JP3748907B2 - Crankshaft of integrated swing type power unit - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a crankshaft of an integrated swing type power unit.
[0002]
[Prior art]
For example, some scooter type vehicles have an integrated swing type power unit. The integral swing type power unit is pivotally attached via a link to a pivot shaft installed between power unit suspension brackets usually provided on a body frame.
[0003]
On the other hand, an integral swing type power unit equipped with a single cylinder engine has a weight distribution of the crank web 4 of the crankshaft 3 with respect to the reciprocating motion part such as the piston 2 in the engine 1 as shown in FIG. It is distributed to the left and right one by one.
[0004]
In addition to the engine 1, a power transmission mechanism and the like are integrally formed in the integrated swing type power unit, and the center of gravity 5 is located on one side of the engine center line 6. Note that an arrow 7 is an excitation force generated by the reciprocating motion unit.
[0005]
[Problems to be solved by the invention]
If the deviation 8 between the center of gravity 5 of the integrated swing type power unit and the engine center line 6, that is, the line of action of the excitation force by the reciprocating motion unit 2 is large, the rotational moment around the center of gravity 5 becomes large and vibrations in the left-right direction occur in the engine 1. To do. However, in the conventional pivoting method of the integrated swing type power unit to the body frame, the vibration in the vertical direction of the engine 1 can be absorbed, but the vibration in the horizontal direction cannot be absorbed.
[0006]
The present invention has been made in consideration of the above-described circumstances, and an object of the present invention is to provide a crankshaft of an integral swing type power unit that reduces vibrations in the left-right direction.
[0007]
[Means for Solving the Problems]
In order to solve the above-described problem, a crankshaft of an integrated swing type power unit according to the present invention has a crankshaft pivotally attached to a vehicle body frame and divided into left and right as described in claim 1. In an integral swing type power unit including a single cylinder engine , a conduction case extending rearward from the engine, and a rear wheel supported at the rear end of the conduction case ,
The left and right crankshafts are connected and integrated by a crankpin, and are pivotally supported in a crankcase by a pair of bearings, and one of the left and right crankshafts is provided with a drive pulley of a transmission. The crankshaft is equipped with a charging device,
The crank web of the crankshaft is arranged on the left and right of the engine center line, and the integrated swing type power unit is positioned with a center of gravity biased toward one crankshaft side where the transmission is provided,
The weight of the crank web on the center of gravity side that is biased to one side of the engine center line of the integrated swing type power unit is set so as to be heavier than the crank web on the other side.
[0008]
[Action]
In the present invention having the above-described configuration, in the integrated swing type power unit including a single cylinder engine having a crankshaft pivotally attached to a vehicle body frame and divided into left and right, the left and right crankshafts are connected by crank pins. Connected and integrated, and supported in a crankcase by a pair of bearings, while the crank web of the crankshaft is disposed on the left and right of the engine center line, and the integrated swing type power unit is provided with a transmission. The center of gravity of the crank web is located on the crankshaft side and the center of the crank web is biased to one side of the engine center line of the integrated swing type power unit. Left of the engine Direction of the vibration can be reduced.
[0009]
【Example】
Embodiments of the present invention will be described below with reference to the drawings.
[0010]
FIG. 1 is a left side view showing an example of a scooter type vehicle to which the present invention is applied.
[0011]
In FIG. 1, the scooter type vehicle 11 has a body frame 12, and the body frame 12 includes a down tube 13 and a pair of left and right rear frames 14 extending rearward and upward from the rear end side of the down tube 13. The The rear frame 14 is curved near its middle and extends rearward and upward.
[0012]
A head pipe 15 is provided at the front end of the down tube 13. The head pipe 15 is provided with a front fork 17 and a handle bar 18 that rotatably support the front wheel 16, and the front wheel 16 is steered to the left and right by the handle bar 18.
[0013]
An article storage chamber 19 capable of storing a helmet or the like is provided above the rear frame 14, and an operation seat 20 is installed above the article storage chamber 19 so as to be openable and closable.
