JPH10167159A - Power unit of electric auxiliary bicycle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simplify sealing structure between a housing of an electric assist motor and a casing by forming a breather chamber communicating with the inside of an electric assist motor on a casing upper part supported on a car body frame and providing a breather hole communicating the inside of the breather chamber to the outside on the casing. SOLUTION: A breather chamber 134 is formed on an upper part of a casing 45 between a crankshaft and an electric assist motor 30. A communicating hole 135 to communicate an upper part of this breather chamber 134 to a second storage chamber 50 is provided on a left casing half body 46 of the casing 45, and a breather hole 136 to communicate a lower part in the inside of the breather chamber 134 to the outside is provided on a right casing half body 47. Consequently, air in a housing 90 of the electric assist motor 30 is breathed through the breather chamber 134 and the breather hole 136 in accordance with expansion and contraction of air due to repetition of heating at the time of using the electric assist motor 30 and cooling at the time of not using it, compression and decompression of the inside of the housing 90 is prevented and sealing structure is simplified.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a casing supported on a vehicle body frame by rotatably supporting a crankshaft having crank pedals at both ends thereof, and a casing capable of transmitting rotational power from the crankshaft. A power transmission member rotatably supported by the vehicle and coupled to and coupled to the rear wheel; an electric assist motor having a rotation axis parallel to the crankshaft and attached to the casing; the electric assist motor and the power The present invention relates to a power unit for an electric assist bicycle including a reduction gear train provided between transmission members.

[0002]

2. Description of the Related Art Conventionally, such a power unit has been already known, for example, from Japanese Patent Application Laid-Open No. Hei 8-216968.

[0003]

In such a power unit, the electric assist motor is mounted on the casing with its axis of rotation substantially parallel to the ground, so that a drain hole also serving as a breather is provided in the housing of the electric assist motor. It is difficult to provide the drainage structure because the drainage structure is complicated. In the above-described conventional motor, the drainage structure is not provided in the electric assist motor, and the electric assist motor is in a hermetically sealed state for waterproofing. Is attached to the casing. However, when the electric assist motor is in a sealed state, air in the housing of the electric assist motor repeatedly expands and contracts due to repeated heat generation during use and cooling during non-use. And the seal portion between the casings needs to enhance the waterproofness regardless of the pressure increase / decrease in the housing due to the expansion and contraction of the air, the structure of the seal portion becomes complicated, and an expensive seal member having high sealability is required. Used.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a power unit of a battery-assisted bicycle that can simplify a seal structure between a housing and a casing of an electric assist motor. I do.

[0005]

SUMMARY OF THE INVENTION In order to achieve the above object, the invention according to claim 1 comprises a casing supported on a body frame by rotatably supporting a crankshaft having crank pedals at both ends thereof, A power transmission member rotatably supported by the casing to be capable of transmitting rotational power from the crankshaft and interlocked with and connected to a rear wheel; and a rotational axis parallel to the crankshaft and having a rotational axis parallel to the crankshaft. In a power unit of an electric assist bicycle including an electric assist motor to be mounted and a reduction gear train provided between the electric assist motor and the power transmission member, a breather chamber communicating with the electric assist motor is formed at an upper part of a casing, A breather hole for communicating the breather chamber with the outside is provided in the casing.

According to the configuration of the first aspect of the present invention, the housing of the electric assist motor is provided in accordance with the expansion and contraction of air due to the repetition of heat generation when the electric assist motor is used and cooling when not used. Air can be breathed through the breather chamber and breather hole,
Since the pressure inside the housing of the electric assist motor is not increased or decreased, the seal structure between the housing and the casing of the electric assist motor can be simplified.

According to a second aspect of the present invention, in addition to the configuration of the first aspect, the breather chamber is formed above the casing between the crankshaft and the electric assist motor, so that the breather chamber is formed. Can be arranged at a relatively high position from the ground, and the intrusion of water into the breather chamber can be prevented as much as possible.

According to a third aspect of the present invention, in addition to the configuration of the second aspect, the idle shaft having an axis parallel to the crankshaft and forming a part of a reduction gear train, By being rotatably supported by the casing at a position lower than a straight line connecting the axis of the crankshaft and the rotation axis of the electric assist motor, the crankshaft and the electric assist motor are brought close to each other to form a reduction gear train, The breather chamber can be formed by effectively using the empty space between the crankshaft and the electric assist motor, and the power unit can be made compact.

According to a fourth aspect of the present invention, in addition to the configuration of any one of the first to third aspects, a communication hole for communicating an upper portion of the breather chamber into the electric assist motor is provided. A breather hole that allows the lower part of the room to communicate with the outside is provided in the casing,
Water can be prevented from entering the casing and the electric assist motor from the breather chamber, and the water entering the breather chamber can be reliably discharged.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments of the present invention will be described below based on one embodiment of the present invention shown in the accompanying drawings.

