U.S. patent number 3,919,986 [Application Number 05/403,158] was granted by the patent office on 1975-11-18 for output controlling method and device for internal combustion engines.
This patent grant is currently assigned to Toyota Jidosha Kogyo Kabushiki Kaisha. Invention is credited to Kenji Goto.
United States Patent |
3,919,986 |
Goto |
November 18, 1975 |
Output controlling method and device for internal combustion
engines
Abstract
A method of and a device for controlling the output of an
internal combustion engine, in which a mixture in an amount
corresponding to the amount required for the full load operation of
the engine is caused to flow into each cylinder in the suction
stroke, even in the case of partial load operation, and, in the
compression stroke, the amount of mixture required for the
particular load of the engine is remained in the cylinder and the
remaining part thereof is caused to flow back into the suction
system from the cylinder.
Inventors: |
Goto; Kenji (Shizuoka,
JA) |
Assignee: |
Toyota Jidosha Kogyo Kabushiki
Kaisha (Aichi, JA)
|
Family
ID: |
13628626 |
Appl.
No.: |
05/403,158 |
Filed: |
October 3, 1973 |
Foreign Application Priority Data
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|
|
|
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Jul 9, 1973 [JA] |
|
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48-77251 |
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Current U.S.
Class: |
123/316;
123/324 |
Current CPC
Class: |
F02D
9/08 (20130101); F02D 9/06 (20130101); F02D
33/00 (20130101) |
Current International
Class: |
F02D
9/06 (20060101); F02D 33/00 (20060101); F02D
9/08 (20060101); F02D 9/00 (20060101); F01L
001/34 () |
Field of
Search: |
;123/105,75E |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Burns; Wendell E.
Assistant Examiner: Reynolds; David
Attorney, Agent or Firm: Spensley, Horn and Lubitz
Claims
I claim:
1. A method of controlling the output of a four-cycle internal
combustion engine, comprising supplying an amount of mixture
corresponding to the amount required at the full-load operation of
the engine into a cylinder of the engine at the suction stroke, and
at the compression stroke causing an amount of mixture in excess to
the amount required for operation of the engine to flow back from
the cylinder into a suction pipe by the action of the piston in
said cylinder, said mixture in excess being delivered only to the
suction pipe coupled to the corresponding cylinder and being
substantially confined for use within said corresponding cylinder,
whereby the output of the engine is controlled.
2. The method of claim 1 wherein:
said amount caused to flow back is controlled by throttling said
flow-back of said excess mixture such that the amount of said
flow-back entering a conduit communicating with said suction pipe
is controlled, said throttling of said flow-back being achieved by
a throttle disposed within said conduit.
3. A device for controlling the output of an internal combustion
engine comprising a suction port from which an amount of mixture
corresponding to the amount required for the full load operation of
the engine is supplied into a cylinder, a back-flow port provided
separately from said suction port, a conduit communicating the
cylinder with a suction pipe through the back-flow port in a direct
fashion such that substantially all of said mixture delivered
through said conduit to said suction pipe is supplied to said
cylinder corresponding to said conduit and suction pipe, said
back-flow port being opened only at a specific stage of the
compression stroke of the engine, and a throttle valve provided in
the conduit and being operated such that said throttle is angularly
displaced in a closing direction as the load on the engine is
increased.
4. The device of claim 3 wherein:
said internal combustion engine is a four cycle engine; and
said back-flow port is opened during the compression cycle between
bottom dead center and 130.degree. after bottom dead center, said
back-flow port having a maximum opening at 60.degree. after bottom
dead center.
5. The device of claim 3 wherein:
said suction pipe and said conduit are exterior to the walls of
said cylinder.
Description
BACKGROUND OF THE INVENTION
This invention relates generally to the control of the output of
internal combustion engines, and particularly to a method of and a
device for controlling the output of internal combustion engines,
in which a mixture once sucked into each cylinder in an amount
corresponding to the amount required for the full load operation of
the engine, even in the case of partial load operation, is
partially caused to flow back into the suction pipe in the
compression stroke, the amount of mixture flowing back into the
suction pipe being controlled thereby to control the output of the
engine.
The output of internal combustion engines, e.g. reciprocating
internal combustion engines, has generally been controlled by a
throttle valve which is provided in the suction pipe between the
suction valve and the carburetor Venturi at a location downstream
of said carburetor Venturi and which is opened and closed by the
accelerator pedal operatively interlocked therewith.
