US2965088A - Fuel pump air bleed - Google Patents

Description

Dec. 20, 1960 I. E. COFFEY FUEL PUMP AIR BLEED Filed Dec. 10, 1953 2 Sheets-Sheet 1 5 m L! IIIIIIIIII x; 4/ f INVENTOR.

ATTORNEY Dec. 20', 1960 FEY 2,965,088

FUEL PUMP AIR BLEED Filed Dec. 10, 1953 2 Sheets-Sheet 2 'IIIIIIII III! IIIIIIIII INVENTOR.

ATTORNEY FUEL PUMP AIR BLEED Filed Dec. 10, 1953, Ser. No. 397,417

10 Claims. (Cl. 123--179) This invention relates to a system for cooling and also venting the fuel supply for an internal combustion engine, and a novel vent valve for that system. More specifically, the fuel supply system, according-to this invention, includes a vent valve which is responsive to ambient temperatures and engine operation.

This invention finds particular application to the fuel supply systems generally provided for automotive equipment wherein the supply tank for fuel is located remote from the engine. It is customary in such systems to provide a fuel pump, usually located adjacent the engine and driven therefrom. This pump is, in turn, connected on its suction side with the fuel tank and on its discharge side with the engine. With such an arrangement of the parts, it is inevitable, because of their location, that some or all will be exposed to heat from the engine. Where the fuel supplied is highly volatile, its temperature materially afiects the efiiciency of operation cf the system as a whole because the lighter ends of that fuel vaporize within the system so as to interrupt the continuous flow of liquid to and from the pump. The pump, therefore, must be capable of handling a mixture of both vapors and liquid; otherwise, the system will become vapor-locked and the supply of fuel to the engine interrupted.

This condition of vapor lock can occur in present fuel systems during engine operation, and often occurs when the engine is shut off after being brought to normal running temperatures, or when the engine stalls. Restarting under these conditions is usually impossible until the engine has cooled down. On the other hand, this condition of vapor lock can and often does occur in congested traffic conditions when the pump is operated at slow speeds. In many instances the complete relocation of the fuel lines to shield them from the heat is not possible, or is impractical, because of the location of the pump and carburetor. Consequently, this problem presents many obstacles to a satisfactory solution.

The present system described below improves the fuel pump efiiciency under adverse conditions of high temperature by providing a vent in the fuel system on the suction side of the fuel pump. The vent is controlled by a metering type of valve to restrict the degree of vent opening, and this metering valve is, in turn, controlled by a temperature responsive device which opens thevent at high ambient temperatures, the degree of vent opening increasing with increases in temperature. The vent allows escape of the vapors forming in the suction line, and thereby insures that a solid column of fuel will be present in that line before the engine is started, regardless of temperature. On actuation of the starter motor, the metering valve automatically closes the orifice so that the action of the pump at this time will supply enough fuel to start the engine even at the slow pump operating speeds prevalent during the cranking'operation. After the engine is started, however, the metering valve is under the sole control of the temperature means, thus permitting the pump to draw in the cooler air circulated about the rates atent O 2,965,088 Patented Dec. 20, 1960 engine by the engine driven fan. This produces a beneficial efiect on pump operation.

In the drawings,

Fig. l is a diagrammatic view of a system according to the present invention.

Fig. 2 is a vertical section of the pump and vent valve shown in Fig. 1.

Fig.3 is an enlarged detail view showing in section the adjusting means for the thermostat of the vent valve.

Fig. 4 is an enlarged detail view in section of the vent valve in closed position; and

Fig. is an enlarged detail view of the vent valve and thermostat mechanism taken at right angles to the views in Figs. 3 and 4.

Turning now to Fig. l, the drawings illustrate an internal combustion engine 1 equipped with the usual exhaust manifold 2, intake manifold 3, and carburetor 4. The carburetor 4 has a thermostatically controlled choke mechanism 5 of a type now recognized as standard equipment in the automotive art. In the carburetor 4 is a throttle controlled by a lever 6 connected by way of a rod 7, or the like, with the usual accelerator pedal.

Engine 1 drives a generator 10 by means of a belt 11 meshing with sheave 12 on the engine crankshaft, and a similar sheave 13 on generator 10 connected to the armature. Generator 10 has its field connected to ground through a resistance 14 and a pair of brushes 15 and 16, one of which 15 is grounded through a connection 17. Brush 16 is connected through lead 19 with a relay cutout generally indicated as 20. On the electromagnet of the relay 20 is a main winding 21 connected to one end of switch arm 22. A shunt or holding winding 23 connects with the lead 19 and with the ground. The relay 20 connects the lead 19 through the relay points 25 with a lead which extends to battery B. The other terminal of the battery B is connected with the ground.

