JP2762128B2 - Case reed valve type engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A. Object of the Invention (1) Field of the Invention The present invention relates to a case reed valve type engine equipped with a starter motor used for a motorcycle, for example.

(2 Prior Art Case reed valve type 2 mounted on motorcycles, etc.
Cycle engines are known for their high efficiency and high output, and also have good performance in refueling the large end of the crank and cooling the piston. Also, various types of motorcycles using a starter motor as an engine starting device have been proposed (for example, see Japanese Patent Application Laid-Open No. 62-289493). In particular, in a family use vehicle, a belt-type continuously variable transmission, a starter motor, The handling is facilitated by combining.

(3) Problems to be Solved by the Invention By the way, when the above-described case reed valve type two-cycle engine is mounted on a motorcycle, an intake system such as a reed valve and a carburetor interferes with the starting device, and the layout becomes difficult. However, there is a problem that the degree of freedom of setting the intake system is hindered and the characteristics of the engine cannot be sufficiently exhibited.

The present invention has been made in view of the above circumstances, and has as its object to effectively utilize space and increase the degree of freedom in designing an intake system by rationally laying out an intake system and a starter of an engine. I do.

B. Configuration of the Invention (1) Means for Solving the Problems In order to achieve the above object, the present invention provides a crankcase provided with a reed valve and a starter motor, and controls the wheels via a belt-type continuously variable transmission. In a case reed valve type engine to be driven, a reed valve is disposed on the back side of a cylinder connected to a crankcase, and a starter motor is disposed at a position facing the reed valve across a crankshaft. A belt-type continuously variable transmission in which a plate-shaped valve body is disposed so as to be able to contact and separate so that the opening surface is parallel to the crank axis and faces the outer periphery of a weight portion of the crank shaft, and is supported by the crank shaft. A starter gear formed on the drive pulley is driven by the starter motor.

(2) Operation According to the present invention having the above-described configuration, the starter motor and the reed valve are disposed so as to face each other across the crankshaft, so that a space is formed on the back surface of the cylinder extending from the crankcase. By arranging the reed valve using this pace, the degree of freedom of the layout of the intake system can be increased.

Further, since the starter gear is formed on the drive pulley of the belt-type continuously variable transmission, a dedicated starter gear is not required, and the number of parts is reduced accordingly.

Further, the reed valve has an opening surface for seating the plate-shaped valve body so as to be able to come and go, and is parallel to the crank axis, and faces the outer periphery of the weight portion of the crank shaft. Even if it is arranged, the space occupied by the valve in the radial direction of the crankshaft can be reduced as much as possible while securing a sufficiently large valve opening surface, and each space for the starter motor and the reed valve is sufficiently secured around the crankshaft.

(3) Example Hereinafter, an example of the present invention will be described with reference to the drawings.

1 to 8 show one embodiment of the present invention. FIG. 1 is an overall side view of a motorcycle equipped with the engine.
FIG. 2 is an enlarged sectional view of a main part of FIG. 1, and FIG. 3 is II of FIG.
FIG. 4 is a sectional view taken along the line IV-IV in FIG. 3, FIG. 5 is a sectional view taken along the line VV in FIG. 3, and FIG.
7 is a side view of the movable pulley half of the driven pulley, and FIG. 8 is an enlarged view of a cam groove.

As shown in FIG. 1, this motorcycle is equipped with a power unit P having an engine E and a transmission case T at the center of a body frame F. A rear fork 1 is pivotally supported by a pivot pin 2 at the rear of the body frame F so as to be vertically swingable. A rear cushion 3 is mounted between the rear fork 1 and the body frame F. A rear wheel Wr supported at the rear end of the rear fork 1 via an axle 4 is connected to the power unit P via a chain 6 wound around a driven sprocket 5 fixed to the axle 4.

As shown in FIGS. 2 and 3, the power unit P
The engine E is a two-cycle rear intake case reed valve type engine, and is mounted on the front of the transmission case T with its cylinder 7 inclined obliquely upward and forward. The reed valve 8 provided in the intake system of the engine E is mounted on the upper end surface of the crankcase 10 corresponding to the back of the cylinder 7 so that the valve housing 8h projects the inner end into the intake port 9. With such an arrangement, the configuration is such that the volume of the crank chamber is as small as possible. Also the housing of the valve
On the inner end face of 8h, an opening face 8b on which the plate-shaped valve element 8a of the reed valve 8 is seated so as to be able to come and go, as is clear from FIG.
The surface 8b is arranged so as to be parallel to the crank axis and facing the outer periphery of the weight portion 15w of the crank shaft 15.

