Abstract:
An adjustable solenoid having an enclosure containing a winding through which a current is passed. The winding defines an area and a plunger is positioned at one end of the area with a mechanical biasing mechanism for providing a biasing force to the plunger, the mechanical biasing mechanism is secured to the plunger at one end and a support at the other end. A stator having a first threaded portion engaged within a threaded opening of the enclosure causes the stator to travel between a first position and a second position as a rotational force is applied to the stator. The first position is closer to the plunger than the second position, and the stator is in a facially spaced relationship with respect to the plunger and the stator has a second threaded portion for engaging a threaded portion of the support, the second threaded portion of the stator causes the support to travel between a first position and a second position, the second position of the support provides the mechanical biasing mechanism with a greater biasing force than the first position.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to an adjustable magnetic device. 
     BACKGROUND 
     A magnetic tripping device such as a solenoid generally comprises a coil or winding of wire through which a current is passed. The solenoid is configured to manipulate an actuator when the electromagnetic force generated by the coil exceeds a predetermined value of the solenoid. 
     The actuator is generally biased by a mechanical force in an opposite direction of the force generated by the electromagnetic field of the coil. This force is typically provided by a spring or other mechanical means wherein a plunger of the actuator is biased with respect to a stator positioned opposite to the actuator. 
     In addition, an air gap is positioned in between the actuator and a stator. The air gap is also located within the coil and provides an insulating barrier to the force generated by the electromagnetic field of the coil. 
     Accordingly, the tripping or predetermined tolerances of a solenoid are dependent upon the mechanical biasing force and the size and positioning of the air gap. 
     Moreover, the required range or predetermined tolerances of a magnetic tripping device vary in accordance with user&#39;s requirements such as the circuit loading. 
     Most solenoids are either fixed (nonadjustable) or have a single means of adjustment for either the air gap or biasing force. 
     In an attempt to accommodate these varying tolerances, an adjustable trip solenoid has been developed wherein the air gap between the stator and the actuator can be varied. However, the varying of this air gap also causes the spring biasing force to vary. Moreover, these changes are opposite with respect to each other. For example, increasing the air gap will also decrease the biasing force of a spring. 
     Accordingly, there is a need for an adjustable solenoid wherein the air gap and mechanical biasing force can be varied so that as the air gap is decreased the mechanical biasing force is also decreased, and vice versa. 
     SUMMARY OF THE INVENTION 
     In an exemplary embodiment of the invention, an adjustable solenoid provides an adjustable air gap where the mechanical biasing force of the solenoid is either decreased or increased as the air gap is increased or decreased. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a front cross-sectional view of a solenoid constructed in accordance with the instant application; 
     FIG. 2 is a front cross-sectional view illustrating movement of a solenoid constructed in accordance with the instant application; 
     FIG. 3 is a view along lines  3 — 3  of FIG. 1; 
     FIG. 4 is a front perspective view of a portion of an alternative embodiment; 
     FIG. 5 is a front perspective view of the FIG. 4 embodiment illustrating movement thereof; 
     FIG. 6 is a front perspective view of the FIG. 4 embodiment illustrating movement thereof; and 
     FIG. 7 is a front perspective view of circuit breaker with an adjustable trip solenoid. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to FIGS. 1 and 2, an adjustable trip solenoid  10  is illustrated. In an exemplary embodiment, solenoid  10  is coupled to a circuit interruption mechanism  70  of a circuit breaker  72  (FIG. 7) wherein the movement or actuation of solenoid  10  causes a tripping mechanism  74  to trip circuit breaker  72 . 
     Solenoid  10  has a support structure  12  into which a coil  14  is received. Coil  14  consists of a copper wire through which a current is passed. In accordance with the direction of the current being passed through coil  14 , a magnetic field is generated by solenoid  10 . 
     A plunger  16  for movement within solenoid  10  has an actuating member  18 . Actuating member  18  is configured to pass through an opening  20  in support structure  12  of solenoid  10 . In addition, actuating member  18  is configured to have a planar member  19 , which in conjunction with actuating member  18  provides a receiving area for a portion of an actuating arm  21 . The movement of plunger and accordingly actuating member  18  causes actuating arm  21  to move from a first position to a second position (illustrated by the dashed lines in FIG.  1 ). See also FIG.  2 . 
