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BACKGROUND OF THE INVENTION
The invention relates to an electrical switch that includes an actuator
movably guided in a switch housing and carrying contacts for making or
breaking an electric connection with stationary contacts mounted in the
switch. The actuator has a surface which extends parallel to the actuator
movement and in which there is provided a guide curve having at least two
latching positions. A pin rides in the curve upon movement of the actuator
such that the actuator can be locked in on and off positions in the
respective latching positions of the guide curve according to the preamble
of patent claim 1.
Such electrical switches are used to switch electrical devices on and off
by pressure operations the actuator locking home in the respective switch
position. These switches are used, in particular, for household
appliances, such as vacuum cleaners and the like.
Such an electrical switch whose actuator, which is movably guided in the
housing and can be brought into two latched positions by means of
pressure, has been disclosed in German Offenlegungsschrift 2,217,690. In
the first latched position, the contact bridges arranged on the actuator
do not touch the break contacts located in the housing, so that the switch
is in the off position, while in the second latched position the contact
bridges touch the break contacts, as a result of which the switch is
located in the on position.
In order to fix the latched positions, this electrical switch has two
identical heart-shaped guide curves arranged on mutually opposite sides of
the actuator. Located on the sides of the housing assigned to the guide
curves are two slots in which a gudgeon of a bolt engages. A further pin
of the bolt engages, in turn, in the assigned guide curve, as a result of
which the latched positions of the switch are fixed by the interaction of
pin and guide curves.
It has proved to be disadvantageous in this switch that jamming of the
gudgeon in the slot of the housing, or of the pin in the guide curve can
occur in the event of tilting of the actuator. In both cases, there is
then the risk of a lack of latching in the on or off position. This
uncertain switching performance means, in turn, a defective operational
reliability for the switch in question. Moreover, this switch is difficult
to install because of the two bolts which are to be simultaneously
inserted on the two sides of the housing.
SUMMARY OF THE INVENTION
It is the object of the invention to develop the switch mentioned at the
beginning in such a way that reliable notching in the on and off positions
is ensured and no maloperations occur.
This object is achieved by the invention, according to which the electrical
switch has a switch housing movably receiving an actuator that carries a
movable contact cooperating with a stationary contact held in the switch
housing. The actuator has two opposite surfaces on which two curve guides
of different configuration are provided. Two pins, supported in the switch
housing, ride in the respective guide curves as the actuator moves. The
two pins are interconnected by means of a connecting element which is
elastically deformed by forces derived from the unlike guidance of the two
pins by the guide curves. The guide curves determine a latched on position
and a latched off position for the switch.
In a further embodiment of the switch according to the invention, the
connecting element coupling the two pins engaging in the guide curve
consists of a U-shaped bracket which is inserted into a corresponding
receptacle in the base of the housing. It is therefore possible for the
switch to be particularly simply installed by firstly providing the base
with the break contacts, placing the bracket into the receptacle, and then
setting up the actuator with the switching contacts in such a way that the
pins on the U-shaped bracket engage in the guide curves and, finally, the
housing is pushed over the actuator and the base, said actuator locking
home in corresponding latching or snap connections on the base. In
addition, given the use of the U-shaped bracket it is possible to
eliminate an otherwise necessary additional spring element which serves as
connecting element.
In a further advantageous embodiment of the invention, the terminals for
the switch are provided with a U-shaped part which serves as a break
contact surface. The U-shaped part is plugged onto correspondingly shaped
webs in the base. As a result, the U-shaped part can be arranged in two
different positions, so that the terminals can optionally emerge from the
housing both downwards and to the side.