[0014]
A pair of left and right power unit suspension brackets 21 is provided at the center lower portion of the body frame 12, and the front portion of the integral swing type power unit 23 is swingable via a link 24 on a pivot shaft 22 installed between the power unit suspension brackets 21. It is pivotally attached to.
[0015]
The integral swing type power unit 23 includes a single cylinder engine 25 and a conductive case 26 extending rearward from one side of the engine 25. The integrated swing type power unit 23 also serves as a swing arm and is elastically supported by the rear frame 14 by a rear shock absorber 27. A rear wheel 28 as a driving wheel is held at the rear end of the conduction case 26.
[0016]
FIG. 2 is a horizontal sectional view of the integrated swing type power unit 23 taken along the line II-II in FIG. 1, and the engine 25 is mounted on the front portion of the integrated swing type power unit 23. The engine 25 mainly includes a crankcase 29, a cylinder 30, and a cylinder head 31. A crankshaft 32 is disposed in the crankcase 29 at a right angle to the traveling direction of the vehicle. The center of gravity of the integral swing type power unit 23 is located on the engine center line, that is, on the left side of the movement axis of a reciprocating unit such as a piston described later, for example, on the left side in the figure.
[0017]
FIG. 3 is an enlarged cross-sectional view of the crankshaft 32. As shown in FIGS. 2 and 3, the crankshaft 32 is divided into, for example, left and right, and for convenience, they are referred to as a left crankshaft 32L and a right crankshaft 32R, respectively. Each of the crankshafts 32L and 32R is composed of crank webs 33L and 33R and crank journals 34L and 34R arranged on the left and right of the engine center line. Further, counterweights 35L and 35R are formed on one side of the crank webs 33L and 33R, respectively. The crankshafts 32L and 32R are connected by a crankpin 36 and integrated.
[0018]
A large end of a connecting rod 37 is connected to the crankpin 36. A piston 39 is connected to the small end of the connecting rod 37 via a piston pin 38. The piston 39 reciprocates in the cylinder 30, and the reciprocating stroke is transmitted to the crankshafts 32L and 32R via the connecting rod 37 to rotate the crankshafts 32L and 32R. The crankshafts 32L and 32R are pivotally supported in the crankcase 29 by a pair of bearings 40.
[0019]
On the other hand, as shown in FIG. 2, a drive pulley 42 of a V-belt type automatic transmission 41 provided in the conduction case 26 is attached to the left end portion side of the left crankshaft 32 </ b> L. Thus, the driving force of the engine 25 is transmitted to the driven pulley 44.
[0020]
The driven pulley 44 is rotatably supported by a driven shaft 45 provided at the rear portion of the integral swing type power unit 23, and the rotational driving force transmitted to the driven pulley 44 is driven via the centrifugal clutch mechanism 46. Is transmitted to.
[0021]
The driven shaft 45 is connected to the rear axle 48 through a transmission mechanism 47 that is a reduction gear mechanism and a power transmission device, and the rotation of the engine 25 is transmitted to the rear wheel 28 through the transmission mechanism 47.
[0022]
Further, an alternator 49 constituting a part of the charging device and a cooling fan 50 constituting a part of the engine cooling device are provided on the right end portion side of the right crankshaft 32R.
[0023]
Further, a valve operating device 51 is provided in the cylinder head 31, and a chain drive sprocket 52 is provided on the right crankshaft 32R. A cam sprocket 54 is provided at one end of a cam shaft 53 that constitutes a part of the valve gear 51, and this cam sprocket 54 is connected to a chain drive sprocket 52 by a timing chain 55. Then, the rotation of the crankshafts 32L, 32R is transmitted to the camshaft 53 via the timing chain 55, whereby the valve operating device 51 is operated.
[0024]
4 (a) and 4 (b) are cross-sectional views taken along line IV-IV in FIG. 3, and FIGS. 5 (a) and 5 (b) are cross-sectional views taken along line V-V in FIG. is there.
