internal parts) is attached to the AFM 1. As a result, there is no problem that the characteristics change before and after the cover is attached, and the adjustment reliability can be improved.
Even when the adjustment terminal 8c is provided outside the coupler 8a in a portion exposed after the cover is mounted, the same effect can be obtained.

(Effect 5 of Example)
In this embodiment, “flow rate-output adjustment point” for setting “single adjustment value” and “adjustment value after assembly” is set to 3 or more (specifically, 8 points, 16 points, etc.). .
Thereby, the adjustment precision of AFM1 can be raised and the high precision of AFM1 can be achieved.

  In the above embodiment, the “single data” is stored in the AFM 1 manufacturer (manufacturer), but may be stored in the internal memory 14 of the AFM 1. Specifically, “single data” may be stored in the internal memory 14 separately from “adjustment value after assembly”, and the “single data” may be provided outside the AFM 1 later.

  In the above-described embodiment, the example in which the AFM 1 is mounted on the air cleaner 4 has been shown. However, the present invention is not limited to the AFM 1 assembled into the air cleaner 4, and a passage structure (such as an intake pipe) different from the air cleaner 4. The present invention may be applied to the AFM 1 that is assembled into an assembly.

  In the above embodiment, the example in which the present invention is applied to the AFM 1 that measures the intake flow rate sucked into the engine 2 has been described. However, the present invention may be applied to a flow rate measurement device different from the measurement of the intake flow rate.

1 AFM (flow rate measuring device)
4 Air cleaner (object to be mounted)

Claims (5)

In the flow measurement device (1) in which the secondary adjustment is performed in which the sensor output is adjusted by flowing a known flow rate through the attachment object while being mounted on the attachment object (4).
This flow measuring device (1) includes a bypass passage (5a) through which a part of the fluid flowing inside the attachment object (4) passes , and is adjusted before being mounted on the attachment object (4). In a single unit state that is attached to the reference pipe, a primary adjustment for adjusting the sensor output by flowing a known flow rate through the reference pipe is performed .
The flow rate measuring apparatus according to claim 1, wherein the single data when the primary adjustment is performed is stored in an internal memory (13) of the flow rate measuring apparatus. In the flow measuring device (1) according to claim 1,
The flow rate measuring device (1) mounts the single adjustment value set for adjustment in the single unit state and the post-assembly adjustment value set for adjustment in the state mounted on the attachment object (4). The flow rate measuring device is stored in an internal memory (14). In the flow measurement device (1) according to claim 2,
The single adjustment value and the post-assembly adjustment value are written in the internal memory (14) using an adjustment terminal (8c) that can be exposed to the outside of the flow measurement device (1). apparatus. In the flow measurement device (1) according to claim 2 or claim 3,
The flow rate measuring device, wherein the single adjustment value and the post-assembly adjustment value are provided at three or more points for different flow rates. In the flow measuring device (1) according to any one of claims 1 to 4,
The flow rate measuring device (1) is an air flow meter that measures an intake flow rate sucked into a vehicle running engine (2),
The flow rate measuring apparatus according to claim 1, wherein the attachment object (4) is a passage component constituting the intake passage (3), such as an air cleaner (4) for air filtration.

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