US3776256A

US3776256A - Fuel evaporative control system

Info

Publication number: US3776256A
Authority: US
Inventors: C Marshall
Original assignee: American Motors Corp
Current assignee: American Motors Corp
Priority date: 1970-08-14
Filing date: 1972-01-21
Publication date: 1973-12-04
Anticipated expiration: 1990-12-04

Abstract

A system designed to prevent raw fuel vapors from entering the atmosphere from the carburetor fuel bowl and the fuel tank of a motor vehicle. The carburetor is internally vented and the fuel tank vent line routes the vapors from the tank through a float type liquid-vapor separating valve to the cylinder head cover of the engine. The vapors are stored in the crankcase of the engine while the engine is not operating and combusted during engine operation with the blow-by products by use of the positive crankcase ventilation system.

Description

I United States Patent 1 [111 3,776,256 Marshall Dec. 4, 1973 [54] FUEL EVAPORATIVE CONTROL SYSTEM 2,425,070 8/1947 Nicolette 137/202 3,302,658 2/1967 DeFrees 137/493.8 [75] Inventor. Charles J. Marshall, Detroit, Mich. 2,243,262 5/1941 smithwv 37/202 [73] Assignee: American Motors Corporation,

Kenosha, Wis. Primary Examiner-Alan Cohan Filed: J 1972 Attorney-Gerald E. McGlynn, Jr. et al.

[21] Appl. No.: 219,908 57 ABSTRACT Related US. Application Data A system designed to prevent raw fuel vapors from en- [62] Division or Ser. No. 63,699, Aug. 14, 1970, Pat. No. wring the atmosphere from the Carburetor fuel bowl 3,650,256. and the fuel tank of a motor vehicle. The carburetor is internally vented and the fuel tank vent line routes the [52] US. Cl. 137/202 vapors fr m h tank through a float type liquid-vapor [51] Int. Cl. F16k 45/00 p ng v lve o th ylin er head cover of the en- [58] Field of Search 137/202, 493, 493.8 g h p r r tored in the crankcase of the engine while the engine is not operating and combusted [56] References Cited during engine operation with the blow-by products by UNITED STATES PATENTS use of the positive crankcase ventilation system.

3,168,103 2/1965 4 Claims, 6 Drawing Figures Kochaver 137/202 FUEL EVAPORATIVE CONTROL SYSTEM This is a division, of application Ser. No. 63,699 filed Aug. 14, 1970, now U.S. Pat. No. 3,650,256.

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention pertains to evaporative controlsystems for vehicle fuelsystems.

2. Description of the Prior Art A conventional fuel evaporative control system may include an internal expansion tank located in the upper portion of the fuel tank and having orifices therein to restrict the passage of fuel into same upon filling the fuel tank. A vapor-liquid separator system is generally connected to the expansion tank to allow the passage of the vapors therethrough and the return of the liquid fuel to the fuel tank. A valve is normally positioned in the vent line beyond the separator and incorporates pressure and vacuum relief means to normalize fuel system conditions inasmuch as the tank filler cap is sealed. The vent line from the valve may be connected to a canister containing charcoal for the adsorption of the vapors, or directly to the engine for vapor storage therein. With a canister, an air purge is necessary to strip the vapors from the charcoal and conduct same to the engine for burning.

SUMMARY OF THE INVENTION Applicant has designed a system that is characterized by its simplicity of operation and economy of manufacture when compared tothe conventional system detailed above. Specifically, applicant has provided a unique float type valve that allows the passage of vapors therethrough but prevents liquid fuel from entering the crankcase. Applicant has dispensed with the charcoal canister, the vapor-liquid separator, and the valve in the vent line. Although the internal expansion tank is utilized to provide expansion space for the fuel, same is not absolutely necessary since, by providing the proper configuration of the tank and the positioning of 1 the filler neck, a suitable back pressure can be obtained .to preventthe total filling of the fuel tank. The fuel tank filler cap of applicants system has vacuum and pressure relief valves which are normally closed and calibrated to open only when an abnormal condition is encountered such as plugged lines or the like. A necessary part of applicants float type valve is a vacuum relief valve which prevents a vacuum build up when the float valve is closed, to allow the float to open and the liquid fuel to. return to the tank. Although theoretically a positive pressure should exist in the valve due to the compression of the vapors therein by the liquid fuel to the extent of the system pressure as determined by the cap pressure relief valve, in actual practice a vacuum is developed. Applicants vacuum relief valve which is connected to the vent line above the float valve relieves the vacuum and does so without the need of a filter. Applicant has also provided as a safety feature an annular wall around the vacuum relief valve which forms a vapor pocket to insure sealing of the normally closed, flexible vacuum valve and prevents the passage thereby of liquid fuel. Although only a central vent line from the tank to the valve is shown, larger tanks may have dual, diagonally located vent lines connected to the valve. Applicants system which includes the unique float type valve enables the vehicle to. pass most conceivable fore and aft, side grade and maneuvering tests,

even'with hot fuel. Of course thelocation of the entire system (including the valve which is located high in the kickup on theunderside of the vehicle) outside thepassenger compartment-also prevents hazards arising from faulty installation or repair.

