Compact magnetic solenoid valves using a composite magnetic material

摘要

The recent progress of electronic control systems in vehicles is remarkable as evidenced by the development of electronic fuel injection systems, (EFI), automatic transmission control systems, and anti-lock brake systems, (ABS). The number of actuators for the systems has been increasing. Consequently, a need has been identified for a reduction in volume and number of the system actuators for control purposes. A composite magnetic material has been developed with the aim of miniaturizing magnetic solenoid valves for actuator applications. A composite magnetic material is such that both ferromagnetic and paramagnetic sections coexist within a single material, and can contribute to optimization of the magnetic circuit of a solenoid valve. This paper describes the development of a composite magnetic material, and its resultant characteristics. The chemical composition of the material, essentially 18% chromium-8% nickel stainless steel, required to improve both ferromagnetic and paramagnetic properties and the process of producing composite magnetic properties are reported in detail. This composite magnetic material exhibited superior properties, having a magnetic flux density B40 (induction at H of 4000A/m) of 0.8 Tesla in the ferromagnetic section, and relative permeability μr of 1.01 in the paramagnetic section. The application of this material to a magnetic solenoid valve for ABS could reduce by approximately 20% volume.