Information
-
Patent Grant
-
6666183
-
Patent Number
6,666,183
-
Date Filed
Thursday, December 20, 200122 years ago
-
Date Issued
Tuesday, December 23, 200320 years ago
-
Inventors
-
Original Assignees
-
Examiners
Agents
- Birch, Stewart, Kolasch & Birch, LLP
-
CPC
-
US Classifications
Field of Search
US
- 123 195 R
- 123 1932
- 123 572
- 123 196 M
-
International Classifications
-
Abstract
To provide a V-type internal combustion engine capable of forming a breather path having a sufficiently large flow path area without enlarging a cylinder block. A 5-cylinder V-type internal combustion engine includes a breather apparatus, a crankshaft having three crankpins and a cylinder block formed with a front bank of three cylinders and a rear bank of two cylinders. Two crankpins disposed at both ends are connected with two connecting rods connected to pistons fitted to cylinder bores formed in the front and the rear banks. A crankpin disposed in the middle is connected only with a connecting rod connected to a piston fitted to a cylinder bore formed at a middle of the front bank and in the rear bank. A breather path of a breather apparatus is formed at a space portion between the two cylinder bores at a position opposed to the cylinder bore in the middle.
Description
BACKGROUND OF THE INVENTION
The present invention claims the benefit of Japanese Patent Application No. 2000-387707, filed Dec. 20, 2000, the entirety of which is hereby incorporated by reference.
1. Field of the Invention:
The present invention relates to a V-type internal combustion engine having a breather apparatus for recirculating blowby gas from a crankcase to an intake system. In particular, the present invention relates to the arrangement of a breather path constituting the breather apparatus.
2. Description of Background Art:
A V-type internal combustion engine having a breather apparatus for recirculating blowby gas to an intake system has been disclosed in Japanese Utility Model Publication No. 7209/1989. The breather apparatus is provided with a breather chamber provided at a bottom wall portion of a V-bank. A hole communicates the crankcase with the breather chamber. Furthermore, a communication path is formed at a cylinder wall of the cylinder block for communicating the breather chamber and a valve operating chamber, which is in communication with an intake manifold. Accordingly, blowby gas from the crankcase is recirculated to the intake manifold via the breather chamber, the communication path and the valve operating chamber.
In addition, according to the conventional breather apparatus, the communication path, which is also a breather path for flowing blowby gas, is formed in the cylinder wall on an inner side of the V-bank. Therefore, a flow path area of the communication path is limited. Accordingly, in order to ensure a sufficient flow path area, a plurality of communication paths are formed. Alternatively, in order to increase the flow path area of the communication path, it is necessary to significantly bulge the cylinder wall formed with the communication path toward the inner side of the V-bank. Therefore, a width of the bank formed with the communication path is increased in a direction orthogonal to a direction of arrangement of the cylinders, increasing the size of the cylinder block and restricting the arrangement of an intake apparatus in a space formed by the V-bank. Accordingly, the internal combustion engine is increased in size
SUMMARY OF THE INVENTION
The present invention has been carried out in view of such a situation and it is an object thereof to provide a V-type internal combustion engine capable of forming a breather path having a sufficiently large flow path area without enlarging the cylinder block.
According to a first aspect of the present invention, a V-type internal combustion engine includes a breather apparatus for recirculating blowby gas from a crankcase to an intake system. A crankshaft having three or more crankpins includes a first, a second and a third crankpin contiguous with each other in a direction of a rotational axis line thereof. A cylinder block is formed with a first and a second bank which form a V-like shape. The first and the third crankpins are respectively connected with a first and a third connecting rod, respectively connected to a first and a third piston, respectively fitted to a first and a third cylinder bore formed at the first bank. The second crankpin is disposed between the first and the third crankpins, is connected only with a second connecting rod, connected to a second piston, fitted to a second cylinder bore formed at the second bank. Furthermore, the breather apparatus includes a breather path formed at a space portion between the first and the third cylinder bores in the first bank.
According to the first aspect of the present invention, in the first bank, the space portion formed between the first and the third cylinder bores which constitutes a position opposed to the second cylinder bore of the second bank, is provided with a minimum width in the direction of the rotational axis line to a degree slightly smaller than a diameter of the second cylinder bore. Therefore, a flow path area of the breather path formed at the space portion can be sufficiently increased without increasing a width of the first bank in the direction of the rotational axis line and a width in a direction orthogonal to an assumed plane including the rotational axis line and a center line of the first cylinder bore or the third cylinder bore. Accordingly, a width of the cylinder block in the direction of the rotational axis line is not increased.
As a result, in the first bank, the breather path is formed at the space portion having a minimum width in the direction of the rotational axis line to the degree slightly smaller than the diameter of the second cylinder bore. Therefore, the breather path having a sufficiently large flow path area is provided without enlarging the first bank in the direction of the rotational axis line and in the direction orthogonal to the assumed plane. Accordingly, the cylinder block is not enlarged and the weight of the cylinder block is reduced. Furthermore, by increasing the flow path area of the breather path, a flow rate of blowby gas flowing through the breather path can be kept to a minimum. Therefore, separation of lubricating oil mist mixed in the blowby gas is expedited.
According to a second aspect of the present invention, there is provided a V-type internal combustion engine having an odd number of cylinders including a breather apparatus for recirculating blowby gas from a crankcase to an intake system. A crankshaft having a plurality of crankpins includes a first and a second crankpin contiguous with each other in a direction of a rotational axis line thereof. A cylinder block is formed with a first bank having an odd number of cylinders and a second bank having an even number of cylinders which form a V-like shape. The first crankpin is connected with a first and a second connecting rod, respectively connected to a first and a second piston, respectively fitted to a first and a second cylinder bore, respectively formed at the first and the second banks. The second crankpin is connected only with a third connecting rod, connected to a third piston, fitted to a third cylinder bore, formed in a bank having a larger number of the cylinders. The breather apparatus includes a breather path formed at a space portion contiguous with the same side at which the second crankpin is contiguous to the first crankpin relative to the first cylinder bore in the bank having a smaller number of the cylinders.
According to the second aspect of the present invention, in the bank having the smaller number of the cylinders, the space portion contiguous with the first cylinder bore or the second cylinder bore disposed at a position opposed to the third cylinder bore of the bank having the larger number of the cylinders, is provided with a width in the direction of the rotational axis line to a degree slightly smaller than a diameter of the third cylinder bore within a range such that the bank having the smaller number of cylinders does not project to the bank having the larger number of the cylinders in the direction of the rotational axis line. A flow path area of the breather path formed at the space portion can sufficiently be increased without increasing a width of the bank having the smaller number of the cylinders in a direction orthogonal to an assumed plane including the rotational axis line and a center line of the first cylinder bore or the second cylinder bore. Accordingly, a width of the cylinder block in the direction of the rotational axis line is not increased. Furthermore, the width in the direction of the rotational axis line is reduced by coupling the two connecting rods to the first crankpin.
As a result, in the bank having the smaller number of cylinders, the breather path is formed at the space portion having the width in the direction of the rotational axis line to a degree slightly smaller than the diameter of the third cylinder bore within the width in the direction of the rotational axis line of the bank having the larger number of cylinders. Therefore, a breather path having a sufficiently large flow path area is provided without enlarging the bank having the smaller number of cylinders in the direction orthogonal to the assumed plane including the rotational axis line and the center line of the cylinder bore. Accordingly, the advantage of the cylinder block being downsized by coupling the two connecting rods to the first crankpin is not deteriorated. Furthermore, by increasing the flow path area of the breather path, a flow rate of blowby gas flowing in the breather path can be kept to a minimum and therefore, the separating of lubricating oil mist mixed in the blowby gas can be expedited.
