RU2614836C1 - Automotive device for measuring adhere ratio to the road - Google Patents

Abstract

FIELD: measurement equipment.

SUBSTANCE: proposed to automotive friction measuring device pavements factor containing trailing device with a measuring wheel, coupled with it a car with a manual transmission and a trip computer, and a computing device further includes distance sensor that is connected to a computing device, automatic maintenance system multisystem vehicle speed and routing computer, one of whose inputs is connected to a computing device and one of the outputs - to the display, laid down in front of the cab of the towing vehicle.

EFFECT: improving accuracy of measurements.

4 cl, 4 dwg

Description

The invention relates to road construction, more specifically to devices (road laboratories) for the operational measurement of the coefficient of adhesion of a car wheel with a road or airfield coating.

Known trailed device for periodic measurement of the coefficient of adhesion of the road surface, containing a measuring wheel, on the axis of which a gear pulley is mounted, connected by a gear drive belt with a second gear pulley mounted on the shaft of the electric motor. Near the teeth of the second pulley, between the branches of the toothed belt, a sensor is installed that gives an impulse when another tooth passes past it. The pulses from the sensor are transmitted to the central processor, where the peripheral speed of the measuring wheel, which is untwisted before the measurement by an electric motor and lowered to the measured surface using the articulated lever mechanism, is calculated by the frequency of their repetition [US No. 6681614]. The known device cannot perform measurements in motion and requires special preparation of the surface of the measuring wheel and the road section before measurement. In addition, the measurement method carried out by a known device does not comply with the established current GOST 30413-96.

Also known is a one-wheel device for continuous measurement of the coefficient of adhesion of the road surface, designed for installation on a car, comprising a measuring wheel, a gear disk made of ferromagnetic material mounted coaxially with it, and a sensor installed near the teeth of the disk, which gives an impulse when another tooth passes past it. The pulses from the sensor are fed to the central processor, where the peripheral speed of the measuring wheel is calculated by their repetition rate, and the calculation results are compared with the speedometer of the vehicle on which this device is installed. As a result of the comparison, a signal is generated for the driver warning of a slippery road [US No. 6276189].

A disadvantage of the known device is that it is not intended and cannot perform the functions of a measuring laboratory. The measured values are only compared with each other. The absolute, and accurate data on the coefficient of adhesion of the known device does not provide.

Closest to the proposed technical essence and the achieved result is an automobile test device for measuring the coefficient of road surfaces, consisting of a car with a manual gearbox and a trailed one-wheeled device of the PKRS-2 type with a measuring wheel, brake and measuring devices. Measuring devices mounted on a towed device include a traction force dynamometer used to measure the adhesion coefficient, and means for transmitting in electrical form the signals from the sensor and dynamometer to a device for processing and fixing data, hereinafter referred to as the “computing device” installed in the vehicle. The initial result for calculating the adhesion coefficient is the traction force on the device’s coupling device at the moment when the measuring wheel is completely braked (locked) when moving at a given translational speed ["Measuring instruments approved for circulation in the USSR. Description of approved samples ”/ M .: Publishing house of standards, 1988. (PKRS-2 is registered under No. 10913-87)]. According to clause 4.1.1 of GOST 30413-96 “Method for determining the coefficient of adhesion of a car wheel to a road surface”, this device is the standard means of measuring the coefficient of adhesion.

According to the same standard, the adhesion coefficient is measured at a speed of 60 ± 5 km / h. Since neither the car nor the towed device contains special devices for measuring the translational speed of the measuring wheel, during the measurement the speed is set according to the speedometer of the car serving as a tractor for the towed device.

According to GOST 1578-76 (Speedometers automobile and motorcycle with a drive from a flexible shaft) and GOST 12936-72 (Speedometers automobile with an electric drive) the error of the speedometer should be only positive and at a speed of 60 km / h should not exceed 4 km / h. An additional error of the speedometer speed indicator is added to this value if the ambient temperature differs from + 20 ° C. This error should not exceed ± 2% for every 10 ° C difference from + 20 °. Since according to GOST 30413-96, measurements are carried out in the temperature range from 0 to + 40 ° C, an additional error of up to 4% may appear.

Thus, if the car driver, guided by the speedometer, maintains a speed of 65 km / h, assuming that he still does not go beyond the tolerance range required by GOST 30413-96, then, taking into account the positive speedometer error of 4 km / h, the actual speed will be 61 km / h If the measurements are carried out at an air temperature close to 0 ° C, then an additional error of 4% will be 2.6 km / h. Thus, the actual test speed may be 63.6 km / h. If the driver can withstand the minimum permissible speed of 55 km / h, then taking into account the positive error of the speedometer, the actual speed will be 51.3 km / h, and if the air temperature is close to 0 ° C (additional error of 2.2 km / h ), then the minimum actual speed with the indicated errors may be even 49.1 km / h.

