UA35358A - appliance for measurement of accelerations on equipped with springs sections of mobile stock - Google Patents

Abstract

The invention relates to rail transport, in particular to evaluation of dynamical (riding) properties of mobile stock. The appliance for measurement of accelerations on equipped with springs sections of mobile stock has indicators of accelerations, indicators of absolute angular displacements.

Description

The invention relates to railway transport, in particular, to the assessment of dynamic (driving) qualities of rolling stock.

In the process of experimental research, linear accelerations of individual elements of rolling stock, for example, braced parts, are measured.

At the same time, acceleration is usually measured in three directions according to the axes of the spatial coordinate system: longitudinal (X), transverse (Y) and vertical (7). For this, acceleration sensors are installed on the object, for example, on the floor of the railway car body, orienting their axes according to the coordinate system.

But when the object moves, angular displacements of its elements inevitably occur, and therefore traditional measurements of accelerations have relatively large errors.

It is known that when measuring acceleration, of course, acceleration sensors are installed on the body in the area of the heel or in the middle part of the body ("Wagon! грузовье и пассижанские. Метод! испитания на прочность и ходовье качастье" RD 24.050.37.95). But in this case, in addition to measuring accelerations, the gravitational field of the Earth also acts on the acceleration sensors, and therefore the signal at the sensor output is the sum of two components. One of the components is a value proportional to the projection of the acceleration vector of the earth's gravity on an axis that coincides with the measurement axis of the sensor, which, when the object moves, also makes angular movements in the Earth's gravitational field. Thus, during angular movements in the Earth's gravitational field, an additional signal caused by its angular movements appears at the output of the linear acceleration sensor. That is, this second component is a source of error when measuring small (0.1-0.3)9 accelerations, which is typical for low-frequency dynamic processes, for example, when researching the running qualities of passenger cars.

If the measuring axis of the sensor is parallel to the force of the earth's gravity, then the value of the additional signal (Shi ) is determined by the expression

Op-Kka sov ?, where: K is the sensitivity of the sensor, d is the acceleration of the earth's gravity, Ф is the angle of inclination of the measuring axis of the sensor in the vertical plane relative to the earth's surface.

If the measuring axis of the sensor is perpendicular to the vector 9, that is, it is in the horizontal plane, then the value of the additional signal (y would be sk 9 vip ?.

If the vehicle is moving, angular oscillations appear, as a rule, relative to all three axes of the spatial coordinate system. If we assume that axis 7 is directed vertically parallel to the force of the earth's gravity, axis X - along the track, and axis Y - across the track, then the output signal of the sensor, which is the sum of the two components, will be determined

U xz Oh u,

X from Han to Tsu

In x Ul yu Ox where: 7, x, y - output signals of sensors installed along axes 2, X, Y, respectively; lin, Khlin, Ulin - ACTUAL linear accelerations along axes 2, X, Y, respectively;

Oh, Tsu - signals corresponding to the angular movements of the sensor relative to the x and y axes, respectively.

Thus, from the given equations, it follows that the output signals of acceleration sensors have two components: a useful signal that corresponds to the measured acceleration, and an additional signal that corresponds to angular displacements. During normal measurements with normal acceleration sensors, it is impossible to separate these components.

The analogue of the claimed invention that is closest to the invention in terms of its technical essence and the achieved result is a. with. USSR "Device for measuring acceleration" Mo 1670631 c 01 15/08. The device consists of a case in which there is an inertial mass, springs with adjusting screws, an acceleration indicator, a flag with holes, and a Hook hinge. For greater stability of the housing in a vertical position, the bottom of the housing is made of material whose total mass is comparable to the mass of an inertial body. The body is in a vessel filled with liquid and is a float. This keeps the hull and also the inertial body in a vertical position relative to the Earth's horizon. The body is connected to the bottom of the vessel with the help of a ball joint located in the center of the bottom of the body.

