RU2562355C1 - Device to determine wheel grip coefficient regarding artificial surface - Google Patents

Abstract

FIELD: measurement equipment.

SUBSTANCE: device comprises a measuring wheel, a frame, a registration block and a controlled power supply block, the first outlet of the registration block is connected to the first inlet of the controlled power supply block. Additionally the device includes a master vehicle axle, the second measuring wheel, a controlled brake, the first and second torque sensors. The controlled brake via the master vehicle axle is mechanically connected to the first and second measuring wheels, and the first and second torque sensors are placed accordingly on the first and second measuring wheels. The torque sensors have two outlets - an outlet of the torque and speed of the measuring wheel rotation, which are accordingly connected from the first torque sensor to the first and second inlets of the registration block, and from the second sensor to the third and fourth inlets of the registration block. The second outlet of the registration block is the outlet of the critical grip coefficient at rest Kgrip1, and the third outlet of the registration block is the outlet of the grip coefficient Kgrip2 of the road surface, measured by the second measuring wheel, or the grip coefficient of a landing strip. A source of power supply is connected to the second inlet of the controlled power supply block. The outlet of the controlled power supply block is connected to the inlet of the controlled brake. Device equipment is placed on the frame, which rests against the measuring wheels and acts at the surface of an artificial surface as a normal load force. Grip coefficients are calculated according to formulas Kgrip1=M1/P1·R; Kgrip2=M2/P2·R; Kgrip=Kgrip2·f, where Kgrip1 is a critical grip coefficient of the first measuring wheel at rest; Kgrip2 is a grip coefficient measured by the second measuring wheel; Kgrip is a grip coefficient of an aerodrome landing strip; f is a correction coefficient; M1 and M2 are moments of the grip force of accordingly the first and second measuring wheel with the artificial surface, Nm; P1 and P2 are the normal load forces of accordingly the first and second measuring wheel to the surface of the artificial surface, N; R is a radius of the measuring wheel, m.

EFFECT: increased accuracy of measurement.

5 dwg

Description

The invention relates to a device for determining the coefficient of adhesion on constructed and operated roads, checking the condition of road surfaces in settlements, as well as checking the status of runways of airfields.

Known pendulum type decelerometer used to determine the adhesion coefficient of the runway of the airfield. This device consists of an air-damped pendulum connected to an arrow showing negative acceleration.

To measure the coefficient of adhesion, the car accelerates to a predetermined speed, then the driver presses the brake pedal. The decelerometer pendulum, together with the locking arrow, deviates in the direction of travel. The value of the negative acceleration is read. By simple calculations, the coefficient of adhesion is determined. This device has significant errors in determining the coefficient of adhesion (the design and operation of the decelerometer are given in the "Manual for the operation of civil airfields in the Russian Federation").

Another known device is ″ Device for determining the coefficient of adhesion of the wheel with an airfield coating ″ (Copyright certificate No. 630982).

The known device comprises a measuring wheel, a locking clutch, a gearbox, a measuring element, a calculator, a control panel, a measuring device, a measuring trolley frame, a central link, a side link, a guide link and a driving wheel.

The determination of the coefficient of adhesion by a known device is that when the measuring trolley moves due to the difference in the diameters of the driving and measuring wheels connected through a blocking clutch to the gearbox, the measuring wheel rotates with a predetermined slip relative to the coating. The ratio of the diameters of the driving and measuring wheels provides a given slipping of the measuring wheel. Due to the slipping of the measuring wheel, a longitudinal traction force (Fssp.) The adhesion coefficient is calculated as the ratio of the longitudinal adhesion force to the normal load of the measuring wheel on the coating surface.

A disadvantage of the known device is. When determining the coefficient of adhesion and achieving a given speed of movement, the skid of the measuring trolley appears - the lateral braking force appears, which underestimates the accuracy of determining the coefficient of adhesion. The skid of the measuring trolley is due to the presence of different diameters of the measuring and driving wheels.

