Wiper motor

Abstract

The invention relates to a wiper motor (10; 10a) comprising a device (32) for detecting an angular rotation position of a shaft (28) connected at least indirectly to an electric motor (12), the device (32) having at least one magnetic element (18), and a sensor element (34; 34a) for detecting the at least one magnetic element (18), the sensor element (34; 34a) being disposed in the area of a circuit board (44; 44a).

Description

Wiper motorTechnical Field

[0001] The invention relates to a wiper motor comprising an electronically commutated electric motor characterized by a particularly simple and compact placement of a device for detecting an angular rotation position of a shaft connected to the electric motor.Background Art

[0002] JP 2008 160941 A discloses a wiper motor having the features of the preamble of claim 1 . The known direct-current motor, which comprises carbon brushes, has an annular magnet on a shaft, a Hall sensor disposed on a circuit board being configured to detect the angular rotation position of said annular magnet. The known device can be used to determine the angular rotation position of the shaft in order to be able draw a conclusion especially as to the position of wiper blades connected to the wiper motor. This is necessary in order to be able to reverse the polarity of the electric motor or reverse a direction of rotation of the electric motor at reversal points of the wiper blades on a vehicle window.Disclosure of the invention

[0003] The wiper motor according to the invention with the features of claim 1 has the advantage that the angular rotation position of the shaft can be detected without an additional annular magnet. As a result, the wiper motor, which comprises the electric motor and a gear mechanism connected to the shaft, can be of a particularly compact design in terms of its overall length. Moreover, the omission of an additional magnetic element (annular magnet) connected to the shaft allows a particularly cost-effective configuration.

[0004] The invention is based on the idea of detecting the angular rotation position of the shaft coupled to the electric motor by having a sensor element detect the magnetic elements disposed on a rotor of a brushless electric motor so as to conclude therefrom the angular rotation position of the shaft. Detecting the individual magnetic elements additionally makes it possible not only for the angular rotation position of the shaft to be detected but also for stator windings of the electric motor to be supplied with current or actuated in a timely manner to enable the electric motor to operate.

[0005] In light of the explanations above, a wiper motor having the features of claim 1 therefore comprises a device for detecting an angular rotation position of a shaft connected at least indirectly to an electric motor. The device comprises at least one magnetic element and a sensor element for detecting the at least one magnetic element, the sensor element being disposed in the area of a circuit board. According to the invention, the electric motor is an electronically commutated electric motor, and the shaft thereof is connected to a rotor having magnetic elements disposed parallel to an axis of rotation of the rotor at regular angular distances about the axis of rotation, the magnetic elements interacting with stator windings and being detectable by the sensor element.

[0006] Advantageous embodiments of the wiper motor according to the invention are presented in the dependent claims.

[0007] As initially explained, the detection of the individual magnetic elements or the angular rotation position of the shaft serves the purpose of supplying current to the stator windings at the correct points in time. Hence, it is provided for signals of the sensor element to be fed to an evaluation circuit configured to at least indirectly supply current to the stator windings of a stator radially surrounding the rotor as a function of the detected angular rotation position of the shaft.

[0008] In a particularly advantageous constructive layout, the sensor element is disposed opposite an end face of the rotor, the magnetic elements extending as far as to the end face of the rotor.

[0009] Furthermore, it is preferred for the sensor element to be disposed at a top or a bottom of the circuit board. This allows space-saving placement of the sensor element.

[0010] In particular, it is provided for the sensor element to be connected directly to the top or the bottom of the circuit board. A direct connection is understood to mean that the sensor element is connected to the circuit board merely via the connection serving as the electrical contact, in particular a soldered connection.

[0011] In an alternative constructive layout, the sensor element may be disposed to the side of the circuit board and be connected to a circuit of the circuit board via transmission elements. Especially in the case that the transmission elements are wire elements, this allows for a variable or arbitrary placement of the printedcircuit board relative to the sensor element in order to enable an overall optimized arrangement of components with regard to the other components of the wiper motor, for example.

