WO2004113848A1 - 熱式空気流量計 - Google Patents
熱式空気流量計 Download PDFInfo
- Publication number
- WO2004113848A1 WO2004113848A1 PCT/JP2004/002906 JP2004002906W WO2004113848A1 WO 2004113848 A1 WO2004113848 A1 WO 2004113848A1 JP 2004002906 W JP2004002906 W JP 2004002906W WO 2004113848 A1 WO2004113848 A1 WO 2004113848A1
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- WIPO (PCT)
- Prior art keywords
- temperature
- substrate
- flow rate
- air flow
- air
- Prior art date
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- 239000000758 substrate Substances 0.000 claims abstract description 78
- 238000010438 heat treatment Methods 0.000 claims abstract description 48
- 238000012545 processing Methods 0.000 claims description 21
- 238000012937 correction Methods 0.000 claims description 17
- 238000002485 combustion reaction Methods 0.000 claims description 9
- 238000005259 measurement Methods 0.000 claims description 9
- 239000004065 semiconductor Substances 0.000 claims description 9
- 230000006870 function Effects 0.000 claims description 4
- 238000000059 patterning Methods 0.000 claims 1
- 238000001514 detection method Methods 0.000 description 25
- 238000004364 calculation method Methods 0.000 description 9
- 238000010586 diagram Methods 0.000 description 9
- 238000011144 upstream manufacturing Methods 0.000 description 9
- 238000000034 method Methods 0.000 description 8
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 4
- 229910052710 silicon Inorganic materials 0.000 description 4
- 239000010703 silicon Substances 0.000 description 4
- 230000007423 decrease Effects 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 230000020169 heat generation Effects 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 2
- 229910021420 polycrystalline silicon Inorganic materials 0.000 description 2
- 229920005591 polysilicon Polymers 0.000 description 2
- 230000005540 biological transmission Effects 0.000 description 1
- 238000009529 body temperature measurement Methods 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 238000005530 etching Methods 0.000 description 1
- 239000000446 fuel Substances 0.000 description 1
- 238000002347 injection Methods 0.000 description 1
- 239000007924 injection Substances 0.000 description 1
- 229910052697 platinum Inorganic materials 0.000 description 1
- 229920005989 resin Polymers 0.000 description 1
- 239000011347 resin Substances 0.000 description 1
- 230000004044 response Effects 0.000 description 1
- 229920003002 synthetic resin Polymers 0.000 description 1
- 239000000057 synthetic resin Substances 0.000 description 1
- 238000012546 transfer Methods 0.000 description 1
- 238000003466 welding Methods 0.000 description 1
Classifications
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
- G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
- G01F1/68—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by using thermal effects
- G01F1/696—Circuits therefor, e.g. constant-current flow meters
- G01F1/6965—Circuits therefor, e.g. constant-current flow meters comprising means to store calibration data for flow signal calculation or correction
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
- G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
- G01F1/68—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by using thermal effects
- G01F1/684—Structural arrangements; Mounting of elements, e.g. in relation to fluid flow
- G01F1/6842—Structural arrangements; Mounting of elements, e.g. in relation to fluid flow with means for influencing the fluid flow
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
- G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
- G01F1/68—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by using thermal effects
- G01F1/696—Circuits therefor, e.g. constant-current flow meters
Definitions
- the present invention relates to a thermal air flow meter for measuring an air flow rate, and particularly to an air flow meter suitable for measuring an intake air amount of an internal combustion engine.
- a heating resistor having a temperature dependency in an intake passage (air passage) and a resistor (temperature compensation resistor) for temperature compensation of the heating resistor are provided.
- a method of measuring the intake air flow rate by arranging them is widely known.
- This type of air flow meter controls the heating current flowing through the heating resistor so that the temperature difference between the heating resistor and the temperature compensation resistor is constant even if the heat of the heating resistor is released to the airflow.
- the air flow is measured by directly or indirectly detecting the change in the current.
