WO2016210309A1

WO2016210309A1 - Float bowl carburetor

Info

Publication number: WO2016210309A1
Application number: PCT/US2016/039330
Authority: WO
Inventors: Teruhiko Tobinai
Original assignee: Walbro Llc
Priority date: 2015-06-25
Filing date: 2016-06-24
Publication date: 2016-12-29

Abstract

A carburetor may include a main body including a fuel and air mixing passage and a fuel bowl having a latch and a body defining a fuel chamber. The body is imperforate and the latch engages the main body to at least in part retain the fuel bowl on the main body. In at least some implementations, the fuel bowl is formed from plastic and the main body is formed from metal. The fuel bowl may include a mount outboard of and spaced from the fuel chamber and the mount is held against the main body. A strainer cup may be carried by the main body and include a trap surface that holds the mount against the main body to simplify retention of the fuel bowl against the main body.

Description

FLOAT BOWL CARBURETOR

Reference to Co-pending Applications

This application claims the benefit of U.S. Provisional Patent Application Serial No. 62/184,540 filed June 25, 2015, which is incorporated herein by reference in its entirety.

Technical Field

The present disclosure relates generally to float bowl carburetors.

Background

Float bowl carburetors are generally known in the art and include a body that is mounted on an engine or intake manifold. Float bowl carburetors generally include a fuel and air mixing passage and a fuel inlet passage to allow fuel into the carburetor. Air is supplied to the mixing passage through an air filter of an air cleaner on an air inlet side of the carburetor. The carburetor generally has a float regulated fuel chamber defined in a bowl that is attached to the carburetor main body. The float assembly is connected to a metering valve assembly which allows fuel to enter the bowl and maintains a substantially constant pressure of fuel within the bowl. The bowl is mounted to the carburetor main body by a plurality of fasteners, such as screws, and the bowl may include one or more openings through it and into the fuel chamber to receive a fastener that mounts the bowl to the main body, or carries a valve or other component. Such openings have to be sealed against fuel leakage and increase the complexity and number of components in the carburetor. Further, the multiple fasteners used to connect the bowl to the main body increase the time, cost and complexity of assembling the carburetor.

Summary

A carburetor may include a main body including a fuel and air mixing passage and a fuel bowl having a latch and a body defining a fuel chamber. The body is imperforate and the latch engages the main body to at least in part retain the fuel bowl on the main body.

In at least some implementations, the fuel bowl is formed from plastic and the main body is formed from metal. The fuel bowl may include a mount outboard of and spaced from the fuel chamber and the mount is held against the main body. A strainer cup may be carried by the main body and include a trap surface that holds the mount against the main body to simplify retention of the fuel bowl against the main body. A fuel path from a fuel source to the fuel bowl chamber may include an inlet that leads to a chamber defined at least in part by the strainer cup and an outlet that leads from the chamber defined at least in part by the strainer cup to the fuel chamber so that fuel that enters the fuel bowl is communicated first with the chamber defined at least in part by the strainer cup. A filter or strainer may be carried in that chamber, to filter fuel before it enters the fuel chamber.

In at least some implementations, a carburetor includes a main body, a fuel bowl and a cup. The main body includes a fuel and air mixing passage. The fuel bowl has a body defining a fuel chamber and a mount. And the cup is carried by the main body and has a trap surface that overlies a portion of the mount and traps that portion of the mount against the main body to retain the fuel bowl relative to the main body.

Brief Description of the Drawings

The following detailed description of certain embodiments and best mode will be set forth with reference to the accompanying drawings, in which:

FIG. 1 is a top perspective view of a fuel bowl carburetor;

FIG. 2 is a bottom perspective view of the carburetor;

FIG. 3 is another perspective view of the carburetor;

FIG. 4 is a partial side perspective view of the carburetor;

FIG. 5 is a partially exploded view similar to FIG. 4 showing a fuel bowl separated from a main carburetor body and a strainer cup separated from the fuel bowl;

FIG. 6 is an enlarged, fragmentary sectional view showing a strainer cup of the carburetor;

FIG. 7 is a sectional view of the carburetor; and

FIG. 8 is a fragmentary sectional view of a fuel shutoff valve.

