Step-by-step timer switch activation system for program control devices

Abstract: The system incorporates advantages that comprise providing the positioning ratchet (23) with a shaft (25) about which an elevating lever (12) can swing which can take up an active and an inactive position such that when the cogs (10) on the block of program cams (15) elevate the ratchet (23), the elevating lever (12) takes up the active position and is thereupon returned to its inactive position when its free end (32) is moved by a rotatory boss (31) integral with the excentric cam (1), dragging with it in this latter movement the anti-return ratchet (15), causing the latter to draw away from the holding cogs (34) on the timer cam (6) at a time when the catch (4) on the driving pawl (3) is also drawn away from the same, allowing the timer cam to be reset.

Description: The present invention relates to a step-by-step timer switch activation system for program control devices, of the kind based in a rotary cams block, for honehold appliances. BACKGROUND OF THE INVENTION One step-by-step timer switch activation system for program control devices is known, (cf. EP-A-0 199 568 which belongs to the prior art according to Article 54(3)EPC) having a system comprising two subsystems that can act jointly or separately, with one of which subsystems time intervals of a duration equivalent to the turning period of the fast cams block or fractions thereof can be obtained, and with the second of which any of the time intervals of the first subsystem can be multiplied by two preset factors. This known device incorporates: a block of program cams drived in rotation by a motor shaft, having an integral drive cog ring; a timer cam formed with a exterior drive cog sector and a interior holding cog sector, having the same rotation axle as the cams block; a rotary eccentric cam which provides to a coaxial driving pawl with a steady reciprocating motion, having a peripherical nose; driving and activation means including said swivel driving pawl provided with a catch which engages both said integral cog ring and said drive cog sector; a three interior levels cam profile rotating with the cams block, and a time interval selector lever pivotable around an axle distanced from the cams block, provided with a cam follower which is borne by the interior cam profile and with a bolt abutment; timer cam holding and resetting means including a swivel positioning ratchet engaging the cogs of the cams block; and an anti-return ratchet provided with a holding catch at one of its ends engaging the holding cogs of the timer cam. The risk of the known system lies in that when the control device shaft is turned by hand to select a working program of the appliance or to eliminate a part thereof the block of program cams is incorrectly positioned between two stable program positions, it might stay there permanently, unable to continue the block advance, whereupon the programmed appliance with the control device will run the working stage (heating, centrifuging and so forth) corresponding to such position endlessly, until the user changes the incorrect position. DISCLOSURE OF THE INVENTION The activation system object of the invention provides a solution, so that even if such incorrect position of the selector, the block of program cams happens, it shall not be permanently stopped in the said position, allowing the driving mechanisms to act upon the same and advance it towards a stable position so that it may thereafter resume its program operation. The step by step timer switch activation system provided by the invention further comprises: - timer cam holding and resetting means including said positioning ratchet whose free end has an integral spindle; an elevating lever provided with a boss located between their two ends, one of them being a free end, and the other coupled to said spindle on the positioning ratchet, for being displaced outards and inwards the cams block, and the other end; said antireturn ratchet, provided with a holding catch at one of its ends engaging the holding cogs of the timer cam, the other end lying beyond reach of said boss on the elevation lever; a plurality of helical springs, each one associated to one of said lever or ratchets; timer cam resseting abutments including two adjacent ramp surfaces, being radially located on the timer cam (6) and a bolt on the selector lever; said peripherical nose on the eccentric cam, which upon turning thrusts the free end of the elevating lever going it away from the cams block, whereupon the anti-return ratchet can, urged by its associated spring, engage the holding cog sector of the timer cam. A second advantage of the activation system provided by the invention lies in that though its actuation is linked to the swinging of the positioning ratchet by cogs integral with the block of program cams, the strength with which the same impinges upon the latter is only slight, thereby facilitating the obtention of low torque values of the said block of program cams if so desired. When the block of program cams moves one step forward by hand or automatically, the cogs integral with the latter, in a known way cause a positioning ratchet to rise and fall with respect to the driving pawl and the antireturn ratchet. This movement in turn causes an elevating swivel lever to be reset, the free end of which lever is subsequently thrust by the eccentric cam with a period being less or equal to the duration of the shortest time interval, so that displacing the elevating lever counter the reset travel direction that means outwards the cams block causes the antireturn ratchet to disengage the timer cam in the case when the driving pawl is also disengaged therefrom, whereupon the timer cam is free to be reset. The timer switch shall then be able to work again, according to the parameters corresponding to the program position of the block of program cams. In addition to what the known timer switch provides, a second possibility has been provided by the invention to drive the timer cam, according to which when the selection lever follower is on the selection cam profile of narrowest or medium level or radius, the resetting abutments define a partially advanced position for the timer wheel, the first counting cog thereof lying within reach of the respective catch of the driving pawl. DESCRIPTION OF THE DRAWINGS Figure 1.