Electric control unit and assembling method thereof

Abstract

The invention discloses an electronic control unit and a method for assembling the electronic control unit. The electric control unit comprises a shell; the circuit board assembly is located in the shell, the circuit board assembly comprises a circuit board, and the circuit board is electrically connected with at least one power device; and a bracket having a first support portion configured to support a first portion of a first surface of the at least one power device during pre-assembly, and a pressing portion configured to apply a force to a second surface of the at least one power device, wherein the second surface is opposite to the first surface; wherein the housing has a second support portion configured to support a second portion of the first surface of the at least one power device during final assembly. The electronic control unit has a good heat dissipation effect.

Description

TECHNICAL FIELD

[0001] The present application relates to an electronic control unit. The present application also relates to a method of assembling the electronic control unit. BACKGROUND

[0002] An electronic control unit (ECU) is a control device for a vehicle, which is composed of integrated circuits. The electronic control unit generally has a housing in which a circuit board is arranged, and electronic components on the circuit board, such as power devices, generate heat when working. A plurality of power devices are arranged in the electronic control unit, and thus a large amount of heat is generated. The design of the electronic control unit includes heat dissipation and insulation of the power devices, and also takes into account the fixation of these power devices with respect to the housing.

[0003] In the current technology, in order to dissipate heat, the power devices are fastened to the housing of the electronic control unit by screws, or fastened by a spring sheet which is pressed onto the power devices under a certain pressure. The above-mentioned methods can make the power devices in contact with the housing, and the heat is taken away by the housing. The effective contact area between the power devices and the housing determines the heat dissipation effect. SUMMARY

[0004] An aspect of the present application is to provide an electronic control unit which maintains good contact between a power device and a housing.

[0005] The electronic control unit comprises

[0006] a housing,

[0007] a circuit board assembly located in the housing, the circuit board assembly comprising:

[0008] a circuit board electrically connected to at least one power device; and

[0009] a support having a first support portion configured to support a first portion of a first surface of the at least one power device during pre-assembly; and

[0010] a pressing portion configured to apply a force to a second surface of the at least one power device, wherein the second surface is opposite to the first surface;

[0011] wherein the housing has a second support portion configured to support a second portion of the first surface of the at least one power device during final assembly.

[0012] In an embodiment of the electronic control unit, the second support portion is formed as a step protruding inwardly of the housing.

[0013] In an embodiment of the electronic control unit, the second surface faces the circuit board.

[0014] In one embodiment of the electronic control unit, the first support portion has a hollow region, and the second support portion is positioned to be inserted into the hollow region.

[0015] In one embodiment of the electronic control unit, the step height is set to have a difference between a surface of the step and a surface of the first support portion during the final assembly.

[0016] In one embodiment of the electronic control unit, the pressing portion is connected to the bracket, and the pressing portion includes an elastic element configured to abut against a second surface of the power device and to be deformed once during the pre-assembly and to be deformed twice during the final assembly.

[0017] In one embodiment of the electronic control unit, the elastic element is a plate, a portion of the plate is fixed to the bracket via a screw, and an end portion of the plate is configured to be movable on the second surface of the at least one power device such that the plate is deformed in extension.

[0018] In one embodiment of the electronic control unit, the second support portion is provided on a side of the housing having a heat sink or on a side of the housing having a heat dissipation device provided outside the housing.

[0019] In one embodiment of the electronic control unit, the bracket has a connecting portion corresponding to an edge portion of the circuit board, and the housing is configured to have a threaded hole such that a fastener is screwed into the threaded hole after passing through the edge portion and the connecting portion.

[0020] In one embodiment of the electronic control unit, the bracket has a seat, a first side and a second side of the seat are arranged with a first power device and a second power device, respectively, the plate includes a first pressing portion and a second pressing portion, the first pressing portion acts on the first power device, the second pressing portion acts on the second power device, and a first step corresponding to the first power device and a second step corresponding to the second power device are integrated on the housing.

[0021] In one embodiment of the electronic control unit, the at least one power device is soldered to the circuit board by a pin, the pin extends from a side portion of the at least one power device between the first surface and the second surface and passes through a hole provided by the bracket after being bent once, and then reaches a soldering hole on the circuit board.

