1
FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
[See section 10, Rule 13]
ROTARY ELECTRIC MACHINE;
MITSUBISHI ELECTRIC CORPORATION, A CORPORATION
ORGANISED AND EXISTING UNDER THE LAWS OF JAPAN, WHOSE
ADDRESS IS 7-3, MARUNOUCHI 2-CHOME, CHIYODA-KU, TOKYO
1008310, JAPAN
THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE
INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED.
2
Description
Technical Field
[0001] The present invention relates to a controller-integrated type rotating
electric machine in which a controller is mounted.
5
Background Art
[0002] A controller-integrated type rotating electric machine in which a rotating
electric machine is integrated with a controller, there is known an alternator for a
vehicle (see, for example, Patent Literature 1). The alternator for a vehicle,
10 which is described in Patent Literature 1, includes a field core, a spacer, a
bearing component, and a pulley in the stated order from a counter-belt drive
side as components to be provided to a rotary shaft together with a nut on a belt
drive side being one free end of the rotary shaft.
[0003] Hitherto, in the alternator for a vehicle, an input torque is applied to the
15 pulley from an engine side via a belt to rotate the pulley. When the pulley is
rotated, the components mounted to the rotary shaft are rotated via a screw
threaded on one end of the rotary shaft and the nut mounted on the screw.
Specifically, the alternator for a vehicle has such a structure that, when the
pulley is rotated, the pulley and the other fastened components can be integrally
20 rotated by a frictional force generated between the pulley and ground contact
surfaces of the other fastened components.
[0004] Further, the field core is configured so as not to be movable to the
counter-belt drive side with respect to the rotary shaft. The following two
structures are given as the reason thereof. The rotary shaft includes a flange
25 portion, which is a portion having a larger diameter, on the counter-belt drive
3
side of the rotary shaft along a terminal end surface of the field core on the
counter-belt drive side, or the rotary shaft has knurling on an outer peripheral
surface of a portion of an outer periphery of the rotary shaft, at which the core is
located in contact therewith. With the structures described above, the field
core and the rotary shaft are fixed 5 to each other.
[0005] The rotary shaft as described above is configured to act like a bolt having
the flange portion on the counter-belt drive side as a bolt head. Thus, the field
core, the spacer, the bearing component, and the pulley are fastened with use of
the nut and the flange portion of the rotary shaft or with use of the nut and the
10 knurling of the rotary shaft. Further, a steel material containing a small carbon
content is generally used for the field core for the purpose of improvement of
magnetic characteristics. Thus, among the components fastened with use of
the nut and the flange portion of the rotary shaft, the field core has a low
strength.
15
Citation List
Patent Literature
[0006] [PTL 1] JP 2017-112775 A
20 Summary of Invention
Technical Problem
[0007] However, the related art has the following problems. In the alternator
for a vehicle, which is described in Patent Literature 1, when an excessive input
torque is applied to the pulley, the frictional force generated on the ground
25 contact surfaces of the fastened components between the rotary shaft and the nut
4
is overwhelmed by the input torque. Thus, sliding of the pulley and drag of the
nut occur. As a result, loosening of the nut may be caused thereby. Thus,
there arises a problem in that dropping of the nut or the pulley may lead to an
accident.
[0008] In the related art, the components to be fastened to the 5 rotary shaft with
use of the nut include the field core, the spacer, the bearing component, and the
pulley. In this case, a soft material having a small carbon content is used for
the field core. Hence, the field core has a relatively smaller yield stress than
those of the other components. Thus, a tightening torque for the nut to be used
10 is set to fall within a low range so as to prevent break down or damage of the
field core.
[0009] In other words, with the related art, the tightening torque for the nut
cannot be set sufficiently large. As a result, with the related art, the problems
such as the loosening of the nut and unnecessary sliding of the pulley, which
15 may be caused when an excessive input torque is applied, cannot be solved.
