Note: Descriptions are shown in the official language in which they were submitted.
2093~77
CRANRSHAFT OF V-TYPE 6-CYLINDER rNTERNAL COMBUSTION ENGINE
BACRGRO~ND OF THE INVENTION
(1) Field of the Invention
The present invention relates to a crankshaft of a V-type
6-cylinder co~bustion engine having four crank journals.
(2) Description of the Prior Art
A crankshaft has an important function of producing dynamics
by changing rectilinear motion generated by pistons of each
cylinder into rotational motion, and, at the same time, applying
force with the pistons that reach a bottom dead point to occur
the rectilinear motion successively. The crankshaft should be
able to rotate without vibration, since the center of crank
journals and crank pins is eccentric to each other, and the
crankshaft cannot normally maintain a balance.
In order to solve such a problem, balance weights are
generally provided to crank arms opposite to the crank pins to
maintain balance during the rotation of the crankshaft.
While the balance weights used in a small-sized engine are
formed integrally with the crank ar~s, those in a large-sized
engine are made separately and attached to crank arms.
The balance weights are aligned in a symmetrical direction
to offset inertia couple. Since the development angle of the
crank arms in a series 4-internal co~ustion engine usually has
180 degrees, there is no problem in the disposition of the
balance weights. In the case of the V-type 6-cylinder internal
combustion engine, however, it is hard to position the balance
weights. Because the weight of the crankshaft i6 excessively
~093677
heavy, if the balance weights are provided to all the crank arms,
torsional vibration occurs in the high speed reqion engine.
U.S. Patent Nos. 4,552,104 and 4,730,512 disclose methods
to solve such problems of the V-t~ype 6-cylinder internal
combustion engine.
Force of the crankshaft acting on both of its ends
influences the size of inertia couple. In the above method,
dynamic balance on the whole crankshaft is effectively achieved
by disposing balance weights on both of its ends, and dynamic
balance between adjacent main bearings is achieved by disposing
balance weight on the midmost crank arm .
However, the balance weight pro~ided to the midmost crank
arm just influences the dynamic balance between the adjacent main
bearings, and does not influence the dynamic balance on the whole
crankshaft. Thus, the dynamic balance on the whole crankshaft
depends on each pair of the balance ~eights disposed on both the
ends of the crankshaft, and the size of the balance weights must
be large. When it comes to molding of the crankshaft, a die has
an upper-and-lower separating line. In the case of the balance
weight disposed on the midmost crank arm, the separating line is
on an adjacent crank pin, and upper and lower dies move in a
direction of the center of gravity of the balance weight.
Accordingly, it is too hard to mold a proper size of the balance
weight.
A crankshaft disclosed in Japansse Unexamined Publication
No. Sho 60-227037 has six balance weig~ts aligned in line to each
crank arm to have 60 degrees of its disposition angle, and the
2093677
inertia couple may be thereby relieved.
The third and fourth balance weights disposed on the crank
arms adjacent to the midpoint of the crankshaft contribute to the
dynamic balance between adjacent main bearings and the dynamic
balance of the whole crankshaft, as well. Since the second and
fifth balance wleights are provided to the third and seventh crank
arms, moment arm is thereby short, and this technique is not
effective. In conclusion, the first and sixth balance weights
should be for~ed large.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a
crankshaft of a V-type 6-cylinder internal combustion engine
which ensures a decrease of the engine vibration and surface
pressure affecting each crank journal by achieving effectively
dynamic balance of a whole crank shaft and dynamic balance couple
between inner main bearings with an optimus size of balance
weight.
It is another object of the present invention to provide a
crankshaft of a V-type 6-cylinder internal combustion engine
which can pr~mote productivity of a cran~shaft as desired,
especially, balance weights.
The crankshaft of a V-type 6-cylinder internal combustion
engine of this invention including first to sixth crank pins
connected with connecting rods, having first to fourth crank
journals between the first to sixth crank pins, and first to
ninth crank arms between first to sixth crank pins and the first
to fourth crank journals, comprises:
2a99~77
a first balance weight provided to the first crank arm, the
center of gravity of the first balance weight being mal-
distributed to the lower part with respect to the center axis of
the crankshaft;
a second balance weight provided to the second crank arm,
the center of gravity of the second balance weight being mal-
distributed to the lower part, and deviated from the first
balance weight in a counterclockwise direction;
third and fourth balance weights provided respectively to
the fourth crank arm and sixth crank arm and having centers of
gravity deviated upward and downward and orthogonally in a
clockwise direction with respect to the center of gravity of the
first balance weight;
a fifth balance weight provided to the eiqhth crank arm, the
center of gravity of the fifth balance weight being in vertical
~ymmetry with the second balance weight; and
a sixth balance weight provided to the ninth crank arm, the
center of gra~ity of the sixth balance weight being mal-
distributed to be in vertical symmetry with the first balance
weight.
