JP2009268266A - Starter motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the startability of an engine while miniaturizing a starter motor installed inside a crank pulley. <P>SOLUTION: In the starter motor 29, a plurality of coils 34 disposed in the outer peripheral part of a stator 31 fixed to a cylinder block, and a plurality of permanent magnets 37 disposed in the inner peripheral part of an annular rotor 32 fixed to a crank shaft 17 and surrounding the outside in the radial direction of the stator 31, are opposed to one another via an air gap g in the radial direction. The permanent magnets 37 are movably provided on the rotor 32 in the radial direction. Then, characteristics of a torque type motor are given to the starter motor by arranging the permanent magnets 37 closer to the coils 34 of the stator 31 or the characteristics of a rotation type motor are given to the starter motor by arranging the permanent magnets 37 away from the coils 34 of the stator 31, so that starting performance of the engine is improved. Besides, the permanent magnets 37 are moved in the radial direction of the rotor 32, thereby preventing an increase in the dimension of the starter motor 29 in the axis direction. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention includes a stator fixed to an engine body, and an annular rotor fixed to a crankshaft penetrating the center of the stator and surrounding a radially outer side of the stator, and is disposed on an outer peripheral portion of the stator The present invention relates to a starter motor in which a plurality of coils and a plurality of permanent magnets arranged on an inner peripheral portion of the rotor are opposed to each other through a radial air gap.

A motor / generator is housed in a crank pulley that is provided on the crankshaft of the engine and drives auxiliary machinery via an endless belt, and the crankshaft is driven by driving the motor / generator as a starter motor when the engine is started. Japanese Patent Application Laid-Open Publication No. 2004-228688 discloses a technique of generating power by ranking and starting an engine and driving a motor / generator as a generator after the engine is started.
Japanese Patent No. 3777272

  By the way, at the start of cranking by the starter motor, a large torque exceeding the piston load in the compression process is required. Therefore, it is desirable that the starter motor has a torque type characteristic capable of generating a large torque, and cranking is started. In order to increase the cranking speed and start the engine in a short time during the period from the start to the complete explosion, it is desirable that the starter motor has a high rotational speed characteristic.

  However, since it is difficult to combine the above two characteristics with a single motor / generator, a motor / generator capable of generating a large torque and capable of high rotation is required. There was a problem that led to

  The present invention has been made in view of the above circumstances, and an object of the present invention is to improve engine startability while reducing the size of a starter motor provided inside a crank pulley.

  In order to achieve the above object, according to the first aspect of the present invention, a stator fixed to the engine body, and a crankshaft penetrating the center of the stator are fixed to surround a radially outer side of the stator. A starter motor comprising an annular rotor, wherein a plurality of coils disposed on an outer peripheral portion of the stator and a plurality of permanent magnets disposed on an inner peripheral portion of the rotor are opposed to each other via a radial air gap. A starter motor is proposed in which the permanent magnet is provided on the rotor so as to be movable in a radial direction.

  According to the second aspect of the present invention, in addition to the configuration of the first aspect, the permanent magnet is supported by the guide means provided on the rotor so as to be slidable in the radial direction, and is capable of compression deformation. A starter motor is proposed which is biased radially inward by a member to a minimum air gap position.

  According to the invention described in claim 3, in addition to the structure of claim 1 or 2, a starter motor is proposed in which the main body of the rotor is made of a magnetic material.

  According to the invention described in claim 4, in addition to the structure of any one of claims 1 to 3, when the rotor rotates with the driving force of the crankshaft, it cooperates with the stator. A starter motor characterized by functioning as a generator is proposed.

  The chain cover 26 of the embodiment corresponds to the engine body of the present invention, the pulley body 35 of the embodiment corresponds to the main body of the rotor of the present invention, and the guide groove 35a and the guide member 36 of the embodiment are Corresponding to the guide means of the present invention, the leaf spring 39 of the embodiment corresponds to the elastic member of the present invention.

