US3683301A

US3683301A - Electromagnetically operated solid state timing device

Info

Publication number: US3683301A
Application number: US153982A
Authority: US
Inventors: Robert D Boley; Charles F Meyer; Rudolf H Kiessling; Kenneth L Paape
Original assignee: Square D Co
Current assignee: Schneider Electric USA Inc
Priority date: 1971-06-17
Filing date: 1971-06-17
Publication date: 1972-08-08
Anticipated expiration: 1989-08-08
Also published as: GB1393386A

Abstract

An electromagnetically operated solid state timing device having switching contacts and features which will permit the device to act as a direct replacement for an electromagnetically operated pneumatic timer. The device includes an electromagnet, a permanent magnet latch, a snap switch, solid state circuitry and accessible controls so the device may be easily programmed to actuate the snap switch an adjustable time delay after the electromagnet is energized or deenergized.

Description

United States Patent Boley et a1.

[54] ELECTROMAGNETICALLY OPERATED SOLID STATE TIMING DEVICE UNITED STATES PATENTS [4 1 Aug. 8, 1972 Grass et al. ..335/l70 Traina ..3l7/141 S Primary Examiner-Harold Broome Attorney-Harold J. Rathbun et al.

[57] ABSTRACT An electromagnetically operated solid state timing device having switching contacts and features which will permit the device to act as a direct replacement for an electromagnetically operated pneumatic timer. The device includes an electromagnet, a permanent magnet latch, a snap switch, solid state circuitry and accessible controls so the device may be easily programmed to actuate the snap switch an adjustable time delay after the electromagnet is energized or deenergized.

11 Claims, 11 Drawing Figures Pearse et al. ..317/141 S PAIEIEDAUE 8 #9 2 3,683,301

SHEET 1 [IF 4 .WVENTORS ROBERT D. BOLEY CHARLES F. MEYER RUDOLF H. KIESSLING KENNETHVLPAAPE PATENTEmuc 81912 3.683.301

SHEET 3 [1F 4 i 'EN 101$ ROBERT D. BOLEY CHARLES F. MEYER RUDOLF H. KIES NG KENNETH L. PA E ELECTROMAGNETIC ALLY OPERATED SOLID STATE TIMING DEVICE This invention relates to timing devices and is more particularly concerned with an electromagnetically operated timing device having mechanically operated switching contacts and a solid state timing circuit which will provide a switching output change an adjustable time interval after the device is energized or de-energized.

Timing devices are frequently used in industrial equipment to control an operating interval of a machine function or a process step as well as provide an output signal if an anticipated event fails to occur within a prescribed time interval. One form of a timing device frequently used in industrial installations is known as a pneumatic timer, an example of which is illustrated in U.S. Pat. No. 2,929,898, which was granted to Carl A. Schaefer on Mar. 22, 1960. While timers as shown in the Schaefer patent have been used with success in industry, their accuracy generally is limited when timing prolonged time intervals and their function may be impaired by dusty or highly corrosive environments. Another form of timing unit, which has been more recently introduced, is a device known as a solid state timer which uses solid state circuitry to measure a time interval and solid state components, such as silicon controlled rectifiers to control the opening or closing of an output circuit. While solid state timing devices may be constructed to accurately time prolonged timing periods and to be unaffected by substantially all environments, their use is restricted in that they are usually expensive and Iirnited because of the heat sinks which are required to dissipate the heat generated in the solid state components by currents in the output circuit. The timing device as will be hereinafter described incorporates the advantages of both the pneumatic and solid state timing devices in that it may be constructed at a lower cost than a solid state timing device and will provide accurately timed prolonged timing intervals in dusty environments.

It is an object of the present invention to provide a timing device which will act as a direct replacement for a pneumatic timer and which has the timing accuracy and resistance to adverse environmental conditions of a solid state timing device.

A further object is to provide a timing device which includes an electromagnet and a solid state timing circuit that may be readily converted to provide a time delay after energization or a time delay after de-energization mode of operation.

An additional object is to provide a timing device which includes an electromagnet, a solid state timing circuit, a snap switch, which controls the output of the device, and a permanent magnet latch which has its actuation controlled by the electromagnet and its release controlled by the timing circuit.

Another object is to provide a timing device which includes an electromagnet, a solid state timing circuit, a permanent magnet latch, which has its actuation controlled by the electromagnet and its release controlled by the timing circuit, a snap switch, which controls the output circuits of the device and has its actuation controlled by the permanent magnet latch, a means for manually releasing the latch, a means for programming the device to provide two different timing periods and two different modes of operation and a structure which will permit additional switches to be added to the device.

Further objects and features of the invention will be readily apparent to those skilled in the art from the following specification and from the appended drawings illustrating a preferred embodiment, in which:

FIG. 1 is a front plan view of a timing device incorporating the features of the present invention;

FIG. 2 is a side view of the device in FIG. 1 with the portions of the device shown in cross section as taken along a line indicated by an arrow 2 in FIG. 1, with a permanent magnet latch portion of the device in a released position;

FIG. 3 is a side view of an upper portion of the device in FIG. 1 with the portions of the device shown in cross section as taken along a line indicated by an arrow 3 in FIG. 1 and with the permanent magnet latch in a latched position;

FIGS. 4 and 5 respectively are side and top views of the device in FIG. 1 with a housing for the solid state components of the device removed;

FIG. 6 is an exploded view showing in perspective certain components of the permanent latch in FIGS. 2 and 3;

FIG. 7 is a perspective view of an actuator for the latch in FIGS. 2 and 3;

FIG. 8 is a cross-sectional view taken along line 88 in FIG. 1',

FIG. 9 is a cross-sectional view taken along line 99 in FIG. 1;

FIG. 10 schematically shows a timing circuit as used in the device in FIG. 1; and

FIG. 11 is an enlarged perspective view showing a portion of a range and mode selector parts as used in the device in FIG. 1.

For convenience in description, the timing device is described herein as oriented when the base of the device is mounted on a front wall of a vertical panel with the enclosure containing the timing circuit at the upper end of the device, the parts of the device being described in relation to this position. Accordingly, the terms front and rear, upper and lower, top and bottom, vertical and horizontal and the like are not absolute but merelyv define more readily the relative positions of portions of the parts and their relative positions to each other when the device is mounted on the panel.