The conventional internal combustion engines of the type described
have had the following disadvantages: Namely, (1) the amount of the
residual gas is large because the combustion gas is sucked into the
suction system under the effect of the vacuum pressure occurring in
said suction system during the overlapping period of the opening
strokes of the suction valve and exhaust valve; (2) a fluctuation
of the vacuum pressure in the suction stroke under varying load on
the engine results in a fluctuation of the amount of liquid fuel in
the suction pipe and control of the air fuel ratio during the
period of this fluctuation is difficult; (3) in the suction stroke,
the vacuum pressure in the suction pipe increases the pumping loss;
and (4) the throttle valve closes the suction pipe at the
deceleration of the engine, so that a shortage of the intake air
results and unburned gases are released into the atmosphere.
SUMMARY OF THE INVENTION
According to the present invention, an amount of mixture
corresponding to the amount required for the full load operation of
the engine, even in the case of partial load operation, is sucked
into each cylinder in the suction stroke and, in the compression
stroke, the mixture is partially caused to flow back into the
suction pipe according to the load on the engine, whereby the
output of the engine is controlled.
To this end, according to the invention each cylinder of the engine
is provided with at least two ports which are respectively
communicated with the suction pipe and opened and closed by valve
means and the like, and a conduit communicating at least one of
said ports with the suction pipe is provided therein with a
throttle valve whose opening is controlled by an output controlling
mechanism such as an accelerator pedal and a conduit communicating
at least one other port with the suction pipe is used for passing
an amount of mixture corresponding to the amount required for the
full load operation of the engine, in the suction stroke the amount
of mixture corresponding to the amount required for the full load
operation being sucked into the cylinder from said latter port and,
in the compression stroke, said latter port being closed and the
mixture in the cylinder being partially caused to flow back into
the suction pipe from said former port according to the degree of
opening of said throttle valve, whereby the output of the engine is
controlled.
An object of the invention is to provide a method of and a device
for controlling the output of internal combustion engines, which
does not make the internal pressure of the suction pipe extremely
low, which minimizes the pumping loss and which prevents the
exhaust gas from being sucked into the suction system under the
effect of the vacuum pressure in said suction system.
Another object of the invention is to provide a method of and a
device for controlling the output of internal combustion engines,
which increases the amount of mixture in proportion to the amount
of residual gas at the deceleration of the engine from a high speed
phase of operation and does not cause misfire.
Still another object of the invention is to provide a method of and
a device for controlling the output of internal combustion engines,
which maintains the amount of mixture supplied from the suction
port constant independently of the fluctuation of the load on the
engine, which reduces to a minimum the fluctuation of the amount of
liquid fuel passing in the suction pipe and facilitates control of
the air fuel ratio.
Still another object of the invention is to provide a method of and
a device for controlling the output of internal combustion engines,
which prevents misfire or after-burning at the start of
deceleration due to overpitch arising from the gasification of
liquid fuel and which prevents overheating of an exhaust gas
purifying device when such device is used with the engine.
A further object of the invention is to provide a method of and a
device for controlling the output of internal combustion engines,
which during operation of the engine under low loads, causes the
mixture to recirculate repeatedly between the suction system and
the cylinder, whereby the atomization of the mixture is promoted,
the combustion chamber of the cylinder is cooled by the
recirculating mixture, the suction gas temperature and therefore
the highest combustion temperature is lowered owing to the reduced
pumping loss, and the discharge of NOx is decreased.
An additional object of the invention is to provide a method of and
a device for controlling the output of internal combustion engines,
in which during the compression stroke, the compressed gas is
caused to flow back into the suction system from the cylinder,
whereby swirling of the gas in the combustion chamber is enhanced,
the combustion rate is increased and thereby the efficiency of the
engine is increased.
BRIEF DESCRIPTION OF THE DRAWINGS
FIGS. 1 to 3 are sectional views of a reciprocating four-cycle
internal combustion engine in which the present invention is
embodied, FIG. 1 being a view of the engine in the suction stroke,
FIG. 2 being a view of the engine in the compression stroke, and
FIG. 3 being a view of the engine in the exhaust stroke;
FIG. 4 is a characteristic diagram illustrating the operations of
the valves of the internal combustion engine shown in FIGS. 1 to 3;
and
FIG. 5 is an indicator diagram (P-V diagram) of the internal
combustion engine.