The advantages achieved with the invention consist, in particular in that
the switch has a very low overall volume, and yet has a switching
performance that is very operationally reliable and completely excludes
maloperations. The actuator is also always positioned vertically in the on
position, as a result of which tilting is reliably prevented. Because of
the connecting element which couples the pins engaging in the guide
curves, it is possible to eliminate complexly shaped bolts and associated
slots in the housing for receiving the bolts. Rather, it is possible to
select simple pins and connecting elements which can be produced from
wire, so that the switch is cost effective and also simple to install. The
possibility of arranging the terminals both downwards and at the side
provides manifold possibilities for using the switch according to the
invention, depending on the desired aim.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows a side view of the switch according to the invention,
FIG. 2 shows a section along the line 2--2 in FIG. 1,
FIG. 3 shows a section along the line 3--3 in FIG. 2,
FIG. 4 shows a section along the line 4--4 in FIG. 2,
FIG. 5 shows a section along the line 5--5 in FIG. 4,
FIG. 6 shows a section along the line 6--6 in FIG. 4, the metal parts being
represented unsectioned in FIGS. 2 to 6 for the purpose of better
illustration,
FIGS. 7 to 13 show sketches of the principle of the mode of operation of
the switch in various actuating positions,
FIG. 14 shows a section through a further design variant for the switch,
FIG. 15 shows a section through yet another embodiment, and
FIG. 16 shows a section along the 16--16 in FIG. 15.
DESCRIPTION OF THE PREFERRED
As emerges from FIG. 1, the electrical switch 1, which can be actuated by
pressure, is constructed as a double-pole on/off switch and can be latched
in the on and off positions, has a housing 2 and a base 5 carrying the
electrical terminals 12. Integrally formed on the base are webs 44 which
are shown in more detail in FIG. 4 and have guide grooves in which
corresponding counter parts 45 in the interior of the housing 2 engage. As
a result, when installing the switch 1 the housing 2 can be pushed onto
the base 5 and detachably secured to the latter by means of latching or
snap connections known per se. Located on the housing 2 is a neck 3 which
serves as a guide for an actuator 4.
As may be seen from FIGS. 2 and 3, the actuator 4 can be moved against the
pressure of a spring 6 which is located in a receptacle 7 arranged on the
base 5. Two contact bridges 8, which are fitted with switching contacts 10
are elastically arranged on the actuator 4 by means of springs 9. The
switching contacts 10 of the contact bridges 8 can be brought through
movement of the actuator 4 in the event of the exertion of pressure in the
direction of the arrow 46 (see FIG. 1) to bear against the break contact
surfaces 11 of the electrical terminals 12, as a result of which an
electrical connection is produced between the terminals 12, and thus the
on position of the switch 1 is produced. When the actuator 4 is located in
the off position of the electrical switch 1 shown in FIGS. 2 and 3,
because of the spring pressure of the spring 6 the switching contacts 10
of the contact bridges 8 are at a certain distance from the break contact
surfaces 11, so that the electrical connection is broken.
The electrical switch 1 has one latched position each in the off and in the
on positions. The latched position in the off position is fixed due to the
fact that because of the pressure of the spring 6 the actuator 4 with the
shoulders 13 bears against corresponding surfaces of the neck 3 in the
interior of the housing 2. Provided on the actuator 4 in order to fix the
other latched position in the on position are two guide curves 14, 15 of
differing shape on mutually opposite surfaces extending parallel to the
direction of movement.
As can be gathered from FIGS. 3 and 5, the first guide curve 14 consists of
a surface 16 which is raised on the actuator 4 and whose outer contour has
the shape of a heart, which is why the surface 16 is also called a
switching heart. The second guide curve 15 is formed by a surface 17 which
is sunk on the actuator 4 and in the center of which an elevated,
triangular surface 18 is located, and this is to be seen by comparing
FIGS. 3 and 6. As emerges, furthermore, from FIG. 6, the inner contour of
the guide curve 15 is essentially constructed in the shape of a heart.
Engaging respectively in the two guide curves 14 and 15 is a pin 19, 20.
These two pins 19, 20 are coupled with one another by a connecting element
21. The connecting element 21 has in this exemplary embodiment the shape
of a U-shaped bracket and is placed in a receptacle 22 on the base 5. As
is to be seen in the present exemplary embodiment, the pins 19, 20 and the
connecting element 21 can be produced from one piece by bending a spring
wire. It is expediently possible to select a round cross section for the
spring wire, but any other cross-sectional shape is also conceivable.
The mode of operation of the switch 1 according to the invention is shown
in more detail in FIGS. 7 to 13, in which the guide curve 15 is to be seen
in top view, and the guide curve 14, which is located, covered per se, on
the opposite surface of the actuator 4, is represented by dashes. The two
pins 19, 20 are represented by circles, and the connecting element 21 is
omitted for reasons of clarity.