  According to the configuration of the first aspect, the plurality of coils disposed on the outer peripheral portion of the stator fixed to the engine body and the inner peripheral portion of the annular rotor fixed to the crankshaft and surrounding the outer side in the radial direction of the stator. In a starter motor in which a plurality of permanent magnets are opposed to each other via a radial air gap, the permanent magnet is provided on the rotor so as to be movable in the radial direction. The engine starting performance can be improved by giving the characteristics of the motor or by providing the characteristics of the rotary motor by moving the permanent magnet away from the stator coil. Moreover, since the permanent magnet moves in the radial direction of the rotor, it is possible to prevent an increase in the axial dimension of the motor.

  According to the second aspect of the present invention, the permanent magnet is supported by the guide means provided on the rotor so as to be slidable in the radial direction, and is urged radially inward to the minimum air gap position by the elastically deformable resilient member. Therefore, as the rotational speed of the rotor increases, the permanent magnet automatically moves outward in the radial direction while compressing the elastic member by centrifugal force. As a result, immediately after the start of the starter motor, the air gap can be reduced to exhibit the characteristics of the torque type motor, and crankshaft cranking can be started with sufficient torque. Further, in the region from the starter motor driving to the complete explosion of the engine, the air gap can be increased to exhibit the characteristics of the rotary motor, and the engine can be started in a short time to save power consumption.

  According to the third aspect of the present invention, since the main body of the rotor is made of a magnetic material, the magnetic flux passing through the main body of the rotor efficiently increases and passes through the stator when the permanent magnet moves radially outward. The magnetic flux is efficiently reduced, and the characteristics of both the torque type motor and the rotary type motor can be exhibited remarkably.

  According to the fourth aspect of the present invention, when the rotor rotates with the driving force of the crankshaft, it functions as a generator in cooperation with the stator. Therefore, during operation of the engine, the starter motor functions as a generator to generate electric power. By eliminating the special generator, the number of parts and the cost can be reduced.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

  1 to 7 show an embodiment of the present invention. FIG. 1 is a front view of the engine, FIG. 2 is an enlarged sectional view taken along line 2-2 in FIG. 1, and FIG. 3 is a sectional view taken along line 3-3 in FIG. FIG. 4 is an operation explanatory diagram corresponding to FIG. 3 (during medium speed rotation), FIG. 5 is an operation explanatory diagram corresponding to FIG. 3 (during high speed rotation), and FIG. FIG. 7 is a graph showing the amount of power generated by the starter motor with respect to the engine speed.

  As shown in FIG. 1, an accessory part mounting bracket 12 is fixed to a side surface of a cylinder block 11 of a multi-cylinder engine E mounted on a vehicle, and a power steering oil pump 13 is attached to the accessory part mounting bracket 12. The auto tensioner 14, the engine cooling water pump 15, and the air conditioning compressor 16 are fixed. A crank pulley 18 provided at the shaft end of the crankshaft 17 of the engine E, an oil pump drive pulley 19 provided in the oil pump 13, a tensioner pulley 20 provided in the auto tensioner 14, and a water pump drive provided in the water pump 15. A single endless belt 23 is wound around a pulley 21 and a compressor driving pulley 22 provided in the compressor 16, and the driving force of the crankshaft 17 is driven by the oil pump 13, the water pump 15 and the compressor 16 by the endless belt 23. And tension is applied to the endless belt 23 by the auto tensioner 14.

  As apparent from FIGS. 2 and 3, a drive sprocket 25 around which a timing chain 24 for driving the valve operating mechanism is wound is integrally formed on the crankshaft 17 protruding from the side surface of the cylinder block 11. The drive sprocket 25 is covered with a chain cover 26 fixed to the cylinder block 11. The crank pulley 18 is fitted to the shaft end of the crankshaft 17 protruding from the chain cover 26 and is fixed by a key 27 and a nut 28.