[0022] Another aspect of the present application is to provide a method of assembling the electronic control unit of any one of the above embodiments, comprising:

[0023] pre-assembling the bracket, the at least one power device, and the circuit board to form the circuit board assembly; and

[0024] the circuit board assembly is assembled with the housing such that the at least one power device is in contact with the housing.

[0025] After assembly, the electric control unit according to the present application ensures that the circuit board assembly is fixed relative to the housing while ensuring that the power device is tightly attached to the housing to obtain as much effective contact area as possible, so that the heat generated by the power device is carried away via the housing. During final assembly, the power device is mainly supported by the second support part from the housing while being pressed by the pressing part, the surface of the power device is attached to the second support part, and is fastened between the pressing part and the housing. In the present application, the fixation of the power device is associated with the bracket and the housing, without the need for fasteners, and the design of the circuit board is not affected.

[0026] The second support part is provided as a step that can be inserted between the first support part to replace the main support for the power device. By the difference between the step and the first support part, a pushing force of the power device towards the pressing part can be provided, and in turn a sufficient pressure of the pressing part against the power device is generated on the pressing part to press the power device against the step. The pressing part adopts an elastic element and has a pre-elastic force before being in contact with the step, which ensures the positioning of the power device in the bracket and provides effective pressure. The step is arranged near the heat sink or heat dissipation device, which helps to transfer the heat of the power device.

[0027] In the case where the electric control unit includes multiple power devices, the number of pressing parts corresponds to the number of power devices, and the power devices are respectively supported by different steps. When there is a dimensional error between the steps or the housing is not flat, the independent pressing parts can respectively provide corresponding pressure to the power devices, so as to eliminate the force imbalance between the multiple power devices, and at the same time, the requirement for manufacturing the housing is reduced.

[0028] The present application does not need to process the circuit board with respect to the fixation and heat dissipation of the power device, so the circuit board can not be provided with a forbidden area, which is beneficial to the circuit arrangement of the circuit board.

[0029] The present application also simplifies the assembly steps of the electric control unit and reduces the manufacturing cost.

[0030] Other aspects and features of the present application will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, illustrating the principles of the application by way of example only. It should be understood, however, that the drawings merely for the purpose of explanation and are not limiting of the scope of the application, as described in the appended claims. It should also be understood that the drawings are not necessarily drawn to scale and that, unless otherwise indicated, they are merely intended to conceptually illustrate the structures and procedures described herein. BRIEF DESCRIPTION OF DRAWINGS

[0031] The application will be more fully understood with reference to the following detailed description taken in conjunction with the accompanying drawings, in which like elements are referred to with like reference numerals, and in which:

[0032] Figure 1 A partial view of an embodiment of an electric control unit to which the present application pertains;

[0033] Figure 2 A view of an embodiment of an electric control unit to which the present application pertains during pre-assembly; and

[0034] Figure 3 A view of an embodiment of an electric control unit to which the present application pertains during final assembly. DETAILED DESCRIPTION

[0035] To assist those skilled in the art with a complete understanding of the subject matter of the present application, a detailed description of a specific embodiment of the present application is provided below with reference to the accompanying drawings.

[0036] Figure 1 A partial view of an embodiment of an electric control unit to which the present application pertains. As shown, the electric control unit includes a housing 10, a circuit board assembly 60, and a presser 74. The circuit board assembly 60 includes a circuit board 62 and a bracket 64. The circuit board 62 is electrically connected to at least one power device. In the illustrated embodiment, there are two power devices. The power devices 36, 38 are, for example, IGBTs, MOFFETs, or diodes, etc. The power devices generate a large amount of heat during operation. The bracket 64 is an insulating member, such as made of plastic. The bracket 64 is in the form of a concave middle relative to the edges. The bracket 64 has a first support portion 68 at the bottom of the concave portion for supporting a portion of the power device. As Figure 2 shown, the power device 66 includes a first surface 70 as a lower surface and a second surface 72 as an upper surface. The first surface 70 and the second surface 72 are opposite. A first portion 76 of the first surface 70 is supported by the first support portion 68. Other portions of the first surface 70, such as a second portion 78, are supported by the housing 10. The housing 10 has a second support portion 12, and the second portion 78 of the first surface is supported by the second support portion 12. The presser 74 exerts a force on the second surface 72 of the power device.