Closest to the claimed invention in technical essence is a ″ Device for measuring the coefficient of adhesion of a wheel with a road surface ″ having the maximum number of similar essential features with the features of the claimed device and therefore adopted as a prototype (patent of the Russian Federation, RU 2244057 C1; 7 E01C 23/07 )

The known prototype device (Fig. 1) contains a measuring wheel 1, an auxiliary wheel 2, a frame 3, bearing bearings 4, a speed sensor 5 connected to a recording unit 6, a load device 7, a rotating electromagnetic clutch 8 with an excitation coil 9, a drive 10, a power supply 11, a controlled power supply 12. In this case, the load device 7 is mounted on the frame 3. The leading part of the electromagnetic clutch 8 is connected to the drive 10, and the driven part to the measuring wheel 1. The drive 10 is connected to the power supply 11. The excitation winding 9 sub yuchena to the controlled power supply unit 12.

The work of a known device.

Before taking measurements, the surface of the road surface is moistened. The drive 10 is supplied with power from the power supply 11. The torque from the drive 10 is transmitted via a gear to a rotating electromagnetic clutch 8. The torque of the measuring wheel 1 depends on the magnitude of the control signal of the controlled power supply 12. A control signal is supplied from the recording unit 6, which smoothly increases the power of the controlled power supply from zero to a maximum value. The start of slipping of the measuring wheel 1 is detected by the speed sensor 5. The signal from the sensor 5 is transmitted to the registration unit 6, in which the start of slipping and the value of the control signal corresponding to the moment that is transmitted to the measuring wheel 1 through the rotating electromagnetic clutch 8 are recorded. The moment transmitted by the rotating electromagnetic powder clutch 8 is directly proportional to the value of the control signal of the block registration 6. The coefficient of adhesion is determined by the moment required to bring the measuring wheel 1 from a standstill to slip mode. To obtain reliable data on the magnitude of the coefficient of adhesion, before using the device, it is necessary to obtain experimentally the dependence of the magnitude of the control signal on the magnitude of the coefficient of adhesion. To do this, measure in areas with a known coefficient of adhesion and record the magnitude of the signal going to the excitation winding 9 of the rotating electromagnetic powder clutch.

A disadvantage of the known prototype device is:

- a significant limit of permissible absolute measurement error, which is explained by the complexity of determining the beginning of the slipping of the measuring wheel;

- the range of operating temperature measurements from +1 to +50 degrees. Measurements are carried out only in the summer, as the investigated surface of the pavement is wetted.

The purpose of the proposed device (Fig. 2) is to increase the accuracy of measurements of the critical rest coefficient of rest coefficient Kscp1, which is determined when the braking torque Mt of the electromagnetic brake is equal to the clutch moment M1 of the measuring wheel, as well as the accuracy of measurements of the coefficient of adhesion Kscp. the runway of the airfield and the coefficient of adhesion Ksstp.2 motor roads. Measurements are taken at any time of the year.

The goal in the device for determining the coefficient of adhesion of the wheel to the surface of the artificial surface is achieved by the fact that it, as in the prototype, contains a measuring wheel, frame, registration unit and a controlled power supply, while the first output of the registration unit is connected to the first input of the controlled power supply,

Additionally, the drive axle, a second measuring wheel, a controlled brake, and first and second torque sensors are included in the device. The controlled brake is mechanically connected through the driving axle to the first and second measuring wheels, and the first and second torque sensors are placed on the first and second measuring wheels, respectively. The torque sensors have two outputs - the output of the measuring wheel rotation speed and torque, which respectively connect from the first torque sensor to the first and second inputs of the registration unit, and from the second sensor to the third and fourth inputs of the registration unit. The second output of the registration unit is the output of the critical rest coefficient of adhesion Ksst 1, and its second output is the output of the coefficient of adhesion Kst 2 of the road surface measured by the second measuring wheel, or the coefficient of adhesion Kstst. the runway of the aerodrome, while a power source is connected to the second input of the controlled power supply. The output of the controlled power supply is connected to the input of the controlled brake. The device equipment is placed on a frame that rests on the measuring wheels and acts on the surface of the artificial coating as a normal load force. In this case, the adhesion coefficients are determined by the formulas

Kstsp. 1 = M1 / P1 · R; Ksstp.2 = M2 / P2 · R Kstsp. = Kstsp.2 · f,

where Kstsp.1 - critical coefficient of rest coupling of the first measuring wheel;

Kstsp.2 - coefficient of adhesion measured by the second measuring wheel;

KSCP. - coefficient of adhesion of the runway of the airfield;

f is the correction factor;

M1 and M2 are the moments of adhesion forces of the first and second measuring wheels, respectively, with the surface of the artificial turf, Nm;

P1 and P2 - normal load forces, respectively, of the first and second measuring wheels on the surface of the artificial turf, N;

R is the radius of the measuring wheel, m

In the known technical solutions, features similar to the distinguishing features of the claimed device are not found, as a result of which it can be considered that the proposed device corresponds to the inventive step.

