Pressure generators for drive mechanisms and brake devices

Abstract

The present invention relates to a drive mechanism (2) comprising an electric machine arranged in a housing (3), an end shield (9) associated with the machine, and at least one circuit board (19) arranged in the housing (3), the circuit board (19) being fixed to the end shield (9) by metallic fastening means (25). It is intended that the metallic fastening means (25) is electrically coupled to a ground connection (42) of the circuit board (19).

Description

[Technical Field]

[0001] The present invention relates to a drive mechanism comprising an electric machine arranged in a housing, an end shield attached to the machine, and at least one circuit board arranged in the housing, the circuit board being fixed to the end shield by a metallic fixing means.

[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 aforementioned type are known from the prior art. In the case of drives equipped with an electric machine, the electric machine is typically arranged in a housing of the drive. The machine typically has a rotatably supported rotor and a stator fixed to the housing, which is provided with, in particular, multi-phase motor windings. The motor windings are distributed around the rotor so that the rotor can rotate when the motor windings are appropriately energized. Furthermore, at least one end shield is typically provided attached to the machine. Preferably, the end shield covers the electric machine. Typically, the drive shaft of the drive is rotatably supported by the end shield. For this purpose, the end shield preferably carries a pivot bearing acting between the drive shaft on the one hand and the end shield on the other hand. A circuit board is often arranged in the housing of the drive. For example, the circuit board is part of a sensor mechanism configured to detect the rotational position of the rotor. It is known to fasten the circuit board to the end shield by metallic fastening means. Summary of the Invention

[0004] The drive mechanism according to the present invention is characterized in that the metallic fastening means is electrically coupled to the ground connection of the circuit board. The metallic fastening means is electrically conductive, so that the ground connection of the circuit board can be connected to the electrical system ground by the fastening means. Prior to this application, known drive mechanisms typically required separate conductive coupling means that were electrically coupled to the ground connection of the circuit board and electrically coupled or connectable to the system ground. The solution according to the present invention eliminates this separate coupling means. Correspondingly, the number of components in the drive mechanism can be reduced, thereby saving costs. Additionally, the metallic fastening means ensures a mechanically robust connection of the ground connection of the circuit board to the system ground. Preferably, the end shields are metallic or made of a metallic material.

[0005] According to a preferred embodiment, the metallic fastening means is in contact with the ground connection on the one hand and the metallic end shield on the other hand. That is, the metallic fastening means is electrically connected directly to the ground connection, and no additional components are used. This also achieves a low number of parts. In addition, the metallic fastening means is in contact with the metallic end shield, so that the ground connection of the circuit board is electrically connected to the metallic end shield by the metallic fastening means. This is therefore advantageous because it allows technically simple connection of the metallic end shield to the system ground. Preferably, the contact surface of the fastening means in contact with the ground connection has a galvanic coating, particularly preferably a tin, silver, or gold coating. Preferably, the contact surface of the fastening means in contact with the end shield has a galvanic coating, particularly preferably a tin, silver, or gold coating. Preferably, the contact surface of the end shield in contact with the fastening means has a galvanic coating, particularly preferably a tin, silver, or gold coating. The coating reduces the electrical contact resistance between the fastening means and the end shield or between the earth connection and the fastening means.

[0006] According to an advantageous embodiment, the ground connection is arranged on a side of the circuit board facing away from the end shield, and the fastening means biases the ground connection with a force acting in the direction of the end shield. Preferably, the fastening means biases the ground connection with a force acting in the direction of the end shield, thereby pressing the circuit board against the end shield. This, on the one hand, achieves a mechanically robust fixation of the circuit board to the end shield. In particular, tilting of the circuit board is prevented. In addition, a mechanically robust electrical connection between the fastening means and the ground connection is also provided. Preferably, the fastening means biases the end shield with a force acting in the direction of the circuit board or the ground connection. Preferably, the fastening means is elastically deformable and provides a force as an elastic force or a restoring force. For this purpose, the fastening means is made of, for example, steel.

[0007] According to a preferred embodiment, it is provided that the ground connection is a ground plane and that the fastening means abuts against the ground plane. If the ground connection is configured as a ground plane, manufacturing tolerances can be compensated for. In particular, even if the relative positioning of the circuit board with respect to the fastening means changes slightly, the fastening means is still electrically connected to the ground plane. Preferably, the fastening means abuts against the ground plane. Preferably, the ground plane is configured as a copper plane. Such a ground plane can be produced within the framework of a normal component mounting method for a circuit board and therefore can be realized without incurring additional costs. Preferably, the copper plane has a galvanic coating, particularly preferably a tin, silver, or gold coating.

