US2932701A - Electric time switches - Google Patents

Description

April 12, 1960 Filed Jan. 10, 1958 F. o. HORSTMANN 2,932,701

ELECTRIC TIME SWITCHES 2 Sheets-Sheet 1 INVENTOR FREDERICK O. HORSTMANN ATTORNEY April 12, 1960 F. o. HORSTMANN 2,932,701 ELECTRIC TIME SWITCHES Filed Jan. 10, 1958 2 Sheets-Sheet 2 INVENTOR J Fnsnzmcx O. H ORSTMANN ATTORNEY United States Patent Ofice Patented Apr. 12, 1960 ELECTRIC TIME SWITCHES Frederick Otto Horstmann, Bath, England Application January 10, 1958, Serial No. 708,208

Claims priority, application Great Britain January 15, 1957 '5 Claims. (Cl. 200-35) This invention relates to electric time switches of the type used for making or breaking electric circuits, for example electric lighting circuits, at predetermined times of the night or day. Time switches of the type referred to herein comprise a dial plate rotated periodically and carrying adjustable members, referred to herein as tappets, adapted to actuate an electric switch mechanism.

Time switches of this type are described in Horstmanns prior British patent specifications Nos. 329,633, 331,083, 373,554 and 500,670.

The object of the present invention is to provide a time switch of this type which is of improved and novel construction having a number of advantages in manufacture and operation.

According to one aspect of the present invention, a time switch has a dial plate driven through a speedreduction gearing by an electric motor, the said dial plate carrying tappets adapted to actuate an electric switch mechanism, in which the said speed reduction gearing includes a ratchet wheel, a driving pawl for rotating the ratchet wheel and a reciprocating connection between the pawl and a member of said gearing whereby said pawl is reciprocated to drive said ratchet wheel in a given direction irrespective of the direction of rotation of the motor, said switch mechanism comprising two staggered starwheels adapted to be selectively engaged by the tappets and fixed to a first pinion wheel, two switch blade operating cams fixed to a second pinion wheel, the second pinion wheel being driven from the first pinion wheel.

Preferably, the ratchet wheel drives the dial plate through an epicyclic speed-reduction gearing, to which end the ratchet wheel may carry a rotatably mounted planet of the case part 3 by a movement carrying plate 9, having a number of pressed-out and rearwardly inclined tongues of which one is shown at 8 in the view of Figure 2. The tongues 8 resiliently press against the body of the synchronous motor when the plate 9 is secured in position as shown. The plate is located in the case part 3 and is retained by a part-circular spring clip 56 which is received in grooves formed in the inner faces of the lands 4. The face plate 9 carries a spindle 10 on which is rotatably mounted a large pinion wheel 11 fixed to a smaller pinion wheel 12. The pinion 11 engages with the pinion 7 and the pinion 12 fixed to pinion 11 engages with a large output pinion wheel 13 rotatably mounted on a spindle 14 also carried by the plate 9. Fixed to the pinion 13 is an eccentric bush 14 on which is rotatably mounted a sleeve 15 carrying a spring ratchet pawl 16 of hard drawn wire. The pawl 16 has a crook 17 which receives one end of a tension spring 18, the other end of Which is retained by a pin 19 mounted on the plate 9. The tension of spring 18. holds the pawl 16 in engagement with the teeth of a ratchet wheel 20 rotatably mounted on a spindle 21. The rear face of the ratchet wheel 20 which retains all the rotating gears and the eccentric sleeve on their respective shafts is protected by a circular hardened steel shim 22. The ratchet wheel 20 is itself spaced from the back plate 9 by a wheel which is meshed with two sun wheels of equal pitch diameter but having difierent numbers of teeth, one sun wheel being fixed and the other sun wheel being connected to the dial plate.

