NVH Testing

NVH Testing

Our range of extreme low noise N.V.H. Chassis Dynamometer systems have evolved and acquired techniques and capabilities previously only demanded in “high accuracy” emission test systems.

With continuous development of motor vehicles comes the demand for ever-improving product refinement. An increasingly significant area of this important work is passenger safety and comfort. The measurement and evaluation of vehicle noise, vibration, and harshness levels is subject to the variations in road and climatic conditions. By using a chassis dynamometer within a semi-anechoic chamber, the difficulty in monitoring these parameters under controlled conditions an be overcome.

Hofmann produce specialist chassis dynamometer designs which allow investigation of NVH levels whilst the vehicle is running under accurate and repeatable road load simulation, speed, force, or acceleration control.

Hofmann Chassis Dynamometer within a semi-anechoic chamber

Hofmann NVH chassis dynamometers are available as standard in single roller, 4×2, 4×4, and independent configurations.

The rollers are available from 1.8m to 2.5m in diameter, running in hydrodynamic or roller element bearings. The roller assemblies are acoustically attenuated to minimise the effect of noise generation and amplification. They can be either coated to represent a road surface or fitted with interchangeable road surface simulation shells.

Trunnion mounted motors compensate for system losses and simulate road load forces, vehicle inertia and gradients. These motors are installed in isolated areas and connected to the rolls by torsionally tuned couplings and drive shafts. Acoustic shaft seals, roll covers, and breakthrough seals around the rollers ensure effective noise containment. Wheelbase adjustment is available to accommodate different vehicles. Roller centres can be set automatically as part of the road load model information, or set to the user’s specific dimensions. The dynamometer baseframe is mounted on a moving carriage.

The dynamometer is provided with real-time control processor, Distributed I/O architecture and a GUI running the Windows™ 10 operating system. A powerful data logger can store system and vehicle parameters. A fully configurable real-time graphic package displays this information on screen.

A central server function and host computer interface are available to enable data to be passed in either direction.

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TYPICAL SPECIFICATION

Speed range 280 km/h
Absorption power per axle 278 kW
(100 – 280 km/h)
Force per axle 10000 N
(0 – 100 km/h)
Inertia simulation range 600 – 5400 kg
Wheelbase adjustment 2260 mm – 4700 mm
Roller diameter 1800 mm x 2 off
Width 610 mm
Spacing 1016 mm
Acoustic performance at 100 km/h 45 dBA (typical)