US3441010A

US3441010A - Apparatus for controlling the flow of fuel to an engine

Info

Publication number: US3441010A
Application number: US602986A
Authority: US
Inventors: Edward J Barr; John H Brooks
Original assignee: Mcculloch Corp
Current assignee: Mcculloch Corp
Priority date: 1966-12-19
Filing date: 1966-12-19
Publication date: 1969-04-29
Anticipated expiration: 1986-04-29
Also published as: GB1207364A; DE1576593B1; JPS4844208B1

Description

April 29, 1969 E. J. BARR ETAL 3,441,010

APPARATUS FOR CONTROLLING THE FLOW OF FUEL TO AN ENGINE Sheet Filed Dec. 19, 1966 FIGI INVENTORS EDWARD J. BARR JOHN H. BROOKS ATTORNEYS April 29, 1969 E. J. BARR ETAL APPARATUS FOR CONTROLLING THE FLOW 0F FUEL TO AN ENGINE Sheet Filed Dec.

PULSE SIGNALS 49 FROM ENGINE CRANKCASE INVENTORS EDWARD J. BARR FUEL FROM FUEL RESERVOIR JOHN H. BROOKS 5 fled why,

ATTORNEYS United States Patent US. Cl. 123-119 6 Claims ABSTRACT OF THE DISCLOSURE A carburetor including a fuel-flow control which is independent of air flow through the carburetor and which is governed by superambient pressure conditions Within the crankcase of an engine.

General background of the invention The problems associated with supplying mixtures of fuel and air to internal combustion engines are complex and have resulted in the development of a large number of carburetion devices.

Many of these devices such as those featured in the United States Barr Patent 3,201,096 and the United States Barr Patent 3,104,617 are characterized by diaphragm fuel pumps which are operated by fluctuations in crankcase pressure. In these patented devices, the flow of fuel between the diaphragm pump and the air passage of the carburetor is determined by movements of a fuel-flow regulating diaphragm as influenced by air flow through a venturi portion of the air passage.

Nevertheless, it has been found that it would be desirable to improve carburetor structures such as those featured in the above-noted Barr patents by enabling them to vary fuel supply more accurately in response to changes in engine load conditions. In addition, it has been found that it would be desirable to improve such carburetors so as to provide a higher engine power output at all engine speeds by supplying a more correct mixture of air and fuel, by removing the air flow restriction of the metering venturi from the air passage, and by using an air passage size selected for optimum air flow.

Further, it would be desirable to improve such carburetors by simplifying their overall structure.

Summary of invention Specifically, it is an object of the invention to provide improved structures in the carburetion art which enable carburetion to be more responsive to engine operating conditions.

It is also an object of the invention to provide improved carburetion techniques which enable engines to increase their maximum power output, particularly at low operating speeds.

Another object of the invention is to provide a vastly simplified carburetion system and technique which can wholly avoid conventional, venturi-type fuel feed arrangements.

A collateral object of the invention is to provide improved carburetion systems which are characterised by overall structural simplicity and by a higher degree operational efliciency and reliability.

In order to accomplish at least some of these principal objectives, there is presented through this invention, an improved carburetor apparatus which comprises an air passage, fluid operated control means for feeding fuel to the air passage and operating signal means independent of the air passage for supplying an operating, fluid signal to the control means. The operating signal means is 3,441,010 Patented Apr. 29, 1969 ice adapted to be connected with a fluid chamber of an engine, to be supplied with air and fuel by the carburetor apparatus and within which chamber, pressure varies as a function of the speed and throttle setting of the engine.

A related facet of the invention entails a combination including an air passage for supplying air and fuel to an engine, a fuel compartment, and passage means leading from the fuel compartment to the air passage. This combination includes means for pressurizing fuel in the fuel compartment, which means is responsive to the operating speed and throttle setting of the engine and independent of the air velocity in the said air passage.

Another independently significant apparatus aspect of the invention entails the ability to utilize a carburetor air passage which has a longitudinally constant cross section.

A still further independently significant aspect of the invention entails an apparatus for uniquely modulating a fuel flow controlling, fluid signal derived from an engine chamber which communicates with an engine piston. In this apparatus, pressurized fluid from an engine chamber in communication with an engine piston is transmitted to a control signal compartment. This signal is modulated by continuously venting a portion of the fluid from the signal compartment.

