JP2002122046A - Fuel evaporation recovering apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel evaporation recovering apparatus, substantially improving fuel evaporation recovering efficiency, reducing weight of the device, and preventing discharge of fuel evaporation into the atmosphere, without affecting components of emission gas or driving characteristics of an automobile or the like. SOLUTION: This fuel evaporation recovering device is provided with a canister 2, a membrane-separating module 6, a compressor 5, a negative pressure control valve 7, and a cooling module 9. The membrane separating module 6 separates the fuel evaporation V from an exhaust port 22 into an air-rich component A and a fuel-evaporation rich component V. An impermeable side exhaust port 64 is connected to an intake pipe 4 and driving force by the compressor 5 acts from an external space 65 to an internal space 66. The fuel- evaporation rich component V is discharged from an exhaust port 63 and the air-rich component A is discharged from the impermeable side exhaust port 64. The exhaust port 63 is connected to the cooling module 9, and the fuel evaporation is liquidized and recovered by a fuel tank 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel vapor recovery device for recovering and returning fuel vapor from a fuel tank to a fuel tank.

[0002]

2. Description of the Related Art Conventionally, fuel vapor generated from a fuel tank of a vehicle or the like is prevented from escaping into the atmosphere as shown in FIG.
The fuel vapor recovery device shown in FIG. In this fuel vapor recovery device, for example, fuel vapor (vapor) generated as the temperature of the fuel F inside the fuel tank 1 rises
Is temporarily absorbed and stored in the activated carbon of the canister 2 through the ventilation path 11 and the fuel vapor inflow port 21, and the suction load of the intake pipe 4 of the engine is set so that the storage amount does not exceed the adsorption capacity of the canister 2. The pressure is introduced into the intake pipe 4 through the ventilation path 12 through the control valve 3 using the pressure. The desorption of the fuel vapor from the canister 2 will be described in more detail. The fuel vapor adsorbed and stored in the activated carbon in the canister 2 enters the canister 2 from the gas introduction port 23 connected to the bottom of the canister 2. The air is purged through the fuel vapor discharge port 22 by the introduced air, and the amount of air introduced into the intake pipe 4 is controlled by the purge control valve 3 to be burned in the combustion chamber of the engine.

However, in such a fuel vapor recovery apparatus, the amount of air introduced from the ventilation path 12 to the intake pipe 4 is controlled, but this controls the mixture of fuel vapor and air that is not accurately measured. If this mixture is added to the accurately measured fuel component from the fuel injection valve on the upstream side of the intake pipe 4, it becomes difficult to perform combustion at the set air-fuel ratio, and the operating characteristics of the engine are reduced. This causes problems such as a decrease in exhaust gas and adverse effects on components of exhaust gas. Further, as fuel consumption is required to be reduced in response to recent environmental problems and resource saving, ultra-lean by direct injection of fuel into the combustion chamber from conventional lean-mixture combustion (around 20). When trying to perform a mixture ratio combustion (a mixture ratio of about 40 to 50),
The above-mentioned problem occurs more remarkably.

In order to solve such a problem, a canister, a membrane separation module, and a condensing means are provided, and the fuel vapor concentrated by the membrane separation module is liquefied by the condensing means and returned to the fuel tank. Fuel vapor recovery device (JP-A-10-274106 and JP-A-10-274106)
1-93784). In order to operate the membrane separation module, the presence of a pressure difference between the supply side and the permeation side is a necessary condition.In these known techniques, a pressure difference is generated by reducing the pressure of the gas on the permeation side by a vacuum pump. This is the driving force for membrane separation.

[0005]

However, in the membrane separation method using a vacuum pump with reduced pressure, the amount of gas to be processed per unit membrane area is reduced, so that there is a problem that the membrane module becomes large and the pressure reduction system is increased. Since the pipe has a larger gas volume than the pressurized pipe, the pipe diameter is inevitably increased, and there is a problem that it is not preferable from the viewpoint of the pipe layout and the weight reduction. In particular, considering the on-board use of an automobile, the problem of increased weight and layout may be a major obstacle to adoption.

The present invention has been made in view of the above-mentioned problems of the prior art, and has as its object to realize a significant improvement in fuel vapor recovery efficiency and a reduction in the weight of an apparatus, and It is an object of the present invention to provide a fuel vapor recovery device which does not affect the operation characteristics such as the above and the components of exhaust gas and does not release fuel vapor into the atmosphere.

[0007]

Means for Solving the Problems As a result of intensive studies to achieve the above object, the present inventor pressurized air containing fuel vapor generated by purging from a fuel tank or a canister using a compressor. The present inventors have found that the above-mentioned problems can be solved by using a pressure-based separation membrane system which feeds the solution into a membrane separation module, and have completed the present invention.

