Electric power shovel, and method of assembling drive unit for driving motor of electric power shovel

Abstract

The present application provides an electric working machine and a method of assembling a driving unit for driving a motor of the electric working machine. One aspect of the present application relates to an electric working machine including a motor, a circuit board, a first semiconductor switch, a metal plate, a heat dissipation member, and an externally threaded member. The first semiconductor switch is on a first circuit surface of the circuit board, has a first metal surface and a first mounting surface, and is electrically connected to a power source and the motor. The first mounting surface is on an opposite side of the first metal surface and faces the first circuit surface. The metal plate has a first plate surface that is joined to the first metal surface and a second plate surface that is on an opposite side of the first plate surface. The heat dissipation member directly or indirectly contacts the second plate surface. The externally threaded member fastens the heat dissipation member and the metal plate.

Description

Technical Field

[0001] This invention relates to an electric work machine equipped with a semiconductor switch. Background Technology

[0002] Japanese Patent No. 5512110 discloses an electric tool comprising a drill bit, a motor that generates driving force to drive the drill bit, and a drive circuit that drives the motor. The drive circuit includes six switching elements. Summary of the Invention

[0003] In recent years, power tools, including electric work machines, have become increasingly high-output. This has led to an increase in the current flowing through the motors and drive circuits of these machines. Consequently, the heat generated by the switching elements within the drive circuits has also increased. Therefore, it is necessary to efficiently dissipate the heat generated by these switching elements.

[0004] One aspect of the present invention aims to improve the heat dissipation efficiency of semiconductor switches in electric work machines.

[0005] In this invention, the terms "first," "second," etc., are merely intended to distinguish elements from each other, and are not intended to limit the order or number of elements. Therefore, the first element can be called the second element, and similarly, the second element can be called the first element. In addition, the first element can be present without the second element, and similarly, the second element can be present without the first element.

[0006] One aspect of the present invention provides an electric work machine comprising a motor, a circuit board, a first semiconductor switch, a metal plate, a heat sink, and an external threaded component. The motor is configured to receive power from a power source for driving. The circuit board has a first circuit surface and a second circuit surface located opposite to the first circuit surface. The first semiconductor switch is located on the first circuit surface, has a first metal surface and a first mounting surface, and is electrically connected to the power source and the motor. The first mounting surface is located opposite to the first metal surface and faces the first circuit surface. The metal plate has a first plate surface that engages with the first metal surface and a second plate surface located opposite to the first plate surface. The heat sink is in direct or indirect contact with the second plate surface. The external threaded component securely connects the heat sink and the metal plate.

[0007] According to this electric working machine, the heat generated by the first semiconductor switch is dissipated to the outside via a metal plate and a heat sink. By placing the metal plate between the first semiconductor switch and the heat sink, the heat dissipation path can be enhanced. Furthermore, the heat sink and the metal plate are fastened together using an external threaded component, improving the tightness of contact between the heat sink and the metal plate. As a result, heat can be effectively transferred from the metal plate to the heat sink. Therefore, the heat dissipation efficiency of the first semiconductor switch can be improved.

[0008] Another aspect of the present invention provides a method for assembling a drive unit for driving a motor of an electric work machine. The method includes the steps of: mounting a semiconductor switch of the drive unit on a circuit board of the drive unit, the semiconductor switch having a mounting surface and a metal surface opposite to the mounting surface, with the mounting surface facing the circuit board; joining a first plate surface of a metal plate to the metal surface; directly or indirectly contacting a heat dissipation component with a second plate surface located opposite the first plate surface; and fastening the heat dissipation component and the metal plate together using screws.

[0009] This method can improve the heat dissipation efficiency of semiconductor switches. Attached Figure Description

[0010] Figure 1 This is a diagram showing the appearance of the electric work machine according to the first and second embodiments.

[0011] Figure 2 This is a diagram showing the electrical configuration of the electric work machine according to the first and second embodiments.

[0012] Figure 3 This is a top view showing the circuit board equipped with the drive circuit according to the first embodiment.

[0013] Figure 4 This is a cross-sectional view of the circuit board according to the first embodiment.

[0014] Figure 5 This is a diagram showing a modified example of the cross-section of the circuit board according to the first embodiment.

[0015] Figure 6 This is a diagram showing the first circuit plane of the circuit board equipped with the drive circuit according to the second embodiment.

[0016] Figure 7 This is a diagram showing the second circuit surface of the circuit board according to the second embodiment.

[0017] Figure 8 This is a diagram showing the appearance of the metal component inserted into the circuit board according to the second embodiment.

[0018] Figure 9 This is a diagram showing the electrical connection between the source terminal of the first semiconductor switch and the drain terminal of the fourth semiconductor switch according to the second embodiment.

[0019] Figure 10 This is a cross-sectional view of the circuit board according to the second embodiment.

[0020] Figure 11This is a partial cross-sectional view showing the drive unit involved in other embodiments. Detailed Implementation

[0021] [Summary of Implementation Methods]

[0022] One embodiment may provide an electric work machine having at least one of the following features:

[0023] • Feature 1: It is configured as a motor that receives power from a power source for driving;

[0024] • Feature 2: A circuit board having a first circuit surface and a second circuit surface located on the opposite side of the first circuit surface;

[0025] Feature 3: A first semiconductor switch located on the first circuit surface, having a first metal surface and a first mounting surface, and electrically connected to a power supply and a motor;

[0026] Feature 4: The first mounting surface is located on the opposite side of the first metal surface and faces the first circuit surface;

[0027] Feature 5: A metal plate having a first plate surface that is joined to the first metal surface and a second plate surface located on the opposite side of the first plate surface;

[0028] Feature 6: A heat dissipation component that is in direct or indirect contact with the second plate surface;

[0029] Feature 7: An externally threaded component that securely connects the heat dissipation component and the metal plate.

[0030] According to the electric operating machine having at least features 1 to 7, heat generated by the first semiconductor switch is dissipated to the outside via a metal plate and a heat dissipation component. By placing the metal plate between the first semiconductor switch and the heat dissipation component, the heat dissipation path can be enhanced. Furthermore, the heat dissipation component and the metal plate are fastened together using an external threaded component, thereby improving the tightness of contact between the heat dissipation component and the metal plate. As a result, heat can be effectively transferred from the metal plate to the heat dissipation component. Therefore, the heat dissipation efficiency of the first semiconductor switch can be improved.

[0031] In addition to having at least one of features 1 to 7, or alternatively, a certain implementation may also have the following features:

[0032] Feature 8: The heat dissipation component has a through hole for the insertion of an external threaded component;

[0033] Feature 9: The metal plate has internal threads that engage with the external threaded components.

[0034] According to the electric working machine having at least features 1 to 9, by screwing the internal and external threads formed on the metal plate, the tightness of the contact between the heat dissipation component and the metal plate can be improved, thereby enabling heat to be effectively transferred from the metal plate to the heat dissipation component. Furthermore, by having internal threads on the metal plate, the number of components in the electric working machine can be reduced.

[0035] In addition to having at least one of features 1 to 9, or alternatively, a certain implementation may also have the following features:

[0036] Feature 10: A conductive elastic component disposed between the first circuit surface and the heat dissipation component.

[0037] According to the electric working machine having at least features 1 to 7, 10, by distributing an elastic member between the first circuit surface and the heat dissipation member, the elastic member can absorb the assembly tolerances of the first semiconductor switch, the metal plate, and the heat dissipation member assembled on the circuit board. Furthermore, the elastic member electrically connects the circuit board and the heat dissipation member. Therefore, the accumulation of static electricity on the circuit board can be suppressed, resulting in the suppression of local voltage rises on the circuit board due to static electricity, and ultimately, damage to electronic components on the circuit board due to electrostatic discharge can be suppressed.

[0038] In addition to having at least one of features 1 to 10, or alternatively, a certain implementation may also have the following features:

[0039] Feature 11: Circuit components;

[0040] Feature 12: The metal plate has through holes;

[0041] Feature 13: The first semiconductor switch has a first height in a direction perpendicular to the circuit board;

[0042] Feature 14: The through hole of the board is aligned with the circuit component mounted on the first circuit surface, and the circuit component has a second height in the vertical direction that is greater than the first height.

[0043] According to the electric working machine having at least features 1 to 7 and 11 to 14, the metal plate has a through hole. Thus, a circuit component having a height greater than that of the first semiconductor switch can be mounted on the first circuit surface.

[0044] In addition to having at least one of features 1 to 14, or alternatively, a certain embodiment may also have the following features:

[0045] Feature 15: Circuit components mounted on the first circuit plane;

[0046] Feature 16: The first semiconductor switch has a first height in a direction perpendicular to the circuit board;

[0047] Feature 17: The circuit component has a second height in the vertical direction that is less than the first height.