A timing device 10, shown in the drawings, includes a metal base 12, an electromagnet 14, an actuator 16, an electric switch 18, a permanent magnet latch assembly 20 and an enclosure 22 for printed circuit board 24 having a solid state timing circuit mounted thereon. The base 12 and the electromagnet 14 preferably are of the form fully disclosed in U.S. Pat. No. 3,501,723, which was granted on Mar. 17, 1970 to Kenneth J. Marien. As disclosed in the Marien patent, the base 12 positions the electromagnet 14 and acts as a guide for the actuator 16. The actuator 16 basically has the form of the carrier for the movable contacts in the device disclosed in the Marien patent with the supports for the movable contacts omitted and a cam member 25 for controlling the actuation of the switch 18 added thereto, as will be later'described. The electromagnet 14 includes a stationary magnet part 26, a magnet coil 28 and an armature 30 which is connected to the actuator 16 by a pin 32 so the armature 30 and the actuator 16 move together as a unit. The coil 28 is provided with a pair of windings, not shown, which are magnetically coupled together to act as the windings of a transformer in a manner well known to those skilled in the art. One of the pair of windings within the coil 28 has its opposite ends connected to a pair of input terminals 34 and is wound to induce a magnetic flux in the stationary magnet part 26 and the annature 30 in a direction which will cause the armature 30 to be attracted upwardly toward the stationary magnet part 26 when the coil winding connected to the input terminals 34 is energized by an appropriate alternating current. The other of the pair of windings within the coil 28 has its opposite ends connected to a pair of output terminals 36 and acts as a secondary winding so that an output potential appears across the terminals 36 whenever the coil connected to the input terminals 34 is energized.

The base 12 has a pair of horizontally spaced ledges formed thereon, one of which is shown as a ledge 38 in FIG. 3. A support member 40 is secured on the upper surfaces of the ledges 38 by a pair of screws 42 shown in FIG. 5. The support member 40 includes an overhanging portion 44, a depending portion 46, an upwardly projecting portion 48 and a pair of spaced ledges 50. The overhanging portion 44 provides a seat for one end of a compression spring 52 that has its other end resting on an upper surface of the actuator 16 so as to constantly urge the actuator 16 and the armature 30 downwardly, as in FIG. 2, to a deactivated position wherein the pole faces of the armature 30 are spaced from the pole faces of the stationary magnet part 26 when the coil 28 is de-energized. The downward movement of the actuator 16 and the armature 30 is limited by the engagement between a lower surface, now shown, on the portion of the actuator 16 that positions the cam 25 and an upper surface on a boss-like projection 56 that extends forwardly on the base 12.

The upwardly projecting portion 48 and the depending portion 46 respectively extend upwardly and downwardly from the front marginal edge of the overhanging portion 44. An opening 60, shown in FIG. 5, is provided in the overhanging portion 44 by the material that is removed to provide the upwardly extending projecting portion 48 when the metal support member 40 is formed. The depending portion 46 has a centrally located opening 62 therein and a notch 64 extending along its lower marginal edge. The ledges 50 extend from opposite ends of the notch 64 along the lower marginal edge of the depending portion 46 to present a pair of upwardly facing surfaces 66 whereon a pair of spaced feet 68 on an operating lever 70 are pivotally and slidably positioned. The support member 40 additionally is mounted on the base by a pair of spaced hooks 72 which extend at opposite ends of the rear marginal edge of the overhanging portion 44 andthe hook on portions of the base 12. The pair of screws 42 extend through openings in the overhanging portion 44 into threaded members, not shown, which are positioned in the material forming the pair of spaced ledges 38.

The permanent magnet releasable latch assembly 20, which is positioned on the projecting portion 48, in-

. cludes a permanent magnet 76, a magnet coil 78, a

mounting post 80, a mounting screw 82, a pole piece 84, a pole piece 85, and an armature86. The post 80 has a cylindrical shape and extends through a central opening in the magnet coil 78. One end of the post 80 is secured to the projecting portion 48 and the other end of the post 80 has a threaded bore which receives the screw 82. The permanent magnet 76 has a cylindrical shape and has the

pole pieces

84 and 85 respectively secured at its opposite ends. The magnet 76 is magnetized in a direction so that the

pole pieces

84 and 85, which are respectively L-shaped and disc-shaped, are opposite in magnet polarity. The screw 82 extends through suitable openings in the

pole pieces

84 and 85 and the magnet 76 and is threaded into the post 80. The screw 82 maintains the

pole pieces

84 and 85, the magnet 76 and the coil 78 assembled on the projecting portion 48 with the pole piece 85 positioned adjacent the magnet coil 78 and having portions engaging the bore end of the post 80. The L-shaped pole piece 84 has a leg portion 88 secured to the permanent magnet 76 and a leg portion 90 extending to present an edge which acts as a magnet pole face 92 that is spaced from an upper edge 94 of the projection portion 48. When the permanent magnet 76, the magnet coil 78, and the pole piece 84 are thus mounted on the post 80, the pole face 92 will have a magnet polarity that is opposite to the polarity of the projection portion 48.

The armature 86 is pivoted on the projecting portion 48 by a pair of ears 96. The ears 96 extend from opposite sides of the armature 86 and are received in notches in the opposite vertical side edges of the projecting portion 48 so that a portion 98 on the armature 86 is engageable with the pole face 92. The armature 86 also has a hook 100 extending rearwardly which provides a surface that is spaced from the rear surface of the armature 86.

The cam member 25 is secured on an upper surface of the actuator 16 and, as shown in FIG. 7, has a pair of cam surfaces 104 and 106 extending in opposite directions from an axis indicated by a numeral 108. The cam member 25 is mounted on the actuator 16 to have the axis 108 extend along a vertical center of the actuator 16 and when so mounted, the cam surface 104 will face forwardly and upwardly and the cam surface 106 will face forwardly and downwardly from a front edge of the actuator 16.

