Electromagnetic actuators

Jan. 14, 1958

2,820,183

E. B. ANDER

ELECTROMAGNETIC ACTUATORS

Filed June 1, 1953

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ATTORNEY

United States Patent Office

2,820,183

Patented Jan. 14, 1958

2,820,183

ELECTROMAGNETIC ACTUATORS

Eric B. Ander, Minneapolis, Minn., assignor to Minneapolis-Honeywell Regulator Company, Minneapolis, Minn., a corporation of Delaware

Application June 1,1953, Serial No. 358,933

Claims. (Cl. 317—172)

This invention pertains to electromagnetic actuators and more particularly to improvements in the positioning and in the adjustment of the movable armature assembly of electromagnetic actuators.

The principles of this invention are described and explained in connection with a generally U-shaped magnetic frame member positioned with the bight portion of the frame abutting a base member and with the two arm portions extending vertically away from the base with their ends forming two pole faces which are substantially coplanar. A bar-type permanent magnet is positioned so that one of its ends abuts the bight portion of the frame and is so proportioned that its other end is substantially coplanar with the pole faces of the frame. A coil is positioned around one of the arms of the frame and is adapted to be energized by a low energy source of potential such as a thermocouple or thermopile. A suitably shaped plate type armature is positioned so as to overlie the pole faces of the frame and is adapted to be pivotally supported along an axis near its center. A tail spring resiliently biases the armature toward the rear pole face and flux flows flowing from the permanent magnet also tends to maintain the armature in this position. Energization of the coil will result in an increased force of attraction being developed between the armature and the front pole face and a reduced force of attraction being developed between the armature and the rear pole face. These forces act on the armature causing it to rotate about its pivotal axis toward the front pole face, against the force of the biasing spring. Due to the fact that the turning forces acting on the armature are a function of the distance between the armature and both of the pole faces on the frame, it follows that the positioning of the pivotal axis of the plane of the armature with respect to the plane of the front and rear pole faces is a critical one. This is better understood if it be assumed that a certain amount of armature travel or rotation is required to operate a control device such as a diaphragm controller for a diaphragm valve or one or more contacts in an electrical circuit interrupter. Thus, if the pivotal axis of the plane of the armature is too close to the plane of the pole faces, the forces on the armature will be sufficient to cause armature rotation but the close spacing will not allow enough armature rotation to actuate the control device. Also, if the pivotal axis of the plane of the armature is too far from the plane of the pole faces, the forces acting on the armature when the coil is energized will be insufficient to cause rotation of the armature. It follows, therefore, that there is a critical dimension, with narrow limits, at which the pivotal axis of the plane of the armature should be positioned with respect to the plane of the frame pole faces so that the forces acting on the armature are sufficient to cause rotation and so that enough spacing is provided to prevent sufficient armature travel to actuate the control device.

It has been found in the actual quantity production of an actuator as above described that due to a “pile up” of tolerances on the actuator base, the magnetic frame with its various component portions, and the armature support, it is necessary to provide a means of adjusting the position of the armature with respect to the plane of the pole faces.

A broad object of my invention therefore is to provide an improved type of support for the armature assembly of an actuator of the general type described in the preceding paragraph wherein the armature is pivotally mounted on supports the elevation of which are adjustable so that the pivotal axis of the plane of the armature can be positioned within the critical distance from the plane of the pole faces.

Another object of the invention is to provide in an armature support a means of adjusting the position of the armature so that the plane of the armature while horizontal is parallel to the plane of the pole faces.

A further object of the invention is to provide an improved armature support wherein the plane of the armature may be adjusted with respect to the plane of the stationary portion of the actuator and wherein any transverse movement of the armature with respect to the frame is precluded.

Still another object of the invention is to provide a compact, powerful, and efficient polarized electromagnetic actuator wherein means are provided for quickly and accurately assembling and calibrating said actuator.

