US1847732A - Charge forming device - Google Patents

Description

March 1, 1932. w. HTEETER 1,847,732

CHARGE FORMING DEVICE Filed Oct. l5, 1928 2 Sheets-Sheet l 0 anw M m M 1 l 7 l w M o J Z 4 m w 2 z 28o/o /20 7 22 .4/ O 7- u @M 4 b 5 K M 0 2 8 H- HH A w a w 4 ww 5 n 4l ./0 Y 4/ M uw ,aM/o hun... HHH@ M 40 5 426 l/Prd7 533` Mmm a a Mm H M Z8 ,n .uw a mw M 1 a, v y 8). U......l....|.....|. l M. H 4 A e .0)1 3 5 W s 4 2 44@ 2 March l, 1932. w. H. TEETER 1,847,732

CHARGE FORMING DEVICE Filed Oct. l5, 1928 2 Sheets-Sheet 2 O"Ill Patented Mar. 1, 1932 UNITED STATES 'PATENT oFElc-E WILFOBD H. OF DAYTON, OHIO, ASSIGNOB., BY ASSIGNMENTS, TO DELCO PRODUCTS CORPORATION, F DAYTON, OHIO, A CORPORATION OF DELAWARE CHARGE FOBHING- DEVICE .Application led October 15, 1928. Serial No. $12,510.

This invention relates to charge forming devices for internal combustion engines and more particularly to that type of charge forming device which comprises a plurality of primary mixing chambers, one for each intake port of the engine, having a commonl source of fuel supply and cooperating respectively with a plurality of secondary mlxing chambers, each located adjacent an engine intake port, each of said secondary mlxlng chambers receiving primary fuel mixture from one of the primary mixing chambers and receiving additional air through an air manifold which supplies air to all the secondary mixing chambers.

Examples of this type of charge forming device are disclosed in the prior application of Fred E. Aseltine, Serial No. 83,979, filed January 26, 1926, andthe Patent of Fred E. Ascltine and Wilford H. Teeter, No.`

In devices of this character heretofore,

known, as for example those shown in the above mentioned applications, means are provided to enrich the mixture on opening movements of the throttle to supply a mixture of the proper proportions to most satisfactorily operate the engine during the acceleration period. Ity has been found that ya leanenmixture is desirable during the acceleration period when the engine is hot than when said engine is cold and the principal object of the present invention is to provide means for enriching the mixture on opening movements of the throttle to supply the desired mixture =for acceleration and to provide thermally responsive means for. controlling said mixture enriching means so that the latter is effective to supply a richer mixture nwhen the engine `is cold than when said engine l-is relatively warm.

More speciically, it is an object of the present invention to provide means for retarding the opening of the air valve-during opening movements of the throttle to enrich the mixture for acceleration and to provide thermally responsive means for controlling the operation of said retarding means.

According to the present invention, these objects are accomplished by the provision of a dash ot for retarding the opening movement oft e air valve provided with a movable cylinder which is moved by the throttle the retarding effect of said dash pot as the throttle is opened and thermally responslve means is provided associated with the cylinder of said dash pot to regulate the escape .during its opening movement to increase Y the engine is cold, either in cold weather or vwhen 1t is first started, the valve is held closed or nearly closed by the thermo/static element, but as the engine warms up after running for any appreciable time, or when' the weather 'is hot, the valve is adapted to be opened to a greater degree by said thermostatic element to permit flel to esca from the dash valve isl opened.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings wherein a preferred embodiment of one form of the present invention is clearly shown.

In the drawings:

Fig. 1 is a vertical longitudinal section through -a charge forming device in which the present invention is embodied.

Figs. 2 and 3 are detail sections on the lines 2-2 and 3 3 of Fig. 1':

Figure 4 is a side elevation of the carburetor unit, showing the mechanism for operating the dash pot cylinder.

Figures 5 and 6 are detail views of this mechanism. The reference numeral 10 indicates an air pot more rapidly as the a1r d manifold which is provided with three outlet y.

attaching Bange '14 adapted to be secured to 1W the engine block in the conventional manner.

49 described in detail in this application.

. 55 'ping of said column of fuel.

