US 3068086 A
Description (OCR text may contain errors)
Dec. 11, 1962 R K ENSIGN ET AL 3,068,086
EQUALIZING SYSTEM FOR GASEOUS FUEL FEEDS FOR INTERNAL COMBUSTION ENGINES Filed Jan. 24, 1958 Ivrsurae 5,
Bay Id E1676, .E QM/IIY CIEA/SEAJ,
United States Patent Office Patented Dec. 11, 1962 3,068,936 EQUALIZING SYSTEM FQR GASEQUS FUEL FEEDS FOR INTERNAL CQMBUSTION EN- GENES Roy K. Ensign, Fullerton, and Ervin F. Jensen, Alhambra, Caliltl, assignors, by mesne assignments, to American Bosch Arma Corporation, a corporation of New York Filed Jan. 24, 15958, Ser. No. 711,052 2 Claims. (Cl. 48184) This invention concerns systems for maintaining the fuel and air mixture ratio, in gaseous fuel systems, at predetermined ratio figures at various engine speeds.
In a typical gaseous fuel feed system, a pressure regulator is employed to deliver gaseous fuel to the venturi of a carbureter at a predetermined pressure which is usually about equal to atmospheric pressure, or the pres sure existent at thecarbureter air intake. The pressure at which the regulator delivers depends upon the pressures exerted on the valve-and-diaphragm system of the delivery stage of the regulator. There may or may not be springs or other elements exerting constant forces on that system in directions to set the delivery pressure below or above the atmospheric pressure existent in the air intake. But the final control of the delivery pressure is commonly effected by a balance passage that applies the pressure existent in the carbureter air intake to the reference pressure chamber of the delivery stage diaphragm, to make the delivery pressure bear a constant or predetermined relation to the existent air intake pressure. That pressure varies considerably due to the use of air cleaners on the intake and also due to varying frictional and turbulence losses at varying air speeds through the intake.
Although that pressure controlling system may be, in theory, perfect in operation to keep the fuel delivery pressure constant with relation to the air intake pressure, certain serious difficulties arise in connection with certain types of engines operated through ranges of speed and of throttle opening. As an example, these difficulties are pronounced in some ranges and conditions of operation in connection with some four cylinder engines, and perhaps particularly those in which there is rather large overlap between the open phases of the intake and exhaust valves. Due, apparently to pulsing variations of the air pressure in the air intake, the pressure applied via the balance passage to the reference chamber, and/ or applied to the regulator delivery chamber via the fuel feed passage connecting into the air passage, tendsin some instances to build up, and in others to drop, in certain ranges of engine operation; with the result that the delivery pressure builds up and the fuel and air mixture becomes too rich, or that pressure drops and the mixture becomes too lean. These pressure pulsations and resultant rise or drop in the fuel delivery are increased and aggravated by the length and size of the air intake passage and air cleaner. The precise reason for the changes in delivery pressure due to the pulsations is somewhat obscure. One possible explanatory theory of the cause of the difliculty is that resonant waves are set up in the intake and connected passages; but we do not intend that the invention should be limited by any such theory. It is the general object of the present invention to overcome such pressure changes.
The invention does that by locating a highly sensitive, and preferably unloaded, pulsation responsive check valve in, for example, the balance passage, accompanied by asmall by-pass bleed. In some installations the valve is installed to open in the direction from the reference chamber to the air intake so as to act, during the low pressure phases of excessive pulsation occurring at certain engine ranges, to prevent the reference chamber pressure from risingthat is, to lower that pressure relative to what it otherwise would be. In other installations the sensitive valve opens in the direction from the air intake to the reference pressure chamber, so as to prevent the pressure in that chamber from falling-that is, to keep that pressure higher than it otherwise would be. And in those installations it has been found that in some instances the most highly effective results through all engine ranges are attained by also employing a relief valve discharging from the reference pressure chamber to a fixed pressure, e.g. atmospheric, to limit the' pressure in the chamber.
Typical illustrative embodiments of the invention are described in the following and shown in the accompanying drawings, in which:
FIG. 1 is a schematic view showing how the invention is applied to a typical fuel feed system;
FIG. 2 is an enlarged sectional detail of certain parts shown in FIG. 1;
FIG. 2a is a similar sectional detail showing a modification;
FIG. 3 is a section on line 33 of FIG. 2;
FIGURE 3a is a section on line Zia-3a of FIGURE 2;
FIG. 4 is a fragmentary section showing another modification;
FIG. 4a is a fragmentary section showing a modification of FIG. 4; and
FIG. 5 is a fragmentary elevation showing the valves of FIGS. 4 and 4a.
