Method for determining loading power of heavy gas steady-state working condition method

Abstract

The invention relates to a method for determining loading power by a heavy gas steady-state working condition method, which is a method for determining the loading power when heavy gas is subjected to exhaust emission detection by the steady-state working condition method, and comprises the following steps of: measuring system equivalent inertia and system resistance of a vehicle and a rack on a light gas rack or a heavy diesel rack by adopting a free and constant force loading two-time sliding method; the system resistance is measured by freely sliding on the other rack, the difference between the friction resistance of the tire and the surface of the roller at the same vehicle speed point on the two racks can be obtained, the difference between the resistance coefficients serves as a constant, and the difference between the friction resistance of the tire and the surface of the roller of the two racks, the difference between the resistance coefficients and the difference between the loss power are obtained by multiplying the constant by the driving axle load. The loading power of double shafts on two identical light-gas racks is simulated on the heavy-gas rack through double-shaft driving, the equivalent inertia of a neutral gear transmission system of the vehicle is measured on the heavy-gas rack, a transmission shaft between a rear driving shaft and an inter-axle differential mechanism is detached, and the inter-axle differential mechanism is locked and tested on the light-gas rack.

Description

TECHNICAL FIELD

[0001] The method for determining the load power of heavy-duty steady-state operating conditions is a method for determining the load power when a heavy-duty vehicle with a spark-ignition engine is tested for exhaust emission under steady-state operating conditions on a heavy-duty diesel vehicle load deceleration chassis dynamometer, and belongs to the technical field of automobile exhaust emission testing. BACKGROUND

[0002] The pollutant emission testing of a vehicle using gasoline is carried out in accordance with GB18285-2018 "Gasoline Vehicle Pollutant Emission Testing Limits and Measurement Methods (Double-idle Method and Simple Operating Condition Method)". According to GB18285-2018 Clause 1, "This standard is also applicable to other vehicles equipped with spark-ignition engines". That is, it is applicable to gas-fueled vehicles such as natural gas vehicles under Clause 3.19, and many single-axle or double-axle driven natural gas heavy-duty tractors. The chassis dynamometer for testing under Clause B.5.1.1.1 of the standard cannot adapt to the testing of double-axle driven heavy-duty vehicles. The existing testing station only has a two-axle four-roller light-duty gasoline vehicle bench and a three-axle six-roller heavy-duty diesel vehicle bench. The roller diameter of the light-duty vehicle bench is limited to (218±2) mm, and the three-axle six-roller heavy-duty diesel vehicle bench does not limit the roller diameter, and the roller diameter is usually greater than 300 mm. In order to standardize the uniformity of the load power for testing, the chassis dynamometer with a roller diameter not equal to (218±2) mm is used to calculate the set power value, and the surface friction loss power of the tires and rollers with two different roller diameters is required. The standard does not specify the measurement method of the surface friction loss power of the tires and rollers with two different roller diameters, and the method for determining the load power of heavy-duty steady-state operating conditions uses an accurate and fast method to determine the load power. SUMMARY

[0003] The method for determining the load power of heavy-duty steady-state operating conditions is as follows: the vehicle is tested on a light-duty gasoline vehicle bench or a heavy-duty diesel vehicle bench using the free and constant force loading twice sliding method, or the twice constant force loading sliding method, the system equivalent inertia and system resistance of the vehicle and the bench are measured, the system resistance is measured by free sliding on another bench, the difference between the tire and roller surface friction resistance at the same speed point on the two benches is obtained, the difference between the tire and roller surface friction resistance at the same speed point on the two benches is obtained by multiplying the difference between the resistance coefficients by the driving axle weight, and the difference between the tire and roller surface friction resistance at the same speed point on the two benches is obtained by multiplying the difference between the resistance coefficients by the driving axle weight. The loss power difference. The heavy-duty vehicle with a spark-ignition engine is referred to as a heavy-duty gasoline vehicle or a heavy-duty vehicle, and the heavy-duty vehicle has single-axle drive and double-axle drive. The double-axle driven heavy-duty vehicle simulates the load power of the double-axle on two identical light-duty gasoline vehicle benches on the heavy-duty diesel vehicle bench.

