U.S. patent number 3,603,298 [Application Number 04/853,669] was granted by the patent office on 1971-09-07 for arrangement for controlling discharge of unburnt hydrocarbons from decelerating automobile engine.
This patent grant is currently assigned to Toyota Jidosha Kogyo Kabushiki Kaisha. Invention is credited to Norihiko Nakamura, Kiyohiko Oishi, Tadahide Toda.
United States Patent |
3,603,298 |
Toda , et al. |
September 7, 1971 |
ARRANGEMENT FOR CONTROLLING DISCHARGE OF UNBURNT HYDROCARBONS FROM
DECELERATING AUTOMOBILE ENGINE
Abstract
An arrangement for controlling discharge of unburnt hydrocarbons
from decelerating automobile engine by holding throttle valve of
engine carburetor open at position slightly more open that position
of valve under idling conditions of engine comprises lever
connected to throttle valve for movement therewith. Blocking
structure moves into and out of engagement with lever for
preventing throttle valve from reaching idling position when
blocking structure engages lever. Motivating system operates to
move blocking structure into engagement with lever when automobile
engine decelerates from above predetermined speed so that throttle
valve is held open. Motivating system includes driving device
connected to operate blocking structure, speed detector for sensing
speed of automobile engine, and speed setter associated with speed
detector and driving device for causing driving devices to move
blocking structure into engagement with lever when automobile
engine decelerates from above predetermined speed.
Inventors: |
Toda; Tadahide (Sunto-Gun,
JA), Nakamura; Norihiko (Sunto-Gun, JA),
Oishi; Kiyohiko (Sunto-Gun, JA) |
Assignee: |
Toyota Jidosha Kogyo Kabushiki
Kaisha (Toyota City, JA)
|
Family
ID: |
13213602 |
Appl.
No.: |
04/853,669 |
Filed: |
August 28, 1969 |
Foreign Application Priority Data
|
|
|
|
|
Sep 3, 1968 [JA] |
|
|
43-62901 |
|
Current U.S.
Class: |
123/329;
123/406.73 |
Current CPC
Class: |
F02D
41/0005 (20130101); F02D 41/12 (20130101); F02M
3/07 (20130101); F02P 5/106 (20130101); F02B
1/04 (20130101); Y02T 10/42 (20130101); Y02T
10/40 (20130101) |
Current International
Class: |
F02D
41/00 (20060101); F02M 3/07 (20060101); F02P
5/04 (20060101); F02D 41/12 (20060101); F02P
5/10 (20060101); F02M 3/00 (20060101); F02B
1/04 (20060101); F02B 1/00 (20060101); F02p
005/04 (); F02d 003/00 (); F02d 011/10 () |
Field of
Search: |
;123/117.1,97B
;1/102 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Burns; Wendell E.
Claims
What is claimed is:
1. An arrangement for controlling the discharge of unburnt
hydrocarbons from a decelerating automobile engine by holding the
throttle valve of the engine carburetor open at a position slightly
more open than the position of the throttle valve under idling
conditions of the engine, the arrangement comprising blocking means
for holding the throttle valve of the engine carburetor open at a
predetermined position at least more open than the position of the
throttle valve under idling conditions, a driving device connected
to the blocking means and motivated by negative pressure for moving
the blocking means away from its blocking position, a speed
detector for sensing the speed of the automobile, a speed setter
responsive to the speed detector constructed and arranged to emit a
change signal for deactivating the driving device when the
automobile speed sensed by the speed detector is above a
predetermined value and for activating the driving device when the
automobile speed sensed by the speed detector is below the
predetermined value, a negative pressure take out orifice opening
to the intake passage of the engine carburetor and located on the
downstream side of the throttle valve when the throttle valve is
held open by the blocking means, and a distributor having a
negative pressure lag device motivated by negative pressure
developed at the negative pressure take out orifice whereby the
throttle valve is held open by the blocking means at a position at
least more open than the position of the throttle valve under
idling conditions only when the speed of the automobile is above
the predetermined value and the ignition time is retarded during
decelerations from speeds above the predetermined value.
