IL37554A - Magnetic switches and method and apparatus for making them - Google Patents

Description

This invention relates to switch devices of a type in which switching contacts are controlled by a reciprocable permanent magnet and to a method and an apparatus for constructing such devices. The devices are readily and economically manufacturable while being reliable in operation. Uniform operating characteristics are obtained even with variations in the characteristics of magnets and other components.

Magnetic reed switch devices are known in which a reciprocable magnet controls actuation of a reed switch such as, for example, one of the type comprising resilient contact elements of magnetlo material extending within and from opposite ends of an elongated sealed glass envelope to free ends in overlapping relation, such free ends being engagable under the influence of the magnetic field of a permanent magnet positioned in proximity thereto. Such magnetic reed switch devices have important advantages. The reed switch is explosion proof and with evacuation of the envelope, arcing and pitting of the contacts are substantially obviated. However, prior art devices have not always been uniform and reliable in oper-ation, especially when a plurality of switches are used in proximity to one another as is often the case with pushbutton switches, for example. In addition, the prior art devices have generally been difficult and expensive to manufacture.

This invention was evolved with the general object of overcoming the disadvantages of prior devices and of providing switch devices which are uniform and reliable in operation while being readily and economically manufacturable.

Another object of the invention is to provide improved methods of constructing switch devices using movable magnets. A further object is to provide improved apparatus for - - constructing switch devices using movable magnets.

In accordance with an important feature of the invention, a switch device is provided in which a first holding means holds magnet means on an actuating structure for rectilinear bodily movement in a certain path while a second holding means holds a magnetically actuatable switch means on a support structure, at least one of such holding means including slida-bly and frictionally interengaged surface means permitting rectilinear positional adjustment in a direction parallel to the direction of the rectilinear movement. With this arrangement, the position of the actuating structure at which the magnet means effects actuation of the switch means can be adjusted. Preferably and in accordance with a very important feature, the holding means is accessible for adjustment after assembly of the device so that each completed device can be adjusted to obtain operation when the actuating structure is at a predetermined position and all switch devices released from production can have the same operational characteristics. This feature is found to be very important not only in achiev-ing uniformity, but also in reducing the possibility of malfunctions when a plurality of the switch devices are used in close proximity, as is often times the case. When the switch means of all devices are operated at a predetermined intermediate position of the pushbutton or other actuating structure, it is found that although the magnetic field from a closely adjacent switch device may change somewhat the position of operation, it will not effect it to the extent of preventing operation thereof. Further, since each device is effected by other devices to the same extent that the other devices are effected by it, all devices will have substantially the same - - f characteristics .

Important specific features of the invention relate to the manner of construction which permits the adjustment to be readily accomplished after assembly of the device. For example, one feature is in the provision of a roll pin disposed in an axially extending passage of a pushbutton actuating element, one end of the roll pin being engaged with a magnet and the other being engagable by an adjustment tool to permit adjustment of the position of the magnet after assembly.

Additional important features of the invention relate to constructional arrangements by which the devices are readily and economically manufacturable while being rugged and reliable in operation. One of such features is in the provision of a socket in the end of a pushbutton element or the like for receiving a magnet with a coiled compression spring being disposed between the magnet and an end wall of a housing for both holding the magnet in the socket and for acting as a return spring for the pushbutton element. Another is in the provision of one or more integral resilient fingers extending along the side of the pushbutton member toward the closed end of the housing with a transverse projection on the free end of each finger arranged to spring outwardly when the pushbutton is inserted into the housing in assembly to engage a stop surface in the housing and to act as a return stop for the pushbutton.

Another one of such features relates to the mounting of a reed switch in which leads found on the switch are soldered or welded to portions of a one-piece stamping which is thereafter severed and which then provides both terminals of the device. Another important feature of the invention relates to a method of construction of the switch devices in which the devices are assembled with an adjustable element displaced in one direction away from the normal range of positional adjustment thereof and after assembly, the element is moved in an opposite direction until the desired operation is effected. In particular, a pushbutton element can be held in an intermediate position and the adjustable element is then moved until the operation of the switch is effected.

A further important feature relates to apparatus for performing the adjustment automatically.