The air manifold has secured to the lower side thereof by any suitable means, a frame 16 supporting a constant level fuel chamber 18 attached to said frame by screws 20. Fuel is conducted to said fuel chamber through a conduit, which is not disclosed herein and the flow of fuel to said chamber is controlled by a oat 22 operating in the usual manner.

A distributor block 24 is secured to the upper side of the air manifold in any desirable way and said distributor block has a plurality of primary mixing chambers 26 formed therein, as indicated in the drawings. The specific construction of the distributor block and the means for conveying the fuel mixture formed therein to the secondary mixing chambers will be described later.

To conduct fuel from the fuel chamber 18 to the distributor block there is provided a tube 28 screwed into a passage 30 formed in the wall of the air manifold. Tube 28 extends downwardly into the fuel chamber to ceived in the passage 30 is a sleeve 34 partly closed at its lower end and open at its upper end, an orifice 35 being formed in the lower end of said sleeve to provide a valve seat with which asuction operated valve 36 received in said sleeve cooperated. This valve forms a two-stage metering Valve which is illustrated in detail and fully described in the above mentioned patent and need not be Seated on top of the sleeve 34 is a check valve 38 which prevents the fuel in the tube 28 flowing back toward the fuel chamber. It has been found that under certain conditions of operation, as for instance when the engine speed is suddenly reduced, the resulting reduction in suction on the column of fuel between the fuel chamber and the primary mixing chambers would permit this column to drop suiiiciently to cause a temporary fuel starving of the engine unless means were provided to prevent such an occurrence, and it is the function of the above mentioned check valve to prevent the drop- The upward movement of the check valve is limited by fingers 40 projecting from a sheet metal collar 41 received in an enlargement in the passage 30.

The lowerface of the distributor block is provided with a groove 42 which constitutes a fuel distributing canal and conducts liquid fuelfrom the passage 30 to each of the primary mixing chambers above referred to. A removable fuel metering plug 44r conducts fuel from the canal to each of the primary mixture passages, as indicated in Fig. 2 and an air inlet bushing 46 admits air to each of the primary mixture passages adjacent said metering plugs, as shown in Fig. 3. In so far as the present invention is concerned, the specific formation of these air inlet bushings is not material and reference is made, therefore, to Patent No. 1,762,463 for a more detailed description.

To secure equalization of pressure in the various primary mixing chambers, a passage 48 is provided to place all of said chambers in communication with each other. This passage is inthe form of a groove or channel cut in the bottom face of a plate 50 secured in any suitable manner to the upper face of the distributorblock. The passage 48 communicates with each primary mixture passage through holes 52 bored in the top of said distributor block. 'Each primary mixture passage is connected with one of the branches of the main air manifold by a conduit, this construction being fully shown and described in the above mentioned patent and forming no part of the present invention. The passage connecting the primary mixture passage with the branch 12 of the air manifold is disclosed herein and comprises a vertical bore 54 formed in the distributor-block which registers with a bore 56 in the wall of the manifoldbranch 12.

The construction of the secondary carburetors is identical, and that which is located in the branch 12 of the manifold is shown in the Fig. 1. A large Venturi tube 60 is held in position in the manifold by means of a set screw 62, the tapered end of which cooperates with a recess 64 in the outer surface of the venturi. The venturi is provided with a channel 66 in its outer surface which registers with the bore 56 above referred to and a slot 68 in the wall of the venturi at the point of the greatest depression therein permits passage of the primary mixture from the channel 66 to the interior of said Venturi` tube. The rich mixture entering the venturi through said slot is mixed with additional air and the resultant mixture is drawn into the engine by the suction therein, the flo-w of said mixture being controlled by a throttle valve 70 secured to a shaft 72. Each outlet branch of the manifold is provided with a Venturi tube and throttle, the throttles being operated simultaneously by a mechanism fully described in the copending application above referred to.