According to a third aspect of the present invention, there is provided the V-type internal combustion engine according to the second aspect of the present invention, wherein the crankshaft includes a third crankpin contiguous with a side opposed to the side at which the first crankpin is contiguous with the second crankpin. The third crankpin is connected with a fourth and a fifth connecting rod, respectively connected to a fourth and a fifth piston, respectively connected to a fourth and fifth cylinder bore, respectively formed at the first and the second banks. Furthermore, the space portion is present between the first and the fourth cylinder bores or between the second and the fifth cylinder bores.
According to the third aspect of the present invention, in the bank having the smaller number of cylinders, the space portion formed between the first and the fourth cylinder bores or between the second and the fifth cylinder bores, is provided with a minimum width in the direction of the rotational axis line to a degree slightly smaller than the diameter of the third cylinder bore and within the range of a width of the bank having the larger number of cylinders in the direction of the rotational axis line. Therefore, the flow path area of the breather path formed at the space portion can be sufficiently increased without increasing the width of the bank having the smaller number of cylinders in the direction of the rotational axis line and accordingly, without increasing the width of the cylinder block in the direction of the rotational axis line, the width in the direction of the rotational axis line being reduced by coupling the two connecting rods to each of the first and the third crankpins.
As a result, in addition to the advantages according to the second aspect of the present invention, a breather path having a sufficiently large flow path area is provided without enlarging the bank having the smaller number of cylinders in the direction of the rotational axis line and accordingly, without deteriorating the advantage of the cylinder block being downsized by coupling the two connecting rods to each of the first and the third crankpins. Furthermore, the weight of the cylinder block is reduced.
According to a fourth aspect of the present invention, in the V-type internal combustion engine according to any one of the first through third aspects of the present invention, the space portion is formed with a return path for lubricating oil and a partition wall is provided between the breather path and the return path such that the breather path and the return oil path are in parallel with each other in the direction of the rotational axis line.
According to the fourth aspect of the present invention, the space portion is provided with a minimum width in the direction of the rotational axis line to a degree slightly smaller than the diameter of the cylinder bore within a range such that the bank having the smaller number of cylinders does not project to the bank having the larger number of cylinders in the direction of the rotational axis line. In addition, the return path for lubricating oil having a sufficiently large flow path area can be formed in addition to the breather path having a sufficient blow path area without enlarging the cylinder block. Furthermore, the blowby gas and the lubricating oil can be prevented from mixing together by the partition wall, which partitions the breather path and the return oil path to be in parallel with each other in the direction of the rotational axis line.
As a result, the breather path and the return oil path are formed at the space portion having a minimum width in the direction of the rotational axis line to a degree slightly smaller than the diameter of the cylinder bore such that they do not project in the direction of the rotational axis line relative to the bank having the larger number of cylinders. Accordingly, the return oil path having a sufficient flow path area is provided along with the breather path without enlarging the cylinder block and the lubricating oil therefore returns smoothly. Furthermore, the blowby gas and the lubricating oil can be prevented from mixing together by the partition wall and an amount of the lubricating oil mist mixed into the blowby gas can be reduced.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus are not limitative of the present invention, and wherein:
FIG. 1
is a right side view of a V-type internal combustion engine to which the present invention is applied;
FIG. 2
is a sectional view substantially taken along a line II—II of FIG.
1
.
FIG. 3
is a plane view of a cylinder block of
FIG. 1
;
FIG. 4
is a right side view of the cylinder block and a lower crankcase of
FIG. 1
;
FIG. 5
is a sectional view of the cylinder block and the lower crankcase taken along a line V—V of
FIG. 3
;
FIG. 6
is a sectional view taken along a line VI—VI of
FIG. 5
;
FIG. 7
is a sectional view taken along a line VII—VII of
FIG. 4
;
FIG. 8
is a front view of the lower crankcase viewed in the direction of an arrow VIII of
FIG. 4
;
FIG. 9
is a sectional view taken along a line IX—IX of
FIG. 8
;
FIG. 10
is a sectional view taken along a line X—X of
FIG. 4
;
FIG. 11
is a bottom view of the cylinder block;
FIG. 12
is a view taken along a line XII—XII of
FIG. 3
;
FIG. 13
is an end face view of a rear bank of the cylinder block in a direction XIII of
FIG. 12
; and
FIG. 14
is a bottom view of a rear cylinder head.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
An explanation will now be provided for embodiments of the present invention with reference to the accompanying drawings.
Referring to
FIGS. 1 through 5
, a V-type internal combustion engine E to which the present invention is applied, is a V-type 5-cylinder 4-cycle internal combustion engine of a dual overhead cam (DOHC) type. The engine is also a water-cooled type, and which constitutes a power apparatus mounted to a motorcycle along with a transmission apparatus for transmitting power to rear wheels. As illustrated in
FIG. 1
, the internal combustion engine E is provided with, in a front and rear direction, a cylinder block
1
having a front bank
4
F and a rear bank
4
R forming a V-bank in a V-like shape having an angle of substantially 75°. A front cylinder head
2
F and a rear cylinder head
2
R are fastened to upper end faces
4
F
a
and
4
R
a
of the cylinder block
1
at the respective banks
4
F and
4
R. A front head cover
3
F and a rear head cover
3
R are respectively fastened to the two cylinder heads
2
F and
2
R. Furthermore, a lower portion of the cylinder block
1
is formed with an upper crankcase
5
and an upper portion thereof is formed with the two banks
4
F and
4
R, respectively. Furthermore, a lower end face
5
a
of the upper crankcase
5
is matched with an upper end face
6
a
of a lower crankcase
6
to thereby fasten the cylinder block
1
and the lower crankcase
6
. Furthermore, a crankshaft
7
is transversely arranged in a left and right direction of a vehicle body, and is rotatably supported by the crankcase constituted by the upper crankcase
5
and the lower crankcase
6
in a state in which a rotational axis line L thereof is disposed on a match face of the lower end face
5
a
of the upper crankcase
5
and the upper end face
6
a
of the lower crankcase
6
. Furthermore, in the specification, the terms “front, rear, left, right” signify “front, rear, left, right” with respect to the vehicle body.
Furthermore, with reference to
FIG. 5
, a front portion of the upper crankcase
5
and a front portion of the lower crankcase
6
forms the crankcase
8
containing the crankshaft
7
. Furthermore, a rear portion of the upper crankcase
5
and a rear portion of the lower crankcase
6
forms a transmission chamber
9
containing a wet type multi-plate friction clutch (not illustrated) and a gear transmission M of an always in-mesh type constituting a transmission apparatus. The lower end face
6
b
of the lower crankcase
6
is matched with an upper end face
10
a
of an oil pan
10
in oil tight relationship to thereby fasten the oil pan
10
.
Furthermore, the crankcase
8
and the transmission chamber
9
are separated by a bearing portion D
1
constituting a left side wall and a bearing portion D
4
constituting a right side wall (refer to
FIG. 2
) constituting two side walls of the cylinder block
1
and the lower crankcase
6
. The crankcase
8
and the transmission chamber
9
are separated by a partition wall comprising an upper partition wall A
1
formed at the cylinder block
1
and a lower partition wall A
2
formed at the lower crankcase
6
to thereby constitute chambers independent from each other. Accordingly, the crankcase
8
is hermetically closed.