[0048] According to an electric working machine having at least features 1 to 7 and 15 to 17, a circuit component having a height smaller than that of the first semiconductor switch can be mounted on the first circuit surface.

[0049] In addition to having at least one of features 1 to 17, or alternatively, a certain embodiment may also have the following features:

[0050] Feature 18: The elastic component is a leaf spring.

[0051] According to an electric working machine having at least features 1 to 7, 10, and 18, an elastic member can be made to be in close contact with a circuit board and a heat dissipation member. Furthermore, static electricity generated on the circuit board can be appropriately discharged to the heat dissipation member via the elastic member.

[0052] In addition to having at least one of features 1 to 18, or alternatively, a certain embodiment may also have the following features:

[0053] Feature 19: The second semiconductor switch is located on the first circuit surface, and unlike the first semiconductor switch, it has a second metal surface and a second mounting surface, and is electrically connected to the power supply and the motor. The second mounting surface is located on the opposite side of the second metal surface and faces the first circuit surface.

[0054] Feature 20: The first plate surface is brazed to the first metal surface and the second metal surface;

[0055] Feature 21: The circuit component is disposed on the first circuit plane between the first semiconductor switch and the second semiconductor switch.

[0056] According to the electric working machine having features 1 to 7, 11 to 14, 19 to 21, or features 1 to 7, 15 to 17, 19 to 21, a circuit component can be mounted on the first circuit surface and between the first semiconductor switch and the second semiconductor switch.

[0057] In addition to having at least one of features 1 to 21, or alternatively, a certain implementation may also have the following features:

[0058] Feature 22: The circuit component is a thermistor.

[0059] According to an electric working machine equipped with features 1-7, 11-14, 19-22, or features 1-7, 15-17, 19-22, a thermistor can be mounted between the first semiconductor switch and the second semiconductor switch. Therefore, the temperature of the first semiconductor switch and the second semiconductor switch can be detected with high precision.

[0060] In addition to having at least one of features 1 to 22, or alternatively, a certain embodiment may also have the following features:

[0061] Feature 23: The heat dissipation component includes multiple heat sinks.

[0062] According to the electric working machine with features 1 to 7 and 23, the heat dissipation efficiency of the first semiconductor switch can be further improved.

[0063] At least one of the first semiconductor switch and the second semiconductor switch includes a surface mount package, more specifically including a top surface cooled package and a double-sided cooled package, but is not limited thereto.

[0064] Examples of top-side cooling packages include, but are not limited to, TO-Leaded Top-side cooling (TOLT) packages. Examples of double-side cooling packages include, but are not limited to, Double-side-cooling Small Outline Package (DSOP). Examples of the first and second semiconductor switches include, but are not limited to, metal-oxide-semiconductor field-effect transistors (MOSFETs), junction field-effect transistors (JFETs), insulated-gate bipolar transistors (IGBTs), bipolar transistors, solid-state relays (SSRs), and thyristors.

[0065] Examples of electric work machines include: various electrical equipment used in amateur woodworking, manufacturing, gardening, construction, and other work sites. Specifically, this includes: power tools for stonemasonry, metalworking, and woodworking; gardening work machines; and tools for preparing the work site environment. More specifically, this includes: electric blowers, electric hammers, electric hammer drills, electric drills, electric screwdrivers, electric wrenches, electric grinders, electric polishers, electric circular saws, electric reciprocating saws, electric wire saws, electric cutting tools, electric chainsaws, electric planers, electric nail machines (including riveting machines), electric lawn mowers, electric lawn trimmers, electric hedge trimmers, electric lawn mowers, electric cleaners, electric sprayers, electric spreaders, electric dust collectors, electric bicycles (or e-bikes), and battery-powered handcarts, but is not limited to these.

[0066] One embodiment may provide a method for assembling a drive unit for driving a motor of an electric work machine, having at least any one of the following features:

[0067] Feature 24: The semiconductor switch of the driving unit is mounted on the circuit board of the driving unit;

[0068] Feature 25: The semiconductor switch has a mounting surface and a metal surface on the opposite side of the mounting surface, and the mounting surface is opposite to the circuit board;

[0069] Feature 26: To bond the first surface of the metal plate to the metal surface;

[0070] Feature 27: The heat dissipation component is in direct or indirect contact with the second plate surface located on the opposite side of the first plate surface;

[0071] Feature 28: The heat dissipation components and the metal plate are fastened together using screws.

[0072] According to the method having at least features 24 to 28, the heat dissipation efficiency of semiconductor switches can be improved.

[0073] In one embodiment, features 1 to 28 described above can also be combined in any combination.

[0074] In one embodiment, any one of the features 1 to 28 described above may be removed.

[0075] [Specific exemplary implementation methods]

[0076] The following describes a specific exemplary embodiment. This specific exemplary embodiment provides an electric work machine 1 in the form of an electric chainsaw. An electric chainsaw is a type of gardening tool. However, such an electric work machine 1 is merely an example, and the present invention can be applied to all types of electric work machines.

[0077] (1. First embodiment)

[0078] <1-1. Composition of Electric Working Machines>

[0079] like Figure 1 As shown, the electric work machine 1 includes a housing 2. The housing 2 is formed of synthetic resin. The housing 2 houses the motor 20 inside. The housing 2 also houses the drive unit 25 inside. The drive unit 25 includes: a circuit board 11 described later, and a drive circuit 21 mounted on the circuit board 11.

[0080] The terms "up," "down," "front," "back," "left," and "right" used in the following description are merely for the purpose of facilitating understanding of the structure of the electric work machine 1 and its components, and are not intended to limit the orientation of the electric work machine 1 and its components. The electric work machine 1 and its components can be configured in all directions.

[0081] The electric work machine 1 includes a guide rod 9. The guide rod 9 is a plate-shaped component. The guide rod 9 protrudes from the outer casing 2 toward the front of the electric work machine 1.

[0082] The electric work machine 1 includes a chainsaw 9a as a tool. The chainsaw 9a includes multiple interconnected blades. The chainsaw 9a is detachably mounted on the periphery of the guide rod 9. The chainsaw 9a is connected to the rotor shaft (not shown) of the motor 20 via a power transmission mechanism (not shown). The power transmission mechanism includes a sprocket (not shown) configured for mounting the chainsaw 9a.

[0083] Therefore, by driving the motor 20, the chainsaw 9a moves around the periphery of the guide rod 9. The electric workpiece 1 can cut the workpiece by means of the moving chainsaw 9a.

[0084] The electric work machine 1 includes a battery assembly 5. In this embodiment, the battery assembly 5 protrudes upward from the rear of the outer casing 2. A battery pack 12 is detachably mounted to the battery assembly 5. The battery pack 12 can be mounted on the rear end face of the battery assembly 5. The battery pack 12 includes a secondary battery. In this embodiment, although the secondary battery is a lithium-ion battery, it is not limited to lithium-ion batteries. By being mounted to the battery assembly 5, the battery pack 12 can supply DC power to the electric work machine 1.

[0085] In other embodiments, the electric work machine 1 may replace the battery assembly 5 with a power cord. The electric work machine 1 may also receive AC power from a commercial power source or other AC power source via the power cord. The AC power received from the AC power source may also be converted into DC power or AC power with different characteristics within the electric work machine 1.

[0086] The electric work machine 1 is equipped with a hand guard 4. The hand guard 4 protrudes upward from the front of the outer casing 2.

[0087] The electric work machine 1 has a side handle 3A and a top handle 3B behind the hand guard 4. Either the side handle 3A or the top handle 3B may be omitted. The side handle 3A and the top handle 3B are made of synthetic resin.

[0088] The side handle 3A is a tubular component. The side handle 3A protrudes from the left side of the housing 2 toward the left. Therefore, the user of the electric work machine 1 can hold the side handle 3A with their left hand from the rear of the electric work machine 1.

[0089] The top handle 3B protrudes upward from the upper part of the housing 2. The rear end of the top handle 3B is connected to the battery assembly 5, thereby forming a space between the top handle 3B and the housing 2. Thus, the user can insert their fingers into this space to hold the top handle 3B.

[0090] The electric work machine 1 has a trigger switch 7 located below the top handle 3B. The trigger switch 7 is operated by the user (e.g., pulled) to drive the motor 20. When the trigger switch 7 is pulled upwards by the user, the motor 20 is driven. Conversely, when the operation of the trigger switch 7 is released, the drive of the motor 20 is stopped.

[0091] The electric work machine 1 has a trigger locking stop 8 above the top handle 3B. When the user presses the trigger locking stop 8 downwards, the lock of the trigger switch 7 is released.

