JPH0443820A - Two-cycle engine - Google Patents

Abstract

PURPOSE:To improve accuracy of a rotary valve by forming one side inner face of a valve chamber by means of a crank case cover, and forming the other side face by means of a valve cover. CONSTITUTION:A valve chamber 56 is formed in a thin disc-shaped space surrounded by a crank case cover 31 and a valve cover 54, and a sectoral valve plate 57 is slidably inserted in the valve chamber 56. The inner face of the valve chamber 56 is formed by means of the crank case cover 31, and the other inner face is formed by means of the valve cover 54. Namely, each inner face of the valve chamber 56 is formed by means of each face of a member. A crank case can be formed with its light weight, and accuracy of the rotary valve can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a two-stroke engine equipped with an intake rotary valve.

(Prior art) Conventionally, two-stroke engines are
There is one shown in Publication No. 01212.

According to this, the crankcase is divided into an upper case and a lower case with the crankshaft as a boundary, and the crankshaft is rotatably supported between these two cases.

An intake port is formed in a side wall of the upper case on one axial end side of the crankshaft, and a low-return valve for opening and closing the intake port is provided. This rotary valve has a valve cover that covers the outer surface of the side wall of the crankcase at one end of the crankshaft, and also has a valve chamber formed by a space between the outer surface of the side wall of the crankcase and the valve cover. There is. A valve plate is housed in the valve chamber so as to be slidable on the inner surface of the valve chamber, and the valve plate rotates along with the crankshaft to repeatedly open and close the intake port.

As a result, the intake port is opened at a predetermined crank angle, and a desired intake timing can be obtained.

(Problems to be Solved by the Invention) According to the above-mentioned conventional configuration, both inner surfaces of the valve chamber facing each other function as guide surfaces when the valve plate rotates. Since the inner surface is formed across the two members of the upper case and the lower case, there is a possibility that a step may occur on the inner surface of the valve chamber at the joint between these two cases, which may cause problems in terms of accuracy.

(Objective of the Invention) This invention was made in view of the above-mentioned circumstances, and an object thereof is to make a crankcase lightweight and to improve the accuracy of a rotary valve.

(Structure of the Invention) The present invention is characterized in that a crankshaft is housed in a crank chamber within a crankcase body, and a side wall of the crankcase body at one end of the crankshaft in the axial direction an opening is formed in the crankshaft, through which the crankshaft can be inserted into and removed from the crank chamber;
A crankcase cover is provided that allows the opening to be opened and closed, a crankshaft is rotatably supported by the crankcase body and the crankcase cover, an intake port is formed in the crankcase cover, and the crankcase cover is provided with an intake port. A valve cover is provided to cover the outer surface of the crankcase cover, a valve chamber is formed in the space between the crankcase cover and the valve cover, and the valve plate is housed in this valve chamber so as to be able to slide freely on the inner surface of the valve chamber. However, the valve plate is attached to the crankshaft, and the valve plate, which rotates with the crankshaft, repeatedly opens and closes the intake port.

(for production) The effects of the above configuration are as follows.

Both inner surfaces facing each other in the valve chamber 56 function as guide surfaces when the valve plate 57 rotates, and one inner surface is connected to the crankcase cover 31.
The other inner surface is formed by the valve cover 54. That is, since each inner surface of the valve chamber 56 is formed by the surface of one member, conventionally, the inner surfaces of the valve chamber 56 in 27 crankcases were formed over two members. In comparison, accuracy problems are less likely to occur.

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

In FIG. 2, reference numeral 1 denotes a motorcycle, and its body frame 2 has one main frame 3, and this main frame 3 has a box-shaped cross section and a rear bulge. A front fork 4 is supported at the front end of the main frame 3 so as to be steerable. A front wheel 5 is supported at the lower end of the front fork 4, and a handle 6 is attached to the upper end of the front fork 4. Also, 7 is a cowling.

