CN103398849A - Idle Speed Calibration Method for the Relationship between Vehicle Speed and Engine Speed - Google Patents

Abstract

An idling calibration method for relation between vehicle speed and engine speed is a method for calibrating relation between vehicle speed and engine speed under idling working condition of engine without installing engine speed meter to measure engine speed when vehicle is detecting dynamic property or waste gas emission or fuel economy on chassis dynamometer bench, through test statistics or resource sharing or estimating average stable idling of engine of detected vehicle on chassis dynamometer, after engine speed and vehicle speed of vehicle on bench are stable under idling working condition, measuring vehicle speed of drum of chassis dynamometer, and calibrating to obtain ratio of vehicle speed of detected vehicle on bench to average stable idling of engine.

Description

Idle Speed Calibration Method for the Relationship between Vehicle Speed and Engine Speed

Technology area

The idle speed calibration method of the relationship between the vehicle speed and the engine speed is to measure the engine speed without installing the engine tachometer when the car is tested on the chassis dynamometer bench for power performance, exhaust emission or fuel economy. The method for the relationship between the engine speed belongs to the technical field of the automobile performance bench test detection method.

Background technique

In the exhaust emission detection of diesel vehicles with loading and deceleration method, the engine speed needs to be measured. Using an engine tachometer to measure the engine speed has a contradiction between operability and accuracy. If an engine tachometer with high accuracy is used for measurement, the installation speed The operability of the instrument sensor is very poor; if the adsorption vibration sensor with better operability is used, the detection accuracy is very poor.

When the rated torque of the engine is specified at the speed point of the load to detect the dynamic performance or fuel economy, when calculating the loading force of the power absorbing device or calculating the rated torque to detect the vehicle speed, the ratio of the vehicle speed to the engine speed of the transmission gear of the vehicle is required K, refer to the Chinese invention patent "Automobile Constant Speed Engine Specified Load Detection Method", patent number: ZL200910225329.7, when the vehicle being inspected has no engine tachometer, no complete vehicle technical parameters, and no resource sharing to obtain the K value , you need to install an engine tachometer to calibrate the K value, and there is also a contradiction between operability and accuracy. In order to overcome the deficiencies of the existing technology, the idle speed calibration method based on the relationship between the vehicle speed and the engine speed is adopted, without installing an engine tachometer, and the vehicle can quickly calibrate the engine idle speed on the chassis dynamometer to obtain the K value.

Contents of the invention

In the same automobile mechanical transmission, the relationship between the vehicle speed Vi after the gear is engaged and the engine speed ni is fixed, and K=Vi/ni is a constant. The rated speed of different engines varies greatly, but the idle speed of the engine is not much different, and the idle speed of the engine on the chassis dynamometer with the transmission gear of different vehicles is not much different. Through the test statistics of various models or resource sharing Alternatively, it can be estimated that the speed range of the stable idle speed of the engine on the chassis dynamometer of various vehicles can be determined, and the average stable idle speed can be used as the engine speed corresponding to the speed of the idle speed of the vehicle bench, so as to obtain the speed range of the detected vehicle. The relationship between the speed of the gear and the engine speed, the test method is as follows:

The vehicle turns off non-essential energy-consuming devices such as the air conditioner, drives on the unloaded chassis dynamometer, uses a high-precision engine tachometer to measure the engine crankshaft speed, increases the accelerator and puts the transmission detection gear to increase the vehicle speed, and then completely Release the accelerator pedal to keep the engine at idle speed, and the vehicle speed and engine speed gradually decrease. When the engine speed and vehicle speed are stable at idle speed, measure and record the crankshaft speed of the engine, respectively for diesel vehicles, gasoline vehicles, passenger cars and trucks Measure the engine idle speed of the vehicles in use in various model series, so as to obtain the stable engine idle speed range on the chassis dynamometer. Due to the different resistance of the vehicle bench system of different types and different series models, in order to reduce the stable idle speed of various engines Scope, to improve accuracy, can be classified by diesel vehicles and gasoline vehicles, or by passenger cars and trucks, or by model series, or can be obtained through resource sharing or classification estimation.

Since the vehicle bench system resistance (including engine idling resistance) on the chassis dynamometer is greater than the engine idling resistance, the driving force and fuel supply of the engine idle condition on the bench increase accordingly, and the engine idle speed decreases slightly. For example, if the stable idling speed of a diesel truck idling in a model series is in the range of (650-750) r/min, it can be estimated that the stable idling speed range of the diesel engine on the chassis dynamometer is (600-700) r/min, and the average stable idling speed is 650r/min.

