RU217339U1 - Installation for measuring the coefficient of adhesion during complex movement of a blocked automobile wheel with a road surface - Google Patents

Abstract

The utility model relates to measuring technology, in particular to devices for quickly measuring the friction coefficient of a locked automobile wheel as it slides on a hard road surface, and can be used in the investigation of traffic accidents. The installation contains a horizontally located movable frame, on which more than one rack is fixed, and a carrier frame with an automobile wheel and holes for the racks, through which it is fastened to the movable frame. The movable and carrier frames are made of circular cross section, in addition, the carrier frame is made with constructive through channels in the side surface and horizontal rods, which have the possibility of horizontal radial movement along the constructive through channels relative to the carrier frame to the required angle of rotation. Spring-type shock absorbers are additionally installed between the movable and carrier frames. The proposed installation is mobile, has small overall dimensions, can be used in various conditions directly at the scene of an accident and allows you to equally measure both direct braking and side slip at different wheel angles, i.e. the installation is universal.

Description

The utility model relates to measuring technology, in particular to devices for quickly measuring the friction coefficient of a locked car wheel as it slides on a hard road surface, and can be used in the investigation of traffic accidents (RTA).

Known "Tire tester for determining the coefficient of transverse adhesion of an elastic tire of an automobile wheel" (RU No. 181521, publ. 07/17/2018), which contains two measuring wheels installed symmetrically relative to the longitudinal axis of the tire tester, a force measuring sensor. Two measuring wheels are mounted on independent lever suspensions with longitudinal movement of the levers in rotary frames with the possibility of their simultaneous angular movement by a screw mechanism located on the tire tester's supporting frame and rigid fixation with bolts at the set side slip angles of the measuring wheels with the possibility of measuring with the required accuracy by angular indicators. movements. The axes of the measuring wheels and the measuring tongue of the tire tester are mounted on movable supports located on the suspension arms of the measuring wheels and the bearing frame of the tire tester, with the possibility of their movement only in the directions of the action of the lateral and the resulting total reactions in the contact patches of the elastic tires of the measuring wheels, and are connected to the force-measuring sensors mounted on the suspension arms of the measuring wheels and the tire tester's carrier frame, metal ballast weights placed symmetrically with respect to the longitudinal axis of the tire tester and the measuring wheels' axes, on the brackets of the tire tester's carrier frame with the possibility of a discrete increase in the normal load on the measuring wheels while maintaining a low center location mass of the tire tester. The disadvantage of this technical device is that it allows you to measure only the lateral and total reactions in the contact patch of an elastic tire of an automobile wheel when rolling with side slip.

Known portable impact device MADI (Nemchinov M.V. Grip quality of road surfaces and vehicle traffic safety. M.: Transport, 1985, p. 201-202), which allows you to simulate the process of sliding a locked car wheel on the road surface, which consists of two rubber imitators of push rods connected by hinges with a movable coupling and rubber imitators, a support rod, in the upper part of which a movable load is fixed, springs and a registering washer.

This device does not allow to reproduce with high accuracy the movement (friction, sliding) of a particular automobile wheel, since it does not imitate its design as such with rubber simulators (there is no wheel tire shape and differentiable air pressure in it, the properties of simulating grip qualities are limited by the characteristics of simulators), which entails behind the errors. In addition, the disadvantage of the device is that before use, the device must first be calibrated on level ground, then on the test site.

Known technical solution "Dynamometric trolley design E.G. Podlikha (MADI) ”(Borovsky B.E. Road traffic safety. - L .: Lenizdat, 1984. - 304 p., ill., p. 102-103), consisting of a towing device, a wheel with a tire, a supporting frame , shock absorber loading frame and metal discs as cargo.

