Permanent magnet unit

Abstract

The invention relates to a permanent magnet unit (100) for mounting on an axial end of a shaft, comprising: a magnet carrier (1) which is arranged to be fastened on the end of the shaft, the magnet carrier (1) comprising a plate (1.2) made of a ferromagnetic material and forming a magnet attraction surface (1.2. 1), the invention relates to a permanent magnet unit (100) comprising a magnet carrier (1) having a magnet attraction surface (1.2. 1) which extends transversely to the axial direction (Z) of a shaft in the state in which the permanent magnet unit (100) is mounted on the shaft, and at least one permanent magnet (2a, 2b) which is magnetically attracted on the magnet attraction surface (1.2. 1) of the magnet carrier (1), the magnet support element is fastened to the magnet carrier (1) and supports the respective permanent magnets (2a, 2b) in at least one support direction (X,-X, Y,-Y) extending parallel to the magnet attraction surface (1.2. 1).

Description

Technical Field

[0001] The present invention relates to a permanent magnet unit for installation on the axial end of a shaft, comprising: a magnet carrier, which is configured to be fastened on the end of the shaft, wherein the magnet carrier includes a plate member, which is made of ferromagnetic material and forms a magnet adsorption surface, which extends transversely to the axial direction of the shaft when the permanent magnet unit is installed on the shaft, and at least one permanent magnet, which is magnetically adsorbed on the magnet adsorption surface of the magnet carrier. Background Art

[0002] This type of permanent magnet unit is used in particular in a magnet-based rotation angle measurement system for detecting the rotational movement of a shaft, wherein the permanent magnet unit is mounted on the axial end of the shaft so as to rotate along with the shaft, and the magnetic field generated by the permanent magnet unit or the change in the magnetic field when the shaft rotates is detected with the aid of a suitable magnetic sensor unit.

[0003] A permanent magnet unit of the type mentioned in the introduction is known, for example, from DE 10 2015 101 246 A1. Summary of the invention

[0004] The object underlying the invention is to achieve a reliable positioning of at least one permanent magnet.

[0005] This object is achieved by a permanent magnet unit having the features of independent claim 1 .

[0006] The permanent magnet unit according to the invention comprises a magnet carrier, which is arranged to be fastened to the end of a shaft. Preferably, the magnet carrier comprises a thread so as to be screwed with the shaft. However, the magnet carrier can in principle be arranged to be mounted on the axial end of the shaft in any manner, for example by a press fit, an adhesive connection or a welded connection.

[0007] Here, according to the invention, the magnet carrier comprises a plate member, which is made of a ferromagnetic material, in particular a ferromagnetic metal, and forms a magnet attraction surface, which, when the magnet carrier is mounted on the shaft, extends transversely to the axial direction of the shaft, preferably substantially perpendicular to the axial direction of the shaft. Preferably, the magnet carrier for fastening to the end of the shaft also comprises a convex member (Stempel), which extends substantially perpendicular to the magnet attraction surface and is designed to be coaxially mounted on the shaft, so that the axial distance between the end of the shaft and the magnet attraction surface can be determined in a simple manner by the axial length of the convex member.

[0008] The permanent magnet unit according to the present invention further comprises at least one permanent magnet, at least one of which is magnetically, i.e. due to magnetic attraction, adsorbed on a magnet adsorption surface of a magnet carrier formed by a ferromagnetic plate. Advantageously, at least one permanent magnet is additionally bonded to the plate. Preferably, all permanent magnets are arranged on the side of the magnet adsorption surface opposite to the axis in the installed state of the permanent magnet unit. Preferably, at least one permanent magnet is configured as a block magnet, i.e. is configured as a square. Preferably, the permanent magnet unit according to the present invention comprises two, preferably substantially identical, permanent magnets, which are arranged on the magnet adsorption surface spaced apart from each other. Preferably, in a top view of the magnet adsorption surface, the two permanent magnets are arranged point-symmetrically with respect to the rotation axis of the shaft.

