Valve assembly and servo system incorporating same

Claim 2

In a valve assembly, a housing, a needle vAlve seat carried by the housing and having an opening therein, a needle valve, a force coil assembly carrying the needle valve, means mounted in the housing forming a magnetic field about the coil assembly, yieldable means secured to the predetermined position with respect to said needle valve seat and means for supplying current to said coil to move said needle valve from said predetermined position against the force of the yieldable means to precisely meter the fluid passing through said valve seat, said yieldable means consisting of a bellows secured to the coil assembly.

Claim 3

A valve assembly as in claim 1 wherein said valve seat is formed of Teflon wherein said needle valve is formed of metal.

Claim 4

A valve assembly as in claim 1 wherein said means mounted in the housing forming a magnetic field about the coil assembly includes a permanent magnet, a pole piece adjacent said permanent magnet and having a hole therein, and an additional pole piece adjacent said magnet having an extension extending through the hole and forming an airgap between the extension and the first named pole piece, said coil assembly being disposed in said airgap.

Claim 5

An assembly as in claim 3 wherein said bellows is centrally mounted on said extension and is secured to said coil assembly.

Claim 6

In a valve assembly, a housing, a cylindrical permanent magnet disposed in said housing, a female pole piece having an opening therein adjacent one end of the cylindrical permanent magnet, a male pole piece adjacent the other end of the permanent magnet and having an extension extending through the hole in said female pole piece, a cover plate secured to said housing, a valve seat holder mounted in said cover plate for adjustment longitudinally thereof, valve seat means carried by the valve seat holder and having an opening therein, a needle valve, a coil assembly carrying said needle valve and disposed in said hole in the female pole part and receiving the extension of the male pole part and yieldable means for retaining said coil assembly and the needle valve carried thereby in a predetermined position with respect to the valve seat, said yieldable means including a bellows concentrically mounted on said extension of said male pole piece.

Claim 7

In a valve assembly, a housing, a cylindrical permanent magnet disposed in said housing, a female pole piece having an opening therein adjacent one end of the cylindrical permanent magnet, a male pole piece adjacent the other end of the permanent magnet and having an extension extending through the hole in said female pole piece, a cover plate secured to said housing, a valve seat holder mounted in said cover plate for adjustment longitudinally thereof, valve seat means carried by the valve seat holder and having an opening therein, a needle valve, a coil assembly carrying said needle valve and disposed in said hole in the female pole part and receiving the extension of the male pole part and yieldable means for retaining said coil assembly and the needle valve carried thereby in a predetermined position with respect to the valve seat, said yieldable means including a bellows concentrically mounted on said extension of said male pole piece.

Claim 8

An assembly as in claim 5 wherein said valve seat means is formed of Teflon and said needle valve is formed of a metal.

Claim 9

An assembly as in claim 5 together with means for supplying current to said coil assembly.

Claim 10

In a valve assembly, a housing, a needle valve seat carried by the housing and having an opening therein, a needle valve, a force coil assembly carrying the needle valve, a permanent magnet mounted in the housing, a pole piece adjacent said permanent magnet and having a hole therein, an additional pole piece adjacent said magnet having an extension extending through the hole and forming an airgap between the extension and the first named pole piece, said coil assembly being disposed in the airgap, yieldable bellowslike means surrounding the additional pole piece and secured to the coil assembly and normally retaining said needle valve in a predetermined position with respect to said needle valve seat.

Claim 11

In a valve assembly, a housing, a needle valve seat carried by the housing and having an opening therein, a needle valve, a force coil assembly carrying the needle valve, a permanent magnet mounted in the housing, a pole piece adjacent said permanent magnet and having a hole therein, an additional pole piece adjacent said magnet having an extension extending through the hole and forming an airgap between the extension and the first named pole piece, said coil assembly being disposed in the airgap, yieldable bellowslike means surrounding the additional pole piece and secured to the coil assembly and normally retaining said needle valve in a predetermined position with respect to said needle valve seat.

Claim 12

A valve assembly as in claim 8 wherein said needle valve seat is in the form of an assembly consisting of a valve seat holder carried by the housing, said valve seat holder having a passage therethrough, a valve seat mounted in the holder and having an opening therein in communication with the passage in said valve seat holder and being in alignment with the needle valve and being of such a size so that the needle valve can close the opening in said seat and means for establishing a seal between the valve seat holder and the housing.

Claim 13

In a valve assembly, a housing, a needle valve seat carried by the housing and having an opening therein, a needle valve, a force coil assembly carrying the needle valve, a permanent magnet mounted in the housing, a pole piece adjacent said permanent magnet and having a hole therein, an additional pOle piece adjacent said magnet having an extension extending through the hole and forming an airgap between the extension and the first named pole piece, said coil assembly being disposed in the airgap, yieldable means in the form of bellows surrounding the additional pole piece and secured to the coil assembly and normally retaining said needle valve in a predetermined position with respect to said needle valve seat.

Claim 14

In a valve assembly, a housing, a needle valve seat carried by the housing and having an opening therein, a needle valve, a force coil assembly carrying the needle valve, a permanent magnet mounted in the housing, a pole piece adjacent said permanent magnet and having a hole therein, an additional pOle piece adjacent said magnet having an extension extending through the hole and forming an airgap between the extension and the first named pole piece, said coil assembly being disposed in the airgap, yieldable means in the form of bellows surrounding the additional pole piece and secured to the coil assembly and normally retaining said needle valve in a predetermined position with respect to said needle valve seat.