JP2003020953A - Internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase a thermal efficiency by reducing the size of an internal combustion engine in the axial direction of a cylinder and increasing the degree of constant volume of the air-fuel mixture of the internal combustion engine during combustion. SOLUTION: A piston 16 slidably fitted to a cylinder 14 is connected, through a first connecting rod 19, to an auxiliary piston 17 slidably fitted to an auxiliary cylinder 15 on the same axis as the cylinder 14. An intermediate pin 18 fitted into the auxiliary piston 17 is connected to right and left crankshaft halves 24 and 28 through two second connecting rods 30 and 32. The right and left crankshaft halves 24 and 28 are disposed on the radial outside of the cylinder 14 in the sliding range of the piston 16 on the cylinder 14. Thus the increased amount of volume of a combustion chamber 42 relative to the increased amount of a crank angle on the piston 16 top dead center basis can be suppressed, and the thermal efficiency can be increased by increasing the degree of constant volume of the air-fuel mixture during combustion.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an internal combustion engine in which a piston slidably fitted in a cylinder is connected to a crankshaft via a connecting rod.

[0002]

2. Description of the Related Art FIG. 7 schematically shows a conventional general 4-cycle single cylinder internal combustion engine.

This internal combustion engine E includes a cylinder 01, a piston 02 slidably fitted in the cylinder 01, a cylinder head 03 connected to the cylinder 01, and a cylinder 0.
1, a combustion chamber 04 formed on the lower surface of the cylinder head 03, a crankshaft 05, and a connecting rod 06 that connects the piston 02 to the crankshaft 05.
With. And the piston 02 is the cylinder head 03
And the crankshaft 05.

FIG. 7A shows a state in which the piston 02 is at the top dead center, and the crank angle θ at this time is 0 °. FIG. 7C shows a state in which the piston 02 is at the bottom dead center, and the crank angle θ at this time is 180 °.
FIG. 7B shows a state in which the piston 02 is located at the midpoint between the top dead center and the bottom dead center, and the crank angle θ at this time is 9
The angle θa does not become 0 °, but becomes smaller than 90 °. The reason is that the connecting rod 06 is located on the axis L1 of the cylinder 01 at the top dead center and the bottom dead center, whereas the connecting rod 06 is inclined by the angle φ with respect to the axis L1 of the cylinder 01 at the midpoint. Is.

FIG. 6 shows a crank angle θ based on the top dead center of the internal combustion engine E and a piston 02 based on the top dead center.
The relationship with the displacement x of is indicated by the chain line. Piston 0 here
The stroke between the top dead center and the bottom dead center of 2 is 2R (R is the crank radius). As described with reference to FIG. 7B, when the piston 02 is at the center midpoint between the top dead center and the bottom dead center (the displacement x of the piston 02 is the point R), the crank angle θ is smaller than 90 °. The angle is θa. On the other hand, a sine curve shown by a solid line (x = Rsin (θ−90 °) + R)
Then, when the piston 02 is at the midpoint between the top dead center and the bottom dead center, the crank angle θ is 90 °.

As described above, in the conventional internal combustion engine E, the line indicating the relationship between the displacement x of the piston 02 and the crank angle θ (see the chain line) is located above the sine curve indicated by the solid line. . This means that when the piston 02 descends from the top dead center at the beginning of the expansion stroke,
This means that the increase amount of the displacement x of the piston 02 with respect to the increase amount of the crank angle θ is larger than the sine curve characteristic.

[0007]

By the way, in the conventional internal combustion engine E shown in FIG. 7, since the crankshaft 05 is arranged below the cylinder 01 in the direction of the axis L1, the size of the engine E is increased in the direction of the axis L1. In addition to this, there was a problem that the mass was dispersed in the direction of the axis L1.

Further, in order to improve the thermal efficiency of the internal combustion engine E, it is desirable to increase the equal volume of the air-fuel mixture during combustion. That is,
When the combustion of the air-fuel mixture starts near the top dead center of the piston 02 and the piston 02 descends, the volume of the combustion chamber 04 above the piston 02 increases, but the combustion chamber 04 with respect to the increase amount of the crank angle θ at that time. The smaller the increase in volume, the higher the isovolume and the higher the thermal efficiency. However, in the conventional internal combustion engine E shown in FIG. 7, the amount of increase in the volume of the combustion chamber 04 with respect to the amount of increase in the crank angle θ from the top dead center becomes large and the isovolume decreases, so the thermal efficiency of the internal combustion engine E is reduced. It was disadvantageous in raising it.

