ELECTRIC DRIVE DEVICE AND ELECTRIC STEERING POWER SUPPORT DEVICE

Abstract

Electric drive device (1) for driving a machine system, comprising: an electric motor (EM) having an output shaft (OS) through which control elements of the machine system are driven; and an electronic control unit (9) located at a position opposite the position where the output shaft (OS) of the electric motor (EM) is located, the electronic control unit (9) comprising a cylindrical metal housing (111) with a bottom wall having the electric motor (EM) associated therewith, and an electronic control device arrangement (ECA) installed in the cylindrical metal housing (111) to control the operation of the electric motor (EM), wherein the electronic control device arrangement (ECA) is divided into three parts which are installed coaxially in the cylindrical housing (111) in a sequence, the three parts being: a current circuit part (15) mounted on a metal base plate (16) which mainly generates an electric current, a power converter circuit part (21) mounted on a metal base plate (22) which mainly drives the electric motor (EM), and a control circuit part (25) mounted on a resin plate (26) which mainly controls the power converter circuit part (21), wherein a metal heat transfer substrate (14) is installed in the cylindrical metal housing (111), while at a cylindrical outer wall thereof it is in contact with an inner wall of the cylindrical metal housing (111); and wherein the metal base plate (16) of the current circuit part (15) and the metal base plate (22) of the power converter circuit part (21) are intimately connected to opposite flat surfaces of the metal heat transfer substrate (14).

Description

BACKGROUND OF THE INVENTION: 1. Field of the invention:

[0001] The present invention relates generally to an electric drive device, and more specifically to an electric power steering device. More precisely, the present invention relates to an electric power steering device comprising an electronic control unit installed therein. 2. Description of the related prior art:

[0002] In the field of industrial machinery today, components for controlling the machines are driven by an electric motor. Recently, a so-called mechanically and electrically integrated drive device has begun to be put into practical use in industrial machinery. In this device, an electronic control unit, comprising semiconductor elements for controlling the speed and torque of the electric motor, is integrally installed within the electric motor itself.

[0003] One such mechanically and electrically integrated drive device is an electric power steering system used in motor vehicles. When a driver turns the steering wheel in an electric power steering system, the direction and torque of rotation of the steering shaft connected to the steering wheel are detected. Based on this detection, an electric motor rotates in the appropriate direction to assist the driver's steering. In other words, when the driver turns the steering wheel, the electric motor generates steering assistance torque. An electronic control unit (ECU), installed within the electric power steering system, controls the electric motor in this manner.

[0004] The published Japanese patent application (tokkai) JP 2013 - 60 119 A discloses such an electric power steering device. That is, the electric power steering device disclosed in the publication comprises an electric motor and an electronic control unit installed in a main body of the electric power steering device.

[0005] More precisely, the electric motor used for the electric power steering device has a cylindrical motor housing made of aluminum alloy to contain essential components of the electric motor, and the electronic control unit used for this purpose is housed in an ECU package located at one axial end of the cylindrical motor housing opposite the other axial end, where an output shaft of the electric motor is located. The electronic control unit in the ECU package generally comprises a current circuit section, a power converter circuit section which includes a MOSFET (metal oxide silicon field-effect transistor) to control the driving of the electric motor, and a control circuit section that controls the MOSFET. Output terminals of the MOSFET are connected to input terminals of the electric motor via busbars.

[0006] The electronic control unit (ECU) in the housing is supplied with electrical current from a power source via a connector assembly made of resin with embedded wires. Information signals from detection sensors are fed to the ECU to determine the current operating state of the electric power steering system. During assembly of the electric power steering system, the connector assembly is inserted through an opening in the ECU housing, connected to the ECU, and then secured to an outer wall of the ECU housing with connecting bolts.

[0007] In addition to the aforementioned electric power steering device, the drive device of the mechanically and electrically integrated type is applied to electric hydraulic pressure control devices, such as electric brakes and the like.

[0008] Further examples, each relating to electric motors with axially arranged integrated control electronics, are disclosed in US 2012 / 0 098 365 A1, DE 10 2005 060 282 A1 and US 2014 / 0 239 755 A1. SUMMARY OF THE INVENTION:

[0009] The electric power steering device described in the aforementioned published Japanese patent application (tokkai) JP 2013 - 60 119 A is located in the engine compartment of a motor vehicle. Therefore, miniaturization of the electric power steering device is highly desirable, as various auxiliary devices, such as an exhaust emission control device, a safety measuring device, and the like, are now located in the engine compartment.

[0010] Furthermore, in the electric power steering device of the aforementioned Japanese publication, the power circuit section, the power converter circuit section, and the control circuit section are mounted on two substrates. However, due to the increased number of components comprising the power circuit section, the power converter circuit section, and the control circuit section, the size of the housing for the electronic control unit is inevitably increased, particularly in a radial direction. Since the power circuit section and the power converter circuit section are the ones that generate heat, it was also highly desirable for the heat from these circuit sections to be effectively dissipated into the environment.