- thermal air flow meter When such a thermal air flow meter is installed in an internal combustion engine such as an automobile, the heat of the engine is transmitted from the wall of the intake passage to the air flow meter due to the temperature rise of the internal combustion engine. Also, the air temperature may change while driving. In addition, there is also heat generated by the air flow meter itself, such as a drive circuit for driving the air flow meter. If such an ambient temperature change or self-heating occurs, an error occurs in the detected flow rate of the air flow meter even with the temperature compensation resistor.
- Japanese Patent Application Laid-Open No. 61-23939 discloses a method for detecting the amount of air when the temperature of the body constituting the air passage through which the air to be measured flows is different from the detected air temperature. Since it is known from experience that an error occurs, this detection error is corrected as follows. That is, a resistor for measuring air temperature is installed in the air passage, and a temperature detecting resistor for detecting the wall temperature is provided on the wall of the air passage, and the air flow fi signal is transmitted to the air passage wall surface temperature and the air temperature. Is corrected based on the difference between
- a temperature sensor for detecting an air temperature and a temperature of the substrate are detected on a substrate having a flow rate measuring element (heating resistor, temperature compensation resistor).
- a substrate temperature sensor is provided.
- the substrate of the flow measuring element has a structure supported by a support attached to the air passage wall.
- the substrate temperature sensor is provided at one end of the substrate on the support side.
- the air temperature sensor is located at the other end of the substrate (opposite the support).
- the substrate temperature sensor detects an increase in the substrate temperature due to the heat of the engine or the like being transmitted from the intake passage wall to the substrate of the flow measurement element via the support.
- the flow rate detection error is corrected based on the substrate temperature information and the air temperature information.
- a substrate temperature sensor, an air temperature sensor, and a substrate temperature sensor are formed on a substrate.
- the air flow detection value is detected from the temperature difference between the two.
- a semiconductor substrate such as silicon
- the thermal conductivity of the silicon substrate is large in the substrate material, so the supported side of the substrate and the opposite side Temperature difference with Rarely occurs. Therefore, the substrate temperature information and the air temperature information are almost always the same, and it is not possible to sufficiently detect heat from the outside such as the engine that is transmitted to the substrate, and there is a point that needs to be improved in terms of correction accuracy. .
- An object of the present invention is to solve the above-mentioned problems of the prior art, improve the flow measurement accuracy, and improve the accuracy of the air temperature detection.
- the present invention is basically configured as follows to achieve the above object.
- the flow measurement element is formed by forming a heating resistor and a temperature compensation resistor on a substrate (first substrate).
- the flow measuring element is supported by a casing that houses a drive circuit of the air flow meter, and is disposed in the air passage to be measured for flow through the casing.
- a first and a second temperature sensor for measuring temperature at two points in the air flow meter, wherein the first temperature sensor is provided on a substrate (first substrate) of the flow measurement element, and a second temperature sensor is provided inside the casing. It is provided in.
- the second temperature sensor is preferably disposed on a circuit board housed in a casing (for example, a second board on which a drive circuit of an air flow meter and a signal processing device are mounted).
- the signal processing device determines the air flow rate, which compensates for external thermal effects, based on three pieces of information, the output signal from the flow rate measurement element and the output signals from the first and second temperature sensors. It is possible to calculate (a specific example of this arithmetic expression will be described in an embodiment).
- the flow rate measuring element is supported by another component, the flow rate detection error caused by the transmission of heat from the outside can be corrected, and highly accurate air flow rate detection can be performed.