A carburetor 11 and an air cleaner 12 are arranged upstream of the reed valve 8 so as to be located in a space formed between a transmission case T extending rearward and a cylinder 7 inclined upward and forward. Engine E cylinder 7
A crankshaft 15 connected via a connecting rod 14 to a piston 13 slidably fitted in the transmission case T is directed to the left and right direction of the vehicle body via a pair of ball bearings 16, 16.
It is supported by.

A flywheel 18 is fixed to a right end of a crankshaft 15 projecting rightward from the crankcase 10 into the engine cover 17 with a nut 19. A fan 20 for cooling the engine E is integrally fixed to an outer surface of the flywheel 18, and a magnet 22 of a generator 21 is provided with a stator coil 23 on an inner surface of a flange 18 a formed on an outer periphery of the flyhole 18. Is mounted so as to surround the outer periphery of the.

On the other hand, a spline 15a is formed on the crankshaft 15 projecting leftward from the crankcase 10 into the transmission case T, and a spline 15a is formed on the right end of the spline 15a on the fixed side of the drive pulley 52 of the belt-type continuously variable transmission B. A pulley half 26 is fitted and fixed to the crankshaft 15. Also, the crankshaft
At the left end of 15 is a lamp plate with the tightening force of nut 27
28 is fixed so that it cannot rotate relative to the crankshaft 15,
A guide formed in the axial direction of the movable pulley half 29 of the drive pulley 25 supported at the tip thereof with a slide piece 28a rotatably and axially slidable relative to a spline 15a formed on the crankshaft 15. It is slidably engaged with the piece 29a. As a result, the lamp plate 28 rotates integrally with the movable pulley half 29 while allowing the movable pulley half 29 to slide in the axial direction. A centrifugal weight 30 is accommodated in a space formed between the movable pulley half 29 and the ramp plate 28 and tapered outward in the radial direction.
When the rotation speed of the crankshaft 15 increases and the centrifugal force acting on the centrifugal weight 30 increases, the movable pulley half 29 pressed by the centrifugal weight 30 moving radially outward in the tapered space moves to the right. The section between the pulley halves 26 and 29 has been moved, and the space between the pulley halves 26 and 29 has been reduced.
It is configured to move the V-shaped belt 31 outward in the radial direction.

A needle bearing 35 and a ball bearing provided with a grease pocket 34 are provided at the left half of a reduction gear input shaft 33 having a right end and a center supported at a rear portion of the transmission case T via a pair of bale bearings 32. The inner sleeve 37 is supported by 36 so as to be rotatable relative to the reduction gear input shaft 33. Outer sleeve on outer circumference of inner sleeve 37
The inner sleeve 37 and the outer sleeve 38 are supported on the fixed pulley half 40 and the movable pulley half 40 of the driven pulley 39 of the belt-type continuously variable transmission B. 41 are respectively fixed.
A clutch inner 43 of an automatic centrifugal clutch 42 is fixed to a right end of the inner sleeve 37 with a nut 44, and the outer sleeve 38 and the movable pulley half 41 are fixed by a spring 45 mounted between the inner sleeve 37 and the clutch inner 43. Are urged in a direction approaching the fixed pulley half 40.

As shown in FIG. 7, a pin 46 is implanted radially outward on the peripheral surface of the inner sleeve 37, and a roller 47 provided at the tip of the pin 46 is formed on the peripheral surface of the outer sleeve 38. The three cam grooves 48 are engaged. As is apparent from FIG. 8, the cam groove 48 has a substantially triangular shape, and is inclined between the first position P1 and the third position P3 (in the rotational direction leading side) with respect to the circumferential direction of the outer sleeve 38. A traveling cam surface 48b is formed between the second position P2 and the third position P3 (on the rotational direction delay side), and is inclined with respect to the circumferential direction of the outer sleeve 38.

At the rear of the engine E, an automatic centrifugal clutch 42 is disposed in a space formed between the above-described belt-type continuously variable transmission B and a below-described gear reducer. That is, a clutch outer 49 located outside the clutch inner 43 is spline-fitted to the intermediate portion of the reduction gear
Fixed at 50. As is apparent from FIG. 4, the three clutch weights 53 pivotally supported on the side walls of the clutch inner 43 by the pins 51 and urged radially inward by the springs 52 have the inner periphery of the flange 49a of the clutch outer 49. The starting clutch 54 is formed by mounting the friction member 53a facing the surface. On the other hand, as is apparent from FIG. 5, the two clutch weights 57 pivotally supported by the pins 55 on the side walls of the clutch outer 49 and urged radially inward by the springs 56 are provided with flanges 43a of the clutch inner 43. A friction member 57a facing the inner peripheral surface is mounted to constitute an engine brake clutch 58. Therefore, as apparent from FIG. 3, the driven pulley 39 of the reduction gear input shaft 33
A start clutch 54 is arranged on the side, and an engine brake clutch 58 is arranged adjacent to the opposite side.

