Patent Description:
There are known pressure relief valves for numerous application and systems. One of the commonly used applications for pressure relief valves is a fuel tank in which typically high pressure is accumulated. The recently developed hybrid vehicles in which fuel tank cooperates together with an electric motor, the fuel vapor system is selectively shut down, thus requiring a pressure relief valve which can independently operate.

Related prior art is shown e.g. by <CIT> that discloses a pressure release valve having a first tubing connectable fuel tank of a vehicle and a second tubing. The vehicle comprises a vehicle a vehicle computer wherein the vehicle computer directly controlling the pulsed operations of the pressure release valve. <CIT> also discloses pressure release valve to ventilate a fuel tank of a vehicle.

According to an aspect of the presently disclosed subject matter there is provided a pressure relief valve having a first tubing connectable to a fuel tank of a vehicle, the vehicle including a vehicle computer and a second tubing connectable to a fuel vapor treating device. The pressure relief valve comprises a controller, configured for receiving an actuation signal from the vehicle computer, wherein the controller includes a circuit board which forms a pulsed signal as required and an externally actuated (hereinafter EA) valve disposed between the first tubing and the second tubing and being configured for pulsed actuation by a controller thereby allowing pulsed fluid flow through a primary port disposed between the first tubing and the second tubing.

The EA valve can include a housing defining a first tubing and a second tubing and wherein the EA valve is configured to selectively open and close a primary port extending between the first tubing and second tubing. The pulsed actuation can be carried out by a controller.

The EA valve can be configured to be actuated by an external energy source. The EA valve can be an electromechanical valve. The EA valve can be a solenoid having an armature selectively extending in and out of a solenoid body and a plunger mounted on the armature and being configured to sealingly engage the primary port.

The EA valve can be perpendicularly disposed with respect to said first tubing such that pressure from the tank urges said plunger towards said primary port.

The controller can be configured to receive electrical power from an energy-storage device. The controller is configured to form a pulsed signal such which allows pulsed actuation of the EA valve.

The EA valve can be configured to be normally close, and to open only in response to an actuation by the controller.

The pulsed fluid flow can be configured to prevent a lift force of a sudden high velocity vapor flow thereby precluding corcking of fuel vapor valves coupled to then tank.

The pulsed actuation can include a signal configured with pulses having a wave length and amplitude which allows measured release of pressure from the tank.

The pulses can be configured to open the primary port for a short period of time such that only a predetermined amount of pressure can be released therefrom during each pulse. The pulses can be configured to open said primary port for <NUM> milliseconds at most. The pulses can configured to repeatedly open said primary port at least two times with a gap of at least <NUM> milliseconds between the each opening.

The controller can be configured to actuate the EA valve on occasions when the fuel tank can be about to be opened. The controller can be configured to actuate the EA valve in response to opening of a fuel door.

The pressure relief valve can further include an overpressure valve (hereinafter OP valve).

The OP valve can be configured to selectively open and close an overpressure port disposed between the first tubing and second tubing. The OP valve can be configured to allow fluid flow through the overpressure port in response to a pressure level in the tank rising above a predetermined pressure level. The valve can include a biased shaft being having a shaft head configured to sealingly engage a periphery of the overpressure port. The OP valve can further include a bleeding valve configured for allowing fluid flow between the first tubing and the second tubing when pressure at the tank drops below a predetermined level.

The bleeding valve can include a bleeding aperture formed in the shaft head and having a biased piston slidably mounted therein and being configured to sealingly engage the bleeding aperture. The piston can be provided with a seal configured to sealingly engage the overpressure port and having a corresponding bleeding aperture.

The shaft can be being biased by a shaft spring and the piston can be being biased by a piston spring so disposed with respect to one another such that the bleeding valve can operate independently of the OP valve.

The OP valve can be configured such that pressure in the first tubing exceeding a predetermined threshold can overcome the biasing force of the shaft spring, allowing thereby fluid flow through the overpressure port and when pressure in the second tubing exceeds a predetermined threshold the biasing force of the piston spring can be overcome, allowing thereby fluid flow through the bleeding valve.

The OP valve can be coaxially disposed with respect to the first tubing such that pressure from the first tubing exceeding a predetermined level facilitating the opening the OP valve. The OP valve can include housing defining a first fluid path being in fluid communication with the first tubing and a second fluid path being in fluid communication with the second tubing and a fluid port extending therebetween and a piston configured to biased towards a wall portion defined inside the housing thereby sealing the fluid port.

