RU2474792C1 - Method of diagnosing car mass air flow sensors and apparatus for realising said method - Google Patents

Abstract

FIELD: physics.

SUBSTANCE: stand for testing sensors has a mount on which a fan with an electric heater is mounted. The fan is connected to a throttling unit through a tapered and a ridged pipe. A post which is attached to the mount is fitted with a measuring device, having trim drags for adjusting sensitivity, and a switch. The measuring device is connected through electric connectors to the reference and tested sensors. There is a measuring scale on the throttling unit. Diagnosis is carried out as follows: the reference and tested sensors are placed on the stand while connecting the tested sensor to a bridge circuit. The fan blows air through both sensors while measuring flow rate using a throttling valve. Relative estimation of voltage from the reference and tested sensors is carried out while ensuring smooth opening of the throttling valve. The difference between signals from the reference and tested sensors is obtained without preliminary calculations. The technical state of the tested sensor is determined from the obtained difference.

EFFECT: shorter duration of testing, high reliability of estimating the technical state of tested sensors.

3 cl, 3 dwg, 1 tbl

Description

The invention relates to the field of operation of machines and can be used in the diagnosis of mass air flow sensors (DMRV) of vehicles equipped with a microprocessor control system of an internal combustion engine (ICE).

A known method for diagnosing DMRV using a digital multimeter (A. Tranter. Automobile Electrical Equipment Manual. St. Petersburg, CJSC Alfamer Publishing, 1998), when implemented, measures voltage, current, resistance at the terminals of the connector of a working mass flow sensor air.

Significant disadvantages of the method are the low reliability and accuracy of the measurement, the limited validation of the DMRV in different modes.

There is a method of checking the MT-4 motor tester with the KRP-4M prefix (MT-4 diagnostic motor-tester program. KRP-4M prefix. User manual. Samara: NPP "New technological systems", 2002), when implemented, to the diagnostic connector the vehicle is connected to the diagnostic connector and programmed by the fault codes, as well as by the changes in the signals from the sensor determine its technical condition.

The disadvantages of the method are the high cost of the stand, the difficulty of localization of individual malfunctions.

There is a known method of checking with a DST-2 device (GAZ cars with an engine ZM3-4062.10 Maintenance manual for a MIKAS engine control system 5.4 M. Legion Avtodata, 1999), which consists in connecting a DST-2 device connector to a DMRV. They start the engine, create diagnostic modes, and by changing the voltage parameters they judge the mass flow rate of air, on the basis of which the technical state of the air flow meter is evaluated.

The disadvantages of this method are the high cost of the device, the inability to localize individual malfunctions, the limited testing of the DMRV in different modes.

Adopted as a prototype method (Technical conditions DMRV: TU 37.473.017-99) is used when checking the technical condition of the DMRV. The method consists in monitoring the technical condition of the DMRV on a special stand. At the same time, establish a reference and test DMRV, turn on the fan, create a stream of air that passes through the sensors in series. Change the flow rate using the throttle. Checking the electrical parameters of the sensor is carried out at a temperature of (23 ± 5) ° C at the stand. Measure the output voltage of the sensor at the control values of the mass air flow indicated in the table. A sensor is considered to have passed the test if its electrical parameters comply with the technical requirements.

However, this method also has a number of disadvantages: a significant verification time, a significant time for evaluating the technical state of the DMRV, low reliability and accuracy of the verification.

The closest to the claimed stand (Technical conditions DMRV: TU 37.473.017-99) in terms of essential features is the well-known stand for testing mass air flow sensors adopted as a prototype, which contains a frame with a fan attached to it with an electric motor connected by a transitional and corrugated nozzles with a throttle assembly; pipe clamps; reference and test sensors; measuring device and power supply. Measurements of the output voltage of the tested DMRV sensor are carried out with a voltmeter, and an air flow meter is also installed to measure the amount of passing air.

The stand has a number of disadvantages: the presence of only one voltmeter does not allow reliable and accurate assessment of the technical state of the DMRV, and the accuracy of the test significantly depends on the ambient temperature, and the set temperature is not always possible to provide, the presence of an air flow meter makes the stand more expensive, in general, when using of this stand, the time for evaluating the technical state of the air flow sensor is significantly longer.

The aim of the invention is to reduce the duration of the test time of the sensor DMRV, increasing the reliability and accuracy of the assessment of the technical condition of the sensors DMRV.

This goal is achieved by the fact that in the proposed method for diagnosing automobile air mass flow sensors, which consists in monitoring the technical condition of automobile air mass flow sensors on the bench while installing a reference and test sensors, supplying fan air flow through the sensors in series, changing the flow rate using a throttle dampers, while the tested sensors are connected in a bridge circuit and carry out a relative assessment of voltages from the reference and of the tested sensors, smoothly ensuring the opening of the throttle, receive the difference of the signals of the reference and the tested sensors without preliminary calculations, which determine the technical condition of the tested sensor.