These and other objects of this invention will become apparent from the reading of the attached description together with the claims and the drawings in which:

Figure 1 is a side elevational view, partly in section, of a polarized electromagnetic actuator together with diaphragm controller and a diaphragm valve;

Figure 2 is a top or plan view of the device shown in Figure 1 with the cover member removed;

Figure 3 is a right end elevational view of the device shown in Figure 1 with the cover member in section;

Figure 4 is an enlarged view of one of the supports for the armature assembly of the actuator shown on the preceding drawings; and

Figure 5 is a plan view of a portion of the actuator with the armature assembly removed.

The body for the diaphragm valve is made up of two castings, an upper casting 11 which also serves as a base for the electromagnetic actuator and the diaphragm controller and a lower casting 12 having a threaded aperture 13 in one end thereof which serves as an inlet opening and a threaded aperture 14, in the other end which serves as an cutlet for the valve. Integrally contained within lower casting 12 is an annular shoulder portion 15 the hollow interior 16 of which is in communication with opening 14. A flexible diaphragm member 17 having the same general plan configuration as the mating surfaces of the upper and lower valve castings 11 and 12 is positioned between these valve castings together with a gasket member 18, the assembly being held together by a plurality of machine screws 19. The center portion of the diaphragm member 17 is adapted to seat itself across the top portion of opening 16 and a metallic disc 20 of appreciable weight is secured to the top of diaphragm 17 by a machine screw 21 and a nut 22. The purpose of disc 20 is to aid in maintaining a tight fit between diaphragm 17 and the opening 16 when the valve is in the closed position.

A generally U-shaped magnetic frame member 30 having a bight portion 31 is positioned so that bight portion 31 abuts a portion of the top surface of upper valve casting 11 which as aforementioned serves as the actuator base. Frame 30 has two vertically extending arm portions 32 and 33, the upper ends of which respectively form a front and rear pole face 34 and 35. A coil' 36 wound on a bobbin 37 is positioned on the bight portion 31 of frame member 30 and surrounds arm 32 of:

2,820,183 , 4

-boss-portion 65 extends through apertures 55 in the ex tended portions 54 of reed -52. The design of the arma ture assembly is such that the center of gravity is substantially near the line joining the points where portions 54 of reed 52 project forwardly from the bracket 51, It follows, therefore, that the weight of the armature assembly will be supported by post members 61 and that any rotation of the armature assembly will occur along a pivotal axis which coincides with a line joining the points where portions 54 of reed 52 extend forwardly from oracket 51. The pivoting thus takes place on flat surface 64 of post members 61 and the boss portions 65 extending through apertures 55 in reed member 52 serve to position the armature assembly with respect to the posts 61 and prevent any transverse or longitudinal movement of the armature assembly with respect to the posts.

As seen in Figure 1, armature bracket member 51 is a substantially flat member but has at its rear extremity a bent down portion 70 which in turn has a bent out portion 71. Threaded into portion 71 of bracket 51 is a machine screw 72 having an intermediate shoulder 73, the upper surface of which is protected by a stainless steel washer 74. Threaded onto the top of machine screw 72 is a nut member 75 which has a lower surface parallel to washer 74. Between the lower surface of nut 75 and the top of washer 74 is positioned the end of the control arm 80 of a diaphragm controller 43 of the type shown in a pending application of William L. Huntington subject invention. Since the details of the diaphragm controller 43 are not essential to the subject invention they will not be described herein. It will be sufficient to state that upward movement of the end of control arm SO on the diaphragm controller 43 will result in the diaphragm assembly in the main valve consisting of diaphragm 17 and weight 20 to be caused to move upwardly so as to allow the passage of fluid through aperture 13 into the,main valve body and thence through aperture 16 cutlet It. Also, when the end of control arm 80 of the diaphragm controller 43 is moved downward, the diaphragm assembly will be caused to seat down tightly against annular portion 15 of the valve thus closing the valve.

A lever member 81 which is pivotally connected to an end wall of diaphragm controller 43 by means of a machine screw 82 has secured to an intermediate part thereof one end of a resilient spring 83, the other end of which attached to a stainless steel post 84 which is staked

Spring 83 thus biases the armature assembly to the position shown in Figure 1. At the free end of lever member 81 is a bent over portion 85 having an aperture therein^ through which extends the shank of a machine screw aperture in a boss portion 87 integral with base 11™ A coil spring 88 circumscribes machine screw 86 and is disposed between the top of boss portion 87 and the under ^sjdeof flange portion 85 of lever 81 and exerts an out81 against the under side of the head on screw 86. It will be appreciated that rotation of screw 86 will result in lever member 81 being disposed either clockwise or counterclockwise around its pivot point established at the amount of tension that biasing spring 83 exerts on the tail piece of the armature assembly.