[0011] It is therefore an object of the present invention to provide an electric drive device and an electric power steering device that are free from the disadvantages mentioned above.

[0012] According to the present invention, an electric drive device and an electric power steering device are provided in which the radial size of a metal housing in order to install an electronic control unit is prevented from increasing, and heat generated by the electronic control unit is effectively transferred to the metal housing through a metal heat transfer substrate installed in the metal housing.

[0013] In the present invention, the electrical elements forming the electronic control unit are functionally divided into three groups, which are arranged coaxially in a cylindrical metal housing to prevent the cylindrical metal housing from having an increased radial size. Furthermore, the respective metal base plates of two circuit sections are intimately connected to opposing flat surfaces of a circular metal heat transfer substrate, the cylindrical outer wall of which is intimately connected to a cylindrical inner surface of the cylindrical metal housing. This allows heat generated by the two circuit sections to be effectively transferred through the metal heat transfer substrate to the cylindrical metal housing and then effectively radiated from the cylindrical metal housing to the outside.

[0014] According to a first aspect of the present invention, the following are provided: an electric drive device for driving a machine system, comprising an electric motor having an output shaft through which control elements of the machine system are driven; and an electronic control unit arranged at a position opposite the position where the output shaft of the electric motor is located, the electronic control unit comprising a cylindrical metal housing with a bottom wall having the electric motor connected thereto, and an electronic control device arrangement installed in the cylindrical metal housing to control the operation of the electric motor, the electronic control device arrangement being divided into three parts installed coaxially in the cylindrical housing in a sequence, the three parts being: a power circuit part,a power converter circuit part mounted on a metal base plate and mainly generating an electric current, a power converter circuit part mounted on a metal base plate and mainly driving the electric motor, and a control circuit part mounted on a resin plate and mainly controlling the power converter circuit part, wherein a metal heat transfer substrate is installed in the cylindrical metal housing, while at a cylindrical outer wall thereof is in contact with an inner wall of the cylindrical metal housing; and wherein the metal base plate of the power converter circuit part and the metal base plate of the power converter circuit part are intimately connected to opposing flat surfaces of the metal heat transfer substrate.

[0015] According to a second aspect of the present invention, an electric power steering device for a motor vehicle is provided, comprising: an electric motor having an output shaft by which a power steering force is exerted on a steering shaft of the vehicle; an electronic control unit for controlling the electric motor, wherein the electronic control unit is arranged at a position opposite the position where the output shaft of the electric motor extends; a cylindrical housing having a base to which the electric motor is connected; and an electronic control device arrangement installed in the cylindrical housing to control the operation of the electric motor, wherein the electronic control device arrangement is divided into three parts installed coaxially in the cylindrical housing in a sequence, the three parts being: a power circuit part,a power converter circuit part mounted on a metal base plate and mainly generating an electric current, a power converter circuit part mounted on a metal base plate and mainly driving the electric motor, and a control circuit part mounted on a resin plate and mainly controlling the power converter circuit part, wherein a metal heat transfer substrate is installed in the cylindrical metal housing, while at a cylindrical outer wall thereof is in contact with an inner wall of the cylindrical metal housing; and wherein the metal base plate of the power converter circuit part and the metal base plate of the power converter circuit part are intimately connected to opposing flat surfaces of the metal heat transfer substrate.

[0016] According to a third aspect of the present invention, an electric power steering device for a motor vehicle is provided, comprising: a cylindrical metal housing having a first, second, third, and fourth chamber arranged coaxially in a sequence; an electric motor located in the fourth chamber and having an output shaft through which a power steering force is exerted on a steering shaft of the motor vehicle; a current circuit section located in the first chamber and comprising a first metal base plate and electrical elements mounted on the first metal base plate; a power conversion circuit section located in the second chamber and comprising a second metal base plate and electrical elements mounted on the second metal base plate; a control circuit section located in the third chamber and comprising electrical elements;a circular metal heat transfer substrate arranged in the cylindrical metal housing between the first and second chambers, the circular metal heat transfer substrate having a cylindrical outer wall in contact with an inner cylindrical surface of the cylindrical metal housing, an upper flat surface with which the first metal base plate is intimately connected, and a lower flat surface with which the second metal base plate is intimately connected; and a lid element connected to an open end of the cylindrical metal housing. BRIEF DESCRIPTION OF THE DRAWINGS:

[0017] Other tasks and advantages of the present invention will become clear from the following detailed description in conjunction with the accompanying drawings, in which: Fig. 1 a perspective view of a known electric power steering device, the essential section of which is of a so-called mechanically and electrically integrated type; Fig. 2 an enlarged perspective view of the essential section of the known electric power steering device made of Fig. 1 is of the so-called mechanically and electrically integrated type; Fig. 3 a perspective exploded view of an essential section of an electric power steering device according to the present invention; Fig. 4 is an enlarged sectional view of the essential section of the electric power steering device of the present invention; Fig. 5 is an enlarged perspective view of an inverted cover element used in the essential section of the electric power steering device of the present invention; Fig. 6 is a perspective view of a current circuit part that is used in the essential section of the electric power steering device of the present invention; Fig. 7 is a perspective view of an inverted power converter circuit part used in the essential section of the electric power steering device of the present invention; and Fig. Figure 8 shows a perspective view of an inverted control circuit part used in the essential section of the electric power steering device of the present invention. DESCRIPTION OF THE KNOWN ELECTRIC STEERING POWER ASSISTANCE DEVICE:

[0018] Before a detailed description of the present invention is given, a known electric power steering device, the essential section of which is of a mechanically and electrically integrated type, will be briefly described with the aid of the Fig. 1 and Fig. 2 described in order to clarify the unique features of the electric power steering device that the present invention possesses.

[0019] Referring to Fig. Figure 1 shows the complete construction of a known electric power steering device 1, the essential section of which is of a mechanically and electrically integrated type. The electric power steering device 1 shown is designed and constructed to steer the front wheels of a motor vehicle.

[0020] In Fig. 1 is designated by number 2 as a steering shaft to which a steering wheel (not shown) is connected. The steering shaft 2 has a pinion (not shown) at its lower end, which effectively engages with a rack (not shown) that is movable in a lateral direction of the vehicle. The rack has tie rods 3 at each of its ends, and the rack is covered by a rack housing 4. A rubber boot 5 extends between the rack housing 4 and each tie rod 3.

[0021] The number 6 designates an electric power assist unit designed to assist the driver's steering efforts. The electric power assist unit 6 generally comprises a rotation / torque sensor 7, which detects the direction and rotational torque of the steering shaft 2; an electric motor unit 8, which includes an electric motor to assist the lateral movement of the rack via a gear unit 10; and an electronic control unit (ECU) 9, which controls the electric motor based on the information detected by the rotation / torque sensor 7.

[0022] As from the Fig. As can be seen in Figure 1, an output shaft (not shown) of the electric motor of the electric motor part 8 extends towards the gear unit 10 and engages with the gear unit 10, and the electronic control unit 9 is arranged in a position axially opposite the position where the gear unit 10 is provided.

[0023] As from Fig. As can be seen in Figure 2, the electric motor part 8 has a cylindrical motor housing 11A made of aluminum alloy in which the electric motor “EM” is installed.

[0024] It should be noted that also in Fig. 2 the electronic control unit 9, comprising an aluminum alloy ECU housing 11B, is arranged at an axial end of the electric motor part 8, which is axially opposite the position where the output shaft (not shown) of the electric motor “EM” is provided.

[0025] The motor housing 11A and the ECU housing 11B are fitted together at their facing ends and integrally connected via connecting bolts (not shown). The electronic control device assembly installed in the ECU housing 11B comprises a power circuit section that produces current, a power converter circuit section that includes a MOSFET to control the driving of the electric motor of the electric motor section 8, and a control circuit section that controls the MOSFET. The output terminals of the MOSFET and the input terminals of the electric motor are electrically connected via busbars (not shown).

[0026] As from the Fig. As can be seen in Figure 2, a resin cover element 120 is fixed at the other end of the ECU housing 11B via connecting bolts (not shown). The cover element 120 forms part of a connector assembly. The cover element 120 is provided with a current input connector 120A, an information signal input connector 120B, and a command signal output connector 120C.During operation, the electronic control device assembly, which is installed in the ECU housing 11B, is supplied with an electrical current from the power source through the current input connector terminal 120A of the cover element 120, and at the same time information signals output by various detection sensors are routed to the electronic control device assembly via the information signal input connector terminal 12B, and command signals output by the electronic control device assembly are supplied to various controlled parts via the command signal output connector terminal 120C.

[0027] Referring again to Fig. 1. When the steering wheel (not shown) is turned or operated by the driver during operation, the direction of rotation and the rotational torque of the steering wheel 2 are detected by the rotation / torque sensor 7. The detected values ​​of the direction of rotation and the rotational torque are then processed by the electronic control unit 9 to calculate a desired amount of driving operation to be performed by the electric motor. Based on this calculated desired amount of driving operation, the electric motor is actuated by the MOSFET of the power converter circuit section, causing the output shaft of the electric motor to rotate in the same direction as the steering shaft 2 for a given time. This assists the driver's manual steering effort with the electric power assist unit 6.