The idling calibration method for the relationship between vehicle speed and engine speed is a method for calibrating the relationship between vehicle speed and engine speed without measuring the engine speed when the car performs related performance testing on the chassis dynamometer. It is characterized in that: through test statistics or resource sharing or Estimate the average stable idle speed n ₁ of the engine of the inspected vehicle on the chassis dynamometer, turn off the non-essential energy-consuming devices such as the air conditioner on the vehicle, and increase the accelerator on the unloaded chassis dynamometer, put the gearbox on the detection gear and increase the vehicle speed Finally, release the accelerator pedal completely to keep the engine at idle speed, and the engine speed and vehicle speed gradually decrease. After the engine speed and vehicle speed are stable at idle speed, measure the speed of the chassis dynamometer drum, that is, the wheel speed V ₁ , and calibrate The ratio K=V ₁ /n ₁ of the vehicle speed of the detected vehicle on the bench to the engine speed is obtained. The advantages of this method are as follows:

1. The resistance of the vehicle bench system of different series of models is different, but the ratio of system resistance to engine idling resistance does not change much, so that the ratio of fuel supply increase and idle speed reduction also does not change much. The system resistance is relatively large, the engine idling resistance is relatively large, and the various ratios do not change much. Turn off non-essential energy-consuming devices to reduce system resistance.

2. The transmission detection gear is generally determined according to the different performance testing requirements of the vehicle. The power and exhaust emission detection is usually the direct gear, and the fuel economy detection is usually the highest speed gear. The engine idle speed of the same vehicle transmission in different gears Little change.

3. In order to minimize the statistically stable idle speed range of the engine and improve the accuracy of calibration, test statistics or estimation can be subdivided by different fuels, different vehicle types, and different model series. The inspected vehicles are automatically retrieved according to the registered vehicle information Average steady idle speed from test statistics or estimation.

4. Perform various performance tests at the rated engine torque point, and calculate the corresponding vehicle speed V _m =K×n _m according to the rated engine torque speed n _m .

5. Without the complete technical parameters of the inspected vehicle, the engine torque and engine accessory consumption torque can be equivalently converted to the equivalent driving force of the engine on the surface of the driving wheel and the equivalent resistance of the engine accessories, so as to determine the power absorption device for various performance tests of the vehicle required loading force.

6. There is no need to install an engine tachometer to measure the speed. According to the measured instantaneous vehicle speed Vi, the corresponding instantaneous engine speed ni=Vi/K can be calculated.

specific implementation plan

The idle speed calibration method for the relationship between vehicle speed and engine speed, taking the exhaust emission detection method of diesel vehicles under loading and deceleration conditions as an example, the specific implementation plan is as follows:

Test a 5040 series box-type diesel truck, the engine rated speed is 3600r/min, the average stable idle speed of this series is estimated to be 650r/min, the vehicle turns off non-essential energy-consuming devices such as air conditioners, and the vehicle is tested on an unloaded chassis dynamometer , increase the accelerator and gradually put on the direct gear to make the vehicle speed exceed 30km/h, then release the accelerator pedal completely to keep the engine in the idling condition. At this time, the engine speed and vehicle speed will gradually decrease. After the vehicle speed is stable, the vehicle speed V ₁ of the chassis dynamometer roller is measured to be 15.2km/h, and the relationship between the vehicle speed of the vehicle's gearbox direct gear and the engine speed value K=V ₁ /n ₁ =15.2/650=0.0234 is calculated. Then increase the accelerator to detect the exhaust gas emission by loading and decelerating working conditions. When the measured instantaneous vehicle speed is Vi, the corresponding instantaneous engine speed is ni=Vi/K=Vi/0.0234. When the maximum wheel power is detected, the vehicle speed is 78.3km /h, the corresponding engine speed is 78.3/0.0234=3346r/min.

The idle speed calibration method of the relationship between the vehicle speed and the engine speed can measure the K value and the engine speed corresponding to each speed point without installing an engine tachometer, which has the advantages of good operability and accuracy.

Claims (1)

1. the idling scaling method of the speed of a motor vehicle and engine speed relationship, that automobile is when the enterprising line correlation Performance Detection of chassis dynamometer, do not measure engine speed and demarcate the method for the speed of a motor vehicle and engine speed magnitude relationship, it is characterized in that: by test statistics or resource sharing or the engine of estimation institute's inspection vehicle on chassis dynamometer, on average stablize idling n ₁Vehicle cuts out the nonessential energy-dissipating devices such as air-conditioning, on the chassis dynamometer that does not load, after opening the throttle and hanging up wheel box and detect the gear rising speed of a motor vehicle, be totally released gas pedal, make engine be in idling operation, engine speed and the speed of a motor vehicle descend gradually, after idling operation was all stablized, measuring the dynamometer roller speed of a motor vehicle was the wheel vehicle velocity V until engine speed and the speed of a motor vehicle ₁, demarcate and obtain the institute's speed of a motor vehicle of this gear of inspection vehicle on stand and the ratio K=V of engine speed ₁/ n ₁.