The present invention has been made in view of the above circumstances, and reduces the axial dimension of the cylinder of the internal combustion engine, and also increases the isochoricity of the air-fuel mixture during combustion to improve thermal efficiency. The purpose is to

[0010]

In order to achieve the above object, according to the invention described in claim 1, a piston slidably fitted in a cylinder is connected to a crankshaft through a connecting rod. In the internal combustion engine, there is proposed an internal combustion engine characterized in that a crankshaft is arranged radially outside a piston sliding range of a cylinder.

According to the above construction, since the crankshaft is arranged radially outside the piston sliding range of the cylinder, the conventional internal combustion engine having the crankshaft on the axis of the cylinder but outside the piston sliding range can be used. In comparison, the axial dimension of the cylinder of the internal combustion engine can be reduced and the mass can be concentrated.

According to the invention described in claim 2,
In addition to the structure of claim 1, the connecting rod comprises a first connecting rod whose one end is connected to the piston, and a second connecting rod whose one end is connected to the crankshaft, and the other end of the first connecting rod and the second connecting rod. An internal combustion engine is proposed in which the other ends of the second connecting rods are connected to each other via an intermediate pin that moves in the axial direction of the cylinder.

According to the above construction, the connecting rod is divided into a first connecting rod having one end connected to the piston side and a second connecting rod having one end connected to the crankshaft side, and the other ends of both connecting rods are connected to the cylinder. Since they are connected to each other via an intermediate pin that moves in the axial direction, the top dead center of the piston is used as a reference compared to the conventional internal combustion engine in which the crankshaft is provided outside the piston sliding range on the cylinder axis. The amount of increase in the volume of the combustion chamber with respect to the amount of increase in the crank angle can be suppressed to a small value, whereby the equal volume at the time of combustion of the air-fuel mixture can be increased and the thermal efficiency can be increased.

According to the invention described in claim 3,
In addition to the structure according to claim 2, the crankshaft is composed of a pair of crankshaft halves divided into two with a cylinder in between, and each crankshaft half is connected to both ends of the intermediate pin through second connecting rods. An internal combustion engine characterized by the above is proposed.

According to the above construction, since a pair of crankshaft halves divided into two with the cylinder in between are connected to both ends of the intermediate pin via the second connecting rods respectively, the crankshaft does not interfere with the cylinder. While avoiding it, it is possible to avoid applying an unbalanced load on the piston and the first and second connecting rods and prevent the occurrence of abnormal wear.

According to the invention described in claim 4,
In addition to the configuration according to any one of claims 1 to 3, there is proposed an internal combustion engine characterized in that a balancer weight provided on a balancer shaft driven by a crankshaft is arranged around a cylinder.

According to the above construction, the balancer weight provided on the balancer shaft that rotates in conjunction with the crankshaft is arranged around the cylinder. Therefore, the mass of the balancer weight is concentrated around the cylinder to enhance the vibration reducing effect. be able to.

Incidentally, the first connecting rod 1 of the embodiment.
The ninth and second connecting rods 30 and 32 correspond to the connecting rod of the present invention, and the left and right crankshaft halves 24 and 28 of the embodiment correspond to the crankshaft of the present invention.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below based on the embodiments of the present invention shown in the accompanying drawings.

1 to 6 show an embodiment of the present invention. FIG. 1 is a horizontal sectional view of an internal combustion engine for a motorcycle, and FIG.
2 is a sectional view taken along the line 2-2 of FIG. 1, FIG. 3 is a sectional view taken along the line 3-3 of FIG. 1, FIG. 4 is a sectional view taken along the line 4-4 of FIG. 2, and FIG. 5 is an explanatory view of the operation of the internal combustion engine of the present invention. 6 is a graph showing the relationship between the crank angle θ and the piston displacement x.

As shown in FIGS. 1 to 4, a four-cycle single-cylinder engine E for a motorcycle includes a left engine block 11 and a right engine block 12 which are divided into left and right parts. , 12, a cylinder block 13 is sandwiched. Cylinder block 1
3 includes a cylinder 14 and an auxiliary cylinder 15 arranged on a common axis L1, a piston 16 is slidably fitted in the cylinder 14, and an auxiliary piston 17 is slid in the auxiliary cylinder 15. Fit freely.

A substantially cylindrical body portion 1 of the auxiliary piston 17.
An annular support portion 17c is provided in the inside of 7a via a pair of arm portions 17b and 17b, and an intermediate pin 18 is provided between the two through holes 17d and 17d penetrating the main body portion 17a and the support portion 17c. Fit together. Both ends of the intermediate pin 18 are slidably fitted into a pair of slits 15a, 15a formed in the auxiliary cylinder 15 in the direction of the axis L1. The upper end of the first connecting rod 19 extending in the direction of the axis L1 is connected to the piston 16 via the piston pin 20, and the bifurcated lower end of the first connecting rod 19 is connected to the intermediate pin 18 inside the auxiliary piston 17. It Therefore, the piston 16 and the auxiliary piston 17 move integrally via the first connecting rod 19, and the first connecting rod 19 does not swing and always has the axis L1.
Located on top.

