US2769943A - Electromagnetic control device - Google Patents

Description

Nov. 6, 1956 R B. MATTHEWS 2,769,943

ELECTROMAGNETIC CONTROL DEVICE Filed April 20, 1953 V W1 Ex P19. 1. x 5 35 -27 W1 7 -32 25 I [/0 12 r 22 29 LE H 21 26 I 5 5% 5.; I 3 5 37 g 4 E E 23 24cm v0 I8 37 P T 36 v INVENTOR. Fl E 505562]! 5. difafffwzai 5 BY United States Patent Ofitice a Patented Nov. 5, iii-t;

2,7 69 ,9 43 ELECTROMAGNETIC CONTROL DEVICE Russell B. Matthews, Milwaukee, Wis., assignor to Mil waukee Gas Specialty Company, Milwaukee, Wis., a corporation of Wisconsin Application April 20, 1953, Serial No. 349,667 12 Claims. (Cl'. 317-168) This invention relates to improvements in electro magnetic control devices.

In the development of control and operating devices Examples of apparatus requiring large initial forces for actuation are fluid control valves on electrical switches having high contact pressures and/or snap acting means. In the case of a valve,

requirement. Repulsion type electromagnetic operators are particularly well suited to applications requiring high initial force, since this type of operator exerts its maximum force at the start of its stroke. In contrast Patent No. 2,637,344, 121,817, filed October 17, 1949, now Patent No. 2,637,343, illustrate specific forms of electromagnetic repulsion type actuators embodied in fuel control valves. The cop'ending application of Gifiord I. Holmes and Russell B. Matthews, Serial No. 180,482, filed August 19, 1950, illustrates an forms therewith a low voltage It is a principle object of the present invention to by the absence of a wound rotor or movable coils requiring flexible leads and eliminating the necessity for laminated magnetic structure.

Another object of the invention is to provide an im- Another object of the invention is to provide an improved control device of the character described which, when embodied in a fluid control valve, has all of its electrical parts located away from the fluid stream so that there is no danger of umming or sticking of the parts as a result of contamination by foreign matter carried in the fluid stream.

A- further' object of the invention is to provide an improved control device of the character described which is compact in construction and which, when embodied in a fluid control valve, is removable from the valve body More specifically an object of the invention is to provide an improved control device of the character described having a primary coil and having a flux diverting secondary coil in coaxial radially spaced relation with a central magnetically permeable core portion, there being a tubular core portion coaxially within the primary coil and spaced from the central core portion to provide an equivalents thereof. in the drawing accompanying and forming a part of this specification and illustratin one com lete embodi- Figure 2 is a sectional plan view taken approximately along the line 22 of Figure 1.

Referring more particularly to the drawing, the improved electromagnetic control dev1ce is indicated by operated thereby. It is understood, of course, that the invention may be employed for corn trolling other devices or apparatus if desired.

The valve 6 has a tubular body 7 affording an inle and outlet 7a and 721, respectively, and is provided intermediate its length with an annular valve seat 3, the axis of which may extend diametrically of the body 7. The valve body is also preferably formed with an internally threaded tubular extension 9 which may be coaxial with the valve seat 8; A movable valve member 1% is faced with a layer of suitable resilient facing material It seating of the valve member 1%.

The electromagnetic control device or operator 5 is is best described as follows:

A centrally bored circular base plate or end Wall 14 interposed between the plate 14 and the adjacent end of the tubular extension 9. An elongated upstanding cylindrical core 17 has its lower end press fitted into the central aperture of the plate 14. A centrally bored circular plate 13 is formed with a coaxial annular boss 15 and is press fitted on the upper end of the core 17 in sealing relationship. The core 17 and end walls 13 and 14 are made of magnetically permeable material such as iron and are in fiux conducting relationship.