In the drawings, a typical carbureter is shown with air intake 10 (which may or may not be equipped with an air cleaner), venturi l2, throttle l4 and connection at 16 with the engine intake manifold 18. The fuel pressure regulator 20 may be single or multiple stage, here shown illustratively as two-stage.
Fuel under pressure enters the first stage via pipe 22, controlled by first stage valve 24 operated by diaphragm 26 which typically has a reference pressure spring 28 set to maintain a typical pressure of 8-10 p.s.i. in first stage chamber 34 The second, or delivery stage has diaphragm 32 operating valve 34 controlling admission of fuel from first stage chamber 30 to delivery chamber 36. The connection, as by lever 38, between diaphragm 32 and valve 34 is such that movement of the diaphragm into chamber 36 (to the right in the drawing) causes valve 34 to open, while diaphragm movement in the opposite direction into reference pressure chamber 40 (to the left in the drawing) causes valve 3 to close. The valve-diaphragm system may be biased in a valve closing direction by e.g. a biasing spring 42 if it is desired to have valve 34 open at a pressure in 36 somewhat lower than the pressure in reference pressure chamber 4%. But, whether or not such a bias is used, the pressure maintained in delivery chamber 36 depends on the pressure in reference chamber 40. Increase or decrease of pressure in 40 correspondingly increases or decreases the delivery pressure in 36.
Delivery chamber 36 delivers to the venturi throat via tube 42. The balance tube 44 is typical of the balance passages that pick up the total pressure in air intake 10 and communicate that pressure directly to reference pressure chamber 443. The present invention places certain valvular controls in the balance passage, as now described.
Referring first to FIG. 2, balance tube 44 communicates with a small chamber 46 formed in a structure 4-8 preferably cast integrally with cover plate 50 that forms the outer wall of reference chamber at In chamber 46, a valve structure 52 controls communication of the balance tube with reference chamber 49. As here shown in illustrative form, valve structure 52 comprises a hollow body 54 with a valve seat 56 surrounding a passage 58 that leads from chamber 46 to the interior of 54. Spacedly opposed (.3 to valve seat 56 is a valve limiting seat 60 surrounding a passage 62 that leads from the interior of 54 to reference chamber 40. Seat 60 and passage 62 are formed in a disk 64 press-fitted into 54 and having openings 66 which freely intercommunicate reference chamber 40 with the interior of 54.
A thin light-weight disk valve closure 70 lies freely between valve seat 56 and limiting seat 60, floating freely to move onto either seat. This disk valve may be composed of thin light-weight plastic. It fits the interior chamber of 54 loosely and is edge-notched as shown for example at 72 in FIG. 3a to allow free fluid passage from one side of the closure to the other in the interior chamber of 54. Valve closure 70 has a small central perforation 74 which forms, in effect, a restricted open passage by-passing the valve. This valve closure has no loading in either direction; and in the position of usual installation it stands in a vertical plane so that it is not moved in either direction even by its own slight weight.
The operation of the valvular device as so far described is as follows. In normal operation the balance connection 44 keeps the pressure in reference chamber 40 the same as in intake 10. Normally, the pressures on opposite sides of valve closure 70 are equal. When pressure pulsations occur in intake 10, closure 70 moves to the right away from seat 56 during the high pressure phases of the pulsations. In that position the valve is open to the full capacity of the balance tube and air under the higher pressure moves freely through 53, through the interior of 54 past the valve edge and thence through 66 into reference chamber 40. On the low pressure phases, closure 70 moves to the left onto seat 56. In that position communication between reference chamber 49 and air intake is cut off except for the small bleed that flows through the by-pass opening 74. The result is that pressure in reference chamber 4% follows, at a somewhat lower pressure, the general pressure changes of the pressure peak phases of the pulsations in 10, and is consequently somewhat higher than its average would be if 44 were directly connected with 40. How much higher that reference pressure is, is controlled by the relative sizes of the passages.
As an example, on one type of four cylinder engine we found that in the operating range at relatively low speed with open throttle, the fuel mixture became much too lean, due to pressures in the reference and delivery chambers becoming too low. In that installation the balance tube was .25 inch internal diameter. That difliculty was largely overcome by installing a valvular system such as shown in FIG. 2, with a bypass bleeder opening 74 of r 0.11 inch in diameter. The extremely light weight of the valve closure and its free floating action Without any loading in either direction are important to the results attained.
Further beneficial results are had by positively limiting the pressure increase in the reference chamber, and FIG. 2 shows our preferred means of doing that.
A valve seat 86 is formed around a passage 82 leading through cover plate 50. A cover member 84 is secured to plate 50, with a circular chamber 36 at its inner face. A limiting valve seat 83 is formed on the inner face, and a light-weight thin closure disk 90 floats freely between seats 80 and 88. This valve closure is like the closure 7i previously explained except that it has no central opening. A passage 92 leads from chamber 86 to a zone of constant pressure, for example to atmosphere, protected from dust by the overhanging wall 94.
If the pressure in reference chamber 40, and consequently in delivery chamber 36, builds up above atmospheric valve closure 99 moves olf seat 80, and the pressure is then relieved, down to the constant pressure, by flow through 82, around 90 and out through 92. At any pressure below the constant pressure, in 40, closure 90 moves immediately onto seat 80, and the pressure in is then controlled solely by the valve-controlled balance tube.
As mentioned before, in some installations the pressures in reference chamber 40 and delivery chamber 36 tend to become too high at certain ranges of engine operation, resulting in mixtures too rich. To correct that tendency in such installations, the balance control valve is arranged as shown in FIG. 2a. The valve structure there shown is similar to that of FIG. 2 and the similar parts are given the same numerals. Here however the seat 60 in disk 64 is the valve seat proper, while seat 56 is the valve limiting seat; and openings 66a through the wall of valve body 54 replace the openings 66 of FIG. 2. This valve thus opens in the direction from reference chamber 40 to the air intake, closing in the opposite direction. In operation, this valve opens to relieve the pressure in 40 during the low pressure phases of the pressure pulsations in the air intake, and closes during the high pressure phases. The pressure in 46 is thus held at something less than what it otherwise would be and thus providing a leaner mixture. The bleed at 74 passes air slowly into reference chamber 49 during the high pressure phases of pulsation, thus tending, as in FIG. 2, to smooth out the pressure curve in 40 and making that pressure follow the general pressure changes in the air intake, at a pressure somewhat above the low pressure phases.
FIG. 4 shows a further modification in which the valve controls a passage through the diaphragm-that is, a pas sage between the delivery chamber 36 and the reference pressure chamber 49 and balance passage 44. In this form of the invention the valve controls a passage that includes the delivery tube 42 and the delivery chamber 36, leading from the air and mixture passage at the venturi, and the opening through the diaphragm.
As shown here a light thin flap valve closure 100- typically of thin sheet plasticis attached at one end to diaphragm 32, as by rivets shown at 102. This valve closure controls an opening 104 through the diaphragm, normally lying flatly on the diaphragm face and moving freely, to the left in FIG. 4, to open the passage 194. The valve may have a small by-pass opening 106 similar to the opening 74 in valve 70. The material of the valve, and its mounting, are such that it is substantially un-biased in either direction.
On intake pulsations reaching the reference chamber 40 valve 10% opens on the low peaks to pass fluid from 36 to 4d to build up the pressure in 40 and consequently to raise the delivery pressure in 36, in case where otherwise the delivery pressure in 36 is too low.
On the other hand, to correct a condition of too high pressure in 36, the valve 106 may be mounted on the opposite face of the diaphragm as shown in FIG. 4a, to open on the high peak phases communicated to balance chamber 40, and thus to reduce the pressure in 40 and consequently also in 36.
1. In gaseous fuel feed systems for internal combustion engines comprising a carbureter having an air and mixture passage with an air intake, a venturi throat and connection to the engine intake manifold, a gas pressure regulator having a delivery chamber, a gas delivery passage from said delivery chamber to the venturi throat, a pressure controlling diaphragm-valve system associated with the delivery chamber, one face of the diaphragm being exposed to the pressure in the delivery chamber, a pressure establishing reference chamber at the face of the diaphragm opposite said one face and wherein variations of pressure cause corresponding variations of pressure in the delivery chamber, and a balance passage connecting the air intake of the carbureter with said reference chains ber normally maintaining pressure in said reference chamber equal to that in the air intake; improvement means preventing pressure pulsations which occur in said air intake and are communicated by the balance passage to the reference chamber from causing the pressure in said reference chamber to vary from its normal equality to that in the air intake, said means comprising a check valve controlling said balance passage and providing relatively free communication between the air intake and said reference chamber in one direction only, said check valve having a thin valve closure member of light weight, substantially non-loaded, and freely movable by pressure pulsations back and forth between closed and open positions, and a constantly open passage, by-passing the check valve, of a size relatively small as compared with the passage through the valve when open.
2. The improvement means defined in claim 1, and including also a passage leading independently of the balance passage from said reference chamber to a zone of constant pressure other than the pressure in said air intake,
and a check valve controlling said passage and opening in the direction away from said reference chamber, said check valve having a freely movable, substantially unloaded, thin valve closure of light weight.
References Cited in the file of this patent UNITED STATES PATENTS 2,563,228 Ensign Aug. 7, 1951 2,634,088 Niesemann Apr. 7, 1953 2,754,185 Ensign July 10, 1956 2,754,186 Ensign July 10, 1956 2,775,984 Dahl Jan. 1, 1957 2,886,065 Hershman May 12, 1959