DE8908132U1 - Electrical switch for moving equipment or equipment parts - Google Patents

Description

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The invention relates to an electrical switch according to the preamble of claim 1.

Switches of the aforementioned type are used as so-called motion detectors or position detection switches/sensors in devices or parts of devices that can assume several positions, whereby the various positions (inclinations, movements) can trigger certain consequences (e.g. dangers).

This is primarily intended for use in irons and fan heaters. If, for example, an iron that is switched on remains stationary on its heating surface for a long time, there is a risk of fire, or at least a risk of damage to the support surface. In such a situation, the switch in question, which in this case remains open, should send a corresponding message to the electronics, which then switches off the heating of the iron after approx. 15 to 30 seconds. If, on the other hand, the iron is moved back and forth, the switch opens and closes constantly, thereby informing the electronics that the device is in use and the heating must remain ready for use. If the iron is placed on its back, the switch falls into a permanently closed position. This means that the electronics are informed that the device is in a safe position, so that the heating should or can remain ready for use or - to save energy - should or can be switched off after around 10 minutes.

The situation is similar with a fan heater: if it falls over, there is a risk of fire. The switch in question, which closes automatically in this case, must therefore ensure that the heating coil is switched off quickly by sending appropriate information to the electronics.

Safety switches of the type in question are known as so-called mercury switches. As the name suggests, their peculiarity is that the movable

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Mercury is used as the contact body. Since this metal assumes a liquid state at the temperatures normally prevailing on earth, the switch housing that houses the contact body must be hermetically sealed. It is obvious that the switch will no longer function if the mercury or a portion of it escapes from the switch housing. The requirement for absolute housing sealing is also necessary because mercury is a highly toxic substance. This results in a comparatively large manufacturing effort, combined with correspondingly high costs. Nevertheless, the possibility of mercury escaping from the switch housing can never be completely ruled out. Environmental damage cannot be ruled out even if the mercury switch remains intact throughout the entire service life of the device in question. One day, when it has served its purpose, the device will end up in the rubbish dump and may be stored there for years. Then it will almost inevitably happen that the toxic mercury will leak out of the switch housing at some point.

The object of the invention is to create a switch of the type described at the beginning, which operates reliably over the long term and does not pose a danger to the environment.

According to the invention, the object is achieved in that the movable contact body is designed as a spherical metallic solid body and the fat contacts are arranged parallel or essentially parallel to metallic contact pins and that two contact pins can be actuated by the spherical solid body which, in the closed position, bridges the distance between the contact pins and simultaneously touches the two contact pins.

The invention avoids the risk of the contact body escaping from the housing by designing it as a spherical solid body. At the same time, this ensures a high

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Functional reliability and a long service life of the switch are guaranteed. Since the use of toxic mercury is avoided, environmental damage is excluded. In addition, the switch according to the invention is comparatively simple and cost-effective to manufacture because no special requirements need to be placed on the tightness of the housing.

Further embodiments and advantages of the invention can be found in claims 2 - 17.

To illustrate and explain the invention in more detail, the following embodiments are shown in the drawing and described in detail below. It shows (Fig. 1 - 8 and 15, 16, each greatly enlarged compared to the natural size):

Fig. 1 in vertical section (section I-I in Fig. 2) a basic design of a switch according to the invention, with two contact pins and a spherical solid body,

Fig. 2 the object of Fig. 1 in plan view (housing cover omitted),

Fig. 3 a graphical representation of the force relationships when contacting the contact pins through the spherical solid body, in plan view corresponding to Fig. 2,

Fig. 4 shows another embodiment of the switch according to the invention, based on four contact pins and two spherical solid bodies arranged one above the other, viewed from above (housing cover omitted),

Fig. 5 is a section along the line V-V in Fig. 4,

Fig. 6 shows a further embodiment of the switch according to the invention, with five contact pins and two spherical solid bodies arranged next to each other, in plan view corresponding to Fig. 4*

Fig. 7 is a section along the line VII-VII in Fig. 6,

Fig. 8 a section along the line VIII-VIII in

Fig.7,
Fig. 9 the switch according to Fig. 6 - 8 in (opposite Fig. 6-8

reduced) perspective view, Fig. 10 a circuit diagram for the switch according to Fig. 6-9, Fig. 11 an installation example of an inventive

switch (schematic),
Fig. 12 an application example of a switch according to the invention in an electric iron,

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Fig. 14 - based on an electrical circuit - another example of application of a switch according to the invention, e.g. suitable for an electric fan heater ,

Fig. 15 the contact conditions between spherical.