In order that the invention may be readily carried into effect, one embodiment will now be described in detail, by way of example, with reference to the accompanying drawings, in which:

Figure 1 is a front view of a time switch of the type referred to herein with its front cover removed;

Figure 2 is a front view of a part of the time switch driving mechanism;

Figure 3 is a side elevation of the time switch, part of the casing and front cover being cut away; and

Figure 4 is a rear view of the lower part of the time switch, showing contacts for the electrical connections thereto.

As shown particularly in Figures 1 and 3, the time switch comprises a case 1, of moulded material, having a substantially oval shape and having a front cover 2. A cylindrical rearward extension 3 of the case 1 has a number of inwardly projecting lands 4, moulded integrally with the case and dimensioned to locate a synchronous electric motor 5, of generally cylindrical shape, having a rotor spindle 6 carrying a pinion 7. The synchronous motor 5 is held securely against its seating at the back bush 30.

By the drive mechanism so far described, the motion of the synchronous motor 5, running at the synchronous speed of 200 rpm, is reduced in speed by the reduction gearing comprising pinions 7, 11, 12 and 13 and is converted into a reciprocating motion by the eccentric bush 14' and sleeve 15. A reciprocating motion of the pawl 16 is produced regardless of the direction of rotation of the motor 5. Therefore, no special starting mechanism or special construction of the motor is required in this time switch to ensure that the motor always runs in one direction.

The reciprocating motion of the pawl 16 is again converted to a rotary motion of the ratchet wheel 20, for which the pawl 16 is thus the driving pawl. The teeth of the ratchet wheel 20 are arranged so that the ratchet wheel is rotated in the anti-clockwise sense as seen in Figure 2. Reverse motion is prevented by restraining spring pawl 23 mounted on a pin 24 and anchored in a hole 25 in the face plate 9, through which a rearwardly bent end of spring 23 extends.

As most clearly seen in the views of Figure 2 and Figure 3, the ratchet wheel 20 carries a forwardly extending pin 26 on which is rotatably mounted a planet wheel 27. The planet wheel 27 engages the two sun wheels 28 and 29 of equal pitch diameter to each other.

The sun wheel 28 is fixedly mounted on the spindle 21 which has a rearwardly extending portion terminating in a rectangular key 31. The key 31 is received in a rec tangular slot 32 in the plate 9 which prevents rotation of the spindle 21 and sun wheel 28. The sun wheel 29 is mounted on a forwardly extending sleeve 33 which is rotatably mounted on the spindle 21. The sleeve 33 projects through a central aperture in a second movement? carrying plate 34 and'has a split front end 35 on which is mounted a dial plate 36. I

Since the sun wheel 28 is fixed, the planet wheel 27 is rotated as it is carried round the sun wheel 28 by the rotation of the ratchet wheel 20. The two sun wheels 28 and 29 are cut with one tooth difference between them, the sun wheel 28 having teeth and the sun Wheel 29 having '81 teeth, so that with one complete rotation of the ratchet wheel 20, a relative rotational displacement of the two sun wheels 28 and 29 is produced, corresponding to the pitch of one tooth of the'sun wheel 29. Since the sun wheel 28 is fixed, this displacement provides a slow rotation of the sun wheel 29.

The speed reduction of the time switch driving mechanism described is such as to produce one complete revolua sleeve 37 having a fixed collar 38 and a numberof intermediate spacing discs: 39 and tappet-carrying discs 46. If additional tappets are required their discs 40 would replace a suitable number of the spacers 39., A forwardly-pivotable locking arm 41 provides an axial pressure,- in the position in which it is shown in the drawings, between the dial plate 36 and the collar 38 to'lock the tappet discs 40. In the embodiment described, an on tappet 42 and an off tappet 43 are provided, having radial arms carrying rearwardly extending pins 43' and 44 respectively, the pin 43' of the on tappet extending further backwards than the pin 44 of the off tappet.

