Solenoid-controlled valve

A solenoid-controlled valve comprising:

• a housing having an interior control chamber and including a tubular part closed at its opposite ends by first and second end parts of non-magnetic material, said tubular part having first and second end portions of magnetic material separated by an intermediate portion of non-magnetic material;
• means defining first and second ports in said first and second end parts, respectively, communicating with said chamber, said first port having an outwardly facing first valve seat and said second port having an inwardly facing second valve seat;
• a first valve member cooperating with said first seat to close said first port;
• seating spring means urging said first valve member to seat to close said first port;
• a second valve member cooperating with said second valve seat to close said second port;
• means defining a third port in said second end part communicating with said chamber;
• first and second members in said chamber, made of magnetic material and located adjacent and movable toward and away from said first and second ports, respectively, said first member being provided with means to engage and unseat said first valve member and said second movable member being engageable with to seat said second valve member;
• fixed ported partition means of magnetic material in said chamber between said movable members and peripherally engaged with said second end portion;
• spring means engaged between said partition means and each of said movable members for urging the latter toward their respective end parts to thus unseat said first valve member against the urging of said seating spring means and open said first port and engage said second valve member and close said second port;
• a solenoid surrounding said tubular part and extending beyond the opposite ends of said intermediate portion for applying a magnetic field to the interior of said housing;
• a yoke member which, together with said tubular part, encloses said solenoid, said yoke member, said first end portion, said first movable member, said partition means, said second movable member and said second end portion defining a magnetic circuit having a magnetic flux;
• a magnetic flux by-pass for flowing magnetic flux between said second end portion and said partition means to by-pass said second movable member in said magnetic circuit, said flux by-pass being saturated with a magnetic flux smaller than that in said magnetic circuit;
• and
• means defining magnetic resistances between said second movable member and said second end portion and between said first movable member and said first and end portion, the resistance between said second movable member and said second end portion being greater than that between said first movable member and said first end portion,
• whereby application of a small electric current to said solenoid magnetically attracts said first movable member toward said partition means with sufficient force to overcome that of said spring means therebetween and allows said first valve member to seat while said flux by-pass lessens the magnetic attraction of said second movable member toward said partition means sufficiently to avoid overcoming the force of said spring means therebetween and thus said second port remains closed, and
• application of a large electric current to said solenoid causes said by-pass to become saturated with magnetic flux and flux flows through said magnetic resistance between said second movable member and said second end portion and develops sufficient magnetic attraction between said second movable member and said partition means to overcome the force of said spring means therebetween and thus unseats said second valve member and opens said second port.