An ignition switch 31 of the key operated twist type is provided to connect and disconnect the battery with the ignition for the engine through lead 32, and also with the starting circuit for the starter motor. The ignition system for the engine has not been shown, since it forms no part of the the present invention. The starter motor circuit is connected to the battery through lead 30, twist switch 31, and lead 33 connected with the twist switch. Lead 33 extends to a starter switch generally indicated as 34, which may be of any type and operated in any manner desired. Switch 34, when operated, completes the circuit between lead 33 and lead 35 extending to and through a solenoid for the vent valve of an atmospheric bleed V for the mechanical fuel pump shown diagrammatically as P. This pump is of the type operated by a cam on the engine camshaft C. It is shown here diagrammatically, for purposes of convenience, separated from the engine, but it should be understood that the location of the pump P is actually on the engine 1 adjacent the camshaft for operating the engine valve mechanism. Lead 35 extends to and through an electromagnet of a starter relay switchgenerally indicated as 36, and from thence to ground through lead 19 and the brushes of the generator 10.

A circuit has been described so far in which operation of the twist switch 31 and starter switch 34 will energize the solenoid to operate a vent valve in the atmospheric bleed V and also starter motor relay 36. The starter motor circuit including the relay 36 is illustrated here as one of the conventional types commonly used in motor vehicles. In such circuits, the operation of the relay 36 closes a circuit from lead 39 through a starter solenoid 40 which has a shunt winding 41 connected to ground. Winding 41 will be immediately energized from the battery B to operate the armature of the solenoid 40 and close the switch 42' against the resistance of spring 43,

At the same time, relay 40 mechanically engages the starter motor pinion with the ring gear on the fly wheel of .the engin 1,. 1l in a well known mann r- Simul an ously with this engagement and with Qtheclosing .of the switch 42, the split field 45 and 46 oflstatiter motor 47 is-energized by the irect connection-dim .main lead 49 with lead 50 connected to the starter motor. Starter .motor 47 has a ground connection ;52 ,for the field .;and the brushes indicated as 54 and 55. i' i i The above description will serve toiillustrate one manher ,of interconnecting the pump vent valve control of the atmospheric bleed with the electrical system usually provided to energize the starter motorcircuit of .an .automotive vehicle.

Turning now to Fig. 2, a fuel pump and .an atmospheric bleed have been shown for purposes ofiillustration in order to explain astructureifor carrying out the objects of this invention. Thefuel pump .P shown is .of the detachable typemounted on the engine :in a position to he operated by the camshaft C. This pump may be any suitable type such as shown in Coffey Patent 2,625,- 114 of January 13, 1953, or such as shown in the Coffey application Serial No. 280,985 of April 7, i952, andnow abandoned, for Check Valve Device. Since the operation and construction of such pumps is well known ,in the art, there is no reason for burdening the description here with the details of the pump structure. It is sufiicient .to point out that ,the pump P has an inlet or suction side with a connection 6 and an outle or di charge side with a connection 61. Each is, in turn, connected, as shown in Fig. 1, by a suctionline 62 with the fuel tank T and a discharge line 64 from the outlet .61 to the carburetor 4. As illustrated in Fig. 1, the tank T is disposed in a position adapted to supply .fuel through the suction line 62 into the suction chamber 67 of the pump P without causing leakage of fuel upwardly through the vent orifice 67. The atmospheric bleed V is shown connected by a nipple 66 with the air dome 67 on the .suction side or intake side of the pump P. v

The details of atmospheric bleed V are shown assembled in Fig. 2, and separately and enlarged in Figs. 3-5.. Referring to these figures, nipple 66 has a vent orifice 67' and is secured to a cylindrical casing 68 for enclosing the mechanism and its thermostatic control. vA casing 69 for enclosing the solenoid and air filter is secured to the lower casing 68 by means of rolled edge 70 formed in the casing 68. Riveted to the lower wall of thecasing 68 is a bracket 72 apertured at 73 for rotatably supporting shaft 74. Bracket 75 is secured to shaft 74 and formed with an ear 76 in abutting relation to an ad justing screw 78 threaded in the casing 68 and provided with a lock nut 79. A torsion spring 80 surrounds the shaft 74 and has oppositely hooked ends 81 and 81 ' engaging brackets 75 and 72, respectively. This spring will maintain car 76 in firm engagement with the adjusting screw '78, and at the same time permit the movement of the screw to turn the shaft 74. '9 k' I The metering valve device 83 is positioned in the vent orifice 67' by means of a thermally responsive bimetallic coil 85. Coil 85 surrounds shaft 74 and is formed with a diametrically extending portion 86 received in aslot 87 in the end of shaft 74.