The core 17 is formed with a diametric slot 18 (Figure 2) which in the illustrated embodiment extends axially downwardly from a point spaced from the upper end of the core to the lower end thereof. The core also has an axial bore 19 which, in the illustrated embodiment, is

'formed by a pair of complementary axially extending rectangular grooves 19 and 20 in the opposite faces of the slot 18. The opposite faces of the slot 18 are correspondingly recessed at the lower end of the core 17 to receive a sleeve bearing 21, and said faces are also correspondingly recessed intermediate the length of the core to receive a sleeve bearing 22, said bearings being made of non-magnetic material such as stainless steel and being coaxial with the core 17. A stem 23 is axially slidably positioned in the bearing sleeves 21 and 22, the lower end of said stem projecting into the valve body 7 and being operatively connected to the valve member 10. The stem 23 and the bearing sleeves 21 and 22 may be square in cross-section as shown most clearly in Figure 2.

The electromagnetic device or operator 5 further comprises a cylindrical sleeve 25 spaced from and coaxially surrounding the core 17, the bosses 15 and 1.6 being sealingly received in the opposite ends of said sleeve as shown. The sleeve 25 has an intermediate section 26 which is made of magnetically permeable material such as iron, and has a pair of opposite end sections 27 and 28 which are made of non-magnetic material, such as stainless steel or other suitable material. At the upper end of the intermediate, magnetically permeable section 26 an annular transverse wall or flange 29 of magnetically permeable material surrounds the sleeve 25 and is connected to the section 26 of said sleeve in flux conducting relationship.

An annular magnetic field producing means which in the illustrated form of the invention takes the form of a fixed exciting or primary coil 30 coaxially surrounding the sections 26 and 28 of the sleeve 25 between the wall 29 and the end wall 14. The coil 30 has a pair of terminals 31 which are adapted to be connected to a source of alternating current (not shown). A second annular magnetic field producing means in the form of a fixed coil 32 coaxially surrounds the section 27 of the sleeve 25 between the wall 29 and the end wall 14. The coil 32 has a substantially smaller number of turns than the coil 30 and has a pair of terminals 33 and 34.

twill be noted that the core 17 and end walls 13 and 14 form a spool-like structure, and over this spool-like structure a removable elongated cup-shaped casing 12 of magnetic material is coaxially fitted as shown. A screw 41 threaded axially into the core 17 may be used to removably secure the casing 12 in operative position. The casing 12 is in flux conducting relationship with each of the walls 13, 29 and 14 and is provided with suitable openings for the passage therethrough of leads from the terminals 33, 34 and 31.

A third magnetic field producing means in the form of a sleeve 36 coaxially surrounds the core 17 within the sleeve 25. The sleeve 36 is freely movable along the core 17 within the annular space or air gap between the section 26 of the sleeve 25 and said core. At least a portion of the sleeve 36 is positioned radially inwardly of the section 26 as shown in Figure 1. The sleeve 36 has an integral diametrically extending portion 37 positioned in the slot 18 as shown in Figure 2. The sleeve 36 is made of non-magnetic material of high conductivity, such as copper or aluminum, said sleeve constituting a single turn, closed loop coil. The diametric portion 37 of the sleeve 36 is preferably made of non-magnetic material of higher resistance, such as stainless steel, and

said portion is fixed to the stem 23 so that axial movement of the sleeve 36 is accompanied by like movement of the stern and valve member 10.

The terminals 33 and 34 of coil 32 are electrically connected to the contacts of a circuit controlling device 35 which may take the form of a thermostatic or other condition responsive switch. During normal operation of the improved control device the exciting coil 30 is energized, since the device has a low stand-by power loss. Assuming that the contacts 35 are open, the magnetic field established by the coil 30 causes magnetic flux to flow through the closed flux path provided by the casing 12, end walls 13 and 14, and core 17. For example, the flux flow in one direction is up the core 17, outwardly through the end wall 13, downwardly through the casing 12, and inwardly to the core through the end wall 14. When the circuit of coil 32 is open, there is no substantial force exerted on the sleeve 36, and the valve member 10 is biased to the closed position by fluid pressure thereagainst and gravity (although as will be apparent to those skilled in the art that a suitable biasing spring could also be provided for this purpose).