1 to 16 show an embodiment of the present invention. FIG. 1 is a side view of an electric assisted bicycle, FIG. 2 is a longitudinal side view of a power unit, and FIG. 3 is a line 3-3 in FIG. FIG. 4 is a cross-sectional view, and FIG.
5 is a sectional view taken along line 5-5 of FIG. 4, FIG. 6 is an enlarged view of the vicinity of the crankshaft of FIG. 3, FIG. 7 is a sectional view taken along line 7-7 of FIG. 6, and FIG. FIG. 9 is a sectional view taken along line 8-8 of FIG. 6, and FIG. 9 is a sectional view taken along line 9-9 of FIG.
FIG. 10 is an enlarged cross-sectional view of the vicinity of the electric assist motor of FIG. 3, and FIG.
12 is an enlarged sectional view taken along line 12-12 of FIG. 10, FIG. 13 is a front view of a boss, FIG. 14 is a front view of a ring body, FIG. 15 is a front view of a reinforcing plate, and FIG. It is an exploded perspective view.

Referring to FIG. 1, the electric assisted bicycle includes a vehicle body frame 21 having a substantially U-shape in a side view.
Front fork 23 to the head pipe 22 at the front end of the body frame 21 is steerably supported, the front wheel W _F at the lower end of the front fork 23 is rotatably supported, the bar handle 24 is provided on the upper end of the front fork 23. A power unit 31 having an electric assist motor 30 is provided at a lower portion of the body frame 21. The power unit 31 extends rearward and downward from the body frame 21 above a rear portion of the power unit 31, and extends substantially horizontally behind the power unit 31. left, rear wheel W _R is rotatably supported to the right pair of rear forks 25 ... between the left and right pair of stays 26 ... are provided between the rear portion of the two rear fork 25 ... and the vehicle body frame 21. Further, a seat post 28 having a seat 27 at an upper end is mounted on the rear portion of the body frame 21 so that the vertical position of the seat 27 can be adjusted.
The carrier 29 is fixedly arranged behind the.

A crankshaft 33 having crank pedals 32, 32 at both ends is rotatably supported by a casing 45 of the power unit 31, and can transmit power from the crankshaft 33 and assist power from the electric assist motor 30. An endless chain 36 is wound around a drive sprocket 34 that can also act on the rear wheel WR and a driven sprocket 35 provided on the axle of the rear wheel W _R so as to be covered by the chain case 44.

The operation of the electric assist motor 30 is controlled by a controller 37 fixedly supported on the front side of the power unit 31 and under the body frame 21. The controller 37 rotates the electric assist motor 30. The operation of the electric assist motor 30 is controlled based on the number and the input torque by the input pedals 32, 32.

A front basket 38 is attached to the head pipe 22 via a bracket 43. In addition, a battery storage case 39 disposed on the back of the front basket 38 is also attached to the bracket 43, and a battery 40 for supplying electric power to the electric assist motor 30 is removably stored in the battery storage case 39. Is done.

A large part of the body frame 21 is covered with a cover 41, and a main switch 42 for supplying electric power from the battery 40 to the controller 37 and the electric assist motor 30 is disposed above the cover 41. Is done.

Referring also to FIGS. 2 to 5, the casing 45 of the power unit 31 is
Between the first casing 6 and the left casing half 46.
And a right casing half 47 connected to the left casing half 46, and a cover 48 forming a second storage chamber 50 between the left casing half 46 and coupled to the left casing half 46. , And a rubber gasket 51 is mounted on a surface of the cover 48 connected to the left casing half 46.

The crankshaft 33 is rotatably supported by the casing 45 such that most of the crankshaft 33 is disposed in the first storage chamber 49, and is supported by the right casing half 47 via a ball bearing 52. The right end of the crankshaft 33 is supported via roller bearings 54 on the inner periphery of the rotating cylindrical body 53 serving as a power transmission member, and the left end of the crankshaft 33 is connected to a left casing half via a ball bearing 55. It is supported at 46. Thus, the drive sprocket 34 disposed on the right side of the right casing half 47 is connected to the rotary cylinder 53.

The pedaling force of the crank pedals 32 at the left and right ends of the crankshaft 33 is transmitted from the crankshaft 33 to the drive sprocket 34 via power transmission means 56. The casing 45 includes the electric assist motor 30.
The output of the electric assist motor 30 is transmitted to the drive sprocket 34 via a reduction gear train 57 to assist the pedaling force of the crank pedals 32, 32.

With further reference to FIGS. 6 to 8,
The power transmission means 56 for transmitting the power of the crankshaft 33 to the drive sprocket 34 is disposed in the first storage chamber 49, and includes a torsion bar 58 connected to the crankshaft 33, and a rotating cylinder 53. And torsion bar 5
And a first one-way clutch 59 provided between them.

The crankshaft 33 is provided with a slit 60 extending along the axis thereof.
8 is a cylindrical shaft portion 58a rotatably fitted between left and right inner wall surfaces 60a and 60b of the slit 60;
Arm 58 projecting from both sides from the left end of FIG.
b, and an arm 58c protruding to both sides from the right end (upper end in FIG. 6) of the shaft 58a, and is attached to the slit 60.

