US1881686A - Charge forming device - Google Patents

Description

Oct. ll, 1932. KOEHLY ET AL v 1,881,686

CHARGE FORMING DEVICE Filed May 23, 1930 y@ Z gjmwntou Patented Oct. 11, 1932 UNITED STATES PATENT OFFHCE PAUL KOEHLY AND GLEN I. DELAPLANE, OF DAYTON, OHIO, ASSIGNORS TO DELCO PRODUCTS CORPORATION, OF DAYTON, OHIO, A CORPORATION F OHIO CHARGE FORMING DEVICE Application filed May 23, 1930. Serial No. 454,918.

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 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. Aseltinc et al, Serial No. 288,683, filed June 10, 1928, and Serial No. 360,404, filed May 4, 1929.

It is an object of the present invention to provide improved means for controlling the fuel supply during operation under various operating conditions and. more particularly to provide novel means for controlling the a dmision of fuel at relatively high speed with relatively wide open throttle.

It is a further object of the present invention to provide a fuel passage which is effective to supply additional fuel to the mixing chambers at relatively high speed operation which is controlled by the piston of the dashpot which regulates movement of the main air valve in such manner that said fuel passage operates not only to supply fuel as described, but also acts as a by-pass to permit the passage of fuel around the dashpot piston and thus to variably control the resistance of the dashpot in accordance with the position of the piston and variations in the engine speed.

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

In the drawing:

Fig. 1 is a vertical section through a charge forming device constructed according to the present invention showing the carburetor unit and one outlet branch of the manifold with which it is associated.

Fig. 2 is a fragmentary vertical section on the line 2--2 of Fig. 1.

Fig. 3 is a horizontal section on the line 3-3 of Fig. 1.

The device disclosed comprises an intake manifold having three outlet branches ada-pted 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 y 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 -f 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 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.

The fuel nozzles 34 project upwardly into the primary mixing chambers 36, the structure of which will be more fully described hereinafter. Fuel is conducted from the float bowl 28 to these nozzles through a vertical fuel passage 38 formed in the casting 26 and to which fuel is admitted through a fixed fuel feeding orifice 40 and through an orifice of variable area in the form of an elongated slot 42 which is normally ineffective, but which is rendered effective and is controlled in a manner which will be later described. The vertical fuel passage 38 communicates at its upper end with a horizontal channel 44, formed in the top of the casting 26 and communicating directly with the three fuel nozzles 34, as shown in Fig. 2. As will be explained more fully later, the fixed orifice 40 supplies all of the fuel to the nozzles 34 during operation at low and intermediate speeds and the fuel feeding slot. 42 is only brought into action when the speed is relatively high and the throttle is relatively h Wide open. Each nozzle is provided with a restriction 46 to limit the supply of fuel therethrough.

Each fuel nozzle is provided with a main fuel outlet 48 in the top of the nozzle and a secondary fuel outlet comprising the orifices 50 and 52 in the side Wall of the nozzle near the bottom of the mixing chamber. At intermediate and high speeds, the suction is great enough to lift fuel from the main fuel outlet as Well as from the orifices 50 and 52, but at idling or loW speed operation under load is not enough to lift fuel higher than to a point between the main and secondary fuel out-lets and fuel flows from the latter by the action of gravity.

The primary mixing chambers constitute the enlarged inlet ends of the primary mixture'passages 54, which are parallel and close together, as shown in F ig. 2. When the carburetor unit is secured to the manifold, these passages register With primary mixture conduits which convey the primary mixture to the secondary mixing chambers in the manner fully disclosed in the earlier applications above referred to. The primary mixture conduit associated With the middle branch of the manifold is shown in Fig. 1 and comprises a tube 56 secured in the manifold casting in any desirable Way. Restrictions 58 separate the primary mixing chambers from the remainder of the primary miX- ture passages and passages 60 admit air to the primary mixture passages immediately posterior to these restrictions for the purpose of reducing the velocity of flow past the nozzles as more fully set forth in the earlier applications.

A single throttle valve 62, operated in the manner briefly described hereinafter, extends across all of the primary mixture passages to control the How therethrough and is provided with grooves 62 which register with said passages.