Also with reference to
FIG. 2
, the front bank
4
F is provided with three cylinders C
1
, C
3
and C
5
aligned and integrally coupled in the direction of the rotational axis line L of the crankshaft
7
. Furthermore, center lines N
1
, N
3
and N
5
of the cylinder bores B
1
, B
3
and B
5
formed at the respective cylinders C
1
, C
3
and C
5
, are directed from the rotational axis line L in skewed front upper directions and the respective cylinders C
1
, C
3
and C
5
are inclined forwardly. Furthermore, the rear bank
4
R is provided with two cylinders C
2
and C
4
aligned and integrally coupled along the direction of the rotational axis line L. Center lines N
2
and N
4
of cylinder bores B
2
and B
4
formed at the respective cylinders C
2
and C
4
are directed from the rotational axis line L in skewed rear upper directions and the respective cylinders C
2
and C
4
are inclined rearwardly. Pistons P
1
through P
5
are slidably fitted in the cylinder bores B
1
through B
5
of the respective cylinders C
1
through C
5
. The pistons P
1
through P
5
are reciprocated by combustion pressure from combustion chambers formed between the respective pistons P
1
through P
5
and the cylinder heads
2
F and
2
R. The pistons P
1
through P
5
rotate the crankshaft
7
via connecting rods R
1
through R
5
connecting the respective pistons P
1
through P
5
and the crankshaft
7
.
Specifically, the crankshaft
7
is supported by the cylinder block
1
and the lower crankcase
6
by four bearing portions D
1
through D
4
respectively formed in the direction of the rotational axis line L at predetermined intervals at journals J
1
through J
4
via main bearings
11
. Furthermore, the crankcase
8
is partitioned into three chambers in the direction of the rotational axis line L with the two bearing portions D
1
and D
4
being located at the ends and the two bearing portions D
2
and D
3
being disposed in the middle.
In the crankshaft
7
, a crankpin K
1
between the bearing portion D
1
and the bearing portion D
2
, is connected with both of the connecting rods R
1
and R
2
connected to piston pins S
1
and S
2
of the two pistons P
1
and P
2
. A crankpin K
2
disposed between the bearing portion D
2
and the bearing portion D
3
and contiguous with the crankpin K
1
, is connected only with the connecting rod R
3
connected to a piston pin S
3
of the piston P
3
. Furthermore, a crankpin K
3
disposed between the bearing portion D
3
and the bearing portion D
4
and contiguous with the crankpin K
2
, is connected with both of the connecting rods R
4
and R
5
connected to a fourth and a fifth piston pin S
4
and S
5
of the two pistons P
4
and P
5
.
Referring to
FIG. 1
, the respective cylinder heads
2
F and
2
R are formed with an intake port
12
having a pair of inlet ports opened toward the combustion chamber and an exhaust port
13
having a pair of outlet ports. The intake ports
12
and the exhaust ports
13
are provided with a pair of intake valves
14
respectively opening and closing the pair of inlet ports and a pair of exhaust valves
15
for opening and closing the pair of outlet ports. In addition, each of the cylinder heads
2
F and
2
R are provided with an ignition plug T facing inside of the respective combustion chamber, at the respective combustion chamber. Furthermore, in the front cylinder head
2
F, an intake cam shaft
16
and an exhaust cam shaft
17
are rotatably supported by four cam holders arranged at intervals in the direction of the rotational axis line L. In the rear cylinder head
2
R, the intake cam shaft
16
and the exhaust cam shaft
17
are rotatably supported by three cam holders arranged at intervals in the direction of the rotational axis line L. Furthermore, two sets of the two cam shafts
16
and
17
are respectively driven to rotate at a rotational number of ½ of that of the crankshaft
7
by power of the crankshaft
7
transmitted from an intermediate gear
19
in mesh with the drive gear
18
provided at a right end portion of the crankshaft
7
via a front side timing gear train
20
and a rear side timing gear train
21
. The cam shafts
16
and
17
drive the respective intake valves
14
and the respective exhaust valves
15
at predetermined timings.
Furthermore, an intake apparatus connected to the respective intake ports
12
, is arranged on the inner side of the V-bank. An exhaust pipe connected to the exhaust ports
13
of the cylinders C
1
, C
3
and C
5
of the front bank
4
F, is extended in the rear direction by passing through a recess formed at the right side of the lower portion of the left wall of the oil pan
10
.
Furthermore, as illustrated in
FIG. 2
, the drive gear
18
and the intermediate gears
19
disposed on the right side of the cylinder block
1
and the two cylinder heads
2
F and
2
R, are covered by a cover
22
attached to right side walls of the upper crankcase
5
and the lower crankcase
6
. Two timing gear trains
20
and
21
are arranged in a cavity Y formed at right end portions of the two banks
4
F and
4
R of the cylinder block
1
and the two cylinder heads
2
F and
2
R. Therefore, the drive gear
18
, the intermediate gears
19
and the two timing gear trains
20
and
21
are contained in a gear chamber
23
constituted by a space formed by the right side walls and the cover
22
and the cavity Y. The gear chamber
23
is in communication with the oil pan
10
via a cavity formed at the lower crankcase
6
formed therebelow (not illustrated). Furthermore, an alternator
24
is provided at a left end portion of the crankshaft
7
.
Referring to
FIG. 1
, the power of the crankshaft
7
is transmitted to the multi-plate friction clutch via a primary speed reducing mechanism comprising a primary drive gear
25
and a primary driven gear
26
and is transmitted further to the gear transmission M. A main shaft
27
and a counter shaft
28
of the gear transmission M are respectively provided with a main gear group and a counter gear group, not illustrated. When a shift drum
29
is rotated by a speed change operating mechanism, shift forks engaged with cam grooves of the shift drum
29
are moved in the left and right direction on a support shaft
30
. Gears of the main gear group and the gears of the counter gear group in correspondence with the speed change operation are brought in mesh with each other. The power of the crankshaft
7
is subjected to speed change and is transmitted from the main shaft
27
to the counter shaft
28
and power of the counter shaft
28
is transmitted to rear wheels via a secondary speed reducing mechanism having a chain (not illustrated).
Furthermore, the power of the crankshaft
7
is transmitted to a pump gear
32
provided at a drive shaft
33
of an oil pump unit U via an intermediate gear
31
b
in mesh with a pump drive gear
31
a
rotated integrally with the primary driven gear
26
rotatably supported by the main shaft
27
to drive the oil pump unit U. The left end of the drive shaft
33
is coupled with a rotating shaft provided with an impeller of a cooling water pump, not illustrated.
An explanation will now be given of a lubricating system for the power apparatus. An oil strainer
34
is arranged in the oil pan
10
. An oil pipe
35
extends from the oil strainer
34
in the upper direction and is connected to a fourth intake port of a feed pump
36
of the oil pump unit U. Referring to
FIGS. 5 and 6
, the oil pump unit U is provided with a first scavenge pump
37
, the feed pump
36
, a second scavenge pump
38
and a third scavenge pump
39
in the axial direction of the drive shaft
33
successively from the right. The pumps
36
through
39
are constituted by trochoid pumps. The oil pump unit U is provided with a first intake port
37
a
of the first scavenge pump
37
, a second intake port
38
a
of the second scavenge pump
38
, a third intake port
39
a
of the third scavenge pump
39
and a single first delivery port
40
communicating with the respective delivery ports (not illustrated) of the first through the third scavenge pumps
37
through
39
. Furthermore, the oil pump unit U is provided with a fourth input port
36
a
of the feed pump
36
and a relief port
36
b
provided with a relief valve and a second delivery port
36
c
. The first delivery port
40
is provided in the vicinity of the second scavenge pump
38
in the axial direction of the drive shaft
33
and is directed substantially toward the main shaft
27
of the gear transmission M.
