US2754185A - Controlled gaseous fuel feed system for internal combustion engines - Google Patents

Description

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R. F. ENSIGN INTERNAL COMBUSTION ENGINES CONTROLLED GASEOUS FUEL FEED SYSTEM FOR Q. Y R m w N 2 m m N T 1 3 A v m B i p. k \l 7 July 10, 1956 Filed Jan. 6, 1953 CONTROLLED cAsE'o Filed Jan. 6, 1953 R F. ENSIGN US FUEL FEED SYSTEM FOR INTERNAL COMBUSTION ENGINES 2 Sheets-Sheet 2 W L, if

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INVENTOR.

BY v ism Q Siam ATTOE/VE Ys QGNTRGLLED GASEOUS FUEL FEED SYSTEM FQR INTERNAL COPVIBUSTION ENGINES Roy F. Ensign, San Marino, Calif., assignor to Ensign Carburetor Company, Huntington Park, Calif a corporation of California Application January 6, 1953, Serial No. 329,870

11 Claims. (Cl. 48-184) This invention relates to certain improvements in the gaseous fuel feed system of the Roy F. Ensign Patent 2,073,299; relating more particularly to controls for providing suitable fuel mixtures for starting and idling and for other operating conditions. The improvements constituting the invention will be best understood from the following descriptions and discussion of typical and illustrative embodiments of the invention. Reference for that purpose is had to the accompanying drawings, wherein Figs. 1, 2, 3 and 4 are schematic sections showing several typical and illustrative embodiments; and

Fig. la is a detail section on line a-a of Fig. 1.

Fig. 1 shows in schematic section a typical illustrative embodiment of the invention. In that view the essentials of a typical carburetor fed by a typical fuel pressure regulator are shown. The carburetor has air intake (which may or may not be provided with an air cleaner or other obstruction), a venturi throat 11, a throttle 12, and is connected beyond the throttle to engine intake manifold 13. A pitot tube picks up the total air pressure in the air inlet, and the fuel supply nozzle 17 delivers to the venturi throat. Tube 22 connects between the port 19, on the down-stream side of the throttle, and the passage 54.

The regulator shown here is of the type of the Ensign Patent No. 2,073,299. Its initial pressure intake 30 is controlled by the pressure regulating valve 32 which, under control of regulating diaphragm 34, regulates the pressure in the outlet or delivery chamber 36 which delivers directly to fuel nozzle 17. As shown illustratively, valve 32 closes against the pressure in the inlet and a spring 38 exerts a closing force on the valve sufi'icient to hold it closed by a pressure which in practice is commonly set to be equal to a pressure of about one-quarter inch of water on the elfective area of diaphragm 34. In other words, it takes a pressure of about A water in a valve opening direction on the diaphragm to balance the valve or to just open it. Pivoted valve lever 40 connects the valve and diaphragm so that movement of the diaphragm into or toward its diaphragm chamber 37 opens the valve while movement into or toward its reference chamber 42 closes the valve. Reference chamber 42 is supplied with the air intake pressure from pitot tube 15 via balance tube connection 24. In the absence of a cleaner or other obstruction on the air intake, that pressure will be atmospheric; in any case it will be the efiective total pressure present at the entrance to the venturi. Diaphragm chamber 37 here effectively forms a restrictedly connected part of delivery chamber 36; separated from that chamber 36 by a wall 44 and restrictedly connected to it, conveniently by the opening 46 through which valve lever 40 passes loosely. In previous systems-see for example the Ensign patent mentioned above-pressure modifications have been applied from the intake manifold to the isolated diaphragm chamber 37 to lower the pressure there and thus cause diaphragm movement in the direction to open valve 32 and raise the pressure in delivery chamber 36, for instance during idling atent operation of the engine when throtfle 12 is closed and the depression in the intake manifold is high. The present invention controllably applies the manifold depression effectively for starting operations as well as for idling, etc.; and applies the manifold depression under the automatic control of a diaphragm actuated valvular system so associated with the other parts of the regulator as to raise and maintain the delivery pressure to and at a point above what it otherwise would be; in this case main taining it approximately equal to the reference pressure.