That is, the fuel vapor recovery device of the present invention is a fuel vapor recovery device provided in a direct injection engine system that performs ultra-lean combustion or stratified combustion, and includes an inlet port for introducing fuel vapor from a fuel tank, and an inlet port. Adsorption means for adsorbing the fuel vapor, and a gas introduction port for introducing a gas for purging the fuel vapor adsorbed by the adsorption means,
A canister having a discharge port for discharging the purged fuel vapor, and a fuel vapor flowing from the discharge port of the canister is separated into a fuel vapor rich component and an air rich component by a fuel vapor selectively permeable separation membrane. A membrane separation module for discharging components from an air-rich component discharge port and a fuel vapor rich component discharge port, introducing the gas for purging the fuel vapor, and supplying the purged fuel vapor to the membrane separation module. A compressor that generates a driving force for introduction, fuel vapor supply and membrane separation, and a fuel vapor rich component discharge port of the membrane separation module is disposed on the permeate side of the separation membrane and connected to the fuel tank, The fuel vapor component contained in the fuel vapor rich component is liquefied or absorbed by a liquid fuel in the fuel tank and collected, The air-rich component discharge port of the membrane separation module is disposed on the non-permeable side of the separation membrane and connected to an intake pipe of an engine, and the air-rich component is removed by a negative pressure generated by the engine. It is characterized by.

In a preferred embodiment of the fuel vapor recovery apparatus according to the present invention, the pressure of the compressor when supplying gas to the membrane separation module is 0.01 MPa in gauge pressure.
０．１0.18 MPa.

Further, a preferred embodiment of the fuel vapor recovery device of the present invention is opened only when the pressure becomes lower than a predetermined negative pressure between the air rich component discharge port of the membrane separation module and the intake pipe of the engine. And a control valve.

Still another preferred embodiment of the fuel vapor recovery apparatus of the present invention is that the ratio of the permeate-side flow rate to the non-permeate-side flow rate of the separation membrane is adjusted according to the concentration of the fuel vapor supplied to the membrane separation module. The fuel vapor on the non-permeate side of the separation membrane that is changed and connected to the intake pipe of the engine is controlled to a concentration and a flow rate that do not affect stratified combustion.

Still another preferred embodiment of the fuel vapor recovery apparatus according to the present invention has two or more canisters and swings fuel vapor adsorption and fuel vapor desorption for each canister by valve control. Features.

Further, in another preferred embodiment of the fuel vapor recovery apparatus of the present invention, a fuel component discharge port connected to the permeation side of the membrane separation module is connected to a fuel tank, and the liquid fuel in the fuel tank is supplied to the fuel tank. It is characterized by absorbing components.

In another preferred embodiment of the fuel vapor recovery apparatus of the present invention, a cooling module is added between the fuel rich component discharge port of the membrane separation module and the fuel tank, thereby liquefying the fuel vapor component. Then, the fuel tank is returned to the fuel tank.

Still another preferred embodiment of the fuel vapor recovery apparatus according to the present invention uses the heat absorption energy generated when the fuel vapor is purged from the canister, wherein the condenser is built in the canister. And the fuel vapor generated by at least one of the fuel tank and the fuel system line and the fuel vapor separated and concentrated by the membrane separation module are liquefied and recovered by the condenser.

[0016]

In the fuel vapor recovery apparatus of the present invention having the above-described structure, the fuel vapor from the fuel tank is introduced into the canister and then sent to the membrane separation module using a compressor. It is separated into a fuel vapor rich component and an air rich component. Then, the fuel-rich component is liquefied by the cooling module and returned to the fuel tank as necessary, or is recovered by being absorbed by the fuel in the fuel tank. On the other hand, the air-rich component is sent from an air-rich component discharge port of the membrane separation module to an intake pipe via a valve installed as needed, and is sent into a combustion chamber of the engine. Therefore, the fuel vapor is not substantially supplied to the engine and burned, and emission to the atmosphere is also prevented.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a fuel vapor recovery device according to the present invention will be described in detail. As described above, this fuel vapor recovery device adsorbs and holds the fuel vapor from the fuel tank and purges and adsorbs the adsorbed fuel vapor with a purge gas (typically air). A membrane separation module for separating fuel vapor into an air-rich component and a fuel vapor component, and a compressor that introduces the purge gas and supplies the purged fuel vapor to the membrane separation module.

Here, a feature of the fuel vapor recovery apparatus of the present invention resides in a pressurized type separation membrane system in which separation is performed using a compressor as a driving force for membrane separation.
One of the features is that the air-rich gas which is a gas on the non-permeate side in the membrane separation module is removed by the negative pressure of the engine. In this method, air containing fuel vapor generated by purging from a fuel tank or a canister is pressurized using a compressor and sent to a membrane separation module, thereby increasing the processing speed of gas per membrane area.
This is because the inventors have found that the separation coefficient is improved. The advantages of the pressurized type system are that the gas throughput per unit membrane area and the separation coefficient of air / fuel vapor can be increased, and the piping diameter is smaller than that of vacuum piping. What you can do.
In addition, a layout advantage and a weight saving advantage can be obtained.