In addition, when viewed from the front of the crankshaft
(FIG. 6), the first and sixth balance weights, and the second,
third, fourth, and fifth balance weights maintain rotatary
balance each other to equilibrate as a whole.
As another embodiment of this invention, one balance weight
may be disposed between the third and fifth balance weights.
The inertia couple and unbalanced couple by balance weight~
~g677
can be offset by the disposition of such balance weights.
Accordingly, in another aspect the present invention
resides in a crankshaft of a V-type 6-cylinder internal
combustion engine including first to sixth crank pins
connected with connecting rods, having first to fourth
crank journals between said first to sixth crank pins, and
first to ninth crank arms between first to sixth crank pins
and the first to fourth crank journals, the combination
therewith comprising:
a first balance weight provided to said first crank
arm, a center of gravity of said first balance weight being
initially mal-distributed to a lower part of said first
crank arm with respect to a center axis of the crankshaft;
a second balance weight provided to said second crank
arm, a center of gravity of said second balance weight
being initially mal-distributed to a lower part of said
first crank arm, and offset from said first balance weight
in a counterclockwise direction, wherein the center of
gravity of said second balance weight is formed to be
offset by 30 degrees in a counterclockwise direction from
said first balance weight;
third and fourth balance weights provided respectively
to said fourth crank arm and sixth crank arm, with centers
of gravity of said third and fourth balance weights being
initially mal-distributed to be offset from said first
balance weight in a clockwise direction;
a fifth balance weight provided to said eighth crank
arm, a center of gravity of said fifth balance weight being
initially mal-distributed to be in vertical symmetry with
said second balance weight; and
a sixth balance weight provided to said ninth crank
arm, a center of gravity of said sixth balance weight being
initially mal-distributed to be in vertical symmetry with
said first balance weight, and wherein said fifth crank arm
is free of a balance weight.
209~6~7
Further scope of applicability of the present invention will
become apparent from the detailed description given hereinafter.
~owever, it shculd be understood that the detailed description
and specific eYamples, while indicatimg 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 DESC~IPTION OF T~E DRAWINGS
The present invention will beco~ more fully understood from
the detailed description given hereinhelow and the accompanying
drawings which are given by way of ill~stration only, and thus,
are not limitative of the present inYention, and wherein:
FIG. 1 is a side view of a cr~n~ ft in accordance with a
first preferred embodiment of the present invention;
FIG. 2A is a sectional view ta~en along lines I - I of FIG.
l;
FIG. 2B is a sectional view ta~n along lines II - II of
FIG. l;
FIG. 2C is a sectional view ta~en along lines III - III of
PIG. l;
FIG. 2D is a sectional view ta~n along lines IV - IV of
FIG. l;
FIG. 2E is a sectional view ta~en along lines V - V of FIG.
l;
FIG. 2F is a sectional view ta~en along lines VI - VI of
2~9677
FIG. l;
FIG. 3 is a plan view of the cran~shaft in accordance with
the first preferred embodiment of this invention;
FIG. 4 depicts schematically the disposition of balance
weights of FIG. l;
FIG. 5 depicts schematically the disposition of balance
weights of FIG. 3;
FIG. 6 depicts schematically the disposition of the balance
weights of the first embodiment, centering around a center axis
of the crankshaft;
FIG. 7 depicts schematically the size of each centrifugal
force of the balance weights as sho~n in FIG. 4;
FIG. 8 is a side view of a cr~n~s~ft in accordance with a
second preferred embodiment of the present invention;
FIG. 9A iS a sectional view taken along lines I - I of FIG.
8;
FIG. 9B iS a sectional view ta~en along lines II - II of
FIG. 8;
FIG. 9C iS a sectional view taken along lines III - III of
FIG. 8;
FIG. 9D is a sectional view taken along lines IV - IV of
FIG. 8;
FIG. 9E iS a sectional view taken along lines V - V of FIG.
