JP2002181134A - Engine balancer - Google Patents

Abstract

(57) [Summary] (with correction) [PROBLEMS] To provide an engine balancer which prevents mechanical loss and foaming of lubricating oil, and reduces the size of the engine. In an engine (17) in which an axis (24) of a cylinder (25) is inclined substantially horizontally or slightly upward from the horizontal, two balancer shafts (33, 34) each having half the mass of a crank balancer (31) are separated from a crankshaft (29). One balancer shaft 33 is operatively connected to a balancer drive gear 39 provided on the crankshaft 29, and the other balancer shaft 34 is operatively connected to the balancer shaft 33. The balancer weight 37 formed on the balancer shaft 33 is connected to the crank balancer 3.
1, and a balancer weight 38 formed on the other balancer shaft 34 is arranged with a phase difference of 180 ° with respect to the crank balancer 31.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine balancer.

[0002]

2. Description of the Related Art For example, in a single-cylinder or two-cylinder four-stroke engine used in a motorcycle or the like, vibrations due to reciprocating motion of a piston are easily generated. For this reason, some engines have a balancer device for removing the vibration. The balancer device includes, for example, a crank balancer having a web integrally formed on a crankshaft and a balancer weight corresponding to the total mass of a piston, a connecting rod, etc. And a primary balancer device that removes the vibrations.

In order to completely eliminate the primary vibration of the engine, two primary balancers are used for the primary balancer device.
There is a so-called two-axis balancer.

[0004] In a general arrangement of the two-axis balancer, the two-axis balancer is arranged on a straight line passing through the center line of the crankshaft, on both sides of the axis of the cylinder, at the same distance.

[0005]

However, when the primary balancer is disposed on both sides of the cylinder axis, for example, when the cylinder of the engine is arranged substantially upright or slightly inclined forward, the longitudinal length of the engine is increased. This causes the engine to become larger.

In addition, for example, when the cylinder of the engine is arranged substantially horizontally or slightly upward from the horizontal, the lower balancer is immersed in the lubricating oil in the oil pan, so that lubricating oil bubbles due to mechanical loss and agitation, which is not preferable. . Further, the vertical height of the engine is increased, which results in an increase in the size of the engine.

The present invention has been made in view of the above circumstances, and has as its object to provide an engine balancer that prevents mechanical loss and foaming of lubricating oil, and also reduces the size of the engine.

[0008]

According to the present invention, there is provided an engine balancer for solving the above-mentioned problems.
As described in the above, in an engine in which the axis of the cylinder is arranged substantially horizontally or slightly inclined upward from the horizontal, the crank formed on the crankshaft and having the mass necessary to cancel the inertial force acting on the piston and the connecting rod A balancer, and a primary balancer device including two balancer shafts each having half the mass of the crank balancer, wherein the primary balancer device is disposed in a crankcase above the crankshaft, and The balancer driven gear having the same number of teeth as the balancer drive gear provided on the shaft and being operatively connected is provided on the one balancer shaft, and a counter drive gear is provided on the balancer shaft. Has teeth and works A counter driven gear is provided on the other balancer shaft, and the center of gravity of the crank balancer is moved relative to a piston pin connecting the piston and the connecting rod when the piston is located at its top dead center or bottom dead center. In this state, the balancer weight formed on the one balancer shaft is arranged so as to be in phase with the crank balancer, and the balancer weight formed on the other balancer shaft is connected to the crankshaft. It is arranged with a phase difference of 180 ° with the balancer.

In order to solve the above-mentioned problems, an oil pan for storing lubricating oil is formed on the opposite side of the primary balancer device with the crankshaft interposed therebetween. .

Further, in order to solve the above-mentioned problems,
As described in claim 3, the counter drive gear and the counter driven gear of the primary balancer device are arranged so as to mesh with each other on a line passing through the center of the crankshaft orthogonally to the axis of the cylinder.

Further, in order to solve the above-mentioned problem, as described in claim 4, a reinforcing plate is laid over the joint portion of the vehicle body frame, and a pivot shaft for mounting the engine is mounted on the reinforcing plate. In addition, an engine mount is formed on the crankcase near the primary balancer device, and the engine mount is mounted on the pivot shaft.

[0012]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a left side view showing an example of a scooter type vehicle to which the present invention is applied. As shown in FIG. 1, the scooter type vehicle 1 has a body frame 2, and the body frame 2 is a pair of left and right upper frames 3 and lower frames 4, which are vertically separated from each other. The lower frame 4 includes a pair of left and right seat frames 5 extending rearward from near the rear end connecting portion.