This invention contemplates other objects, features and advantages of which will become more fully apparent with reference to the detailed description taken in conjunction with the accompanying drawings which illustrate preferred embodiments and in which: FIGURE 1 is an elevational view showing two switch devices constructed in accordance with the principles of the invention; FIGURE 2 is a sectional view of one of the devices of FIGURE 1, taken substantially along line II-II of FIGURE 1; FIGURE 3 is a sectional view taken substantially along line III-III of FIGURE 2; FIGURE 4 is a sectional view taken substantially along line IV-IV of FIGURE 2; FIGURE 5 is a sectional view, on a greatly enlarged scale, of an adjustment pin of the device of FIGURES 2-4; FIGURE 6 is an elevational view illustrating the form of a stamping used in the support of a switch in the device of FIGURES 2-4; FIGURE 7 illustrates the stamping of FIGURE 6 after per-forming a bending operation; FIGURE 8 shows the assembly of the stamping of FIGURE 7 and a reed switch; FIGURE 9 is a view showing the assembly of FIGURE 8 after performing a severing operation; FIGURE 10 shows the mounting of the assembly of FIGURE 9 on a cap member; FIGURE 11 shows the combination of the assembly of FIGURE 10 and a main housing body portion; FIGURE 12 is an elevational view of a sub-assembl of a pushbutton and magnet, partly in section; and FIGURE 13 shows apparatus constructed in accordance with the invention, used in the construction of the switch device of FIGURES 2-4.

Reference numeral 10 generally designates a pushbutton switch device constructed in accordance with the principles of this invention. The device 10 comprises a housing 11 and a pushbutton 12 which is depressed to electrically connect a pair of terminals 13 and 14 which may be connected to circuitry to be controlled.

As shown in FIGURE 1 , the housing 11 of the device may be inserted through an opening 15 in a panel 16 to extend a threaded mounting stud 17 and the terminals 13 and 14 through openings in a board 18, a nut 20 being threaded on the stud 17. Board 17 may be a printed circuit board having circuitry directly connected to terminals 13 and 14, if desired. A vertically extending locating rib 21 is provided on one side of the housing 11 to extend through a notch 22 of the opening 15 and three additional ribs 23 are provided, adapted to engage the top surface of the panel 16 about the opening 15 . It is here noted that the device 10 may be oriented in any direction and terras such as "vertical", "horizontal", "upper", "lower", and the like are used for ease and clarity of description and are not to be construed as limitations.

In FIGURE 1, the device 10 is shown mounted in close proximity to a device 24 of identical construction and addi-, tional devices may be similarly mounted in any desired grouping arrangement. It will be understood that mounting arrangements other than the illustrated arrangement may be used.

Referring to FIGURE 2, a magnet 25 is held on the push- button 12 for movement therewith and when the pushbutton 12 is depressed, the magnetic field of the magnet 25 effects actuation of a reed switch 26 held inside the housing 11 along-side the portion of the pushbutton 12 in the housing 11 .

Magnet 25 is preferably a cylindrical ferrite magnet which is magnetized in an axial direction, to provide opposite magnet poles at the upper and lower planar faces thereof.

Reed switch 26 comprises an elongated casing or envelope 27 of glass or other dielectric material, the envelope 27 being preferably evacuated or filled with an inert gas. A pair of reed contacts 29 and 30 of magnetic material are disposed within the envelope 27 to extend from opposite ends thereof to free ends in overlapping relation. Contacts 29 and 30 are normally disengaged but when the magnet 25 is moved to a position such that the opposite poles thereof are disposed opposite the contacts 29 and 30, the contacts 29 and 30 are drawn together into tight engagement.

Other types of magnetically actuated switches may be employed, if desired, and the housing 11 may be arranged for mounting of one or more additional switches therein, for simultaneous actuation.

Important features relate to the manner in which the magnet 25 is held on the pushbutton 12 for movement therewith. Pushbutton 12 is formed with a socket 31 which receives the magnet 25 and also the upper end portion of a coiled compression spring 32 engaged with the lower face of the magnet 25 . The lower end of the spring 32 is seated in a socket 33 formed by a generally cup-shaped portion 3^ of an end cap 35 of the housing 11 . In assembly, the end cap 35 is bonded to a main body portion 36 of the housing, preferably by means of an ultrasonic bonding or welding operation. Both the end cap 35 and the main body portion 36 are preferably of a molded plastic material.

