Engine test stand

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An engine test stand is a facility used to develop, characterize and test engines. The facility, often offered as a product to automotive OEMs, allows engine operation in different operating regimes and offers measurement of several physical variables associated with the engine operation.

A sophisticated engine test stand houses several sensors (or transducers), data acquisition features and actuators to control the engine state. The sensors would measure several physical variables of interest which typically include:

crankshaft torque
angular velocity of crankshaft
intake air and fuel consumption rates, often detected using volumetric and/or gravimetric measurement methods
air-fuel ratio for the intake mixture, often detected using an exhaust gas oxygen sensor
concentration of environment pollutants in the exhaust gas e.g. carbon monoxide, different configurations of hydrocarbons and nitric oxides, sulphur dioxide, particulate matter
temperatures and gas pressures at several locations on the engine body e.g. engine oil temperature, spark plug temperature, exhaust gas temperature, intake manifold pressure
atmospheric conditions such as temperature, pressure, humidity

Information gathered through the sensors is often processed and logged through data acquisition systems. Actuators allow for attaining a desired engine state (often characterized as a unique combination of engine torque and speed). For gasoline engines, the actuators may include an intake throttle actuator, a loading device for the engine such as an induction motor. The engine test stands are often custom-packaged considering requirements of the OEM customer. They often include a microcontroller based feedback control system with following features:

closed loop desired speed operation (useful towards characterization of steady-state or transient engine performance)
closed loop desired torque operation (useful towards emulation of in-vehicle, on-road scenarios, thereby enabling an alternate way of characterization of steady-state or transient engine performance)

1 Categories of engine test stands depending on their purpose
2 Engine testing for R&D
3 See also
4 Manufacturer of engine test stands and components

[edit] Categories of engine test stands depending on their purpose

Research and Development of engines, typically at an OEM laboratory
Tuning of in-use engines, typically at service centers or at racing
End of production line at an OEM factory

[edit] Engine testing for R&D

Image:TitanTestStand.jpg

Research and Development activities on engines at automobile OEMs have necessitated sophisticated engine test stands. An automobile OEM is interested in developing engines that serve the following three-fold objective:

as much high fuel efficiency as possible
as much better drivability and durability as possible
comliance to relevant emission legislations

Consequently, an R&D engine test stands allow for a full-fledge engine development exercise through measurement, control and record of several relevant engine variables.

Examples for typical tests include:

tests to determine fuel efficiency and drivability: torque-speed performance test under steady-state and transient conditions
tests to determine durability: aging tests, oil and lubrication tests
tests to determine compliance to relevant emission legislations: volumetric and mass emission tests over stated emission test cycles
tests to gain more knowledge about the engine itself: engine mapping exercise or development of multidimensional input-output maps among different engine variables. e.g. a map from intake manifold pressure and engine speed to intake air flow rate.