The plate 34 is located against a lip 45 moulded at the front of the case portion 3 and is retained by a partcircular spring clip 46 which is received in a groove formed in the case 1. When assembled, as shown in the view of Figure 3, the plate 34 forms a continuous surface with the interior rear surface 47 of the case 1. V The plate 34 has a projection 60 which locates in a keyway moulded in the case 1 to position the plate 34 rotationally. The plate 9 has a similar projection by which it is located in the same keyway and it is retained by a part-circular spring clip 56.

The plate 34 is also provided with a small circular aperture facing the pinion wheel 13. The pinion wheel 13 is provided with radially spaced markings on its front face, so that the markings are visible through the aperture in the plate 34 and serve to indicate the movement of the drive mechanism and thus that the motor is running. a

An earthing clip 48, secured to the outside of the cylindrical part 3 of the case 1, has a tongue 49 which extends through an aperture in the case and bears against the back surface of the plate 34 to provide an earthin connection thereto. g

Mounted on the plate 34 is a pin 50, on which is rotatably mounted a moulded assembly' comprising a front, three-pointed star-wheel 51, a rear three-pointed starwheel 52 and a pinion wheel 53. The two star-wheels 51, 52 are arranged with their points in staggered relationship. A leaf spring 54, secured at one end to the plate 34, bears against the points of the star-wheels 51 and 52 and serves to locate the assembly in rotation. The leaf spring 54 has a downwardly extending portion 55 which bears against the front of the assembly to retain it on the pin 50.

A pin 57 moulded in the case -1 carries a pinionwheel 58 which engages both with the pinion wheel 53 and a contacts 68 and 69 respectively andsecured to terminals 70 and 71 respectively which extend through the case 1, as shown in the views of Figurel and Figure 4. j

' As, is best seen from the view 'of Figure 3, rotation of the dial plate 36 carries the tappets 42 and 43 past the star-wheels-Sl and 52. The rearwardly extending pins 43' and 44 engage with the points of the star-wheels 52 and sl respcctively to move them forward by one position as the tappets' pass. However, owing to the different lengths of the pins 43' and 44 and the different levels of the star-wheels 51 and52, only the pin 43 can engage with the star-wheel 52;

Actuation of the star-wheel 52 is arranged to close the switch contacts 68 and 69, as is further explained below.

l} If, for any reason, the time switch is incorrectly set, whereby the switch is already in the off position when an off tappet passes, no further actuation of the switch results because the pin 44 is too short to engage the star-wheel 52. The star-wheel 52 thus remains stationary until it is engaged by the pin 43'.

In normal operation, the star-wheels 51 and 52 are each rotated by one-sixth of a revolution by the appropriate pins 43' or 44. This rotary movement is transmitted byway of the pinions 53, 58 and 59 to the Arzbcrger switch cams 62 and 63. The cams 62, 63 are formed so that the switch contacts 68 and 69 are closed and opened three times for each complete revolution of the assembly 61. The assembly 61 is initially assembled in relation to the star-wheels 51 and 52 so that movement imparted to the star-wheel 52 causes the switch contacts 68 and 69 to be closed, while movement imparted to the star-wheel 51 causes the switch contacts to be opened. i

The cams 63, which effect the closing of the switch, are shaped so that the switch contact 69 is made to I approach very closely to the switch contact 68 before the cam surface step is reached to cause the actual closing of the switch. By this means, contact bounce, and hence contact burning, are much reduced.

The card 65 carries radial markings On and Off which are visible through a window in a cover 72 arranged in front of the switch mechanism. The cover 72 rests on two projections 97 moulded inside the case 1 and on two part-cylindrical moulded projections 98. The projections 98 are shaped to receive spare fuses, one of which is shown in position at 99. V

A mechanism is also provided for switching the switch manually to the on position. A sleeve 73 is carried on a pin 74 mounted in the case 1. The sleeve '73 has a fluted handle 73 which'projects throug'hthe cover 72 and through a recessed portion 102 of the front cover 2.