It will be noted that the spring 32 serves to hold the magnet 25 in the socket 31 and also serves as a return spring for the pushbutton 12 to move it upwardly when released. In addition, the spring 3 serves to hold the upper face of the magnet 25 against an adjustment pin 37 which is disposed in a passage 38 of the pushbutton 12, extending from the upper end of the socket 31 to the uppper end face of the pushbutton 12. By axial adjustment of the position of the pin 37, the position of the magnet 25 relative to the pushbutton 12 is adjusted and it is possible to obtain actuation of the switch 26 at a predetermined intermediate position of the pushbutton 12, with a high degree of accuracy, irrespective of variations in the characteristics of the magnet 25 and the switch 26. This feature is particularly important when the switch device is used in proximity to other devices similarly constructed or otherwise in the presence of relatively strong external magnetic fields. If the relative position of the magnet 25 on the pushbutton 12 and the relative position of the switch 26 and the housing 11 were both fixed, variations in the characteristics of the magnet 25 or the switch 26 might produce a condition in which the switch would be actuated without depressing the pushbutton, in response to an external field such as produced by operation of an adjacent switch. It is also desirable that a substantial movement of the pushbutton 12 be required for switch actuation without however requiring an unduly large range of movement of the pushbutton 12.

A method and an apparatus for adjusting the position of the pin 37 are described hereinafter but it is noted that an important feature is that the passage 38 extends to the upper face of the pushbutton 12 so that pin 37 is accessible for adjustment after assembly. The pressure of engagement between the outer surface of the pin 37 and the inner surface of the passage 38 is such that the pin is securely held in an adjusted position through the frictional interengagement and at the same time it is such that the relative slidable movement necessary for adjustment is permitted. Preferably, the pin 37 is a roll pin formed by rolling a strip of thin resilient sheet steel with more than one complete convolution and most preferably with at least two as shown in the cross sectional view of FIGURE 5. With this feature, the" pin can be resili-ently compressed to permit insertion and slidable adjustment while at the same time a tight frictional interengagement is obtained. Another important feature of the invention is in the provision of a pair of integral fingers 39 and 40 on the pushbutton 12 extending downwardly along opposite sides thereof with integral outward projections 4l and 42 on the free ends of the fingers 39 and 40 defining upwardly facing sur-faces engagable with stop surfaces 3 and 44 in the main body portion 36 of the housing, to limit upward movement of the pushbutton 12. The main housing body portion 3 has axially extending internal grooves 45 and 46 which receive the fingers 39 and 40. To facilitate assembly, the lower faces of the projections 4l and 42 are preferably inclined to cam the free ends of the fingers inwardly when inserting the pushbutton 12 into the housing 11. When the projections 4l and 42 are positioned below the stop surfaces 43 and 44, the fingers 39 and 40 spring outwardly to limit upward movement of the pushbutton 12 and withdrawal of the pushbutton 12 from the housing 11.

Downward movement of the pushbutton 12 is limited by the engagement of a downwardly facing shoulder 48 thereof with the upper surface of the main body portion 36.

Another important feature of the invention relates to the manner in which the reed switch 26 is supported and electrically connected to terminals 13 and 14. As shown in FIGURE 6, a stamping 50 is provided including a horizontally extending first portion 1, second and third portions extending down-* wardly from opposite sides of the portion 1 to define the terminals 13 and 14, a fourth portion 52 extending horizontally in spaced parallel relation above the first portion 1 and a fifth portion 53 extending vertically in-between the first and fourth portions 51 and 52. After cutting to the shape shown in FIGURE 6, the stamping 50 is bent to turn part of the first portion 51 at right angles to the remaining part, as shown in FIGURE 7. Then as shown in FIGURE 8, leads 55 and 56, connected to the reed contacts 29 and 30, are soldered or welded to the first and fourth portions 51 and 52.

As shown in FIGURE 9, a die-cutting operation is perform-ed to cut away a part of the portion 51, between the points of connection of lead 55 and portion 53 thereto and to provide a separation 57 and two separate electrical paths from the leads 55 and 6 to the terminals 13 and 14.

Next, the sub-assembly shown in FIGURE 9 is mounted on the end cap 35 to extend the terminals 13 and 14 through openings in the end cap 35 , the stud 17 having been bonded to the end cap in a separate operation. ■ This operation is shown in FIGURE 10. This step is preferably performed while holding the sub-assembly of FIGURE 9 in the same jig as that in which · the die -cutting operation was performed so that the parts are readily and properly aligned.