[0092] <1-2. Control Unit>

[0093] like Figure 2 As shown, the electric work machine 1 has a control unit 10.

[0094] The control unit 10 receives DC power from the battery 12a in the battery pack 12 to control the motor 20 by driving or stopping the chainsaw 9a. In this embodiment, the motor 20 is a 3-phase brushless DC motor. In other embodiments, the motor 20 may also be a single-phase brushless DC motor, a 2-phase brushless DC motor, a 4-phase or higher brushless DC motor, a brushed motor, an AC motor, or a stepper motor.

[0095] The control unit 10 includes: a drive unit 25 with a drive circuit 21, a gate circuit 22, a control circuit 23, and a regulator 24.

[0096] The drive circuit 21 is configured to: (i) receive DC motor current from the battery 12a; (ii) convert the received DC motor current into three-phase AC motor current (i.e., U-phase, V-phase, and W-phase motor current); and (iii) supply the three-phase AC motor current to the three-phase windings (not shown) of the motor 20. Specifically, the drive circuit 21 is a three-phase full-bridge inverter circuit equipped with semiconductor switches Q1 to Q6 (first to sixth phases). In other embodiments, the drive circuit 21 may be a single-phase, two-phase, or four-phase or more full-bridge inverter circuit, or a half-bridge inverter circuit.

[0097] Specifically, the first to sixth semiconductor switches Q1 to Q6 are FETs. More specifically, the first to sixth semiconductor switches Q1 to Q6 are N-channel MOSFETs. In other embodiments, at least one of the first to sixth semiconductor switches Q1 to Q6 may also be: a P-channel MOSFET, a JFET, an IGBT, a bipolar transistor, an SSR, or a thyristor.

[0098] In drive circuit 21, semiconductor switches Q1 to Q3 (first to third) are high-side switches. These switches are connected to terminals U, V, and W of motor 20 and power line Lp. Power line Lp is connected to the positive terminal of battery 12a. In drive circuit 21, semiconductor switches Q4 to Q6 (fourth to sixth) are low-side switches. These switches are connected to terminals U, V, and W of motor 20 and ground line Ln. Ground line Ln is connected to the negative terminal of battery 12a.

[0099] Semiconductor switches Q1 to Q6, numbered 1 to 6, each have gate terminals 41, 51, 61, 71, 81, and 91; drain terminals 42, 52, 62, 72, 82, and 92; and source terminals 43, 53, 63, 73, 83, and 93. The gate terminals 41, 51, 61, 71, 81, and 91 of semiconductor switches Q1 to Q6 are connected to gate circuit 22. The drain terminals 42, 52, and 62 of semiconductor switches Q1 to Q3, numbered 1 to 3, are connected to power line Lp. The source terminals 73, 83, and 93 of semiconductor switches Q4 to Q6, numbered 4 to 6, are connected to ground line Ln. The source terminal 43 of semiconductor switch Q1 is connected to the drain terminal 72 of semiconductor switch Q4 and the U phase of motor 20. The source terminal 53 of the second semiconductor switch Q2 is connected to the drain terminal 82 of the fifth semiconductor switch Q5 and the V phase of the motor 20. The source terminal 63 of the third semiconductor switch Q3 is connected to the drain terminal 92 of the sixth semiconductor switch Q6 and the W phase of the motor 20.

[0100] Gate circuit 22 turns semiconductor switches Q1 to Q6 (number 1 to 6) on or off according to the control signal output from control circuit 23, supplying three-phase AC motor current to the three-phase windings of motor 20. As a result, motor 20 rotates.

[0101] The control circuit 23 includes a microcomputer (or microcontroller, or microprocessor) not shown. In other embodiments, the control circuit 23 may include an additional microcomputer. Furthermore, in other embodiments, instead of a microcomputer, or in addition to the above, the control circuit 23 may also include: a graphics processing unit (GPU), wiring logic, an application-specific integrated circuit (ASIC), an application-specific general-purpose component (ASSP), a programmable logic device (PLD) (e.g., a field-programmable gate array (FPGA), etc.), discrete electronic components, and / or combinations thereof.

[0102] The regulator 24 is configured to: (i) receive DC power from the battery 12a, and (ii) generate a power supply voltage Vcc. The power supply voltage Vcc is supplied to the internal circuitry of the control unit 10, which includes the control circuit 23.

[0103] The control unit 10 also includes a load switch Q7 and a bootstrap circuit 26. The load switch Q7 is configured between the battery 12a and the drive circuit 21 on the power line Lp to protect the drive circuit 21 and / or the motor 20. The load switch Q7 is a semiconductor switch. Specifically, the load switch Q7 is an N-channel MOSFET. In other embodiments, the load switch Q7 may also be a P-channel MOSFET, JFET, IGBT, bipolar transistor, or SSR. Furthermore, in other embodiments, the load switch Q7 may also be a mechanical relay. Moreover, the gate terminal of the load switch Q7 is connected to the control circuit 23 via the bootstrap circuit 26. When the motor 20 is allowed to drive, the load switch Q7 remains in the ON state. The motor current flowing to the load switch Q7 may be greater than the motor current flowing to the first to sixth semiconductor switches Q1 to Q6, respectively. The voltage applied to the load switch Q7 may be greater than the voltage applied to the first to sixth semiconductor switches Q1 to Q6. Therefore, the rated voltage and rated current of the load switch Q7 are higher than the rated voltage and rated current of the first to sixth semiconductor switches Q1 to Q6, respectively.

[0104] The drive circuit 21 includes a first thermistor 27 and a second thermistor 29. The first thermistor 27 is positioned near the first to third semiconductor switches Q1 to Q3 and measures the temperature of the switches. The first thermistor 27 sends a temperature detection signal indicating the measured temperature to the control circuit 23. The second thermistor 29 is positioned near the fourth to sixth semiconductor switches Q4 to Q6 and measures the temperature of the switches. The second thermistor 29 sends a temperature detection signal indicating the measured temperature to the control circuit 23.

[0105] <1-3. Drive Unit>

[0106] <1-3-1. Example>

[0107] Reference Figure 3 as well as Figure 4 The driving unit 25 is described below. The driving unit 25 includes: a circuit board 11, a driving circuit 21 mounted on the circuit board 11, four elastic members 35, two metal plates 100, two heat dissipation members 200, and four externally threaded members 400. Furthermore, Figure 3 The two metal plates 100, two heat sinks 200, and four external threaded components 400 are transparently displayed. In fact, the driving circuit 21 on the circuit board 11 is covered by the two metal plates 100 and the two heat sinks 200.

[0108] The circuit board 11 is a printed circuit board (PCB). The circuit board 11 has a rectangular planar shape. In other embodiments, the circuit board 11 may also have a planar shape other than a rectangle. The circuit board 11 includes a first circuit surface 11A and a second circuit surface 11B. The second circuit surface 11B is located on the opposite side of the first circuit surface 11A.

[0109] The drive circuit 21 includes: first to sixth semiconductor switches Q1 to Q6, first and second thermistors 27 and 29, U-phase terminal 45, V-phase terminal 55, and W-phase terminal 65.

[0110] Semiconductor switches Q1 to Q6 (numbers 1-6) are surface-mount type. That is, semiconductor switches Q1 to Q6 have surface-mount packages. More specifically, semiconductor switches Q1 to Q6 have top surface-cooled packages, and more specifically, they have TOLT packages. Semiconductor switches Q1 to Q6 are of the same type, but are not limited to the same type. Semiconductor switches Q1 to Q6 are disposed on the first circuit surface 11A. Semiconductor switches Q1 to Q3 (numbers 1-3) are arranged in a row along the left-right direction in front of the first circuit surface 11A, and semiconductor switches Q4 to Q6 (numbers 4-6) are arranged in a row along the left-right direction behind the first circuit surface 11A. In addition, semiconductor switches Q1 and Q4 (numbers 1 and 4) are arranged along the front-back direction. Semiconductor switches Q2 and Q5 (numbers 2 and 5) are arranged along the front-back direction. Semiconductor switches Q3 and Q6 (numbers 3 and 6) are arranged along the front-back direction.

[0111] Semiconductor switches Q1 to Q6 are each packaged in a plate shape, comprising: (i) one corresponding end among first ends 46A, 56A, 66A, 76A, 86A, and 96A; and (ii) one corresponding end among second ends 46B, 56B, 66B, 76B, 86B, and 96B, respectively, opposite to the first ends 46A, 56A, 66A, 76A, 86A, and 96A. Drain terminals 42, 52, 62, 72, 82, and 92 of semiconductor switches Q1 to Q6 protrude from the first ends 46A, 56A, 66A, 76A, 86A, and 96A, respectively. The gate terminals 41, 51, 61, 71, 81, and 91 of the first to sixth semiconductor switches Q1 to Q6 protrude from the second end 46B, 56B, 66B, 76B, 86B, and 96B, respectively. The source terminals 43, 53, 63, 73, 83, and 93 of the first to sixth semiconductor switches Q1 to Q6 protrude from the second end 46B, 56B, 66B, 76B, 86B, and 96B, respectively.

