US2491760A

US2491760A - Pressure carburetor

Info

Publication number: US2491760A
Application number: US22167A
Authority: US
Inventors: Jr Andrew William Orr
Original assignee: Individual
Current assignee: Individual
Priority date: 1948-04-20
Filing date: 1948-04-20
Publication date: 1949-12-20
Anticipated expiration: 1966-12-20

Description

Dec. 20, 1949 A. w. oRR, JR

PRESSURE GARBURETOR Filed April 20, 1948 A 01T J1:

IN V EN TGR.

Patented Dec. 20, 1949 TED STATES PATENT OFFICE PRESSURE CARBURETOR Application April 20, 1948, Serial No. 22,167

l. Claim.

The objects of this invention are:

(i) To simplify and make more positive the operation of a pressure type carburetor when the throttle is almost closed.

2) To prevent the discharge of a slug of gasoline which otherwise would be discharged into the inlet manifold every time the engine is started.

(3) To facilitate the prompt restarting of the carburetor after a shutdown.

This case is a continuation in part of my copending applications Serial No. 689,260 led- August 8, 1946 and Serial No. 717,673 led December 2l, 1946.

The drawing shows the preferred form of my invention.

The air enters at I8, flows through the venturi I2, past the throttle Ill and past a long narrow slot I5 in the walls of the outlet pasage |40 adjacent to the downstream lip of throttle' I4. A valve I8 on the throttle shaft controls the communication between the fuel passages and 22.

Fuel enters at 24 from the fuel pump 26 having a flexible diaphragm |22 flexed by the broken link |24. This link is exed by the cam |26".

When the pressure above the diaphragm |22 is excessive a spring |28 is compressed. Check valves |30 and |32 complete this well known pump. This pump is of a well known type.

Fuel flows from. the entrance 24, through the chamber 50, past the throttle controlled valve I8, along the passage 22 to the chamber 54 above the diaphragm 50. (The diaphragm 56 separates the chamber 50 from the chamber 54.) This diaphragm 56 is pushed up by the spring 58 which pushes a diaphragm 60 up and thus raises the cup 52 which engages with the underside of the diaphragm 56.

A release valve 54 engages with the upper side of the diaphragm 58 and the lower side of a diaphragm 18 and controls the flow of fuel from the chamber 51| past the valve 63 to the passage 56, down past the valve 68 and so out through nozzle 18 to mixture outlet pasage |40. A diaphragm 12, loaded by the spring 14, and the air entrance pressure derived from the air impact tube 16 presses the Valve 68 onto its seat.

A diaphragm 18 is subjected on its upper face to the pressure in the air entrance I 0 through the impact tube 1S. The chamber 30, above the diaphragm 18, is connected by the passage 82 to the chamber 84 on the right of the diaphragm 'I2'. The chamber 86, beneath the diaphragm 18, is connected through the restriction 38 with the throat of the venturi I2. An inclined air passage 98 connects the narrow vertical slot I6 with the chamber 86 through the restriction 92. A drain passage 94 is provided for obvious reasons.

An acceleration pump is provided and is' operated by a link 98 driven by the throttle lever 98, mounted on the shaft of the throttle valve I4. This pump comprises a piston |00 which is operated by the link 96.

The left hand face of diaphragm |04 displaces fuel from a chamber |00 whenever the throttle is opened. Fuel enters and leaves the chamber |05 through the restricted passage |08. This restricted passage |08 is connected to the descending fuel outlet passage 86.-

Fuel economy' is secured by means of the valve |4. This v'al've' |I4` is mounted on the small horizontal diaphragm. H6. Chamber ||8,located belowthis diaphragm IB, is connected to the passage 82 which is connected through the inclined' passage 16` and with the air entrance I0. The passage- ||9 connects the chamber II'I, located above the diaphragm I Ifir with the main ir passage |40' downstream of the throttle I4.

A spring |25 engages with a cup |21 connected to the valve I4 and tends to open the valve I I4.

Two springs |20 and |22 are arranged under the cup |29 sov as to engage with the upper side of diaphragm 18. The inner spring |20 is the Wide open throttle bias spring and is quite light but exerts this light pressure at all times. The outer spring |22 exerts zero pressure until the choke lever cam |24 has been moved an appreciable degree from its off position.

When cam |24 is rotated clockwise then the loose spring |22 is compressed and an additional compression is added to the pressure imposed by the smaller inner spring |20 at all times.

The spring load on the valve 68 is such that a 3 pressure of 2 to 3 pounds per square inch across the diaphragm 12 will open the valve 68 and compress the spring I4 and allow fuel to discharge from nozzle 1B.

A pressuredifference of 1 to 2 pounds per square inch will lower the diaphragm Bil and compress the spring 58 and permit the valve S3 to open.

A low speed adjustment is provided and is shown at 45. This adjustment permits fuel to flow from passages 2@ to 22 in addition to that which flows past the fuel throttle valve IS.

Operation When the engine is stopped, 'the spring |23 in the fuel pump raises diaphragm |22 and tends to maintain fuel flow to the engine until the diaphragm |22 reaches its maximum stroke. Fuel would continue to flow through this carburetor because the light biassing spring |25 tends to I hold valve 53 open and valve 68 will remain open and discharge this fuel until the fuel pressure drops below 2 or 3 pounds per square inch. However the bleed holes in check valves I3@ and |32 permit the fuel delivered by diaphragm |22 to be returned to the fuel tank through fitting I3@ after the engine has stopped so that the fuel is not discharged to the engine manifold. Also when the pressure in chamber 553 falls below 1 or 2 pounds per square inch spring 58 moves cup E2 against diaphragm 56 and closes valve 63 against the opposition of the lighter spring 12d. If spring 58 and diaphragm Sil were not provided, the valve 63 would normally be opened and diaphragm 56 extended to the limit of its travel by biassing spring i29 after the engine was stopped. Then when the engine was again started diaphragm 5G would, in moving valve 3 to near its closed position, push a slug of fuel into the engine through valve 6B. Spring 53 thus through diaphragm Sil and cup 62 holds diaphragm 5E in the up position and valve 55S at its closed position when there is no fuel pressure in the chamber 5U. This makes closed throttle starting of the engine possible with a pressure carburetor.

` When the throttle is slightly opened for starting the valve i8 is opened silghtly. This would not provide suilicient fuel in cold weather so the cam |24 is rotated clockwise. The springs i2@ and |22 are compressed so that the valve t3 opens to admit sufficient fuel.

After the engine has started and is running the throttle I4 is opened. As the throttle i4 opens the lip of the throttle sweeps over the long narrow slot I6 and the suction in the outlet |49. which is transmitted through the restriction 92, no longer influences the pressure in the chamber 8B. Thereafter the pressure in the chamber 86 Siti is the pressure in the throat of the venturi I2. The pressure in the throat of the venturi I2 thereafter opposes the pressure drop through the restriction 52 in the fuel passage in the well known manner. The fuel/air ratio is thus maintained constant until the throttle I4 is almost wide open when the valve II4 is opened by the pressure transmitted through the passage I I9. The opening of the valve I I4 adds fuel sufficient to develop maximum horsepower.

What I claim is:

The combination of a variable stroke fuel pump and a pressure type carburetor in which there is a moving wall in said pump acting as a piston, positive means for moving said moving wall on its suction stroke, spring means for moving said moving wall on its pressure stroke, inlet and outlet check valves, small openings acting as a bypass passages around said check valves, an air entrance to said carburetor, a venturi therein, a second moving wall responsive to the pressure drop in said Venturi, a fuel passage leading from said fuel pump, a restriction in said passage, a third moving wall responsive to the pressure drop due to fuel now through said fuel restriction, said second and third moving walls being arranged so as to oppose each other, a fuel valve in series with said fuel restriction and connected to said second and third moving walls, a throttle valve downstream from said venturi, a second fuel valve connected to the air throttle and located in the fuel passage in series with said fuel restriction, said second valve being normally Wide open but adapted to restrict the fuel ow when the throttle is moved towards its idling position, yieldable means maintaining at al1 times a pressure on said second moving wall tending to open the first mentioned fuel Valve, a fourth moving wall, yieldable means tending to move said fourth movable wall in one direction, the pressure from the first moving wall tending to move said fourth moving wall in the opposite direction, said fourth moving wall being adapted to engage with and to close said first mentioned fuel valve when the fuel pump registers `zero pressure, that is, when the variab stroke pump is not operating.

. ANDREW WILLIAM ORR, JR.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 55 2,361,227 Mock Oct. 24, 1944 2,432,274 Barr Dec. 9, 1947 2,447,791 Barfod Aug. 24, 1948