JP7666177B2 - Drive unit - Google Patents

Description

The present invention relates to a drive device.

Conventionally, a control unit including a substrate on which multiple electronic components and a power wiring pattern for supplying power thereto are provided is known, for example, as described in Patent Document 1. In Patent Document 1, the substrate is a multi-layer substrate, with the power wiring patterns arranged on the periphery of a predetermined layer, and the power wiring patterns arranged facing each other between the layers. The opposing power wiring patterns between the layers act as a capacitor that utilizes the dielectric constant of the substrate, reducing the impedance of the power supply and absorbing power supply noise. By suppressing the emission of power supply noise, it is possible to prevent malfunction of peripheral devices.

JP 2002-94246 A

However, in a control unit, it is desirable to protect the control circuit from external noise, and there is room for improvement in this regard.

The present invention has been made in consideration of the above points, and its purpose is to provide a drive device that can protect a control circuit from external noise.

The drive device of the present invention integrally comprises a motor (20) and a control unit (40) that controls the motor. The control unit has a substrate (41) arranged on the rotation axis (O) of the motor, a motor drive element (55) that supplies electricity to the motor, a power wiring pattern (56) that is connected to the motor drive element and supplies power, and a control circuit (61) that sends a control signal to the motor drive element.

The portion of the substrate that is within a predetermined distance from the rotation axis and is closer to the rotation axis than the outer edge of the substrate is defined as the substrate center (45). The portion of the substrate other than the substrate center is defined as the substrate outer periphery (46).

The control circuit is disposed at the center of the substrate, and the power wiring pattern is disposed radially outward from the motor drive element on the outer periphery of the substrate, surrounding the motor drive element and the control circuit by at least half the circumference and extending along the outer edge of the substrate.
If the mounting surface of the board opposite the heat sink (33) is defined as a first mounting surface (47) and the mounting surface of the board facing the heat sink is defined as a second mounting surface (48), the motor drive element is disposed on the first mounting surface. The power wiring pattern includes a power supply pattern (57) disposed on the first mounting surface and connected to the high potential side of the motor drive element to supply power, and a ground pattern (58) disposed on the second mounting surface and connected to the low potential side of the motor drive element, the ground pattern being electrically connected by contacting the heat sink.

This ensures that the power wiring pattern has sufficient conductor capacity to carry a large current, and the motor drive elements and control circuit are surrounded and shielded by conductors with relatively low impedance. This protects the control circuit from external noise.

FIG. 2 is a vertical cross-sectional view of the drive device according to the embodiment. 2 is a diagram showing the substrate, electronic components, and screw in FIG. 1 as viewed from the direction of arrow II. FIG. 3 is an enlarged view of part III of FIG.

The following describes an embodiment of the drive unit with reference to the drawings.

[One embodiment]
1, the drive device 10 integrally comprises a motor 20 and a control unit 40 that controls the motor 20. The control unit 40 controls the motor 20 to generate a desired torque based on information input from the outside and information such as the motor current detected inside the control unit 40. The torque of the motor 20 is output to the outside from the output end of the rotating shaft 26.

The motor 20 is a three-phase brushless motor and includes a stator 21, a rotor 25, and a housing 31 that houses them. The stator 21 has a stator core 22 fixed to the housing 31, and a three-phase winding set 23 assembled to the stator core 22. The three-phase winding set 23 is connected to the control unit 40 via lead wires (not shown).

The rotor 25 has a rotating shaft 26 supported by a rear bearing 35 and a front bearing 36, and a rotor core 27 into which the rotating shaft 26 is fitted. The rotor 25 is provided inside the stator 21 and can rotate relative to the stator 21. A permanent magnet 37 is provided on one end of the rotating shaft 26.

The housing 31 has a cylindrical case 32, a front end frame 33 provided at one end of the case 32, and a rear end frame 34 provided at the other end of the case 32. The front end frame 33 and the rear end frame 34 are fastened to each other by bolts (not shown). The front end frame 33 also functions as a heat sink for the control unit 40. In the following, when describing the function of the front end frame 33 as a heat sink, it will be referred to as the "heat sink 33" as appropriate.

As shown in Figures 1 and 2, the control unit 40 has a heat sink 33 and a substrate 41 arranged on the rotation axis O of the motor 20, a screw 51 as a fixing member for fixing the substrate 41, a motor drive element 55 that supplies electricity to the motor 20, a power wiring pattern 56 connected to the motor drive element 55 to supply power, a control circuit 61 that sends a control signal to the motor drive element 55, and a rotation angle sensor 62 that detects the rotation angle of the rotating shaft 26.

The substrate 41 is disposed on the opposite side of the heat sink 33 from the stator 21. In one embodiment, there is only one substrate 41, but in other embodiments, there may be two or more substrates. The screw 51 passes through a through hole 42 in the substrate 41. The motor drive element 55 is composed of a switching element such as a MOSFET, and performs switching operation in response to a control signal from the control circuit 61 to switch the current flow state of the three-phase winding set 23. The control circuit 61 performs calculations based on information from the outside and the rotation angle sensor 62, etc., and generates signals to command the motor drive element 55, etc.

The control unit 40 further has a cover 64 arranged to cover the board 41 and the electronic components mounted thereon, and a connector 66 for connecting the control unit 40 to the outside.

The cover 64 protects the control unit 40 from external shocks and prevents dust, water, and the like from entering the control unit 40. Electronic components other than the motor drive element 55 and the control circuit 61 are not shown in Figures 1 and 2. The connector 66 is fixed to the connector connection portion 43 of the board 41 by a screw 63, and extends out of the cover 64 through an opening 65.

