US3237467A

US3237467A - Stepping mechanisms

Info

Publication number: US3237467A
Application number: US343304A
Authority: US
Inventors: Cartier Roger John
Original assignee: Controls Company of America
Current assignee: Controls Company of America
Priority date: 1963-02-13
Filing date: 1964-02-07
Publication date: 1966-03-01
Anticipated expiration: 1983-03-01
Also published as: GB1012075A; DE1948235U; FR1356395A

Description

' March 1, 1966 R. J, CARHER 3,237,467

STEPPING MECHANISMS Filed Feb. 7, 1964 INVETOR F er- UT 'ar'fier' AT-roRNEY United States Patent O 3,237,467 STEPPIN'G MECHANISMS Roger John Cartier, Vimercate, Milan, Italy, assignor to Controis Company of America, Melrose Park, Ill., a

corporation of Delaware Filed Feb. 7, 1964, Ser. No. 343,304 Claims priority, application France, Feb. 13, 1963,

3 Ciaims. (ci. 74-152) wheel, means for reciprocating the pawl to advance the vratchet wheel through a step of one tooth at each reciprocation of said reciprocatling means, and deactivating 'means for temporarily rendering the pawl inoperative to advance the ratchet wheel despite continued operation of the reciprocating means.

vThe ability to render the pawl inoperative to advance the ratchet wheel finds application, for example in domestic laundry appliances or dish washing machines having a programmed time switch incorporating a Stepping mechanism. In such a case, it may be desirable to halt the rotating parts of the time switch whenever the function of the machine is not time-controlled, for example whilst the wash water is being heated to a predetermined temperature. i 'i f More particularly the present invention provides a Stepping mechanism comprising a ratchet wheel, an actuating pawl spring biassed toward engagement with the teeth of the ratchet wheel, means for reciprocating the pawl to advance the ratchet wheel through a step of one tooth at each reciprocation, a pvoted lever having a projection thereon which, in the operative position of the lever, lies adjacent the ratchet teeth immediately approaching the pawl and prevents the pawl during its backward movement from passing over the next adjacent one of these teeth into the next intertooth space, spring biassing means acting on the lever to urge it in one direction, and control means responsive to conditions independent of the operation of the mechanism acting on the lever to urge it in the opposite direction, so that the projection on said lever is moved into and/ or out of operation in dependence upon said conditions.

Two embodiments of the invention will now be particularly described, by way of example only, with reference to the accompanying drawings in which:

FIGURE l is a view in elevation of a Stepping mechanism showing a ratchet wheel, an actuating pawl arranged to be reciprocated and to advance the ratchet wheel during each forward movement, a locking pawl for holding the ratchet wheel stationary during backward movement of the actuating pawl, and a mechanism for rendering the actuating pawl temporarily inoperative;

FIGURE 2 is a sectional view, along line II-II of FIGURE 1, of a heating resistance and of a bimetallic element forming part of the above-mentioned mechanism;

FIGURE 3 is a circuit diagram showing the connection of the heating resistance of the bimetallic element of FIGURES 1 and 2, with a thermostatic interrupter immersed in a liquid whose temperature determines the functioning of the mechanism; and

rice

FIGURE 4 is an elevation of a modified embodiment of the mechanism adapted to be controlled electromagnetically.

As shown in FIGURE l, the Stepping mechanism comprises a ratchet wheel 1 fixed on an axle 2 and arranged to advance stepwise in the direction of arrow F, under the action of the forward movement of a control tooth 3a of an actuating pawl 3, the pawl being pvoted at 4 on a reciprocally moving lever, not shown, and reciprocated by movement of the lever. The pawl is biassed by a spring 5 to urge it into meshing engagement with the teeth ofratchet wheel 1. The tooth 3a of the pawl is extended transversely parallel to the pivotal axis of the pawl for a reason which will be discussed below.

The ratchet wheel 1 is also engaged by a locking pawl 6 which holds it in position during backward movement of the actuating pawl and also assists in preventing overtravel of the ratchet wheel at the end of a step of advance movement. The looking pawl is pivoted at 7 and biassed by a spring 8 to hold a projection 6a of this pawl in engagement with the teeth of the ratchet wheel.

