At the beginning of last year, LIEBHERR customized a high-power and high-pressure excavator for their customer. 6 months later, customer complained about oil leakage. After testing, the engineer found that there was no problem with the hydraulic relief valve. The leakage was concentrated in the auxiliary valve, so it was locked as a sealing problem. After disassembling the hydraulic relief valve, it was found that it was caused by the serious wear of the sealing ring. David was responsible for the purchase of hydraulic valves. After he contacted the original factory of hydraulic relief valve, the manufacturer soon sent a new sealing ring. However, a similar situation occurred again in 2 months, and the sealing ring of hydraulic relief valve was replaced for 3 consecutive cycles. The customer was very dissatisfied with this after-sales service and complained directly to the headquarters. The boss asked David to come up with a thorough solution as soon as possible.
David was also surprised why the sealing ring of the hydraulic relief valve had to be replaced in 2 months. The manufacturer informed that the pressure and limit temperature of this equipment are very special, especially for high-frequency operation. The service life of the sealing ring of the hydraulic relief valve can only be guaranteed in 2 months, it has to be replaced every 2 months, no other solution. David contacted many other hydraulic valve manufacturers, most of them said that they could only replace the sealing ring every 2 months, and some also suggested changing the whole hydraulic system assembly of the excavator. After 1 year, David hasn't come up with a new plan yet. The customer is unhappy and the boss keeps pushing him.
David browsed AAK website and asked directly by email whether AAK has tips on the sealing ring of hydraulic relief valve or not. After receiving the drawings and working conditions of the hydraulic relief valve from David, we found that the pressure of the hydraulic relief valve is 550bar, the limit temperature is 180 ℃, and it has very high-frequency operation. Even the high temperature resistant fluororubber sealing ring is not suitable for this hydraulic relief valve.
After 3 days of thinking, AAK technical team jumped out of the dead end of thinking about the material of the sealing ring. Can we redesign the structure between the sealing ring and the valve? After the test, it was found that adding "Glyd-ring" may solve the sealing problem of the hydraulic relief valve. David asked us to design and make samples of the hydraulic relief valve installed with Glyd-ring as soon as possible. After 30 days, their engineer installed AAK hydraulic relief valve for customer. 2 months later, the customer didn't call to complain. David felt that AAK might have solved the sealing problem of the hydraulic relief valve that had plagued them for more than a year. 6 months later, there was still no leakage. David was relieved finally. The customer recognized this solution, and the boss was also very happy. In particular, their engineers appreciated AAK design ability and quality.
AAK newly designed hydraulic relief valve is to open a small groove in the contact section between the valve spool and the valve sleeve to install the dynamic seal of Glyd-ring. Most peers can't think of such installation. Even if they think of it, there may be few factories who can operate the process. Such a sealing system can ensure high-frequency friction. The material has stable performance, the pressure resistance range can be below 600bar, and the temperature range is - 30 ℃ - + 200 ℃. Through the dynamic deformation of the sealing ring, it can ensure 100% sealing and prevent the pressureless liquid leakage.
The sealing of AAK hydraulic relief valve, may be thought of by peers, but it may not be possible to do so. There are wonderful tricks in seal design. Welcome to give it a try!
AAK HYDRAULIC VALVE (141) 2022-01-19