EP2837989B1 - Rotary switch for electrical appliances using improved latching means - Google Patents

Description

Field of the invention

The invention relates to a rotary switch with latching device as a control element for electrical appliances, wherein the rotary switch comprises a rotary knob, a shaft and a latching device. The invention also relates to a locking device for rotary switches with two voltage applied to a latching contour locking lugs under spring force.

Background of the invention

Rotary switch with locking device are often used as controls for electrical appliances to select, for example, different programs in a washing machine. For this purpose, the rotary switches are usually arranged on a front page for the user easily accessible and connected inside the device with an electrical circuit, for example via a rotating field sensor or a sliding contact.

For example, from the German patent application DE 102 34 925 A1 a rotary selector known as an operating device of electrical appliances, which has a spring-loaded ball catch. The provided with a single or Doppelkugelrastung rotary selector is used in a shaped as a hollow cylinder guide member with internal locking contour. The holder of the rotary selector in the guide part via hook-shaped retaining pin.

Further, the German Offenlegungsschrift discloses DE 103 23 544 A1 a locking device for a rotary switch or a rotary resistance. Two rounded ends of a leaf spring which are shaped to latching noses lie diametrically on a locking disk, which connected via a rotary axis with a knob. The locking disk is arranged here between a rotary knob and a bearing.

DE 10 2005 001 560 A1 discloses a rotary switch with locking device, wherein a rotatable adjusting ring is rotatably supported via a ball bearing on fixed housing parts of the rotary switch, and wherein two under the spring force of a compression spring latching pins rest on a arranged on the inside of the rotatable adjusting ring locking contour. US 2009/0095614 A1 discloses a rotary switch with locking device, according to the preamble of claim 1, wherein the rotary switch is mounted neutral by force of leaf springs. For this purpose, the rotary switch in each case two in the direction of the axis of rotation above or below a radially extending from the axis of rotation outwardly extending portion of the rotary switch vertical locking lugs, which rest under spring force of a leaf spring on a formed on this section as a concentric ring, vertical locking contour. DE 10 2007 038 547 A1 . DE 3834 390 C1 . DE 10 2008 045 232 A1 and DE 202 19 655 U1 each disclose a rotary switch with locking device, wherein the rotary switch is rotatably supported about a bearing via a bearing and the latching device comprises two detents which rest under spring force of one or more coil springs on a latching contour, wherein the latching lugs are each guided perpendicular to the axis of rotation in a plane and the locking contour is also arranged in this plane.

The problem underlying the invention

The invention has for its object to provide a comparison with the prior art improved rotary switch with locking device as a control for electrical appliances. In particular, an improved rotary switch with latching device is to be provided, which can be operated more reliably and without tilting of the latching device.

Inventive solution

The solution of the problem is achieved by a rotary switch with locking device as a control for electrical appliances according to claim 1. The rotary switch comprises a Rotary knob, a shaft, a bearing and said locking device. The latching device comprises two latching lugs which rest on a latching contour under spring force. The bearing of the shaft is disposed between the knob and the latching device.

Electrical appliances are, for example, household appliances such as washing machines, dishwashers or dryers. But it can also be small electrical appliances such as coffee machines or coffee grinders. It can also be power tools. The electrical appliances are powered by electrical energy. The electrical supply is done either by a mains connection or by batteries or rechargeable batteries. The rotary switch can be used in such electrical appliances for selecting various programs and / or for switching on and off. For this purpose, such rotary switches are usually connected either free of contact via a rotary field sensor or by a sliding contact with corresponding contacts on an electrical circuit.

The rotary switch according to the invention comprises a rotary knob which is non-rotatably connected via a shaft with a part of the latching device. Rotationally connected means that Rotary knob, shaft and a part of the latching device are rotatable together, and that a rotation of the rotary knob leads by an angle to a rotation of the shaft and a part of the latching device by the same angle. The rotation takes place about a common axis of rotation. The co-rotated part of the locking device is either the locking contour or the unit of the two locking lugs.

According to the invention are two locking lugs under spring force to a locking contour. On the locking contour a plurality of locking positions is arranged, which are formed as latching depressions, in which engage the latching noses under the action of the spring force. Furthermore, the latching contour may have elevations. The latching contour may be in the form of a disk or cylinder, with the latching depressions and elevations along the circumference being provided on the inside or the outside. In the case of a substantially circular disk or a cylinder with a substantially circular cross-section, the detent recesses and elevations are formed as deviations from a central position. The latching noses can abut, for example, on opposite sides in the opposite direction to the latching contour. In detent position, the detents are in a detent recess. When turning the knob, the locking lugs are first deflected by the latching contour against the spring force against the central position before they engage the next latching recess again. The force is calculated as the product of the sum of the deflections of the two locking lugs with the spring constant of the spring used. In comparison, a single locking lug would have to experience the entire deflection alone with the same spring constant in order to produce the same force. For this purpose, the locking recesses would have to have a greater deviation from the central position, whereby a larger locking contour would be necessary for the same number of locking positions. The use of two locking lugs thus allows a per detent lesser deflection, whereby smaller detent recesses can be arranged on the locking contour, which allows a higher number of detent positions or with a constant number of detent positions a smaller size of the detent contour. A second oppositely arranged locking lug also makes it possible to compensate for the force of the first latching lug on the shaft. In this way we counteracted tilting of the rotary switch, whereby the operation of the rotary switch is reliable.

An inventive rotary switch with locking device allows the user to set a variety of locking positions safely and reproducibly. The interaction of locking lugs with locking contour also gives the user an acoustic and tactile feedback.

The bearing of the shaft is arranged according to the invention between the knob and the latching device. This position of the bearing allows the knob to be positioned very close to the bearing, resulting in a particularly short lever arm. As a result, a force exerted by the knob on the shaft, acting perpendicular to the direction of rotation torque is minimized. The rotary switch is therefore much more reliable to use than would be the case with a differently placed bearing. A tilting or clamping of the rotary switch is thereby counteracted particularly successfully.

Due to the rounding of the requirements of the locking lugs, an increased number of locking positions can be realized because the tips of the locking lugs can be made narrower. In addition, a safer locking in the locking positions can be achieved because the locking lugs can engage more deeply in the locking recesses.

Preferred embodiments of the invention

Advantageous embodiments and developments, which can be used individually or in combination with each other, are the subject of the dependent claims.

In a preferred embodiment of the invention, the requirements of the locking lugs are rounded, wherein the radius of the rounding is less than two-fifths of the maximum width the locking lugs is. A support may in this case be a contact point, a contact line or a contact surface between a latching lug and the latching contour. By reduced compared to a ball detent radius of rounding an increased number of locking positions can be realized because the tips of the locking lugs can be made narrower. In addition, a safer locking in the locking positions can be achieved because the locking lugs can engage more deeply in the locking recesses. The rounded support also reduces the friction between the latching lugs and the latching contour, which also reduces the wear on both components. Preferably, the cross section of the latching lugs lying parallel to the plane of rotation has substantially the shape of a triangle, particularly preferably an isosceles triangle. The radius of the rounding of the support is preferably smaller than half the width of the detent recesses, particularly preferably smaller than two-fifths of the width of the detent recesses, so that the supports of the detents can engage particularly easily in the detent recesses. This also allows a particularly high number of locking positions. In a further preferred embodiment, the support of the locking lug is flattened, resulting in a trapezoidal cross-sectional area.

Preferably, the spring force with which the latching lugs rest on the latching contour, generated by a coil spring. Coil springs are inexpensive and available in almost any size and thickness. This saves costs in the manufacture and maintenance of the rotary switch. Furthermore, it is possible to set a spring force which is specifically adapted to the respective application or the respective user. Particularly preferably, the coil spring is a metal spring. Furthermore, it is also known to use leaf springs in locking devices. Preferably, the spring force is generated by a single coil spring. In a particularly preferred manner, however, more than one spring can also generate the spring force. For example, the latching lugs can rest on the latching contour from opposite sides, guided radially inwards relative to the axis of rotation. Then the locking lugs are preferably stored separately on each spring. The springs are preferably arranged so that the spring forces compensate each other.

In a preferred embodiment of the invention, the detents in detent position exert no force on the shaft. Preferably, this is achieved by supporting the two latching lugs on opposite ends of a common spring. Preferably, the spring is guided freely movable in the direction of force relative to the shaft. Preferably, the Spring guided in a hollow cylinder. As a result, a displacement perpendicular to the direction of force is prevented. The movement or deflection of the spring is limited in the direction of force only by the latching noses, which bear against the latching contour. A respectively different large deflection of the two locking lugs causes only a translation of the center of gravity of the spring in their leadership. The forces with which the two locking lugs abut the locking contour, always have the same amount due to the use of a common spring. There is a constant balance of power without a force acting on the shaft. The advantage of this arrangement is that the detents do not affect the position of the shaft. This counteracts tilting of the rotary switch. In addition, the bearing of the shaft is less stressed and therefore can be made less robust and cost-saving. When turning the knob but occur forces that also act on the shaft.

In a preferred embodiment, the locking lugs are guided radially outward with respect to the axis of rotation. Radially guided means radially starting from the axis of rotation or aiming at the axis of rotation. The guide preferably limits the degree of freedom of the movement of the latching noses in one direction. Particularly preferably, the latching lugs are guided perpendicular to the axis of rotation in a plane. However, arrangements are also possible in which the detents do not lie in one plane or in which they are not arranged perpendicular to the axis of rotation. The latching lugs can also be arranged parallel to the axis of rotation on radially opposite sides of the axis of rotation and abut against a latching contour which is preferably designed as a latching disc. This results in a resulting force parallel to the axis of rotation, which also acts on the shaft. Preferably, the forces are equalized, so that no torque is applied perpendicular to the axis of rotation on the shaft.

Preferably, the locking lugs are rotatably connected to the knob. Particularly preferably, the locking lugs on the shaft rotatably connected to the knob. The locking lugs are therefore rotated by rotation of the knob relative to the locking contour. The latching contour is preferably connected in a rotationally fixed manner to the electrical appliance, which means that the latching contour does not rotate relative to the electrical appliance. Conversely, the locking contour can be connected in a rotationally fixed manner to the rotary knob and the latching lugs can be connected in a rotationally fixed manner to the electrical appliance. In this case, the latching lugs are preferably arranged radially inwardly toward the axis of rotation, wherein the latching lugs thereby are preferably arranged perpendicular to the axis of rotation on opposite sides of the axis of rotation. Here, the locking lugs are preferably mounted on separate springs. Preferably, both springs have the same hardness, so that rest at the same deflection, the locking lugs with a force equal amount to the locking contour. These forces aimed at the axis of rotation stabilize and center the shaft and thus function like a second bearing, which counteracts a tilting of the rotary switch.

In a preferred embodiment, the entire circumference of the shaft is enclosed by a bearing. Particularly preferably, in the axial direction, a predominant part of the section of the shaft, which lies between locking device and rotary knob, is enclosed by the bearing. As a result, the shaft is guided very precisely and limited to only one rotational degree of freedom about the axis of rotation. This again improves the reliability of the rotary switch. In a particularly preferred embodiment, the rotary knob can be displaced in the axial direction. A bearing which encloses a large part of the shaft makes it possible to carry out such a displacement particularly precisely and without tilting.

The bearing of the rotary switch in which the shaft is preferably formed as a sliding bearing. This allows a particularly simple and inexpensive design of the camp. But it can also be carried out in a particularly preferred manner as a rolling bearing. In any case, the bearing is designed so that it allows the rotation axis only one rotational degree of freedom, in a particularly preferred manner but also at least one translational degree of freedom.

Preferably, the latching contour has at least two mutually opposite latching depressions. In a particularly preferred embodiment, the latching contour has a plurality of latching depressions. In addition, it is known to arrange locking recesses with different depths on a latching contour. Preferably, the locking contour may also have elevations, whereby, for example, a rotation of the knob can be prevented by more than a complete revolution. The elevations are designed such that only a torque peak is generated, whereby advantageously a particular switching position is displayed.

Brief description of the drawings

Further advantageous embodiments will be described in more detail below with reference to an embodiment shown in the drawings, to which the invention is not limited.

Fig. 1

einen erfindungsgemäßen Drehschalter mit Rasteinrichtung für Elektrogeräte in einer perspektivischen Darstellung;

Fig. 2

eine Explosionsdarstellung des Drehschalters nach Fig. 1;

Fig. 3A und 3B

zwei Schnittansichten eines Drehschalter nach Fig. 1.

It shows schematically:

Fig. 1

a rotary switch according to the invention with latching device for electrical appliances in a perspective view;

Fig. 2

an exploded view of the rotary switch after Fig. 1 ;

FIGS. 3A and 3B

two sectional views of a rotary switch after Fig. 1 ,

Detailed description of the invention with reference to an embodiment

In the following description of a preferred embodiment of the present invention, like reference characters designate like or similar components.

In Fig. 1 is a perspective view of a rotary switch 1 with latching device as a control for electrical appliances in an embodiment shown with a scale. You can see a knob with a scale 2 which is mounted in a switch housing 4. The switch housing 4 has a pointer 5 for the scale 2 for reading the rotary switch position. In addition, the switch housing 4 comprises fastening means 6 with which the rotary switch can be mounted on an electrical appliance. The knob is completed with a cover 7.

Fig. 2 shows the rotary switch 1 off Fig. 1 in an exploded view, wherein the components are shown offset from each other in the axial direction. Two locking lugs 8 and a coil spring 9 are shown offset in the radial direction. In the embodiment shown, the latching device is divided into two components. A detent guide 10 includes a shaft 11 and a radial guide for a coil spring 9 at the two ends of each latching lugs 8 rest. The Coil spring 9 can move in the direction of force. The second component of the latching device is a switch housing 4, which comprises a bearing 12 designed as a slide bearing for the shaft 11 and an inner latching contour. In the embodiment shown, the switch housing 4 and the detent guide 10 are each made in one piece, for example using the injection molding process. The shaft 11 is rotatably connected after insertion into the bearing 12 with a knob 3. For this purpose, 11 detent springs 13 are provided with locking projections at the top of the shaft, which are connectable to corresponding counterparts in the knob 3. As a result, in particular the latching lugs 8 are rotatably connected to the knob 3. Between switch housing 4 and knob 3, a switch ring 14 is also introduced, which serves as a sliding pad for the knob 3 and also has a pointer 5 for a scale 2. A lid 7 can be removed from the knob 3, whereby openings in the knob 3 are accessible, through which the connection between the knob 3 and shaft 11 can be solved. As shown, a sliding contact 15 can be fastened to the latching nose guide 10 on the lower side, so that a connection with the switch electronics 16 is set.

Fig. 3A shows a sectional view of the rotary switch 1 after Fig. 1 , The section runs perpendicular to the plane of rotation through the axis of rotation and along the longitudinal axis of the locking lugs 8. As in Fig. 3A good to see, the bearing 12 of the shaft 11 is disposed between the knob 3 and the latching device. The detents 8 are mounted in the detent guide 10 on a coil spring 9, which can move along the direction of force. By using only one coil spring 9, which is movable in the direction of force, it is ensured that the spring force is evenly divided between the two locking lugs 8 and also acts in the locked position no force on the locking lug guide 10. Therefore, no force acts on the shaft 11. The two outer edges or tips of the locking lugs 8 are referred to as constraints. Furthermore, located at the top of the shaft 11 latching projections and detent springs 13 are shown, which engage in the corresponding counterparts of the rotary knob 3. This releasable connection mechanism makes it possible to arrange the bearing 12 of the shaft 11 between the knob 3 and the latching device. In addition, in the embodiment shown significantly more than half of the portion of the shaft 11 between locking device and knob 3 is enclosed by the bearing 12. This will be the Rotary switch 1 particularly reliable. When turning the shaft 11 does not tilt and does not get stuck.

In Fig. 3B is a cross section of the rotary switch after Fig. 1 shown. The section runs through the plane of rotation at the level of the locking lugs 8. In this view, the details of the locking device can be seen in more detail. The latching device is in a position in which the latching lugs 8 are engaged in a latching recess of a latching contour 17. In locking position, no force acts on the shaft 11. The locking lugs 8 have a substantially triangular cross-section, wherein the apex of the triangle is rounded and the radius of the rounding is less than two-fifths of the maximum width of the locking lugs 8. The tips of the triangles each form the supports of the detents 8. The illustrated detent contour 17 has a plurality of detent recesses. The detent recesses are arranged rotationally symmetrical in this embodiment, so that both detents 8 engage in each case in identically shaped, opposite detent recesses. But the embodiment shown also allows a locking contour 17, in which opposite locking recesses are unequal depth. The movable coil spring 9 compensates for this by a translation in the direction of force in each case. In the Fig. 3B shown latching contour 17 has rounded edges. In conjunction with the rounded supports of the locking lugs 8, the operation of the locking device is particularly wear.

The features disclosed in the foregoing description, the claims and the drawings may be of importance both individually and in any combination for the realization of the invention in its various forms.

The invention makes a rotary switch for electrical appliances in its operation particularly reliable. Due to the balanced distribution of forces in the locking device occur no disturbing torques that can lead to tilting of the shaft in the camp. In addition, the rounded shape of the locking lugs reduces wear and thus extends the life of the rotary switch. Furthermore, the invention enables a particularly cost-effective design of the rotary switch.

LIST OF REFERENCE NUMBERS

1.

rotary switch

Second

scale

Third

knob

4th

switch housing

5th

pointer

6th

fastener

7th

cover

8th.

locking lug

9th

coil spring

10th

Rest nose guide

11th

wave

12th

camp

13th

detent spring

14th

switch ring

15th

sliding contact

16th

switch electronics

17th

catch contour

Claims (8)

1. Rotary switch (1) with locking device as a control element for electrical appliances, wherein the rotary switch (1) comprises a rotary knob (3), a shaft (11) and a bearing (12) for the shaft (11) and the locking device comprises two lugs (8) resting against a locking contour (17) under spring force, and wherein the bearing (12) of the shaft (11) is arranged between the rotary knob (3) and the locking device and the locking contour (17) has a plurality of locking depressions arranged opposite one another in each case and elevations, wherein the elevations are embodied to generate a torque peak of the torque exerted onto the shaft (11) by the rotary knob (3), in order as a result to indicate a particular switching position of the rotary switch (1);
   characterised in that
   the lugs (8) are guided in a plane at right angles to an axis of rotation of the shaft (11) and the latching depressions and elevations of the latching contour (17) are arranged in this plane.
2. Rotary switch (1) with locking device according to claim 1, characterised in that the latching lugs (8) have rounded supports, wherein the radius of the roundness is less than two fifths of the maximum width of the lugs (8).
3. Rotary switch (1) with locking device according to claim 1 or 2, characterised in that the spring force is produced by a helical spring (9).
4. Rotary switch (1) with locking device according to one of the preceding claims, characterised in that in the latching position the latching lugs (8) exert no force on the shaft (11).
5. Rotary switch (1) with locking device according to one of the preceding claims, characterised in that the latching lugs (8) are guided radially outward with respect to the axis of rotation.
6. Rotary switch (1) with locking device according to one of the preceding claims, characterised in that the latching lugs (8) are connected to the rotary knob (3) in a torque proof manner.
7. Rotary switch (1) with locking device according to one of the preceding claims, characterised in that the bearing (12) encloses a large part of the section of the shaft (11) present between the locking device and the rotary knob (3).
8. Rotary switch (1) with locking device according to one of the preceding claims, characterised in that the bearing (11) is embodied as a friction bearing.

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