[0037] The first support portion 68 and the second support portion 12 provide primary support to the power device during different processes. In the case of only the circuit board assembly, the first portion 76 of the first surface of the power device is supported by the first support portion 68. In one embodiment, the presser 74 presses the power device 66 against the first support portion 68 and thereby against the bracket 64, as Figure 2The second part 78 of the first surface of the power device is supported by the second support portion 12 when the circuit board assembly and the housing are assembled together, and the pressing portion 74 presses the power device 66 against the second support portion 12 and thus against the housing 10, as shown in Figure 3

[0038] The first support portion 68 has a hollow region 80 in which the second support portion 12 is positioned. When the circuit board assembly is assembled to the housing, the second support portion 12 can pass through the hollow region 80 and thus carry the power device 66.

[0039] In the illustrated embodiment, the second support portion 12 is configured as a step 14 that protrudes inwardly from the housing 10. When the circuit board assembly is assembled to the interior of the housing, the step 14 is inserted into the hollow region 80 and thus comes into contact with the power device 66.

[0040] In one embodiment, the step 14 is configured to have a height difference h between its surface and the surface of the first support portion 68, as shown in Figure 3 When the circuit board assembly and the housing are assembled in place, the step 14 is higher than the first support portion 68. The height difference h does not need to be large, for example, in the range of 0.2-0.5 mm. This small height difference can generate a pushing force on the first surface 70 of the power device to make it rise, and on the opposite second surface 72, due to the pressing of the pressing portion 74, the downward pressure is increased to tightly press the power device 66 against the step 14. In one embodiment, the step is provided on the side of the housing that has a heat sink, and the heat generated by the power device is transferred to the housing and then to the heat sink through the step, and is carried away by the cooling medium. In another embodiment, the housing does not have a heat sink, but the housing is in close proximity to a heat dissipation device, for example, the housing is arranged on the heat dissipation device of an electric motor. In this case, the heat generated by the power device can also be transferred to the housing and then to the heat dissipation device outside the housing through the step, as shown in Figure 1 The cooling medium passes through the heat dissipation device 22 to carry away the heat, as shown by the arrows.

[0041] The surface of the step can be provided with a layer of glue that has both insulation and heat conduction functions, or a multi-layer pad formed by stacking an insulating layer and a heat conducting layer. Due to the pushing force exerted by the step, the pressure of the opposite pressing portion can be increased, so that the power device is tightly attached to the step, and when there is no gap between the power device and the step, the effective contact area of the power device is maximized, achieving good heat dissipation effect.

[0042] ​In one embodiment, the pressing portion 14 is connected to the holder 64. The pressing portion 14 is configured as an elastic element 82 which is deformed when it is pressed against the second surface 72 of the power device. In another embodiment, the elastic element 82 is deformed once when the first support portion 68 supports the power device 66 to position the power device 66 in the holder 64. When the second support portion 12 supports the power device 66, the second support portion 12 lifts the power device 66 and causes the elastic element 82 to deform again. The pressure generated by the deformation of the elastic element 82 acts on the power device 66 and presses it against the second support portion 12. For example, if the height h of the step is in the range of 0.2-0.5 mm, the elastic element 82 can generate a force of 20-100 N to press the power device firmly against the step. The height of the step 14 is calculated in relation to the pressure that the elastic element can exert.

[0043] In one embodiment, the elastic element is a plate, for example a leaf spring, which has a fixed portion 86 and is fixed to the holder 64. In another embodiment, the leaf spring is assembled to the holder 64. The end of the leaf spring is a moving end 88 which can move on the second surface 72 of the power device. When the leaf spring is deformed, its moving end 88 moves on the second surface 72 and the shape of the leaf spring is stretched. In other embodiments, the pressing portion can be connected to the housing and the second surface of the power device is pressed by the force transferred from the housing to the pressing portion.

