Pressure generators for drive mechanisms and brake devices

Abstract

The invention relates to a drive mechanism (2) comprising an electric machine (4) arranged in a housing (3), the rotor (13) of which is arranged non-rotatably relative to a drive shaft (9) rotatably supported in the housing (3), and a sensor unit (23) designed for detecting the rotational position of the rotor (13), the sensor unit (23) having a printed circuit board (24) with at least one sensor element, the printed circuit board (24) being designed in the shape of a ring disk and arranged coaxially with respect to the rotation axis (10) of the drive shaft (9). It is provided that the printed circuit board (24) is arranged in the housing (3) and that the drive mechanism (2) comprises a shielding plate (37) which at least partially radially surrounds the printed circuit board (24).

Description

[Technical Field]

[0001] The present invention relates to a drive mechanism comprising an electric machine arranged in a housing, the rotor of which is arranged non-rotatably relative to a drive shaft which is rotatably supported in the housing, and a sensor unit formed for detecting the rotational position of the rotor, the sensor unit having a printed circuit board with at least one sensor element, the printed circuit board having a ring-disk shape and arranged coaxially with respect to the rotation axis of the drive shaft.

[0002] Furthermore, the invention relates to a pressure generator for a braking system equipped with such a drive mechanism. [Background technology]

[0003] Drives of the type mentioned above are known from the prior art. In drives equipped with an electric machine, the electric machine is typically arranged in a housing of the drive. The rotor of the electric machine is typically arranged non-rotatably on a drive shaft rotatably supported in the housing. By arranging the rotor on the drive shaft, the drive shaft can be driven or rotated by the electric machine. Rotation of the drive shaft can also operate a work machine operatively connected to the drive shaft, such as a pump mechanism. It is known to detect the rotational position of the rotor using a sensor unit having a printed circuit board with at least one sensor element. In this case, a printed circuit board shaped like a ring disk and arranged coaxially with the rotation axis of the drive shaft is often used. This type of configuration or arrangement of the printed circuit board allows for space-saving integration of the printed circuit board within the drive. The sensor unit is, for example, an inductive sensor, whereby the sensor element includes at least one receiving coil formed on the printed circuit board. Summary of the Invention

[0004] The drive mechanism according to the present invention is characterized in that a printed circuit board is disposed within a housing and that the drive mechanism includes a shielding plate that at least partially radially surrounds the printed circuit board. The arrangement of the printed circuit board within the housing makes the drive mechanism particularly compact. However, due to its location within the housing, the printed circuit board is spatially close to conductive lines extending through the interior of the housing. These conductive lines may disrupt the function of the sensor unit due to capacitive effects during operation of the drive mechanism. Typically, the sensor unit includes at least one electronic component, such as an application-specific integrated circuit (ASIC), disposed on the printed circuit board. Such electronic components are particularly susceptible to interference due to capacitive effects. The shielding plate according to the present invention shields the printed circuit board and elements disposed or formed on it, thereby at least reducing interference due to capacitive effects. Preferably, the shielding plate is made of a plastic material. This achieves particularly effective shielding of the printed circuit board. Since the printed circuit board is arranged in the housing, at least one portion of the shielding plate, which radially surrounds the printed circuit board, is also arranged in the housing. Preferably, the printed circuit board is axially opposite the rotor or a measurement transmitter that is non-rotatably connected to the rotor. With such a measurement transmitter, the sensor unit is preferably configured to detect the rotational position of the rotor by detecting the rotational position of the measurement transmitter. When the terms "axial" and "radial" are used within the scope of this disclosure, these terms relate to the rotational axis of the drive shaft, unless otherwise expressly disclosed. Preferably, the shielding plate is located radially spaced from the printed circuit board.

[0005] According to an advantageous embodiment, it is provided that the shielding plate surrounds the printed circuit board in the radial direction all around, i.e. the extension of the shielding plate is closed in the circumferential direction, and with this type of configuration of the shielding plate, particularly effective shielding of the printed circuit board is achieved.

[0006] According to an advantageous embodiment, it is provided that the shielding plate is fixed to the housing. This is advantageous in terms of stable fixing of the shielding plate. Preferably, the shielding plate is fixed directly to the housing. This has the advantage that an electrically conductive connection is formed between the shielding plate and the metal housing, so that the shielding plate can be connected to an electrical ground connection using the housing. Particularly preferably, the shielding plate is fixed to the housing by a form-locking connection. According to an alternative embodiment, the shielding plate is fixed to a rotatably supported element of the drive mechanism, for example, to the rotor or drive shaft.