The technical result from the use of a new method for testing DMRV sensors is that connecting the tested sensors in a bridge circuit allows a relative assessment of voltages from the reference and tested sensors, the need to compare the obtained measurement results with tabular ones has disappeared. in the developed method, the relative diagnostic parameters are monitored (the difference between the readings of the reference and tested sensors in volts). Checking the electrical parameters of the sensor is independent of the ambient temperature. Since the claimed method monitors the relative diagnostic parameters (the difference between the readings of the reference and tested sensors in volts), preliminary calculations are not required. The resulting voltage difference between the reference and tested sensors allows you to quickly and with high reliability determine the technical condition of the tested sensor.

To implement the proposed method, a bench for testing mass air flow sensors is used, comprising a bed with a fan fixed to it with an electric motor connected by a transitional and corrugated pipe to a throttle assembly; pipe clamps; reference and test sensors; measuring device; Power Supply; unlike the prototype, the measuring device is mounted on a rack and contains balancing resistances and resistances for adjusting sensitivity, a switch and is connected by electrical connectors to the reference and test sensors; a throttle unit has a measuring scale.

At the stand, the measuring scale has divisions from 0 to 90 ° with a division value of 10 °.

The technical result from the use of a new test bench for DMRV sensors is that balancing resistances allow you to set the voltmeter zero readings before starting the test, using resistances to adjust the sensitivity of the voltmeter and switch allows you to change the sensitivity of the voltmeter scale from 1 to 5 volts. Connection with electrical connectors to the reference and test sensors allows the measurement of the difference in voltage of the sensors, as well as significantly reduce the time of testing the DMRV. The measuring scale on the throttle unit allows you to perform the specified test modes DMRV, and dividing from 0 to 90 ° with a division value of 10 allow loading to be performed with a given accuracy.

According to the information available to the authors, the new set of features, both in the method and in the test bench for sensors of mass air flow, which allows to reduce the time of the diagnosis process, to increase the accuracy and reliability of diagnosis, is not known from the prior art, which proves the technical solution meets the criterion "Novelty" and the criterion of "inventive step".

Figure 1 presents the stand for testing sensors of mass air flow.

Figure 2 presents the electrical circuit of the measuring device.

The test bench for sensors of mass air flow (figure 1) consists of a frame 1, which is the basis of the stand for testing mass air flow sensors. A fan 2 is mounted on the bed 1 with an electric motor 3 by means of an arm 4. A fan adapter 5 is attached to the fan 2 with screws. The adapter pipe 5 of the fan is connected by means of the corrugated pipe 6 of the fan to the throttle assembly 7. All pipes are attached using clamps of 8 pipes (of which there are 6 in total). The throttle assembly 7 is mounted on the strut 9 and fixed to the bed 1. The throttle assembly 7 has a measuring scale 10. The throttle assembly 7 is connected via a corrugated pipe 11 to the reference DMRV 12. The reference DMRV 12 is mounted on the strut 13, which is attached to the frame 1. The reference DMRV 12 is connected to the test DMRV 14 by means of the corrugated pipe 15. The corrugated pipe 15 is attached to the reference DMRV 12 and the tested DMRV 14 with clamps of 8 pipes. The test DMRV 14 is mounted on a rack 16, which is screwed to the bed 1. To the reference DMRV 12, a wiring harness 18 from the measuring device 19 is connected using an electrical connector 17. To the test DMRV 14 is connected using an electrical connector 20 a wiring harness 21 from the measuring device 19 The measuring device 19 is mounted on a stand 22, which is attached to the bed 1. The measuring device 19 is connected via wires to the power supply 23. The standard sensors DMRV 12 and the subject 14 also through electrical ue connectors 17 and 20 are connected with the power supply 23.

The measuring device 19 is a module, the bridge circuit of which is shown in figure 2, which consists of electrical connectors 17 and 20, a power supply 23. The electrical connector 17 is connected to a reference sensor DMRV 12. On the electrical connector 17 there are conclusions 1 ₁ , 2 ₁ , 3 ₁ , 5 ₁ . 1 ₁ - mass; 2 ₁ - mass; 3 ₁ - signal from the sensor "+", V; 5 ₁ - power supply of the sensor + 12 ... 15 V. The electrical connector 20 is connected to the tested sensor DMRV 14. On the electrical connector 20 there are conclusions 1 ₂ , 2 ₂ , Z ₂ , 5 ₂ . 1 ₂ - mass; 2 ₂ - mass; 3 ₂ - signal from the sensor "+", V; 5 ₂ - sensor supply + 12 ... 15 V. The bridge circuit contains resistances 24 and 25, as well as balancing resistances 26, 27. Resistance 28, 29 are also installed to adjust the sensitivity of the voltmeter, switch 30, voltmeter 31.