[0010] The present invention has been made to solve the problems described
above, and has an object to provide a rotating electric machine having such a
structure as to release a field core from an axial force to enable increase in
tightening torque for a nut and the axial force for achievement of increase in
20 force for restraining sliding of a pulley.
Solution to Problem
[0011] In order to solve the above-mentioned problems, according to one
embodiment of the present invention, there is provided a rotating electric
25 machine, including: a rotary shaft rotatably supported by a front bearing and a
5
rear bearing; a field core firmly fixed to the rotary shaft; and a pulley fitted over
the rotary shaft on one end side so as to be rotatable integrally with the rotary
shaft, wherein the pulley, the front bearing, and the field core are arranged in a
stated order from the one end side of the rotary shaft toward another end side of
the rotary shaft, wherein the pulley is fastened to the rotary shaft 5 with use of a
male thread formed on the one end side of the rotary shaft and a nut to be
mounted to the male thread, and wherein the rotary shaft has a flange portion,
which projects radially outward and is arranged to be located between the front
bearing and the field core in an axial direction of the rotary shaft.
10
Advantageous Effects of Invention
[0012] The rotating electric machine according to one embodiment of the
present invention has such a structure that the flange portion having a diameter
larger than that of the rotary shaft is arranged between the bearing and the field
15 core so as to prevent the field core from being affected by an axial force
generated by a tightening force for the nut. With the structure described above,
the field core can be released from the axial force. As a result, a force for
restraining sliding of the pulley can be increased by achievement of increase in
torque of a tightening force for the nut and increase in frictional force generated
20 by the axial force in the thread.
Brief Description of Drawings
[0013] [FIG. 1] FIG. 1 is a sectional view of a rotating electric machine
according to a first embodiment of the present invention.
25 [FIG. 2] FIG. 2 is a sectional view of a rotary shaft of the rotating
6
electric machine, which has been subjected to heat treatment, in the first
embodiment of the present invention.
[FIG. 3] FIG. 3 is a sectional view of a pulley of the rotating
electric machine, which has been subjected to the heat treatment, in the first
embodiment of the 5 present invention.
[FIG. 4] FIG. 4 is an enlarged sectional view of a rotary shaft of a
rotating electric machine according to a second embodiment of the present
invention and its surroundings.
[FIG. 5] FIG. 5 is an enlarged sectional view of a rotary shaft of a
10 rotating electric machine according to a third embodiment of the present
invention and its surroundings.
[FIG. 6] FIG. 6 is an enlarged sectional view of a rotary shaft of a
rotating electric machine according to a fourth embodiment of the present
invention and its surroundings.
15 [FIG. 7] FIG. 7 is an enlarged sectional view of a rotary shaft of a
rotating electric machine according to a modification example of the fourth
embodiment of the present invention and its surroundings.
[FIG. 8A] FIG. 8A is an enlarged sectional view of a rotary shaft of
a rotating electric machine according to a fifth embodiment of the present
20 invention and its surroundings.
[FIG. 8B] FIG. 8B is a sectional view taken along the line A-A of
FIG. 8A.
[FIG. 9A] FIG. 9A is an enlarged sectional view of a rotary shaft of
a rotating electric machine according to a sixth embodiment of the present
25 invention and its surroundings.
7
[FIG. 9B] FIG. 9B is a sectional view taken along the line B-B of
FIG. 9A.
Description of Embodiments
[0014] Now, a rotating electric machine according to 5 embodiments of the
present invention is described with reference to the accompanying drawings.
[0015] First Embodiment
FIG. 1 is a sectional view of a rotating electric machine according to a
first embodiment of the present invention. The rotating electric machine
10 according to the first embodiment is a controller-integrated type rotating electric
machine, and is mounted in a vehicle to be used for driving assistance and
power generation.
[0016] A controller-integrated type rotating electric machine 1 includes a
rotating electric machine main body 1a and a controller 1b, which are integrated
15 with each other. The rotating electric machine main body 1a includes a field
core 2, a stator 3, a front bracket 4, a rear bracket 5, a front bearing 7, a rear
bearing 8, cooling fans 20 and 21, and a rotary shaft 22.
