FLAPPER AND ARMATURE/FLAPPER ASSEMBLY FOR USE IN A SERVOVALVE

• US 20170261116A1
• Filed: 01/06/2017
• Published: 09/14/2017
• Est. Priority Date: 03/10/2016
• Status: Active Grant

• Current Assignee: Hamilton Sundstrand Corporation (Raytheon Technologies Corporation d/b/a RTX)
• Original Assignee: Hamilton Sundstrand Corporation (Raytheon Technologies Corporation d/b/a RTX)
• Inventors: Sarafin, Jakub, Zgrecki, Michal
• Granted Patent: US 10,458,440 B2
• Time in Patent Office: Days
• CPC Class Codes: F15B 13/0438 the pilot valves being of the nozzle-flapper type

Abstract

A flapper for use in a servovalve is described, the flapper comprising a first material and a second material, the first material having a first coefficient of thermal expansion and the second material having a second coefficient of thermal expansion and wherein the first and second coefficients of thermal expansion are different to each other. An armature/flapper assembly is also described, which comprises this flapper as well as a plate and a torsion bridge. A method of compensating for alteration of the null of a servovalve due to temperature changes in a servovalve is also described.

Claims

1. A flapper for use in a servovalve, said flapper comprising:

a first material; and

a second material;

wherein the first material has a first coefficient of thermal expansion and the second material has a second coefficient of thermal expansion, and

wherein the first and second coefficients of thermal expansion are different than each other.

2. The flapper of claim 1;

wherein;

said flapper comprises an elongated cylindrical component that extends along a longitudinal axis from a first end to a second end, and has a length extending between said first end and said second end;

said flapper further includes a first segment comprising said first material and a second segment comprising said second material; and

said first segment and said second segment extend longitudinally along at least a part of said length.

3. The flapper of claim 2 wherein, said first segment and said second segment extend longitudinally along the full length of the flapper.

4. The flapper of claim 1, wherein the flapper is bimetallic and said first segment comprises a first metal and said second segment comprises a second metal.

5. The flapper of claim 1, wherein said first material is an aluminum alloy and said second material is molybdenum.

6. An armature/flapper assembly for use in a servovalve, said armature/flapper assembly comprising the flapper of claim 1 and further comprising

a plate, and

a torsion bridge;

said flapper comprising an elongated cylindrical component that extends along a longitudinal axis from a first end to a second end,

said flapper being connected to said plate at said first end,

said plate being connected to said torsion bridge, and

said torsion bridge being connectable to a body of said servovalve.

7. The armature/flapper assembly of claim 6 wherein said plate extends in a plane perpendicular to the longitudinal axis of the flapper.

8. A servovalve comprising:

a flapper having;

a first material

a second material;

wherein the first material has a first coefficient of thermal expansion and the second material has a second coefficient of thermal expansion, and

wherein the first and second coefficients of thermal expansion are different than each other; and

an armature assembly including;

a plate, and

a torsion bridge;

said flapper comprising an elongated cylindrical component that extends along a longitudinal axis from a first end to a second end,

said flapper being connected to said plate at said first end,

said plate being connected to said torsion bridge, and

said torsion bridge being connectable to a body of said servovalve

9. The servovalve of claim 8, further comprising:

a first nozzle and a second nozzle and wherein said flapper is positioned within said servovalve so that said first material of the flapper faces said first nozzle and said second material of the flapper faces said second nozzle.

10. The servovalve of claim 9 further comprising:

at least one permanent magnet with a coil winding, said permanent magnet being attached to a magnetically permeable armature comprising said flapper; and

means for applying an electrical current to the coils.

11. A method of compensating for alteration of the null of a servovalve due to temperature changes in a servovalve, comprising providing a flapper within said servovalve, said flapper comprising

a first material and a second material,

said first material having a first coefficient of thermal expansion and said second material having a second coefficient of thermal expansion and wherein the first and second coefficients of thermal expansion are different to each other.

12. The method of claim 11 wherein said flapper comprises an elongated cylindrical component that extends along a longitudinal axis from a first end to a second end,

said method further comprising the step of connecting said first end of said flapper to a plate and connecting said plate to a torsion bridge to form an armature/flapper assembly, and connecting said torsion bridge to said servovalve.

13. The method of claim 12 comprising the step of positioning said plate to extend in a plane perpendicular to the longitudinal axis of the flapper.

14. The method of claim 11, wherein said flapper comprises:

an elongated cylindrical component that extends along a longitudinal axis from a first end to a second end and has a length extending between said first end and said second end; and

a first segment comprising said first material and a second segment comprising said second material;

wherein said first segment and said second segment extend longitudinally along at least a part of said length; and

wherein the servovalve further comprises;

a first nozzle and a second nozzle;

wherein the method further comprises;

positioning said flapper within said servovalve so that said first material of the flapper faces said first nozzle and said second material of the flapper faces said second nozzle.

15. The method of claim 11, wherein said servovalve further comprises at least one permanent magnet with a coil winding, said permanent magnet being attached to a magnetically permeable armature comprising said flapper and the method further comprising applying an electrical current to the coil winding.