[0112] The first semiconductor switch Q1 includes: (i) a first metal surface 46, and (ii) a first mounting surface 48 located on the opposite side of the first metal surface 46. The second semiconductor switch Q2 includes: (i) a second metal surface 56, and (ii) a second mounting surface 58 located on the opposite side of the second metal surface 56. The third semiconductor switch Q3 includes: (i) a third metal surface 66, and (ii) a third mounting surface 68 located on the opposite side of the third metal surface 66. The fourth semiconductor switch Q4 includes: (i) a fourth metal surface 76, and (ii) a fourth mounting surface 78 located on the opposite side of the fourth metal surface 76. Figure 3 , 4 (Not shown in the figure). The fifth semiconductor switch Q5 includes: (i) a fifth metal surface 86, and (ii) a fifth mounting surface 88 located on the opposite side of the fifth metal surface 86. Figure 3 , 4 (Not shown in the figure). The sixth semiconductor switch Q6 includes: (i) a sixth metal surface 96, and (ii) a sixth mounting surface 98 located on the opposite side of the sixth metal surface 96. Figure 3 , 4 (Not shown in the image).

[0113] The first to sixth metal surfaces 46, 56, 66, 76, 86, and 96 each include a metal plate (metal pad) that is surface-bonded to the package of one of the first to sixth semiconductor switches Q1 to Q6. The metal plate may be made of aluminum, copper, silver, or gold, or be made of aluminum, copper, silver, or gold. The first to sixth semiconductor switches Q1 to Q6 are mounted on the first circuit surface 11A with the first to sixth mounting surfaces 48, 58, 68, 78, 88, and 98 facing the first circuit surface 11A. The first to sixth mounting surfaces 48, 58, 68, 78, 88, and 98 are soldered to the first circuit surface 11A.

[0114] Semiconductor switches Q1 to Q6 are arranged on the first circuit surface 11A with their first ends 46A, 56A, 66A, 76A, 86A, and 96A as the front side and their second ends 46B, 56B, 66B, 76B, 86B, and 96B as the rear side. Therefore, the source terminal 43 of the first semiconductor switch Q1 is opposite to the drain terminal 72 of the fourth semiconductor switch Q4. The source terminal 53 of the second semiconductor switch Q2 is opposite to the drain terminal 82 of the fifth semiconductor switch Q5. The source terminal 63 of the third semiconductor switch Q3 is opposite to the drain terminal 92 of the sixth semiconductor switch Q6. The source terminals 43, 53, and 63 are electrically connected to the drain terminals 72, 82, and 92 via printed wiring (or lines or conductive rails) and / or vias (not shown) on the first circuit surface 11A. The printed wiring is formed of a metal foil with high conductivity. More specifically, the metal foil comprises copper, silver, or gold. The through-holes are filled with metal or plated with metal. This metal comprises copper, silver, or gold.

[0115] A first thermistor 27 is disposed on the first circuit plane 11A between a first semiconductor switch Q1 and a second semiconductor switch Q2. A second thermistor 29 is disposed on the first circuit plane 11A between a fourth semiconductor switch Q4 and a fifth semiconductor switch Q5. In this embodiment, the first to sixth semiconductor switches Q1 to Q6 each have a first height H1. The first and second thermistors 27 and 29 each have a second height H2. The first height H1 and the second height H2 correspond to the lengths in the vertical direction, and the second height H2 is greater than the first height H1.

[0116] The U-phase terminal 45 is disposed on the first circuit surface 11A between the first semiconductor switch Q1 and the fourth semiconductor switch Q4. The source terminal 43 of the first semiconductor switch Q1, the drain terminal 72 of the fourth semiconductor switch Q4, and the U-phase terminal 45 are electrically connected to each other. The drain terminal 42 of the first semiconductor switch Q1 is electrically connected to the power line Lp via printed wiring (not shown) and / or vias (not shown) on the first circuit surface 11A. The source terminal 73 of the fourth semiconductor switch Q4 is electrically connected to the ground line Ln via printed wiring (not shown) and / or vias (not shown) on the first circuit surface 11A.

[0117] The V-phase terminal 55 is disposed on the first circuit surface 11A between the second semiconductor switch Q2 and the fifth semiconductor switch Q5. The source terminal 53 of the second semiconductor switch Q2, the drain terminal 82 of the fifth semiconductor switch Q5, and the V-phase terminal 55 are electrically connected to each other. The drain terminal 52 of the second semiconductor switch Q2 is electrically connected to the power line Lp via printed wiring (not shown) and vias (not shown) on the first circuit surface 11A. The source terminal 83 of the fifth semiconductor switch Q5 is electrically connected to the ground line Ln via printed wiring (not shown) and / or vias (not shown) on the first circuit surface 11A.

[0118] The W-phase terminal 65 is disposed on the first circuit surface 11A between the third semiconductor switch Q3 and the sixth semiconductor switch Q6. The source terminal 63 of the third semiconductor switch Q3, the drain terminal 92 of the sixth semiconductor switch Q6, and the W-phase terminal 65 are electrically connected to each other. The drain terminal 62 of the third semiconductor switch Q3 is electrically connected to the power line Lp via printed wiring (not shown) and vias on the first circuit surface 11A. The source terminal 93 of the sixth semiconductor switch Q6 is electrically connected to the ground line Ln via printed wiring (not shown) and / or vias (not shown) on the first circuit surface 11A.

[0119] The elastic member 35 is conductive. Specifically, the elastic member 35 is a leaf spring made of metal such as copper or aluminum. More specifically, the elastic member 35 has a cross-section that is Z-shaped but not limited to a Z-shape. In other embodiments, the elastic member 35 may also be a metal helical spring. Alternatively, the elastic member 35 may also be a sponge with its surface covered by a conductive material.

[0120] The elastic members 35 are respectively disposed on the first circuit surface 11A to the right of the first semiconductor switch Q1, to the left of the third semiconductor switch Q3, to the right of the fourth semiconductor switch Q4, and to the left of the sixth semiconductor switch Q6. The elastic members 35 each have: (i) a first member surface 35A, and (ii) a second member surface 35B located opposite to the first member surface 35A. The first member surface 35A is bonded to the first circuit surface 11A by solder or the like.

[0121] The metal plates 100 are rectangular plate-shaped components. These metal plates 100 are arranged above the first circuit surface 11A with their long sides aligned horizontally. One metal plate 100 is configured to cover the upper surfaces of three high-side switches (i.e., the first to third semiconductor switches Q1 to Q3). The upper surfaces of the three high-side switches include metal surfaces 46, 56, and 66 (first to third sides). The other metal plate 100 is configured to cover the upper surfaces of three low-side switches (i.e., the fourth to sixth semiconductor switches Q4 to Q6). The upper surfaces of the three low-side switches include metal surfaces 76, 86, and 96 (fourth to sixth sides). The four elastic members 35 are not covered by these metal plates 100. These metal plates 100 are components that improve the heat dissipation efficiency of the heat generated by the first to sixth semiconductor switches Q1 to Q6. Furthermore, Figure 4 The cross-section along the high-side switch is shown, but the structure around the low-side switch is the same as that around the high-side switch. Therefore, the structure around the high-side switch will be described below, while the description of the structure around the low-side switch will be omitted.

[0122] The metal plate 100 includes: (i) a first plate surface 100A, and (ii) a second plate surface 100B located opposite to the first plate surface 100A. The first plate surface 100A is bonded to the first to third metal surfaces 46, 56, and 66 by means of solder. In other embodiments, the first plate surface 100A may also be bonded to the first to third metal surfaces 46, 56, and 66 by means of an adhesive with relatively high thermal conductivity. Examples of adhesives with relatively high thermal conductivity include: silicone and epoxy resin.

[0123] The metal plate 100 includes: a metal base 140, an insulating layer 130, first to third metal foils 111 to 113, a right insulating portion 121, first and second insulating portions 122 and 123, and a left insulating portion 124. The metal base 140 is an aluminum metal plate. That is, the metal base 140 is a metal plate with high thermal conductivity and excellent heat dissipation. In other embodiments, the metal base 140 can be a metal plate formed of other metals such as copper. The metal base 140 can also be any metal plate with excellent heat dissipation. The upper surface of the metal base 140 corresponds to the second plate surface 100B.