Further, a pair of left and right rear arm brackets 8 are integrally molded downward from the rear end of the main frame 3, and a rear arm 10 is pivoted to the rear arm bracket 8 by a pivot shaft 9 so as to be vertically swingable. The front and rear middle parts of the rear arm 10 are connected to the main frame 31 via a shock absorber (not shown).
This is supported. A rear wheel 11 is supported at the swing end of this rear arm lO.

Reference numeral 13 denotes a two-stroke engine, and a power transmission device 14 is connected to the engine 13, and the engine 13 and the power transmission device 4 are supported by the rear part of the main frame 3 and the lower part of the rear arm bracket 8. . The sill 13a of the engine 13 projects forward, and the rear end of an intake chamber 15 extending substantially horizontally in the front-rear direction is connected to the intake port of the engine 13.

Further, an exhaust port is opened on the lower surface of the cylinder 13a, and an exhaust pipe 16 extends rearward from the exhaust port. Furthermore, the inside of the main frame 3 serves as a fuel tank, from which fuel is supplied to the engine 13. Further, a radiator 17 is disposed in front of a space sandwiched between the main frame 3 and the engine 13.

The rear wheel 11 is interlocked and connected to a power transmission device 14 by a chain winding means 19, and the rear wheel 11 is driven to travel via the power transmission device 14 and the chain winding means 19 by the operation of the engine 13. It has become.

An integral cover 20 is provided to cover the main frame 3 from above, and the integral cover 20 is detachably supported on the main frame 3 by front and rear bolts 21, 21. Further, a sheet 22 is integrally molded at the rear end of the integrated cover 20, and this sheet 22 is attached to the main frame 3 through the integrated cover 20.
The seat 22 is also supported by a pivot shaft 24 at the upper end of a support bar 23 projecting from the rear of the exhaust pipe 16.

In the above case, by loosening the front and rear bolts 21, 21, the front portion of the cover unit 20 can be rotated upward about the pivot shaft 24. In this way, it is possible to perform maintenance and inspection of each device provided on the upper surface of the main frame 3, which will be described later, without removing the cover unit 20 or the seat 22 from the vehicle body.

A footrest bracket 25 is protruded from each rear arm bracket 8, and this footrest bracket 25
A footrest 26 is provided corresponding to the rider's feet on the seat 22.

1 and 3, the crankcase 27 of the engine 13 has a crankcase body 28 which itself is integrally molded. The crankcase body 28 has a crank chamber 29 inside thereof, and is provided with an opening 30 that opens the crank chamber 29 toward the left side. Further, the crankcase 27 has a crankcase cover 31 that freely opens and closes the opening 30, and the crankcase cover 31 is removably screwed to the crankcase body 28 by a port 31a.

A crankshaft 33 whose shaft center extends in the vehicle width direction is housed in the crank chamber 29, and both ends of the crankshaft 33 are attached to left and right bearings 34 and 35 in the crankcase body 28 and the crankcase cover 31, respectively. Supported by In the above case, the entire crankshaft 33 including its web passes through the opening 30 into the crank chamber 29.
It is said that it can be inserted and removed. In addition, the crank case body 2
8 has a cylindrical shape with a bottom, is lightweight, and has sufficient rigidity.

A cylinder 36 is provided that projects forward from the crankcase 27, and the cylinder 36 is fixed to the crankcase 27 by bolts 37.

A piston 38 is fitted into the cylinder 36 so as to be slidable forward and backward, and the piston 38 is interlocked and connected to the crankshaft 33 by a connecting rod 39.

1 to 5, an intake port 41 is formed in the crankcase cover 31, and this intake port 4
1 is connected to an intake pipe 43 that extends obliquely toward the upper left side through a rotary valve 42. On the other hand, the intake chamber 15 has a branch pipe 44 extending downward at the rear thereof, and the lower end of the branch pipe 44 is connected to the intake pipe 43.
is connected to the top of the The intake pipe 43 is provided with a throttle valve 46, and as shown in FIG.
It is designed to be linked to the rotation operation of the right end side accelerator grip.

