Note: Descriptions are shown in the official language in which they were submitted.
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_ PATENT SPECIFICATION
- 1. Title of the Invention
Apparatus for Driving Engine Balancers :
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2. Detailed Description of the Invention
: This invention relates to improvements in apparatus
for driving engine balancers.
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For a conventional in-line four cylinders engine,
. various means to eliminate vertical secondary vibromotive
` force so as to prevent the vibration of the engine have
been proposed. But no apparatus has been available that
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eliminates secondary vibromotive momentum due to recipro-
cating mass and vibromotive momentum due to explosion torque.
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In an engine of conventional type, as is commonly known,
balancer driving mechanism is provided in the front part
thereof, separate from timing gears for
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camshaft. In addition, water pump, cooling fan and driving
mechanisms such as dynamo are arranged tandem along the
axis of the crankshaft. This not only increases the en-
tire length of the engine, but also mal~es its assembly
and maintenance complex since so many compenents as men-
tioned above are placed in a very small space.
This invention is proposed to eliminate the afore-
mentioned shortcomings. More particularly, the primary
lo feature of this invention lies in an apparatus for driving
engine balaneer in which at least a pair of balaneers are
disposed on lines that are on both sides of, at desired
distances, and substantially parallel to the axis of tne
; erank shaft. In this balancer driving mechanism, said
pair of balaneers are at distanee from eaeh other with
respect to the axis of the cylinders, and are so designed
as to rotate opposite to each other, at a speed twiee the
rotating speed of the cranlc shaft. A gear shaft re~ersing
one of said pair of balancers and a driving mechanism driving
the other balancer shaft, the camshaft and so on through
a timing belt or a timing chain by means of the cran]c
shaft are disposed in the front or rear part of the cyl-
inder block.
Now this invention will be described in detail
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with reference to the accomp~nying drawings, in which:
~ig. 1 is a schematic view of an embodiment of this in-
ven-tion, with a part thereof cut open. Fig. 2 is a
- cross-sec-tional view as seen in the direc-tion of arrow
s II-II in Fig. 1. Fig. 3 is a schematic view showing an
;; application of this invention, with a part thereof cut
open. Fig. 4 is a cross-sectional view looking in the
direction of arrow IV-IV in ~ig. 3. And Fig. 5 is a
schematic view of another application of balancer driving
mechanism according to this invention.
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;~ Referring first to Figs. 1 and 2, an embodlment
of this invention will be described in detail.
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;~; 15 A crank shaft 1 is fitted in a cylinder block 2.
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At least a pair of balancer shafts 3 and 4 are disposed
on lines that are on both sides of, at desired distances,
and substantially parallel to the axis of the cranls shaft
1. Said pair of balancer shafts 3 and 4 are at distance
from each other with respect to the axis of the cylinders,
and are so designed as to rotate opposite to each other,
at a speed 2~ twice the rotating speed ~ of the crank
shaft 1, as illustrated in Fig. 1.
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25 Item 5 is a belt pulley fitted to the shaft 7 of
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a reversing gear, not shown, that meshes with a gear 6
fitted to the balancer shaft 4. Reference numberal 8
denotes a belt pulley fitted to said balancer shaft 3,
9 a belt pulley fitted to a camshaft lO, ll a belt pulley
fitted to said crank shaft l, 12 a timing belt engaged
with said belt pulleys 5, 8 9 and ll and 13 and 14 an
idler and a tension, respectively, of said timing belt 12.
Journals 19 and 20 of the crank shaft 1 are supported in
bearings 21 and 22, respectively. A piston Z3 is fitted
to the end of a connecting rod 24 supported by the crank
shaft 1. Reference numeral 25 designates a flywheel, 26
a bell housing, 27 a timing gears case fitted in the
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front part of the cylinder blocks 2, 28 a cooling fan op-
erated by a belt driving mechanism 29 connected with the
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crank shaft 1, and 30 an oil pan.
In the embodiment of this invention thus composed, the
balancer shafts 3 and 4 are driven, when the engine operates
by the single timing belt 12 through the belt pulleys 5,8,
9 and 11. This dispenses with the need ~f providing
separate driving mechanisms for the cam shaft and the balan-
cers, different from the conventional apparatus. Accordingly
the apparatus of this invention can be placed compactly in
a small space in the frontpart of the engine, thus reducing
its manufacturing cost
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and increasing its maintainabili-ty. F~lrthert it can eli-
minate secondary vibromotive force and momentum due to
reciprocating mass and explosion torque simultaneously
and remar~ably. ~s is eviden-t from above, this invention
; 5 offers excellent operations and results.
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Now an example in which the above-described em-
bodiment of this invention is applied will be described
~ith reference to Figs. 3 and ~, wherein parts similar
to those in Figs. 1 and 2 are designated by similar ref-
; erence numerals.
In this example, the balancer driving mechanismof this invention is placed in the rear part 31 of the
cylinder block, which was provided in the front part there-
of in Figs. 1 and 2. This arrangement necessitates only
expanding the bell housing 26 enclosing a clutch 32 up-
ward as sho~m in Fig. 3, while making the timing gears
case used in the conventional apparatus no longer nec-
essary. Therefore, the entire length of the engine, inthe longitudinal direction of the crank shaft, can be
reduced. Also, maintainability of the engine is improved
because only the cooling fan and some auxiliary compo-
nents such as the dynamo are provided in the front part
of the engine.
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~nother example wherein the above-described em-
bodiment of this invention is applied v~ill be explained
vlith reference to Fig. 5, in which parts similar to those
in Figs. 1 through 4 are designated by similar reference
numerals.
In this second example, the mechanism for reversing
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one of the pair of balancer shafts ~ employed in the above-
described emboidment is eliminated. Instead, as illus-
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trated in Fig. 5, the belt pulley 5 is fitted to the
balancer shaft 4, and a timing belt 36, having indenta-
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tions 33 and 34 on both sides, is used.
As shown in Fig. 5, the internal indentations 33
of said timing belt 36 are engaged with the belt pulley
8 on one of the pair of balancer shafts 3, while the ex-
ternal indentations 34 thereof with the belt pulley 5 on
the other balancer shaft 4, whereby said balancer shafts
3 and 4 and the camshaft 9 are driven by the motive power
-~ 20 of the crank shaft 1. This arrangement may be provided
~ in both the front and rear parts of the cy~inder block 2
- depending on its design, as in the cases of Figs. 1 and 3.
In the aforesaid example, the balancer shafts 3
and 4 are rotated in opposite directions by a single
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timing belt, without employing any particular reversing
mechanism. This lowers manufacturing cos-t, simplifies
the structure of the balancer driving mechanism, and re-
duces occurrence of troubles. So the same operations
5 and results as can be obtained from the aforesaid embodi-
ment are expectable.
: Instead of the timing belt used in the above-men-
tioned example, sprockets and a chain may be used. Also,
the same operations and results can be obtained ~Ihen this
invention is used for a horizontal engine.
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