[0124] The insulating layer 130 is bonded to the lower surface of the metal base 140. More specifically, the upper surface of the insulating layer 130 is bonded to the lower surface of the metal base 140 using an adhesive or the like. The insulating layer 130 comprises, or is formed of, a material with excellent insulation and heat dissipation properties. Examples of such materials include, for example, silicon and epoxy resin.

[0125] The first to third metal foils 111 to 113, the right insulating portion 121, the first and second insulating portions 122 and 123, and the left insulating portion 124 are bonded to the lower surface of the insulating layer 130. The first to third metal foils 111 to 113, the right insulating portion 121, the first and second insulating portions 122 and 123, and the left insulating portion 124 form the first plate surface 100A. In other words, the first to third metal foils 111 to 113, the right insulating portion 121, the first and second insulating portions 122 and 123, and the left insulating portion 124 are included in the first plate surface 100A.

[0126] The first to third metal foils 111 to 113 are square metal foils (sheets), specifically copper foils. The first to third metal foils 111 to 113 each have a size equivalent to that of the first to third metal surfaces 46, 56, and 66. In other embodiments, the first to third metal foils 111 to 113 may also be other metal foils such as silver or gold foil.

[0127] The first metal foil 111 is disposed on the first plate surface 100A opposite to the first metal surface 46. The second metal foil 112 is disposed on the first plate surface 100A opposite to the second metal surface 56. The third metal foil 113 is disposed on the first plate surface 100A opposite to the third metal surface 66. That is, the first to third metal foils 111 to 113 are arranged in the left-right direction with the same spacing as the first to third semiconductor switches Q1 to Q3.

[0128] The first metal foil 111 is bonded to the first metal surface 46 using solder 101. The second metal foil 112 is bonded to the second metal surface 56 using solder 102. The third metal foil 113 is bonded to the third metal surface 66 using solder 103. However, current does not flow between the first to third metal foils 111 to 113 and the first to third metal surfaces 46, 56, and 66. The first to third metal foils 111 to 113 are disposed on the first board surface 100A for brazing the metal plate 100 to the first to third semiconductor switches Q1 to Q3. Depending on the type of metal contained in the metal plate 100, it is difficult to braze the first to third metal surfaces 46, 56, and 66 to the metal plate 100. In particular, when the metal contained in the metal plate 100 is aluminum, it is difficult to achieve brazing. The first plate 100A includes the first to third metal foils 111 to 113, and the first to third metal surfaces 46, 56, and 66 can be brazed to the first plate 100A.

[0129] Solders 101 to 103 are alloys containing lead and / or tin, and have higher thermal conductivity than resins. The first to third semiconductor switches Q1 to Q3 are bonded to the metal plate 100 using solders 101 to 103, which have high thermal conductivity. Therefore, compared to bonding the first to third semiconductor switches Q1 to Q3 to the metal plate 100 using resins or the like, the heat dissipation efficiency of the heat dissipation path from the first to third semiconductor switches Q1 to Q3 toward the metal plate 100 is improved.

[0130] In other embodiments, the first to third semiconductor switches Q1 to Q3 may also be bonded to the metal plate 100 by means of a thermally conductive material (TIM), and the first to third metal foils 111 to 113 are removed from the metal plate 100. Examples of TIM include thermal paste, thermal adhesive, thermal sheet, thermally conductive compound, and thermal gel.

[0131] The first and second insulating portions 122 and 123, the right insulating portion 121, and the left insulating portion 124 are solder resist (or solder mask) applied to the insulating layer 130. In other embodiments, the first and second insulating portions 122 and 123, the right insulating portion 121, and the left insulating portion 124 may be formed of an insulating material or may contain an insulating material. Examples of insulating materials include silicon and epoxy resin.

[0132] The first insulating portion 122 is disposed between the first metal foil 111 and the second metal foil 112. The second insulating portion 123 is disposed between the second metal foil 112 and the third metal foil 113. The right insulating portion 121 is disposed to the right of the first metal foil 111. The left insulating portion 124 is disposed to the left of the third metal foil 113.

[0133] A through-hole 160 is formed in the metal plate 100, through which the first insulating portion 122, the insulating layer 130 above it, and the metal base 140 pass. The through-hole 160 is opposite to a first thermistor 27 mounted on the first circuit surface 11A. Since the second height H2 is greater than the first height H1, the first thermistor 27 is not housed between the first circuit surface 11A and the first insulating portion 122. Thus, the through-hole 160 is formed in the metal plate 100. A portion of the first thermistor 27 is housed within the through-hole 160.

[0134] Two internal threads 150 are formed on the metal plate 100. Each internal thread 150 includes a helical thread. One internal thread 150 is formed on the inner surface of a through hole through which the right insulating portion 121, the insulating layer 130 above it, and the metal base 140 pass. The other internal thread 150 is formed on the inner surface of a through hole through which the left insulating portion 124, the insulating layer 130 above it, and the metal base 140 pass. In this embodiment, the internal threads 150 are formed on the inner surface of each through hole in the metal base 140. In other embodiments, either internal thread 150 may also be formed on the inner surface of the corresponding through hole in the metal base 140.

[0135] The second plate surface 100B is bonded to the bonding layer 300. The heat dissipation component 200 is in indirect contact with the second plate surface 100B via the bonding layer 300. The bonding layer 300 is formed by applying a material having (i) adhesion and (ii) a thermal conductivity higher than air onto the second plate surface 100B, or by attaching a sheet of such material to the second plate surface 100B. Specifically, the bonding layer 300 is formed of TIM, and more specifically, of a thermally conductive compound. Generally, the second plate surface 100B has minor irregularities. In addition, the bottom surface of the heat dissipation component 200 also has minor irregularities. The bonding layer 300 improves the heat dissipation efficiency of the heat dissipation path from the metal plate 100 to the heat dissipation component 200 by filling the gap between the second plate surface 100B and the bottom surface of the heat dissipation component 200. In other embodiments, the bonding layer 300 and the heat dissipation component 200 can be removed from the drive unit 25. If sufficient heat dissipation can be achieved with only the metal plate 100, the heat dissipation component 200 may not need to be connected to the metal plate 100.

[0136] In other embodiments, the sealing layer 300 can be removed from the drive unit 25, and the heat dissipation component 200 can be directly bonded to the second plate surface 100B (see reference). Figure 11 Alternatively, in other embodiments, the metal plate 100 and the bonding layer 300 may be removed from the drive unit 25. An insulating layer may also be formed on the bottom surface of the heat dissipation component 200, and three metal foils may be disposed on the insulating layer. Furthermore, the three metal foils may be brazed to the first to third metal surfaces 46, 56, and 66 of the first to third semiconductor switches Q1 to Q3.

[0137] The right and left ends of the heat sink 200 contact the second component surface 35B of one of the two elastic components 35. The heat sink 200 is not fixed to these second component surfaces 35B, but is supported by the elastic force of these elastic components 35. Therefore, the assembly tolerances of the first to third semiconductor switches Q1 to Q3, the metal plate 100, the sealing layer 300, and the heat sink 200 are absorbed by these elastic components 35.

[0138] Since the elastic members 35 are conductive, the circuit board 11 is electrically connected to the heat dissipation member 200. This suppresses the occurrence of static electricity on the circuit board 11. Consequently, local voltage rises on the circuit board 11 caused by static electricity are suppressed. Furthermore, damage to electronic components on the circuit board 11 due to electrostatic discharge is suppressed.

[0139] In other embodiments, the drive unit 25 may replace the two heat dissipation components 200 and instead include a single heat dissipation component covering the upper surfaces of the first to sixth semiconductor switches Q1 to Q6. The single heat dissipation component may be supported by a single elastic component or by three or more elastic components. The single elastic component or the three or more elastic components may each be configured similarly to the elastic component 35.

[0140] The heat dissipation component 200 is a heat sink made of metals such as aluminum or copper. For example... Figure 4 As shown, the heat dissipation component 200 includes: a base 210, a plurality of heat sinks 220, and a mounting portion 230. The base 210 is plate-shaped and is joined to the bonding layer 300 in a manner that is arranged substantially parallel to the circuit board 11 and the metal plate 100. Two through holes 250 are formed in the base 210. These through holes 250 are formed to be opposite (or arranged) to internal threads 150. The inner surface of each through hole 250 does not have threads, but has a smooth inner surface.

[0141] The plurality of heat sinks 220 are plate-shaped. The plurality of heat sinks 220 are connected to the base 210 with their long sides aligned along the front-back direction. The plurality of heat sinks 220 are arranged in the left-right direction. In other embodiments, the plurality of heat sinks 220 may also be arranged on the base 210 with their long sides facing left-right in the front-back direction. Furthermore, in other embodiments, the plurality of heat sinks 220 may each have other shapes such as a wave-shaped shape or a pointed shape.

