Electromagnetic driving device and flow rate controlling apparatus employing the same driving device

• US 20020101314A1
• Filed: 01/25/2002
• Published: 08/01/2002
• Est. Priority Date: 01/26/2001
• Status: Active Grant

• Current Assignee: DENSO Corporation
• Original Assignee: DENSO Corporation
• Inventors: Oishi, Kenichi, Ando, Motoyoshi, Nakane, Hiroyuki
• Granted Patent: US 6,806,802 B2
• Time in Patent Office: Days
• US Class Current: 335/256
• CPC Class Codes: F16K 31/0613 with cylindrical slides
• CPC Class Codes: F16K 31/0624 Lift valves
• CPC Class Codes: H01F 7/081 Magnetic constructions
• CPC Class Codes: H01F 7/13 characterised by pulling-force characteristics
• CPC Class Codes: H01F 7/1607 Armatures entering the winding

Abstract

Non-magnetic layers are formed on an inner circumferential wall of a housing portion 13 and an outer circumferential wall of a plunger 17, respectively. Assuming that the thickness of the non-magnetic layer of the housing portion is t0, the thickness of the non-magnetic layer of the plunger is t1, a magnetic gap formed in a radial direction between respective magnetic materials of the housing portion and the plunger which excludes the non-magnetic layers is d0, and an air gap formed in a radial direction between the non-magnetic layers when the plunger does not deviate from but remains coaxial with the housing portion is d1, the thickness are set so as to satisfy 40 μm≦t0+t1≦80 μm, d0≈100 μm. In addition, it is set such that the attracting portion becomes saturated magnetically when the value of electric current that is supplied to a coil increases to reach a predetermined value which falls between 40% or larger and 60% of smaller of a maximum value of the electric current.

Claims

1. An electromagnetic driving device comprising;

a movable core,

a stator having a housing portion for housing said movable core in such a manner as to move in a reciprocating fashion therein and an attracting portion between which and said movable core a magnetic force is generated for attracting said movable core to one of reciprocating movement directions and cooperating with said movable core to form a magnetic circuit,

a coil for generating a magnetic force which attracts said movable core to said attracting portion side when energized, and

a non-magnetic layer formed on at least one of sides where said housing portion and said movable core are situated, respectively, to diametrically face each other,

and wherein R defined as (d₁/d₀)×

100 is set so as to satisfy 20%≦

R≦

60%, when a magnetic gap which is formed in a radial direction between the housing portion and the movable core and excludes the nonmagnetic layers is defined as d0 and air gap which is formed in a radial direction between the housing portion and the movable core and includes the non-magnetic layers when the movable core does not deviate from, but remains coaxial with, the housing portion defined as d₁,

and wherein any of said attracting portion, said housing portion and said plunger portion becomes saturated magnetically when the value of electric current that is supplied to said coil increases to reach a predetermined value which falls between 40% or larger and 60% or smaller of a maximum value of electric current that is supplied to said coil.

2. An electromagnetic driving device as set forth in claim 1, wherein a non-magnetic layer is formed on at least one of sides where said housing portion and said movable core are situated, respectively, to diametrically face each other, and wherein the total thickness of said non-magnetic layer so formed falls between 40 μ

m or larger and 80 μ

m or smaller.

3. An electromagnetic driving device as set forth in claim 1 or 2, wherein the hardness of at least one of sliding surfaces of said housing portion and said movable core is made equal to or larger than HV200, and wherein a difference in hardness between said sliding surfaces is equal to or smaller than HV300.

7. A flow rate controlling apparatus comprising;

a housing having a plurality of fluid paths which penetrate through a cylindrical circumferential wall,

an electromagnetic driving device as set forth in any of claims 1 to 6,

a movable member adapted to reciprocate together with said movable core to thereby control the flow rate of fluid flowing through said fluid paths, and

biasing means for biasing said movable member in a direction opposite to a direction in which said movable core is attracted by said attracting portion.

4. An electromagnetic driving device comprising;

a movable core,

a stator having a housing portion for housing said movable core in such a manner as to move in a reciprocating fashion therein and an attracting portion between which and said movable core a magnetic force is generated for attracting said movable core to one of reciprocating movement directions and co-operating with said movable core to form a magnetic circuit, and

a coil for generating a magnetic force which attracts said movable core to said attracting portion side when energized, wherein

a non-magnetic layer is formed on at least one of sides where said housing portion and said movable core are situated, respectively, to diametrically face each other, and wherein the total thickness of said nonmagnetic layer so formed falls between 40 μ

m or larger and 80 μ

m or smaller.

5. An electromagnetic driving device as set forth in claim 4, wherein the hardness of at least one of the sliding surfaces of said housing portion and said movable core is made equal to or larger than HV200, and wherein a difference in hardness between said sliding surfaces is equal to or smaller than HV300.

6. An electromagnetic driving device comprising;

a movable core,

a stator having a housing portion for housing said movable core in such a manner as to move in a reciprocating fashion therein and an attracting portion between which and said movable core a magnetic force is generated for attracting said movable core to one of reciprocating movement directions and co-operating with said movable core to form a magnetic circuit, and

a coil for generating a magnetic force which attracts said movable core to said attracting portion side when energized, wherein

the hardness of at least one of sliding surfaces of said housing portion and said movable core is made equal to or larger than HV200, and wherein a difference in hardness between said sliding surfaces is equal to or smaller than HV300.