[0028] However, even in the aforementioned known electric power steering device 1, miniaturization has not yielded a satisfactory result due to its inherent design. That is to say, in the aforementioned known steering device 1, the radial size of the electric power assist unit 6 was not sufficiently reduced by a known measure. Furthermore, the electric power assist unit 6 of the power steering device 1 does not provide a satisfactory means of effectively dissipating the heat from the current circuit and power converter circuitry. DETAILED DESCRIPTION OF THE INVENTION:

[0029] In the following, an electric power steering device according to the present invention, which is free from the aforementioned disadvantages, is described with reference to the Fig. 3, Fig. 4, Fig. 5, Fig. 6, Fig. 7 to Fig. 8 described in detail.

[0030] For better understanding, essentially the same parts as those of the aforementioned known electric power assist unit 6 are designated by the same numbers in the Fig. 3, Fig. 4, Fig. 5, Fig. 6, Fig. 7 to Fig. 8. Furthermore, various directional terms, such as right, left, upper, lower, to the right, and the like, are used in the following description. However, such terms are only to be understood in relation to a drawing or drawings in which a corresponding part or section is shown.

[0031] Referring to Fig. Figure 3 shows an electric power assistance unit 60 of a mechanically and electrically integrated type, which is used in the electric power steering device of the present invention.

[0032] As in Fig. As can be seen in Figure 3, the electric power assistance unit 60 comprises an electric motor “EM” installed in a lower part of a cylindrical motor housing 111 made of aluminum alloy. As shown in Figure 3, the electric power assistance unit 60 comprises an electric motor “EM” installed in a lower part of a cylindrical motor housing 111 made of aluminum alloy. Fig. As can be seen in Figure 3, the electric motor “EM” is positioned in the cylindrical motor housing 111 such that its output shaft “OS” extends diagonally in the direction to the lower left in the drawing.

[0033] As will become clear in the further course of the description, the cylindrical motor housing 111 is of the monoblock type and is designed and dimensioned to contain not only the electric motor “EM”, but also an electronic control device arrangement “ECA”.

[0034] This means that, as can be seen from the Fig. 3 and Fig. 4 shows that the electronic control device assembly ECA is tightly installed within an upper part of the cylindrical motor housing 111.

[0035] As from Fig. As can be seen in Figure 3, the electronic control device arrangement ECA comprises a circular partition 50 which is tightly inserted into the cylindrical motor housing 111, an annular intermediate hollow element 13 which is mounted above the circular partition 50 and fastened to it by connecting bolts 13a, a cover element 12 which is mounted on the annular intermediate hollow element 13 and fastened to it by connecting bolts 12d, and various electronic elements of an electronic control unit (ECU) 9 which are neatly arranged in spaces defined between the wall 50, the hollow element 13 and the cover element 12 in the manner described below.

[0036] More precisely, the electronic elements of the electronic control unit (ECU) 9 comprise a current circuit section 15, a power converter circuit section 21, and a control circuit section 25. As can be seen from Fig. As can be seen in Figure 3, a circular heat transfer substrate 14, made of aluminum or aluminum alloy, is installed inside the ring-shaped intermediate hollow element 13.

[0037] The annular intermediate hollow element 13 comprises a cylindrical body made of a synthetic resin to which the heat transfer substrate 14 is integrally molded. However, if desired, the cylindrical body and the heat transfer substrate 14 can be formed integrally from an aluminum alloy. As described below, the heat transfer substrate 14 effectively transfers heat generated by the current circuit section 15 and the power converter circuit section 21 to the cylindrical motor housing 111. More precisely, the heat transfer substrate 14 transfers the heat from the circuit sections 15 and 21 to the annular intermediate hollow element 13. For this purpose, a cylindrical outer wall of the circular heat transfer substrate 14 is intimately bonded to a cylindrical inner wall of the annular intermediate hollow element 13.

[0038] As from Fig. As can be seen in Figure 3, the current circuit part 15 is arranged between the cover element 12 and the intermediate hollow element 13, which fulfills the function of generating a stable electric current.

[0039] As from Fig. As can be seen in Figure 6, the power circuit section 15 comprises a base plate 16, capacitors 17, inductors 18, switching elements 19, and connectors 20, which are mounted on the metal base plate 16. The base plate 16 comprises an aluminum plate, an insulating layer applied to the aluminum plate, and a wiring pattern printed on the insulating layer. The capacitors 17, the inductors 18, the switching elements 19, and the connectors 20 are mounted on and connected to the wiring pattern in a known manner.

[0040] As from Fig. As shown in Figure 4, the heat transfer substrate 14 and the base plate 16 are intimately connected by connecting bolts (not shown) to increase heat transfer between them. A highly thermally conductive adhesive is used to join the heat transfer substrate 14 and the base plate 16. A gel-like heat transfer material can be used instead of the adhesive.

[0041] As from Fig. As can be seen in Figure 3, part 15 incorporates the capacitors 17, the coils 18, and the connectors 20, which have a space-consuming design. Thus, the current circuit part 15 is installed in a relatively large space defined between the cover element 12 and the annular intermediate hollow element 13. This reason is described below.

