CN114502406A - Improved fuel tank isolation valve with integrated stepper motor - Google Patents

Abstract

The present invention relates to an improved fuel tank isolation valve (FTIV) assembly. The present invention relates to a stepper motor driven valve having application in an EVAP system and for the controlled flow of fuel vapor from the fuel tank to the canister under both overpressure and overvacuum conditions during refueling At the same time, the pressure inside the fuel tank is maintained in a protected pressure range.

Description

Improved fuel tank isolation valve with integrated stepper motor

technical field

The present invention relates to an improved fuel tank isolation valve. In particular, the present invention relates to an improved fuel tank isolation valve integrated with a stepper motor for overpressure relief and overvacuum relief plunger movement and drop-in functionality, the valve having less weight and Cost-effective compact design and provide precise controlled flow.

Background technique

Hybrid vehicles run on electricity most of the time, and the internal combustion engine is idle. Since the fuel tank is a closed system, it generally results in a positive pressure inside the fuel tank due to evaporation of the stored fuel. Additionally, it is necessary for the vehicle to maintain elevated pressure in the fuel tank to suppress the rate of fuel vapor generation and minimize hydrocarbon emissions to the atmosphere. The most obvious solution to overcome the problem is to provide a fuel tank isolation valve (FTIV) coupled to the fuel tank to control the ventilation of the fuel tank. A fuel tank isolation valve (FTIV) may be located in the conduit between the fuel tank and the fuel vapor canister in the evaporative emission control system. It opens automatically when the pressure exceeds the protection limit and the valve is electrically actuated when refueling.

The fuel tank isolation valve (FTIV) also enables fuel vapor containment in the fuel tank until conditions are not suitable for the engine to handle excess vapor. Typically, the fuel tank isolation valve includes an electrically controlled solenoid valve to open and close the inlet and outlet with less precise or no control of the opening in the intermediate position. Therefore, there is no precise control of the flow of fuel vapor from the fuel tank to the canister when refueling.

In US20020112702A1, a method for operating a fuel tank isolation valve and a tank vent valve is disclosed. The fuel tank isolation valve has a first port, a second port, an electric actuator, and a valve body. The first port is in fluid communication with the fuel vapor collection canister and the second port is in fluid communication with the fuel tank. An electric actuator moves the valve body to control fluid communication between the first port and the second port. And the tank vent valve controls ambient fluid flow to the valve vapor collection tank. The method includes supplying a first electrical signal to the electric actuator such that the valve body permits substantially unrestricted flow of fuel vapor between the first port and the second port, supplying the second electrical signal to the electric actuator an actuator such that the valve body substantially prevents fuel vapor flow between the first and second ports, and a third electrical signal is supplied to the electric actuator such that the valve body provides a flow of fuel vapor between the first and second ports restricted fuel vapor flow, and a fourth electrical signal is supplied to the canister vent valve to permit ambient fluid flow into the fuel vapor collection canister. In such a system, the fuel tank isolation valve is controlled by an electrical actuator such as a solenoid valve, which is a typical component and which provides predetermined opening and closing settings and is costly. Controlling the solenoid valve is again difficult.

In US20020088441A1, a system and method for controlling evaporative emissions of volatile fuels is disclosed. The system preferably has a fuel vapor collection canister, a dump valve, an isolation valve and a fuel tank. An isolation valve includes a housing, a valve body, and a seal. The housing has a first port in fluid communication with the supply port of the fuel vapor collection canister, a second port, and a fuel vapor flow path extending between the first and second ports. The valve body is movable relative to the housing along an axis between the first configuration and the second configuration. The first configuration permits substantially unrestricted fuel vapor flow between the first and second ports, and the second configuration substantially prevents fuel vapor flow between the first and second ports. A fuel tank is in fluid communication with the second port of the isolation valve. In the system, the fuel tank isolation valve is controlled by an electrical actuator such as a solenoid valve, which is a typical component and which provides predetermined opening and closing settings and is expensive. Controlling the solenoid valve is again difficult.

Accordingly, the present invention overcomes the disadvantages of the cited technology and provides an improved fuel tank isolation valve incorporating a stepper motor operating as an actuator. This will result in a compact design, precise functional control, cost efficiency, less weight and a reduced number of components in the overall assembly.

Purpose of invention

A primary object of the present invention is to provide an improved fuel tank isolation valve assembly that allows for precise controlled flow and a low cost compact design.

Another primary object of the present invention is to provide an assembly that includes a nozzle, a threaded plunger, and a stepper motor to control the opening and closing of the fuel tank isolation valve.

