US3882204A

US3882204A - Mechanically actuated vent switch

Info

Publication number: US3882204A
Application number: US440455A
Authority: US
Inventors: Amand James C St
Original assignee: Motors Liquidation Co
Current assignee: Motors Liquidation Co
Priority date: 1974-02-07
Filing date: 1974-02-07
Publication date: 1975-05-06
Anticipated expiration: 1992-05-06

Abstract

A mechanically actuated vapor vent includes a direct passage from the primary fuel chamber in a float bowl housing to an air horn outlet for transfer of vapor to a charcoal cannister. The direct vapor passage is under the control of a vent valve that is slidably supported on one end of a stem having the opposite end adapted to be connected to an accelerator plunger assembly for forcing a large quantity of fuel into the mixture passages of the carburetor for instant acceleration. The vent valve is positioned by means of a bias spring against a stop on the stem so as to be positioned by a throttle linkage mechanism into a closed position when the throttle is opened to prevent venting of the primary fuel chamber and into an opened position when the throttle is closed thereby to vent a vapor space above the primary fuel chamber. The accelerator pump stem is movable with respect to the slidable vent to permit operation of the accelerator pump independently of the position of the vent valve and to permit positioning of the vent valve independently of operation of the accelerator pump.

Description

United States Patent 1 3,882,204 St. Amand May 6, 1975 MECHANICALLY ACTUATED VENT SWITCH [57] ABSTRACT [75] Inventor: James C. St. Amand, Spencerport, A mechanically actuated vapor vent includes a direct N.Y. passage from the primary fuel chamber in a float bowl Assi nee General Motors Cor oration housing to an air horn outlet for transfer of vapor to a g De it h p charcoai cannister. The direct vapor passage is under 0 [C the control of a vent valve that is slidably supported [22] Filed: Feb. 7, 1974 on one end ofa stem having the opposite end adapted to be connected to an accelerator plunger assembly [2H Appl' 440455 for forcing a large quantity of fuel into the mixture passages of the carburetor for instant acceleration. [52] U.S. Cl. 261/34 A; 26l/DIG. 67; 261/72 R The vent valve is positioned by means of a bias spring [5 l] Int. Cl. F02m 5/08 against a stop on the stern so as to be positioned by a [58] Field of Search 261/34 A, DIG. 67, 72 R throttle linkage mechanism into a closed position when the throttle is opened to prevent venting of the [56] References Cited primary fuel chamber and into an opened position UNITED STATES PATENTS when the throttle is closed thereby to vent a vapor 2 MI 465 4/1956 Redman at al 261mm 67 space above the primary fuel chamber. The accelera- 2'756683 7/1956 261/34 A tor pump stem is movable with respect to the slidable I749 11/1963 Marsee H 261/34 A vent to permit operation of the accelerator pump in- 3,l89,330 6/1965 N w A v to 251/34 A dependently of the position of the vent valve and to 3,368,326 2/l968 Hervert .6 26l/DlGr 67 permit positioning of the vent valve independently of operation of the accelerator pump. Primary Examiner-Tim R. Miles Attorney. Agent, or FirmJ. C. Evans 2 Chums 4 Drawmg Figures 05 as w W e x /6' 8% 0 f 7/5 76 fiw 7 5&5 d3 5 A 72' PMENIEU HAY 6|975 SHEEI lUF 2 PATENTEI] HAY 8I975 3 882. 204

MECHANICALLY ACTUATED VENT SWITCH This invention relates to carburetors and more particularly to systems for venting the primary fuel chamber of a carburetor.

When an engine is started, the throttle is opened and additional fuel is directed into the mixture passages of the carburetor to produce an enriched air-fuel mixture at start. When the vehicle has stood for a substantial period of time under elevated ambient conditions, the fuel vapor formed in the primary fuel chamber of the float bowl housing can force liquid fuel out of the accelerating fuel flow passages of the carburetor back into the fuel bowl. Accordingly, various proposals have been made wherein the vapor pressure buildup in the primary fuel chamber of the fuel bowl housing is vented to an outside vent to insure a supply of liquid fuel into the air-fuel mixture passages of the carburetor.

