Iowa State University's Off-Highway Vehicle Chassis Dynamometer Laboratory consists of the following pieces of equipment:
- Four corner vehicle chassis dynamometer.
The four corners of the chassis dyno are loaded by placing a vehicle on the roller bed. Each roller bed consists of six 500 mm steel rollers that are coupled together and powered by an electric motor. These rollers are 1796 mm long. Numbering the rollers from the front for the front banks, and from the rear for the rear banks (see in figure below), between the 4th and 5th powered rollers there is a 250 mm OD lift idler roller (labeled "L" in figure below) that is lowered for wheeled vehicles so that the vehicle wheels are cradled between the 4th and 5th powered rollers. For wheeled vehicles, rollers 1, 2, and 3 are decoupled from the other powered rollers to decrease inertia. For tracked vehicles, the idler roller is raised and rollers 1, 2, and 3 are coupled creating a bed of seven rollers to support the vehicle track.
The dyno will support a maximum of 160 kN of axle load or vehicle weight up to 311 kN (70,000 lbs). Each roller bank can place over to 55,000 N of load on a traction element up to 33 km/h and up to 17,000 N between 33 to 80 km/h depending on the ability to generate tractive force between the tractive element and rollers. Thus the chassis dyno can resist a maximum total horizontal tractive draft force of 222 kN (50,000 lbs). The dyno supports a wide range of speeds up to 80 km/h. Acceleration of 3.5 m/s2, which is equivalent to 12.6 km/h/s.
Wheelbase adjustment: The dyno has an adjustable wheelbase range of 1400 mm so that 2900 -- 4300 mm vehicle wheelbases can be accommodated for wheeled vehicle with the wheels cradled between rollers 4 and 5. Smaller wheelbases down to 1285 mm (from measurements; 1500 mm is published) can be accommodated by placing the wheels between roller 5 and 6. Tracked vehicle wheelbases are similar, but since the track is not cradled between rollers, there can be more flexibility than wheeled vehicles. However, wheel base capability can be reduced depending on the track surface length.
The ACME screw that adjusts the wheelbase has a outer diameter of 55 mm and a 12 mm pitch.
The distance between the inner edge of the rollers or minimum inside tire width is 813 mm (32 in.) and that of the outer roller edges is 4405 mm to support a maximum outside tire width of 4.3 m (172 in.). A wide range of vehicle tread widths can be accommodated.
The motor of each dyno corner is controlled with a Vacon/Danfoss frequency converter with the following characteristics:
| Description | Value | Unit |
|---|---|---|
| Manufacturer | Vacon/Danfoss | |
| Nominal Power | 450 | kW |
| Nominal Current | 820 | A |
Each corner of the dyno is powered by a VASCAT motor (M/N MOTOR MAC-QI 250 X) with the following characteristics:
| Description | Value | Unit |
|---|---|---|
| Motor (per unit) | ||
| Manufacturer | Vascat | |
| Nominal Power | 540 | kW |
| Nominal Current | 803 | A |
| Nominal Torque | 3650 | Nm |
| Nominal Speed | 2500 | RPM |
| Protection Class | IP23 | |
| Cooling Type | forced air |
Transmission of mechanical power to and from each electrical motor and the rollers above is implemented through timing belts (Gates Poly Chain Carbon Volt) and pulleys. The belts have a 14 mm pitch. Three different belts are used on the machine with part numbers:
The belts connecting each electric motor to the jack shaft have 224 teeth and are 125 mm wide. P/N is 14GTV-3136-125.
The belts connecting each jack shaft to two rollers above have 280 teeth and are 180 mm wide. P/N is 14GTV-3920-180.
The belts connecting rollers to rollers at the top have 170 teeth are 180 mm wide. P/N is 14GTV-2380-180.
The motor pulley is 64 T x 125 mm wide.
The first jack shaft pulley is 112T x 125 mm wide.
The second jack shaft pulley is 40T x 187 mm wide.
The roller pulleys are 90T x 187 mm wide.