The sleeve 73 carries a cam 75 which engages a crooked portion 76 of the switch arm 66. Rotation of the handle 73 in the clockwise sense, from the off position shown in Figure 1, moves the switch blade 66 downwards to close the contact 68 against thecontact 69. At the same time, a signal arm 7'7 carrying an on indication is moved between the card 65 and the window in the cover 72. The manual operating mechanism is located in the on and off positions by fork arms 78 and 79 respectively which abut against a pin 80 moulded in the casing 1.

If the manual operating mechanism should inadvertently be left in the on position, subsequent operation of the switch mechanism to the on position causes one ofthe three arms 64, formed integrally with the pins 64 and the switch cams 62, 63, to engage an arm 73 extending from the sleeve 73, and return the manual operating mechanism to the-off? position. v

Referring now to Figure 4, a split pin 70 forms the rearward extension of the terminal 7(ljshown in Figure 1.

' A rearwardly extending split pin 81 is connected to the terminal 71 by a conducting strip 82. The pin 81 is also connected bya conducting strip 83 to a clip 84. Auxiliary pins 85 and 86, of smallerdimensions than the pins 70 and 81, are connected respectively to clips 87 and 88. In the arrangement of connections shown in Figure 4, a cartridge fuse 89 extends. between the clip, 87 and a connecting tag 90- arranged in an apert'ureh91 in the moulded case 1. Similarly, a cartridge fuse 92 extends from the clip 88 to a connecting tag 93 arranged in an aperture 94 in the moulded casev 1.

. The connecting tags 98 and 93 are provided at the ends of leads supplying the synchronous motor 5. In the arrangement shown in Figure 4, fuses are provided in both the motor supply leads. If the fuses are not required, the tags 9t) and 93 can be inserted directly in the clips 87 and 88 respectively. Alternatively, the fuses 89 and 94 may be removed and a cartridge fuse of larger size may be fitted between the clip 84 and a tag located in the aperture 95. As a further alternative, one of the fuses 89 or 92 may be arranged between the clip 84 and a terminal block inserted in the apertures 96.

In a modification of the embodiment described above, the mechanism for setting the switch manually to the on" position is replaced by an automatic mechanism for setting the switch selectively to the on or to the oil position on one or more days of the week, regardless of the sequence of operations normally determined by the setting of the on and oif tappets. In this embodiment, the dial plate carries a further tappet having a radial arm of greater length than the on and oil tappets. This arm carries a pin extending rearwards and arranged to sweep a path of greater radius than the pins of the on and ofi tappets. Accordingly, the further tappet does not actuate the star-wheels 51 and 52. A pin carried in the base 47, positioned a little above the terminals 70 and 71, carries a 7-pointed starwheel provided with seven tapped holes adapted to receive screw pegs. In rotation, these pegs bear against the face of a lever mounted on the pin 80 and carrying a pinion wheel, or having a toothed sector which engages a pinion or corresponding toothed sector, mounted on the pin 74. The latter pinion or toothed sector is formed integrally with a plate of insulating material arranged to revolve behind the switch blades 66 and 67. The plate is threaded at two points to receive actuating pegs in one or other of the threaded holes. If an actuating peg is inserted in the upper hole, it will bear against the switch spring 66 to close or hold closed the contacts 68, 69. If an actuating peg is inserted in the lower hole, it will bear against the switch spring 67 to open or hold open the switch contacts 68, 69.

The 7-pointed star-wheel is moved forward one position by each engagement of the further tappet therewith, so that it is rotated one complete revolution in a week.

The pegs thereof engage the lever and the rotary motion is transmitted through the pinions or toothed sectors to the insulating plate, to move the switch either to the on position or to the off position in the manner stated. Thus the switch may be set to the on or off position on any day or days of the week, this additional control over-riding the normal daily operation by the on and off tappets.