In the illustrative form of the invention shown in Fig. l, a second, auxiliary, diaphragm 50 is mounted in the casing structure of the regulator so as to be exposed on one face to the pressure in delivery chamber 36 and on its opposite face to the reference pressure, from pitot tube 15, in reference chamber 52.

A passage 54 has a valve seat 56 which can be closed by valve 58 which is part of lever 60 pivoted in the structure at 62. When valve 58 is open, passage 54 is opened to passage 64 leading to diaphragm chamber 37. Valve lever 60 is connected to auxiliary diaphragm 50 so that movement of the diaphragm toward or into delivery chamber 36 opens the valve 58. Suction from the manifold acting through passage 54 on the valve 58 tends to close the valve; that is, excess of pressure on the under face of the valve over the pressure on its upper face tends to close the valve. The pressure on the under face of the valve is, in general, that obtaining in diaphragm chamber 37 and passage 64. See Fig. 1a which shows that the space or valve chamber 66, in the piece 68 which encloses a passage or chamber around the valve between the passages 54 and 64, and which forms the lower fulcrum support at 62 for the valve lever, is in open communication with passage 64. The valve lever is shown as fulcrummed between a lower support 62 on part 68 and an upper support 70 on the casing portion that forms the wall of passage 64. There is of course some leakage through the space around the valve lever where it passes between its fulcrum supports, and therefore always some leakage between delivery chamber 36 and the valve chamber 66 and passage 64 which is open to 66. That leakage, together with the leakage at 46, tends to equalize the pressures between 36 and 37 when valve 58 is closed.

A light spring 71 merely insures that valve lever 60 follows the movements of diaphragm 50. An adjustable spring 72 presses diaphragm 50 in the direction tending to open valve 58. The resultant of both springs 71 and 72 is to hold valve 58 and diaphragm 50 substantially in balance when the system is standing with equal pressures on the opposite diaphragm faces, or to slightly bias valve 58 open.

On turning over the engine to start there is a relative pressure drop, although very small, at the venturi throat compared with the reference pressures in reference chambers 42 and 52. That relative pressure drop, acting on diaphragm 50, opens valve 58 wide, or holds it open wide. With that valve wide open, the full elfect of the intake manifold depression is applied to diaphragm chamber 37. The manifold depression developed on starting turn-over with throttle closed or partially closed is considerably greater than a quarter inch of water, usually amounting to at least a few inches. That depression applied through the wide open valve 58 to diaphragm chamber 37, will drop the pressure in that chamber by the quarter inch or so that is required to put the main valve system just in balance or to positively open that valve and to bring the discharge pressure in 36 up to the reference pressure required for starting.

On going into idling operation with throttle 12 closed down, the manifold depression increases very greatly while the venturi-throat depression increases very little.

The suction force on the valve 58 at seat 56 increases and tends to draw the valve closed, raising the pressure in 37,

lowering that in 36, and, thus, through action of diaphragm t) tending to balance the'closingforce on valve 58. Adjustments of idle mixture can then be made by adjusting the spring 72 so that the discharge pressure in 36 is held, say, substantially equal to the reference pressure, but at something less than the discharge pressure during starting. During starting, with valve 58 wide open, a fair proportion of the fuel for starting will be drawn through 22 directly to the manifold when the discharge pressure in 36 is atmospheric or more. During idling, with valve 58 partially open some fuel will still be drawn direct tothe manifold; and then to provide the proper idling mixture the discharge pressure in 36 may properly be slightly less than atmospheric or the reference pressure.

In all ordinary ranges of engine operation other than idling, the venturi throat depression becomes relatively large and the modification of the pressure in 36 by the valve 58 becomes relatively small.

