Electric motor with angle sensor, in particular hollow shaft encoder

Abstract

Proposed is an electric motor having an angle sensor, wherein a rotor shaft of the electric motor is connected to an attachment shaft, wherein the attachment shaft has a threaded region, a guide region, a cylindrical portion that effects a centering fit 3, a second non-circular portion, a connecting region, and a first non-circular portion, wherein the rotor shaft has a stepped bore and the threaded region is screwed into an internally threaded region of the rotor shaft, wherein a thread run-out region adjoins the internally threaded region of the rotor shaft, and wherein the guide region of the attachment shaft is received with play in the rotor shaft.

Description

[0001] Electric motor with angle sensor, especially hollow shaft encoder

[0002] Description:

[0003] The invention relates to an electric motor with an angle sensor, in particular a hollow shaft sensor.

[0004] From EP 2 999 094 B1, an attachment shaft for connection to an angle sensor is known, which is adhesively connected to a rotor shaft of an electric motor and has a venting spiral groove.

[0005] From DE 10 2013 002 049 A1, a sensor arrangement is known as the closest prior art.

[0006] An electric motor and an angle sensor are known from DE 10 2019 002 745 A1.

[0007] The invention is therefore based on the object of developing an electric motor with an angle sensor, in particular a hollow shaft encoder, whereby a highly precise but also easily removable connection of an angle sensor to an electric motor is provided.

[0008] According to the invention, the object is achieved in the electric motor according to the features specified in claim 1.

[0009] Important features of the invention in the electric motor with angle sensor, in particular hollow shaft encoder, are that a rotor shaft of the electric motor is connected to an attachment shaft, in particular is connected in a rotationally fixed manner, wherein the attachment shaft has a threaded region, a guide region, a cylindrical section providing a centering fit, a second non-circular section, a connecting region and a first non-circular section, wherein the rotor shaft has a stepped bore and the threaded region is screwed into an internal thread region of the rotor shaft, wherein a thread run-out region adjoins the internal thread region of the rotor shaft, in particular on the side of the internal thread region axially facing away from the guide region, wherein the guide region of the attachment shaft is received in the rotor shaft with play, in particular with a play fit,in particular wherein the cylindrical section effecting the centering fit has a larger outer diameter than the guide area.,

[0010] The advantage here is that the mounting shaft is screwed together, allowing actuation during screwing without transverse torque, since the first non-circular section is easily accessible with a tool in the absence of an angle sensor, allowing the mounting shaft to be screwed in without transverse force, i.e., with only central torque if possible. When inserting the mounting shaft, a guide area is provided for pre-centering, and as the mounting shaft is screwed further into the threaded hole, a centering fit is activated, and a stable, load-bearing connection is achieved through the threaded area. This means that the mounting shaft is aligned with the rotor shaft with high precision, i.e., as precisely as possible.

[0011] The second non-circular section allows for easy disassembly, as it can apply high torque, which can even destroy an additional adhesive bond. This is because the second non-circular section extends radially much further than the first non-circular section.

[0012] Thus, disassembling a fan that is attached to the rotor shaft is only possible if the mounting shaft is first removed. However, disassembling the mounting shaft is simple and therefore easy. The mounting shaft can then also not be reassembled, although this requires first removing the adhesive residue and applying fresh liquid adhesive to the threaded area and the guide area.

[0013] In an advantageous embodiment, the mounting shaft is connected to a hollow shaft of the angle sensor in a rotationally fixed manner. The advantage here is that the hollow shaft is plugged onto the mounting shaft. This enables a simple, force-locking clamp connection.

[0014] In an advantageous embodiment, a cavity is formed axially between the guide area and the internal thread area, in particular for receiving adhesive. This is advantageous because adhesive squeezed out of the guide area or the thread area when screwing in the mounting shaft can be absorbed.

[0015] In an advantageous embodiment, adhesive is arranged between the rotor shaft and the guide area, in particular, wherein adhesive escaping from the threaded area or guide area is located in an annular cavity that is bounded radially inward by the threaded area and radially outward by the stepped bore of the mounting shaft. This is advantageous because the connection of the mounting shaft can be designed to be as stable and resilient as possible.

[0016] In an advantageous embodiment, adhesive is arranged between the internal thread area and the threaded area, in particular with adhesive that has leaked from the threaded area being located in the thread runout area. This is advantageous because the connection of the mounting shaft can be designed to be as stable and resilient as possible.

