US1926021A - Charge forming device - Google Patents

Description

. 12, 1933. F. E. ASELTINE CHARGE FORMING DEVICE Filed May 25, 1930 2 Sheets-Sheet ,jwuentoz 03%; L. A

881 E VQWKMM (lttozmq l atentecl Sept. 12, I933 PATENT CHARGE FORMING DEVICE Fred E. Aseltine, Dayton, Uhio, assignor to Delco Products Corporation, Dayton, Ohio, a corporation of Delaware Application May 23, 1930. Serial No. 454,913

6 Claims.

This invention relates to charge forming devices for internal combustion engines, and more particularly to devices of this character which comprise a plurality of primary carburetors, each .5 of which delivers a primary mixture of fuel and air to a plurality of secondary mixing chambers located adjacent the engine intake ports and in which the primary mixture is mixed with additional air under certain operating conditions.

Devices of this character are shown in the copending applications of Fred E. Aseltine et al., Serial No. 288,683, filed June 10, 1928 and Serial No. 360,404, filed May 4, 1929.

It is the object of the present invention to provide means for more accurately proportioning the mixture of air and fuel under certain operating conditions than has been possible in earlier forms of this device, and more particularly to more accurately regulate the admission of fuel subsequent to the opening of the secondary throttle.

' With this object in viewythe invention consists in the provision of means for controlling the admission of fuel through the high speed fuel nozzles, which is controlled directly from the secondary or air throttle so that the admission of fuel through such high speed fuel nozzles can be accurately regulated in accordance with the position of said air throttle.

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 ciearly shown.

In the drawings:

Fig. l is a vertical section through a charge forming device constructed in accordance with the present invention and showing one outlet branch of the manifold forming a part of said device.

Fig. 2 is a fragmentary side elevation of the device with certain parts broken away to show parts in section.

Fig. 3 is a fragmentary, transverse, vertical section on the line 3-3 of 1.

Fig. 4 is a section on the line 4-4 of Fig. 2.

Fig. 5.is a side elevation of the device viewed from the opposite direction to Fig. 2.

The device disclosed comprises an intake manifold it), having three outlet branches adapted to supply mixture to the several intake ports of a six-cylinder engine, the middle outlet branch 12 being disclosed herein. Flanges 14 are provided on the outlet branches for securing the device to the engine block in the usual manner, while a flange 16 is provided at the inner end of the manifold to which the main carburetor unit is adapted to be secured.

The carburetor unit comprises a housing 18 having a flange 20 adapted to be secured to the flange 16 by screws 22. An air inlet coupling 24 is secured in an opening in the top of the housing in any suitable Way and may be connected with an air cleaner, if desired. A casting 26 in which the fuel supply passages are formed, is secured in any desirable manner to the bottom of the main housing and a fuel bowl 28 is held tight against the bottom of the housing by any suitable means, as for instance, a screw 30, which i is screwed into the casting 26. Fuel is supplied to the bowl by means (not shown) and a float 32 maintains a substantially constant level of fuel therein in the usual manner.

A pair of fuel nozzles 34 and 36 are provided in each of the primary mixing chambers 38, there being three of these chambers, as shown in the two earlier applications above referred to. The nozzle 34 supplies all of the fuelat idling and relatively low speeds and a part of the fuel at all other times, while the nozzle 36 is ineffective to supply any fuel until the throttle has been opened to a considerable degree and the engine is running at relatively high speed. The two fuel nozzles are supplied with fuel through entirely separate fuel passages, the passage supplying the low speed nozzle being shown in Fig. 3. Fuel is admitted from the float bowl to a vertical fuel passage 40 through a calibrated plug 42 screwed into the lower end of such passage, while at its upper end, the passage connects with a horizontal channel formed in the top of the cast ing 26 and communicating directly with all of the nozzles 34.

Each low speed fuel nozzle is provided with a main fuel outlet 44 in the top of the nozzle and a secondary fuel outlet comprising orifices 46 and 48 in the side wall of the nozzle near the bottom of the mixing chamber. At relatively high speeds, the suction is sufficient to lift fuel from the main outlet as well as from orifices 46 and i8, but at lower speeds and idling, the suction is great enough to lift fuel only to some point between the main and secondary fuel out lets and fuel flows from the latter by the action of gravity.