The operating lever 70 has a pair of spaced feet 68 resting on the surfaces 66 and a free end 110 at an end opposite the feet 68 received within the hook 100 so a lost motion connection exists between the armature 86 and the operating lever 70. Suitably located in an intermediate surface portion of the lever so as to be engaged by either of the cam surfaces 104 or 106, in a manner to be later described, is a cam 112 having the shape of a j hip roof with its ridge extending horizontally between an inclined downwardly facing surface 113 and an inclined upwardly facing surface 115. Extending forwardly from the body portion of the lever is a projection 114 which extends through the notch 64 so at least a portion of the projection 114 is accessible from the external front of the timing device 10. The projection 114 has a horizontal length less than the horizontal length of the notch 64 and is arranged so the projection 114 is positioned adjacent the upper surface of the notch 64 while the free edges of the feet 68 are resting on the surfaces 66. Also extending downwardly so as to rest against a front surface portion on the base 12 are a pair of ears 116. The ears 116 prevent the displacement of the lower portion of the lever 70 in a rearwardly direction while the feet 68 prevent the displacement in a forwardly direction. The lever 70 also has an elongated slot 118 extending horizontally in the area of the lever 70 immediately beneath the cam 112. The slot receives a finger 120 on a switch operating lever 122. The free end 110, the cam 112, the projection 114, the ears 116, the slot 118, as well as the feet 68, are arranged so the lever 70 may be moved horizontally between two positions on the device by a manual force exerted on the part 114. For convenience, the letters TDE may be applied to the front surface of the foot 68 on the left side of the lever 70 and the letters TTD on the front surface of the foot on the right side of the lever 70, as in FIG. 6. When the lever is moved to the left to the position shown in FIG. 1, the left edge of the part 114 engages a tooth 124 extending downwardly from the left end of the upper edge of the notch 64 and the cam surface 113 will be aligned so as to be engaged by the cam surface 184 on the cam 25 shown in FIG. 7. When the lever 70 is moved to the right, the right side edge of the part 114 will engage a tooth 126 extending downwardly from the left end of the upper edge of the notch 64 and the cam surface 115 will be aligned so as to be engaged by the cam surface 106. When the lever 70 is positioned in either of the two positions, the free end 110 will be positioned so as to be received by the hook 100 while the length of the slot 118 and the width of the finger 121 is arranged to permit the horizontal movement of the lever 70 to its two extreme positions without moving the switch operating lever 122. The lever 70 is maintained in either of its two positions by a screw 128 which is threaded into a portion on the base 12 and when loosened will permit a finger portion 129 on the lever 70 to pass under the head of the screw 128 so the lever may be moved to either of its two positions. The head of the screw 128, when the screw 128 is tightened in the base, will engage the side edges of the finger 129 to prevent movement of the lever 70 from its adjusted position.

The switch operator lever assembly includes the lever 122 and a means for adjusting the operating distance between the lever 122 and an end of a horizontally movable operating plunger 130 of the switch 18. The adjustment means, which is included to compensate for deviations in manufacturing tolerances of the device 10 and the operating characteristics of the switch 18, includes a cam wheel 132, a pin 134 and a friction washer 136 which are mounted on a front face of the lever 122 so that a tapered surface 138 on the cam wheel 132 engages the free end of the plunger 130 while the friction washer maintains the cam wheel against rotation on the front face of the lever 122. The lever 122 is positioned in the device 10 by a pair of ears 140 which extend forwardly so as to be received in the space between the

teeth

124 and 126 and the respective left and right ends of the notch 64 and the finger 120 which extends through the slot 118. The lever 122 also has a free end 142 which rests against a portion of the lever 70 located above the cam 1 12.

The electric switch 18, as illustrated, is of the conventional commercially available snap acting type and,

as shown, is a single pole double throw version of a double pole double throw snap switch disclosed in US. Pat. No. 3,200,227, which was granted to Walter C. Karch on Aug. 10, 1965. The switch 18 is mounted on the front surface of the depending portion 46 so the terminals 144 and 146 of the switch 18 are readily accessible from the front side of the timing device 10 and the plunger extends through the opening 62 to be engaged by the tapered surface 138.

The plunger 130 is spring biased outwardly of the housing for the switch 18 toward a de-activated position where it carries the movable contacts within the switch to complete a circuit between the pair of terminals 144. When the plunger 130 is moved inwardly into the switch housing to an activated position, it causes the movable contacts within the switch to move with a snap action and complete a circuit through the pair of terminals 146.

The enclosure 22 for the solid state timing circuit on the printed circuit board 24 is preferably formed of a suitable molded insulating material to have an internal cavity 148 with an open bottom end. The enclosure 22 is maintained in its position at the upper portion of the device 10 by a screw 149 which is received in a threaded opening in the overhanging portion 44. The printed circuit board 24, which substantially closes the open bottom end of the enclosure 22, has the circuit components illustrated by FIG. 10 positioned thereon. The printed circuit board 24 is secured on the bottom end of the housing 22 by a pair of screws 152 which extend through openings in the board into suitably located portions of the side walls of the enclosure 22. The board 24 is provided with a suitable sized opening 154 along its front end so that the permanent magnet latch assembly 20 as well as the lever 70 and the annature 86 may extend into the cavity 148.

The components and printed circuits, which are carried by the circuit board 150 so as to be disposed within the cavity 5 are schematically illustrated in FIG. 10 and operate as follows.

