Patent Publication Number: US-2019180960-A1

Title: Indexed rotary switch

Description:
RELATED APPLICATIONS 
     This application corresponds to PCT/EP2017/070944, filed Aug. 18, 2017, which claims the benefit of German Application No. 10 2016 115 548.9, filed Aug. 22, 2016, the subject matter of which are incorporated herein by reference in their entirety. 
    
    
     The invention relates to an indexed rotary switch, in particular a rotary pushbutton switch in a vehicle. 
     Indexed rotary switches include a latching cam for a spring-mounted projection to engage therein. The increment of the indexing is predefined by the distance of the individual latching contours of the latching cam, between which the projection can engage. The projection is part of a spring ring, for example, which is arranged between the rotary member of the rotary switch and a base body and urges the rotary member away from the base body, the projection being urged against the latching cam. The spring force, on the one hand, causes the projection to be urged into the latching cam or between the latching contours. On the other hand, the entire rotary member is urged away from the base body and is thus held free of play. By way of supplement, a pushbutton switch may additionally be integrated by moving the rotary member against an electrical contact contrary to the spring force of the spring ring, DE 10 2014 106 568 A1 shows a typical rotary switch of this type. 
     In rotary switches of this type it is necessary for the spring ring to be securely fixed in place in order to ensure precise control and thus the desired high level of operating comfort. Various methods for securely fastening spring rings in rotary switches are known from the prior art. For one thing, additional fastening means such as screws or bolts are made use of for fixing the spring ring in place. For another thing, use is made of plastic pins that extend through the spring ring and are deformed at a high temperature so that the spring ring is secured with an interlocking fit. However, these methods have the drawback that they require additional components or systems in manufacture and therefore involve higher cost and effort. 
     SUMMARY OF THE INVENTION 
     It is therefore the object of the invention to provide a rotary switch having a more cost-efficient fastening for a spring ring. 
     To achieve the object, provision is made for an indexed rotary switch, in particular a rotary pushbutton switch in a vehicle, including a base body and a spring ring, the spring ring being locked to the base body so as to prevent rotation. The spring ring and/or the base body include(s) latching elements here which can latch to each other and in this way ensure a rotationally fixed and secure fastening of the spring ring, in particular in the axial direction, without this requiring any additional fastening means or special tools. The spring ring may have a shape deviating from that of a ring; in particular, half a spring ring also is a spring ring within the meaning of the invention. 
     According to an advantageous embodiment, the spring ring includes two holding sections located radially opposite each other. Further, two fastening sections which each have a supporting surface are provided on the base body, the spring ring resting by the holding sections against the fastening sections in the axial direction. By having the spring ring including two holding sections radially opposite each other, the spring ring is mounted on the base body with greater stability. The contact in the axial direction ensures that the axial forces which occur upon actuation of the rotary switch can be better transmitted from the spring ring to the base body and can be better absorbed by the rotary switch. 
     Each fastening section may have a recess which interrupts the supporting surface at least in sections. This recess thus forms a gap between the holding section of the spring element and the fastening section of the base body, allowing the spring element to be pressed into this recess at least in sections. This overpressing of the holding sections can be utilized when fastening the spring element, in order to ensure that the spring element is securely latched to the base body. 
     Preferably, the recess comprises at least 50%, in particular 100%, of the width of the supporting surface in the radial direction. This has the advantage that the gap extends under the holding section as far as possible in the radial direction, to allow the latter to be overpressed in as large a radial region as possible. 
     The recess in the circumferential direction preferably has a length which comprises at least 25%, preferably at least 50%, more preferably at least 75% of the length in the circumferential direction of the holding sections. This design is advantageous since in this way the gap in the circumferential direction accounts for as large a region as possible under the holding section, allowing the holding section to be overpressed more easily. 
