CONTROL MAGNET FOR HYDRAULIC CONTROL SYSTEM VALVES

• US 3,851,285 A
• Filed: 10/10/1973
• Issued: 11/26/1974
• Est. Priority Date: 11/11/1972
• Status: Expired due to Term

• Current Assignee: Georg Rothfuss, Heinz Gand, Wilfried Paul Bohringer, Wolfgang Bredenbrock
• Original Assignee: Georg Rothfuss, Heinz Gand, Wilfried Paul Bohringer, Wolfgang Bredenbrock
• Inventors: Rothfuss, Georg, Gand, Heinz, Bredenbrock, Wolfgang, Bohringer, Wilfried Paul
• Primary Examiner(s): Harris, G.
• Application Number:
  US05/405,101
• Time in Patent Office: 412 Days
• Field of Search: 335/255,257,260,262,251,261,258 251/129
• US Class Current: 335/262
• CPC Class Codes: F16H 2710/22 the control being electric
• CPC Class Codes: F16H 61/00 Control functions within control units of change-speed- or reversing-gearings for conveying rotary motion ; Control of exclusively fluid gearing, friction gearing, gearings with endless flexible members or other particular types of gearing
• CPC Class Codes: F16H 61/0251 Elements specially adapted for electric control units, e.g. valves for converting electrical signals to fluid signals
• CPC Class Codes: F16K 31/06 using a magnet , e.g. diaphragm valves, cutting off by means of a liquid
• CPC Class Codes: H01F 2007/085 Yoke or polar piece between coil bobbin and armature having a gap, e.g. filled with nonmagnetic material
• CPC Class Codes: H01F 7/1607 Armatures entering the winding

Abstract

A control magnet for a valve of a hydraulic control system has an armature axially movable on a shaft mounted in bearings for axial displacement. A compression spring between one end of the shaft and an end of the casing surrounding the device has a stiffness low enough so as to push the armature partly out of the coil all the way to its rest position from any initial position. The armature has longitudinal bores and grooves so that the surrounding medium will not interfere with quick operating time of the magnet. An annular core extends part way inside the winding and surrounds the compression spring.

Claims

1. A control magnet suitable for magnetic valves comprising:

a casing (11);

an annular magnet winding (26) inside said casing;

an armature (19) movable within said casing affixed on a rod (18) provided with bearings mounted in said casing for guiding and permitting axial movement of said armature in and out of said winding coaxially therewith, said armature being affixed to said rod at a position on said rod which is between said bearings and being provided with axially extending cavities, (24,

     25), said rod having one extremity protruding into said winding and the other extremity wholly outside of said winding; and

a compression spring held between said casing and the extremity of said rod which protrudes into said winding and arranged to urge said rod out of the space enclosed by said winding.

2. A control magnet as defined in claim 1 in which said compression spring (16) has a stiffness sufficiently small and an axial displacement in compression sufficiently large that said armature (19) is pressed all the way to its end rest position by said spring from any position it may assume when released, whereas the force of said compression spring may nevertheless be overcome by the attraction of the armature from its end rest position when said winding is energized.

3. A control magnet as defined in claim 1 in which at least part of said cavities are axially oriented grooves (24) on the periphery of said armature (19).

4. A control magnet as defined in claim 1 in which at least part of said cavities are bores (25) parallel to the axis of said armature (19).

5. A control magnet as defined in claim 1 in which said bearings are ball bearings disposed for axial movement of said rod.

6. A control magnet as defined in claim 1 in which said bearings are sliding surface bearings provided with polytetrafluoroethylene layers on the bearing surfaces.

7. A control magnet as defined in claim 1 in which said casing (11) provides a ferromagnetic path for the magnetic flux.

8. A control magnet as defined in claim 1 in which near the end of said winding away from said compression spring (16) a re-entrant cylindrical projection (33) of said casing provides a recess into which said end of said armature fits with a peripheral air gap.

9. A control magnet as defined in claim 8 in which in the quiescent position of said armature (19) said recess of said casing (11) closely surrounds said body of said armature for at least half of its axial length.

10. A control magnet as defined in claim 1 in which a tubular core (14) affixed to said casing extends inside said winding and slightly overlaps, without touching, said armature in the rest position of said armature, and also surrounds said compression spring (16).

11. A control magnet as defined in claim 10 in which said body of said armature (19) is beveled towards its end which is nearer to said compression spring (16).

12. A control magnet as defined in claim 11 in which the free end of the inner surface of said core (14) has an outward flare (31).

13. A control magnet as defined in claim 4 in which said armature includes an inner portion made of molded synthetic material forming an intermediate layer between the magnetic portion of said armature and the rod (18) on which said armature is mounted, and in which said bores (25) are located in the portion of said armature which is made of synthetic material.

14. A control magnet as defined in claim 1 in which said rod (18) is a substantially cylindrical rod and has a diameter that is less than half as great as the diameter of said armature (19).