One arm 58b of the torsion bar 58
Are tightly fitted to the left and right inner wall surfaces 60a, 60a of the slit 60 and are integrally connected to the crankshaft 33. The other arm 58c of the torsion bar 58 is connected to the left and right inner wall surfaces 6.
Gaps α, α are formed between the slit 6
0 of the torsion bar 58.
Can be torsionally deformed within a range in which the arm portion 58c moves by the gaps α, α.

The first one-way clutch 59 includes a ring-shaped clutch inner ring 61 coaxially surrounding the crankshaft 33 so as to be rotatable relative to each other, a rotating cylinder 53 serving as a clutch outer ring coaxially surrounding the clutch inner ring 61, and Clutch inner ring 6
A plurality of, for example, four ratchet claws 62... Urged in the expanding direction by an annular spring 63 and supported on the outer circumference of the clutch inner ring 61, and a pair of recesses 61 a, The both ends of the arm portion 58c of the torsion bar 58 are fitted to 61a, and the ratchet teeth 6 for engaging the ratchet claws 62.
4 are formed.

According to the first one-way clutch 59, the crankshaft 33 is depressed by pressing the crank pedals 32, 32.
Is rotated forward, the torque of the crankshaft 33 is increased by the torsion bar 58, the first one-way clutch 59 and the rotating cylinder 53.
The first one-way clutch 59 slips and the reverse rotation of the crankshaft 33 is permitted when the crankshaft 33 is reversed by stepping on the crank pedals 32, 32.

By the way, when the crank pedals 32 to the crankshaft 33 is the direction of arrow a torque in FIG. 8 is input, the load of the rear wheel W _R is transmitted through the rotating cylinder 53 and the ratchet pawl 62 ... Since the clutch inner ring 61 resists the torque in the direction of the arrow a, the arm portion 58c of the torsion bar 58 is twisted relative to the crankshaft 33 in the direction of the arrow b to rotate relatively. As a result, between the crankshaft 33 and the clutch inner ring 61, the crankshaft 33
Relative rotation occurs in accordance with the torque input to.

A slider inner 66 is supported on the outer periphery of the crankshaft 33 so as to be relatively non-rotatable and relatively movable in the axial direction. A slider outer 68 is provided on the outer periphery of the slider inner 66 via a plurality of balls 67. It is supported for relative rotation.

As clearly shown in FIG. 9, the slider inner 6 of the clutch inner race 61 in the first one-way clutch 59 is provided.
A concave cam surface 61b is provided on the end surface on the sixth side, and a convex cam surface 66a engaging with the cam surface 61b is provided on the slider inner 66.

An intermediate portion of a detection lever 70 whose base end is swingably supported on a left casing half 46 via a fulcrum pin 69 is brought into contact with a slider outer 68 from the side opposite to the clutch inner ring 61. You. On the other hand, the detection lever 70
Stroke sensor 71 constituting a torque detecting means S _T is attached to the left casing half 46, the tip of the detection lever 70 to the detector 71a of the stroke sensor 71 is in contact with. Further, a spring 72 is contracted between the detection lever 71 and the left casing half 46, and the detection lever 71 is resiliently brought into contact with the slider outer 68 by the spring force of the spring 72. The inner 66 is a clutch inner ring 61.
It is urged toward the side.

When the torsion bar 58 is twisted in response to torque input from the crank pedals 32, 32 to the crankshaft 33, as shown in FIG.
6 rotates relative to the clutch inner ring 61 in the direction of arrow c, and the cam surface 66a of the slider inner 66 is pressed against the cam surface 61b of the clutch inner ring 61. As a result, the slider inner 66 slides in the direction of the arrow d along the axis of the crankshaft 33 against the spring force of the spring 72, and the detection lever 70 pushed by the slider outer 68 that moves together with the slider inner 66 is used as a fulcrum. By swinging around the pin 69, the detector 71a of the stroke sensor 71 is pressed. The stroke of the detector 71a is determined by the amount of torsion of the torsion bar 58, that is, the crank pedals 32,3.
And in proportion to the input torque inputted from the 2, so that the input torque is detected by the torque detecting means S _T.

Referring also to FIG. 10, a reduction gear train 57 for transmitting the power of electric assist motor 30 to drive sprocket 34 is fixed to motor shaft 73 of electric assist motor 30 in second storage chamber 50. Drive gear 74
And a first intermediate gear 7 fixed to one end of the first idle shaft 75 in the second storage chamber 50 and meshed with the drive gear 74.
6, a second intermediate gear 77 provided integrally with the first idle shaft 75 in the first storage chamber 49, a third intermediate gear 78 meshed with the second intermediate gear 77, and a coaxial with the third intermediate gear 78. Idle shaft 79 disposed on the shaft and a third intermediate gear 78
A second one-way clutch 80 provided between the second idle shaft 79 and the second idle shaft 79.
And a driven gear 8 integrally provided with the rotary cylinder 53 to which the driving sprocket 34 is coupled and meshed with the fourth intermediate gear 81.
2 is provided.