The portion of the substrate 41 that is within a predetermined distance from the rotation axis O and is closer to the rotation axis O than the outer edge 44 of the substrate 41 is defined as the substrate center 45. The portion of the substrate 41 other than the substrate center 45 is defined as the substrate outer periphery 46.

The control circuit 61 is disposed in the central portion 45 of the substrate. In one particular embodiment, the control circuit 61 is disposed on the rotation axis O and approximately in the center of the central portion 45 of the substrate.

The screws 51 are arranged on the outer periphery 46 of the board to ensure a sufficient mounting area, and fix the board 41 to the heat sink 33. In one embodiment, three screws 51 are provided at intervals in the circumferential direction around the rotation axis O.

The power wiring pattern 56 and the motor drive element 55 are disposed on the outer periphery 46 of the substrate. The power wiring pattern 56 is disposed radially outward (i.e., closer to the outer edge 44) than the motor drive element 55, and is formed so as to surround the motor drive element 55 and the control circuit 61 by more than half the circumference and extend along the outer edge 44. In one embodiment in particular, the power wiring pattern 56 is formed over the entire area of the outer periphery 46 of the substrate other than the connector connection portion 43.

The mounting surface of the substrate 41 opposite the heat sink 33 is defined as the first mounting surface 47. The mounting surface of the substrate 41 facing the heat sink 33 is defined as the second mounting surface 48.

The motor drive element 55 is disposed on the first mounting surface 47. In other words, the motor drive element 55 is disposed on the opposite side of the substrate 41 from the heat sink 33.

The power wiring pattern 56 includes a power supply pattern 57 arranged on the first mounting surface 47 and connected to the high potential side of the motor driving element 55 to supply power, and a ground pattern 58 arranged on the second mounting surface 48 and connected to the low potential side of the motor driving element 55. The power supply pattern 57 and the ground pattern 58 are arranged facing each other between the substrates 41. The ground pattern 58 is electrically connected by contacting the heat sink 33.

The ground pattern 58 is formed up to the edge of the through hole 42 and is in contact with the screw 51. The ground pattern 58 is directly connected to the heat sink 33, and is also indirectly connected to the heat sink 33 via the screw 51.

(effect)
As described above, in one embodiment, the control circuit 61 is disposed in the substrate central portion 45. The power wiring pattern 56 is disposed radially outward from the motor driving element 55 in the substrate outer peripheral portion 46, and is formed so as to surround the motor driving element 55 and the control circuit 61 by more than half the circumference and to extend along the outer edge 44 of the substrate 41. This ensures that the power wiring pattern 56 has a conductor capacity sufficient to allow a large current to flow, and therefore the motor driving element 55 and the control circuit 61 are surrounded and shielded by a conductor with a relatively low impedance. This makes it possible to protect the control circuit 61 from external noise.

In one embodiment, the motor driving element 55 is disposed on the first mounting surface 47. The power wiring pattern 56 includes a power supply pattern 57 disposed on the first mounting surface 47 and connected to the high potential side of the motor driving element 55 to supply power, and a ground pattern 58 disposed on the second mounting surface 48 and connected to the low potential side of the motor driving element 55. The ground pattern 58 is electrically connected by contacting the heat sink 33. By electrically connecting the ground pattern 58 to the heat sink 33 in this manner, the impedance of the power wiring pattern 56 is further reduced, and the shielding effect of the power wiring pattern 56 can be further enhanced.

In one embodiment, the power wiring pattern 56 is formed on the entire outer periphery 46 of the substrate, except for the connector connection portion 43. This allows the substrate 41 to be effectively shielded by surrounding it almost entirely.

[Other embodiments]
In another embodiment, the power wiring pattern may be formed to surround the entire periphery of the substrate.

The present invention is not limited to the above-described embodiment, and can be implemented in various forms without departing from the spirit of the invention.

10 Drive device, 20 Motor, 33 Heat sink, 40 Control unit, 41 Board, 44 Outer edge, 45 Board center, 46 Board outer periphery, 51 Screw (fixing member), 55 Motor drive element, 56 Power wiring pattern, 61 Control circuit, O Rotation axis.

Claims (2)

A drive device integrally comprising a motor (20) and a control unit (40) for controlling the motor,
The control unit includes a substrate (41) arranged on a rotation axis (O) of the motor, a motor drive element (55) for supplying electricity to the motor, a power wiring pattern (56) connected to the motor drive element for supplying power, and a control circuit (61) for sending a control signal to the motor drive element,
A portion of the substrate within a predetermined distance from the rotation axis and closer to the rotation axis than the outer edge (44) of the substrate is defined as a substrate center (45), and a portion of the substrate other than the substrate center is defined as a substrate outer periphery (46).
The control circuit is disposed in the center of the substrate,
the power wiring pattern is disposed radially outwardly of the motor drive element in the outer periphery of the substrate, and is formed to surround the motor drive element and the control circuit by at least half a circumference and to extend along the outer edge ;
The mounting surface of the substrate opposite the heat sink (33) is defined as a first mounting surface (47), and the mounting surface of the substrate facing the heat sink is defined as a second mounting surface (48).
the motor drive element is disposed on the first mounting surface,
the power wiring pattern includes a power supply pattern (57) disposed on the first mounting surface and connected to a high potential side of the motor driving element to supply power, and a ground pattern (58) disposed on the second mounting surface and connected to a low potential side of the motor driving element,
A drive device , wherein the ground pattern is electrically connected to the heat sink by contacting the heat sink . The control unit further includes a connector (66) for connecting the control unit to an external device;
The outer periphery of the substrate has a connector connection portion (43) connected to the connector,
2. The drive device according to claim 1 , wherein the power wiring pattern is formed over the entire outer periphery of the substrate other than the connector connection portion.

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