Process and apparatus for the recognition of the state of a solenoid valve

An apparatus for the recognition of the state of an electromagnetically controlled valve, comprising:

• a control circuit,
• a regulated current switching circuit, connected to and controlled by said control circuit, wherein said switching circuit generates a first magnitude switching current and a second magnitude switching current, said first magnitude switching current being greater than said second magnitude switching current,
• said electromagnetically controlled valve, having said armature within a coil, said coil being connected to said regulated current switching circuit, wherein when said first magnitude switching current flows through said coil, said armature moves to its switch on position, and wherein when said second magnitude switching current flows through said coil after said armature is in said switch on position, said armature is held in said switch on position,
• a frequency detector, connected to said coil circuit of said electromagnetically controlled valve,
• wherein when said armature of said electromagnetically controlled valve drops off from a switch on position, and wherein the resulting increase in frequency of said second magnitude switching current exceeds a predetermined threshold value, an error signal is generated by said apparatus.