An input gear 60 integrally formed with the speed reducer input shaft 33 of the gear reducer 59 is a first intermediate gear that is spline-fitted to an intermediate shaft 61 that is supported on the transmission case T below and below the speed reducer input shaft 33.
62, and is formed integrally with the intermediate shaft 61.
The intermediate gear 63 meshes with an output gear 66 press-fitted into a reduction gear output shaft 65 supported by a pair of ball bearings 64 above the rear part of the transmission case T. A drive sprocket 67 is fixed to an end portion of the speed reducer output shaft 65 projecting from the transmission case T to the outside. The drive sprocket 67 is connected to the driven sprocket 5 of the rear wheel Wr via the chain 6. . Second
As is clear from the figure, the intermediate shaft 61 is connected to the reduction gear input shaft 33.
The reduction gear output shaft 65 is disposed behind the intermediate shaft 61 and further above the reduction gear input shaft 33. The length in the direction is shortened.

As shown in FIGS. 2 and 6, the crankcase 10
A starter motor 68 mounted at a position opposite to the reed valve 8 with the crankshaft 15 interposed therebetween is provided with a starter pinion dive mechanism provided inside the transmission case T.
Connected to 69. A starter pinion 70 fixed to the output shaft of the dive mechanism 69 and capable of protruding leftward.
A starter gear 26a is formed on the outer periphery of the fixed pulley half 26 of the drive pulley 25 so as to be positioned on the movement path of the drive pulley 25. Therefore, when the starter motor 68 is started, the starter pinion 70 of the dive mechanism 69 projects leftward and meshes with the starter ring gear 26a, and rotates the crankshaft 15 to which the fixed side pulley half 26 integrated with the starter ring gear 26a is fixed. Then, the engine E is started.

At this time, the starter motor 68 is connected to the crankcase 10
Not only lowers the position of the center of gravity to maintain the balance of the body properly, but also makes the space formed on the back side of the cylinder 7 effective for layout in the reed valve 8, carburetor 11, and air cleaner 12. Used for

On the other hand, as shown in FIG. 3, a kick starter 7 is provided on the rear left side of the transmission case T. That is,
A kick arm 74 having a pedal 73 is fixed to an outer end of a kick shaft 72 pivotally supported on the left wall of the transmission case T,
A drive helical gear 75 is fixed to the inner end. A return spring 76 is mounted between the drive helical gear 75 and the transmission case T so that the kick arm 74 automatically returns to its original position. The driving helical gear
Reference numeral 75 meshes with a driven helical gear 77 supported on the inner surface of the transmission case T so as to be movable in the axial direction. Driven helical gear
A ratchet wheel 78 fixed to the inner end of 77 is opposed to a ratchet tooth 37a formed on the left end of the inner sleeve 37 mounted on the speed reducer input shaft 33 so as to be meshable. A ring-shaped friction spring 79 is in contact with the outer periphery of the ratchet wheel 78, and an end of the friction spring 79 is formed on a wind guide rib 80 formed on the inner wall of the transmission case T.
It is locked to.

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

When the starter motor 68 is started, a starter pinion 70 protruding through the dive mechanism 69 is formed on the outer periphery of the fixed pulley half 26 of the drive pulley 25 and a starter gear.
The engine E is started by driving the crankshaft 15 engaged with the fixed pulley half 26 and engaged with the fixed pulley half 26a. At this time, mounting the starter motor 68 on the lower portion of the crankcase 10 not only lowers the position of the center of gravity to maintain the balance of the vehicle body properly, but also reduces the space formed on the back side of the cylinder 7 by the reed valve 8. And carburetor 11
It is used effectively for layouts. Moreover, since the starter ring gear 26a with which the starter pinion 70 of the starter motor 68 meshes is formed using the outer periphery of the fixed pulley half 26 of the drive pulley 25, there is no need to provide a special starter ring gear and the number of parts is reduced. Is done.

