Note: Descriptions are shown in the official language in which they were submitted.
4~il6
TITLE
Electric time swich mcchanism
FIELD OF THE INVENTION
The invention relates to an elec-tric time switch -
mechanism which operates with an electrically heated
thermal expansion member9 for example a bimetallic member.
BACKGROUND OF THE INVENTION
Time switch mechanis~shave been proposed in which a
heated bimetallic member activates a mechanical ratchet
which, after heating the bimetallic member, releases a
component under spring tension which advances one step.
Thus, several heatlng cycles and cooling cycles of the
bimetallic member may be connected in succession, to pro-
long the switching time in relation to the mere single
heating of the blmetallic member. However,~ with- these
time switch mechanisms, the switching time can only be
adjusted in~steps and the mechanism is also relatively
; expensive and, like all mechanisms, is liable to break
down and is-exposed to wear.
SUMMARY OF THE INVENTION
An object of the invention is therefore to provide
~ . .
a time switch ~echanlsmiwhich is simple and compact with
an improved switching behaviour.
Aocording to the ~nvention there is provided an elec-
25~ tric time switch mechanl~m comprising a plurall-ty of units
.,: . . ~ : .
hc -2- ~
.
: ~ . - :. . . - . . , . . , .... : , .
' ' .... - : ' : .'.,.,. . . ' ' .': ,
. .
:. : : . .. . . ,. . : . ,:
;.,:' ', . ,'' .: ' ; - ,, .-, ~: ' ' ' "' : '
486
each having an operating thermal expansion memher, electrical
heating means for the thermal expansion member and a switch
which is activated by the thermal expansion member, the
units being connected in series in such a way that the
activation of a switch turns off the thermal expansion
member heating means of the associated thermal expansion
member and turns on that of the next following unit, the
switches remaining in the activated state after activation
and being resettable by external activation.
A cascade of thermal expansion members, for
example bimetallic members, is thus provided each of which
has a switch as the single mechanical member. An adjusting
device can preferably be provided for stepless adjustability,
by means o~ which adjusting device the position of at least
one, and preferably all, of the bimetallic members can be
adjusted in relation to the associated switch. The time
switch mechanism can thus be adjusted steplessly to a
period ranging from the shortest period up to the maximum
period.
~O The maximum period can be long since the heating
means of the bimetallic members may be designed so as to
be affected by mass to have considerable thermal capacity
or so as to be thermally inert. They also make the maxi- -
mum p riod available, unlike those in which the same bi-
metallic member is repeatedly heated, since the latter
, - 3 -
.. .. . . ..
- . . .. - . , , - - , .: .
: .
: :- -
. , , . :, , :
- : , . -,~, . - .
.. : - ' ~ :,: ., . ~ - . : " ' ,
are not completely cooled during the following cyc:Les.
Although bimetallic members are referred -to primarily
herein, the thermal expansion elements could -take some
other ~orm, ~or example they could be expansion rods,
tubes or the like, although bimetallic members are par-
ticularly preferred owing -to their large bending capa-
citites.
BRIEF DESCRIPTION OF TEIE DR~WINGS
Fig. 1 is a schematic circui-t diagram of a -time
switch mechanism according to the invention with three
units;
Fig. 2 is a plan view of an embodiment with two
units; and
Fig. 3 is a section along line III--III in Eig. 20
DESCRIPTION OF_PREFERRED EM~ODIM~NTS
Fig. 1 shows a time switch mechanism 11 comprising
three units 12, 13 and 14 each of which has an operating
bimetallic member 15, an associated electric heating
means 16 and a switch 17. Each operating bimetallic
member is provided with a compensation bimetallic member
18 for compensating the ambient temperature, by means of
which the position of the operating bimetallic member may
be adjusted in relation to the switch 17 upon which it
acts. All three units 12, 13, 14 are adjustable together
by means of a toggle 19.
~ .
hc
- ' ' ' :'' , ' . :
'.' ' .. . ~,': . -: ., . ''' ''' '' ~ -
..
, : ,~ - - - . .. . .
: , :; ': .
.'' ~ .
. - . , :
The switches 17 are snap switches which snap Lrom
the position shown for the units 13 and 1/1 in-to the
position shown ~or the unit 12 ancl remain in this posi-
tion until.they are forced back into the position shown
. for the units 13 and 14 by means of an external activa-
tion means which is indica-ted here as a manual press-
button activation means 20.
