US 2892049 A
Description (OCR text may contain errors)
June 23, 1959 s. RUBINSTEIN MAGNETIC SWITCH Filed April e, 1957 United Statesljatent O inesne assignments; to Northrop Corporation, a corporation of California Application April s, 1957, serial No. 651,354
4 claims. (c1. 20o- 151.43`
invention relates tov electrical" switching devices and` morey particularly to an electrical switch responsive to* inertial forces. Numerous and various types of inertial switches have been developed which function lto make `and break an electrical current flowing therethrough as a result of inertial forces acting on the switch. Switches of the above character are very useful in carrying out the operation for which they are intended.V However, to' the best of applicants knowledge, once the above switches have performed an initial switching operation they remain inoperative thereafter until such time a's they are manually reset. Construction of this character limits or precludes the use of the above type of inertial switches in many installations especially where a switch is re- 'quired to function repeatedly without interrupting the operation of apparatus with whi'ch it is associated and controlling.
Accordingly it is an object of the present invention to provide Van electrical switch which is responsive to predetermined inertial forces and which performs its func'- t'ion repeatedly without manual resetting thereof.
Another object is to provide an electrical switch which initially functions in response to abnormal inertial forces and which incorporates means returning movable parts thereof to their original positions at such times as the abnormal inertial forces no longer -act on the switch..
Another object is to provide an electrical switch which is responsive to inertial forces resulting from predetermined changes in either linear or angular accelerations.
Another object is to provide an electricalA switch which is responsive to inertial forces which is simple in design and operation yet rugged in construction, which is practical-ly free of malfunctioning characteristics, is economical to manufacture, and which may be easily adapted to any purpose for which it is intended.
' Although the characteristic features of theV present invention are particularly pointed out in the appended claims, the invention itself, also the manner in which it maybe carried out, will be better understood by referring to the following description taken in connection with the accompanying drawings forming a part of this application and in which:
` Figures l and 3 are longitudinal cross-sectional views of two embodiments of the electrical switch as disclosed herein.
Figure 2 is a cross sectional view of the electrical 'switches as viewed along either the section lines 2-2 of Figure l or Figure 3.
Referring to the drawings and particularly to Figures 'l and 2 in which an inertia switch 11 of the type disclosed iice which houses internal components of the switch 11. The components contained within theV housing 18v include a member 19, a permanent magnet 21, and a spherical member 22 normally arranged as best seen in Figure l.
In the present embodiment the members 19 and 21 are of cylindrical-like configuration and as mounted in the housing are in axial alignment and are spaced vertically with respect to each other as viewed in Figure l. The magnet 21 is further characterized by constituting a right-angled cylinder having. a longitudinal bore 23 while the member 19 is of inverted cup-shaped configuration as positioned in the member 14 and defines a cylindrical bore 24.
As mounted in the assembled housing 18 one end of' the` magnet 2.1v is bottomed in the bore 16 and has a forced fit relationship therewith so it will retain its relative' position therein. The member 19 may also be forced in the bore 24 although the latter member will be held in position by `the male member 12. It will be noted that the spherical member 22 is of greater diameter than the diameter of the longitudinal bore 23 and of less diameter than the bore 24. Also the diameter of the member 22 is less than the distance between the terminal end of the bore 24 and the upper end of the magnet 21.
The member 21 is fabricated from a suitable material and is permanently magnetized to provide a magnetic eld 20 as represented by broken line construction Figure l. The members 19 and 22 are fabricated of metal and the latter member is fabricated of a metal which is attracted by the magnetic field of the magnet 21. Under normal conditions the magnetic field 20 causes the member 22 to seat itself on the uppermost periphery of the passage 23 as shown by solid construction in Figure l. The position of the member 22 described above constitutes the initial or seated position of the member 22 and will be referred to as such hereafter.