[0009] According to the present invention, the permanent magnet unit also includes a preferably one-piece magnet support element, which is fastened to the magnet carrier and supports each permanent magnet in at least one support direction extending parallel to the magnet adsorption surface and thus prevents at least one permanent magnet from sliding in the support direction, especially even when the shaft rotates and therefore when the permanent magnet unit rotates. Reliable positioning of at least one permanent magnet on the magnet adsorption surface can thereby be achieved. Preferably, the magnet support element supports each permanent magnet in at least one support direction extending radially relative to the shaft. The magnet support element is made of a non-ferromagnetic material, preferably plastic, and is preferably constructed as an injection molded part.

[0010] In a preferred embodiment of the permanent magnet unit according to the invention, the magnet support element supports each permanent magnet in two support directions extending perpendicularly to each other, so that the magnet support element prevents at least one permanent magnet from sliding in the two support directions extending perpendicularly to each other. This allows particularly reliable positioning of at least one permanent magnet on the magnet adsorption surface. Here, one of the two support directions preferably extends radially with respect to the axis, and the other of the two support directions therefore extends tangentially with respect to the axis.

[0011] Preferably, the magnet support element supports the respective permanent magnet on two opposite sides and thus in two opposite support directions, so that the magnet support element prevents the at least one permanent magnet from sliding in the two opposite support directions. This allows a particularly reliable positioning of the at least one permanent magnet on the magnet attraction surface. Preferably, the magnet support element supports the respective permanent magnet on two tangentially opposite sides with respect to the axis and / or on two radially opposite sides with respect to the axis.

[0012] Preferably, in addition to the magnet adsorption surface, the plate also forms two supporting surfaces, which are constructed on two opposite sides of the magnet adsorption surface with respect to the supporting direction, wherein the two supporting surfaces extend substantially perpendicularly to the magnet adsorption surface and preferably perpendicularly to the supporting direction, and support the permanent magnet in one supporting direction respectively, thereby preventing the corresponding permanent magnet from sliding in the corresponding supporting direction. In this way, particularly reliable positioning of at least one permanent magnet on the magnet adsorption surface can be achieved. Preferably, the two supporting surfaces support the corresponding permanent magnet in the radially outward supporting direction, so that the centrifugal force acting on the corresponding permanent magnet when the shaft rotates and then when the permanent magnet unit rotates is resisted by the mechanically relatively stable plate forming the supporting surface.

[0013] In a preferred embodiment of the permanent magnet unit according to the present invention, the magnet support element has at least one spring element, wherein the magnet support element supports a permanent magnet in a supporting direction respectively through each spring element. Here, each spring element can be elastically deformed at least in the corresponding supporting direction. If the magnet support element is installed on the magnet carrier after at least one permanent magnet, the at least one spring element enables a relatively simple installation of the magnet support element, or if the magnet support element is installed on the magnet carrier before at least one permanent magnet, the at least one spring element enables a relatively simple installation of at least one permanent magnet. In addition, tolerances caused by manufacturing can also be compensated by at least one spring element when at least one spring element is designed accordingly. Preferably, all spring elements are formed by correspondingly formed areas of a one-piece magnet support element.

[0014] Preferably, there are both two support surfaces and at least two spring elements, and the permanent magnet unit according to the present invention includes two permanent magnets, which are respectively attached to one of the two support surfaces on the outside, and the magnet support element has a central area arranged between the two permanent magnets. Here, at least two spring elements are preferably arranged in the central area so that at least two spring elements are respectively attached to the inner side of one of the two permanent magnets and press the corresponding permanent magnet outward onto the corresponding support surface. This can achieve particularly reliable positioning of at least one permanent magnet on the magnet attraction surface.

[0015] Preferably, the magnet support element has at least one elastically deformable snap-in element, by which the magnet support element is fastened to the magnet carrier. This enables the magnet support element to be simply mounted on the magnet carrier. Preferably, at least one snap-in element engages the plate from behind, particularly preferably from behind the part of the plate that forms the magnet adsorption surface. Preferably, the magnet support element has a plurality of snap-in elements, which are arranged on opposite lateral sides of the plate. Preferably, all snap-in elements are configured such that the magnet support element can be released from the magnet carrier again.

