A device for starting an engine and generating power

Abstract: A device for starting an engine and generating power comprising a frame (3) attached to a main body (1) of an engine, a stator core (4) fixed in the frame and attached with a stator coil (5), a field core (6) attached to an inner end face of the frame, having a clearance in the radial direction between the field core and an inner peripheral portion of the stator core and accommodating a field coil (7), a claw-pole type rotating field electrodes (9) disposed between the stator core and the field core interposing air-gaps respectively among the field electrodes, the stator core and the field core, a driving shaft (13) passing through an inner diameter portion of the field core and supported thereby through bearings (14), a planetary gear device (15) interposed between a crankshaft (2) and the driving shaft (13) an end portion of which is fixed with a sun gear (18) which decelerates and transmits first rotation of the driving shaft to the crankshaft in starting an engine and accelerates and transmits second rotation of the crankshaft to the driving shaft in generating power, a transmission supporting body (27) attached to an end portion of the driving shaft, provided with a plurality of blades (27a) for serving as a fan on an outer end face thereof and attached with and supporting the rotating field electrodes, and a front cover (30) attached to a front portion of the frame, surrounding the transmission supporting body and provided with intake openings (30a) for a cooling wind at an outer end portion thereof.

Description: This invention relates to a device for starting an engine and generating power which is connected to an internal combustion engine, for starting the engine as a starting motor and serving as a generator after the starting. In a general conventional device for starting an engine and generating power attached with a planetary gear, as shown for instance, in Japanese Unexamined Patent Publication No. 81563/1991, no special cooling device is provided for an armature coil and a field coil. Figure 4 is a sectional diagram showing a conventional device for starting an engine and generating power. As shown in Figure 4, the device is constructed by a rotating body 103 integrated with a first rotor 101a and a second rotor 101b by a ring 102, a field coil 105 wound with a field core 104, and an armature coil 106 as major components. This device is not provided with an equipment for cooling the armature coil and the field coil. There are devices of this kind each of which cools an armature coil and a field coil, disclosed for instance, in Japanese Patent Publication No. 198556/1988 and Japanese Unexamined Patent Publication No. 202257/1988. In both devices for starting up an engine and charging electricity, rotating field poles are attached to a crankshaft of an engine and the field poles are excited by excitation coils. Stator cores provided with stator coils are attached to main bodies of the engines. In starting, power is supplied to the excitation coil and an AC voltage having a low frequency is supplied to the stator coil thereby synchronizingly rotating the rotating field poles and the device transmits the rotation to the engine as a starting motor. By increasing the frequency of the supplied AC voltage, the rotation of the rotating field poles is increased thereby starting the engine. When the engine is started, the supply of the AC voltage to the stator coil is stopped. Since the rotating field poles are rotated by a crankshaft, an AC voltage is generated in the stator coil, and the device charges electricity through a rectifier as a generator. In the former device for starting an engine and charging electricity, a cooling solution of the engine per se flows in a cooling water passage surroundingly provided at a back portion of an assembly of the stator core and the stator coil thereby cooling the device. Furthermore, in the latter device for starting an engine and charging electricity, a thermally conductive ring is provided between a cylinder block or a bracket and a transmission case through a thermally conductive seal cover. A thermally conductive gel is sealed among the cylinder block or the bracket, an inter peripheral portion of the ring and an outer peripheral portion of the stator coil. The heat of the stator coil is transferred to the cylinder block or the bracket and the ring through the thermally conductive gel thereby cooling the device. In such a conventional device for starting an engine and charging electricity, the rotating field poles are directly connected to the crankshaft. In starting, a large torque output is required at a low speed rotation. Therefore, the device is magnified. Since the revolution speed is below a pertinent value in power generating, the output can not be enhanced. Furthermore, a sealing means is required for the passage of the cooling solution or the thermally conductive gel. Therefore, the structure thereof is complicated, the fabrication thereof is difficult, the price thereof is elevated, and a large amount of time is required for check and maintenance thereof. A combined electric starter and alternator system for starting an engine and generating power known from US-A-4 862 009 comprises a frame or housing which is attachable to the main body of an engine. A stator of an electric machine is fixly mounted in the housing surrounding a rotor of the machine. The rotor is mounted on a driving shaft one end of which is supported by means of a bearing in a cover plate of the housing and the other end of which is connected via a planetary gear to a crankshaft of the engine. In order to provide a torque multiplication in a starting mode and 1:1 coupling between the crankshaft and the driving shaft after the engine has been started one-way clutches are arranged between the housing and the planetary gear. A special cooling device for cooling the electric machine is not provided in this system. Another known electric machine (US-A-4 162 419) which is used only as an alternator comprises a two-part housing including a front and a rear portion. The front portion is attachable to an engine. A stator core is fixed in the housing and attached with a stator coil