CN104344857A - Thermal type automobile air flow meter for realizing temperature and humidity compensation by utilizing single-chip microcomputer - Google Patents

Thermal type automobile air flow meter for realizing temperature and humidity compensation by utilizing single-chip microcomputer Download PDF

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Publication number
CN104344857A
CN104344857A CN201310348751.8A CN201310348751A CN104344857A CN 104344857 A CN104344857 A CN 104344857A CN 201310348751 A CN201310348751 A CN 201310348751A CN 104344857 A CN104344857 A CN 104344857A
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CN
China
Prior art keywords
temperature
chip microcomputer
humidity
air flow
flow meter
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Pending
Application number
CN201310348751.8A
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Chinese (zh)
Inventor
薛光明
姚喜贵
郑伟
胡大志
孔向东
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Wenzhou University Oujiang College
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Wenzhou University Oujiang College
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Publication date
Application filed by Wenzhou University Oujiang College filed Critical Wenzhou University Oujiang College
Priority to CN201310348751.8A priority Critical patent/CN104344857A/en
Publication of CN104344857A publication Critical patent/CN104344857A/en
Pending legal-status Critical Current

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Abstract

The invention provides a thermal type automobile air flow meter for realizing temperature and humidity compensation by utilizing a single-chip microcomputer. The thermal type automobile air flow meter comprises a sampling pipe and a thermal type air flow detection probe, wherein a thermal type air flow detection probe circuit comprises a hot line sensing element, a constant temperature type Whiston bridge circuit, a temperature and humidity measuring circuit, a signal acquisition circuit, the single-chip microcomputer and a DA output circuit. The single-chip microcomputer is used for acquiring the flow detection signal of the hot line sensing element and the air temperature and humidity detection signal of a temperature and humidity sensor, adopting a temperature compensation algorithm and an accuracy calibration algorithm for correction computation, and then converting a computed result into a corresponding voltage value to be outputted by a DA interface integrated by the single-chip microcomputer. Compared with the prior art, the thermal type automobile air flow meter has the benefits and advantages that hot lines with different performance parameters can be calibrated; a digital temperature and humidity sensor is adopted for temperature and humidity compensation, the compensation precision is higher, and the environmental suitability is higher; the sensor is high in output signal compatibility; the antijamming capacity is higher.