Yet another primary object of the present invention is to provide an assembly for controlling the opening and closing of a valve by linear movement of a threaded plunger.

A further object of the present invention is to provide an assembly that allows automatic opening and closing of the valve by means of a compression spring when the pressure or vacuum inside the fuel tank exceeds a limit.

SUMMARY OF THE INVENTION

The present invention relates to an improved fuel tank isolation valve (FTIV) assembly. More specifically, the present invention relates to a stepper motor driven valve having application in EVAP systems and for use in both overpressure and overvacuum conditions during refueling, along with fuel from tank to tank Together, the controlled flow of vapor maintains the pressure inside the fuel tank within a protected pressure range.

In a main embodiment, the present invention provides an assembly of FTIVs. The assembly includes a nozzle with an integrated tank port for connecting the valve to the fuel tank, a tank port for connecting the valve to the tank, and a stepper motor for electrical opening and closing of the valve. The stepper motor includes a motor housing, a rotor with internal threads, a ball bearing, and a moving plunger with threads on its outer diameter. The sub-assembly further includes: a seal sub-assembly for over-pressure release (OPR), wherein a compression spring is fixed above and in contact with the sealing surface to perform an over-pressure release function; a seal for over-vacuum release (OVR) An assembly with a compression spring secured below it and in contact with the sealing surface to perform an over-vacuum function. The motor housing has an internally threaded rotor and ball bearings that reduce friction when rotating. The threaded plunger fastened to the cavity is fastened to the threaded rotor of the motor, thus completing the assembly of the FTIV. Linear movement of the threaded plunger in the motor housing causes the valve to open and close.

In yet another embodiment, the present invention provides an improved FTIV assembly in idle conditions. The idle condition allows the seal sub-assembly for the OVR and the seal sub-assembly for the OPR to close, thus not connecting the tank mouth to the tank mouth. The compression spring for the OVR supports the seal subassembly (OVR), and at the same time, the compression spring for the OPR supports the seal subassembly (OPR) and keeps the valve closed.

In yet another embodiment, the present invention provides an improved FTIV assembly in open or fueled conditions. Fueling conditions allow energization of the motor to cause the valve to open. As the rotor of the motor rotates, the plunger moves up and down depending on the direction of rotation of the motor used to open and close the valve during refueling.

In yet another embodiment, the present invention provides an improved FTIV assembly in OPR conditions. The OPR conditions allow compression of the compression spring for the OPR and lift the seal subassembly (OPR) upward, which creates a flow of fuel vapor from the tank port to the tank port when the pressure exceeds a predetermined limit.

In yet another embodiment, the present invention provides an improved FTIV assembly in OVR conditions. The OVR conditions allow compression of the compression spring for the OVR and downward movement of the seal sub-assembly (OVR), which creates a flow of fuel vapor from the tank mouth to the tank mouth when the vacuum exceeds a predetermined limit.

Brief Description of Drawings

1(a) and 1(b) are a perspective view and an exploded view, respectively, of a fuel tank isolation valve according to the present invention.

Figure 2(a) is a cross-sectional view of a fuel tank isolation valve according to the present invention.

Figure 2(b) is an enlarged cross-sectional view of a fuel tank isolation valve according to the present invention.

3(a) and 3(b) are a cross-sectional view and an enlarged cross-sectional view, respectively, of a fuel tank isolation valve in an idle condition in accordance with the present invention.

Figure 4(a) is a cross-sectional view of a fuel tank isolation valve during refueling in accordance with the present invention.

4(b), 4(c), 4(d) and 4(e) are enlarged cross-sectional views of a fuel tank isolation valve during refueling in accordance with the present invention.

Figure 5(a) is a cross-sectional view of a fuel tank isolation valve operating in OPR conditions in accordance with the present invention.

5(b) and 5(c) are enlarged cross-sectional views of a fuel tank isolation valve operating in OPR conditions in accordance with the present invention.

Figure 6(a) is a cross-sectional view of a fuel tank isolation valve operating in OVR conditions in accordance with the present invention.

6(b) and 6(c) are enlarged cross-sectional views of a fuel tank isolation valve operating in OVR conditions in accordance with the present invention.

Detailed ways

Many aspects of the present invention may be better understood by reference to the following drawings. Components in the figures are not necessarily drawn to scale. Instead, emphasis is placed on clearly illustrating the components of the invention. Furthermore, like reference numerals refer to corresponding parts throughout the several views of the drawings. Before explaining at least one embodiment of the invention, it is to be understood that the embodiments of the invention are not limited in their application to the details of construction and the arrangement of components set forth in the following description or illustrated in the accompanying drawings. Embodiments of the invention are capable of being practiced and carried out in various ways. Also, the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting.

