JPH03111620A - Case lead valve type engine - Google Patents

Abstract

PURPOSE:To effectively use a space and to increase latitude in design of an air intake system by providing a lead valve at a rear face side of a cylinder and a starter motor at a position opposite to the lead valve with a crank shaft sandwiched therebetween. CONSTITUTION:In a case lead valve type engine E having a lead valve 8 and a starter motor 68, the lead valve 8 mounted on a crank case 10 is disposed at a rear face side of a cylinder 7. The starter motor 68 is disposed at a position opposite to the lead valve 8 with a crank shaft 15 of the crank case 10 held therebetween. Since the starter motor 68 and the lead valve 8 are disposed so as to sandwich the crankshaft 15 therebetween, a space is formed in a rear face of the cylinder 7 extending from the crank case 10. The lead valve 8 is disposed by using this space. Accordingly, the latitude in the layout of an air intake system is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION A0 OBJECTS OF THE INVENTION (1) Industrial Field of Application The present invention relates to a case reed valve type engine equipped with a starter motor used, for example, in a motorcycle.

(2) Conventional technology Case reed valve type two-stroke engines installed in motorcycles, etc. are known for their high efficiency and high output, and also have good performance in terms of oil supply to the big end of the crank and cooling of the piston. have. In addition, various types of engine starting devices for motorcycles using starter motors have been proposed (for example, see Japanese Patent Application Laid-open No. 62-289493), and especially for family-use vehicles, belt-type continuously variable transmissions and starter motors have been proposed. By combining these, ease of handling is achieved.

(3) Problems to be Solved by the Invention By the way, when the case reed valve type two-stroke engine described above is mounted on a motorcycle, the intake system such as the reed valve and carburetor may interfere with the starting device, making the layout difficult. However, there is a problem in that the degree of freedom in designing the intake system is inhibited, and the characteristics of the engine cannot be fully demonstrated.

The present invention was made in view of the above-mentioned circumstances, and aims to effectively utilize space and increase the degree of freedom in designing the intake system by rationally rewiring out the engine intake system and starting device. shall be.

B9 Structure of the Invention (1) Means for Solving the Problems In order to achieve the above object, the present invention provides a reed valve mounted on a crankcase in a case reed valve type engine equipped with a reed valve and a starter motor. is disposed on the rear side of the cylinder, and a starter motor is disposed at a position facing the reed valve with the crankshaft of the crankcase interposed therebetween.

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

(3) Examples Hereinafter, the present invention will be described in detail based on the drawings.

Figures 1 to 8 show one embodiment of the present invention.
The figure is an overall side view of a motorcycle equipped with this engine, Figure 2 is an enlarged sectional view of the main part of Figure 1, and Figure 3 is the ■-- of Figure 2.
4 is a sectional view taken along the IV-IV line in Figure 3, Figure 5 is a sectional view taken along the ■-V line in Figure 3, and Figure 6 is a sectional view taken along the
-VI line sectional view, FIG. 7 is a side view of the movable pulley half of the driven pulley, and FIG. 8 is an enlarged view of the cam groove.

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

As shown in FIGS. 2 and 3, the engine E of the power unit P is a two-stroke rear intake case reed valve type engine, and the transmission case T is mounted with the cylinder 7 obliquely inclined forward and upward. It is attached to the front. The reed valve 8 is mounted on the upper wall surface of the crankcase 10 on the back side of the cylinder 7 so that the valve body 8a protrudes into the intake boat 9.The arrangement of the valve body 8a of the reed valve 8 allows the crank chamber to be closed. It is constructed so that its volume is as small as possible. reed valve 8
On the upstream side of the engine, a carburetor 11 and an air cleaner 12 are arranged so as to be located in a space formed between a transmission case T extending rearward and a cylinder 7 inclined in a curved manner. A crankshaft 15 connected via a connecting rod 14 to a piston 13 slidably fitted into a cylinder 7 of an engine E is connected to a pair of ball bearings 16, 16.
is supported by the transmission case T in the left-right direction of the vehicle body.

A flywheel 1 is attached to the right end of the crankshaft 15 that protrudes rightward from the crankcase 10 into the engine cover 17.
8 is fixed with a nut 19.