- the first and second temperature sensors are electrically connected to each other, and the second board calculates and processes at least one of the air flow rate, air temperature, air passage wall temperature, etc. Since internal processing can be performed with a flow meter, there is no need to extend the output terminal of the temperature sensor as a connection terminal for external equipment of the air flow meter. Also, the temperature sensor can be easily installed without using a structure in which the temperature sensor is buried in the wall of the air flow meter as in the related art. BRIEF DESCRIPTION OF THE FIGURES
- FIG. 1 is a cross-sectional view of a thermal air flow meter according to an embodiment of the present invention taken at right angles to an air passage
- FIG. 2 is a cross-sectional view taken along the line BB ′ in FIG. 1
- FIG. FIG. 4 is a diagram showing the appearance of the casing of the air flow meter in a cross section similar to that of FIG. 2,
- FIG. 4 is a plan view showing a flow measuring element used in the above-described embodiment
- FIG. 6 is a cross-sectional view
- FIG. 6 is a diagram showing a drive circuit of the thermal air flow meter used in the above embodiment
- FIG. 7 is a diagram showing a flow detection circuit of the thermal air flow meter used in the above embodiment
- FIG. 1 is a cross-sectional view of a thermal air flow meter according to an embodiment of the present invention taken at right angles to an air passage
- FIG. 2 is a cross-sectional view taken along the line BB ′ in FIG. 1
- FIG. 4 is
- FIG. 8 is a block diagram of a signal processing device used in the above embodiment
- FIG. 9 is a diagram showing a flow rate correction when the intake air temperature changes in the above embodiment
- FIG. FIG. 11 shows the flow rate correction when the intake passage wall surface temperature changes
- FIG. 11 shows the temperature distribution of the thermal air flow meter of the above embodiment
- FIG. 13 is a diagram showing a temperature distribution model of the thermal air flow meter of the above embodiment
- FIG. 13 is a diagram showing a flow rate correction value when the intake air temperature changes in the above embodiment
- FIG. 14 is a diagram of the above embodiment.
- Fig. 15 shows a flow rate correction value when the intake passage wall surface temperature changes
- Fig. 15 is a plan view showing another example of the measuring element used in the above embodiment
- FIG. 16 is A in Fig. 15. -A 'cross-sectional view
- Fig. 17 is a diagram showing a drive circuit of an air flow meter incorporating the flow measuring element of Fig. 15, and
- Fig. 18 is another drive circuit used in the above embodiment. The figure which shows an example. BEST MODE FOR CARRYING OUT THE INVENTION
- FIG. 1 is a cross-sectional view of a thermal air flow meter according to an embodiment of the present invention taken at right angles to an air passage
- FIG. FIG. 3 is a view showing a casing appearance of the air flow meter with a cross section similar to FIG.
- FIG. 4 is a plan view of an air flow measuring element (hereinafter, referred to as a measuring element) 1 used in the present embodiment
- FIG. 5 is a sectional view taken along line C- in FIG.
- the air flow meter is composed of a measuring element 1 and a measuring element 1 in which a heating resistor and a temperature compensating resistor, which will be described later, are formed on a substrate (first substrate) 1 O′c.
- the sub-passage (measuring passage) 4, the circuit board (second board) 14, the casing 5 for accommodating the circuit board 14, the support section 7 for supporting the casing 5, the connector section 70 and the like are arranged.
- the sub-passage 4, the casing 5, the support part 7, and the connector part 70 are integrally formed of synthetic resin.
- the intake passage (main passage) 3 through which the air to be measured flows forms a part of an intake pipe through which intake air passes to the internal combustion engine.
- the air flow meter is mounted on the cylinder 6 forming the intake passage 3 as follows.
- the body 6 has a flow meter mounting hole 60 in its passage wall, through which the auxiliary passage 4 and the casing 5 are inserted.
- the flange-shaped support portion 7 is locked to the outer surface of the air passage wall (body) 6 and is fixed by, for example, a screw.
- auxiliary passage 4 and the casing 5 are sequentially arranged in the radial direction from the wall surface of the intake passage 3 toward the center.
- the auxiliary passage 4 is supported by one end of the casing 5 and is disposed substantially at the center of the intake passage 3.
- the substrate (first substrate) 10c of the measuring element 1 is formed of a semiconductor such as silicon in this embodiment.
- a first temperature sensor 18 for detecting the temperature on the substrate 10c is formed.
- These elements are all formed by a polysilicon resistor (or platinum or the like, irrespective of the material) on the substrate 10c via the electric insulating film 10a, or the first element.
- the temperature sensor 18 may be a semiconductor device such as a thermistor.
- a cavity 9 is formed by anisotropic etching on the back surface where the heating resistor 8, the upstream resistor 16 and the downstream resistor 17 are located.
