US1933388A - Carburetor - Google Patents

Description

Filed Jan. 5, 1951 F. INVENTOR.

fg. 5 ./lugus/'n M ,Dre/079155 ATTORNEY Patented Oct. 3l, 1933 UNITED STATES PATENT Trice CARBURETOR Application January 5, 1931. Serial No.y 506,688

' 13 claims. (Cl. zei- 34) 'Ihis invention relates to carburetors for mo,- bile internal combustion engines andmore particularly has reference to acceleration pumps and temperature controls therefor.

It has long been known in the carburetor art that in order to obtain powerful and rapid acceleration of an internal combustion engine it is necessary to temporarily enrich the mixture as the throttle is suddenly opened to counteract the diluting effect of the suddenly increased air g :How and drop in suction on the main fuel jet.

It is further known that the temporary enrichment of the mixture should be prolonged enough to enable the motor to gain suilcient speed to bring the main fuel jet into full action,

and several devices have been proposed to accomplish this result.

Moreover, it is now generally appreciatedy that a far leaner mixture is required to properly accelerate when the engine is warm than when cold. In fact, I have found that after the engine has warmed up to a certain temperature enrichment of the mixture is not only unnecessary for acceleration, but is a positivey detriment thereto.

Attempts have been made to somewhat reduce the acceleration charge as the temperature increases by the use of thermostatically controlled valves which partially relieve the air pressure on the acceleration `charge as the temperature rises. The diiculty with such devices is that they do not reduce the acceleration charge in direct proportion with the increase in temperature and they have heretofore been applied only to acceleration devices which effect a momentary enrichment which is never prolonged until the engine gains the desired speed.

So far as I am aware noone has yet devised an acceleration pump which gives a prolonged enriching charge and at the same time regulates this charge in proportion to the temperature.

The principal object of this invention is to produce an acceleration device whichwill deliver a prolonged enriching charge that is reduced in direct proportion as the temperature is increased.

Another object of this invention is to accomplish the foregoing result by automatic means without employing metallic thermostatic elements.

A still further object of this invention is to devise an accelerationpumpthat delivers an enriching charge that is in proportion to the degree of opening of the throttle and to the temperature of the carburetor.

With lthese and other objects in view which able connections (not shown).

may be incident to my improvements, my invention consists in the combination and arrangement of elements as hereinafter described and illustrated in the accompanying drawing in which:

Figure 1 is a cross sectional view of a carubur- 60 tor embodying vmy improvements, showing the elements arranged in one plane for the purposes of illustration. Obviously the parts might be arranged more advantageously;

Figure 2 is afragmentary side elevation of the 65 throttle shaft showing the acceleration pump arm;

Figure 3 is a fragmentary sectional view, on an enlarged scale, of the check valve at the bottom of the compression cylinder;

Figure 4 is a front elevational view, on an enlarged scale, of the check valve near the bottom of the pump cylinder;

Figure 5 is a sectional view of same along the line 5-5 of Figure 4; and 75 Figure 6 is a sectional view, on an enlarged scale, of the check valve between the float cham- -ber and acceleration pump cylinder.

Referring particularly to Figure 1, the reference numeral l denotes the body of the carburetor to the lower part of which is xedly attached a oat bowl 2 and compression chamber 3 by suitablebolts, screws or other conventional means (not shown). The body l is provided with the usual air inlet 4, Venturi throat 5, and mixture outlet 6, the last being controlled by a butterfly throttle valve 7 mounted on a shaft 8 which is journalled in the Walls of the mixture outlet 6. On one end of the throttle shaft 8 is fixed an operating lever 9 which is operated by 90 the accelerator pedal of the automobile by suit- On the other end of the shaft 8 is fixed an arm 10 which carries at its free end a roller 11 which' in turn contacts with the head of a hollow stem 12 as clearly 95 shown in Figuresy 1 and 2.