A fan 20 for cooling the engine E is integrally fixed to the outer surface of the flywheel 18, and a magnet 22 of a generator 21 is attached to a stator coil 23 on the inner surface of a flange 18a formed on the outer periphery of the flywheel 18. It is attached so as to surround the outer periphery of the

On the other hand, a spline 15a is formed on the crankshaft 15 that protrudes leftward from the crankcase 10 into the transmission case T, and at the right end of this spline 15a is the fixed side of the drive boo 1J25 of the belt type continuously variable transmission B. A pulley half 26 is fitted onto and fixed to the crankshaft 15. Further, a ramp plate 28 is fixed to the left end of the crankshaft 15 by the tightening force of a nut 27 so that it cannot rotate relative to the crankshaft 15, and a slide piece 28a provided at the tip of the ramp plate 28 is attached to a spline formed on the crankshaft 15. 15a
The drive pulley 25 is slidably engaged with a guide piece 29a formed in the axial direction of the movable half-boot half 29 of the drive pulley 25, which is supported to be relatively rotatable and slidable in the axial direction. As a result, the lamp plate 28 is attached to the movable boom half 2
9 while allowing sliding movement in the axial direction of the movable boob half 2.
Rotates together with 9. A centrifugal weight 30 is housed in a space formed between the movable pulley half 29 and the ramp plate 28 that tapers outward in the radial direction, and the rotational speed of the crankshaft 150 increases to act on the centrifugal weight 30. When the centrifugal force increases, the movable pulley half 29 pressed by the centrifugal weight 30 that moves radially outward in the space of the Taber cane moves to the right, and the fixed pulley half 2
The belt 31, which has a V-shaped cross section and is sandwiched between both pulley halves 26 and 29, is moved radially outward.

A needle bearing 35 and a ball bearing are provided on the left half of the reducer input shaft 33, whose right end and center are supported via a pair of ball bearings 32 at the rear of the transmission case T, with a grease pocket 34 in between. An inner sleeper 37 is supported by 36 so as to be rotatable relative to the reducer input shaft 33. An outer sleeve 38 is supported on the outer periphery of the inner sleeve 37 so as to be relatively rotatable and movable in the axial direction. pulley half body 40 and movable pulley half body 41
are each fixed.

An automatic centrifugal clutch 4 is located at the right end of the inner sleeper 37.
A clutch inner 43 of No. 2 is fixed with a nut 44, and a spring 45 installed between the clutch inner 43 and the outer sleeve 38 and the movable bobbin half 41 approaches the stationary pulley half 40. biased in the direction.

As shown in FIG. 7, a bottle 46 is installed on the circumferential surface of the inner sleep 37 facing outward in the radial direction.
A roller 47 provided at the tip of the outer sleeve 6 engages with three cam grooves 48 formed on the circumferential surface of the outer sleeve 3. As is clear from FIG. 8, the cam groove 48 has a roughly triangular shape, and is inclined with respect to the circumferential direction of the outer sleeve 38 between the first position P1 and the third position P3 (advanced side in the rotational direction). The starting cam surface 48a is also in the second position P.
A running cam surface 48b that is inclined with respect to the circumferential direction of the outer sleeve 38 is formed between the second and third positions P3 (rotational direction delay side).

At the rear of the engine E, an automatic centrifugal clutch 42 is disposed in a space formed between the belt-type continuously variable transmission B described above and the gear reduction gear described below. That is, a clutch outer 49 located outside the clutch inner 43 is spline-fitted to an intermediate portion of the reducer input shaft 33 and fixed with a nut 50 . As is clear from FIG. 4, the three clutch weights 53, which are pivotally supported on the side wall of the clutch inner 43 by pins 51 and biased radially inward by springs 52, are attached to the inner periphery of the flange 49a of the clutch outer 49. A friction member 53a facing the surface is attached to constitute an acceleration clutch 54. On the other hand, the fifth
As is clear from the figure, two clutch weights 57, which are pivotally supported on the side wall of the clutch outer 49 by a pin 55 and biased radially inward by a spring 56, are provided with two clutch weights 57 that are opposed to the inner circumferential surface of the flange 43a of the clutch inner 43. A friction member 57a is attached to the engine brake clutch 58.
is configured. Therefore, as is clear from FIG. 3, the starting clutch 54 is disposed adjacent to the driven pulley 39 side of the reducer input shaft 33, and the engine braking clutch 58 is disposed adjacent to the opposite side thereof.

An input gear 60 integrally formed with the reducer input shaft 33 of the gear reducer 59 is connected to a first intermediate shaft 61 that is spline-fitted to an intermediate shaft 61 that is pivotally supported at the rear and lower side of the reducer input shaft 33 of the transmission case T.
A second intermediate gear 63 that meshes with the intermediate gear 62 and is formed integrally with the intermediate shaft 61 is connected to the reducer output shaft 6 which is supported above the rear part of the transmission case T by a pair of pole bearings 64.
It meshes with the output gear 66 press-fitted into the gear 5. A drive sprocket 67 is fixed to the end of the reducer output shaft 65 that projects outside from the transmission case T, and this drive sprocket 67 is connected to the driven sprocket 5 of the rear wheel Wr via the chino 6. . As is clear from Figure 2,
The intermediate shaft 61 is disposed behind and below the reducer input shaft 33, and the reducer output shaft 65 is disposed behind the intermediate shaft 61 and further above the reducer input shaft 33. As a result, the length of the gear reducer 59 in the longitudinal direction of the vehicle body is shortened.