Another source of error is the time-varying psycho-emotional state of even the same driver. The speed of 60 km / h is relatively high, and the attention of the driver during the measurement of the coefficient of adhesion is focused mainly on the road, and not on the speedometer. Even two measurements taken in a row at the same place, for this reason, may differ in their actual values. The simplest solution to this problem would be to use a car equipped with a cruise control system as a tractor. However, for a number of reasons, primarily economic, automobiles with an automatic transmission that are only equipped with an electronic system for automatically maintaining speed (hereinafter referred to as “SAPS”), commonly called “cruise control”, are not used as a tractor for the road laboratory.

Due to the indicated errors, certain sections of the road with a coating absolutely identical in terms of properties can be rejected, or, conversely, taken into operation, being defective. The economic consequences of such errors are very large.

The purpose and technical result achieved by the proposed invention is to improve the accuracy and reproducibility of the measurement results of the coefficient of adhesion of the road surface with a test device, the vehicle of which is equipped with a manual gearbox.

This result is achieved by the fact that in a known automobile device for measuring the coefficient of adhesion of road surfaces, comprising a towed device with a measuring wheel, a car coupled to it with a mechanical gearbox and an on-board computer, as well as a computing device, an additional distance sensor connected to the computing device, a system for automatically maintaining vehicle speed and a multi-system trip computer, one of the inputs of which is connected to a computer dispenser, and one of the outputs - to the display installed in front of the cab of the truck.

In addition, a distance sensor is installed on one of the wheels of the car.

In addition, the display of the multi-system trip computer is mounted to the right of the steering column of the car outside the projection of the steering wheel on its front panel.

In addition, the input of the on-board computer is connected via a computing device to the sensor of the distance traveled.

The proposed technical solution is based on the new knowledge received by the authors about the effect of the speed at which the adhesion coefficient is measured on the result. It was first established that this influence is much stronger than the drafters of the above documents expected, and that the existing and used means of measuring the adhesion properties of road surfaces in their design features cannot ensure that the speed is maintained with the accuracy required for satisfactory reproducibility and accuracy of measurements. It was necessary to create a device capable of carrying out measurements at a speed that would change by no more than ± 1.6 km / h from the value required by the standard. In this case, two tasks were solved: automatic maintenance of the vehicle speed with a manual gearbox with high accuracy and accurate measurement of this speed with the presentation of the measurement results in a form that is easily readable simultaneously by the operator and the driver.

Thanks to the addition of a well-known automobile device with a distance sensor connected to a computing device, it becomes possible to accurately, free from speedometer and human factor errors, measure the speed of the test setup. In this case, the speed data during the tests are objectively recorded in the memory of the computing device.

Thanks to the installation of a system of automatic speed control (hereinafter referred to as cruise control systems) on a towing vehicle with a manual gearbox, it is possible to automatically maintain the installation speed set by the driver, free of driver errors. This ensures high reproducibility of the measurement results carried out strictly at the same speed.

Thanks to the addition of the known installation to a multi-system trip computer, one of the inputs of which is connected to a computing device, and one of the outputs to a display mounted in front of the tractor cab, the accuracy and reproducibility of measurement results are increased by providing the driver with clearly visible and easily readable speed information movements at any given moment.

Thanks to the installation of the display of the multi-system trip computer to the right of the steering column of the car outside the projection of the steering wheel on its front panel, the accuracy and reproducibility of the measurement results is increased, since the display screen becomes available for viewing by the installation operator who decides to start the measurement.

By connecting the input of the on-board computer through the computing device to the sensor of the traveled distance, the accuracy and reproducibility of measurements are increased, since the jerks and vibrations of the transmission at the time of blocking the measuring wheel do not generate false signals that would come through the speed sensor of the transmission secondary shaft, as is usually the case cruise control systems, to the on-board computer.

The essence of the proposed invention is illustrated by drawings.

In FIG. 1 is a side elevational view of a test vehicle installation.

In FIG. 2 shows a structural diagram including the main elements of the claimed installation indicating the relationship between them.

In FIG. 3 shows a block diagram of a device with a cruise control system, connected at the input through a computing device to the sensor of the traveled path.

In FIG. 4 shows the results of measurements of the coefficient of adhesion obtained on the same test site by the installation of the prototype and the proposed installation.

The proposed automobile device for measuring the coefficient of adhesion of the road surface consists of a car 1 having a mechanical gearbox and a trailed device 2, including a measuring wheel 3, a brake 4, means for moistening the road surface, the necessary sensors of the measured parameters and means for transmitting information. In the passenger compartment of the car 1, a computing device 5 is installed, which is usually used as a personal computer of sufficient computing power. The installation operator is also located there.

Common to a car of known installation and proposed are (Fig. 2) engine 6, engine speed control device 7 (for example, carburetor throttle), manual gearbox 8, transmission 9, including driveshaft and rear axle, rear wheels 10, steering wheel 11 with a steering column 12, a front dashboard 13 and an on-board computer 14.

