Measuring and testing – Instrument proving or calibrating – Dynamometer
Patent
1998-02-21
2000-01-04
Raevis, Robert
Measuring and testing
Instrument proving or calibrating
Dynamometer
G01L 100
Patent
active
06009740&
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to a system and method for incrementally applying weights to a dynamometer to calibrate the dynamometer in a fast, safe and accurate manner.
BACKGROUND
Chassis dynamometers are used in a wide variety of applications, particularly in connection with the testing of motor vehicle engine emissions pursuant to Environmental Protection Agency (EPA) emissions regulations for motor vehicles. Such dynamometers typically incorporate one or more "rolls" which are driven by one or more wheels of a test vehicle. The rolls are typically coupled to an input shaft of some form of power absorption, or exchange device which provides a controlled degree of rolling resistance to the rolls to simulate load and inertia forces normally encountered during vehicle operation. A vehicle engine must overcome inertia forces in order to accelerate or decelerate the vehicle. The engine must also overcome breakaway frictional and rolling frictional forces, as well as adapt to wind forces, generally referred to as road load forces. Dynamometers are designed to simulate the conditions that a vehicle is faced with during actual road operation.
In an effort to ensure that the dynamometer accurately measures torque, exhibits little hysteresis, and accounts for drift, calibration of the dynamometer is required on a periodic basis.
A dynamometer's torque measuring system may be calibrated using the deadweight method. The deadweight method applies known torques on the dynamometer calibration arm, against which the dynamometer output is calibrated. The known torques are produced by calibration weights. Accordingly, a series of calibration weights are applied to a calibration arm or arbor and weight hanger to simulate positive and negative torques. Unfortunately, since the dynamometer is located below the floor level of the test cell in a confined space, the application of the weights onto the calibration arm is an awkward and potentially hazardous process.
With previous dynamometer designs, calibration of the dynamometer required a person to lower, for instance, 50 pound weights, into a confined space, and then subsequently place the weights one at a time on the weight hanger for incremental calibration. The calibration operator would incrementally place weight on the hanger to simulate the varying loads applied during vehicle testing. As an example, for dynamometers testing light-duty vehicles, weights in the range of 650 pounds would have to be applied to the calibration hanger. For complete calibration, an incremental weight, for example 50 pounds, is applied to the calibration hanger, after which the calibration weight is steadied on the calibration arm to obtain a stable reading. For each incremental weight up to the recommended total weight, for example 650 pounds, a calibration reading is taken.
Accordingly, for each of these calibration weights, under the previous designs, a calibration operator would have to carry the calibration weight, for example 50 pounds, and place it on the calibration hanger, until the desired load, for example 650 pounds, was attained. These calibration designs thus posed a significant safety hazard to the employees in charge of calibration, as this process required lifting, sliding and manipulating a substantial amount of weights, with the constant danger of back or other related injuries resulting from the heavy load and strain. In view of this awkward, time-consuming and straining procedure, calibrations of dynamometers were only done when absolutely necessary.
SUMMARY OF THE INVENTION
It is, therefore, an object of the present invention to provide a system and method for deadweight calibrating a dynamometer that eliminates the requirements of manual weight manipulation.
It is another object of the present invention to provide a system and method for deadweight calibrating a dynamometer that is simple, accurate, and safe.
In carrying out the above objects and other objects and features of the present invention, a system for deadweight calibrating a dynamometer is p
REFERENCES:
patent: 4637481 (1987-01-01), Shoemaker
Devendorf David P.
Kwok Tennyson
Noguchi Shinji
Vetter Richard
Horiba Instruments Inc.
Raevis Robert
LandOfFree
System and method for deadweight calibrating a dynamometer does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with System and method for deadweight calibrating a dynamometer, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and System and method for deadweight calibrating a dynamometer will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1063774