Another interesting apparatus facet of the invention relates to structure for rectifying a fluid control signal generated within a crankcase of an internal combustion engine. Pulsating fluid is transmitted from the crankcase chamber to a control signal compartment through check valved conduit means. The check valve structure in this conduit means serves to transmit superambient signals generated in response to piston movement in one direction while blocking subambient signal changes produced by movement of the piston in an opposite direction.

Obviously, maximum benefits of the invention are derived from the coaction of the previously, individually identified, apparatus aspects.

Brief description of the drawings In describing the invention, reference will be made to a preferred carburetor embodiment shown in the application drawings.

In the drawings:

FIGURE 1 provides a schematic sectional view of a carburetor and associated internal combustion engine, illustrating the manner in which fuel is pressurized by superambient crankcase pressure and flowed into a carburetor air passage under the control of crankcase pressure;

FIGURE 2 schematically illustrates the flow path of fuel through the FIGURE 1 carburetor; and

FIGURE 3 is an exploded perspective view of the individual components of the FIGURE 1 carburetor, recognizing that in FIGURE 1 the FIGURE 3 components have been schematically illustrated and flow paths altered to enable a complete fuel flow path to be shown in a single illustrative plane.

Overall engine and carburetor system FIGURE 1 schematically illustrates an overall engine and carburetor system embodying significant features of the present invention. FIGURE 2 augments FIGURE 1 by illustrating the fuel flow path through the carburetor of the system.

FIGURE 1 schematically shows a conventional, twocycle internal combustion engine 1. Engine 1 is provided with a cylinder 2, a piston 3 mounted for reciprocation within cylinder 2, and a connecting rod 4. Connecting rod 4 is pivotally secured at its upper end to piston 3 and at its lower end to a radially offset portion of a crank shaft 5.

Crank shaft 5 is housed within crankcase 6. Crankcase 6 defines a closed chamber communicating directly with piston 3. Crankcase 6 is provided with a reed-valve controlled, fuel inlet port 7. A conventional reed valve 8 functions as a check valve to admit a liquid fuel (such as gasoline and oil) and air mixture into the interior space 9 of the crankcase. Valve 8 also prevents a reverse flow of this fuel mixture out of the crankcase space 9. Cylinder 2 includes conventional fuel inlet ports 10 and 11 and an exhaust port 12, with inlet ports 10 and 11 communicating with space 9.

In a conventional fashion, on the upstroke of the piston 3, fuel within the combustion chamber 13 of cylinder 2 is compressed. As the piston 3 reaches the upper end of its stroke, the compressed fuel is ignited by a conventional spark plug in the cylinder head, not shown. On the downstroke of the piston 3, induced by the burning of the combustion charge, the exhaust port 12 is first uncovered and the burned gas exits through this uncovered port. Shortly thereafter, the continued downward movement of the piston 3 opens the fuel inlet ports 10 and 11. Fresh fuel within the crankcase space 9 then enters the combustion chamber 13 through the fuel inlet ports 10 and 11.

As will be understood, fresh fuel is drawn into the crankcase space 9 during the upstroke of the piston 3 which creates a relatively low, i.e., subambient, pressure condition in the crankcase space 9. On the downward stroke of the piston 3, this fresh charge is compressed by the movement of the piston 3 into the crankcase space 9. The pressurized fuel charge within the crankcase space 9 then flows into the uncovered ports 10 and 11.

During the operation of the engine 1, variations in its operating speed and throttle condition will produce generally corresponding changes in the pressure of the gaseous components of the fuel and air mixture within the crankcase 9. Thus as the speed of piston reciprocation increases or as the throttle is opened wider, the pressure of the gaseous fuel charge within the space 9 increases. Conversely, as engine speed drops or as the throttle is closed, the pressure of the gaseous charge within the crankcase 9 drops. In short, crankcase pressure may be viewed as being a function of the operating speed and throttle condition of the engine 1 and therefore a function of engine fuel requirements. It will here be understood of course that crankcase chamber 9 may be considered a pulse chamber associated with the engine 1 and within which fluid pressure pulses in response to the reciprocating movement of the piston 3.

The mixture of air and fuel, which is predominantly gaseous in character, is supplied to port 7 through conduit means 14 extending from the air passage of a carburetor 15.

It thus now becomes appropriate to consider the unique and improved fashion by which air and fuel is supplied to the engine, in direct response to engine generated, positive pressure conditions existing within the crankcase 9.

