US3832505A - Piston actuated switch with screw threads on piston and housing - Google Patents

Abstract

The invention comprises a cylindrical housing having an internal telescopic split bore for receiving a solenoidally actuated piston. The piston has an extremity spring biased and anchored and the other extremity has disposed thereon a resistive contact. The split bore is conductively coated and separated by an insulative medium. The resistive contact on said piston is disposed to engage one of said conductive contacts in response to the excitation of the solenoid to permit conduction under the control of the resistive contact. Removal of the excitation permits the piston to return to its original position under the control of the spring bias. The amplitude of make and break of contact currents is controlled by the resistive element during the initial stages of switching.

Description

United States Patent [191 Wong [451 Aug. 27, 1974 PISTON ACTUATED SWITCH WI'IH SCREW THREADS ON PISTON AND HOUSING Inventor: Franklin Victor Wong, 777 County Line Rd., Apt. 23A, Amityville, NY. 11701 Filed: May 15, 1973 Appl. No.: 360,462

US. Cl 200/158, 335/257, 200/33 R Int. Cl. H01h 3/40 Field of Search 317/1 12-114; 200/82 R, 82 E, 158, 33 R, 33 D, 61.08, l suiizi/ atzirzss References Cited UNITED STATES PATENTS Ferrara 200/33 R 3,524,960 8/1970 Lohff 200/158 Primary Examiner-Robert K. Schaefer Assistant Examiner-Gerald P. Tolin ABSTRACT The invention comprises a cylindrical housing having an internal telescopic split bore for receiving a solenoidally actuated piston. The piston has an extremity spring biased and anchored and the other extremity has disposed thereon a resistive contact. The split bore is conductively coated and separated by an insulative medium. The resistive contact on said piston is disposed to engage one of said conductive contacts in response to the excitation of the solenoid to permit conduction under the control of the resistive contact. Removal of the excitation permits the piston to return to its original position under the control of the spring bias. The amplitude of make and break of contact currents is controlled by the resistive element during the initial stages of switching.

5 Claims, 18 Drawing Figures PATENTEnAuazmu SHEET 10F 3 Fig.1.

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PISTON ACTUATED SWITCH WITH SCREW THREADS ON PISTON AND HOUSING BACKGROUND AND THE INVENTION GENERALLY This invention relates to electric switches, specifically to the plunger actuated switch of new and novel construction utilizing a cylinderical piston as one leg of the contact surface, and a fixed cylindrical receiver comprising the other contact surface and also to the new and novel construction of utilizing electrical passive elements in the form of resistance, inductance, capacitance, or semiconductor diode as an integral part of the piston.

Relay switches of prior art have utilized a plunger to transverse the gap between two (2) fixed point contacts thus fundamentally completing the electrical continuity of a circuit. A number of switches of prior art do not take into consideration however the reverse flow of Electromotive Force resulting from a load impedance consisting of electrical inductance and capacitance. In addition, prior switches were susceptible to resistance variation resulting from Hot-Switching which has a departmental effect on low level electrical potential.

The present invention utilizes a cylindrical relay coil enclosing the contact surface area of a switch which generates an electro-magnetic field around the contacts, and actuates a rotatable, slidable, sectionalized piston. I

The invention consists of a cylinderical insulated form about which a cylinderical relay coil is mounted, including a pair of terminals for the coil to which electricity is applied for activation. The relay coil is positioned such that the electro-magnetic field encompasses the mating surfaces of the switch and, in addition, imparts a magnetic translatory force on a piston which essentially becomes the armature of a solenoid. The insulated cylinder which houses a threaded stationary receiver and threaded piston is molded and shaped to form a cylindrical cavity. The material selected, such as teflon, or glass, for the insulated cylinder shall exhibit sufficient strength to withstand shock, vibration, and pressure to function in an adverse entironment and, if necessary, electro-magnetic interference and radio interference shields are adaptable to enclose the switch.

