Disc Brake

Brake disc with pressure cylinder and pads.

blockType: Engee1DMechanical.Brakes.Disc

Path in the library:

/Physical Modeling/1D Mechanical/Brakes & Detents/Rotational/Disc Brake

Description

Block Disc Brake It is a brake disc made in the form of a cylinder exerting pressure on one or more brake pads that are in contact with the shaft rotor. As a result of the friction of the pads, a brake element arises that counteracts the rotation of the shaft.

Disc brake model

This figure shows the front and left views of the brake disc.

disc brake en

The brake disc converts the pressure in the brake cylinder into a force that is applied along the middle radius of the brake pad. The equation that the unit uses to calculate the braking torque depends on the speed of rotation of the disc, , so when ,

However, when , the torque applied by the brake is equal to the external torque applied to the rotor. The maximum value of the braking torque, in the case of , is defined as:

In both cases ,

Where

– braking torque;
– applied pressure in the piston;
– the speed of rotation of the disk;
– number of brake pads;
– coefficient of static friction between the pads and the rotor;
– coefficient of kinetic friction between the pads and the rotor;
– diameter of the brake piston;
– the average radius of application of the brake pad force to the rotor disc;
– outer radius of the brake pad;
– the inner radius of the brake pad.

By default, the unit simulates a dry brake. You can simulate viscous friction by setting for the parameter Viscous friction coefficient, , a nonzero value. The torque on the disk in a system with viscous friction is equal to:

Thermal model

You can simulate the effects of heat flow and unit temperature changes using port H, an optional non-directional port. To enable the port, go to settings Friction check the box for the parameter Thermal Port. The inclusion of the thermal port also allows you to change the values for the following parameters:

Friction > Static friction coefficient vector
Friction > Coulomb friction coefficient vector
Thermal Port > Thermal mass

Variables

Use the parameter group Initial Targets to set the priority and initial target values for the block parameter variables before simulation. For more information, see Configuring physical blocks using target values.

Ports

Input

# P — cylinder pressure
scalar

Details

The inlet port associated with the pressure in the cylinder.

Data types	`Float64`
Complex numbers support	I don’t

Conserving

# S — shaft
rotational mechanics

Details

A non-directional port connected to a rotating disc shaft.

Program usage name

shaft_flange

# H — heat flow
heat

Details

A non-directional port connected to the heat flow.

The thermal port allows you to simulate the heat flow between the unit and the connected network.

Dependencies

To use this port, select the check box for the parameter Thermal Port.

Program usage name

thermal_port

Parameters

Geometry

# Mean pad radius — the average mounting radius of the brake pad
m | um | mm | cm | km | in | ft | yd | mi | nmi

Details

The average radius of the brake pads.

Units	`m` \| `um` \| `mm` \| `cm` \| `km` \| `in` \| `ft` \| `yd` \| `mi` \| `nmi`
Default value	`150.0 mm`
Program usage name	`mean_radius_pad`
Evaluatable	Yes

# Cylinder bore — piston diameter
m | um | mm | cm | km | in | ft | yd | mi | nmi

Details

Diameter of the brake piston.

Units	`m` \| `um` \| `mm` \| `cm` \| `km` \| `in` \| `ft` \| `yd` \| `mi` \| `nmi`
Default value	`10.0 mm`
Program usage name	`cylinder_bore`
Evaluatable	Yes

# Number of brake pads — number of pads

Details

The number of brake pads.

Default value	`2`
Program usage name	`pad_count`
Evaluatable	Yes

Friction

# Thermal Port — The thermal model

Details

Select this option to enable heat flow and temperature changes.

Default value	`false (switched off)`
Program usage name	`has_thermal_port`
Evaluatable	No

# Static friction coefficient — static friction

Details

Coefficient of static friction. The value must be greater than the value set for the parameter. Coulomb friction coefficient.

Dependencies

To use this option, uncheck the box. Thermal Port.

Default value	`0.9`
Program usage name	`static_friction_coefficient_const`
Evaluatable	Yes

# Coulomb friction coefficient — contact friction

Details

The coefficient of Coulomb friction on the contact surface of the pad with the disc. The value must be greater than zero.

Dependencies

To use this option, uncheck the box. Thermal Port.

Default value	`0.7`
Program usage name	`coulomb_friction_coefficient_const`
Evaluatable	Yes

Details

An array of temperature values used to build a one-dimensional interpolation table of temperature and efficiency correspondence. The values of the array should increase monotonously.

Dependencies

To use this option, check the box Thermal Port.

Units	`K` \| `degC` \| `degF` \| `degR` \| `deltaK` \| `deltadegC` \| `deltadegF` \| `deltadegR`
Default value	`[280.0, 300.0, 320.0] K`
Program usage name	`temperature_vector`
Evaluatable	Yes

# Static friction coefficient vector — static friction vector

Details

The vector of values of the coefficients of static friction, such that:

The number of elements in the vector must be the same as the number of elements in the specified vector for the parameter Temperature;
The values must be greater than the corresponding values specified for the vector parameter. Coulomb friction coefficient vector.

Dependencies

To use this option, check the box Thermal Port.

Default value	`[0.9, 0.8, 0.7]`
Program usage name	`static_friction_coefficient_vector`
Evaluatable	Yes

# Coulomb friction coefficient vector — vector of contact friction

Details

The vector of values of the Coulomb friction coefficients on the contact surface of the pad with the disc, such that:

The number of elements in the vector must be the same as the number of elements in the specified vector for the parameter Temperature;
The values are monotonously increasing;
Each value must be greater than zero.

Dependencies

To use this option, check the box Thermal Port.

Default value	`[0.8, 0.7, 0.6]`
Program usage name	`coulomb_friction_coefficient_vector`
Evaluatable	Yes

Details

The angular velocity at which friction changes its model from static to kinetic.

Units	`rad/s` \| `deg/s` \| `rad/min` \| `deg/min` \| `rpm` \| `rps`
Default value	`0.1 rad/s`
Program usage name	`w_breakaway`
Evaluatable	Yes

# Viscous friction coefficient — coefficient of viscous friction
N*m*s/rad | mN*m*s/rad | kN*m*s/rad | kgf*m*s/rad | lbf*ft*s/rad

Details

The viscous friction model represents the loss of energy to the cooling/lubricating fluid between the pads and the disc. To model such a system, specify a non-zero value of the viscous friction coefficient.

Units	`Nms/rad` \| `mNms/rad` \| `kNms/rad` \| `kgfms/rad` \| `lbffts/rad`
Default value	`0.0 Nms/rad`
Program usage name	`viscous_coefficient`
Evaluatable	Yes

Thermal Port

# Thermal mass — heat capacity
J/K | kJ/K

Details

The thermal energy required to change the temperature of a component by one degree. The higher the heat capacity, the more resistant the component is to temperature changes.

Dependencies

To use this option, check the box Thermal Port.

Units	`J/K` \| `kJ/K`
Default value	`50.0 kJ/K`
Program usage name	`thermal_mass`
Evaluatable	Yes

Examples

Simulation of the movement of an electric vehicle according to the WLTC cycle