阅读说明：本技术 一种重型车辆的制动控制方法 (Brake control method of heavy vehicle ) 是由 史德刚 孙鸿玲 王睿喆 于 2020-07-21 设计创作，主要内容包括：本发明公开了一种重型车辆的制动控制方法,根据理想的前、后轴制动力分配关系,以保证重型车辆在制动时的方向稳定性为主要依据,制定了固定比例前、后轴制动力分配策略,在保证制动方向稳定性的基础上最大限度地利用电机进行制动,针对重型机械的特殊性和其内部电池系统、电机转速、液压制动系统以及电机制动能力进行综合协调,保证了制动的可靠性,并最大限度地进行了能量的回收。(The invention discloses a brake control method of a heavy vehicle, which is characterized in that according to an ideal front axle and rear axle brake force distribution relation, a fixed proportion front axle and rear axle brake force distribution strategy is established on the basis of ensuring the directional stability of the heavy vehicle during braking, a motor is utilized to brake to the maximum extent on the basis of ensuring the directional stability of the braking, the comprehensive coordination is carried out according to the particularity of the heavy machine, the rotating speed of the motor, a hydraulic brake system and the braking capacity of the motor, the reliability of the braking is ensured, and the energy recovery is carried out to the maximum extent.)

1. A parking brake control method for an engineering vehicle is characterized in that the heavy vehicle is provided with four brake wheel cylinders, the pressure between the four brake wheel cylinders is independent, and the hydraulic brake torque of each wheel can be independently controlled; the heavy vehicle braking control method is completed by adopting a braking system, wherein the braking system comprises a battery system, a hydraulic system, a vehicle control unit and a motor controller, and the battery system comprises a power battery pack and a battery management system; the hydraulic system comprises a hydraulic brake controller, a brake master cylinder, an energy accumulator, an electromagnetic valve and other hydraulic units, wherein the brake wheel cylinder is positioned at a wheel, the electromagnetic valve controls the on-off of the brake wheel cylinder and the brake master cylinder, each brake wheel cylinder is provided with a brake pressure sensor, the hydraulic brake torque of each wheel is independently controlled, a driver makes judgment on whether braking is needed according to the braking requirement, and after the driver executes braking operation, the brake mode is distributed according to the specific braking strength, and the hydraulic brake system is characterized in that: when braking, when the maximum motor braking torque which can be generated by a single wheel is larger than the braking torque required by the single wheel, only the motor braking force is used for braking; when the single wheel is braked, when the maximum motor braking torque of the single wheel is smaller than the required braking torque, the maximum motor braking torque is used for braking, and meanwhile, the hydraulic system provides extra compensation braking torque; when braking, if wheel locking occurs, the ABS system starts to work, the motor braking function is quitted, and the required braking torque is provided by the hydraulic braking system.

2. A brake control method for a heavy vehicle according to claim 1, wherein the maximum braking torque of the motor during braking is further limited by the maximum charging current of the power battery, which is reflected by the remaining capacity, and during charging, when the remaining capacity of the battery is at a medium level, the maximum allowable chargeable current value is large, when the remaining capacity of the battery is excessive, the maximum allowable chargeable current value of the battery is small, and when the remaining capacity of the battery is more than 80%, the motor braking is not performed.

3. The brake control method of a heavy vehicle according to claim 2, wherein the front and rear axle braking forces Fh are calculated based on the braking force distribution curve, and the maximum motor braking force Fm is calculated based on the wheel rotational speed; if Fh > Fm, a combined braking mode of motor braking and hydraulic braking is adopted.

4. The brake control method of a heavy-duty vehicle according to claim 3, wherein the braking force of said motor brake is Fm and the braking force of said hydraulic brake is Fh-Fm.

5. The brake control method of a heavy vehicle according to claim 4, wherein the brake force distribution curve is:

in the formula:

F_μ2-rear wheel braking force;

F_μ1-front wheel braking force;

g-gravity of the heavy vehicle;

h_g-the height of the centre of mass of the heavy vehicle;

l-wheelbase of the front and rear axles of the heavy vehicle;

b-distance of the center of mass of the heavy vehicle from the center line of the rear axle.

Technical Field

The invention relates to the field of braking, in particular to a braking control method of a heavy vehicle.