     It is intended that actuating arm  21  is to be coupled to a mechanism  74  (FIG. 6) that in accordance with the movement of actuating arm  21  from the first position to a second position, will cause an intended result of the mechanism. For example, the movement of the mechanism will cause a circuit breaker to trip. Other uses may be the activation of warning lights, indication lights, status indicators and audible alarms, etc. 
     In addition, actuating arm  21  is provided with a biasing force in the direction of arrow  23  that must be overcome by the movement of plunger  18 . In addition, the biasing force in the direction of arrow  23  also provides stability to actuating arm  21 . Moreover, the biasing force causes actuating arm  21  to return to the position illustrated in FIG. 1, once plunger  16  returns to its initial position. A spring  25  or other bias producing means causes the biasing force to be placed upon arm  21 . 
     As an alternative, and as illustrated by the dashed lines in FIG. 1, actuating arm  21  is positioned to rest upon plunger  18  and the biasing force of spring  25  is in a direction opposite to arrow  23 . In addition, and as yet another alternative, actuating arm  21  may be replaced by a pair of actuating arms or planar member in which a portion is received and engaged by planar members  19  of plunger  18 . 
     The movement of plunger  16  is caused by electromagnetic forces, which are generated by a current running through coil  14 . 
     One end of a pair of springs  22  are secured to plunger  16  and the other end of springs  22  are secured to a pair of spring position stands  24 . Springs  22  are positioned to provide a biasing force in the direction of arrow  26 . Accordingly, and in order to position plunger  16  as illustrated by the dashed lines in FIG. 1, the electromagnetic force generated by solenoid  10  must overcome the biasing force of springs  22 . 
     A stator  28  is positioned opposite to plunger  16  and an air gap  30  is defined between plunger  16  and stator  28 . In addition, air gap  30  is positioned within coil  14 . 
     Stator  28  is configured to have a first threaded portion  32  and a second threaded portion  34 . An engagement surface  36  of spring position stands  24  also has a threaded portion  38 . Threaded portion  38  is configured to have the same configuration (i.e. angle, size and slope) of first threaded portion  32 . 
     Second threaded portion  34  of stator  28  is received and engaged in an opening  40  of support structure  12 . The inner surfaces of opening  40  are configured to have a threaded engagement surface  42  that is sized and configured to engage second threaded portion  34  of stator  28 . 
     An end portion  44  of stator  28  has an engagement opening  46 . (FIG. 2) Engagement opening  46  is configured to receive and engage a tool such as a screwdriver, Allen wrench or other item for applying a rotational force to stator  28 . 
     The pitch or angle of engagement of first pair of threads  32  and  38  is substantially opposite to second pair of threads  34  and  42 . In addition, the size of threads  34  and  42  is substantially smaller than threads  32  and  38 . In an exemplary embodiment, the size of threads  32  is 10 threads per inch, and the size of threads  34  is 32 threads per inch. Accordingly, there is approximately a 3 to 1 thread ratio between threads  32  and  34 . Of course, it is contemplated that the dimensions; size and configuration of threads  32  and  34  may be larger or smaller than the dimensions mentioned above. Accordingly, and as a rotational force is applied to engagement opening  46  in a first direction, stator  28  will move in the direction of arrow  48 . This movement of stator  28  will cause the size of air gap  30  to decrease. However, since the angle of engagement of first pair of threads  32  is opposite to that of second pair of threads  34 , the movement of stator  28  in the direction of arrow  48 , caused by the rotation of stator  28  in a first direction, will also cause spring position stands  24  to move in an opposite direction or in the direction of arrow  50 . Moreover, and since the size of threads  32  is substantially larger than the size of threads  34 , this movement is at a much greater rate with respect to each revolution of stator  28 . 
     Accordingly, and as spring position stands  24  move in the direction of arrow  50 , biasing force of springs  22  is decreased. A pair of shoulder portions  52  are located on the inner surface of support structure  12 . Shoulder portions  52  provide an area into which spring position stands  24  can move as they move in the direction of arrows  50 . 
     Accordingly, and as a rotational force is applied to stator  28  in a first direction, the size of air gap  30  is reduced while the biasing force of springs  22  is also reduced. 
     Conversely, and as a rotational force is applied to stator  28  in a second direction, the size of air gap  30  will increase, while the biasing force of springs  22  is also increased. 