Carburetor 15 comprises, as its basic components, a fuel pump, a fuel feed control mechanism, and an air and fuel mixing passage.

Fuel pump 16 of carburetor 15, as schematically shown in FIGURES 1 and 2, comprises a fuel inlet port 17 extending from a conventional fuel supply or reservoir 18. Port 17 communicates with a chamber 19 disposed on one side of a sintered bronze or multiple screen layer, fuel filter 20. Fuel passes through filter 20 into a chamber 21 and then through a flexible flap, check valve 22 into a fuel compartment 23. Fuel compartment 23 is disposed on one side of flexible, i.e., movable diaphragm 24. Fuel flows out of fuel compartment 23, under the influence of movement of diaphragm 24 into this compartment, and through a check valved port 25. A conventional flap-type check valve 26 serves to control this out-flow of fuel.

A signal compartment 27 communicates through conduit or passage means 28 with crankcase space 9. Alternating subambient and superambient pressure pulses generated within the chamber 9 by reciprocation of the piston 3 are transmitted through conduit means 28 to signal chamher 27. These pressure pulses induce pulsating movement of the diaphragm 24. During movement of the diaphragm 24 into the fuel space 23, fuel is displaced from this space through the port 25. Flap valve 22, during this pressurizing and displacing of the fuel, closes the chamber 21. During movement of the diaphragm 24 away from the fuel chamber 23, the port 25 is closed by the check valve 26, while the check valve 22 is open so as to admit additional fuel into the chamber 23.

Fuel discharged through port 25 flows through a passageway 29 which leads to a fuel flow control valve.

The structure and mode of operation of fuel pump 16 are known in the art, as evidenced by the disclosure of Barr Patent 3,104,617. As in the case of the pump featured in this Barr patent, it is contemplated that in the fuel pump of the present invention, the

flap valves

26 and 22 as well as the pumping diaphragm 24 may be provided by a unitary, sheet-like member fabricated of elastomeric material or by a laminate comprising rubber or plastic layers in combination with flexible reinforcing.

With this known arrangement of structural components, pressure pulsations within the crankcase interior 9 serve to pump fuel through the fuel pump 16 into the fuel delivery passage 29.

With the fuel pump portion of the carburetor 15 having been described, it now becomes appropriate to consider the control mechanism 30 of the carburetor which serves to regulate the discharge of pressurized fuel into the air passage of the carburetor.

Control mechanism 30 is characterized by a movable or flexible diaphragm 31 which divides a chamber 32 into a fuel compartment 33 and a signal compartment 34.

In fuel compartment 33, a metallic plate 35 is interposed between the diaphragm 31 and a valve operating arm 36. Valve operating arm 36 is pivotally mounted on a pivot shaft 37 having an axis parallel to diaphragm 31. One end of arm 36 is biased laterally into engagement with the plate 35 by a coil spring 38. The other end of arm 36 engages a needle-type valve 39. With diaphragm 31 disposed in the neutral or rest position shown in FIG- URE 1, valve operating arm 36 holds needle valve 39 in a position engaging a valve seat 40 so as to close the fuel supplying passage 29. Preferably, coil spring 38 provides only slightly more biasing of the arm 36 than is necessary to hold valve 39 closed when no pressurized fluid is present in compartment 34.

Fuel is discharged from fuel compartment 33 through an open passage 41 which communicates with

idle ports

42 and 43. Flow through passage 41 to

idle ports

42 and 43 may be selectively regulated by a conventional needle valve 44.

Fuel also flows from fuel compartment 33 through a passage 45 to a main fuel port 46. Flow through passage 45 to main fuel port 46 may be controlled by a conventional needle valve 47. Port 46 may be provided with a conventional ball-type check valve 48 as illustrated, or alternatively with other known forms of check valves to permit a discharge flow of fuel from the passage 45 through the port 46 while preventing a flow of air into the port 46 for back flow through the passage 45 to the fuel compartment 33.

These components of control mechanism 30 thus far described are well known. There now will be described a unique concept for controlling the operation of the valve 39 and determining the pressure of fuel being discharged into an air passage of the carburetor 15.

