# Heavy Duty Chassis Dyno Background

Southwest Research Institute
10 th 

# December 2014

1

# Outline

• Specifications

– Dyno rolls & torque capacity, cooling fan, HVAC, CVS & PM system



## • Overview

– Free

- body, coastdown , test cycles



## • Instrumentation & Features

– DAQ, fuel measurement, drive by wire, variability control



## • Vehicles Tested

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# SwRI Heavy Duty Chassis

Dyno 

# Specifications

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# HD Chassis Dynamometer Specifications

4 

## • Two 48 inch diameter rolls



## • 300 hp DC motor on each roll

• 250 hp road speed fan

• 100 ton HVAC system

• CVS System

• Horiba 7200D emissions bench



## • SwRI developed fuel cart

• 1066 compliant

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# HDC Specifications: Dyno Rolls & Torque Capacity

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## • Twin 300 hp DC rolls

– Class 8 vehicles

– All wheel drive vehicles

– 7500 lb vehicle weight minimum



## • 4500 lb each

– Typical light duty vehicle weight

– Average mass simulation of ~68,000 

### lb

# HDC Specifications: Cooling Fan

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## • 250 hp fan

• Fully retractable

• Capable of simulating road speeds of over 100 mph

# HDC Specifications: HVAC System

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# • Two 50 ton units

• Installed November 2012



# • 40CFR 1066 compliance

# HDC Specifications: CVS & Emissions Measurement

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## • MEXA 7200 D emissions measurement system

• CO 2 

### , CO, NO x 

### , THC



### • CH 4 

### measurement with bag sampling system



## • CVS sampling system

• Up to 3 , 000 CFM

• 47 mm PM measurement system

# Heavy Duty Chassis Dyno

Overview

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# Overview: Setup

12/10/2014 10 Engine Trans Driveline Wheels Torque

Speed Physical Inertia, Friction Dyno

- Set simulated inertia, road load T 1

Cut



## • Typical engine testing is just that, the engine

• Powertrain testing includes the transmission

• Heavy Duty Chassis Dyno

– Includes powertrain and driveshaft, differential, wheels, inertia, and friction

# Overview: Coast

- downs

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## • Inputs to controller

– Mass

– C d 

### , C rr 

### from on

- road coastdowns • Perform coast

- down on chassis dynamometer



### – Iterative process to account for friction

0 1000 2000 3000 4000 5000 6000

0 5 10 15 20 25 30 35 Force (N)

Speed (m/s) Typical Coast

- Down Procedure

Target

1st Iteration Acceptable

# Overview: Typical Test Cycles

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### • ARB Transient

– Short transient



### • World Harmonized Vehicle Cycle

– Medium length, mixture transient and steady state

0 5 10 15 20 25

0 100 200 300 400 500 600 700 800 Speed (m/s)

Time (s) ARB Transient Cycle



### • Parcel Cycle

– Long low speed transient, heavy idle time



### • Utility Cycle

– Long, low speed transient

# Heavy Duty Chassis Dyno

Instrumentation

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# Instrumentation: Data Acquisition

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## • SwRI internally developed system “HDT”

– Utilizes NI hardware



### – Numerous voltage, frequency, CAN inputs and outputs

– Ethernet communication with Horiba emissions bench

 Allows for calibration of instruments remotely



## • Continuous measurement of emissions per 40CFR part 1065

• Emissions results when test ends

– Outputs grams of each constituent

# Instrumentation: Fuel Cart

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### • SwRI developed fuel flow system

– Coriolis style mass flow meter

– Closed loop temperature & pressure controlled

– Captures transient operation

 Improved carbon balance error

 Detect small changes for development

0 10 20 30 40 50 60 70

0 10 20 30 40 50 60

3800 4000 4200 4400 4600 4800 5000 Fuel Flow [kg/hr]

Time [msec] Day Tank

Cart
CAN Fueling

# Heavy Duty Chassis Dyno



# Variability Sources & Mitigation

Approaches

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# HDC Variability

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### • Heavy duty chassis dynamometer fuel economy variability

– Unlike engine and power

- train test cells, no control of temperatures and pressures

 Coolant temperature

 CAC outlet temperature

 Inlet restriction

 CAC delta p

 Exhaust restriction



### • Steps to decrease variability

– Drive by wire

– Engine clutched fan

– External compressed air supply

# Drive by Wire

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### • Light

- duty colleagues were using method first

• Adopted to HD use early 2014

– Use only with automatic, or automatic shifting manual transmissions



### • GEM driver model for control

– Immediate benefits

 Improved FE COV, very little pedal variation

300 310 320 330 340 350 360 370 380 390 400 Time (s) Throttle Position

- ARB Cycle

Drive by Wire Drive By Wire Drive by Wire

Human Driver

Human Driver

# Clutched Fan Control

19 

## • Disable the clutched fan or control fan to engage same time, and duration during each cycle

• Minimal change at engine idle speed

• Significant change at higher engine speeds

0.6 2.4 4.4 9.8 17.8

0 2 4 6 8 10 12 14 16 18 20

600 900 1200 1500 1800 Power (kW)

Engine Speed (RPM)

Fan Absolute Power

– Zero Vehicle Speed

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# Air Compressor Control

• EPA requested an analysis of air compressor impact on transient cycles

– Supply shop air to onboard tanks to prevent operation



## • Air compressor impact hidden by variation of driver

20 720 740 760 780 800 820 840 860 880 900 Tank Pressure (kPa) Air Compressor Characterization

- ARB Cycle

Driver ARB 1

Driver ARB 2

DBW

- Tank Pressure

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# Heavy Duty Chassis Dyno

Closing Statements

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# Summary of Testing

• Transit Bus

• F650

• Freightliner Cascadia

• Kenworth T700

• Kenworth T270 Box Truck

• Autocar Refuse Hauler

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# Conclusions

• Heavy Duty Chassis Dyno capable of testing all wheel drive vehicles, all the way up to class 8 vehicles

• 40CFR 1066 Compliance

• Current program goals provided opportunities to improve operation of heavy duty chassis dyno

• Variability mitigation in the form of “robot” driver, clutched fan control, and air compressor control

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# Questions?

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