[0016] In a preferred embodiment of the permanent magnet unit according to the present invention, the magnet carrier has a thread for mounting on the shaft. This enables the permanent magnet unit to be mounted on the shaft simply and reliably. Here, the spiral thread can be configured as an external thread, such as an external thread on the outside of a pin or the like, and can also be configured as an internal thread, such as an internal thread on the inside of a hollow cylindrical convex part or the like. Here, the magnet support element is preferably connected to the magnet carrier in a relatively rotationally fixed manner and has a receptacle for a screwdriver, which is arranged so that the permanent magnet unit can be screwed to the shaft in a simple manner by inserting a screwdriver into the receptacle.

[0017] Preferably, the magnet support element is made of plastic. Particularly preferably, the magnet support element is designed as a plastic injection-molded part. This enables relatively cost-effective production of the magnet support element, wherein the magnet support element can also be designed to be relatively variable.

[0018] Preferably, the magnet support element has a larger axial extension than the at least one permanent magnet, so that the magnet support element protrudes axially beyond the at least one permanent magnet on the axial side facing away from the magnet attraction surface, thereby reducing the risk of mechanical damage to the at least one permanent magnet. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Embodiments of the present invention are described below with reference to the accompanying drawings.

[0020] Figure 1 shows a perspective view of the upper side of a permanent magnet unit according to the invention,

[0021] Figure 2 Shows Figure 1 A top view of the upper side of the permanent magnet unit in FIG.

[0022] Figure 3 Shows Figure 1 A perspective view of the underside of the permanent magnet unit in FIG.

[0023] Figure 4 Shows Figure 1 A three-dimensional view of the magnet carrier of the permanent magnet unit in FIG. 1 , together with the permanent magnets mounted thereon. DETAILED DESCRIPTION

[0024] The drawing shows a permanent magnet unit 100 according to the invention, which is designed to be mounted on an axial end of a shaft (not shown here) as a component of a rotation angle measuring system (not shown here).

[0025] The permanent magnet unit 100 comprises a magnet carrier 1 having a male part 1.1 and a plate part 1.2 which is fastened on an axial end of the male part 1.1.

[0026] The male part 1.1 comprises, in the axial end region facing away from the plate part 1.2, a thread 1.1.1 designed as an external thread, by means of which the magnet carrier 1 can be screwed into a correspondingly designed internal thread of the shaft in order to fasten the permanent magnet unit 100 on the shaft in a rotationally fixed manner.

[0027] The sheet metal part 1 . 2 consists of a ferromagnetic metal and has a U-shaped profile in a side view.

[0028] The plate 1.2 forms a magnet adsorption surface 1.2.1, which extends basically perpendicular to the axial direction of the convex part 1.1, and the axial direction corresponds to the Z direction in the drawing, that is, the magnet adsorption surface extends in the XY plane extending parallel to the X direction and the Y direction in the drawing, and the magnet adsorption surface further extends basically perpendicular to the axis when the permanent magnet unit 100 is installed on the axis.

[0029] In addition, the plate 1.2 forms a first supporting surface 1.2.2a and a second supporting surface 1.2.2b, which are constructed on the sides of the magnetic adsorption surface 1.2.1 that face each other in the X direction, and they extend from the convex part 1.1 to the distance and perpendicular to the magnetic adsorption surface 1.2.1 in a YZ plane extending parallel to the Y direction and the Z direction.

[0030] The permanent magnet unit 100 further includes a first permanent magnet 2a and a second permanent magnet 2b, which are substantially identical and are respectively constructed as block magnets, i.e., square-shaped, and are magnetically adsorbed on the magnet adsorption surface 1.2.1.