Cast integral with the body 1 of the carburetor is a tubular well 13 which functions as the cylinder of an acceleration pump. Within the cylinder 13 is arranged a piston 14 threaded upon a piston rod 15 which passes through a stufng box 16 into the compression chamber 3. Piston rod 1,5 carries at its lower end a second piston 17 which is also adjustably mounted by threading on rod 15 and is secured by a lock nut 18. Sur- 105 rounding the rod 15 above piston 14 is a helical spring 19 which bears at its lower end upon piston 14 and at its upper end upon the lower face of the stem 12. Below piston 14 is a second helical spring 20 bearing at its upper end against 110 vlili against the bottom of cylinder 13. Springs 19 and 20 are thus opposed in reaction and tend to move piston 14 in opposite directions. Spring 19 is made stronger and normally overcomes the force of spring 20 until the latter is aided by the compression developed in cylinder 3 by piston 17, as will be more fully explained hereinafter;

The piston 14 has a small passageway 21 bored through from onev side to the other to permit liquid fuel to pass' slowly from the lower part of cylinder 13, below piston 14, to the upper part above the piston, thus allowing the piston to descend slowly withoutl expelling liquid fuel from cylinder 13. The upper end of cylinder 13 is closed by 'a sleeve nut 22 which acts as a guide for stem 12. Cylinder 13 communicates with float bowl 2 through a passageway 23 which is provided with a check valve 24 permitting the free owof liquid fuel from bowl 3 to cylinder 13 but preventing any return ow, as clearly shown in Figure 6.

Near the bottom of cylinder 13 is a ball check valve 25 which permits the escape of liquid fuel from cylinder 13 after a certain predetermined pressure has been developed by piston 14, but prevents any return flow back into cylinder 13. Check valve 25 is shown in detail in Figures 4 and 5 and consists of a ball 26 which seats in a conical groove 27 in the wall of cylinder 13. This ball is normally held to its seat by a spring 28, the tension of which is adjusted by screw 29 threaded in the apex of a 3-arm spider 30 which is attached to the wall of cylinder 13 by suitable screws 31. The tension of spring 28 is so adjusted by screw 29 that ball 26 will not lift from its seat by such a pressure as is developed in ,cylinder 13 by the slow descent of piston 14, but is immediately lifted by the higher pressure developed by the quick descent of piston 14 when throttle 7 is suddenly opened. Thus when the throttle 7 is slowly opened no liquid fuel escapes rom cylinder 13 but merely surges through the passageway 21 to the'space above piston 14 andreturns the same way when the piston rises again. In order to permit the free escape of air from the cylinderv 13 above piston 14, the lower ange of stem 12 is provided with a plurality of.

notches 32 and sleeve nut 22 has a passageway l33 to the outside ofthe carburetor.

Cast in the body 1 'ofthe carburetor between the float bowl 2 and cylinder 13 is a surge chamber 34 which is completely closed except for an entrance port 35, controlled by check valve 25, and an exit port 36 which communicates through a passageway 37 and restricted orifice 38 with the mixing chamber of the carburetor. The purpose of the surge chamber is to prolong the pressure of the piston 14 which is accomplished by the cushioning effect of the air and liquid fuel vapor which is trapped and compressed in the upper part of chamber 34 when piston 14 suddenly descends and expels the liquid fuel from cylinder 13. It will be noted that port 35 is much larger than the restricted orifice 38 at the end of outlet passageway 37. Hence when piston 14 suddenly descends the liquid fuel is forced into chamber 34 at a much faster rate than it can escape through orice 38. It, therefore, collects in chamber 34,1rises therein and compresses the entrapped air and liquid fuel vapor. The pressure thus developed continues tov message 0the lower face of piston 14 and at its lower end' and this pressure causes the liquid fuel to continue to dow out through orince 33 until chamber 34 is cleared. This action considerably prolongs the period of discharge of the acceleration charge. p