The OP valve further comprising a cap member configured to biased towards the piston thereby sealing the fluid port and to retract away from the piston when pressure at the tank drops below a predetermined level. The cap member can include a stop member configured to engage a second wall portion inside the housing thereby limiting the movement of the cap member towards the piston.

The piston can be configured to retract in response to a pressure level in the tank rising above a predetermined pressure level. The piston can be biased by a major spring and the cap member can be biased by a minor spring wherein the major spring exerts forces greater than the forces exerted by the minor spring, such that the pressure level required for opening the port by retracting the piston can be higher than that which can be required for opening the port by retracting the cap member.

According to another aspect of the presently disclosed subject matter there is provided a fuel vapor system comprising a pressure relief valve according to the respective claims.

The pressure relief valve could comprise a housing having the first tubing connectable to the first reservoir and the second tubing connectable to the second reservoir being open to the atmosphere and an externally actuated valve disposed in the housing and being configured for pulsed actuation by a controller thereby allowing pulsed fluid flow between the first reservoir and the second reservoir.

According to a further aspect of the presently disclosed subject matter there is provided a method for evacuating fuel vapor from a fuel tank to a fuel vapor treating device. The method comprises providing an externally actuated valve having a controller, an inlet port and an outlet port. Coupling a first tubing between the inlet port of the externally actuated valve and the fuel tank of a vehicle, the vehicle including a vehicle computer, the controller being configured for receiving an actuation signal from the vehicle computer and coupling a second tubing between the outlet port of the externally actuated valve and the fuel vapor treating device. The controller including a circuit board which forms a pulsed signal as required generating the pulsed signal configured for pulsed actuation of the externally actuated valve thereby allowing pulsed fluid flow between the fuel tank and the fuel vapor treating device.

According to yet another aspect of the presently disclosed subject matter there is provided a pressure relief valve for controlling fluid flow between a first fluid path and a second fluid path. The pressure relief valve comprising a piston defining a fluid port therein extending between the first fluid path and the second fluid path and having a first biasing member configured to urge said piston towards a wall portion. The pressure relief valve further can include a cap member having a sealing surface configured to seal said fluid port, said sealing member having a second biasing member configured to urge said sealing surface towards said port, and further having a stop member configured to limit the movement of said sealing member towards said piston.

According to yet another aspect of the presently disclosed subject matter there is provided an over pressure valve for controlling fluid flow between a first fluid path and a second fluid path. The pressure relief valve includes a piston defining a fluid port therein extending between the first fluid path and the second fluid path and having a first biasing member configured to urge the piston towards a wall portion; and a cap member having a sealing surface configured to seal the fluid port, the sealing member having a second biasing member configured to urge the sealing surface towards the port, and further having a stop member configured to limit the movement of the sealing member towards the piston. When pressure at the second fluid path exceeds a predetermined threshold the piston is pushed against the forces of the first biasing member, and the sealing member is urged towards the port of the piston until the stop member limits the movement thereof whereby the sealing surface disengages the port allowing fluid flow between the second fluid path and the first fluid path; and wherein when pressure at the second fluid path drops below a predetermined threshold the sealing member is urged against the forces of the second biasing member while the port is urged towards the wall portion whereby the sealing surface disengages the port allowing fluid flow between the first fluid path and the second fluid path.

In order to better understand the subject matter that is disclosed herein and to exemplify how it may be carried out in practice, embodiments will now be described, by way of non-limiting examples only, with reference to the accompanying drawings, in which:.

<FIG> and <FIG> show a pressure relief valve <NUM> comprising a housing <NUM> having a first tubing 14a connectable to a first reservoir (not shown), for example a fuel tank (as shown in <FIG>), and a second tubing 14b connectable to a second reservoir, for example a fuel vapor treating device (as shown in <FIG>). The housing <NUM> further includes an externally actuated valve (herein after EA valve) <NUM> disposed therein and being configured to selectively open and close a primary port 18a extending between the first and second tubing 14a and 14b. The EA valve <NUM> is configured for pulsed actuation by a controller <NUM> and it thus allows pulsed fluid flow through primary port 18a. The housing <NUM> further includes an over pressure valve (herein after OP valve) <NUM> being configured to selectively open and close an overpressure port 18b extending between the first and second tubing 14a and 14b. The OP valve <NUM> can be configured to allow fluid flow through the overpressure port 18b in response to a predetermined pressure gradient between the first tubing 14a and the second tubing 14b.

