US2553846A

US2553846A - Timer construction

Info

Publication number: US2553846A
Application number: US42862A
Authority: US
Inventors: George S Clemens
Original assignee: Individual
Current assignee: Individual
Priority date: 1948-08-06
Filing date: 1948-08-06
Publication date: 1951-05-22
Anticipated expiration: 1968-05-22

Description

y 22, 1951 e. s. CLEMENS 2,553,846

TIMER CONSTRUCTION Filed Aug. 6, 1948 W 1, 24g 24 2a 266 42a Patented May 22, 195i UNITED STATES PATENT OFFICE 8 Claims.

My invention relates to timers and like devices wherein an electrical circuit condition is established for a predetermined time interval or while a predetermined event takes place.

It is frequently desirable to provide mechanisms wherein an operation may be manually initiated and will continue for a predetermined time thereafter. Thus, in hand drying machines used in public washrooms, it is desirable to provide a single push button operable to initiate operation of the air heating elements and the blower. However, it is also necessary that the heating elements and the blower be deenergized after a predetermined period of time to avoid the chance of continuous operation of the mechanism when it is not in fact being used.

Heretofore, the timer mechanisms for blowers and like devices have included circular cams driven by timer motors and which have a peripheral notch in which the cam follower falls to deenergize the unit. While this limits the time of operation of the unit, it, is frequently necessary to hold the manual start button for a considerabl time period before the mechanism positively starts. More frequently, users unacquainted with the device will repeatedly press the starting button, thereby causing the motor to execute 1 This latter operation is highly undesirable for it causesa number of partial starts in succession.

the motor to operate for long periods under sub .stantially locked motor conditions with the consequent motor overheating and blowing of fuses. It is therefore a general object of the present invention to provide an improved mechanism for use in timing devices.

A further object of the present invention is to provide an improved timer mechanism which'is Figure 2 is a fragmentary portion of Figure l 1 showing the timer in the beginning of an operating cycle;

Figure 3 is a cross-sectional view through axis;

III-III, Figure 2; and

Figure 4 is a fragmentary cross-sectional view through axis IV-IV; Figure 2.

As shown in Figure 1, the timer of the present I invention includes a timer motor l0 which operates to rotate shaft i2 'in the clockwise direction when energized at terminals Ilia and 1b.. The

shaft 52 receives the cam 14 and the holding member lt'which operate as described in detail hereafter.

The cam follower indicated generally at I8 rides on the cam Hi.

manual start button 22 positioned'to swing but-t ton Ell free of cam i i-when 'depressed as'indicated by arrow 22a, Figure 2. The cam follower also includes a pair'of contact elements 24 'and' 26 which serve to establish an electrical circuit" when button 28 is in. the raised position 'of Fig ure 2.

The contacts 2% and Ed'serve to establish. an

electric circuit to the drier motor M, the heater These element H, and to the timer motor Ill. circuits may be traced from the terminal .28 to the common connection of motor M, heater H' and timer it, through these elements. to the upper conducting leaf 25a which extends to'contact button 2t.

extends from'spring' 32 to .the upperrarm 26a The ends of. that which sustains contact 26. spring 35 are attached to spring 32 .and arm Eta by the protuberances 26b and 32a, Figure 4,. which are received in matingholes' in the end.

portions of spring 36.

When button 20 rides in notch I la or 14b of."

cam Hi, spring 32- tends to straighten, thus'shifting the outer end of the spring tfiz-in the downward direction below the tipofithe arm 26a; The spring 35 thereupon exerts an upward component of force on arm 25a andlifts that arm to a spaced position relative to button 24 as shown.

in Figure 1.

When spring 32 is flexed upwardly as shown. in Figure 2, the outer end of spring. 36. swings.

to a position above the tip of arm 2611. This causes spring to exert a downward component of force on arm. 26a and thereby flexes arm.- Zlia to the contact making. position of. Figure 2.

Arm serves to back uparm Eta-to limit the forces exerted thereon.

This followerincludes a button positioned to rideon cam" Mandi a:

From button 26, the circuit may." be traced to button 2 3 and through conducting:

The cam I4 is held on shaft I 2 by the hub 40, Figure 3, which is retained on that shaft by the set screw 40a. The hub 4!] snugly receives the cam I i to cause rotations of the latterin accord with the rotations of the shaft. The hub 40 further has a reduced portion defining an annular wall. The holding member It is loosely received on this reduced portion and is thus held against the face of the cam l4.

Spaced pins 42 and 42a extend in the axial direction from cam [4 to define limits of motion of the holding member 16. The pin 44 extends axially from the holding member l6 in like fashion to receive spiral spring 46 which is anchored at its opposite ends to pin 42. Spring 46 acts to urge holding member IS in the clockwise direction relative to cam [4, thereby urging it to the registered position relative to notches Ida and Mb as shown in Figure 2.

The holding member It acts to hold arm 32 in the position of Figure 2 when button 22 is depressed. This results from the action of spring it which snaps member I6 to that position when member 26 is swung free of the periphery of the cam M.

The member [6 extends a slight distance beyond the periphery of the cam [3 and thus engages the member 20 as the cam rotates. Consequently when the motor ID is once set in motion, it continues to rotate cam I4 until one half revolution is executed, at which time the mem her 263 will engage the forward edge of member [6. Further rotation of the cam I l causes holding member IE to swing in the counter-clockwise direction relative to cam 14, thereby uncovering notch Ma or Mb as shown in Figure 1 and permitting

contacts

24 and 26 to open, thus stopping motor l0.