Background

The traditional rear-drive heavy commercial vehicle and engineering transport vehicle have complex working environment, often run on a road surface with low adhesion coefficient such as sand, mud, ice and snow and the like or a road surface with large gradient, and usually involve frequent braking and turning operation due to the particularity of the working environment and the working state, for example, a bulldozer usually repeatedly reciprocates on a route during engineering operation, so that the bulldozer can continuously brake, and the heavy vehicle has large weight, so that the kinetic energy of the vehicle is also large, a large amount of energy can be wasted during braking, if the energy of the braking kinetic energy is not effectively utilized, the phenomenon that braking equipment is heated and locked due to the large friction braking phenomenon can be caused, the physical structure of the heavy vehicle is greatly damaged, the service life of the heavy vehicle is shortened, and the energy recovery through simple is not a main technical obstacle in the field, the comprehensive coordination is carried out aiming at the particularity of heavy machinery and the internal battery system, the motor rotating speed, the hydraulic braking system and the motor braking capacity of the heavy machinery, and the technical problem to be solved in the industry at present is urgently needed.

Disclosure of Invention

In view of the above drawbacks or needs for improvement in the prior art, the present invention provides a parking brake control method for a construction vehicle, wherein the heavy vehicle has four brake cylinders, the pressures of the four brake cylinders are independent of each other, and the hydraulic braking torque of each wheel can be independently controlled; the heavy vehicle braking control method is completed by adopting a braking system, wherein the braking system comprises a battery system, a hydraulic system, a vehicle control unit and a motor controller, and the battery system comprises a power battery pack and a battery management system; the hydraulic system comprises a hydraulic brake controller, a brake master cylinder, an energy accumulator, an electromagnetic valve and other hydraulic units, wherein the brake wheel cylinder is positioned at a wheel, the electromagnetic valve controls the on-off of the brake wheel cylinder and the brake master cylinder, each brake wheel cylinder is provided with a brake pressure sensor, because the pressures of the four brake wheel cylinders are mutually independent, the hydraulic brake torque of each wheel is independently controlled, a driver makes a judgment whether to brake according to the brake requirement, and after the driver executes the brake operation, the brake mode is distributed according to the specific brake strength, the hydraulic brake system is characterized in that: when braking, when the maximum motor braking torque which can be generated by a single wheel is larger than the braking torque required by the single wheel, only the motor braking force is used for braking; when the single wheel is braked, when the maximum motor braking torque of the single wheel is smaller than the required braking torque, the maximum motor braking torque is used for braking, and meanwhile, the hydraulic system provides extra compensation braking torque; when braking, if the wheels are locked and the ABS system starts to work, the motor braking function is quitted, and the required braking torque is completely provided by the hydraulic braking system;

specifically, the maximum braking torque of the motor during braking is limited by the maximum charging current of the power battery, the limitation is reflected by the residual capacity, in the charging process, when the residual capacity value of the battery is in a medium level, the allowed maximum chargeable current value is larger, when the residual capacity value of the battery is too large, the allowed maximum chargeable current value of the battery is smaller, and when the residual capacity value of the battery is larger than 80%, the motor is not braked;

specifically, front and rear axle braking force Fh is calculated according to a braking force distribution curve, and maximum motor braking force Fm is calculated according to the rotating speed and the speed of wheels; if Fh is larger than Fm, a combined braking mode of motor braking and hydraulic braking is adopted;

specifically, the braking force of the motor brake is Fm, and the braking force of the hydraulic brake is Fh-Fm;

specifically, the braking force distribution curve is as follows:

in the formula:

F_μ2-rear wheel braking force (N);

F_μ1-front wheel braking force (N);

g-gravity (N) of the heavy vehicle;

h_g-the height of the centre of mass (m) of the heavy vehicle;

l-wheelbase (m) of the front and rear axles of the heavy vehicle;

b-distance (m) of center of mass of heavy vehicle from center line of rear axle

The braking force distribution curve is an ideal front and rear axle braking force distribution curve. When the actual braking force distribution curve is positioned below the curve, the front wheels can be locked before the rear wheels, and the steering capacity is lost; when the actual braking force distribution curve is located above the curve, the rear wheel is locked before the front wheel, the longitudinal adhesion utilization rate of the rear wheel is maximum at the moment, and the rear axle is easy to destabilize and sideslip under the action of a slight lateral force. Therefore, the braking force distribution curve of the distributed drive electric vehicle should be made lower than the curve.