Referring to
FIG. 5
, the lower crankcase
6
is provided with an inclined partition wall A
2
a
extending from a front portion of a lower end face
6
b
coupled with the oil pan
10
in a skewed rear upper direction and constituting an acute angle between the inclined partition wall A
2
a
and a flat wall portion
6
c
2
, described below, of a front wall
6
c
of the lower crankcase
6
. The oil pump unit U is attached to an attaching face formed on the side of the oil pan
10
of the inclined partition wall A
2
a
constituting a portion of the lower partition wall A
2
. In a state in which the oil pump unit U is attached to the attaching face, as illustrated in
FIG. 7
, the inclined partition wall A
2
a
is provided with a first, a second and a third intake port
41
,
42
and
43
, respectively connected to the first, the second and the third input ports
37
a
,
38
a
and
39
a
. Furthermore, lubricating oil which is supplied into the crankcase
8
, once lubricating necessary lubricating portions and flowing down to the bottom portion of the crankcase
8
, is sucked respectively from the first through the third intake ports
41
through
43
to the first through the third scavenge pumps
37
through
39
and is discharged from the first delivery port
40
into the transmission chamber
9
.
Furthermore, as illustrated in
FIGS. 8 and 9
, in the inclined partition wall A
2
a
, at a position slightly upward from the lower end face
6
b
, there an oil path G
1
is provided to the second delivery port
36
c
by coupling with an end face of the second delivery port
36
c
. The oil path G
1
is connected to an oil path G
2
constituting an introducing oil path G
4
, described below, for conducting the lubricating oil to an oil filter
44
for cleaning the lubricating oil by removing foreign matters in the lubricating oil by a filter element
44
a
. Referring to
FIGS. 5 and 8
, a cylindrical shaped oil filter
44
is attached to an attaching seat
45
formed at the front wall
6
c
of the lower crankcase
6
. Specifically, the front wall
6
c
is provided with a partially cylindrical curved wall portion
6
c
1
constituting a portion in a peripheral direction of a substantially cylindrical peripheral wall with the rotational axis line L as a center line. The flat wall portion
6
c
2
substantially in a flat plate shape continuous with a lower end portion
6
c
1
a
of the curved wall portion
6
c
1
is disposed substantially right below the rotational axis line L and extends in a vertical lower direction to reach a lower end face
6
b
. A portion of the lower end face
6
b
in correspondence with the flat wall portion
6
c
2
is matched to the upper end face
11
a
at the front wall
10
b
portion in the flat plate shape of the oil pan
10
.
The attaching seat
45
projects from front faces of the curved wall portion
6
c
1
and the flat wall portion
6
c
2
in a space formed by the curved wall portion
6
c
1
and the flat wall portion
6
c
2
. An attaching face
45
a
attached with the oil filter
44
, is disposed upward from the lower end face
6
b
, disposed rearward from a contact portion
6
c
3
of the front face in contact with an assumed plane H in contact with a frontmost portion of the lower end face
6
b
and a front face of the curved wall portion
6
c
1
. Furthermore, the attaching face
45
a
is formed at a position slightly projected forward from the assumed plane H and substantially along the assumed plane H. Also with reference to
FIG. 10
, inside of the attaching seat
45
an oil path G
3
is formed comprising a groove in a ring-like shape opened to the attaching face
45
a
and the oil path G
2
one end of which is connected to the oil path G
1
and other end of which is connected to a lower portion of the oil path G
3
from a tangential direction of the oil path G
3
. An introducing oil path G
4
is constituted by the oil path G
2
and the oil path G
3
. The lubricating oil delivered from the feed pump
36
flows into the oil filter
44
via the introducing oil path G
4
.
Furthermore, at a central portion of a circular ring of the oil path G
3
, a screw hole
46
is formed with female threads in a direction orthogonal to the attaching face
45
a
. The screw hole
46
is threaded with a cylindrical shaped threaded portion
44
b
for forming an oil path to an inside of the oil filter
44
. Furthermore, an introducing oil path G
5
is formed opened to a peripheral wall in the vicinity of a bottom portion of the screw hole
46
and extends substantially in parallel with the rotational axis line L and accordingly, the lower end portion
6
c
1
a
of the curved wall portion
6
c
1
and to the right side of the screw hole
46
in the vicinity of the lower end portion
6
c
1
a.
With reference to
FIGS. 4 and 10
, the introducing oil path G
5
is connected to an oil path G
6
formed at the front wall
6
c
and opened to the upper end face
6
a
at the right end portion of the lower crankcase
6
. The oil path G
6
is connected to one end of an oil path G
7
formed at the right end portion of the cylinder block
1
. The other end of the oil path G
7
is connected to a main gallery G
8
formed at a bottom wall portion
1
a
of the V-bank of the cylinder block
1
at the upper end face
6
a
. The main gallery G
8
extends from a right end portion of the bottom wall portion
1
a
substantially in parallel with the rotational axis line L, opens at a left end face of the cylinder block
1
(refer to FIG.
3
), as illustrated in
FIG. 2
, and is connected to an oil path G
9
formed at an alternator cover
37
fastened to a left end face of the crankshaft
7
. The oil path G
9
is connected to an oil path G
11
formed by utilizing a screw hole threaded with a bolt
48
of the crankshaft
7
via an oil path G
10
formed at an inside of the bolt
48
for fixing a rotor of the alternator
24
to the crankshaft
7
. Furthermore, the oil path G
11
is connected with one end of an in-shaft oil path G
12
formed at an inside of the crankshaft
7
. The other end of the in-shaft oil path G
12
is connected to an oil path G
13
formed by utilizing a screw hole threaded with a bolt
49
for fixing a ring for hampering movement of the drive gear
18
in the direction of the rotational axis line L at the right end portion of the crankshaft
7
. The oil path G
13
is connected to an oil path G
16
provided at the cover
22
via an oil path G
14
formed at inside of the bolt
49
. An oil path G
15
is formed at a cap
50
mounted to the cover
22
. The lubricating oil which has passed through the oil path G
16
is injected from a nozzle
51
provided at the other end of the oil path G
16
toward the intermediate gears
19
, the drive gear
18
and the two timing gear trains
20
and
21
.
Furthermore, the first through the third crankpins K
1
through K
3
are formed, in the diameter direction, with oil paths G
17
connected to the in-shaft oil path G
12
for supplying the lubricating oil to the connecting portions of the respective crankpins K
1
through K
3
connected with the connecting rods R
1
through R
5
. The journals J
2
and J
3
are formed, in the diameter direction, with oil paths G
18
connected to the in-shaft oil path G
12
for supplying the lubricating oil to the bearing portions D
2
and D
3
. Furthermore, the journals J
1
and J
4
are formed, in the diameter direction, with oil paths G
19
respectively connected to the oil path G
11
and the oil path G
13
for supplying the lubricating oil to the two bearing portions D
1
and D
4
.