The left crank block half 24 is rotatably supported by the left engine block 11 and the left cover 21 connected to the left side surface of the left engine block via two ball bearings 22 and 23. Block 12
The right crankshaft half 28 is rotatably supported by the right cover 25 connected to the right side surface of the crankcase 2 through two ball bearings 26 and 27. Of course, the left crankshaft half 24 and the right crankshaft half 28 are located on the common axis L2 (see FIG. 1). The crank pin 29 provided on the left crankshaft half 24 and the left end of the intermediate pin 18 form a second connecting rod 30.
And the right end of the intermediate pin 18 and the crank pin 31 provided on the right crankshaft half 28 are also connected to each other.
It is connected by a connecting rod 32.

The cylinder head 41 connected to the left engine block 11 and the right engine block 12 has a combustion chamber 42 facing the top surface of the piston 16, an intake port 43 and an exhaust port 44 extending from the combustion chamber 42, and an intake port. An intake valve 45 that opens and closes 43, and an exhaust valve 46 that opens and closes the exhaust port 44 are provided. An intake pipe 48 having a fuel injection valve 47 is connected to the intake port 43, and a spark plug 49 is provided in the combustion chamber 42.

A camshaft 52 is supported in a valve operating chamber 51 surrounded by a cylinder head 41 and a head cover 50, and a driven sprocket 53 provided on the camshaft 52 is provided on the left crankshaft half 24. It is connected to the drive sprocket 54 via a timing chain 55. An intermediate portion of an intake rocker arm 57 is pivotally supported on an intake rocker arm shaft 56 provided on the cylinder head 41. One end of this intake rocker arm 57 abuts an intake cam 58 provided on a cam shaft 52, and the other end It contacts the stem end of the intake valve 45. An intermediate portion of an exhaust rocker arm 60 is pivotally supported on an exhaust rocker arm shaft 59 provided on the cylinder head 41. One end of the exhaust rocker arm 60 abuts on an exhaust cam 61 provided on a cam shaft 52 and the other end. Contacts the stem end of the exhaust valve 46.

Left engine block 11 and left cover 2
1, the balancer shaft 64 is supported via a pair of ball bearings 62 and 63, and the output shaft 67 is supported via ball bearings 65 and 66. The first gear 68 provided on the left crankshaft half 24 meshes with the second gear 69 provided on the balancer shaft 64, and the balancer shaft 6
The third gear 70 provided on the No. 4 meshes with the fourth gear 71 provided on the output shaft 67. A fan-shaped balancer weight 72 (see FIGS. 1 and 3) is provided at the inner end of the balancer shaft 64, that is, at a position adjacent to the cylinder 14. Since the first gear 68 and the second gear 69 have the same number of teeth, the balancer shaft 64 rotates at the same speed as the left crankshaft half 24. The output shaft 67 protruding from the left cover 21 is connected to, for example, an input shaft of a belt type continuously variable transmission.

Right engine block 12 and right cover 2
A balancer shaft 75 is supported on the bearing 5 through a pair of ball bearings 73 and 74, and a fifth gear 76 provided on the right crankshaft half body 28 meshes with a sixth gear 77 provided on the balancer shaft 75. A fan-shaped balancer weight 78 (see FIGS. 1 and 2) is provided at the inner end of the balancer shaft 75, that is, at a position adjacent to the cylinder 14. Since the fifth gear 76 and the sixth gear 77 have the same number of teeth, the balancer shaft 75 has the right crankshaft half 28.
Rotates at the same speed as. The right crankshaft half body 28 is provided with a speed detection gear 80 facing the pulsar 79 for detecting the number of rotations thereof.

As is apparent from FIG. 2, the engine E having the above-described structure has the mounting portion 12 provided on the right engine block 12.
a is supported by the vehicle body frame 83 via the engine hangers 81 and 82.

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

FIG. 5 schematically shows the internal combustion engine E of this embodiment, and corresponds to the conventional internal combustion engine shown in FIG.