It is therefore an object of this invention to provide a new and improved evaporative control system fora vehicle fuel system.

Another object of this invention is to provide a new and improved float type valve foruse :in an evaporative control system for a vehicle fuel system.

. BRIEF DESCRIPTION OF THE DRAWINGS FIG. I 1 is a side view of' the evaporative controlsystern of this invention mounted on a vehicle which is shown in broken lines;

FIG. 2 is a plan view of the float type valve of this invention;

FIG. 3 is a front view of the valve shown in FIGJZ;

FIG. 4 is a sectional view taken along line 4-4 of FIG. 3;

FIG. 5 is an enlarged front, sectional view of the fuel tank cap used with the evaporative control system; and

FIG. 6 is a side view (partially in section) of the cap shown inFIG. 5.

DESCRIPTION OF THE. PREFERRED EMBODIMENT Referring to FIG. 1, 10 indicates a fuel evaporative control system for a vehicle 11. Vehiclell has an engine 12 located in the front end of the vehicle and a fuel tank 14 at the other end. Fuel tan'k14 has a filler neck 15 which is closed by a filler cap 16. Expansion tank 18 is fixedly mounted inside the upper portion of fuel tank 14. A plurality of upper and lower orifices 19 in tank 18 restrict the flow of fuel therethrough duringfuel tank filling to provide a thermal .expansion volume. Fuel tank 14 is located below the rear floor pan under the vehicle trunk compartmentandrearward of the kick-up 20. The kick-up" provides space under the vehicle for the movement of the solid rear axle.

Fuel vent line 2l extends from the upper portion of fuel tank 14, where the line is preferably in;communication with the expansion tank 18, to the engine 12.

Preferably the vent line is attached to engine. 12 at an engine cylinder head cover as shown. A metered hole may be provided in the cover to control the. amount of the fuel vapor fumes moving into the engine. Intermediate the ends of vent line 21 and connected. thereto is float type valve .22. Valve 22 is mounted in the kickup area on the under side of vehicle 11 above fuel tank 14. Vent line 21 also extends to and from valve.22

on the under side of vehicle 11.

Fuel tank filler cap 16, as shown inFlGS. 5 and6, is

of conventional construction. Cap 16 includesshell24,

diaphragm spring 25 having shoulderl26 and gasket 28 which is in sealing relationship with the end of filler neck 15 (not shown). Rivet 29 connectshandler30, shell .24 and cup 31 togetherfCup 3.1 haspmjections 32 which are adapted to engage cam surfaces (not shown) on filler neck 15 to tighten the cap thereto. Rig idly attached to cup 31 with gasket29a therebetween is baffle cup 34having .cover 34a which has. mounted therein spring 35, seal plate 36, and gasket 3810 form a pressure valve 40. Hollow rivet 39 connects sealplate 36 and gasket 38 together.

Vacuum valve 41 having spring 42 and sealer plate 44 is also located in cup 34. Because of opening 45 in the lower part of cup 34, a vacuum can be applied to vacuum valve 41 thereby compressing spring 42. The vacuum is relieved by outside air which can move through a duct 46 in cap 16, around shoulder 26 and via a passage 48 in cup 31 through aperture 49 in cover 34a and through hollow rivet 39. Normally the vacuum valve opens at 0.5 psi.

Pressure valve 40 will remain sealed with gasket 38 in contact with cup 31 until the pressure exceeds 1 psi which is sufficient to compress spring 35 to provide communication to the outside atmosphere along the route of the vacuum relief. As mentioned previously the vacuum and pressure valves are closed under normal operating conditions.

Float type valve 22 is shown best in FIGS. 1, 2, 3 and 4. Valve 22 has suitable provisions for being mounted on the underbody of vehicle 11 and includes a housing having a body 50 and cover 51 joined thereto with O- ring 52 therebetween. Body 50 has port 54 which is connected to vent line 21. Although only one vent line is shown, plugged port 55 could be connected to fuel tank 14 should a dual diagonal tank venting arrangement be required. Port 54 has communication with the interior of body 50 even though guide means 56 is interposed in same. Guide means 56 has a plurality of small holes 57 for the passage of vapor therethrough and a larger central guide hole 58 for float element 59. Float element 59 consists of rod 60 which passes through float 61 and culminates in a needle valve tip 62 which may be made of synthetic rubber. Washer 64 and fastener 65 connect rod 60 to float 61 to construct float element 59. Body 50 also has 3 spaced bosses 66 upraised from the bottom thereof to keep float 61 and therefore float element 59 from blocking port 54.