[0007] According to an advantageous embodiment, it is provided that the shielding plate has at least one bendable connection and is fixed to the housing by means of the bendable connection. The bendable connection allows a form-locking connection to be technically easily produced. For this purpose, a housing part of the housing may have, for example, a break, in which case the bendable connection is guided through the breakable connection and engages with the housing part for form-locking the shielding plate. Instead of fastening using at least one bendable connection, the shielding plate may also be fastened to the housing in other ways and manners. According to a further embodiment, the shielding plate is fastened to the housing by, for example, caulking.

[0008] Preferably, the shielding plate is fixed to a bearing shield of the housing. The bearing shield is a housing cover of the housing that rotatably supports the drive shaft. Typically, the bearing shield carries a rotary bearing for supporting the drive shaft. Preferably, the printed circuit board is arranged between the bearing shield on the one hand and the rotor or the measurement transmitter on the other hand.

[0009] Preferably, the electric machine has a stator with, in particular, multi-phase motor windings, where the motor windings are electrically connected or can be electrically connected to an electric energy store by at least one electrically conductive motor phase supply conductor, and the shielding plate is arranged radially between the printed circuit board on the one hand and the at least one motor phase supply conductor on the other hand. During operation of the drive mechanism, a high voltage gradient is typically applied to the motor phase supply conductor, which can cause significant interference with the sensor unit, primarily due to capacitive effects. In this respect, arranging the shielding plate radially between the printed circuit board on the one hand and the motor phase supply conductor on the other hand is particularly advantageous for effective shielding of the printed circuit board. Preferably, the drive mechanism has a wiring plate fixedly arranged on the housing, where the wiring plate radially surrounds the wiring plate and the motor phase supply conductor extends through the wiring plate.

[0010] According to an advantageous embodiment, it is provided that the drive mechanism has a carrier element fixed to the housing and carrying the printed circuit board, and that the carrier element has the shielding plate, i.e., the shielding plate is part of the carrier element. In any case, the carrier element is typically provided to fasten the printed circuit board to the housing. In other words, by incorporating the shielding plate into the carrier element, the total number of parts provided does not increase.

[0011] According to an advantageous embodiment, the carrier element has a base body made of plastic, and the shielding plate is electrically separated from the printed circuit board by the base body. This prevents an electrical short circuit between the shielding plate, on the one hand, and the conductive paths formed on the printed circuit board, on the other hand. Preferably, the printed circuit board is fixed to the base body, so that the base body of the carrier element supports the printed circuit board. Preferably, at least one portion of the shielding plate extends through the base body made of plastic.

[0012] Preferably, the carrier element is fixed to the housing by a shielding plate, which is particularly suitable for this purpose due to its mechanical robustness, and in addition, contact between the housing and the shielding plate is desirable anyway in order to form a conductive connection between the shielding plate and the housing.

[0013] According to an advantageous embodiment, it is provided that the shielding plate has a first portion extending at least substantially in the axial direction and a second portion extending at least substantially in the radial direction, the first portion at least partially surrounding the printed circuit board in the radial direction and the second portion at least partially covering the printed circuit board, in this way the printed circuit board is not only shielded in the radial direction but also in the axial direction, i.e. shielded by the second portion at least partially covering the printed circuit board.

[0014] The pressure generator for a braking system according to the invention comprises a pump mechanism, a drive mechanism for operating the pump mechanism, and a control device for controlling the drive mechanism. This pressure generator is characterized by the features of the drive mechanism according to the invention as defined in claim 11. This also results in the advantages already mentioned. Further advantageous features and combinations of features are evident from the above description and the claims.

[0015] According to an advantageous embodiment, it is provided that the shielding plate is electrically coupled to an electrical ground connection of the control device, so that the shielding plate can suppress capacitive effects that occur when the drive mechanism is operated. Preferably, the electrical coupling between the shielding plate and the ground connection is provided at least proportionally by the housing of the drive mechanism and the housing of the pump mechanism.