Air is admitted to the carburetor through the coupling 24 and is controlled by a main air valve 66 normally held against the seat y68 by a spring 70 received between the valve and the flange 72 projecting from a sleeve 74 slidably mounted on a stationary sleeve 76 which is fixed in the main housing and guides the air valve stem 78. In order to choke the carburetor to aid in starting the engine, the valve may be lifted by a lever 80, which extends below the flange 72 in the manner fully described in the earlier cases, until the sleeve 74 engages the valve 66 to hold it closed. Enough air to carry the starting fuel to the engine intake ports is admitted through slots 84 formed in the top of the valve as fully shown in Fig. 1.

The valve 66 admits air to a chamber 86 from which it flows to the primary mixing chambers through an opening 88 in the bottom of said air chamber and to the secondary mixing chambers formed in the manifold through a passage 90 leading to the manifold inlet and controlled by manually and suction operated valves 92 and 94, secured to shafts 96 and 98 respectively, which are journalled i in the main housing.

' The operating means vfor the throttle and the valve 92 constitute no part of this invention and arc not illustrated herein, but the mode of operation of these valves will now be very'briefiy described in order to enable a better understanding of the operation of the whole device. The throttle is connected to the valve 92' by an adjustable lost motion connection which permits certain independent movement of the throttle and is generally adjusted so that the throttle may move independent of the valve 92 until it reaches a position corresponding to a vehicular speed of approximately 15 to 20 miles per hour on the level. On further opening of the throttle, the valve 92 is moved simultaneously.

On any increase of suction in the chamber 86, the valve 66 is opened to admit more air and the opening of this valve is retarded to prevent fluttering of the valve and to prevent admission of suliicient air to lean the mixture. For this purpose a dashpot is provided comprising a cylinder 100 and a piston 102 slidal ble therein and secured in any desirable way to the lower end of the valve stem. The dashpot illustrated is filled With fuel by leakage around the piston, but any conventional form of-dashpot may be employed.

The valve 94 is also controlled by a dashpot (not shown) the resistance of which is regulated by a piston 104, which is normally held in a position to closethe port 106 by a spring 108, and comprises a relief valve to control the action of the dashpot in the manner described in the copending application 360,404. The chamber 110 and the fuel passages indicated in general by the reference character 112, which lead from said chamber to the mixture passages form parts of the delivery passages from a fuel pump for supplying additional fuel during the acceleration period. Neither of these devices constitute a part of the present invention and, l

therefore, are not disclosed specifically herein, being fully shown and described in application Serial No. 360,404.

As has been stated hereinbefore, the fuel inlet 40, which is of fixed area suppli es all of the fuel to the nozzles during operation at low and intermediate speeds. For reasons which have been fully pointed out in the earlier applications above referred to, it has been found necessary at relatively high Tir speeds following the opening of the valve 92, to supply additional fuel in order to prevent the mixture from becoming too lean to be properly combustible and to give the desired power.

According to the present invent-ion,`

this auxiliary fuel supply means comprises the tapered slot 42, which is formed on the inner wall of the dashpot cylinder 100, as indicated in Fig. 2. The slot is so formed that it is very narrow at its upper end and gradually enlarges toward the bottom where it communicates through a channel 114 and a calibrated plug 116 with the vertical passage 38. A plate 118, secured to the bottom of the casting 26, closes the channel 114 and the dashpot cylinders in the casting 26, a suitable gasket preventing leakage. It will be clear from the disclosure of Figs. 1 and 2 that when the air valve 66 is closed and the dashpot piston 102 is in the upper position as shown in Figs. 1 and 2, that the fuel passage 42 is closed. As the air valve opens the dashpot piston is moved downwardly and when the air lvalve assumes the position it would normally occupy when the vehicle is running at a speed of approximately to miles per hour on the level, the piston begins to uncover the upper end of the tapered slot to permit a flow of fuel therethrough to the fuel passage 38. As the valve continues to open, the piston is moved downwardly to a greater extent and the effective area of the fuel passage 42 is gradually increased so that the amount of fuel supplied thereby will be increased as the engine speed increases.