I claim:

1. A time switch comprising a casing which includes mounting means for a synchronous electric motor having an output rotor spindle, a dial plate, a spindle for said dial plate, parallel to said rotor spindle, switch mechanism, tappets on said plate for actuating said switch mechanism, a ratchet wheel drive to said dial plate wherein the ratchet wheel is coaxial with said dial plate spindle, a speed reduction gear from said motor spindle to said ratchet wheel including an output wheel, an eccentric disc fixed to a face of said output wheel about the rotational axis thereof, a sleeve rotational on said eccentric disc and carrying a pawl in engagement with the ratchet wheel teeth whereby said pawl reciprocates to drive the ratchet wheel in one direction only by rotation of the eccentric disc with the output wheel in either direction, said ratchet wheel drive including a planet pinion rotational about a pivot projecting from the ratchet wheel at a position oifset from the axis thereof, two sun wheels in mesh with said pinion and of equal diameter but having at least a difference of one between the respective numbers of teeth, one sun wheel being fixed in said casing coaxial with said dial plate spindle, and a driving connection between the other sun wheel and said dial plate.

2. A time switch comprising a casing mounting a synchronous electric motor and a switch actuating dial plate, a two-stage speed reduction drive from the motor to the dial plate including uni-directional means in the first stage for rotating the second stage in one direction only irrespective of the direction of rotation of the electric motor, said second stage comprising a pair of co-axial sun wheels of equal pitch diameter one fixed and the other drivingly connected with the dial plate, and a rotatable planet pinion in mesh with both said sun wheels and driven by said uni-directional means round said sun wheels, the fixed sun wheel having at least one tooth less than the other wheel.

3. A time switch comprising a casing having mounting means for a synchronous electric motor and a switch actuating dial plate driven thereby through a two-stage reduction gear with a ratchet wheel drive from the first to the second stage, said second stage comprising an epicyclic gear having two sun wheels of equal pitch diameter and different numbers of teeth one fixed and the other drivingly connected to the dial plate, a planet pinion in mesh with both sun wheels and carried on said ratchet wheel oifset from the axis thereof, a reciprocatable pawl engaging the ratchet wheel teeth to drive the ratchet wheel in one direction only, and means providing a reciprocating drive from the last gear of the first stage to said pawl.

4. A time switch comprising a casing having mounting means for a synchronous electric motor having a spindle, a switch actuating dial plate, a two-stage reduction gear between the motor spindle and the dial plate of which the second stage comprises a planet pinion and a plurality of sun wheels with different numbers of teeth in mesh with said planet pinion, and a uni-directional transfer drive between the two gear stages including a pawl, means for reciprocating the pawl from the last gear wheel of the first stage and a rotational ratchet wheel driven in one direction only by said pawl irrespective of the direction of rotation of the motor, said ratchet wheel carrying said planet pinion at a position offset from its rotational axis.

5. A time switch having a dial plate driven through a speed-reduction gearing by an electric motor, the said dial plate carrying tappets adapted to actuate an electric switch mechanism, in which the said speed reduction gearing includes a ratchet wheel, a driving pawl for rotating the ratchet wheel and a reciprocating connection between the pawl and a member of said gearing whereby said pawl is reciprocated to drive said ratchet wheel in a given direction irrespective of the direction of rotation of the motor, said switch mechanism comprising two staggered star-wheels adapted to be selectively engaged by the tappets and fixed to a first pinion wheel, two switch blade operating cams fixed to a second pinion wheel,

the second pinion wheel being driven from the first pinion wheel.

References Cited in the file of this patent UNITED STATES PATENTS 1,937,392 Long Nov. 28, 1933 2,187,406 Staples Jan. 16, 1940 2,256,466 Cullin Sept. 23, 1941 2,438,061 Lear Mar. 16, 1948 2,605,833 Bliss Aug. 5, 1952 2,693,115 James et al. Nov. 2, 1954 2,723,320 Harris Nov. 8, 1955 2,830,473 Brown Apr. 15, 1958 2,833,976 Kennedy et a1. May 6, 1958

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