[0142] The mounting portion 230 is plate-shaped and has a thickness greater than that of any of the heat sinks 220. The mounting portions 230 are connected to the right end of the base 210 along their long sides in the front-to-back direction. In other embodiments, the mounting portions 230 may also be connected to the left end of the base 210. Alternatively, in other embodiments, the mounting portions 230 may also be connected to the front or rear end of the base 210 along their long sides in the left-to-right direction.

[0143] The heat dissipation component 200 has a first contact surface 200a on the lower side of the base 210. The first contact surface 200a indirectly contacts the first to third semiconductor switches Q1 to Q3 via a metal plate 100 or the like.

[0144] The heat dissipation component 200 has a second contact surface 200b on the right end face of the mounting portion 230, which is different from the first contact surface 200a. The second contact surface 200b extends in a direction intersecting the first contact surface 200a. In this embodiment, the second contact surface 200b extends perpendicularly to the first contact surface 200a.

[0145] Refer again Figure 3 as well as Figure 4 The second contact surface 200b contacts the load switch Q7. The load switch Q7 is a plug-in type switch; that is, the load switch Q7 has a through-hole package. More specifically, the load switch Q7 is a radial lead type switch. Generally, semiconductor switches with through-hole packages have a rated voltage and rated current that are greater than those of semiconductor switches with surface mount packages. In this embodiment, to ensure higher reliability and / or higher durability, the load switch Q7 has a rated voltage and rated current that are greater than those of any one of the first to sixth semiconductor switches Q1 to Q6.

[0146] The load switch Q7 includes a main body 30. The main body 30 is cuboid in shape. The load switch Q7 is screwed to the mounting portion 230 with one outer surface of the main body 30 in contact with the second contact surface 200b of the mounting portion 230. In other embodiments, the load switch Q7 may also be fixed to the mounting portion 230 using a clip or the like with one outer surface of the main body 30 in contact with the second contact surface 200b. Alternatively, in other embodiments, one outer surface of the main body 30 may be bonded to the second contact surface 200b by means of a clamping member 700 such as a thin adhesive sheet.

[0147] The heat generated by the first to third semiconductor switches Q1 to Q3 is transferred to the heat sink 200 via the metal plate 100 and is dissipated through the heat sink 200. The heat generated by the load switch Q7 is directly transferred to the heat sink 200 and is dissipated through the heat sink 200.

[0148] The load switch Q7 includes a first lead 31, a second lead 32, and a third lead 33. The first lead 31 is connected to the gate terminal of the load switch Q7. The second lead 32 is connected to the drain terminal of the load switch Q7. The third lead 33 is connected to the source terminal of the load switch Q7. Through-holes 131, 132, and 133 are formed on the circuit board 11. The through-holes 131, 132, and 133 penetrate the circuit board 11 along its thickness. The first to third leads 31 to 33 protrude downward from the main body 30 and extend downward. The first to third leads 31 to 33 (i) are inserted into the through-holes 131, 132, and 133, and (ii) are electrically connected to printed wiring (not shown) on the first circuit surface 11A via the through-holes 131, 132, and 133.

[0149] Each external threaded component 400 has a threaded portion 410. The threaded portion 410 is a helical thread formed on the side of the cylinder of the corresponding external threaded component 400. The threaded portion 410 is formed at a position corresponding to the internal thread 150 on the external threaded component 400 that is inserted into the through hole 250. The external threaded components 400 are inserted into the corresponding through holes 250, and the corresponding threaded portions 410 engage with the corresponding internal threads 150. Through the engagement of these threaded portions 410 and these internal threads 150, the heat dissipation component 200 is securely fixed to the metal plate 100. Furthermore, the tightness of the contact between the heat dissipation component 200, the sealing layer 300, and the metal plate 100 is improved, thereby increasing the heat dissipation efficiency from the metal plate 100 towards the heat dissipation component 200.

[0150] In other embodiments, instead of the internal thread 150 formed on the metal plate 100, the drive unit 25 may also include two nuts (internal threads) (i.e., the drive unit 25 may also include a total of four nuts). Two external threaded parts 400 may also engage with the two nuts on the underside of the right insulating portion 121 and the left insulating portion 124.

[0151] After assembling the first to sixth semiconductor switches Q1 to Q6, the two metal plates 100, and the two heat sinks 200 onto the circuit board 11, the drive unit 25 is molded from resin. The resin-molded drive unit 25 is housed in the housing 2. In other embodiments, the drive unit 25 may also be housed in a housing after assembling the first to sixth semiconductor switches Q1 to Q6, the two metal plates 100, and the two heat sinks 200 onto the circuit board 11. This housing is housed in the outer casing 2.

[0152] <1-3-2. Variation>

[0153] Reference Figure 5This section describes a modified version of the drive unit 25. The modified version differs from the previous embodiment in that the first thermistor 27 has a third height H3 instead of a second height H2. Furthermore, the modified version differs from the previous embodiment in that a through-hole 160 is not formed in the metal plate 100. The third height H3 is smaller than the first height H1. Therefore, in this modified version, the first thermistor 27 is housed between the first circuit surface 11A and the first insulating portion 122, and thus, a through-hole 160 is not formed in the metal plate 100.

[0154] <1-3-3. Effect>

[0155] According to the first embodiment described in detail above, the following effects can be achieved.

[0156] (1) The heat generated by the first semiconductor switch Q1 is dissipated to the outside via the metal plate 100 and the heat sink 200. By placing the metal plate 100 between the first semiconductor switch Q1 and the heat sink 200, the heat dissipation path can be enhanced. Furthermore, the heat sink 200 and the metal plate 100 are fastened together by the external threaded member 400, which improves the tightness of contact between the heat sink 200 and the metal plate 100. Therefore, heat can be effectively transferred from the metal plate 100 to the heat sink 200. Thus, the heat dissipation efficiency of the first semiconductor switch Q1 can be improved.

[0157] (2) By screwing the two internal threads 150 formed on the metal plate 100 into the two threaded portions 410, the tightness of the contact between the heat dissipation component 200 and the metal plate 100 can be improved, thereby enabling heat to be effectively transferred from the metal plate 100 to the heat dissipation component 200. In addition, by forming two internal threads 150 on the metal plate 100, the number of components in the drive unit 25 can be reduced.

[0158] (3) At least one elastic member 35 is disposed between the first circuit surface 11A and the heat dissipation member 200. Accordingly, at least one elastic member 35 can be used to absorb the assembly tolerance of the first to third semiconductor switches Q1 to Q3, the metal plate 100 and the heat dissipation member 200 assembled on the circuit board 11.

[0159] (4) At least one elastic member 35 electrically connects the circuit board 11 to the heat dissipation member 200. Accordingly, when static electricity is generated on the circuit board 11, the static electricity is discharged to the heat dissipation member 200 via at least one elastic member 35. Therefore, it is possible to suppress the local voltage rise on the circuit board 11 caused by static electricity. Furthermore, it is possible to suppress electrostatic damage to the electronic components on the circuit board 11.

[0160] (5) Since a through hole 160 is formed in the metal plate 100, a first thermistor 27 having a second height H2 that is larger than the first height H1 can be mounted on the first circuit surface 11A.

[0161] (6) Even if the metal plate 100 does not have a through hole 160, the first thermistor 27 with a third height H3 smaller than the first height H1 can be mounted on the first circuit surface 11A.

[0162] (2. Second implementation method)

[0163] <2-1. Differences from the first embodiment>

[0164] Since the basic structure of the second embodiment is the same as that of the first embodiment, the differences will be described below. Furthermore, the same reference numerals as in the first embodiment indicate the same configurations; please refer to the preceding description.

[0165] According to the driving unit 25 of the first embodiment described above, semiconductor switches Q1 to Q6 are mounted on the first circuit surface 11A. In contrast, the driving unit 25 of the second embodiment differs from that of the first embodiment in that a low-side switch (i.e., semiconductor switches Q4 to Q6, 4th to 6th) is mounted on the second circuit surface 11B. That is, in the second embodiment, the electronic components of the driving circuit 21 are mounted on both surfaces of the circuit board 11. Therefore, the circuit board 11 of the second embodiment is smaller than that of the circuit board 11 of the first embodiment.

[0166] Furthermore, the driving unit 25 according to the second embodiment differs from the driving unit 25 according to the first embodiment in that: (i) it has three metal parts 600, first to third printed wiring 511 to 513, and fourth to sixth printed wiring 521 to 523, and (ii) instead of two heat dissipation parts 200, it has one of the heat dissipation parts 200 and an additional heat dissipation part 500.