[0017] A stator winding 3a is wound around the stator 3. The stator core 2 is
provided on an inner periphery side of the stator 3. The field core 2 includes a
20 field winding 2a wound around a core 2b. In the following description, the
core 2b is also referred to as "field core 2b". The front bracket 4 and the rear
bracket 5 are arranged at both ends of the stator 3 in an axial direction of the
rotary shaft 22. The front bracket 4 and the rear bracket 5 are provided as a
pair of brackets so as to support the stator 3.
25 [0018] The front bearing 7 is fixed to the front bracket 4. The rear bearing 8 is
8
fixed to the rear bracket 5. The rotary shaft 22 is rotatably held by the front
bearing 7 and the rear bearing 8. The rotary shaft 22 is fixed at a center of the
field core 2. The rear bearing 8 may be press-fitted over the rotary shaft 8 so as
to be fixed thereto.
[0019] The rotary shaft 22 according to the first embodiment 5 has a flange
portion 23 being a portion of the rotary shaft 22, which is formed to have a
larger diameter. The front bearing 7 is arranged on one end side 25 of the
rotary shaft 22 so as to be adjacent to the flange portion 23. Meanwhile, the
field core 2 is arranged on another end side 26 of the rotary shaft 22 so as to be
10 adjacent to the flange portion 23.
[0020] A male thread is formed on the one end side 25 of the rotary shaft, and a
nut 14 is mounted thereto. The cooling fan 20 and the cooling fan 21, which
are configured to generate cooling air through rotation of the field core 2, are
provided to both ends of the field core 2 in the axial direction. The nut 14
15 forms the one end side 25 of the rotary shaft 22. Meanwhile, slip rings 13 form
the another end side 26 of the rotary shaft 22.
[0021] On the one end side 25, a pulley 12 is provided to the rotary shaft 22
projecting from the front bracket 4. The pulley 12 is fastened to the rotary
shaft 22 with use of the male thread formed on the one end side 25 of the rotary
20 shaft 22 and the nut 14 mounted thereto. Thus, the pulley 12 is fitted over the
one end side 25 of the rotary shaft 22 so as to be rotatable integrally with the
rotary shaft 22.
[0022] Further, a rotational position detecting sensor 6 configured to detect a
rotation state of the field core 2 is provided to the rotary shaft 22 projecting from
25 the rear bracket 5 on the another side. Further, a pair of the slip rings 13
9
configured to supply a current to the field winding 2a are provided on a side
closer to the another end side 26 with respect to the rotational position detecting
sensor 6. A pair of brushes 17, which are held in sliding contact with the slip
rings 13, are provided on an outer side of the rear bracket 5. The brushes 17
are held in 5 brush holders 16.
[0023] Next, the controller 1b is described. The controller 1b includes a power
circuit unit, a field circuit unit, and a control circuit unit. However, none of the
power circuit unit, the field circuit unit, and the control circuit unit is clearly
illustrated in FIG. 1. The power circuit unit is electrically connected to the
10 stator winding 3a. The field circuit unit is electrically connected to the field
winding 2a. The control circuit unit is configured to control the power circuit
unit and the field circuit unit.
[0024] Next, with reference to FIG. 1, an operation of the controller-integrated
type rotating electric machine 1 is described. The controller-integrated type
15 rotating electric machine 1 functions as an electric motor for vehicle driving
assistance, and functions as a power generator for power generation.
[0025] First, description is made of a case in which the controller-integrated
type rotating electric machine 1 functions as the electric motor. DC power
supplied from an external battery (not shown) to the power circuit unit is
20 converted into a three-phase AC current through ON/OFF control of the power
circuit unit, and is then supplied to the stator winding 3a.
[0026] Further, the DC power supplied from the external battery is adjusted in
the field circuit unit, and is then supplied to the field winding 2a. Through the
supply of the DC power, a rotating magnetic field is generated around the field
25 winding 2a. As a result, the field core 2 is rotated together with the rotary shaft
10
22.