As shown in FIGS. 2 and 6, the crankcase 10
, i.e. the intake boat 9 with the reed valve 8
A starter motor 68 mounted on the opposite side of the crankshaft 15 is connected to a well-known starter pinion jumping mechanism 69 provided inside the transmission case T. The fixed pulley half 2 of the drive pulley 25 is positioned in the movement path of the starter pinion 70 which is fixed to the output shaft of the plunge mechanism 69 and can protrude leftward.
A starter ring gear 26a is formed on the outer periphery of 6. Therefore, when the starter motor 68 is started, the starter pinion 70 of the jump mechanism 69 projects to the left and meshes with the starter ring gear 26a, rotating the crankshaft 15 to which the stationary pulley half 26, which is integral with the starter ring gear 26a, is fixed. Then engine E is started.

On the other hand, as shown in FIG. 3, a kick starter 71 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 the outer end of a kick shaft 72 pivotally supported on the left wall of the transmission case T, and a drive helical gear 75 is fixed to the inner end thereof. A return spring 76 is installed between the drive helical gear 75 and the transmission case T to automatically return the kick arm 74 to its original position.

The drive helical gear 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. A ratchet wheel 78 fixed to the inner end of the driven helical gear 77 is engaged with ratchet teeth 37a formed on the left side of the inner sleeve 37 attached to the reducer input shaft 33. A ring-shaped friction spring 79 is in contact with the outer periphery of the ratchet wheel 78, and the end metal of the friction spring 79 is engaged with an air guiding rib 80 formed on the inner wall of the transmission case T.

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

When the starter motor 68 is started, the starter pinion 70 that protrudes through the plunger n69 is connected to the drive pulley 2.
The engine E is started by driving the crankshaft 15 to which the fixed pulley half 26 is fixed.

At this time, the starter motor 68 is connected to the crankcase 1.
By installing it at the bottom of the cylinder 7, it not only lowers the center of gravity and maintains the balance of the vehicle properly, but also lowers the center of gravity.
The space formed on the back side is effectively used for the layout of the reed valve 8 and capretor If.

On the other hand, starting the engine E using the kick starter 71 is performed by kicking the pedal 73 of the kick arm 74 extending outward from the transmission case T from the front to the back of the page. The kick of the pedal 73 rotates the driven helical gear 77 that meshes with the driving helical gear 75, and at this time, the driven helical gear 7 is rotated by the frictional force received from the friction spring 79 that slides on the ratchet wheel 78.
Since resistance is applied to the rotation of the driven helical gear 77, an axial thrust is applied to the driven helical gear 77 from the driving helical gear 75. As a result, the driven helical gear 77 and the ratchet wheel 78 move together to the right, and the ratchet wheel 78 meshes with the 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 via the pin 46 implanted in the inner sleeve 37, and the fixed pulley half 40 and the movable pulley half of the driven pulley 39 fixed to both sleeves 37 and 38 are rotated. The belt 31 wrapped around the body 41 is driven. The rotation of the belt 31 is transmitted to the drive pulley 25, and the drive pulley 25 is supported by the crankshaft 15.
The engine E is started by rotating. When the engine E starts and the driven pulley 39 starts rotating, the ratchet teeth 37a formed on the inner sleeve 37
The ratchet wheel 78 is thrown away, and the kick arm 74 is returned to its original position by the return spring 76.

Now, when the engine E is started by the above-mentioned 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 comes into contact with the starting cam surface 48a of the cam groove 48 formed in the seventh outer sleeve 38, presses the outer sleeve 3B in the direction of the arrow, and moves toward the first position pt, causing the inner sleeve 37 to rotate. is transmitted to the outer sleeve 38. In this way, the movable half-boot 41 is pressed in the direction of the arrow so as to approach the fixed pulley half 40, and the belt 31 is pinched between the two half-boots 40 and 41. Slippage is prevented and engine E can be started smoothly.

The above action is also performed when the stationary side boolean half 40 of the driven pulley 39 rotates in advance of the movable side pulley half 41 due to the operation of the engine brake, and the belt 31
slips are 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 transmitted to the movable pulley half 41 of the driven pulley 39, which has a small load. For this purpose, as shown in FIG. 8, the movable pulley half 41 rotates in the direction of arrow a.
The pin 46 implanted in the inner sleeve 37 comes into contact with the starting cam surface 48b of the cam groove 48 and presses the outer sleeve 38 in the direction of the arrow while moving toward the second position P2.
The rotation of the outer sleeve 38 is transmitted to the inner sleeve 37. In this case as well, the movable pulley half 4
1 is pressed in the direction of the arrow so that the belt 31 approaches both pulley halves 40.
0.41, which prevents slipping and ensures smooth power transmission when starting or climbing under heavy loads.