lVhen the throttles 70 are only partially opened, there is but a small quantity of air flowing through each manifold branch at relatively low velocity. Because of the low velocity of air flow there is a tendency for fuel particles to settle with out the fuel mixture and collect on the manifold wall resultingin uneven fuel distribution. To overj come this tendency each branch of the manifold is provided with an automatic restrictmg valve which opens in accordance with the velocity of the entering air and causes the entering mixture to pass said valve at relatively high velocity under all operating conditions. Each of said valves is mounted in a sleeve 74 inserted in the manifold branch and extending into the engine intake port when the device is assembled. The sleeve 74 is held in place by means of ears 76 cut out of the wall of said sleeve, the ears being'clamped between the manifold and the engine when the manifold is attached thereto. The sleeve 74 is provided with a transverse pin 78 on which two Hat valves 80 are pivoted.y These valves are urged toward closed position by a spring 82 which is connected to the valve as indicated in Fig. 1. The lower wall of the'sleeve is provided with a projecting lip 84 which is held back in the sleeve as shown in Fig. 1, forming a space between said lip and the lower wall of the sleeve. Holes 85 are provided toconnect the space between the lip and the sleeve with the intake passage and to permit passage of the fuel mixture for idling when the valves 80 are closed, and also to enable any fuel which-precipitates from the fuel mixture to flow back into the mixture stream to be re-atomized.

To admit air to the air manifold 'an air inlet horn 90 is secured in any suitable way to to the upper wall of the manifold casting over an opening 92 in the said wall. The flow of air is controlled by valve 94 normally held against its seat 96 by a spring 98 received between the valve and a flange 100 projecting from the lower en'd of a sleeve 102 which is slidably mounted on a stationary guide sleeve 104 supported by a spider 106 secured by screws 108 to the air horn. The

guide sleeve limits the opening movement of'the air valve and the slidable sleeve is adapted to be raised by amechanism not illustrated herein to a position where its upper end engages theair valve to hold said valve closed when it is desired to choke the engine to facilitate starting. In order to enable the parts to vbe assembled, the bottom Wall of the manifold is provided with an opening 110 which is adapted to be closed when the device is assembled by a packin washer 112 secured to a metal plate 1,14 fixe in the lower end of the guide` sleeve.

To enrich the fuel mixture for acceleration and to prevent fluttering of the air valve on opening movements of the throttle the opening of said valve is retarded by a liquid dash pot as shown in Fig. 1. This dash pot comprises a cylinder 120 slidably received in a guide 122 cast integral with the frame 16. Holes 124 and 126 are provided in the guide end cylinder respectively below the fuel level in the ioat chamber, said holes registering with each other when the cylinder is in its normal lowered position to permit passage of the liquid fuel from the fioat chamber to the interior of the dash pot cylinder. The cylinder is adapted to be lifted to increase the retarding effect of the dash pot by means which will be described presently.

Cooperating with the cylinder is a piston 128 mounted on the lower end of the air valve stem 130 in the manner described in the above mentioned copending applications. A bypass 132 comprising a pipe secured in the wall of the cylinder 120 has its upper end normally covered by the dash pot piston but is uncovered during downward motion. of said piston to permit passage of the fuel from the lower end of the cylinder around the piston and partially relieve the retarding action of the dash pot when the air valve is partially open. j

When the throttles are opened to accelerate the engine and increase the speed of the vehicle, the manifold suction is communicated to the lower side of the air valve and is effective to open said valve and move the dash pot piston downward. The retarding effect of the dash pot greatly diminishes as the piston moves downwardly and the bypass is being uncovered. The relation of the by-pass to the piston determines the diminution of the retarding effect on the opening movement of the air valve, and this reduction is varied automatically according to the position of the throttle. The greater the initial opening of the throttles at the time they are further opened to increase the speed, the less will be the retarding action. This variation is necessary because less retarding of the air valve would be required when accelerating from a 20 to a 25 mile per hour speed than from a 10 to 25 mile per hour speed, assumvided with a flange 140 which is adapted to be engaged by pins 142 projecting inwardly from eachof the arms 144 of a bifurcated lever secured to the rock shaft 146, which is operated by means fully disclosed in the above mentioned patent, to lift the cylinder on opening` movement of the throttle. The means Ifor lifting the dash pot cylinder through the medium of the throttle includes, briefly, an arm 145 secured by a clamp or in any other suitable way to the tube 72 to which the throttle is fixed. Pivoted on a pin 147 projecting from said arm is an arm 149 having a cam slot 151 therein, the position of said cam slot relative to the arm 145 being controlled by a set screw 153 threaded in a gaging arm 149. The cam slot engages a pin 157 in the end of arm 159 pivoted on the rock shaft 146 outside the housing. Projecting from the arm 159 is a lug 161 in which a screw 163 is threaded. This screw has a reduced portion extending through a hole in the end of an arm 165 secured to the shaft 146, while a spring 167 surrounds the reduced part of the screw between the lug 161 and arm 165. Obviously as the throttle is opened the cam slot through the medium of pin 157 rocks the arm 159 downwardly compressing the spring 157 and through arm 165 rocking the shaft 146 to lift the dash pot cylinder as described. The lifting of the cylinder as described will increase the resistance to the downward motion of the piston and has been found desirable because when the throttle is opened slowly the downward movement of the piston is slow and there is so much leakage of fuel past the piston that the retarding effect of the dash pot on the opening movement of the air valve is largely eliminated. When the cylinder is moved upwardly simultaneously with the downward movement of the piston, however, it tends to displace more fuel than can escape by leakage and retards the opening movement of the air valve to the extent desired.