Conduit means 49 extends between crankcase interior 9 and signal compartment 34 of control mechanism 30. As schematically shown, conduit means 49 communicates with a crankcase port 50 which is generally remotely located with respect to the fuel inlet port 7 and which is elevated above the base of crankcase space 9 where some oil may tend to accumulate. Passage means 49 is check valved to allow a flow of fluid at superambient pressure within crankcase space 9 from this space to the signal compartment 34. This check valve arrangement serves to prevent or block a flow of fluid from the signal compartment 34 to the crankcase space 9 in response to subarnbient pressures within this space created during the upstroke of the piston 3.

This check valving may be accomplished by interposing a flexible lip-type check valve 51 in the passage means 49 of the type described in the US. Hoffman, 3,155,110 patent. As illustrated, a cylindrical body portion 52 of check valve 51 is supported between

annular passage abutments

53 and 54, with check valving, flexible lips, 55 of the valve 51 facing the signal compartment 34.

As will thus be appreciated, this check valve serves to rectify the fluctuating subambient and superambient pressure signal generated within the compartment 9, as a result of piston reciprocation, and transmits only the positive or superambient pulse portions of this signal.

The pressure level of the crankcase signal is diminished by flow restricting, orifice means 56 which may be disposed in the passage means 49.

A constant venting of signal compartment 34 is accomplished by means of a restricted vent 57. As illustrated, vent 57 may comprise a flow restricting, bleed orifice providing communication, through a side wall of the compartment 34, between the signal compartment 34 and the atmosphere surrounding the carburetor 15.

With this arrangement, gaseous fluid within the crankcase compartment 9, which is pressurized to a superambient level by the piston 3, is transmitted through the passage means 49 to the signal compartment 34. The level of pressure of this fluid is a function of the operating speed and throttle condition of the engine, as previously noted. Through the combined interaction of the flow restricting orifice 56, and the check valve 51, this signal generating fluid is both reduced in pressure and rectified in the sense that positive pressure fluid only is transmitted.

The bleed orifice 57, in allowing a continuous flow of fluid into and out of the compartment 34, serves to modulate this pressure signal and prevents a buildup of pressure within the signal compartment 34 which would not reflect pressure conditions within the crankcase 9. In other words, with the check valve 51 in the system, it is necessary to vent the system to prevent a mere continuous buildup of pressure within the signal compartment.

The pressure generated within the compartment 34 will tend to move the diaphragm 31 upwardly, when the apparatus is viewed as shown in FIGURE 1, so as to open the needle valve 39 and admit pressurized fuel to the fuel compartment 33. Fuel will enter the compartment 33, fill the compartment, and flow through the

passages

41 and 45 to the idle and fuel ports respectively. The pressure of the fuel body within the compartment 33 will rise to a level governed by the pressure in signal compartment 34. In other words, when the fuel pressure within the compartment 33, coupled with the normally relatively small biasing effect of the spring 38, produces enough force acting on the diaphragm 31 to balance the pressure of the gaseous fluid acting on the diaphragm 31 within the signal compartment 34, the diaphragm 31 will tend to be restored to a neutral position so as to cause the arm 36 to tend to reclose the needle valve 39. As will be appreciated with the continuous out-flow capability of the system, as provided by the

passages

41 and 45 and their associated fuel ports, a more or less steady state condition will develop, with the valve 39 remaining partially open and continuously admitting fuel to the chamber 33 and with the diaphragm 31 being maintained in a substantially or near balanced condition but displaced upwardly as shown in FIGURE 1 so as to hold the valve 39 open.

In this connection it should be appreciated that the flow restricting orifice 56 performs an important function in maintaining the level of the pressure of the fluid body within the compartment 34 beneath the level of the pressure of the fuel body in compartment 23 being supplied to the conduit means 29. This flow restriction of the crankcase signal pressure insures that this signal does not overpower the fuel pressure and prevent the closing of the valve 39 once it has been opened.

As will be subsequently described, at idle speeds of engine 1, the signal within compartment 34 may not be of suflicient strength to govern the delivery of fuel. However, under full or partial engine load condition, the signal compartment 34 functions to both open the valve 39 and determine the level of fuel pressure within the fuel compartment 33, i.e., the delivery pressure of fuel to the

fuel ports

42, 43 and 46.

With this mode of fuel delivery, the fuel and air, mixing and delivery passage 58 may be radically simplified. Thus, as shown in FIGURE 1, this carburetor air passage 58 is wholly devoid of the usual venturi structure and is characterized by a longitudinally uniform cross section. This cross section conventionally will be circular or cylindrical in character.

