Solenoid actuator for high pressure valve

Claim 2

A solenoid for controlling high pressure fluid including a coil, a core in the coil, a plunger that moves longitudinally toward and from the core, a tubular plunger guide of magnetizable material surrounding the plunger, the interior of the plunger guide and the plunger within the guide being in position for contact with the high pressure fluid in a closed system when the solenoid is in use, and means for compressing the core and the plunger guide longitudinally with a prestressing force on said core and said plunger guide in a direction counter to the direction of tension stress imposed on the plunger guide by entrance of the high pressure fluid into the plunger guide whereby the prestressing force offsets some of said tension stress.

Claim 3

The solenoid described in claim 1 characterized by a reinforcing sleeve of non-magnetizable material surrounding the plunger guide and located between the outside of the plunger guide and the inside surface of the coil for imparting added hoop strength to the plunger guide for resisting radial force against the plunger guide by said high pressure fluid that enters into the plunger guide.

Claim 4

A solenoid including in combination a coil that surrounds a center space, a relatively fixed core of magnetizable material at the upper end of the center space, a plunger of magnetizable material in the space below said relatively fixed core and movable toward and from the core through a stroke, a magnetizable guide in the space and surrounding the plunger and in which the plunger slides during its stroke, the upper end of the plunger guide being closed so that fluid pressure in the guide exerts an upward thrust against the closed upper end of the guide, a side wall of the guide extending downwardly from the closed upper end and comprising a guide bearing in which the plunger slides, a part of the length of the side wall being of thin section that undergoes magnetic saturation when the coil is energized so as to concentrate more flux in the cross section of the plunger, and means for protecting the thin wall section from permanent deformation by fluid pressure in the guide, said means including connected parts compressing the plunger guide longitudinally to prestress the thin wall section in a direction opposite to that in which the thin wall section is stressed by pressure of the fluid in the guide acting against the closed upper end of said guide.

Claim 5

A solenoid including in combination a coil that surrounds a center space, a relatively fixed core of magnetizable material at the upper end of the center space, a plunger of magnetizable material in the space below said relatively fixed core and movable toward and from the core through a stroke, a magnetizable guide in the space and surrounding the plunger and in which the plunger slides during its stroke, the upper end of the plunger guide being closed so that fluid pressure in the guide exerts an upward thrust against the closed upper end of the guide, a side wall of the guide extending downwardly from the closed upper end and comprising a guide bearing in which the plunger slides, a part of the length of the side wall being of thin section that undergoes magnetic saturation when the coil is energized so as to concentrate more flux in the cross section of the plunger, and means for protecting the thin wall section from permanent deformation by fluid pressure in the guide, said means including connected parts compressing the plunger guide longitudinally to prestress the thin wall section in a direction opposite to that in which the thin wall section is stressed by pressure of the fluid in the guide acting against the closed upper end of said guide.

Claim 6

The solenoid described in claim 3 characterized by the plunger guide having thicker wall sections close together and limiting the longitudinal extent of the thin wall section and holding said thin wall section against radial deformation by the pressure in the plunger guide.

Claim 7

The solenoid described in claim 3 characterized by said connecting parts including also a flange at the lower end of the plunger guide extending radially outward under the lower end of the coil, and a housing of magnetizable material extending across the closed upper end of the plunger and down the outside of the coil to provide a flux path around the outside of the coil, said flange and housing being securely connected together and exerting longitudinal pressure on the plunger guide.

Claim 8

The solenoid described in claim 5 characterized by the flange and housing being connected with one another by screw threads and being movable longitudinally when rotated with respect to one another to screw them along the threads to adjust the compression imparted to the thin wall section of the plunger.

Claim 9

The solenoid described in claim 6 characterized by the threads being of sufficient strength and low enough pitch to compress the thin wall section to a stress in compression to offset a substantial part of the force of the fluid pressure against the closed end of the plunger and the tension effect that said fluid pressure in the plunger guide imparts to the thin wall section of the plunger guide.

Claim 10

The solenoid described in claim 3 characterized by the solenoid being a part of control means for regulating the flow of a high pressure fluid, and the guiding surfaces of the plunger guide being exposed to contact with the fluid that the solenoid controls and being subject to the pressure of that fluid, the metal of the plunger guide being one that is non-corrosive from contact with said fluid.

Claim 11

The solenoid described in claim 8 characterized by the plunger guide being stainless steel of the 300 series.

Claim 12

The solenoid described in claim 8 characterized by the plunger guide and other parts of the solenoid being of a strength to operate with fluid pressure in the plunger guide as high as 6000 pounds per square inch.

Claim 13

The solenoid described in claim 3 characterized by a sleeve of non-magnetizable material around the outside of the plunger guide and reinforcing the plunger guide against deformation by excessive hoop stresses by pressure fluid within the plunger guide and exerted against the thin wall section.

Claim 14

The solenoid described in claim 3 characterized by the relatively fixed core at the upper end of the coil having a cylindrical portion that extends downward into the space surrounded by the coil, the closed upper end of the plunger guide contacting with the upper end of said cylindrical portion and constituting a functional part of the core of the solenoid, and a compression spring between the plunger and the closed upper end of the plunger guide, said spring being held at one end in a recess in one of the confronting faces of the plunger and the closed upper end of the plunger guide.