8;
FIG. 9F iS a sectional view taken along lines VI - VI of
FIG. 8;
FIG. 9G iS a sectional view taken along lines VII - VII of
20~9677
FIG. 8;
FIG. 10 is a plan view of the cran~shaft in accordance with
the second preferred embodiment of this invention;
FIG. 11 depicts schematically the disposition of balance
weights of FIG. 8;
FIG. 12 d~picts schematically t~e disposition of balance
weights of FIG. 10;
- FIG. 13 depicts schematically the disposition of the balance
weights of the second embodiment, centering around a center axi~
of the crankshaft; and
FIG. 14 depicts schematically the size of each centrifugal
force of the balance weights as shown in FIG. 11.
DETAILED DESCRIPTION OF THE Pk~KKED EMBODIMENTS
FIG. 1 is a side view of a cran~shaft in accordance with
this invention, and reference numerals 1 to 6 designate first to
~ixth crank pins connected to connectinq rods.
The pair of crank pins 1, 2 is arranged between first and
second crank journals 11, 12, the pair of crank pins 3,4 is
arranged between second and third crank journals 12, 13, and the
pair of crank pins 5, 6 is arranged between third and fourth
crank journals 13, 14.
First, second, third, fourth, fifth, sixth, seventh, eighth
and ninth crank arms 21 to 29, respectively, are interposed
between the first to sixth crank pins 1 to 6, respectively and
the first to fourth crank journals 11 to 14. A flywheel (not
illustrated) is provided to a flange 30 formed to be adjacent to
the fourth crank journal 14.
- 2099677
In the crankshaft of the present imvention, first and second
balance weights 31, 32 are provided respectively to the first and
second crank arms 21, 22 of the front end a~ong the first to
ninth crank arms 21 to 29.
The third and fourth balance weights 33, 34 are provided
respectively to the midmost fourth a~d sixth crank arms 24, 26.
The fifth and sixth crank arms 28, 29 of the rear end are
provided with the fifth and sixth balance weights 35, 36.
FIGS. 2A to 2F are sectional views of each part of the
crankshaft. The center of gravity of the first balance weight 31
provided to the first crank arm 21 is mal-distributed to the
lower part to the center axis C of the crankshaft. The center of
gravity of the second balance weight 32 provided to the second
crank arm 22 is mal-distributed to the lower part, as shown in
FIG. 2B, and the second balance weight 32 is located to be
deviated by about an angle of 30 degrees in the counterclockwise
direction from the first balance weight 31.
The third balance weight 33 provid~d to the fourth crank arm
24 and the fourth balance weight 34 provided to the sixth crank
arm 26 are mal-distributed upward and downward in a direction
orthogonally to the left with respect to the center of gravity
of the first balance weight 31, as sh~wn in FIGS. 2C and 2D, and
the center of gravity between them is in vertical symmetry. The
fifth balance weight 35 provided to the eighth crank arm 28 is
located in vertical symmetry with the second balance weight 32
as shown in FIG. 2E. The sixth balance weight 36 provided to the
ninth crank arm 29 is located in vertical symmetry with the fir~t
2099677
-
balance weight 31, as shown in FIG. 2F.
Like the second balance weight 32, the fifth balance weight
35 is located to be deviated by about 30 degrees in the clockwise
direction from the sixth balance wei~ht 36. The first balance
weight 31 and sixth balance weight 36, the second balance weight
32 and fifth balance weight 35, and h~ third balance weight 33
and fourth balance weight 34 are identical to and almost the same
as each other in first moment of mass.
Accordingly, the first, second balance weights 31, 32
disposed on the both ends of the cran~haft are in symmetry with
the fifth and sixth balance weights 35, 36. The midmost third and
fourth balance weights 33, 34 are disposed upward and downward
in a direction orthogonally to the first and second balance
weights 31, 32, as shown in FIG. 3.
The disposition of each balance weight 31 to 36 of FIG. 1
may be depicted in FIG. 4.
Thus, the first and sixth balance weights 31, 36, the second
and fifth balance weights 32, 35, and the third and fourth
balance weights 33, 34, are disp~sed respectively to be
symmetrical to the center axis C of the crankshaft, and the third
balance weight 33 is in symmetry with the fourth balance weight
34 with respect to the center axis of the crankshaft.
What is depicted in FIG. 3 is obtained by rotating the
structure in FIG. 1 by 90 degrees, a~d the disposition of the
balance weights is changed, as shown in FIG. 5.
The first and sixth balance weig~*s 31, 36, the second and
fifth balance weights 32, 35, and the third and fourth balance
2a3~77
~eights 33, 34, are in symmetry with each other with respect to
the center axis C.
Therefore, in the crankshaft of this invention, the balance
weights are arranged in axial sy letry completely with respect
to the center aYis.
FIG. 6 depicts the disposition of the first to sixth balance
weights 31 to 36 with respect to the center axis C of the
crankshaft.
The first and sixth balance ~eights 31 and 36 are in
rectilinear sy~metry with each other. The second balance weight
32 is disposed contrary to the crank pins 1, 2, with an angle ~
of + 30 degrees with respect to a line connecting the center of
the crank pins 1 and 2 to the center axis C. The fifth balance
weight 35 is disposed contrary to the crank pins 5, 6, with an
angle ~ of + 30 degrees, with respect to a line connecting the
center of the crank pins 5, 6 to the center axis C. The second
balance weight 32 is in vertical symm~try with the fifth balance
weight. The third and fourth balance ~eights 33, 34 are arranged
in an opposite direction to the third and fourth crank pins 3,
4, and have an angle ~ of + 60 degrees with respect to the line
connecting the center of the third and fourth crank pins with the
center axis C.
An unbalanced couple around the center axis C in the
~tructure appearing in FIG. 5 does not exist. That is, an
unbalanced couple caused by rotation ~eight and turnaround weight
is offset at the center axis, and the unbalanced couple due to
the disposed balance weights is offset, too.
1 0
-- 20~3677
However, when it comes to the unbalar~-ed couple in the
disposition as shown in FIG. 4, referring to FIG. 7, the
unbalanced couple caused by rotation weight and turnaround weight
occurs in a direction as indicated by arrows A1 to A6. An
unbalanced couple by the crank ar~s without balance weights
occurs in a direction as indicated by arrows B1 and B2, and the
unbalanced couple by the balance weights ~s generated in a
direction as indicated by arrows Dl to D~.
Thus, the couple produced with respect to the center axis
C by arrows A1, ~ ; A2, A5; A3, A~; and s1, s2 ~ay maintain
a balance due to the couple by arrows ~, D6; D2, D5; and D3, D~.
FIG. 8 to FIG. 14 depict a cran~shaft i~ accordance with a
second preferred embodiment, and like reference numerals
designate like parts throughout all the spec~fication.
Each pair of first, second, third, fourth and sixth crank
pins 1 through 6, respectively, is arrange~ between first to
fourth crank journals 11 through 14, respect vely.
First, second, third, fourth, fifth, sixth, seventh, eighth
and ninth crank arms 21 through 29, respectively, are interposed
between the first through sixth crank p~ns 1 through 6,
respectively, and the first through fourth crank journals 11
through 14. A flywheel (not illustrated) is provided on a flange
30 formed to be adjacent to the fourth crank journal 14.
In the crankshaft of the present inventio~, first and second
balance weights 31, 32 are provided respectively to the first and
second crank arms 21, 22 of the front end of the crankshaft among
the first to ninth crank arms 21 through 29. The third, fourth
2093677
and fifth balance weights 33, 34, 35 are provided respectively
to the midmost fourth, fifth, sixth crank arms 24, 25, 26. The
fifth and siYth crank arms 28, 29 of the rear end of the
crankshaft are provided with the fifth and sixth balance weights
36, 37.
FIG. 9A to 9G are sectional views of each part of the
crankshaft. The center of gravity of the first balance weight 31
provided to the first crank arm 21 is mal-distributed to the
lower part to the center axis C of the crankshaft. The center of
gravity of the second balance weight 32 provided to the second
crank arm 22 is mal-distributed to the lower part, as shown in
FIG. 9B, and the second balance weight 32 is located to be
deviated by about 30 degrees in the counterclockwise direction
from the first balance weight 31.
The third balance weight 33 provided to the fourth crank arm
24 and the fourth and fifth balance ~eights 34, 35 provided to
the fifth and sixth crank arms 25, 26 are located orthogonally
to the left with respect to the center of gravity of the first
balance weight 31, as shown in FIGS. 9C, 9D and 9E, and the
center of gravity between them is in vertical symmetry. The
center of gravity of the fifth balance weights 35 is located in
vertical symmetry with that of the third balance weight 33.
The center of gravity of the fourth balance weight 34 is
located on around the midpoint between the third and fifth
balance weights 33, 35.
The sixth balance weight 36 provid~ed to the eighth crank arm
28 is in vertical symmetry with the second balance weight 32, as
-
2039677
shown in FIG. 9F. The seventh balance weight 37 provided to the
ninth crank arm 29 is in vertical sy ~etry with the first balance
weight 31, as shown in FIG. 9G.
The sixth balance weight is dis~ ~ed to be deviated by about
30 degrees in clockwi~e direction with respect to the seventh
balance weight 37, like the second balance weight 32.
The first balance weight 31 and s~eventh balance weight 37,
the second balance weight 32 and sixth balance weight 36, and the
third balance weight 33 and fifth balance weight 35 are identical
to, or the same as each other in first moment of mass. The fourth
balance weight 34 has first moment of mass that maintains a
balance with the second, third, fifth and sixth balance weights
32, 33, 35, 36.
Accordingly, the first, second balance weights 31, 32
disposed on both ends of the crankshaft are in symmetry with the
sixth and seventh balance weights 36, 37. The midmost third,
fourth and fifth balance weights 33, 34, 35 are vertically
disposed to be orthogonal left to the line of center of gravity
between first and second balance weights 31, 32, as shown in FIG.
10 .
The disposition of each balance ~eight 31 through 37 of FIG.
8 may be depicted in FIG. 11.
The first and sixth balance weights 31, 36, the second and
fifth balance weights 32, 35, and the third and fourth balance
weights 33, 34, are disposed respectively to be symmetrical to
the center axis C of the crankshaft, and the third balance weight
33 iS in symmetry with the fourth balance weight 34 with respect
7 ~
to the center axis of the crankshaft.
What is depicted in FIG. 10 is obtained by rotating the
structure in FIG. 8 by 90 degrees, a d the disposition of the
balance weights is changed as shown in FIG. 12.
The first and sixth balance wei~hts 31, 36, the second and
fifth balance weights 32, 35, and the third and fourth balance
weights 33, 34, are in symmetry with each other with respect to
the center axis C.
Therefore, in the crankshaft of this invention, the balance
weights are arranged in axial symmetry with respect to the center
axis.
FIG. 13 depicts the disposition of the first through seventh
balance weights 31 through 37 with respect to the center axis C
of the crankshaft.
The first and seventh balance ~eights 31 and 37 are in
rectilinear symmetry with each other. The second balance weight
32 is disposed contrary to the crank pins 1, 2, with an angle a
of i 30 degrees with respect to a li~e connecting the center of
the crank pins 1 and 2 to the center axis C. The sixth balance
weight 36 is disposed contrary to the crank pins 5, 6, with an
angle ~ of i 30 degrees, with respect to a line connecting the
center of the crank pins 5, 6 to the center axis C.
An unbalanced couple around th~ center axis C in the
structure appearing in FIG. 12 does not exist. That is, an
unbalanced couple caused by rotation ~eight and turnaround weight
is offset at the center axis, and ~h~ unbalanced couple due to
the disposed halance weights is offset, too.
1 4
209~677
However, when it comes to the unbalance couple in the
disposition as shown in FIG. 11, referrinq to FIG. 14, the
unbalanced couple caused by rotation ~eight and turnaround weight
occurs in a direction as indicated by arrows A1 to A6. The
unbalanced couple by the crank ar~ls occurs in a direction as
indicated by arrows B1 and B2, and the unbalanced couple by the
balance weights is generated in a direction as indicated by
arrows D1 to D6.
Thus, the couple produced with respect to the center axis
C by arrows Al~ A6; A2~ A5; A3~ Al; and s1, g2 ~ay maintain
a balance due to the couple by arrows Dl, D6; D2, D5; and D3, Dl.
The present invention makes it possible to offset an inertia
couple produced from the crankshaft and achieve effectively
dynamic balance of a whole crank shaft and dynamic balance couple
between inner main bearings with an optimun size of balance
weight.