[0016] Next, the present invention will be described in more detail with reference to the drawings. [Brief explanation of the drawings]

[0017] [Figure 1] 1 is a simplified diagram of a pressure generator for a braking system. [Figure 2] FIG. 2 is a cross-sectional view of a drive mechanism of a pressure generator. [Figure 3] FIG. 10 is another cross-sectional view of the drive mechanism. DETAILED DESCRIPTION OF THE INVENTION

[0018] FIG. 1 is a simplified diagram of a pressure generator 1 for a hydraulic brake system of a motor vehicle. The pressure generator 1 includes an electric drive mechanism 2. The drive mechanism 2 includes a housing 3, which in this embodiment has a circular cross section. The drive mechanism 2 further includes an electric machine 4. The electric machine 4 is disposed within the housing 3 and is therefore not visible in FIG. 1 . The pressure generator 1 includes a pump mechanism 5 as a working machine, which includes at least one fluid pump. The housing 3 of the drive mechanism 2 is fixed to a housing 7 of the pump mechanism 5 by means of a number of fixing means 6. The drive mechanism 2 is configured to operate at least one fluid pump of the pump mechanism 5 using the electric machine 4. The pressure generator 1 further includes a control device 8 for controlling the electric machine 4. The pump mechanism 5 is disposed between the drive mechanism 2 on the one hand and the control device 8 on the other hand.

[0019] Figure 2 is a cross-sectional view of the drive mechanism 2. As can be seen from Figure 2, the drive mechanism 2 has a drive shaft 9 that is rotatably supported about a rotation axis 10 in the housing 3. The drive shaft 9 is operatively connected to at least one fluid pump of the pump mechanism 5 by means of a transmission 11. In Figure 2, only a spur gear 12 of the transmission 11 is shown, which is arranged non-rotatably relative to the drive shaft 9. However, the transmission 11 is preferably configured as a planetary gear mechanism.

[0020] The electric machine 4 comprises a rotor 13 arranged non-rotatably relative to the drive shaft 9, and a stator 14 arranged fixedly in the housing. The stator 14 has polyphase motor windings, not shown for clarity, distributed around the rotor 13 such that the rotor 13, and hence the drive shaft 9, can be rotated or driven by appropriate energization of the motor windings.

[0021] The housing 3 has a pole pot 15 that carries the stator 14. The pole pot 15 is made of a metal material. As can be seen in FIG. 1, the pole pot 15 is formed like glass. In this respect, the pole pot 15 has a bottom 16 and a sleeve portion 17. The bottom 16 extends at least substantially radially. The sleeve portion 17 extends from the bottom 16 at least substantially axially.

[0022] The housing 3 further comprises a bearing shield 18, which covers the electric machine 4 and thus forms a housing cover for the housing 3. The bearing shield 18 is made of a metallic material and is formed by deep drawing in the present embodiment. The bearing shield 18 is configured to support the drive shaft 9. For this purpose, the bearing shield 18 comprises an axially extending sleeve-shaped support part 19. Between the support part 19 and the drive shaft 9, a rotary bearing 20 is arranged, which in the present embodiment is a rolling element bearing 20.

[0023] The bearing shield 18 further comprises a radially extending ring-disc shaped housing part 21 which in this embodiment is directly connected to the support part 19.

[0024] The bearing shield 18 further has an axially extending sleeve-shaped fixing part 22. A radially outwardly directed side surface 43 of the fixing part 22 abuts radially inwardly directed side surface 45 of the pole pot 15. In this embodiment, the bearing shield 18 is press-fit into the pole pot 15 so that a frictional connection is formed between the fixing part 22 and the pole pot 15. However, the bearing shield 18 may also be fixed to the pole pot 15 in other ways, for example by adhesive bonding, welding or by at least one other fixing means.

[0025] The drive mechanism 2 further includes a sensor unit 23 configured to detect the rotational position of the rotor 13. The sensor unit 23 has a ring-disk-shaped printed circuit board 24 arranged in the housing 3. The printed circuit board 24 is arranged coaxially with the rotation axis 10 of the drive shaft 9, so that it radially surrounds the drive shaft 9. In this embodiment, the printed circuit board 24 is arranged between the housing part 21 of the bearing shield 18 on the one hand and the rotor 13 on the other hand. The printed circuit board 24 has a first end face 25 facing the rotor 13 and a second end face 26 facing the housing part 21. A sensor element of the sensor unit 23 is arranged or formed on the first end face 25. In this embodiment, the sensor unit 23 is configured as an inductive sensor 23. For this purpose, the sensor element has at least one transmitter coil and at least one receiver coil, the transmitter coil and the receiver coil being formed on the printed circuit board 23 as conductive paths. An electronic component 27 of the sensor unit 23 is arranged on a second end surface 26 of the printed circuit board 24 facing the housing part 18. In this embodiment, the electronic component 27 is an application specific integrated circuit (ASIC). The electronic component 27 is configured to demodulate or process the sensor signal of the sensor element.