[0004] 1. Single-axle driven heavy-duty gasoline vehicle testing

[0005] The heavy vehicle with wheel diameter of about 1000mm is driven on the light gasoline bench, and the system equivalent inertia is measured by the free and loaded sliding method after the driving drum reaches high speed and is in the neutral gear. The system equivalent inertia multiplied by the deceleration of the free sliding at the specified speed point of the light gasoline bench can obtain the system resistance Fa of the light gasoline bench at the specified speed point. The system equivalent inertia minus the basic inertia of the light gasoline bench is the equivalent inertia Mc of the vehicle in the neutral gear.

[0006] The vehicle is driven on the heavy diesel bench at high speed and in the neutral gear, and the system equivalent inertia is the sum of the equivalent inertia Mc and the basic inertia of the heavy diesel bench. The deceleration at the specified speed point and the system resistance Fz can be obtained by the free sliding without loading. The difference between the system resistances at the same speed point on the two benches Fa-Fz can be obtained. The system resistance of the vehicle on the bench is the sum of the resistance of the vehicle transmission system in the neutral gear Fc, the friction resistance of the tire and the drum surface Fb, and the bench resistance Ft. Since the resistance of the vehicle transmission system in the neutral gear is the same at the same speed point on the two benches, the difference between the resistances of the two benches can be obtained by dividing the difference between the resistance coefficients by the weight of the driving shaft. Similarly, the free and loaded sliding method can be used on the heavy diesel bench first, and then the free sliding method can be used on the light gasoline bench.

[0007] 2. Test of heavy gasoline vehicle with dual-axle drive

[0008] (1) Measurement of the system equivalent inertia and the system resistance of the vehicle in the neutral gear and the bench on the heavy diesel bench

[0009] The dual-axle drive vehicle has a differential between the two axles. The differential is locked, and the system equivalent inertia and the system resistance of the vehicle in the neutral gear and the bench are measured by the free and loaded sliding method. The equivalent inertia of the vehicle transmission system in the neutral gear can be obtained.

[0010] The driving shaft between the rear driving shaft and the differential is removed, the differential is locked, and the front driving shaft is placed on the light gasoline bench. The system equivalent inertia and the system resistance of the vehicle in the neutral gear and the bench are measured by the free and loaded sliding method. The equivalent inertia m1 of the front driving shaft and the equivalent inertia m2 of the rear driving shaft can be obtained by subtracting the basic inertia of the light gasoline bench from the system equivalent inertia. The system resistance of the rear driving shaft and the bench is measured by the free sliding after the rear driving shaft is driven by the motor at high speed. Alternatively, m1 and m2 can be estimated, the system resistance of the front and rear driving shafts and the bench is measured by the free sliding, the system resistance of the vehicle transmission system in the neutral gear and the two light gasoline benches at the same speed point can be obtained, and the difference between the friction resistances of the tires and the drum surface of the two benches at the same speed point can be calculated.

[0011] (2) Measurement of the system equivalent inertia and the system resistance of the vehicle in the neutral gear and the bench on the light gasoline bench

[0012] Remove the drive shaft between the rear axle and the inter-axle differential, lock the inter-axle differential, and measure the system equivalent inertia and system resistance of the vehicle's empty front drive axle and the test bench using the free and loaded two-slip method. Turn off the power to the rear drive wheels after driving them to high speed, measure the system equivalent inertia and system resistance of the rear drive axle and the test bench using the free and loaded two-slip method, or estimate the system equivalent inertia of the rear drive axle and the test bench, measure the system resistance of the rear drive axle and the test bench using the free-slip method, and obtain the equivalent inertia of the vehicle's empty drive train and the system resistance of the vehicle's empty drive train and the light gasoline test bench.