Using the proposed device during its implementation will improve the quality of operation and repair of road surfaces on highways and in settlements, as well as reliably assess the condition of artificial surfaces of runways of airfields. The essence of the proposed device for determining the coefficient of adhesion of the wheel to the surface of the artificial coating is illustrated by drawings, which show:

in FIG. 1 is a structural diagram of a prototype;

in FIG. 2 is a structural diagram of the proposed device;

in FIG. 3 - algorithm for determining the coefficient of adhesion of the road surface;

in Fig 4 is an algorithm for determining the coefficient of adhesion of the runway of the airfield;

in FIG. 5 is a drawing explaining the determination of the maximum marginal coefficient of adhesion Ksstp.maks.

The proposed ″ Device for determining the coefficient of adhesion of the wheel to the surface of the artificial surface ″, as a prototype contains: measuring wheel 1, frame 3, registration unit 6 and a controlled power supply 12. In this case, the first output of the registration unit 5 is connected to the first input of the controlled power supply 12.

Additionally, the device includes: driving axle 13, second measuring wheel 14, controlled brake 15, first 16 and second 17 torque sensors. Moreover, the controlled brake 15 through the driving axle 13 is mechanically connected to the first 1 and second 14 measuring wheels, and the first 16 and second 17 torque sensors are placed respectively on the first 1 and second 14 measuring wheels. The torque sensors have two outputs - the output of the measuring wheel speed and torque, which respectively connect from the first 16 torque sensors to the first and second inputs of the registration unit 6, and from the second 17 sensors to the third and fourth inputs of the registration unit 6. Second the output of the registration unit 6 is the output of the critical coefficient of rest coupling Ksst 1, and its third output is the output of the coefficient of adhesion Kst 2 of the road surface measured by the second measuring wheel, or clutch coefficient airfield runway. At the same time, a power source is connected to the second input of the controlled power supply. The output of the controlled power supply unit 12 is connected to the input of the controlled brake 15. The equipment of the device is placed on the frame 3, which rests on the measuring wheels and acts on the surface of the artificial coating as a normal load force. Cohesion coefficients are determined by the formulas

Kstsp. 1 = M1 / P1 · R; Ksstp.2 = M2 / P2 · R Kstsp. = Kstsp.2 · f,

where Kstsp.1 - critical coefficient of rest coupling of the first measuring wheel;

Kstsp.2 - coefficient of adhesion measured by the second measuring wheel;

KSCP. - coefficient of adhesion of the runway of the airfield;

f is the correction factor;

M1 and M2 are the moments of adhesion forces of the first and second measuring wheels, respectively, with the surface of the artificial turf, Nm;

P1 and P2 - normal load forces, respectively, of the first and second measuring wheels on the surface of the artificial turf, N;

R is the radius of the measuring wheel, m

The design of the proposed device

The claimed measuring device is made on two measuring wheels, on which the frame 3 is installed. The measuring wheels 1 and 14, the frame 3 and the device equipment located on it make up the normal load force on the surface of the artificial coating. Normal forces P1 and P2 are known and remain constant during operation of the device. The normal forces P1 and P2, the radius of the measuring wheels R and the correction factor f are entered into the memory of the registration unit 6 to calculate the adhesion coefficients.

The driving axle 13 consists of a series of interacting bodies that transmit braking torque from the controlled brake 15 to the measuring wheels. The driving axle 13 contains: a gearbox, a junction box, a final drive, a differential, half shafts on which the hubs are mounted. The differential is symmetrical with a blocking coefficient of 1. The controlled brake 15 is connected to the junction box, and the first 1 and second 14 measuring wheels are mounted on the hubs of the driving axle 13.

To check the condition of the road surface on measuring wheels 1 and 14, a car chassis is used, and to check the condition of the runway of an airfield, an aircraft chassis.

The registration unit 6 is made on a PIC18 microcontroller. The microcontroller has programmable memory, random access memory, analog-to-digital converters, built-in interfaces, timers, real-time timer, inputs and outputs for input and output of information.