[0025]
As shown in FIG. 4A, a weight 56 is fixed to the crank web 33L of the left crankshaft 32L with respect to the center of gravity of the integral swing type power unit 23, that is, the engine centerline with screws 57, for example, and the right crankshaft 32R It is set to be heavier than the crank web 33R. As shown in FIG. 5A, a light hole 58 is formed in the crank web 33R and the counterweight 35R of the right crankshaft 32R so as to be lighter than the crank web 33L of the left crankshaft 32L. Also good.
[0026]
Further, as shown in FIGS. 4B and 5B, the counterweight 35L of the left crankshaft 32L with respect to the center of gravity of the engine 25, that is, the engine centerline is larger than the counterweight 35R of the right crankshaft 32R, or The counterweight 35R of the right crankshaft 32R may be formed smaller than the counterweight 35L of the left crankshaft 32L.
[0027]
Next, the operation of this embodiment will be described.
[0028]
As described above, the weight of the crank web 33L of the left crankshaft 32L with respect to the center of gravity of the integrated swing type power unit 23, that is, the engine center line is set to be heavier than the crank web 33R of the right crankshaft 32R. As a result, as shown in FIG. 6, the action line 60 of the excitation force 59 generated by the reciprocating motion of the piston 39 or the like moves to the center of gravity side. The action line 60 of the excitation force 59 moves toward the center of gravity, and the deviation 61 between the center of gravity and the action line 60 becomes smaller than before, so that the rotational moment around the center of gravity becomes smaller than before. Reduces vibration.
[0029]
Fixing the weight 56 to the crank web 33 or drilling the light hole 58 can be easily applied to conventional models. When the weight distribution of the left and right crank webs 33L and 33R can be calculated in advance, the left and right counterweights 35L and 35R may be formed according to the weight distribution, and mass production is possible.
[0030]
【The invention's effect】
As described above, according to the crankshaft of the integral swing type power unit according to the present invention, the integral swing type power unit including the single cylinder engine having the crankshaft pivotally attached to the vehicle body frame and divided into the left and right sides. The crank web of the crankshaft is arranged on the left and right of the engine center line, and among these crank webs, the weight of the crank web on the center of gravity side of the integrated swing type power unit is set to be heavier than the crank web on the other side. Therefore, the vibration in the left-right direction of the engine can be reduced.
[Brief description of the drawings]
FIG. 1 is a view showing an embodiment of a crankshaft of an integral swing type power unit according to the present invention.
FIG. 2 is a horizontal sectional view of the integrated swing type power unit taken along line II-II in FIG.
FIG. 3 is an enlarged sectional view of a crankshaft.
4A and 4B are cross-sectional views taken along line IV-IV in FIG.
5A and 5B are cross-sectional views taken along line VV in FIG.
FIG. 6 is a schematic view of an engine.
FIG. 7 is a schematic view of a conventional engine.
[Explanation of symbols]
11 Scooter type vehicle 12 Body frame 23 Integrated swing type power unit 25 Single cylinder engine 32L, 32R Crankshaft 33L, 33R Crank web 35L, 35R Counterweight 39 Piston 56 Weight 58 Light hole 59 Excitation force generated by reciprocating motion of piston, etc. 60 Line of action 61 of vibration force Deviation between center of gravity and line of action

Claims (1)

A swing unit pivotally attached to a vehicle body frame and having a crankshaft divided into left and right parts, an integrated swing having a conduction case extending rearward from the engine and a rear wheel supported at the rear end of the conduction case Type power unit
The left and right crankshafts are connected and integrated by a crankpin, and are pivotally supported in a crankcase by a pair of bearings, and one of the left and right crankshafts is provided with a drive pulley of a transmission. The crankshaft is equipped with a charging device,
The crank web of the crankshaft is arranged on the left and right of the engine center line, and the integrated swing type power unit is positioned with a center of gravity biased toward one crankshaft side where the transmission is provided,
The crankshaft of an integrated swing type power unit, wherein the weight of the crank web on the center of gravity side that is biased to one side of the engine center line of the integrated swing type power unit is set to be heavier than the crank web on the other side.

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