[0042] As from Fig. As can be seen in Figure 3, the power converter circuit part 21, which mainly controls the operation of the electric motor EM, is arranged in a space defined between the annular intermediate hollow element 13 and the motor housing 111.

[0043] As from Fig. Figure 7 shows a view of the power converter circuit section 21, which, with respect to those shown in Fig. As shown in Figure 4, when inverted, part 21 comprises a base plate 22, a plurality of MOSFETs 23, and input / output connectors 24 effectively mounted on the base plate 22. Like the base plate 16 of the power circuit part 15 mentioned above, the base plate 22 comprises an aluminum plate, an insulating layer applied to the aluminum plate, and a wiring pattern printed on the insulating layer. The MOSFETs 23 and the input / output connectors 24 are mounted on and connected to the wiring pattern in a known manner.

[0044] As from Fig. As shown in Figure 4, the heat transfer substrate 14 and the base plate 22 are intimately connected by connecting bolts (not shown) to increase heat transfer between them. A highly thermally conductive adhesive is used to join the heat transfer substrate 14 and the base plate 22. A gel-like heat transfer material can be used instead of the adhesive.

[0045] As from Fig. As can be seen in Figure 3, a control circuit part 25 is arranged between the power converter circuit part 21 and the circular partition 50 in the motor housing 111, which mainly controls the switching operation of the MOSFETs 23 of the power converter circuit part 21.

[0046] As from Fig. Figure 8 shows a view of the control circuit part 25, which, with respect to those shown in Fig. As shown in Figure 4, when inverted, part 25 comprises a resin substrate 26 and a microcomputer 27 mounted on the resin substrate 26 to control the MOSFETs 23.

[0047] As from Fig. As can be seen in Figure 4, the resin substrate 26 of the control circuit part 25 and the base plate 22 of the power converter circuit part 21 are spaced apart from each other by a given distance.

[0048] How best to Fig. As shown in Figure 3, the cover element 12 has several connectors 12A, 12B, and 12C mounted on it. Electrical current and various signals from the current circuit section 15, the power converter circuit section 21, and the control circuit section 25 are output and input through these connectors 12A, 12B, and 12C.

[0049] The detailed construction of the lid element 12 is described in Fig. Figure 5 shows a view of the lid element 12, relative to the one in Fig. The 4 shown are reversed.

[0050] The following section describes in detail the electronic control device assembly (ECA) installed in the motor housing 111 using the Fig. 3 and Fig. 4 described.

[0051] As can be seen from the drawings, the annular intermediate hollow element 13 is attached to the motor housing 111 by connecting bolts 28, and the heat transfer substrate 14 is integrated with the molded resin of the annular intermediate hollow element 13. As mentioned previously, the heat transfer substrate 14 and the annular intermediate hollow element 13 can be formed in one piece from an aluminum oxide alloy or the like.

[0052] As from Fig. As shown in Figure 4, an outer cylindrical wall of the cylindrical heat transfer substrate 14 is in close contact with an inner cylindrical surface of the motor housing 111. This allows heat to be transferred smoothly and effectively from the heat transfer substrate 14 to the motor housing 111. If desired, a highly thermally conductive adhesive can be applied to the contacting surfaces of the heat transfer substrate 14 and the motor housing 111. A sealing ring 29 is arranged between the circular heat transfer substrate 14 and the cylindrical motor housing 111. In the embodiment shown, the sealing ring 29 is inserted into an annular recess (no reference numeral) formed in the outer cylindrical surface of the heat transfer substrate 14. The sealing ring 29 creates a watertight seal between the heat transfer substrate 14 and the cylindrical motor housing 111.

[0053] As from the Fig. 3 and Fig. As can be seen in Figure 4, the base plate 16 of the power circuit section 15 is intimately positioned on the upper surface of the heat transfer substrate 14. Several connecting bolts are used to fasten the base plate 16 to the heat transfer substrate 14.

[0054] As in Fig. As shown in Figure 4 and mentioned previously, relatively space-consuming elements of the power circuit section 15, such as capacitors 17, coils 18, and connectors 20, are mounted on the metal base plate 16. Thus, the power circuit section 15 is arranged in a hermetically sealed space “HSS” defined between the cover element 12 and the annular intermediate hollow element 13.

[0055] The sealing capability of the hermetically sealed HSS room is increased by the following sealing construction.

[0056] As in Fig. As shown in Figure 4, two sealing rings 32a and 32b are effectively arranged between an outer cylindrical wall of a cylindrical part of the cover element 12 and an inner cylindrical wall of the annular intermediate hollow element 13. In the illustrated embodiment, the two sealing rings 32a and 32b are inserted into annular grooves (no reference numeral) formed in the outer cylindrical wall of the cylindrical part of the cover element 12. If a large effective sealing capacity of the sealed space is required, an overlap section 31 between the cylindrical part of the cover element 12 and the annular intermediate hollow element 13 is enlarged. The numbers 33a and 33b in the Fig. 4 and Fig. 5 are designated as plug connectors which are arranged to pass through the power input connector part 12A. That is, when the cylindrical part of the cover element 12 is properly placed in the intermediate hollow element 13, the plug connectors 33a and 33b engage with socket connectors 33c and 33d provided by the power circuit part 15.