while a field core is attached to an inner end face of the rear portion of the housing and accommodates a field coil. A driving shaft passes through an inner diameter portion of the field core and is supported through bearings in an intermediate wall of the rear portion and an end wall of the front portion. A cup-shaped ferromagnetic member is connected to the driving shaft. The radially outer peripherie of the cup-shaped member is provided with a series of pole fingers extending in the clearance between the stator core and the field core. A further ferromagnetic member provided with pole fingers is connected with the cup-shaped member by means of a coupling ring for forming claw-pole type rotating field electrodes. The further ferromagnetic member of the claw-pole type rotating field electrodes is provided with blades extending toward the intermediate wall of the rear portion which includes appertures for drawing cooling air through a part of the housing which is located outside the chamber for accommodating the electric machine and which accommodates a rectifier assembly. It is the object of the present invention to provide a device for starting an engine and generating power which has a simple and compact structure and includes a cooling system which effectively performs the cooling of the device. This object is achieved by a device according to claim 1. In accordance with the present invention a simple and compact structure of the device is achieved by attaching the field core to an inner end face of the frame which is attachable to the main body of an engine and by supporting the driving shaft by the field core through bearings. Further, a simple cooling system is obtained by providing the transmission body for connecting the rotating field electrodes to the driving shaft with blades so that the transmission supporting body serves as a fan. Thus, the fabrication of the device is easy and time and labor for the check and maintenance is safed. In the drawings: Figure 1 is a longitudinal sectional diagram of an embodiment of a device for starting an engine and generating power according to the present invention; Figure 2 is a front sectional view showing ventilation passages of a frame in Figure 1; Figure 3 is a front sectional view showing ventilation passages of a frame in embodiment 2 of this invention; and Figure 4 is a sectional diagram showing a conventional device for starting an engine and generating power. EXAMPLE 1 Figure 1 is a longitudinal sectional diagram of a device for starting an engine and generating power according to the present invention. A reference numeral 1 designates an engine main body wherein a flange of a crankshaft 2 is provided. A numeral 3 designates a frame fixed to a front end of the engine main body 1, composed, for instance, of an aluminum material and provided with a great number of axial ventilation passages 3b at the inner peripheral portion thereof and a great number of exhaust openings 3a at a rear end portion thereof. A numeral 4 designates a stator core fixed to the inner peripheral portion of the frame 3 which is provided with a stator coil 5 of a three-phase winding. A numeral 6 designates a field core fixed to an end face of the engine main body by a bolt 8, which is wound with a field coil 7. A numeral 9 designates rotating field poles disposed between the stator core 4 and the field core 6 having respectively air-gaps among them, which are consisted of field poles 10 and 11 connected to a nonmagnetic connecting ring 12 by welding or the like and arranged at both sides of the connecting ring. Claw poles 10a and lla are protruded from the field poles 10 and 11 alternately with respect to the circumferential direction. A numeral 13 designates a driving shaft which passes through an inner diameter portion of the field core 6 and is supported thereby through bearings 14, and 15 a planetary gear device constructed as follows. A numeral 16 designates a transmission body supported by the driving shaft 13 through a bearing 17, which is fixed and connected to a flange of the crankshaft 2. A numeral 18 designates a sun gear fixed to the driving shaft 13, 19 an inner gear fixed to the inside of the frame 3 which is pushed to fix by a fixing ring 20,and 21 a plurality of planetary gears meshed with the sun gear 18 and the inner gear 19, which spin and orbitally rotate around the sun gear, and which is supported by supporting pins 22 the end portions of which are fixed to the transmission body 16 through bearings 23. A numeral 25 designates a spacing ring, and 26 a pair of thrust bearings which contact the both ends of the sun gear 18. Next, a numeral 27 designates a transmission supporting body which is fixed to a flange 15a at the front portion of the driving shaft 13 by bolts 28, which is attached with field poles 10 by bolts 29 at an outer periphery side of an inner end face thereof for supporting the rotating field poles 9. A plurality of blades 27a are provided at the transmission supporting body 27, which also serves as a fan. A numeral 30 designates a front cover attached to the front end of the frame 3 by bolts 31, the front end portion of which is provided with a plurality of intake openings 30a, and at an inner periphery on the outer diameter side thereof, ventilation passages 30b communicating to the respective ventilation passages 3b of the frame 3, are provided. At the front end portion of the driving shaft 13, a rotating body 32 provided with a great number of teeth is provided by a fixing screw 33. At the front portion of the front cover 30, a plurality of angle detectors 34 corresponding to the teeth, are attached, which detect the position of the rotating field poles 9. A numeral 35 designates an oil seal attached to the field core 6. A numeral 36 designates an end lid attached to the front portion of the front cover 30 by bolts 37. Figure 2 is a front sectional diagram of the stator core of the frame 3 of Figure 1. A great number of the axial ventilation passages 3b are provided at the inner peripheral portion of the frame 3. Next, explanation will be given to the operation. In starting the engine, power is supplied to the excitation coil 7 and a three-phase AC voltage having a low frequency is supplied to the