     It is of advantage if the recess has a depth in the axial direction of less than 1 mm, preferably less than 0.5 mm, more preferably of 0.1 mm. In this way, the recess is sufficiently deep to ensure that the latching elements snap securely into place, but at the same time only so deep that the spring ring will not be damaged by the deformation during overpressing. In addition, in these cases the bottom of the recess may serve as a stop, by means of which the process reliability can be increased, in particular in the case of manual fastening of the spring ring. 
     In a preferred embodiment, the holding sections have holding tabs provided thereon for mounting the spring ring so as to prevent rotation. Due to their design, holding tabs offer additional fastening possibilities and are therefore suitable for ensuring that the spring ring is fixed in the axial and circumferential directions. 
     In a further preferred embodiment, each holding section has two holding tabs provided thereon that are opposite each other and form a U-profile together with the holding section. This design improves the stability of the spring ring and defines the radial position of the spring ring. 
     Each holding section preferably includes a holding tab having a latching tongue and each fastening section includes a respective undercut in which the latching tongue can latch in the axial direction. In this way, the spring element can be simply and securely fastened in the axial direction without any additional fastening means, such as screws or bolts, being required therefor. 
     It is advantageous if at least some of the holding tabs have latching lugs which can each latch with a fastening section. This provides additional fastening means which can be intended to secure the fastening of the spring ring to the base body. 
     Preferably, each fastening section comprises a groove in which a holding tab can be received so as to prevent rotation. In this way the stability of the fastened spring ring is increased, in particular in that torques can be absorbed which otherwise caused the spring ring to tilt or turn. 
     In an advantageous embodiment, each holding section includes a holding tab having one, in particular two oppositely arranged tab sections, the tab sections projecting from the holding tabs in or against the circumferential direction and resting against the corresponding fastening sections on preferably angled circumferential surfaces in the radial direction. The tab sections increase the contact surface by which the holding tabs rest against the base body, and thereby improve the stability of the spring ring. By the circumferential surfaces of the fastening sections being angled in the regions opposite the tab sections in relation to those regions in which the holding tabs do not have a tab section, the spring ring is fixed in place in or against the circumferential direction. 
     The rotary switch may comprise a rotary member which is rotatable about a longitudinal axis and is mounted on the base body for limited displacement in the direction of the longitudinal axis, a latching cam having latching contours being provided on the base body and/or on the rotary member. Further, the spring ring may include an indexing section having a resiliently yielding projection which can engage in the latching cam. This design provides the functionalities of the indexed rotary pushbutton switch in an efficient manner, namely the adjusting of the rotary member in the axial direction to at least two positions and the rotating of the rotary member about the longitudinal axis to a plurality of positions as predefined by the latching cam. 
     Preferably, the spring ring is pretensioned against the latching cam such that the at least one projection of the indexing section engages between two neighboring latching contours. The projection in the indexing section is thereby securely mounted between two latching contours, allowing the rotary switch to be adjusted to clearly defined positions. 
     To prevent the spring ring from rotating along with the latching cam, holding tabs are preferably provided on the spring ring for mounting the spring ring so as to prevent rotation, the holding tabs more particularly projecting in the opposite direction than the contact surface and the projection. 
     According to a further preferred embodiment, the spring ring comprises at least one contact section which includes a contact surface that can rest on the latching cam, the radius of curvature of the contact surface being considerably larger than the radius of curvature of the projection, and the contact section being pretensioned against the latching cam such that the contact section rests by the contact surface on at least two neighboring latching contours of the latching cam and acts on the rotary member in the axial direction. In this way, in addition to the indexing section, by which the indexing of the rotary switch is provided in the known manner, the rotary switch comprises a contact section which rests at the cam but cannot engage into it. This means that the contact surface of the contact section is springily pressed against the latching cam, so that an increased friction is produced between the latching cam and the contact surface, the friction providing a resistance when the rotary member is rotated. This resistance, which is provided additionally, may be made use of for increasing the operating comfort. 