2. An arrangement for controlling the discharge of unburnt
hydrocarbons from a decelerating automobile engine as in claim 1
wherein the blocking means comprises a rotatable arm free to engage
and disengage a throttle lever on the engine carburetor and wherein
the driving device is connected to the negative pressure take out
orifice during decelerations after the automobile speed sensed by
the speed detector is below the predetermined value.
Description
BACKGROUND OF THE INVENTION
The present invention relates to an arrangement for controlling the
discharge of unburnt hydrocarbons from a decelerating automobile
engine, and more particularly to an arrangement that performs this
function by holding the throttle valve of the engine carburetor at
a position slightly more open than the position of the throttle
valve under idling conditions.
When the accelerator pedal of an automobile having a gasoline
engine and carburetor is released, the throttle valve in the
carburetor closes to its least opening in a very short time. The
latest opening of the throttle valve occurs under idling
conditions. In the meantime the speed of the engine itself and the
force of the driving wheel. As a result, the negative pressure in
the intake tube sharply rises. In consequence the fresh air
decreases in volume thereby hampering a perfect compression of the
mixture in the engine cylinders. Moreover, the residual exhaust gas
in the cylinders dilutes the fresh air whereby normal combustion in
the cylinders is impossible. The atmosphere is then polluted with a
large volume of unburnt hydrocarbon discharge.
For the purpose of limiting the discharge of unburnt hydrocarbons
under deceleration of a car engine and thereby preventing air
pollution, the throttle valve must be kept slightly more open than
under idling conditions even though this may detract from the
braking effect of the engine. Conventionally, this has been
accomplished by extending the time for closing the throttle valve
by means of a pneumatic dash pot or by utilizing the high negative
pressure generated in the intake tube during deceleration and
thereby slightly pulling open the once closed throttle valve by
means of a diaphragm or the like.
Due to the nature of a pneumatic dash pot it cannot maintain the
throttle valve open by a constant degree for a long time. If the
throttle valve is to be kept open for a long time, the degree of
opening in the initial period in deceleration must necessarily be
large and this will not assure the required deceleration. Further,
it would be quite difficult to control the working time of such a
small pneumatic dash pot as can be mounted in the carburetor.
Moreover, it would be difficult to manufacture a reliable and
dependable dash pot for such use.
On the other hand, the throttle valve pulling mechanism like a
diaphragm which utilizes the high negative pressure arising in the
intake tube under deceleration cannot be prevented from discharging
unburnt hydrocarbons in the initial period in deceleration. It is
operated by the high negative pressure which arises when the
throttle valve closes once to the opening degree in idling time
under deceleration. Besides to develop the necessary force to open
the once closed throttle valve a diaphragm of considerable size is
required. If a small diaphragm is designated to develop a force
large enough to open the throttle valve, the design will be
stretched. Moreover, the diaphragm would not hold up. Further, when
the once closed throttle valve is reopened, an unfavorable
"hunting" phenomenon takes place in which the throttle valve comes
to be reclosed because of the natural drop in the negative
pressure.
Accordingly, it is an object of the present invention to eliminate
the above drawbacks and provide a device which quickly responds to
the deceleration of a car engine and immediately shifts the
carburetor throttle valve to a constant opening position maintained
with stability during deceleration.
SUMMARY OF THE INVENTION
In accordance with the present invention an arrangement is provided
for controlling the discharge of unburnt hydrocarbons from a
decelerating automobile engine by holding the throttle valve of the
engine carburetor open at a position slightly more open than the
position of the throttle valve under idling conditions of the
engine. The arrangement comprises a lever connected to the throttle
valve for movement therewith. Blocking structure moves into and out
of engagement with the lever for preventing the throttle valve from
reaching its idling position when the blocking structure engages
the lever. A motivating system is constructed and arranged to move
the blocking structure into engagement with the lever when the
automobile decelerates from above a predetermined speed. The
throttle valve is then held open. The motivating system includes a
drive device connected to operate the blocking structure, a speed
detector for sensing the speed of the automobile engine, and a
speed setter associated with the speed detector and the driving
device for causing the driving device to move the blocking
structure into engagement with the lever when the automobile engine
decelerates from above the predetermined speed.
Brief Description of the Drawing
Other objects and advantages of the present invention in addition
to those mentioned above will be apparent to those skilled in the
art from a reading of the following detailed description in
conjunction with the accompanying drawings wherein:
FIG. 1 is a partial sectional view of one embodiment of the present
invention;
FIG. 2 is a partial sectional view similar to FIG. 1 illustrating
another sequence in the operation of the present invention;
FIG. 3 is a front elevational view of another embodiment of the
present invention with portions broken away to show detail; and
FIG. 4 is a circuit on a larger scale of a car speed setter shown
in FIGS. 1 and 2.
DETAILED DESCRIPTION OF THE INVENTION
Referring in more particularity to the drawing, FIGS. 1 and 2 show
the fresh air intake passage of a carburetor 1 with a choke valve
2, a venturi tube 3 and a throttle valve 4 located in the air
intake passageway. A shaft 5 of the throttle valve 4 extends out of
the carburetor 1 and is fitted with a throttle lever 6. At both
ends of the throttle lever 6 are oppositely mounted an r.p.m.
adjust screw 7 and an open-degree adjust screw 8 for the throttle
valve under deceleration. When the throttle valve 4 closes to the
opening degree in idling time, the tip of the r.p.m. adjust screw 7
is designed to hit a stopper 9.
Reference numeral 10 identifies a negative pressure take out
orifice for negative pressure lead. The orifice is located on the
upstream side of the throttle valve 4 when the throttle valve 4 is
open to the degree of idling time or less. It is located on the
downstream side of the throttle valve 4 when the throttle valve 4
is open to more than the degree of idling time.
Negative pressure take out orifice 11 provides negative pressure
lag. Orifice 11 is located on the downstream side of the throttle
valve 4 when the opening of the throttle valve 4 is equal to or
less than the opening in the idling time. It is located on the
upstream side of the throttle valve 4 when the opening of the
throttle valve 4 is more than the opening at idling time.
Rotatable arm 12 is pivoted to a shaft 13 connected to the
carburetor 1. At the left end of the arm a bent portion 14 is
provided and at the right end of the arm a return spring 15 is
fitted which moves the rotatable arm 12 in a counterclockwise
direction thereby bringing the left underside of the arm 12 into
contact with a stopper 16, as shown in FIG. 1. When the rotatable
arm or blocking structure is positioned as shown in FIG. 1 and the
throttle valve 4 begins to close, the valve ultimately reaches a
position slightly more open than at idling time. The tip of the
open-degree adjust screw 8 engages the bent portion 14 of the
blocking structure 12 to prevent further closing of the valve.
The right side of the rotatable arm 12, as viewed in FIGS. 1 and 2,
is hinged to the top end of a rod 17. The bottom end of the rod 17
is linked to a diaphragm 19 installed within a negative pressure
multiplier 18. When the negative pressure in the negative pressure
chamber 20 of the negative pressure multiplier 18 is low, the
rotatable arm 12 moves counterclockwise around a shaft 13 under the
force of a return spring. 15. The left underside of the rotatable
arm 12 then abuts the stopper 16, as illustrated in FIGS. 1 and 2.
When the negative pressure in the negative pressure chamber 20 is
high, the diaphragm 19 displaces downward to pull the rod 17 down
and move the rotatable arm 12 clockwise around the shaft 13 against
the force of the return spring 15. Such movement causes the bent
portion 14 of the rotatable arm 12 to assume its raised position,
as illustrated in FIG. 2. With the rotatable arm 12 in unblocking
position the throttle valve 4 can close the throttle opening since
the tip of the open-degree adjust screw 8 for the throttle valve
clears the bent portion 14 of the arm 12.
Reference numeral 21 identifies a car speed detector operated by a
speed meter drive cable 22 rotated by the wheels of an automobile.