Detailed Description

Referring in more detail to the drawings, FIGS. 1-3 illustrate a float bowl type carburetor 10 having a main body 12 with a fuel and air mixing passage 14 extending therethrough, a fuel bowl 16 carried by the main body 12 and a fuel control assembly 18 through which fuel flows to the fuel bowl. As shown in FIG. 3, a throttle valve 20 is rotatably supported in the vicinity of an outlet end 22 of the fuel and air mixing passage 14, and as shown in FIGS. 1 and 4, a choke valve 24 may be rotatably supported in the vicinity of an inlet end 26 of the mixing passage 14.

The fuel bowl 16 is coupled to the main body 12 surrounding a fuel metering and supply assembly 30 (FIG. 5) with a seal 32 between the fuel bowl 16 and main body 12 to provide a fluid tight seal between them. The fuel bowl 16 may have a traditional shape (or any desired shape) and is shown with an imperforate body portion 34 that defines a fuel chamber 35 and is open at an upper end 36 which, in assembly, is sealed to the carburetor main body 12. That is, in at least some implementations, the body portion 34 that defines the fuel chamber 35 does not have any openings or penetrations therethrough which greatly reduces the possibility of fuel leakage from the fuel bowl 16 and avoids the needs for fasteners, seals and related components. As is known in the art, a horseshoe-shaped float 42 is received in the fuel chamber. The float 42 is buoyant and hence, responsive to the level of liquid fuel in the fuel chamber 35 so that when the fuel level in the fuel chamber 35 lowers, an inlet valve (not shown) is opened so that fuel in a fuel tank (not shown) is provided into the fuel chamber 35.

The fuel control assembly may include a filter or strainer 44 (diagrammatically shown in FIG. 7) and a fuel shutoff valve 46. The strainer 44 may be provided to filter fuel received from the fuel tank before the fuel enters the fuel bowl 16 for delivery to an engine. The strainer 44 may be received within a strainer chamber 48 which may be defined between a cup 50 and the main body 12. Alternatively, the cup 50 may be used without any filter member or strainer, and may catch and retain sediment that settles out of the fuel. A fuel inlet 52 communicates with the strainer chamber 48 and with the fuel tank to admit fuel into the strainer chamber. A fuel outlet 54 (FIGS. 6 and 7) communicates with the strainer chamber 48 and with the fuel chamber 35 of the fuel bowl 16 to provide fuel to the fuel chamber 35.

The fuel shutoff valve 46 may include a manually rotatable or otherwise movable lever 56 coupled to a valve body 58 that is received within a cavity 59 formed in the main body 12 between the fuel inlet 52 and the fuel outlet 54. As shown in FIGS. 7 and 8, the valve body 58 may be generally annular with a circular periphery and a central bore 60 through which a post 62 formed on the main body 12 extends. The valve body may also have a slot 64 that selectively communicates the fuel inlet 52 with the strainer chamber 48 via openings 66 and 68 in a seal 70 disposed between the valve body 58 and a bottom wall 72 of the cavity 59. In a first position of the valve 46, the slot 64 does not communicate the inlet 52 and chamber 48 and fuel from the fuel tank is prevented from flowing to the strainer chamber 48 and hence, the fuel bowl 16. In a second position of the valve 46, fuel can flow through the valve from the inlet 52 to the chamber 48 and then to the fuel bowl. The valve 46 rotates about the post 62 when the valve is rotated between its first and second positions. In this way, when the engine is not running, the valve 46 can be rotated to the first position to prevent fuel in the tank from draining through the carburetor. To permit fuel flow when engine operation is desired, the shutoff valve 46 can be rotated to its second position. Fuel may flow under the force of gravity through the valve 46 and to the strainer chamber which may be located below the valve and cavity, or a pump may be provided in the system.