In addition, the installation includes a sensor for the traveled path 15 connected to the computing device 5. The sensor can be an inductive type, the signal source for which is ferromagnetic teeth, notches or holes in the disk 16 mounted on the wheel, or the active type if the disk 16 consists of alternating magnets different polarity. Since modern cars include an anti-lock braking system (ABS), the elements of which are wheels mounted on wheels similar to disk 16, there is no need to install an additional disk on the wheel. It is enough to install the sensor 15 next to the standard ABS sensor of the car, and it can be of the same type. It is more convenient to install the sensor 15 at the rear fixed wheels of the car.

The Hall effect sensor 15 is connected to a computing device 5, where the signal from it is converted to a vehicle speed value taking into account the diameter of the wheel. When measuring the coefficient of adhesion, this value is taken as the speed at which the test is carried out.

Additionally included in the structure of the proposed device, the cruise control system includes a speed sensor 17 mounted on the secondary shaft 18 of the gearbox 8 and connected to the input of the on-board computer 14, the output of which is connected to the engine speed control device 7. To set the speed that must be maintained cruise control system, serves as a push-button device, or remote control 19, connected to the on-board computer 14.

The proposed device also contains a multi-system trip computer 20, one of the inputs of which is connected to the computing device 5, and one of the outputs to the display 21, installed in front of the cab in the driver's field of vision. Computer 20 serves to convert digitally expressed information about the installation speed into a form that is accessible for visual perception. For the convenience of taking measurements and increasing their accuracy, it is preferable that the display 21 be mounted on the dashboard 13 of the car to the right of the steering column 12 so that it is clearly visible to both the driver and the operator behind him.

An improvement of the proposed device is the option when the input of the on-board computer 14 is connected not to the speed sensor 17, but via the Hall effect computer 5 to the distance sensor 15 operating on the Hall effect (Fig. 3). The computing device 5 converts the signal from the sensor 15 into a signal similar to that generated by the sensor 17.

In this variant, the torsional vibrations of the driveline of the transmission 9 caused by jerks at the moment of blocking the measuring wheel 3 do not create false signals coming through the sensor 17 to the on-board computer 14. This increases the accuracy of measurements. To maintain the possibility of a return to the cruise control scheme based on measuring the speed of the secondary shaft 18, for example, during debugging, the proposed device may include a switch 22.

The proposed device works as follows.

The driver sets using the remote control 20 a preset speed value, guided by the readings of the display 21, on which the speed information is displayed, the primary source of which is the sensor 15. The readings of the vehicle’s speedometer are not taken into account. The cruise control system maintains the set speed value with an accuracy of no worse than ± 3% (60 km / h ± 1.8 km / h), freeing the driver’s attention from engine speed control. The driver can only follow the standard tachometer or warning light so that the engine speed does not go beyond the optimal range. If this happens, for example, on a steep climb, the driver engages a more suitable gear and re-sets the cruise control mode in accordance with the set speed.

The operator behind the driver monitors the speed indicated by display 21 and selects the moment the measurement begins. At the same time, the driver does not block the display 21 with his back. At the operator’s command, the device for moistening the road surface in front of the measuring wheel 3 is turned on, which is braked by the brake 4 until it is completely locked, and the dynamometer installed on the trailed device measures the horizontal traction force, according to which the computing device 5 calculates the adhesion coefficient of the road surface.

The field studies conducted by the applicant of the proposed automobile device showed that it is able to withstand a given speed of 60 km / h, which is standard for measurements with a spread of less than ± 2 km / h. Moreover, these studies confirmed the previously established fact that the accuracy of maintaining the speed required to ensure reproducibility of the measurement results should be significantly higher than that provided by standard automobile speedometers. The use of the cruise control system has reduced the influence of the human factor on the accuracy of measurements. It is enough for the driver, guided by the readings of the display 21, to set the speed required by the measurement conditions, turn on the cruise control system and focus on driving. The set speed will be maintained automatically, more precisely than the driver would have done.

In FIG. Figure 4 shows probability plots P of the fact that the actual speed v of the towing vehicle coincides with the standard (60 km / h) obtained when measuring on the same instrument with the same car before and after equipping the test setup with the proposed device. The presence of the second maximum on the “DO” chart is most likely due to the human factor. From the graphs it can be seen how much the accuracy of maintaining a given standard speed increases from the use of the proposed device. In turn, this allows to ensure high reliability, accuracy and precision of the results of measurements of the coefficient of adhesion.

Claims (4)

1. An automobile device for measuring the coefficient of adhesion of road surfaces, comprising a towed device with a measuring wheel, a car coupled to it with a mechanical gearbox and an on-board computer, as well as a computing device for determining the adopted value of the driving speed during measurements, characterized in that additionally included a distance sensor connected to a computing device, a system for automatically maintaining vehicle speed and a multi-system route ny computer, one input of which is connected to the computing device, and one of the outputs - to the display, laid down in front of the cab of the towing vehicle. 2. An automobile device according to claim 1, characterized in that the sensor of the distance traveled is installed on one of the wheels of the car. 3. An automobile device according to claim 1, characterized in that the display of the multi-system trip computer is mounted to the right of the steering column of the car outside the projection of the steering wheel on its front panel. 4. An automobile device according to claim 1, characterized in that the input of the on-board computer is connected through a computing device to the sensor of the distance traveled.

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