The internal combustion engine E of this embodiment has a cylinder 14
And a piston 16 slidably fitted in the cylinder 14.
An auxiliary piston 17 slidably fitted to an auxiliary cylinder 15 coaxial with the cylinder 14, a first connecting rod 19 integrating the piston 16 and the auxiliary piston 17, and a cylinder head 41 facing the piston 16. The formed combustion chamber 42, the left and right crankshaft halves 24, 28, and the two second connecting rods 30, which connect the auxiliary piston 17 to the left and right crankshaft halves 24, 28 via the intermediate pin 18, And 32. And the left and right crankshaft halves 24, 28 are
The piston 16 is arranged radially outside.

FIG. 5A shows a state in which the piston 16 is at the top dead center, and the crank angle θ at this time is 0 °. FIG. 5C shows the piston 16 at the bottom dead center, and the crank angle θ at this time is 180 °.
FIG. 5B shows a state in which the piston 16 is located at the midpoint between the top dead center and the bottom dead center, and the crank angle θ at this time is 9 degrees.
The angle θb does not become 0 °, but becomes larger than 90 °. The reason is that, at the top dead center and the bottom dead center, the second connecting rods 30 and 32 are on the axis L1 of the cylinder 14, while at the midpoint, the second connecting rods 30 and 32 are on the axis L1 of the cylinder 14. This is because 32 is inclined by the angle φ. The first connecting rod 19
Only integrates the piston 16 and the auxiliary piston 17, and is always on the axis L1 and does not swing.

FIG. 6 shows the crank angle θ based on the top dead center of the internal combustion engine E and the piston 16 based on the top dead center.
The relationship with the displacement x of is indicated by a broken line. Piston 1 here
The stroke between the top dead center and the bottom dead center of 6 is 2R (R is the crank radius). As described with reference to FIG. 5B, when the piston 16 is at the middle point of the top dead center and the bottom dead center (the point where the displacement is R), the crank angle θ becomes an angle θb larger than 90 °. On the other hand, in the sine curve shown by the solid line, the crank angle θ is 90 ° when the piston 16 is at the midpoint between the top dead center and the bottom dead center.

As described above, in the internal combustion engine E of this embodiment,
The line showing the relationship of the displacement x of the piston 16 with respect to the crank angle θ (see the broken line) is located below the sine curve shown by the solid line, and x <Rsin (θ−90 °) + R
It can be seen that This means that when the piston descends from the top dead center in the expansion stroke, the increase amount of the displacement x of the piston 16 with respect to the increase amount of the crank angle θ is smaller than the sine curve characteristic.

As described above, in order to improve the thermal efficiency of the internal combustion engine E, it is desirable to increase the equal volume of the air-fuel mixture at the time of combustion, and for that purpose, when the piston 16 descends from the top dead center in the expansion stroke, The smaller the increase amount of the volume of the combustion chamber 42 with respect to the increase amount of the crank angle θ, the higher the equal volume is and the thermal efficiency is improved. The crank angle θ in the graph of FIG. 6 is 0.
As is clear from the expansion stroke portion from ° to 180 °, the displacement x of the piston 16 from the top dead center of the internal combustion engine E of the present embodiment shown by the broken line is the piston 02 of the conventional internal combustion engine E shown by the chain line. The displacement is smaller than the displacement x, so that the isovolume in the expansion stroke is increased and the thermal efficiency is improved.

The first and second connecting rods 1
In the expansion stroke in which the largest load is applied to 9, 30, 32, the auxiliary piston 17 moves in the direction away from the left and right crankshaft halves 24, 28, so that the second connecting rod 30, 32 does not have the conventional internal combustion engine E. The opposite tensile load is applied. Thus, the tensile load is applied to the second connecting rods 30 and 32, which is advantageous in strength as compared with the case where a compressive load is applied. As a result, the second connecting rods 30 and 32 can be made thinner and lighter. You can

Further, the left and right crankshaft halves 2 are radially outward of the sliding range of the piston 16 of the cylinder 14.
Since 4, 28 are arranged, compared with the conventional internal combustion engine E in which the crankshaft is arranged outside the piston sliding range,
The size of the cylinder 14 of the internal combustion engine E in the direction of the axis L1 can be reduced and the mass can be concentrated.

Even if the crankshaft is divided into the left and right crankshaft halves 24 and 28 and arranged on both sides of the cylinder 14, the two second connecting rods 30 and 32 arranged on both sides of the cylinder 14 are respectively provided. By connecting the left and right crankshaft halves 24, 28 with each other, avoiding the interference of the left and right crankshaft halves 24, 28 with the cylinder 14, the auxiliary piston 17, the piston 16 and the first and second connecting rods. 19,3
It is possible to prevent the occurrence of abnormal wear by preventing an unbalanced load from acting on 0 and 32.

The left and right crankshaft halves 24, 2
Since the balancer weights 72 and 78 that rotate in tandem with 8 are arranged around the cylinder 14, the mass of the balancer weights 72 and 78 can be concentrated around the cylinder 14 to enhance the vibration reducing effect.