The rotating force can be used to generate a voltage proportional
to the car speed. Reference numeral 23 identifies a car speed
setter which amplifies the voltage generated by the speed detector
and opens or closes a contact through a switching action. As shown
in FIG. 4, it comprises transistors, diodes, rectifiers,
resistances, capacitors and a coil. The speed detector 21 rotates
at r.p.m. proportional to the car speed to generate an AC voltage.
An AC current is full wave-rectified by the selenium-rectifier Se,
smoothed by the capacitor C.sub.1, thereby eliminating the
pulsation component, and an input voltage Vi is produced.
The input voltage Vi divided by the resistances R.sub.1 and R.sub.2
and as the result the potential at the point A becomes -V.sub.1,
which is negative with respect to the earth potential.
When an ignition key switch Ig-Sw is closed and while the
automobile operates at low speed, the potential at the point A is
approximately zero, and the potential at the point B becomes
positive on account of the Zener diode ZD.sub.1, thereby causing
the base current iB.sub.1 to flow the transistor Tr.sub.1.
Thereupon the potential at the point C, i.e., the collector
potential of the transistor Tr.sub.1 drops, becoming about equal to
the potential at the point D, i.e., the emitter potential of the
transistor Tr.sub.1. Accordingly, no current flowing in the
transistor Tr.sub.2, the coil L is not energized and the contact 24
is open.
When the automobile operates at high speed, the input voltage
V.sub.1 rises and in consequence the potential at the point A,
i.e., -V.sub.1 increases further to the negative side. Thus, the
potential at the point B turns negative, making it impossible for
the base current iB.sub.1 to flow in the transistor Tr.sub.1. The
collector current iC.sub.1 ceases to flow in the transistor
Tr.sub.1 and as the result the potential at the point C rises. The
potential at the point C is divided by the resistances R.sub.5,
R.sub.6 and R.sub.7. Since the base potential VB.sub.2 of the
transistor Tr.sub.2 is so set as to become higher than the emitter
potential Ve.sub.2 of Tr.sub.2 through division by R.sub.6 and
R.sub.7, in the transistor Tr.sub.2 the base current iB.sub.2
flows, and it is made continuous, so that the collector current
iC.sub.2 flows therein which energized the coil L to close the
contact 24, thereby energizing the electromagnetic coil 27. A
negative pressure change valve 25 comprises a housing 26 having
openings 31, 32, 33 and 34. Then the contact 24 of the car speed
setter 23 closes a magnet coil 27 is energized and a core 28 is
shifted to the right, as shown in FIG. 1. Such movement compresses
a return spring 29 and shifts a valve 30 to the right. In this
state, the opening 31 communicates with the opening 34 and the
opening 32 communicates with the opening 33.
When the contact 24 of the car speed setter 23 opens to deenergize
the coil 27, the return spring 29 moves the valve 30 to the left,
as illustrated in FIG. 2. The opening 31 communicates with the
opening 32 while the opening 33 communicates with the opening
34.
An air purifier 35 is located in the upstream end of the carburetor
1. An air supply opening 36 supplies air at atmospheric pressure to
the opening 33 in the negative pressure change valve 25.
A distributor 37 has a negative pressure lead device 38 and a
negative pressure lag device 39. The negative pressure lead device
38 communicates with the negative pressure takeout orifice 10 and
accelerates the engine ignition timing when a negative pressure
develops therein. The negative pressure lag device 39 communicates
with the opening 34 of the negative pressure change valve 25 and
delays the engine ignition timing when a negative pressure develops
therein.
The opening 31 of the negative pressure change valve 25
communicates with the negative pressure take out orifice 11 for the
negative pressure lag. The opening 32 communicates with the
negative pressure chamber 20 of the negative pressure multiplier
18.
The function of the device according to the present invention is as
follows. While the automobile operates at high speed the car speed
detector 21 generates a voltage value representative of the
automobile speed. When the speed exceeds a predetermined limit the
voltage value thus developed closes the contact 24 to thereby
energize the magnet coil 27. As a result, the valve 30 is shifted
to its right-hand position, as shown in FIG. 1. Then the negative
pressure take out orifice 11 for negative pressure lag communicates
with the negative pressure lag device 39 while the negative
pressure chamber 20 of the negative pressure multiplier 18
communicates with the air supply opening 36 of the air purifier 35
thereby venting it to the atmosphere.