[0027] The rotation of the rotary shaft 22 is transmitted from the pulley 12 to an
engine via a drive belt (not shown). Further, the control circuit unit controls
the power circuit unit and the field circuit unit based on information from an
external device (not shown) and the rotational position detecting 5 sensor 6.
[0028] Next, the operation of the controller-integrated type rotating electric
machine 1 when functioning as the power generator is described. When the
engine is rotated, a rotational force of the engine is transmitted to the rotary
shaft 22 via the drive belt and the pulley 12. As a result, the field core 2 is
10 rotated to excite three-phase AC power in the stator winding 3a.
[0029] Then, the control circuit unit controls ON/OFF of the power circuit unit
so as to convert the three-phase AC power excited in the stator winding 3a into
DC power. The DC power obtained by the conversion is supplied to the
external battery to charge the external battery.
15 [0030] In the first embodiment, the structure of the rotary shaft 22 having the
flange portion 23 is employed. With the above-mentioned structure, a surface
of an inner ring on a portion of a side surface of the front bearing 7, which is
located on a side opposite to the pulley 12, corresponds to a terminal end surface
of a fastened section to be fastened by tightening the nut 14.
20 [0031] As a result, the members to be fastened by tightening the nut are limited
to the front bearing 7 and the pulley 12. Thus, the field core 2 having a smaller
strength than those of the front bearing 7 and the pulley 12 is released from an
axial force generated by tightening the nut. Specifically, through the
employment of the structure of the rotary shaft 22 having the flange portion 23,
25 the field core can be prevented from being affected by the axial force generated
11
by a tightening force for the nut. As a result, the tightening force for the nut
can be set to be larger than that in the related art. Thus, a force for restraining
sliding of the pulley 12 can be improved.
[0032] Next, description is made of a case in which a further improvement of
the force for restraining the sliding of the pulley 12 is achieved 5 through heat
treatment performed on at least one of the components. FIG. 2 is a sectional
view of the rotary shaft 22, which has been subjected to heat treatment, in the
first embodiment of the present invention. FIG. 3 is a sectional view of the
pulley 12, which has been subjected to the heat treatment, in the first
10 embodiment of the present invention. In FIG. 2 and FIG. 3, hatched portions
correspond to portions having been subjected to the heat treatment.
[0033] As illustrated in FIG. 2, through the heat treatment performed on the
rotary shaft 22 and the flange portion 23, a resistance against a compressive
force in the flange portion 23 and a resistance against a tensile force in the
15 thread portion of the rotary shaft 22, which are generated by tightening the nut
14, can be increased.
[0034] Further, as illustrated in FIG. 3, through the heat treatment performed on
a portion of the pulley 12, on which a fastening force acts, a resistance against a
compressive force generated in the pulley 12 by tightening the nut 14 can be
20 increased.
[0035] As described above, through the heat treatment performed on the
portions of the rotary shaft 22 and the pulley 12, on which the fastening force
acts, the tightening force for the nut 14 can be set to be larger. As a result, the
force for restraining the sliding of the pulley 12 can be further improved. The
25 ranges of the heat treatment illustrated in FIG. 2 and FIG. 3 are examples.
12
When the heat treatment is performed on the rotary shaft 22 and the pulley 12
over ranges equal to or larger than the illustrated ranges, a higher effect of the
resistances can be achieved.
[0036] As described above, according to the first embodiment, the rotary shaft
has such a structure that the flange portion, which is a portion 5 having a larger
diameter than that of the other portion of the rotary shaft, is arranged between
the front bearing and the field core. With the structure described above, the
field core can be prevented from being affected by the axial force generated by
the tightening force for the nut. Hence, the tightening force for the nut can be
10 set to be larger. As a result, the rotating electric machine with the improved
force for restraining the sliding of the pulley can be obtained.