Cover 51 has port 68 which is connected to the vent line 21 for transfer of vapor fumes to engine 12. Located in port 68 is needle valve seat 69 which is adapted to be closed by needle valve 62. Also located in port 68 is vacuum valve 70. Vacuum valve 70 is preferably made of rubber-like material and is adapted to flex and open at approximately one-half psi vacuum in valve 22. Opening of valve 70 exposes slotted openings 71 to allow vapor from the engine to move into valve 22 to relieve any vacuum therein. Annular wall 72 is supplied to provide an air pocket about vacuum valve 70 in conjunction with liquid fuel to positively seal same.

In operation, fuel vapors from expansion tank 18 and therefore from fuel tank 14 move through vent line 21 to valve 22. The vapors pass through small holes 57 in guide 56 and into body 50. With float element 59 resting on bosses 66, the vapors can move around float 61 and valve seat 69 into port 68. The vapors continue on through vent line 21 to engine 12 for storage therein. Should a drastic increase in ambient temperature occur to expand the liquid fuel, any liquid fuel moving into valve 22 will move float 61 and therefore float element 59 to move the attached needle valve 62 to engage seat 69. Liquid fuel can therefore not enter the engine 12. Annular wall 72 in conjunction with liquid fuel will fonn an air pocket about vacuum valve to positively seal same, so no liquid fuel can lap around the valve and past same. Continued expansion of the liquid fuel and vapors will cause the pressure valve 40 in cap 16 to open to equalize system pressure. Of course the expansion tank volume and the location of valve 22 are designed to accommodate most conceivable situations.

Upon cooling, the liquid fuel will leave valve 22. Thus the float 61 and therefore float element 59 will drop opening the needle valve 62 to again allow fuel vapors to be stored in the engine where they will be combusted with blow-by products via the conventional PCV system. Should any unanticipated vacuum develop in valve 22, the vacuum valve 70 will open and vapor and air at substantially atmospheric pressure from the engine will relieve the vacuum.

From the foregoing, it should be apparent that applicant has provided a system which will work in most conceivable situations with a minimum of components.

I claim:

1. A float type valve adapted for use with a fuel evaporative control system for a vehicle, said valve comprising:

a. a valve housing having at least two ports;

b. a float element located in said housing and adapted to close one of said ports upon movement by liquid fuel;

c. a vacuum valve located in said housing, said valve being adapted to relieve the vacuum in said housing when said element has closed one of said ports;

d. said vacuum valve being in communication with said one port when said vacuum valve is open;

e. said one port of said housing having a seat and said element comprising a float and a needle valve mounted thereon, said needle valve being adapted to engage said seat to close said one port;

f. said housing having guide means and said element having an extension adapted to move in said guide means to control movement of said element;

g. said guide means being located in the second of said two ports but not blocking said second port;

h. said valve housing having an annular wall surrounding said vacuum valve to form an air pocket thereabout in conjunction with liquid fuel to positively close the normally closed vacuum valve.

2. The valve of claim 1 in which said valve housing includes a body and a cover with sealing means therebetween.

3. The valve of claim 2 in which said seat and said vacuum valve are located in said cover and said second port and said guide means are located in said body.

4. The valve of claim 3 in which said vacuum valve is made of rubber-like material and is adapted to flex upon the application of vacuum thereto.

Claims

1. A float type valve adapted for use with a fuel evaporatIve control system for a vehicle, said valve comprising: a. a valve housing having at least two ports; b. a float element located in said housing and adapted to close one of said ports upon movement by liquid fuel; c. a vacuum valve located in said housing, said valve being adapted to relieve the vacuum in said housing when said element has closed one of said ports; d. said vacuum valve being in communication with said one port when said vacuum valve is open; e. said one port of said housing having a seat and said element comprising a float and a needle valve mounted thereon, said needle valve being adapted to engage said seat to close said one port; f. said housing having guide means and said element having an extension adapted to move in said guide means to control movement of said element; g. said guide means being located in the second of said two ports but not blocking said second port; h. said valve housing having an annular wall surrounding said vacuum valve to form an air pocket thereabout in conjunction with liquid fuel to positively close the normally closed vacuum valve.