The pair of output terminals 36 from the coil 28 are shown in FIG. 10 as connected to a pair of input terminals of a full wave rectifying diode bridge 156. The bridge 156 has a pair of output terminals 158 and 160 and diodes poled so the terminal 158 has a positive polarity relative to the terminal 160 when the terminals 36 are energized. The terminal 160 is directly connected to a common or ground lead 162 for the circuit. The terminal 158 is connected through a current limiting resistor R1 to a lead 164 which in turn is connected through a dirxle D1 to a lead 166. The diode D1 is poled to conduct current from the lead 164 to the lead 166 and block current flow from the lead 166 to the lead 164. A Zener diode D2, connected between the

leads

162 and 164, regulates the potential between the leads 164 and 166 and the lead 162. A capacitor C1 is connected between the

leads

162 and 164 and a capacitor C2 is connected between the leads 162 and 166. A transistor T1 has an emitter directly connected to the lead 162, a collector connected through a collector load resistor R2 to the lead 166 and a base connected through a resistor R3 to the lead 162. The base of the transistor T1 is also connected through a resistor R4 to the side of the capacitor C1 that is connected to the lead 164. A transistor T2 has an emitter directly connected to the lead 162, a collector connected through a collector load resistor R to a junction 168, and a base connected through a resistor R6 to the lead 162 and through a resistor R7 to a movable member 170 of a programmable selector that'has a pair of stationary members respectively designated as TDD and TDE. The stationary member TDD is connected to the lead 164 and the stationary contact TDE is connected to the collector of the transistor T1. The junction 168 is connected through a resistive timing circuit consisting of a resistor R8, which acts as a minimum resistance, and potentiometer type resistor R9 to the lead 166. The junction 168 is also connected through a capacitor C3 to the lead 162 and through a capacitor C4 to a member 172 which is arranged to engage a member H1 and connect the capacitor C4 to the lead 162; A programmable unijunction transistor PUT has an anode A, an anode-gate G and a cathode C electrode. The anode A is connected to the junction 168. The gate G of the transistor PUT is connected to a junction 174 that is connected through a resistor R10 to the lead 166 and a resistor R11 to the lead 162. The cathode C of the transistor PUT is connected through a gate resistor R12 to the gate G of a silicon controlled rectifier SCR. The rectifier SCR has a cathode directly connected to the lead 162 and an anode connected through the magnet coil 78 in the magnet latch assembly to the lead 166. The capacitors C5, C6, and C7 are respectively connected between the lead 162 and the junction 174, the gate G of the rectifier SCR and the anode of the rectifier SCR. The capacitors C5, C6 and C7 act as noise filters. A resistor R13, connected between the cathode of the unijunction transistor PUT and the lead 162, acts as a load resistor.

The programmable unijunction transistor PUT, as used in the above described circuit, is designated and sold by the General Electric Company as a D13T2 three terminal planar passivated PNPN device. The D13T2 device and its characteristics is described in an application note 90.70, 11/67 issued by the Semiconductor Products Department, Syracuse, New York, U.S.A., entitled The D13T A- Programmable Unijunction Transistor, by W. R. Spofiord, Jr., Application Engineering Syracuse, New York.

The circuit in FIG. 9 will cause the magnet coil 78 to be energized an adjustable time delay after the terminals 36 are de-energized by positioning the movable member 170 in a position where it makes contact with the stationary member TDD. If the circuit is to operate with a reduced time delay, the member 172 is positioned to be out of engagement with the member HI and thus interrupt a circuit between the capacitor C4 and the lead 162. The alternating current potential which appears at the terminals 36 when the coil terminals 34 are energized, is rectified by the bridge rectifier 156 and impressed as a direct current potential between the leads 164 and 166 and the lead 162. The direct current potential, which exists as a positive voltage on the leads 164 and 166, charges the capacitors Cl and C2 and supplies a positive bias to the base of the transistor T2 from the lead 164 through a circuit that includes the movable member 170 and the stationary member TDD and the resistor R7 so that the transistor T2 is biased into saturation. The saturated transistor T2 discharges and maintains the capacitor C3 discharged so that the programmable unijunction transistor PUT and the rectifier SCR remain non-conducting. The removal of the energizing potential at the terminals 36, which occurs when the coil 28 is de-energized, causes the charge on the capacitor C1 to rapidly dissipate and the positive bias on the base of the transistor T2 to be removed so that the transistor T2 switches to a non-conducting state. The non-conducting transistor T2 permits the capacitor C3 to charge through the resistive timing circuit that comprises the resistors R8 and R9. The charge energy for the capacitor C3 is initially furnished by the capacitor C1 and subsequently by the capacitor C2 which were charged when the magnet coil 28 was energized. The capacitors Cl and C2 are selected so that capacitance of the capacitor C2 greatly exceeds the capacitance of the capacitor C1. For example: the capacitor C1 may have a capacitance of 1.5 mfd., whereas the capacitor C2 has a capacitance of 1,900 mfd. When the charge on the capacitor C3 reaches a predetermined value, as dictated by the intrinsic stand-0E ratio of the programmable unijunction transistor PUT, the transistor PUT switches to its conductive state and supplies a sharp voltage pulse through its anode to cathode electrodes to the gate and cathode of the rectifier SCR. The rectifier SCR is switched to a conductive state by the voltage pulse at its gate G and provides a discharge path for the charge remaining on the capacitor C2 through the magnet coil winding 78. The magnet coil 78 is energized by the current flow provided by the discharging capacitor C2 and is wound to cause the magnet latch assembly 20 to be released when the magnet coil 78 is energized. Thus the magnet latch assembly 20 is released a predetermined time interval after the terminals 36 are de-energized.

The circuit is programmed to operate with a time delay after the terminals 36 are initially energized by positioning the movable member so its engages the stationary member TDE. When the terminals 36 are initially energized with an alternating current, the capacitors Cl and C2 willbe charged by the rectified direct current output of the bridge rectifier 156. The capacitor C1 has a small capacitance andtherefore the appearance of the potential at the terminals 36 will cause the transistor T1 to be biased into its conductive state and a potential to appear at the stationary member TDE which is substantially equal to the potential of the lead 162. Thus the transistor T2 will remain desaturated. The desaturated transistor T2 will permit the capacitor C3 to charge at a rate determined by its resistive timing circuit, including the resistor R9. A predetermined time interval after the potential at the terminals 36 initially appears, the charge on the capacitor C3 will cause the unijunction transistor PUT to switch to a conductive state and thereby switch the rectifier SCR into a conductive state so that the magnet coil 78 is energized to cause the release of the magnet latch assembly 20 by the current from the lead 166 that flows through the conducting rectifier SCR. The circuit, including the capacitor C4 and the movable member 172, is included to increase the time of operation of the circuit. When the movable member 172 is positioned to complete the circuit through the stationary member 111 to the lead 162, the capacitor C4 is connected in parallel with the capacitor C3 so as to increase the capacitance of the timing circuit and therefore the time interval required for the capacitors C3 and C4 to be charged to a value which will exceed the intrinsic stand-off ratio of the programable unijunction transistor PUT. In this connection the value of the potential on the capacitors C3 and C4 required to switch the programmable unijunction transistor PUT into a conductive state is controlled by the resistive values of the resistors R9 and R10 in a manner described in the application note by W. R. Spofford, supra. The resistor R1 is included in the circuit to limit the current flow through the circuit from the bridge rectifier 156 through the magnet coil 78 and the rectifier SCR when the rectifier SCR switches to a conductive state.