[0012] Moreover, it is preferred for the sensor element to be a Hall sensor.

[0013] According to another preferred layout of the structural components, the sensor element, together with the circuit board, is disposed in the area of a gear housing, and the rotor is disposed in a motor housing connected to the gear housing.

[0014] Alternatively, however, the sensor element may protrude into a motor housing, or the electric motor, the circuit board, and the sensor element may be disposed in a shared housing.

[0015] Other advantages, features, and details of the invention are apparent from the following description of preferred embodiments of the invention and from the drawings.Brief Description of the Drawings

[0016] Fig. 1 and Fig. 2 each show a simplified view of the basic structure of a wiper motor according to the invention in the area relevant to the invention with its respective essential components.Embodiments of the Invention

[0017] Similar elements or elements having a similar function are designated by similar reference signs in the figures.

[0018] The wiper motor 10 illustrated in Fig. 1 serves to actuate or drive at least one wiper blade (not shown) connected to the wiper motor 10 via a mechanical mechanism, as is known from the prior art.

[0019] The wiper motor 10 has an electronically commutated electric motor 12, which is of an internal-rotor design and comprises a rotor 16 configured to rotate about a longitudinal axis 14. Moreover, in a manner known per se, the rotor 16 has magnetic elements 18 disposed at regular angular distances about the longitudinal axis 14. Viewed in the direction of the longitudinal axis 14, the rotor 16 is radially surrounded by a stator 20. As also known per se, the stator 20 has multiple stator windings 22, which can be supplied with current as needed asa function of the angular rotation position of the rotor 16 through a controller having an evaluation circuit.

[0020] The rotor 16 is connected to a rotor shaft 28 for co-rotation, the rotor shaft 28 having a toothed portion 30 which meshes with mating teeth of a spur wheel to enable a reduction of the speed of the electric motor 12. The toothed portion 30 is thus part of a gear mechanism of the wiper motor 10, the gear mechanism being connected to the wiper blades mentioned above.

[0021] Furthermore, the wiper motor 10 comprises a device 32 for detecting the angular rotation position of the rotor shaft 28. The device 32 comprises at least one sensor element 34, in particular a Hall sensor 36, which serves to detect the magnetic fields of the magnetic elements 18 as the rotor 16 rotates about its longitudinal axis 14. To this end, the magnetic elements 18, which are disposed parallel to the longitudinal axis 14 on a pitch circle diameter, extend as far as to an end face 38 of the rotor 16, which faces the sensor element 34, so as to enable reliable detection of the magnetic fields of the magnetic elements 18 through a minimum distance to the sensor element 34. This is made possible by the fact that the sensor element 34 is disposed directly opposite the said end face 38.

[0022] In the case of the wiper motor 10 illustrated in Fig. 1 , the sensor element 34 is disposed at a top 40 or a bottom 42 of a circuit board 44. The connection between the sensor element 34 and the circuit board 44 is formed by a bonded connection in the form of a soldered connection; i.e. , the sensor element 34 is connected directly to the circuit board 44. Furthermore, the circuit board 44 also reaches right up to the end face 38 in the exemplary embodiment illustrated.

[0023] Whereas the rotor 16 and the stator 20 of the electric motor 12 are disposed inside a motor housing 46, the rotor shaft 28 protrudes into a gear housing 48. Moreover, the circuit board 44 with the sensor element 34 is also disposed in the area of the gear housing 48.

[0024] The wiper motor 10a illustrated in Fig. 2 essentially differs from wiper motor 10 in that the sensor element 34a is connected to the circuit board 44a in an electrically conductive manner via transmission elements 50, in particular wire elements or wire connections 52. Furthermore, the sensor element 34a protrudesinto the motor housing 46a, while the circuit board 44a is located in the gear housing 48a.