Upper frame 3 and lower frame 4
A head pipe 6 is provided at the front end of the head pipe. A front fork 8 for rotatably supporting a front wheel 7 is provided on the head pipe 6.
, A handlebar 9 and the like are provided, and the handlebar 9 steers the front wheel 7 to be rotatable left and right.

An article storage room 10 capable of storing a helmet (not shown) and the like is provided above the seat frame 5, and an operation seat 11 is installed above the article storage room 10 so as to be openable and closable. The body frame 2 is covered by a body cover 12 around the body frame.

FIG. 2 is an enlarged side view of the rear part of the vehicle body. As shown in FIGS. 1 and 2, a joint between the upper frame 3 and the lower frame 4 of the body frame 2 and a joint between the seat frame 5 and the pair of left and right plate-like reinforcing plates 13 are provided.
For example, the front part of the swing type engine unit 15 swings via a link 16 around a pivot shaft 14 provided between the reinforcing plates 13 so as to extend over the lower frame 4 and the seat frame 5. Be worn.

The swing type engine unit 15 includes an engine 17 and a transmission case 18 extending rearward from one side of the engine 17. The transmission case 18 also serves as a swing arm, and as shown in FIG. 1, is elastically supported by the vehicle body frame 2 by a rear shock absorber 19 provided at the lower center of the down tube in front of the pivot shaft 14. Then, a rear wheel 20 as a driving wheel is held at the rear end of the transmission case 18.

By the way, as shown in FIG.
Is connected to a carburetor 21 constituting an engine intake system, and an upstream side of the carburetor 21 is connected to an air cleaner 22 also constituting an engine intake system. The carburetor 21 and the air cleaner 22 are arranged on the front upper side of the engine 17 in front of the pivot shaft 14 and swing integrally with the swing type engine unit 15. Further, a fuel tank 23 is disposed in a lower front part of the engine intake system.

FIG. 3 shows a swing type engine unit 15.
3 is a partial vertical sectional view of FIG. As shown in FIG. 3, an engine 17 is arranged at the front of the swing type engine unit 15. The engine 17 has a cylinder 25 whose axis 24 is inclined substantially forward or slightly upward from the horizontal.
The reciprocating motion of the internal piston 26 rotates the crankshaft 29 which is supported in the crankcase 28 via the connecting rod 27 and extends in the vehicle width direction. On the other hand, an oil pan 30 for storing lubricating oil is formed below the crankshaft 29 of the crankcase 28, and a belt-type automatic transmission (not shown) is arranged in the transmission case 18.

A crank balancer 31 having a mass necessary to cancel the inertial force acting on the piston 26 and the connecting rod 27 is integrally or eccentrically formed on the crankshaft 29. The engine 17 includes a primary balancer device 32 for completely removing the primary vibration.

The primary balancer device 32 is a two-axis balancer having two balancer shafts 33, 34,
The components are collectively arranged in the crankcase 28 above the crankshaft 29. An engine mount 35 on which the link 16 pivotally connected to the pivot shaft 14 is held is provided on the crankcase 28 near the primary balancer device 32.
Is formed.

The two balancer shafts 33 and 34 extend in the vehicle width direction similarly to the crankshaft 29 and are arranged in parallel with the crankshaft 29. One of the two balancer shafts 33 and 34 (hereinafter, referred to as a first balancer shaft 33 for the sake of description) is a line passing through the center of the crankshaft 29 at right angles to the axis 24 of the cylinder 25. While being arranged behind 36,
The other balancer shaft (hereinafter, referred to as a second balancer shaft 34 for the sake of explanation) is disposed forward of a line 36 passing through the center of the crankshaft 29. The distance between the line 36 passing through the center of the crankshaft 29 and the first balancer shaft 33 and the second balancer shaft 34 is set to the same distance.

The first balancer shaft 33 and the second balancer shaft 34 are respectively connected to the crank balancer 3.
The weights of the first and second balancers 37, 3 are set so that the weight of the first and second balancer shafts is equal to half of that of the crank balancer 31.
8 are integrally or eccentrically formed.

A balancer drive gear 39 is provided on the crankshaft 29, and a balancer driven gear 40 having the same number of teeth as the balancer drive gear 39 and operatively connected is provided on the first balancer shaft 33, for example. .

Further, a counter drive gear 41 is provided on the first balancer shaft 33, and a counter driven gear 42 having the same number of teeth as the counter drive gear 41 and operatively connected is provided on the second balancer shaft 34. Can be The counter drive gear 41 and the counter driven gear 42 mesh on a line 36 passing through the center of the crankshaft 29.