As the next step, the combination shown in FIGURE 10 is combined with the main body portion and the end cap 35 is bonded to the main body portion 36, preferably with an ultrasonic bonding or welding operation. In this operation, the switch 26 and the portions 5 and 53 of the stamping 50 are disposed in an axially extending slot 58 in the main housing body portion 36. Also, the portion 5 of the stamping 0 is tightly clamped between opposed surface portions of the end cap 35 and main body portion 36 . The switch assembly is thus firmly held in position.

In separate operations, the pin 37 is inserted into the passage 38 of the pushbutton 12 to a position in which the lower end thereof is at the upper end of the socket 31, and the magnet 25 is then inserted into the socket 31 to be held by a magnet attraction to the pin 37 . A sub-assembly is thus formed as shown in FIGURE 12, and after insertion of the spring 32 into the main body portion of the housing, the pushbutton assembly of FIGURE 12 is inserted to be locked into the housing through the operation of the spring fingers 39 and 40.

An important feature is that with the magnet 25 in the upper end of the socket 31, as shown in FIGURE 12, it is displaced upwardly from the positional range of proper operation of the device and with the magnet 25 so positioned, it can he simply moved downwardly until properly positioned. This is accomplished by positioning the pushbutton 12 at a predetermined intermediate position and then inserting an actuating pin into the passage 38 and moving it downwardly until the switch 26 is actuated. This operation can be effected by hand or automatically by apparatus constructed in accordance with the principles of the invention, shown in FIGURE 13.

With reference to FIGURE 13, reference numeral 60 generally designates an automatical adjustment system, according to the invention in which the switch 10 is supported on a suitable support 6l, which may, for example, by an indexing turntable on which the assembly operations are performed, the adjustment being effected at a final station in the assembly operation. In the operation of the system 60, a pair of clamp devices 62 are first moved together to surround the upper por-tion of the pushbutton 12, clamp devices 62 being actuated by a suitable mechanism 63 which may be electrically controlled or actuated, and controlled from a control circuit 64 . After moving the clamp devices together, a pin 6 is driven downT wardly by means of a lead screw 66 which is driven through a speed reducer 67 from a reversible motor 68. Pin 65 enters the passage 38 in the pushbutton 12 and engages the adjustment pin 37. The pushbutton 12 is carried downwardly until shoulders thereof engage upwardly facing shoulders 69 and 70 of the clamp devices 62. The pushbutton is then at a predetermined intermediate position. With further downward movement, the pin 37 is moved downwardly relative to the pushbutton 12 to move the magnet 25 downwardly also. When contacts 29 and 30 of the reed switch 26 engage, a circuit is completed through conductors 71 and 72 to the control circuit, conductors 71 and 72 being connected to the terminals 13 and 14. Control circuit 64 then reverses the motor 68 to move the lead screw 66 and pin 65 upwardly until returned to the initial position. Finally, the clamp mechanism 63 is actuated to withdraw the clamp devices 62.

It will be understood that modifications and variations may be effected without departing from the spirit and scope of the novel concepts of this invention. 37554/2

Claims (16)

1. A switch device, comprising: magnetically actu table magnet means Bwltch meanSj/for actuating said switch means when disposed in proximit thereto, an actuating structure, a support structure supporting said actuating structure for rectilinear movement relative thereto, first holding means including spring biasing means for holding said magnet means on s aid actuating structure and for providing spring biased, rectilinear bodily movement in a certai path and second holding means for folding said switch means o said support structure at a position in proximit to said certain path, at least one of said holding means including slldably and frictionally interengaged surface means permitting rectilinear positional ad ustment in a dlreotlon parallel to the direction of said rectilinear movement for adjustment of the device to obtain operation of said switch means when said actuating structure is moved to a certain position relative to said support structure.

2. The switch device as claimed in Claim 1, said one of said holding means including means accessible for engagement after assembly of said device for adjustment of said holding means*

3. The switch device as claimed in Claim 1, said slldably and frictionally interengaged surface means being Included in said first holding means, whereby t#e position of said magnet^ means is adjustable relative to said actuating structure.