Has the advantages that:

according to an ideal front axle and rear axle braking force distribution relation, a fixed proportion front axle and rear axle braking force distribution strategy is formulated based on the main basis of ensuring the directional stability of the heavy vehicle during braking. After the total braking force applied to a single wheel is determined, a distribution strategy of motor braking force and hydraulic braking force is formulated according to the external characteristics of the in-wheel motor, the motor is utilized to brake to the maximum extent on the basis of ensuring the stability of the braking direction, namely, the comprehensive coordination is carried out according to the particularity of heavy machinery, an internal battery system, the motor rotating speed, a hydraulic braking system and the motor braking capacity, the braking reliability is ensured, and the energy recovery is carried out to the maximum extent.

Drawings

FIG. 1 is a strategy flow diagram of a heavy vehicle braking control method;

FIG. 2 is a structural diagram of a heavy vehicle braking system.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. In addition, the technical features involved in the embodiments of the present invention described below are combined with each other as long as they do not conflict with each other.

1-2, the invention provides a parking brake control method for a construction vehicle, wherein the heavy vehicle is provided with four brake cylinders, the pressure between the four brake cylinders is independent, and the hydraulic brake torque of each wheel can be independently controlled; the heavy vehicle braking control method is completed by adopting a braking system, wherein the braking system comprises a battery system, a hydraulic system, a vehicle control unit and a motor controller, and the battery system comprises a power battery pack and a battery management system; the hydraulic system comprises a hydraulic brake controller, a brake master cylinder, an energy accumulator, an electromagnetic valve and other hydraulic units, wherein the brake wheel cylinder is positioned at a wheel, the electromagnetic valve controls the on-off of the brake wheel cylinder and the brake master cylinder, each brake wheel cylinder is provided with a brake pressure sensor, because the pressures of the four brake wheel cylinders are mutually independent, the hydraulic brake torque of each wheel is independently controlled, a driver makes a judgment whether to brake according to the brake requirement, and after the driver executes the brake operation, the brake mode is distributed according to the specific brake strength, the hydraulic brake system is characterized in that: when braking, when the maximum motor braking torque which can be generated by a single wheel is larger than the braking torque required by the single wheel, only the motor braking force is used for braking; when the single wheel is braked, when the maximum motor braking torque of the single wheel is smaller than the required braking torque, the maximum motor braking torque is used for braking, and meanwhile, the hydraulic system provides extra compensation braking torque; when braking, if wheel locking occurs, the ABS system starts to work, the motor braking function is quitted, and the required braking torque is provided by the hydraulic braking system.

Specifically, the maximum braking torque of the motor during braking is also limited by the maximum charging current of the power battery, the limitation is reflected by the residual capacity, the maximum allowable chargeable current value is larger when the residual capacity value of the battery is in a medium level during charging, the maximum allowable chargeable current value of the battery is smaller when the residual capacity value of the battery is too large, and the motor braking is not performed when the residual capacity value of the battery is more than 80%.

Specifically, front and rear axle braking force Fh is calculated according to a braking force distribution curve, and maximum motor braking force Fm is calculated according to the rotating speed and the speed of wheels; if Fh > Fm, a combined braking mode of motor braking and hydraulic braking is adopted.

Specifically, the braking force of the motor brake is Fm, and the braking force of the hydraulic brake is Fh-Fm.

Specifically, the braking force distribution curve is as follows:

in the formula:

F_μ2-rear wheel braking force (N);

F_μ1-front wheel braking force (N);

g-gravity (N) of the heavy vehicle;

h_g-the height of the centre of mass (m) of the heavy vehicle;

l-wheelbase (m) of the front and rear axles of the heavy vehicle;

b-distance (m) of the center of mass of the heavy vehicle from the center line of the rear axle;

the braking force distribution curve is an ideal front and rear axle braking force distribution curve. When the actual braking force distribution curve is positioned below the curve, the front wheels can be locked before the rear wheels, and the steering capacity is lost; when the actual braking force distribution curve is located above the curve, the rear wheel is locked before the front wheel, the longitudinal adhesion utilization rate of the rear wheel is maximum at the moment, and the rear axle is easy to destabilize and sideslip under the action of a slight lateral force. Therefore, the braking force distribution curve of the distributed drive electric vehicle should be made lower than the curve.

It will be understood by those skilled in the art that the foregoing is only a preferred embodiment of the present invention, and is not intended to limit the invention, and that any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the present invention.