Furthermore, referring to
FIGS. 3 and 4
, in the main gallery G
8
, at a portion thereof connected with the oil path G
7
, head oil paths G
20
and G
21
are formed extending from the connected portion to the cylinder heads
2
F and
2
R of the respective banks
4
R and
4
F in the cylinder block
1
, by way of the respective head oil paths G
20
and G
21
. The lubricating oil is supplied to a front valve operating apparatus VF constituted by the two cam shafts
16
and
17
. Lifters and the like are arranged at an inside of a front valve operating chamber
52
F formed by the front cylinder head
2
F and the front head cover
3
F. A rear valve operating chamber VR is constituted by the two cam shafts
16
and
17
. Lifters and the like are arranged at an inside of a rear valve operating chamber
52
R formed by the rear cylinder head
2
R and the rear head cover
3
R (refer to FIG.
1
). That is, the respective head oil paths G
20
and G
21
are connected to oil paths formed at cam holders fixed to the respective cylinder heads
2
F and
2
R and disposed at right ends thereof at upper end faces
4
F
a
and
4
R
a
. The respective valve operating apparatus VF and FR are lubricated by lubricating oil supplied from the cam holders to hollow portions of the two cam shafts
16
and
17
and supplied from oil holes provided at necessary portions of the two cam shafts
16
and
17
.
Furthermore, referring to
FIGS. 4 and 11
, at the main gallery G
8
, contiguous with the right side of the cylinder C
2
of the rear bank
4
R, an oil path G
22
is formed opened to the lower end face
5
a
of the cylinder block
1
(lower crankcase
5
). The oil path G
22
branches, by way of an oil path
23
comprising a groove formed at the lower end face
5
a
of the cylinder block
1
and an oil path G
24
comprising a groove formed at the upper end face
6
a
of the lower crankcase
6
a
, to pass an oil path G
25
and an oil path G
26
formed at the lower crankcase
6
. The lubricating oil is supplied to the sliding portions of the main shaft
27
and the support shaft
30
of the gear transmission M.
Furthermore, referring to
FIGS. 5 and 11
, along the main gallery G
8
, at an inner face of the bottom wall portion
1
a
of the cylinder block
1
, five mounting portions
53
are provided mounted with nozzles
54
(refer to
FIG. 5
) in correspondence with the respective cylinder bores B
1
through B
5
at portions including the center lines N
1
through N
5
of the respective cylinder bores B
1
through B
5
and intersected with assumed planes orthogonal to the rotational axis line L. By injecting the lubricating oil which has passed through oil paths G
27
provided at the respective mounting portions
53
and connected to the main gallery G
8
from the nozzles
54
, the lubricating oil is supplied to the connecting portions of the respective pistons S
1
through S
5
and the respective connecting rods R
1
through R
5
and sliding portions of the respective cylinders C
1
through C
5
and the respective pistons P
1
through P
5
.
An explanation will now be given of a return oil path of the lubricating oil and a breather apparatus.
First, with regard to the front bank
4
F, referring to
FIGS. 3 and 11
, at the front wall of the cylinder head
2
F, at a left side portion of the cylinder C
1
, that is, the left end portion of the front bank
4
F, between the two cylinders C
1
and C
3
and between the two cylinders C
3
and C
5
, a first, a second and a third return oil path
55
,
56
and
57
of the lubricating oil are formed, respectively having opening portions
55
a
,
56
a
and
57
a
at the upper end face
4
F
a
of the cylinder block
1
. Furthermore, oil paths connected to the respective opening portions
55
a
,
56
a
and
57
a
are formed to open to an inside of the front valve operating chamber
52
F. The lubricating oil which has finished lubricating the front valve operating apparatus VF is gathered at the lower portion of the cylinder block
1
by way of the first through the third return oil paths
55
through
57
formed at the front wall of the cylinder block
1
, passes through a return oil pipe
58
(refer to
FIG. 1
) connected thereto at the lower end face
5
a
of the cylinder block
1
and returns to the oil pan
10
by way of an oil path
59
(refer to
FIG. 7
) having an opening portion
59
a
(refer to
FIG. 8
) provided below the flat wall portion
6
c
2
of the front wall
6
c
of the lower crankcase
6
.
In addition, referring to
FIGS. 12 and 13
, in the rear bank
4
R, substantially in the front and rear direction, that is, in a direction orthogonal to an assumed plane including the rotational axis line L and dividing the V-bank in two, at a position opposed to the cylinder bore B
3
of the front bank
4
F, between the cylinder bore B
2
and the cylinder bore B
4
in the direction of the rotational axis line L, a space portion
60
is formed having a width in the direction of the rotational axis line L to a degree slightly smaller than the diameter of the cylinder bore B
3
and substantially equal to an interval in the direction of the rotational axis line L between a central point of the journal J
2
and a central point of the journal J
3
in the direction of the rotational axis line L. As a result, as illustrated in
FIG. 3
, the space portions
60
is within a range such that it does not project relative to the front bank
4
F in the direction of the rotational axis line L.
In the space portion
60
, a cavity
62
is formed having a partition wall
61
extending substantially in parallel with the direction of the rotational axis line L and continuous with an outer peripheral wall C
2
a
of the cylinder C
2
and an outer peripheral wall C
4
a
of the cylinder C
4
. The cavity
62
is formed between an inclined partition wall A
1
a
constituting a portion of the upper partition wall A
1
, extending from the bottom wall portion
1
a
in a skewed rear lower direction and reaching a rear end of a lower portion of the rear bank
4
R and an upper end face
4
R
a
of the rear bank
4
R, between the outer peripheral wall C
2
a
of the cylinder C
2
and the outer peripheral wall C
4
a
of the cylinder C
4
and between the inner side wall
4
R
b
of the V-bank of the rear bank
4
R and an outer side wall
4
R
c
of the V-bank extending in a skewed rear lower direction and continuous to an upper wall
5
C of the transmission chamber
9
. Furthermore, between a vertical partition wall A
1
b
extending from an end portion of the inclined partition wall A
1
a
on the side of the transmission chamber
9
in the vertical lower direction toward the lower end face
5
a
and constituting the upper partition wall A
1
and the outer side wall
4
R
c
of the V-bank, an opening portion
63
is formed for communicating the cavity
62
and the transmission chamber
9
. Furthermore, a width of the cavity
62
in the direction of the rotational axis line L is substantially equal to an interval between the bearing portion D
2
and the bearing portion D
3
in the rotating shaft direction. A width thereof in a direction orthogonal to an assumed plane including the rotational axis line L and the center line N
2
or the center line N
4
(hereinafter, referred to as “orthogonal” direction) is substantially equal to a width of the rear bank
4
R in the orthogonal direction at portions of the cylinders C
2
and C
4
.
Above the cavity
62
, a path
64
is formed interposing the partition wall
61
, extending to substantially a central portion of the upper end face
4
R
a
and the inclined partition wall A
1
a
in a direction of the center line N
2
or the center line N
4
. The path
64
has an opening portion
64
a
at the upper end face
4
R
a
on an inner side of the V-bank. A path
65
is formed having an opening portion
65
a
at the upper end face
4
R
a
and constituting the opening portion
63
at its rear portion on an outer side of the V-bank. The paths
64
and
65
are arranged in parallel with the direction of the rotational axis line L by the partition wall
61
. Furthermore, by a path
66
formed below the partition wall
61
and below the cavity
62
, the path
64
and the opening portion
63
are in communication with each other. Furthermore, a breather path
67
of the cylinder block
1
is constituted by the opening portion
63
, the path
66
and the path
64
. A oil return path
68
of the lubricating oil from the rear valve operating chamber
52
R in the cylinder
1
is constituted by the path
65
and the opening portion
63
.