The mechanism so far described will open the vent orifice to the suction side of the pump by varying amounts in response to the action of temperature responsive member 85. The initial setting will determine the temperature for closing the vent orifice, and can be adjustably controlled by the screw 78 so as to predetermine the temperature at which the orifice 67 will be opened by the metering valve 83. As the temperature increases, orifice .67 will be further opened by the action of the thermostat 85. When the engine is not operating, opening of the vent valve 83 will allow the escape of the volatileg e on the suction side of the pump from the housing 68 by way of vent holes 90 into the casing 69,

and from the casing by way of vent holes 91 and 92 to the atmosphere.

In the casing 69 is an air filter 93 of copper or steel wool held in place by a screen member 94. Also within the casing 69 is the solenoid for closing the metering valve 83. This solenoid structure comprises an armature 97 fixed to an armature shaft 98 by means of a set screw. Shaft 98 is slidably mounted within guides 10.0 and 101. A field coil 102 serves, when energized, to move the armature and its shaft 98 downwardlyinto engagement with the metering *valve 83, forcing it firmly into engagement with its seat to close the orifice 67 As shown in Fig. 1, field 102 is connected into the starter motor control circuit by the lead 35, so that when the starter switch and ignition switch are closed, solenoid field winding 102 will be energized and force armature 1shaft98 downwardly to close the valve as shown in Fig.

4.. When tie-energized, shaft 98 will exert no great amount of force on the metering valve 83, and the valve metering valve 83, regardless of the temperature. 'When this valve is closed, leakage on the suction side of the ,fuel pump is prevented so as to enable the pump to deliverits maximum capacity at ordinary cranking speeds. After the engine has been started, however, the degree of opening of the metering valve 83, if any, is under the exclusive control of the thermal responsive coil because the solenoid is de-energized and no longer exerts a closing force on the metering valve 83. As the temperature adjacent the engine increases, this will effect a change in the ambient temperature adjacent the pump P and bleed V due to radiation or convection, or both. At a predetermined temperature, depending upon the position of the adjusting screw 78, metering valve 83 will begin to open, allowing the leakage of cooler air drawn in by the usual engine driven fan to leak into the suction side of the fuel pump P. It has been found that this slight amount of leakage provided by the metering valve 83 is extremely beneficial to the efficient operation of the pump at high temperatures. It is believed that the presence of air in the system aids materially in condensing the fuel vapors present in the suction line and in the pump. Of course, a slight amount of air leakage such as provided by the vent at high temperatures has very little effect on the normal capacity of the pump to deliver when operated at engine speed, and it is not contemplated that during operation of the pump the temperatures will be high enough to open the valve 83 more than just .a slight amount.

After the engine has been shut off by Opening the switch 31, the circulation of cooling air around the engine ceases,due toinoperation of the engine driven fan, and it is at this time that the ambient temperature surrounding the pump and fuel lines leading to the pump may increase and-become excessive. Accordingly, the thermal responsive coil 85 will respond to open the orifice 67 far enough to provide adequate venting to eliminate the accumulation of vapors from the suction side of the pump and its connecting lines to the tank so that, when the engine is again started and the metering valve 33 closed by the solenoid, the'lines on the suction side of the pump will be full of fuel and the pump will act upon solid fuel. This increases the output of the pump so that the carburetor bowl may be rapidly filled with fresh fuel if its supply has been partially or wholly exhausted by evaporation due to heat.

:It is contemplated that the atmospheric bleed V may take difierent forms and .may be connected :at o her places in the system, to perform .the same function and produce, the same result. Consequently, the invention s is not limited to the precise disclosure, but only by the scope of the appended claims.

I claim:

1. In an engine fuel supply system having a pump, a fuel tank for supplying liquid fuel to said pump, a connection from the suction side of said pump to said tank, and a discharge connection from said pump to said engine, the combination of, an atmospheric bleed con nected to said system on the suction side of said pump, and control means for said bleed responsive to ambient temperatures adjacent said fuel system when the engine is at rest to open said bleed for venting fuel vapors from said pump caused by boiling of the fuel and thereby avoid vapor lock in said system.

