RU2522663C1 - Method for disc braking device parameters optimisation - Google Patents

Abstract

FIELD: transport.

SUBSTANCE: method consists in determination of mechanical component of friction power at initial parameters of friction pad form which component pad's volume wear rate is found. Actual lifetime of friction pad is determined from found value of wear rate. Then, lifetime increment value is assigned and optimal values of area, length of friction pad and brake disc roughness radius are determined.

EFFECT: increasing friction pad lifetime due to consideration of friction pad and brake disc geometrical parameters impact on the value of friction power mechanical component and to selection of efficient ratio of their geometrical parameters.

Description

The invention relates to the field of mechanical engineering, mainly to the field of automotive industry, and is intended to search for optimal parameters of disk brake devices.

A known method of optimizing the parameters of a disk brake device by determining the geometric parameters of the friction lining of brake pads, based on the calculation of the surface area of the friction lining by obtaining the ratio of the total friction work to the product of the duration of a single braking and the allowable specific friction power and the length of the friction lining by obtaining the product of the average radius of the friction lining at the central angle, expressed in radians.

[Alexandrov M.P., Lysyakov A.G., Fedoseyev V.N., Novozhilov M.V. Braking devices, M.: Mechanical Engineering, 1985, S. 298 - 312].

The specified method does not allow to determine the service life of the brake device and to obtain rational values of the geometric parameters of the brake pads, which provide an increase in the resource of the friction lining of the brake device.

There is also a method for optimizing the width of the friction lining of the brake device, which consists in determining the effective friction area of the friction pad in relation to the braking torque to the product of the radius, friction coefficient and specific load and then determining the width of the friction pad in relation to the found value of the effective friction area of the friction pad to the product of the coefficient mutual overlap and the perimeter of the center line of the friction lining [Friction, wear and lubrication. Handbook in 2 volumes, volume 2, edited by I.V. Kragelsky and V.V. Alisin, 1979. M.: Mechanical Engineering, p.253].

The disadvantage of this method is the inability to obtain rational values of the geometric parameters of the brake pads, providing increased resource friction lining brake device.

The objective of the present invention is to develop a method for optimizing the parameters of a disk brake device, providing an increase in the friction lining resource by taking into account the influence of the geometric parameters of the friction lining and the brake disk on the value of the mechanical component of the friction power and choosing a rational ratio of their geometric parameters.

The task is achieved in that they determine the mechanical component of the friction power with the initial parameters of the friction lining, by which its volume wear rate is found, the actual friction lining life is determined from the found wear intensity, then the increment of the resource is set and the optimal values of the area and length of the friction lining are determined and radius of roughness of the brake disc according to the following relationships

$$F=\sqrt{\frac{0.6\cdot {10}^{-\mathrm{four}}\cdot I_w\cdot R\cdot \nu \cdot N^2\cdot n\left(t\right)\cdot t}{S\cdot H}}$$

$$R=\frac{F^2\cdot S\cdot H}{n\left(t\right)\cdot t\cdot 0.6\cdot {10}^{-\mathrm{four}}\cdot I_w\cdot \nu \cdot N^2}$$

$$H=\frac{0.6\cdot {10}^{-\mathrm{four}}\cdot I_w\cdot R\cdot \nu \cdot N^2\cdot n\left(t\right)\cdot t}{F^2\cdot S}$$

where F is the area of the friction lining, m ² ; I _w is the energy intensity of wear, R is the radius of microroughness of the surface of the brake disc, m; ν is the sliding velocity, m / s; N - normally directed clamping load, N; n (t) is the coefficient of the required increment of the resource; t is the actual resource of the friction lining, s; S is the height of the friction lining, m; N - the length of the friction lining, m

The essence of the proposed method lies in the fact that the increase in the resource of the brake device is achieved by reducing the value of the mechanical component of the friction power, which goes to the destruction of the friction lining, while maintaining such characteristics of the brake device as the clamping load and sliding speed.

The method is as follows.

The mechanical component of the friction power is determined at the initial parameters of the friction lining according to the following dependence

$$W_{mex}=0.6\cdot {10}^{-\mathrm{four}}\frac{R\nu N^2}{F\cdot H}$$

where R is the radius of microroughness of the surface of the brake disc, m;

ν is the sliding velocity, m / s;

N - normally directed clamping load, N;

F is the area of the friction lining, m ² ;

N - the length of the friction lining, m

By the found value of the mechanical component of the energy balance, the volumetric wear rate of the friction lining is determined by the formula

$$I_V=I_w\cdot W_{mex}=i_h\cdot \frac{W_{mex}}{f\cdot HB}$$

where I _w is the energy intensity of wear J / m ³ ,

W _fur - mechanical component of the energy balance, J / s

i _h is the specific linear wear rate, m / m;

f is the coefficient of friction;

HB - hardness, MPa.