An object of the present invention is to improve the supply of fuel to a carburetor during start conditions by the provision of a direct vapor vent passage formed in an air horn housing in communication with the primary fuel chamber of the carburetor and an outlet and wherein vapor is vented by a valve positioned by a stem common to an accelerator plunger assembly, the vent valve being movable positioned with respect to the accelerator pump stem to operate independently thereof in the event that the accelerator plunger assembly becomes inoperative.

Yet another object of the present invention is to provide an improved mechanically actuated vapor vent valve assembly on one end thereof and a vent valve on the other end thereof for controlling flow from a direct vapor passage between the primary fuel chamber in a float bowl housing and a vent opening exteriorly of the carburetor with means being provided to calibrate the position of the vent valve with respect to a stationary valve seat, said means being arranged so that either the pump or the vent valve can become inoperative without effecting the operability of the other operative component connected to the stem.

Still another object of the present invention is to provide an improved, combined, mechanically operated vapor vent valve and accelerator pump plunger operating mechanism wherein a common stem supports both the vent valve and the accelerator pump plunger including means for independently operating either the vent valve or the accelerator pump plunger in the event that the other operative component becomes inoperative and wherein means are provided on the common operating stem to axially adjust the position of the vent valve with respect thereto to calibrate it with respect to a valve seat interposed between an inlet and an outlet of a direct vent passage from the primary fuel chamber in a float bowl housing and an exterior vent opening.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings wherein a preferred embodiment of the present invention is clearly shown.

In the drawings:

FIG. 1 is a fragmentary top elevational view ofa carburetor including the present invention;

FIG. 2 is a fragmentary sectional view taken along the line 22 of FIG. 1;

FIG. 3 is a fragmentary sectional view taken along the line 3--3 of FIG. 1 with the vent valve and accelerator pump components shown in elevation; and

HO. 4 is a horizontal sectional view taken along the line 44 of FIG. 2 looking in the direction of the arrows.

Referring now to the drawing, in FIG. 1 a fragmen- 5 tary, top elevational view of a carburetor I0 is illustrated showing an air horn housing 12 having an upstanding circular tube l4 thereon which is in open communication with a controlled pressure region under the carburetor air cleaner. the tube 14 communicates with an air horn chamber 16 as seen in FIG. 3 which is communicated through a passage 18 in a gasket 20 interposed between the air horn housing 12 and an intermediate fuel bowl housing 22. The passage 18 defines a vent from the vapor space above fuel in a primary fuel chamber 24 in the fuel bowl housing 22 whereby vapors are directed into the chamber 16.

The air horn housing 12 further includes a passage 26 therein which communicates with the chamber for directing vapor therefrom to a tubular fitting 28 connected to the housing [2 at the passage 26 therein adapted to be connected to a charcoal cannister for absorbing vapor emissions from the carburetor during certain phases of operation.

The fuel bowl housing 22 has an internal wall portion 30 thereof directed interiorly of the primary fuel chamber 24 sealed with respect to the air horn housing 12 by the gasket 20. The internal wall portion includes a cylindrical bore 32 therein having a tapered opening 34 leading thereto receive an accelerator pump assembly 36 which is operative to force fuel through accelerating pump passages into mixture conduits of the carburetor to supply an additional amount of fuel for acceleration. The accelerator pump assembly 36 more particularly includes a squared stem 38 at one end thereof whichh is directed through a square opening 40 in a valve seat member 42 that is supportingly received within the air horn housing at the base of the tube 14. A pump plunger 44 integrally formed with the squared stem 28 extends interiorly of the bore 32. It includes an annular groove 46 therein adjacent the squared stem 38 to de fine a shoulder 48 against which is located a spring retainer 50 that engages one end of a pump spring 52 having the opposite end thereof supportingly received on a radial flange 54 on a pump piston retainer 56 which is secured to the plunger 44. A piston 58 has a radially inwardly directed flange 60 thereon secured to the retainer 56 and an outwardly flared skirt 62 which is in sliding sealing engagement with the bore 32 to force liquid fuel from a chamber 64 below the piston through a passage 65 when the piston 58 is reciprocated downwardly within the bore 32 and to draw liquid fuel back into the chamber 64 from an inlet passage 66 when the plunger is moved outwardly of the bore 32.