The present invention relates to an improved fuel tank isolation valve (FTIV) assembly. In particular, the present invention relates to a stepper motor driven valve having application in EVAP systems and for use during refueling, under both overpressure and overvacuum conditions, along with fuel vapor from the fuel tank to the canister. Together with the controlled flow, the pressure inside the fuel tank is maintained within a protected pressure range.

In a main embodiment, the present invention provides an assembly of FTIVs. The assembly includes a nozzle with an integrated tank port for connecting the valve to the fuel tank, a tank port for connecting the valve to the tank, and a stepper motor for electrical opening and closing of the valve. The stepper motor includes a motor housing, a rotor with internal threads, a ball bearing, and a moving plunger with threads on its outer diameter. The sub-assembly further includes: a seal sub-assembly for over-pressure release (OPR), wherein a compression spring is fixed above and in contact with the sealing surface to perform an over-pressure release function; a seal for over-vacuum release (OVR) An assembly with a compression spring secured below it and in contact with the sealing surface to perform an over-vacuum function. The motor housing has an internally threaded rotor and ball bearings that reduce friction when rotating. The threaded plunger fastened to the cavity is fastened to the threaded rotor of the motor, thus completing the assembly of the FTIV. Linear movement of the threaded plunger in the motor housing causes the valve to open and close.

In yet another embodiment, the present invention provides an improved FTIV assembly in idle conditions. The idle condition allows the seal sub-assembly for the OVR and the seal sub-assembly for the OPR to close, thus not connecting the tank mouth to the tank mouth. The compression spring for the OVR supports the seal subassembly (OVR), and at the same time, the compression spring for the OPR supports the seal subassembly (OPR) and keeps the valve closed.

In yet another embodiment, the present invention provides an improved FTIV assembly in open or fueled conditions. Fueling conditions allow energization of the motor to cause the valve to open. As the rotor of the motor rotates, the plunger moves up and down depending on the direction of rotation of the motor used to open and close the valve during refueling.

In yet another embodiment, the present invention provides an improved FTIV assembly in OPR conditions. The OPR conditions allow compression of the compression spring for the OPR and lift the seal subassembly (OPR) upward, which creates a flow of fuel vapor from the tank port to the tank port when the pressure exceeds a predetermined limit.

In yet another embodiment, the present invention provides an improved FTIV assembly in OVR conditions. The OVR conditions allow compression of the compression spring for the OVR and downward movement of the seal sub-assembly (OVR), which creates a flow of fuel vapor from the tank mouth to the tank mouth when the vacuum exceeds a predetermined limit.

Referring to Figure 1(a), there is shown a cross-sectional view of a fuel tank isolation valve (10) according to the present invention. The fuel tank isolation valve comprises a valve housing (11) assembled on the motor housing (12), wherein the valve housing (11) comprises a tank opening (13) and a tank opening (14), and the electrical The casing (12) has an electrical connection port (15).

Referring to Figure 1(b), there is shown an exploded view of the fuel tank isolation valve (10) according to the present invention. The assembly includes a nozzle with an integrated tank port (14) for connecting the valve to the fuel tank, a tank port (13) for connecting the valve to the tank, and a stepper motor for electrical opening and closing of the valve (17). The sub-assembly further comprises: a sealing sub-assembly (4) for over-pressure release (OPR), wherein a compression spring (3) is fixed above it and in contact with the sealing surface to perform an over-pressure release function; for over-vacuum release (OVR) seal sub-assembly (7) with a compression spring (6) fixed below it and in contact with the sealing surface to perform an over-vacuum function. The motor housing (12) has an internally threaded rotor (20) and ball bearings that reduce friction when rotated. The threaded plunger (16) fastened to the cavity is fastened to the threaded rotor of the motor, thus completing the assembly of the FTIV (10).

Referring now to Figure 2(a), the present invention provides a cross-sectional view of an FTIV assembly. The assembly (10) includes a nozzle with an integrated tank port (14) for connecting the valve to the fuel tank, a tank port (13) for connecting the valve to the tank, and a valve for electrical opening and closing of the valve. Stepper motor (17). The stepper motor (17) comprises a motor housing (12), a rotor (20) with internal threads, a ball bearing (9) and a moving plunger (16) with threads on its outer diameter. The sub-assembly further comprises: a sealing sub-assembly (4) for overpressure relief (OPR), wherein the compression spring (3) is fixed above it and in contact with the sealing surface (5) to perform the overpressure relief function; for An over-vacuum release (OVR) seal sub-assembly (7) with a compression spring (6) fixed below it and in contact with the sealing surface (8) to perform the over-vacuum function. The motor housing (12) has an internally threaded rotor (20) and ball bearings (9) that reduce friction when rotated. The threaded plunger (16) fastened to the cavity is fastened to the threaded rotor (20) of the motor, thus completing the assembly of the FTIV. Linear movement of the threaded plunger (16) in the motor housing causes the valve (10) to open and close.

Referring to Figure 2(b), there is shown an enlarged cross-sectional view of a fuel tank isolation valve in accordance with the present invention. A seal sub-assembly (4) is fitted on the sealing surface (5) for the OPR function to provide a seal for the OPR function. Also, a seal sub-assembly (7) is fitted under the sealing surface (8) for the OVR function to provide sealing for both the OVR function and the fueling function.

Referring now to Figures 3(a) and 3(b), a cross-sectional and enlarged cross-sectional view of a fuel tank isolation valve in an idle condition in accordance with the present invention is shown. The compression spring (6) for OVR keeps the sealing sub-assembly (7) for OVR in contact with the sealing surface (8), and at the same time, the compression spring (3) for OPR keeps the sealing sub-assembly for OPR (4) is in contact with the sealing surface (5) so that the tank port (14) is not connected to the tank port (13) and the fuel vapor is kept inside the fuel tank. The threaded plunger (16), having an annular flange (22) at the top end, is mounted in the seal sub-assembly (7), and at the bottom end, it is fastened to a threaded cavity (22) in the rotor (20). 21) to provide inline functionality.

Referring to Figures 4(a) to 4(e), there are shown cross-sectional and enlarged cross-sectional views of a fuel tank isolation valve during refueling in accordance with the present invention. During refueling, the motor (17) is energized and the rotor (20) begins to rotate together with the shaft, which moves the threaded plunger (16) downwards, compressing the compression spring (6) to seal the seal for the OVR. The device (7) moves down and allows flow conditions from the tank mouth (14) to the tank mouth (13) as depicted in Figure 4(a).

In the first condition, through the leak point of the motor (17) + 2 revolutions, a small linear stroke of the plunger (16) occurs, and the small opening path opens and the first condition of the flow rate is achieved, as in Fig. 4(b) ) are depicted in. With further rotation of the motor (17), i.e. at the leak point of the motor + 20 rotations, additional strokes of the plunger (16) occur and the open path area increases, which achieves the second condition of the flow rate, as in Depicted in Figure 4(c). By full rotation of the motor (17), the plunger (16) performs its full stroke and there is a full opening of the valve (10) and a flow resistance condition is achieved, as depicted in Figure 4(d). The flow paths in fueling conditions are as shown in Figure 4(e).

Referring to Figures 5(a) to 5(c), there are shown cross-sectional and enlarged cross-sectional views of a fuel tank isolation valve (10) operating in OPR conditions in accordance with the present invention. When the fuel tank isolation valve (10) is in OPR condition, there is buildup inside the valve (10) in the area (18) between the spring seat (19) and the seal sub-assembly (4) for OPR function pressure, and the compression spring (3) for the OPR function keeps the seal subassembly (4) in contact with the sealing surface (5), thereby maintaining the fuel tank isolation valve (10) in a closed condition, as shown in Figure 5 ( a) as depicted. When the pressure increases beyond the predetermined protection point limit, the pressure exerts a force to compress the compression spring (3) for the OPR function and lift the seal sub-assembly (4) for the OPR function upward, as shown in Figure 5(b) depicted in. As the seal sub-assembly (4) for the OPR function is lifted upwards, the valve opens and flow begins from the tank port (14) to the tank port (13). Excessive fuel vapor enters the canister and the pressure begins to drop, as depicted in Figure 5(c). As soon as the pressure drops to the protection point limit (ie, the safety margin), the valve closes again.

Referring to Figures 6(a) to 6(c), there are shown cross-sectional and enlarged cross-sectional views of a fuel tank isolation valve (10) operating in OVR conditions in accordance with the present invention. When the fuel tank isolation valve (10) is in OVR condition, there is buildup inside the valve (10) in the area (18) between the spring seat (19) and the sealing sub-assembly (7) for the OVR function and the compression spring (6) for the OVR function keeps the seal sub-assembly (7) for the OVR function in contact with the sealing surface (8) to maintain the fuel tank isolation valve (10) in a closed condition, As depicted in Figure 6(a). There is a stroke provided between the seal sub-assembly (7) for the OVR and the plunger (16) to use the full spring force for sealing without any interference to the threads provided at the bottom end of the plunger (16) any dependencies. Also, the same stroke is used for the OVR function as it is controlled according to the flow resistance function. When the vacuum increases beyond the guard point limit, the vacuum exerts a force to compress the compression spring (6) and the seal sub-assembly for OVR function (7) moves downward due to the seal sub-assembly for OVR function The stroke between (7) and plunger (16), as depicted in Figure 6(b). Here, the plunger remains in its position and the movement of the sealing sub-assembly (6) for OVR function is equal to the stroke between the sealing sub-assembly (7) for OVR function and the plunger (16). As the seal sub-assembly (7) for the OVR moves down, the valve opens and flow begins from the tank port (13) to the tank port (14), as depicted in Figure 6(c). The vacuum begins to be released from the tank, and as soon as the vacuum reaches the guard point limit (ie, the safety margin), the valve closes again.

Thus, the FTIV assembly allows for the opening and closing of the valve by linear movement of the plunger.

Example 1

Refueling during switch-on conditions

During refueling, the stepper motor becomes on. Due to the rotation of the stepper motor, the plunger with the lead screw moves downward, thereby moving the seal assembly for the OVR function downward by compressing the compression spring for the OVR function. In the first condition, through the leak point of the motor + 2 revolutions, a small linear stroke of the plunger occurs and the small opening path becomes open, which achieves a condition of 11.4 L/min. maximum at 16 kPa. With further rotation of the motor, ie at the leak point of the motor + 20 rotations, an additional stroke of the plunger occurs and the open path area increases, which achieves a condition of maximum 155 L/min at 16 kPa. By full rotation of the motor (step 416), the plunger performs its full stroke and full opening of the valve occurs, achieving a flow resistance condition of 78 L/min at a maximum differential pressure of 0.35 kPa.

The foregoing descriptions of embodiments of the present invention have been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed, and modifications and variations are possible in light of the above teachings, or may be acquired from practice of the invention. The embodiment was chosen and described in order to explain the principles of the invention and its practical application, to enable others skilled in the art to utilize the invention in various embodiments, and with various modifications as are suited to the particular use contemplated.

Claims (6)

1. An improved fuel tank isolation valve (10) with an integrated stepper motor (17), comprising:

a valve housing (11) comprising a tank opening (13) and a tank opening (14) and comprising a compression spring (3), a seal sub-assembly (4) for performing an over-pressure relief (OPR) function, a seal sub-assembly (7) for performing an over-vacuum relief (OVR) function and a compression spring (6);

a motor housing (12) having an electrical connection port (15);

a threaded plunger (16); and

a spring seat (19);

wherein,

the stepper motor (17) comprising the motor housing (12), a threaded rotor (20) and a plurality of ball bearings (9) positioned between the motor housing (12) and the threaded rotor (20), the plurality of ball bearings (9) for reducing friction when the threaded rotor (20) is in use;

-said threaded plug (16), having an annular flange (22) at the top end, mounted in said seal subassembly (7), and at the bottom end it is fastened in a threaded cavity (21) in said threaded rotor (20) to provide an inline function; and

the valve (10) allows for opening and closing of the valve by linear movement of a threaded plunger (16).

2. The improved fuel tank isolation valve (10) with integrated stepper motor (17) as claimed in claim 1, wherein said spring seat (19) secures said compression spring (6) and said threaded plunger (16) passes through said spring seat (19).

3. The improved fuel tank isolation valve (10) with integrated stepper motor (17) as claimed in claim 1, wherein said seal sub-assembly (4) has said compression spring (3) fixed above it, said seal sub-assembly (4) being in contact with a sealing surface (5) for Over Pressure Relief (OPR) function.

4. The improved fuel tank isolation valve (10) with integrated stepper motor (17) as claimed in claim 1, wherein a seal sub-assembly (7) has said compression spring (6) fixed thereunder, said seal sub-assembly (7) being in contact with a sealing surface (8) to perform an over-vacuum relief (OVR) function.

5. The improved fuel tank isolation valve (10) with integrated stepper motor (17) as claimed in claim 1, wherein an annular cavity is provided for the ball bearing (9) between the motor housing (12) and the threaded rotor (20).

6. The improved fuel tank isolation valve (10) with integrated stepper motor (17) as set forth in claim 1, wherein said stepper motor (16) maintains pressure within a protected pressure range, provides electrical control of fuel vapor flow from tank to canister during refueling, provides Over Pressure Relief (OPR) and Over Vacuum Relief (OVR).

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