The principle of operation of the acceleration measuring device is based on the transformation of the force that occurs during the accelerated movement of an inertial body into a proportional movement of the flag.

However, due to the fact that the body of the device for measuring accelerations is located in a vessel with liquid and is fixed with a hinge, it is always maintained in a strictly vertical position due to the pushing force of the liquid. The disadvantage of this device is the error associated with the inclination of the body during the movement of the object on which the device for measuring accelerations is fixed. If the pushing force acting on the body is greater than the force of gravity, then the body will indeed be in a vertical position, but at the same time this system is a pendulum that can oscillate relative to the hinge. At the same time, the length of the pendulum is equal to the distance from the point of suspension of the hinge to the center of mass of the body.

In general, the natural frequency 9 of such a system is determined by the expression:

Fital where t is the mass of the pendulum, I is the length of the pendulum, I is the moment of inertia of the pendulum.

In our case, UR is where P is the repulsive force.

If the weight of the body and the pushing force are the same, then there will be no oscillations, but the body will lose stability, and even with a slight inclination, the center of gravity of the body and the center of gravity of the displaced liquid will no longer be on the same vertical.

The essence of the proposed invention lies in the fact that the device for measuring the accelerations of the sprung parts of the rolling stock includes both acceleration sensors, which are used to measure the acceleration, and absolute angular displacement sensors, the signal of which is used to compensate for errors caused by the angular displacement of the sensors.

In fig. a functional diagram of the proposed device is given. The device consists of acceleration sensors 1, 2, 3, installed parallel to the axes 72, X, M of the spatial coordinate system on the sprung part of the rolling stock, the outputs of which are connected to the inputs of matching devices 4, 5, 6. The inputs of matching devices are connected to the inputs of adders 7, 8, 9. Sensors of absolute angular displacements 14, 15 are also installed on the braced part of the rolling stock, the outputs of which are connected to the inputs of matching devices 10, 11, 12, 13, and the outputs of the latter are connected to the second and third inputs of adders. The outputs of the adders are connected to the inputs of the recorder 16.

The device works like this. The signal from the output of the acceleration sensor 1, installed on the sprung part of the rolling stock in the longitudinal direction (X), enters the input of the matching device 4, where the signal is amplified, and from the output of the sensor 14 of the absolute angle of movement relative to the Y axis, it enters the input of the matching device 10, and from its output to the second input of the adder 7. From the output of the adder, the corrected signal corresponding to the linear acceleration in the X direction enters the input of the register 16.

The signal from the output of the acceleration sensor 2, installed in the transverse direction (U) on the sprung part of the rolling stock, enters the input of the matching device 5, which works similarly to the device 4, from its output the signal enters the first input of the adder 8, and its second input enters the signal from the output of the matching device 11, the input of which is connected to the output of the sensor 15 of the absolute displacement of the angle relative to the U axis. From the output of the adder, the signal enters the input of the recording device 16.

The signal from the output of the acceleration sensor 3, installed on the braced part in the vertical direction (7) is fed to the input of the matching device b, and from its output to the first input of the adder 9. The second and third inputs of the adder 9 receive signals from the outputs of the matching devices 11 and 12 , the inputs of which are connected to the outputs of absolute angular displacement sensors 14 and 15. The signal from the output of the adder 9 is proportional only to the linear vertical acceleration. From the output of the adder, the signal enters the input of the recording device, 16.

The technical result of the claimed invention consists in the possibility of measuring only linear accelerations.

The proposed device can be used without additional costs wherever it is necessary to measure acceleration on the spring-loaded parts of railway rolling stock. , i ; » | i and

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Claims (1)

A device for measuring accelerations on sprung parts of rolling stock, which contains acceleration sensors installed in accordance with selected directions, and which is distinguished by the fact that the device additionally contains sensors of absolute angular displacements, the outputs of which are connected to the inputs of matching devices, and the outputs of the latter are connected to the second inputs of adders , and their first inputs are connected to the outputs of matching devices, the inputs of which are connected to the outputs.