Description

Utilize the hot type automobile air flow meter of chip microcontroller temperature and humidity compensation
Technical field:
The present invention relates to a kind of hot type automobile air flow meter, particularly a kind of hot type automobile air flow meter utilizing chip microcontroller temperature and humidity compensation.
Background technology:
Automobile air flow meter is the critical component of motor car engine electric injection system, it is the Main Basis that engine electric spray system ECU decision-making distributive value exports to the measurement result of air inlet amount, and therefore the precision of its measurement result has conclusive impact to the operating mode of engine, fuel consumption and discharge amount of exhaust gas.At present, hot type automobile air flow meter is most widely used in automobile air flow meter with features such as its superior performance, simple structure, lower cost and higher reliabilities.But, because thermal air flowmeter is comparatively responsive to the change of medium temperature, and traditional hot type automobile air flow meter adopts the circuit framework based on mimic channel, discharge circuit is utilized to coordinate thermistor directly to realize temperature compensation, temperature compensation precision is not high, and cannot humidity compensate be realized, especially for the situation that current domestic hot line consistency of performance is poor, sensor can not carry out for different hot line performance index having for precision calibration, therefore may cause larger measuring error.
Summary of the invention:
Object of the present invention is just for the problems referred to above, provides a kind of hot type automobile air flow meter utilizing chip microcontroller temperature and humidity compensation.The present invention includes stopple coupon and hot type air mass flow detection probe, wherein hot type air mass flow detection probe circuit comprises hot line sensitive element, thermostatic type whiston bridge circuit, temperature and humidity measurement circuit, signal acquisition circuit, single-chip microcomputer and DA output circuit.The air flowing through hot line sensitive element will cause the change of hot line sensitive element heating current, this current change quantity becomes monotonic functional relationship with air mass flow, this current change quantity is undertaken gathering and being converted to voltage signal by thermostatic type resistance bridge signal acquisition circuit, and this signal carries out data acquisition by the A/D module of single-chip microcomputer after low-pass filtering.Meanwhile, single-chip microcomputer, by the signal of AD mouth collecting temperature sensor, obtains Current Temperatures measurement result.The software systems of single-chip microcomputer adopt digital filtering technique the sensor signal of acquisition to be processed, and import temperature compensation algorithm and carry out corrected Calculation.Correction result is converted to corresponding magnitude of voltage again and is exported by the DA interface that single-chip microcomputer is integrated, and exports to ECU after carrying out output impedance coupling by voltage follower.
The present invention compared with prior art its beneficial effect is: the present invention adopts and realizes carrying out flowmeter accuracy of detection temperature and humidity compensation with digital algorithm model based on single-chip microcomputer and digital hygro sensor, has the advantage of the following aspects compared with the hot type automobile air flow meter of conventional analog circuits framework:
1, store precision calibration parameter database in single-chip microcomputer, corresponding precision calibration can be carried out for different hot line performance index, thus greatly reduce product to the requirement of hotline component consistency of performance;
2, digital temperature-humidity sensor is adopted to carry out Temperature and Humidity, can not only detected temperatures, and humidity can be detected simultaneously, compare traditional thermistor, digital temperature-humidity sensor detection speed is faster, and accuracy of detection is higher, and data stability is better simultaneously;
3, adopt digital compensation model algorithm to carry out temperature and humidity compensation, compensation precision is higher, and environmental suitability is better;
4, sensor output signal can select the various ways such as analog output, rate-adaptive pacemaker and numeral output, and interface flexible, can adapt to the requirement of multiple ECU interface signal;
5, replace mimic channel by digital circuit, antijamming capability is stronger.
Accompanying drawing illustrates:
Fig. 1 is schematic appearance of the present invention;
Fig. 2 is flow detection sonde configuration schematic diagram of the present invention;
Fig. 3 is scheme of installation of the present invention;
Fig. 4 is flow detection of the present invention and temperature and humidity compensation principle of work block diagram.
Embodiment:
Below in conjunction with accompanying drawing, the invention will be further described
In Fig. 1 ~ 3,1 hot type air mass flow detection probe, 2 stopple coupons, 3 upper covers, 4 hot line sensitive elements, 5 metal frame, 6 probing shells, 7 thermistors, 8 O-ring seals, 9 testing circuits, 10 engine air inlet tubes, 11 digital hot type automobile air flow meters.
As seen from the figure, stopple coupon 2 is arranged on automobile engine intake tube 10 place, when the engine operates, the air that draft tube sucks enters stopple coupon 2, hot type air mass flow detection probe 1 is installed in stopple coupon 2, air enters from the air guiding flow passage bottom the probing shell 6 of hot type air mass flow detection probe 1, flows through hot line sensitive element 4, flows out from the outlet of flow-guiding channel.In the process, hot line sensitive element 4 is in heated condition, flow through the air of hot line sensitive element 4 by a part of heat with hot line sensitive element 4, and the heat taken away becomes monotonic quantity corresponding relation with MAF.Because hot line sensitive element 4 is connected on the brachium pontis of constant temperature resistance bridge, therefore, the thermal loss that air is taken away is compensated by the heating current increasing hot line sensitive element 4 automatically by by electric bridge, makes the temperature of hot line sensitive element 4 remain constant.Single-chip microcomputer can obtain the flow value of present air by the integrated AD port curent change measured on hot line sensitive element 4.Due to this process air flow amount constant when, the temperature and humidity of air itself has a certain impact to the heat taken away, and therefore needs to carry out temperature and humidity compensation.The Current Temperatures of digital temperature-humidity sensor 7 to air is installed in circuit measure, digital temperature-humidity sensor 7 is arranged on the side of circuit, isolate with hot line sensitive element 4, avoid the measurement of the temperature of hot line to the actual temperature of air to impact.The testing result of digital temperature-humidity sensor 7 pairs of aerial temperature and humidities passes through I 2c agreement is sent to single-chip microcomputer, single-chip microcomputer substitutes in model of temperature compensation algorithm after the measurement result of digital temperature-humidity sensor 7 is carried out digital filtering process and carries out temperature compensation calculating, and carry out data correction through precision calibration parameter database, finally draw the actual flow of air, and pass through the DA port output transducer detection signal of single-chip microcomputer.