When the contacts of the switch 35 are closed, a current is induced in the coil 32 and a magnetic field is thereby established which field opposes the magnetic field on the exciting coil 30 and thereby prevents the flow of substantial amounts of flux through the portion of the core 17 radially inwardly of the coil 32 and sleeve section 27. Flux established by the coil 30 is thereby diverted and caused to flow across the annular air gap between the core and the sleeve section 26. The fiux thus diverted flows from the core radially across the air gap to the sleeve section 26, thence through the wall 29, casing 12, and end wall 14 back to the core 17.

The magnetic field of the primary coil 30 also induces a current in the sleeve 36, and this induced current establishes a magnetic field around said sleeve. When the magnetic flux of the field of the exciting coil 30 is diverted radially across the air gap between the core 17 and the sleeve section 26 as aforementioned, the magnetic flux of the field of the sleeve 36 reinforces said radial flux at the lower end of the sleeve and neutralizes or opposes said radial flux at the upper end of the sleeve. A condition of unbalance is thus produced which lifts the sleeve 36. To put it another way, the fields of the sleeve and of the exciting coil 30 are mutually repellant when the flux of the exciting coil is shunted radially across the air gap, and since the exciting coil is fixed, the sleeve 36 is lifted by repulsion. Lifting of the sleeve 36 also lifts the stem 23 and valve 10 to open the latter.

The repulsion effect exerts its maximum lifting force at the beginning of its stroke, and this maximum force is utilized to crack the valve against the force of the fluid pressure tending to hold said valve in closed position. As pointed out hereinbefore, the force necessary to continue valve movement after the initial cracking is substantially less than the initial force requirement. Thus, while the force exerted by the repulsion etfect diminishes from its initial maximum, the force necessary to continue valve movement after cracking also diminishes as the valve leaves its seat. The lifting force on the sleeve 36 and the opposing force of gravity action on said sleeve, stem 23 and valve 10 arrive at a condition of equilibrium when said parts reach a raised position such as that indicated by the dot-and-dash lines in Figure l. The sleeve, stem and valve come to rest at this raised position without the necessity for any stop members limiting the travel of the sleeve 36. Quiet operation thereby results, since there are no hammer blows on valve actuation, such as are common in magnetic attraction type actuators.

The sleeve 36, and hence, the valve member 10, is held in raised position as long as the contacts of the switch 35 are held closed. When the invention is applied 0 a valve 6 for controlling the flow of fueltothe main burner of a heating unit, the contacts of the thermostatic switch 35 are calls for heat.

section 26. the air gap, radial flux to react against, and the lifting action produced by reaction of said sleeve field with the radial flux also ceases. As a result, the sleeve 36, stem 23, and valve member drop by gravity, and with the aid of fluid pressure in the valve body 7, to seat the valve member 10 on the seat 8. The resilient valve facing 11 insures quiet seating of the valve.

The device 110 volts A. C. is impressed on the terminals 31, the voltage at the terminals 33 and 34 may be 24 volts A. C.

the coil 32 is made E. t. P which opposes primary flux flow through the mentioned portion of the core, and this back E M F nate flux path provided by the air gap. This leaves a relatively small amount of undiverted primary flux for excitation of the coil 32.

of the appended claims.

What I claim as the invention is: l. In an electromagnetic control device:

permeable producing through; a magnetically permeable frame with respect to which said annular field producing means is fixed, said frame being connected to spaced portions of said an outer flux path extending about the exterior of said annular field producing means, said core and frame forming a closed flux path; a sleeve connected to said frame providing an outer flux path extending about the exterior of said annular field producing means, said core and frame forming a closed flux path; a magnetically permeable sleeve connected to said frame in flux conducting relation thereto and coaxially surrounding said core in spaced relationship to provide an annular air gap between said core and sleeve; electromagnetic fiux diverting means for selectively shunting flux established by said field producing means radially across said annular air gap; movable annular field producing means surrounding said disposed in a predetermined position in said air gap, the fields of said fixed and movable field producing means he- 3. In an electromagnetic control device: a first annular magnetic field producing means; an elongated magnetiextending coaxially within said field an inner flux path thereeable frame with respect to conducting relation thereto and providing an outer flux path extending about the exterior of said annular field producing means, said core and frame forming a closed flux path; a magnetically pe meable sleeve connected to said frame means in flux conducting relation thereto and magnetic flux across said air gap. 4. In an electromagnetic exciting coil; an elongated frame being connected to both ends of said core in flux conducting relation thereto and providing an outer flux path extending about the exterior of said exciting coil, said core and frame forming a closed flux path; a magnetically permeable sleeve connected to said frame in flux conducting relation thereto and surrounding an intermediate portion of said core in spaced relationship to provide an annular air gap between said core and sleeve; an annular flux diverting coil fixed with respect to said frame and coaxially surrounding said core at one end of said sleeve and inductively coupled with said exciting coil, said flux diverting coil being operable when its circuit is closed to shunt the magnetic flux established by said exciting coil radially across said annular air gap; and movable field producing means positioned to travel freely in said air gap and be repulsed by the passage of magnetic flux across said air gap.

