Note: Descriptions are shown in the official language in which they were submitted.
7~3
This invention relates to a constant idle control
mechanism which controls the idle speed of a vehicle engine
as a function of the load on the engine, as measured by the
magnitude of the engine manifold vacuum.
To achieve maximum fuel economy, and also to control
vehicle engine emissions, it is ve:ry desirable to set the
engine idle speed as low as possible, while insuring that the
engine runs smoothly and does not stall. Accordingly, idle
control mechanisms have been proposed which actuate the
butterfly valve of the engine carburetor as a function of
engine manifold vacuum, to thereby set engine idle speed as
a function of the engine manifold vacuum, which is a measure
of the load on the engine. ~lowever, these prior art devices
have not been entirely satisfactory, because the strength of
the various vehicle components, such as the throttle return
springs, which also act directly on the butterfly valve
of the vehicle carburetor, have a tendency to change over
a period of time and also have a tendency to change in response
to ambient temperature conditions. Accordingly, these prior
art constant idle control mechanisms cannot control as a
function of load on the vehicle engine alone, and thus
cannot maintain a constant engine idle speed regardless of
the engine loading.
The present invention resides in a control mechanism
which incorporates a housing defining a pressure chamber
therein with means for communicatiny first and second pressure
signals into the pressure housing. A plunger is slidably
mounted in the pressure chamber and extends from the housing.
Fluid pressure responsive means is movable within the pressure
chamber in response to the pressure differential between
the first and second pressure signals. Fluid motor means
is operated by the fluid pressure and is operatively connected to
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the plunger for moving the latter. Means is responsive
to the fluid pressure responsive means for controlling
the fluid pressure level operating the fluid motor.
The fluid motor means includes piston means
slidably mounted in the pressure chamber, and the
communicating means includes means communicating one
of the pressure signals to one side of the piston means
and the other pressure signal to the other side of the
piston means.
An object of an embodiment of our invention is
to provide a constant idle control mechanism which is
capable of maintaining a constant engine idle speed
regardless of the loading of the vehicle engine.
Another object bf an embodiment of our invention
is to provide a constant idle control mechanism which
maintains a constant engine idle speed regardless of the
variations in the forces applied to the mechanism.
Still another ob~ect of an embodiment of our
invention is to provide a constant idle control mechanism
which maintains constant engine idle speed regardless
of the changes in the force characteristics of the
engine throttle return springs.
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Still another impor~ant o~ject of our in~ention is to provide a
control valve mechani~m in which a vacuLlm sensitive diaphr~gm controls a fluid
motor which does not exert any ]oad on the vacuum sensitive dlaphrasm, yet
provides an output force sufficlent to cor.trol the bLJtterfly valve of the
vehicle engine carburetor.
DESCRIPTION OF TtiE DRA~INGS
The sole Figure of the drawing is a longitudi,nal cros~-sectior.al
view of a constant idle control valve me-hanism made pursuant to the ~eaeh~
ings of our present invention.
DETAILE~ DESCRIPTION OF THE DRAWINGS
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Referring now to the drawing~ a constant idle speed cor,trol
mechanism generall~ indicated by the nurneral lG includes a housing 12
defining a pressure chamber Tndicated generally by the numeral 14 there-
with~n. Housiing 12 also defines a bore 16 which slidably re.-eives an
output plunger 18, one end 20 of which exter;ds fro,~ the bore 16. rhe ~nd
20 of the plunger 18 is connected to a conventional butterfly val~e or a
vehicle carburetor (not shown) and moves in the d~rection tndicated by the
arrow "A" to-increase idle speed and in the reve.se dire_tion to reduc~
idle speed.
A pair of transversely extending, eoaxial diaphragm members
generally indicated by the numerals 22 and 24 separate ~he pres;ure chamber
14 into a first chamber 26 defined between the upper edge (viewing ~he
Fisure) of the diaphragm`22 and the corresponding end 28 of the howsing 12,
a second chamber 30 between the diaphragms 22, 24; and a third ch3mber 32
defined bet~een the diarhragm 24 and the lowsr end 34 of the housing 12. A
spring 36 carried in the First chamber 2~ ~xtends bet~ eIl .ne uppcr ~dge of
the diaphra~m 22 and 3 spring retainer 3~ Ihe posItlon o~ the spring
rPtainer 38 is controlled by an adjusting scrc~ 40, so that the fGrce that
the spring 36 eY~erts on the di3phragm 22 can h~ adjusted. As can ~e seen
in the drawingJ the spri!l9 36 yieldabiy ur3es tha diaDhra5,m 2? d^wn~rdly
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viewing the Figure, towa ds the plungeF 18.