From the foregoing description it will be apparent that I have provided a unit capable of actuating heater H and blower motor M for a preselected time determined by the speed of rotation of motor H) and the angular distance between notches la and Mb. Moreover, this operation is achieved by a single actuation of the button 22 and there is no tendency for the unit to stop after actuation due to failure of cam follower 20 to ride out of notch Ma or l lb during the time button 22 is actuated.

Moreover, it will be apparent that the time period may be preselected relative to the motor speed by appropriate choice of notches [4a and Mb. Commercial timer motors are standardized at a speed of one revolution per minute so that by use of the two notch cam shown these motors can be utilized to establish a 30 second running time of the unit. This correspondingly reduces the expense of the structure.

While I have shown and described a particular embodiment of my invention, it will, of course, be understood that I intend by the appended claims to cover all variations and modifications coming within the true spirit and scope thereof.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. In a timer switch of the type wherein a cam having a notch is rotated at predetermined speed when an electric circuit condition is established and a cam follower rides on said cam to establish said condition when it rides out of said notch, the improvement which comprises a holding member movably mounted relative to said cam and in one position adapted to overlay substantially the entire extent of said notch to define a cam surface to hold said follower free from said notch, and means operable to urge said member to said one position to establish positively said circuit condition when said follower is swung free of said cam, said holding member having portions for engagement with said follower to move said member out of said one posi tion as said cam rotates.

2. In a timer switch of the type wherein a circular cam having a peripheral notch is rotated at predetermined speed when an electric circuit condition is established and a cam follower rides on said cam to establish said condition when it rides out of said notch, the improvement which comprises a holding member mounted against the face of said cam for swinging movements about the axis of the cam and operable in one position to overlay substantially the entire extent of the notch to hold said follower free from said notch, and spring means operable to urge said member to said one position to establish positively said circuit condition when said follower is swung free of said cam, said member having a portion extending radially beyond said cam to be engaged by said follower to swing said memher out of said one position as said cam rotates.

3. A positively setting cam mechanism for a device of the type wherein an operation progresses when a cam follower assumes one p351" tion and stops when the follower has a second position, said mechanism comprising means defining a cam surface to receive said follower and operable to hold said follower in said first position and having a notch to receive said follower to permit said follower to move to said second position, a holding member movably affixed to said means and operable in one position to define a cam surface overlaying substantially the entire extent of the notch to hold said follower out of said notch, and means biasing said holding member to said one position, said holding member having portions to engage said follower to move said member out of said one position as said cam rotates.

4. A cam for a timer switch comprisinga disk having a peripheral surface with an inwardly extending notch to receive a cam follower, a holding member mounted for rotations relative to said disk and about the axis of the disk, said member being adapted to register with said notch when in one position to define a cam surface overlaying substantially the entire extent of the notch to hold said cam free of said notch, spring means operable to urge said member to said one position and stop means operable to hold said member in said one position against the action of said spring means, said holding member defining a wall extending from said peripheral surface to engage said follower and swing said member out of registry with said notch.

5. A timer mechanism comprising in combination, a cam having a peripheral surface with a notch, a cam follower adapted to ride on said surface and to establish a first circuit condition when on said surface and a second circuit condition when in said notch, means operable to rotate said cam when said first circuit condition is established, a holding member mounted for movements about the axis of the cam to registry with said notch to define a cam surface overlaying substantially the entire extent of the notch for holding said follower out of said notch, spring means operable to bias said member to said registered position, and stop means operable to hold said member in said registered position against the bias of said spring means, said member defining a catch element to engage said follower and swing said member out of registry with said notch as said cam rotates.

6. A timer mechanism comprising in combination, a cam having a peripheral surface with a notch, a cam follower adapted to ride on said surface and to establish a first circuit condition when on said surface and a second circuit condition when in said notch, means operable to rotate said cam when said first circuit condition is established, a holding member mounted for movements about the axis of the cam to registry with said notch to define a cam surface overlaying substantially the entire extent of the notch to hold said follower out of said notch, and spring means operable to bias said member to said registered position, said member defining a catch element to engage said follower and swing said member out of registry with said notch as said cam rotates.

'7. A cam for use with a follower, said cam comprising in combination a disk having a pair of diametrically opposed peripheral notches, a holding member mounted adjacent the face of said disk for movements about the axis of the disk, said member having diametrically opposed portions for registry With said notches to define cam surfaces overlaying substantially the entire extent of the notches for holding said follower out of said notches, spring means operable to urge said member to registry with said notches, and stop means operable to hold said member in registry against the action of said spring means, said member having portions extending beyond said disk for engagement with said follower to swing said member out of registry when said disk is rotating.

8. A cam for use with a follower, said cam comprising in combination, a disk defining a cam surface having a pair of diametrically opposed notches, a hub for said disk defining a wall in spaced relation with the face thereof, a holding member interposed between said wall and said face and loosely fitted on said hub, said member defining a pair of diametrically opposed cam portions operable to overlay substantially the entire extent of the notches to hold said follower out of said notches when said member is in registry therewith, a pair of axially extending stop elements mounted on said disk and defining a limited range of movement of said follower, one extreme of said range being in registry with said notches, and spring means operable to urge said member towards said extreme of movement, said member extending beyond the periphery of said disk to define a wall for engagement with said follower to swing said member out of registry with said notches as said cam rotates.

GEORGE S. CLEMENS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,909,138 Vollmer May 16, 1933 2,297,090 Weaver Sept. 29, 1942 FOREIGN PATENTS Number Country Date 211,368 Switzerland Nov. 18, 1940