轻型车转鼓试验循环分析

Duty cycle for chassis dyno IQA test.
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2015/11/4
Cummins Confidential
Background
For IQA test, we follow the AEB 21.52 to test cooling and CAC system for trucks and Buses. We test vehicle at rated torque and rated power duty cycle to validate the cooling and CAC application design. We are challenged by OEM and customer when we test the passenger vehicle and light duty vehicles. The point from OEM is that the passenger vehicles and light duty vehicles almost never run at rated full load, why we test vehicle cooling system at High load. This topic is trying to find the real maximum load for passenger vehicles and the light duty vehicles, and attempt find a way to aim a duty cycle for LD on chassis dyno test.
TTD vs T Ambient 90 2500
80 2000 70 1500
r/min Engine Speed kPa Deg C/ P
60
50
1000
T
40 500 30
20 300 400 500 600 time（S） 700 800 900
0
T_Ambient
T_Coolant_out (Deg C) 出水温度
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2015/11/4
Cummins Confidential
AEB 21.52 specification for Cooling System test.
The TTD is in constant when engine stable run but rising T coolant and T ambient
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2015/11/4
Cummins Confidential
AEB 21.52 specification for Cooling System test.
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2015/11/4
Cummins Confidential
AEB 21.52 specification for Cooling System test.
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2015/11/4
Cummins Confidential
AEB 21.52 specification for Cooling System test.
The TTD measured at maximum load is reprehensive cooling system capability of the vehicle. The TTD is constantly when ambient temperature 15-43 Deg C, So, TTD is called Cooling Constant Factor by some OEM. TTD maximum limit depend on the area vehicle will run.
D
C
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2015/11/4
Cummins Confidential
Vehicle over payload
Over load happened frequently, heavily. Overload limited by transport legal regulation. Start ability will be impacted by over load physically. The over load limited by it start. Over load, will make the vehicle speed lower than normal. Suppose over load will be 150% over load as worst situation. Suppose the over load happened at rated torque speed.
T_Coolant_in (Deg C) 进水温度
TTD
Engine_Speed (rpm) 发动机转速
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2015/11/4
Cummins Confidential
LDV Cooling system Severest Environments Factors
The vehicle cooling system severest environments should be simulated at chassis dyno test or tow dyno test for validate cooling system design. The considered factor should be below.
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2015/11/4
Cummins Confidential
Vehicle run on severest grade road
The severest road for vehicle is at maximum grade uphill and worst friction. The road roll friction is depend on tire performance and road construction, the friction calculated in tire loss power in VMS simulation. Grade hill depend on road construction specification. If the road is not plane, vehicle could not drive in high power and speed since the shake and noise. The grade and distance specification as next page table presents.
– Engine duty cycle design.
– Vehicle over payload. – Vehicle run on severest road. – Run at high ambient temperature. – Air conditioner open and accessory components run. – Fan drive control – Thermostat range
– – – – – – – – – Engine duty cycle design. Vehicle over payload. Vehicle run on severest grade road. Run at high ambient temperature. Air conditioner open and accessory components run. Fan drive control Thermostat range Coolant heat capacity and system daeration Transmission operation
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2015/11/4
Cummins Confidential
Vehicle over payload
Avalon engine on DAF FALF45 rapid truck did a overload test for duty cycle logging. The truck load is on specification. Its GW is 7 tons. The over load realized by tow another vehicle. The dual vehicles GVW is 16, 20, 25 tons. Its over load is 125%,185% and 250%. The duty cycle is logged as run time vs. engine torque and speed.
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JTG B01-2003 Technical Standard of High Way Engineering
Design Speed
Minimum Hill distance
Sh iya n
G uc he ng L ao he ko u Z ao ya ng
S ui zh ou Xi ao ga n
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2015/11/4
Cummins Confidential
Vehicle over payload
Right figure is engine run time vs engine speed and engine Torque. A is the vehicle VGW 7 tons with 125 kw/2600rpm engine at full load on high way. B is the same vehicle 125% over load run at same high way.
Light Duty Vehicle &Passenger Car Chassis Dyno Test Load Analysis
Chen P Peng
Agenda
Background AEB 21.52 specification. LDV Cooling system Severest Environment Factors
– Coolant heat capacity and system daeration
– Transmission operation
wk.baidu.com
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2015/11/4
Cummins Confidential
Engine Duty Cycle Design
Engine duty cycle base on power train design and the driver operation. Engine run at lower speed and higher shift will get engine more possible close to full load. Most engine designed run most time at top torque speed instead of maximum speed. Engine torque speed is more important than maximum speed for system validation test.
A
B
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2015/11/4
Cummins Confidential
Vehicle over payload
Continuously C is 185% over load run at same high way. D is 250% over load at same high way. The over load result the engine run at 50% between 80% of rated speed run. Very few run at maximum speed.