When the negative pressure chamber 20 of the negative pressure
multiplier 18 is at atmospheric pressure the return spring 15
causes the rotatable arm 12 to move in a counterclockwise direction
until the left underside of the rotatable arm 12 hits the stopper
16, as shown in FIG. 1. When the engine is under a considerably
high load for accelerated or steady running the throttle valve 4,
as indicated in solid outline in FIG. 1, is held widely open. With
the negative pressure take out orifice 10 for negative pressure
lead located downstream from the throttle valve 4 a high negative
pressure is developed and transmitted to the negative pressure lead
device 38. The negative pressure take out orifice 11 for negative
pressure lag is upstream form the throttle valve 4 and no negative
pressure is developed. Accordingly, no negative pressure acts on
the negative pressure lag device 39. As a result, the ignition
timing on the distributor 37 is accelerated to meet the high speed
operation of the engine. A normal high speed running is thereby
guaranteed.
When the automobile decelerates from a high running speed the
throttle lever 6 and the throttle valve 4 rotate clockwise from the
position indicated in solid outline in FIG. 1. With the rotatable
arm 12 positioned as in FIG. 1, the tip of the deceleration valve
open-degree adjust screw 8 stops at the position indicated by
phantom in FIG. 1 where it contacts the bent portion 14 of the
rotatable arm 12. In this condition, the throttle valve 4 is
slightly more widely open than at idling time thereby permitting a
larger intake of air than in the conventional mechanism. This
prevents the discharge of unburnt hydrocarbons under
deceleration.
As described above, when the automobile decelerates the throttle
valve 4 is positioned as shown in phantom in FIG. 1. The negative
pressure take out orifice 10 for negative pressure lead is upstream
from the throttle valve 4 and in consequence only an
inconsequential negative pressure (-5 -10 mm. Hg) develops. The
negative pressure lead device 38 will not act. Meanwhile, the
negative pressure take out orifice 11 for negative pressure lag is
at that time downstream form the throttle valve 4. A high negative
pressure is developed which is transmitted to the negative pressure
lag device 39. Thus, with a high negative pressure transmitted to
the negative pressure lag device 39 the distributor 37
satisfactorily retards the ignition timing to produce a full engine
brake effect.
When the car speed drops below a certain limit, for example, 20
km./h., the voltage generated in the car speed detector 21 falls
below a certain value which operates to open the contact 24 of the
car speed setter 23 thereby deenergizing the magnet coil 27 and
moving the valve body 30 of the negative pressure change valve 25
to the left under the force of the return spring 29, as shown in
FIG. 2. In consequence, the negative pressure take out orifice 11
for negative pressure lag communicates with the negative pressure
chamber 20 of the negative pressure multiplier 18. The negative
pressure lag device 39 communicating with the air supply opening 36
of the air purifier 35 and is thereby vented to the atmosphere.
When the negative pressure take out orifice 11 for negative
pressure lag is far downstream from the throttle valve 4 a strong
negative pressure develops which is transmitted to the negative
pressure chamber 20 of the negative pressure multiplier 18.
Thereupon, the diaphragm 19 displaces downward to pull the rod 17
and move the rotatable arm 12 clockwise against the return spring
15 to the position of FIG. 2. The bent portion 14 of the rotatable
arm 12 is elevated to allow the tip of the deceleration value
open-degree adjust screw 8 to pass. The r.p.m. adjust screw 7 hits
the stopper 9 thereby enabling the throttle valve 4 to close to the
open degree in idling. In idling under this condition the negative
pressure take out orifice 10 for negative pressure lead is upstream
from the throttle valve 4. A very weak negative pressure (-5-10 mm.
Hg) is developed. The negative pressure lead device 38 does not
function whereby stable idling is guaranteed.