The squared stem 38 has an externally threaded extension 68 at the opposite end thereof which extends upwardly into the tube 14 through an open end 70 of the valve seat element 42. The open end has an annular lip 72 thereon defining a vent valve seat at a point interposed between the passage 18 from the vapor space above the primary fuel chamber 24 and the outlet passage 26 from the air horn housing chamber I6.

Vapor flow through the open end 70 between the passage 18 and the passage 26 is under the selective control ofa mechanically actuated vent valve assembly 74 which includes a vent valve element 76 with a central opening 78 therethrough. The vent valve element 3 76 is carried by a radially outwardly directed flange 80 on an open end of a stem adaptor 82 with an internally threaded bore 84 therethrough into which the threaded extension 68 is thereadably received.

The adaptor 82 is threaded with respect to the extension 68 to axially position the flange 80 thereon with respect to the annular valve seat defining lip 72 thereby to calibrate the position of the valve element 76 with respect to its seat. The squared stem 38 will hold the extension 68 against rotation as the adaptor is axially adjusted for calibration and will serve to guide both the accelerator pump assembly 36 and the vent valve assembly 74 for reciprocation with respect to the bore 32 and the annular lip 72 respectively.

The outer end of the stem adaptor 82 has ann annular groove 86 therein in which is seated a spring retainer 88 movable axially within the groove 86 with respect to the stem adaptor 82. A vent valve spring 90 has one end thereof in engagement with the spring retainer 88 and the opposite end thereof in engagement with a flat plate portion 92 of the valve element 76 to bias a flexible face 94 of the element 76 into sealed engagement with the flange 80 around the central opening 78 through the element 76 to seal therebetween. The spring 90 will also yield to permit relative axial movement between the valve element 76 and the outer surface of the stem adaptor 82 so as to permit the squared stem 38 and the intergral plunger 44 thereon to assume a full throttle acceleration position within the bore 32 wherein the piston 58 is located at the bottom of the bore 32 at the end of an accelerating fuel pump stroke The end 96 of the stem adaptor 82 has a transverse groove 98 formed thereacross. lt engages a rounded end 100 of a throttle lever 102 which extends through a slot 103 in the upper end of tube 14. Lever 102 has an intermediate portion 104 thereon pivotally secured to a pair of upstanding. spaced

brackets

106, 108 on the upper surface 110 of the air horn housing 12 by means of a pivot pin [12. An opposite end 114 of lever [02 includes an elongated slot 116 therein which receives a bent end 118 of a throttle link 120. The throttle link 120 is directed through openings 122. 123 in the air horn housing 12 and gasket thence through an opening 124 in the gasket into the interior of the carburetor. The link [20 has a bent portion 126 on the opposite end thereof which extends exteriorly of the carburetor for connection to a throttle plate thereof.

in operation. when the throttle is closed. the engine will be stopped and under elevated ambient temperature and engine soak conditions the vapor pressure within the vapor space above the liquid in the primary fuel chamber 24 will increase in pressure. Accordingly, during this phase of operation the lever 102 will be positioned by the throttle link 120 in a solid line position at which point a return spring 128 connected between lever [02 and tube 14 will tend to raise the end 100. A conventional accelerator pump return spring will then be free to raise pump 36 along with the stem adaptor 82 thereon upwardly within the tube 14. This will cause the valve element 76 to be raised with respect to the lip 72 thereby to open communication between the chamber 24 and the tubular fitting 28 through a path defined by the gasket passage 18. the air horn housing chamber 16 and the passage 26. During this vent phase of operation. the vapors are collected by a charcoal cannister exteriorly of the carburetor and pressure is relieved in the fuel chamber to assure a positive supply of liquid fuel into the mixture passage of the carburetor under warm engine start conditions.