The construction of the switch is further characterized in that the member 19 and magnet 21 are mounted in the housing 18 in spaced vertical relation. Also the members 12 and 14 are fabricated of electrical insulating material. Accordingly at such time as the switch is subject to abnormal inertial forces the member 22 will be displaced laterally, that is from its initial position to a position in which it is in contact with the side wall of the bore 24, as shown by dotted construction in Figure 1. This latter position of the member 22 is hereinafter referred `to as the final or unseated position of the spherical member. With the member 22 in its final position it will be apparent that an electrical current may flow between the member 19 and magnet 21.
The construction of the switch 11 is Acompleted by electrical connectors 26 and 27 which pass through end portions of members 12 and 14 and are respectively attached to the magnet 21 and member 19.
In operation the switch 11 may be utilized generally as a load sensing device. Specifically it may be utilized to sense centrifugal or centripetal forces, to sense dy'- namic balance or unbalance of rotating parts, to sense excessive sideslips or skids of an aircraft or the like, to sense maximum allowable accelerations or decelerations of -an aircraft or the like, etc.
Assuming the switch 11 is mounted on an aircraft (not shown) to sense maximum allowable accelerations thereof. Further it is assuming that the aircraft is traveling to the left with respect to Figure l. During normal operations of the aircraft the spherical member 22 is retained in its initial position by the magnetic field 20.
At such times as the airplane exceeds its allowable maximum acceleration, the moment due to the inertial force acting on the member 22 overcomes the moment provided by the magnetic field of the magnet and the force of gravity.
Accordingly the member 22 is urged from its initial position and is pivoted to the right about the edge of the passage 23. The spherical member 22 continues to move to the right, maintaining contact with the upper end of the magnet 21, until it reaches its final position at which vtime it is in contact with the `bore 24 of the cup-shaped member 19. A path for an electrical current is now provided between the connectors 26 and 27, the cu-rrent flowing via the member 19, spherical member 22, and vmagnet 21. This flow of current may be utilized to ener gize apparatus (not shown) functioning to reduce the aircrafts acceleration to an acceleration within the prescribed maximum allowable acceleration of the subject aircraft.
At such time as the airplanes acceleration is reduced to or slightly below the aforementioned limits the magnetic field of the magnet 21 overcomes the inertial moment and the spherical member 22 is returned to its initial position, the flow path for the electric circuit is broken, and the apparatus functioning to reduce the aircrafts acceleration is no longer effective. It will be obvious to one skilled in the art that Iby varying the weight and size of the spherical member 22 its sensitivity to inertial forces can be varied and therefore the switch 11 can be designed so that it will function under any predetermined condition.
The embodiment of the switch as shown in Figure 3 is quite similar to the switch 11 as shown in Figure l and is identified in its entirety by the numeral 11. Accordingly only those features of the switch 11 that differ from the construction of switch 11 will be discussed and similar parts will be identified by the same numerals with the addition of a prime.
The switch 11 is omnidircctional in operation and is rendered so by placing a pair of switches, similar to the switch 11 of Figure l, in back to lback relation and in the construction shown is of integral construction. ln this embodiment a pair of spherical members 22-22 are located at each end of the magnet 21 and electrical contact is made between the members 22 and respective end surfaces of the terminal bores 24-24. In this embodiment the terminal end surfaces of the bores 24 are shown as convex surfaces with respect to the magnet 21' when assembled in the housing 1S. The relationship of the magnet 21 with respect to the members 19-19 is further characterized as follows: The central portions of the end surfaces of the bores 24', with respect to the adjacent end surfaces of the magnet 21', are spaced apart a distance slightly exceeding the distance the uppermost and lowermost portions of the members 22-22 are above and below the adjacent end surface of the magnet 21 at such times as the members 22-22 are in their respective initial positions as shown by solid construction in Figure 2. Further the distance between the respective central portions of the end surfaces of the bores 24--24 and the adjacent end surfaces of the magnet 21 is slightly less than the diameter of the spherical members 22-22. In other words the spherical members 2222 as mounted in the housing 13 are not able to move an appreciable distance from their respective initial positions but rather they rock or pivot around the edges of the passageway 23. In this embodiment it will be seen that electrical contact is made between the spherical members 22 and the end surfaces of the bores 24-24 of the members 19 at such times as the switch 11 is activated.