A conventional butterfly throttle valve 59 is mounted on a pivot shaft :60 for valving movement within the passage 58. In a conventional fashion, with the butterfly valve 59 disposed in a near fully closed i.e. idle position, as shown in FIGURE 1, one lip portion 61 of the valve will be disposed between the

idle ports

42 and 43, with the idle ports being downstream of the main fuel port 46. As illustrated, all of the

fuel ports

42, 43 and 46 discharge directly into the air passage 58 for mixing with the air flowing through this passage in response to vacuum conditions existing within the crankcase 9.

Operation of system While the engine 1 is operating at idle or low speed conditions with throttle 59 closed (but permitting a small air flow), a very low level, positive pressure signal will exist within the signal compartment 34 as a result of the relatively low positive pressure pulses generated within the crankcase 9. Depending upon the strength of the spring 38, this pressure level within the compartment "34 may or may not be sufficient at low idle conditions to induce movement of the diaphragm 31.

'1t the signal in compartment 34 is not strong enough to overcome the spring 38, the entire injection of fuel into the passage 58 will be effected by air being drawn through the passage 58 and partially deflected by the lip portion 61 to enter the idle port 43 and carry fuel through the port 42 back into the passage 58 for transmission to the crankcase chamber 9.

If the pressure level within compartment 34 at idle conditions is sutficient to overcome the spring 38, the diaphragm will be moved so as to open the valve 39 and allow fuel to flow through the

passages

45 and 41 under pressure determined by the pressure within the signal compartment 34. When this occurs, fuel will be discharged in very small quantities from the port 46 and some augmented fuel discharge may result from the port '42 as a result of the signal compartment generated and fuel feeding pressure, However, at engine idle conditions, it is contemplated that the predominant fuel feeding effect will result from the deflection of air into the port 43 which will pass out of the port 42 carrying fuel with it in a well recognized fashion, described for example, in the aforementioned Barr Patent 3,201,096.

Under part throttle or full throttle operating conditions where the throttle valve 59 is part or fully open, the predominant feeding of fuel will occur through the main fuel port 46 under the influence of signal compartment 34, in the manner previously described. In this case, it will be recognized that the

idle ports

42 and 43 are quite small relative to main port 46 so as to allow only a relatively small rate of fuel fed through the idle ports in relation to that of the main port 46.

During part or full throttle operations, as changes in engine operating speed and throttle condition occur, generally corresponding changes in the pressure level within the sign-a1 compartment 34 will occur. These changes in the pressure level within the compartment 34, which will occur promptly in response to changes in engine operating speed and throttle condition, will produce generally corresponding changes in the pressure of fuel within the fuel compartment 33 being delivered to the port 46. Thus, as the throttle is opened and engine speed increases, the pressure of the fuel being delivered to the port 46 will increase so as to increase the rate of fuel flow into the passage 58 and satisfy engine fuel demand. Conversely, when the throttle is partially closed and engine speed reduces, the pressure of fuel within the compartment 33 will be correspondingly reduced so as to lessen the rate at which the fuel is supplied to the engine.

Structural details of preferred embodiment FIGURE 3 illustrates components of a carburetor assembly which will provide the fuel llow and control system shown in FIGURES l and 2.

As illustrated, these components comprise a main body 62, a regulator or control diaphragm 63, a diaphragm plate 64, a fuel pump diaphragm 65, and a cover plate 66.

Cover plate "66 includes a conduit-like stub 67 adapted to be connected with a conduit leading to a fuel supply 18 previously noted. Plate '66 provides infeed passage '17, which communicates with an opening 68, in fuel pump diaphragm *65. Recess 68a in the underside of plate 64 cooperates with diaphragm opening 68 to provide chamber 19, previously described, which communicates with a filter 20, not shown in FIGURE 3. Filter 20, would be press fitted or be otherwise mounted in an upper portion of a recess 69 of plate 66 so as to provide beneath it the chamber 21. Plate 66 has formed in it an L-shaped passage 21a, defining a continuation of chamber 21. Flow through this passage is regulated by a check valve flap 22 which is provided by the fuel pump diaphragm sheet .65.

A recess 70 in plate '66 provides fuel compartment 23. A connecting passage 71 defines a continuation of compartment 23 and provides communication between chamber 23 and an opening 72 adjacent flap 22. Opening 72, cooperates with a recess 72a of plate 64 to provide communication between check valve 22 and the connecting passage 71.