[0025] Additionally, it is noted that any kind of transmission elements 50 other than wire connections 52 may be provided, such as optical transmission elements 50 or the like.

[0026] In another embodiment (not shown), separate motor housings 46, 46a and gear housings 48, 48a may be dispensed with and a shared housing 55 may be used instead, as indicated by the dashed line in Fig. 2.

[0027] The signals of the sensor element 34 are transmitted to the evaluation circuit of the controller and serve the purpose of supplying current to the stator windings 22 as a function of the angular rotation position of the rotor shaft 28.

[0028] The wiper motor 10, 10a thus described can be altered or modified in various ways without departing from the spirit of the invention. For instance, it is conceivable for the electronically commutated electric motor 12 to be of an external-rotor design instead of an internal-rotor design.Reference signs

[0029] 10, 10a wiper motor

[0030] 12 electric motor

[0031] 14 longitudinal axis

[0032] 16 rotor

[0033] 18 magnetic element

[0034] 20 stator

[0035] 22 stator winding

[0036] 28 rotor shaft

[0037] 30 toothed portion

[0038] 32 device

[0039] 34, 34a sensor element

[0040] 36 Hall sensor

[0041] 38 end face

[0042] 40 top

[0043] 42 bottom

[0044] 44, 44a circuit board

[0045] 46, 46a motor housing

[0046] 48, 48a gear housing

[0047] 50 transmission element

[0048] 52 wire connection

[0049] 55 housing

Claims

Claims1 . A wiper motor (10; 10a) comprising: a device (32) for detecting an angular rotation position of a shaft (28) connected at least indirectly to an electric motor (12), the device (32) having at least one magnetic element (18), and a sensor element (34; 34a) for detecting the at least one magnetic element (18), the sensor element (34; 34a) being disposed in the area of a circuit board (44; 44a), characterized in that the electric motor (12) is an electronically commutated electric motor (12), and the shaft (28) is connected to a rotor (16) having magnetic elements (18) disposed parallel to an axis of rotation (14) of the rotor (16) at regular angular distances about the axis of rotation (14), the magnetic elements (18) interacting with stator windings (22) and being detectable by the sensor element (34; 34a).

2. The wiper motor according to claim 1 , characterized in that signals of the sensor element (34; 34a) are fed to an evaluation circuit configured to at least indirectly supply current to the stator windings (22) of a stator (20) radially surrounding the rotor (16) as a function of the detected angular rotation position of the shaft (28).

3. The wiper motor according to claim 1 or 2, characterized in that the sensor element (34; 34a) is disposed opposite an end face (38) of the rotor (16), the magnetic elements (18) extending as far as to the end face (38) of the rotor (16).

4. The wiper motor according to any one of claims 1 to 3, characterized in that the sensor element (34) is disposed at a top (40) or a bottom (42) of the circuit board (44).

5. The wiper motor according to claim 4, characterized in thatthe sensor element (34) is connected directly to the top (40) or the bottom (42) of the circuit board (44).

6. The wiper motor according to any one of claims 1 to 3, characterized in that the sensor element (34a) is disposed to the side of the circuit board (44a) and is connected to a circuit of the circuit board (44a) via transmission elements (50).

7. The wiper motor according to claim 6, characterized in that the transmission elements (50) are wire elements (52).

8. The wiper motor according to any one of claims 1 to 7, characterized in that the sensor element (34; 34a) is a Hall sensor (36).

9. The wiper motor according to any one of claims 1 to 8, characterized in that the sensor element (34), together with the circuit board (44), is disposed in the area of a gear housing (48), and the rotor (16) is disposed in a motor housing (46) connected to the gear housing (48).

10. The wiper motor according to any one of claims 1 to 8, characterized in that the sensor element (34a) protrudes into a motor housing (46a), or the electric motor (12), the circuit plate (44a), and the sensor element (34a) are disposed in a shared housing (55).

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