  The starter motor 29 disposed inside the crank pulley 18 is a motor / generator that can also be used as a generator, and includes an annular stator 31 fixed to the outer surface of the chain cover 26 by a plurality of bolts 30. It is comprised with the cyclic | annular rotor 32 fixed to the inner surface of the crank pulley 18 so that the outer periphery of 31 may be enclosed.

  The stator 31 includes an annular stator core 33 in which a large number of silicon steel plates are laminated, and a plurality of coils 34 wound around a plurality of teeth 33 a protruding from the outer peripheral surface of the stator core 33. Are fixed to the chain cover 26 with the bolts 30 penetrating the shaft.

  The rotor 32 uses a pulley body 35 made of a magnetic material as a back iron, and a plurality of (six in the embodiment) guide grooves 35a... That are recessed radially outward are formed on the inner peripheral surface thereof. At the same time, guide members 36... Protrude radially inward from the open ends of the guide grooves 35 a. The guide grooves 35a and the guide members 36 constitute the guide means of the present invention, and the permanent magnets 37 are fitted therein so as to be slidable in the radial direction. A sub back iron 38 is fixed to the outer peripheral surface of each permanent magnet 37, and a curved leaf spring 39 is disposed between the bottom of the guide groove 35 a and the sub back iron 38.

  When the crank pulley 18 is not rotating, the permanent magnet 37 integrated with the sub-back iron 38 is urged radially inward by the elastic force of the leaf spring 39 and is locked to the guide members 36, 36. (See FIG. 3). At this time, the air gap g between the permanent magnet 37 and the coil 34 is minimized. When the crank pulley 18 rotates, the permanent magnet 37 moves radially outward while compressing the leaf spring 39 by centrifugal force, so that the rotational speed of the crank pulley 18 exceeds a predetermined value and the leaf spring 39 becomes incompressible any more. When this occurs, the air gap g between the permanent magnet 37 and the coil 34 is maximized (see FIG. 5).

  Next, the operation of the embodiment of the present invention having the above configuration will be described.

  In order to start the engine E, the starter motor 29 is energized to function as a motor. That is, when a current is passed through the coils 34 of the stator 31 fixed to the chain cover 26 to drive the starter motor 29, a magnetic flux passing through the stator 31 and the rotor 32 is generated as shown in FIG. Torque acts to rotate the crank pulley 18, crank the crankshaft 17 to which the crank pulley 18 is fixed, and start the engine E.

  Since the centrifugal force does not act on the permanent magnets 37 (and sub-back irons 38) when the rotor 32 stops rotating, the permanent magnets 37 are guided by the elastic force of the leaf springs 39. The air gap g between the stator 31 and the rotor 32 is in a minimum state. Accordingly, the magnetic flux passing through the stator 31 and the rotor 32 increases, and the starter motor 29 functions as a torque type motor, and generates a large torque for the same current. When starting cranking of the engine E, a large torque is required to overcome the static friction force acting on the crankshaft 17 and the piston and push the piston up to the top dead center in the compression stroke. As a result, the cranking of the engine E can be started by generating necessary torque without increasing the size of the starter motor 29 (see FIG. 3).

  When the cranking of the engine E is started in this way, the permanent magnets 37 are resisted against the leaf springs 39 by the centrifugal force acting with the rotation of the rotor 32 until the engine E reaches a complete explosion state. Since the air gap g increases and the magnetic flux passing through the stator 31 and the rotor 32 decreases by moving to the intermediate position radially outward (see FIG. 4), the characteristics of the starter motor 29 rotate from the torque type. The engine E can be started quickly by increasing the cranking speed by increasing the rotational speed.