- This cavity 9 is formed from the lower surface of the substrate 10c to the boundary surface of the electric insulating film 10a '.
- the heating resistor antibody 8, the upstream resistor 16, and the downstream resistor 17 are located on the electrical insulating film 10 a in the 9 cavities.
- These resistors have temperature dependence, and the resistance characteristics change according to the temperature.
- an electrical insulating film 10b is formed on the uppermost layer of the substrate 10c in order to protect these resistance antibodies and the temperature sensor.
- the temperature compensating resistor 11a senses the air temperature and compensates so that the difference between the temperature of the heating resistor 8 and the air temperature (the temperature of the temperature compensating resistor) becomes substantially constant.
- the temperature compensation resistor 11a and the first temperature sensor 18 are formed on the electrical insulating film 10a and on the tip side of the substrate 10c (on the side opposite to the supporting portion of the measuring element 1).
- the measuring element 1 (first substrate 10c) is supported at one end of the casing 5 as shown in FIG. At one end of the supported side (casing side) on the substrate 10 c, the above-described resistors 8, 16, 17, 1 la and the terminal electrode 13 of the first humidity sensor 18 are arranged.
- the terminal electrode 13 and the terminal electrode 50 of the external circuit of the measuring element 1 (the circuit board 14 in the casing 5) are electrically connected by wire bonding.
- the first temperature sensor 1.8 is a semiconductor device such as a semiconductor device, it may be electrically connected to an external circuit by welding.
- the circuit board 14 includes a driving circuit for the air flow meter (a heating current control circuit for the heating resistor 8, for example, a circuit including bridge element resistors 19 and 20, an operational amplifier 21 and a transistor 22 shown in FIG. 6) and And a signal processing device 30.
- a driving circuit for the air flow meter a heating current control circuit for the heating resistor 8, for example, a circuit including bridge element resistors 19 and 20, an operational amplifier 21 and a transistor 22 shown in FIG. 6) and And a signal processing device 30.
- the signal processing device 30 stores the elements of the air flow detection circuit (the signal output line 33 in FIG. 7), the arithmetic unit 31 (FIG. 8) for correcting and calculating the air flow, and the flow rate correction data. And a memory 32.
- the circuit board 14 is provided with a second temperature sensor 15 for detecting the temperature on the circuit board (the temperature inside the casing).
- the second temperature sensor 15 is composed of a semiconductor device such as a thermistor.
- the first temperature sensor 18 and the second temperature sensor 15 measure the two-point temperature of the air flow meter, and therefore preferably have the same characteristics.
- a circuit board (second board) 14 and a measuring element board (first board) 10 c divided in the radial direction of the air passage 3 are separated, and these boards are used for two-point temperature measurement.
- the temperature sensors 15 and 18 can be separately arranged.
- These first and second substrates are sequentially arranged via an electrical connection.
- the flow measurement signal (detected air flow rate) Qm and the output signals Tl and ⁇ 2 of the first and second temperature sensors are all input to the signal processing device 30 of the second substrate 14 via the ⁇ / D converter ( (Fig. 8) Based on these signals, the intake air temperature (air temperature) Ta and the intake passage wall surface temperature Tw are calculated, and the air flow is corrected and calculated (corrected air flow Q'm). Note that specific examples of these calculations will be described later.
- a terminal electrode 51 for connecting to a connector terminal 71 for external connection via wire bonding is provided at one end of the circuit board (second board) 14 on the side opposite to the measuring element 1.
- Connector terminal 71 is connected to the air flow meter A power supply terminal and a terminal for outputting the above-mentioned signals Ta, Tw, and Q'm.
- the connector terminal 71 is connected to an external battery 23 (FIGS. 6 and 7) and an engine control unit (not shown).
- the air flow data Q'm is used as fuel injection amount calculation data by the engine control unit, and the air temperature Ta and the wall temperature Tw can be used for other purposes.
- the heating resistor 8 and the temperature compensating resistor 11a in FIG. 4 are elements of the bridge circuit shown in FIG.