2. In an engine fuel system having a pump, a fuel tank for supplying liquid fuel to said pump, a connection from the suction side of said pump to said tank, and a discharge connection from said pump to said engine, the combination of, an atmospheric bleed comprising a metered orifice connected to said system on the suction side of said pump, and control means for said orifice responsive to vapor forming ambient temperatures adjacent said fuel system When said engine is operating to open said bleed for admitting varying small amounts of air leakage into said pump depending on temperature conditions.

3. In an engine fuel supply system having a pump, a fuel tank for supplying liquid fuel to said pump, a connection from the suction side of said pump to said tank, and a discharge connection from said pump to said engine, the combination comprising a metered orifice connected to said system on the suction side of said pump, a metering device for said orifice, and a thermal responsive means to determine the degree of opening of said orifice by said metering device with increases in ambient temperatures adjacent said system when the engine is at rest to open said bleed for venting fuel vapors from said pump caused by boiling of the fuel and thereby avoid vapor lock in said system.

4. In an engine fuel supply system having a pump, a fuel tank for supplying liquid fuel to said pump, a connection from the suction side of said pump to said tank, a discharge connection from said pump to said engine, the combination of, an atmospheric bleed connected to said fuel supply system on the suction side of said pump and responsive to ambient temperatures adjacent said fuel system comprising, an orifice, a metering device for said orifice, and a thermal responsive member to determine the degree of opening of said orifice by said metering device responsive to vapor forming ambient temperatures adjacent said system when said engine is operating to open said bleed for admitting varying small amounts of air leakage into said pump depending on temperature conditions.

5. The combination as defined in claim 3, in which the thermal responsive member is provided with a manual adjustment to determine the opening and closing temperature of said metering device.

6. The combination as defined in claim 4, in which the thermal responsive member is mounted for manual rotatable adjustment to determine the degree of orifice opening by said metering device for a given temperature.

7. An engine fuel supply system having a pump, a fuel tank for supplying liquid fuel to said pump, a connection from the suction side of said pump to said tank,

a discharge connection from said pump to said engine, a starter motor for said engine, and a control circuit to energize said starter motor, the combination comprising an atmospheric bleed connected to said fuel supply system on the suction side of said pump, and valve means for said atmospheric bleed connected to said control circuit responsive to energization of said starter motor to close said atmospheric bleed during operation of said starter motor.

8. In an engine fuel supply system having a pump, a fuel tank for supplying liquid fuel to said pump, a connection from the suction side of said pump to said tank, a discharge connection from said pump to said engine, a starter motor for said engine, and a control circuit to energize said starter motor, the combination comprising an atmospheric bleed connected to said fuel supply system on the suction side of said pump, control means for said bleed responsive to ambient temperatures adjacent said fuel supply system when the engine is at rest to open said bleed for venting fuel vapors from said pump caused by boiling of the fuel and thereby avoid vapor lock in said system, and means associated with said control means connected to said control circuit and responsive to energization of said starter motor to close said atmospheric bleed during operation of said starter motor.

9. In an engine fuel supply system having a pump, a fuel tank for supplying liquid fuel to said pump, a connection from the suction side of said pump to said tank, a discharge connection from said pump to said engine, a starter motor for said engine, and a control circuit to energize said starter motor, the combination of an atmospheric bleed connected to said fuel supply system on the suction side of said pump and responsive to ambient temperatures adjacent said fuel system, comprising an orifice, a metering device for said orifice, a thermal responsive member to determine the degree of opening of said orifice by said metering device with increases in ambient temperature adjacent said system when said engine is operating to open said bleed for admitting varying small amounts of air leakage into said pump depending on temperature conditions, and means associated with said metering device connected to said control circuit and responsive to energization of said starter motor to close said atmospheric bleed during operation of said starter motor.

10. In combination, a fuel pump having suction and discharge connections and an atmospheric bleed for said suction connection comprising an orifice, a metering device for controlling the fiow of gases through said orifice, a thermal responsive element to actuate said device to determine the degree of opening of said orifice responsive to increases in ambient temperature adjacent said pump, and means including an electric motor operable to move said metering device to override said thermal responsive element and close said orifice.

References Cited in the file of this patent UNITED STATES PATENTS 1,976,519 Rockwell Oct. 9, 1934 2,118,886 Joesting May 31, 1938 2,364,605 Curtis Dec. 12, 1944 2,412,019 Walker Dec. 3, 1946 FOREIGN PATENTS 775,235 France Feb. 14, 1935

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