Also attached to the bent down portion 70 of bracket member 51 is a generally L-shaped spring member 90 84 and a rivet 91 and which has offset portions 92 extending outwardly from portion 70. The outwardly extending portions 92 have detents 93 therein which cooperate with knurling on the peripheries of nut 75 and shoulder one of its ends the., frame. Arm .32 of the frame constitutes Ihe core -of the coil and is a member having on its lower end a portion of reduced diameter (not shown) which passes through an aperture in frame member :30 and threads into a threaded aperture m base member 11. In this manner framamember 30 is securely held in position with respect to base member 11.

It is to be noted that the front pole face 34 and the rear pole face 35 are substantially coplanar. A ’bar-type: permanent magnet 38 is positioned with one of its ends abutting the bight portion 31 of frame member 30 and is proportioned so that its other end is substantially coplanar with front and rear pole faces 34 and 35 respectively.

Permanent magnet 38 is positioned and held in place with respect to frame member 30 by a generally U-shaped non-magnetic clamp 40, the bight portion 41 of which is secured to arm 33 of frame 30 by a machine screw 42 the threaded end of which extends through an aperture in arm 33 and threads into the sidewall of diaphragm controller 43 which will be described later. It will be appreciated that screw 42 thus serves to hold clamp member 40 with respect to the frame 30 and also serves to hold frame 30 with respect to upper valve housing 11.

The U-shaped clamp 40 has arms 44 and 45 which are 25 adapted to embrace the sides of permanent magnet 38 and also the sides of arm portion 33 of frame member 30. A machine screw 48 extends through an aperture in arm 45 of U-shaped clamp 40 parallel to bight portion the clamp and is adapted, when turned, to develop a clamping force of arm portions 44 and 45 against the permanent magnet 38 so as to firmly hold the permanent magnet and position it with respect to the frame. _ola

An armature member 50 is adapted to overlie the front 35 so and rear pole faces 34 and 35 and is a part of an armature assembly comprising armature 50, an armature bracket 51, and a flexible reed 52, the armature assembly being staked together by a plurality of rivets 53 with „„„ _L1IC mam i the reed 52 being disposed between the bracket 51 and 40 and outlet 14. the armature 50. For the most part, bracket member 51 overlies reed member 52 but reed member 52 has a pair of extending portions 54, each of which has an aperture 55 therein. Portions 54 with apertures 55 are best shown in Figure 2. The purpose of this arrangement will be 45 described below.

In this actuator it is essential that an adjustment be provided so that the pivotal axis of the plane of the armature 50 can be adjusted with respect to the plane of the front and rear pole faces 34 and 35. I; _talIl that the plane of armature 50, while horizontal, be parallel to the plane of the front and rear pole faces 34 and 35. A vertically adjustable support system for the armature assembly is provided as follows. Integral with the base &lt;·*« « - « P«\of boss portion, &amp; wbieb „o _posi. « honed intermediate the front and rear pole faces 34 and _r- * · - ^{α lnto a tllreacIe}d and are on opposite sides of base 11. Each of the bosses 60 has a threaded aperture therein into which is threaded the lower portion of longitudinally adjustable posts 61. ' ‘ ____________ members having a threaded portion 62 at their lower extremity and having a hexagon portion 63 at a location near the top thereof but intermediate the two ends. The tops of posts 61 are flat as is best shown in Figure 5 at « bn, b._vc al their can,» a raised cr b«_{ss P}U, «S „ which has a diameter shghtly less than the apertures 55 -------- ' - · - - - - ^UUUO1 ror tne in reed member 52. The boss portions 65 have a threaded recess 66 therein, as shown in Figure 5, into which are threaded the ends of machine screw members and also portions of bracket member 51 overlie and bear on the top surface 64 of post members 61 with the reed member .52 beingdisposed between surface 64 and bracket memherSl. The armature assembly is positioned so that 75 73 of machine screw 72 so as toprevent rotation of these _T, .·„ . -n ------— — - — ----a clvcj μ_υ5ι οι which is staKea

It is also important a0 to the bent down portion 70 of bracket member 51 iri7r&gt;nrnl Η» «οι-αΙΙα! Ο— — J ., « · ..