In the illustrated embodiment the heating means 16
o~ the operating bimetallic mem'ber 15 are joined to a
connection 21 of a domestic power supply network and
communicate with a contact 22 of the swi-tch 17. The
moving switch members 23 of the swi-tches 17 and the other
counter-contacts 24, (which are contac-ted after the
snapping of the switch member) are arranged in series in
15 such a way that a second connection-~ o-L the power supply
network communicates either with the contact 22 or, by
means of the switch, member 23 and the other counter-contact
24, with the switch member o~.-the next unit~
Fig. 1 al30 shows a power control instrument 25 ~or an
electric cooker plate 26 which has a snap switch 27. ,The
snap switch 27 is. activated by a bimetallic mem~er 28 heated .
~y ,a heating means 2~.. This is a pulsation power control
instrument known ~ se which supplies power to -the heatlng ,.'.
resistance 30 of the electric cooker plate in pulses of a : :
duratio~ which ~ari.es depending on the adjustment. The power
~` . ' ' ' - . ' ' ' ,
hc . _5_ .
., .
: ''. - ~ ' .
- ~ :' ' :- ' '
- : .- ,
con-trol instrument is also adjustable by means of the
toggle 19 by means of which the time switch mechanis~
is also adjuste~. The hea-ting means 29 of -the power
control instrument is switched by the ti~e switch mec-
hanism ll and is connected to the contac-t 24 of the last
unit lL~ of the time switch mechanis~. The other pole
of the heating means 2~ is connected via the swi-tch 27
of the power control instrument to the connection 21 so
that -the heating means of the power control instrument
switches itself.
The -time switch mechanism shown in Fig. 1 is designed
as a device for starting cooking with a power-controlled
cooker plate. With these cooker plates, the power is
adjusted manually and steplessly9 so that with adjustment
to a lower continuous cooking value which usually lies in
the order of magnitude below a quarter o:E the total power
of -the cooker plate, init-ial cooking would take a very
long time. The time switch mechanism ll is -therefore de-
signed to prevent pulsation, tha-t is to say the perlodic
0 turning on and off of the switch 27 of the power control
-
instrument 25, for a predetermined initial cooking period.
In the time switch mechanism according to the invention
the coupling between the adjustment of the power control
instrument and the time switch mechanism is advanta~eously5 such that for the dura-tlon of the inltial cooking phase the
hc -6- ~
.
~ .
,, ~ ' ~'' :: .' " ' '
. : , .: .
.- . - ~ ~ - ' , . ' . , ' ' . '
full power of the electric cooker plate according to the
adjusted continued-cooking power is appliecl. This takes
into consideration the fact tha-t the housewi~e, when
using a saucepan with large amount of contents requiring
a long initial cooking -time, normally also adjus-ts the
continued cooking power higher than with a smaller amount
of material to be cooked.
The -time switch mechanism shown in Fig. 1 operates as
follows. ~fter adjusting the desired power and thus also
the running time of the time switch mechanism by means of
the toggle 19, the pivotally mounted bimetallic members
composed of compensation bimetallic member 18 and opera-
ting bimetallic member 15 are brought into a predetermined
positlon in relation to their switches 17. Following the
previous-initial cooking procedure, all switches 17 were
in the position shown with the unit 12, that is to say the
switch ~embers 23 were connected to the contacts 2~, The
housewife now starts up the initial cooking operation by
A activating the press-button ~. The switch members 23 of
all three switches 17 are thus ~ade to snap over in an anti-
clockwise direction and are now in contact with the con-
tacts 22. The heating means 16 of the operating bimeballic
member 15 is thus ~irstly switched on with the unit 12 and
upon completion of the heating-up time of the bimetallic
member 15, which i9 preferably selected to be quite long,
hc ~7~
. . . . .
. - , . . . . . ...
. : . . : :'
'
.
. ~
36
the bimetallic member 15, in accordance with its ad-
justment by the adjusting device 31 ac-tivated by -the
toggle 19, brings the switch member ~3 of the switch
17 to snap into the position shown in Fig. 1. The
heating means 16 of the unit 12 thus becomes ~ree from
current and the operating bimetallic member cools down
again, but does no-t cause the switch member 23 to snap
back into the previous pOSitiOIl owing to -the action oi
the switch 17.
It should be noted that the heating means 16 of
the unit 13 is thus switched on and now also carries
out the operating cycle described above. A-fter switching
over the switch 17 of the unit 13, the unit 14 is started
up in the same way, and aft0r the unit lL~ has been swit-
ched, the heating means 29 of the power control instrument
25 receives current via the three switches 17 of the
time switch mechanism with their switch members 23 and 24,
and the normal pulsation operating of the power control
instrument is initiated.