DESCRIPTION OF THE PREFERRED EMBODIMET
With reference to FIGS. 1 to 3, a cylinder head 1A of a cylinder 1
of an internal combustion engine is provided with a suction port
2A, a suction valve 2 for opening and closing said port 2A, an
exhaust port 3A, an exhaust valve 3 for opening and closing said
port 3A, a back-flow port 4A and a back-flow valve 4 for opening
and closing said port 4A.
A conduit 5A diverged from a suction pipe 5 is connected to the
back-flow port 4A and the suction pipe 5 is connected to the
suction port 2A.
The conduit 5A is provided therein with a throttle valve 6 by which
the flow in said conduit is controlled. The throttle valve 6 is
operatively interlocked with an output controlling mechanism, such
as an accelerator pedal, (not shown) to be operated thereby in such
a manner that it is angularly displaced in a closing direction as
the load on the engine increases and in an opening direction as the
load on the engine decreases. Reference numeral 7 designates a
piston.
The suction valve 2, the exhaust valve 3 and the back-flow valve 4
respectively are operated by operating means, such as cams, (not
shown) which are operatively interlocked with the output shaft of
the engine, in the manner shown in the characteristic diagram of
FIG. 4. In the characteristic diagram of FIG. 4, the axis of
abscissa is scaled by the crank angle .theta. of the engine and the
axis of ordinate by the valve lift h, and the curve A represents
the operational characteristic of the exhaust valve 3, the curve B
the operational characteristic of the suction valve 2 and the curve
C the operational characteristic of the back-flow valve 4. Namely,
the exhaust valve 3 starts opening from a point immediately before
the piston 7 reaches its bottom dead center I of the piston 7 and
is closed at a point immediately after the piston 7 reaches its top
dead center I. The suction valve 2 starts opening at a point
immediately before the piston 7 reaches its top dead center I and
is closed at a point immediately after the piston reaches its
bottom dead center II. The back-flow valve 4 starts opening at a
point immediately before the piston reaches its bottom dead center
II and is closed at a point about 130.degree. of the crank angle
from the bottom dead center II of the piston, the lift of said
valve being largest at a point where the crank angle is
60.degree..
Now, the operation of the internal combustion engine described
above will be described.
The suction valve 2 is opened at the point immediately before the
piston 7 reaches its top dead center (TDC) and a mixture is sucked
into the cylinder 1. The volume of the mixture is the same as that
required at the full load operation of the engine, even in the case
of not full load operation, and the pressure thereof is the
atmospheric pressure (or the pressure of supercharged mixture when
a supercharger is used). The flow-back valve 4 is opened at the
point immediately before the piston 7 moving down from its top dead
center I reaches its bottom dead center (BDC) II and closed at the
point when the piston 7 advances from its bottom dead center II
about 130.degree. in terms of the crank angle. The suction valve 2
is closed at the point immediately after the piston reaches its
bottom dead center II. Thus, it will be understood that the mixture
in the cylinder 1 is forced back into the conduit 5A and suction
pipe 5 through the back-flow port 4A in an amount according to the
degree of opening of the throttle valve 6 in the initial stage of
the compression stroke. (No mixture is forced back into the conduit
5A when said conduit is closed by the throttle valve 6.)
As a consequence, the engine generates an output corresponding to
the amount of mixture remaining in the cylinder I and operates
along the P-V curve shown in the diagram of FIG. 5.
The mixture forced back into the conduit 5A is partially or
entirely sucked into the cylinder 1 at the next suction stroke
through the suction pipe 5 and the suction port 2A and the mixture
thus sucked is further partially recirculated in the passage formed
by the cylinder 1, the conduit 5A and the suction pipe 5.
Although in the embodiment described and illustrated herein the
opening and closing of the suction port 2A and the back-flow port
4A are effected by means of valves, it should be understood that
the same may be effected by any other means. It should also be
understood that while the present invention has been described
herein as applied to a four-cycle reciprocating internal combustion
engine, it is generally applicable to other types of internal
combustion engine, including a reciprocating two-cycle internal
combustion engine or rotary piston engine.
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