2,820,183

Vast mentioned members due to vibration, but allow the •turning of nut 75 and screw 72 with a hand tool so as to adjust the “pull in” and “drop out” position of armature 50 with respect to the limits of travel of control arm 80 of diaphragm controller 43.

A pair of wires 100 which are the ends of coil 36 are connected to terminal members 101 by soldering or the like. Terminal members 101 are secured to the end of machine screws 102 which extend through suitable apertures in upper valve housing member 11. Threaded onto the external end of machine screws 102 are jam nuts 104 and binding post nuts 103. The terminal assemblies are insulated from member 11 by insulative tubing 105 and end piece insulators 106 and 107. Binding post nuts 103 provide a means of connecting wires from an external source of electromotive force such as a thermocouple or thermopile to coil 36.

A dish shaped cover member 110 is adapted to fit over the electromagnetic actuator and the diaphragm controller 43 resting upon a suitable shoulder provided on base member 11 and is secured thereto by a plurality of machine screws 111.

As indicated heretofore, in a polarized electromagnetic actuator of the type herein described, it is essential that the pivotal axis of the armature be within a critical distance of the plane established by the front and rear pole faces of the frame. It is also essential that the plane of the armature, while the armature is in a horizontal position, is relatively parallel with the plane of the front and rear pole faces. In the present invention, adjustable post members 61 provide the means of achieving the above described requirements. In one method of assembly of the electromagnetic actuator, the frame member 30 together with the coil and core assembly and the permanent magnet are preassembled and positioned on the base member 11. A jig is then positioned over the actuator and bears against the rear pole face 35 at two spaced points and also against the center of the front pole face 34. The three points of contact with the rear and front pole faces thus establish the plane of these pole faces and provide a reference level for the positioning of adjustable post members 61. The jig has two extended portions that project out over the flat tops 64 of post members 61. The post member 61 is then turned with respect to boss 60 until the flat surface 64 bears against the under side of the jig at which point jam nut 68 is turned down on the threaded portion 62 of post member 61 so as to positively lock post member 61 with respect to boss 60. This procedure is also followed with the post member 61 on the opposite side of the actuator and thus the pivotal surface for the armature assembly is established which (1) provides a pivotal axis that is within the critical distance from the plane of the front and rear pole faces and (2) is parallel to the plane of the front and rear pole faces. The preassembled armature assembly consisting of the armature, the armature bracket, and the flexible reed 52 is then placed in position with the boss portion 65 projecting up from surface 64 of post member 61 extending through apertures 55 in reed member 52. Screw members 67 are then screwed in place thus preventing the armature assembly from being removed from the main frame and support assembly. Biasing spring 83 is then attached between lever member 81 and stainless steel post 84 and then machine screw 72 and nut member 75 on the armature bracket portion 71 are adjusted so as to adjust the “drop-out” and “pull-in” of the actuator respectively.

It will be obvious to those skilled in the art that methods other than that above described could be used to assemble the electromagnetic actuator. For example, a dial indicator arrangement could be used to position the tops of the adjustable post members 61 with respect to the front and rear pole faces 34 and 35. I therefore desire that it be understood that the invention should not be limited by the above described method of assembly, but only by the appended claims.

It will be appreciated by those skilled in the art that the above described electromagnetic actuator, diaphragm controller and diaphragm valve together form a compact and efficient mechanism and it will be appreciated that the armature support means provide a method of quick and accurate positioning of the armature assembly with respect to the front and rear pole faces of the magnetic frame.

While I have shown and described a specific embodiment of this invention, further modifications and improvements will occur to those skilled in the art. I desire it to be understood, therefore, that this invention is not limited to the particular form shown and I intend in the appended claims to cover all modifications which do not depart from the spirit and scope of this invention.