Intake device for internal combustion engine

Intake device for multiple cylinder I.C. engine, the intake opening of the carburetor for each cylinder being connected with a carburetor base connected to an air cleaner in chamber form. The chamber intake openings for each carburetor are separated by partition plates.

SUMMARY OF THE INVENTION 
The invention relates to an intake device for an internal combustion engine 
having multiple cylinders, each provided with a carburetor, with the 
intake openings of the carburetor for each cylinder connected with a 
carburetor base, which is connected to an air cleaner in chamber form. 
Partition plates are placed between the areas of the intake openings for 
each carburetor opening into the said base, so as to serve as partitions 
between the opening areas. 
BACKGROUND OF THE INVENTION 
Engines with several cylinders are used in two wheeled motor vehicles and 
other vehicles. For example, in the case of a V type four cylinder engine, 
a serially aligned four cylinder engine, and other such engines, the 
distances between the intake openings of each cylinder are relatively 
small, and further, the configurations around them vary. In cases where 
there are differences in intake resistance, a great deal of air may be 
taken in by some particular intake openings, while the air intake is 
reduced in quantity for other intake openings. In other words, there are 
many cases involving an arrangement for the various intake openings in an 
intake system, when the openings are placed adjacent to each other due to 
considerations of space or the like, it is quite possible for intake 
quantity imbalances to arise due to the conformation around the openings 
and other such factors. 
In the design of internal combustion engines, in cases where there are 
multiple cylinders, it is hard to set out the air intake system circuits 
in the same manner for each cylinder, so that the aforementioned 
imbalances in the air intake quantities for each cylinder can easily 
arise, causing such malfunctions as imbalances in intake volume 
effectiveness, imbalances in carburetor settings, and the like, to occur. 
In particular, in the case of the constant vacuum type of carburetor, of 
the form in which the throttle opening degree is made larger in proportion 
to the intake quantity, the throttle does not open for cylinders where the 
intake quantity is small, while the degree of opening for cylinders with a 
large quantity of intake is great, and the imbalances of intake volume 
effectiveness, output, carburetor settings, and the like, become all the 
greater. 
For instance, in the case of the structure shown in FIG. 6, with a 
carburetor base for a four cylinder V type engine where multiple cylinders 
are arranged front and back, an air cleaner (not shown in the figure) is 
connected on top of the base 51, and on the lower wall of base 51 there 
are openings 52a, 52b, 52c, and 52d, made as intake connection openings 
for the carburetors 52 for each of the cylinders. There are variations in 
the distances between the outer rim wall area 53 of the base 51 and the 
various intake connection openings, particularly in the cases of distances 
to the left and right relative to the rim wall area sides 53a and 53b, and 
as there is variation in the configurations involved, it is easy for 
imbalances in intake volume among the various cylinders to occur. 
OBJECTION OF THE INVENTION 
The present invention is intended to resolve the imbalances in intake 
quantity among the various cylinders of an engine with multiple cylinders, 
and to achieve an equalized balance of intake quantity for each cylinder. 
It is an object of the present invention to provide an intake device for an 
internal combustion engine made in such a fashion that it achieves a rise 
in performance capacity for the multiple cylinder engine as a whole, by 
making the configurations around the intake connection openings for each 
cylinder of the multiple cylinder engine more or less the same, having a 
set intake quantity for each cylinder, balancing the intake effectiveness 
among the cylinders, balancing output, balancing the carburetor settings, 
and the like. 
In order to achieve this objective, the carburetor base connected with the 
air cleaner is made in chamber form, and partition plates are located in 
the spaces between the carburetor intake openings made in the several 
respective spaces in the carburetor base, the structure being so formed as 
to make the configuration around each intake opening more or less the same 
.