5. In an electromagnetic control device: an annular exciting coil; an elongated magnetically permeable core extending coaxially within said coil and providing an inner flux path therethrough; a magnetically permeable frame with respect to which said exciting coil is fixed, said frame being connected to both ends of said core in flux conducting relation thereto and providing an outer flux path extending about the exterior of said exciting coil, said core and frame forming a closed flux path; a magnetically permeable sleeve connected to said frame in flux conducting relation thereto and surrounding an intermediate portion of said core in spaced relationship to provide an annular air gap between said core and sleeve; an annular flux diverting coil fixed with respect to said frame and coaxially surrounding said core at one end of said sleeve and inductively coupled with said exciting coil, said second coil being operable when its circuit is closed to shunt the magnetic flux established by said exciting coil radially across said annular air gap; a non-magnetic and conducting member positioned to travel freely in said air gap and be repulsed by the passage of magnetic flux across said air gap; an element to be actuated; and means operating axially within said core and connecting said non-magnetic and conducting member to said element for actuation of the latter by movement of said nonmagnetic and conducting member in said air gap.

6. In an electromagnetic control device: an annular exciting coil; an elongated magnetically permeable core extending coaxially within said coil and providing an inner flux path therethrough; a magnetically permeable frame with respect to which said exciting coil is fixed, said frame being connected to both ends of said core in flux conducting relation thereto and providing an outer flux path extending about the exterior of said exciting coil, said core and frame forming a closed flux path; a magnetically permeable sleeve connected to said frame in flux conducting relation thereto and surrounding an intermediate portion of said core in spaced relationship to provide an annular air gap between said core and sleeve; an annular flux diverting coil fixed with respect to said frame and coaxially surrounding said core at one end of said sleeve and inductively coupled with said exciting coil, said second coil being operable when its circuit is closed to shunt the magnetic flux established by said exciting coil radially across said air gap; and movable annular field producing means coaxially surrounding said core and positioned to travel freely in said air gap and be repulsed by the passage of magnetic flux across said air gap.

7. In an electromagnetic control device: a magnetically permeable tubular casing having a pair of magnetically permeable opposite end walls; an elongated magnetically permeable core extending coaxially within said casing and connected to said end Walls in flux conducting relation thereto; an annular exciting coil within said casing coaxial with said core; a magnetically permeable sleeve positioned within said exciting coil and coaxially surrounding an intermediate portion of said core in spaced relationship to provide an annular air gap between said core and sleeve, said sleeve being connected to said casing in flux conducting relation thereto; an annular fiux diverting coil within said casing coaxially surrounding said core and offset axially from said exciting coil and said sleeve, said flux diverting coil being inductively coupled with said exciting coil and being operable when its circuit is closed to shunt the magnetic flux established by said exciting coil radially across said annular air gap; and an annular non-magnetic and conducting member coaxially surrounding said core and positioned to travel freely in said air gap and be repulsed by the passage of magnetic flux across said air gap.

