초록 ▼

The present invention is directed to providing an inexpensive, yet effective, simulation for measuring the sound level of the muffler contribution to the total sound created by a truck during a drive-by. The simulation method includes disconnecting a drive shaft of the drive mechanism of the truck a

The present invention is directed to providing an inexpensive, yet effective, simulation for measuring the sound level of the muffler contribution to the total sound created by a truck during a drive-by. The simulation method includes disconnecting a drive shaft of the drive mechanism of the truck and installing a dynamometer. When the throttle of the engine is increased, the dynamometer applies a load so that the acceleration rate of the drive mechanism compares similarly to the acceleration rates of a truck during an actual drive-by test in accordance with CFR 40, part 202. Sound barriers are placed around sounds sources other than the muffler of the truck. Microphones are used to sense the sound during the test for recording by strip-chart recorders.

대표청구항 ▼

Apparatus for producing operating conditions and measuring sound of an operable vehicle during a stationary simulated drive-by test, said apparatus comprising: an actual vehicle including wheels and means for driving said wheels, said driving means including an engine with means for exhausting gases

Apparatus for producing operating conditions and measuring sound of an operable vehicle during a stationary simulated drive-by test, said apparatus comprising: an actual vehicle including wheels and means for driving said wheels, said driving means including an engine with means for exhausting gases, said exhausting means including a muffler, said driving means being disconnected with respect to driving said wheels; a dynamometer; means attached to said actual vehicle for connecting said dynamometer to said driving means; means for controlling said dynamometer to simulate operational loading of said engine; means for measuring sound, said measuring means including a plurality of regularly spaced microphones along a first line parallel to and spaced from a second line, said second line being an imaginary direction of travel of said actual vehicle; and means for at least partially shielding sound emanating from said driving means from said microphones, said muffler being unshielded by said shielding means with respect to said microphones; whereby said shielding means shields much of the sound from said driving means, except from said muffler, so that said sound measuring means measures primarily muffler sound in the operational environment of said muffler even though said actual vehicle is not moving, said dynamometer and said controlling means simulating operational loading of said engine.