The high speed fuel nozzles 36 are supplied with fuel through a separate passageway which is shown in Fig. 4. Fuel is supplied from the float bowl through a fuel port 50 which is controlled in a manner hereinafter described in detail. The port connects with a vertical bore 52 in the casting 26, which in turn connects with a horizontal passage 54 leading to another vertical passage 56, in which is provided a calibrated plug 58, to determine the maximum flow'of fuel therethrough. In an enlarged chamber 60, at the upper end of the vertical passage 56, is received a suction operated two-stage fuel valve 62 which is normally seated on a shoulder 64 in the passage. The valve is provided with a passage 66 therethrough to permit a small amount of fuel to flow through the valve when the latter is seated on the shoulder 64, and the suction effective on such valve is relatively low. The lower end of the valve is tapered, asindicated at 63 and it is also tapered intermediate its length at 70 where it engages the shoulder 64 when the valve is in the position shown in Fig. 3. As the suction increases, this valve is lifted and fuel is permitted to flow around the valve as Well as through the passage 66 in the manner fully described in application Serial No. 360,404. The port 50 is normally' closed by a valve .74 which is lifted in the manner hereinafter described to permit the high speed fuel nozzles to becomeeifective. Both high and low speed fuel nozzles are provided with restrictions 76 to regulate the flow therethrough.

The primary mixing chambers constitute the enlarged inlet ends of the primary mixture passages 78 which are parallel'and close together, as shown in application Serial No. 360,404. When the carburetor is secured to the'manifold, these passages register with primary mixture conduits which convey'the primary mixture to'secondary mixing chambers formed in the outlet endsof the manifold branches where they communicate with the engine intake ports, one of said conduits being shown in Fig. 1 and comprising a tube 79 receiving a bore in the manifold and extending to the outlet end of branch 12. Restrictions 80 separate the primary mixing chambers from the rest of the primary mixture passages and the passages 82 admit air to said primary'mixture passages immediately posterior to said restrictions for the purpose of reducing the velocitycf flow past the nozzles. The specific construction of the mechanism referred to immediately above is fully shown and described in application Serial A'single throttle valve 84 operated in the manner to be briefly described later, extends across all'of the primary mixture passages to control the flow 'ther'ethrough' and .is provided with grooves 36, which register with said mixture pas- All of the air admitted to the carburetor is controlled by an air valve 88, normallyv held against a seat by a spring 92 received between the valve and the flange 94 extending from a sleeve 96 slidably mounted on the stationary sleeve 98, which is fixed in the main housing and guides the airvalve stem 100. In order to choke the carburetor to facilitate starting, the valve may be lifted by a lever 102 which projects into the housing 18 beneath'the flange 94 untilthe sleeve 96 engages the air valve 88 to holdit closed. Enough air to carry the starting fuel'to the intake ports is admitted through slots 104 formed in the top of the air valve, as shown in Fig. 1.

The valve 88 admits air to a main air chamber 106 from which it flows to the primary mixing chambers through an opening 108 in the bottom of said air chamber and to the 'secondary'mixing chambers through a passage 110 leading to the manifold inlet controlled by manually and suction operated valves 112 and 114 secured to shafts 115 and 118 respectively, journalled for rotation in the main housing.

While the specific operating mechanism for the valves in this device forms no part of the present invention, the valve operating mechanism is recited in certain of the claims and, therefore, is described briefly herein. This mechanism comprises a cam plate 119, which is secured in any desirable manner to one end of the primary throttle and is provided with an orifice 121 in which some operating connection such as a Bowden cable,'may be connected to extend to apoint convenient to the operator of the vehicle. The cam plate is provided with a slot 123, which engages a pin 125 projecting from an arm 127 and secured to one end of the valve shaft 116, so that as the cam plate is operated by the operator of the vehicle to move the primary throttle, the slot 127 is effective to move the valve 112 through the medium of the connections above described. The slot 127 is so designed that a part thereof is concentric with the axis of the primary throttle so that for a portion of the movement of the cam plate it is ineffective to move the arm 127, being therefore, in effect, a lost motion connection. Of course, the form of the slot may be varied to suit any particular conditions it is desired to meet, but it is normally so designed that the valve 112 will not be moved until the throttle has been opened to a position sufficient to permit an engine speed corresponding to a vehicular speed of approximately fifteen to twenty-five miles er hour on the level.

The means for connecting the suction operated valve 114 to the operating mechanism above (1 scribed so that the closing movement of sa valve 114 is effected, is not described herein since l-i5 ing a cylinder and a piston 122 slidable therein and secured to the lower end of the air valve stem. As shown, this dashpot is adapted to be filled with fuel by leakage around the piston, out any conventional form of dashpot may be employed.

A dashpot is also provided to retard opening movements of the valve 114, its piston being connectedto the valve by a link 121 which is connected to a lever 123, one end of which is conone end of shaft 118. The resistance of this dashpot to opening movements of the valve is adapted to be controlled by an auxiliary piston 124 which is normally held in position to close a port 126, by a spring 128, received in the cylinder 130 in which the piston slides. A pump is also provided which is adapted to deliver fuel during the acceleration period through the passages indicated at 132. All of these devices are fully disclosed in application Serial No. 360,404, but do not form part of thisinvention.