The center of gravity of the crank balancer 31 is positioned symmetrically with respect to the piston pin 43 connecting the piston 26 and the connecting rod 27 when the piston 26 is located at its top dead center or bottom dead center, that is, the cylinder 25. Are arranged on the axis 24 of In this state, the first balancer weight 37 of the first balancer shaft 33 is arranged so as to be in phase with the crank balancer 31, and the second balancer weight 38 of the second balancer shaft 34 is shifted 180 ° from the crank balancer 31. They are arranged with a phase difference.

FIGS. 4A to 4D show the positional relationship between the crank balancer 31 and the first and second balancer weights 37 and 38 at each position.

Next, the operation of the present embodiment will be described.

The mass W _k of the crank balancer 31 is shown in FIG.
As shown in the figure, when the position of α from the axis 24 of the cylinder 25 is _defined as the reciprocating weight part _Wre ,

## EQU1 ## It can be obtained by W _k = W _re × sin (α−π / 2). Thereby, the crankshaft 29

## EQU2 ## Vibration is made straight in the direction of ψ = α−π / 2.

By forming the crankshaft 29 with the crank balancer 31 having a mass necessary to cancel the inertial force acting on the piston 26 and the connecting rod 27, the vibration generated by the reciprocating motion of the piston 26 is canceled.

A primary balancer device 32 composed of a first balancer shaft 33 and a second balancer shaft 34 whose total mass is equal to the mass of the crank balancer 31.
When the piston 26 is located at the top dead center or the bottom dead center (top dead center = 0 °, see FIG. 4A, bottom dead center = 1
80 °, see FIG. 4 (c)), first balancer shaft 33
If the first balancer weight 37 of the second balancer shaft 34 is arranged so as to be in phase with the crank balancer 31 and the second balancer weight 38 of the second balancer shaft 34 is arranged with a phase difference of 180 ° from the crank balancer 31, the piston When 26 is located 90 ° before and after its top dead center or bottom dead center (90 °, see FIG. 4B), 270 °, FIG.
(See (d)), since the first balancer shaft 33 and the second balancer shaft 34 and the crank balancer 31 have opposite phases, the exciting force in the direction orthogonal to the axis 24 of the cylinder 25 is canceled.

Further, the primary balancer device 32 composed of the first balancer shaft 33 and the second balancer shaft 34 is connected to the crankcase 2 above the crankcase 28.
8, the crankcase 2
8, that is, the engine 17 can be made compact, and the gears of the shafts 33 and 34 can be easily driven, so that the weight and the number of parts can be reduced.

In the embodiment of the present invention, the primary balancer device 32 is connected to the crankcase 28 above the crankshaft 29 in the engine 17 in which the axis 24 of the cylinder 25 is inclined substantially horizontally or slightly upward from the horizontal.
In the example shown, the cylinders are arranged almost vertically or slightly inclined forward (not shown).
In the above, the primary balancer device may be collectively disposed in the crankcase in front of or behind the crankcase, and the front-rear length of the engine can be reduced as compared with the conventional one.

On the other hand, the opposite side of the primary balancer device 32 across the crankshaft 29, that is, the crankcase 2
By forming the oil pan 30 for storing the lubricating oil below the crankshaft 29, the primary balancer device 32 is prevented from being immersed in the lubricating oil in the oil pan 30. As a result, mechanical loss is reduced, and since the lubricating oil is not agitated, foaming of the lubricating oil and occurrence of cavitation are prevented.

Also, by arranging the counter drive gear 41 and the counter driven gear 42 of the primary balancer device 32 so as to mesh with each other on a line 36 passing through the center of the crankshaft 29 orthogonally to the axis 24 of the cylinder 25, the first The balancer shaft 33 and the second balancer shaft 34 extend from the center of the crankshaft 29 to the cylinder 2.
5 can be extended substantially uniformly in the direction of the axis 24, so that the size of the crankcase 28 can be reduced.

Further, when an engine mount 35 for holding the link 16 pivotally connected to the pivot shaft 14 is formed on the crankcase 28 near the primary balancer device 32, the vibration is reduced at this location by the primary balancer device 32. Because of the location, the vibration transmitted to the mount bush (not shown) is reduced, and the durability of the mount bush is improved.

Further, since the engine mount 35 is connected to the connecting portion between the upper frame 3 and the lower frame 4 of the vehicle body frame 2 and the connecting portion between the seat frame 5 through the reinforcing plate 13, the mounting strength is increased.

[0038]

As described above, according to the engine balancer of the present invention, in an engine in which the axis of the cylinder is inclined forward substantially horizontally or slightly upward from horizontal, the piston is formed on the crankshaft. A crank balancer having a mass necessary to cancel the inertial force acting on the connecting rod, and a primary balancer device including two balancer shafts each having half the mass of the crank balancer are provided. A balancer driven gear having the same number of teeth as the balancer drive gear provided on the crankshaft and being operatively connected is provided on the one balancer shaft while being disposed in the crankcase above the crankshaft. Set the counter drive gear on the balancer shaft. A counter driven gear having the same number of teeth as the counter drive gear and being operatively connected is provided on the other balancer shaft, while the center of gravity of the crank balancer is located at the top dead center or the bottom dead center of the piston. When the piston pin and the connecting rod are connected, the piston pin is disposed symmetrically with respect to the piston pin, and in this state, the balancer weight formed on the one balancer shaft is disposed so as to be in phase with the crank balancer. At the same time, since the balancer weight formed on the other balancer shaft is arranged with a phase difference of 180 ° from the crank balancer,
The engine vibration can be reduced and the engine can be made more compact.

Further, since an oil pan for storing lubricating oil is formed on the opposite side of the primary balancer device with the crankshaft interposed therebetween, mechanical loss is reduced, and foaming of lubricating oil and cavitation are prevented.

Further, since the counter drive gear and the counter driven gear of the primary balancer device are arranged so as to mesh with each other on a line passing through the center of the crankshaft orthogonal to the axis of the cylinder, the size of the crankcase can be reduced.

Further, a reinforcing plate is laid over the connecting portion of the vehicle body frame, a pivot shaft for mounting the engine is mounted on the reinforcing plate, and an engine mount is formed on the crankcase near the primary balancer device. However, since the engine mount is mounted on the pivot shaft, the durability and strength of the mount are increased.

[Brief description of the drawings]

FIG. 1 is a left side view of a scooter type vehicle showing an embodiment of an engine balancer according to the present invention.

FIG. 2 is an enlarged side view of a rear portion of the vehicle body.

FIG. 3 is a partial vertical sectional view of a swing type engine unit.

FIGS. 4A to 4D are diagrams showing a positional relationship between a crank balancer and first and second balancer weights at respective positions.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Scooter type vehicle 2 Body frame 3 Upper frame (body frame) 4 Lower frame (body frame) 5 Seat frame (body frame) 13 Reinforcement plate 14 Pivot shaft 15 Swing type engine unit 17 Engine 24 Cylinder axis 25 Cylinder 26 Piston 27 Connecting rod 28 Crankcase 29 Crankshaft 30 Oil pan 31 Crank balancer 32 Primary balancer device 33 First balancer shaft 34 Second balancer shaft 35 Engine mount 36 Line orthogonal to the cylinder axis and passing through the center of the crankshaft 37 First balancer weight 38 Second balancer weight 39 Balancer drive gear 40 Balancer driven gear 41 Counter drive gear 42 Counter driven gear 43 Piston pin

Claims (4)

[Claims] A crank balancer formed on a crankshaft and having a mass necessary for canceling an inertial force acting on a piston and a connecting rod in an engine in which an axis of a cylinder is inclined substantially forward or slightly upward from the horizontal. And a primary balancer device composed of two balancer shafts each having half the mass of the crank balancer. The primary balancer device is disposed in a crankcase above the crankshaft, and the crankshaft The balancer driven gear having the same number of teeth as the balancer drive gear provided on the one balancer shaft is provided, and a counter drive gear is provided on the balancer shaft, and the same number of teeth as the counter drive gear is provided. Having number and operative connection When the piston is located at the top dead center or the bottom dead center of the piston, the center of gravity of the crank balancer is provided on the other balancer shaft. In this state, the balancer weight formed on the one balancer shaft is arranged so as to be in phase with the crank balancer, and the balancer weight formed on the other balancer shaft is connected to the crank balancer in this state. And a 180 ° phase difference. 2. The engine balancer according to claim 1, wherein an oil pan for storing lubricating oil is formed on the opposite side of said primary balancer device with respect to said crankshaft. 3. The balancer for an engine according to claim 1, wherein the counter drive gear and the counter driven gear of the primary balancer device are arranged so as to mesh with each other on a line passing through the center of the crankshaft orthogonally to the axis of the cylinder. . 4. An engine mount is formed on a connecting portion of the vehicle body frame, a reinforcing plate is provided over the connecting portion of the vehicle body frame, a pivot shaft for mounting the engine is mounted on the reinforcing plate, and an engine mount is formed on the crankcase near the primary balancer device. 4. The engine balancer according to claim 1, wherein said engine mount is mounted on said pivot shaft.