[0031] The first permanent magnet 2a lies with its outer side 2a.1 on the first supporting surface 1.2.2a, so that the first supporting surface 1.2.2a supports the first permanent magnet 2a in a supporting direction corresponding to the X direction.

[0032] The second permanent magnet 2b lies with its outer side 2b.1 on the second supporting surface 1.2.2b, so that the second supporting surface 1.2.2b supports the second permanent magnet 2b in a supporting direction corresponding to the −X direction opposite to the X direction.

[0033] The permanent magnet unit 100 further comprises a one-piece magnet support element 3 which is designed as an injection-molded part made of plastic and is fastened to the magnet carrier 1 , in particular to the plate 1 . 2 of the magnet carrier 1 , and is connected to the magnet carrier 1 in a rotationally fixed manner.

[0034] The magnet supporting element 3 comprises a central region 3.1 arranged between the first permanent magnet 2a and the second permanent magnet 2b, wherein the central region 3.1 supports the first permanent magnet in a supporting direction corresponding to the -X direction and supports the second permanent magnet 2b in a supporting direction corresponding to the X direction.

[0035] The magnet support element 3 also includes four elastically deformable spring elements 3.2a-3.2d, which are constructed in the central area 3.1 so that the first spring element 3.2a and the second spring element 3.2b are abutted against the inner side 2a.2 of the first permanent magnet 2a and support the first permanent magnet 2a in the -X direction and are pressed onto the first support surface 1.2.2a in the X direction, and the third spring element 3.2c and the fourth spring element 3.2d are abutted against the inner side 2b.2 of the second permanent magnet 2b and support the second permanent magnet 2b in the X direction and are pressed onto the second support surface 1.2.2b in the -X direction.

[0036] The magnet supporting element 3 also includes an arched first external region 3.3a adjacent to the central region in the Y direction and an arched second external region 3.3b adjacent to the central region in the -Y direction, wherein the first external region 3.3a supports the first permanent magnet 2a and the second permanent magnet 2b on the first end faces 2a.3 and 2b.3 in the Y direction, respectively, and the second external region 3.3b supports the first permanent magnet 2a and the second permanent magnet 2b on the second end faces 2a.4 and 2b.4 opposite to the first end faces 2a.3 and 2b.3 in the -Y direction, respectively.

[0037] The first snap-fit ​​element 3.4a is constructed on the first outer area 3.3a, and the second snap-fit ​​element 3.4b is constructed on the second outer area 3.3b, wherein the first snap-fit ​​element 3.4a and the second snap-fit ​​element 3.4b can respectively be elastically deformed and engage with the plate 1.2 from the back, in particular engage with the part of the plate 1.2 that forms the magnet adsorption surface 1.2.1 from the back, so that the magnet support element 3 is fastened to the magnet carrier 1 by the first snap-fit ​​element 3.4a and the second snap-fit ​​element 3.4b.

[0038] The magnet support element 3 also includes a receiving portion 3.5 for a screwdriver, which is constructed concentrically with the convex part 1.1 on the side of the central area 3.1 of the magnet support element 3 facing away from the convex part 1.1, so that the permanent magnet unit 100 can be screwed into the corresponding consistent thread of the shaft using the thread 1.1.1 by inserting a screwdriver into the receiving portion 3.5.

[0039] Reference numerals list

[0040] 100 Permanent Magnet Units

[0041] 1 Magnet carrier

[0042] 1.1 Convex parts

[0043] 1.1.1 Helical thread

[0044] 1.2 Panels

[0045] 1.2.1 Magnetic adsorption surface

[0046] 1.2.2a First support surface

[0047] 1.2.2b Second support surface

[0048] 2a The first permanent magnet

[0049] 2a.1 Outer side

[0050] 2a.2 Inside

[0051] 2a.3 First end face

[0052] 2a.4 Second end face

[0053] 2b Second permanent magnet

[0054] 2b.1 Outer side

[0055] 2b.2 Inside

[0056] 2b.3 First end face

[0057] 2b.4 Second end face

[0058] 3. Magnetic support element

[0059] 3.1 Central area

[0060] 3.2a First spring element

[0061] 3.2b Second spring element

[0062] 3.2c Third spring element

[0063] 3.2d Fourth spring element

[0064] 3.3a ​​The first external region

[0065] 3.3b Second external area

[0066] 3.4a First engagement element

[0067] 3.4b Second engagement element

[0068] 3.5 Accommodation section.