The main disadvantage of the described installation is that its operation is limited to the use of a non-removable universal measuring automobile wheel (regardless of the purpose of measurement), which significantly reduces the possibility of modeling the behavior of an automobile wheel associated with a specific accident on the road surface under various conditions, and, consequently, the reliability and accuracy of measurements. Indeed, the grip qualities of the road are determined mainly by its roughness and degree of moisture, while the same qualities of the car depend on a number of factors that have nothing to do with the quality of the pavement in use, in particular, the state of the contact surface of the car wheel (its tire tread - the wear height of the lugs, the geometric pattern of the tread, etc.), the degree of its inflation and its design features (diameter, profile height of the sidewall of the tire, etc.), the load on the wheel (which changes during braking due to the redistribution of forces ) etc. Also, the disadvantages include the fact that this device (however, like others) has the ability to measure only the parameters of direct braking (the measurement of side slip parameters is excluded by the design feature of the installation) of the test wheel on the test surface.

Known dynamometric installation for measuring the coefficient of adhesion of a locked automobile wheel with a road surface (Installation for measuring the coefficient of adhesion of a blocked automobile wheel with a road surface (RU No. 159197, publ. 10.02. load shock absorber and metal discs as cargo.

The main disadvantage of the described installation is that its operation is limited to two measurement phases - the coefficient of adhesion during direct braking and the coefficient of adhesion during side slip, which significantly reduces the possibility of modeling the behavior of an automobile wheel in a state of complex movement (at different angles of the longitudinal axis of the wheel relative to its displacement vector). ) on the road surface under various conditions, and hence the reliability, variability and accuracy of the measurements.

As a prototype, the technical solution "Installation for measuring the coefficient of adhesion during complex movement of a blocked automobile wheel with a road surface" (RU No. 210446, publ. 15.04.2022) was adopted, containing a horizontally located movable frame, on which more than one rack is fixed, and a supporting frame with a car wheel and holes for racks through which it is attached to a movable frame. The movable and carrier frames are made of circular cross section, in addition, the carrier frame is made with constructive through channels in the side surface and horizontal rods, which have the possibility of horizontal radial movement along the constructive through channels relative to the carrier frame to the required angle of rotation.

The disadvantage of this technical solution is the lack of the possibility of simulating the nature of the translational movement of an automobile wheel, taking into account the depreciation properties of the vehicle suspension, which does not allow obtaining experimental data with a minimum threshold of measurement error.

The objective of the utility model is to expand the functionality of the device by providing a measurement of the coefficient of adhesion of the wheel to the road surface in the state of side slip at different slip angles to more reliably simulate the movement of the wheel during complex movement, taking into account the sprung mass of the suspension.

This is achieved by the fact that the installation for measuring the coefficient of adhesion during complex movement of a blocked automobile wheel with a road surface, containing a horizontally located movable frame, on which more than one rack is fixed and a carrier frame with an automobile wheel and holes for the racks, through which it is fastened to the movable frame, while the movable and carrier frames are made of circular cross section, in addition, the carrier frame is made with structural through channels in the side surface and horizontal rods that have the possibility of horizontal radial movement along the constructive through channels relative to the carrier frame at the required angle of rotation, moreover, between the movable and bearing frames are additionally equipped with spring-type shock absorbers.

The technical result lies in the constructive versatility of the installation, which allows you to equally measure the coefficient of adhesion of a locked car wheel associated with a specific accident with the road surface directly at the scene of the accident, both with direct braking and with side sliding at different angles of the wheel relative to the drag vector and taking into account the depreciation properties of the vehicle suspension.

The essence of the installation for measuring the coefficient of adhesion of a blocked automobile wheel with a road surface is illustrated by graphic images, which show:

Fig. 1 – general view of the installation.

Fig. 2, 3 – view of the installation from above and from the side.

Fig. 4 – general view of the installation.