The actuating pawl 3 can, under certain conditions,

be prevented temporarily from advancing the ratchet wheel by preventing the pawl during its backward movement from engaging in the next intertooth space of the ratchet wheel 1. This is effected by means of a lever 10 pivoted at 11 for movement in a plane parallel to the plane of the ratchet wheel, this lever having towards its free end, a nose portion 10a of which the outer edge 10b is curved to match the curvature of the envelope of the teeth of the ratchet wheel and depending on the position occupied by the lever 10, lies either slightly outside the envelope of the teeth of the ratchet wheel, of inwardly of the circle defined by the bottom of the intertooth spaces of the ratchet Wheel.

A spring 12, wrapped around the pivot axle of the lever 10, has one of its ends in abu-tment with a stop 13, and its other end pressing against the lever 10. This spring maint'ains a bias on the lever 10 in a sense to ur'ge it into the position shown in the drawing, in which the edge 101) is slightly outside the envelope of the ratchet teeth, thereby preventing the control tooth 3a of the actuating pawl 3 from falling, during the backward movement of the actuating pawl, in-to the intertooth space situated immediately behind that which the pawl tooth occupied at the end of the last advance of the actuating pawl.

The lever 10 has at its free extremity a flattened tongue 10c which cooperates with the free end of a bimetallic element 14 whose opposite end is fixed adjacent the pivotal axis of the lever 10, this bimetallic element being Surrounded by a heating resistor 15.

Adjacent the middle of its length, the lever 10 has a recess with a bent-out edge forming a feeler projection 10d. This projection cooperates with a surface cam or lever stop 1a formed in the ratchet wheel 1, the surface cam having a recess or depression 1b at a point on its periphery.

The heating resistor 15 is connected in a circuit which can, for example, be controlled by a thermostatic interrupter 16 subject to the temperature of liquid L contained in a tank or cistern C.

In the modified embodiment shown in FIGURE 4, 'the clockwise movement of the lever 10, which is effective 'to render .the actuating pawl 3 operative again, iS controlled, not by a birnetallic element, but by an electromagnet 17 acting on an armature 18 provided at the end of one of the arm-s of a lever 19 pvoted on a fixed axis 20, the other arm of which acts on a pin 21 fixed to -the lever 10. The bias imparted to the lever 10 by the lever 19 is partially opposed by a return spring 22.

The embodiments of the invention described above function in the following way:

When, in the course of the rotation of the ratchet wheel 1, the projection d of the lever 10 falls into the depression 1b of lever stop or cam 1a, the lever 10 pivots in an anti-clockwise direction, under the action of spring 12. (The same result can be obtained in the absence of spring 12, by suitably disposing and adjusting the bias of, the bimetallic strip 14.) When this happens, the nose portion 10a covers the teeth of the ratchet wheel, and the edge 10b of 'this por-tion 10a lies slightly outside the envelope of the teeth of the ratchet wheel, thus covering the intertooth space into which the actuating pawl 3 would normally engage at 'the end -of the next backward movement.

As mentioned above, the tooth 3a of the pawl is laterally extended, and when the tooth 3a has ridden up the face of the ratchet tooth with which it is in engagement, further retreat of the pawl will cause the lateral extension of the pawl tooth 3a to slide on the edge 101i and so prevent the pawl tooth from dropping into the next intertooth spaoe. During the next advance of the pawl 3, the extension of .tooth 3a will slide in the opposite direction -on edge 10b` and at the end of this movement, the pawl tooth 3a Will drop back into the same intertooth fspace as it occupied at the beginning of the retreat movement so that no advance of the ratchet wheel will occur.

tIt is obvious that, to prevent the actuating pawl 3 forcing lever 10 to pivot in a clockwise direction, and thus to discontinue the temporary arrest of the advance of the ratchet wheel, it is limportant that spring 12, or in the absencel of the spring 12 the bimetallic element 14, or in the caseof FIGURE 4 the spring 22, should be strong enough to overcome the bias of the pawl.

