FR3078294A1 - SAFETY DEVICE FOR FUEL TANK - Google Patents

Abstract

The present invention relates to a device (10) for safety, for motor vehicle fuel tank, comprising: - A coil (63), - a member (70) movable under the effect of the magnetic field generated by the coil, forming a permitting passage for the circulation of fuel vapor when it is open, the device comprising a safety element (40) configured to activate under the effect of the fuel vapors and forming a second passage for the circulation of fuel vapor when it's open

Description

SAFETY DEVICE FOR FUEL TANK

The present invention relates to electromechanical devices comprising a coil and a movable element under the effect of the magnetic field of the coil, and more particularly an electromechanical device comprising a safety element for fuel tank used in the automotive field.

Vehicles with internal combustion engines are conventionally fitted with an activated carbon filter called a canister which absorbs and retains fuel vapors from the tank. The canister is connected to the engine intake via a purge solenoid valve which is closed when the engine is stopped and which opens so that the filter can be purged when the engine is running. The excess vapors in the tank are thus evacuated towards the engine or they are burned. The evacuation is done, however, by keeping the fuel tank under pressure.

Hybrid vehicles also include such a canister system associated with a purge solenoid valve.

One drawback of these systems in a hybrid vehicle is that the solenoid valve does not work when the hybrid vehicle is in electric mode, that is to say when the heat engine does not work. The same problem arises with vehicles with an internal combustion engine in situations where the solenoid valve is not activated. In these cases, an accumulation of fuel vapor forms in the canister. To avoid saturation of vapors in the canister, manufacturers use pressurized fuel tanks to reduce the amount of vapor that goes from the fuel tank to the canister. This accumulation of vapors increases the pressure in the tank beyond the pressure threshold tolerated by the tank or defined by the standards in force. The opposite phenomenon can also occur when the vehicle is at a temperature which does not favor the evaporation of the fuel, or when it remains inactive for a certain period.

It is thus necessary to provide a device making it possible to avoid this increase or decrease in pressure in the fuel tank.

The object of the present invention is therefore to alleviate one or more of the drawbacks of the devices of the prior art by proposing an electromechanical device comprising a safety device for a fuel tank, thus allowing the overpressure or depression of the tank beyond the tolerance thresholds or defined.

For this, the present invention provides a safety device for a fuel tank of a motor vehicle, comprising:

A coil, a movable element under the effect of the magnetic field generated by the coil, comprising a safety element configured to activate under the effect of fuel vapors

The advantage of the device is that it avoids keeping the tank under overpressure. The overpressure makes it possible to limit the passage of vapor towards the canister, and thus to avoid saturation of the canister.

According to one embodiment of the invention, the safety device, for a fuel tank of a motor vehicle, comprises:

A coil, a movable element under the effect of the magnetic field generated by the coil, forming a first passage for the circulation of fuel vapor when it is open, and a safety element configured to activate under the effect of fuel vapors and forming a second passage for fuel vapor circulation when open.

According to one embodiment of the invention, the security element is formed by a valve.

According to one embodiment of the invention, the valve is an on / off type valve.

According to one embodiment of the invention, the valve is arranged along the axis X of the device, offset relative to the axis X, so that the vapors arriving through the inlet conduit circulate around the movable element when it is in the closed position and arrives at the valve.

According to one embodiment of the invention, the valve comprises a spring configured to compress under the effect of the pressure exerted by the fuel vapors.

According to one embodiment of the invention, the valve is arranged on a second fuel vapor circulation conduit so that when the first conduit is closed by the electromagnetic system, the vapors can circulate and be controlled by the valve .

According to one embodiment of the invention, the valve includes an additional safety element.

According to one embodiment of the invention, this additional security element is a spring.

The invention also relates to an engine assembly comprising:

a fuel tank connected by a fuel vapor circulation conduit with a canister and opening into a motor a safety device according to the invention disposed on this vapor circulation conduit at the outlet of the fuel tank.

The invention also relates to the use of the device according to the invention in a hybrid vehicle.