The installation for measuring the coefficient of adhesion of a blocked automobile wheel with a road surface (Fig. 1, 3) contains a horizontally located round movable frame 1, on the bottom of which two wheels 2 of free rotation of the bearing type are diagonally mounted on each side of the longitudinal axis of the installation. To the upper part of the movable frame 1 are rigidly fixed, for example, by welding, vertical guide racks 3, at least two on each side of the longitudinal axis of the installation. Vertical guide racks 3 are designed to be installed on the movable frame 1 of the round carrier frame 4 through the corresponding through holes made in the walls of the carrier frame 4. Spring-type shock absorbers 12 are additionally installed between the movable and carrier frames, designed to simulate the suspension of a car. Two rods 5 are attached to the side wall of the carrier frame 4, on which, for example, a car wheel 7 is attached through the flange 6. The rods 5 through the flanges 8 and 9 are bolted to the side wall of the carrier frame 4 through constructive through channels 10 cut in this wall. . On the upper surface of the carrier frame 4, a towing device 11 is fixed coaxially to the longitudinal axis (Fig. 2). To take readings and simulate the load, a measuring device is used, for example, a dynamometer, and additional weights, up to a total of 120 kg (not shown in the figure).

Installation example.

To measure the coefficient of adhesion during direct braking, a round carrier frame 4 through through holes, using vertical guide posts 3, is installed on a round movable frame 1, shock absorbers 12 are fixed. in an accident. Through flanges 8 and 9 and structural through channels 10, the rods 5 are attached to the carrier frame 4. With this connection, the carrier frame 4 moves freely up and down relative to the vertical guide posts 3 (movement is limited by the structural dimensions of the wheel) and can be dismantled from the movable frame 1 for transportation. Structural through channels 10 allow the rods 5 with the wheel 7 fixed on them to be moved radially inside the carrier frame 4, which makes it possible to measure the side slip coefficient of the wheel 7 in various angular positions. To simulate the actual load on the wheel of the car, the supporting frame 4 is loaded with additional loads (for example, up to 120 kg in total) and the tension of the damping elements 12 is adjusted. at a pressure in the wheel of 0.2 MPa (or otherwise, if it was different at the time of the accident). The towing device 11 is rigidly coupled through a measuring device, for example, a dynamometer (not shown in Fig.), with a vehicle that transports the installation, using wheels 2 mounted on the bottom of the movable frame 1, along a section of the road at a constant predetermined speed in order to measure the coefficient clutch. To measure the coefficient of adhesion during side slip, the rods 5 are moved radially inside the carrier frame 4 along the constructive through channels 10, setting the required angle of the wheel for measurement. Further work on measuring the coefficient of adhesion during direct braking or side slip is reduced to moving the device in a guided mode along the road surface. The dynamometer measures the traction force, on the basis of which the desired coefficient is calculated by the formula

,

,

where m is the load on the wheel, kg;

V is the speed of movement of the installation, m/s;

S is the installation displacement, m;

q is the specific pressure in the wheel, MPa;

A - the area of the contact patch of the tire with the supporting surface, m ² ;

P - towing force, N.

The proposed installation is mobile, has small overall dimensions, can be used in various conditions directly at the scene of an accident (which, due to the difficulty of maintaining road conditions at the time of an accident over time, provides the necessary efficiency and quality of measurement), and also allows the use of a wide range of wheels ( regardless of the design dimensions) of passenger cars, providing the variability of their use (wheel inflation, wear and tread pattern of the tire, the height of its lugs, etc.), and also allows you to equally measure both direct braking and side slip at different angles of rotation of the wheels, taking into account the damping properties of the suspension, which increases the accuracy of measurements, i.e. the installation is universal.

Claims (1)

Installation for measuring the friction coefficient during complex movement of a blocked automobile wheel with a road surface, containing a horizontally located movable frame on which more than one rack is fixed, and a carrier frame with an automobile wheel and holes for the racks through which it is fastened to the movable frame, while the movable and carrier frames are made of circular cross section, in addition, the carrier frame is made with structural through channels in the side surface and horizontal rods, which have the possibility of horizontal radial movement along the structural through channels relative to the carrier frame at the required angle of rotation, characterized in that between the movable and carrier the frames are additionally equipped with spring-type shock absorbers.

Images