Although the embodiments of the present invention have been described in detail above, the present invention can be variously modified without departing from the gist thereof.

For example, although the internal combustion engine E for a motorcycle is illustrated in the embodiment, the present invention can be applied to an internal combustion engine for any other purpose including multiple cylinders.

The engine E of the embodiment is provided with the left and right crankshaft halves 24, 28 on both sides of the cylinder 14, but is provided with only one of the left and right crankshaft halves 24, 28. Is also good.

Although the embodiment has exemplified the 4-cycle internal combustion engine E, the present invention can also be applied to an overhead valve type 2-cycle internal combustion engine.

[0044]

As described above, according to the invention described in claim 1, since the crankshaft is arranged radially outside the piston sliding range of the cylinder, the piston sliding range is on the cylinder axis. As compared with a conventional internal combustion engine having an external crankshaft, it is possible to reduce the axial dimension of the cylinder of the internal combustion engine and to concentrate the mass.

According to the invention described in claim 2,
The connecting rod is divided into a first connecting rod whose one end is connected to the piston side and a second connecting rod whose one end is connected to the crankshaft side, and the other ends of both connecting rods are connected via an intermediate pin that moves in the axial direction of the cylinder. Therefore, compared with the conventional internal combustion engine in which the crankshaft is provided outside the piston sliding range on the cylinder axis, the combustion chamber with respect to the increase in crank angle based on the top dead center of the piston The amount of increase in the volume can be suppressed to a small level, which makes it possible to increase the equal volume at the time of combustion of the air-fuel mixture and improve the thermal efficiency.

According to the invention described in claim 3,
Since a pair of crankshaft halves divided into two with the cylinder in between are connected to both ends of the intermediate pin via the second connecting rods, respectively, while avoiding the crankshaft from interfering with the cylinder, the piston and the first,
It is possible to prevent an unbalanced load from being applied to the second connecting rod and prevent abnormal wear from occurring.

According to the invention described in claim 4,
Since the balancer weight provided on the balancer shaft that rotates in conjunction with the crankshaft is arranged around the cylinder, the mass of the balancer weight can be concentrated around the cylinder to enhance the vibration reduction effect.

[Brief description of drawings]

FIG. 1 is a horizontal sectional view of an internal combustion engine for a motorcycle.

FIG. 2 is a sectional view taken along line 2-2 of FIG.

FIG. 3 is a sectional view taken along line 3-3 of FIG.

FIG. 4 is a sectional view taken along line 4-4 of FIG.

FIG. 5 is an explanatory diagram of the operation of the internal combustion engine of the present invention.

FIG. 6 is a graph showing the relationship between crank angle θ and piston displacement x.

FIG. 7 is an explanatory diagram of the operation of a conventional internal combustion engine.

[Explanation of symbols]

14 Cylinder 16 Piston 18 Intermediate Pin 19 1st Connecting Rod (Connecting Rod) 24 Left Crankshaft Half (Crankshaft) 28 Right Crankshaft Half (Crankshaft) 30 2nd Connecting Rod (Connecting Rod) 32 2nd Connecting Rod (Connecting rod) 64 Balancer shaft 72 Balancer weight 75 Balancer shaft 78 Balancer weight L1 Cylinder axis

Claims (4)

[Claims] 1. A piston (16) slidably fitted in a cylinder (14) is connected to a connecting rod (19, 3).
In the internal combustion engine that is connected to the crankshaft (24, 28) via the crankshaft (24, 28), the crankshaft (24, 28) is arranged outside the piston (16) sliding range of the cylinder (14) in the radial direction. Characterized internal combustion engine. 2. A connecting rod (19, 30, 3)
2) includes a first connecting rod (19) having one end connected to a piston (16), and a crankshaft (2).
4, 28) and a second connecting rod (30, 32) having one end connected to the other end of the first connecting rod (19) and the second connecting rod (3).
2. The internal combustion engine according to claim 1, characterized in that the other ends of (0, 32) are connected to each other via an intermediate pin (18) that moves in the direction of the axis (L1) of the cylinder (14). 3. The crankshaft (24, 28) is composed of a pair of crankshaft halves (24, 28) divided into two with a cylinder (14) sandwiched between them. Internal combustion engine according to claim 2, characterized in that it is connected to both ends of the intermediate pin (18) via second connecting rods (30, 32) respectively. 4. A balancer weight (72, 78) provided on a balancer shaft (64, 75) driven by a crankshaft (24, 28) is arranged around the cylinder (14). The internal combustion engine according to any one of claims 1 to 3.