[0167] <2-2. Drive Unit>

[0168] Reference Figures 6-10 This describes an embodiment of the drive unit 25 according to the second embodiment. For example... Figure 6 As shown, the first to third semiconductor switches Q1 to Q3 are arranged in a row along the left-right direction on the first circuit surface 11A, similar to the first embodiment. The first to third semiconductor switches Q1 to Q3 are also configured in the first embodiment such that the first ends 46A, 56A, and 66A are on the front side and the second ends 46B, 56B, and 66B are on the rear side.

[0169] like Figure 7 As shown, semiconductor switches Q4 to Q6, numbered 4 to 6, are arranged in a row along the left-right direction on the second circuit surface 11B. Semiconductor switches Q4 to Q6 are respectively positioned opposite semiconductor switches Q1 to Q3, numbered 1 to 3, separated by the circuit board 11. Semiconductor switches Q4 to Q6 are configured such that the second ends 76B, 86B, and 96B are the front side, and the first ends 76A, 86A, and 96A are the rear side.

[0170] Therefore, the source terminal 43 of the first semiconductor switch Q1 is disposed opposite to the drain terminal 72 of the fourth semiconductor switch Q4, separated by the circuit board 11. The source terminal 53 of the second semiconductor switch Q2 is disposed opposite to the drain terminal 82 of the fifth semiconductor switch Q5, separated by the circuit board 11. The source terminal 63 of the third semiconductor switch Q3 is disposed opposite to the drain terminal 92 of the sixth semiconductor switch Q6, separated by the circuit board 11.

[0171] The circuit board 11 includes first to third through holes 501 to 503 penetrating the circuit board 11. The first to third through holes 501 to 503 are slits extending in a left-right direction. The first to third through holes 501 to 503 are disposed near the source terminals 43, 53, 63 and the gate terminals 41, 51, 61 (for example, within 10 mm of these terminals) along the second ends 46B, 56B, 66B of the first to third semiconductor switches Q1 to Q3. Therefore, the first to third through holes 501 to 503 are disposed near the drain terminals 72, 82, 92 along the first ends 76A, 86A, 96A of the fourth to sixth semiconductor switches Q4 to Q6.

[0172] The length of each of the first to third substrate through-holes 501 to 503 in the left-right direction is approximately equal to the width in the left-right direction of at least one corresponding semiconductor switch among the first to sixth semiconductor switches Q1 to Q6. In other embodiments, the planar shape of each of the first to third substrate through-holes 501 to 503 can be an ellipse, a circle, or a polygon.

[0173] Metal components 600 are respectively inserted into one corresponding through-hole of the first to third substrate through-holes 501 to 503. Figure 6 as well as Figure 7 For convenience, the metal component 600 is inserted into the first and second substrate through holes 501 and 502. The metal component 600 is then removed from the third substrate through hole 503. In fact, the first to third substrate through holes 501 to 503 are all filled with the metal component 600.

[0174] Metal component 600 comprises or is made of a metal with high conductivity. Examples of metals include copper, silver, gold, and aluminum. Metal component 600 is a pre-manufactured solid component. In other embodiments, at least one of the three metal components 600 may be a conductive paste that is filled in the through-holes 501-503 of the first to third substrates and cured or sintered. The conductive paste is a metal paste, and more specifically, may be gold paste, silver paste, copper paste, or aluminum paste. Furthermore, in other embodiments, at least one of the three metal components 600 may be solder that is filled in the through-holes 501-503 of the first to third substrates and cured.

[0175] like Figure 8 As shown, the metal component 600 includes a first portion 610 and a second portion 620. The first portion 610 is cuboid in shape. On any horizontal plane, the length of the long side of the first portion 610 is greater than the length of each of the first to third substrate through holes 501 to 503 in the left-right direction. On any horizontal plane, the length of the short side of the first portion 610 is slightly less than the length of each of the first to third substrate through holes 501 to 503 in the front-back direction, but it can be the same or larger. The second portion 620 is cuboid in shape. The second portion 620 is connected to the lower part of the first portion 610 such that the long side of the second portion 620 aligns with the long side of the first portion 610. The length of the long side of the second portion 620 is slightly less than the length of each of the first to third substrate through holes 501 to 503 in the left-right direction. The length of the short side of the second portion 620 is slightly less than the length of each of the first to third substrate through holes 501 to 503 in the front-back direction. The height of part 2 620 is approximately equal to the thickness of the circuit board 11. The metal parts 600 each have a T-shaped vertical cross-section, but may also have other vertical cross-section shapes.

[0176] Metal components 600 are inserted from the first circuit surface 11A toward the second circuit surface 11B into corresponding through holes 501 to 503 of the first to third substrates. A first portion 610 hooks onto the first circuit surface 11A, preventing the corresponding metal component 600 from falling off the circuit board 11. A second portion 620 is housed within the first to third through holes 501 to 503.

[0177] like Figure 6 as well as Figure 9As shown, the first to third printed wirings 511 to 513 are respectively disposed between one corresponding source terminal of the first to third semiconductor switches Q1 to Q3 (43, 53, 63) and one corresponding substrate through-hole of the first to third substrate through-holes 501 to 503. Furthermore, the first to third printed wirings 511 to 513 are also disposed on the rear side of one corresponding substrate through-hole of the first to third substrate through-holes 501 to 503.

[0178] Printed wirings 511-513 (first to third) are electrically connected to source terminals 43, 53, and 63, respectively. Specifically, printed wirings 511-513 are soldered to source terminals 43, 53, and 63, respectively. In addition, printed wirings 511-513 are electrically connected to a corresponding metal component 600. Specifically, printed wirings 511-513 are soldered to the first portion 610 of a corresponding metal component 600. The metal component 600 is electrically connected to a corresponding terminal among the U-phase terminal 45, V-phase terminal 55, and W-phase terminal 65 via a corresponding printed wiring from printed wirings 511-513.

[0179] Solder resist 15 is applied between the source terminals 43, 53, and 63 and the three metal components 600, and on the first to third printed wirings 511 to 513. Additionally, solder resist 15 is applied to the rear side of the three metal components 600, and on the first to third printed wirings 511 to 513. No solder resist 15 is applied to the underside of the first to third mounting surfaces 48, 58, and 68. The lower ends of the gate terminals 41, 51, and 61, the drain terminals 42, 52, and 62, and the source terminals 43, 53, and 63 are located slightly higher than the corresponding mounting surface among the first to third mounting surfaces 48, 58, and 68. When solder resist 15 is applied to the underside of the first to third mounting surfaces 48, 58, and 68, solder bonding of the gate terminals 41, 51, and 61, the drain terminals 42, 52, and 62, and the source terminals 43, 53, and 63 becomes difficult.

[0180] like Figure 7 as well as Figure 9 As shown, the 4th to 6th printed wirings 521 to 523 are respectively disposed between one corresponding drain terminal of the 4th to 6th semiconductor switches Q4 to Q6 (72, 82, 92) and one corresponding substrate through-hole of the 1st to 3rd substrate through-holes 501 to 503. Furthermore, the 4th to 6th printed wirings 521 to 523 are also disposed on the rear side of one corresponding substrate through-hole of the 1st to 3rd substrate through-holes 501 to 503.

[0181] Printed wirings 521-523, numbered 4 to 6, are electrically connected to drain terminals 72, 82, and 92, respectively. Specifically, printed wirings 521-523 are soldered to drain terminals 72, 82, and 92, respectively. Additionally, printed wirings 521-523 are electrically connected to a corresponding metal component of the metal components 600. Specifically, printed wirings 521-523 are soldered to the second portion 620 of a corresponding metal component of the metal components 600. The metal components 600 are electrically connected to a corresponding terminal of the U-phase terminal 45, V-phase terminal 55, and W-phase terminal 65 via a corresponding printed wiring from printed wirings 521-523.

[0182] Solder resist 15 is applied between the drain terminals 72, 82, and 92 and the three metal components 600, and on the 4th to 6th printed wirings 521 to 523. Additionally, solder resist 15 is applied to the rear side of the three metal components 600, and on the 4th to 6th printed wirings 521 to 523. No solder resist 15 is applied to the underside of the 4th to 6th mounting surfaces 78, 88, and 98.