The diaphragm 22 comprises a pair of plates 42, 44 which are secured
together. The plates 42, ~4 clamp an annular bead !~6 theret,etween. The annulaf
bead 46 circumscribes the inner periphery of a f1exible ruhber member 48, and
sirnilcir annular beads 50, 51 on the outer periphery of the member 48 are
sealingly secured to the wall of the housing 12. Similarly, the lower diaphragm
24 comprises a pair of plates 52, 54 which are secured together. The plates
52 and 54 clamp an annular bead 5i6 therebetween. The bead 56 cirsumscribes
the inner periphery of another rubber member 58, which is also provided with
beads 60, 61 on the outer periphery thereof which are ssalingly attached to the
wall of the housing 12. An annular, expandable filter material 62 (such as
foam rubber) is disposed between the plates 44 and 52, and serves to ;ilter
ambient atmospheric air which is communicated into the chamber 30 through the
inlet port 64. Another inlet member 66 is communicated to engine manifold
vacuum, and defines a passage 68 therewithin which splits into a pair or
~ranches 70, 7? to communicate engine manifold vacuum both into the upper
chamber 2~, and to the lcwer chamber 32.
An annular spring retainer 74 is carried by the plunger 18 within
~he chamber 32. A spring 76 extends between the bottom wall 34 of the housing
12 and the spring retainer 74, to thereby yieldably exert an upwarcily directed
force (viewing the Figure) on the plunger 18. Furtharmore, ~he atoremen~ioned
throttle return springs (not shown) also 3ct on the plunger 18 when the valve
mechanism 10 is installed on a veh1cle, and supplement the spring 7~ in ursing
the plunger 18 upwardly viewing the Figure. However, the sum of the forcss
exerted by this spring 76 and by the aforementioned throttle return sprlngs
~not shown) Is less than the force exerted by the spring 3~.
The upper p!ate 42 of the ciiaphr3gm 22 is provided with a r3ised
porrion 73 which slidablv receives a valve merniber 80. A spring 82 is disposed
between the valve mernber 80 and the raised portion 78, and yisldably urges the
valve member 8~ downwardly vi~wing the Figure. The ~ower plate 44 c,f the
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diaphragm 22 ~!erines a coaxial opening 84 theroln, but the diameter of the
opening 84 is less than the dia~leter of the valve miem~er 80, so that th_ spring
82 is capable of urging the valYe member 80 into ellgagement ~ith the ;~ripheral
porticn 86 of the plate 44, which thereby serves as a stop for the valv. member
80. The upper diaphragm plate 52 of the diaphras.~ 21. is alsc provlded Witil 3
.aised portion 88 haviny a peripheral portion ao wilich is adapteri tv engage ~h2
portion 86 of the plate 4~1, and is also p,ovided wi~h a dimple 32 whicn is
adap~ed to project through ths opening 84 and to engage the valve rnember 80,
raisi,ng the latter off the portion 86 in opposition to the fo.ce a~;erted b~/
10 the spring 82. An opening 94 is provided in the portion 92, whi~.. h co:r,rmir.ic~;~e.