[0044] The holder 64 has a seat 84. The pressing portion 74 is fixed to the seat 84 by means of screws, rivets, etc. The seat 84 has the pressing portion and the power device arranged on its two sides, respectively. The pressing portion comprises a first pressing portion 32 and a second pressing portion 34 and acts on the power device separately. In one embodiment, the first pressing portion 32 acts on the first power device and the second pressing portion 34 acts on the second power device. The first pressing portion 32 and the second pressing portion 34 can be connected to each other, for example, the first pressing portion 32 and the second pressing portion 34 are integrated on the two sides of a leaf spring, respectively, or the first pressing portion 32 and the second pressing portion 34 are separate. As shown in Fig. 1, the first pressing portion 32 and the second pressing portion 34 are separate. Figure 1As shown, on the left side, i.e. the first side, of the seat 84, one end of the first pressing portion 32 is clamped in one slot of the seat 84, and the other end abuts against the second surface of the first power device 36. On the right side, i.e. the second side, of the seat 84, one end of the second pressing portion 34 is clamped in the opposite slot of the seat 84, and the other end abuts against the second surface of the second power device 38. The pressing portions and the power devices are arranged in a symmetrical manner, and can also be arranged in other manners. The illustrated embodiment only shows one cross section of the electronic control unit. In other embodiments, a plurality of power devices can be arranged in the electronic control unit, and these power devices are symmetrically arranged on both sides of the seat. The first step 40 and the second step 42 are integrated inside the housing to support the first power device 36 and the second power device 38 respectively. The number of the pressing portions, the power devices, and the steps correspond to each other, which is advantageous to eliminate manufacturing errors. When there is a slight manufacturing error between the first step 40 and the second step 42, or the housing has a slight defect, resulting in that the first side and the second side are not completely symmetrical as they should be, the first power device and the second power device have a potential unbalanced force condition. Since the first pressing portion 32 is independent of the second pressing portion 34, they can each adaptively adjust the force applied to the first power device 36 and the second power device 38, thereby eliminating the above-mentioned unbalanced risk, and thus the manufacturing requirements of the housing can be reduced, in turn reducing the cost.

[0045] The seat 84 for fixing the pressing portions is located in the center of the bracket 64. The edge of the bracket 64 is formed as a connecting portion 90, and is connected with the edge of the circuit board 62. Corresponding to the connecting portion 90, the housing 10 is provided with a boss 16, and a threaded hole is provided in the boss 16. The fastener 20 is screwed into the threaded hole after passing through the edge of the circuit board 62 and the connecting portion 90.

[0046] The power devices are electrically connected with the circuit board 62 through the pins 92. The power devices are arranged such that they are opposite to the circuit board 62, i.e. the second surfaces face the circuit board 62. The pins 92 extend from one side of the power devices between the first surfaces and the second surfaces. The bracket 64 provides protection holes 94 for the pins. The pins 92 pass through the holes 94 after being bent once, and finally reach the corresponding soldering holes of the circuit board 62.

[0047] The assembly process of the electronic control unit related to the present application will be introduced below. The assembly process includes two steps: a pre-assembly step and a final assembly step. In the pre-assembly step, a circuit board assembly is formed; in the final assembly step, the circuit board assembly is assembled with the housing.

[0048] First, the bracket 64 is provided. In one embodiment, the bracket 64 is integrated with a first support portion 68 for positioning the power devices, a seat 84 for positioning the pressing portions 74, a hole 94 for positioning the pins 92 of the power devices, and a connecting portion 90.

[0049] The power device is placed in the bracket 64, and a first portion 76 of the first surface of the power device is supported by the first support portion 68. Then the pressing portion 74 is installed, so that one end of the pressing portion 74 is fixed with the bracket 64, and the other end is abutted on the second surface 72 of the power device. The pressing portion 74 is deformed to a certain extent, so that the power device is pre-positioned in the bracket 64.

[0050] The circuit board 62 is placed above the bracket 64, and the pins 92 of the power device are inserted into the soldering holes after passing through the holes 94. Then the pins 92 are soldered, as shown in Figure 2 The circuit board assembly is formed.

[0051] Then the circuit board assembly is placed in the housing 10, and the holes on the edge of the circuit board 62 and the holes on the bracket connecting portion 90 are aligned with the threaded holes of the housing boss 16. The second support portion 12 passes through the hollow area 80.