DESCRIPTION OF PREFERRED EMBODIMENT 
FIG. 1 is a general side view of a two wheeled motor vehicle 1, comprising 
head tube 3 at the front end of frame 2. Front fork 4, which carries front 
wheel 5, is supported so that it operates freely. At the upper front area 
of frame 2, there is placed fuel tank 6, with seat 7 attached behind it. 
Rear fork 8 extends from the lower rear area of the frame, and supports 
rear wheel 9. 
At the lower front area of frame 2, there is supported engine 10. In the 
illustrated example, this is a 90.degree. V-type engine, viewed from the 
side, with a crankshaft lateral arrangement; it is a four cylinder engine, 
with two front cylinders and two rear cylinders, each set comprising a 
left-hand and a right-hand cylinder at a distance from each other. The 
engine 10 is made up of a casing 101, which consists of the transmission 
case and the crank case. Above this are located cylinder blocks 102, 
arranged in V fashion; above these are cylinder heads 103, surmounted by 
cylinder head covers 104. On the upper part, placed to the right and left, 
at the front, are the cylinder ports for two cylinders, while at the rear, 
to the right and left, are the cylinder ports for two more cylinders, with 
openings facing frontwards. The carburetors 11 are located from the center 
to the upper area of a space C between the front and rear cylinders A and 
B; in the illustrated example, there are four carburetors 111-114 (see 
FIG. 4), for each of the cylinders. 
The intake areas 111a-114a for carburetors 111-114 are set up at relatively 
corresponding spaces with respect to each other to the right and left, and 
above the space between intake areas 111a-114a there is placed the 
carburetor base 12. The latter has the shape of a box opening at the top, 
and walls 122-125 as the four sides of its lower wall 121. The upper flow 
ends of intake areas 111a-114a of the respective carburetors 111-114 open 
into lower wall 121 in the form of intake openings 111b-114b. As shown in 
FIG. 4, intake opening 113b of carburetor 113 at the left rear side is 
joined at a position near the left side wall 122 at the rear of lower wall 
121; intake opening 111b of carburetor 111 at the left front side is 
joined at a position farther from left side wall 122 at the front of lower 
wall 121; intake opening 114b of carburetor 114 at the left side of the 
rear area is joined at a position farther from right side wall 123 of the 
lower wall; and, carburetor 112 at the left side of the front area has its 
opening joined at a position near the right side wall 123 at the front 
area of the lower wall. Thus air intake openings 111b-114b are distributed 
to front and back, right and left, in relative corresponding positions, 
without overlap, joined at positions in the lower wall. As for the 
sparking order of the intake system described above, inclusive of the 
carburetors, the progression is from carburetor 113 to carburetors 112, 
114 and 111 in succession. 
Above lower wall 121 of base 12, partition plates 126-128 are inserted with 
their ends against the front and back walls 124 and 125; partition plate 
126 is set in place so as to divide the space between intake openings 113b 
and 111b, partition plate 127 is placed so as to divide the space between 
intake openings 111b and 114b, and partition plate 128 is placed so as to 
divide the space between intake openings 114b and 112b. As a result, the 
left and right end walls 122 and 123, as well as the partition plates 
126-128, divide up the spaces around intake openings 111b-114b more or 
less evenly, creating roughly uniform volume area spaces a-d, which are 
open at the top. 
On top of base 12, there is installed an air cleaner 13. The casing 131 for 
air cleaner 13 is shown in FIG. 2. The front area is enclosed by the 
enclosure wall 132. The receiver section 135 is placed so as to receive 
element 134, with lower wall 133. The rear area 136 is so formed as to 
make a double base construction when placed on top of the base 12, and 
this section is connected with the receiver section 135. The top wall 137 
has arranged below it, from front to back, the partition plates 126-128, 
with partition segments 138-140 fitted vertically so as to fit with the 
partition plates 126-128. Top wall 137 slopes down towards the rear, and 
the open spaces between the partition segments are 138-140 are connected 
with the receiver section 135. Casing 131 is so formed that its rear area 
136 fits on top of base 12 in layered fashion, and partition plates 
138-140 fit on in such a way that they form the upper half of the base. 
The left and right walls 141 of the rear area fit vertically with side 
walls 122, 123 of the base vertically. In this fashion, an intake circuit 
is formed such that the intake openings 111b-114b in the carburetor base, 
connecting with the air cleaner 13, each have the same conformation and 
the same volume capacity. In FIG. 2, 142 is a cover arrangement containing 
the intake section 143, which takes in exterior air. 
FIG. 5 shows an engine 1010 having four cylinders in a straight series 
arrangement. The carburetors 1011-1014 for each of the cylinders of this 
engine are connected with openings 1111b-1114b in the air cleaner case 
1113, which serves as the carburetor base. The partition plates 1126-1128 
are installed vertically, so as to divide the spaces between the opening 
areas. By means of a joint 1113a at the rear of air cleaner case 1113, 
there is connected element body 1132, which receives element 1134. The 
structure is covered by a cover 1142, having an intake section 1143, which 
is located above the element body 1132. Instead of a four cylinder engine, 
engines having three, five or more cylinders could also be used. 
FIG. 7 is an illustration of a structure in which the vertically protruding 
upper and lower partitions for the base 2012 and the air cleaner 2013 have 
a frame trap 2050 placed between them; it is desirable to install such 
frame trap in this area. 
If the present invention is used in the manner described above, due to the 
fact that partitions are placed so as to divide the spaces up between each 
of the intake openings for each of the cylinders, in the carburetor base, 
the conformation around each of the intake openings is more or less the 
same, and accordingly imbalances in the intake quantities are largely 
prevented, an equal balance of intake volume is achieved for each of the 
cylinders, provisions are made for balance of the carburetor settings, 
balance of the output, balance of the volume effectiveness, and the like, 
for each cylinder, and the performance capability of a multiple cylinder 
engine is increased. In addition, these advantages are obtained by making 
use of such a simple construction as the installation of partition plates.