Measuring and testing – Simulating operating condition – Marine
Reexamination Certificate
1998-07-23
2001-05-22
Noori, Max (Department: 2855)
Measuring and testing
Simulating operating condition
Marine
C073S570000, C073S011060, C073S118040
Reexamination Certificate
active
06234011
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an apparatus and a method for testing the performance of a railroad vehicle or an automobile and, more specifically, to an apparatus and a method for testing a truck of a railroad vehicle or a suspension of an automobile.
Since the truck of a railroad vehicle and the suspension of an automobile are important parts that determine the degree of comfortability of a ride in the vehicle and the stability during running, it is necessary to evaluate the performance of the truck or suspension before the development of a vehicle. In particular, there is a possibility that a truck may make a snake action during high-speed running. It is an important subject to avoid the snake action.
At present, tests are conducted by using an actual truck to clarify how the phenomenon of snake action occurs during running of a vehicle, because it is difficult to analyze the snake action by computer simulation mainly for the following reasons:
(1) It is difficult to analyze the contact surfaces between the wheels and the rails.
(2) Trucks have many structure-related nonlinear factors.
Among the tests using an actual truck is what is called an actual vehicle test in which an actual vehicle is run on actual rails. On the other hand, an on-base test is also conducted in which a truck is mounted on rail wheels. In the on-base test, a plurality of wheels are rotatably joined to the bottom portion of a truck and a weight frame having a weight corresponding to that of a vehicle is mounted on the top-surface side of the truck. The wheels, the truck, and the weight frame simulate a railroad vehicle. On the other hand, to simulate railroad rails of infinite length, a plurality of cylindrical rollers are rotatably provided on a base. The wheels provided at the bottom of the truck and the cylindrical rollers are located at positions that correspond to each other. The running characteristics of the railroad vehicle on rails can be simulated by mounting a mock vehicle on the rollers and rotating the rollers with one end of the truck fixed to a coupler. An example of such a testing apparatus is described in Hirotsu et al., “Simulation of Snake Action of Railroad Vehicles,” Transactions of the Japan Society of Mechanical Engineers, Vol. 532 Ed. C, No. 90-0204A, pp. 65-72, December 1990.
However, in the above conventional actual vehicle test, the results of each test is are results obtained one combination of conditions (such as a vehicle structure, rail states, and running conditions). Since the actual vehicle test involves a number of parameters, it is difficult to determine the running performance and the degree of comfortability of a ride under another combination of conditions based on the experimental results obtained. In the on-base test, since the mock vehicle is bound by the coupler, relative positions of a vehicle in the running direction are determined in accordance with whether the wheels are rotating in the normal or reverse direction. However, in this case, it is difficult to take the characteristics of the vehicle into account, and the motion of the mock vehicle is different from that of an actual vehicle. Therefore, satisfactory test results cannot be obtained. Further, trucks having an active damper that have been developed in recent years require that a movement state be fed back as a feedback signal. Therefore, there is a problem that the on-base test cannot accommodate such trucks.
SUMMARY OF THE INVENTION
The present invention has been made in view of the above problems in the art, and an object of the invention is therefore to enable a performance test, or a durability test mainly on a truck of a railroad vehicle, to be conducted easily while conditions are changed in various manners.
Another object of the invention is to conduct a test that simulates an actual railroad vehicle or automobile with high accuracy by combining a computer simulation and a model test.
A further object of the invention is to conduct, on a truck of a railroad vehicle or a suspension of an automobile, with a simple configuration, a performance test or a durability test that is equivalent to an actual vehicle test.
To attain the above objects, according to a first aspect of the invention, there is provided an apparatus for testing a vehicle that runs on a running surface, comprising freely rotatable rotary bodies that simulate the running surface; a mock vehicle having wheels and being provided on the rotary bodies; and a digital computer having storing means for storing a numerical model that is virtually connected to the mock vehicle.
To attain the above objects, according to a second aspect of the invention, there is provided an apparatus for testing a vehicle that runs on rails, comprising first and second rail simulating means each of which simulates rails and has a plurality of freely rotatable rotary bodies; first and second mock vehicles provided on the first and second rail simulating means, respectively, and each having a plurality of rotatable rail wheels; first and second vibrating means for vibrating the first and second mock vehicles, respectively; a digital computer that stores a numerical model of a vehicle body virtually connected to both of the first and second mock vehicles; first and second reaction force measuring means for measuring reaction forces that are exerted on the first and second mock vehicles, respectively; and control means for controlling the first and second vibrating means based on measured reaction force values, respectively, wherein an actual vehicle is simulated by using the first and second mock vehicles and the numerical model.
To attain the above objects, according to a third aspect of the invention, there is provided a method for testing a vehicle that runs on a running surface, comprising the steps of driving a mock running surface; measuring a reaction force generated from a truck; inputting a measured reaction force value to a digital computer; calculating, with the digital computer, a vehicle movement after a lapse of a preset time (&Dgr;t) from a point in time when the reaction force was measured by using the measured reaction force value and a numerical model of a vehicle body that has been input in advance to the digital computer; calculating, with the digital computer, a vibration instruction signal indicating vibration to be applied to a mock vehicle based on the calculated vehicle movement; and driving a vibrator based on the vibration instruction signal after a lapse of the preset time (&Dgr;t).
To attain the above objects, according to a fourth aspect of the invention, there is provided a method for testing a vehicle having a plurality of mock vehicles that runs on rails, comprising the steps of rotating mock rails; measuring reaction forces generated from the respective mock vehicles; inputting measured reaction force values to a digital computer; calculating, with the digital computer, movements of the respective mock vehicles after a lapse of a preset time (&Dgr;t) from a time point when the reaction forces were measured by using the measured reaction force values and a numerical model of a vehicle body that has been input in advance to the digital computer and virtually connected to each of the mock vehicles; calculating, with the digital computer, vibration instruction signals for vibrators for vibrating the mock vehicles based on the calculated vehicle movements, respectively; and driving, with controllers, the vibrators after a lapse of the preset time (At) based on the vibration instruction signals, respectively.
Preferably, in the apparatus according to the first aspect of the invention, there are further provided vibrating means for vibrating the mock vehicle; reaction force measuring means for measuring a reaction force that is exerted on the mock vehicle; and control means for controlling the vibrating means, wherein the running surface is rails and the vehicle is a railroad vehicle.
Alternatively, there are further provided vibrating means for vibrating the mock vehicle; reaction force measuring.
Horiuchi Toshihiko
Sugano Masaharu
Yamagishi Wataru
Yamakado Makoto
Evenson, McKeown, Edwards & Lenahan P.L.L.C.
Hitachi , Ltd.
Noori Max
Stevens Maurice
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