US3925630A

US3925630A - Timer switch assembly having latch assembly for preventing contact engagement

Info

Publication number: US3925630A
Application number: US534359A
Authority: US
Inventors: John L Harris
Original assignee: Deltrol Corp
Current assignee: Deltrol Corp
Priority date: 1974-12-19
Filing date: 1974-12-19
Publication date: 1975-12-09
Anticipated expiration: 1992-12-09

Abstract

An adjustable automatic reset pushbutton timer in which a knob is rotated to set the timing and is pushed to start the time cycles. The knob shaft carries a spring return timing cam and an adjustable stop which sets the starting point. At the end of the cycle a lobe on the cam raises a pair of switch blades with the contacts closed and then drops one while holding the other, opening the contacts. Pushing the knob in first releases a sliding gear type clutch and then moves the cam off the sides of the switch blades, allowing them to drop, and the cam to reset. Closure of the contacts is delayed until the pushbutton knob is released by an axial latch which moves under one blade when the knob is pushed.

Description

United States Patent 1191 Harris Dec. 9, 1975 TIMER SWITCH ASSEMBLY HAVING 3,180,157 4/1965 Harris 200/38 A x LATCH ASSEMBLY FOR PREVENTING 3,489,015 1/1970 Harris 200/39 R x 3,686,450 8/1972 Willis 200/38 FA x CONTACT ENGAGEMENT [75] Inventor: John L. Harris, Clearwater, Fla. Primary E i -J Scott I [73] Assignee: Deltrol Corporation, Bellwood, Ill.

22 Filed: Dec. 19, 1974 [57] ABSTRACT An adjustable automatic reset pushbutton timer in [21] Appl 534359 which a knob is rotated to set the timing and is pushed to start the time cycles. The knob shaft carries a [52 US. Cl. 200/39 R; 74/352; 200/35 R; Spring return timing 9am and an adjustable p which ZOO/3g A sets the starting point. At the end of the cycle a lobe 51 161.01? H01H 43/10 on the Cam raises a P of Switch blades with the 58 Field 61 Search 74/35, 3.52, 3.54, 568 R; contacts closed and then drops one While holding the 200/33 R, 35 R, 38 R, 38 A, 38 F 38 F 3 other, opening the contacts. Pushing the knob in first B, 38 BA, 38 C, 38 CA, 39 R, 39 A 153 L releases a sliding gear type clutch and then moves the 153 3 cam off the sides of the switch blades, allowing them 1 to drop, and the cam to reset. Closure of the contacts [56] References Cited is delayed until the pushbutton knob is released by an UNITED STATES PATENTS axial latch which moves under one blade when the knob is pushed. 2,706,224 4/1955 White 200/39 R 2,733,764 2/1956 Bliss 200/39 R 13 Claims, 6 Drawing Figures 6 43 4o 45 i9 /36 47 I 23 3 44 5 s s3 6 Y 54 TIMER SWITCH ASSEMBLY HAVING LATCH ASSEMBLY FOR PREVENTING CONTACT ENGAGEMENT BACKGROUND OF THE INVENTION This invention relates to adjustable pushbutton timers of the automatic reset type in which a previously set time cycle is repeated each time a button is pushed.

Timers of this type are made by a number of manufactures and usually have a knob for setting the timing and a separate pushbutton for starting the time cycle. Usually a spring return cam actuates the timer switch at the end of the cycle and is reset to an adjustable starting position by release of a clutch which occurs when the pushbutton is depressed.

The simplest and lowest cost clutch for spring return timers is the type where a gear and its driving pinion are separated. This type of clutch presents problems when used in pushbutton timers. When the pushbutton is depressed slowly, the gear teeth can rub while the timer is resetting, causing undesirable wear and shortening the timer life.

Another problem with pushbutton timers which release the clutch when the pushbutton is depressed is that the timer does not start timing until the pushbutton is released. Unless means are provided for keeping the timer switch open until the pushbutton is released, the time that the button is held in is added to the overall time cycle, giving inaccurate timing.