It should there~ore~-be noted that with the time switch
mechanism according to the invention, the switching times
of the individual units 12, 13, 11~ add up so that consider-
able maximum periods are achieved. However, owing to the
adjustability of all $hree units, thls period can also be
adjusted to small values if desired. It would of course
hc -8-
~ ,
'~
8~
also be possible to make only individual uni-ts adjust-
able and allow some (the basic time, so to speak) -to
run cons-tantly. It is also feasible -to perform the
turning on operation by means of an al-ternative type of
activation (for example by means o~ a rotatable ~ember
or by means of cams) instead of using the pressure
activation means 20. Furthermore, it is -Leasible to
switch the switch 17 into its starting posi-tion as soon
as the toggle 19 is turned back to zero. In this case,
the time switch mechanism would run automatically with
each initial cooking operation,
Figs. 2 and 3 show an embodimen-t oi a time switch
mechanism 11~ which has only two units 12', 13~. It is
placed in a substantially square flat housing 32 which
is sealed with a cover 33 through which passes an adjus-
ting shaft 34 in the direction of its smallest dimension.
Owing to its flat struoture, -the time ~witch mecha-
nism lll is particularly suitable for use as an adaptor
switch for a power control instrument, that is to say a
power control instrument of the same basic dimensions
can be j,oined directIy on to its rear and thus be made
into a block with the tlme switch mechanism. The adjus-
ting shafts of both instruments can engage in each other.
- ~he adjusting shaft 34 can be rotated by the toggle
19. Furthermore, the toggle 19 may be'pressed towards the
hc -9-
~ ,, .
. ~ :
36
time switch mechanism so that it presses a tube 35 against
the force of a compression spring 36 .surrounding the adjust-
ing shaft. The tube is joined to a resetting cam 37 with
two oblique surfaces 38 for resett:ing the switch members 24
of the switches 17.
The operating bimetallic members 15 of the two
units 12', 13' are arranged parallel to each other on
opposite sides of the adjusting shaft 34, transversely
to its axis, and are pivotal about shafts 39 extending
parallel to the adjusting shaft. Swivelling levers ~1
are pressed on to an adjusting curve 42 fixed on the
adjusting shaf~ 34 by means of an angle piece and com-
pression springs 40O The swivelling levers are also
formed of bimetallic material and form the compensation
bimetallic members.
The heating means 16 of the operating bimetallic
members 15 are of large thermal capacity and are designad
with relatively wide heat coupling from the bimetallic
members, so that the time constants of the bimetallic
member are relatively large. The power can be supplied
to these heating means either by means of the shafts 39
or the compression springs 40 or by means of separate
moving supply lines.
The free ends of the operating bimetallic members
15 act ~y means of adjusting screws 43 which also form the
contacts 22 on the switch members 23, The members 23, as
: -- 10 --
.~.....
. .
- .
-:
, '' ~ . ' .
shown par-ticularly in Fig. 3, consis-t oL flat plates
having tapering edges which rest on a single-thrus-t
bearing 44 and on a C-shaped spring 45 which puts the
switch member 23 under an ini-tial compression. Each
spring 45 is supported at its other end on one oL the
single-thrust bearings 44. The switch members 23
co-operate with two fixed counter-contacts 24 which
ars separa-ted by an insulating wall and are arranged
back to back between the two switches 17 arranged in a
mirror image relationship. The switch members 23 each
have a projection poin-ting toward the centre of the
switch, on which projection bevelled tabs 46 are formed
which are able to co-operate with the resetting cam 37
when the switch member is snapped over into the position
in which it contacts its counter-contact 24. Since the
dead-centre of the bow-spring 45 is overstepped when the
switch member is snapped over to this position, the switch
member 23 does not spring back in-to the starting position
shown when the bimetallic member cools down and re-adopts
the outward-pivoted position shown.
. It should be noted that the design of the switches
17-is particularly simple. Thus, the bimetallic heating
means 16 make contact directly above the point of support,
that-is to say the adjusting screw 43, and no special
counter-contact is required. The construction of the time
'
hc
. ,, : .. -
- .
: ~ . . . . ..... .
. . - , ~ . :
. .. : , -,
. : , :
486
switch mechanisl~ is simple, requires -~ew mechanical and
electrical components and is compac-t.
Although in the embodiment shown in Figs. 2 an~ 3,
a successive switching Or two units ensures a sufl`icien-t
period Ior initial cooking operations, it is possible to
produce other desired period by means o~ a larger number
oI units, Ior example iI the time switch mechanism is
used for other purposes apart Irom controlling the initial
cooking time of electric cooker plates.
-
.
: , .
'.
. .... .
.. / , ..
hc -12- - -
.
~ . '
~ ' ' .
' ' ' ' ''
.
. - .,,: ' '