The latched position corresponding to the off position is to be seen in
FIG. 7. The two pins 19, 20 are located opposite one another in the same
position, which is approximately situated in the central plane of the
actuator 4 below the two guide curves 14 and 15. As already mentioned,
this latched position is fixed by the interaction of the spring 6 and the
shoulders 13 with the housing 2.
If the actuator 4 is moved by pressure in the direction of the arrow 46
(compare FIG. 1), the pin 19 comes to bear against the guide curve 14
which is formed by the outer contour of the raised surface 16, and is
deflected in the direction of the arrow 23 in accordance with the outer
contour, which extends obliquely upwards. Because of the connecting
element 21, the pin 20 is likewise deflected and, as is to be seen in FIG.
8, finally touches the inner contour of the guide curve 15. Approximately
in this position of the pins 19, 20, the switching contacts 10 of the
contact bridges 8 come to bear against the break contact surfaces 11 of
the electrical terminals (compare also FIG. 2), as a result of which the
electrical connection is produced.
Given further movement by pressure on the actuator 4, the pin 20 is then
guided along the inner contour of the guide curve 15 essentially
vertically upwards in the direction of the arrow 24. At the same time, the
pin 19 is again deflected somewhat further in the oblique direction 23 and
finally guided likewise vertically upwards along the outer contour of the
guide curve 14 in accordance with the arrow 25. As may be seen with the
aid of the arrows 24 and 25, the two pins 19, 20 are differently deflected
because of the different shapes of the two guide curves 14, 15, so that
the connecting element 21 is elastically deformed in this movement
section. Due to this elastic deformation, the connecting element 21
constructed in the present exemplary embodiment as a U-shaped bracket is
subjected to torsional stress. During this movement, the springs 9 of the
contact bridges 8 (see FIG. 2) are simultaneously compressed, since the
switching contacts 10 already bear against the break contact surfaces 11.
The two pins 19, 20 finally reach the position shown in FIG. 9. While the
pin 20 moves there in the direction of the arrow 26 into the upper channel
34, because of the tension which is caused by the torsion of the U-shaped
bracket the pin 19 springs back in the direction of the arrow 27 as far as
the deflection corresponding to the pin 20, since the positive movement is
then terminated by the guide curve 14. The downward movement of the
actuator 4 is finally terminated by the stop of the lower surface 35 of
the actuator 4 at the base 5 (see also FIG. 5 in this connection).
In this position, there is now a weakening of the pressure on the actuator
4, so that because of the elastic force of the spring 6 said actuator is
again moved upwards against the arrow 46 in FIG. 1. In this case, however,
the compressed state of the springs 9 ensures that the switching contacts
10 bear against the break contact surfaces 11. During this upward movement
of the actuator 4, the pin 19 now comes to bear against the outer contour,
extending obliquely downwards, of the guide curve 14, and moves along the
latter in the direction of the arrow 28, as is to be seen in FIG. 10,
until the upper depression 36 in the guide curve 14 is reached. The pin 20
is guided along by the connecting element 21 in a corresponding deflection
to the pin 19, and upon reaching the depression 36 likewise comes to bear
against the triangular surface 18 due to the pin 19. Upon reaching the
upper depression 36 due to the pin 19, the electrical switch 1 is located
in the second latched position, which is shown in more detail in FIG. 11
and corresponds to the on position.
If the electrical switch 1 located in the on position is to be switched
off, the actuator 4 is once again pressed in the direction of the arrow 46
according to FIG. 1, as a result of which the pin 19 is guided along the
outer contour, extending vertically upwards, of the guide curve 14 in the
direction of the arrow 29, as is to be seen in FIG. 11. At the same time,
the pin 20 is guided vertically upwards until coming to bear against the
inner contour of the guide curve 15, and guided along there obliquely
upwards in the direction of the arrow 30. In this case, the connecting
element 21 is, in turn, elastically deformed. In the present exemplary
embodiment, the U-shaped bracket is subjected to torsional stress, since
by contrast with the pin 19, which is guided in the vertical direction 29,
the pin 20 is deflected further in the direction of the arrow 30, as is
shown in FIG. 12. If the upper point 37 of the guide curve 14 has been
reached by the pin 19, the latter snaps into the same position as the pin
20 because of the torsional tension. The electrical connection still
exists in this position, that is to say the switching contacts 10 continue
to bear against the break contact surfaces 11. At the same time, the
movement of the actuator 4 in the direction of the arrow 46 is, in turn,
terminated in this position by the lower surface 35 bearing against the
base 5.