BRIEF SUMMARY OF THE INVENTION The primary object of the invention is to provide a simple and low cost adjustable push button timer, which gives accurate timing, has long life and reliability and which is easily installed.

In accordance with the invention a single knob has two functions. It can be turned to set the timing and can be pushed for repeating time cycles. The timer cam shaft is axially movable. Pushing it in shifts the timer cam axially releasing the clutch allowing the timer to reset. Releasing the cam shaft allows the clutch to engage and closes the switch.

A further object ofthe invention is the provision of a pushbutton timer mechanism having a gear tooth release type of clutch with means for preventing wear on the gear teeth caused by partial clutch disengagement due to slow operation of the pushbutton.

This is achieved by arranging the timer switch to also serve as a holding means for preventing reset of the cam when the pushbutton is depressed until the clutch is fully disengaged. Depression of the pushbutton first releases the clutch and then releases the cam from the switch, allowing it to reset.

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is an external view of a typical pushbutton timer embodying the invention;

FIG. 2 is a rear view of the timer mechanism and switch with the timer cover removed, the parts being shown in the timed-out position;

FIG. 3 is a fragmentary view showing the positions of the timer cam and switch just before the end of a time cycle;

FIG. 4 is a view similar to FIG. 2 but showing the positions of the parts when the pushbutton is initially depressed:

FIG. 5 is a schematic sectional view showing the position of the parts when the timer shaft is in its normal position;

FIG. 6 is a similar schematic view showing the positions of the parts when the pushbutton is first depressed, corresponding to FIG. 4.

. DETAILED DESCRIPTION OF THE INVENTION FIG. 1 shows the exterior of a typical timer embodying the invention. It shows a housing 1 supporting a switch panel 2 and a timer motor 3. The timer also includes the usual threaded mounting hub 4 through whcih a shaft 5 extends and also includes the usual 10- cating pin 6 for preventing turning of the timer in its mounting. This housing supports the mechanism which will not be described.

The timer switch 7 includes an inner switch blade 8 carrying a contact 9 and supported by a bracket 10 suitably attached to the switch panel 2. The switch 7 also includes an outer switch blade 11 carrying a movable contact 12, blade 11 being supported by a bracket 13 attached to panel 2. Both switch blades are biased to the left as seen in FIG. 2. Switch blade 8 includes an offset portion 14 extending to the left and terminating in a cam' riding portion 15. The outer switch blade 11 includes an offset portion 16 terminating in a cam riding portion 17 which extends downwardly beyond the end of the cam riding portion 15 of blade 8.

Cam riding portions

15 and 17 are actuated in part by a cam lobe 18 of a combination cam and gear 19.

Gear 19 is mounted on the main shaft 5, the forward end of this shaft fitting through a threaded mounting stud 4 attached to front plate 22 of the timer. The back end of shaft 5 is bored out at 23 to receive a stud 24 attached to the back plate 25 of the timer. A spring 26 biases the shaft 5 toward its forward position. It will be apparent that the shaft 5 is mounted for axial movement by pushing on the knob 27, being movable to the position shown in FIG. 6 by pushing on the knob and being returned to its normal position of FIG. 5 by the return spring 26. The shaft 5 is also rotatable by knob 27 which will now be described.

Shaft 5 is formed with a shoulder 30 which supports a tension washer 31 mounted in front of a reciprocating carrier 32 which fits over a shoulder 33 formed on an adjusting stop member 34. Stop member 34 is a press fit on the shaft 5 and rotates with this shaft so that the knob 27 indicates the adjusted position of this stop member. A retainer 35 is also press fit on the shaft 5 and

parts

34 and 35 are pressed on shaft 5 to a point providing substantial tension on the tension washer 31. This washer thus holds the adjustable stop member 34 firmly against the reciprocating carrier 32, permitting angular adjustment of the stop member and retaining it in its adjusted position.

The cam and gear 19 is formed with an inwardly extending stop stud 36 and the adjustable stop member 34 is provided with a similar stud 37 arranged in the path of stop stud 36. A reset spring 38 surrounds the retainer 35 and a hub portion on the cam and gear, this reset spring being arranged to drive the cam and gear 19 counterclockwise until stop stud 36 on the gear engages stud 37 on the adjusting member 34 as shown in FIG. 4.