- Is a view of the system object of the invention, showing the timer cam reset mechanism remaining inactive. Figure 2.- Is a view of the system of fig. 1 just as it is changed to a condition whereupon the timer cam reset mechanism is ready for resetting Figure 3.- Shows the timer cam and the driving pawl in the position beginning the timing of a long duration interval Figure 4.- Shows the system in an intermediate step position at the end of a timing interval according to fig. 3 Figure 5.- Shows the return mechanism of the timer cam in a reset position. Figure 6.- Shows the system with the timer cam released from the ratchet to be reset. PREFERRED EMBODIMENT OF THE INVENTION With reference to figures 1 to 6 the eccentric cam (1), upon turning continuously about its axle (2) provides the driving pawl (3) with a reciprocating motion such that its catch (4) can cause either the block of program cams (5) or the timer cam (6) to advance step by step. In the case shown in figure 1, since the cam profile follower 7 is borne by the cam profile level (9) of widest radius, the timer cam (6) lies beyond reach of the catch 4 which can therefore only engage the cogs (10) integral with the block of program cams (5). On the other hand, the timer cam (6) reset mechanism remains inactive since the boss 11 on the elevating lever (12), which is at its position furthest from the timer cam (6), with respect to the latter lies behind the end of the anti-return ratchet (15). When the system changes to a long-timing position, as shown in figure 2, the cam profile follower (7) is placed at a medium level (16) or narrow level 17, causing the selection lever (8) to swing about its axle 18, overcoming the force of the spring (19) that opposes such movement. When the follower 7 moves to either of these two levels 16 or 17 the abutment (38) integral with the selection lever (8) is also displaced, which in turn impinges upon the ramp surface 21 on the timer cam to move the latter to a rotation position that is slightly more advanced than that corresponding to the position of basic and short interval timing of figure 1. When the block of program cams (5) moves one step forward, the boss (11) on the elevating lever (12) takes up, as shall be explained hereinafter, its active position, before the end (14) of the anti-return ratchet (15) to move soon after, as shall also be explained hereinafter, to the position shown in figure 1. The movement of the boss 11 on the elevating lever from the position shown in figure 2 to that shown in figure 1 is aimed at resetting the timer cam (6) but as in this case it is already in its starting position, it bears no effect upon the same. When the driving pawl moves back, it meets the timer cam somewhat advanced shown in fig.3, as described before, and therefore the catch 4 engages with the first driving cog 20 on the timer cam that prevents the catch (4) from reaching the cogs (10) on the block of program cams (5), which is when the timing stroke begins, operating hereafter in the same way as the known timer switch activation system. When a deeper space (21) in the driving or counting cogs sector 22 on the timer cam (6) comes within reach of the catch 4 as shown in, figure 4, the catch (4) can enter into the same, engaging the cogs 10 on the block of program cams. Figure 4 shows the system in an intermediate step position, that means between two program stable positions, where the positioning ratchet (23) is superposed upon the cogs 10 on the block of program cams. The elevation of the positioning ratchet cogs 23' from the bottom to the tip of the cogs 10 causes the elevating lever (12), which is coupled to the spindle 25 integral with the positioning ratchet (23), to move in the direction of the arrow 24. This displacement causes the boss (11) to be drawn away from the end (14) of the anti-return ratchet, allowing the elevating lever to move from the position shown in figure 1 to that shown in figure 2, by means of a spring (26) that urges the same towards the latter, the system then moving forthwith to the position shown in figure 5. The spring 39 urges the positioning ratchet 23 to engage the cog ring 10. As is shown in Figure 5, after the block of program cams (5) moves one step forward, the catch (4) on the driving pawl shall have been disengaged such condition being caused jointly by the rotation of the eccentric (1) the spigot 27 integral with the bearing plate 28 of the timer switch driving an internal profile (29) of the driving pawl (3), overcoming the force of the spring (30) that tends to engage the catch. If rotation of the excentric (1) continues, the peripherical nose (31) therefrom pushes the free end 32 of the elevating lever towards the outside and the movement of the boss (11) is transmitted to the end 14 of the anti-return ratchet, which turns drawing its catch (33) away from the holding cogs 34 on the timer cam (6), which is released to be reset, given that the catch (4) on the driving pawl has also been drawn away. Timer cam 6 return to zero comes about by traction of the spring 35 that causes the timer cam to turn as far as the ramp surface 36 or the surface, depending upon whether the next step is long-timing or otherwise, abuts against the bolt abutment 38 on the selection lever (8). Finally, the boss 11 overruns the end 14 of the anti-return ratchet, so that both take up the inactive position shown in figure 1. The spring 40 urges the antireturn ratchet catch 33 to engage the holding cogs 34.