As is clear from FIG. 8, the angle of inclination of the starting cam surface 48a with respect to the rotational direction of the outer sleeve 38 (direction of arrow a) is set smaller than the angle of inclination of the running cam surface 48b. This sufficiently increases the clamping force of the belt 31 during start-up, when the belt 31 is most likely to slip, and prevents the pin 46 from interfering with the movement of the pin 46 from the second position P2 to the third position P3, which will be described later. It has become.

When the inner sleeve 37 is rotated 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 is rotated.

Then, the clutch weight 53 pivotally supported by the clutch inner 43 expands against the spring 52 due to centrifugal force, and the friction member 53a contacts the inner surface of the flange 49a of the clutch outer 49, thereby applying driving force to the clutch outer 49. communicated. The rotation of the clutch outer 49 is transmitted to the reducer input shaft 33 to which the clutch outer 49 is spline-fitted, and the input gear 600 rotations are transmitted to the first and second intermediate gears 62, 63 fixed to the intermediate shaft 61, and the reducer. Output shaft 6
5 is transmitted to an output gear 66 fixed to the output gear 66. The rotation of the reducer output shaft 65 is controlled by the driving sprocket 67 and the chino 6.
, is transmitted to the rear wheel Wr via the driven sprocket 5.

Now, as the rotation of the engine E gradually increases, the centrifugal weight 30 attached to the movable pulley half 29 of the drive boo 1725gIj of the belt type continuously variable transmission B moves radially outward due to centrifugal force, and the movable pulley half The body 29 is moved in the direction approaching the fixed side booby half body 26. As the two pulley halves 26 and 29 approach, the width of the V space formed between them is sandwiched, and the belt 31 is moved to the radius of the drive pulley 25. Move outward in the direction. ■ When the belt 31 moves outward, the movable bobbin half 41 of the driven pulley 39 moves as described above.
Pressed by the belt 31, it moves to the right while resisting the spring 45, and is formed between the two pulley halves 40 and 41.
The width of the space has expanded, ■The belt 31 is a driven pulley 39
move radially inward. As a result, continuously variable transmission is performed such that the reduction ratio is large in the low speed rotation range of the engine E and small in the high speed rotation range. During high-speed running when the reduction ratio of the belt-type continuously variable transmission B is the smallest, the tension of the belt 31 causes the movable pulley half 41 to be furthest away from the fixed pulley half 40, and the pin 46 is in the cam groove 48. It is stably held at the third position P3.

When the rotation of the engine E is decelerated while driving, the clutch weight 53 pivotally supported on the clutch inner 43 is moved by the spring 5.
The second elastic force separates the clutch outer 49 from the flange 49a, cutting off the transmission of driving force. However, since the clutch outer 49 connected to the rear wheel Wr side is still rotating, the clutch weight 57 pivotally supported on its side wall expands against the spring 56, and the friction member 57a
contacts the flange 43a of the clutch inner 43. As a result, the rotation of the rear wheel Wr is transmitted to the engine E side, and the engine brake is activated. At this time, since the cam surface 48a is provided so that the movable pulley half 41 approaches the stationary boolean half 40, the effectiveness of the engine brake is further improved.

C8 Effects of the Invention According to the invention described above, the lead pulp is disposed on the back side of the cylinder, and the starter motor is further disposed at a position facing the lead pulp across the crankshaft of the crankcase. A space is secured for installing an intake system such as a carburetor and an air cleaner connected to the pulp, making it possible to increase the degree of freedom in its layout.

[Brief explanation of drawings]

Figures 1 to 8 show one embodiment of the present invention.
The figure is an overall side view of a motorcycle equipped with this engine, Figure 2 is an enlarged sectional view of the main part of Figure 1, and Figure 3 is the ■-- of Figure 2.
■ Line sectional view, Figure 4 is the IV-IV line sectional view in Figure 3, Figure 5 is the V-V line sectional view in Figure 3, Figure 6 is Vl in Figure 2.
-Vl line sectional view, FIG. 7 is a side view of the movable pulley half of the driven pulley, and FIG. 8 is an enlarged view of the cam groove. 7...Cylinder, 8...Lead pulp, IO...
Crank case, 15... Crankshaft, 68... Starter motor Figure 5 Figure 4 Procedure amendment (voluntary) October 19, 1990 Patent application No. 1-246763 Name of the invention Case reed valve type engine Relationship with the case of the person making the amendment Patent applicant

Claims (1)

[Claims] In a case reed valve type engine equipped with a reed valve (8) and a starter motor (68), the reed valve (8) attached to the crankcase (10)
) is disposed on the rear side of the cylinder (7), and a starter motor (68) is disposed at a position facing the reed valve (8) across the crankshaft (15) of the crankcase (10). Case reed valve type engine.