A fuel injection valve 48 is attached to the intake pipe 43, and its injection direction 49 is diagonally downward intersecting the axis of the intake pipe 43 and toward the vicinity of the intake port 41. In particular, in FIG. 2, a fuel pump 51 is provided that supplies fuel within the main frame 3 to the fuel injection valve 48.

The low recess valve 42 will be explained with reference to FIGS. 1 and 15 and FIGS. 3 to 7.

The valve case 53 of the rotary valve 42 is connected to the crankcase cover 31 and the crankcase cover 3.
1 and a valve cover 54 that covers the crankcase cover 31 from the outside, and the valve cover 54 is detachably screwed to the crankcase cover 31 with bolts 55. A thin disc-shaped space surrounded by the crankcase cover 31 and the valve cover 54 is a valve chamber 56, and a fan-shaped valve plate 57 is slidably fitted into the valve chamber 56. Furthermore, a communication hole 58 is formed in the valve cover 54 in correspondence with the intake port 41.

A relative angle variable means 59 is provided which connects the valve plate 57 to the left end of the crankshaft 33 and allows the relative angle between the two to be changed.

That is, a support cylinder 60 is rotatably supported on the left end of the crankshaft 33, and the valve plate 57 is externally fitted onto an elliptical projection 61 formed on the outer peripheral surface of the support cylinder 60. In other words, the valve plate 57 rotates together with the support cylinder 60 to repeatedly open and close the communication hole 58. In particular, as shown in Figure 7, 6
2 is a reinforcing plate, and this reinforcing plate 62 is attached to the valve plate 57 with rivets 63 to reinforce this valve plate 57. A sliding hole 65 is formed on the left end of the crankshaft 33 on its axis, and a sliding shaft 66 is fitted into the sliding hole 65 so as to be freely slidable in the axial direction.

A pair of engagement grooves 67 are provided on the inner circumferential surface of the support cylinder 60, facing each other in the radial direction and extending in the axial direction.
．． 67 is formed. Further, a pair of spiral elongated holes 68, 68 are formed in the left end portion of the crankshaft 33 corresponding to each of these engagement grooves 67, and these spiral elongated holes 68 are arranged around the axis of the crankshaft 33 and are arranged in the same manner as each other. It draws a gentle spiral in the direction. Furthermore, a pair of spherical concave surfaces 69 and 69 are formed on the outer peripheral surface of the sliding shaft 66 in correspondence with each of the spiral elongated holes 68. A sphere 70 is slidably fitted into each concave surface 69, and each sphere 7o is fitted into the engagement groove 67 and the spiral elongated hole 68 so as to be movable along the longitudinal direction thereof.

When the sliding shaft 66 is slid in the axial direction, the sliding shaft 66 and the support cylinder 60 rotate together through the sphere 70 with their relative angles unchanged.
On the other hand, as the sphere 70 moves through the spiral elongated hole 68, the support cylinder 60 and the crankshaft 33 rotate together while their relative angles change.

In particular, in FIGS. 1, 3, and 6, there is a disk at one end of the sliding shaft 66 that is freely rotatable around its axis but moves along with the sliding shaft 66 in the axial direction. An engagement circumferential groove 71 is formed on the outer circumferential surface of the disk.

On the other hand, a pivot shaft 72 is rotatably supported on the valve cover 54 about its axis, and a pivot arm 73 is attached to the pivot shaft 72. An engagement pin 7 that slidably engages with the engagement circumferential groove 71
4 is installed.

The pivot shaft 72 is operatively connected to a servo motor 76 housed within the cover unit 20 via a wire winding means 75. An electronic control device 77 is provided to control the servo motor 76, and the electronic control device 77 controls the servo motor 76 by inputting external detection signals such as the rotational speed of the crankshaft 33.

That is, the wire winding means 75 and the servo motor 76 constitute a driving means for operating the relative angle variable means 59,
The relative angle variable means 59 can be operated from outside the crankcase 27 by this driving means.