Claims (4)

1. one kind utilizes the hot type automobile air flow meter of chip microcontroller temperature and humidity compensation, it is characterized in that: comprise stopple coupon and hot type air mass flow detection probe, wherein hot type air mass flow detection probe hardware circuit comprises hot line sensitive element, thermostatic type whiston bridge circuit, digital temperature-humidity sensor, signal acquisition circuit, single-chip microcomputer and DA output circuit, and software comprises temperature and humidity compensation model algorithm and hot line precision calibration parameter database and correction algorithm.
2. the hot type automobile air flow meter utilizing chip microcontroller temperature and humidity compensation according to claim 1, it is characterized in that: inner embedding Single Chip Microcomputer (SCM) system and digital hygro sensor, current changing signal and the aerial temperature and humidity signal of hot line sensitive element is gathered by single-chip microcomputer, demarcate correction algorithm by the temperature compensation mathematical modelling algorithms of single-chip microcomputer inside and hot line accuracy of detection and carry out computing, the high precision test realizing sensor exports.
3. the hot type automobile air flow meter utilizing chip microcontroller temperature and humidity compensation according to claim 1, it is characterized in that: scm software partly integrated hot line precision calibration parameter database and correction algorithm, precision consistency calibration can be carried out to the hot line of different performance parameter, thus greatly reduce the inconsistent impact on sensor accuracy of detection of hot line performance index.
4. the hot type automobile air flow meter utilizing chip microcontroller temperature and humidity compensation according to claim 1, it is characterized in that: sensor signal exports and adopts single-chip microcomputer DA port to coordinate voltage follower circuit to export, also can directly export with pulse signal form or digital signal form output, signal output impedance is large, type is enriched, compatible good, antijamming capability is strong.
CN201310348751.8A 2013-08-05 2013-08-05 Thermal type automobile air flow meter for realizing temperature and humidity compensation by utilizing single-chip microcomputer Pending CN104344857A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN201310348751.8A CN104344857A (en) 2013-08-05 2013-08-05 Thermal type automobile air flow meter for realizing temperature and humidity compensation by utilizing single-chip microcomputer

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN201310348751.8A CN104344857A (en) 2013-08-05 2013-08-05 Thermal type automobile air flow meter for realizing temperature and humidity compensation by utilizing single-chip microcomputer

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CN104344857A true CN104344857A (en) 2015-02-11

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN106288225A (en) * 2016-08-30 2017-01-04 上海高盾科技发展有限公司 The fresh-air purifying equipment of a kind of band temperature and humidity compensation controls device
CN108027265A (en) * 2015-09-30 2018-05-11 日立汽车系统株式会社 Measuring physical

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JPH07229776A (en) * 1994-02-21 1995-08-29 Hitachi Ltd Air flow rate measuring device
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JPH07229776A (en) * 1994-02-21 1995-08-29 Hitachi Ltd Air flow rate measuring device
JPH10197305A (en) * 1997-01-16 1998-07-31 Hitachi Ltd Thermal air flowmeter and measuring element for thermal air flowmeter
CN101029840A (en) * 2006-03-02 2007-09-05 黄金火 Gas flow sensor with integrated control and its integrated controlling method
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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN108027265A (en) * 2015-09-30 2018-05-11 日立汽车系统株式会社 Measuring physical
CN108027265B (en) * 2015-09-30 2020-01-14 日立汽车系统株式会社 Physical quantity detecting device
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CN106288225A (en) * 2016-08-30 2017-01-04 上海高盾科技发展有限公司 The fresh-air purifying equipment of a kind of band temperature and humidity compensation controls device

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Application publication date: 20150211

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