Retarding of the opening of the air valve forms a richer than normal mixture for acceleration for two reasons. First, of course the amount of air entering the carburetor is reduced, decreasing the-'proportion of air in the mixture. Also the difference in pressure between the ends of the primary mixture conduits is increased resulting in greater suction at the jets, greater fuel flow, and a reduced interval of time required to convey the enriched primary mixture of the secondary mixing chambers. The mechanism described inthe foregoing pages and the function thereof is all described in full detail in the above mentioned patent. Y

As has been stated previously, it has been found desirable to control the retarding effect of the dash pot in accordance with the temperature of the engine and to accomplish this result the lower end of the dash pot is provided with a hole 150 which is normally closed by a valve 152 supported by a bi-metallic, thermostatic element 154 in the form of a U- shaped flat spring, which is received on a pin. 156 projecting from a lug 158 which may be either cast with the bottom of the dash pot or secured thereto in any desirable manner. The thermostatic element 154 is received between the lower end of said dash pot and an adjusting screw 160 threaded in an arm 162 projecting from the dash pot, -said screw being adapted to engage one of the ends of the U- shaped member. By variably adjusting said screw, the pressure exerted by the thermostatic member 154 on the valve 152 mav be controlled as desired and the normal position of the valve may be regulated. It will be ob- `ber into which ing the fuel to escape from the dash pot more rapidly as the piston descends. This reduces the retarding effect of the dash pot and allows the air valve to open more rapidly, admitting a greater quantity of air to the mixing chambers per unit of time and forming a leaner mixture than when the valve 152 is closed. While the above described thermally responsive valve is particularly desirable in the form of charge forming device shown herein, its application is in no way limited and it may be employed in any carburetor or in any dash pot per se in which it may be found desirable.

Also when the valve is in its closed or nearly closed position and the opening of the air valve is retarded as much as possible the pressure differential between the ends of the primary mixture conduits is increased and the suction at the jets is increased resulting in the formation of a richer primary mixture than when the valve is open and av reduction in the time interval required to convey said mixture to the secondary mixing chambers, resulting in better acceleration when the engine is relatively cold.

While the form of embodiment of the present invention as herein disclosed, constitutes a preferred form, it is to be understood that other forms might be adapted, all coming within the scope of the claims which follow.

Vhat isy claimed is as follows:

1. A charge forming device for internal combustion engines comprising a primary mixture passage, means for supplying fuel and air thereto, a secondary mixing chamber into which said primary mixture passage delivers, an air valve regulating the flow of air into the mixing chamber, means for retarding the opening of said valve and thermally responsive means for controlling the effect of said retarding means.

2. A charge forming .device for internal combustion engines comprising a primary mixture passage, means for supplying fuel and air thereto, a secondary mixing chamsaid primary mixture passage delivers, an air valve regulating the flow of air into the mixing chamber, means for retarding the opening of said valve, means operated by the throttle for varying the effect of said retarding means, and thermally responsive means for varying the effect of said retarding means.

3. A charge forming device for internal combustion engines comprising a primary mixture passage, means for supplying fuel andsair thereto, a secondary mixing chamber into which said primary mixture passage delivers, an air valve regulating the iow of air into the mixing chamber, means for retarding the opening of said air valve, means for increasing the retarding elfect of said means as the throttle is opened and thermally responsive means for controlling the retarding effect of said means.