Connecting port 25 is formed as an L-shaped passage in plate '66 providing communication between the fuel compartment 23 and the check valve 26, included in diaphragm sheet 65. A space 73 in sheet 65 adjacent check valve 26 cooperates with a recess 74 in the underside of body plate '64 to provide communication with passage means 29. Passage means 29 extends to needle valve 39 and comprises opening of the

components

62, 63 and 64 aligned in a conventional and well-known fashion. Structural details of the passage portion 29 and the associated control valve 39 which are carried within the main body member 62, being conventional, are not shown. Other conventional structures included in body member 62, such as valve 39,

valves

44 and 47, arm 36, etc., have not been shown in detail in FIGURE 3 so as to avoid the obscuring of novel features of the present inventions.

A recess 75 in the underside of diaphragm plate 64 provides pump signal compartment 27. Passage means 28 comprise inter-connected apertured portions of

members

62, 63 and 64 aligned in a conventional fashion during assembly of the carburetor. A dished portion or concave recess 76 on the upper side of the plate "64 provides the control chamber or signal chamber 34.

Regulator diaphragm 63 may comprise a laminate structure including a flexible, diaphragm defining, sheet 77 mounted on the underside of a centrally apertured gasket 78. As schematically shown, metal plate 35 is mounted on a diaphragm sheet 77 within the aperture of the gasket 78.

A recessed under portion 79 of main body 62 provides fuel chamber 33.

Signal passage means 49 within the carburetor is defined by interconnected apertured portions of body 62 and diaphragm sheet 63. Check valve 51 may be telescopingly received within an enlarged lower end 80 of passage portion 49a included in body member 62. Aperture 81 of passage means 49 in sheet 63 may be dimensioned so as to provide the check valve securing, annular abutment 54. A shoulder 82 of the enlarged end of passage 49a provides abutment 53.

Air passage 58 is defined as a smooth cylindrical bore extending through body portion 62. As schematically shown, body portion '62 supports the throttle shaft 60 which in turn supports throttle valve 59 within the air passage 58 in the usual fashion.

A generally L-shaped opening 83 of plate 64 projects axially downwardly from opening 81 and then laterally into communicating relation with recess plate portion 76. Opening 83 defines the orifice 56 identified in FIGURE 1. A laterally extending opening 84 in plate 64 defines the bleed orifice 57 described in relation to FIGURE 1.

The carburetor components shown in FIGURE 3 are interconnected and clamped together by conventional threaded fasteners passing through the apertures A of the

components

63, 64, 65 and 66 into threaded holes B in the underside of the body member 62.

Summary of advantages and scope of invention A principal advantage attributable to the new carburetor concept presentedthrough this invetnion entails the more accurate reponse of the carburetor to engine fuel requirements. In practice, it has been found that with the carburetor of this invention, optimum fuel-air mixtures for an engine may be obtained at low operating speeds without resorting to small air flow passages which restrict engine power.

Another particularly significant advantage entails the ability to totally eliminate a carburetor venturi, with its attendant structural complexities and air flow restriction.

It is also significant to note that the improved carburetor concept of this invention provides accurate and rapid response of carburetor fuel feeding over a remarkably wide range of engine operating conditions.

It is also significant that through the invention, the overall structure of a carburetor may be simplified so as to reduce fabricating costs and minimize maintenance.

In describing the invention, reference has been made to a preferred embodiment. However, those skilled in the carburetor art may well recognize additions, deletions, substitutions or other modifications which would fall within the purview of the invention as defined in the appended claims.

We claim:

.1. An improved carburetor apparatus comprising:

an induction passage operable to transmit air and fuel to an engine;

fluid operated control means for feeding fuel to said induction passage; operating means isolated from said induction passage for supplying operating fluid to said control means;

said operating means being connected with a fluid chamber of an engine to be supplied with air and fuel by said carburetor apparatus and within which chamber the pressure varies as a function of the speed and throttle condition of said engine and pulses are provided in response to reciprocation of a piston of said engine; and

means operable to maintain a substantially steady state pressure of fluid transmitted by said operating means to said control means in response to a particular engine speed and throttle condition, with said steady state pressure being a function of said engine speed and throttle condition.