The first idle shaft 75 has an axis parallel to the motor shaft 73 of the electric assist motor 30. A ball bearing 83 is provided between the right casing half 47 and the first idle shaft 75, and a left casing half is provided. Body 46
A ball bearing 84 is interposed between the first idle shaft 75 and the first idle shaft 75. The second idle shaft 79 is the first idle shaft 75
And the right casing half 4
Ball bearing 85 between the first idle shaft 79 and the second idle shaft 79
But also the left casing half 46 and the second idle shaft 7
A ball bearing 86 is interposed between 9.

In such a reduction gear train 57, the torque associated with the operation of the electric assist motor 30 is reduced and transmitted to the drive sprocket 34, but when the operation of the electric assist motor 30 is stopped, the second Direction clutch 8
The idle operation of the second idle shaft 79 is allowed by the function of 0,
The rotation of the drive sprocket 34 due to the pedaling force of the crank pedals 32, 32 is not hindered.

Referring also to FIG.
In the left casing half body 46, there is integrally provided a fitting tubular portion 88 protruding on the opposite side to the cover 48.
The housing 90 of the electric assist motor 30 is fastened to the left casing half 46 by a plurality of, for example, two bolts 89 while being fitted to the fitting tubular portion 88.

The electric assist motor 30 includes a crankshaft 3
3. The motor shaft 73 has an axis parallel to the axis 3 and the length of the motor shaft 73 along the axis
And is attached to the casing 45 with a length shorter than the axial length of the yoke 90a. The yoke 90a is formed in a cylindrical shape and one end of the yoke 90a is closed. Multiple magnets 91 ...
A rotor 92 having a motor shaft 73 and disposed coaxially in a housing 90; a commutator 93 provided on the rotating shaft 73 at the other end of the yoke 90a; and a plurality of brushes slidingly contacting the commutator 93. 94 ... are provided.

The left casing half 46 is integrally provided with a support wall 95 facing the other end opening of the housing 90 of the electric assist motor 30 so as to close the inner end of the fitting cylinder 88. The opening end of the housing 90 is fitted to the fitting portion 96 provided on the inner surface of the portion near the inner end of the fitting cylindrical portion 88. A positioning pin 97 is implanted in the support wall 95, and a notch 98 for engaging the positioning pin 97 is provided at an open end of the housing 90.
Is provided. Therefore, the housing 90 is fitted to the fitting cylinder 88 while keeping its position along the radial direction and the circumferential direction constant, and the locking head is engaged with the one end closing portion of the housing 90. Each bolt 89, 89 is screwed to the support wall 95.

One end of the motor shaft 73 is rotatably supported via a ball bearing 99 as a first bearing on a bearing housing 90b which is provided to protrude outward at the center of the one end closed portion of the housing 90. The other end of the motor shaft 73 is rotatably penetrated through the support
A second bearing that projects toward the storage chamber 50 and allows air to flow between the support wall 95 and the intermediate portion of the motor shaft 73 in the housing 90 and between the second storage chambers 50. The ball bearing 100 is provided so as to be pressed into the support wall 95, and the motor shaft 73 is provided with a retaining ring 104 for restricting the inner ring of the ball bearing 100 from moving toward the commutator 93.

A support plate 101 is fixed to the support wall 95, and the brushes 94 are slidably held by a plurality of brush holders 102 provided on the support plate 101.
The brushes 94 are urged in a direction in which they come into sliding contact with the commutator 93 by springs 103 provided between the brush holders 102 and the brushes 94. As described above, the brush holders 102, the brushes 94, the ball bearings 100, and the like are directly supported by the left casing half 46 without being held by using a motor bracket or the like, thereby reducing the number of parts. In addition to this, the size of the electric assist motor 30 in the direction along the axis of the crankshaft 33 can be further reduced.

An annular concave portion 105 is provided on the inner peripheral edge of the fitting cylindrical portion 88 so as to form a step, and the right case half 47 has a housing 9 of the electric assist motor 30.
Annular portion 1 which is joined to the tip of fitting tube portion 88 surrounding
06 is provided. Thus, an O-ring 107 that is in close contact with the outer periphery of the yoke 90 a in the housing 90 is sandwiched between the annular concave portion 105 provided on the inner peripheral edge of the distal end of the fitting cylindrical portion 88 and the annular portion 106.