' 4. A charge forming device for internal combustion engines comprising a primary mixture passage, means for supplying fuel and air thereto, a secondary mixing chamber into which said primary mixture passage de-l livers, an air valve regulating the liow of air -into the mixing chamber, a dash pot for retarding the opening `of the air valve, means operated by the throttle for varying the resistance of the dash pot and thermally responsive means for varying the resistance of the dash pot.

5. A charge forming device for internal combustion engines comprising a primary mixture passage, means for supplying fuel and air thereto, a secondary mixing chamber into which said primarymixture passage delivers, anV air valve regulating the flow of air into the mixing chamber, a dash pot for retarding the opening of the air valve, means for increasing the resistance of the dash pot as the throttle is opened and thermally responsive means simultaneously effective to control the resistance of the dash pot.

6. A charge forming devicefor internal combustion engines comprising a primary mixture passage, means for supplying fuel and air thereto, a secondary mixing chamber into which said primary mixture passage delivers, an air valve regulating the flow of air into the mixing chamber, a dash pot having a movable cylinder and piston for retarding the openin of the air valve, means operated by the t lrottle for lifting the cylinder to increase the resistancevof the dash pot and thermally responsive means effective throughout the movement of said cylinder for varying the resistance of said dash pot.

7. A charge forming device for internal s combustion engines comprising a primary mixture passage, means for supplying fuel and air thereto, a secondary mixing chamber into which said primary mixture passage delivers, an air valve re ulating the lloW of a1r into the mixing cham r, a dash pot having a movable cylinder and piston for retarding the opening of the air valve, means operated by the throttle for lifting the cylinder to ine crease the resistance of the dash pot and thermally responsive means carried by said cylinder and elfective in any position of said cylinder to vary the resistance of said dash ot. v P 8. A charge forming device for internal combustionengines comprising a primary and air thereto, a seconda mixing chamber into which said 1primary mixture passage delivers, an air va ve regulatin the iow of air into the mixing chamber, a 'quid dash pot for ret-arding the opening of the air valve, a valve `for controlling escape of liquid from said dash pot and thermally responsive' means i for positioning said valve. a

9. A charge forming device for internal combustion engines comprising a 'primary mixture passage, means for supplying fuel and air thereto, a secondary mixing chamber into which said primary mixture passage delivers, an air valve regulating the ilow of air into the mixing chamber, a liquid dash pot for retarding the opening of the air valve, a valve for controlling escape' of liquid from said dash pot, thermally responslve means for positioning said valve and means'for regulating the action of the thermally responsive means.

10. A charge forming device for multicylinder internal combustion engines comprising a plurality of primary mixture passages, a plurality of secondary mixing chambers into which said passages deliver, means for supplying fuel .and air to said mixture passages, an air valve controlling admission of air to all of said secondary mixing chambers, means for retarding the opening of said air valve to increase the suction in all of said mixture pas sages to enrich the mixture for acceleration, and thermally responsive means controlling the effect of said retarding means.

1l. In a carbureter having a suction op- 10o erated air valve, a dash pot for controlling said air valve comprising a cylinder and a piston movable therein, means admitting liquid to said cylinder and thermally responsive means controlling the escape of liquid from 105 said cylinder whereby the resistance of said dash pot may be regulated.

12. In a carbureter having a suction operated air valve dash pot for controlling said air valve comprising a cylinder and a. piston 110 movable therein, means admitting liquid to saidY cylinder and thermally responsive' means controlling the escape of liquid from said cylinder comprising a thermostatic element sup- R ported on said cylinder and a valve carried mixture passage, means for supplying fuel CERTIFICATI; 0F CORRECTION.

Patent No. 1,847,732( March 1, 1932.

i wlLFoRD H. TEETER.

lt is hereby certified that error appears in the printed specification ofthe above numbered patent requiring correction as follows: Page 5, line 109, claim l2,4 after "valve" insert the Comma and article a"; and that the said Letters Patent should be read with this correction therein that vthe same may conform to the record ofv the case in the Patent Office.

Signed and sealed this 7th day of February, A. D. 1933.

M. J. Moore, (Seal) 3 Acting Commissioner of Patents.

Images