the chamber 30 ~ith the chamber 32 through the opening 94, and a co!r.sponding
aperture 96 provided in the lower pl3te 54 Orr the Glapnrasm 24
MOD~ OF OPERATION OF THE INVEl'ir!ON
The v3rio~:s components of the constant idle control la, lO 3re
illustrated in the Figure in the position which they assume when ~he vehicle
en~ine is not operating. !n this condition, the chambars 26, 3û and 37 ~re
all at substantially atr,ospheric pressure. Therefore, the sprirg 3b urges the
dia,chragm 22 into engdgemen~ with t.he ~iaphragm 24 and urges the dieiph.~sms
22 and 24 as a unit 3sainst the ~Ipper ~nd of the plunger 18, tnereby urginy
20 tre spriing retaine~ 74 on the plunger 13 tnto engagement ~ittl ~ha stop 9~ on
the housins 1' wriich defines the maximum extended position or the plunger 18,
which corresponds to maxirrium opening of ~he c~rturetor butterfly valve. '~lhen
tne vehicle engine is started, manifold vacu im is comm~nicated tr.tc the
chambe s 26 and 32. 'Alhen t'-is occurs, the diaphragm 22 moYes up~ardly
~fie~.~Jin~ the Flgure~ in opposition to the spri,n3 36. As the diaphraym 22
moves, the valve merrber 80 will be moved out of sealing enga(3enlent w!th
~e o. i '~ice ~4, ard the r.~er jpherc,i eclgas of the. l~tt~r wil 1 e.nga3~ th~
peripheral pGrt,on ~ cf thiQ opening ~i Acco^dingly, since r.hc valve
membar 8û is move~ o~lt o; engaSement witil .:he or;f 1ce ~4, a~mospher ic ai r
30 is corrmunicared from the chamter 'C into tha ch~mber 37, there~y reduciny
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the v3cuum level ln ~h_ cIaamber 32, Whon tnis occurs, of ccurse, ~he
pressure diffeIenti31 across the di2phragm 24 is reduced, thereby permitting
the spring 76 and the aforemerttioned ~hrottle return spIirlgs (not ahown)
acting on the plunger 13 to m~ve the la~ter and .he diaphragm 24 wpwardly
viewing the Flgure. The diaphragm 24 will -move into a positio~ so that
the opening 94 cooperates with the valve meinber ~d to define a bleed orifice
therebetween, thereby permitting just enough ~mbient ~tmospheric pressure
to comm~nicate into the charr.ber 32 so ~hat the di~phragm 24 remains in a
steady state position. !f the engine ioading condition should change, for
13 exarrIple~ to increase the ensine manifold vacuum level, as occurs when the
venicle engine loadi~g is reduced, the ir.creased vacuum level communicated
into ~he chamber 26 wi!l cau,e tha diaphragrr 22 to move upwardly viewing
Figure 1. Of course, tne blead orifice betw~en tne ~pening 94 and thn
valve member 80 will then be increased, .hereby comm-lnicating an incre3sed
a~ount o, ambient at~ospheric air through the opening 94 in~o the :harr~er
32, to reduce the pressure differen~ial across the diaphragM 24. When
this occurs, the spring 76 and the aforem~ntioned throttle return springs
(not shown) move the plunger and ~he diaphragm 24 upwardly, there~y ~ecreasinS
the carburetor outterfly val~e opening to maintain constant idle speed
to correspond to the reduced load on the vehicle engine. If, on the other
hand, the load on the ~ehicle engine should increase, ~hereby reductng the
engine manifold vacuum levQl, the reduced manifold vacuum level communicated
into the chamber 26 will permit the spring 36 to urge the diaphra~m 22 down-
ward1y viewing the Figure, thereby permttting the va!ve membeI ~0 to seal of.f'
the crifice 94, to terminata an~f communic3tion of ambisrlt atm3sphertc air
from the chamber 3L~ into the c~mker 32. There~ore, the ~aclIuM le~ol tn the
chamber 32 will increase, there~y sut'in3 ~he diaphr39~ 24 down~3rdl;f ~.le~.ir:g
the Fi~re, against the ot~position ~f the spring 7O and the ~ir~rem-ntionLad
thro~.~le return sprir,gs ~nGt ~hown). A&cordingly, the plunger 1~ is then
extended from tne hGu;ir,n 1~ tn tlLe directiorl ~f .he~ arrow ~h~I r.c~ increa.;e
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butterly v21YP opening to mainta~n a constant engine Idle speed with increased
loaa. Conseauen ly, ~he engine idle speed is held constant at high maniFold
vacuum levels, because the engine, at its reduced loading, can idle with 3
reduced butterfly opening. Conversely, when engine loading increases,
~hereby reducing the engine maniCold vacuùm~ the butterfly v~lve is opened~
so that the engine will still idle at a constant idle even though the
vehicle engine loadir.g has increased.
It will also be noted that the iower diapnragm 24 follows ~he upper
diapnragm 22, but does not exert any 10ad on tt. Accordingly, the upp~r
lU diaphragm 22 is res?onsive solely to er,gine manifold v~cuum, and is not af'ected
by ,he fcrce or the plunger 18J since there is no direct connection between
the plunger 18 and the diaphragm 2?.. Accordinglyj the diaphragm 24 acts as a
fluid motor, communication across which is controlled by the valve member 8G
and the ori;ice 94, ta thereby control movement of the lower di~phragm 24 as
a function of the movement of the upper diaphr3gm 22. There-fore, the engine
idle speed set sy the idle controller 10 will be solely a function of ';he
enaine maniroid vacuum.
