US2920153A - Electric time switches - Google Patents

Description

1960 B. G. HORSTMANN 2,920,153

ELECTRIC TIME SWITCHES Filed Dec. 18, 1957 2 Sheets-Sheet 1 ii} 1 1 55 26 22 I 5' L19 7 59 Q l" g;- 67 :5:

INVENI OR BEVAN G. HORSTMANN BY aw zinziwg a ATTOR NE Y 1960 B. G. HORSTMANN 2,920,153

ELECTRIC TIME SWITCHES Filed Dec. 18, 1957 2 Sheets-Sheet 2 INVENTOR BEVAN ,G. HORSTMANN ATTORNEY United States Patent 1 2,920,153 ELECTRIC TIME SWITCHES Bevan Graham Horstmann, Bath, Somerset, England Application December 18, 1957, Serial No. 703,557 2 Claims. (Cl. 200-38) This invention relates to electric time switches of the type having a control spindle which is set by manual rotation in one direction and is subsequently returned to its original position by a time-regulated clockwise mechanism, a cam attached to the control spindle being designed to move main switch contacts to an on position when the control spindle is manually rotated and to restore the contacts to their original off position when the control spindle is returned to its original position after a time interval which depends on the angle through which the spindle was manually rotated; such time switches are hereinafter referred to as the type set forth. The. invention is particularly applicable to time switches of the type set forth in which the control spindle has an axial movement by which the switching device can be set to its off position after the spindle has been angularly displaced, provision being made for holding the spindle axially displaced for a delay period which can be set by rotation of a knob or dial and then causing it to move to an axial position in which it holds the switching device in its-on position until the spindle has been turned back to its starting position. Such time switches may be used for example for turning on a cooker for a predetermined cooking period the starting of which is delayed for a period set by rotation of the knob or dial above referred to.

The invention provides a time switch of the type set forth which can be set to a permanent on position (i.e. to a position in which the switch will remain on indefinitely) at will, by merely turning the control knob to an extreme position. This is achieved according to the invention by a member on the control spindle which operates auxiliary switch contacts for stopping the clockwork mechanism when the control spindle is set to a predetermined position, at which the main switch is closed.

A practical arrangement of the invention will now be described, by way of example only, with reference to the accompanying drawings whereof:

Figure 1 is a side view of a time switch according to this invention.

Figure 2 is a side elevation of the knob and its associated parts shown diagrammatically in a different position of that in Figure 1.

Figures 2a and 2b are respectively front and side elevations diagrammatically illustrating the position of parts shown in Figure 2.

Figure 3 is a side elevation similar to Figure 2 further illustrating the various switches in different positions than that shown in Figure 2.

Figures 3a and 3b are respectively (front and side elevations showing structure diagrammatically indicated in Figure 3.

Figure 4 is a further side elevation of the knob in another position. 7

Figures 4a and 4b are respectively front and side elevations of the condition of parts shown in Figure 4.

Figure 5' is a side elevation of the knob and its associated parts in an additional diagrammatic relationship from Figure 4.

Figures 5a and 5b are respectively front and side elevations of the parts diagrammatically illustrated as they appear in Figmre 5.

Figure 6 is a further side elevation of the knob disclosed in Figures 2, 3, 4 and S.

2,920,153 Patented Jan. 5, 1960 Figures 6a and 6b are respectively front and side elevations of the knob shown in Figure 6 with the parts in the diagrammatic relationship indicated therein.

Referring to Figure l of the drawings: the time switch comprises asynchronous electric motor 10 connected to a mains supply by loads 11, 12 through the intermediary of a switch 13 between leads '12 and 112, the latter being connected to the motor. Motor 10 drives a going train 14 of a clockwork mechanism, said train comprising a pinion 15 which meshes with a gear 16 mounted on a spindle 17 through a friction clutch 18 e.g. comprising metal discs 19 between which is clamped, by springs 20, the gear 16 of a fibre material, the discs being coupled to the spindle 17.

The spindle '17 is mounted in bearings 21 and extends completely through the clockwork mechanism and carries a control knob assembly (generally indicated at 22) at one end and a cam means 23' at the other end. The spindle 17 may be rotated (as later described) by knob assembly 22 and by the clockwork mechanism through clutch 18, and the spindle, which is urged towards the right as seen in Figure 1 by a spring 24, may be moved axially in its bearings. During the rotational and axial movements the spindle correspondingly moves the cam means 23.

