One-sentence answer: An automotive solenoid valve integrates the electromagnetic drive and the fluid channel in the same housing, and the coil cavity must be strictly isolated from the flow channel. A micro-leak at the valve seat sealing face will cause internal leakage. Using the CTS Sentinel A28 differential pressure leak detector to compare a master part (reference part) with the part under test allows separate testing of flow channel internal leakage and coil cavity isolation, making it suitable for 100% inspection and screening on high-volume solenoid valve production lines.
One is the internal leakage of the flow channel itself, that is, whether the inlet and outlet are connected; the other is the isolation between the coil cavity and the flow channel, preventing fluid from corroding the winding or moisture from intruding into the electrical section. The two requirements have different criteria and cannot be covered by a single test program.
The mating face between the valve seat cone or flat surface and the valve spool depends on machining accuracy and assembly coaxiality. The leak rate is often at a small magnitude and needs to be judged under a stable reference.
Injection-molded parts have incomplete filling and internal shrinkage cavities, while metal parts rely on end cover O-rings and press fitting. The plugging method and pressure upper limit during testing are different.
Solenoid valves in transmission shifting, braking, fuel and thermal management systems actuate frequently. Factory testing is the only step that quantifies the initial sealing state.
Sealing locations:
Consequences of leakage: internal leakage makes the actuator respond slowly and prevents pressure from being held, manifesting as shift shock, slower braking response or injection quantity deviation; external leakage and cross-cavity leakage pollute the environment and corrode the coil, eventually leading to complete valve failure, which is a safety- and emission-related failure mode.
Solenoid valves are small-volume, high-cycle, high-volume workpieces and need to cover two different judgments:
Both should be tested, but the criteria are separate. Internal leakage refers to the cross-flow between the inlet and outlet, which determines the valve's control capability; external leakage and cross-cavity leakage refer to fluid or moisture escaping to the outside of the housing or into the coil cavity, which relates to electrical safety. Use the A28 to establish separate test programs and judge item by item, so that the results have process guidance value.
It is possible, so the test pressure must be set according to the product definition, generally controlled within a range that will not cause the spool to leave the valve seat. If the product structure determines that the spool inherently has clearance in the static state, the test state should correspond to the sealing state defined by the product and be fixed in the test program, avoiding arbitrary pressure application on site.
Note the pressure upper limit and the plugging method. Injection-molded parts may undergo elastic deformation at higher pressure or leak air from the overmolding interface, causing false leaks. It is recommended to first conduct a pressure gradient test to confirm the safe range of the housing, then use a custom-formed soft plugging surface to avoid local stress concentration.
For sealing tests of automotive solenoid valves, the two requirements of internal leakage and electrical cavity isolation must be quantified separately. The CTS Sentinel A28 uses differential pressure comparison to support fine judgment of small-volume workpieces. With custom-formed fixtures and 32 test programs, it is suitable for 100% inspection, sorting and data traceability on multi-model solenoid valve production lines.
WeChat for technical support
PLUS Douyin