To retain the shutoff valve 46 a cover 74 is provided over the shutoff valve 46 and is secured to the main body 12. In the implementation shown, the cover 74 seals against a sidewall 76 of the cavity 59 in which the shutoff valve 46 is received and is secured to the main body 12 by a single fastener 78 coupled to the post 62. The fastener 78 may be threaded and the post 62 may include a complementarity threaded bore 80 (FIG. 7). The post 62 preferably extends through the valve body 58, and the cover 74 engages the post 62 and does not bear on the valve body 58 with any significant force so that the valve 46 may be rotated between its first and second positions.

The cup 50 may be sealed to the main body 12 by a seal 82 and secured to the main body 12 by one or more fasteners 84. In at least some implementations, a single fastener 84 is used to secure the cup 50 to the main body 12, and as will be discussed below, the fuel bowl 16 may also be secured to the main body 12 by this same fastener 84. One or both of the cup 50 and fuel bowl 16 may be formed from a plastic material to reduce weight and reduce the cost of the carburetor.

In at least some implementations, including the implementation shown in the drawings, the fuel bowl 16 includes a bracket or mount 86 that is associated with the cup 50 so that when the cup is secured to the main body 12, the fuel bowl 16 also is secured, at least in part, to the main body 12. In the implementation shown, the mount 86 includes an opening 88 that surrounds at least a portion of the cup 50. While shown as a fully circular opening 88 that completely surrounds a generally cylindrical sidewall 90 of the cup 50, the opening 88 need not be circumferentially continuous or enclosed and may instead be a partial opening such that the fuel bowl does not fully surround the cup. Additionally, the opening 88 and cup 50 may include shapes other than circular or partially circular for the opening 88 and cylindrical (round exterior) for the cup sidewall 90. As shown, the opening 88 is defined within the mount 86 which extends laterally from the fuel bowl body 34 and is integrally formed from the same piece of material as the remainder of the fuel bowl 16 (including, but not limited to, the body 34). In at least some implementations, the mount 86 is external to the fuel chamber 35 and not in communication therewith.

The cup 50 includes a trap surface 92 which may be defined on an outwardly extending tab or flange 94, that overlies at least part of the fuel bowl 16 (e.g. the mount 86) and traps part of the fuel bowl against the main body 12. In this way, when the cup 50 is secured to the main body 12, the fuel bowl 16 is also secured at least in part to the main body 12. In the implementation shown, the trap surface 92 includes a circumferentially continuous and radially outwardly extending flange 94 of the cup 50 that is larger in size than the opening 88 so that the flange 94 overlies the mount 86 completely around the opening 88.

In at least some implementations, the cup 50 is secured to the main body by a single screw 84 received through an opening 96 in the main body 12 and within a pocket or blind bore 98 in the cup 50 (which does not open into the strainer chamber 48 so no seals are needed in the area of the fastener 84). Alignment of the fastener 84 with the opening 96 and bore 98 ensures that the cup 50 is full seated within the chamber 48 and relative to the main body 12, and likewise ensures that the fuel bowl 16 is in its proper position relative to the main body 12.

To provide a second point of connection between the fuel bowl 16 and the main body 12, the fuel bowl 16 may include a coupler 100 adapted to overlie and engage a portion of the main body as shown in FIG. 3. This second point of connection may be circumferentially spaced apart from the mount 86, and in some implementations it may be generally diametrically opposed or opposite to the mount 86. The two points of connection provide a more robust connection that resists fuel leakage from the fuel bowl 16 or separation of the fuel bowl 16 from the main body 12. In the implementation shown, the coupler includes a hook or J-shaped latch 100 that extends outwardly from the fuel bowl body 34 and overlies a flange or catch 102 on the main body 12. The latch 100 may be formed from the same piece of material as the fuel bowl 16 so that the latch 100 is integral with the fuel bowl 16. The latch 100 may engage the main body 12 in the opposite direction that the cup 50 engages the fuel bowl 16. In the implementation shown, the fuel bowl 16 is attached beneath the mixing passage 14, the cup 50 engages the fuel bowl 16 from below and traps the fuel bowl mount 86 in a first direction (e.g. upwardly, relative to gravity and in the orientation shown in FIGS 3 and 4) against the main body 12, while an end of the latch 100 is received over the catch 102 and bears downwardly on the catch 102. A lateral stop 104 (FIG. 3) may help to locate and retain the latch 100 on the catch 102. The point of contact between the latch 100 and catch 102 may be located above the height of the seal 32, and the latch 100 may extend above the open end 36 of the fuel bowl body 34.

