Due to the internal structure of the car, it is impossible to complete the filling in such a short period of time by conventional means. Therefore, the vehicle braking system must be evacuated first, and when the pressure reaches a certain degree of vacuum, the liquid is under pressure. Join below. And it is required to judge whether there are any leakages in the various systems of the car through vacuum change of the system at the same time as vacuum, which is particularly important for the brake system of the car. Therefore, the degree of vacuum in the system will directly affect the braking performance of the car. 1 is the requirement for the system vacuum degree when BOSE automobile brake system is filled with brake fluid, that is, the vacuum degree of the brake fluid tank, the front wheel, and the rear wheel of the filling head and the automobile is required to be vacuumed. At the time of 30s, they were pumped to 110Pa, 140Pa and 1000Pa, respectively. The indicators that can be controlled are the vacuum degree of the tank mouth. The vacuum degree of the front and rear wheels is naturally formed in the interior of the car.
At present, the existing filling machine generally adopts 2 pipelines, namely one for vacuum and one for filling. Since the vacuum line is also in contact with the liquid, the liquid remaining in the line will begin to vaporize at a high degree of vacuum when the next vacuum is drawn, thereby affecting the degree of vacuum of the system. The existing method can only make the system vacuum reach 800-1000 Pa within 30s, which will directly affect the braking effect. To avoid this problem, in general, each vehicle must be manually vented at the end of the brake pipe at the rear wheel after the filling is completed, which greatly affects the efficiency of the car production line and leads to the car. One person on the production line raises the strange phenomenon of two people exhausting.
German BOSE automotive system vacuum requirements solution The filling machine works as shown in Figure 2, the filling head uses 3 valves combined in the filling head inside the method to reduce the filling head volume, so that The manual operation of the workers is more convenient. The three valves are pneumatically controlled shut-off valves that are controlled by the PLC through solenoid valves to form a three-port valve body (Figure 3). The three functions of vacuum pumping, filling and pumpback are completely separated to maintain The vacuum system dries and the vacuum degree of the system can reach below 100 Pa in 30 seconds, which will fundamentally avoid the problem of vacuum degree reduction caused by the brake fluid gasification in the vacuum system.
The three pistons in the three-hole valve body are hollow, and the upper part of the three-body valve body is respectively connected with vacuum pumping, filling and withdrawing piping, making it part of the piping. This is done to save space.
All three valves are spring-controlled and normally closed. The spring is located at the upper end of the piston. Under the action of spring force (150N), the piston is pressed against the bottom of the three-hole valve body and sealed with the end face of the piston, between the two. A PTFE sealing gasket with good corrosion resistance keeps the filling head in good airtightness. When each air inlet is vented separately, the piston moves upwards under the pressure of the compressed air, and the sealing part is opened to become a passage. The three valves through the three-hole body part pass through the connecting body and are two-way, ie, filling and returning. The pumping is performed all the way, and the vacuum is detached all the way to complete the introduction of the gas or liquid through the three-hole valve body into or out of the filled container, and the liquid (or gas) in the piston communicates with the lower part and flows to the connecting body. Due to the upward movement of the piston, the space of the spring chamber becomes smaller. In order to avoid the back pressure caused by the compression of the air, an air outlet is provided in the upper part of the three-hole valve body for ventilation. Specifically shown in Figure 4.
The filling machine workflow is shown in Figure 5. In the filling process, Figure 2 filling machine working principle Figure 1 - valve vacuum channel; 2 - vacuum valve drive air flow line; 3 - valve filling channel; 4 - filling valve to drive the air flow pipe; Valve evacuation channel; 6-retract valve drive air flow line; Figure 3 three-hole valve body 1-spring gland; 2-hole valve body;3-spring; 4-piston; 5-bottom drag cover; 6-Gaskets; 7-Connecting bodies; 8-Filling and Withdrawing Two Valves are merged here to one way; 9-Bottom Towing; 10-Seal; 11-Air Inlet; 12-Air Outlet Figure 4 Three holes Valve body and connecting body connection Figure 32 - - - - - - - - Page 3 - - - - - - Volume 20, Issue 1 First of all, the container to be filled Leak detection. After the filling head is automatically mounted on the tank port of the brake fluid, the vacuum valve is opened to vacuum the vehicle brake system, and there is a pressure holding time of 5 to 10 seconds. The vacuum value is used to determine the system pressure. Whether the moving system has leaked. When it is found that there is leakage in the brake system, a fault signal will be sent to stop filling. When it is confirmed that there is no leakage, the brake system must be vacuumed again until the tank of the brake fluid tank approaches absolute vacuum. That is, about 100 to 120 Pa.
After the leak check is completed, the vacuum valve is closed, the fill valve is opened, and the brake system is filled. When it is full, close the filling valve, open the retraction valve and the vacuum valve, let the compressed air enter the brake system through the vacuum valve, so that the excess brake fluid in the system will be pumped back through the retraction valve and its corresponding pipeline. At this point in the three valves, the filling valve is closed, the vacuum and the retraction both open, one inlet and one suction, forming a loop. At the outlet of the filling head retraction pipeline, a back-suction liquid level control tube is fixed by means of interference fit. The depth of the tube deep into the vehicle brake fluid reservoir is the controlled liquid level.
During the entire filling process of vacuuming, filling and withdrawing, the vacuum valve and its vacuum pipeline are not in contact with the liquid, but are only used as passages for air in and out, so there is no problem of liquid residue, and of course there is no liquid gas. The phenomenon of occurrence.
Conclusion The filling head has been tested in practice on the production line. Its indicators fully meet the requirements of the filling process. It has exceeded certain imported equipment in improving the vacuum degree of the system. Japanese equipment used on the Changhe Doosan Automobile Production Line has an index of vacuum of 400 Pa. Generally, the German equipment is 133 Pa. The vacuum index of this filler head is not more than 100 Pa (it has been used on the Geely Free Ship car production line). The design of the filling head is innovative, advanced and feasible, and has already applied for national patents. It fills the domestic gap to a certain extent and has a great promotion prospect.
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