4. The switch device as claimed in Claim 1, said actuating structure including a reciprocable member, and said 37554/2 first holding means comprising socket means at one end of said member for receiving said magnet means, axial passage means extending from said socket to the opposite end of said member, and an adjustment pin in said passage means engagable with said magnet means, said slidable and frictionally Inters engaged surface means being defined by the other surface of said adjustment pin and the inner surface of said passage means.

5. The switch device as claimed in Claim 4, said pin being a roll pin defined by substantially more than one convolution of a resilient metal strip.

6. The switch device as claimed in Claim 4, said support structure comprising hollow housing means defining an internal guideway receiving said reciprocable member and having a closed end wall facing said socket means, and a coiled compression spring acting between said closed end wall and said magnet means to hold said magnet means in said socket means and against said pin and to urge said reciprocable member away from said closed end wall.

7. The switch device as claimed in Claim 6, wherein said closed end wall includes spring- receiving socket means for receiving one end of said coiled compression spring.

8. The switch device as claimed in Claim 6, comprising: at least one resilient finger integrally connected at one end to said reciprocable member and extending along one side of said member toward said closed end wall of said housing means to an opposite free end, and an integral projection on said free end of said finger projecting transversely and outwardly therefrom, said housing means having an internal stop surface facing said closed end and engagable by said .projection to limit movement of said reciprocable member away from said closed end wall, said free end of said finger being deflectable, inwardly during assembly until positioned beyond said stop surface.

9. • 9. The switch device as claimed in Claim 8, including a second resilient finger integrally connected at one end to said reciprocable member and extending along an opposite side of said member toward said closed end wall of said housing means to an opposite free end, and an integral projection on said free end of said second finger projecting transversely and outwardly therefrom, said housing means having a second internal stop surface facing said closed end wall and engagable by said projection of said second finger at the same time that the projection of said first finger engages said f rst internal stop surface.

10. The switch device as claimed in Claim 6, wherein: said switch means comprises a reed switch including an elongated hollow casing and a pair of contacts of resilient magnetic material extending w thin said casing from opposite ends thereof to free ends in overlapping interengagable relation; said second holding means comprises a stamping including a first portion in generally transverse relation to said casing, second and third portions projecting from opposite ends of said first portion in generally parallel relation to said casing and defining switch terminals, a fourth portion in generally parallel relation to said first portion, and a fifth portion between said first and fourth portions in generally parallel relation to said casing; and including a pair of lead wires having ends connected to said contacts and projecting from said casing to opposite ends connected to points between said first and fourth portions, said first portion being severed at a point between the connections of said lead wire and said fifth portion thereto.

11. The switch device as claimed in Claim 10, wherein said hollow housing means includes a main body portion, and said closed end wall includes an end cap portion bonded to said body portion, said end cap portion having openings therethrough which said second and third portions of said stamping are extended, said end cap and body portions having opposed surfaces in clamping engagement with said first portion of said stamping. 37554/2

12. A method of constructing the switch device according to Claim 1, said method including the steps of: assembling said device with said adjustable means at a position displaced in one direction awajp from the normal range of positional adjustment thereof, holding said actuating structure at a predetermined position» and engaging and moving said adjustable means in an opposite direction until actuation of said switch means is effected*

13. · An apparatus for constructin the switch device according to Claim 1, said apparatus including: means fo supporting said switch device, means for holding said actuating structure at ascertain position, electrically controlled means for engaging said adjustment means and moving said adjustment means in a direction opposite said one direction, and means constrolled from said switch means for discontinuing operation of said electrically controlled means upon actuation of said switch means.

14. The apparatus as claimed in Claim 13, wherein said aduatlng structure includes a reciprocable member, wherein said first holding means comprises socket means at one end of said member receiving said magnet means, axial passage means extendin from said socket to the opposite end of said member and an adjustment pin in said passage means engagable with s aid magnet means, said electrically controllable means comprising a pin adapted to extend through said passage means into engagement with said 37554/2 £

15. · A switch device as claimed in Claim 1, substantially as described with reference to the accompanying drawings.

16. A method of constructing the svitch device according to Claim 1, substantially as described with reference to the accompanying drawings. 17· An apparatus for constricting the switch device according to Claim 1 substantially as described with reference to the accompanying drawings. For the Applicants TNERS