The threaded receiver comprising a uniform hollow cylinder with expanded section forms one of the contact surfaces of the switch, which is mounted rigidly in an enclosed insulated cavity. A terminal welded to the receiver provides the means for connecting the circuit to be controlled and, in addition, the allocation of sufficient head space directly in front of the uniform hollow circular cylinder allows the piston to protrude through the receiver when the switch is energized to close the contacts. The expanded section incorporates an inner conductive lining spanning the circumference of the receiver and reaches the piston seats. The conductive lining has uniformly spaced fingers which exert a force against the piston to insure agood electrical continuity. The construction of the lining specifically the fingers at present has been conceived to assume a concave curvature, which will exhibit characteristics of elasticity and resiliency to retain its original shape after the withdrawal of the piston assuming the open state.

The complete inner lining of the switch consists of a circular insulator separating the piston conductor and another circular insulator which electrically isolates the piston and spring assembly from the receiver. A terminal welded to the piston conductor provides the means for connecting the circuit to be controlled.

A rotatable piston consists of four (4) sections having a common threaded center shaft on which all sections are joined together. The center shaft represents the conduit that provides the electrical path to the receiver. A threaded resistance section forms the head of the piston and is constructed longer than the uniform hollow reduced circular section of the receiver; thus, electrical contact is made prior to the full engagement of the switch. During this period of initial contact between the resistance section and the receiver, electrical current will start to flow between the terminals via the passive elements which includes the resistance section and the rear of the piston body which is electrically part of the piston conductor. The rate of rise or fall of the voltage and current depends on the values selected for the passive elements which are in series with the electrical circuit. As the piston slides forward, the engagement of the threads causes the piston and related assemblies to rotate approximately between and 270 in a clockwise direction whichever is most suitable. The rear conductor of the piston is held rigidly to the spring assembly by an insulated circular retainer which is secured to the threaded center shaft conductor by a lock-nut. Thus, the piston and spring assembly function as a single integral unit. A return force exerted by the spring overcomes the inertia of the piston and withdraws the unit to break contact in two steps after removal of the coil voltage. The piston body will break contact first with the receiver lining; however, since the resistance section is designed to be much longer than the reduced receiver section, contact is still maintained and electrical current will flow at a reduced level. Consequently, circuit continuity is broken at a lower electrical potential reducing the contact arcing that arises from the ionization of the air between the contacts. The spring is anchored securely to a circular insulated plate which floats on ball bearings and allows the whole spring assembly to rotate; thus, reducing the friction at the rear of the switch. Also, part of the spring assembly is the rear circular cover securely attached to the insulated cylinder housing which provides access to the internal parts of the switch. In addition, this access provides an option to repair and replace parts from normal and abnormal usage.

The primary object of this invention is to provide a switch that controls the flow of electrical energy to a prescribed time constant by the use of passive elements that exhibit certain electrical properties.

Another object is to provide a switch that is specifically designed to function with an electrical potential on both contact surfaces. In relay terminology this function is defined as Hot-Switching.

Another object is to provide a switch that minimizes the ionization of the air between two (2) contact surfaces by reducing the electrical potential on the contacts; subsequently, switching of electrical potential is accomplished at a reduced level.

Another object is to provide a switch that minimizes the contact junction temperature, which literally destroys the contact surfaces, by reducing the electric po tential at which the switch is energized and deenergized, thus increasing the reliability of the switch after repeated open and closures.

Another object is to provide a switch with a cylinderical contact surface area in which a uniform contact re sistance is maintained after repeated use.

Another object is to provide a switch consisting of multiple removable sections whereby different configurations may be selected.

Another object is to provide a switch that has one contact which rotates aspecific angle to wipe and clean each contact surface to remove any residue that accumulates when two electrical potential surfaces are constantly being switched.

Other objects and advantages will become apparent from a reading of the specifications and a study of the accompanying drawings and wherein;

FIG. I is an enlarged longitudinal cross-sectional view of the switch showing the piston in the retracted position;

FIG. 2 is a sectional view of FIG. 1 taken on the line AA thereof;

FIG. 3 is a top view of the receiver lining seen in FIG.