By the way, the casing 45 is arranged such that the axis of the crankshaft 33 and the axis of rotation of the electric assist motor 30 disposed rearward of the crankshaft 33 are substantially at the same height from the ground. The front parts of the left and right casing halves 46 and 47 are supported by brackets 108 and 108 fixed to the left and right sides of the lower part of the body frame 21 with a pair of bolts 109 and
The nuts 110 and 110 are fastened together. Brackets 111 are fixed to the front portions of the pair of left and right rear forks 25... At the rear portion of the casing 45, the left casing half 46 protrudes outward from the fitting tubular portion 88. The hanger part 112 is provided integrally with the hanger part 112, and the hanger part 113 integrally connected to the annular part 106 is provided in the right casing half 47 so as to be sandwiched between the brackets 111 and 111 together with the hanger part 112. The portions 112 and 113 are fixed to both brackets 11 by bolts 114 and nuts 115.
It is supported between 1,111.

A drive gear 74 is mounted via a spline 140 to the other end of the motor shaft 73 projecting from the support wall 95 into the second storage chamber 50. In addition, the outer ring is a support wall 95
The inner ring of the ball bearing 100 press-fitted into the retaining ring 1
A bolt 142 coaxial with the motor shaft 73 is screwed to the other end of the motor shaft 73 so that the drive gear 74 and the reluctor 141 are sandwiched between the inner ring and the inner ring. The movement of the drive gear 74 along the axis of the shaft 73 is prevented, and the drive gear 74 is
Fixed to

When a bolt 142 is screwed onto the motor shaft 73 and fastened to the outer surface of the motor shaft 73 on one end side of the motor shaft 73, that is, on the ball bearing 99 side, a tool such as a wrench is engaged. To prevent rotation of the shaft 73, a pair of flat engagement surfaces 73a, 73a that are parallel to each other are provided as shown in FIG.

[0042] with the reluctor 141, which rotational speed detecting means S _R is composed of an electromagnetic pickup coil type sensor 143, the outer periphery of the reluctor 141 projections 1
41a, and the sensor 143 is provided with the protrusion 141a.
And is fixed to the left casing half 46 of the casing 45 with a detection unit 143a that can approach and oppose the casing.

The first intermediate gear 76 meshed with the drive gear 74 has its outer peripheral portion, that is, the portion meshed with the drive gear 74 made of synthetic resin. A ring body 119 having a toothed portion 125 on the outer periphery and formed in a ring shape from a synthetic resin is fastened to a boss 118 made of stainless steel.

Referring also to FIG. 13, the boss 118
Ball bearing 84 provided on first idle shaft 75
End of the spline 12
0, the first idle shaft 75 is attached to the first idle shaft 75 such that relative rotation around the axis is disabled. The other end of the boss 118 is integrally provided with a flange portion 118a extending outward in the radial direction. Also, a step is formed between the outer periphery of the flange portion 118a and the annular mounting plate portion 118b facing one end of the boss 118 so as to be flush with the end surface of the flange portion 118a. A cylindrical portion 118c extending toward the other end of the boss 118 is integrally formed on the outer periphery of the mounting plate portion 118b, and is provided at three places, for example, at equal intervals in the circumferential direction of the cylindrical portion 118c. There are provided fastening portions 118d which are flush with the surface of the mounting plate portion 118b facing the one end side in the axial direction and project outward and screw holes 121 are provided in each of the fastening portions 118d.

Referring also to FIG.
Has an inside diameter that allows the flange portion 118a of the boss 118 to be fitted thereto, and each of the fastening portions 118 of the boss 118
d. a supporting portion 119a having an outer diameter corresponding to an imaginary circle connecting the outer edges of the ring-shaped supporting portion 119a;
a coaxially surrounding cylindrical portion 119b, and support portion 119a
And a connecting plate portion 119c for connecting the cylindrical portion 119b over the entire circumference.
8, a metal cylindrical tightening collar 122 is integrally embedded corresponding to each screw hole 121. A plurality of ribs 123 project from both front and back surfaces of the support portion 119a between the tightening collars 122, and circular ribs 12 coaxial with the cylindrical portion 119b are provided on both front and back surfaces of the connecting plate portion 119c.
4 are protruded. Further, a large number of teeth 125 meshing with the drive gear 74 are formed on the outer periphery of the cylindrical portion 119b, for example, as helical teeth.

The support portion 11 of the ring body 119 is attached to the mounting plate portion 118b of the boss 118 from one axial end of the boss 118.
9a abuts, and a metal reinforcing plate 126 abuts on the ring body 119 on the side opposite to the mounting plate 118b. As shown in FIG. 15, the reinforcing plate 126 is
22 are formed in a ring shape with through holes 127 individually corresponding to the bolts 128 and bolts 128 respectively inserted into the through holes 127 and the fastening collars 122.
Are screwed into the screw holes 121 of the boss 118, respectively, so that the tightening strength does not act on the ring body 119 made of synthetic resin, the ring body 119 is fastened to the boss 118, and the first intermediate gear 76 will be configured.