The first 16 and second 17 torque sensors are mounted on the first 1 and second 14 measuring wheels, respectively. The sensors are used to measure the moments of adhesion forces M1 and M2 with the surface of the artificial turf. Each sensor is equipped with a telemetry system for transmitting a useful signal. Each sensor has two outputs - the first moment is transmitted to the moment M of the coupling force of the measuring wheel with the coating surface, and the second output is the rotation speed N of the measuring wheel. The outputs of the torque sensors 16 and 17 are connected to the inputs of the registration unit 6.

The controlled brake 15 is an electromagnetic powder brake. The controlled brake 15 has two coaxial elements; case with electromagnet winding and rotor. The housing from the rotor is separated by an annular gap, which is filled with dry alloyed ferromagnetic powder. Torque braking torque Mt is transmitted by doped ferromagnetic powder, the viscosity of which changes in accordance with the change in current in the excitation winding of the controlled brake 15. The braking torque Mt of the controlled brake 15 is directly proportional to the current of the excitation winding of the electromagnet. The rotor speed of the controlled brake 15 does not affect the braking time Mt.

Managed power supply 12 is a power unit, which, according to the controlled voltage from the registration unit 6, generates an excitation current of the winding of the electromagnet of the controlled brake 15.

Cohesion coefficient measurement

With the beginning of the movement of the measuring device, the torque sensors 16 and 17 measure the moments of adhesion forces M1 and M2 of the measuring wheels with the surface of the artificial turf (Fig. 3). In this case, the first torque sensor 16 is controlling, according to the signals of which the braking torque Mt of the controlled brake 15 is determined. The voltage of the first sensor 16 is supplied to the recording unit 6, where a control voltage is generated in accordance with the voltage value of the signal from the sensor 16. The control voltage is supplied to the controlled power supply unit 12, where, in accordance with the control voltage, the amount of current transmitted through the controlled power supply unit 12 to the excitation winding of the controlled brake 15 is determined. The current of the excitation winding of the controlled brake creates a braking torque Mt that acts on the measuring wheels. A symmetrical differential is used in the driving axle 13, which allows the braking torque Mt of the controlled brake 15 to be divided equally (Mt / 2) between the measuring wheels.

In this case, the operation of the first measuring wheel 1 is determined by its three states:

- during measurements, the measuring wheel 1 does not slip and M1 ...> MT / 2 in this case, the voltage of the first sensor 16 through the recording unit 6 and the controlled power supply 12 increases the excitation current of the excitation winding of the controlled brake 15, while the braking torque Mt of the controlled brake increases;

- during measurements, the measuring wheel 1 stalls, then M1 <MT / 2, and in this case, the voltage of the first sensor 16 through the recording unit 6 and the controlled power supply 12 decreases the excitation current of the excitation winding of the controlled brake 15 - the braking torque Mt decreases;

- during measurements, the measuring wheel 1 does not slip, but M1 = MT / 2 - the voltage of the first sensor 16 is maintained, the braking torque Mt of the controlled brake 15 is maintained. If M1 = MT / 2 is equal between the measuring wheel 1 and the surface of the artificial turf, the maximum braking force Ftor.maks., Which is equal to traction force. FSCP. measuring wheel 1 with a coating surface. In this case, the measuring wheel 1 is located on the border of the beginning of its slipping. Cohesion coefficient measured at the slip boundary is the critical rest coefficient of coupling. The critical coefficient of rest coupling of the first 1 measuring wheel Kst 1 in the registration unit 6 is calculated by the formula

Ksstp. 1 = M1 / P1 · R,

where Kstsp.1 - critical coefficient of adhesion of the first 1 measuring wheel;

M1 is the moment of adhesion of the first 1 measuring wheel to the surface of the artificial turf, Nm;

P1 - normal load of the first 1 measuring wheel on the coating surface, N;

R is the radius of the measuring wheel, m

The condition of the road surface is determined simultaneously by two tracks. Using one rut, the first 1 measuring wheel determines the critical coefficient of rest adhesion Ksstp.1, and on the second rut of the road surface with the second 14th measuring wheel determines the coefficient of adhesion Kstsp.2,

at the same time, the braking torque Mt / 2 acts on the second measuring wheel. The coefficient of adhesion KSCP.2 in the registration unit 6 is calculated by the formula

Ksstp. 2 = M2 / P2 · R,

where Kstsp.2 - coefficient of adhesion of the second track of the road surface;

M2 is the moment of adhesion of the second 14 measuring wheel with the surface of the artificial coating, Nm;

P2 - normal load of the second 14 measuring wheels on the surface of the coating, N;

R is the radius of the measuring wheel, m

The condition of the pavement is determined on roads under construction, under repair and in operation, as well as in settlements at any time of the year. The speed of the measuring device does not affect the result of the measurements.

