Measuring and testing – Dynamometers – Responsive to torque
Patent
1985-11-27
1987-06-02
Ruehl, Charles A.
Measuring and testing
Dynamometers
Responsive to torque
7386214, G01L 316, G01L 320
Patent
active
046693181
DESCRIPTION:
BRIEF SUMMARY
This invention relates to apparatus for dynamometer testing of motor vehicles, that is, apparatus adapted to be drivingly connected with a driven vehicle output shaft and comprising means for measuring one or more quantities significant to the performance of the engine and the transmission, such as the torque that the driven shaft applies to a power-absorbing device (brake) forming part of the test apparatus.
Known apparatus for dynamometer testing of motor vehicles usually comprises a ramp or a platform or some other kind of support for the entire vehicle or the end of the vehicle where the driven shaft is located. The support is provided with friction rollers connected to the dynamometer system which are engaged by the tires of the driven vehicle wheels. In dynamometer test apparatus of this type the unavoidable and unpredictably variable slipping and friction between the tires and the friction rollers often causes unacceptable inaccuracy of the test result.
In other known dynamometer test apparatus the friction rollers are replaced by shaft couplings through which the driven vehicle shaft is non-slippingly connected with the dynamometer system. Such apparatus comprises a hoisting device for raising the vehicle so that the driven wheels can be rotated without engaging the supporting structure. The shaft couplings are flexible so that substantially only torque is applied to the dynamometer system by the driven shaft.
Both types of dynamometer test apparatus are bulky and costly. For this and other reasons they are used almost exclusively in large maintenance installations and laboratories where dynamometer testing is carried out frequently enough to warrant the installation of bulky and expensive test equipment.
An object of the invention is to provide dynamometer test apparatus that does not require a platform or similar support for the vehicle and thus is easy to transport, that lends itself to use both in maintenance installations or laboratories and in the field, and that is cheaper than the known stationary apparatus and yet permits testing with the same degree of accuracy as known apparatus of the type having a non-slip connection of the driven shaft to the dynamometer system.
The invention is directed to apparatus for dynamometer testing of motor vehicles which, like the known types of apparatus discussed above, comprises a dynamometer having a stator, a rotor mounted for rotation in the stator and engageable with a driven vehicle power output shaft for rotation therewith, a stator holder supporting the stator and connected therewith to carry the torque loading on the dynamometer, and means for measuring the torque loading on the dynamometer. According to the invention, such apparatus is characterised in that the rotor is provided with means for flexurally rigid coupling of the rotor to the driven vehicle shaft adjacent one side of the stator holder, in that the greater portion of the stator and the rotor extend in cantilever fashion from the opposite side of the stator holder, and in that the stator holder is provided with a ground engaging support.
Thus, according to the invention, the dynamometer rotor is adapted to have a flexurally rigid connection with the driven vehicle shaft, and the stator holder also serves the purpose of carrying the weight of the dynamometer and at least part of the weight of the vehicle.
Since in actual practice the driven vehicle shaft always has a differential and thus comprises two half-shafts which are driven from a common power source but are rotatable relative to each other, the use of apparatus according to the invention comprises the use of two basically identical test units which are connected to different half-shafts. In order that the difference between the rotational speeds of the half-shafts may be kept within a predetermined narrow range, the two test units may be controlled by a common measuring and control system which varies the load absorbed by one or the other of the units in dependence of a measured speed difference .
A more detailed description of
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Engstrom Nils G.
Ruehl Charles A.
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