In fixing the first intermediate gear 76 to the first idle shaft 75 as described above, the boss 118 of the first intermediate gear 76 is attached to the first idle shaft 75 via the spline 120 so as not to rotate relatively. At the same time, one end of the first intermediate gear 76, that is, one end of the boss 118 is brought into contact with the inner ring of the ball bearing 84. A ring-shaped receiving member 129 facing the other end of the first intermediate gear 76 is detachably attached to the first idle shaft 75. That is, a retaining ring 130 is mounted on the outer surface of the end of the first idle shaft 75, and the receiving member 129 is connected to the first idle shaft 75 such that the retaining ring 130 prevents movement in the direction away from the first intermediate gear 76. 75. A disc spring 131 is provided between the first intermediate gear 76 and the receiving member 129, and the end of the disc spring 131 on the first intermediate gear 76 side is connected to the first intermediate gear 7.
6, the cylindrical portion 118c of the boss 118 is brought into contact with the flange portion 118a of the boss 118 so as to be restricted from expanding radially outward. The first intermediate gear 76 is pressed toward the inner ring side of the ball bearing 84 by the spring force exerted by the disc spring 131. Therefore, the first intermediate gear 76 whose relative rotation about the axis is prevented by the spline 120 is pressed toward the inner ring of the ball bearing 84, and the first intermediate gear 76 is
Fixed to idle shaft 75.

Incidentally, the first and second idle shafts 75 and 79 in the reduction gear train 57 are formed by a straight line connecting the axis of the crankshaft 33 and the rotation axis of the electric assist motor 30 as clearly shown in FIGS. Well down, the first
The idle shaft 75 is disposed so as to be positioned lower than the second idle shaft 79. Above both idle shafts 75 and 79, an upper portion of the casing 45 between the crankshaft 33 and the electric assist motor 30 is provided. A breather chamber 134 is formed.

With particular attention to FIG. 11, the breather chamber 134
Are the left casing half 46 and the right casing half 47
A communication hole 135 is formed in the left casing half 46 to allow the upper part of the breather chamber 134 to communicate with the second storage chamber 50. Thus, the inside of the electric assist motor 30 is connected to the second storage chamber 5 via the ball bearing 100 provided between the support wall 95 and the motor shaft 73.
0, the interior of the electric assist motor 30 communicates with the upper part of the breather chamber 134. Also, the breather hole 13 for communicating the lower part in the breather chamber 134 to the outside.
6 is provided on the right casing half 47. Moreover, the left casing half 46 is integrally provided with a wall 137 close to the right casing half 47 so as to form a maze between the communication hole 135 and the breather hole 136.

By the way, as shown in FIG. 16, the cover 41 covering most of the body frame 21 is
An upper cover 41a for covering the vehicle body frame 21 from above and a lower cover 41b for covering the body frame 21 from below are connected to each other, and an opening 139 facing the main switch 42 is provided above the upper cover 41a. Is provided.

Next, the operation of this embodiment will be described. When the occupant steps on the crank pedals 32 to drive the electric assisted bicycle, the power of the crankshaft 33 is transmitted to the drive sprocket 34 via the power transmission means 56. is, the power to the rear wheel W _R through the chain 36 and driven sprocket 35 is to be transmitted.

[0052] input torque by the crank pedals 32, 32 at this time is detected by the torque detecting means S _T. Also are those rotational speed of the electric assist motor 30 is detected by the rotation speed detecting means S _R as a rotation speed representing a bicycle speed, both detection means S _T, electric assist the assist power corresponding to the detected value of S _R When the motor 30 is used, the load on the occupant can be reduced.

In such a power unit 31 of the electric bicycle, a plurality of gears 74, 76, 77, 78, 81, 82 constituting a reduction gear train 57 provided between the electric assist motor 30 and the rotary cylinder 53. Since the outer peripheral portion of the first intermediate gear 76 which is one of the first intermediate gear 76 is formed of a synthetic resin, it is possible to suppress the generation of gear noise at the meshing portion of the first intermediate gear 76 and the driving gear 74. Becomes Therefore, the length along the axis of the motor shaft 73, which is parallel to the axis of the crankshaft 33, is
Therefore, the generation of gear noise in the reduction gear train 57 can be suppressed as much as possible even if the electric assist motor 30 is of a high-speed type. In addition, the first intermediate gear 76 meshes with the drive gear 74 fixed to the motor shaft 73 of the electric assist motor 30, and generates the gear noise at the meshing portion of the reduction gear train 57 at the highest speed. The suppression can further enhance the gear noise suppression effect.

The first intermediate gear 76 has a large number of teeth 1 on a metal boss 118 connected to the first idle shaft 75.
25 are formed by fastening a synthetic resin ring 119 having an outer periphery 25 with the teeth 125. The teeth 125 that require high molding accuracy can be formed by molding of synthetic resin. Can be improved in accuracy. In addition, since the coupling load for fixing the first intermediate gear 76 to the first idle shaft 75 is made of synthetic resin, it does not act on the ring body 119 which is relatively weak in strength. The first intermediate gear 76 can be reliably fixed to the first idle shaft 75 by increasing the load.