[0057] As from Fig. Figure 5, which shows the inverted cover element 12, shows a signal connector 34 extending from the bottom side of the cover element 12, which has a plurality of conductor cables 35 whose ends are exposed to the outside, as shown. Fig. As can be seen in Figure 4, when the cover element 12 is properly fitted together with the intermediate hollow element 13 in the manner mentioned above, the signal connector 34 is placed in an opening 36 formed in the heat transfer substrate 14, which causes the exposed ends of the line cables 35 to engage with given circuits of the control circuit part 25.

[0058] As from the Fig. 3 and Fig. As can be seen in Figure 4, the power converter circuit part 21 and the control circuit part 25 are arranged in a space defined between the heat transfer substrate 14 and the circular partition 50 in the motor housing 111.

[0059] As from Fig. As shown in Figure 4, the base plate 22 of the power converter circuit section 21 is snugly placed on the lower surface of the heat transfer substrate 14 and fastened to the substrate 14 by connecting bolts 22a. As shown, the MOSFETs 23 and connecting wires 37 are placed on the lower surface of the base plate 22.

[0060] In most cases, the current circuit section 15 and the power converter circuit section 21 are designed to handle or manage a current whose current-carrying capacity is greater than that of the control circuit section 25. An electric current generated by the power converter circuit section 21 is applied directly to the electric motor EM via busbars (not shown).

[0061] As from Fig. As shown in Figure 4, the heat transfer substrate 14 has both an upper surface, to which the base plate 16 of the power circuit section 15 is attached in a flat and intimate manner and secured by connecting bolts (not shown), and the aforementioned lower surface, to which the base plate 22 of the power converter circuit section 21 is attached in a flat and intimate manner and secured by connecting bolts 22a. With such an intimate connection, any heat generated in the power circuit section 15 and the power converter circuit section 21 is transferred to the heat transfer substrate 14, then to the motor housing 111, and finally to the open air. It should be noted that both the upper and lower surfaces of the heat transfer substrate 14 are used to effectively absorb heat from the power circuit section 15 and the power converter circuit section 21. This arrangement results in a compact thermal radiant design.

[0062] As from Fig. As can be seen in Figure 4, a plurality of support columns 38 of the intermediate hollow element 13 are placed in the space defined between the power converter circuit part 21 and the motor housing 111. The resin substrate 26 of the control circuit part 25 is supported by the support columns 38. As shown, the microcomputer 27 is mounted on a lower surface of the resin substrate 26 of the control circuit part 25.

[0063] As previously mentioned, the signal connector 34 of the cover element 12 is placed in the opening 36 of the heat transfer substrate 14, thus avoiding contact with the current circuit part 15 and the power converter circuit part 21. Accordingly, the line cables 35, held by the signal connector 34, can be connected to specific circuits of the control circuit part 25 without being interrupted by these parts 15 and 21. This arrangement eliminates the need for cable guides or devices, thereby reducing the manufacturing costs of the electric drive device.

[0064] As from Fig. As can be seen in Figure 5, the cover element 12 is equipped with various connectors, including a power connector 33, which connects the aforementioned connectors 33a and 33b; a signal connector 34, which connects the detection sensors to the control circuit section 25; and a drive connector 39, which connects the power converter circuit and the power source. The drive connector 39 is held securely by a flat support section 40.

[0065] As from Fig. As can be seen in Figure 4, both the base plate 22 of the power converter circuit section 21 and the base plate 16 of the current circuit section 15 are positioned behind the resin substrate 26 of the control circuit section 25 with respect to the electric motor "EM". Thus, the resin substrate 26 can serve as a heat shield to protect the two base plates 22 and 16 from the heat of the electric motor "EM".

[0066] As can be seen from the above description, according to the present invention the electronic control device arrangement “ECA” comprises (see Fig. 4) Essentially three axially spaced areas, which are: the uppermost area where the power circuit part 15 is located, mounted on the base plate 16; the middle area where the power converter circuit part 21 is located, mounted on the base plate 22; and the lowermost area where the control circuit part 25 is located, mounted on the resin substrate 26. With this subdivided arrangement, the number of parts mounted on each plate or substrate 16, 22, or 26 can be reduced, and thus the radial size of each plate or substrate 16, 22, or 26 can be reduced.

[0067] Due to the aforementioned segmented arrangement, the axial length of the electronic control device assembly (ECA) is inevitably increased. However, due to the nature of the electric power steering system, this increase in the axial length of the ECA has no noticeable effect on the overall length of the electric power steering system.