[0037] Further, according to the first embodiment, the structure of fixing the
rotary shaft and the nut through welding may be employed. With the
above-mentioned structure, when an excessive input torque is applied, loosening
15 of the nut can be prevented. Further, even when an excessive input torque is
applied to cause the sliding of the pulley, co-rotation and dropping of the nut can
be suppressed.
[0038] Second Embodiment
In a second embodiment, description is made of a case in which
20 improvement of the force for restraining the sliding of the pulley 12 is achieved
by suitably setting outer-diameter dimensions of the rotary shaft 22.
[0039] FIG. 4 is an enlarged sectional view of a rotary shaft of a rotating electric
machine according to the second embodiment and its surroundings. An outer
diameter of a portion of the rotary shaft 22 on the field core 2 side with respect
25 to the flange portion 23 is represented by D1. An outer diameter of a portion of
13
the rotary shaft 22 on the front bearing 7 side with respect to the flange portion
23 is represented by D2. For the outer diameters of the rotary shaft 22, D2 is set
to be larger than D1. The same reference symbols as those in FIG. 1 denote the
same or similar components, and a detailed description thereof is omitted.
[0040] The outer diameter of the rotary shaft 22 according 5 to the second
embodiment is set so as to satisfy a relation: D2>D1. Specifically, the outer
diameter of the portion of the rotary shaft 22 according to the second
embodiment 2 on the one end side 25, which is formed as the male thread, is set
to be larger. As a result, a resistance against the tensile force generated in the
10 rotary shaft 22 by tightening the nut 14 can be improved. Further, the force for
restraining the sliding of the pulley 12 can be improved by setting the tightening
force for the nut 14 to be larger.
[0041] Third Embodiment
In a third embodiment, description is made of a case in which
15 improvement of the force for restraining the sliding of the pulley 12 is achieved
by suitably setting the outer-diameter dimension of the rotary shaft 22, an outer
diameter of the inner ring of the front bearing 7, and an outer-diameter
dimension of a boss portion 12a of the pulley 12.
[0042] FIG. 5 is an enlarged sectional view of a rotary shaft of a rotating electric
20 machine according to the third embodiment of the present invention and its
surroundings. An outer diameter of the flange portion 23 of the rotary shaft 22
is represented by D3. An outer diameter of the inner ring of the front bearing 7
is represented by D4. An outer diameter of the boss portion 12a of the pulley
12, which is brought into contact with the front bearing 7, is represented by D5.
25 For the outer diameters, each of the outer diameters D3 and D5 is set equal to D4.
14
The same reference symbols as those in FIG. 1 denote the same or similar
components, and a detailed description thereof is herein omitted.
[0043] In the third embodiment, the structure in which the outer-diameter
dimensions D3 and D5 are set equal to D4 is employed. With the
above-mentioned structure having the same outer diameters, the 5 tightening force
for the nut is transmitted to the flange portion 23 having the outer diameter D3
via the pulley 12 having the outer diameter D5 and the front bearing 7 having the
outer diameter D4.
[0044] As a result, a resistance against a compressive force generated in the
10 flange portion 23 of the rotary shaft 22 and the pulley 12 by tightening the nut
14 can be increased. Further, the force for restraining the sliding of the pulley
12 can be improved by setting the tightening force for the nut 14 to be larger.
[0045] Fourth Embodiment
In a fourth embodiment, description is made of a case in which
15 improvement of the force for restraining the sliding of the pulley 12 is achieved
by suitably changing a shape of the flange portion 23.
[0046] FIG. 6 is an enlarged sectional view of a rotary shaft of a rotating electric
machine according to the fourth embodiment of the present invention and its
surroundings. An outer peripheral surface of a portion of the flange portion 23
20 of the rotary shaft 22 according to the fourth embodiment, with which the field
core 2b is brought into contact, is formed to have a step-like shape. An outer
diameter of a step 31 portion of the outer peripheral surface, at which the flange
portion 23 of the rotary shaft 22 and the field core 2 are brought into contact
with each other, on the field core 2b side with respect to the flange portion 23 of
25 the rotary shaft 22, is represented by D6. Further, an outer diameter of a
15
portion of the rotary shaft 22 on the field core 2b side with respect to the flange
portion 23 is represented by D1. An outer diameter of the flange portion of the
rotary shaft 22 is represented by D3.