[0017] In an advantageous embodiment, the guide area borders the cylindrical section that creates the centering fit. This is advantageous because, when inserting the mounting shaft, the guide section takes effect first, followed by the centering fit. In an advantageous embodiment, the second non-circular section is arranged axially between the cylindrical section that creates the centering fit and the connecting area. It is advantageous that the second non-circular section is arranged outside the stepped bore of the mounting shaft, but as close as possible to the adhesive connection.

[0018] In an advantageous embodiment, the hollow shaft of the angle sensor is connected to the mounting shaft in the connection area, particularly by force. This allows for a simple and highly precise centered connection of the hollow shaft of the angle sensor, with the angle sensor detecting the angular position of the hollow shaft relative to the housing of the angle sensor.

[0019] In an advantageous embodiment, an elastic ring, in particular an O-ring, is arranged between the rotor shaft and the second non-circular section, in particular wherein the elastic ring is arranged radially outside the cylindrical section that effects the centering fit, in particular wherein the elastic ring rests on a front side of the second non-circular section that is facing away from the connection region, in particular an axial front side, and / or on a front side of the rotor shaft that is facing the second non-circular section, in particular an axial front side, in particular wherein the ring axis of the elastic ring is aligned parallel to the axis of rotation of the rotor shaft. The advantage here is that axial shocks that are transmitted from the motor to the angle sensor are dampened by means of the elastic ring. The elastic ring can also be manufactured from a material such as Teflon, for example. It is important that as high a proportion of the shock energy as possible is absorbed.

[0020] In an advantageous embodiment, the first non-circular section borders on the connecting region, in particular on the side of the connecting region axially facing away from the second non-circular section. It is advantageous in this case that the first non-circular section forms the axial end region of the attachment shaft and thus a torque can be applied centrally, i.e. without transverse torque, in order to screw the attachment shaft into the rotor shaft. In an advantageous embodiment, a fan is placed on the rotor shaft and connected to the rotor shaft in a rotationally fixed manner, wherein the region covered by the fan in the axial direction overlaps or encompasses the region covered by the internal thread region and / or thread run-out region in the axial direction, in particular wherein fan blades are formed on the fan that are evenly spaced from one another in the circumferential direction. It is advantageous in this case that the fan can be removed when the attachment shaft is removed from the rotor shaft.

[0021] In an advantageous embodiment, the clear inner diameter of the fan or the outer diameter of the rotor shaft in the area covered by the fan in the radial direction is smaller than the largest outer diameter of the second non-circular section. This is advantageous because the fan can also be removed after removing the mounting shaft.

[0022] In an advantageous embodiment, the largest outer diameter of the second non-circular section is larger than the largest outer diameter of the connecting area and the largest outer diameter of the first non-circular section. This is advantageous in that a large torque can be applied, particularly for disassembling the mounting shaft.

[0023] In an advantageous embodiment, the first non-circular section is an external non-circular section, in particular an external hexagon section, or an internal non-circular section, in particular a hexagon socket section. This is advantageous because the torque can be introduced centrally, i.e., centrally, into the mounting shaft using a tool, particularly without transverse torque, especially when screwing the mounting shaft into the rotor shaft.

[0024] In an advantageous embodiment, the second non-circular section is an external non-circular section, in particular an external hexagon section. This is advantageous because a simple tool can be used.

[0025] In an advantageous embodiment, the first non-circular section is formed on a screw, which is screwed into a threaded hole, in particular an axial hole, of the mounting shaft, in particular with a washer or a perforated disk arranged between the screw head of the screw and the mounting shaft. Advantageously, the non-circular section can be provided by means of a screw. Thus, only an axially directed threaded hole needs to be created in the mounting shaft, and then the screw is screwed in.

[0026] In an advantageous embodiment, the guide area is formed as the outer surface of a circular cylinder. This allows for simple and cost-effective production.

[0027] In an advantageous embodiment, instead of the guide region and the cylindrical region providing the centering fit, a conically shaped region is formed on the mounting shaft, which is arranged axially between the threaded region of the mounting shaft and the second non-circular section, in particular wherein the outer diameter of the conical region increases monotonically, in particular strictly monotonically, with decreasing distance from the second non-circular section. This is advantageous in that very precise centering of the mounting shaft relative to the rotor shaft is enabled.

[0028] In an advantageous embodiment, the hollow shaft of the angle sensor is non-positively connected to the connecting area of ​​the mounting shaft, wherein a seal, in particular a sealing ring, such as an O-ring, is arranged between the hollow shaft and the second non-circular section, which seals the hollow shaft towards the second non-circular section, in particular wherein the seal is arranged radially outside the connecting area, in particular therefore the radial distance area related to the axis of rotation of the rotor shaft and covered by the seal is spaced from the radial distance area related to the axis of rotation of the shaft and covered by the connecting area, in particular wherein the seal rests against a finely machined end face of the mounting shaft, in particular wherein the end face is flat and the normal of the end face is aligned parallel to the axis of rotation of the rotor shaft,In particular, the housing of the angle sensor is connected to a housing part, in particular the fan cover, of the electric motor by means of a torque support. A shaft seal is accommodated in the housing of the angle sensor, which seals against the hollow shaft, in particular, a sealing lip of the shaft seal rests against the radial outer circumference of the hollow shaft. It is advantageous that the interior of the angle sensor can be sealed from the environment.