On the other hand, the start of the engine E using the kick starter 71 is performed by kicking the pedal 73 of the kick arm 74 extending from the transmission case T to the outside from the front to the back of the drawing. The kick of the pedal 73 causes the driven helical gear 77, which meshes with the drive helical gear 75, to rotate, at which time the friction spring slides on the ratchet wheel 78.
A resistance is given to the rotation of the driven helical gear 77 by the frictional force received from 79, so that the driven helical gear 77 receives an axial thrust from the driving helical gear 75. This allows
The driven helical gear 77 and the ratchet wheel 78 move rightward integrally, and the ratchet wheel 78 meshes with ratchet teeth 37a formed on the end surface of the inner sleeve 37.
When the inner sleeve 37 rotates, the outer sleeve 38 also rotates through a pin 46 implanted in the inner sleeve 37, and the fixed pulley half 40 and the movable pulley half 40 of the driven pulley 39 fixed to the sleeves 37, 38. Belt 31 wrapped around body 41
Is driven. The rotation of the belt 31 is transmitted to the drive pulley 25, and the crankshaft on which the drive pulley 25 is supported
The rotation of 15 causes the engine E to start.
When the engine E starts and the driven pulley 39 starts rotating, the ratchet wheel 78 is jumped off by the ratchet teeth 37a formed on the inner sleeve 37, and the kick arm 74 is returned to the original position by the return spring 76.

When the engine E is started by the kick starter 71, the driving force of the kick arm 74 is first transmitted to the inner sleeve 37, and as shown in FIG. Is driven in the direction of arrow a. As a result, the pin 46 is formed in the cam groove formed in the outer sleeve 38.
48 to the first position P1 while abutting on the starting cam surface 48a of 48 and pressing the outer sleeve 38 in the direction of arrow b.
The rotation of the inner sleeve 37 is transmitted to the outer sleeve 38. In this manner, the movable-side pulley half 41 is pressed in the direction of the arrow b so as to approach the fixed-side pulley half 40, so that the belt 31 is nipped by the two pulley halves 40 and 41 and slips. This prevents the engine E from starting smoothly. The above operation is performed when the fixed pulley half 40 of the driven pulley 39 rotates prior to the movable pulley half 41 due to the operation of the engine brake, and the slip of the belt 31 is prevented.

When the engine E starts, the rotation of the crankshaft 15 is transmitted from the drive pulley 25 of the belt-type continuously variable transmission B to the driven pulley 39. At this time, the driving force of the belt 31 is first the movable pulley half of the driven pulley 39 with a small load.
It is transmitted to 41. As a result, as shown in FIG. 8, the movable pulley half 41 rotates in the direction of arrow a, and the pin 46 implanted in the inner sleeve 37 contacts the starting cam surface 48b of the cam groove 48, and The rotation of the outer sleeve 38 is transmitted to the inner sleeve 37 while pressing the sleeve 38 in the direction of arrow b toward the second position P2. Also in this case, similarly to the above, the movable-side pulley half 41 is pressed in the direction of arrow b so as to approach the fixed-side pulley half 40, so that the belt 31 is moved.
Is prevented from slipping due to being pinched by the two pulley halves 40, 41, and power transmission at the time of starting with a large load or at the time of climbing a slope is performed smoothly.

As is apparent from FIG. 8, the inclination angle of the starting cam surface 48a with respect to the rotation direction of the outer sleeve 38 (the direction of arrow a) is set smaller than the inclination angle of the traveling cam surface 48b. As a result, the clamping force of the belt 31 at the time of starting, in which the slip of the belt 31 is most likely to occur, is sufficiently increased, and after the start, the pin 46 is moved from the second position P2 to the third position described later.
The movement to the position P3 is not prevented.

When the inner sleeve 37 rotates by the driving force transmitted to the driven pulley 39 as described above, the clutch inner 43 of the automatic centrifugal clutch 42 fixed to the inner sleeve 37 rotates. Then, the clutch weight 53 pivotally supported by the clutch inner 43 expands against the spring 52 by centrifugal force, and the friction member 53a comes into contact with the inner surface of the flange 49a of the clutch outer 49, so that the driving force is applied to the clutch outer 49. Is transmitted. The rotation of the clutch outer 49 is transmitted to the speed reducer input shaft 33 where the clutch outer 49 is spline-fitted,
The rotation of the input gear 60 is transmitted to first and second intermediate gears 62 and 63 fixed to the intermediate shaft 61 and an output gear 66 fixed to the output shaft 65 of the speed reducer. The rotation of the reduction gear output shaft 65 is transmitted to the rear wheel Wr via the driving sprocket 67, the chain 6, and the driven sprocket 5.