8. In an electromagnetic control device: a magnetically permeable tubular casing having a pair of magnetically permeable opposite end walls; an elongated magnetically permeable core extending coaxially Within said casing and connected to said end Walls in flux conducting relation thereto; a sleeve extending within said casing between said end walls and coaxially surrounding said core in spaced relationship, said sleeve having a magnetically permeable intermediate portion providing an annular air gap between said permeable portion and said core, said sleeve also having a pair of opposite non-magnetic end portions; an annular exciting coil within said casing coaxially surrounding the magnetically permeable intermediate portion and one of the non-magnetic end portions of said sleeve; means etfecting a magnetic flux conducting connection between the magnetically permeable intermediate portion of said sleeve and said casing; an annular flux diverting coil within said casing coaxially surrounding the other non-magnetic end portion of said sleeve, said flux diverting coil being inductively coupled with said exciting coil and being operable when its circuit is closed to shunt the magnetic flux established by said exciting coil radially across said annular air gap; and a non-magnetic and conducting member positioned to travel freely in said air gap and be repulsed by the passage of magnetic flux across said air gap.

9. In an electromagnetic control device: a magnetically permeable tubular casing having a pair of magnetically permeable opposite end walls; an elongated magnetically permeable core extending coaxially within said casing and connected to said end Walls in flux conducting relation thereto; a sleeve extending within said casing between said end walls and coaxially surrounding said core in spaced relationship, said sleeve having a magnetically permeable intermediate portion providing an annular air gap between said permeable portion and said core, said sleeve also having a pair of opposite non-magnetic end portions; a transverse annular wall of magnetically permeable material connecting ;one end of said permeable sleeve portion to said casing in fiux conducting relationship therewith; an annular exciting coil within said casing on one side of said transverse wall coaxially surrounding the magnetically permeable intermediate portion and one of the non-magnetic end portions of said sleeve; an annular flux diverting coil within said casing on the other side of said transverse wall coaxially surrounding the other non-magnetic end portion of said sleeve, said flux diverting coil being inductively coupled with said exciting coil and being operable when its circuit is closed to shunt the magnetic flux established by said exciting coil radially across said annular air gap; and an annular non-magnetic and conducting member coaxially surrounding said core Within said sleeve and positioned to travel freely in said air gap and be repulsed by the passage of magnetic flux across said air gap.

10. In an electromagnetic control device: an elongated core having a longitudinally extending transverse slot thereacross; an actuating member having a portion movably positioned in said core slot; an element to be actuated by movement of said actuating member; and a stem axially slidably mounted within said core and having a portion positioned in said core slot and connected to said actuating member, said stem also having a portion prosaid end walls, said sleeve having a magnetically permejecting from one end of said core and connected to said able intermediate portion providing an annular air gap element for actuation of the latter upon movement of between said permeable portion and said core; an exsaid actuating member. citing coil surrounding said sleeve; a flux diverting coil 11. In an electromagnetic control device: an elongated surrounding said sleeve and offset axially from said excyclindrical core having an axially extending diametric citing coil; a magnetically permeable tubular casing coslot thereacross; a cylindrical actuating sleeve coaxially axially surrounding and extending between said end walls surrounding said core and movable therealong, said sleeve to enclose said coils, said casing having a flux conducting having a diametrically extending connecting portion movconnection with said end walls and being removable from ably positioned in said core slot; an element to be actusaid end walls and coils by axial movement; means affordated by movement of said actuating member, and a stem ing a. flux conducting connection between the permeable coaxiallv slidably mounted within said core and having portion of said sleeve and said casing; and a non-maga portion pos tioned in said core slot and connected to netic and conducting member positioned to travel freely tne diametric connecting portion or" said actuating sleeve, in said air gap. said stem also having a portion projecting from one end of said core and connected to said element for actuation References Cited in the file of this patent grief/l: latter upon axial movement of said actuating UNITED STATES PATENTS 12. In an electromagnetic control device: an elongated 1,351,027 Davis et al Aug. 31, 1920 magnetically permeable core; a magnetically permeable 1,979,127 Warrick Oct. 30, 1934 end Wall fixed to each end of said core in flux conducting 1,980,736 Trofirnov Nov. 13, 1934 relationship therewith; a sleeve coaxially surrounding 2,637,344 Matthews May 5, 1953

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