[0029] Further advantages emerge from the dependent claims. The invention is not limited to the combination of features in the claims. Further possible combinations of claims and / or individual claim features and / or features of the description and / or the figures will become apparent to those skilled in the art, particularly from the problem and / or the problem posed by comparison with the prior art.

[0030] The invention will now be explained in more detail using schematic illustrations:

[0031] In Figure 1, an attachment shaft 11 connected to a rotor shaft 8 for connecting the rotor shaft 8 of a first electric motor according to the invention to an angle sensor is shown in section.

[0032] In Figure 2, the mounting shaft 11 of a second electric motor according to the invention is shown in an exploded oblique view, wherein, in contrast to the embodiment according to Figure 1, the mounting shaft 11 has a conical instead of a cylindrical shaft section and a screw 20 can be screwed into the axial end of the mounting shaft 11.

[0033] Figure 3 shows a sectional view of the rotor shaft 8 with the mounting shaft 11 screwed in.

[0034] Figure 4 shows a sectional view of the attachment of the angle sensor to the first electric motor.

[0035] As shown in Figure 1, the first electric motor has a rotor shaft 8 into which an attachment shaft 11 is screwed to enable the attachment of an angle sensor, in particular a hollow shaft encoder.

[0036] At its axial end region facing the angle sensor, in particular at its axial end face, the rotor shaft has a stepped bore. The mounting shaft 11 has a threaded region 6, adjacent to which a cylindrical guide region 4 is located. On the side of the cylindrical guide region 4 axially facing away from the threaded region 6, a further cylindrical section of the mounting shaft 11 adjoins the threaded region 6, acting as a centering fit 3.

[0037] Before being connected to the rotor shaft 8, the threaded portion 6 and the cylindrical guide portion 4 are coated with adhesive 9, which can exit into a cavity 5 or into a threaded runout 7 axially adjacent to the threaded portion 6 of the mounting shaft 11. The stepped bore of the rotor shaft 8 has the threaded runout 7 as its innermost stepped section, which is arranged axially next to an internal thread into which the threaded portion 6 of the mounting shaft 11 is screwed.

[0038] Axially adjacent to the internal thread is a further stepped section of the stepped bore, which accommodates the guide area 4 of the mounting shaft 11 with a certain amount of play, in particular with a clearance fit. The further stepped section projects beyond the guide area 4 in the axial direction, forming the cavity 5 into which the adhesive 9 can enter.

[0039] The further cylindrical section of the mounting shaft 11 has a larger diameter than the guide area 4 and is thus inserted without play, in particular as a centering fit, into the further step section of the step bore of the rotor shaft 8.

[0040] In this way, when inserting the mounting shaft 11 into the rotor shaft 8, guidance is initially achieved by the guide area 4 and, when further screwing in the mounting shaft 11, precise centering is achieved by means of the further cylindrical section of the mounting shaft 11 acting as a centering fit 3.

[0041] For attaching a tool, the mounting shaft 11 has a first non-circular section 10 at its axial end region facing away from the rotor shaft 8, so that the screwing torque of a tool can be applied centrally with little or no transverse force.

[0042] The first non-circular section 10 can be designed as an external hexagon area, as shown in Figure 1, or as an internal hexagon area.

[0043] A second non-circular section 2, particularly a wrench size, is formed on the mounting shaft 11 axially between the area 3 acting as a centering fit and the connecting area 1. Thus, an additional tool can be inserted into this second non-circular section 2 to enable disassembly of the mounting shaft 11 with such a high torque that the integral connection is severed. The mounting shaft 11 can also be referred to as an adapter shaft.

[0044] The largest outer diameter of the second non-circular section 2 exceeds the largest outer diameters of the areas of the mounting shaft 11 accommodated in the rotor shaft 8.

[0045] The inner ring of a rolling bearing is mounted on the rotor shaft 8, the outer ring of which is accommodated in a bearing flange. A fan can be mounted axially between this bearing and the second non-circular section and connected to the rotor shaft in a rotationally fixed manner, in particular by means of a keyway. The largest outer diameter of the second non-circular section 2 may even be larger than the smallest diameter of the fan, in particular, the clear inner diameter of the fan.

[0046] Replacing the fan is made easy by simply dismantling the mounting shaft 11.

[0047] As shown in Figures 2 and 3, instead of the first non-circular section 10, a screw 20 can be screwed into a threaded bore of the adapter shaft 11, the screw head of which has an external hexagon area and / or an internal hexagon area. An intermediate perforated disc 21 protects the end face of the mounting shaft 11 facing the screw head of the screw 20. In particular, the perforated disc 21 is arranged between the screw head of the screw 20 and the end face of the mounting shaft 11 facing the screw head of the screw 20.

[0048] In addition, according to the embodiment according to Figures 2 to 4, instead of the cylindrical guide area 4 and instead of the area acting as a centering fit 3, a conical connecting area 23 is formed on the mounting shaft 11.

[0049] The stepped bore has a corresponding inner cone as a further step section.

[0050] This results in improved guidance and centering. As shown in Figure 4, a fan 40 is mounted on the rotor shaft 8. The fan is connected to the rotor shaft 8 in a rotationally fixed manner and has fan blades. The air flow generated by the fan is deflected by a fan shroud 45, which is connected to the motor housing of the electric motor, so that the air flow flows along the motor housing.

[0051] The largest outer diameter of the second non-circular section 2 is larger than the clear inner diameter of the fan 40.

[0052] The rotor shaft 8 is rotatably mounted via the bearing 41 accommodated in the bearing plate 42.

[0053] The mounting shaft 11 can be removed by means of a tool that is applied to the second non-circular section 2, so that after the mounting shaft 11 has been removed, the fan cover can also be removed and the fan 40 can be replaced.

[0054] Without dismantling the mounting shaft 11, the fan 40 cannot be dismantled because the clear inner diameter of the fan 40 is smaller than the largest outer diameter of the second non-circular section 2.

[0055] A hollow shaft of the angle sensor is pushed onto the connecting area 1 of the mounting shaft 11 and is connected to it in a rotationally fixed manner.

[0056] Since the second non-circular section 2 protrudes radially beyond the connecting region 1, the hollow shaft can be tightly connected to the second non-circular section 2 by means of a seal, in particular a sealing ring such as an O-ring, and thus the interior of the angle sensor, in particular hollow shaft encoder, is sealed from the environment, since a shaft sealing ring accommodated in the housing of the angle sensor comprising the housing part 43 seals the housing towards the hollow shaft 46.

[0057] The hollow shaft 46 is arranged in the angle sensor so that it can rotate relative to the housing part 43

[0058] The seal 44 is arranged radially outside the connection area 1, in particular with respect to the axis of rotation of the rotor shaft 8. The housing of the angle sensor is connected to the fan cover 45 by means of a torque support not shown in the figures.

[0059] In further embodiments according to the invention, instead of the external hexagon area or internal hexagon area in the first non-circular section 10 and / or second non-circular section 2, a polygonal area can also be used.

[0060] List of reference symbols

[0061] 1 connection area

[0062] 2 second non-circular section, especially wrench size

[0063] 3 Centering fit

[0064] 4 cylindrical guide area

[0065] 5 Cavity

[0066] 6 Thread range

[0067] 7 Thread runout

[0068] 8 Rotor shaft

[0069] 9 Adhesive

[0070] 10 first non-circular section, especially hexagon

[0071] 11 Mounting shaft

[0072] 20 screw

[0073] 21 hole disc

[0074] 22 hexagon socket

[0075] 23 Connection area

[0076] 40 fans

[0077] 41 warehouses

[0078] 42 Bearing shield

[0079] 43 Housing of the angle sensor, especially hollow shaft encoder

[0080] 44 Seal

[0081] 45 Fan cover

[0082] 46 hollow shaft

Claims

Patent claims: 1.Electric motor with angle sensor, in particular a hollow shaft encoder, wherein a rotor shaft of the electric motor is connected to an attachment shaft, in particular is connected in a rotationally fixed manner, characterized in that the attachment shaft has a threaded region, a guide region, a cylindrical section bringing about a centering fit (3), a second non-circular section, a connecting region and a first non-circular section, wherein the rotor shaft has a stepped bore and the threaded region is screwed into an internal thread region of the rotor shaft, wherein a thread run-out region adjoins the internal thread region of the rotor shaft, in particular on the side of the internal thread region axially facing away from the guide region, wherein the guide region of the attachment shaft is received in the rotor shaft with play, in particular with a play fit, in particular wherein the cylindrical section bringing about the centering fit 3 has a larger external diameter than the guide region.

2. Electric motor according to claim 1, characterized in that the mounting shaft is connected to a hollow shaft of the angle sensor.

3. Electric motor according to one of the preceding claims, characterized in that a cavity is formed axially between the guide region and the internal thread region, in particular for receiving adhesive.

4. Electric motor according to one of the preceding claims, characterized in that adhesive is arranged between the rotor shaft and the guide area, in particular wherein adhesive which has escaped in particular from the threaded area or guide area is located in an annular cavity which is delimited radially inwardly by the threaded area and radially outwardly by the stepped bore of the mounting shaft.

5. Electric motor according to one of the preceding claims, characterized in that adhesive is arranged between the internal thread region and the thread region, in particular wherein adhesive which has escaped from the thread region is located in the thread run-out region.

6. Electric motor according to one of the preceding claims, characterized in that the guide region adjoins the cylindrical section which effects the centering fit.

7. Electric motor according to one of the preceding claims, characterized in that the second non-circular section is arranged axially between the cylindrical section providing the centering fit and the connecting region.

8. Electric motor according to one of the preceding claims, characterized in that the hollow shaft of the angle sensor is connected to the mounting shaft in the connection area, in particular in a force-fitting manner, and / or that an elastic ring, in particular an O-ring, is arranged between the rotor shaft and the second non-circular section, in particular wherein the elastic ring is arranged radially outside the cylindrical section which effects the centering fit, in particular wherein the elastic ring bears against an end face of the second non-circular section which is facing away from the connection area, in particular an axial end face, and / or against an end face of the rotor shaft which is facing the second non-circular section, in particular an axial end face, in particular wherein the ring axis of the elastic ring is aligned parallel to the axis of rotation of the rotor shaft.

9. Electric motor according to one of the preceding claims, characterized in that the first non-circular section adjoins the connecting region, in particular on the side of the connecting region axially remote from the second non-circular section.

10. Electric motor according to one of the preceding claims, characterized in that a fan is mounted on the rotor shaft and connected to the rotor shaft in a rotationally fixed manner, wherein the region covered by the fan in the axial direction overlaps or encompasses the region covered by the internal thread region and / or thread runout region in the axial direction. In particular, fan blades are formed on the fan that are evenly spaced from one another in the circumferential direction.

11. Electric motor according to one of the preceding claims, characterized in that the clear inner diameter of the fan or the outer diameter of the rotor shaft in the region covered by the fan in the radial direction is smaller than the largest outer diameter of the second non-circular section, and / or that the largest outer diameter of the second non-circular section is larger than the largest outer diameter of the connecting region and than the largest outer diameter of the first non-circular section.

12. Electric motor according to one of the preceding claims, characterized in that the first non-circular section is an external non-circular section, in particular an external hexagon section, or an internal non-circular section, in particular an internal hexagon section, and / or that the second non-circular section is an external non-circular section, in particular an external hexagon section.

13. Electric motor according to one of the preceding claims, characterized in that the first non-circular section is formed on a screw which is screwed into a threaded bore, in particular an axial bore, of the mounting shaft, in particular wherein a washer or a perforated washer is arranged between the screw head of the screw and the mounting shaft.

14. Electric motor according to one of the preceding claims, characterized in that the guide area is designed as a jacket surface of a circular cylinder or that instead of the guide area and the cylindrical area effecting the centering fit, a conically shaped area is formed on the mounting shaft, which is arranged axially between the threaded area of ​​the mounting shaft and the second non-circular section, in particular wherein the outer diameter of the conical area decreases with decreasing Distance to the second non-circular section increases monotonically, in particular strictly monotonically.

15. Electric motor according to one of the preceding claims, characterized in that the hollow shaft of the angle sensor is non-positively connected to the connecting area of ​​the mounting shaft, wherein a seal, in particular a sealing ring, such as an O-ring, is arranged between the hollow shaft and the second non-circular section, which seals the hollow shaft towards the second non-circular section, in particular wherein the seal is arranged radially outside the connecting area, in particular thus the radial distance area related to the axis of rotation of the rotor shaft and covered by the seal is spaced from the radial distance area related to the axis of rotation of the shaft and covered by the connecting area, in particular wherein the seal rests against a finely machined end face of the mounting shaft, in particular wherein the end face is flat and the normal of the end face is aligned parallel to the axis of rotation of the rotor shaft,in particular, wherein the housing of the angle sensor is connected to a housing part, in particular a fan cover, of the electric motor by means of a torque support, wherein a shaft sealing ring is accommodated in the housing of the angle sensor, which seals against the hollow shaft, in particular wherein a sealing lip of the shaft sealing ring rests on the radial outer circumference of the hollow shaft.

Images