[0013] The vehicle is driven onto the heavy diesel test bench, the system equivalent inertia of the vehicle's empty drive train and the heavy diesel test bench is known, the system resistance of the vehicle's empty drive train and the heavy diesel test bench at a specified speed point is measured by free-slip, and the difference in tire and drum surface friction resistance, the difference in resistance coefficient, and the difference in power loss at the same speed point between the two test benches can be calculated.

[0014] 3. Statistical method to determine the equivalent inertia of the drive axle

[0015] The equivalent inertia of the drive axle of a heavy vehicle is mainly determined by the wheel rotational inertia, and the difference in equivalent inertia of the drive axle is not significant when the tire diameter range changes little. According to test statistics, the equivalent inertia of the front drive axle of the vehicle's empty drive train is about 230 kg, and the equivalent inertia of the rear drive axle is about 215 kg. The difference in tire and drum surface friction resistance, the difference in resistance coefficient, and the difference in power loss can be measured by slipping on the light gasoline test bench and the heavy diesel test bench.

[0016] The difference in resistance coefficient is taken as a constant, multiplied by the weight of the drive axle of the vehicle being tested to obtain the difference in tire and drum surface friction resistance, the difference in resistance coefficient, and the difference in power loss between the two test benches.

[0017] Since the adhesion weight of the dual drive axle on the light gasoline test bench drum is slightly reduced, the resistance or resistance coefficient of the light gasoline test bench can be multiplied by δ to compensate. δ is selected in the range of 1.0 to 1.15, δ = 1.0 when the two drive axles are independent suspensions, δ = 1.0 for single axle drive vehicles, and the set power value for any heavy vehicle ASM operating condition is calculated according to GB18285-2018 BA.1.1 and BA.1.2.

[0018] The method for determining the load power of the heavy vehicle steady state operating condition has outstanding technical effects: 1. It is simple and fast to operate, can utilize the existing program for measurement on the light gasoline test bench and the heavy diesel test bench, and can use diesel tractor tests to simplify the test conditions. 2. The difference in tire and drum surface friction resistance coefficient is used for calculation, which greatly reduces the influence of different tire diameters and changes in tire and drive train technical conditions. 3. The tire and drum surface friction resistance or resistance coefficient of the dual axle drive wheels on the light gasoline test bench is compensated, further improving the accuracy and uniformity of determining the load power. DETAILED DESCRIPTION

[0019] According to JJF1221-2009 "Calibration Specification for Chassis Dynamometer for Vehicle Exhaust Pollution Detection", the system equivalent inertia and system resistance of the vehicle partial transmission and the bench are measured by free and loaded twice slip method.

[0020] The light gasoline bench roller diameter is Φ218mm, the bench basic inertia is 916kg, the bench resistance power is 0.40kW at 25km / h and 0.80kW at 40km / h. The heavy diesel bench roller diameter is Φ452mm, the bench basic inertia is 1460kg, the bench resistance power is 0.50kW at 25km / h and 1.03kW at 40km / h. The ignition type natural gas double axle driven heavy duty tractor, the total mass is 8805kg, the front and rear drive axle weights are 2092kg and 1957kg respectively, the two drive axle weights are (2092+1957)×9.8=39680N.

[0021] The vehicle drives into the heavy diesel bench, the system inertia is measured by free and loaded twice slip method, which is 1911kg, the vehicle empty gear transmission equivalent inertia is 1911-1460=451kg, the system resistance power is 6.68kW at 25km / h and 12.17kW at 40km / h.

[0022] The transmission shaft between the rear drive axle and the inter axle differential is removed, the inter axle differential is locked, the front drive axle is placed on the light gasoline bench, the system inertia is measured by free and loaded twice slip method, which is 1156kg, the front axle drive equivalent inertia is 1156-916=240kg, the rear axle is 451-240=211kg, the system resistance power is 3.88kW at 25km / h and 7.24kW at 40km / h. (Or estimate the equivalent inertia of the front and rear axles, only need to measure the system resistance and power by free slip method).