[0068] Since the base plate 16 of the current circuit section 15 and the base plate 22 of the power converter circuit section 21 are each placed on the lower and upper surfaces of the heat transfer substrate 14, the heat generated by the circuit sections 15 and 21 can be effectively transferred to the motor housing 111 and thus effectively radiated to the outside. Using the upper and lower surfaces of the heat transfer substrate 14 as a mounting means for the circuit sections 15 and 21 reduces the size of the electronic control device assembly (ECA).

[0069] Since the power circuit part 15, which includes various space-consuming electrical parts, is accommodated in a storage space defined by the relatively long overlapping part 31, effective accommodation of the space-consuming electrical parts in the space is achieved.

[0070] As mentioned above, the present invention provides an electronic control device arrangement divided into three parts in an axial direction, namely: a current circuit part mounted on a metal base plate to mainly generate an electric current, a power converter circuit part mounted on a metal base plate to mainly drive an electric motor, and a control circuit part mounted on a resin plate to mainly control the power converter circuit part, in which a metal heat transfer substrate is installed in a metal housing of the electronic control device arrangement, while it is in contact with an inner wall of the metal housing.and in which the metal base plate of the current circuit section and the metal base plate of the power converter circuit section are intimately and each attached to opposite flat surfaces of the metal heat transfer substrate. With this arrangement, the heat generated by the current circuit section and the power converter circuit section is effectively transferred through the metal heat transfer substrate to the metal housing and radiated from the metal housing to the outside.

[0071] With the aforementioned axially arranged three parts of the electronic control device assembly, the radial size of each – the current circuit, the power converter, and the control circuit – can be reduced. Since the respective metal base plates of the current circuit and power converter circuits are intimately attached to opposing surfaces of the metal heat transfer substrate, which is mounted to the inner wall of the metal housing, the heat generated by the current and power converter circuits is effectively transferred through the metal heat transfer substrate to the metal housing and efficiently radiated from the metal housing to the outside.

[0072] The entire content of Japanese patent application 2014-178802, filed on September 3, 2014, is hereby incorporated by reference.

[0073] Although the invention has been described above with reference to embodiments of the invention, the invention is not limited to such embodiments as described above. Various modifications and variants of such embodiments can be carried out by those skilled in the art in light of the above description.