In order to regulate the amount of accelerating charge in accordance with the temperature Aof the carburetor, chamber 3 is provided. This chamber communicates with float bowl 2 through passageway 39 which is normally closed at its lower end by a ball check valve 40 and at its upper end by a manually operated needle valve 41. Ball check valve 40 is shown in detail in Figure 3 and consists of a'ball 51 which seats on a bushing 42 screwed into the walls of passageway 39. Ball 51 is held to its seat by a light 'spring 52 which is adjusted by step bushing 43. The force of spring 52` is adjusted to just overcome the weight of .ball 51 and hold it to its seat as long as the pressure in chamber 3 does not fall below that inthe oat bowl which is maintained under atmospheric pressure by vent 44. When 'the pressure in chamber 3 falls to a point where it is equal to, or less than, the atmospheric pressure in float bowl 2, then the weight of the liquid fuel column in passageway 39 is sumcient to overcome the force of spring 52 and ball 51 falls away from its seat, opening valve 40, provided, of course,

that valve 41 is open which is habitually the case when the carburetor is in operation.

From the foregoing disclosure it is clear that whenever the pressure in chamber 3is equal to or less than that in float bowl 2, liquid fuel will iiow from the latter into the former until the pressures are substantially equal when valve 40 will close and hold in c I ber 3 whatever liquid fuel has thus entered. v

' n. 3- is intended to always hold a small amount of liquid fuel which will usually be almost e wholly in the vapor phase except at very low temperatures, and the size and length of chamber 3 is made such that if no liquid fuelwere present, but only air, when piston 17 is ln its uppermost position, the pressure of this air would beso reduced as to fall below the atmospheric pressurein bowl 2, so that valve 40 would open and allow some liquid fuel to flow into chamber 3. This result is secured by reason of the difference in vapor pressure between air and liquid fuel in the vapor phase. As all commercial liquid fuel (gasoline) contains some entrained air,` there will always be some air lcarried into chamber 3 with the liquid fuel, so that the contents of this chamber will consist of a mixture of air and fuel vapor together with some fuel liquid. The amount of liquid fuel in vapor phase and the consequent pressure de-l spring 20 equals the force applied by spring 19.

When this point is reached further downward thrust of stem l2 by arm l0 results in no further movement of piston 1.4 but simply in a compression of spring 19 which remains so compressed until the thrust on stem 12 is relieved by the upward movement of 10.

The pe in ch er 3 thus serves to regulate the downward travel of piston 14 strictly in accordance with the temperature -of the carburetor, as the vapor pressure of liquid fuel is a linear function of temperature within the ton 17 is such as to oer little or no compression to any air or vapor which may collect in chamber 3 in the .space above the piston, but rather to return any such air or vapor to the space below the piston.

A float 45 in bowl 2 normally` maintains the liquid level constant at the height shown by the line X-X in the conventional manner and the bowl is also supplied with liquid fuel from a main supply tank by the usual supply pipe (not shown). Bowl 2 communicates with a main fuel nozzle 46 through opening 47 in the base thereof.

The operation of my device is as follows: when the carburetor is not in operation the throttle is held closed by a spring on the accelerator pedal (not shown). The armv 10 is then in a horizontal position and the piston 14 at the top of its stroke by reason of the pressure from spring 20- and the absence of superior pressure on spring 19. If now the throttle 7 is suddenly opened and the engine is cold, the piston 14 quickly descends unchecked by piston 17 until it reaches a point well down in its stroke. It thus expels a relatively large charge of accelerating fuel which passes quickly into chamber 34 where it compresses the entrapped air and vapor which in turn, subsequently expands and forces the fuel outinto the mixing chamber of the carburetor in a prolonged stream.

If, on the other hand,I the throttle 7 is suddenly opened while the engine is hot, piston 14 is checked by piston 17 early in its stroke and little or no acceleration fuel is delivered to the mixing chamber.

From the above description it is clear that the same general effect would be obtained if any gas were used in chamber 3 which has a vapor pressure sufiiciently high at the normal operating temperature range of the carburetor and this vapor pressure were substantially a linear function of the temperature.' Thus air alone in chamber 3 could be used to control the stroke of piston 14 in accordance with the temperature of the carburetor, but since liquid fuel has a higher vapor pressure than air, it is easier to secure the desired regulation, and it is to be preferred to air alone.