To explain the above control in detail with reference to FIGS. 3 and 7, when the engine 13 is running at low speed, the sliding shaft 66 is inserted into the sliding hole 65 as shown by the solid line in FIG. The relative angle between the valve plate 33 and the valve plate 57 is as shown by the solid line in FIG. Next, when the rotational speed of the engine 13 begins to increase, the servo motor 76 is operated via the electronic control device 77, and the operation of the servo motor 76 is controlled by the wire winding means 75. It is transmitted to the rotating arm 73 via the pivot shaft 72. Then, as shown by the imaginary line in FIG. 3, the rotating arm 73 rotates around the pivot shaft 72 together with the engagement pin 74, and the sliding shaft 66 is pulled out from the sliding hole 65.

Then, the sphere 70 moves into the spiral elongated hole 6 along with the sliding shaft 66.
8 by moving the crankshaft 3 in its longitudinal direction.
3 changes, and the valve plate 57 rotates in the same direction as the rotational direction R of the crankshaft 33 as shown by the imaginary line in FIG. It looks like this. As a result, the opening timing of the intake port 41 is advanced, and the performance of the engine 13 is improved.

In the above case, the opening timing of the intake port 41 may be delayed as the rotational speed of the engine 13 increases.

In FIG. 1 and FIG. 2, an exhaust valve means 78 is provided to vary the exhaust timing at the exhaust port of the cylinder 36, and this exhaust valve means 78 is housed in the cover body 20 via a wire winding means 79. The servo motor 80 is connected to the servo motor 80. This servo motor 8
0 is also controlled by the electronic control device 77.

When the intake port 41 is opened by the operation of the crankshaft 33, the piston 38, the rotary valve 42, etc., the air-fuel mixture is sucked into the crankcase 27, and then this air-fuel mixture is fed into the cylinder 36. The exhaust gas after combustion is discharged through the exhaust pipe 16, and the engine 13 is operated. Incidentally, since such an action is the same as that of a conventional two-stroke engine, a detailed explanation thereof will be omitted.

The power transmission device 14 will be explained with reference to FIGS. 1 and 3.

The mission case 82 of the power transmission device 14 has a mission case body 83 that is integrally formed at the rear of the crankcase body 28.
On the right side of 3, there is an opening 8 that opens the inside to the right side.
4 is formed. In addition, the above mission case 82
has a mission case cover 85 which closes the opening 84 in a freely openable and closable manner. A transmission shaft 87 and an output shaft 88 are supported by the transmission case 82 parallel to and behind the crankshaft 33, and a dry multi-disc clutch 89 is attached to the right end of the transmission shaft 87. .

A reducing gear 91 is attached to the right end of the crankshaft 33, and an increasing reducing gear 92 that meshes with the reducing gear 91 is attached to the drive side of the clutch 89. Further, the driven side of the clutch 89 is attached to the speed change shaft 87. The speed change shaft 87 and the output shaft 88 are interlocked with each other by a variable speed gear mechanism 93, and this gear mechanism 93 meshes with a gear group 94 provided on the speed change shaft 87. A gear group 95 is provided on the output shaft 88. The output shaft 88 drives the rear wheel 11 via the chain winding means 19 as described above.

In FIG. 1, a speed change operation mechanism 97 is provided for operating the gear mechanism 93 to change speed.

This speed change operation mechanism 97 has a change lever shaft 98 supported by the transmission case 82, and this change lever shaft 98 is supported by the transmission case 82.
The shaft 98 is connected to a foot-operated change lever (not shown) via an interlocking arm 99 and an interlocking link (not shown). Also, a cam ft1l is attached to the same mission case 82.
oo is supported, and two bent shafts 102 are provided along this cam cylinder 100.
The three shift forks are respectively attached to the fork shaft 1 above.
02 is slidably supported in the axial direction.