The circuit will not provide a false output timing signal in event the circuit is reset during the timing interval when the circuit is programmed to operate in either the time delay after energization or de-energization modes. The positioning of the movable member 170 on the stationary member TDD will program the circuit to provide an output a timed interval after the input to the terminals 36 is removed. The removal of the input to the terminals 36 causes the transistor T2 to desaturate and the capacitor C3 to be charged through the resistor R9 by the charge across the capacitor C2. A momentary input to the terminals 36 during the timing period, which is sufficient to upset the calibration of the circuit, will cause the transistor T2 to momentarily saturate and discharge the capacitor C3. Thus the subsequent removal of the momentary input to the terminals 36 will re-initiate the timing period with the capacitor C3 in a discharged state, so that a momentary input during the timing interval will merely reset the timing circuit and not cause a false release of the magnet latch assembly 20. The timing circuit is programmed to provided a timed output signal after the circuit is energized when the movable member 170 is positioned on the stationary contact TDE. A momentary interruption of the input to the terminals 36 during the timing interval when the switching contact 170 is positioned on the contact TDE will cause the capacitor C1 to discharge and the transistor T1 to desaturate. The charge previously impressed on the capacitor C2 will cause the transistor T2 to saturate and discharge the previously applied timing charge on the capacitor C3. Thus when the input signal is restored to the terminals 36, the timing circuit will be reset and a full timing interval will be required before the timing circuit will supply an output signal which will cause the magnet latch assembly 20 to be released.

Located at the upper left front of the enclosure 22 is a range and mode selector 176 which is provided to program the operation of the circuit shown in FIG. 10. To accommodate the selector 176, the upper left portion of the enclosure 22 is provided with a rectangularly shaped opening, or window, 178, wherein an insulating board 180 that is formed of relatively thin and stiff material is positioned. The insulating board 180 has a pair of vertically extending

slots

182 and 184 which are parallel to each other and are respectively designated as Range and Mode, in FIG. 1. Secured on the opposite ends of the slot 182 is the pair of members respectively designated as HI and LO, which are vertically spaced from each other in the slot 182 and correspond to the stationary members HI and L0, in FIG. 10. Similarly secured on the opposite ends of the slot 184 respectively are members TDD and TDE which are vertically spaced from each other in slot 1 and correspond to the stationary members TDD and TDE in FIG. 10. The members HI, LO, TDD and TDE are identical and are formed of a relatively thin metal piece to provide a receptacle at the associated end of the slot where they are located. Movable in the slot 182, and selectively into electrical engagement with the member HI or the member L0, is a metal slider 201 and a screw 203 which provide the function and correspond to the movable member 172 in FIG. 10. Similarly movable in the slot 184 and selectively into electrical engagement with the member TDD or the member TDE, is a metal slider 202 and a screw 204 which are identical with the slider 201 and the screw 203 and provide the function and correspond to the movable member in FIG. 10. The member H1 is shown in detail in FIG. 11, it being understood that the members LO, TDD and TDE are similarly shaped and are positioned in their associated slots in the manner illustrated in FIG. 1. The member HI is formed as a U-shaped channel to have a pair of

legs

186 and 188 extending from a bight portion 190. The edges of the

legs

186 and 188 are positioned on the front surface of the board so that the bight portion 190 is spaced from the front surface of the board 180. The bight portion 190 has an open ended slot 192 formed therein that extends from the lower marginal edge of the bight portion 190. Each of the

legs

186 and 188 has a finger 194 extending rearwardly through a suitable opening in the board 180. As illustrated by FIG. 11, the finger 194 on the leg 188 has its end bent over the rear surface of the board 180 to maintain the member HI on the front surface of the board 180. The corresponding finger on the leg 186 is similarly bent to maintain the leg 186 and the member HI on the front surface of the board 180. Extending from an upper marginal edge 196 of the bight portion 190, and rearwardly through the slot 182 in a manner shown in FIG. 8, is a finger 198 which, through a suitable lead 200, is electrically connected to a portion of the circuit on the printed circuit board 24 that corresponds to the lead 162 in FIG. 10. The slider 201 and the screw 203 are shown in detail in FIG. 11, it being understood that as the

sliders

201 and 202 are identical, and the screws 203 and 204 are identical, the description of the shape and function of the slider 201 and the screw 203 in FIG. 11 will provide a description of the shape and function of the slider 202 and the screw 204. The slider 201 is formed of a relatively thin rectangularly shaped metal part that has a centrally located threaded opening which receives the screw 203. The slider 201 has a width slightly less than the distance between the

legs

186 and 188 and a thickness which will permit it to be received between the front surface of the board 180 and the rear surface of the bight portion 190. The slider 201 is maintained in an assembled position with the member HI by loosening the screw 203 and moving the slider 201 upwardly between the

legs

186 and 188 to a position where the screw 203 is positioned adjacent the top end of the slot 192. The slider is maintained in assembled position with the member HI when the screw 203 is tightened so that portions on the rear surface of its head are pressed against portions on the front surface of the bight portion 190, while portions on the front surface of the slider 201 are pressed against portions on the rear surface on the .bight portion 190. The slider 201 is provided with a finger 206 that extends through the slot 182 in a manner shown in FIG. 8, so that an electrical conductor 208, which is secured thereto, will connect the slider 201 to the capacitor C4 shown in FIG. 10.