Then, by the value of the volumetric wear rate, the actual friction lining life is determined by the following formula

$$t=\frac{H\cdot B\cdot S}{I_{\nu }}$$

 where B is the width of the friction lining;

H is the length of the friction lining;

S - the height of the friction lining, m

The determination of the mechanical component of the friction power, volumetric wear rate of the friction lining and the actual resource of the friction lining can be carried out by any known analytical dependence.

Then, depending on the planned duration of the overhaul run of the brake device, the value of the required increment of the friction lining resource n (t) is set.

So, for example, according to the Rules of the Russian Open Championship and Cup of 2012 for rally, the length of a single section of the rally along special routes varies from 10 to 50 km and can be covered from 1 hour 30 minutes to 2 hours 30 minutes, which determines the different duration of the overhaul distance of the brake devices at every stage. For example, for a stage with a maximum duration, it is necessary to increase the friction lining resource up to 1.5 times in comparison with a short stage.

The determination of the optimal values of the area, length of the friction lining and the radius of roughness of the brake disc is carried out according to empirical formulas obtained in the course of experimental studies of disc brake devices.

The area of the friction lining, providing the planned resource, is determined by the following formula

, $$F=\sqrt{\frac{0.6\cdot {10}^{-\mathrm{four}}\cdot I_w\cdot R\cdot \nu \cdot N^2\cdot n\left(t\right)\cdot t}{S\cdot H}}$$

,

The roughness of the brake disc, providing the planned life of the friction lining is determined as follows:

$$R=\frac{F^2\cdot S\cdot H}{n\left(t\right)\cdot t\cdot 0.6\cdot {10}^{-\mathrm{four}}\cdot I_w\cdot \nu \cdot N^2}$$

The length of the friction lining that provides the planned resource is determined by the following relationship

$$H=\frac{0.6\cdot {10}^{-\mathrm{four}}\cdot I_w\cdot R\cdot \nu \cdot N^2\cdot n\left(t\right)\cdot t}{F^2\cdot S}$$

where F is the area of the friction lining, m ² ; I _w is the energy intensity of wear, R is the radius of microroughness of the surface of the brake disc, m; ν is the sliding velocity, m / s; N - normally directed clamping load, H; t is the actual resource of the friction lining, s; S is the height of the friction lining, m; H - the length of the friction lining, m

The following is an example implementation of the proposed method for a brake device with the following initial characteristics:

radius of microroughness of the surface of the brake disc - 0.0000001 m;

sliding speed - 100 m / s;

normally directed clamping load - 300 H;

the friction lining area is 0.005 m ² ;

friction lining length - 0.1 m;

specific linear wear rate - 10 ^-7 ;

coefficient of friction - 0.4;

hardness - 400 MPa;

friction lining width - 0.05 m;

friction lining height - 0.01 m.

Based on the given values, the following actual characteristics of the brake device were determined:

1) the mechanical component of the friction power is 1.08 J / s:

2) the volumetric intensity of wear of the friction lining - 6.75 * 10 ^-11 m ³ / s;

3) actual resource - 205.76 hours;

4) to increase the friction lining life by 1.5 times, one of the following actions must be performed:

- 1.22 times increase the area of the friction lining while maintaining the ratio of its length to width unchanged. In this case, it will be 0.0061 m ² ;

- 1.5 times increase the length of the friction lining by reducing its width while maintaining the area at the same level. The new geometric parameters will be: length 0.15 m, width 0.033 m;

- 0.67 times reduce the radius of the protrusions of the roughness of the brake disc by increasing the purity of its processing.

Thus, the proposed method for determining the parameters of a disk brake device allows one to determine the existing friction lining resource by the mechanical component of the friction power and volumetric wear rate, and then by changing the radius of the roughness of the brake disc, the area of the friction lining and its length, increase this indicator to the required value.

Claims (1)

A method for optimizing the parameters of a disk braking device, namely, that the mechanical component of the friction power is determined at the initial parameters of the friction lining, by which its volume wear rate is found, the actual wear life of the friction lining is determined by the found wear intensity, then the resource increment is set and the resource increment is determined and determined the optimal values of the area, length of the friction lining and the radius of roughness of the brake disc according to the following relationships:

where F is the area of the friction lining, m ² ; I _w is the energy intensity of wear, R is the radius of microroughness of the surface of the brake disc, m; ν is the sliding velocity, m / s; N - normally directed clamping load, H; n (t) is the coefficient of the required increment of the resource; t is the actual resource of the friction lining, s; S is the height of the friction lining, m; H - the length of the friction lining, m