[0026] According to a further embodiment, the drive mechanism 2 has a measurement transmitter which is coupled non-rotatably to the rotor 13, and the printed circuit board 24 is arranged between the housing part 21 of the bearing shield 18 on the one hand and the measurement transmitter on the other hand. In this embodiment, the sensor unit 23 is then designed to detect the rotational position of the rotor 13 by detecting the rotational position of the measurement transmitter.

[0027] The drive mechanism 2 further includes a connection plate 28 fixedly arranged on the housing. The connection plate 28 is ring-shaped and radially surrounds the sensor unit 23. A plurality of electrically conductive motor phase supply conductors 29, 30, 31 extend through the connection plate 28. The motor phase supply conductors 29, 30, 31 are only briefly indicated in FIG. 2. If the pressure generator 1 shown in FIG. 1 were installed in a brake system, the phases of the motor winding of the stator 14 would be electrically coupled to an electrical energy store by the motor phase supply conductors 29, 30, 31.

[0028] The drive assembly 2 further comprises a carrying element 32 for fixing the printed circuit board 24 to the bearing shield 18. The construction of the carrying element 32 will be explained in more detail below with reference to Figure 3, which shows a cross-section of a portion of the drive mechanism 2 in the region of the carrying element 32.

[0029] The carrier element 32 has a base body 33 made of plastic. The printed circuit board 24 is fixed to the base body 33, for example, by a locking connection. The base body 33 is ring-shaped and arranged coaxially with respect to the rotational axis 10 of the drive shaft 9. The base body 33 has a first portion 34 that radially surrounds the printed circuit board 24. That is, the first portion 34 extends around the entire circumferential circumference of the printed circuit board 24. The base body 33 also has a second portion 35. The second portion 35 at least substantially covers the printed circuit board 24. Correspondingly, the second portion 35 is arranged between the printed circuit board 24, on the one hand, and the housing part 21 of the bearing shield 18, on the other hand. In the region of the second portion 35, the base body 33 has a material cutout 36 or hollow space 36 in which the electronic component 27 is arranged.

[0030] The carrier element 32 further comprises a shielding plate 37, which in this embodiment extends through the base body 33 and is form-lockingly connected to the base body 33. The shielding plate 37 is preferably made of a copper material. The base body 33 and the shielding plate 37 are formed in such a way that the shielding plate 37 is electrically decoupled from the printed circuit board 24 by the base body 33.

[0031] In this embodiment, the shielding plate 37 has an axially extending first portion 38 that radially surrounds the printed circuit board 24. Correspondingly, the first portion 38 is sleeve-shaped. In this case, the first portion 38 of the shielding plate 38 is radially arranged between the printed circuit board 24 on the one hand and the connection plate 28 or the motor phase supply conductors 29, 30, 31 on the other hand.

[0032] In this embodiment, the shielding plate 37 further has a radially extending second portion 39. The second portion 39 is formed in the shape of a ring disk and extends radially inward starting from the first portion 38. In this case, the second portion 39 partially covers the printed circuit board 24, so that the second portion 39 partially faces the printed circuit board 24 in the axial direction.

[0033] In this embodiment, the shielding plate 37 further has an axially extending third section 40, which projects from the basic body 33. The third section 40 has a free end 41 provided with two flexural connections 42, which are guided through axial breaks 43 in the housing part 21 of the bearing shield 18 and engage therein, thereby fixing the carrier element 32 to the bearing shield 18 by means of a form-locking connection 44. As can be seen from FIG. 2, in addition to the third section 40 shown in FIG. 3, several further third sections 40, each with two flexural connections 42, are provided, which are distributed around the circumferential direction of the shielding plate 37. By way of example only, the housing part 21 has six axial breaks 43, and in this case the shielding plate 37 has six third parts 40, each with two bent connections 42, and each of the axial breaks 43 is guided through by a bent connection 42 of one of the other third parts 40.