The upper left hand corner of the enclosure 22 is provided with a suitable opening which receives a support 210 for a conventional potentiometer resistor 212 that has an adjusting screw 214 accessible from the front side of the enclosure. The potentiometer resistor 212 corresponds to the resistor R9 in FIG. 10 and provides a convenient means for adjusting the operation of the circuit in FIG. 10 from the external front side of the device 10. If desired, the adjusting screw 214 may be concealed by a suitable cover 216, shown in FIG. 9, after the resistor 212 has been adjusted.

As shown in FIGS. 2 and 4, the portion 98 on the armature 86 extends upwardly beyond pole face 92 and the armature 86 is pivotally movable from a position shown in FIG. 2 where the portion 98 is spaced from the pole face 92 to a position shown in FIG. 3 where the portion 98 engages the pole face 92. The device 10 is provided with a means which may be used to manually move the armature 86 from the position shown in FIG. 4 to the position shown in FIG. 2 and a means which will indicate whether the armature is at its latched position shown in FIG. 4, or at its released position shown in FIG. 2.

As most clearly shown in FIGS. 1 and 2, the manual release means includes a plunger 218 that has a portion 222 extending through an opening in the front wall of the enclosure 22 and a portion 224 that is movable along the bottom surface of the top wall of the enclosure 22. The portion 224 has a rear end 226 aligned with the portion 98 to move the armature from the position shown in FIG. 4 to the position shown in FIG. 2 when the plunger is moved rearwardly in the enclosure 22 by a manual force that is applied to the portion 222 from the external front side of the enclosure 22. The plunger is positioned and guided during its movements in the enclosure 22 by portions of the opening in the front wall of the enclosure 22 through which the portion 222 extends and a rectangularly shaped boss 228 that extends downwardly from the bottom surface of the top wall of the enclosure 22. The portion 224 is slotted to receive the boss 228 and position the rear end 226 at the rear surface side of the boss 228. The portion 224 is maintained on the boss by a metal plate 230 and a screw 232 which is threaded into the boss 228 and positions the guide plate on the bottom end of the boss 228. A compression spring 234 having its opposite ends positioned on a front side of the boss 228 and a rear end 236 of the slot within the plunger 218 constantly biases the plunger forwardly to an inoperative position in the enclosure 22.

The means for visually indicating when the armature 86 is at its latched and at its released position includes a lever 238 which is shown in FIG. 3. The lever 238 is mounted on a fulcrum 240 so an arm portion 242 on the lever 238 extends rearwardly of the fulcrum 240 and an arm portion 244 on the lever 238 extends forwardly of the fulcrum 240. The arm portions 242 and 244 are arranged to exert lever movements about the fulcrum 240 to rotate the lever 238 in a clockwise direction in FIG. 3 when no external forces are applied on the portion 242. The arm portion 244 has a flag portion 246 on its free end. The flag portion 246 is movable in a slot 248 in the front wall of the enclosure 22 so as to be visible from the front exterior side of the enclosure 22. The arm portion 242 extends so that it is engaged by a free end 250 on the armature 86 and is shaped so the lever 238 will be free to rotate clockwise to a position wherein the upper end of the flag portion 246 engages an upper end 252 of the slot 248 when the armature 86 is in its released position, shown in FIG. 2, and the lever 238 will be rotated counterclockwise to a position where the lower side of the flag portion 246 is positioned at the lower end 254 of the slot 248 when the armature 86 is in its latched position as shown in FIG. 3. Thus the position of the flag portion 246 in the slot 248 will provide a visual indication of the operative condition of the armature 86.

The timing device 10 may be programmed to time a short timing interval by positioning the slider 201 and the screw 203 at the lower end of the slot 182 and tightening the screw 203 so that the slider 201 is pressed into engagement with the member L0 to complete an electric circuit between the slider 201 and the member L0. The device 10 is programmed to time a longer timing period by positioning the slider 201 and the screw 203 at the upper end of the slot 182 and tightening the screw 203 to press the slider 201 into engagement with the member HI and thereby complete an electrical circuit between the slider 201 and the member H1. The time interval of either the short or the long time periods may be varied by adjusting the potentiometer 212.

The timing device 10 may be adjusted to delay the actuation of the snap switch 18 after the electromagnet 14 is energized or de-energized by the proper adjustment of the position of the lever 70 and the position of the slider 202 in the mode and range selector 176. The device 10 is programmed to actuate the snap switch 18 a predetermined interval after the electromagnet 14 is de-energized, hereinafter called the TDD mode, by positioning the slider 202 and the screw 204 at the upper end of the slot 184 so that the slider 202 electrically engages the member TDD when the screw 204 is tightened. Thus the circuit on the printed circuit board 24 as illustrated in FIG. 10 will be programmed to operate with the member 170 in FIG. 10 positioned on the member TDD. The lever 70 is programmed to operate in the TDD mode by positioning the lever 70 as shown in FIG. 1, wherein the legend TDD on the foot 68 on the right side of the lever 70 will be visible. The operating lever 70 is maintained in its adjusted TDD mode position when the screw 128 is tightened. When the lever 70 is at its TDD mode position and the electromagnet 14 is de-energized, the cam surface 113 on the operating lever 70 will be aligned with the cam sur face 104 on the cam member 25 which is carried by the actuator 16, as shown in FIG. 2. The cam surface 104 is shaped so that when the electromagnet 14 is de-energized, the surface 113 will be adjacent the cam surface 104 and permit the operating lever 70 as well the armature 86 to be pivoted rearwardly about their respective pivots which include the feet 68 on the lever 70 and the ears 96 on the armature 86 to the positions shown in FIG. 2.

The switch operating lever 122 has portions 254 pivoted on portions 256 on the operating lever 70 and is connected to be moved with the lever 70 through the connection provided by the finger 120 and the slot 118. Thus when the lever 70 moves rearwardly to the position shown in FIG. 2, the switch operating lever 122 will move rearwardly to a position which will permit the plunger 130 on the snap switch 18 to move to its deactivated position and actuate the switch contacts to complete a circuit through the terminals 144.

The timing device is energized when a suitable alternating current potential, applied to the input ter' minals 34, from an alternating current source, not shown, causes the magnet coil 28 to be energized. The coil 28, when energized, causes the armature 30 to move upwardly from its deactuated position into engagement with the stationary magnet 26 and the output terminals 36 to supply an alternating current potential through a pair of leads 258 to terminals on the printed circuit board which correspond to the terminals 36 in FIG. 10 so that the circuit in FIG. 10 is energized in a manner previously described. The upward movement of the armature 30 causes the actuator 16 and the cam 25 to move upwardly to their actuated positions. During the upward movement of the cam 25 to its actuated position, the cam surface 104 through its engagement with the downwardly facing surface 113 causes the lever 70 to rotate counterclockwise to its actuated position, as shown in FIG. 3. The movement of the lever 70 to its actuated position also causes the armature 86 to rotatecounterclockwise to a position wherein its portion 98 engages the pole face 92 and the lever 122 to rotate counterclockwise to the position shown in FIG. 3. The counterclockwise movement of the lever 122 causes the plunger 130 of the snap switch 18 to move inwardly into the switch housing to its actuated position and actuate the contacts within the switch 18 to complete a circuit between the terminals 146. The armature 30, the actuator 16, the cam 102, the lever 70, the lever 122, the armature 86 and the plunger 130 will remain in the positions described as long as the coil 28 is energized.

The timing device 10 is de-energized when the alternating current potential supplied to its input terminals 34 is removed so that the weight of the armature 30, as well as the force supplied by the spring 52, causes the armature 30 and the actuator 16 to move downwardly to their de-actuated positions. The movement of the actuator 16 to its de-actuated position causes the cam 25 to move downwardly and the cam surface 104 to move out of engagement with the downwardly facing surface 113. The operating lever 70, however, is prevented from following the movement of the cam 25 by the magnet latch assembly as the flux generated by the permanent magnet 76 through the pole face 92 causes the armature 86 to be maintained in its engagement with the pole face 92. The armature 86 is operatively connected to the lever 70 by the hook 100 so that the operating lever 70 and the lever 122 are maintained in a position which will cause the plunger 130 of the snap switch 18 to be maintained in its actuated position and complete a circuit through the terminals 146 in spite of the fact that the magnet coil 28 of the timing device 10 is de-energized.

The magnet coil 78 is energized a predetermined interval after the coil 28 is de-energized by the circuit on the printed circuit board 24 in a manner described in connection with FIG. 10. The coil 78 is wound and is energized by current flow from the circuit shown in FIG. 10 so its output flux opposes the flux output of the permanent magnet 76 when the coil 78 is energized. Thus when the coil 78 is energized, the fluxes of the permanent magnet 76 and the magnet coil 78 oppose each other so that the force provided by the spring bias on the plunger 130 causes the plunger 130 to move to its de-actuated position and the lever 122, the lever 70, as well as the armature 86, to move clockwise about their respective pivots to their de-actuated positions.

The device 10 is programmed to actuate the snap switch 18 a predetermined interval after the electromagnet 14 is energized, hereinafter called the TDE mode, by positioning the slider 202 and the screw 204 at the lower end of the slot 184 so that the slider 202 electrically engages the member TDE when the screw 204 is tightened. Thus the circuit on the printed circuit board 24 will be programmed to operate with the member 170, in FIG. 10, positioned on the member TDE. The lever is programmed to operate in the TDE mode by moving the lever 70 to the right in the notch 64 to a position wherein the legend TDE on the foot 68 on the left side of the lever 70 will be visible. The operating lever 70 is maintained in its adjusted TDE mode position when the screw 128 is tightened. When the lever 70 is at its TDE mode position and the electromagnet 14 is de-energized, the cam surface on the operating lever 70 will be aligned with the cam surface 106 on the cam member 25. The cam surface 106 is shaped so that when the electromagnet 14 is deenergized, the upper edge on the cam surface 106 will engage the portion of the cam surface 115 that is ad jacent the ridge that separates the cam surfaces 113 and 115 so that the operating lever 70, the lever 122 and the armature 86 are moved forwardly about their respective pivots to the position shown in FIG. 3. The lever 122 will cause the plunger on the snap switch 18 to be in its actuated position and the switch contacts to complete a circuit through the terminals 146.

The energization of the coil 28, when the timing device 10 is programmed in the TDE mode, causes the output terminals 36 to supply an alternating current potential through the leads 258 to the terminals on the printed circuit board which correspond to the terminals 36 in FIG. 10 so that the circuit in FIG. 10 is energized to operate in the TDE mode, as previously described. The energized coil 28 also causes the armature 30, the actuator 16, and the cam 25 to move upwardly to their energized position. The upward movement of the cam 25 causes the cam surface 106 to move out of engagement with the upwardly facing surface 115. The operating lever 70, however, is prevented from following the movement of the cam 25 by the magnetic latch assembly 20 because the circuit in FIG. 10 is now programmed to delay the energization of the magnet coil 78 for a timed interval after the terminals 36 are energized. The armature 86, which is maintained in its engaged position with the pole face 92, is operatively connected to the lever 70 by the hook 100 so that the operating lever 70 and the lever 122 are maintained in position which will cause the plunger 130 of the snap switch 18 to be maintained in its actuated position in coil 78 causes the magnet latch assembly to be released, as previously described. The release of the magnet latch assembly 20 permits the armature 86, the lever 70, and the lever 122 to be moved to their deactuated positions as the force provided by the spring bias on the plunger 130 causes the plunger 130 to move to its de-actuated position and the contacts of the switch 18 to move to complete a circuit through the terminals 144.

The subsequent de-energization of the timing device when the timing device 18 is programmed to operate in the TDE mode will cause the armature 30 and the actuator 16 to move downwardly to their de-actuated positions. The downward movement of the actuator 16 to its de-actuated position causes the cam to move downwardly and the cam surface 106 to move into engagement with the upwardly facing surface 115 and the lever 70 to rotate counterclockwise to the position shown in FIG. 3. The counterclockwise movement of 25 the lever 70 also causes the armature 86 and the lever 122' to rotate counterclockwise to a position where the armature 86 is maintained in its latched position because of its engagement with the pole face 92. The counterclockwise movement of the lever 122 causes the plunger 130 of the snap switch 18 to move to its actuated position and a circuit to be completed between terminals 146. Thus the timing device 10 is conditioned to time a subsequent time period and delay the operation of thesnap switch for a predetermined time interval after the timing device 10 is energized.

While not specifically shown, it is clearly apparent that additional switches, not shown, may be positioned adjacent either the right or left side of the timing device 10 to be actuated instantaneously upon the operation of the actuator 16. Further, it is apparent that the device as described will consistently time either short or long timing periods when the device is operated in the TDE or TDD modes of operation. Further, the device 10 uses a snap, switch which is capable of conducting and interrupting substantial currents to control its load circuit and solid state circuitry to accurately time the time intervals, the device 10 may be used as an economical substitute for either pneumatic or solid state type timing devices.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A timing device comprising: an electromagnet including a stationary magnet part, a magnet armature assembly and a magnet coil magnetically coupled to the stationary magnet part and the armature assembly for causing the armature assemblyto move from a first to a second position when the magnet coil is energized, an electric switch having an operator movable from a first position to a second position, a releasable permanent magnet latch having a member movable from a first position to a second position, a permanent magnet providing an output flux for maintaining the member in its first position and a magnet release coil providing an output flux to effectively cancel the flux output of the permanent magnet for releasing the latch member for movement to' its second position when the magnet release coil is energized, an operating lever assembly having a first portion movable by the armature assembly, a second portion engageable with the switch operator, and a third portion engaged by the latch member for maintaining the switch member in its second position when the latch member is at its first position and for releasing the switch operator for movement to its first position upon release of the latch member, and a solid state timing circuit having inputs connected to receive an inputsignal change concurrently with the energization or deenergization of the electromagnet coil and outputs connected to the magnet release coil for energizing the magnet release coil a predetermined time interval after an input signal change.

2. The timing device as recited in claim 1 wherein the armature assembly includes a pair of spaced oppositely facing cam surfaces and the lever assembly is selectively movable to two programmed positions wherein the first portion engages one of the pair of cam surfaces when the lever is at a first programmed position for maintaining the switch operator in its second position when the armature assembly is at its first position and wherein the first portion engages a second one of the pair of cam surfaces when the lever is at a second of its two programmed positions for maintaining the switch operator in its second position when thearmature assembly is at its second position.

3. The timing device as recited in claim 1 wherein the switch is of the snap acting type.

4.-The timing device as recited in claim 1 wherein the portion of the operating lever that engages the switch operator is adjustable.

5. The timing device as recited in claim 1 including an operating button having a portion engageable with the latch member for moving the member to its second position when a manual force is applied to the operating button.

, 6. The timing device as recited in claim 1 wherein a lost motion connection provides the engagement between the third portion and the latch member.

7. The timing device as recited in claim 1 wherein the electromagnet coil has a pair of input terminals and a pair of terminals connected to provide the input signal change to the solid state circuit when the electromagnet coil is energized.

8. The timing device as recited in claim l-wherein the solid state circuit includes a capacitor whichprovides the electrical energy to the release coil to release the magnet latch a predetermined time interval after the electromagnet coil is de-energized.

9. The timing device as recited in claim 2 wherein a two position switch provides a programmed input to the solid state circuit for programming the solid state circuit in a first mode of operation when the lever is programmed in its first position and the two position switch is at a first of its two positions and for programming the solid state circuit in a second mode of operation when the lever is at its second position and the switch is at a second of its two positions.

10. The timing device as recited in claim 9 including a potentiometer resistor having a manually adjustable portion for varying the time interval and wherein the device.

11. The timing device as recited in claim 10 including a means for varying the timing interval in discrete steps, said means having a portion externally accessible and manually movable from the front side of the device for adjusting the timing interval in discrete steps from the front side of the device.

Claims

1. A timing device comprising: an electromagnet including a stationary magnet part, a magnet armature assembly and a magnet coil magnetically coupled to the stationary magnet part and the armature assembly for causing the armature assembly to move from a first to a second position when the magnet coil is energized, an electric switch having an operator movable from a first position to a second position, a releasable permanent magnet latch having a member movable from a first position to a second position, a permanent magnet providing an output flux for maintaining the member in its first position and a magnet release coil providing an output flux to effectively cancel the flux output of the permanent magnet for releasing the latch member for movement to its second position when the magnet release coil is energized, an operating lever assembly having a first portion movable by the armature assembly, a second portion engageable with the switch operator, and a third portion engaged by the latch member for maintaining the switch member in its second position when the latch member is at its first position and for releasing the switch operator for movement to its first position upon release of the latch member, and a solid state timing circuit having inputs connected to receive an input signal change concurrently with the energization or deenergization of the electromagnet coil and outputs connected to the magnet release coil for energizing the magnet release coil a predetermined time interval after an input signal change.

2. The timing device as recited in claim 1 wherein the armature assembly includes a pair of spaced oppositely facing cam surfaces and the lever assembly is selectively movable to two programmed positions wherein the first portion engages one of the pair of cam surfaces when the lever is at a first programmed position for maintaining the switch operator in its second position when the armature assembly is at its first position and wherein the first portion engages a second one of the pair of cam surfaces when the lever is at a second of its two programmed positions for maintaining the switch operator in its second position when the armature assembly is at its second position.

4. The timing device as recited in claim 1 wherein the portion of the operating lever that engages the switch operator is adjustable.

6. The timing device as recited in claim 1 wherein a lost motion connection provides the engagement between the third portion and the latch member.

8. The timing device as recited in claim 1 wherein the solid state circuit includes a capacitor which provides the electrical energy to the release coil to release the magnet latch a predetermined time interval after the electromagnet coil is de-energized.

10. The timing device as recited in claim 9 including a potentiometer resistor having a manually adjustable portion for varying the time interval and wherein the adjustable portion of the potentiometer, the two position switch, a portion on the lever assembly for selectively moving the lever assembly to the two programmed positions and an operating button that has a portion engageable with the latch member for manually moving the latch member to its second position each include portions that are externally accessible and manually operable from a front side of the timing device.