- the resistance value of the temperature compensation resistor 1 la changes in response to the air temperature.
- the current of the heating resistor 8 is controlled by the temperature compensating resistor 11 a so that the temperature of the heating resistor 8 is always higher than the temperature of the detection target air 2 by a constant temperature.
- This bridge circuit comprises a heating resistor 8, a temperature compensating resistor 11a, fixed resistors 19, 20 and an operational amplifier 21 and a transistor 22 as driving circuits, and A battery 23 serving as a drive circuit power supply source is electrically connected.
- the heating resistor 8 and the temperature compensating resistor 11a are polysilicon resistors having a large resistance temperature coefficient.
- the potential difference between the bridge voltages 24 and 25 is fed back to the bridge circuit through the operational amplifier 21 and the transistor 22 so that the resistance ratio of the bridge is always constant.
- the temperature compensating resistor 11a By increasing the initial resistance value of the temperature compensating resistor 11a and conversely decreasing the initial resistance value of the heating resistor 8, the temperature compensating resistor 11a has a small heating value and is almost equal to the temperature of the air 2 to be detected. It becomes. On the other hand, the heating resistor 8 maybe
- the initial resistance value is reduced.
- the back surface of the heating resistor 8 is thermally insulated by a cavity 9 as shown in FIG. 5, and the resistance value increases as the temperature rises due to heat generation. Therefore, the resistance value of the heating resistor 8 increases until the resistance ratio of the bridge resistors 8, 11a, 19, and 20 becomes constant, and the heating resistor 8 becomes the temperature compensating resistor 1
- the temperature can be controlled so as to be higher than the temperature of 1a, that is, the temperature of the detected air 2 by a certain temperature.
- FIG. 7 is a circuit for detecting the flow rate of the detected air 2.
- the air flow 2 flows into the measuring element 1.
- the upstream resistor 16 and the downstream resistor 17 are cooled by the airflow 2
- the downstream resistor 17 is cooled by the heating resistor 8.
- the heated air flows and is heated. Therefore, the resistance of these two resistors changes with temperature.
- the voltage signal Qm corresponding to the temperature difference, that is, the air flow is obtained. can get.
- the arithmetic unit 31 (signal processing device 30) mounted on the circuit board 14 (FIGS. 1 and 2) includes the substrate temperature from the first temperature sensor 18. (Measurement element temperature) Tl, the temperature in the casing from the second temperature sensor 15 ⁇ 2, and the detected air flow rate Qm from the flow rate detection circuit 33 are input.
- the input signal (information) is converted from an analog signal to a digital signal by a computing unit 31 and is processed.
- the intake air temperature T a, the intake passage wall temperature T w, and the corrected air flow rate are accurately calculated.
- Q'm is calculated. These calculated signals are output to a device outside the air flow meter via the output port. A specific example of this calculation will be described later.
- the intake air temperature (detected air temperature) T a and the intake passage wall surface temperature T w are output in addition to the air flow rate Q. If necessary, only the air flow rate signal or any one of Configuration to select and output items is also possible ] Y
- An object of the present invention is to perform high-accuracy air flow detection without being affected by such a temperature change, and the details will be described below.
- Figures 9 and 10 show that the thermal air flow meter (a flow meter without a two-point temperature sensor) generated when the temperature of the air to be detected 2 or the wall temperature of the intake pipe changed in the conventional thermal air flow meter. An example of the detected flow rate error will be described.
- characteristic I shows the appropriate detected flow signal Qm-intake pipe flow Qs characteristic (standard characteristic).
- the standard characteristic I is, for example, a Qm-Qs characteristic when the wall temperature T w is 20 and the intake air temperature is 20.
- the wall temperature T w and the intake air temperature T When a suddenly changes from the normal temperature, the temperature compensation resistor 11a can no longer cope sufficiently, and a flow rate detection error occurs.