The particular time switch being described is tocontrol a domestic electric oven and the oven is connected between leads 11 and 25, the latter being connected to lead 12 through a main switch 26 which is actuated by cam means 23. The cam means also actuates the auxiliary switch 13.

The cam means 23 comprises a recess 27 having an inclined face leading to a flat surface 28 and a raised part 29 lying radially beyond the recess 27. The switches 13, 26 have a common movable arm 30 having one of the contacts 31, 32 of the two switches and the arm has a follower 50 to enter recess 27 as shown in Figure 1. The raised part 29 engages an arm 33 carrying the other contact 34 of switch 13.

The assembly 22 comprises a knob 35 secured to an end of spindle 17 and a ring 36 around the knob. The ring 36 is loose on the front bearing 21 and is urged by a spring 37 towards a stationary plate 38, a rubber plug 51 being interposed so that the ring is held against inadvertent movement by frictional engagement of the plug with plate 38.

A pin 39 projects from plate 38 and co-acts with a slot 40 in the back of the ring to limit the angular movement thereof.

A block 41 projects forwardly from the back of the ring and can enter a recess 42 behind the knob 35. When the block is in the recess rotation of the knob will turn the ring. If the knob is pulled axially away from the ring the recess is carried clear of. the block and the knob may turn independently of the ring. The back face of the knob at the side of recess 42 is flat and permits the knob to turn relatively to the ring while the block 41 abuts said back face.

A cooking period scale 43 graduated in hours extends partly around the ring which has a pointer 44 and the knob is also graduated in a time delay (e.g. hour) scale 45.

The time switch will now be described in use.

In the position of- Figure 2 the block 41 is within recess 42, the pointer 44 is opposite zero on scales 43 and 45, and cam 23 is in a position such that follower 50 is in recess 27 while raised part, 29 is away from arm 33. This is the extreme right hand position of the cam as indicated by line x. The switches 13 and 26 are open and consequently the clockwork mechanism is inoperative and the oven is disconnected from the mains.

The operation of selecting a cooking period of 2 hours which is to be initiated after a delay period of 5 /2 hours will now be described, starting from the inoperative position shown in Figures 1 and 2.

The knob 35 is rotated clockwise to carry the pointer 44 opposite the 2 hour graduation on the cooking scale 43, the ring 36 being moved round with the knob because the block 41 is in recess 42. The spindle 17 is turned with knob 35 so that cam 23 is also rotated clockwise whereby follower 50 rides out of the recess 27 and engages face 28 with the result that arm 30 is displaced to close switches 13 and 26. The clockwork mechanism is then driven by motor and the circuit to the oven is completed. The position of the various parts is then as shown in Figure 3.

The knob 35 is then pulled axially (as shown by the arrow of Figure 4) against spring 24 with the result that cam 23 is drawn away from arm 30, i.e. to the left of line x (Figure 4). Consequently switch 26 is opened breaking the circuit to the oven. Arm 33 of switch 13 is sprung towards cam 23 so that switch "13 remains closed but in the position of Figure 2 closing movement of arm 33 is prevented by engagement of the horizontal limb of the arm with the cam. However, when the cam is moved to the left (Figure 4) the arm is free and switch 13 remains closed though arm 30 moves to the left to open switch 26.

When knob 35 is moved axially block 41 disengages recess 42 so that the knob can be turned independently of the ring 36. This is now done (in the same direction as before) to bring the 5 /2 hour graduation on the delay scale 45 opposite pointer 44. During this adjustment ring 36 is held against rotation by plug 51. In turning the knob cam 23 has been correspondingly rotated by spindle 17 to carry recess 27 further away from follower 50 (see Figure 5). The switches 13, 26 remain as for Figure 4.

During rotation of knob 35 spindle 17 is rotated without driving the going train 14 because of friction clutch 18. When spindle 17 is moved axially pinion .15, because of its lenth, remains in mesh with gear 16 which, of course, is moved with the spindle.

The clockwork mechanism is then operative (switch 13 being closed) to drive spindle 17 in the opposite direction carrying cam 23 and knob 35 round with it-ring 36 remains stationary.

