US2917110A

US2917110A - Vapor lock preventing device

Info

Publication number: US2917110A
Application number: US615272A
Authority: US
Inventors: Earl M Brohl
Original assignee: Motors Liquidation Co
Current assignee: Motors Liquidation Co
Priority date: 1956-10-11
Filing date: 1956-10-11
Publication date: 1959-12-15
Anticipated expiration: 1976-12-15

Description

Dec. 15', 1959 E, M, BROHL 2,917,110

VAPOR LOCK PREVENTING DEVICE Filed Oct. 11, 1956 7,7 l M 1 1/ '73 FUEL 0125085705 7 l /fl\ easzem/e IN V EN TOR.

United States P t VAPOR LOCK PREVENTING .nnvrcn Earl M. Brohl, Flint, Mich., assignor to General Motors Corporation, Detroit, Mich., a corporation of Delaware Application October 11, 1956, Serial Nn...615,272 5 Claims. Cl. 158-36) The present device relates 'to an'irnproved vapor lock preventing device particularly adapted for use with internal combustion. engines which are subjected to high ambient temperatures.

Vapor locks have long been a source of trouble in the operation of internal combustion engines, particularly during .hot weather. 'The vapor lock may .occur when a sufficiently large accumulation of fuel vapors collects within some portion of the fuel system and blocks the flow of fuel 'therethroug'h. Fuel systems are particularly susceptible to vapor locks during hot weatherwhen the 'fuel system must operate in relatively high ambient temperatures under which condition there is a tendency "towards excessive fuel vaporization. As noted, fuel vapors may collect in quantities su'flicient to cut on fuel flow until the ambient temperatures are suitably reduced or the system is otherwise bled of the troublesome vapors. This vapor'lockpropensity maybe aggravated when the vehicle is operated "in a relatively rarefied atmosphere, as when in a mountainous area, causing a relative increase in fuel vapor pressure .thereby increasing the 'rate of vaporization.

Numerous devices have been developed for eliminating theproblem of vapor'lock. Most of these devices, however, have been unsatisfactoryeither because of their failure to operate properly, e.g,, failure 'to adequately vent the system or in'also permitting-the escape of liquid fuel; or because the devices were too expensive .to commercially incorporate into fuel systems.

It is therefore the purpose of the present invention to provide a fuel vapor venting device which is economical to manufacture and which may be readily incorporated into .fuelsystern components .as ztheynow existj More specifically, tthe present .device provides a mechanism .whereby :the liquid .and. vapor :fuels (are effectively .mechanically separated .in such .a way 'as to cause :no .loss or unnecessary handling of fuel.

The present vapor venting device may be incorporated in various parts of the fuel system, however, it has been found particularly satisfactory to incorporate such device in the fuel filtering bowl.

A further refinement of the present device is the in corporation therein of a thermostatically controlled valve which renders the venting mechanism inoperative under conditions where the ambient temperatures are such as to preclude any problem arising from a vapor lockup. In this way liquid fuel is denied egress through the venting system under all operating conditions.

The subject vapor venting mechanism will hereinafter be described in detail.

In the drawing:

Figure 1 is a diagrammatic representation of a fuel system incorporating the subject invention; and

Figure 2 is a detail of the vent tube and thermostatic valve construction.

Referring to the drawing, a fuel system has been shown in order to place the subject venting mechanism in an illustrative environment and includes a fuel reservoir .10, a carburetor 12, a fuel filtering device 14, a first conduit 16 connecting said reservoir and said filtering device and a second conduit 18 leading from the filter- :ing device 14 to the carburetor 12. A third conduit 20 communicates the filtering bowl with the reservoir 10. It is to be understood that the fuel system shown is in no way a limitation on the vapor venting device, per se, inasmuch as it is equally adaptable to various other types of fuel systems in which the problem of vapor lock might be present. 7

The fuel filtering device i4 is an essentiaily closed receptacle comprising a U-shaped glass bowl 22 and a cover member 24 adapted to coact therewith. The cover 24 has a plurality of passages formed therein including an inlet passage 26 which opens upwardly into communication with the glass bowl to permit fuel to flow .therewithin, an outlet conduit 28 communicates with bowl.22 through a centrally disposed vertical passage 30.

V The passages 26 and 28 respectively communicate with conduits 16 and 18 and thereby permitting liquid fuel to flow from the reservoir through the receptacle to the carburetor.

fuel system.

Cover 24 includes the centrally disposed upstanding boss 34 which has a shoulder 36 formed thereon. A perforate plate 33 is centrally supported on shoulder 36 and peripherally locked between bowl 22 and cover 24 ,through a suitable gasket 40.

Plate 38 is centrally vertically spaced from cover 24 to define therewith an annular chamber 42 which communicates with the upwardly opening end 44 of inlet passage 26.

Filter 32 comprises an inverted U-shaped element, the open end of which is supported on plate 38 to overlay the perforations in the plate. Thus fuel flows from end 44 of passage 26 to annular chamber '42, through the perforated plate 38 into filter 32 passing therethrough into bowl 22, leaving through passages 31'? and 28.

