RU87524U1 - INSTALLATION FOR DETERMINING RESISTANCE TO ROLLING OF PNEUMATIC WHEELS - Google Patents

Abstract

Installation for determining the rolling resistance of pneumatic wheels, including a welded frame on racks with horizontal supports, two wheels between which a support platform simulating the road is clamped, pendulum balances on each wheel to set the torque, solenoid valves for fixing the wheels in the initial position, rotation angle sensors, fixing the rotation angle of each wheel, adjusting screws for changing the normal deformation of tires and ball bearings on which the movable shaft of one the scaffold moves along the slots and on the support plates of the installation frame by means of adjusting screws, characterized in that the pendulum counterweights on each wheel in the initial fixed position are located at an angle of 45 ° to the horizontal and spread in opposite directions.

Description

The utility model relates to transport engineering, in particular, to installations for determining the rolling resistance of pneumatic wheels.

A known installation for determining the rolling resistance of pneumatic wheels with free, slow rolling of the wheel with the tire under test on the drum. The installation is a frame on which a running drum is installed with the tested pneumatic wheel, the axes of which are in the horizontal plane. The drive of the running drum is carried out using an electric motor through a V-belt drive. The mounting frame also has a lever device with hinged loads, with which the test wheel is pressed against the running drum, that is, the normal deformation of the tire changes. [one]

The disadvantages of this installation include the fact that the running drum has a significant curvature (usually the diameter of the drums does not exceed 2 ... 2.5 m). In this case, the deformation of the tire in contact with the running drum is greater than the deformation of the tire in road conditions, as a result of which the obtained value of the coefficient of rolling resistance exceeds the actual value, and this installation also has a very complex structure.

There is also known a device for determining the rolling resistance of pneumatic wheels in the driven and brake modes of rolling, which is a base on which an endless running surface with a drive is mounted. The wheel resting on the running surface is mounted freely on the axle and equipped with a brake, while the axis is mounted on a traverse having a movement mechanism along the swinging frame, equipped with a balancer, and the axis of the frame is aligned with the running surface in the contact area with the wheel and connected to a torque clutch fixed in the rotary device. The swivel column, in which the axis is located, is installed in the support sleeve and clamped by the latch. [2]

This installation has the same drawback as described above - this is the complexity of the design, as well as the fact that on this installation it is not possible to measure the rolling resistance of pneumatic wheels in the driving mode, in which it reaches its maximum value.

Also known installation for determining the sum of the moments of rolling resistance of the driving and braking pneumatic wheels [3]. The installation is a welded frame made of channel. The wheels are mounted on the shafts by means of rolling bearings. One shaft is rigidly mounted on the frame, the second shaft is mounted on a slide welded from the corner and freely moving horizontally along the frame using the adjusting screw. When turning the adjusting screw, the distance between the wheels changes (normal tire deformation). To measure the initial position of the wheel, a circular degree scale is fixed on its disk. To fix the initial position of the wheel, electromagnetic valves are used, which are attached to the installation frame. The solenoid valves are powered by a battery. To obtain torque, a pendulum counterweight was made, which is rigidly mounted on the wheel. The counterweight is two steel strips fixed on both sides of the wheel disc. In the strips there is a hole for installing goods. The wheel angle sensor is mounted directly on the wheel hub shaft. A servo rail transmitting wheel vibrations to the angle sensor is rigidly connected to the wheel disk and the roller of the angle sensor. The sensors are connected to an analog-to-digital converter, which in turn is connected to a personal computer [3].

The disadvantage of this installation is that it is not possible to measure the rolling resistance of pneumatic wheels in the driving and brake modes of rolling the wheels separately.

Based on the above-mentioned shortcomings of existing installations for determining the rolling resistance of pneumatic wheels in various rolling modes, we were tasked with creating a setup with which we can determine the rolling resistance of pneumatic wheels in both driving and brake modes of rolling, which will be simple by designs.

To solve this problem, we have improved an existing installation for determining the sum of the moments of rolling resistance of the driving and braking pneumatic wheels, which has a simple design.

Figure 1 presents a General view of the proposed utility model, which is a welded frame 1 on two racks with horizontal supports. Wheels 2 are mounted on shafts by means of rolling bearings. One shaft is rigidly mounted on the frame, the second shaft can be mixed horizontally along the slots and along the support plates 3 of the mounting frame on ball bearings 4 using the adjusting screws 5, in order to change the pressure of the wheels against the supporting platform 6. When turning the adjusting screws, the interaxle changes wheel distance (normal tire deformation). The pressing force is measured using a dynamometer. To set the rotational moment on the wheels, a pendulum counterweight 7 is made on which loads 8 of a certain mass are hung. It is a steel strip with holes for installing goods, fixed on both sides of the wheel drive. To fix the initial angle and keep the wheels in a fixed initial position on the installation frame there are solenoid valves 9, which also free these wheels from a nonequilibrium state. The solenoid valves are powered by a battery. The pendulum balances of each wheel are installed in the initial non-equilibrium fixed position so that they are at an angle of 45 ° to the horizontal and are spread in opposite directions in order to obtain both the driving and braking modes of rolling. Pendulum balances can be installed at various angles from 0 ° to 90 °, but for the convenience of measurement, we take the optimal angle equal to 45 °, because a small value of the angle in the leading rolling mode and vice versa a large value of the angle in the braking mode of rolling will present technical difficulties in determining the rolling resistance. To measure the angle of rotation of the wheels, the installation has angular displacement sensors 10 that record information about the position of the wheel, and the received information is displayed on a personal computer through an analog-to-digital converter, in the form of a table, for subsequent analysis. To transmit the oscillations of the pneumatic wheels to the angle sensors, the installation has servo rails 11. The servo rails are rigidly connected to the rollers of the angle sensors. And the angle sensors are connected to an analog-to-digital converter, which is connected to a personal computer.