When the rotation of the engine E gradually increases, the centrifugal weight 30 attached to the movable pulley half 29 on the drive pulley 25 side of the belt-type continuously variable transmission B moves radially outward by centrifugal force, and the movable pulley The half 29 is moved in a direction approaching the fixed pulley half 26. As the two pulley halves 26 and 29 approach each other, the width of the V space formed therebetween is reduced, and the V-belt 31 moves radially outward of the drive pulley 25. V
When the belt 31 moves outward, the movable pulley half 41 of the driven pulley 39 is pressed by the V-belt 31 and moves rightward against the spring 45 to form between the two pulley halves 40 and 41. The V-belt 31 moves inward in the radial direction of the driven pulley 39. Thus, the continuously variable transmission is performed such that the reduction ratio is large at the low speed rotation of the engine E and is small at the high speed rotation range. When the belt-type continuously variable transmission B is running at a high speed at which the reduction ratio is smallest, the movable pulley half 41 is most separated from the fixed pulley half 40 by the tension of the belt 31, and the pin 46 is It is stably held at the third position P3.

When the rotation of the engine E is reduced during running, the clutch weight 53 pivotally supported by the clutch inner 43 is separated from the flange 49a of the clutch outer 49 by the resilience of the spring 52, and the transmission of the driving force is cut off. However, since the clutch outer 49 approaching the rear wheel Wr is still rotating, the clutch weight 57 pivotally supported on the side wall of the clutch outer 49 expands against the spring 56, and the friction member 57a
Abuts on the flange 43a. As a result, the rotation of the rear wheel Wr is transmitted to the engine E, and the engine brake operates. At this time, the movable side pulley half 41 is
Since the cam surface 48a is provided so as to approach the position 40, the effectiveness of the engine brake is further improved.

C. Effects of the Invention According to the invention described above, the reed valve is disposed on the back side of the cylinder, and the starter motor is disposed at a position facing the reed valve across the crankshaft of the crankcase. A space for installing an intake system such as a carburetor or an air cleaner connected to the reed valve is sufficiently secured without being disturbed by the starting device, and the degree of freedom of the layout can be increased.

In addition, since the starter gear driven by the starter motor is formed on the drive pulley of the belt-type continuously variable transmission, it is not necessary to separately provide a dedicated starter gear, and the number of parts is reduced.

Further, the reed valve is provided with an opening surface on which the plate-shaped valve body is seated so as to be able to come and go, so that the opening surface is parallel to the crank axis and faces the outer periphery of the weight portion of the crankshaft. Even if it is arranged radially outward, the space occupied by the valve in the crankshaft radial direction can be reduced as much as possible while securing the valve opening surface sufficiently wide,
Therefore, sufficient space for the starter motor and the reed valve can be ensured around the crankshaft, and both high output and downsizing of the case reed valve type engine can be achieved.

[Brief description of the drawings]

1 to 8 show an embodiment of the present invention.
The figure is an overall side view of a motorcycle equipped with the engine, FIG. 2 is an enlarged sectional view of a main part of FIG. 1, and FIG. 3 is III in FIG.
FIG. 4 is a sectional view taken along the line IV-IV of FIG. 3, FIG. 5 is a sectional view taken along the line VV of FIG. 3, and FIG.
7 is a side view of the movable pulley half of the driven pulley, and FIG. 8 is an enlarged view of a cam groove. 7 ... cylinder, 8 ... reed valve, 10 ... crankcase, 15 ... crankshaft, 25 ... drive pulley, 26
a Starter gear, 68 Starter motor, B
…… belt type continuously variable transmission, Wr …… rear wheel

Claims (1)

(57) [Claims] 1. A case reed valve type engine having a reed valve (8) and a starter motor (68) in a crankcase (10) and driving wheels (Wr) via a belt type continuously variable transmission (B). , A reed valve (8) is arranged on the back side of a cylinder (7) connected to the crankcase (10), and a starter motor ( 68), and an opening surface (8b) of the reed valve (8) in which the plate-shaped valve element (8a) is seated so as to be able to come in and out of contact with the reed valve (8). The starter ring gear (26a) formed on the drive pulley (25) of the belt-type continuously variable transmission (B) which is arranged so as to face the outer periphery of the weight portion (15w) of the shaft (15) and is supported on the crankshaft (15). The starter motor (68)
A case reed valve type engine, which is driven by: