Search

EP-4146523-B1 - ELECTRONIC CONTROL UNIT AND ELECTRIC POWER STEERING SYSTEM

EP4146523B1EP 4146523 B1EP4146523 B1EP 4146523B1EP-4146523-B1

Inventors

  • ROCKSTEIN, Martin
  • DAUTZENBERG, BERND

Dates

Publication Date
20260506
Application Date
20200508

Claims (10)

  1. Electronic control unit (100) for an electric power steering system (200), the electric power steering system (200) comprising a housing (210) and an electric motor, the electronic control unit (100) being configured to be arranged inside the housing (210) and to be electrically connected to the electric motor, whereby the electronic control unit (100) comprises at least one power board (30, 40) and a heat sink (50), the at least one power board (30, 40) being attached to the heat sink (50), whereby at least one circumferential outer surface (58.1, 58.2) of a heat sink edge (59) of the heat sink (50) is in direct contact with an inner surface (211) of the housing (210) such that heat generated by the at least one power board (30, 40) is conducted via the heat sink (50) to the housing (210), and whereby the heat sink (50) comprises a groove (51) arranged for crimping the housing (210) into the groove (51) and thereby securing the heat sink (50) with the housing (210), characterized in that the electronic control unit (100) comprises a first power board (30) and a second power board (40) as the at least one power board (30, 40), the heat sink (50) being sandwiched in between the first power board (30) and the second power board (40), whereby electronic components (31) of the first power board (30) and electronic components (41) of the second power board (40) are facing towards the heat sink (50), whereby the heat sink (50) comprises several heat conduction surfaces (52) arranged in contact with electronic components (31, 41) of the at least one power board (30, 40), whereby the heat sink (50) comprises several heat conduction surfaces (52) arranged in contact with electronic components (31, 41) of the at least one power board (30, 40) and the several heat conduction surfaces (52) are arranged at different heights along a thickness of the heat sink (50) to accommodate electronic components (31, 41) of different height.
  2. Electronic control unit (100) according to claim 1, whereby the groove (51) is a circumferential groove (51) such that it is arranged around at least half of the circumference of the heat sink edge (59) of the heat sink (50), preferably around the entire circumference of the heat sink (50).
  3. Electronic control unit (100) according to claim 1 or 2, whereby the groove (51) is arranged in between two circumferential outer surfaces (58.1, 58.2) of the heat sink edge (59) directly contacting the inner surface (211) of the housing (210).
  4. Electronic control unit (100) according to any of claims 1 to 3, whereby the crimped housing (210) at the groove (51) is thermally connecting the heat sink (50) with the housing (210).
  5. Electronic control unit (100) according to any of the previous claims, whereby the heat sink (50) is configured as an at least partially circular heat plate.
  6. Electronic control unit (100) according to any of the previous claims, whereby the heat sink (50) comprises heat sink through holes (54) and at least one power board (30) of the at least one power board (30, 40) is secured to the heat sink (50) by means of bolts (1) passing through the heat sink through holes (54) and being fastened in domes (18) extending from a connector plate (10) of the electronic control unit (100).
  7. Electronic control unit (100) according to any of the previous claims, whereby the heat sink (50) comprises heat sink holes (56) and at least one power board (40) of the at least one power board (30, 40) is secured to the heat sink (50) by means of bolts (1) being fastened in the heat sink holes (56).
  8. Electronic control unit (100) according to any of the previous claims, whereby the heat sink (50) comprises heat sink recesses (55) for second power connectors (16) of the electronic control unit (100), the second power connectors (16) extending from a connector plate (10) of the electronic control unit (100) through the heat sink recesses (55) inside of the heat sink (50) to at least one power board (40) of the at least one power board (30, 40).
  9. Electronic control unit (100) according to any of the previous claims, whereby the heat sink (50) comprises a heat sink cutout (53), in particular extending from the heat sink edge (59) to an inside of the heat sink (50), a second logic connector (60) extending from a logic board (20) of the electronic control unit (100) through the heat sink cutout (53) to at least one power board (40) of the at least one power board (30, 40).
  10. Electric power steering system (200) comprising the electronic control unit (100) according to any of the previous claims, whereby the electric motor of the electric power steering system (200) is electrically connected to the at least one power board (30, 40) by means of at least one electric motor connector (80, 90), and whereby the housing (210) of the electric power steering system (200) is crimped into the groove (51) of the heat sink (50) of the electronic control unit (100).