Claims

An electric drive device (1) for driving a machine system, comprising: an electric motor (EM) having an output shaft (OS) through which control elements of the machine system are driven; and an electronic control unit (9) located at a position opposite the position where the output shaft (OS) of the electric motor (EM) is located, wherein the electronic control unit (9) comprises a cylindrical metal housing (111) with a bottom wall having the electric motor (EM) connected thereto, and an electronic control device assembly (ECA) installed in the cylindrical metal housing (111) to control the operation of the electric motor (EM), wherein the electronic control device assembly (ECA) is divided into three parts installed coaxially in the cylindrical housing (111) in a sequence, the three parts being: a current circuit part (15),a power converter circuit part (21) mounted on a metal base plate (16) and mainly generating an electric current, a power converter circuit part (21) mounted on a metal base plate (22) and mainly driving the electric motor (EM), and a control circuit part (25) mounted on a resin plate (26) and mainly controlling the power converter circuit part (21), wherein a metal heat transfer substrate (14) is installed in the cylindrical metal housing (111) and is in contact with an inner wall of the cylindrical metal housing (111) at a cylindrical outer wall thereof; and wherein the metal base plate (16) of the power circuit part (15) and the metal base plate (22) of the power converter circuit part (21) are intimately connected to opposing flat surfaces of the metal heat transfer substrate (14). Electric drive device according to claim 1, wherein the metal heat transfer substrate (14) is installed in the cylindrical metal housing (111) by means of an intermediate hollow element (13), and wherein a cover element (12) is connected to the intermediate hollow element (111) in such a way as to close an open end of the intermediate hollow element (13), the cover element being provided with a plurality of connectors (12A, 12B, 12C). Electric drive device according to claim 2, wherein the intermediate hollow element (13) consists of either a metal or a synthetic resin. Electric drive device according to claim 2, wherein the current circuit part (15) is installed in a space defined between the cover element (12) and the intermediate hollow element (13), the metal base plate (16) of the current circuit part (15) is intimately connected with a surface of the metal heat transfer substrate (14), the power converter circuit part (21) is installed in a space defined between the cylindrical metal housing (111) and the intermediate hollow element (13), the metal base plate (22) of the power converter circuit part (21) is intimately connected with the other surface of the metal heat transfer substrate (14), and the control circuit part (25) is installed in a space defined between the power converter circuit part (21) and the electric motor (EM). Electric drive device according to claim 2, wherein a contact / overlap area (31), where the intermediate hollow element (13) and the cover element (12) are in contact and overlap each other, is equipped with two sealing rings (32a, 32b) to provide a hermetically sealed space for accommodating electrical elements of the current circuit part (15). Electric drive device according to claim 4, wherein the connectors (12A, 12B, 12C) of the cover element (12) are directly connected to printed wiring patterns on the metal base plates (16, 22) of the current and power transformer circuit parts (15, 21) without the use of cable guide parts. Electric drive device according to claim 6, wherein the connectors connected to the power conversion and control circuit parts are embedded in a guide section (34) which is integrally provided by the cover element (12) and in which the guide section (34) extends to the power conversion and control circuit parts (21, 25) through a guide opening (36) formed in the metal heat transfer substrate (14). Electric power steering device (1) of a motor vehicle, comprising: an electric motor (EM) having an output shaft (OS) through which a power steering force is exerted on a steering shaft of the vehicle; and an electronic control unit (9) for controlling the electric motor (EM), wherein the electronic control unit (9) is arranged at a position opposite the position where the output shaft (OS) of the electric motor (EM) extends; and a cylindrical housing (111) having a base to which the electric motor (EM) is connected; and an electronic control device assembly (ECA) installed in the cylindrical housing to control the operation of the electric motor (EM), wherein the electronic control device assembly (ECA) is divided into three parts which are installed coaxially in the cylindrical housing (111) in a sequence, the three parts being: a current circuit part (15);a current converter circuit part (21) mounted on a metal base plate (16) and mainly generating an electric current, a power converter circuit part (21) mounted on a metal base plate (22) and mainly driving the electric motor (EM), and a control circuit part (25) mounted on a resin plate (26) and mainly controlling the power converter circuit part, wherein a metal heat transfer substrate (14) is installed in the cylindrical metal housing (111) while in contact with an inner wall of the cylindrical metal housing (111) at a cylindrical outer wall thereof; and wherein the metal base plate (16) of the current circuit part (15) and the metal base plate (22) of the power converter circuit part (21) are intimately connected to opposing flat surfaces of the metal heat transfer substrate (14). Electric power steering device according to claim 8, wherein the metal heat transfer substrate (14) is installed in the cylindrical metal housing (111) by means of an intermediate hollow element (13), and wherein a cover element (12) is connected to the intermediate hollow element (13) in such a way as to close an open end of the intermediate hollow element (13), the cover element being provided with a plurality of connectors. Electric power steering device according to claim 9, wherein the intermediate hollow element (13) consists of either a metal or a synthetic resin. Electric power steering device according to claim 9, wherein the current circuit part (15) is installed in a space defined between the cover element (12) and the intermediate hollow element (13), the metal base plate (16) of the current circuit part (15) is intimately connected with a surface of the metal heat transfer substrate (14), the power converter circuit part (21) is installed in a space defined between the cylindrical metal housing (111) and the intermediate hollow element (13), the metal base plate (22) of the power converter circuit part (21) is intimately connected with the other surface of the metal heat transfer substrate (14), and the control circuit part (25) is installed in a space defined between the power converter circuit part (21) and the electric motor (EM). Electric power steering device according to claim 9, wherein a contact / overlap area (31), where the intermediate hollow element (13) and the cover element (12) are in contact and overlap each other, is equipped with two sealing rings (32a, 32b) to provide a hermetically sealed space for accommodating electrical elements of the current circuit part (15). Electric power steering device according to claim 11, wherein the connectors (12A, 12B, 12C) of the cover element (12) are directly connected to printed wiring patterns on the metal base plates (16, 22) of the current and power converter circuit parts (15, 21) without the use of cable guide parts. Electric power steering device according to claim 13, wherein the connectors connected to the power conversion and control circuit parts are embedded in a guide section (34) which is integrally provided by the cover element (12) and in which the guide section (34) extends to the power conversion and control circuit parts (21, 25) through a guide opening (36) formed in the metal heat transfer substrate (14). An electric power steering device for a motor vehicle, comprising: a cylindrical metal housing (111) having a first, second, third and fourth chamber arranged coaxially in a sequence; an electric motor (EM) located in the fourth chamber and having an output shaft (OS) through which a power steering force is exerted on a steering shaft (2) of the motor vehicle; a current circuit part (15) located in the first chamber and comprising a first metal base plate (16) and electrical elements mounted on the first metal base plate (16); a power conversion circuit part (21) located in the second chamber and comprising a second metal base plate (22) and electrical elements mounted on the second metal base plate (22); a control circuit part (25) located in the third chamber and comprising electrical elements;a circular metal heat transfer substrate (14) arranged in the cylindrical metal housing (111) between the first and second chambers, the circular metal heat transfer substrate (14) having a cylindrical outer wall in contact with an inner cylindrical surface of the cylindrical metal housing (111), an upper flat surface with which the first metal base plate (16) is intimately connected, and a lower flat surface with which the second metal base plate (22) is intimately connected; and a cover element (12) connected to an open end of the cylindrical metal housing (111).

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