FIG. 4 is a front view of the receiver lining seen in FIG. 1;

FIG. 5 is a side view of the receiver lining seen in FIG. 1;

FIG. 6 is a cross-sectional view of the piston enlarged to show the composite section mated together as seen in FIG. 1;

FIG. 7 is a cross-sectional view of FIG. 6 taken in the line BB thereof, which shows the resistance section in detail;

FIG. 8 is a cross-sectional view of FIG. 6 taken in the line C-C thereof, showing the cone-shaped insulator;

FIG. 9 is a view similar to FIG. 7 showing a threaded shaft attached to the resistance section;

FIG. 10 is a view similar to FIG. 8 showing a modification to incorporate a passive element exhibiting an electrical inductance which is secured to FIG. 9, the resistance section;

FIG. 11 is a view similar to FIG. 8 showing a modification to incorporate a passive element exhibiting an electrical capacitance which is secured to FIG. 9.

FIG. 12 is a view similar to FIG. 8 showing a modification to incorporate a passive element exhibiting directional characteristics such as a semiconductor diode, which is secured to FIG. 9;

FIG. 13 is a crossrsectional view of the piston showing a modification to incorporate a threaded shaft which is secured to FIG. 8 and its associated sections;

FIG. 14 is a detailed view of the insulated assembly secured to the rear of the piston by a lock-nut as seen in FIG. 1 and in addition provides a retainer for the spring;

FIG. 15 is a front view of the insulated assembly as seen in FIG. 14;

FIG. 16 is a front view of the spring rear assembly as seen in FIG. 1;

FIG. 17 is a detailed view of the spring rear assembly as seen in FIG. 1, showing the insulated retainer mounted on ball bearings to which the spring is attached;

FIG. 18 is an electrical schematic defining the mechanical action that the switch performs; as shown, the switch is in the de-energized or normally open state.

Referring now to the drawings wherein like numerals refer to like and corresponding parts throughout the several views, the novel switch disclosed therein to illustrate the invention comprises, a switch body 1 exhibiting electrical insulating properties having a piston slide chamber line with a receiver lining 11, an insulated lining 17, which electrically separates the receiver lining 11 and piston lining 21 and finally another insulated lining 26 which electrically separates the piston lining 21 from the spring 27 and ball bearings 28. The cylinderical cavity formed by linings ll, 17, 21 and 26 constitute a chamber 9A to house and provide a contact surface for the piston 19 to rotate and slide on. At present, it is conceived that the piston lining 21 is constructed of a material that exhibits good conductivity and polished surface to reduce friction, in addition to being of sufficient hardness to sustain repeated operations.

The receiver section 3 is chambered to fit the piston 19 when fully engaged, stops 9 are constructed to seat the slidable piston 19. The minimum thickness of the walls of the receiver 3 is selected to be adaptable to accept internal mounted threads 4 and 5. These threads 4 and 5 are tapped to a minimum depth resembling rifling and having a screw pitch to rotate the piston approximately three-quarters of a turn for full engagement of the piston 19. Upon powering of the coil 8, the magnetic field generated thereby surrounds the contact surfaces and causes the piston 19 to move into the receiver 3.'This moves the switch from the normally open position established by the spring assembly 27 to the actuated closed position. In the normally closed position, the engagement of the threads 12 and 13 imparts a rotary force on the piston 19 and also provides the initial electrical contact between terminals 7 and 34. The point 10 of the piston 19 has been chosen as a convenience, and it may be constructed in the shape of a semi-circle if so desired; however, when the piston 19 is fully engaged with the receiver 3, the displacement of the resistance section 14 that protrudes into the chamber 2 is at a minimum. FIG. 2 exemplifies the front view of the switch taken from line A-A which depicts the exterior outline of the switch body 1; it was conceived to be circular, however, it is obvious that other types of exterior frames for the switch body are adaptable. The walls of the insulated switch body 1 was envisioned to be of minimum thickness with sufficient strength to house the internal parts of the switch. FIG. 3 details the receiver lining 11 showing the circular design contact surface when formed into a cylinder and inserted into the receiver 3. FIG. 4 shows an expanded view of the receiver lining ll specifically the uniformly spaced cutouts 37 which allows the fingers 37A to assume a prescribed curvature 36A as shown in FIG. 5, which applies a spring force against the piston 19 when compressed during closure of the switch. A right angle bend l6 and triangular cutouts 16A seen in FIG. 5 denotes the method in which the receiver lining 11 is anchored to the receiver section 3 and the other bevel end 36 remains free to move when compressed.