Further, in fixing the first intermediate gear 76 to the first idle shaft 75, the first intermediate gear 76 is mounted on the first idle shaft 75 so that relative rotation around the axis is disabled, and one end of the first intermediate gear 76 is brought into contact with the inner ring of the ball bearing 84. Receiving member 1 received by the other end of the first intermediate gear 76 and the retaining ring 130.
A disc spring 131 is provided between the first intermediate gear 76 and the first intermediate gear 76 when the first intermediate gear 76 meshed with the drive gear 74 is fixed to the first idle shaft 75. Therefore, it is possible to prevent the rotation torque around the axis from acting on the ring body 119 which is formed of a synthetic resin having relatively low strength and meshes with the drive gear 74, thereby preventing the first intermediate gear 76 from rotating. It can be fixed to the first idle shaft 75.

When the drive gear 74 is fixed to the motor shaft 73, the motor shaft 73 pierced through the support wall 95 via the ball bearing 100 before the housing 90 of the electric assist motor 30 is mounted on the casing 45. The drive gear 74 is attached to the motor shaft 73 with a bolt 107 coaxial with the motor shaft 73 in a state where the tool shaft such as a wrench is engaged with both engagement surfaces 73a and 73a to prevent the rotation of the motor shaft 73. Therefore, even if the drive gear 74 is fastened to the motor shaft 73 in a state in which the drive gear 74 is engaged with the first intermediate gear 76, no rotational torque acts on the first intermediate gear 76, and the drive gear 74 and the engagement portion are combined. The first intermediate gear 76 made of resin can be protected.

The housing 90 of the electric assist motor 30
Are fitted into a fitting cylinder 88 provided on the left casing half 46 and a pair of bolts 89,
89, between the annular concave portion 105 provided with a step on the inner peripheral edge of the distal end of the fitting cylindrical portion 88,
An annular portion 106 joined to the tip of the fitting tube portion 88 by sandwiching an O-ring 107 that is in close contact with the outer periphery of the housing 90,
Right casing half 4 coupled to left casing half 46
7 is provided so as to surround the housing 90. Therefore, the housing 90 of the electric assist motor 30 is attached to the casing 45 so that a part of the housing 90 projects from the right casing half 47, and the casing 45 is provided with a portion that covers the entire electric assist motor 30. As unnecessary, the housing 90 of the electric assist motor 30 can be attached to the casing 45 while maintaining a sealing property with the casing 45,
It is possible to make the casing 45 compact and lightweight.

Further, since the annular concave portion 105 is provided on the inner peripheral edge of the distal end of the fitting cylindrical portion 88, the left casing half 4
When the casting 6 is a cast product, the annular concave portion 105 can be formed at the same time when the left casing half 46 is cast-formed, so that cutting is not required, and the number of working steps can be reduced.

In attaching the housing 90 of the electric assist motor 30 to the casing 45, before the left and right casing halves 46 and 47 are connected, the fitting cylinder 88 without the O-ring 107 in the annular recess 105 is attached. Then, the O-ring 107 is fitted into the annular concave portion 105, and the left and right casing halves 4 are fitted.
The joining of the O-ring 107 and the O-ring 107 may be sequentially performed, so that the O-ring 107 is prevented from being damaged as compared with the case where the housing 90 is fitted to the fitting tubular portion 88 after the O-ring 107 is attached. It is possible to improve the workability by reducing the frictional resistance when the housing 90 is fitted.

Further, a hanger portion 112 provided on the left casing half 46 and a hanger portion for supporting the casing 45 on the rear forks 25. 113 are provided integrally, and the casing 4
There is no need for a dedicated part for supporting the body 5 on the body frame 21, and the number of parts can be reduced.

The inside of the electric assist motor 30 communicates with the second storage chamber 50 of the casing 45 via the ball bearing 100. The upper half of the casing 45 has left and right casing halves 46, 47. A breather chamber 134 is formed therebetween, and a communication hole 135 is provided in the left casing half 46 to communicate the upper part of the breather chamber 134 to the second storage chamber 50, and the lower part of the breather chamber 134 is communicated to the outside. A breather hole 136 is provided in the right casing half 47. For this reason, the air in the housing 90 of the electric assist motor 30 causes the breather chamber 134 and the breather hole 136 to respond to the expansion and contraction of the air due to the repetition of heat generation when the electric assist motor 30 is used and cooling when not used. Thus, the inside of the housing 90 of the electric assist motor 30 is not pressurized or depressurized. Therefore, the O-ring 107 sandwiching the seal structure between the housing 90 of the electric assist motor 30 and the casing 45 between the two casing halves 46 and 47 as described above is used as the housing 9.
The structure can be a simplified one that is only close to the outer surface of the zero. In addition, a breather hole 136 communicates with a lower part of the breather chamber 134 in the upper part of the casing 45, and the upper part of the breather chamber 134 communicates with the electric assist motor 30.
In addition, it is possible to prevent water from entering the electric assist motor 30, and it is possible to reliably discharge water that has entered the breather chamber 134.