- the characteristic II in Fig. 9 is an experimental data when both the intake air temperature and the wall temperature rise from + 20 ° C to +80, and in this case, the conventional air flow rate The flow rate detected by the meter tends to generate a plus error + AQ a in the entire flow rate range. Conversely, when both the wall temperature and the intake air temperature decrease from + 20 ° C to 12Q ° C (not shown), a negative error tends to occur.
- the temperature of the intake passage wall 6 rises from + 20 ° C to + 80 ° C due to the heat of the engine, while the temperature of the intake air 2 rises by + 20 ° C. ]
- the flow rate signal Qm from the measuring element 1 in FIGS. 1, 2 and 11 the temperature information T1 from the first temperature sensor 18 installed on the measuring element 1, the second This is temperature information T 2 from the temperature sensor 15.
- FIG. 12 shows a simple temperature distribution model in the calculation method of the intake air temperature Ta and the intake passage wall surface temperature Tw.
- the longitudinal direction (radial direction of the intake passage) of the casing 5 of the air flow meter is L
- the temperature in the longitudinal direction L is T
- the temperature of the intake passage wall surface on which the casing 5 is supported is Tw.
- the constant k is a parameter for adjusting the virtual temperature distribution model to the actual temperature distribution obtained from the experimental values.
- T l (Tw-Ta) exp (k-Qm-L 1) + T a
- T 2 (Tw- T a) exp (k-Qm-L 2) + T a
- Tl is the temperature information from the first temperature sensor
- T2 is the temperature information from the second temperature sensor
- Qm is the detected flow rate from the measuring element 1. Since k is a constant and Ll and L2 are constants determined by the mounting structure, the unknowns are Tw and Ta.
- the temperature Tw of the air passage wall surface 6 and the temperature Ta of the detected air 2 are obtained.
- the detected air flow rate Qm obtained from the measuring element 1 and the flow rate detection circuit (FIG. 7) can be calculated. Correction becomes possible.
- the arithmetic unit 31 has a memory 32 therein, and has a map or a function for obtaining a corrected flow rate value corresponding to the detected air temperature T a, the intake passage wall surface temperature Tw, and the detected air flow rate Qm. It is stored as correction data.
- the correction is performed by the following equation.
- the flow rate Q'm is obtained.
- the two-point temperature of the air flow meter can be detected on an independent substrate in the heat transfer path from the wall surface of the flow meter to the intake passage, so that the reliability of the mutual temperature data is improved. be able to.
- the correction flow rate calculation based on the two-point temperature and the air flow rate detection signal and the calculations such as air temperature and wall temperature are all processed in the casing of the air flow meter. For, it is not necessary to provide the data terminal of the temperature sensor, and the output terminal ,
- the temperature sensor is installed on each substrate of the casing and the flow rate measuring element, the body of the air flow meter itself requires almost no processing for the temperature sensor, and the structure of the pod is simplified. Can be.
- the second temperature sensor 15 is provided on the circuit board 14, but it can be mounted separately from the circuit board 14 in the casing 5.
- the flow measuring element 1 may be of a type in which a film-type temperature-sensitive resistor (heating resistor, temperature-compensating resistor) is provided on an insulating substrate.
- a film-type temperature-sensitive resistor heating resistor, temperature-compensating resistor
- FIGS. 15 and 16 show an example of a direct heating current detection type flow measuring element.
- the same reference numerals as those used in the previous embodiment indicate the same or common elements.
- the upstream resistor and the downstream resistor are not used, and as shown in Fig. 17, the heating resistor 8, the temperature compensation resistor 11a, the fixed resistor 19, The intake flow rate signal Qa is obtained from the voltage between the heating resistor 8 and the resistor 19 in the 20 bridge circuit.
- the signal processing device 30 in the above embodiment can be provided outside the air flow meter separately from the drive circuit.
- the dedicated element 18 is used as the first temperature sensor for detecting the temperature Ta on the measuring element 1.However, the accuracy of the temperature compensation resistor 11a is required for the first temperature sensor. If the accuracy can be met, the temperature compensating resistor 11a can be used for the function of the first temperature sensor instead of the dedicated first temperature sensor 18.