A composite cross-sectional view of the piston 19 is seen on FIG. 6 delineating the four sections of the assembly. The threaded shaft 20 essentially is universal to all four sections 14, 18 19A and 23; in addition, it functions as an electrical conductor which connects the resistance section 14 to the piston body 19A. Each section and lock-nut 32 is threaded on the shaft in the counter clockwise direction, that is, if the piston 19 and assembly rotate clockwise. A lock-nut 32 secures the sections on the shaft to insure that the sections of the piston 19 from rotating loose. Each section of FIG. 6 that needs clarification is detailed in a cross-sectional view as shown on FIG. 7 line B-B and FIG. 8 line C-C. The resistance section 14 shown on FIG. 7 consists of a good conductive metal jacket 15, machined or polished to a smooth finish to reduce friction as much as possible, covers a molded resistive material 37 deposited on a metallic hollow shaft 38 threaded internally. An insulator 18 is presently conceived to be constructed of teflon or other machinable material, will exhibit a hollow shaft threaded 18A; thus allowing the shaft 20 to be threaded through the insulator 18. The conical shaped insulator 18 has the characteristics of elasticity to absorb shock of the piston 19 abutting itself against the stops 9 in the normally closed position. The body of the piston ,19A is envisioned to be constructed of a lightweight metal of good conductivity and possess a smaller diameter than the rear of the piston 23 which is in contact with the piston conductor 21 as seen in FIG. 1. Consequently, this reduced diameter of the piston 19A allows no electrical contact with the piston conductor 21; however, its function is to make a physical and electrical contact with the receiver lining 11. A cutout 22 exists between the piston body 19A and the rear section 23 to separate the two sections 19A and 23 from the receiver section 3 and piston conductor 21 to prevent an electrical short circuit during closure of the switch. The rear of the piston 23 is constructed to have a smooth finish and close tolerance and of sufficient width to handle the power being switched.

In order to insulate the piston 19 from the spring 27 as seen on FIG. 1, item 24, which retracts the piston 19 to the normally open state, a teflon or other machinable material is constructed as shown on FIG. 14. One hole 46 is drilled through the center of the insulator 24 to accept the threaded shaft 20 and the other hole 47 is drilled approximately half-way through the rear of the insulator 24 to allow the lock-nut as seen on FIG. 6 to be recessed. A spring retainer chamber 25 is provided to seat the spring 27 which is retained by stops 48. A front view seen from FIG. 15 denotes the circular nature of the insulator 24 and the related cut-outs; in addition, the diameter of the insulator 24 is designed to have a smaller diameter than the rear of the piston body 19A which reduces the friction against the piston conductor 21.