Resistances 28 and 29 for adjusting the sensitivity are selected based on the maximum current passing through the voltmeter, which is 100 μA.

According to Ohm's law, resistance is determined by the formula:

where U is the maximum voltage value, V;

I is the current passing through the voltmeter, μA.

At a maximum sensitivity of a voltmeter scale of 5 V, the resistance is determined by the formula:

At a maximum sensitivity of a voltmeter scale of 1 V, the resistance is determined by the formula:

The stand works as follows.

The test sensor DMRV 14 (Fig. 1) is mounted on the rack 16. Put on the test sensor DMRV 14 a corrugated pipe 15 and fasten it with a clamp 8. To the test DMRV 14 is connected using an electrical connector 20 a wiring harness 21 from the measuring device 19. Heated for 10 minutes power supply 23. The stand is ready to go.

Then, on the power supply 23, the power switch is turned on and the voltmeter 31 is monitored. If the sensitivity of the voltmeter 31 is required during measurements, then the resistance 29 is connected in series with the switch 30, if resistance is required, then the resistance 28 is connected in series with the switch 30. If the arrow of the voltmeter 31 the absence of air flow deviates from zero, then set by adjusting the balancing resistances 26, 27 its zero value.

The method using the inventive stand is as follows.

The electric motor 3 of the fan 2 is turned on. The fan 2 supplies the air flow sequentially through the throttle assembly 7, the reference DMRV 12 and the tested DMRV 14.

Then they begin to change the air flow rate using the throttle of the throttle assembly 7. When changing the air flow velocity passing through the DMRV sensors connected via a bridge circuit, the voltmeter 31 should show a zero value over the entire range of air flow changes. At the request of TU 37.473.017-99, the sensor is considered serviceable with a difference in voltmeter 31 readings.

For new sensors:

at idle (mass air flow Q = 41.31 kg / h) 0.15 V;

in nominal mode (mass air flow Q = 402.05 kg / h) 0.35 V.

For sensors after 3000 hours of operation:

at idle (mass air flow Q = 41.31 kg / h) 0.21 V;

in nominal mode (mass air flow Q = 402.05 kg / h) 0.51 V.

A relative assessment of the voltages from the reference and test sensors is carried out, smoothly ensuring the opening of the throttle, the difference between the signals of the reference and test sensors is obtained without preliminary calculations, which determine the technical condition of the test sensor.

Next, operational tests of the test bench were carried out to check the mass air flow sensors, on which eleven DMRV sensors were installed, the test results of the mass air flow sensors are presented in table 1.

The sensor tests showed that seven sensors from the total sample are faulty. According to the test results built figure 3 the dependence of the output voltage of the sensor from the angle of rotation of the throttle: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 - numbers of the tested sensors.

Thus, providing testing of sensors at the developed stand and using the developed method, a significant reduction in the time of testing of the sensors of the air flow sensor and assessing their technical condition is achieved. This development made it possible to eliminate the use of an expensive air mass meter. In addition, the need to compare the obtained measurement results with tabular ones has disappeared. in the developed method, the relative diagnostic parameters are monitored (the difference between the readings of the reference and tested sensors in volts). Checking the electrical parameters of the sensor is independent of the ambient temperature, as the relative diagnostic parameters are evaluated (the difference between the readings of the reference and tested sensors in volts).

The technical result consists in reducing the time of testing sensors, increasing the accuracy and reliability of testing sensors DMRV.

Claims (3)

1. A method for diagnosing automobile air mass flow sensors, which consists in monitoring the technical condition of automobile air mass flow sensors on a stand while installing a reference and test sensors, supplying air flow through the fans through the sensors in series, changing the flow rate using a throttle valve, characterized in that the tested sensor is connected in a bridge circuit and a relative voltage assessment is carried out from the reference and tested sensors, smoothly echivaya throttle opening, obtaining a difference of the reference and test signals of sensors without preliminary calculations, using which the technical condition of the test sensor. 2. A test bench for mass air flow sensors, comprising a frame with a fan mounted on it with an electric motor connected by a transitional and corrugated pipe to a throttle assembly, pipe clamps, reference and test sensors, a measuring device, a power supply, characterized in that the device is mounted on a rack and contains balancing resistances and resistances for adjusting sensitivity, a switch, and is connected using an electrical connector With reference and test sensors, a measuring scale is installed on the throttle assembly. 3. The stand according to claim 2, characterized in that the measuring scale has divisions from 0 to 90 ° with a division value of 10 °.

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