Furthermore, at an inside of the partition wall
61
, a water path
61
a
is provided for communicating a cooling water jacket of the cylinder C
2
and a cooling water jacket of the cylinder C
4
. Furthermore, further, at an upper portion of the partition wall
61
, an eaves portion
61
b
is formed extending to the outer side of the V-bank and a projected edge portion
61
c
is formed constituting a front end portion of the eaves portion
61
b
and produced by projecting an edge portion of the opening portion
65
a
of the path
65
on the side of the partition wall
61
over the direction of the rotational axis line L in the lower direction. Furthermore, the opening portion
63
constituting a flow inlet of the breather path
67
and constituting a flow outlet of the return oil path
68
, is provided below the partition wall
61
and to a side more proximate to the outer side wall
4
R
c
of the V-bank than a side face
61
d
on the side of the return oil path
68
of the partition wall
61
and is disposed at a position at which a portion of the blowby gas flowing from the opening portion
63
impinges on the side face
61
d
and a flow elevating along the side face
61
d
is produced.
Furthermore, in the rear cylinder head
2
R, as illustrated in
FIGS. 12 and 14
, a space portion
70
is formed at a position in correspondence with the space portion
60
. A breather path
71
and a return oil path
72
of the lubricating oil are formed having opening portions
71
a
and
72
a
having sizes respectively matching precisely with the opening portions
64
a
and
65
a
of the path
64
and the path
65
and communicating with inside of the rear valve operating chamber
52
R. Furthermore, a partition wall
73
is formed having a lower end face matched with an upper end face of the partition wall
61
. At inside of the partition wall
73
, a water path
73
a
is formed for communicating a cooling water jacket formed by surrounding the combustion chamber of the cylinder C
2
at the rear cylinder head
2
R, the ignition plug T and a lower portion of a cylindrical portion
69
(refer to
FIG. 2
) containing an ignition coil and a cooling water jacket formed by surrounding the combustion chamber of the cylinder C
4
. The ignition plug T and a lower portion of a pipe contain an ignition coil.
Furthermore, as illustrated in
FIGS. 2 and 12
, at an upper portion of the rear head cover
3
R, above the breather paths
67
and
71
, a breather chamber
74
is provided having an inlet
74
a
opened to an inside of the rear valve operating chamber
52
R. A recirculating pipe (not illustrated) connected to a connection pipe
75
connected to the breather chamber
74
is connected to an intake path constituting an intake system of the internal combustion engine E.
Thereby, blowby gas in the crankcase
8
sucked by the first through the third scavenge pumps
37
through
39
along with the lubricating oil and discharged into the transmission chamber
9
, flows from the transmission chamber
9
into the breather chamber
74
by passing through the breather paths
67
and
71
, is recirculated from the breather chamber
74
to the intake path via the recirculating pipe and is supplied to the combustion chamber. Therefore, a breather apparatus is formed for recirculating the blowby gas from the crankcase
8
to the intake path by the first through the third intake ports
41
through
43
, the first through the third scavenge pumps
37
through
39
, the transmission chamber
9
, the breather paths
67
and
71
, the rear valve operating chamber
52
R, the breather chamber
74
, the connection tube
75
and the recirculating pipe.
An explanation will now be given of the operation and effect of the embodiment constituted as described above.
When the internal combustion engine E is operated and the oil pump unit U is operated, the lubricating oil sucked from the oil pan
10
to the feed pump
36
by passing through the oil strainer
34
, is delivered from the second delivery port
36
c
, flows into the oil filter
44
by way of the oil path G
1
and the introducing oil path G
4
, is removed of foreign matters or the like by the oil filter
44
and is supplied to the main gallery G
8
by passing through the introducing oil path G
5
, the oil path G
6
and the oil path G
7
.
The lubricating oil flowing from the main gallery G
8
into the in-shaft oil path G
12
via the oil paths G
9
, G
10
and G
11
, is supplied to the journals J
1
through J
4
and the crankpins K
1
through K
3
, lubricates the respective sliding portions, and is injected from the nozzles
51
, lubricates the mesh portion and the sliding portions of the drive gear
18
, the intermediate gears
19
and the two timing gear trains
20
and
21
. Furthermore, the lubricating oil is injected from the nozzles
54
and lubricates the sliding portions of the respective piston pins S
1
through S
5
and the sliding portions of the respective pistons P
1
through P
5
and the respective cylinders C
1
through C
5
. In addition, the lubricating oil flowing from the main gallery G
8
into the head oil paths G
20
and G
21
, lubricates the sliding portions of the valve operating apparatus VF and VR in the respective valve operating chambers
52
F and
52
R.
Furthermore, the lubricating oil which has been supplied to the crankcase
8
and has finished lubricating the lubricating portions of the sliding portions and the like described above, flows down to the bottom portion of the crankcase
8
formed between the front wall
6
c
and the inclined partition wall A
2
a
, and is sucked from the first through the third intake ports
41
through
43
to the first through the third scavenge pumps
37
through
39
. The lubricating oil delivered from the scavenge pumps
37
through
39
, is discharged from the first delivery port
40
into the transmission chamber
9
, lubricates the lubricating portions of the sliding portions of the multi-plate friction clutch, the gear transmission M and the like and thereafter returns to the oil pan
10
. In addition, the oil which has lubricated the drive gear
18
, the intermediate gears
19
and the two timing gear trains
20
and
21
, returns from the lower portion of the gear chamber
23
opened to the oil pan
10
to the oil pan
10
. The lubricating oil supplied to the front valve operating chamber
52
F, returns to the oil pan
10
via the return oil paths
55
through
57
and the return pipe
58
. The lubricating oil supplied to the rear valve operating chamber
52
R returns to the oil pan
10
via the return oil paths
72
and
68
and via the transmission chamber
9
. In this way, the lubricating oil supplied into the crankcase
8
is sucked by the first through the third scavenge pumps
37
through
39
. Therefore, power loss is not caused by scraping up the lubricating oil by the crankshaft
7
.
Furthermore, as described above, blowby gas in the crankcase
8
is sucked to the first through third scavenge pumps
37
through
39
along with the lubricating oil, is discharged into the transmission chamber
9
, is recirculated from the transmission chamber
9
to the intake path by way of the breather path
67
formed at the space portion
60
, the breather path
71
formed at the space portion
70
, the rear valve operating chamber
52
R, the breather chamber
74
and the recirculating pipe, is supplied to the combustion chamber and is combusted.