The rear spring assembly as seen in FIG. 1, is detailed on FIG. 16 and FIG. 17 consists of an assembly of different parts 27, 28, 29, 30, 31 and designed to provide access to the internal mechanisms of the switch and a freedom of movement for the piston 19. The rear of the spring assembly as seen on FIG. 16 is attached to the switch body 1 which has the same diameter 31, by captive screws placed around the circumference. Other related parts seen in FIG. 16 provide a prospective view of the shape of the spring assembly. An enlarged detail view of the spring assembly seen on FIG. 17 details each part of the assembly for clarification. The major housing 31 for the spring 27 is constructed of a strong insulated chamber 31A to receive the spring retainer 29 and ball bearings 28 on which the spring retainer revolves on. I-Ioles are drilled and counter-sunk 30 to allow the captive screws to seat properly, only four are shown, if a hermatical seal is desired, a gasket and additional screws will be required. The spring 27 at present has been envisioned to be anchored to the spring retainer 29 by attaching bolts 35; however, this method does not preclude the fact that the spring 27 and ball bearings 28 cannot be molded together as one piece with the retainer 29. As seen on FIG. 16, the spring retainer has a smaller diameter than the chamber 31A; thus, sufficient space is provided for freedom of movement of the spring retainer 29. A number of ball bearings 28 are placed around the circumference of the spring retainer 29 to reduce the friction during rotation of the piston 19. These ball bearings 28 are retained by the seats which is a pivoting point.

Seen on FIG. 1 are two terminals 7 and 34 which are connected to the Direct Current circuit to be controlled and welded to the receiver lining 11 and piston conductor 21, respectively. The Direct Current and Voltage capacity being switched governs the physical size of the overall switch conduits and passive elements. It is obvious that the difference in the current and voltage capacity of the switch determines the passive resistance value 37 of the piston 19; that is, a high DC current would require more resistance than a low current switch. The switch envisioned does not predetermine which polarity is connected to each terminal; however, when a semiconductor is selected as a passive element, the direction of Direct Current flow will have to be considered. The power to the relay coil 8 can be transmitted through conduits connected in any feasible configuration that is acceptable during manufacturing.

Another feature of this invention is the adaptability of the switch to provide a number of different configurations to suit the load that it controls. The modification of the piston 19 seen on FIG. 13 allows the selection of different passive elements which can be attached to the main body of the piston 198. The shaft 45 as seen on FIG. 13 has been envisioned to be constructed with sufficient reversable threads 45A to protrude out from the piston body 198 to accept the elements seen on FIG. 10, FIG. 11 and FIG. 12. An inductance 41 spot-welded 42 between two metallic reverse threaded terminals 39 as seen on FIG. 10 represents one option that can be attached to the shaft 45 as seen on FIG. 13. Similar to FIG. 10 another option that can be selected is seen on FIG. 11 and FIG. 12; in FIG. 11, a capacitance 43 is attached between two terminals 39, and also seen on FIG. 12, a semi-conductor diode 44 is inserted between two terminals 39. It is obvious that the position of the diode can be reversed if so desired during manufacturing. Finally, to complete the piston 19, a resistance section, as seen on FIG. 9, line BB, is constructed with a reverse threaded shaft 40 which is imbedded and secured in the resistance material 37. The resistive section 14 is attached to the conical insulator 18 as seen on FIG. 8 or other similar passive elements.

An electrical schematic as seen on FIG. 18 describes the mechanical action that is internally taking place within the switch. A DC power supply represented E connected as seen on FIG. 18 provides power through the resistance and whichever passive element to the load. When the relay coils 8 are energized, the piston 19 makes initial contact with the receiver 3 which allows current to flow through points C and G. Full engagement of the piston 19 in the receiver 3 shorts out the passive elements connected between C and D which is simulated by the closure of switch F. Withdrawal of the piston 19, simulating the opening of the switch F allows the current to flow through points C and G before the circuit is opened. Seen on FIG. 18 are electrical schematics of passive elements that can be substituted between points C and D; thus, providing a means to tailor the time constant of the switch to the time constant of the load.