It will be obvious also that because of the opening of the passage 42, the resistance of the dashpot to opening of 'the air valve will be gradually decreased as the valve moves toward open position so that its retarding effect on the admission of air is gradually decreased as the engine speed increases. This has been found desirable to secure a mixture 40` of desired proportions during the acceleration period following an opening of the throttle, it having been found that the degree of enrichment required 'when accelerating at high speeds is less than when accelerating at relatively low speeds. The slot 42, therefore, performs two distinct functions: first, admitting additional fuel to provide a mixture of proper proportions at higher speeds, and second, simultaneously controlling the resistance of the dashpot to restrict the admission of air to the desired extent as the speed varies.

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 mixture passage, a throttle controlling the flow of mixture therethrough, an air valve controlling admission of air to said mixture, a fuel supplypassage of fixed area for supplying fuel to the mixture passage during normal operation, a dashpot for retarding the opening movement of the air valve and a second normally ineffective fuel'passage for supplying fuel to the mixture passage, said second fuel passage being normally closed and adapted to be opened by the dashpot piston as the valve is opened.

2. A charge forming device for internall combustion engines comprising a mixture passage, a throttle controlling the flow of mixture theret rough, an air valve controlling admission of air to said mixture, a dashpot controllinfr the opening movement of said air valve comprising a cylinder and piston movable relatively thereto, and a tapered fuel passage formed in the Wall of the'dashpot cylinder for supplying fuel tothe mixture passage.

8. A charge forming device for internal combustion engines comprising a mixture passage, a throttle controlling the flow of mixture therethrough, an air valve controlling admission of air to said mixture, a dashpot controlling the opening movement of said air valve comprising a cylinder and piston movable relatively thereto, and a tapered passage in the wall of the dashpot cylinder adapted to supply fuel to the mixture passage, said passage beingk uncovered by the dashpot piston on movements of the air valve, whereby the area of the fuel passage and the resistance of the dashpot is simultaneously' variedby said piston.

4. A charge forming device for internal combustion engines comprising a mixture passage, a throttle controlling the flow of mixture therethrough, an air valve controlling admission of air to said mixture, a fuel nozzle constituting the main fuel supply to the mixture passage during all normal operation of the engine, a dashpot retarding opening movements of the air valve, and a fuel passage for supplying fuel to said nozzle and receiving fuel from the dashpot cylinder, the

dash pot cylinder and piston cooperating with each other to form a valve for regulating the flow of fuel through said fuel passage substantially in accordance with variations in the position of the air valve.

5. A charge forming device for internal combustion engines comprising'l a mixture passage, a throttle controlling the fiow of mixture therethrough, a main air valvecontrolling admission of air to said mixture, a fuel nozzle constituting the main fuel supply to the mixture passage during all normal operation of the engine, a dashpot retarding opening movements of the air valve, and a fuel passage for supplying fuel to said nozzle and receiving fuel from the dashpot cylinder, the dashpot cylinder and piston cooperating with each other to form a valve for varying the flow of fuel through said fuel passage substantially proportionally to the movements of the air valve.'

of and communicating With the dashpot cylinder and controlled by the {laslmot piston, said port being so designed that the supply ot fuel to the nozzle and the retarding eI/eet of the dashpot are Simultaneously regulated by movement of said piston as the air valve moves.

13. A charge forming device fer internal combustion engines Comprising a mixture passage, a throttle controlling the loW of mixture therethrough, n main air va ve controlling admission of air to said mixture, a fuel nozzle for supplying fuel to the mixture passage, a dashpot for retarfling opening movements of the rln air valve comprising a cylinder and piston movable therein, and a fuel passage for Supplying fuel to said nozzle said passage having an inlet port communieating with the dnshpot cylinder and controlled by the dashpot piston, said port being so designed that the supply of fuel to the nozzle is increaeed and the retarcling effect of the dashpot is simultaneously decreased by vivement of the dashpot piston on opening movement of the air valve.

ln testimony whereof we hereto nHiX our signatures.

GLEN I. DELAPLANE. PAUL KOEHLY.

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