The EA valve <NUM> can be any valve which is actuated by an external energy source, as opposed to being actuated by the pressure gradient across the housing <NUM>, e.g. pressure difference between the first tubing 14a and the second tubing 14b. According to an example of the presently disclosed subject matter the EA valve is an electromechanical valve, here illustrated as solenoid, otherwise the EA valve can be pneumatically actuated, or actuated by any other external source of energy.

In the present example, the EA valve <NUM> includes solenoid body <NUM> having an armature <NUM> selectively extending in or out of the solenoid body. The armature <NUM> can be biased by a solenoid spring <NUM> which is disposed such that the armature normally extends out of the solenoid body <NUM>. The EA valve <NUM> further includes a plunger <NUM> having a plunger head <NUM> and a seal <NUM> configured to sealingly engage the primary port 18a. The plunger <NUM> is mounted on the armature <NUM> such that when the latter extends out of the solenoid body <NUM> the plunger head <NUM> engages the primary port 18a preventing fluid flow therethrough.

According to an example, the solenoid spring <NUM> bears on one side thereof against a shoulder portion defined on the plunger <NUM>, and on the other side thereof bears against the solenoid body <NUM>.

The solenoid body <NUM> further includes a coil <NUM> wrapped thereabout and configured to energize the armature <NUM> causing it to withdraw into the solenoid body <NUM> by overcoming the biasing force of spring <NUM>.

According to an example, the EA valve <NUM> is activated by a controller <NUM> which is adapted to receive electrical power from a vehicle alternator or from any other energy-storage device (not shown). The controller <NUM> is configured to form a pulsed signal such which allows pulsed actuation of the solenoid as explained in detail hereinafter. The controller <NUM> is configured to receive an actuation signal from the vehicle computer and includes a circuit board which forms a pulsed signal as required. The EA valve <NUM> can be configured to be normally close, and can be opened only in response to an actuation by the controller <NUM>, for example, an electrical signal.

The EA valve <NUM> can be perpendicularly disposed with respect to the first tubing 14a. This way, in case the first tubing 14a is coupled to a fuel vapor outlet of a fuel tank, fluid flow from the tank urges the plunger head <NUM> towards the primary port 18a, and the pressure inside the tank facilitate maintaining the EA valve <NUM> in the closed position.

The over pressure valve (herein after OP valve) <NUM>, as best seen in <FIG>, includes a shaft <NUM> being biased by a shaft spring <NUM> and configured with a shaft head <NUM> and a sealing protrusion <NUM> defined about the periphery thereof. The sealing protrusion <NUM> is configured to sealingly engage a corresponding groove <NUM> defined about the periphery of the overpressure port 18b. The shaft spring <NUM> is mounted over the shaft <NUM> and bears against the housing <NUM> on one end thereof and against the shaft head <NUM> on the other end thereof thereby urging the latter to sealingly engage the overpressure port 18b.

The OP valve <NUM> further includes a bleeding valve <NUM> comprising piston <NUM> slidablely mounted inside the shaft <NUM> and through a bleeding aperture <NUM> formed in the shaft head <NUM>. The piston <NUM> can include a piston head <NUM> defined at one end thereof configured to slidablely engage the bleeding aperture <NUM>. The other end thereof is coupled to bearing member <NUM> having a diameter smaller than that of the shaft spring <NUM>. A seal <NUM> having a corresponding bleeding aperture 55a is mounted between the shaft head <NUM> and the piston head <NUM> and being configured to sealingly engage the overpressure port 18b. The periphery of the seal <NUM> is disposed between the shaft head <NUM> and the wall of the overpressure port 18b.

The piston <NUM> is biased by a piston spring <NUM> bearing against the bearing member <NUM> on one side thereof and against the shaft head <NUM> on the other end thereof. The piston spring <NUM> is configured with a diameter smaller than that of the shaft spring <NUM>. Accordingly, the piston <NUM>, the piston spring <NUM> and the bearing member <NUM> are disposed inside the periphery of the shaft spring such that the bleeding valve <NUM> can operate independently of the shaft <NUM>.

The OP valve <NUM> is configured such that pressure in the first tubing 14a exceeding a predetermined threshold can overcome the biasing force of the shaft spring <NUM>, whereby the sealing protrusion <NUM> of the shaft head <NUM> slides away from the corresponding groove <NUM> allowing fluid flow through the overpressure port 18b. When pressure in the second tubing 14a exceeds a predetermined threshold the biasing force of the piston spring <NUM> is overcome, whereby the piston <NUM> is moved towards the port 18b.