When the throttle linkage opens the throttle valve of the carburetor approximately 7, the lever 102 is ro tated by the link 120 so as to move the rounded end downnwardly against the stem adaptor 82 to shift the valve element 76 into engagement with the annular lip 72 and the vent value spring 90 will maintain it in sealed biased relationship therewith to prevent venting of fuel to the charcoal cannister. Under these conditions. a vent path is provided from the vapor space above the primary fuel chamber 24 through the gasket passage 18 thence through the chamber 16 and outwardly of the tube 14 to the air cleaner whereby vapors are returned during engine operation to be consumed in the engine combustion process.

Positioning the throttle link in a wide open throttle position. as will occur under acceleration, will cause the lever 102 to shift the stem adaptor 82 downwardly within the tube 14 to cause the squared stem 38 and the plunger 44 to move interiorly of the bore 32 so as to cause the pump piston 58 to discharge liquid fuel from the bore 32 to the mixture passages of the carburetor. During this phase of operation, the adaptor stem 82 moves with respect to the vent valve element 76 through the central opening 78 therein and the vent valve spring 90 is compressed to freely accommodate this over-travel movement of the squared stem 38.

By virtue of the aforedescribed arrangement. the accelerator pump assembly 36 operates independently of the position of the vent valve element 76. Furthermore, the vent valve element 76 is positioned solely by the stern adaptor 82 and the vent valve spring 90 against the lip 72. Accordingly. in the event that any of the operative components of the accelerator pump assembly 36 become inoperative, the vent valve assembly 74 will still function to selectively direct vapors to the cannister when the throttle is closed and the enginer is offand to the air cleaner when the throttle is partially opened and the engine is running. As a result. the capacity of the cannister is not exceeded and fumes during engine operation will be drawn through the air cleaner for combustion within the engine. Likewise in the event that any of the operative components of the vent valve assembly 74 are rendered inoperative, the squared stem 38 and stem adaptor 82 will define a direct couple to the throttle link 120 so that the accelerator pump assembly 36 will still be operative.

While the embodiments of the present invention, as herein disclosed, constitute a preferred form, it is to be understood that other forms might be adopted.

What is claimed is:

l. A mechanical idle vent valve assembly comprising: a housing having a first passage in communication with a float bowl primary fuel chamber. said housing including a second passage adapted to be communicated with an inlet to a charcoal cannister, means forming a valve seat interposed between said first and second passages, a reciprocating shaft having a square cross section directed through said housing, said square shaft adapted to be connected to an accelerator plunger assembly within a float bowl ofa carburetor. means on said housing for supporting said square shaft for reciprocation with respect to said housing and against rotation with respect thereto, said square shaft having a threaded extension thereon. a stem adaptor having an internally threaded open ended portion thereon with a radially outwardly directed end flange threadably received on the threaded extension of said squared shaft for axial adjustment thereon, said stem adaptor including a circumferential groove formed thereon on the opposite end of said threaded portion from the flange end thereon, a spring retainer slidably supported within said groove, a valve element slidably supported on the outer surface of said stem adaptor at the opposite end thereof having a surface thereon supportingly received by said radially outwardly directed flange, a spring having one end thereof in engagement with said retainer and the opposite end in engagement with said valve for biasing said valve against said flange, said adaptor including an end portion thereof defining a bearing surface. an operating lever having a first portion thereon engageable with said bearing surface, means for pivotally supporting said lever for rotation with respect to said housing, said lever having a second portion thereon adapted to be connected to a throttle link for moving said first portion with respect to said bearing surface to cause said stem adaptor and said squared shaft to reciprocate with respect to said housing, said lever having a first opera tive position when the throttle is open to locate said valve element against said valve seat, said spring biasing said valve against said valve seat when said lever is in its first position to close communication between said first and second passages to prevent vapor transfer from the primary fuel chamber to the cannister when the throttle is open, said lever having a second operative position when the throttle is closed to position said vent valve in spaced relationship to said seat to communicate said first passage with said second passage thereby to direct vapor from the primary fuel chamber to the cannister, said lever having a third operative position wherein said stem adaptor and squared shaft are directed inwardly of the housing when the vent valve is closed to operate said plunger assembly with said vent valve being maintained sealed against said seat by said spring as said stem adaptor and squared shaft are moved axially relative thereto, said spring and said vent valve coacting to permit free sliding movement of said stern adaptor with respect to said seated vent valve to maintain said plunger assembly operative independently of the relative relationship between said vent valve and said valve seat and said vent valve being positioned independently of operation of said plunger as sembly.