Installation works as follows.

To determine the rolling resistance of the pneumatic wheels in the driving mode, we set the pendulum balances 7 of each wheel 2 in the initial fixed position so that they are at an angle α _нв = 45 ° and are fixed in this position by electromagnetic valves 9 (see Fig. 2). Then we hang on the pendulum balances 7 of both wheels 2 loads 8, thereby setting the driving moment on both wheels 2 of the installation. At the same time, we hang the load 8 on the support platform 6, but with the expectation that the moment created on the support platform 6 by the load 8 is less than the total moment created by the loads 8 on the pendulum balances 7 of the two installation wheels. In this case, we get the leading mode of rolling wheels.

Then we bring the wheels 2 out of their initial position with the help of electromagnetic valves 9 and observe the damped vibrations of the wheels 2 of their transition to the equilibrium state with the recording of this process and its output to the computer. In this case, the pendulum balances 7 with weights 8 on the wheels 2, which create a torque, move downward towards each other, and the supporting platform 6 with the load 8 is vice versa upward. Thus, the angle α _HB decreases, and the driving moment created by the pendulum balances 7 and the weights 8 mounted on them also decreases, then the wheels 2 stop when the balance between the loads 8 on the pendulum balances 7 and the load 8 on the supporting platform 6 occurs (see figure 2).

After the wheels stop, we determine the angle α _kV , at which they came into equilibrium. From this angle, you can determine the total moment of resistance of both wheels to rolling in the leading loading mode according to the following formula

Where - the sum of the moments of rolling resistance of both wheels in the leading rolling mode;

g is the acceleration of gravity;

l is the length of the pendulum balances;

m _b1 , m _b2 - the mass of the load on the pendulum counterweight, creating a driving moment, respectively, on the first and second wheels;

α _q1 , α _q2 - the angle of equilibrium position of the wheels, respectively, of the first and second wheels;

m ₃ is the mass of cargo at the reference site;

r _to - the radius of the wheel.

The determination of rolling resistance of pneumatic wheels in the brake rolling mode is as follows. We install the pendulum balances 7 of each wheel 2 in the initial fixed position so that they are at an angle α _NT = 45 ° and are fixed in this position by electromagnetic valves 9 (see figure 3). We load the pendulum balances 7 and the support platform 6 with weights 8, but the total moment created by the loads of 8 pendulum balances 7 should be less than the moment created by the load 8 of the support platform 6. In this case, we get the braking mode of the wheels. Then, using electromagnetic clamps 9, we remove the wheels 2 from an nonequilibrium state and record the process of transition of the brake wheels 2 to an equilibrium state. In this case, the wheels 2 will rotate so that the pendulum balances 7 will move up, and the load 8 with the supporting platform 6 down, that is, there will be an increase in braking torque on the wheels 2 until there is an equilibrium between the loads 8 on the pendulum balances 7 and a load of 8 on the supporting platform 6 (see figure 3).

After the wheels stop, we determine the angle α _kt , at which they came into equilibrium. From this angle, you can determine the total moment of rolling resistance of pneumatic wheels in the brake mode of rolling according to the formulas:

Where - the total moment of rolling resistance of both wheels in the braking mode of rolling;

m _t1 , m _t2 - the mass of the load on the pendulum counterweight, creating braking torque, respectively, on the first and second wheels;

α _ct1 , α _ct2 - the angle of equilibrium position of the wheels, respectively, of the first and second braking wheels.

This installation, with its simplicity of design, allows with sufficient accuracy to determine the rolling resistance of pneumatic wheels in the driving and brake modes of rolling, and the results are not distorted as in some installations with running drums.

Literature

1. Car tires / Biderman VL, Guslitser RL, Zakharov S.P. et al. - Moscow: Goskhimizdat, 1963 .-- 384 p.

2. A.S. USSR No. 492778. Wheel test device with elastic tire. / V.G. Anopchenko // publ. in bull. No. 11, 1986

3. Novikov K.V. Determination of rolling resistance when testing wheeled tractors by the rollback method: Dis. ... cand. tech. sciences. - Kirov, 2005 - 143 p. - prototype.

Claims (1)

Installation for determining the rolling resistance of pneumatic wheels, including a welded frame on racks with horizontal supports, two wheels between which a support platform simulating the road is clamped, pendulum balances on each wheel to set the torque, solenoid valves for fixing the wheels in the initial position, rotation angle sensors, fixing the rotation angle of each wheel, adjusting screws for changing the normal deformation of tires and ball bearings on which the movable shaft of one the scaffold moves along the slots and on the support plates of the installation frame by means of adjusting screws, characterized in that the pendulum counterweights on each wheel in the initial fixed position are located at an angle of 45 ° to the horizontal and spread in opposite directions.