[0052] The fastener 20 is screwed into the threaded holes through the circuit board 62 and the bracket 64. As the fastener 20 is screwed in deeper and deeper, the second support portion 12 generates an upward pushing force on the second portion 78 of the first surface of the power device, and the pushing force in turn makes the fixed pressing portion 74 continue to deform, and the force generated by the continuous deformation of the pressing portion 74 is reacted on the second surface 72 of the power device, so as to press the power device against the second support portion 12.

[0053] In the assembled electronic control unit, there is a space 96 between the circuit board 62 and the bracket 64, which is beneficial to heat dissipation of the circuit board and the power device. The power device is clamped by the forces on the first surface 70 and the second surface 72, and is in close contact with the housing 10. The power device is fixed without using screws, and there is no need to set a forbidden area in the area where the circuit of the circuit board is arranged. The application provides a solution with cost reduction, mechanical reliability, and good heat dissipation effect.

[0054] Although the specific embodiments of the application have been shown and described in detail to illustrate the principles of the application, it should be understood that the application can be implemented in other ways without departing from such principles.

Claims

1. An electronic control unit, characterized by Comprising: a housing (10), a circuit board assembly (60) located within the housing (10), the circuit board assembly (60) comprising: a circuit board (62) electrically connected to at least one power device (66); and a bracket (64) having a first support portion (68) configured to support a first portion (76) of a first surface (70) of the at least one power device (66) during a pre-assembly; and a pressing portion (74) configured to apply a force to a second surface (72) of the at least one power device (66), wherein the second surface (72) is opposite to the first surface (70); wherein the housing (10) has a second support portion (12) configured to support a second portion (78) of the first surface (70) of the at least one power device (66) during a final assembly.

2. The electronic control unit of claim 1, wherein: the second support portion (12) is formed as a step (14) protruding into an interior of the housing (10); the first support portion (68) has a hollow region (80) into which the second support portion (12) is positioned; the second surface (72) is positioned to face the circuit board (62).

3. The electronic control unit of claim 1, wherein: the step (14) is dimensioned such that there is a drop (h) between a surface of the step (14) and a surface of the first support portion (68) during the final assembly.

4. The electronic control unit of claim 1, wherein: the pressing portion (74) is connected to the bracket (64), the pressing portion (74) comprising an elastic element (82) configured to rest against the second surface (72) of the power device (66) and to undergo a primary deformation during the pre-assembly and a secondary deformation during the final assembly.

5. The electronic control unit of claim 4, wherein: the elastic element (82) is a plate, a portion of the plate being fixed to the bracket (64) via a screw, an end of the plate being configured to be movable on the second surface (72) of the at least one power device (66) such that the plate undergoes a stretching deformation.

6. The electronic control unit of claim 1, wherein: the second support portion (12) is provided on a side of the housing (10) having a heat sink or on a side of the housing (10) having a heat dissipating device provided outside thereof.

7. The electronic control unit of claim 1, wherein: the bracket (64) has a connecting portion (90) corresponding to an edge portion of the circuit board (62), the housing (10) being configured to have a threaded hole such that a fastener (20) is screwed into the threaded hole through the edge portion and the connecting portion (90).

8. The electronic control unit of claim 5, wherein: The bracket (64) has a seat (84), a first power device (36) and a second power device (38) are arranged on a first side and a second side of the seat (84), respectively; the plate includes a first pressing portion (32) and a second pressing portion (34), the first pressing portion (32) acts on the first power device (36), and the second pressing portion (34) acts on the second power device (38); a first step (40) corresponding to the first power device (36) and a second step (42) corresponding to the second power device (38) are integrated on the housing (10).

9. The electronic control unit of claim 1, wherein: The at least one power device (66) is soldered to the circuit board (62) via a pin (92); the pin (92) extends from a side of the at least one power device (66) between the first surface (70) and the second surface (72), and after undergoing a single bend, passes through a hole (94) provided by the bracket (64), thereby reaching a soldering hole on the circuit board (62).

10. A method of assembling an electronic control unit according to any one of claims 1-9, characterized by include: pre-assembling the bracket (64), the at least one power device (66), and the circuit board (62) to form the circuit board assembly (60); The circuit board assembly (60) is assembled with the housing (10) such that the at least one power device (66) is in contact with the housing (10).

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