Upon release of the actuator 4 or weakening of the pressure on the actuator
4, the latter moves upwards because of the force of the spring 6 and
opposite to the direction of the arrow 46 according to FIG. 1. The pin 19
is in this case moved along the outer contour of the guide curve 14 in the
direction of the arrow 31 and subsequently perpendicularly downwards. At
the same time, the switching contacts 10 are raised by the break contact
surfaces 11 (see FIG. 2), the electrical connection being broken again.
The pin 20 is guided along in the same position during this movement,
until it finally comes to bear against the inner contour of the guide
curve 15 and is moved there obliquely downwards in the direction of the
arrow 33 in accordance with FIG. 13. Since, now, the pins 19 and 20 are
moved anew along the different guide curves 14 and 15, the U-shaped
bracket is once again subjected to torsional stress in this movement
section, so that upon reaching the lower point 38 of the guide curve 14
the pin 19 snaps along the direction of the arrow 32 into the first
latched position corresponding to the off position of the electrical
switch 1.
In some cases, a pressure point which is clearly detectable during
switching on is desired in such a switch. This point can be realized by
constructing the distance between the inner contour of the guide curve 15
and the outer contour of the triangular surface 18 such that at the
constriction 39 located in the switching-on path, which is traversed by
the pin 20 from the latched position corresponding to the off position
into the latched position corresponding to the on position, and is to be
seen in more detail in FIG. 6 said distance is equal to or slightly
smaller than the cross-sectional width or, in the case of a round cross
section, the diameter of the pin 20. If the pin 20 then reaches the
constriction 39, the latter must be brought through the constriction 39
onto the actuator 4 by means of increased pressure. After the pin 20 has
passed the constriction 39, a smaller pressure once again suffices for
further movement of the actuator 4, so that the typical pressure point
performance exists.
As is to be seen in more detail in FIGS. 4 to 6, the electrical terminals
12 are provided with a U-shaped part 40 which is widened as compared with
the terminal 12, the terminal 12 leaving a leg of the U in a cranked off
fashion. The break contact surfaces 11 are formed by the other leg of the
U. The U-shaped part 40 is plugged on a correspondingly shaped web 41 of
the base 5. It is thereby possible to plug on the U-shaped part 40 in such
a way that the terminals 12 project vertically downwards from the housing
2, in order to be connected to the terminal printed conductors on a
printed circuit board by means of plating through. The U-shaped part 40
can also be plugged onto the web 41 in the way to be seen in FIG. 14. The
terminals 12 then project sideways at the bottom on the housing 2, as a
result of which this switch is particularly suitable for surface mounting
on a printed circuit board. In this case, the break contact surfaces 11
are formed by the base of the U. It remains to be stressed that it is
possible to eliminate corresponding holes in the housing 2 for leading
through the terminals 12, since the latter project from the switch 1 at
the base 5, which shuts off the housing 2 below.
A further variant of the electrical terminals of the switch 1 is to be seen
in FIG. 15. In this case, the terminals are not cranked off. The terminal
42 consists of a direct extension of a leg of the U-shaped part 43, which
is plugged on the web 41. Terminals 42 constructed in such a fashion are
particularly easy to manufacture in terms of production engineering. As is
further to be seen in FIG. 16, the terminals 42 of this variant have
essentially the see width as the U-shaped part 43.
The invention is not restricted to the exemplary embodiment described.
This, instead of arranging the two guide curves on the actuator, it is
also within the scope of the invention to arrange them on the inner
surfaces of the housing and to arrange the connecting element for the pins
on the actuator. However, it is important in the exemplary embodiment that
the two guide curves have a different shape, as a result of which the
connecting element coupling the two pins is elastically deformed in
sections during the movement of the actuator. Due to this elastic
deformation, a force is exerted on the respective pin, as a result of
which, as described with the aid of FIGS. 7 to 13, the latter is moved in
the direction of the travel, so that maloperations are reliably excluded.
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