[0047] The outer diameters D1, D3, and D6 of the rotary shaft 22 are set so as to
satisfy a relation: D1D1, the
15 number of teeth of each of the splines can be increased. As a result, a load
applied on one tooth of each of the splines is reduced, and hence a life of the
splines can be prolonged.
Reference Signs List
20 [0060] 1 controller-integrated type rotating electric machine (rotating electric
machine), 2, 2b field core, 7 front bearing, 12 pulley, 12a boss portion of pulley,
12b key groove of pulley, 12c spline of pulley, 14 nut, 22 rotary shaft, 22b key
groove of rotary shaft, 22c spline of rotary shaft, 23 flange portion of rotary
shaft, 24 key, 25 one end side of rotary shaft, 26 another end side of rotary shaft,
25 31 step portion of outer peripheral surface at which flange portion of rotary shaft
19
and field core are brought into abutment against each other, D1 outer diameter of
portion of rotary shaft on field core side with respect to the flange portion, D2
outer diameter of portion of rotary shaft on front bearing side with respect to
flange portion, D3 outer diameter of flange portion of rotary shaft, D4 outer
diameter of inner ring of front bearing, D5 outer diameter 5 of boss portion of
pulley
20
We Claim:
[Claim 1] A rotating electric machine, comprising:
a rotary shaft rotatably supported by a front bearing and a rear bearing;
a field core firmly fixed to the rotary shaft; and
a pulley fitted over the rotary shaft on one end side so 5 as to be rotatable
integrally with the rotary shaft,
wherein the pulley, the front bearing, and the field core are arranged in a
stated order from the one end side of the rotary shaft toward another end side of
the rotary shaft,
10 wherein the pulley is fastened to the rotary shaft with use of a male
thread formed on the one end side of the rotary shaft and a nut to be mounted to
the male thread, and
wherein the rotary shaft has a flange portion, which projects radially
outward, and is arranged at a position between the front bearing and the field
15 core in an axial direction of the rotary shaft.
[Claim 2] The rotating electric machine according to claim 1, wherein the rotary
shaft and the pulley each have a key groove, and are fixed to each other by
insertion of a key into the key groove.
20
[Claim 3] The rotating electric machine according to claim 1, wherein the rotary
shaft and the pulley each have a spline formed on a surface to be brought into
contact with each other, and are fixed to each other by meshing between the
spline of the rotary shaft and the spline of the pulley.
25
21
[Claim 4] The rotating electric machine according to any one of claims 1 to 3,
wherein the nut is fixed to the rotary shaft by welding under a state of being
mounted to the male thread.
[Claim 5] The rotating electric machine according to any one 5 of claims 1 to 4,
wherein at least a part of each of the rotary shaft and the flange portion is
subjected to heat treatment.
[Claim 6] The rotating electric machine according to any one of claims 1 to 5,
10 wherein at least a part of each of the pulley is subjected to heat treatment.
[Claim 7] The rotating electric machine according to any one of claims 1 to 6,
wherein an outer diameter of a portion of the rotary shaft on the one end side
with respect to the flange portion is set to be larger than an outer diameter of a
15 portion of the rotary shaft on another end side with respect to the flange portion.
[Claim 8] The rotating electric machine according to any one of claims 1 to 7,
wherein an outer diameter of the flange portion, an outer diameter of an inner
ring of the front bearing, and an outer diameter of a boss portion of the pulley,
20 which is brought into contact with the front bearing, are set to be equal to each
other.
[Claim 9] The rotating electric machine according to any one of claims 1 to 8,
wherein an outer peripheral surface, at which the flange portion and the field
25 core are brought into abutment against each other, has a step.
22
[Claim 10] The rotating electric machine according to claim 9, wherein the step
has a tapered shape.