IPC분류정보
국가/구분 |
United States(US) Patent
등록
|
국제특허분류(IPC7판) |
|
출원번호 |
US-0282313
(2002-10-28)
|
우선권정보 |
DE-0053019 (2001-10-26) |
발명자
/ 주소 |
|
출원인 / 주소 |
|
대리인 / 주소 |
Ostrolenk, Faber, Gerb & Soffen, LLP
|
인용정보 |
피인용 횟수 :
10 인용 특허 :
10 |
초록
▼
An electromagnet having a hollow cylindrical coil former fitted with a coil winding and surrounded by a magnet housing. The coil former is bounded by upper and lower pole shoes. A nonmagnetic metal tube in the hollow cylinder of the magnet defines an armature space for a magnet armature that divides
An electromagnet having a hollow cylindrical coil former fitted with a coil winding and surrounded by a magnet housing. The coil former is bounded by upper and lower pole shoes. A nonmagnetic metal tube in the hollow cylinder of the magnet defines an armature space for a magnet armature that divides the armature space into first and second chambers, which are connected via a pressure equalizing channel in the magnet armature. A push rod passes through an axial hole in the lower pole shoe, to a control piston of a hydraulic valve, whose interior is connected via a further pressure equalizing channel in the lower pole shoe to the first chamber of the armature space. The push rod is a profiled rod contacting the magnet armature, the rod is of a cross-sectional shape different than that of the axial hole in the lower pole shoe and of a cross-sectional area less than that of the axial hole. The magnet armature has a central longitudinal hole of a diameter smaller than the largest profile width and larger than the smallest profile width of the push rod.
대표청구항
▼
1. An electromagnet comprising:a hollow, cylindrical coil former having upper and lower ends; a coil winding fitted within the coil former; a magnet housing surrounding the coil former;an upper pole shoe at the upper end of the coil former, an electrical part resting on the upper pole shoe;a lower p
1. An electromagnet comprising:a hollow, cylindrical coil former having upper and lower ends; a coil winding fitted within the coil former; a magnet housing surrounding the coil former;an upper pole shoe at the upper end of the coil former, an electrical part resting on the upper pole shoe;a lower pole shoe at the lower end of the coil former, the lower shoe being shaped to project a distance partially into the hollow cylinder of the coil former;a nonmagnetic metal tube disposed in the hollow cylinder of the coil former and having an internal cavity which defines an armature space above the lower pole shoe;a cylindrical magnet armature fitted into the armature space, moveable along the armature space and guided in such movement by the metal tube; the magnet armature being of shorter length along the metal tube than the armature space; the magnet armature dividing the armature space into a first chamber and a second chamber separated by the armature; at least one axially extending pressure equalizing channel in the magnet armature connecting the first and second chambers of the armature space;an axial hole passing through the lower pole shoe between outside the lower pole shoe and into the first chamber of the armature space;a push rod passing through the axial hole in the lower pole shoe, being separate from and engageable with the magnet armature, extending outside the lower pole shoe and engageable with another object; the axial hole in the lower pole shoe and the push rod being respectively so shaped that the push rod is guided in the axial hole in the lower pole shoe; the push rod is a loose rod with an external profile in the axial hole; the axial hole having a first cross sectional shape and the push rod having a second cross sectional shape different than the first cross sectional shape of the axial hole, wherein the first and second cross sectional shapes have respective first and second cross sectional areas, the second cross sectional area of the rod is less than the first cross sectional area of the axial hole for defining free cross sectional spaces within the axial hole in the lower pole shoe and outside the push rod, and the free cross sectional spaces define pressure equalizing channels between the first chamber of the armature space and outside the lower pole shoe. 2. In combination, the electromagnet of claim 1 and a hydraulic valve, the valve having a valve housing with an interior and a control piston moveable in the valve housing, the push rod of the electromagnet being connected to the control piston of the hydraulic valve;the valve housing being mounted on the electromagnet at such location and in such manner that the valve housing interior is connected by a pressurized equalizing channel in the lower pole shoe to the first chamber of the armature space. 3. The combination of claim 2, wherein the non-magnetic metal tube has the form of a cup-shaped copper tube having one end which is closed and is shaped and sized as to seal the coil winding against operating fluid of the hydraulic valve and the tube being shaped to form a guide for movement of the magnet armature in the armature space. 4. The electromagnet of claim 1, wherein the magnet armature has an end face on which the push rod rests, a central longitudinal hole in the magnet armature end face with a diameter smaller than the largest width of the profile of the push rod and larger than the smallest width of the profile of the push rod, and the push rod has an end at the central longitudinal hole of the armature, the respective diameter of the central longitudinal hole and the profile of the end of the push rod are such that the end of the push rod partially covers the longitudinal hole in the armature for enabling the longitudinal hole to define a pressure equalizing channel between the first and the second chambers of the armature space of the electromagnet. 5. The electromagnet of claim 4, wherein the push rod has a polygonal profile. 6. The elec tromagnet of claim 5, wherein the polygonal profile of the push rod comprises profile edges of the rod which are rounded, or the rod having a rounded profile with at least one side flattened. 7. The electromagnet of claim 5, wherein the push rod is comprised of a brass alloy. 8. The electromagnet of claim 7, wherein the push rod is produced by extrusion without metal cutting machining or is to be cut to length by stamping. 9. The electromagnet of claim 1, wherein the push rod has a polygonal profile. 10. The electromagnet of claim 4, wherein each of the cross sectional areas of the pressure equalizing channel in the lower pole shoe which is defined between the profile of the push rod and the axial hole in the lower pole shoe, and the cross sectional area of the longitudinal hole in the magnet armature not covered by the end of the push rod each have a flow cross section of at least 0.5 mm 2 and a static operating pressure of up to 10 bar. 11. The electromagnet of claim 1, wherein the non-magnetic metal tube has the form of a cup-shaped copper tube having one end which is closed and is shaped and sized as to seal the coil winding against operating fluid of the hydraulic valve and the tube being shaped to form a guide for movement of the magnet armature in the armature space. 12. The electromagnet of claim 11, wherein the magnet armature is machined at an upper end thereof and at a lower end thereof, defining bearing points between the magnet armature and the inner face of the non magnetic metal tube, with the diameter of the magnet armature being minimally reduced between the bearing points thereof. 13. The electromagnet of claim 10, further comprising a low friction or wear reducing coating between the magnet armature and the inner face of the non-magnetic metal tube for reducing the hysteresis of the magnet armature. 14. The electromagnet of claim 13, wherein the lower friction coating comprises a PTFE coating on at least one of the magnet armature and the non magnetic metal tube. 15. The electromagnet of claim 13, wherein the magnet armature is machined at an upper end thereof and at a lower end thereof, defining bearing points between the magnet armature and the inner face of the non magnetic metal tube, with the diameter of the magnet armature being minimally reduced between the bearing points thereof.
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