stator coil 5. In this way, the rotating field poles 9 are rotated at a low speed by the device as a starting motor and the rotation is transmitted to the sun gear 18 through the transmission supporting body 27 and the driving shaft 13. The rotation is decelerated through the planetary gear device 15 and rotates the crankshaft 2. The position of the rotating field poles 9 is detected by the angle detectors 34. By a control means (not shown) the frequency of the three-phase AC voltage of the stator coils 5 is gradually increased and the phase thereof is controlled, thereby elevating the revolution number to a value required for the starting. When the engine is started, the application of the voltage to the stator coil 5 is stopped. When the engine has been started, the rotation of the crankshaft 2 is accelerated through the planetary gear device 15 and rotates the rotating field poles 9 through the driving shaft 13 and the transmission supporting body 27. In this way, the device generates the three-phase AC voltage as a three-phase AC generator. This three-phase AC voltage is supplied to a driving motor (not shown) of a vehicle thereby running the vehicle by the rotation. Furthermore, the three-phase AC voltage is converted into a DC voltage through a rectifier (not shown) which is supplied to a storage battery for charging electricity and to DC loads. On the other hand, the cooling operation of the device for starting an engine and generating power is as follows. By the rotation of the transmission supporting body 27 which also serves as a fun, a cooling wind is introduced from the intake openings 30a, which flows through the ventilation passages 30b and 3b and is exhausted through the exhaust openings 3a. In this way, the stator coil 5 and the stator core 4 are effectively cooled. EXAMPLE 2 Figure 3 is a front sectional diagram showing embodiment 2 of a stator core of the frame according to the present invention. A great number of cooling fins 40 are provided at the outer periphery of the frame 3. By a fanning action due to the rotation of the transmission supporting body 27, the temperature of the cooling wind passing through the ventilation passages 3b is gradually elevated which is caused by cooling the stator. However, the heat dissipation from the cooling fins 40 of the frame 3 is promoted thereby enhancing the cooling effect all the more. EXAMPLE 3 In the above Examples, the field coils 7 are directly wound in the field core 6 through an insulator. However, the field core may be divided in the axial direction and the field cores which are wound in coil bobbins may be accommodated in both directions and integrated. As stated above, according to the present invention, the armature coil and the field coil are cooled down. As stated above, according to the present invention, the stator is fixed in the frame which is attached to the engine main body and the field core attached with the field coil is provided therein. The claw-pole type rotating field poles are arranged between the inner peripheral portion of the stator core and the outer peripheral portion of the field core respectively interposing air gaps among them. The driving shaft is connected to the crankshaft through the planetary gear device. The rotating field poles are fixed to and supported by the transmission supporting body which is fixed to the front end side of the driving shaft. Therefore, the functions of starting an engine and generating power are combined by a single body. Moreover, pertinent rotational speeds are provided for the both functions, which downsizes the device. Furthermore, the outer end phase of the transmission supporting body is provided with the blades which constitute a fan. The ventilation passages are provided between the inner portion of the frame and the back portion of the stator core, thereby flowing the cooling wind by the fan. Accordingly, the device is provided with a simple structure, the fabrication thereof is easy and the cooling of the stator is effectively performed.

Claims: A device for starting an engine and generating power comprising: a frame (3) attached to a main body (1) of an engine; a stator core (4) fixed in the frame (3) and attached with a stator coil (5); a field core (6) attached to an inner end face of the frame (3), having a clearance in the radial direction between the field core (6) and an inner peripheral portion of the stator core (4) and accommodating a field coil (7); a claw-pole type rotating field electrodes (9) disposed between the stator core (4) and the field core (6) interposing air-gaps respectively among the field electrodes (9), the stator core (4) and the field core (6); a driving shaft (13) passing through an inner diameter portion of the field core (6) and supported thereby through bearings (14); a planetary gear device (15) interposed between a crankshaft (2) and the driving shaft (13) an end portion of which is fixed with a sun gear (18) which decelerates and transmits first rotation of the driving shaft (13) to the crankshaft (2) in starting an engine and accelerates and transmits second rotation of the crankshaft (2) to the driving shaft (13) in generating power; a transmission supporting body (27) attached to an end portion of the driving shaft (13), provided with a plurality of blades (27a) for serving as a fan on an outer end face thereof and attached with and supporting the rotating field electrodes (9); and a front cover (30) attached to a front portion of the frame (3), surrounding the transmission supporting body (27) and provided with intake openings (30a) for a cooling wind at an outer end portion thereof. The device according to claim 1, further comprising: a plurality of ventilation passages (3b) provided at a back face of the stator core (4) in an inner portion of the frame (3). The device according to claim 2 further comprising: a plurality of cooling fins (40) at an outer peripheral portion of the frame (3).

Inventors: ODAHARA KAZUHIRO, SUGIYAMA TAKESHI, ODAHARA, KAZUHIRO, MITSUBISHI DENKI ENGINEERING, SUGIYAMA, TAKESHI, MITSUBISHI DENKI K.K.
Applicants: MITSUBISHI ELECTRIC CORP, MITSUBISHI DENKI KABUSHIKI KAISHA
Application year: 1992
Main classification: F02N11
IPC codes: H02K9, H02K19, H02K7, H02K5, F02N11