Further, the breather chamber 134 is provided with the crankshaft 3
3 and the upper part of the casing 45 between the electric assist motor 30, the breather chamber 1
34 can be disposed at a relatively high position from the ground to prevent water from entering the breather chamber 134 as much as possible. Moreover, the first and second idle shafts 75 and 79, which are components of the reduction gear train 57, are rotatably supported by the casing 45 at a position below a straight line connecting the axis of the crankshaft 33 and the rotation axis of the electric assist motor 30. By doing so, the crankshaft 33 and the electric assist motor 30 are brought close to each other to form a row of reduction gears 57, and a breather chamber 134 is formed by effectively utilizing an empty space between the crankshaft 33 and the electric assist motor 30. The power unit 31 can be made more compact.

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

[0064]

As described above, according to the first aspect of the present invention, the housing of the electric assist motor is provided in accordance with the expansion and contraction of the air due to the repetition of heat generation when the electric assist motor is used and cooling when not used. Air in the air through the breather chamber and the breather hole,
Since the pressure in the housing is not increased or decreased, the sealing structure between the housing and the casing of the electric assist motor can be simplified, and an inexpensive sealing member can be used.

According to the second aspect of the present invention, the breather chamber is disposed at a relatively high position from the ground, so that intrusion of water into the breather chamber can be prevented as much as possible.

According to the third aspect of the present invention, the reduction gear train is formed by bringing the crankshaft and the electric assist motor close to each other, and the breather chamber is effectively used by effectively utilizing the empty space between the crankshaft and the electric assist motor. By forming, the power unit can be made compact.

According to the fourth aspect of the present invention, it is possible to prevent water from entering the casing and the electric assist motor from the breather chamber as much as possible and to reliably discharge the water that has entered the breather chamber.

[Brief description of the drawings]

FIG. 1 is a side view of an electric assisted bicycle.

FIG. 2 is a vertical sectional side view of a power unit.

FIG. 3 is a sectional view taken along line 3-3 of FIG. 2;

FIG. 4 shows the state of FIG. 3 with the driving sprocket omitted.
It is an arrow side view.

FIG. 5 is a sectional view taken along line 5-5 in FIG. 4;

FIG. 6 is an enlarged view of the vicinity of the crankshaft in FIG. 3;

FIG. 7 is a sectional view taken along line 7-7 of FIG. 6;

FIG. 8 is a sectional view taken along line 8-8 of FIG. 6;

FIG. 9 is a view showing the engagement state of the slider inner and the clutch inner ring as viewed from the direction of arrows 9-9 in FIG. 6;

FIG. 10 is an enlarged sectional view of the vicinity of the electric assist motor of FIG. 3;

FIG. 11 is an enlarged sectional view taken along line 11-11 of FIG. 4;

FIG. 12 is an enlarged sectional view taken along line 12-12 of FIG. 10;

FIG. 13 is a front view of the boss.

FIG. 14 is a front view of a ring body.

FIG. 15 is a front view of a reinforcing plate.

FIG. 16 is an exploded perspective view of a cover.

[Explanation of symbols]

21 ... body frame 30 ... electric assist motor 31 ... power unit 32 ... crank pedal 33 ... crankshaft 45 ... casing 53 ... rotating cylinder as power transmission member 57 ... -Reduction gear train 75 ... 1st idle shaft 79 ... 2nd idle shaft 134 ... breather chamber 135 ... communication hole 136 ... breather hole W _R ... rear wheel

Claims (4)

[Claims] A casing (45) rotatably supporting a crankshaft (33) having crank pedals (32) at both ends thereof and supported by a body frame (21);
The interlocking the rear wheel (W _R) rotatably while being supported on said rotational power from the crankshaft (33) to allow transmission casing (45), connected by a power transmission member (5
3) an electric assist motor (30) having a rotation axis parallel to the crankshaft (33) and attached to the casing (45); the electric assist motor (30) and the power transmission member (53). In the power unit of the electric assist bicycle including the reduction gear train (57) provided therebetween, a breather chamber (134) communicating with the electric assist motor (30) is formed at an upper portion of the casing (45), and the breather chamber (134) is formed. 134) A power unit for an electrically assisted bicycle, characterized in that a breather hole (136) for communicating the inside with the outside is provided in the casing (45). 2. The battery-assisted bicycle according to claim 1, wherein the breather chamber (134) is formed at an upper portion of a casing (45) between the crankshaft (33) and the electric assist motor (30). Power unit. 3. An idle shaft (75, 79) having an axis parallel to the crankshaft (33) and constituting a part of a reduction gear train (57) is provided with an idle shaft (75) and an axis of the crankshaft (33). The power unit according to claim 2, wherein the power unit is rotatably supported by the casing (45) at a position below a straight line connecting the rotation axis of the electric assist motor (30). 4. A communication hole (135) through which an upper portion of the breather chamber (134) communicates with the electric assist motor (30).
4. A power unit for an electric assist bicycle according to claim 1, wherein a casing (45) is provided with a breather hole (136) for communicating a lower portion inside the breather chamber (134) to the outside. .