- An example of the driving circuit in this case is shown in FIG. 1.8. This circuit example is basically the same as that shown in FIG. 6, except that the change in the resistance value of the temperature compensation resistor is obtained from the change in the voltage across the temperature compensation resistor 11a. The signal value is taken out as the air temperature (temperature on the flow rate measuring element) T a. This signal Ta is input to the signal processing device 30.
- a flow rate detection error due to a temperature change of intake air or a rise in temperature of an intake passage wall surface where the air flow meter is installed is measured. Correction can improve detection accuracy. Moreover, the detection accuracy can be improved by a simplified structure in which the temperature sensor and its terminals are not required to be embedded in the body of the air flow meter.
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Abstract
Description
Claims
Priority Applications (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP04717885A EP1637847A4 (en) | 2003-06-18 | 2004-03-05 | AIR-METER THERMAL |
US10/560,896 US7269999B2 (en) | 2003-06-18 | 2006-03-05 | Thermal airflow meter |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2003173158A JP4177183B2 (ja) | 2003-06-18 | 2003-06-18 | 熱式空気流量計 |
JP2003-173158 | 2003-06-18 |
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WO2004113848A1 true WO2004113848A1 (ja) | 2004-12-29 |
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PCT/JP2004/002906 WO2004113848A1 (ja) | 2003-06-18 | 2004-03-05 | 熱式空気流量計 |
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US (1) | US7269999B2 (ja) |
EP (1) | EP1637847A4 (ja) |
JP (1) | JP4177183B2 (ja) |
CN (1) | CN100414263C (ja) |
WO (1) | WO2004113848A1 (ja) |
Cited By (3)
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US7523659B2 (en) | 2006-05-08 | 2009-04-28 | Hitachi, Ltd. | Flow measurement apparatus |
WO2019021762A1 (ja) * | 2017-07-24 | 2019-01-31 | 株式会社デンソー | 物理量計測装置及び計測制御装置 |
JP2019023610A (ja) * | 2017-07-24 | 2019-02-14 | 株式会社デンソー | 物理量計測装置及び計測制御装置 |
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CN100408981C (zh) * | 2003-11-20 | 2008-08-06 | 株式会社日立制作所 | 热式流体流量计 |
US8291762B2 (en) * | 2004-01-15 | 2012-10-23 | Robert Akins | Work capacities testing apparatus and method |
JP4317556B2 (ja) | 2006-07-21 | 2009-08-19 | 株式会社日立製作所 | 熱式流量センサ |
US20100162809A1 (en) * | 2007-05-10 | 2010-07-01 | Acque Ingegneria S.R.L. | Flow rate sensor for water ducts and a method for measuring water flow |
JP5052275B2 (ja) * | 2007-09-20 | 2012-10-17 | アズビル株式会社 | フローセンサの取付構造 |
JP5284864B2 (ja) * | 2009-04-30 | 2013-09-11 | 日立オートモティブシステムズ株式会社 | 熱式空気流量計 |
KR101637447B1 (ko) * | 2010-01-27 | 2016-07-07 | 엘지전자 주식회사 | 의류건조기의 습도센서 및 이를 구비한 의류건조기 |
DE102010015523A1 (de) * | 2010-04-16 | 2011-10-20 | Continental Automotive Gmbh | Luftmassenmesser |
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JP5315304B2 (ja) * | 2010-07-30 | 2013-10-16 | 日立オートモティブシステムズ株式会社 | 熱式流量計 |
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JP2019023610A (ja) * | 2017-07-24 | 2019-02-14 | 株式会社デンソー | 物理量計測装置及び計測制御装置 |
Also Published As
Publication number | Publication date |
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US20070089503A1 (en) | 2007-04-26 |
EP1637847A1 (en) | 2006-03-22 |
CN1806159A (zh) | 2006-07-19 |
JP4177183B2 (ja) | 2008-11-05 |
US7269999B2 (en) | 2007-09-18 |
JP2005009965A (ja) | 2005-01-13 |
CN100414263C (zh) | 2008-08-27 |
EP1637847A4 (en) | 2007-08-29 |
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