Having described the invention, what is claimed is:

l. A switch comprising a switching housing consisting of two cylindrical halves exhibiting the electrical prop erties of an insulator sealed together to form a cavity therein, a slidable rotating piston mounted therein, a relay coil surrounding said switch housing, said cavity being disposed at one end to receive said piston and provide sufficient head space therefor and at the other end to have fixedly mounted a spring assembly, said cavity section further comprising a receiver which becomes one contact of the switch, said receiver being reduced at one end and threaded to accept said piston during full engagement, said receiver includes a metallic lining enclosing the inner circumference thereof and extending to the said reduced section of the receiver, said lining having the characteristics of expansion and contraction during normal operation of the said switch, a conductive lining cylindrically disposed about the piston part of said cavity, an insulated strip lining the circumference of the said cavity and placed in between said receiver, lining and piston lining, the said piston lining being cylindrical in shape and lining the internal circumference of said cavity while maintaining contact with said piston on which it slides and rotates, another insulated strip lining the circumference of the said cavity to electrically insulate said piston lining from the spring assembly, an insulated cover providing access to the internal mechanisms of the said switch and additionally housing the said springassembly, said insulated cover being secured to said insulated housing by captive screws placed around the circumference of the cylinder, the said spring assembly consisting of a insulated spring retainer and mounting hardware which secures the spring, the other ends of the said spring being attached to an insulated spring holder mechanically secured to the said piston by appropriate hardware, said piston consisting of a resistance section, insulator section, piston body section and spring holder section, and including a threaded shaft centrally disposed on said piston to secure said sections, said resistance section of the said piston being threaded to mate with said receiver thereby simulating a locking effect which prevents contact bounce, and access terminals welded to said receiver andsaid piston conductor, respectively, to which the load is connected. I

2. A switch according to claim 1 in which said insulator section is constructed in two pieces, one piece being constructed as part of said resistance section and the other piece mounted in said piston, both pieces being attached to opposite ends of said insulator section containing no passive element, so that in operation the piston will insert a resistance in series with the circuit in the normally closed state.

3. A switch according to claim 2 in which said insulator section contains an inductance.

4. A switch according to claim 2 in which said insulator section contains a capacitor.

5. A switch according to claim 2 in which said insula tor section contains a semi-conductor diode.

Claims (5)

1. A switch comprising a switching housing consisting of two cylindrical halves exhibiting the electrical properties of an insulator sealed together to form a cavity therein, a slidable rotating piston mounted therein, a relay coil surrounding said switch housing, said cavity being disposed at one end to receive said piston and provide sufficient head space therefor and at the other end to have fixedly mounted a spring assembly, said cavity section further comprising a receiver which becomes one contact of the switch, said receiver being reduced at one end and threaded to accept said piston during full engagement, said receiver includes a metallic lining enclosing the inner circumference thereof and extending to the said reduced section of the receiver, said lining having the characteristics of expansion and contraction during normal operation of the said switch, a conductive lining cylindrically disposed about the piston part of said cavity, an insulated strip lining the circumference of the said cavity and placed in between said receiver, lining and piston lining, the said piston lining being cylindrical in shape and lining the internal circumference of said cavity while maintaining contact with said piston on which it slides and rotates, another insulated strip lining the circumference of the said caVity to electrically insulate said piston lining from the spring assembly, an insulated cover providing access to the internal mechanisms of the said switch and additionally housing the said spring assembly, said insulated cover being secured to said insulated housing by captive screws placed around the circumference of the cylinder, the said spring assembly consisting of a insulated spring retainer and mounting hardware which secures the spring, the other ends of the said spring being attached to an insulated spring holder mechanically secured to the said piston by appropriate hardware, said piston consisting of a resistance section, insulator section, piston body section and spring holder section, and including a threaded shaft centrally disposed on said piston to secure said sections, said resistance section of the said piston being threaded to mate with said receiver thereby simulating a locking effect which prevents contact bounce, and access terminals welded to said receiver and said piston conductor, respectively, to which the load is connected.

2. A switch according to claim 1 in which said insulator section is constructed in two pieces, one piece being constructed as part of said resistance section and the other piece mounted in said piston, both pieces being attached to opposite ends of said insulator section containing no passive element, so that in operation the piston will insert a resistance in series with the circuit in the normally closed state.

3. A switch according to claim 2 in which said insulator section contains an inductance.

4. A switch according to claim 2 in which said insulator section contains a capacitor.

5. A switch according to claim 2 in which said insulator section contains a semi-conductor diode.

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