2. In a carburetor having a fuel bowl housing defining a primary fuel chamber closed by an air horn housing and wherein an accelerator pump assembly is located within the primary fuel chamber for providing fuel enrichment under acceleration conditions, the improvement comprising: an air horn housing having a chamber with an inlet passage in communication with the pri mary fuel bowl and an outlet passage adapted to be connected to a charcoal cannister for collecting vapors from the primary fuel chamber, a valve seat formed in said air horn chamber between said inlet passages and said outlet passages, a vent valve located in overlying relationshhip with said valve seat movable with respect to said valve seat to open and close communication between the inlet passage to said chamber and the outlet passage therefrom, said movable vent valve having a central opening therethrough, a shaft directed through said opening, coacting means on said shaft and said air horn housing for preventing relative rotation therebetween, said shaft having one end thereof adapted to be connected to an accelerator plunger assembly and including a threaded extension on the other end thereof located centrally of said annular valve seat and extend ing therefrom into said air horn housing chamber. a stem adaptor including a flanged opened end thereon and an internally threaded bore threadably received on said extension for axially positioning said stem adaptor with respect to said threaded extension, said vent valve having a central opening therethrough through which said stem adaptor extends with said flanged end engaging said vent valve around the central opening therein for supporting said vent valve for movement away from said annular valve seat, said stem adaptor including a grooved upper end thereon having a spring retainer slidably supported therein, spring means connected between said retainer and said vent valve for holding said vent valve against said flange, actuator means for reciprocating said stem adaptor and said shaft with respect to said air horn housing upon throttle movement, said actuator means including a first operative position wherein said stem adaptor and shaft are moved inwardly of said chamber to position said vent valve in sealed engagement with said annular valve seat to prevent vapor transfer from the primary fuel bowl to the cannister when the throttle is open said actuator means having a second position wherein said stem adaptor and spring retainer are moved with respect to said closed vent value for operating said plunger assembly when said vent valve is closed, said actuator means having a third operative position wherein said shaft and said stem adaptor are moved outwardly of said air horn housing to locate said vent valve in spaced relationship with said valve seat to permit transfer of vapors from the primary fuel chamber to the cannister,