In order that any fuel vapors which tend to accumulate in .filter bowl 22 can be mechanically separated from the liquid fuel, a tube is supported on the cover 24 and projects through the boss 34. The upper end 52 of tube 50 terminates adjacent the upper portion of the 'upper portion of bowl 22 into which end 52 of tube 56? projects.

While the device as thus far described is adequate to prevent the excessive build-up of fuel vapors within the fuel system, it has been found to be advantageous to provide means whereby the fuel venting system is rendered inoperative during conditions when ambient tem peratures are sufficiently low to preclude the possibility of vapor lock. In this way the useless bypassing of liquid fuel through the venting system is prevented The bypassing of liquid fuel may otherwise occur in the absence of vapor in the bowl 22.

To this end, a thermostatically controlled valve 60 is provided at the upper or open end 52 of the vent Thus any fuel vapors collecting in the 3 tube 50. The valve consists of 61 fixed at one end 62 to the tube 50 and reversely bent in such a way that the other end 64 sits freely across the open end of tube 50. The bimetallic spring is provided with a convoluted portion 66 intermediate its ends to suitably position the free end of the strip with respect to the open end of the tube as well as to fix the spring rate and thereby determine the temperatures at which the valve end 64 will open and close. It will be seen in Figure 2 that end 62 of the bimetallic spring is of arcuate form so as to conform to the shape of the tube whereas the free or valve end 64 is fiat so as to correspond to the inclined flattened open end 52 of the tube. End 62 of the spring may be secured in any convenient way to tube 50 such as by spot welding.

Valve 6% is shown in the drawing in the closed position indicating an ambient temperature such as to preclude excessive formation of fuel vapors. To illustrate, it has been found satisfactory to construct the spring valve 60 in a way to permit its closing at 120 F. and its opening at 125 F. These figures are, of course, illustrative and could be varied to the individual operating characteristics of the fuel system in which the subject device was to be incorporated.

The form of thermostatic spring valve 60 is preferred because of its simplicity which results in reliable operation as well as economy of manufacture.

With the vent tube arrangement as shown, during conditions conducive to excessive vapor formation, the vapors in the upper portion of the filtering bowl 22 will be conducted therefrom, supra, permitting the liquid fuel only to pass on through the system. When ambient temperatures are below a value likely to cause excessive vapor formation the thermostatic valve 66 closes the vent tube 50 blocking the otherwise likely flow of liquid fuel through the vent system. In this way an adequate supply of liquid fuel free of vapor-lock-forming quantities of fuel vapor is always available.

I claim:

1. A vapor venting device for a fuel system comprising a closed receptacle, a first conduit formed in said receptacle for supplying liquid fuel thereto, a second conduit disposed in the lower portion of the receptacle and adapted to deliver liquid fuel therefrom, a tube disposed in said receptacle and terminating at one end near the upper end of said receptacle, a thermostatically controlled valve cooperating with said one end of said tube, and a third conduit communicating with the other end of said tube whereby fuel vapors formed in said receptacle may be separated from the liquid fuel and vented through said tube and third conduit when the ambient temperature is sufficiently high to open said valve.

2. A vapor venting device as defined in claim 1 in a bimetallic metal spring which said valve includes a bimetallic metal spring fixed at one end to said tube and terminating at the other end in a portion adapted to close the said one end of said tube.

3. A fuel system comprising a carburetor, a fuel reservoir and means for separating fuel vapor from the liquid fuel, said meanscomprising a closed receptacle, fuel inlet and outlet passages respectively connecting said reservoir and carburetor with said means, a filtering element intermediate said inlet and outlet passages for purifying the liquid fuel flowing from said reservoir. to said carburetor, a vent tube mounted within said receptacle and terminating at one end near the upper portion thereof, a thermostatic valve cooperating with the open end of said tube to control the fiow therethrough, the other end of said tube communicating with a conduit connecting said receptacle to said reservoir whereby fuel vapors formed in said receptacle may be separated from the liquid fuel and returned to said reservoir when the ambient temperature is sufificient to open said valve.

4. A vapor venting device for a fuel system comprising a closed receptacle, inlet and outlet passages formed in said receptacle for supplying and discharging liquid fuel, a tube defining a vent passage and having one end terminating within theupper portion of said receptacle and its other end adapted to be connected to a source of said liquid fuel, and a thermostatic valve in said upper portion controlling the said vent passage whereby fuel vapors formed in said receptacle may effect opening of said valve and consequent venting of said receptacle through said other end of said vent passage.

5. A fuel system comprising a carburetor, a fuel reservoir and a device for separating fuel vapor from liquid fuel, said device comprising a closed receptacle, fuel outlet and inlet conduits connecting said receptacle with said carburetor and reservoir respectively, a vent tube defining a flow passage terminating at one end in an upper zone of said receptacle, said vent tube communicating with said reservoir, a thermostatically operated valve associated with. said tube within said upper zone of said receptacle to control said flow passage, and the arrangement being such that the temperature of fuel vapor in said receptacle may effect operation of said valve thereby opposing vapor lock tendencies in the system by venting said vapor through said flow passage to said reservoir.

References Cited in the file of this patent UNITED STATES PATENTS 1,849,590 Phillips Mar. 15, 1932 1,941,390 De Lancey Dec. 26, 1933 2,323,525 Ebel et a1. July 6, 1943 2,545,856 Orr Mar. 20, 1951