A dual-channel breather on an air booster pump for construction machinery

A dual-channel breather on an air booster pump for construction machinery

Abstract: Starting from the adaptability of the air booster pump in construction machinery, a structural principle and working process of a dual-channel breather with drainage function are proposed.

Key words: Braking system, air booster pump, breather

I. Introduction:

Due to the harsh working conditions of construction machinery, some wheeled construction machinery equipped with dry braking systems often experience braking failure. As the main braking component, the air booster pump is a component that is prone to failure. This article briefly discusses the structure and principle of a dual-channel breather on an air booster pump used in construction machinery from the perspective of adaptability.

Ii. Structure and Working Principle of Air Booster Pump in Braking System

The braking systems of the existing wheeled walking machinery mostly use compressed air generated by the engine compressor to increase the pressure of the synthetic brake fluid, thereby pressing the brake friction pads and achieving the braking effect. The air booster pump is the main device for increasing the pressure. The air booster pump is divided into two parts: the cylinder and the hydraulic master cylinder, as shown in Figure 1.

When braking, the compressed air entering from the foot pedal pushes the piston 3 to overcome the resistance of the return spring 4. Through the push rod, the piston 8 of the hydraulic master cylinder moves to the right, expelling the air in the cylinder through the breather. The brake fluid in the master cylinder generates high pressure and enters the piston cylinder of the brake. When the brake pedal is released, the compressed air returns from the joint, and the pistons 3 and 8 return to their original positions under the action of the spring. Outside air enters the cylinder through the breather. The brake fluid of the brake flows back into the master cylinder through the oil pipe, and the master cylinder piston returns to its original position. The brake fluid returns to 6 oil cups. Due to the frequent operation of the braking system and the harsh working environment, a large amount of dust and moisture enter the booster pump through the breather or compressed air. The breather usually provided is a straight-through type with a filter.

1. Hollow core bolt 2 isolation plate 3 Filter cotton 4 Rubber cover

Figure 2 Structure of the old-fashioned respirator

As shown in Figure 2 or a similar structure: between the perforated rubber cover and the perforated isolation plate, filter cotton is filled, and then the rubber cover is pressed against the head of the hollow bolt. In this way, during the operation of the booster pump, the air must pass through the filter cotton for filtration before entering the air chamber. However, the moisture in the braking system and impurities produced during the movement of the piston cannot be discharged and adhere to the inner surface of the cylinder barrel, forming rust. This can easily lead to braking failure and cause major accidents. Moreover, when the temperature drops below zero, the moisture in the system can freeze, causing the booster pump to freeze and fail. Once the breather is blocked, the air in the booster pump cannot be replenished, resulting in braking lag. It affects the braking effect, poses safety hazards and threatens life and property. In order to enable the air booster pump to automatically remove impurities and moisture from the inner surface of the cylinder during operation, reduce rust caused by moisture inside the booster pump, minimize accidents resulting from the failure of the air booster pump, improve its dust-proof performance, and minimize potential safety hazards, a dual-channel breather for the air booster pump used in construction machinery has been designed.

Iii. Structure and Working Principle of the New Dual-Channel Respirator

This type of respirator needs to be installed at the very bottom of the booster pump, and a small hole should be drilled on the end cover of the booster pump, as shown in Figure 3.

When the booster pump is drawing in air, spring 6 pushes the core 7 to the left end, covering the small hole B. The holes on the core are staggered from those on the spring seat 2, allowing air to pass through the coarse filter cotton 4, the fine filter screen on the core, and hole A into the booster pump. When the booster pump is exhausting, due to the presence of the fine filter screen, there is a pressure difference in the air before and after the fine filter. Gently push the core 7 (as shown in Figure 4) to compress the spring 6 and move it to the right. The small hole B will open. When air enters the respirator through hole A, due to the change in the hole diameter, a low-pressure area will be created, and dust, moisture, etc. will enter the respirator through the small hole B with the air. When the core moves to the right, the holes on the core coincide with those on the spring seat, and the air is directly discharged from the respirator without passing through the filter screen. This enables the air booster pump to automatically remove dust, moisture and other substances during operation, thereby enhancing the service life of the air booster pump and the reliability of the braking system. If the booster pump is installed at a temperature of 3 to 5 degrees, it will be more conducive for water to flow to hole B, and the effect will be better.

Four. The new dual-channel respirator has the following advantages and effects:

a) It enables the air booster pump to have a strong anti-fouling ability, automatically removing dust and moisture from the booster pump during operation, thereby enhancing the lifespan and reliability of the braking system.

b) Due to the presence of the fine filter screen, the intake air undergoes two-stage filtration, significantly enhancing the filtration accuracy. This makes the braking system cleaner and greatly improves the system performance.

c) As all the respirators are detachable components, they are easy to maintain and have strong interchangeability.

d) Due to the continuous movement of the core during operation and slight impacts, the filter screen can automatically shake off the dust, thus extending the working time.