Determining the status of the runway of the aerodrome

The condition of the runway is determined in accordance with the requirements of ICAO (International Civil Aviation Organization) FIG. four.

At the manufacturing stage of the device, it is torrified. Torrification is carried out on a dynamic roller stand. The stand rollers have a special coating with a known coefficient of adhesion, which allows, in conditions close to real ones, to check and adjust the measuring device. And also on the dynamic bench, in accordance with the requirements of ICAO, with a certain value of relative slip S (from 0.1 to 0.3) on the second measuring wheel 14, the maximum limiting coefficient of adhesion Ksst.max is obtained. (Fig. 5). The relative slip S of the measuring wheels is determined by the formula

S = N1-N2 / N1,

where N1 and N2 are the rotation speeds of the first 1 and second 14 measuring wheels, respectively.

The value of the relative slip of the second measuring wheel 14, corresponding to the maximum coefficient of adhesion, is called critical SK. At Sk, Kscp.1 and Kscp.mak are determined. In relation to to Ksstp.1 determine the correction factor f

f = RSCMax / RSC.1.

When determining the state of the runway of the airfield, the critical rest coefficient Ksst 1 = M1 / R R is simultaneously determined, as well as in accordance with the ICAO requirements, the adhesion coefficient Ksst.

Kstsp. = Kstsp.2 · f,

where is KSCP. - coefficient of adhesion of the runway of the airfield;

Kstsp.2 - coefficient of adhesion measured by the second measuring wheel;

f is the correction factor.

The positive effect of the implementation of the proposed device is to increase the accuracy of determining the coefficient of adhesion. The coefficient of adhesion is determined regardless of the speed of the measuring device and at any time of the year. When measuring surface wetting is not required. The condition of the road surface can be checked in the settlements in compliance with the rules of the road.

Claims (1)

A device for determining the coefficient of adhesion of the wheel to the surface of the artificial coating, comprising a measuring wheel, a frame, a registration unit and a controllable power supply, the first output of the registration unit being connected to the first input of the controllable power supply,
characterized in that the driving automobile axis, the second measuring wheel, the controlled brake, the first and second torque sensors are further included, the controlled brake being mechanically connected through the driving automobile axis to the first and second measuring wheels, and the first and second torque sensors are placed respectively on the first and second measuring wheels, the torque sensors have two outputs - the output of torque and speed of rotation of the measuring wheel, which respectively turn off from the first torque sensor to the first and second inputs of the registration unit, and from the second sensor to the third and fourth inputs of the registration unit, the second output of which is the output of the critical resting coupling coefficient Ksst1, and the third output of the registration block is the output of the ksst coupling coefficient. 2 of the road surface measured by the second measuring wheel, or the coefficient of adhesion Ksstp. the runway of the airfield, the power supply is connected to the second input of the controlled power supply, the output of the controlled power supply is connected to the input of the controlled brake, the device equipment is placed on a frame that rests on the measuring wheels and acts on the surface of the artificial surface as a normal load force, while adhesion coefficients are calculated by the formulas
Ksstp. 1 = M1 / P1 · R; Kstsp.2 = M2 / P2 · R; Kstsp. = Kstsp.2 · f,
where Kstsp.1 - critical coefficient of rest coupling of the first measuring wheel;
Kstsp.2 - coefficient of adhesion measured by the second measuring wheel;
KSCP. - coefficient of adhesion of the runway of the airfield;
f is the correction factor;
M1 and M2 are the moments of adhesion forces of the first and second measuring wheels, respectively, with the surface of the artificial turf, Nm;
P1 and P2 - normal load forces, respectively, of the first and second measuring wheels on the surface of the artificial turf, N;
R is the radius of the measuring wheel, m

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