     When the rotary switch is rotated, the indexing section, which is arranged on one side of the spring ring, is periodically deflected by the latching contours, whereby the spring ring is deformed and tensions are produced in the spring ring. In order that these tensions do not affect the contact section which is arranged in particular on the opposite side of the indexing section, it is particularly important that the spring ring is securely fastened to the holding sections which are arranged in particular between the indexing section and the contact section. The fastening of the rotary switch according to the invention ensures that the contact section is decoupled from the indexing section and rests against the latching cam with an essentially constant pretensioning farce. In this way, a defined frictional resistance can be provided at the rotary member, although the spring ring is variably deformed at the indexing section upon rotation. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Further advantages and features will be apparent from the description below in conjunction with the accompanying drawings, in which: 
         FIG. 1  shows a perspective view of a rotary switch from the prior art; 
         FIG. 2  shows a perspective view of the spring ring of the rotary switch of  FIG. 1 ; 
         FIG. 3  shows a perspective view of a rotary switch according to the invention; 
         FIG. 4  shows a perspective view of the spring ring of the rotary switch of  FIG. 3 ; 
         FIG. 5  shows a schematic sectional view of the mounting of the spring ring in the rotary switch of  FIG. 3 ; 
         FIG. 6  shows a schematic sectional view of the mounting of the spring ring in a further embodiment of the rotary switch according to the invention; 
         FIG. 7  shows a schematic sectional view of the mounting of the spring ring in the rotary switch of  FIG. 6 ; 
         FIG. 8  shows a perspective view of a further embodiment of a spring ring for a rotary switch according to the invention; 
         FIG. 9  shows a schematic sectional view of the mounting of the spring ring of  FIG. 8  in a rotary switch according to the invention; and 
         FIG. 10  shows a schematic side view of the mounting of the spring ring of  FIG. 8  in a rotary switch according to the invention. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  shows a rotary switch  10 ′ from the prior art. The rotary switch  10 ′ has a base body  12 ′ which has a rotary member  14 ′ mounted thereon for rotation about a longitudinal axis L′ and for limited displacement in the direction of the longitudinal axis L′. The base body  12 ′ includes a protruding dome  16 ′ which extends into the interior of the rotary member  14 ′. 
     Provided on the lower front face, with respect to  FIG. 1 , of the rotary member  14 ′ is an indexing member  18 ′ which includes a latching cam  20 ′ protruding contrary to the longitudinal direction L′ and having a plurality of latching contours  22 ′, Further provided on the base body  12 ′ is a shoulder  24 ′ on which the spring ring  26 ′ rests which is shown in  FIG. 2 . 
     The spring ring  26 ′ is stamped out of a metal sheet and has a pair of protruding holding tabs  28 ′ bent at right angles contrary to the longitudinal direction L′ and engaging into slots on the shoulder  24 ′ so that the spring ring  26 ′ is mounted on the base body  12 ′ so as to prevent rotation in the circumferential direction U. The spring ring  26 ′ further includes a pair of indexing sections  30 ′ which each have a projection  32 ′ and spring sections  34 ′ that are arranged in front of and behind the projections  32 ′ in the circumferential direction U. 
     As can be seen in  FIG. 1 , the spring ring  26 ′ rests on the shoulder  24 ′ by a pair of holding sections  36 ′ which are located opposite each other in the circumferential direction and have the holding tabs  28 ′ provided thereon, and is held by the holding tabs  28 ′ so as to prevent rotation about the longitudinal axis L′ with respect to a direction of rotation. 
     The rotary member  14 ′ is placed with its latching cam  20 ′ on the base body  12 ′ such that the indexing sections  30 ′ are pretensioned in the longitudinal direction L′ between the shoulder  24 ′, that is, the base body  12 ′ and the latching cam  20 ′ of the rotary member  14 ′. This causes the projections  32 ′ to be urged against the latching cam  20 ′ or the latching contours  22 ′ and between the latching contours  22 ′. 
     Rotation of the rotary member  14 ′ is only possible when the projections  32 ′ are urged back by the latching contour  22 ′ contrary to the longitudinal direction L′. The projections subsequently snap into the next recess  38 ′ between the latching contours  22 ′. 
     Instead of a spring ring  26 ′ having two indexing sections  30 ′, spring rings  26 ′ are also known from the prior art in which one of the two indexing sections  30 ′ is replaced by a contact section having a contact surface. 
     In contrast to the projection  32 ′, the contact surface has a considerably smaller curvature, as a result of which it cannot engage between the latching contours  22 ′, but can only rest on the latching cam  20 ′, that is, the latching contours  22 ′. 
     Thus, while the spring sections  34 ′ provide a spring force in the longitudinal direction L′, no additional force is provided for indexing the rotary member  14 ′ since the contact surface cannot engage between the latching contours  22 ′. 
     The contact surface therefore generally increases the frictional resistance in the direction of rotation of the rotary member  14 ′ without changing the characteristic of the indexing by the projection  32 ′ and the latching cam  20 ′. 
     A spring ring  26 ′ having an indexing section and a contact section thus has a dual function: For one thing, the spring ring provides for the indexing of the rotary switch  10 ′ or of the rotary member  14 ′. For another thing, the spring ring  26 ′ generally increases the friction between the rotary member  14 ′ and the base body  12 ′ or provides a spring force in the longitudinal direction L′, which, firstly, allows the haptics of the rotary switch  10 ′ to be adjusted and, secondly, allows the rotary member  14 ′ to be mounted free of play, without a change in the characteristic of the indexing. 
     In addition, the rotary switch  10 ′ may have a push function, so that an electrical contact is established by pushing in the rotary member  14 ′ contrary to the longitudinal direction L. 
     The resistance to a pressing in of the rotary member  14 ′ may be increased, for example by increasing the spring tension of the spring sections  34 ′. 
     In this embodiment, the spring ring  26 ′ is fastened in slots on the shoulder  24 ′ merely by means of the holding tabs  28 ′. To be able to mount the delicate spring ring  26 ′ manually without bending it, the holding tab  28 ′ is dimensioned with clearance with respect to its seat. This will promote assembly errors. Even with correct assembly, however, there is no defined, fixed position relative to the latching cam  20 ′. 
     To overcome these problems, the rotary switch  10  according to the invention shown in  FIG. 3  having the spring ring  26  shown in  FIG. 4  is provided. The rotary switch  10  essentially corresponds to the rotary switch  10 ′ shown in  FIG. 1  and includes at its shoulder  24 ′ two fastening sections  40 , each having a supporting surface  42 , against which the spring ring  26  rests by its holding sections  36  in the axial direction A. The spring ring  26  shown in  FIG. 4  essentially corresponds to the spring ring  26 ′ shown in  FIG. 2  and, instead of a second indexing section  30 ′, it may comprise the contact section already mentioned above (provided with reference number  44  here). The considerably smaller curvature in comparison to the projection  32  can be clearly seen. 
     This spring ring  26  is also stamped out of a metal sheet and is constructed to be symmetrical with respect to the axis M. The spring ring  26  further includes two holding sections  36  located opposite each other in the circumferential direction U and each offset by about 90° from the indexing section  30  or the contact section  44  in the circumferential direction U. 
     Each holding section  36  comprises a pair of holding tabs  28 , an outer holding tab  48  arranged radially on the outside of the spring ring  26 , and an inner holding tab  50  arranged radially on the inside of the spring ring  26 . The outer and inner holding tabs  48 ,  50  of each holding section  36  are bent at right angles and protrude in the axial direction A, so that they form a U-profile with the respective holding section  36  (see  FIGS. 5 and 6 ). 
     In comparison to the outer holding tab  48 , the inner holding tab  50  protrudes further in the axial direction A and includes a latching tongue  52  and two latching lugs  54 . 
     The latching tongue  52  is formed by a section arranged centrally in the inner holding tab  50  and deflected radially inwards and counter to the axial direction A. 
     The latching lugs  54  project from the inner holding tab  50  oppositely to each other and in and counter to the circumferential direction U, respectively. 
       FIG. 5  shows a sectional view taken through the sectional axis S (see  FIG. 4 ) of the spring ring  26  in its state installed in the rotary switch  10 , with the base body  12  of the rotary switch  10  being illustrated cut off at the level of the spring ring  26  for greater clarity. 
     The base body  12  has a groove  56  at each fastening section  40  for receiving the inner holding tab  50  and, adjacent to the groove  56 , an undercut  58  in which the latching tongue  52  of the inner holding tab  50  can latch counter to the axial direction A. 
     The spring ring  26  rests against the supporting surfaces  42  of the fastening sections  40  in the axial direction A. The fastening sections  40  each have a recess  60  under the holding section  36  in the axial direction A, so that at these points the supporting surfaces  42 , against which the spring ring  26  rests, are interrupted. 
     The depth T of the recess  60  in the axial direction A may range from 0.1 mm to 1 mm. 
     In an alternative embodiment, the depth T of the recess  60  in the axial direction A may be more than 1 mm, in particular 2 mm to 5 mm. 
     The width b of the recess  60  in the radial direction amounts to about half the width B of the supporting surface  42  in the radial direction. 
     As in the embodiment shown in  FIG. 6 , the recess  60  may also extend over the entire width B. 
       FIG. 7  shows the holding section  36 , resting against the supporting surface  42 , from  FIG. 6  in a side view. The recess  60  interrupts the supporting surface  42  in the circumferential direction U, so that the holding section  36  rests against the fastening section  40  at two sections of the supporting surface  42  separate from each other. 
     The length g of the recess  60  in the circumferential direction U may be between 25% and 75% of the total length Q in the circumferential direction U of the holding section  36 . 
     The fastening section  40  protrudes from the shoulder  24  counter to the axial direction A. 
     The groove  56  comprises a first section  62  adjacent to the holding section  36  and a second section  64  adjoining the first section  62  in the axial direction. 
     The second section  64  has a width r in the circumferential direction U. The width r substantially corresponds to the width of the inner holding tab  50 , so that the latter is accommodated in the groove  56  in the circumferential direction U by means of an interlocking fit. 
     The first section  62  has a larger width R as compared with the width r of the second section  64 , as a result of which the groove  56  is configured to latch with the latching lugs  54  protruding from the inner holding tab  50  in the circumferential direction U. 
     The inner holding tab  50  has rounded portions  66  at its end projecting from the spring ring  26  in the axial direction U in order to prevent the holding tab  50  from getting caught with the groove  56  during insertion and thus to facilitate insertion. 
     When mounting the spring ring  26 , the spring ring  26  is inserted into the base body  12  so that the inner holding tabs  50  protrude into the corresponding grooves  56  of the fastening sections  40  and the holding section  36  abuts against the supporting surfaces  42  in the axial direction A. The holding sections  36  are then pressed into the recesses  60  beyond their contact position. During this overpressing, the spring ring  26  is elastically deformed and springs back again when the pressure decreases, so that the latching tongues  52  snap into the corresponding undercuts  58  and the spring ring  26  is mounted free of play. 
     The holding sections  36  have notches  67  (see  FIG. 4 ) on the radial inner side, i.e. on the side on which the inner holding tabs  50  are arranged, the notches  67  improving the flexibility of the holding sections  36  in the region of the inner holding tabs  50  and thus facilitating the latching of the spring ring  26  by overpressing. 
     The overpressing of the spring rings  26  can be effected in the course of manufacture by means of a hand lever press (not shown). 
     In a further embodiment, the recesses  60  may be configured to be very shallow and have a depth t of up to 0 mm, i.e. embodiments of the rotary switch  10  according to the invention that have no recesses  60  are also possible. Here the supporting surfaces  42  or the fastening sections  40  are elastically deformed during assembly by the pressure on the holding sections  36 , so that the latching tongues  52  latch into the corresponding undercuts  58  and the spring ring  26  is mounted free of play. 
     The overpressing causes the spring ring  26  to be firmly connected to the base body  12  in the axial direction A, in particular under pretension. Since the inner holding tabs  50  are received with a form fit in the second section  64  of the groove  56  in the circumferential direction U, the spring ring  26  is additionally mounted such that rotation is prevented. The inner and outer holding tabs  48 ,  50 , configured as a U-profile with the holding section  36 , further ensure a secure fastening in the radial direction. In this way, the spring ring  26  can be fastened to the base body  12  free of play and process-reliably without additional fastening means. 
     Due to the fact that the width of the groove  56  in the radial direction is roughly the same as the thickness of the inner holding tab  50  (see  FIG. 5 ), the latching tongues  52  in the respective undercuts  58  are prevented from being disengaged. As a result, the spring ring  26  further cannot be removed without a deformation of the base body  12  and/or of the spring ring  26 . 
     The spring ring  26  shown in  FIG. 8  substantially corresponds to the spring ring  26  shown in  FIG. 4 , but has additional tab sections  68  on the outer holding tabs  48 . Each outer holding tab  48  has two oppositely arranged tab sections  68  provided thereon, which project from the outer holding tab  48  in or counter to the circumferential direction U, respectively. 
     The tab sections  68  are formed in one piece with the outer holding tabs  48 . 
     The tab sections  68  are angled from the outer holding tab  48  in the radial direction toward the longitudinal axis L at an angle α (see  FIG. 9 ). 
       FIG. 9  shows a section perpendicular to the longitudinal axis L taken through a fastening section  40  of a rotary switch  10  according to the invention, against which the spring ring  26  from  FIG. 8  rests. 
     The fastening section  40  has circumferential surfaces  70  on its radial outer surface  72  (see also  FIG. 3 ), which are angled in relation to the outer surface  72  and located opposite the tab sections  68 . 
     The outer holding tab  48  rests against the outer surface  72 , while the tab sections  68  rest against the circumferential surfaces  70 . 
     By the tab sections  68  being arranged on the outer holding tab  48  opposite to each other and resting against the angled circumferential surfaces  70 , the spring ring  26  is fixed in place both in and counter to the circumferential direction U. 
     The outer holding tab  48  having the tab sections  68  can rest against the shoulder  40  with the inner holding tab  50  under pretension so that a press fit is formed. For an easier placement of the spring ring  26 , the shoulder  40  may have appropriate chamfers on the axial edges. 
     Further, the outer holding tab  48  may rest by the tab sections  68  in the axial direction A against one or more second shoulders  74  provided on the fastening section  40  or on the base body  12  (see  FIG. 10 ), which protrude from the outer surface  72  in the radial direction. 
     As is shown in  FIG. 10 , the second shoulders  74  are configured such that only the tab sections  68  rest on the second shoulders  74 , while the portion between the tab sections  68  that is formed by the holding tab  48  does not rest on or against the second shoulders  74 . 
     When the spring ring  26  is mounted, the second shoulders  74  support the tab sections  68  against the force applied to the holding section  36  in the axial direction A and thus facilitate the elastic pushing-in of the holding section  36  into the recess  60  beyond its contact position at the supporting surfaces  42 . Furthermore, the position of the spring ring  26  is additionally stabilized, in particular by the contact surface, which is wider in the circumferential direction U, and thus the risk of the spring ring  26  being tilted or twisted is further reduced. 
     In a further embodiment, the second shoulders  74  may include an additional axial section  76 , with which the second shoulders  74  form an L-profile in the circumferential direction U. 
     The additional axial section  76  borders the tab sections  68  in the radial direction and in this way increases the stability of the spring ring  26 .