[0008] Preferably, the fastening means is configured as a locking means, i.e., the fastening means is configured for fastening the circuit board to the end shield by forming at least one locking connection, which is advantageously relevant for assembling the drive mechanism, since the locking connection can be quickly manufactured by snapping together the corresponding components. Preferably, the fastening means is configured as a locking clamp.

[0009] According to an advantageous embodiment, the locking means has a first locking portion and a second locking portion, where the first locking portion projects through the first through-hole of the end shield and engages with the end shield from the rear to form the first locking connection, and the second locking portion projects through the second through-hole of the end shield and engages with the end shield from the rear to form the second locking connection. This allows for a particularly robust mechanical fixation of the circuit board to the end shield. Preferably, the first and / or second locking portions are configured to prevent release of the first or second locking connection by a force acting on them in the direction of the circuit board. For this purpose, for example, the first and / or second locking portions each have a notch that provides the locking connection.

[0010] According to an advantageous embodiment, the circuit board has a through-hole, and the first locking portion protrudes through the through-hole of the circuit board. That is, the first locking portion protrudes through both the through-hole of the circuit board and the first through-hole of the end shield. Preferably, the through-hole of the circuit board and the first through-hole of the end shield are aligned with each other. The through-hole allows the circuit board to be larger in size than a circuit board that extends only between the first and second locking portions.

[0011] Preferably, the drive mechanism includes a spacer plate made of an electrically insulating material and disposed between the circuit board and the end shield. The spacer plate electrically insulates the conductive tracks formed on the end shield side of the circuit board from the end shield. Preferably, the spacer plate has at least one alignment protrusion that engages with an alignment through-hole in the end shield to align the circuit board to the end shield. Preferably, the spacer plate has at least one alignment protrusion that engages with an alignment through-hole in the circuit board to align the circuit board to the spacer plate. Preferably, the spacer plate has a through-hole through which the first locking portion of the fixing element protrudes.

[0012] According to an advantageous embodiment, it is provided that the drive mechanism has a sensor mechanism configured to detect the rotational position of the rotor of the electric machine, and that the circuit board is part of the sensor mechanism. Preferably, the sensor mechanism has a further circuit board in addition to the circuit board, on which sensor elements of the sensor mechanism are formed. Correspondingly, the further circuit board is configured as a sensor circuit board. Preferably, the sensor circuit board is configured in the shape of a ring disk and is arranged coaxially with respect to the rotor. The circuit board preferably has a connection mechanism for communication technical coupling with a controller. In this respect, the circuit board is configured as a connecting circuit board. Preferably, the circuit board is connected to the further circuit board by a cable, in particular by a flat-band cable.

[0013] The pressure generator for a braking system according to the present invention comprises a pump mechanism, a drive mechanism for operating the pump mechanism, and a controller for controlling the drive mechanism. The pressure generator is characterized by the inventive configuration of the drive mechanism according to the features of claim 10. This also results in the advantages already mentioned. Further advantageous features and combinations of features are evident from what has been said above and from the claims.

[0014] Next, the present invention will be described in more detail with reference to the drawings. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 2 is a perspective view of a pressure generator for a brake device. [Figure 2] FIG. 10 shows an end shield and sensor mechanism of the drive mechanism of the pressure generator. [Figure 3] FIG. 10 is a cross-sectional view of a region of a circuit board of a sensor mechanism. [Figure 4a] 10A to 10C are diagrams showing an attachment step for fixing the sensor mechanism to the end shield. [Figure 4b] 10A to 10C are diagrams showing an attachment step for fixing the sensor mechanism to the end shield. [Figure 4c] 10A to 10C are diagrams showing an attachment step for fixing the sensor mechanism to the end shield. DETAILED DESCRIPTION OF THE INVENTION

[0016] FIG. 1 is a perspective view of a pressure generator 1 for a hydraulic braking 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. An electric machine (not visible in the figure) of the drive mechanism 2 is arranged within the housing 3. The electric machine includes a rotatably supported rotor and a stator, which is fixedly arranged in the housing and includes a multi-phase motor winding. The rotor is non-rotatably arranged on a drive shaft of the drive mechanism 2, which is rotatably supported within the housing. 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 a plurality of fixing means 6. The drive shaft is operatively connected to the fluid pump by a transmission so that the fluid pump can be operated by the drive mechanism 2 or the electric machine. The pressure generator 1 further includes a controller 8 for controlling the electric machine. The pump mechanism 5 is arranged between the drive mechanism 2 on the one hand and the controller 8 on the other hand.