While I have shown and described the preferred embodiment of my invention, I desire it to be understood that I do not limit myself to the constructional details shown by way of illustration as these may be modified in combination and arrangement by those skilled in the art without departing from the spirit of my invention or exceeding the scope of the appended claims.

I claim: f

1. In a carburetor, an acceleration pump, means for actuating saidpump, said pump comprising temperature controlled pneumatic means for regulating the length of stroke of said pump and pneumatic means for prolonging the output of said pump beyond the completion of its stroke.

2. In a. carburetor having a liquid fuel float chamber, an acceleration pump and a pneumatic regulating cylinder supplied with liquid fuel from said chamber for controlling the stroke of the pump.

3. In a carburetor, an acceleration pump comprising a reciprocable member, yielding means for reciprocating said member, a chamber supplied with a volatile fluid, and a piston in said chamber connected to said reciprocable member to control the stroke thereof in accordance with the temperature of the fluid.

4. In a carburetor having a throttle, an acceleration pump comprising a reciprocable member adapted to force a charge of fuel to the carburetor, a yielding connection between the throttle and the reciprocable member, a chamber containing a volatile fluid, a piston in said chamber connected to the reciprocable member to control the stroke thereof in accordancel withv the temperature of the fluid, and pneumatic means for prolonging the discharge of the pumpv beyond the completion of its stroke.

5. In a carburetor having a throttle, a liquid fuel acceleration pump, means for actuating said pump in accordance with the movement of the throttle, said pump comprising pneumatic-means for automatically regulating the length of stroke of said pump in accordance with the temperature of the liquid fuel. 1

6. In a carburetor having a throttle, a liquid fuel acceleration pump, means for actuating said pump in-accordance with the movement of said throttle, and means, comprising a pneumatic chamber containing a temperature-responsive expansible fluid, for regulating the length of stroke of said pump in accordance with the temperature of the liquid fuel.

'7. In a-carburetor, a liquid fuel acceleration pump comprising a reciprocable member, means for reciprocating said member, and temperatureresponsive means for varying the stroke of said member in accordance with the temperature of the liquid fuel. l

8. In a carburetor having a liquid fuel reservoir, an acceleration pump comprising a reciprocable member, and pneumatic meansv for regulating the length of stroke of said pump in accordance with the temperature thereof, including a chamber supplied with fuel from said reservoir through a passage completely closed during the power stroke of said member.

9. In a. carburetor having a fuel reservoir and a mixing chamber, a liquid fuel acceleration device comprising a reciprocable member, means to deliver to said mixing chamber a predetermined amount of accelerating charge at a predetermined low temperature, and means for gradually decreasing the length of stroke of said member in proportion to the increase in temperature of said fuel, including a chamber supplied with fuel from said reservoir through a passage completely closed during the power stroke of said member.

l0. In a carburetor having a fuel reservoir and a mixing chamber, a liquid fuel acceleration device comprising a reciprocable member, means to deliver to said mixing chamber a predetermined amount of accelerating charge at a predeterminedk low temperature, and means for graduallyl decreasing said charge in proportion to the increase in temperature of said fuel until saldcharge is reduced to zero at a pretermined higher temperature, including a chamber supplied `with fuel from said reservoir throughv a passagel completely closed during the power stroke of said member.

l1. In a carburetor having a fuel reservoir, an acceleration pump comprising a reciprocable member, and pneumatic means for controlling the length of stroke of said member, and for prolonging the time of output of said pump, including a chamber supplied with fuel from said reservoir through a passage completely closed during the power stroke of said member.

l2. In a carburetor having a fioat reservoir, an acceleration pump comprising a reciprocable member, pneumatic means, including a chamber completely closed during the power 'stroke of said ipeaaae pump ,comprising a reciprocable member, a

chamber completely closed during the power stroke'of said member for automatically regulating the stroke of said member in accordance with .the temperature of said fuel, means for supplying a temperature-responsive expansible iuid` to said chamber, and means for controlling said supply by the vapor pressure of said uid AUGUSTIN M. PREN'rrss.

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