In the rear bank
4
R, the space portion
60
formed between the cylinder bore B
2
and the cylinder bore B
4
at the position opposed to the cylinder bore B
3
of the front bank
4
F, is provided with a minimum width in the direction of the rotational axis line L to a degree slightly smaller than the diameter of the cylinder bore B
3
within a range such that it does not project in the direction of the rotational axis line L relative to the front bank
4
F. Therefore, the breather path
67
is provided a sufficiently large flow path area without increasing the width in the direction of the rotational axis line L of the rear bank
4
R having a number of cylinders smaller than that of the front bank
4
F, and the width in the orthogonal direction. Accordingly, the width in the direction of the rotational axis line L of the cylinder block
1
is not increased, the advantage of the cylinder block
1
being downsized by reducing the width in the direction of the rotational axis line L by coupling the two connecting rods R
1
and R
2
and the two connecting rods R
4
and R
5
respectively to the two crankpins K
1
and K
3
is not deteriorated, and the weight of the cylinder block
1
is reduced. Furthermore, by increasing the flow path area of the breather path
67
, a flow rate of the blowby gas flowing in the breather path
67
is kept to a minimum and therefore, an effect of separating lubricating oil mist mixed in the blowby gas is expedited.
The space portion
60
is provided with a width in the direction of the rotational axis line L to a degree slightly smaller than the diameter of the cylinder bore B
3
within a range which does not project to the front bank
4
F in the direction of the rotational axis line L. Therefore, the return oil path
68
of the lubricating oil having a sufficiently large flow path area can be formed in addition to the breather path
67
having a sufficient flow path area without enlarging the cylinder block
1
. Furthermore, lubricating oil from the rear valve operating chamber
52
R returns smoothly, the blowby gas and the lubricating oil can be restrained from being mixed with each other by the partition wall
61
partitioning the two paths
64
and
65
in parallel with the direction of the rotational axis line L and an amount of the lubricating oil mist mixed into the blowby gas can be reduced.
By separating the crankcase
8
and the transmission chamber
9
by the partition wall comprising the upper partition wall A
1
and the lower partition wall A
2
, the breather path
67
constituted by the opening portion
63
, the path
66
and the path
64
is also separated from the crankcase
8
. Therefore, the lubricating oil scattered by rotating the crankshaft
7
does not directly intrude the breather path
67
and the lubricating oil mist is prevented from mixing with the blowby gas.
The partition wall
61
and the partition wall
73
are respectively formed with the water paths
61
a
and
73
a
of cooling water. Therefore, when warming up the internal combustion engine E, the breather paths
67
and
71
are warmed by cooling water from the cooling water jackets of the cylinder block
1
and the rear cylinder head
2
R as well as cooling water flowing in the water paths
61
a
and
73
a
of the partition walls
61
and
73
. Therefore, condensation of steam at the breather paths
67
and
71
and the breather chamber
74
is prevented and accordingly, water is prevented from mixing wtih the separated lubricating oil and a deterioration of the lubricating oil caused by mixing water can be avoided.
Furthermore, at the upper portion of the partition wall
61
, the eaves portion
61
b
extends to the outer side of the V-bank and the projected edge portion
61
c
constitutes the front end portion of the eaves portion
61
b
. Therefore, although a portion of the blowby gas flowed from the opening portion
63
reaches the rear valve operating chamber
52
R by passing through the return oil paths
68
and
72
, a portion thereof impinges on the side face
61
d
of the partition wall
61
on the side of the return oil path
68
and an elevating flow is produced along the side face
61
d
. Furthermore, the elevating blowby gas impinges on the lower face of the eaves portion
61
b
and the elevating flow is hampered and deflected to the lower side by the projected edge portion
61
c
. Therefore, the flow of the lubricating oil passing through the return oil path
68
is significantly restrained from being hampered by the elevating blowby gas and the lubricating oil flows down to the return oil path
68
smoothly.
Furthermore, the attaching face
45
a
of the attaching seat
45
formed at the front wall
6
c
of the lower crankcase
6
, is disposed above the lower end face
6
b
coupled with the oil pan
10
of the lower crankcase
6
and is disposed at a position comparatively higher than that in the case of attaching the oil filter
44
to the oil pan
10
or the case of arranging the oil filter
44
to ride over the lower crankcase
6
and the oil pan
10
. Furthermore, the oil filter
44
is formed forward from the assumed plane H and substantially along the assumed plane H and therefore, regardless of presence of the curved wall portion
6
c
1
being bulged forwardly, the attaching face
45
a
can easily be recognized from above. Therefore, attachment and detachment of the oil filter
44
while confirming the attaching face
45
a
are facilitated and the operability of maintenance of the oil filter
44
is promoted. Furthermore, by disposing the attaching face
45
a
rearward from the contact portion
6
c
3
in contact with the assumed plane H on the front side of the curved wall portion
6
c
1
bulged to the front side of the front wall
6
c
of the lower crankcase
6
, an amount of projection of the oil filter
44
to the front side is restrained. Therefore, the internal combustion engine E can be downsized and there is increased a degree of freedom of arranging an exhaust pipe connected to the exhaust port
13
, extended to the lower side by passing through the front side of the front bank
4
F, bent to the left side at the lower side and extended through the space formed to recess the lower portion of the left wall of the oil pan
10
to the right side in the lower direction.
Furthermore, the attaching seat
45
is provided by utilizing the space formed between the front face of the curved wall portion
6
c
1
and the front face of the flat wall portion
6
c
2
. Furthermore, the introducing oil path G
4
and the introducing oil path G
5
are formed at an inside thereof. Therefore, it is not necessary to project the front wall
6
c
of the lower crankcase
6
into the crankcase
8
for forming the oil paths G
4
and G
5
, the inner structure of the crankcase
8
can be simplified, the crankcase can be downsized and accordingly, the internal combustion engine E can be downsized. Furthermoremore, the introducing path G
5
formed at a position more remote in the direction orthogonal to the attaching face
45
a
from the attaching face
45
a
directed in the skewed lower direction than the introducing oil path G
4
, is formed at a vicinity of the lower end portion
6
c
1
a
constituting a comer portion formed by the curved wall portion
6
c
1
and the flat wall portion
6
c
2
. Therefore, the inside of the attaching seat
45
can effectively be utilized, an amount of projecting the attaching seat
45
to the front side is reduced and accordingly, an amount of projecting the oil filter
44
to the front side is reduced and the internal combustion engine E can further be downsized.
An explanation will now be given of a modified constitution with regard to an embodiment modifying a portion of the constitution of the above-described embodiment as follows.
Although according to the embodiment, the internal combustion engine E is provided with a hermetically closed crankcase
8
, the breather apparatus may communicate with the breather path
67
via a path communicating with the crankcase without hermetically closing the crankcase. In that case, air downstream from an air cleaner of the intake system is introduced into the front valve operating chamber communicating with the crankcase via the path. Furthermore, a PCV valve can be provided at the breather chamber or the output pipe.
Although according to the embodiment, the V-type internal combustion engine E is constituted by 5 cylinders, the internal combustion engine E may be a V-type internal combustion engine having an odd number of cylinders, for example, it may be an internal combustion engine of 3 cylinders or 7 cylinders. Furthermore, in the case of a 3-cylinder V-type internal combustion engine, the space portion of the cylinder block is formed at a position contiguous with a cylinder bore of a bank having an odd number of the cylinder comprising 1 cylinder and by a width in a rotational axis line direction which does not project in the rotational axis line direction of a crankshaft relative to a bank having an even number of cylinders comprising 2 cylinders constituting a bank having a larger number of cylinders.
Furthermore, although according to the above-described embodiment, the first and the third crankpins K
1
and K
3
are respectively connected with two of the connecting rods R
1
and R
2
and two of the connecting rods R
4
and R
5
, there may be constituted a V-type internal combustion engine of a style which connects a single connecting rod to a respective crankpin. Furthermore, there may be constituted a V-type internal combustion engine of a style in which crankpins connected with two connecting rods and crankpins connected with a single connecting rod are irregularly present in a rotational axis line direction of a crankshaft.