[0017] To support the drive shaft, the drive mechanism 2 has a metal end shield 9. The end shield 9 is attached to and covers the electric machine. The drive mechanism 2 also has a sensor mechanism 10 formed to detect the rotational position of the rotor of the electric machine. The sensor mechanism 10 is disposed on the machine-side side 11 of the end shield 9. Next, the configurations of the end shield 9 and the sensor mechanism 10 will be described in more detail with reference to Figures 2 and 3. For this purpose, Figure 2 is a perspective view of the end shield 9 and the sensor mechanism 10. Figure 3 is a cross-sectional view of the sensor mechanism 10.

[0018] The sensor arrangement 10 has a ring-disc-shaped sensor circuit board 13. The sensor circuit board 13 is arranged coaxially with the drive shaft and is fixed to the end shield 9 by a carrier element 14 made of plastic. The sensor circuit board 13 has a sensor element 16 on its side 15 facing away from the end shield 9. In this embodiment, the sensor arrangement 10 is configured as an inductive sensor 10. To this end, the sensor element 16 has at least one transmitter coil 17 and at least one receiver coil 18, with the coils 17 and 18 being configured as conductive tracks on the side 15 of the sensor circuit board 13 facing away from the end shield 9.

[0019] The sensor arrangement 10 further includes a circuit board 19. The circuit board 19 is arranged on the end shield 9 at a distance from the sensor circuit board 13. In this embodiment, the circuit board 19 is shaped like a ring segment. The sensor circuit board 13 and the circuit board 19 are electrically connected to each other by a cable 20. In this embodiment, the cable 20 is arranged as a flat-band cable 20. The circuit board 19 includes a connection mechanism 21. The connection mechanism 21 electrically connects or can electrically connect the sensor arrangement 10 to the controller 8. In this respect, the circuit board 19 is arranged as a connecting circuit board 19. In this embodiment, the connection mechanism 21 includes multiple plug connectors 45. The drive mechanism 2 includes a plug guide 46 in the form of a guide sleeve 46 made of plastic. The plug guide 46 at least partially surrounds the plug connector 45 radially. The plug guide 46 is arranged on a side 47 of the end shield 9 facing away from the electric machine and is fixed to the end shield 9.

[0020] A spacer plate 22 is disposed between the end shield 9 and the circuit board 19. The spacer plate 22 is made of an electrically insulating material, so that the conductive tracks formed on the side 50 of the circuit board 19 facing the end shield 9 are electrically insulated from the end shield 9 by the spacer plate 22. The end shield 9 has a plurality of alignment through-holes 51. The spacer plate 22 has alignment protrusions corresponding in number to the alignment through-holes 51, but the alignment protrusions are not visible in the figure. To align the spacer plate 22, each alignment protrusion engages with a corresponding alignment through-hole 51 on the other side. The circuit board 19 has a plurality of alignment through-holes 23. In this embodiment, there are two alignment through-holes 23. The spacer plate 22 has a number of alignment protrusions 24 corresponding to the number of alignment through-holes 23. To align the circuit board 19, each alignment protrusion 24 engages with a corresponding alignment through-hole 23 on the other side.

[0021] The circuit board 19 is fixed to the end shield 9 by a metal fixing means 25. In this embodiment, the fixing means 25 is formed as a locking means 25 or a locking clamp 25. The locking means 25 has a first locking portion 26 and a second locking portion 27. The first locking portion 26 protrudes through a through-hole 28 in the circuit board 19, a through-hole 29 in the spacer plate 22, and a first through-hole 30 in the end shield 9. The first locking portion 26 engages with the end shield 9 from the rear to form a first locking coupling portion 31. The second locking portion 27 protrudes through a second through-hole 32 in the end shield 9 and engages with the end shield 9 from the rear to form a second locking coupling portion 33.

[0022] In this embodiment, the locking portions 26 and 27 each have a base body 34 and a notch 35 oriented at an angle relative to the base body 34 to form the locking coupling 31 or 33. The notch 35 has a first end 36 facing away from the circuit board 19 and a second end 37 facing the circuit board 19. The first end 36 pivotally connects the notch 35 to the base body 34 of the locking portion 26 or 27. The second end 37 of the notch 35 abuts against an abutment surface 38 on the end shield 9 facing away from the circuit board 19, thereby creating the locking couplings 31 and 33. The aforementioned configuration of the notch 35 prevents a force acting on the locking portions 26 and 27 in the direction of the circuit board 19 from releasing the locking couplings 31 and 33. When such a force acts on the locking portions 26 and 27, the force increases the angle between the base body 34 and the notch 35. Therefore, the locking connections 31 and 33 can only be released by means of a special tool.