When the knob is returned to the position at which zero on scale 45 is opposite pointer 44 block 41 enters recess 42 (Figure 3). This occurs at the end of the delay period of 5 hours and block 41 entering recess 42 enables spring 24 to move spindle 17 axially so that switch 26 is closed. The oven is then switched on. Switch 13 remains closed and spindle 17 is driven to carry knob 35 and ring 36 around as a unit with cam 23. At the end of 2 hours cooking period pointer 44 is opposite zero of scale 43 and cam 23 has been rotated so that recess 27 is opposite follower 50 (Figure 2). Consequently switches 13 and 26 are opened, the oven is shut off and the motor 10 is stopped.

When it is required to switch the oven on without controlling the time of the cooking operation by the clockwork mechanism in the manner described the knob 35 is turned to an extreme position as shown in Figure 6 while the knob is in driving engagement with ring 36, so that pointer 44 is opposite the maximum cooking time of 4 hours on scale 43. Cam 23 is thereby rotated to bring follower 50 on to face 28 so that switch 26 is closed, and the oven is thereby switched on, and projection 29 having engaged arm 33 the end of the latter rides up the said projection whereby switch 13 is opened and the motor 10 is rendered inoperative.

I claim:

1. An electric time switch arrangement comprising a main switch comprising first and second main switch contacts, an auxiliary switch comprising first and second auxiliary switch contacts, a common movable switch arm whereon said first main switch and auxiliary switch contacts are mounted, cam means confronting said switch arm and said second auxiliary switch contact and operably associated therewith to open and close said switch contacts, said cam means being rotatable from a Zero position wherein said main switch contacts and auxiliary switch contacts are open, through a range of intermediate positions wherein both switches are closed the cam means acting on said common movable switch arm, to a full-on position wherein said main switch contacts are closed and said auxiliary switch contacts are open by action of said cam means upon said second auxiliary switch contact, said cam means also being displaceable away from said contacts to open the contacts of said main switch when they are closed, a rotatable and axially displaceable control spindle whereon said cam means is mounted, spring means acting so as to urge said cam means towards said switch contacts, manually-operable means whereby said control spindle can be rotated in one direction for setting the switch, said manually-operable means also permitting said control spindle and cam means to be moved to an axially displaced position against the action of said spring means, an electric motor controlled by said auxiliary switch and in driving connection with said control spindle to rotate said spindle, when said auxiliary switch contacts are closed, back to said zero position, and time delay means adapted selectively to maintain said control spindle and said cam means in their said axially displaced position for a predetermined period.

2. An electric time switch arrangement comprising a main switch comprising first and second main switch contacts, an auxiliary switch comprising first and second auxiliary switch contacts, a common movable switch arm whereon said first main switch and auxiliary switch contacts are mounted, cam means confronting said switch arm and said second auxiliary switch contact and operably associated therewith to open and close said switch contacts, said cam means being rotatable from a zero position wherein said main switch contacts and auxiliary switch contacts are open, through a range of intermediate positions wherein both switches are closed the cam means acting on said common movable switch arm, to a full-on position wherein said main switch contacts are closed and said auxiliary switch contacts are open by action of said cam means upon said second auxiliary switch contact, said cam means also being displaceable away from said contacts to open the contacts of said main switch when they are closed, a rotatable and axially displaceable control spindle whereon said cam means is mounted, spring means acting so as to urge said cam means towards said switch contacts, a manually-operable knob whereby said control spindle can be rotated in one direction for setting the switch, said manually-operable knob also being displaceable so as to move said control spindle and cam means to an axially displaced position against the action of said spring means, an electric motor controlled by said auxiliary switch and in driving connection with said control spindle to rotate said spindle, when said auxiliary switch contacts are closed, back to said zero position, and time delay means comprising a ring confronting the knob, a block associated with said ring and projecting towards the knob and engageable into a recess in the knob, for selectively maintaining said control spindle and said cam means in their said axially displaced position for a predetermined period.

References Cited in the file of this patent UNITED STATES PATENTS 2,499,270 Ellis Feb. 28, 1950 2,702,322 Truesdell s Feb. 15, 1955 2,758,166 Aust et a1. Aug. 7, 1956 2,782,271 Jordan Feb. 19, 1957 2,803,715 Guth Aug. 20, 1957 2,813,161 Tuttle Nov. 12, 1957 UNITED STATES PATENT OFFICE v CERTIFICATE OF CORRECTIGN Patent No. 2,920,153 January 5 1960 Bevan Graham Horstmann It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 1 line 4 for "clockwise" read clockwork Signed and sealed this 16th day of August 1960.

SEAL) Attest:

KARL H. AXLINE ROBERT C. WATSON Attesting Ofiicer Commissioner of Patents

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