According to an example the OP valve is coaxially disposed with respect to the first tubing 14a, hence, pressure or fluid flow from the first tubing is applied directly on the shaft head <NUM> facilitating the opening thereof in case the pressure at the first tubing 14a exceeds a certain threshold.

Thus, in case the first tubing 14a is coupled to a fuel vapor outlet of a fuel tank, when pressure in the tank exceed a predetermined level, the shaft head <NUM> of the OP valve <NUM> is opened allowing thereby fluid flow from the first tubing towards the second tubing 14b, even in case the EA valve <NUM> is closed.

Reference is now made to <FIG>, the pressure relief valve can be integrated in a vehicle fuel vapor system generally designated <NUM> and having a fuel tank <NUM> and a vapor treating device <NUM>, such as a canister. The fuel tank <NUM> is coupled to a filler neck <NUM> and includes a fuel vapor outlet tube <NUM>, which is coupled to a first tubing of the pressure relief valve <NUM>. A second tubing extending from the pressure relief valve <NUM> is coupled to the vapor treating device <NUM>, which can be open to the atmosphere.

The following is a detailed explanation of the operation of the pressure relief valve as described in <FIG>, however in the case where the valve is integrated in a fuel vapor system and mounted in a fuel vapor path between a fuel tank and a vapor treating device, hereinafter referred to as a canister.

The pressure relief valve <NUM> allows opening the EA valve <NUM> in response to a signal for example, an electric signal form the vehicle computer, and the OP valve <NUM> can be open in response to a pressure gradient across the valve larger than a predetermined gradient. That is to say, in the case where the first tubing 14a is coupled to a fuel tank (as shown in <FIG>) and the second tubing 14b is coupled to a canister, when the pressure at the tank exceed a predetermined level the OP valve <NUM> can be opened so as to bring the pressure level in the tank to the desired pressure range. Similarly, when the pressure at the tank drops below a predetermined level the bleeding valve <NUM> can be opened so as to bring the pressure level in the tank to the desired pressure range.

<FIG> shows the pressure relief valve <NUM> in a fully closed position in which both the EA valve <NUM> and the OP valve <NUM> are closed. In this position, the plunger head <NUM> of the EA valve <NUM> sealingly engages the primary port 18a and the shaft head <NUM> of the OP valve sealingly engage the overpressure port 18b. Thus, in this position, fuel vapor flow from the first tubing 14a to the second tubing 14b, and hence form the tank to the canister is precluded. It is appreciated that is this position the plunger <NUM> operates under the force of the spring <NUM> urging the seal <NUM> on the primary port 18a. Thus, in this position there is no need for energy from an external source to energize the EA valve <NUM>.

<FIG> shows the pressure relief valve <NUM> in the open position thereof, in which the EA valve <NUM> is opened while the OP valve <NUM> remains closed. In this position, the plunger head <NUM> of the EA valve <NUM> disengages the primary port 18a thereby allowing vapor flow from the tank towards the canister. Opening the EA valve <NUM> is carried out in response to a pulsed signal from the controller <NUM> which in the case of a solenoid energizes the coil <NUM> wrapped about the solenoid body <NUM> thereby causing a pulsed displacement of the armature <NUM> away from the primary port 18a. At the end of each pulse the spring <NUM> forces the armature <NUM> and the plunger <NUM> to engage back the primary port 18a. Thus, as a result of the pulsed signal from the controller <NUM> a pulsed fluid flow is formed between the first tubing 14a and the second tubing 14b. Hence, vapor flow from the tank to the canister is allowed in a pulsed fashion, such that does not cause corcking of other fuel vapor valves coupled to the tank such which can be be clogged by the lift force of the sudden high velocity vapor flow.

Accordingly, the pulsed signal can be configured with pulses having a wave length and amplitude which allows measured release of pressure, such which will not result in malfunction of other fuel vapor accessory. According to an example, each pulse can be at most <NUM> milliseconds long and can be repeated for <NUM> or <NUM> times or more with a gap of at least <NUM> milliseconds between the pulses.