[0183] The source terminals 43, 53, and 63 of the first to third semiconductor switches Q1 to Q3 are each electrically connected to a corresponding drain terminal 72, 82, and 92 of the fourth to sixth semiconductor switches Q4 to Q6 via a corresponding metal component 600. This minimizes the length of the printed wiring from the source terminals 43, 53, and 63 to their respective drain terminals 72, 82, and 92. Consequently, the inductive component of the drive circuit 21 is reduced. This suppresses surge voltages accompanying the switching operation of the first to sixth semiconductor switches Q1 to Q6, thereby reducing the rated voltage of the first to sixth semiconductor switches Q1 to Q6. Furthermore, heat generated by the first to sixth semiconductor switches Q1 to Q6 can be suppressed. This allows for the removal or reduction of at least one of the metal plate 100 and heat dissipation components 200 and 500. Additionally, it enables the miniaturization of electronic components on the circuit board 11. Therefore, the drive unit 25 can be miniaturized, thereby reducing costs.

[0184] Without using the metal component 600, source terminals 43, 53, and 63 can be electrically connected to drain terminals 72, 82, and 92, respectively, using printed wiring and vias. However, when connecting these terminals using printed wiring and vias, the printed wiring becomes longer, and the inductive component of the printed wiring increases. As a result, the surge voltage accompanying the switching operation of semiconductor switches Q1 to Q6 increases.

[0185] like Figure 10As shown, similarly to the first embodiment, one metal plate 100 and the heat dissipation component 200 are attached to the high-side switch. On the other hand, the other metal plate 100 and the heat dissipation component 500 are attached to the low-side switch. The basic configuration of the heat dissipation component 500 is the same as that of the heat dissipation component 200. Hereinafter, the differences between the heat dissipation component 500 and the heat dissipation component 200 will be explained.

[0186] The heat dissipation component 500 includes a base 510, a plurality of heat sinks 520, and an outer peripheral wall 540. The base 510 is a plate-shaped component with a length greater than that of the base 210 in the left-right direction. Each of the plurality of heat sinks 520 has the same shape as the plurality of heat sinks 220. The heat dissipation component 500 does not include a mounting portion 230. The plurality of heat sinks 520 are connected to the base 510 with their long sides facing the front-back direction. The plurality of heat sinks 520 are arranged in the left-right direction. In other embodiments, the plurality of heat sinks 520 may also be arranged in the front-back direction on the base 510 with their long sides facing the left-right direction. Furthermore, in other embodiments, the plurality of heat sinks 520 may have other shapes such as a wavy shape or a pointed shape.

[0187] The outer peripheral wall 540 is connected to the upper surface of the base 510. The outer peripheral wall 540 has a height that is the same as the length from the upper surface of the base 510 to the upper end of the heat dissipation component 200. The outer peripheral wall 540 surrounds the left, right, front, and rear sides of the circuit board 11, the two metal plates 100, and the heat dissipation component 200, respectively.

[0188] After assembling the first to sixth semiconductor switches Q1 to Q6, two metal plates 100, heat sink 200, and heat sink 500 onto the circuit board 11, resin is injected into the inner side of the outer peripheral wall 540, and the drive unit 25 is molded from the resin. The resin-molded drive unit 25 is housed in the housing 2.

[0189] In other embodiments, the outer peripheral wall 540 may be removed from the heat dissipation component 500. When the outer peripheral wall 540 is removed, the drive unit 25 is held in a mold and molded with resin. The resin-molded drive unit 25 is housed in the housing 2. Alternatively, when the outer peripheral wall 540 is removed, the drive unit 25 may also be housed in a housing. The drive unit 25 housed in the housing is in turn housed in the housing 2.

[0190] <2-3. Variations>

[0191] exist Figure 10 In the middle, the first and second thermistors 27 and 29 each have a second height H2, and through holes 160 are formed in the metal plate 100 respectively, but it can also be as Figure 5The first embodiment shown is modified as described above. That is, the first and second thermistors 27 and 29 may each have a third height H3, and through holes 160 are not formed in the metal plate 100.

[0192] <2-4. Effects>

[0193] According to the second embodiment described in detail above, the effects of the first embodiment described above (1) to (6) can be achieved.

[0194] (3. Other implementation methods)

[0195] (a) In the above embodiments, although one metal plate 100 is coupled to three high-side switches and one metal plate 100 is coupled to three low-side switches, the present invention is not limited thereto. Figure 3 , 6 In section 7, as shown by the dotted line, one metal plate 100 can also be attached to one semiconductor switch. This increases the flexibility in the arrangement of the semiconductor switches by attaching different metal plates 100 to each semiconductor switch. That is, it is not necessary to arrange the three high-side switches or the three low-side switches in a row. Six semiconductor switches can be freely arranged on the first circuit surface 11A, or on the first circuit surface 11A and the second circuit surface 11B. Additionally, one metal plate 100 can also be attached to two semiconductor switches. Furthermore, one heat sink 200 or another heat sink can be securely connected to one metal plate 100 using an external threaded component 400. Alternatively, one heat sink 200 or another heat sink can be securely connected to multiple metal plates 100 using an external threaded component 400.

[0196] (b) In the above embodiments, first and second thermistors 27 and 29 having a second height H2 are mounted on the circuit board 11. However, different circuit components having a second height H2 may be mounted instead of the first and second thermistors 27 and 29. Furthermore, in a variation of the above embodiments, first and second thermistors 27 and 29 having a third height H3 are mounted on the circuit board 11. However, different circuit components having a third height H3 may be mounted instead of the first and second thermistors 27 and 29.

Claims

1. An electric work machine, characterized in that, The electric work machine has the following features: A motor is configured to receive power from a power source for driving. A circuit board having a first circuit surface and a second circuit surface located on the opposite side of the first circuit surface; A first semiconductor switch, located on the first circuit surface, has a first metal surface and a first mounting surface, and is electrically connected to the power supply and the motor. The first mounting surface is located on the opposite side of the first metal surface and faces the first circuit surface. A metal plate having a first plate surface that engages with the first metal surface, and a second plate surface located on the opposite side of the first plate surface; A heat dissipation component that is in direct or indirect contact with the second plate surface; as well as An external threaded component securely connects the heat dissipation component and the metal plate.

2. The electric work machine according to claim 1, characterized in that, The heat dissipation component includes: a through hole for the external threaded component to be inserted. The metal plate has an internal thread that engages with the external threaded component.

3. The electric work machine according to claim 1 or 2, characterized in that, The electric work machine also has a conductive elastic component disposed between the first circuit surface and the heat dissipation component.

4. The electric work machine according to any one of claims 1 to 3, characterized in that, The electric work machine also includes electrical components. The metal plate has through holes. The first semiconductor switch has a first height in a direction perpendicular to the circuit substrate. The through hole of the board is aligned with the circuit component mounted on the first circuit surface, and the circuit component has a second height that is greater than the first height in the vertical direction.

5. The electric work machine according to any one of claims 1 to 3, characterized in that, The electric work machine also includes: circuit components mounted on the first circuit surface. The first semiconductor switch has a first height in a direction perpendicular to the circuit substrate. The circuit component has a second height that is smaller than the first height in the vertical direction.

6. The electric work machine according to claim 3, characterized in that, The elastic component is a leaf spring.

7. The electric work machine according to claim 4, characterized in that, The electric work machine also includes a second semiconductor switch, which is located on the first circuit surface. Unlike the first semiconductor switch, this second semiconductor switch has a second metal surface and a second mounting surface, and is electrically connected to the power supply and the motor. The second mounting surface is located on the opposite side of the second metal surface and faces the first circuit surface. The first plate surface is brazed to the first metal surface and the second metal surface. The circuit component is disposed on the first circuit plane between the first semiconductor switch and the second semiconductor switch.

8. The electric work machine according to claim 5, characterized in that, The electric work machine also includes a second semiconductor switch, which is located on the first circuit surface. Unlike the first semiconductor switch, this second semiconductor switch has a second metal surface and a second mounting surface, and is electrically connected to the power supply and the motor. The second mounting surface is located on the opposite side of the second metal surface and faces the first circuit surface. The first plate surface is brazed to the first metal surface and the second metal surface. The circuit component is disposed on the first circuit plane between the first semiconductor switch and the second semiconductor switch.

9. The electric work machine according to claim 7, characterized in that, The circuit component is a thermistor.

10. The electric work machine according to claim 8, characterized in that, The circuit component is a thermistor.

11. The electric work machine according to any one of claims 1 to 10, characterized in that, The heat dissipation component includes multiple heat sinks.

12. A method for assembling a drive unit for driving a motor of an electric work machine, characterized in that, The method comprises the following steps: The semiconductor switch of the driving unit is mounted on the circuit board of the driving unit. The semiconductor switch has a mounting surface and a metal surface opposite to the mounting surface, and the mounting surface is positioned opposite to the circuit board. Join the first plate surface of the metal plate to the metal surface; The heat dissipation component is brought into direct or indirect contact with the second plate surface located on the opposite side of the first plate surface; as well as The heat dissipation component and the metal plate are fastened together using screws.

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