Patent Application
20230062275
In the context of a motor vehicle, the term electronic control unit (ECU) refers to any computer embedded in the vehicle that controls one or more of the electrical systems or subsystems of the vehicle. Examples of different types of ECUs include engine control modules, transmission control modules, brake control modules, body control modules, and others.
An ECU typically consists of a printed circuit board (PCB) within a housing. There are two main types of ECU housing: bucket-style (also known as slide-in style) or sandwich-style. In a bucket-style housing, the housing is of one-piece construction with an opening at one end through which the PCB is inserted. In a sandwich-style housing, the housing is of two-piece construction, with the PCB secured between the housing portions. Each of the housing types has advantages and disadvantages, but conventionally bucket-style housings are lower-cost while offering less design flexibility than sandwich-style housings.
One area in which conventional bucket-style housings offer less design flexibility than sandwich-style housings is temperature regulation. For example, conventional bucket-style housings restrict the use of heat sinks. This in part because, with a conventional bucket-style housing, any thermal interface material (TIM) applied to a heat-producing component on the PCB would be rubbed off during insertion of the PCB into the housing. The improved ECU housing described herein overcomes this disadvantage without incurring significant cost—thus adding design flexibility while preserving the cost advantages of a bucket-style ECU housing.
One aspect of this disclosure is directed to an ECU for a motor vehicle. The ECU includes a printed circuit board (PCB) in a housing. Some components on the PCB may produce heat when operating. Examples of such heat-producing components include microprocessors, power supplies, memory chips, and others. If the temperature of a heat-producing component is left unregulated, it can overheat during normal operation, causing a temporary malfunction or permanent failure of the ECU.
Heat sinks may be used to help regulate the temperature of heat-producing components. A heat sink is made of a thermally conductive material, such as aluminum, and conducts heat away from the heat-producing component where it can dissipate in a fluid, such as the ambient air. A heat sink may include features such as fins to increase its surface area contacting the air (or other fluid) and thereby maximize heat dissipation.
A thermal interface material (TIM) may be used to enhance thermal coupling between a heat-producing component and a heat sink. A heat-producing component and a heat sink are thermally coupled when a thermally conductive path exists between them such that heat may be transferred from the heat-producing component to the heat sink. A TIM consists of a thermally conductive paste or gel that maximizes thermal coupling by filling any air gaps between the heat-producing component and heat sink. Preferably, a TIM is applied to the surface of a heat-producing component that will contact a heat sink before the PCB is inserted into the housing.
The housing of the ECU is preferably made of molded plastic in a one-piece bucket-style construction. The housing includes a pair of side rails to support the PCB and a heat sink positioned to thermally couple with a heat-producing component on the PCB. During assembly of the ECU, the PCB is slid into the housing through an opening at one end and along the side rails. At the end of each side rail opposite the opening, there is a ramp that lifts the PCB towards the top wall of the housing, thus allowing the electrical component to thermally couple with the heat sink. Locating the ramp at the end of the rails opposite the opening prevents the TIM from being rubbed or scraped off on the housing prior to making contact with the heat sink.
The above aspects of this disclosure and other aspects will be explained in greater detail below with reference to the attached drawings.
The illustrated embodiments are disclosed with reference to the drawings. However, it is to be understood that the disclosed embodiments are intended to be merely examples that may be embodied in various and alternative forms. The figures are not necessarily to scale and some features may be exaggerated or minimized to show details of particular components. The specific structural and functional details disclosed are not to be interpreted as limiting, but as a representative basis for teaching one skilled in the art how to practice the disclosed concepts.
As shown in
The housing 2 is preferably of one-piece molded plastic construction but could be of any suitable material. It consists, generally, of a base 4, a top wall 5, a bottom wall 6, and two side walls 7, with an opening 8 at one end. The base 4 is the portion of the housing that is opposite the opening and from which the walls extend. The base 4 can be flat, curved, or irregular in profile. The walls 5-7 are the portions of the housing 2 that extend away from the base 4 towards the opening 8. Together the walls 5-7 define and surround the opening 8. The walls 5-7 can be flat, curved, or irregular in profile. Adjacent walls 5-7, or one or more walls 5-7 and the base 4, can be merged into one another such that there is no clear edge between them. The top wall 5 is the wall that faces the surface of the PCB that contains the microprocessor 3, i.e. the top side of the PCB. The bottom wall 6 is opposite the top wall 5 and faces the underside of the PCB. The top wall 5 and bottom wall 6 of the housing are connected via the side walls 7.
On the top wall 5 of the housing 2 a heat sink 9 is attached. The heat sink 9 is made of a thermally conductive material, such as aluminum, and may include features, such as fins, to increase its surface area. In the disclosed embodiment, the heat sink 9 is attached to the outside of the housing 2. Alternatively, the heat sink 9 can be attached inside the housing 2. The heat sink 9 may be attached to the housing 2 via adhesive, heat staking, retention features, press-in, or overmolding. In the disclosed embodiment, the heat sink 9 thermally couples with the microprocessor 3 through an aperture 19 in the housing 2. (See
On each side wall 7 of the housing 2 is a rail 11. The rails 11 extend from the opening 8 to a slot 13 at the base 4. During assembly of the ECU, the rails 11 guide and support the PCB 1 as it is inserted into the housing 2 through the opening 8. The rails 11 are angled slightly towards to the top wall 5 such that the distance between the rails 11 and the top wall 5 is less near the base 4 than near the opening 8. This allows for easy insertion of the PCB 1 into the housing 2 while also guiding the PCB 2 towards its final location. At the end of the rails 11 opposite the opening 8, each rail 11 forms a ramp 12 that lifts the PCB 1 further towards the top wall 5 of the housing 2, thus allowing the microprocessor 3 to thermally couple with the heat sink 9. Locating the ramp 12 at the end of the rail 11 opposite the opening 8 prevents the TIM 10 (which is applied to the microprocessor 3 prior to inserting the PCB 1 into the housing 2) from being rubbed or scraped off prior to making contact with the heat sink 9.
Upon reaching the top of the ramp 12, the PCB 1 mates with the slot 13 at the base 4 of the housing 2. The slot 13 contains compression features such as crush ribs 14 to grip the PCB 1. (See
At the end of the PCB 1 opposite the slot 13, a connector 15 mounted on the PCB 1 includes one or more teeth 16 (see
While exemplary embodiments are described above, it is not intended that these embodiments describe all possible forms of the disclosed apparatus and method. Rather, the words used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of the disclosure as claimed. The features of various implementing embodiments may be combined to form further embodiments of the disclosed concepts.