As stated hereinbefore, the fuel inlet port 50 is controlled by a valve '74, which normally prevents admission of fuel through the port 50, but is adapted to be opened after the throttle has been opened to a predetermined degree, to provide .nected by a link 125 to an arm 12? secured to additional fuel to prevent the mixture becoming too lean after the opening of valve 112. As fully explained in application Serial No. 360,404, after such valve begins to open, the suction effective on the nozzles 34 does not increase as rapidly as prior to the opening of the valve. In order to compensate for this slower increase of suction, the fuel port supplies additional fuel and the amount of such fuel must be accurately regulated in accordance with the drop in suction at the nozzles 34 in order to retain the correct mixture proportions. In the earlier devices of this char acter such as shown in the above applications, the valve controlling the seconda y fuel has been operated directly by the prim throttle and with such an arrangement, it has been somewhat difficult to control the action of the valve so that the desired amount of additional fuel may be supplied. Since the admission of air by the valve 112 causes the reduction in suction at the nozzles 3 1, which makes the supplying of additional fuel necessary, the amount of additional fuel supplied should be exactly proportional to the effect of the valve 112. In other words, the movement of the valve 112 and the movement of the fuel valve controlling the additional fuel supply should be accurately synchronized. This has been .icult to do where the fuel valve is operated directly from the primary throttle and the valve 112 operated thereby through some form of lost motion connection. In the event of wear of the parts or some disarrangement of setting of the parts, the fuel valve and the a valve 112 become improperly timed. These d culties are overcome according to the present invention, by operating the fuel valve as directly from the air valve 112 instead of from the primary throttle. leans for accomplishing this comprise a cam which is adjustably secured in any desirable manner on one of the valve shafts 116 is adapted to engage a contact roller hi2 pivotally mounted on one end of a lever in pivote on the pin 146 projecting from the main hous- A spring 143, which is connected at one to the housing and at the other to the lever 14 i, is adapted to hold the roller in en agement with the cam, while the other end of the lever lie is pivotally connected to a link 150, which, its lower end, is pivotally connected to the valve stem It will be obvious that on opening movement of the valve 112, the cam 140 is effective to lock the lever i ls on its pivot and to move the valve 74 to a degree proportional to the movement of the cam. Thus, the fuel valve is moved directly by the air valve and there is little danger of the parts becoming so disarranged or so worn that they will fail to operate in substantial synchronization. In this manner the device is effective to form a mixture of the proper proportions throughout the entire operating range.

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 adopted, all coming within the scope of the claims which follow.

What is claimed is as follows:

1. A charge forming device for internal combustion engines comprising a secondary mixing chamber, a primary mixture passage for supplying a primary mixture of air and liquid fuel to said secondary mixing chamber, a primary throttle, a secondary air passage adapted to supply air to said secondary mixing chamber, a secondary air valve in said passage, means operated by the primary throttle for operating said secondary air valve after a predetermined movement of said throttle, a fuel inlet for supplying fuel to said primary mixture passage and means operated directly by the secondary air valve for controlling the fiow from said fuel inlet.

2. A charge forming device for internal combustion engines comprising a plurality of secondary mixing chambers, a plurality of primary mixture passages, each of which is adapted to supply a primary mixture of air and liquid fuel to one of said mixing chambers, a primary throttle controlling the flow through all of said primary mixture passages, a single secondary air passage adapted to supply air to all of said secondary mixing chambers, a secondary air valve in said passage, means operated by the primary throttle for operating said secondary air valve after a prede termined movement of said throttle, a fuel inlet for supplying fuel to all of said primary mixture passages and means operated directly by the secondary air valve for controlling the how from said fuel inlet.

3. A charge forming device for internal combustion engines comprising a mixture passage, fuel and air inlets for supplying fuel thereto, a fuel valve controlling said fuel inlet, an auxiliary air valve for admittingadditional air, a throttle, means for opening the auxiliary air valve only after a predetermined movement of the throttle, and means for operating the fuel valve only during the movement of the auxiliary air Valve.

4. A charge forming device for internal combustion engines comprising a mixture passage, fuel and air inlets for supplying fuel thereto, a fuel valve controlling said fuel inlet, an auxiliary air valve for admitting additional air, a throttle, means operated by the throttle for opening the auxiliary air valve after a predetermined throttle movement and means operated by the air valve for operating the fuel valve during the opening movement of said air valve.

5. A charge forming device for internal combustion engines comprising a mixture passage, fuel and air inlets for supplying fuel thereto, a

fuel valve controlling said fuel inlet, an auxiliary movement, means operated by the auxiliary air 1 valve for operating the fuel valve, said means being so constructed that the movement of the fuel valve is varied relative to the movement of the air valve as said last named valve is opened.

6. A charge forming device for internal combustion engines comprising a mixture passage, an air inlet therefor, fixed and variable fuel inlets therefor, an auxiliary air valve for admitting additional air, a throttle, a normally closed fuel valve controlling the variable fuel inlet, means operated by the throttle for opening the auxiliary air valve after a predetermined throttle movement, and means operated by the auxiliary air valve for operating said fuel valve.

FRED E. ASELTINE.

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