  FIG. 6 is a graph showing the current flowing through the starter motor 29 when the engine E is started. In the embodiment shown by the solid line compared to the conventional example shown by the broken line, the start is completed in a short time and the power consumption is reduced. You can see that

  Further, after the engine E is started, the rotational speed of the rotor 32 is sufficiently increased and the centrifugal force is increased, so that the permanent magnets 37 move to the radially outer end position against the leaf springs 39 (see FIG. 5), the air gap g is maximized. Conventionally, even if the starter motor 29 is not driven, a torque that overcomes the detent torque (cogging torque) is required to rotate the rotor 32 relative to the stator 31, and the driving force of the engine E is wasted accordingly. There was a problem that was consumed. However, according to the present embodiment, at the time of high-speed rotation after the engine E is started, the detent torque is reduced by automatically increasing the air gap g by the centrifugal force, and the driving power of the engine E is wasted. It can be avoided.

  Further, during operation of the engine, the starter motor 29 can function as a generator to generate electric power, so that it is not necessary to provide a special generator, which can contribute to the reduction in the number of parts and cost.

  When power generation is performed by causing the starter motor 29 to function as a generator, the permanent magnets 37 move radially inward during the low-speed rotation of the engine E, which tends to have a shortage of power generation, and the air gap g becomes smaller. When the engine E is rotating at high speed, the amount of power automatically increases and the amount of power generation tends to be excessive, the permanent magnets 37 move radially outward and the air gap g increases to automatically reduce the amount of power generation. In addition, a stable power generation amount can always be ensured regardless of the rotational speed of the engine E.

  FIG. 7 is a graph showing the relationship between the output current and the rotation speed when the starter motor 29 functions as a generator. In the conventional example, the rise of the output current is delayed in the low rotation speed region immediately after the start of rotation. In contrast, in the present embodiment, it can be seen that a sufficient output current can be obtained immediately after the start of rotation.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various design changes can be made without departing from the present invention described in the claims. Is possible.

  For example, in the embodiment, the resilient means for urging the permanent magnet 37 is constituted by the leaf spring 39, but an arbitrary spring other than the leaf spring 39 or an elastic body such as rubber can be used.

  In the embodiment, a motor / generator is used as the starter motor 29. However, a simple motor that does not function as a generator may be used.

  In the embodiment, the stator 31 is fixed to the chain cover 26. However, the stator 31 can be fixed to a cover such as a belt cover or a gear cover, and when the cover is formed integrally with the cylinder block 11, The stator 31 can be fixed to the cylinder block 11.

Front view of the engine 2-2 line enlarged sectional view of FIG. Sectional view along line 3-3 in FIG. 2 (when stopped or rotating at low speed) Action explanatory diagram corresponding to FIG. 3 (at the time of medium speed rotation) Action explanatory diagram corresponding to FIG. 3 (at high speed rotation) Graph showing the current flowing to the starter motor when the engine starts Graph showing the amount of power generated by the starter motor with respect to engine speed

Explanation of symbols

17 Crankshaft 26 Chain cover (Engine body)
31 Stator 32 Rotor 34 Coil 35 Pulley body (rotor body)
35a Guide groove (guide means)
36 Guide member (guide means)
37 Permanent magnet 39 Leaf spring (elastic member)
g Air gap

Claims (4)

A stator (31) fixed to the engine body (26), and an annular rotor (32) fixed to a crankshaft (17) passing through the center of the stator (31) and surrounding the radial outer side of the stator (31) ), And a plurality of coils (34) disposed on the outer peripheral portion of the stator (31) and a plurality of permanent magnets (37) disposed on the inner peripheral portion of the rotor (32). In the starter motor opposed through the gap (g),
The said permanent magnet (37) is provided in the said rotor (32) so that a movement to radial direction is possible, The starter motor characterized by the above-mentioned.   The permanent magnet (37) is supported by a guide means (35a, 36) provided on the rotor (32) so as to be slidable in the radial direction, and is moved to a minimum air gap position by a resiliently deformable resilient member (39). The starter motor according to claim 1, wherein the starter motor is biased radially inward.   The starter motor according to claim 1 or 2, wherein the main body (35) of the rotor (32) is made of a magnetic material.   When the rotor (32) rotates with the driving force of the crankshaft (17), it functions as a generator in cooperation with the stator (31). The starter motor according to item 1.

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