Claims

1. A mechanical idle vent valve assembly comprising: a housing having a first passage in communication with a float bowl primary fuel chamber, said housing including a second passage adapted to be communicated with an inlet to a charcoal cannister, means forming a valve seat interposed between said first and second passages, a reciprocating shaft having a square cross section directed through said housing, said square shaft adapted to be connected to an accelerator plunger assembly within a float bowl of a carburetor, means on said housing for supporting said square shaft for reciprocation with respect to said housing and against rotation with respect thereto, said square shaft having a threaded extension thereon, a stem adaptor having an internally threaded open ended portion thereon with a radially outwardly directed end flange threadably received on the threaded extension of said squared shaft for axial adjustment thereon, said stem adaptor including a circumferential groove formed thereon on the opposite end of said threaded portion from the flange end thereon, a spring retainer slidably supported within said groove, a valve element slidably supported on the outer surface of said stem adaptor at the opposite end thereof having a surface thereon supportingly received By said radially outwardly directed flange, a spring having one end thereof in engagement with said retainer and the opposite end in engagement with said valve for biasing said valve against said flange, said adaptor including an end portion thereof defining a bearing surface, an operating lever having a first portion thereon engageable with said bearing surface, means for pivotally supporting said lever for rotation with respect to said housing, said lever having a second portion thereon adapted to be connected to a throttle link for moving said first portion with respect to said bearing surface to cause said stem adaptor and said squared shaft to reciprocate with respect to said housing, said lever having a first operative position when the throttle is open to locate said valve element against said valve seat, said spring biasing said valve against said valve seat when said lever is in its first position to close communication between said first and second passages to prevent vapor transfer from the primary fuel chamber to the cannister when the throttle is open, said lever having a second operative position when the throttle is closed to position said vent valve in spaced relationship to said seat to communicate said first passage with said second passage thereby to direct vapor from the primary fuel chamber to the cannister, said lever having a third operative position wherein said stem adaptor and squared shaft are directed inwardly of the housing when the vent valve is closed to operate said plunger assembly with said vent valve being maintained sealed against said seat by said spring as said stem adaptor and squared shaft are moved axially relative thereto, said spring and said vent valve coacting to permit free sliding movement of said stem adaptor with respect to said seated vent valve to maintain said plunger assembly operative independently of the relative relationship between said vent valve and said valve seat and said vent valve being positioned independently of operation of said plunger assembly.

2. In a carburetor having a fuel bowl housing defining a primary fuel chamber closed by an air horn housing and wherein an accelerator pump assembly is located within the primary fuel chamber for providing fuel enrichment under acceleration conditions, the improvement comprising: an air horn housing having a chamber with an inlet passage in communication with the primary fuel bowl and an outlet passage adapted to be connected to a charcoal cannister for collecting vapors from the primary fuel chamber, a valve seat formed in said air horn chamber between said inlet passages and said outlet passages, a vent valve located in overlying relationshhip with said valve seat movable with respect to said valve seat to open and close communication between the inlet passage to said chamber and the outlet passage therefrom, said movable vent valve having a central opening therethrough, a shaft directed through said opening, coacting means on said shaft and said air horn housing for preventing relative rotation therebetween, said shaft having one end thereof adapted to be connected to an accelerator plunger assembly and including a threaded extension on the other end thereof located centrally of said annular valve seat and extending therefrom into said air horn housing chamber, a stem adaptor including a flanged opened end thereon and an internally threaded bore threadably received on said extension for axially positioning said stem adaptor with respect to said threaded extension, said vent valve having a central opening therethrough through which said stem adaptor extends with said flanged end engaging said vent valve around the central opening therein for supporting said vent valve for movement away from said annular valve seat, said stem adaptor including a grooved upper end thereon having a spring retainer slidably supported therein, spring means connected between said retainer and said vent valve for holding said vent valve against said flange, actuator means for reciprocatIng said stem adaptor and said shaft with respect to said air horn housing upon throttle movement, said actuator means including a first operative position wherein said stem adaptor and shaft are moved inwardly of said chamber to position said vent valve in sealed engagement with said annular valve seat to prevent vapor transfer from the primary fuel bowl to the cannister when the throttle is open said actuator means having a second position wherein said stem adaptor and spring retainer are moved with respect to said closed vent value for operating said plunger assembly when said vent valve is closed, said actuator means having a third operative position wherein said shaft and said stem adaptor are moved outwardly of said air horn housing to locate said vent valve in spaced relationship with said valve seat to permit transfer of vapors from the primary fuel chamber to the cannister.