[0023] The rear drive axle is placed on the light gasoline bench, the system resistance power is measured by free slip method, which is 3.96kW at 25km / h and 7.53kW at 40km / h. The system resistance power of the vehicle empty gear on the light gasoline bench is 3.96+3.88=7.84kW at 25km / h and 7.53+7.24=14.77kW at 40km / h. (If the two drive axles are swing type, the power can be multiplied by δ to compensate).

[0024] The difference of the tire and roller surface friction loss power of the vehicle on the light gasoline bench and the heavy diesel bench is (7.84-2×0.4)-(6.68-0.5)=0.86kW at 25km / h and (14.77-2×0.8)-(12.17-1.03)=2.03kW at 40km / h.

[0025] The difference between the tire and the roller surface friction coefficient of two racks: 0.86 x 3600 / (25 x 39680) = 123.84 / 39680 = 0.0031 at 25 km / h, 2.03 x 3600 / (40 x 39680) = 182.7 / 39680 = 0.0046 at 40 km / h. Assuming that the difference in resistance coefficient is constant, multiply the weight of the detected drive shaft to get the difference between the tire and the roller surface friction resistance of the two racks.

[0026] According to GB18285-2018 BA.1.1 and BA.1.2, P5025 = 25 + 0.86 = 25.86 kW, P2540 = 25 + 2.03 = 27.03 kW. If the detected heavy vehicle double drive axle mass is 4800 kg, P5025 = 25 + 0.0031 x 4800 x 9.8 x 25 / 3600 = 26.01 kW, P2540 = 25 + 0.0046 x 4800 x 9.8 x 40 / 3600 = 27.4 kW.

[0027] The steady state condition method for loading heavy diesel engine on heavy diesel engine test bench is simple and fast, which improves the accuracy and standardization of determining the loading power, and simplifies the test conditions.

Claims

1. The method for determining the loading power of a Sinotruk vehicle under steady-state operating conditions is to determine the loading power when a heavy-duty vehicle with a spark-ignition engine is subjected to a steady-state exhaust emission test on a chassis dynamometer using a loading and deceleration method for a heavy-duty diesel vehicle. The method is characterized by: The dual-axle drive Sinotruk simulates the loading power of the dual-axle on two identical light truck test benches on the heavy diesel test bench. The dual-drive Sinotruk first measures the equivalent inertia of the vehicle's neutral transmission system and the system resistance by the free and loaded sliding method twice on the heavy diesel test bench, removes the drive shaft between the rear drive shaft and the inter-axle differential, locks the inter-axle differential, and measures the system equivalent inertia and system resistance of the front drive shaft and the test bench by the free and loaded sliding method in the neutral position on the light truck test bench. The motor drives the rear drive shaft wheels at high speed and then cuts off the power to measure the system resistance of the rear drive shaft and the test bench, or estimates the equivalent inertia of the front and rear axle drive shafts, and measures the system resistance of the vehicle's neutral transmission system and the two light truck test benches by free sliding. Alternatively, first measure the system resistance of the vehicle's neutral transmission system and the two light truck test benches by the free and loaded sliding method on the light truck test bench. The system equivalent inertia and system resistance of the front drive shaft and the test bench are measured by the coasting method, as well as the system equivalent inertia and resistance of the rear drive shaft and the test bench. Alternatively, the equivalent inertia of the rear drive shaft is estimated, and the system resistance of the rear drive shaft and the test bench is measured by free coasting. Then, the vehicle is free coasted in neutral on the heavy diesel test bench to measure the system resistance. Alternatively, the equivalent inertia of the statistical drive shaft is used to measure the system resistance by free coasting. The difference in friction resistance between the tire and the drum surface, the difference in drag coefficient, and the difference in power loss of the two test benches can be obtained. Alternatively, the resistance or drag coefficient of the light truck test bench can be multiplied by δ to compensate. δ is selected in the range of 1.0 to 1.

15. The difference in drag coefficient is taken as a constant and multiplied by the weight of the drive axle of the inspected vehicle to obtain the difference in friction resistance between the tire and the drum surface, the difference in drag coefficient, and the difference in power loss of the two test benches.