Other objects, characteristics and advantages of the invention will be better understood and will appear more clearly on reading the description made below, with reference to the appended figures, given by way of example and in which:

FIG. 1 is a schematic representation of an engine architecture in which the device according to the invention is integrated,

FIG. 2 is a schematic representation of a longitudinal section of a device according to the invention, 2a) open solenoid valve, 2b) closed solenoid valve,

FIG. 3 is a cross section of the device according to the invention,

- Figure 4 is a schematic representation of a longitudinal section of another embodiment of a device according to the invention.

The safety device 10 for a fuel tank according to the invention is integrated into an architecture or assembly 100 of the engine illustrated in FIG. 1.

The engine assembly 100 comprises a fuel tank 1 connected by a conduit 11 for circulation of the fuel vapors with the canister 2. The conduit for the circulation of the fuel vapors opens into the engine 4 with the intake conduit 12. The safety device 10 according to the invention is disposed on this conduit 11 for the circulation of vapors at the outlet of the fuel tank 1. The canister 2 is thus arranged downstream of the safety device 10. A canister purge valve 3 is disposed on the duct 11 for circulating the vapors at the outlet of the canister 2. The engine is supplied with air via the fresh air inlet duct 5, and the exhaust gases are evacuated via the exhaust duct 6.

Thus, the vapors authorized, via the safety device, to pass through the safety device 10, arrive in the canister 2. Then, depending on the operating conditions of the engine, these vapors are recycled by the canister purge valve 3 to the inlet. motor 4.

The safety device 10 according to the invention illustrated in FIGS. 2 and 3, is composed of a purge solenoid valve comprising a safety element 40.

The objective of this safety device is to prevent the fuel tank pressure from being greater than 350 mbar, or even 400 mbar, and less than 200 mbar, even 150 mbar.

The device 10 comprises a conduit 20 for the entry of fuel vapors connected to the conduit 11 for circulation of the vapors arriving from the fuel tank 1, and an outlet conduit 30 connected to the conduit 11 for circulation of the vapors circulating towards the canister 2.

The device 10 includes a connector 50 for its electrical connection.

The materials of the device 10 are chosen to resist hydrocarbon vapors, in particular petrol.

The body 61 of the device 10 internally houses an electromagnetic system 60. The latter comprises a fixed core 62, tubular with axis X, made of a soft ferromagnetic material such as for example iron or ferromagnetic steel.

The electromagnetic system 60 comprises a coil 63 which extends around the fixed core 10 to generate within it a magnetic field when it is electrically powered. The coil 63 is for example made of insulated copper wire, in particular enameled.

The device also includes an element movable along the X axis under the effect of the magnetic field generated by the coil 63, this movable element being in the form of a plunger core 70, made of a ferromagnetic material, axially movable along the X axis inside the fixed core 62.

The plunger core 70 is inside the fixed core, in the example considered, and the flow, which is preferably gaseous (fuel vapors in this case), takes place in contact with it when it is open.

Preferably, the plunger core 70 is made of a soft magnetic material, which loses its magnetization when the magnetic field of the coil ceases, as does the fixed core 62.

The plunger core 70 has a tubular part 71 and a head 72 formed by an annular return towards the inside. The head 72 is crossed in its center by an orifice for mounting a valve seal 80. The latter has an annular groove in which the return 72 engages and comes to bear against a valve seat, not visible, when the solenoid valve is at rest, to close the outlet duct 30.

A return spring 80 ensures the return of the plunger core 70 to its rest position, closing the outlet conduit, in the absence of electrical supply to the solenoid valve.

According to one embodiment of the invention, the fixed core 62 has a thinned zone 622 which makes it possible to concentrate the magnetic induction therein to the point of almost saturating the magnetic material which constitutes this fixed core.

The system 60 is, in the example considered, closed at rest in FIG. 2b, and opens in FIG. 2a when electrically supplied, for example at a DC voltage between and 15V.

The safety element 40 of the safety device 10 is formed by a valve 40.

According to one embodiment of the invention, the valve is an on / off type valve.