It is appreciated that the signal can be actuated on occasions when the fuel tank is about to be opened, for instance before refueling thereof, where it is desired to release pressure from the fuel tank, and to bring it to substantially equilibrium with the atmosphere. Accordingly, the pulses can be configured in accordance with the expected time since it is acknowledged that the vehicle's tank is about be refueled until the opening of fuel tank actual occurs. That is to say, if for example opening the fuel door is utilized as a trigger following which it is expected that the fuel tank is to be opened, the time interval during which the pressure in the tank is to be releases is the expected time between the opening of the fuel door and the actual opening of the fuel tank. According to some examples the expected time interval is <NUM> seconds, thus the pulsed signal is configured to allow substantially releasing the pressure from the tank within <NUM> seconds.

According to the latter example, opening the fuel door can automatically actuate a signal to actuate the controller <NUM> which in return forms a pulsed signal to dictate the operation of the solenoid valve <NUM>. It is appreciated that other triggers can be utilized, such which the actuation of the pulsed signal is carried out within a predetermined time interval prior to opening of the fuel tank.

It is further appreciated that once the pressure in the fuel tank is released following the pulsed opening of the EA valve <NUM>, the valve can be continuously opened without pulses, for example to allow refueling of the tank. It is thus appreciated that the amount of electric power required when forming the pulses can be higher than the amount of energy required to maintain the EA valve <NUM> in the continuous open position thereof. This is due to the fact that opening the EA valve <NUM> when the fuel tank is under high pressure requires more energy than when maintaining the EA valve open once the pressure is released from the tank. Accordingly, the pulsed signal actuated by the controller <NUM> can include pulses having high voltage amplitude, while the last pulse following which the EA valve <NUM> remains opened the voltage amplitude can be lower. This way, overheating of the EA valve <NUM> is precluded.

Referring now to <FIG> the pressure relief valve <NUM> can be opened in response to a high pressure in the first tubing side 14a, such as when pressure in the fuel tank exceeds a predetermined level. At this position, the forces applied by the pressure within the tank overcome the forces of the shaft spring <NUM> biasing the shaft <NUM> of the OP valve <NUM>, this results in the disengagement of the sealing protrusion <NUM> of the shaft head <NUM> from the groove <NUM> defined about the periphery of the overpressure port 18b thus the pressure from within the tank can be released by allowing vapor flow thereform to pass through the overpressure port towards the canister.

It is appreciated that the operation of the OP valve <NUM> can be configured as an emergency valve preventing overpressure in the tank such which can cause damage to the tank. Thus under normal condition the OP valve <NUM> remains closed.

As for the EA valve <NUM>, in this position the latter remains closed under the forces of the spring <NUM> urging the seal <NUM> on the primary port 18a. Thus, as in the fully closed position there is no need for energy from an external source to energize the EA valve <NUM>, and the OP valve <NUM> can operate independently solely in response to the pressure in the tank.

Referring now to <FIG> the pressure relief valve <NUM> can be opened in response to a low pressure in the first tubing side 14a, such as when pressure in the fuel tank drops below a predetermined level, for example when vacuum is formed in the tank. At this position the forces applied by the pressure within the tank overcome the forces of the piston spring <NUM> biasing the piston <NUM> of the bleeding valve <NUM> away from the overpressure port 18b. As a result, the piston head <NUM> is inwardly urged disengaging the shaft head <NUM>, allowing thereby fluid flow through the bleeding aperture <NUM> formed therein. Since the periphery of the seal <NUM> is disposed between the shaft head <NUM> and the wall of the overpressure port 18b, when the piston head <NUM> is moved away from the shaft head <NUM>, the periphery of the seal remains in place while the center thereof is inwardly deformed. In this position fluid flow through the bleeding apertures <NUM> an the corresponding bleeding valve 55a is facilitated, thus allowing vacuum from within the tank to be released.

Claim 1:
A pressure relief valve (<NUM>) having:
a first tubing (14a) connectable to a fuel tank (<NUM>) of a vehicle, the vehicle including a vehicle computer;
a second tubing (14b) connectable to a fuel vapor treating device (<NUM>)
a controller (<NUM>), configured for receiving an actuation signal from the vehicle computer, wherein the controller (<NUM>) includes a circuit board which forms a pulsed signal as required;
an externally actuated, EA, valve (<NUM>) disposed between the first tubing (14a) and the second tubing (14b) and being configured for pulsed actuation by said controller (<NUM>), thereby allowing pulsed fluid flow through a primary port disposed between said first tubing (14a) and said second tubing (14b).