     Thus, for a low X-setting on the solenoid, it is desirable to have a high-efficiency solenoid that can generate a high output force per Ampere-turn for any given construction. To accomplish this, it is desirable to have a small air gap with a low reverse bias force. 
     On the other hand, and for a high X-setting on the same solenoid, it is desirable to lower the efficiency of the solenoid and thereby lower the output force per ampere-turn for the same given construction. To accomplish this, it is desirable to have a large air gap with a large reverse bias force. 
     Accordingly, the solenoid of the instant application allows such adjustments to be made in a quick and convenient manner. Moreover, the same solenoid can be used for such applications. 
     In addition, and as contemplated in accordance with the instant application, the size and configuration of threaded portions  32  and  34  are configured to obtain a desired result. For example, each revolution of stator  28 , or portion thereof, will cause stator  28  to move in a first direction of a known magnitude, while spring position stands  24  move in an opposite direction of a known magnitude. Therefore, and as a rotational force is applied to stator  28 , the movement of stator  28  and spring position stands  24  will adjust the trip setting of solenoid  10  to a known value. 
     Referring now to FIG. 3, and as an alternative, surface  44  of stator  28  is marked with an indication arrow  54  while the surrounding surface of support structure  12  is also marked with a plurality of markings  56  which will indicate the trip setting of solenoid  10  when arrow  54  is pointing thereto. Of course, alternative marking arrangements are contemplated, such as, demarcations on the inner surface of opening  40  and stator  28  which will indicate the trip setting of solenoid  10  as stator  28  moves within opening  40 . For example, such indications may be a color oriented scheme that provides a user with a quick and convenient means of determining the solenoid&#39;s trip setting. 
     Referring now to FIG. 4, an alternative embodiment of the instant application is illustrated. Here, component parts performing similar or analogous functions are numbered in multiples of 100. 
     Here, a solenoid  110  is configured to have a flux shifter  160 . Flux shifter  160  is an elongated sleeve portion constructed out of a ferromagnetic material that is configured to be placed over plunger  116  and is capable of movement in the direction indicated by arrows  162 . 
     Flux shifter  160  is secured to stator  128  by a pair of connection rods  164 . Accordingly, and as a rotational force is applied to stator  128 , through a tool inserted into engagement opening  146 , the threaded portion  134  of stator  128  will travel through the threaded portion  142  of opening  140  which, depending on the direction of the rotational force, will cause stator  128  and accordingly flux shifter  160  to move in either direction of arrows  162 . 
     Accordingly, and as stator  128  is moved in a direction away from plunger  116 , air gap  130  increases in size and flux shifter  160  is repositioned to cover a portion or all of air gap  130 . Since flux shifter  160  is constructed out of a ferromagnetic material, once it is positioned in close proximity to air gap  130 , flux shifter  160  creates a path of lesser reluctance for the magnetic flux of solenoid  110  to travel. 
     For example, and referring now to FIG. 5, as flux shifter  160  covers air gap  130 , the flux of solenoid  110  is partially illustrated by the dashed lines in FIG.  4 . This positioning of flux shifter  160  will allow solenoid  110  to be able to accept a higher current value through coil  114  before plunger  116  is actuated. Moreover, the size of air gap  130  is also increased in the position illustrated by FIG. 5 this also increases in the amount of flux required to actuate plunger  116 . 
     Conversely, and as flux shifter  160  and stator  128  are moved back into the position illustrated by FIG. 4, the flux of solenoid  110  is illustrated partially by the dashed lines in FIG.  6 . 
     Comparing solenoid  110  of FIGS. 5 and 6 shows a high-efficiency electromagnetic system in FIG. 6 and a low efficiency electromagnetic system in FIG.  5 . Since higher magnetic forces are generated from a solenoid having high efficiency, the magnetic forces generated by solenoid  110  of FIG. 6 will be greater than those of FIG. 5 at a given solenoid current value. Alternatively, for a given trip force, the solenoid  110  of FIG. 6 will have a trip point (activation threshold) at a lower solenoid current than will the solenoid  110  of FIG.  5 . 
     Therefore, solenoid  110  provides the user with a single means of adjustment for introducing flux shifter  160  while concurrently increasing air gap  130  and vice versa. This configuration provides a wide range of trip settings for solenoid  110 . 
     In an exemplary embodiment, solenoid  110  has a low gradient compression spring or springs  122  that has a de minimus change in bias force as stator  128  moves. 
     While the invention has been described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims.