Rotary encoder comprising an elastic element for attaching a code disk

Abstract

A rotary encoder (1) comprising a housing (2), a shaft (3), a code disk (4) which is attached to the shaft (3), and a reading head (5) which is designed to detect the rotation of the code disk (4) are disclosed herein. The code disk (4) is affixed in the axial position thereof on an axial side by way of an abutment (6), and a resilient element (7, 17, 19) is arranged on the other axial side providing a clamping force for pressing the code disk (4) against the abutment (6). A method for assembling a rotary encoder is also disclosed herein.

Claims

1. A rotary encoder (1), comprising: a housing (2); a shaft (3); a code disk (4) which is attached to said shaft (3); and a reading head (5) which is configured to detect the rotation of said code disk (4); wherein said code disk (4) is affixed in an axial position on one axial side by an abutment (6) on said shaft (3); and a resilient element (7, 17, 19) is arranged on another axial side of said code disk and provides a clamping force with which said code disk (4) is pressed against said abutment (6) wherein said resilient element (7) is an annular or cylindrical elastomer element.

2. The rotary encoder according to claim 1, wherein said resilient element (7, 17, 19) extends in a circumferential direction around said shaft (3).

3. The rotary encoder according to claim 1, further comprising a first bearing (9) of said shaft (3) arranged such that the clamping force is introduced via said resilient element (7, 17) and said first bearing (9) into said housing (2).

4. The rotary encoder according to claim 3, further comprising a spacer sleeve (8) between said resilient element (7, 17) and said first bearing (9) which extends cylindrically around said shaft (3).

5. The rotary encoder according to claim 1, wherein said shaft (3) is a hollow shaft.

6. The rotary encoder according to claim 1, wherein said abutment (6) is provided by a shoulder in said shaft (3).

7. The rotary encoder according to claim 1, wherein said abutment (6) is a spacer ring which is arranged on a shoulder in said shaft (3).

8. The rotary encoder according to claim 1, wherein said shaft (3) is mounted with respect to a housing upper part (13) of said housing (2) with a first bearing (9) configured as a radial bearing, and wherein said shaft (3) is mounted with respect to a housing lower part (12) of said housing (2) on an oppositely disposed side of said shaft (3) with a second bearing (11) configured as an axial bearing.

9. The rotary encoder according to claim 8, wherein said second bearing (11) is configured as a sliding bearing in the form of a thrust washer protruding from a bearing seat (14) in said housing lower part (12).

10. The rotary encoder according to claim 8, wherein said first bearing (9) is a sliding bearing of said shaft (3) in said housing upper part (13), and wherein the clamping force is introduced into said sliding bearing through a spacer sleeve (8).

11. The rotary encoder according to claim 8, wherein said reading head (5) is arranged between said housing upper part (13) and said housing lower part (12).

12. The rotary encoder according to claim 1, further comprising a flange (10) at one end of said shaft (3), wherein said flange (10) is mounted with respect to said housing (2) by way of an axial bearing, and wherein a rear side of said flange (10) provides said abutment (3).

13. A rotary encoder, comprising: a housing (2); a shaft (3); a code disk (4) which is attached to said shaft (3); and a reading head (5) which is configured to detect the rotation of said code disk (4); wherein said code disk (4) is affixed in an axial position on one axial side by an abutment (6) on said shaft (3); and a resilient element (7, 17, 19) is arranged on another axial side of said code disk and provides a clamping force with which said code disk (4) is pressed against said abutment (6), wherein said resilient element (17, 19) is a disk spring or finger spring having a central opening therein, wherein said shaft (3) is arranged in said central opening.

14. A method for assembling a rotary encoder (1) comprising the steps of: providing a housing lower part (12) with a lower bearing (11); arranging a code disk (4), a resilient element (7, 17, 19) comprising one of an annular elastomer element, a cylindrical elastomer element, a disk spring, or a finger spring, and an upper bearing (9) on a shaft (3); introducing said shaft (3) into a housing upper part (13); arranging and attaching said housing upper part (13) to said housing lower part (12) so that said shaft (3) is mounted by said upper bearing (9) and said lower bearing (11), and a clamping force is applied by said upper bearing (9) via said resilient element (7, 17, 19) so that said code disk (4) is pressed against an abutment (6) on said shaft (3).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention shall be further described below in more detail with reference to preferred embodiments.

(2) FIG. 1 shows a lateral sectional view of a first embodiment of a rotary encoder according to the invention.

(3) FIG. 2 shows a lateral sectional view of a second embodiment of a rotary encoder according to the invention.

(4) FIG. 3 shows a lateral sectional view of a third embodiment of a rotary encoder according to the invention.

(5) FIG. 4 shows a lateral sectional view of a fourth embodiment of a rotary encoder according to the invention.

(6) FIG. 5 shows a lateral sectional view of a fifth embodiment of a rotary encoder according to the invention.

DETAILED DESCRIPTION

(7) The embodiment of a rotary encoder 1 according to the invention shown in FIG. 1 comprises a housing 2 in which a shaft 3 that is rotatable about an axis 100 is arranged. Shaft 3 extends in axial direction A. A code disk 4 is attached to shaft 3 and protrudes from shaft 3 in radial direction R. The rotation of code disk 4 can be detected by a reading head 5.

(8) Code disk 4 is pressed by a clamping force in axial direction A against an abutment 6 which is provided by shaft 3. Abutment 6 is in particular a flat surface with a normal in axial direction A. Abutment 6 extends in particular uniformly around the entire circumference of shaft 3.

(9) In the present embodiment, abutment 6 is configured as a flat surface in other embodiments, however, it is also possible for projections, such as pins or other shaped elements, to be provided which enable the code disk to be positioned precisely in the radial and/or the circumferential direction.

(10) The clamping force acting in axial direction A for clamping code disk 4 on abutment 6 is provided or defined by a resilient element 7 which, in the present embodiment, is arranged directly on code disk 4. Resilient element 7 is configured as an O-ring made of an elastomer material. A spacer sleeve 8 is provided in axial direction A above resilient element 7. Spacer sleeve 8 can have different lengths in the axial direction, but can also be omitted entirely in some embodiments.

(11) A first bearing 9 is arranged in axial direction A above spacer sleeve 8 and is part of the bearing of shaft 3 in housing 2. First bearing 9 is able to transmit the clamping force in axial direction A onto housing 2. The clamping force is determined in particular by the installation height in the housing, the position of the abutment on shaft 3, the axial length of resilient element 7 as well as first bearing 9 and possibly spacer sleeve 8, as well as by the resilience or compressibility of resilient element 7.

(12) In the present embodiment, abutment 6 is provided by a flange 10 at the end of shaft 3. The shaft can then be produced in just one turning process, without the need for a turning process on the end side of flange 10. The inner bore of shaft 3, which is configured as a hollow shaft, can also be bored in a turning process.

(13) Flange 10 is also used to support shaft 3 relative to housing 2 by way of a second bearing 11 in the form of an axial bearing. Second bearing 11 is configured in particular in the form of a thrust washer.

(14) Housing 2 comprises a housing lower part 12 and a housing upper part 13, where housing parts 12, 13 are each provided with an opening so that a connection to an external component can be established from both sides of shaft 3. However, only one opening in housing lower part 12 or in housing upper part 13 can also be provided. A bearing seat in the form of an annular groove 14 for receiving second bearing 11 is advantageously provided in the housing lower part.

(15) Otherwise, housing lower part 12 is configured to be substantially flat. Housing upper part 13, on the other hand, is pot-shaped so that the components of rotary encoder 1 contained therein, in particular shaft 3, code disk 4, and reading head 5 are protected from external influences, in particular dust or dirt and mechanical damage.

(16) Provided in housing upper part 13 is a bearing seat 15 in which first bearing 9 is received. Since the distance between bearing seats 14 and 15 is defined by housing 2, the clamping force acting upon code disk 4 with fully assembled housing 2 can be precisely predetermined by appropriate selection bearings 9, 11, resilient element 7, and optionally a spacer sleeve 8.

(17) In one embodiment of rotary encoder 1 according to the invention, housing lower part 12 can be omitted and rotary encoder 1 can be screwed directly onto an attachment surface on which in particular a surface serving as a thrust ring or a bearing seat for second bearing 11 is provided.

(18) Housing lower part 12 and housing upper part 13 are connected to one another by screwing, clamping, adhesive bonding or by clip elements, so that closed housing 2 is created. Seals are provided between housing 2 and shaft 3 and between housing parts 12, 13 and in other potential gaps in the housing, so that housing 2 is protected against liquids and dust. The seals can be part of the rolling bearings provided.

(19) The method for assembling rotary encoder 1 can be explained by way of example using FIG. 1: Housing lower part 12 is first provided, into which second bearing 11 is inserted. Shaft 3 is arranged in second bearing 11. Code disk 4, then resilient element 7, spacer sleeve 8, and then first bearing 9 are pushed onto shaft 3 up to abutment 6. Reading head 5 is arranged on housing lower part 12. Housing upper part 13 is then mounted and connected to housing lower part 12, in particular screwed on. As a result, a defined distance is specified between bearings 9, 11, and resilient element 7 is compressed by a predetermined distance, whereby a predetermined bearing preload force or clamping force is generated for code disk 4.

(20) Alternatively, the method for assembling rotary encoder 1 can be carried out as follows: Code disk 4, resilient element 7, spacer sleeve 8, and first bearing 9 are first pushed onto shaft 3 up to abutment 6. Reading head 5 is inserted into housing upper part 13. Then shaft 3 with first bearing 9 is inserted into housing upper part 13 into bearing seat 15. At the same time, code disk 4 is pushed into reading head 5. Second bearing 11 is thereafter inserted into bearing seat 14 of housing lower part 12. Housing upper part 13 is then mounted and connected to housing lower part 12, in particular screwed on. As a result, a defined distance is specified between bearings 9, 11, and resilient element 7 is compressed by a predetermined distance, whereby a predetermined bearing preload force or clamping force is generated for code disk 4.

(21) As an alternative, it is also possible, for example, to assemble in the reverse order by first arranging bearing 9, spacer sleeve 8, resilient element 7, and code disk 4 in housing upper part 13, and to then insert shaft 3 into these components. Second bearing 11 and housing lower part 12 are thereafter brought into position and housing parts 12, 13 are connected.

(22) As a further alternative, bearing 9 is pressed onto housing upper part 13. Code disk 4, resilient element 7, and spacer sleeve 8 are placed onto shaft 3. Then shaft 3 is joined together with reading head 5 on bearing 9 and thereby housing upper part 13. Second bearing 11 and housing lower part 12 are thereafter brought into position and housing parts 12, 13 are connected.

(23) Further embodiments of rotary encoders 1 according to the invention are shown in FIGS. 2 to 5, where mainly the differences to the first embodiment shall be explained below:

(24) In the embodiment according to FIG. 2, abutment 6 comprises a positioning element 16 in the form of a circumferential projection, whereby the inner opening of code disk 4 can be selected and centered decoupled from the bearing or shaft diameter.

(25) In addition to or independently thereof, a resilient element 17 in the form of a disk spring is provided which applies a resilient clamping force in axial direction A directly between first bearing 9 and code disk 4. While plug connection 18 of reading head 5 in the first embodiment according to FIG. 1 protrudes laterally outwardly between housing parts 12 and 13, it is directed downwardly through an opening in housing lower part 12 in the embodiment according to FIG. 2. Overall, the second embodiment according to FIG. 2 results in a compact configuration in the axial direction, although a high clamping force can still be achieved due to the use of resilient element 17 in the form of the disk spring.

(26) FIG. 3 shows a further embodiment of a rotary encoder according to the invention, where a resilient element 19 in the form of a shoulder disk is there provided which is clamped at its radially inner end between first bearing 9 and flange 10 formed integrally with shaft 3. The radially outer end of the shoulder plate is resiliently deformed in such a way that it provides the clamping force for affixing code disk 4. In this embodiment, the clamping force for code disk 4 is independent of the preload force of bearings 9, 11. In particular, resilient element 19 in the form of the shoulder disk is made of a metallic material. The shoulder disk is at least twice as thick in its inner region as in its radially outer region.

(27) Instead of a shoulder disk, only a flat washer, i.e. a flat element without a shoulder, can be provided as the resilient element and apply a corresponding clamping force upon code disk 4 by elastic deformation. A step 20 can advantageously be provided in flange 10 radially within abutment 6 in order to reduce the necessary deformation of the resilient element and to center code disk 4. First bearing 9 is advantageously a sliding bearing. It can then be prevented that the outer race of a rolling bearing comes into undesired frictional contact with resilient element 19, even with a large diameter of resilient element 19 in the form of a shoulder disk or a flat washer.

(28) In the further embodiment of rotary encoder 1 of the invention according to FIG. 4, bearings 9, 11 are each provided directly by sliding surfaces in housing 2. Flange 10 of shaft 3 runs directly on a sliding surface of housing lower part 12, and spacer sleeve 8 runs directly on a sliding surface of housing upper part 13. A resilient element 7 is again provided between spacer sleeve 8 and code disk 4 and causes the bearing force in axial direction A and accordingly the clamping force for code disk 4.

(29) In the embodiment according to FIG. 5, shaft 3 is supported by first bearing 9 and second bearing 11, each of which is configured as a rolling bearing. For this purpose, shaft 3 has a flange region 21 that is stepped back in which second bearing 11 is arranged. The clamping force for affixing code disk 4 is again applied to code disk 4 by housing 2 via first bearing 9 and spacer sleeve 8 as well as resilient element 7.

(30) Alternatively, second bearing 11 can also be arranged on a locking ring which is arranged in flange region 21. For this purpose, second bearing 11 can have an inner diameter which corresponds to the outer diameter of flange 10.