Description

The invention is directed at an electronic control unit for an electric power steering system and an electric power steering system. In the electric power steering system, the electronic control unit can be connected with an electric motor for supplying power to the electric motor from a power source such as a battery. The electric power steering system can assist in a handling operation, typically a steering, of a transportation equipment, either by a driver or a machine in an autonomous vehicle. The transportation equipment can be an automobile. The electric power steering system may further comprise a torque sensor, a steering shaft, a handle, typically a steering wheel, and the power source. In the following, a typical arrangement and operation of the electric power steering apparatus in an automobile will be described. The torque sensor may be mounted on the steering shaft. Upon rotating the steering shaft by operating the handle, the torque sensor detects a torque being applied to the steering shaft by the operation of the handle. Upon detection of the torque by means of the torque sensor, a torque signal is output from the torque sensor to the electronic control unit. The electronic control unit then drives the electric motor based at least on the torque signal. Optionally, the control device may include further data such as vehicle speed in addition to the torque signal for controlling the driving of the electric motor. The electronic control unit drives the electric motor by supplying a driving current from the power source, such as the battery of the automobile, to the electric motor. A driving force generated from the electric motor is then transmitted to the wheels directly or via a gearbox depending on the configuration in the automobile. As a result, the electric power steering apparatus changes a steering angle of the wheels by amplifying the torque of the steering shaft by means of the electric motor. This enables the driver to operate the handle with less force. The electronic control unit comprises a power board electrically connected with the electric motor. The power to the electric motor is transmitted via this power board. Thereby, the power board generates heat during operation of the electronic control unit. To prevent overheating and damage of the electronic control unit, a heat sink may be provided inside of the electronic control unit and arranged in thermal contact with a housing of the electric power steering system or electric motor. DE 10 2007 014 645 A1 describes an electrical assembly for an electric power steering system of a motor vehicle. An electric motor is arranged within a tubular housing made of a heat-conducting material with an electronic control unit for controlling the electric motor and with a heat sink connected to the housing of the electric motor for dissipating heat from power components. The heat sink is inserted into the tubular housing, whereby a radial edge and the radial edge has a diameter corresponding in size to the inner diameter of the tubular housing. US 2018/131256 A1, on which the preamble of claim 1 is based, describes an electric power steering apparatus with an electric motor placed in a motor housing and an electronic control unit part mounted in an ECU housing. The ECU housing is connected to the motor housing. US 2017/349206 A1 describes an integrated electric power steering apparatus in which a control unit for controlling a motor is disposed inside a housing. In the known configurations of the heat sink inside the housing, the heat generated by the power board inside the electronic control unit may be dissipated through the housing of the electric power steering system or the electric motor. However, it is desirable to further improve the heat dissipating characteristics of the electronic control unit at a low cost of manufacturing of the electronic control unit and the electric power steering system. Therefore, it is an object of the present invention, to improve the electronic control unit for an electric power steering system and an electric power steering system known from the state of the art, in particular to provide an electronic control unit for an electric power steering system and an electric power steering system having improved heat dissipating characteristics, which are yet easy to assemble and have low cost of manufacturing. This problem is solved by the claims. Therefore, this object is solved by an electronic control unit according to independent claim 1 and an electric power steering system according to dependent claim 10. Further details of the invention unfold from the dependent claims 2 to 9. as well as the description and the drawings. Thereby, the features and details described in connection with the electronic control unit of the invention apply in connection with the electric power steering system and the other way around, so that regarding the disclosure of the individual aspects of the invention it is or can be