Claims: Step by step timer switch activation system for progam control devices of the kind providing at least a time interval multiplication mechanism, comprising a block of program cams (5) drived in rotation by a motor shaft (13), having an integral cog ring (10); a timer cam (6) formed with a drive cog sector (20,21,22) and a holding cog sector (34) having the same rotation axle (13) as the cams block (5); a rotary eccentric cam (1) which provides a steady reciprocating motion to a coaxial driving pawl (3), and has a peripherical nose (31); driving and activation means (1,3,4,8,9,12,16,17,27) including said swinging driving pawl (3) provided with a catch (4) which engages both said cogs (10) of the cams block (5) and said drive cogs (20,22) of the timer cam (6); and a time interval selector lever (8) pivotable around an axle (18) distanced from the cams block, provided with a cam follower (7) which is borne by a three interior levels (9,16,17) cam profile rotating with the cams block, and also provided with a bolt abutment (38); timer cam holding and resetting means (11,12,15,23,31 to 38) comprising a positioning ratchet (23) pivotable around the same axle (18) as the time selector lever (8), engaging said cog ring (10) of the cams block, and whose free end has an integral spindle (25); an elevating lever (12) provided with a boss (11) located between their two ends, one end being coupled to said spindle (25) on the positioning ratchet (23), and the other being a free end (32), which swings outwards and inwards the cams block (5); an antireturn ratchet (15), at one of its ends provided with a holding catch (33) engaging the holding cogs (34) of the timer cam (6), the other end (14) lying within reach of said boss (11) on the elevation lever (12); a plurality of helical springs (19,26,30,35,39,40), each one associated to one of said pawl (3), levers (8,12), ratchets (15,23) and timer cam (6); timer cam resetting abutments including two adjacent ramp surfaces (36,37) being radially located on the timer cam (6) and a bolt (38) on the selector lever (8). Step by step timer switch activation system according to claim 1, wherein the positioning ratchet (23) disengaging the cog ring (10) each time the cams block (5) turns, hauls the elevating lever (12) bringing it away and near the antireturn ratchet (15) in order for said boss (11) to be separated from the end (14) of the anti-return ratchet (15), whereupon the elevating lever (12) is positioned by means of its associated spring (26) closest to the cams block (5), to enable the the timer cam (6) for returning to zero. Step by step timer switch activation system according to claim, wherein said rotary peripherical nose (31) on the eccentric cam (1) thrusts the free end (32) of the elevating lever (12) moving it outwards the cams block (5), and before ending this stroke, the boss (11) positions itself beyond reach the end (14) of the anti-return ratchet (15), whereupon the same can engage the holding cog sector (34) of the timer cam (6), urged by its associated spring (40). Step by step timer switch activation system according to claim 1, wherein the timer cam (6) has two lateral ramp surfaces (36,37), which in combination with said bolt abutment (38) on the selector lever (8) and with the interior cam profile (9,16,17) define two rest conditions of the timer cam (6) differentiated in its rotation advance, the drive cog sector (20,22) lying beyond reach of the catch (4) on the driving pawl or its first driving cog (20) being engaged by the catch (4).

Inventors: CHAUVIGNE MICHEL, LEIBAR GURIDI JOSE CRUZ, CHAUVIGNE, MICHEL, LEIBAR GURIDI, JOSE CRUZ, Leibar Guridi, José Cruz
Applicants: FAGOR S COOP LTDA, FAGOR, S.COOP. LTDA.
Application year: 1992
Main classification: G05B19
IPC codes: H01H43