Research on Inertial Hydraulic Brake of Trailer Chassis

Due to its simple structure, flexibility, low cost and easy maintenance, the trailer chassis has been widely used in the fields of service support system and emergency rescue system at home and abroad. The braking performance of the trailer chassis also reflects its driving safety and stability, and is the main parameter for measuring the chassis of the trailer. At present, the chassis of domestic and foreign trailers mostly use inertial mechanical brakes, electromagnetic brakes and air brakes to brake the trailer chassis. These types of braking methods have their own advantages and disadvantages (see attached table), but in general, they can not meet the requirements of fast transfer, stable and safe braking performance of the trailer chassis.

Comparison table of various braking methods for trailer chassis

Inertial hydraulic brake scheme

Combining the advantages and disadvantages of various braking methods, and fully considering the rapid transfer and stable braking performance of the trailer chassis, we propose to adopt the inertial hydraulic braking method. This method can meet the following requirements while being able to adapt to any tractor traction:

1) The brake system can integrate emergency braking, parking brake and emergency braking into one.

2) Emergency braking when the tractor is running normally, the brake system can be fully executed.

3) When performing each brake function, the braking action should be sensitive, reliable and stable.

4) When the tractor reverses normally, the brake system does not work and the reverse function is normal.

Inertial hydraulic brake system

The brake system is mainly composed of traction ring, inertial force taking device, power take-off link, brake rope, hand brake device, brake master cylinder and oil pot (see Figure 1).

During the driving of the car train, after the main car brakes, the chassis of the trailer still travels in the original direction due to inertia until the trailer traction ring collides with the main vehicle traction hook. As the main vehicle collides with the chassis of the trailer, the inertial force-taking device moves backwards, and the brake cable is pulled by the force-taking link to drive the bracket to rotate counterclockwise, and the piston push rod of the master cylinder is pulled out to drive the brake master cylinder. Working, the pressure oil generated by the master cylinder enters the brake pipe through the oil passage system and finally flows into the wheel cylinder of the wheel. The wheel cylinder piston pushes the brake shoes around the respective support pins under the action of the pressure oil, resulting in rotation. Braking force to achieve braking.

Inertial hydraulic brake principle

The working principle of the inertia hydraulic brake system is to use the thrust generated by the tractor to brake, and the brake main pump of the hydraulic brake system is driven by the tie rod mechanism, so that the brake fluid in the main pump enters the brake cylinder under a certain pressure. The brake pump generates pressure to push the brake shoe to open, and the friction plate presses the inner surface of the brake drum to achieve braking.

Inertial force take-off device

The inertial force taking device is mainly composed of a traction ring, a sliding sleeve, a traction beam and a buffer force taking device (buffer spring, damper, guide column) and the like (see Fig. 2). Its function is that when the tractor brakes, the chassis of the trailer is compressed by the inertial force, the traction ring is compressed backwards along the sliding sleeve, and the buffer spring and the damper are driven to work. The buffer spring starts working under the given pressure condition. It is only possible to move backwards together as a driving power source for connecting the hydraulic brake linkage mechanism. The buffer spring and the damper are the core components of the inertial force pushing brake control device, and the reaction sensitivity and the oscillation of the inertial impact are well controlled. The inertial force transmission damping force and the reaction sensitivity sensing control device, which are compatible with the total mass tonnage of the trailer, have nonlinear characteristics. When the inertial impact force is taken, vibration will inevitably occur. The friction between the liquid in the damper flowing through the orifice and the viscous friction of the liquid form a vibration resistance, which converts the vibration energy into heat energy and is emitted into the surrounding air. Achieve rapid attenuation of vibration. During the use period, the smoothness of the impact process is ensured, and the braking force transmission characteristics required by the actual operation are ensured, the stable braking performance is ensured, and the reliability of the braking system is improved.

Parking brake principle

The structural principle of the parking brake is based on the parking brake operating mechanism as the input of the braking force, and the hydraulic principle is consistent with the inertia braking.

Emergency braking principle

The principle of emergency braking is connected to the tractor through the insurance wire rope. When the decoupling occurs, the main car drives the insurance wire rope to form the input of the braking force, and the hydraulic principle is consistent with the inertia braking.

It can be seen from the above that all kinds of brakes are driven by the adjusting arm bracket to drive the hydraulic mechanism to realize hydraulic braking, and the three braking modes are unified into one body and relatively independent.

Reverse removal principle

When the tractor is reversing (low speed), since the spring designed on the inertia force-taking device has a certain initial pressure, the reversing force is far less than the braking force of the inertia of the trailer on the inertial force-taking device when the tractor brakes, thereby achieving smooth operation. Reversing.

Conclusion

To solve the problem of the trailer chassis that is suitable for the traction demand of various tractors, the first problem to be solved is the braking problem. Through the research on the inertia hydraulic brake, the trailer chassis can realize the rapid transfer, and the braking system has a stable and safe system. Dynamic performance.