Solid body and an uncoated contact pin, in side view, and

Fig. 16 the contact conditions between a spherical solid body and a contact pin coated with electrically conductive paint, in a representation corresponding to Fig. 15.

The structure and mode of operation of the ball switch according to the invention can be seen particularly well in Fig. 1 - 3 - because of the simplified representation of the basic principle.

10 denotes a switch housing made of a suitable material.

electrically insulating material, in particular a heat (

resistant plastic, whereby polyarylsulfone or \

Polyethersulfone has proven to be very suitable in practice. -4

The cube-shaped housing 10, which is open at the top, is separated by a |

Lid 11, which is preferably made of the same material as the &igr;

Housing 10 is firmly closed. There are various 3

different fastening methods, e.g. welding of cover 11 I

and housing 10, conceivable. |

A spherical contact body 12 is arranged within the switch housing 10 and can move freely. The spherical contact body 12 consists of a solid metal, e.g. steel, and is therefore designed as a solid body. It can - for finishing purposes

its surface or to increase its electrical contact capability - be coated with one or more thin layers of one or more suitable contact materials. Possible contact materials include: nickel/gold, silver, platinum/rhodium and others. In practice, a coating with nickel (layer thickness approx. 10/1) and a gold layer of approx. 0.1 μm on top has proven to be very effective.

The spherical solid body 12 cooperates with two metallic contact pins 13, 14, which are arranged parallel to one another at a distance that is smaller than the diameter of the spherical solid body and pass through almost the entire interior of the housing in the vertical direction (see Fig. 1). The contact pins 13, 14 are held in the base 15 of the housing 10, whereby they can be pressed into corresponding holes 16 or can be molded or cast around by the material of the housing 10 during its manufacture. At their ends protruding from the bottom of the housing 10, the contacts 13, 14 are connected (in the usual and therefore not shown manner) to an electrical circuit in such a way that bridging the contact pins 13, 14 by the spherical solid body 12 causes the relevant circuit to be closed.

As can also be seen from Fig. 1, the interior of the switch housing 10 is designed to be axially symmetrical. For this purpose, the support surface for the spherical solid body on the housing base 15" consists of a horizontal partial surface 17 and an adjoining partial surface 18 which slopes upwards in the direction of the contact pins 13, 14. Likewise, the housing cover 11 also has a horizontal partial surface and an inclined partial surface 20. The angles of inclination of the partial surfaces 18, 20 are opposite to one another, but equal in magnitude and are therefore each designated with oC in Fig. 1. Due to the symmetrical design and arrangement of the support surfaces 17-20, an identical function of the switch is guaranteed when it is installed upright and hanging (see Fig. 11).

If the device in which the switch described is installed is tilted and/or moved (accelerated) in the corresponding direction, the spherical solid body moves in the direction of the contact pins 13/14, overcoming the slope of the inclined support surface 18 (or 20). Finally, the spherical solid body 12 comes into contact with the contact pins 13, 14. This closed position of the switch is indicated in Fig. 1 and 2 by a dashed line 12'. Fig. 3 makes it clear that the distance between the contact pins 13, 14 and the ball diameter of the solid body 12 are coordinated in such a way that the contact pins 13, 14 exert a wedge effect on the spherical solid body 12 in the closed position 12', without self-locking occurring. The angle marked /3 in Fig. 3 is decisive for this, the size of which depends on the cooperating materials of the spherical solid body 12 on the one hand and the contact pins 13, 14 on the other. The force relationships that arise here can be seen particularly clearly from the force triangle shown in Fig. 3. Here, the arrow P indicates the contact pressure exerted by the spherical solid body 12 on the respective contact pin 13 or 14, and the arrow marked 1/2G means half the weight of the spherical solid body 12. It can be seen that the contact pressure P of the spherical solid body 12 on the respective contact pin 13 or 14 is considerably greater than half the weight of the solid body. This high contact pressure P ensures a correspondingly high switching reliability.

The switching reliability when the spherical solid body 12 comes into contact with the contact pins 13, 14 can, however, be further improved, as Fig. 15 and 16 clearly show, by coating the contact pins 13, 14 in the area of the contact point 21 (see Fig. 15) and its surroundings with an electrically conductive lacquer. The lacquer layer in question is shown in Fig. 16 (in a much higher thickness than the natural thickness) and is marked with

Due to the relative softness of the lacquer coating 12, it gives way accordingly when the spherical solid body 12 comes into contact with the contact pin 13 or 14, whereby a surface-like contact area F with numerous contact points (e.g. 23 - 26) is created. Silver conductive lacquer or carbon conductive lacquer has proven to be suitable materials for the coating 22 of the contact pins 13, 14.

Fig. 4 and 5 show a special embodiment of a switch according to the invention, which is characterized by the special feature that two spherical solid bodies 12a and 12b are arranged one above the other in two planes (see Fig. 5). This measure also serves to increase the switching reliability of the switch in question. A further special feature is that a total of four contact pins 28, 29, 30, 31 - forming the corner points of a square - are arranged in the housing 27, which has a square cross-section. The contact pins 28 - 31 penetrate the entire housing 27 in its vertical extension and engage with their upper ends in corresponding recesses 32, 33 of the housing cover, numbered 34 here (see Fig. 5). Another important feature of the embodiment according to Fig. 4 and 5 is that the support surfaces for the spherical solid bodies 12a and 12b in the switch housing 27 are obtuse-angled/conical. These are therefore rotationally symmetrical support surfaces. The support surface for the lower spherical solid body 12a is incorporated in the base 35 of the housing 27 and is designated 36. The (lower) support surface for the second spherical solid body 12b is formed by an "intermediate ceiling" 37 inserted into the switch housing 27 - approximately halfway up the same - and is numbered 38. On the underside of the false ceiling 37, a further obtuse-angled/conical recess 39 is provided, with which the spherical solid body 12a cooperates when the switch is in a hanging installation position (i.e. in a position rotated by 180° compared to the drawing representation!

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is installed in the device in question. A similar function for the second spherical solid body 12b is provided by a similar obtuse-angled/conical depression, which is worked into the underside of the housing cover 34 and is designated by 40. The rotationally symmetrical inclined surfaces of all depressions 36, 39, 38 and 40 have the same angle of inclination _, which are each marked with o in Fig. 5.

Due to the circumstances described above, contact between two of the contact pins 28 - 3 \ | by the spherical solid bodies 12a and 12b always occurs when the switch is inclined (relative to its two main vertical planes) by an angle oC ¹ (see Fig. 5).? whereby this angle oC must be greater than the angle of inclination CC of the obtuse-angled/conical contact surfaces 36, 39, 38 and 40. As can be seen from Fig. 4, a total of four different switch positions are possible, which are indicated by dashed lines and marked with 12', 12 ¹¹ , 12'" and 12' ¹ '. In switch position 12', the contact pins 28, 29 are contacted by the solid bodies 12a and 12b, in switch position 12" the contact pins 28 and 31, in switch position 12 · *· the contact pins 31 and 30 and finally in contact position 12 ¹¹¹ ' the contact pins 29 and 30. The switch can therefore provide a total of five different pieces of information depending on the angle of inclination or direction of movement of the device in question (the one shown in Fig. 4 and 5 (the solid central zero position of the spherical solid bodies 12a, 12b is shown). Due to the design conditions (see above), rotationally symmetrical position detection is possible, so that the switch is suitable for installation in an electric fan heater (as a so-called "dead man's switch"), for example. >i

To illustrate the above application example %

of a switch according to Fig. 4 and 5 is shown in Fig. 14 (schematic) Pj

a fan heater in the form of a block diagram. Here, |

41 draws the heating of the fan heater, which for example is a §

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Output of 2000 watts. The heater 41 is operated by a bimetal switch numbered 42, which has switching contacts 43, 44 and a heating coil 45. The heating coil 45 of the bimetal switch 42 is connected in such a way that it can be operated by the spherical solid body 12a (or - in a double ball arrangement according to Fig. 4 and 5 - by the solid bodies 12a and 12b). The spherical solid body 12a is shown in Fig. 14 in the central rest position. It therefore does not touch the contact pin points 28, 29 or 30, 31. The heating winding 45 is therefore switched off and the bimetallic switch 42 remains closed, whereby the heater 41 is supplied with electrical energy. If the device is now rotated by an angle α , the solid body 12a contacts the contact pin pair 28, 29 or 30, 31; the circuit of the heating winding 45 closes, the bimetallic switch 42 opens at 43, 44, and the heater 41 of the fan heater is thus switched off. The embodiment shown in Fig. 6-10 is also a switch in which several contact pin pairs can be operated by a spherical solid body. In this respect there is a certain similarity with the embodiment described above according to Fig. 4 and 5. The variant according to Fig. 6-10 has the special feature that although two spherical solid bodies - numbered 12a and 12b - are provided, these do not lie one above the other but next to each other in a plane. Furthermore - as can be seen in particular from Fig. 6 and 9 - not four contact pins but rather five contact pins are provided, which are designated 46 - 50 and are arranged in the cuboid-shaped housing 51 - forming the contours of a trapezoid. The three contact pins 47, 48 and 49 form a first row, opposite which is a second row consisting of the contact pins 46 and 50. The contact pins 47 - 49 form two contact pin pairs, namely 47 and 48 and 48 and 49. Two further contact pin pairs are formed by the corner contact pins 47 and 46 and 49 and 50.

The switch according to Fig. 6-10 represents a multi-ball system, in such a way that two spherical solid bodies 12a and 12b are provided for actuating one or more of the aforementioned contact pin pairs. As with the other embodiments, the housing 51 is also closed by a cover, which is numbered 52.

As can be seen in particular from Fig. 7 and 8, this switch is also symmetrical in its interior, ie the support surfaces for the spherical solid bodies 12a and 12b on the housing base 53 on the one hand and on the cover 52 on the other hand correspond to one another. These support surfaces are designed in such a way that on the one hand there are inclined surfaces 54, 55 which rise in the direction of the contact pins 47, 48 and 49. In addition, however, inclined surfaces 56, 57 and 58, 59 are provided which are inclined in the direction of the contact pin pairs 49, 50 and 46, 47 respectively. The angle of inclination of the inclined surfaces 54, 55 is designated oO, while the angle of inclination of the other inclined surfaces 56-59 is designated β . Due to these design conditions, the contact pins 46 - 50 are contacted differently by the solid bodies 12a and 12b at different angles of the switch in question. If the switch is in the horizontal position, as shown in Fig. 6-8, the spherical solid bodies 12a and 12b are in their solid middle positions. The contact pins do not touch - all contacts are open. If the switch is only tilted in the direction of Ä' (see Fig. 8), the contact pin pairs 47, 48 and 48, 49 are contacted by the spherical solid bodies 12a and 12b. 12b is closed, provided that the angle of inclination OC ¹ is greater than the angle of the inclined surface (X-. Corresponding contact conditions also arise when the switch is accelerated in the X direction (see Fig. 6). The relevant contact positions of the spherical solid bodies 12a and 12b are indicated by dashed lines in Figs. &euro; and 8 and are designated 12a ¹ and 12b', respectively.

If the switch is used, for example, in an iron (see Fig. 12 and 13) - as a tilt and movement switch, the position of the switch inclined in the direction oC' (Fig. 8) corresponds to the back position of the iron shown in Fig. 13.

If, however, the switch is tilted to its side - the respective tilt directions are marked with β ' in Fig. 7 - contact is made either of the contact

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or the contact pin pair 49, 50 by the spherical solid body 12b. The latter contact position is illustrated in Fig. 6. The two spherical solid bodies 12a and 12b each assume the positions 12a ¹ ' and 12b ¹¹ indicated in dashed lines. Here too, however, the prerequisite must be met that the angle of inclination yd' - whether in the direction C or in the direction B (cf. Fig. 9) - is greater than the angle β of the respective inclined surfaces 56, 57 or 58, 59 that come into effect.

A special feature is that the housing 51 is so thin that when the switch ^is in the ^{upright position} (inclination in direction C or B, Fig. 9), the contact pin 48 cannot be touched by either of the two spherical solid bodies 12a ^or 12b.

In Fig. 10, the previously described operation of the switch according to Fig. 6-8 is illustrated again using a block diagram. From this it is clear that the contact pin 48 on the one hand and the contact pins 46, 50 - the latter together - on the other hand are each connected to the positive pole of an electrical circuit. In contrast, the two remaining contact pins 47, 49 are connected to earth. Two outputs of the circuit are provided, which are numbered 60 and 61 in Fig. 10. Due to this connection of the contact pins 46 - 50, the following levels of the outputs 60 and 61 result for the various possible positions (A-D, see Fig. 9) of the switch in question.

If the switch is in neutral horizontal position
(Position A) then none of the contact pins 46 - 50 of
the spherical solid bodies 12a and 12b (see
see Fig. 6-8 and above); both outputs 60
and 61 therefore have the level "HIGH". If the switch is in
If the contact pins 46/47 are inclined in the direction B, the spherical solid body 12a is contacted (see
Fig. 6 - 8); in this case, the output 60 is again
the IP level designation "HIGH", while output 61 assumes the level position "LOW". The identical level position of the

&igr; Outputs 60, 61 result when the switch is tilted in ) direction C, where the contact pin pair 49, 50 is contacted by the | solid body 12b (see also Fig. 6-8 *! and the above explanations). &idigr;

If, however, the switch is tilted in direction D (tilt \

angle OC ¹ in Fig. 8) the contact surface is touched |

pin pair 47, 48 through the solid body 12a and a loading |

contact of the contact pin pair 48, 49 through the solid body 1

12b. In this case, the output 60 is controlled by the level "LOW" |

while the other output 61 indicates the level &iacgr;

position "HIGH". i

As has already been mentioned several times, all the switches shown in the drawing and described above are designed, due to their symmetrical design, in such a way that they can be installed in the relevant device, e.g. in a fan heater (see Fig. 14) or in an iron (see Fig. 12 J and I3), in either an upright or hanging ^position . Fig. 11 illustrates these two installation options in a schematic representation. 62 here designates a circuit board on which the relevant switch housing - 10 or 27 or 51 - can be installed in an upright position (left side) or in a hanging position (right side).
side). The fastening is done
by soldering the contact pins to the circuit board
62. In the case of the standing variant I shown on the left in Fig. 11, the soldering point is at the bottom and is numbered 63. In contrast, in the case of the variant I shown on the right in Fig. 11, the soldering point is at the bottom and is numbered 63.

In the hanging version, the soldering point is on the top of the circuit board 62. It is marked 64.

In the application example of a switch according to the invention according to Fig. 12 and 13, as Fig. 12 shows, a standing position of the switch in question on the circuit board 62 is selected.

Claims (17)

I · hifi p'fA-'f N.©'e I^ j E«VR,.: DR. £h'E t R! '&U ^: SC HE Ft* LER PATENT ATTORNEY EUROPEAN PATENT ATTORNEY D-7000 STUTTGART? He 2 Dr. S/from 16.06.1989 Applicant: Ing. Karl Hellmuth jun., Seestraße 28, 7311 Bissingen an der Teck Electrical fire extinguisher for any equipment or equipment parts Expectations 1. Electrical switch for movable devices or device parts, in particular fan heaters, irons and the like, which switches automatically depending on the respective position and/or movement of the device or device part, with a housing made of insulating material in which outwardly projecting electrical contacts are fixedly arranged, and with a contact body made of electrically conductive material arranged freely movable within the housing, which cooperates with the fixed contact - the contact body being open or closing, characterized in that the movable contact body is designed as a spherical metallic solid body (12, 12a, 12b) and the fixed contacts are metallic contact pins (13, 14, 28 - 31, 46 - 50) arranged parallel or essentially parallel and that two contact pins can be actuated by the spherical solid body which, in the closed position, bridges the distance between the contact pins and simultaneously touches the two contact pins. 2. Electrical switch according to claim 1, d-rflurch characterized in that the spherical solid body (12, 12a, 12b) in the housing (10, 27, 51) on a support surface (17 - 20 or 36, 38 - 40 or 54 - 59) which rises in the direction of the contact pins (13, 14 or 28 - 31 or 46 - 50). 3. Electrical switch according to claim 1 or 2, characterized in that the interior of the housing (10, 27, 51) is designed symmetrically, such that a running surface (19, 20 or 39, 40 or 54, 56, 58) with a slope is provided on the upper side of the housing, which is mirror-symmetrical to the lower running surface (17, 18 or 36, 38 or 55, 57, 59) of the spherical solid body (12, 12a, 12b), and that the contact pins (13, 14, 28 - 31, 46 - 50) pass through the entire or almost the entire interior of the housing (10, 27, 51). 4. Electrical switch according to claim "., 2 or 3, characterized in that the distance between the contact pins (13, 14 or 28 or 46 - 50) forming contact pin pairs and the ball diameter of the solid body (12, 12a, 12b) are coordinated with one another in such a way that the contact pins exert a wedge effect on the movable solid body when it is in the closed position, but without self-locking occurring, the contact pressure (P) being greater than half the weight of the solid body (1/2 G) (Fig. 3). 5. Electrical switch according to one or more of the preceding claims , characterized in that the housing (10, 27, 51) consists of a heat-resistant plastic, preferably polyarylsulfone or polyethersulfone, and the contact pins (13, 14, 28-31, 46 - 50) are pressed into bores (16) of the housing (10, 27, 51). 6. Electrical switch according to one or more of the preceding claims, characterized in that the housing (10, 27, 51) is cube-shaped or cuboid-shaped. 7. Electrical switch according to claim 5 or 6, characterized in that the housing is designed in two parts, such that it consists of a housing body (10, 27, 51) which receives the contact pins (13, 14, 28 - 31, 46 - 50) and is open at the top, which is closed by a cover (.11* 34 ₃ 52) made of the same material as the housing body. 8« Electrical switch according to one or more of the preceding claims, characterized in that the metallic spherical solid body (12, 12a, 12b) is coated with one or more surface-finishing contact materials, e.g. Sri, Au, Ag, Pt or Rh. 9. Electrical switch according to claim 8, characterized in that the spherical solid body (12, 12a, 12b) consists of steel and has a first (inner) coating of nickel of 10 μm thickness, on which a second (outer) coating of gold of 0.1 μm thickness is applied. 10. Electrical switch according to one or more of the preceding claims, characterized in that the contact pins (13, 14, 28 - 31, 46 - 50) have a coating (22) of electrically conductive lacquer in the region (F) of their contact point (21 or 23 - 26) with the spherical solid body (12, 12a, 12b) (Fig. 16). 11. Electrical switch according to claim 10, characterized in that the coating (22) of the contact pins (13, 14, 28 - 31, 46 - 50) consists of a silver conductive varnish. 12. Electrical switch according to claim 10, characterized in that for coating (22) the Carbon conductive paint is used. 13. Electrical switch according to one or more of the preceding claims, characterized in that several pairs of contact pins (28, 29; 29, 30; 30, 31; 28, 31 or 47, 48; 48, 49; 46, 47; 49, 50) can be actuated by a spherical solid body (12a or 12b) {Fig. 4 ■» 10). 14. Electrical switch according to claim 13, characterized in that four contact pins (28 - 31) are arranged in a housing {27} with a square cross-section, forming the corners of a square, and that the housing surfaces (bottom 15, intermediate cover 37 and cover 34) located within the four corners have obtuse-angled/conical recesses ( 36, 39, 38, 40) for receiving the spherical solid body or bodies (12a or 12b) (Fig. 4 and J/. 15. Electrical switch according to one or more of the preceding claims, characterized in that it is designed as a multi-ball system, such that several spherical solid bodies (12a, 12b) are provided for actuating one or more contact pin pairs (28, 29; 29, 30; 30, 31; 28, 31 or 47, 48; 48, 49; 46, 47; 49, 50) (Fig. 4-10) 16. Electrical switch according to claim 14 and 15, characterized in that the housing (27) has two superimposed "floors" (levels 35, 37) f. and that a spherical solid body (12a or 12b) is arranged on each level for actuating the four continuous contact pins (28 - 31) (Fig. 4 and 5). 17. Electrical switch according to claim 13 and 15, characterized in that a total of five contact pins (46 - 50) are arranged approximately trapezoidally in a housing (51), which interact with two spherical solid bodies (12a, 12b), whereby three in a first nS-"'S !.xS^ciluc nOntoktötlLto (47, 48, 49) two .".3'H Contact pin pairs (47, 48; 48, 49) and two further contact pins (46, 50) arranged in an opposite (second) row each together with the associated corner contact (47 or 49) of the first row form two further contact pin pairs (46, 47 or 49, 50) (Fig. 6 - 10).