[0034] If the drive mechanism 2 is part of the pressure generator 1 as shown in Figure 1, the shielding plate 37 is electrically connected to the earth connection of the control device 8. This electrical connection is then provided, at least proportionally, by the bearing shield 18, the pole pot 15, the fixing means 6 and the housing 7 of the pump mechanism 5.

[0035] The shielding plate 37 shields the sensor unit 23 and in particular the electronics 27 from the motor phase supply conductors 29, 30, 31. Correspondingly, it is prevented that the motor phase supply conductors 29, 30, 31 interfere with the function of the sensor unit 23 due to capacitive effects in the region of the drive mechanism 2. [Explanation of symbols]

[0036] 1 pressure generator 2. Drive mechanism 3 Drive mechanism housing 4 Electrical Machinery 5. Pump mechanism 8 Control Devices 9 Drive shaft 10. Rotation axis of drive shaft 13 Rotors of electrical machines 14 Stator of an electric machine 18 Bearing Shield 23 Sensor unit 24 Printed Circuit Board 29, 30, 31 Motor phase supply wires 32 Carrying element 33 Base body of the supporting element 37 Shielding plate 38 First part of shielding plate 39 Second part of the shielding plate 42 Bent joint of shielding plate

Claims

1. a drive mechanism comprising: an electric machine (4) arranged in a housing (3), the electric machine (4) having a rotor (13) arranged non-rotatably relative to a drive shaft (9) rotatably supported in the housing (3); and a sensor unit (23) configured to detect the rotational position of the rotor (13), the sensor unit (23) having a printed circuit board (24) with at least one sensor element, the printed circuit board (24) having a ring-disc shape and arranged coaxially with respect to a rotation axis (10) of the drive shaft (9), wherein the printed circuit board (24) is arranged in the housing (3); and the drive mechanism (2) has a shielding plate (37) radially surrounding the printed circuit board (24) at least partially; the drive mechanism (3) has a carrying element (32) fixed to the housing (3) and carrying the printed circuit board (24), the carrying element (32) having the shielding plate (37); A drive mechanism characterized in that the carrying element (32) is fixed to the housing (3) by the shielding plate (37).

2. 2. The drive mechanism according to claim 1, wherein the shielding plate (37) surrounds the printed circuit board (24) over the entire circumference in the radial direction.

3. 3. A drive mechanism according to claim 1 or 2, characterized in that the shielding plate (37) is fixed to the housing (3), in particular by a form-locking connection.

4. 4. The drive mechanism according to claim 3, characterized in that the shielding plate (37) has at least one flexural connection (42) and is fixed to the housing (3) by means of the flexural connection (42).

5. 4. A drive mechanism according to claim 3, characterized in that the shielding plate (37) is fixed to a bearing shield (18) of the housing (3).

6. 3. A drive mechanism according to claim 1, wherein the electric machine (4) has a stator (14) with, in particular, multi-phase motor windings, the motor windings being electrically connected or electrically connectable to an electric energy store by at least one electrically conductive motor phase supply conductor (29, 30, 31), and the shielding plate (37) is arranged radially between the printed circuit board (24) on the one hand and the motor phase supply conductor (29, 30, 31) on the other hand.

7. A drive mechanism as described in claim 1, characterized in that the support element (32) has a base body (33) made of plastic, and the shielding plate (37) is electrically isolated from the printed circuit board (24) by the base body (33).

8. A drive mechanism as described in claim 1 or 2, characterized in that the shielding plate (37) has a first part (38) extending at least substantially in the axial direction and a second part (39) extending at least substantially in the radial direction, the first part (38) at least partially surrounding the printed circuit board (24) in the radial direction, and the second part (39) at least partially covering the printed circuit board (24).

9. A pressure generator for a brake device comprising a pump mechanism (5), a drive mechanism (2) for operating the pump mechanism (5), and a control device (8) for controlling the drive mechanism (2), characterized in that the drive mechanism (2) is a drive mechanism (2) described in claim 1 or 2.

10. A pressure generator as described in claim 9, characterized in that the shielding plate (37) is electrically connected to the electrical earth connection of the control device (8).

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