The valve is arranged along the X axis of the device 10, offset relative to the X axis, illustrated in Figure 3

As illustrated in FIG. 3, the valve is arranged so that the vapors arriving through the inlet duct 20 circulate around the plunger core 70 when it is in the closed position and arrives at the level of the valve 40.

More specifically, the inlet conduit 20 is extended so as to form a wall 31 under the end 41 of the valve, oriented in the direction opposite to the circulation of the vapors towards the outlet. The end 41 of the valve, when the valve is in the closed position, thus take support on the wall 31. The valve has a spring 42 which under the effect of the pressure exerted by the vapors arriving through the inlet pipe 20 compresses. The end 41 moves and is therefore no longer in contact with the wall 31. The vapors can then circulate around the valve 40.

The valve 40 is thus disposed on a second conduit 21 for circulation of the fuel vapors so that when the first conduit is closed by the electromagnetic system, the vapors can circulate and be controlled by the valve 40.

According to one embodiment of the invention, the valve 40 is controlled by the engine control unit.

The vapor outlet conduit 30 has an opening 43 which opens into the housing 45 in which the valve is arranged. Thus, when the valve 40 is in the open position, the circulating vapors are evacuated through the opening 43 of the conduit in the outlet conduit 30.

According to an embodiment of the invention, illustrated in FIG. 4, the valve 40 includes an additional safety element 44. This additional safety element is a spring 44. This spring acts in the same direction as the first spring 42 of the valve, and accentuates its effect.

The operation of the device according to the invention is as follows.

When a user fills the fuel tank, the vehicle's thermal and electric motors are switched off. The safety device is in the closed position. Filling the tank causes fuel vapors to form. The tank pressure increases. When the pressure value in the tank increases and exceeds 400 mbar, the safety valve opens and releases vapors until the pressure drops to 400 mbar.

According to one embodiment of the invention, the valve opens when the pressure exceeds 350 mbar.

This operating mode can be carried out under other operating conditions of the vehicle than filling the tank.

Another mode of operation of the device is possible when certain conditions are met. For example if the ambient temperature is low or if the vehicle is not moving. The pressure in the tank drops, the tank is then under vacuum. In this case, the valve remains closed, so that the pressure rises enough so that the tank is again overpressure. The valve remains closed when the pressure is less than 200 mbar, and according to one embodiment of the invention, less than 150 mbar.

The scope of the present invention is not limited to the details given above and allows embodiments in many other specific forms without departing from the scope of the invention. Consequently, the present embodiments should be considered by way of illustration, and can be modified without however departing from the scope defined by the claims supported by the description.

Claims (10)

1. Safety device (10) for a motor vehicle fuel tank, comprising: A coil (63), an element (70) movable under the effect of the magnetic field generated by the coil, characterized in that it comprises a safety element (40) configured to activate under the effect of the vapors fuel. 2. Device according to claim 1, wherein the safety element 40 is formed by a valve (40). 3. Device according to claim 1 or 2, wherein the valve is an on / off type valve. 4. Device according to one of claims 1 to 3, wherein the valve is arranged along the axis X of the device (10), offset relative to the axis X, so that the vapors arriving through the conduit (20 ) inlet flow around the movable member (70) when it is in the closed position and arrives at the valve (40). 5. Device according to one of claims 1 to 4, wherein the valve comprises a spring (42) configured to compress under the effect of the pressure exerted by the fuel vapors. 6. Device according to any one of claims 1 to 5, wherein the valve (40) is disposed on a second conduit for the circulation of fuel vapors so that when the first conduit is closed by the electromagnetic system, the vapors can circulate and be controlled by the valve (40). 7. Device according to any one of claims 1 to 6, wherein the valve (40) comprises an additional safety element (44). 8. Device according to any one of claims 1 to 7, in which this additional safety element is a spring (44). 9. Motor assembly (100) comprising: a fuel tank (1) connected by a fuel vapor circulation duct (11) with a canister (2) and opening into a motor (4) a safety device (10) disposed on this duct (11) circulation of vapors at the outlet of the fuel tank (1). 5 10. Use of the device (10) according to one of claims 1 to 8 in a hybrid vehicle.