These pulleys then implement a 3.9375:1 gear ratio from the motor to the rollers. The coefficient relating motor speed (rev/min) to roller peripheral speed (km/hr) is 0.023936 taking into account the 250 mm roller radius.
The figure below shows the relationship between motor torque and speed for a dyno corner motor. The maximum torque that the motor can provide under a IEC S1 continuous operation duty cycle is 3,650 Nm which corresponds to 55,000 N of force on the rollers' periphery. This torque can be maintained up to 1325 rev/min which corresponds to 33 km/h at the rollers' periphery. The dyno motors are rated to turn up to 3,200 rev/min which corresponds to 80 km/h while delivering up to 17,000 N peripheral force on the rollers.
Each dyno corner motor can deliver a maximum power of 520 kW for the IET S1 duty cycle and 760 kW for S6. For S1, this maximum power is delivered for shaft speeds above 1325 rev/min corresponding to 33 km/h peripheral roller speed. Below this speed, the maximum torque is limiting power delivery. Above 2350 rev/min, the power drops off. The chart shows that at the rated maximum speed of 80 km/h, 380 kW of power is being delivered.
The complete AC-Drive system for the chassis dyno and the PTO dyno is limited to 1000 kW.
- Power Take-Off (PTO) dynamometer
The PTO dyno is powered by a VASCAT motor (M/N MOTOR MAC-QI 250 L) which has a 270 kW nominal power rating for the S1 duty cycle (continous operations); the nominal torque is 2810 N-m. Nominal current is 425.5 A and nominal speed is 918 rev/min and maximum speed is 4000 rpm.
The PTO Dynamometer will accommodate both 540 rpm and 1000 rpm PTO speeds and can absorb or motor up to 250 kW (350 Hp) at 1000 rpm (requiring a load torque of 2386 N-m) and 160 kW (115 Hp) at 540 rpm (requiring a load torque of 2810 N-m).
- Vehicle Connection Unit (VCU)
The VCU enables the connection of sensor associated with the vehicle to the data acquisition system associated with the dyno control system. The data acquisition system is based on Beckhoff EtherCat modules, the specifics are listed below:
Quantity 12: 0 to 10 V Analog Inputs with BNC connectors (Beckhoff EL3164 EtherCAT Terminal)
Quantity 4: Thermocouple Analog Inputs (Beckhoff EL3314 EtherCAT Terminal)
Quantity 4: 0 to 10 V Analog Outputs with Banana Jack Connectors (Beckhoff EL4104 EtherCAT Terminal)
Quantity 8: Digital Inputs (Beckhoff EL1008 EtherCAT Terminal)
Quantity 8: Digital Relay Outputs (Beckhoff EL2634 EtherCAT Terminal)
Quantity 4: Digital Counter Inputs with BNC connectors (Beckhoff EL1512 EtherCAT Terminal)
Quantity 2: Controller Area Network Channels (Beckhoff EL 6751 EtherCAT Terminal)
Data are recorded at 100 samples per second for the entire dyno rig.
VCU Location: The VCU is located 4.5 m from the lateral center of the dyno and 6.5 forward from the rear lift rollers (See above figure). The height of the VCU is 1.5 to 1.8 m above the floor.
- Hydraulic Dynamometer
A hydraulic dynamometer is being built to load the vehicle hydraulic systems such as the remote hydraulics of a tractor. The system can take up to 227 L/min (60 gal/min) at a maximum pressure of 207 bar.
Fuel Flow Meter
ISU Dyno fuel flow meter (Source AIC Systems). Model Number: AIC-5004 Fuel Flow Master, AIC Systems, measuring 1 to 120 L/hr
Connectors: Quick Disconnect European industrial profile with nominal 1/4 in ID. See McMaster for plug adapter fittings.
- Emissions Measurement Equipment
Bruker OMEGA 5 gas analysis system is available in the lab for the measurement of gaseous emissions from engines including NO/NOX, HC, CO, and CO2. The OMEGA 5 can acquire one scan per second at a spectral resolution of 1 cm-1 with 5 m path length gas cell. The system includes a heated membrane pump to draw samples from the vehicle exhaust system at up to 10.5 L/min.