When the interruptin-g means 16 close (eg. under the effect of an increase in the temperature of liquid L contained in tank C) current passes through the heating resistance 15, and the heat so produced raises the bimetallic element 14 to a temperature at which it acquires a warping force sufficient to cause the lever 10 to pivot in a- 'cloekwise direction and thus permit the Stepping mechanism to function normally under the reciprocating action of the pawl 3. When the lever pivots clockwise, projection 10d of the lever 10 is moved out of the depression 1b of the lever stop or cam 1a and must slide on the crcular surface of the cam, so that if the interrupter 16 opens, the lever 10 is no longer free to pivot into the position which renders the pawl 3 inoperative.

The lever 10 can be subjected to the action of control means other than spring 12 (or 22) or zthe bimetallic element 14. For example a sliding bolt could be used to coopera'te with the lever 10, to urge it into a position in which the pawl is rendered inoperative.

Although only two embodiments of the invention have been particularly described, it will be evident to those skilled in the art that other embodimen-ts can be construoted without departing from the scope of the invention as defined by the claims appended hereto.

I claim:

1. The combination with a Stepping mechanism of the type having a ratchet wheel engaged by a pawl adapted to be reciprocated to advance the wheel in a step-by-step manner, -of means for rendering 'the Stepping mechanism inoperative, comprisin-g, a mask movable between an inoperative position and an operative position in which it lies adjacent the ratchet wheel and is engageable by the pawl as the pawl is reciprocated whereby the pawl cannot engage ratchet teeth to effect advance of the ratchet wheel, a lever supporting the mask, means biasing the lever to move the mask to its operative position, a lever stop fixed on the wheel, a portion of the lever riding on the lever stop to hold the lever and mask in the inoperative position, said stop including a drop portion allowing the biasing means to move the lever to its operative position When the lever portion registers with the drop portion of the lever stop whereby the Stepping mechanism is rendered inoperative in a precise angular position of the wheel, and means for moving the lever to it-s inoperative position.

2. The combination of claim 1 in which the means for moving the lever to inoperative position comprises a bimetal and a heater therefor.

3. The combination of claim 1 in which the means for moving the lever to inoperative position comprises a solenoid.

References Cited by the Examiner UNITED STATES PATENTS 1,759,856 5/1930 Klein 74-151 2,'281,`262 4/ 1942 Breitenstein 74-149`X 2,343,549 3/1944 Groghan 74-150 2,797,795 7/ 1957 West. 3,059,488 10/1962 Daubenberger 74-152 X BROUGHTON G. DURI-IAM, Primary Examncr.

Claims

1. THE COMBINATION WITH A STEPPING MECHANISM OF THE TYPE HAVING A RATCHET WHEEL ENGAGED BY A PAWL ADAPTED TO BE RECIPROCATED TO ADVANCE THE WHEEL IN A STEP-BY-STEP MANNER, OF MEANS FOR RENDERING THE STEPPING MECHANISM INOPERATIVE, COMPRISING, A MASK MOVABLE BETWEEN AN INOPERATIVE POSITION AND AN OPERATIVE POSITION IN WHICH IT LIES ADJACENT THE RATCHET WHEEL AND IS ENGAGEABLE BY THE PAWL AS THE PAWL IS RECIPROCATED WHEREBY THE PAWL CANNOT ENGAGE RATCHET TEETH TO EFFECT ADVANCE OF THE RATCHET WHEEL A LEVER SUPPORTING THE MASK, MEANS BIASING THE LEVER TO MOVE THE MASK TO ITS OPERATIVE POSITION, A LEVER STOP FIXED ON THE WHEEL A PORTION OF THE LEVER RIDING ON THE LEVER STOP TO HOLD THE LEVER AND MASK IN THE INOPERATIVE POSITION, SAID STOP INCLUDING A DROP PORTION ALLOWING THE BIASING MEANS TO MOVE THE LEVER TO ITS OPERATIVE POSIWHEN THE LEVER PORTION REGISTERS WITH THE DROP PORTION OF THE LEVER STOP WHEREBY THE STEPPING MECHANISM IS RENDERED INOPERATIVE IN A PRECISE ANGULAR POSITION OF THE WHEEL, AND MEANS FOR MOVING THE LEVER TO ITS INOPERATIVE POSITION.