RU2349890C1 - Automated system for diagnostics of gasoline car-and-motor engines - Google Patents

Abstract

FIELD: engines and pumps.

SUBSTANCE: automated system for diagnostics of car-and-motor engines consists of the following components installed on tested engine: detector of rotation frequency, detector of fuel consumption, spark angle detector, pressure detector, unit for interface of detectors with personal computer (PC) and PC itself. In the process of six cycles engine "acceleration-rundown" operations signals from detectors arrive to recording device that consists of seven main components (three level transducers, instrumental amplifier, operational amplifier, analog-to-digital converter (ADC) and microcontroller), which converts them into digital format and sends to PC. Afterwards obtained information is processed in PC, and control results are represented to user in the form of digital values of diagnostic parameters and schedules of engine dynamic speed characteristics.

EFFECT: more accurate determination of control actual parameters of engines technical conditions and their deviations from nominal values with simultaneous reduction of labour expenses due to automation of primary values measurement process and analysis of obtained data.

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Description

The invention relates to a device for the diagnosis of automotive engines in operating conditions.

There is a method of determining the technical condition of internal combustion engines and an expert system for its implementation (AS RU 99108635/06, G01M 15/00). The method is based on determining the technical condition of internal combustion engines by continuously measuring during multiple acceleration and engine coasts without loading average values in the engine cycle, as well as on the working cycle of each cylinder, angular velocity, crankshaft acceleration and dynamic power, obtaining the dependence of the amplitude spectra of the dynamic power and comparing the obtained indicators with the reference, and the degree of change in the state of the engine from normal to permissible classify oyanie engine. But this method allows you to evaluate the energy performance of engines without taking into account the assessment of fuel performance. In addition, this method does not allow to fully evaluate the real state of the power system, ignition and lubrication of gasoline engines that differ from diesel engines both in principle by the method of ignition of the fuel mixture and structurally by the device of the fuel supply elements.

The purpose of the invention is to increase the accuracy of determining control actual parameters of the technical condition of engines and their deviations from the nominal values while reducing labor costs by automating the process of measuring primary values and analyzing the data.

An automated diagnostic system for automotive engines based on a personal computer (PC) is designed to control the fuel and energy performance of gasoline automotive engines. It carries out, while ensuring full identity, the measurement of four data streams and the processing of the results of monitoring the parameters of the technical condition of automotive engines in a single time base and in real time.

The diagnostic system consists of sensors installed directly on the test engine: speed, fuel consumption, ignition timing, pressure; the unit for interfacing sensors with a personal computer and the PC itself (see drawing).

The system for the diagnostic tests of engines works as follows: during the tests, six cycles of acceleration-coasting operations of the engine are carried out from the minimum to maximum crankshaft idle speed, during which the signals received from the primary sensors installed on the engine enter the device records that converts them to digital format and transfers them to a PC. All received information is processed in a PC using special programs and presented both in the form of numerical values of the technical condition parameters, and in the form of graphs of the dynamic speed characteristics of the engine.

As a result of solving the problem of diagnosing the engine, the system determines the dynamic characteristics, which are dependencies:

- engine speed from time to time;

- angular acceleration from speed and time during acceleration and coasting;

- hourly fuel consumption of the engine speed and time;

- the ignition timing of time and the angle of rotation of the crankshaft.

Based on the above dependencies, the parameters of the internal combustion engine are calculated:

- effective power;

- indicator power;

- power of mechanical losses;

- hourly fuel consumption;

- specific fuel consumption;

- uniform distribution of power in individual cylinders;

- ignition timing for each cylinder;

- modes of operation of the centrifugal and vacuum ignition timing regulator of the sensor-distributor.

Using the device you can check:

- functioning of the fuel supply system;

- uniformity of the cylinders;

- maximum gas pressure in the above-piston space at the end of the compression stroke (compression);

- operation of the maximum speed limiter of the engine crankshaft.

The block diagram of the recording device includes six main blocks: an adapter for a speed channel, an adapter for a fuel consumption channel, an adapter for an angle mark channel, a pressure adapter, a microprocessor, and an RS232 interface adapter.

Consider the purpose and functions of each unit individually. All determined parameters of the technical condition of the engine are divided into primary and secondary (i.e., calculated). The primary parameters are parameters read from sensors installed on the engine. The calculated parameters are obtained as a result of mathematical processing of the primary data. There are only four primary data streams: rotation speed, flow rate, angle and pressure. The remaining parameters are calculated based on the primary.

The speed channel adapter normalizes the speed sensor signal. This signal is frequency, varies from 10 to 65 Hz. To obtain physical parameters, minimal calculations are sufficient.

The fuel flow channel adapter normalizes the signal from the fuel flow sensor. This signal is frequency, varies from 100 to 200 Hz. In order to obtain a physical flow parameter, the original frequency signal must be differentiated.

The angle mark channel adapter normalizes the signal from the ignition timing sensor. The data on the ignition timing is calculated based on the determination of the time period between the time-spaced moment of fixing the speed parameters from the speed sensor and the moment of ignition from the ignition sensor. The characteristics of this parameter are similar to the characteristics of the speed parameter.

The pressure adapter normalizes the signal from the pressure sensor. This signal is analog. For further processing, it must be converted to digital form using an analog-to-digital converter (ADC). Based on the possible maximum parameters of the engine, the duration of the information component of the signal is about 2 ms, and the frequency is 20 ms. In order to get a sufficiently informative amount of data, about 50 samples are needed. Consequently, the conversion time of the ADC, taking into account the time costs of primary processing, should be about 10-20 μs.

The microprocessor measures all primary signals, i.e. converts them into a digital form, convenient for further processing, and communicates with a computer to send the accumulated measurements.

The RS232 interface adapter converts the level of digital signals from the microprocessor to the levels necessary to connect the communication channel to the computer.

The requirement made by the analog pressure channel had a decisive influence on the choice of embodiment of the recording device. The analysis of the characteristics of the analog signal showed that the recording device cannot be passive, since there is a sufficiently high speed of data input from the ADC. Therefore, the device must have an integrated microprocessor to control this data stream.

A solution is proposed when the recording device is designed as a separate unit, and communication with the computer is carried out via the RS232 interface. A specially designed program is used to connect a personal computer with a recording device. Such a constructional solution makes the recorder quite mobile and easy to connect for the average user. And as a personal computer, you can use any low-power computer that has an RS232 interface.

The fuel gauge is designed to measure fuel consumption. Structurally, it is a sealed tank in which a fuel level meter is placed. The meter consists of 5 coaxial cylinders forming an electric capacitor. The capacity of this capacitor depends on the fuel level. If the fuel sensor (capacitor) is completely filled with fuel, then the capacity is maximum, and when the fuel from the sensor is used up, then the capacity decreases by about half compared to the maximum.

The device can be used as a separate diagnostic tool for scheduled maintenance, troubleshooting and adjusting engines in households and repair enterprises, in organizations involved in the sale and leasing of cars, as well as a diagnostic tool in factories producing automotive and agricultural technique.

Claims (1)

Automated diagnostic system for automotive engines, consisting of a speed sensor, a fuel consumption sensor, an ignition timing sensor, a pressure sensor, a unit for pairing sensors with a personal computer (PC) and the PC itself, characterized in that during six cycles acceleration-coasting operations of the engine, the signals from the sensors enter the recording device, which consists of seven main elements (three level converters, an instrumental amplifier, onnogo amplifier, an analog-digital converter (ADC) and a microcontroller) which converts them into a digital format and transmits to the PC, after which the resulting information is processed in the PC and the control results are presented to the user in the form of digital values of diagnostic parameters and graphs dynamic speed motor.