If in this condition the throttle valve 4 is slightly more open
than idling and the car speed is lower than a certain limit (for
example, 20 km./h.), in other words it is an extremely light load
low speed operation, a negative pressure corresponding to the open
degree of the throttle valve 4 develops at the negative pressure
take out orifice 10 for negative pressure lead. The negative
pressure lead device 38 then acts to accelerate the ignition timing
thereby assuring stabilized operation and economical fuel
consumption.
Thus, so long as the car speed is below a certain limit the open
degree of the throttle valve 4 and the ignition timing remain the
same as in a normal engine and the condition remains normal even
when the engine stops thereby assuring the low-temperature starting
characteristic.
At automobile speeds above a predetermined limit the contact 24
remains closed. As shown in FIG. 1, at decelerations from above the
predetermined speed limit the throttle valve 4 stops at a position
slightly more open than at idling thereby introducing enough air to
reduce the unburnt hydrocarbons. The volume of residual
hydrocarbons in the exhaust gas diminishes while the loss in the
engine brake effect is compensated for by sufficient delay of
ignition timing to guarantee deceleration.
As the car steadily slows down to less than the predetermined speed
limit the contact 24 opens and the rotatable arm 12 moves to its
unblocking position. The throttle valve 4 then closes to the open
degree at idling timing thereby assuring a common very light load
low speed operation or idling.
The throttle lever 6 illustrated in FIGS. 1 and 2 may have the
r.p.m. adjust screw 7 and the deceleration throttle open-degree
adjust screw 8 attached on the same side, such as the side that
presently carries the r.p.m. adjust screw 7. Alternatively, as
illustrated in FIG. 3, only the r.p.m. adjust screw 7 can be
attached with the open-degree adjust screw 8 omitted and with the
end 40 of the rod 17 connected to the diaphragm 19 of the negative
pressure multiplier 18. The end 40 is movable between the r.p.m.
adjust screw 7 and the stopper 9. Under high speed operation and
deceleration the negative pressure chamber 20 is at atmospheric
pressure and the end 40 of the rod 17 is between the r.p.m. adjust
screw 7 and the stopper 9 thereby preventing the throttle valve 4
from closing further than a slightly more open position than at
idling. Under low speed operation the rod 17 elevates the end 40
away from between the screw 7 and stopper 9 which allows the
throttle valve 4 to close to its idling position.
In the negative pressure multiplier 18, instead of the diaphragm 19
illustrated, a cylinder-plunger combination or a bellows may be
employed. The negative pressure is utilized for a mechanical
displacement of the arm 12 but it may be utilized to switch an
electrical contact to energize pr deenergize a magnet the core of
which is adopted to displace the arm connected therewith.
Just like an automobile equipped with an automatic speed change
gear when the engine r.p.m. and the car speed are relatively
proportional the engine r.p.m. may be used to operate the car speed
detector 21. Also, the contact 24 may be designed to energize the
magnet coil 27 under low speed operation and deenergize the coil 27
at high speed so that the valve 30 can be switched under the force
of the spring 29.
Thus, according to the present invention, under low speed operation
of the car engine the throttle valve 4 can be held slightly more
open than at idling thereby permitting an ample intake of fresh air
and accordingly reducing the discharge of unburnt hydrocarbons
resulting in a less polluted atmosphere.
The opening degree of the throttle valve 4 under deceleration is
controlled by the positioning mechanism driven by such a device as
the negative pressure multiplier 18 which is designed to limit the
opening of the throttle valve 4 to a position slightly wider than
at idling when the car speed before initiation of deceleration is
above a certain speed limit. Therefore, at the same time as the
initiation of deceleration the opening of the throttle valve can be
set to a position slightly wider than in idling and an effective
deceleration in a very short time can be made in the same manner as
when the step on the accelerator pedal is temporarily softened for
speed change.
Meanwhile, the opening of the throttle valve 4 under deceleration
can be instantly set to a definite position by the positioning
mechanism with very simplified controls and without any "hunting"
or error.
Moreover, the delay of ignition timing for deceleration prevents
the engine brake effect from being reduced through a slightly wider
opening of the throttle valve 4.
* * * * *