Claims

1. A permanent magnet unit (100) for mounting on an axial end of a shaft, comprising: a magnet carrier (1) arranged to be fastened to the end of the shaft, The magnet carrier (1) comprises a plate (1.2), the plate being made of a ferromagnetic material and forming a magnet adsorption surface (1.2.1), the magnet adsorption surface extending transversely to the axial direction (Z) of the shaft when the permanent magnet unit (100) is mounted on the shaft, and at least one permanent magnet (2a, 2b), at least one of the permanent magnets is magnetically adsorbed on the magnet adsorption surface (1.2.1) of the magnet carrier (1), It is characterized in that A magnet support element (3) is provided, which is fastened to the magnet carrier (1) and supports each permanent magnet (2a, 2b) in at least one supporting direction (X, -X, Y, -Y) extending parallel to the magnet adsorption surface (1.2.1).

2. The permanent magnet unit (100) according to claim 1, wherein: The magnet supporting element (3) supports each permanent magnet (2a, 2b) in two supporting directions (X, -X, Y, -Y) extending perpendicularly to each other.

3. The permanent magnet unit (100) according to any one of the preceding claims, wherein: The magnet support element (3) supports each permanent magnet (2a, 2b) on two opposite sides (2a.3, 2a.4, 2b.3, 2b.4).

4. The permanent magnet unit (100) according to any one of the preceding claims, wherein: The plate (1.2) forms two supporting surfaces (1.2.2a, 1.2.2b), which are constructed on two opposite sides of the magnet attraction surface (1.2.1) with respect to a supporting direction (X, -X), and the two supporting surfaces extend substantially perpendicular to the magnet attraction surface (1.2.1) and correspondingly support a permanent magnet (2a, 2b) in a supporting direction (X, -X).

5. The permanent magnet unit (100) according to any one of the preceding claims, wherein: The magnet support element (3) has at least one elastically deformable spring element (3.2a-3.2d), and the magnet support element (3) supports a permanent magnet (2a, 2b) in a supporting direction (X, -X) respectively through the spring element.

6. The permanent magnet unit (100) according to claim 4 and 5, comprising two permanent magnets (2a, 2b), the two permanent magnets respectively resting on one of the two support surfaces (1.2.2a, 1.2.2b) on the outside (2a.1, 2b.1), wherein: The magnet support element (3) has a central area (3.1) arranged between the two permanent magnets (2a, 2b) and has at least two spring elements (3.2a-3.2d), which are arranged on the central area (3.1) so that the two permanent magnets (2a, 2b) are pressed onto one of the two support surfaces (1.2.2a, 1.2.2b) by the at least two spring elements (3.2a-3.2d).

7. The permanent magnet unit (100) according to any one of the preceding claims, wherein: The magnet support element (3) has at least one elastically deformable snap-in element (3.4a, 3.4b), and the magnet support element (3) is fastened to the magnet carrier (1) via the snap-in element (3.4a, 3.4b).

8. The permanent magnet unit (100) according to any one of the preceding claims, wherein: The magnet carrier (1) has a thread (1.1.1) for mounting on the shaft, wherein the magnet support element (3) is connected to the magnet carrier (3) in a rotationally fixed manner and has a receptacle (3.5) for a screwdriver.

9. The permanent magnet unit (100) according to any one of the preceding claims, wherein: The magnet supporting element (3) is made of plastic.

10. The permanent magnet unit (100) according to any one of the preceding claims, wherein: The magnet support element (3) protrudes axially beyond at least one of the permanent magnets (2a, 2b) on an axial side facing away from the magnet attraction surface (1.2.1).

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