[0023] The fixing means 25 has a protrusion 40 that protrudes toward the circuit board 19. When the circuit board 19 is fixed to the end shield 9 by the metal fixing means 25 as shown in Figures 2 and 3, the fixing means 25 urges the circuit board 19 with a pretension force acting toward the end shield 9 by means of the protrusion 40. Furthermore, the fixing means 25 urges the end shield 9 with a pretension force acting toward the circuit board 19 by means of the notch portion 35. This results in a mechanically strong and play-free fixation of the circuit board 19 to the end shield 9.

[0024] The circuit board 19 has a ground connection 42 on a side 41 opposite the end shield 9. The ground connection 42 is positioned so that the protrusion 40 of the fastening means 25 contacts the ground connection 42. That is, the protrusion 40 biases the ground connection 42 with a pretensioning force acting toward the end shield 9. Because the fastening means 25 is made of metal and therefore electrically conductive, and is in contact with the ground connection 42 and the end shield 9, the ground connection 42 is electrically coupled to the end shield 9 by the fastening means 25. This facilitates electrical connection of the ground connection 42 to the electrical system ground. In this embodiment, the ground connection 42 is formed as a ground plane 42. Preferably, the ground plane 42 has a galvanic coating. Preferably, the protrusion 40 of the fastening means 25 and the second end 37 of the latch portion 35 also have a galvanic coating. Preferably, this coating is formed as a tin coating, a silver coating, or a gold coating.

[0025] 4a to 4c are diagrams illustrating the procedure for fixing the sensor mechanism 10 to the end shield 9. First, the plug guide 46 is locked to the end shield 9. Next, the spacer plate 22 is attached to the end shield 9 in advance. At this time, the circuit board 19 is attached to the spacer plate 22 in advance. Next, as described above with reference to FIG. 3, the circuit board 19 is fixed to the end shield 9 by the fixing means 25. [Explanation of symbols]

[0026] 1 pressure generator 2. Drive mechanism 3 Electrical machine housing 5. Pump mechanism 8 Controller 9 End Shield 10 Sensor mechanism 19 Circuit Board 22 Spacer plate 25 Fixing means (locking means or locking clamp) 26 First lock part 27 Second locking part 28 Circuit board penetrations 30 First penetration of end shield 31 First locking joint 32 Second penetration of end shield 33 Second locking joint 41 Side of the circuit board opposite the end shield 42 Earth connection

Claims

1. A drive mechanism comprising an electric machine disposed in a housing (3), an end shield (9) attached to the electric machine, and at least one circuit board (19) disposed in the housing (3), the circuit board (19) being fixed to the end shield (9) by a metallic fixing means (25), the metallic fixing means (25) being electrically connected to a ground connection (42) of the circuit board (19), A drive mechanism characterized in that the earth connection portion (42) is arranged on a side (41) of the circuit board (19) opposite the end shield (9), and a protrusion (40) of the fixing means (25) protruding toward the circuit board (19) biases the earth connection portion (42) with a force acting in the direction of the end shield (9).

2. 2. A drive mechanism according to claim 1, characterized in that the metallic fixing means (25) are in contact with the earth connection (42) on the one hand and with the metallic end shields (9) on the other hand.

3. A drive mechanism as described in claim 1, characterized in that the earth connection portion (42) is an earth surface (42) and the fixing means (25) is in face-to-face contact with the earth surface (42).

4. A drive mechanism as described in any one of claims 1 to 3, characterized in that the fixing means (25) is formed as a locking means (25).

5. A drive mechanism as described in claim 4, characterized in that the locking means (25) has a first locking portion (26) and a second locking portion (27), the first locking portion (26) penetrates and protrudes through a first through-hole (30) of the end shield (9) and engages with the end shield (9) from the rear, thereby forming a first locking coupling portion (31), and the second locking portion (27) penetrates and protrudes through a second through-hole (32) of the end shield (9) and engages with the end shield (9) from the rear, thereby forming a second locking coupling portion (33).

6. A drive mechanism as described in claim 5, characterized in that the circuit board (9) has a through-hole (28) and the first locking portion (26) protrudes through the through-hole (28) of the circuit board (19).

7. A drive mechanism described in any one of claims 1 to 3, characterized in that a spacer plate (22) made from an electrically insulating material and arranged between the circuit board (19) and the end shield (9) is provided.

8. A drive mechanism described in any one of claims 1 to 3, characterized in that the drive mechanism (2) has a sensor mechanism (10) formed for detecting the rotational position of the rotor of the electric machine, and the circuit board (19) is part of the sensor mechanism (10).

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 controller (8) for controlling the drive mechanism (2), characterized in that the drive mechanism (2) is configured in accordance with any one of claims 1 to 3.

Images