Fig. 2'shows another typical embodiment of the invention. One main difference over Fig. 1 is that here in Fig. 2 the valvular application of manifold depression to the main diaphragm chamber is by valvular control of a bypass. Also there is here, along with certain other variational details of structure and function, an automatic restriction of the orifice limiting fuel flow directly into the manifold at higher manifold depressions, said restriction being in addition to that imposed by the action of valve 58 or its equivalent.

In this figure main diaphragm 34a has reference cham ber 42a on one'face and diaphragm chamber 37a on the other, divided from discharge chamber 36a by partition 44a through which valve stem 40a passes loosely at 46a to provide a leak. Valve 32a here opens against the pressure in inlet 30, and that pressure and/or an addi tional spring may provide the pressure by which the valve is normally seated and which diaphragm 34a must overcome to balance the valve and open it.

Auxiliary diaphragm 50a lies between a reference chamber 52a and another chamber 360 in which discharge pressure is maintained via the connective passage 566a. Except for their physical separation, chambers 36a and 360 are one in all effect; the effective action of delivery pressure on the diaphragms being the same as in Fig. l where the diaphragm 50 is directly exposed in delivery chamber 36. And here, the two reference pressure chambers 42a and 52a are physically one, separated only by the perforated partition 361a which acts merely as a stop for diaphragm 50a. The balancing pitot tube connects to both 42a and 52a. In this connection it may here be remarked'that in Fig. l the two reference chambers 42 and 52 are in all effect one chamber, interconnected as they are by tube 24.

The manifold connection 22 leads, through a calibrated orifice and a valvular device to be explained later, to a passage 54a that communicates openly with the diaphragm chamber 37a and also with a valve seat 56a whose passage is valvularly controlled by auxiliary diaphragmfitia which, acting as a valve, seats directly on valve seat 56a when discharge pressure in 360 falls with relation to the reference pressure in 5211. Spring 72a, adjustable in pressure, tends to keepdiaphragm 50a to the right and keep 56a open, but with a very light pressure so that a very slight drop in delivery pressure in 360 with relation to the reference pressure in 52a will tend to pull diaphragm Stia against valve seat 56 1.

In operation at turn-over for starting diaphragm 50a is pulled onto seat 56a by the drop in delivery pressure in 360. That valve closure causes the application of the manifold depression to main diaphragm chamber 37a, to drop the pressure there, to open valve 32a and raise the delivery pressure in 36a and360 .to approximately atmosphere-or to that obtaining in the reference chamber 42a, 52a. When that rise in pressure occurs the valve at 56a tends to open, with the result of tending to lower the discharge pressure. This same action of course takes place after the engine has started and the venturi depression and manifold depression are higher; and thus, in operation, the valvular action of diaphragm Siia is to tend to keep the delivery pressure in 36a and 36%) substantially equal to that in 42a, 52a.

Adjustment of spring 72a adjusts the idling mixture by adjusting the exact relation between the pressure in 36a and that in dirt. That correct adjusted pressure may be something less than atmospheric, in order to compensate for the leak ofifuel, through the leak 46a into 37a and thence through 54a and 22 tothe manifold.

The manifold connection 22 communicates with the passage 54a through one calibrated orifice 80 which is always open and also through another calibrated orifice 3 2 which, when the manifold suction exceeds a given figure, will be closed by the valve 84. When the manifold vacuum reaches, say, three inches of mercury, ball 84 is drawn up onto its seat 86 cutting off orifice 82 from the passage88 which communicates with 54a. Thus, at idling or at any normal operating range the single calibrated orifice 80 determines and limits the application of manifold depression to the regulator and limits the constant fuel flow which goes directly to the manifold. However, at starting turn-over when the manifold vacuum is less than the set amount, ball 84 will drop and open the second orifice 82 to the passages 88 and 54a; and thus provide for faster responses of the regulator to delivery pressure changes when starting.

The valve shown at 90 controls an opening through the partition dividing chamber 37a from 36a. Valve 90 is normally held closed by a light spring 92 and opens in the direction to allow flow from 37a to 36: but preventing reverse flow. Under some circumstances, as when the fuel demand at 17 is suddenly increased, the pressure in 36a may fall temporarily below that in 37a. Valve 90 then opens to allow quick fall of pressure in 37a, in order to accelerate the opening of valve 32a to raise the pressure in 36a.

Figs. 3 and 4 show other-modifications of structure and also show, as an additional element of the combination, a means for limiting the degree of manifold vacuum that is applied, under automatic control of the auxiliary diaphragm, to controllably modify the pressure regulating action of the main diaphragm. Utilization of a limited degree of the manifold suction is, in and of itself, the subject matter of a companion application, filed on December 9, 1952, Ser. No. 324,985, and is only claimed here in combination with automatic diaphragm control of its application to the main diaphragm.

In Fig. 3 the main diaphragm 34b is located between reference pressure chamber 42b and the diaphragm chamber 37b which is separated from delivery chamber 36b by the partition 44b through which the stem 40b of main regulating valve 32b passes with leakage at 4611. Valve 32b is here shown as opening against the initial inlet pressure in inlet passage, the same as explained for Fig. 2.

The auxiliary diaphragm 50b is exposed on one face to the delivery pressure in 36b and on its opposite face to the pressure in reference chamber 52b which is connected to reference chamber 42b by passage 1517, so that both chambers 42b and 52b have the reference pressure of pitot tube '15. Auxiliary diaphragm 50b is freely movable with slight differences of pressure between 15 and 17, and moves to the left in the figure when the delivery pressure at 17 and in 36b falls below that at 15 and in 52b. Moving in that .direction it pushes on and moves a valve pin 60b which, extending through partition 44]), pushes a light spring flap valve 58b, off its seat 56b. By doing so it opens the suction passage 54b through which manifold suction is applied to the diaphragm chamber 37b to lower the pressure there and .cause the diaphragm 34b to open valve 32b to raise thev delivery pressure. The

operation is the same as in Fig. 1, the delivery pressure being automatically kept up substantially to the reference pressure. If desired, a small valve formation 600 on valve stem 6% may be used to close the leak through partition 44b around 60b when valve 58b is moved open.

In Fig. 3 the connection 22, instead of going directly to passage 54b as in Fig. 1, goes to a passage 540 which delivers through a valve seat 541 into a chamber 542 from which passage 54b leads. A diaphragm 543 is subject on one face to the pressure in chamber 542 and on its opposite face to the delivery pressure in 36b. The diaphragm, by movement into chamber 542 can seat on valve seat 541, and is pressed in the opposite direction by a spring 544. The force exerted by spring 544 determines the measure of the maximum vacuum which will be maintained in 542 and applied via 54b to the diaphragm chamber 37b to modify the action of diaphragm 34b. Typically that maximum can be, say, a minus pressure of six inches of water, which is about the low limit of vacuum occuring in the manifold on turning over the engine to start with the throttle closed. The result of so limiting the measure of the maximum vacuum applicable to 37b under control of the auxiliary diaphragm is to relieve the valve 58b of the large variation in the suction force to which it would be subjected if its port 54b were directly connected to 22.

Fig. 4 shows a structure and arrangement similar to Fig. 1, but having some detail functions like those of Figs. 2 and 3. In Fig. 4 the parts which are the same as in Fig. 1 are given the same numerals.

The valve lever 40c, instead of extending through partition 44 engages a pin 400 which extends loosely through the partition and connects with the diaphragm. The partition has at least the one large hole through which the pin extends and that hole or holes are surrounded by a valve seat 910 on which a flat light valve 990 is lightly seated by forked spring 920. The valve structure and function are similar to those of valve 90 in Fig. 2. And the opening 460 in valve 900 through which pin 400 passes loosely will perform the same slow pressure equalizing functions between 36 and 37 as are performed by the similar leaks in Fig. 1 and the other designs.

In Fig. 4 the manifold connection 22 goes to a passage which ends in the downwardly facing valve seat 54b in a chamber 547. A vacuum limiting diaphragm 548 has its upper face exposed to the pressure in 547 and has a valve pad 549 on its upper face adapted to seat upwardly on valve seat 54b. The lower face of the diaphragm is exposed to the reference pressure from in the reference pressure chamber 550; and the diaphragm is pressed down by an adjustable spring 551 with a force which determines in general the maximum vacuum which will be maintained in chamber 547. The action in limiting the maximum vacuum which will be available for modifying application to diaphragm chamber 37 is similar to the action in Fig. 3 and to the action in the mentioned copending application to which reference may be had for detailed explanation. As mentioned in connection with Fig. 3, the spring will typically be set so as to keep valve 549 open for the manifold vacuum developed on turning over to start, but to close the valve down as soon as the engine starts operation.

The vacuum chamber 547 is in Fig. 4 connected via a calibrated orifice 800 and passage 540 directly with diaphragm chamber 37 and that chamber is controllably bled to the delivery chamber 36 by a valvular means operated by auxiliary diaphragm 50. The action in that regard is the same as in Fig. 2. Partition 44 has an opening in the form of a tube forming a valve seat 560. A pivoted counter-balanced valve 561 is operated by diaphragm 50 in such manner as to close the valve passage when diaphragm 50 moves up under the influence of delivery pressure dropping in 36. The action is the same as in Fig. 2, to maintain pressure in 36 substantially equal to the reference pressure. An adjustable spring 720 performs the same function as adjustable spring 72a in Fig. 2; tending to move diaphragm 50 in the direction which opens the valve 561. The arm of valve 561, and the end of spring 720, are both connected to diaphragm 50 by any suitable means that will cause the valve to move in both of about the same size. Such dimensions, however, are

not to be considered as limitations on the invention, as the sizes are not critical.

1 claim: 7

1. In a gaseous fuel feed system for internal combustion engines, the combination of a carburetor having a mixture passage with an air inlet, an outlet adapted for connection to the engine intake manifold and a venturi throat between the inlet and outlet, a gas pressure regulator comprising a pressure regulating valve controlling the flow of gas from an initial inlet to a delivery chamber which communicates with a fuel delivery nozzle at the venturi throat, a valve operating diaphragm having one face exposed to the pressure existent at the air intake, casing means forming a diaphragm chamber at the opposite face of the valve operating diaphragm in restricted communication with the delivery chamber, an auxiliary diaphragm with one face exposed to the pressure existent in the delivery chamber and its opposite face exposed to the pressure existent in the air intake, said auxiliary diaphragm floating in substantially free balance when said pressures on its opposite faces are equal, and means for applying intake manifold depression to the valve-operating diaphragm chamber, said means including valvular means operated by the auxiliary diaphragm to eifectively control the application of that depression.

2. The combination defined in claim 1 and in which the means for applying manifold depression includes orifice means of variable size, and means automatically to reduce the orifice size to a predetermined minimum when the manifold depression exceeds a predetermined amount.

3. The combination defined in claim 1 and in which the means for applying manifold depression includes a means acting automatically to limit the amount of said depression.

4. The combination defined in claim 1 and in which the valvular means directly controls the application of manifold depression to the valve-operating diaphragm chamber.

5. The combination defined in claim 4 and in which movement of the auxiliary diaphragm in a direction against the outlet pressure tends to open said valvular means, and including also an adjustable spring tending to move the diaphragm and valve in said opening direction.

6. The combination defined in claim 1 and in which there is a passage with a calibrated orifice leading from the carbureter outlet to the valve-operating diaphragm chamber, and in which the valvular means operated by the auxiliary diaphragm controls a communication between the valve-operating diaphragm chamber and the delivery chamber.

7. The combination defined in claim 6 and in which movement of the auxiliary diaphragm in a direction against the delivery chamber pressure tends to close said valvular means, and including also an adjustable spring tending to move the auxiliary diaphragm and said valvular means in an opening direction.

8. The combination defined in claim 1 in which the means for applying manifold depression includes means acting automatically to limit the amount of that depression, and in which the valvular means operated by the auxiliary diaphragm directly controls the application of the limited depression to the valve-operating diaphragm chamber, said valvular means opening when the auxiliary diaphragm moves in a direction against the delivery chamber pressure. 9. The combination defined in claim 8 andalso including a valvularly controlled communication passage between the valve-operating diaphragm chamber and the delivery chamber, and valvular means acting to close said communicating passage 'when the auxiliary diaphragm moves to open the depression controlling valve.

10. The combination defined in claim 1, in which the valvular means operated by the auxiliary diaphragm directly controls the application of the depression to the valve-operating diaphragm chamber, said valvular means opening when the auxiliary diaphragm moves in a direction against the delivery chamber pressure, and also including a valvularly controlled communication passage betweenrthe valve-operating diaphragm chamber and the delivery chamber, and valvular means acting to close said communicating passage when the auxiliary diaphragm moves to open the depression controlling valve.

11. The combination defined in claim l, and also including a valvularly controlled communication passage between the valve-operating diaphragm chamber and the delivery chamber, and valvular means actuated by the auxiliary diaphragm to close said communication passage when the first mentioned valvular means acts to apply the depression to the valve-operating diaphragm chamber.

References Citedin the file of this patent UNITED STATES PATENTS 2,340,954 Garretson Feb. 8, 1944 2,448,131 Williams Aug. 31, 1948 2,475,086 Ensign Iuly5, 1949 2,563,228 Ensign Aug; 7, 1951 2,597,335 Jones May 20, 1952

Claims (1)

1. IN A GASEOUS FUEL FEED SYSTEM FOR INTERNAL COMBUSTION ENGINES, THE COMBINATION OF A CARBURETOR HAVING A MIXTURE PASSAGE WITH AN AIR INLET, AN OUTLET ADAPTED FOR CONNECTION TO THE ENGINE INTAKE MANIFOLD AND A VENTURI THROAT BETWEEN THE INLET AND OUTLET, A GAS PRESSURE REGULATOR COMPRISING A PRESSURE REGULATING VALVE CONTROLLING THE FLOW OF GAS FROM AN INITIAL INLET TO A DELIVERY CHAMBER WHICH COMMUNICATES WITH A FUEL DELIVERY NOZZLE AT THE VENTURI THROAT, A VALVE OPERATING DIAPHRAGM HAVING ONE FACE EXPOSED TO THE PRESSURE EXISTENT AT THE AIR INTAKE, CASING MEANS FORMING A DIAPHRAGM CHAMBER AT THE OPPOSITE FACE OF THE VALVE OPERATING DIAPHRAGM IN RESTRICTED COMMUNICATION WITH THE DELIVERY CHAMBER, AN AUXILIARY DIAPHRAGM WITH ONE FACE EXPOSED TO THE PRESSURE EXISTENT IN THE DELIVERY CHAMBER AND ITS OPPOSITE FACE EXPOSED TO THE PRESSURE EXISTENT IN THE AIR INTAKE, SAID AUXILIARY DIAPHRAGM FLOATING IN SUBSTANTIALLY FREE BALANCE WHEN SAID PRESSURES ON ITS OPPOSITE FACES ARE EQUAL, AND MEANS FOR APPLYING INTAKE MANIFOLD DEPRESSION TO THE VALVE-OPERATING DIAPHRAGM CHAMBER, SAID MEANS INCLUDING VALVULAR MEANS OPERATED BY THE AUXILIARY DIAPHRAGM TO EFFECTIVELY CONTROL THE APPLICATION OF THAT DEPRESSION.

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