Furthermore, although the two space portions
60
and
70
are formed with the two paths
64
and
65
respectively divided by the two partition walls
61
and
73
, the breather path
71
and the return oil path
72
, there may be formed a single path having an opening portion of an area equal to or larger than an area combined with the areas of the opening portions
64
a
and
65
a
of the two paths
64
and
65
without providing the two partition walls
61
and
70
and the path may serve as the breather path and the return oil path. Furthermore, the breather path and the return oil path may be formed only by the partition wall
61
without providing the partition wall
73
.
The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.
Claims
- 1. A V-type internal combustion engine, comprising:a breather apparatus for recirculating blowby gas from a crankcase to an intake system; a crankshaft, said crankshaft including at least a first, a second and a third crankpin contiguous with each other in a direction of a rotational axis line of said crankshaft; a cylinder block, said cylinder block being formed with a first and a second bank forming a V-shape; said first crankpin and said third crankpin are respectively connected with a first and a third connecting rod respectively connected to a first and a third piston respectively fitted in a first and a third cylinder bore formed in the first bank; said second crankpin is disposed between said first crankpin and said third crankpin, and is connected only with a second connecting rod connected to a second piston fitted to a second cylinder bore formed in the second bank; and said breather apparatus includes a breather path formed in a space portion between the first and the third cylinder bores in the first bank.
- 2. The V-type internal combustion engine according to claim 1, wherein said space portion is formed with a return oil path for lubricating oil and a partition wall is provided between said breather path and the return oil path for partitioning such that the breather path and the return oil path are in parallel with each other in the direction of the rotational axis line.
- 3. The V-type internal combustion engine according to claim 2, wherein said partition wall includes a water path formed therein for communicating cooling water jackets of the cylinders adjacent the space portion.
- 4. A V-type internal combustion engine having an odd number of cylinders, comprising:a breather apparatus for recirculating blowby gas from a crankcase to an intake system; a crankshaft, said crankshaft having a first crankpin and a second crankpin contiguous with each other in a direction of a rotational axis line of said crankshaft; a cylinder block formed with a first bank having an odd number of cylinders and a second bank having an even number of cylinders forming a V-shape; said first crankpin is connected with a first and a second connecting rod respectively connected to a first and a second piston respectively fitted in a first and a second cylinder bore respectively formed in the first and the second banks; said second crankpin is connected only with a third connecting rod connected to a third piston fitted to a third cylinder bore formed in a bank of the first and the second banks having a larger number of cylinders; and said breather apparatus includes a breather path formed in a space portion in a bank of the first and the second banks having a smaller number of cylinders.
- 5. The V-type internal combustion engine according to claim 4, wherein said crankshaft includes a third crankpin contiguous with a side opposite to the side at which the first crankpin is contiguous to the second crankpin, said third crankpin being connected with a fourth and a fifth connecting rod respectively connected to a fourth and a fifth piston respectively connected to a fourth and fifth cylinder bore respectively formed at the first and the second banks, and said space portion is present between the first and the fourth cylinder bores or between the second and the fifth cylinder bores.
- 6. The V-type internal combustion engine according to claim 4, wherein said space portion is formed with a return oil path for lubricating oil and a partition wall is provided between said breather path and the return oil path for partitioning such that the breather path and the return oil path are in parallel with each other in the direction of the rotational axis line.
- 7. The V-type internal combustion engine according to claim 5, wherein said space portion is formed with a return oil path for lubricating oil and a partition wall is provided between said breather path and the return oil path for partitioning such that the breather path and the return oil path are in parallel with each other in the direction of the rotational axis line.
- 8. The V-type internal combustion engine according to claim 6, wherein said partition wall includes a water path formed therein for communicating cooling water jackets of the cylinders adjacent the space portion.
- 9. The V-type internal combustion engine according to claim 7, wherein said partition wall includes a water path formed therein for communicating cooling water jackets of the cylinders adjacent the space portion.
- 10. A breather apparatus for recirculating blowby gas from a crankcase to an intake system of a V-type internal combustion engine, said V-type internal combustion engine including a cylinder block formed with a first and a second bank forming a V-shape, said breather apparatus comprising a breather path formed in a space portion directly between first and third cylinder bores in the first bank.
- 11. The breather apparatus according to claim 10, wherein said space portion is formed with a return oil path for lubricating oil and a partition wall is provided between said breather path and the return oil path for partitioning such that the breather path and the return oil path are in parallel with each other in a direction of a rotational axis line of a crankshaft of the engine.
- 12. The breather apparatus according to claim 11, wherein said partition wall includes a water path formed therein for communicating cooling water jackets of the cylinders adjacent the space portion.
- 13. The breather apparatus according to claim 10, wherein said space is bounded by outer circumferences of the first and second cylinder boxes.
- 14. A breather apparatus for recirculating blowby gas from a crankcase to an intake system in a V-type internal combustion engine having an odd number of cylinders, the V-type internal combustion engine including a cylinder block formed with a first bank having an odd number of cylinders and a second bank having an even number of cylinders forming a V-shape, said breather apparatus comprising a breather path formed in a space portion directly between cylinders in a bank of the first and the second banks having a smaller number of cylinders.
- 15. The breather apparatus according to claim 14, wherein said space portion is formed with a return oil path for lubricating oil and a partition wall is provided between said breather path and the return oil path for partitioning such that the breather path and the return oil path are in parallel with each other in a direction of a rotational axis line of a crankshaft of the engine.
- 16. The breather apparatus according to claim 15, wherein said partition wall includes a water path formed therein for communicating cooling water jackets of the cylinders adjacent the space portion.
- 17. The breather apparatus according to claim 14, wherein said space is bounded by outer circumferences of the cylinders.
- 18. A breather apparatus for recirculating blowby gas from a crankcase to an intake system of a V-type internal combustion engine, said V-type internal combustion engine including a cylinder block formed with a first and a second bank forming a V-shape, said breather apparatus comprising a breather path formed in a space portion between first and third cylinder bores in the first bank, wherein said space portion is formed with a return oil path for lubricating oil and a partition wall is provided between said breather path and the return oil path for partitioning such that the breather path and the return oil path are in parallel with each other in a direction of a rotational axis line of a crankshaft of the engine.
- 19. The breather apparatus according to claim 18, wherein said partition wall includes a water path formed therein for communicating cooling water jackets of the cylinders adjacent the space portion.
- 20. A breather apparatus for recirculating blowby gas from a crankcase to an intake system of a V-type internal combustion engine, said V-type internal combustion engine including a cylinder block formed with a first and a second bank forming a V-shape, said breather apparatus comprising a breather path formed in a space portion between first and third cylinder bores in the first bank, wherein said space portion is formed with a return oil path for lubricating oil and a partition wall is provided between said breather path and the return oil path for partitioning such that the breather path and the return oil path are in parallel with each other in a direction of a rotational axis line of a crankshaft of the engine.
- 21. The breather apparatus according to claim 20, wherein said partition wall includes a water path formed therein for communicating cooling water jackets of the cylinders adjacent the space portion.
Priority Claims (1)
Number |
Date |
Country |
Kind |
2000-387707 |
Dec 2000 |
JP |
|
US Referenced Citations (11)
Foreign Referenced Citations (1)
Number |
Date |
Country |
64-7209 |
Feb 1989 |
JP |