While the forms of the invention herein disclosed constitute presently preferred embodiments, many others are possible. It is not intended herein to mention all the possible equivalent forms or ramifications of the invention. It is understood that the terms used herein are merely descriptive, rather than limiting, and that various changes may be made without departing from the spirit or scope of the invention.

Claims

Claims;

1. A carburetor, comprising:

a main body including a fuel and air mixing passage;

a fuel bowl having a latch and a body defining a fuel chamber wherein the body is imperforate and the latch engages the main body to at least in part retain the fuel bowl on the main body.

2. The carburetor of claim 1 wherein the fuel bowl is formed from plastic and the main body is formed from metal.

3. The carburetor of claim 1 wherein the fuel bowl includes a mount outboard of and spaced from the fuel chamber and the mount is held against the main body.

4. The carburetor of claim 3 which also includes a strainer cup carried by the main body and including a trap surface that holds the mount against the main body.

5. The carburetor of claim 4 wherein the strainer cup is retained to the main body by a fastener with the trap surface engaged with the mount to retain the fuel bowl relative to the main body.

6. The carburetor of claim 3 wherein the mount includes an opening and at least part of the strainer cup is received through the opening.

7. The carburetor of claim 1 which also includes a fuel shutoff valve having an annular body, a post carried by the main body that extends through the annular body, a cover received over the body and a fastener coupled to the post to hold the cover on the main body.

8. The carburetor of claim 5 wherein the strainer cup includes a blind bore and the fastener extends into the blind bore and through an opening in the main body to retain the position of the strainer cup relative to the main body.

9. The carburetor of claim 4 wherein a chamber is defined between the strainer cup and the main body, and the carburetor includes a fuel inlet that communicates with the chamber to admit fuel into the chamber, and a fuel outlet that communicates with the strainer chamber with the fuel chamber of the fuel bowl so that fuel flows to the chamber between the cup and main body before flowing to the fuel chamber in the fuel bowl.

10. The carburetor of claim 9 wherein a filter or strainer is carried within the chamber that is defined at least partially by the strainer cup.

1 1. A carburetor, comprising:

a main body including a fuel and air mixing passage;

a fuel bowl having a body defining a fuel chamber and a mount; and a cup carried by the main body and having a trap surface that overlies a portion of the mount and traps said portion of the mount against the main body to retain the fuel bowl relative to the main body.

12. The carburetor of claim 1 1 wherein the cup is retained to the main body by a fastener with the trap surface engaged with the mount to retain the fuel bowl relative to the main body.

13. The carburetor of claim 11 wherein the mount includes an opening and at least part of the cup is received through the opening.

14. The carburetor of claim 1 1 wherein the fuel bowl also includes a latch engaged with the main body to provide a second point of connection of the fuel bowl to the main body.

15. The carburetor of claim 14 wherein the fuel bowl body has an open end received adjacent to the main body and the latch engages the main body at a location above the open end.

16. The carburetor of claim 11 wherein a chamber is defined between the cup and the main body, and the carburetor includes a fuel inlet that communicates with the chamber to admit fuel into the chamber, and a fuel outlet that communicates with the strainer chamber with the fuel chamber of the fuel bowl so that fuel flows to the chamber between the cup and main body before flowing to the fuel chamber in the fuel bowl.

17. The carburetor of claim 16 wherein a filter or strainer is carried within the chamber that is defined at least partially by the strainer cup.