In the switch 11' a connector 28 is connected to the magnet 21 while the connectors 26 and 27 are joined so that an electrical flow path will be provided at such time as either spherical member 22 is urged from its initial position to its unseated or final position. In view of the operational discussion in connection 4 with the switch 11 it is believed the operation of the switch 11' will be clear and further detailed discussion in this respect is not deemed necessary. It will be apparent, however, that the switch 11 will function to complete an electrical circuit regardless of the direction of an inertial force acting thereon. Should the switch 11 be accelerated in a true vertical direction as shown in Figure 3, one of the members 22', specifically the member which is free to move when acted on by the inertial forces, is urged away from its initial position and will contact theadjacent convex end surface of the bore 24. Gravity or inertial forces subsequently acting on the subject spherical member 22 will cause the latter member to move laterally on the convex surface and into contact with the edge of the passageway 23 as shown by dotted construction in Figure 3. Accordingly electrical contact will be established between the subject member 19 and magnet 21 and an electrical flow path established through the 'switch 18. It will therefore be seen that a true omnidirectional switch is provided in the latter embodiment regardless of the direction of inertial forces acting thereon. t
While in order to comply With the statute, the invention has been described in language more or less specificv as to structural features, it is to be understood that the invention is not limited to the specific features shown,` but that the means and construction herein disclosed comprise 4a. preferred form of several modes of putting the invention into effect, and the invention is therefore claimed in `any of its forms or modifications within the legitimate and valid scope of the appended claims.
What is claimed is:
1. In an electrical switch the combination comprising: a housing constructed of a dielectric material; a magnetizable metallic member having a pair of spaced parallel plane surfaces and a cylindrical bore extending between and opening on each of said plane surfaces; said magnetizable member being permanently magnetized so that a pole is located adjacent each end of said cylindrical bore; at least one cup-like metallic member which defines a cylindrical cavity that opens on an outside surface of said cup-like member; said magnetizable and cup-like members being mounted insaid housing in spaced relation with said bore and cavity in axial alignment with the open end of said cavity facing vsaid bore to define a receiving chamber therebetween; -and a spherical member `fabricated of electrical conducting material mounted in said receiving chamber for movement therein between initial and final positions in which an electrical flow path is not provided and is provided, respectively, through said switch in response to changes in either linear or angular accelerations of said switch.
2. In an electrical switch as set forth in claim 1: further characterized in that said magnetizable member is a right-angled cylindrical member and said at least one cup-like member constitutes a single member, the said outside surface of said cup-like member and the adjacent end of said cylindrical member are spaced apart a distance less than the radius of said spherical member, and said bore is less in diameter than the diameter of said spherical member and said cavity is greater in diameter than the diameter of said spherical member.
3. In an electrical switch the combination, comprising: a housing constructed of non-electrical conducting material; a permanently magnetized metallic member having a pair of spaced parallel surfaces; said mag` netized member defines a bore which extends completely therethrough in a direction normal to said spaced parallel surfaces; a pair of cup-like metallic members each having a pair of spaced parallel faces and each includes a cylindrical cavity the axis of which is normal to said parallel faces and one end of which terminates in a convex spherical surface and the other end opens on one of said parallel faces; said permanently magnetized and pair of cup-like members being mounted in said housing; said pair of cup-like members being mounted at respective ends of said permanently magnetized member with the open ends of said cavities facing the latter member and with the axes in said cavities aligned with the axis of said bore to deiine a pair of receiving chambers; and a pair of spherical members fabricated of electrical conducting material, a respective one of said spherical members mounted in each of said receiving chambers for movement therein between initial and nal positions in which an electrical flow path is not provided and is provided, respectively, between said permanently magnetized and non-magnetic members.
4. In an electrical switch as set forth in claim 3: further characterized in that said bore is smaller in diameter than the diameter of said spherical members and the intersection of said bore with said spaced paral- References Cited in the iile of this patent UNITED STATES PATENTS 1,662,979 Nelson Mar. 20, 1928 2,415,086 Detwiler Feb. 4, 1947 2,744,976 Black May 8, 1956 2,791,653 Haberland May 7, 1957