2. An improved carburetor apparatus comprising:

an induction passage operable to transmit air and fuel to an engine having a pulse chamber associated therewith;

control means for feeding fuel to said induction passage;

operating means operable to be connected with said chamber, said operating means being isolated from said induction passage for operating said control means in response to the speed and throttle condition of said engine to which fuel and air is to be supplied by said carburetor;

said control means being operable to be connected with fuel pump means, with said fuel pump means supplying pressurized fuel to said control means for transmission to said induction passage; and

pressure regulating means operably connected to said operating means to maintain a substantially steady state pressure of fuel transmitted by said control means to said induction passage in response to a particular engine speed and throttle condition, with said steady state pressure being a function of the speed and throttle condition of said engine and variable in accordance with changes in said engine speed and throttle condition.

3. The improved carburetor apparatus of claim 2:

wherein said operating means comprises conduit means adapted to transmit pressurized fluid from the crankcase of said engine to said control means to eflect the operation thereof.

4. The improved carburetor apparatus of claim 3:

wherein said induction passage comprises a smooth walled, cylindrical passage having a longitudinally uniform cross section; wherein said control means comprises:

movable diaphragm means,

a fuel compartment communicating with one side of said diaphragm means,

fuel discharging passage means communicating with said fuel compartment and with said induction passage,

fuel inlet passage means adapted to supply fuel to said fuel compartment,

valve mean-s operable in response to movement of said diaphragm means to control fluid flow through said fuel inlet passage means;

wherein said operating means comprises:

a signal compartment communicating with a side of said diaphragm means opposite to said one side,

said conduit means being in communication with said signal compartment;

wherein said pressure regulating means includes orifice means providing continuous, restricted communication between said signal compartment and the atmosphere, and

check valve means in said conduit means operable to allow flow from said crankcase to said signal compartment but prevent flow from said signal compartment to said crankcase; and

said pump means being operable to be connected with said fuel inlet passage means to supply pressurized fuel thereto.

5. The improved carburetor apparatus of claim 4:

wherein said pressure regulating means includes flow restricting means in said conduit means extending from said signal compartment and adapted to communicate with said crankcase;

wherein said pump means comprises:

second movable diaphragm means,

a second fuel compartment on one side of said second diaphragm means and passage means for supplying fuel thereto,

a second signal compartment on the opposite side of said second diaphragm means,

conduit means providing fluid communication between said second signal compartment and said crankcase, and

check valve means adapted to allow fuel to flow through said passage means for supplying fuel to said second fuel compartment while preventing a reverse flow of fuel therethrough and permit an outflow of fuel from said second fuel compartment into said fuel inlet passage means leading to said first diaphragm means while preventing a reverse flow of fuel therethrough;

said flow-restricting means and said orifice means being adapted to maintain pressure of fluid being supplied to said signal compartment communicating with said first diaphragm means at a level less than the pressure of fuel supplied to said fuel compartment communicating with said first diaphragm means.

6. An apparatus for generating a signal for controlling the flow of fuel in a carburetor to an induction passage, said apparatus comprising:

chamber means;

yieldable wall means dividing said chamber means into a signal compartment and a fuel compartment;

means transmitting to said signal compartment a flow of fluid from a chamber of an engine, which chamber communicates with an engine piston, with said fluid having pulses therein and being under a pressure exceeding ambient pressure and isolated from said induction passage;

vent means for continuously venting said fluid from said signal compartment while maintaining said compartment under a pressure exceeding ambient pressure; and

means including said vent means for maintaining a substantially steady state pressure in said signal compartment in response to a particular operating speed and throttle condition of said engine.

References Cited UNITED STATES PATENTS 3,037,751 6/1962 Phillips 26135 3,181,843 5/1965 Brown et al. 261-67 3,201,096 8/1965 Barr 123119 XR JULIUS E. WEST, Primary Examiner.

US. Cl. X.R.

@33 3 UNITED STATES PATENT OFFICE (IERTIFICATE 0F CORRECTION Patent No. 3 44l, O10 Dated Ap l 1 Inventor(s) EDWARD J. BARR ET AL It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

in column 2, between

lines

34 and 35, insert the following paragraph:

- A further and individually significant apparatus facet of the invention involves structure by means of which superambient crankcase pulses may be employed to b oth pressurize and pump fuel through a carburetor and control the flow of this pumped fluid to a carburetor air passage in response to engine operalng conditions.

In addition, in column 7, line 74, the word "a" following on" should be deleted.

SIGNED AND SEMEQ fittest:

mum: E. seems: Atieshng Officer W Commissioner of Patents