Then, by stepping on the change lever, the cam cylinder 100 is moved through the interlocking arm 99, the change lever shaft 98, etc.
rotates in a predetermined direction, and in conjunction with this rotation, the shift fork 103 operates, which changes the gear mechanism 93 to a desired meshing state, that is, a desired shift state can be obtained. There is.

As shown in FIGS. 4 and 5, the crankcase 27
A cooling water passage 106 is formed in the cylinder 36, and this cooling water passage 106 is also formed in the cylinder 36.

In FIGS. 1 and 2, a water pump 107 is provided to feed cooling water into each of the cooling waterways 106. This water pump 107 has a pump case 108 attached to the left side of the mission case 82.

Then, by the operation of the water pump 107, the cooling water 1
14 is fed into each of the cooling water channels 106, and then this cooling water 114 is sent to the discharge pipe 11 as shown in FIG.
The cooling water 114 is discharged toward the radiator 17 through the radiator 17 and cooled by the radiator 17.
16 and is returned to the water pump 107 again.

In FIGS. 1 and 2, the rear end of the transmission case 82 is supported by the rear arm bracket 8 with a bolt 122 via a buffer material 121.

In FIGS. 1, 2, and 8, a balancer 124 is supported at the front upper part of the mission case 82, and the balancer 124 is operatively connected to the crankshaft 33 by a gear set 125. The right end of the balancer 124 drives the fuel pump 51 through a worm gear set 127 and an interlocking shaft 128. Note that the fuel pump 51 may be driven by the balancer 124 by wire winding means instead of the worm gear set 127 and the interlocking shaft 128.

Further, the upper part of the crankcase 27 above the upper two balancers 124 is supported by the main frame 3 by a port 131 via a cushioning material 130.

Note that although the above is based on the illustrated example, the crank case body 28
may be divided into two parts, such as vertically, horizontally, etc.

(Effects of the Invention) According to the present invention, both inner surfaces facing each other in the valve chamber function as guide surfaces when the valve plate rotates, and one of the inner surfaces is formed by the crankcase cover, and the other inner surface is formed by the crankcase cover. is formed by the valve cover.

In other words, since each inner surface of the valve chamber is formed by the surface of one member, accuracy is improved compared to conventional methods in which the crankcase side of both inner surfaces of the valve chamber was formed across two members. The above inconvenience is unlikely to occur. Therefore, the accuracy of the low revalve can be improved.

(Margin below)

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, in which Fig. 1 is a partially enlarged view of Fig. 2, Fig. 2 is an overall left side view of the motorcycle, and Fig. 3 is a sectional view taken along the line II-III of Fig. 1. , Figure 4 is the same as above.
IV-IV line arrow view in the figure, Figure 5 is V- in Figure 1 of the same figure.
6 is a partial sectional view of FIG. 1, FIG. 7 is a cross-sectional view of FIG.
■It is a sectional view taken along the line. 13--engine, 27--28 crankcase main chamber, 30--opening, 31 bar, 33 crankshaft, 42--rotary valve case, 54--valve cover chamber, 57--valve plate. Crankcase, 29...Crank/crankcase force 41...Intake port 53...Valve 56...Valve ゛゛゛゛゛Fig.

Claims (1)

[Claims] 1. A crankshaft is housed in a crank chamber in a crankcase body, an opening is formed in the side wall of the crankcase body at one end in the axial direction of the crankshaft, and the crankshaft is inserted into and removed from the crankcase through this opening. possible,
A crankcase cover is provided that allows the opening to be opened and closed, a crankshaft is rotatably supported by the crankcase body and the crankcase cover, an intake port is formed in the crankcase cover, and the crankcase cover is provided with an intake port. A valve cover is provided to cover the outer surface of the crankcase cover, a valve chamber is formed in the space between the crankcase cover and the valve cover, and the valve plate is housed in this valve chamber so as to be able to slide freely on the inner surface of the valve chamber. A two-stroke engine in which the valve plate is attached to the crankshaft so that the valve plate, which rotates with the crankshaft, repeatedly opens and closes the intake port.