The cam and gear 19 is driven by a pinion 39 which is preferrably moulded to a gear 40 and slidably mounted on a shaft 41 which extends between the front plate 22 and the back plate 25. A spacer 42 is mounted 3 on the carrier 32 and a strap 43 is attached to theback end of shaft 5 and fits over the shaft 41 at the back of the gear 40. It will be apparent that this arrangement causes sliding movement of the pinion and gear combination 39-40 on shaft 41 causing its axial position to correspond with that of the shaft 5. The gear 40 is a clutch gear and meshes with a pinion 44 which is mounted on a shaft 45 extending between the front and back plates. The clutch pinion 44 is cut away at its back end 45 and carries a gear 46 meshing with the motor pinion 47 driven by the timer motor 3. A compression spring 48 is located over the shaft 45 and bears on a washer 49 which in turn bears against the pinion 44. This spring 48 thus biases the clutch pinion 44 and its driving gear against the back plate 25 as shown in FIG. 5. The reciprocating carrier 32 is formed with a hole fitting snugly over the shaft 45 which allows in and out movement of the carrier 32 with shaft 5 while preventingrotation of the carrier. Thus the carrier is prevented from turning with the shaft 5 and holds the adjusting member 34 in its adjusted position.

OPERATION,

FIGS. 2 and 5 show the timer parts in the positions assumed at the end of the timing cycle. The latch engaging surface 15 on switch blade 8 is engaging a stop portion 50 formed on the reciprocating carrier 32 and I knob 27 until its pointer 52 indicates the desired timing on a dial 53 carried by the panel 54 to which the timer is mounted. Rotation of the knob 27 rotates shaft and 7 also rotates the adjustable stop member 34 thus setting the angular location of the stop stud 37 relative to the timed-out position of the cam and gear stud 36 as shown in'FIG. 2. It is not neccessary to turn the knob 27 for each time cycle. It may be adjusted only when a change in the length of the time cycle is desired.

In order to start a time cycle the user pushes knob 27 in to the position shown in FIG. 6. During this movement the entire timer assembly with the exception of the clutch pinion 44 moves inwardly. As the shaft 5 is pushed inwardly three things occur in the following sequence:

l. Latch surface 54 on carrier 32 rides under the front end of the latch engaging surface 17 of switch 1 blade 11. V

2. The clutch gear 40 rides off the teeth of clutch pinion 44.

3. The latching surface formed by lobe 18 on the cam and gear clears the rear edges of the latch engaging surfaces and 17 of the switch blades.

When this occurs, there is no longer any restraint on the gear 19 and it is rotated counterclockwise as seen in FIG. 2 by the reset spring until gear stud 36 engages the adjustable stop stud 37. When this action takes place, the latch engaging surface 15 of inner blade 8 remains engaged with thelug 50 on the carrier 32. The latch en.-

. gaging surface 17 drops from the outer latching level shown in FIG. 2 to its inner latchinglevel as shown in FIG.,4 where it rests on the latching surface 54 formed on the carrier 32. As shown in FIG. 4 the switch contacts are still disengaged. Thus pushing the shaft 5 4 in causes the timing mechanism to reset to its starting position. However the timer switch remains open and the time cycle is not started simply by depressing the pushbutton. g, I I

In order to start the time cycle the pushbutton must be released which withdraws the latching surface 54 of the reciprocating carrier from the outer end of the latching surface 17of outer blade 11. This unlatches blade 11 from itssecond or inner latching level and permits it to drop causing contact 12 to engage contact 9. This closes the load circuit to the appliance being controlled and also starts the timer motor. This same releasing action causes the clutchgear to move toward the front of the timer back into engagement with the teeth on the clutch pinion 44. If the teeth on the clutch gears do not mesh at this time, the pinion is free to move forward by compressing the spring 48.

Thus interference of the clutch gear teeth in releasing the pushbutton does not prevent the pushbutton shaft from moving outwardly to its normal position. When the timer motor starts and starts rotating the clutch pinion, the clutch gear teeth will line up'and the clutch pinion spring48 will push the clutch pinion back to its normal position in which the clutch gears are fully engaged.

The timer will now start driving clockwise as seen in FIGS. 2 and 3. As the end of the time cycle approaches, the lobe 18 of the cam and gear engages the camming portion 14 of the inner switch blade 8 and lifts both blades to the positions shown'in FIG. 3. At'the end of the time cycle, the latch or cam engaging surface 15 of blade 8 drops behind lobe 18 and the parts reassume the positions shown in FIG. 2' in which the timer contacts are disengaged.

From the foregoing it will be apparent that thecam lobe 18 has three separate functions. It acts as a cam at the end of the time cycle raisingboth switch blades as shown in FIG. 3 and then dropping the inner switch blade while holding the outer switch-bladeto cause the contacts to disengage. It also serves as a latch for holding out the outer switch blade 11 and releasingthis blade when the pushbutton is pushed. It also serves by engaging the end of bladesurface 15 as. a means for preventing reset of the timing means after the clutch is released. This arrangement in. which resetting-motion of the cam-and gear is prevented until after the clutch is released avoids unnecessary wear on the clutch gears. If this holding or reset delaying means were not present, the timer would start resetting just as soon as clutch gear 40 is pushed off the edge of clutch pinion 44. The edges of the teeth could rub at the relatively high resetting speed, this resulting in wear or damage to the gears. i 7

It will also be apparent that the present invention provides a pushbutton timer with a single knob having two functions. Rotation of the knob serves to set the length of the time cycle and pushing in and releasing the knob serves tostart a time. cycle. It will also be apparent that the start of the time cycle is delayed by the arrangement in whichthelatch engaging surface 17 of the outer blade has two separate'latch releasing edges facing in opposite directions. Pushing the k'nob or button in brings the latching surface 54 underthe front releasing surface and continued inward movement causes the cam lobe 18 which now serves as a latch to ride off the rear latch releasing edge onthe outer blade. This latch 54. Release of the pushbutton retracts latch surface 54 from the front latch releasing surface and permits continued movement of the switch blade to close the timer contacts. This successive latch releasing action delays closure of the timer contacts until the pushbutton is released and thus the time that the pushbutton is held depressed is never part of the time cycle.

From the foregoing it will be apparent that the present invention provides a pushbutton timer having a minimum of parts, which is simple and positive in operation and which incorporates a heavy duty switch having positive snap action in both directions. It will be further apparent that the invention provides a timer which is easy to install and which can be used as a replacement for ordinary manual reset timers without any modification of the appliance in which it is installed. While a preferred form of the invention has been shown and described it will be apparent that many changes may be made without departing from the spirit and scope of the invention as defined in the appended claims.

I claim:

1. In a control device, reciprocating control member means biased in one direction and having latch engaging surface means facing in said one direction, said surface means having first and second latch releasing edges facing in opposite directions, reciprocating latch means movable normal to the latch releasing edges, said latch means and latch engaging surface means being constructed and arranged to release the control member means from first and second latched levels against its bias, the latch means and releasing edges being so proportioned and arranged relative to each other to clear the first latch releasing edge on movement of the latch means in a first direction, allowing movement of the control member means from the first latched level to the second latched level, and to clear the second latch releasing edge on movement of the latch means in the opposite direction thereafter, to allow continued movement of the control member means. I

2. The combination recited in claim 1 in which the latch means has a normal position in which control member means is latched at the first latching level and the latch means is clear of the second releasing edge, the latch means moving toward and beyond the second releasing edge into holding position for the second latching level before clearing the first releasing edge on movement of the latch means in the first direction.

3. The combination recited in claim 1 in which the latch means is formed of first and second relatively movable latch members, the first latch member holding the control member means in its first latched level and the second latch member releasing the control member means from its second latched level.

4. The combination recited in claim 1 including a reciprocating carrier for the latch means arranged to move the latch means in said first and second directions, the latch means being movably mounted on said carrier in a direction normal to the reciprocating movement of the carrier, and means for causing movement of said latch means on the carrier after it has been moved in said first direction to clear the first releasing edge.

5. The combination recited in claim 3 including a reciprocating carrier for the latch members, the first latch member being rotatably mounted on the carrier and also acting as a lifting means for lifting the control member means to its first latching position, and means for rotating said first latch member on the carrier after it has been moved in said first direction to clear the first releasing edge.

6. In an automatic reset timer including a reciprocating timing element, means for driving the timing element in timing direction including a timing motor and a clutch, said clutch comprising a driving gear and a driven gear and clutch operating means arranged to selectively engage or disengage said gears, spring return means for returning the timing element to a starting position when the clutch is disengaged, holding means independent of the clutch for preventing the spring return means from driving the timing element, and control means for the clutch and holding means, said control means being arranged to disengage the clutch and release the holding means in sequence, first releasing the clutch and then releasing the holding means.

7. The combination recited in claim 6 in which the clutch gears are arranged with one gear axially movable relative to the other for selectively engaging and disengaging the clutch, the holding means including latch means movable in the same direction as said axially movable gear.

8. The combination recited in claim 7 in which the control means is an axially movable pushbutton movable' in the same direction as the axially movable gear and latch means.

9. In a push to start timer, a cam having a drop off lobe on its periphery, said cam including axially movable and rotatable mounting means, means including a timer motor for rotating the cam, and outer flexible switch blade having one end fixed and having a free end adapted for engagement with the cam lobe, an inner flexible switch blade having one end fixed and a free end adapted for engagement with the cam lobe, both of said blades being biased toward the cam and the outer blade extending beyond the inner blade over the cam lobe causing the inner blade to move away from the outer blade when the cam rotates to the point where the cam lobe drops the inner blade, the cam and outer blade being arranged so that axial movement of the cam in one direction drops the outer blade from the side of the cam, causing the outer blade to move toward the inner blade in response to the axial movement.

10. The combination recited in claim 9 in which the cam is driven by the motor through a clutch and has a return spring for resetting the cam to a starting point when the clutch is disengaged, and means for disengaging the clutch when the cam is moved axially in said one direction for dropping the outer blade.

11. The combination recited in claim 10 in which the inner blade engaging the drop off of the cam lobe serves as a holding means for preventing reset of the timer on initial disengagement of the clutch, the parts being arranged so that the axial movement of the cam disengages the cam lobe from both blades.

12. The combination recited in claim 10 including holding means for preventing complete dropping of the outer blade when released by axial movement of the cam in said one direction, and means actuated by re turn axial movement of the cam for releasing the holding means.

13. The combination recited in claim 12in which the holding means is an axially movable latch arranged to move in unison with the axial movement of the cam, said latch being arranged to move under the outer blade before it is released by the axial movement of the cam.

Claims

1. In a control device, reciprocating control member means biased in one direction and having latch engaging surface means facing in Said one direction, said surface means having first and second latch releasing edges facing in opposite directions, reciprocating latch means movable normal to the latch releasing edges, said latch means and latch engaging surface means being constructed and arranged to release the control member means from first and second latched levels against its bias, the latch means and releasing edges being so proportioned and arranged relative to each other to clear the first latch releasing edge on movement of the latch means in a first direction, allowing movement of the control member means from the first latched level to the second latched level, and to clear the second latch releasing edge on movement of the latch means in the opposite direction thereafter, to allow continued movement of the control member means.

8. The combination recited in claim 7 in which the control means is an axially movable pushbutton movable in the same direction as the axially movable gear and latch means.

12. The combination recited in claim 10 including holding means for preventing complete dropping of the outer blade when released by axial movement of the cam in said one direction, and means actuated by return axial movement of the cam for releasing the holding means.

13. The combination recited in claim 12 in which the holding means is an axially movable latch arranged to move in unison with the axial movement of the cam, said latch being arranged to move under the outer blade before it is released by the axial movement of the cam.