Further, in the present invention, the air-rich gas, which is a non-permeating gas, is removed by using the negative pressure of the engine. A control valve that opens only when the pressure drops below a certain negative pressure is installed in the gas path connecting the air-rich component exhaust port provided on the non-permeate side of the module and the engine intake pipe. Preferably, the pressure is made available for the removal of air-rich gas.

Further, in the fuel vapor recovery apparatus of the present invention, the compressor is used as described above, but what is important here is that the purge of the fuel vapor in the canister is performed by using the suction force of the compressor. The pressure applied by the compressor to the membrane separation module is preferably in the range of 0.01 MPa to 0.18 MPa in gauge pressure.
If the pressure is less than 0.01 MPa, a situation may be considered in which a sufficient membrane separation driving force cannot be obtained. On the other hand, if the pressure exceeds 0.18 MPa, it is not preferable because the size of the compressor is increased and a part of the fuel vapor may condense and adversely affect the membrane separation module.

The separation coefficient of the membrane separation module is at least 4 in air / fuel vapor separation ratio (molar ratio).
It is desirable that the separation performance is not less than 50 and preferably not less than 10, and it is possible to keep the concentration of fuel vapor on the non-permeate side low even when the concentration of fuel vapor is high,
The influence on the driving performance and exhaust performance of the engine can be suppressed.

Incidentally, assuming that the separation coefficient is 5, the flow rate on the permeate side: the flow rate on the non-permeate side = 5: 5, and the fuel vapor is supplied to the membrane separation module at a concentration of 50%, the concentration of the fuel vapor on the non-permeate side is assumed. Is reduced to 20% or less. When the separation coefficient is set to 10 under the same conditions, the concentration of the fuel vapor on the non-permeate side can be reduced to 10% or less. However, the concentration of the gas actually sent is from a low concentration of 10% or less to 100%.
%, So that the ratio of the flow rate on the permeate side and the flow rate on the non-permeate side is changed as necessary so that the concentration of the fuel vapor fed into the intake pipe of the engine is at least 20% or less.
More preferably, it is adjusted to be 10% or less.

The flow rate on the permeate side and the flow rate on the non-permeate side of the membrane separation module are determined by the concentration of the supplied fuel vapor. Specifically, using a membrane separation module using a fuel selective permeation type separation membrane, the permeate side flow rate is increased when the concentration of fuel vapor is high, and the non-permeate side flow rate is increased when the concentration is low. Control. At this time, it is preferable to control the concentration and the flow rate of the fuel vapor on the non-permeate side of the separation membrane so as not to affect the stratified combustion. In addition, such control can prevent excessive entry of fuel vapor into the engine.

Since the flow rate on the permeate side is determined to some extent by the pressure of the compressor and the permeability coefficient of the membrane separation module, the control of the flow rate on the permeate side and the flow rate on the non-permeate side depends on the gas flow rate on the non-permeate side. Alternatively, it is desirable to control the amount of gas introduced into the membrane separation module. As a method of this flow control, a flow control valve is installed at at least one position between the compressor and the membrane separation module or downstream of the non-permeate side (air rich component discharge port) of the membrane separation module. It may be performed alone or by both the flow control valve and the compressor, or may be performed by changing the pressure of the compressor and changing it. Further, the flow rate may be limited while varying the pressure supplied to the separation membrane by a pressure regulating valve.

In this fuel vapor recovery apparatus, a fuel vapor rich component discharge port provided on the permeate side of the membrane separation module is connected to the fuel tank in order to recover the fuel vapor. It is also possible to install and liquefy the fuel component here, and then return it to the fuel tank and collect it. In this case, as a cooling method, it is possible to use a refrigerant used for the air conditioner, or to send cool air of the air conditioner to the condensing module.In addition, a fuel vapor rich component is cooled and liquefied by using an electronic cooling element or the like. A method of recovery is conceivable.

On the other hand, it is also possible to connect the fuel vapor rich component discharge port directly to the fuel tank, and to absorb and collect the fuel vapor into the liquid fuel in the fuel tank by bubbling or the like. In the present invention, in particular, the gas component on the permeation side of the membrane separation module is one in which the fuel component is concentrated, so that excellent absorption efficiency can be obtained. Further, the condenser is provided in the canister, and as a cooling method of the condenser, the fuel vapor concentrated in the membrane separation module is sent and liquefied and recovered by utilizing heat absorption energy generated when purging the fuel vapor from the canister. It is also possible.

The separation membrane used in the above-mentioned membrane separation module is not particularly limited as long as it has fuel vapor permeability, but is not limited in durability, chemical stability, separation coefficient, gas per unit membrane area. Considering the throughput, it is preferable to use a membrane separation module using a polyimide-based membrane as a cross-linking organosiloxane as a separation active layer, and by using such a membrane, it is possible to increase the membrane area by forming a spiral or hollow fiber. Therefore, a compact module can be obtained. The shape of the module and the amount of gas to be processed may be determined in consideration of the layout and cost, and are not particularly limited.

Further, if the fuel vapor recovery device of the present invention is installed in a direct injection engine system, the operating characteristics of the engine due to ultra-lean combustion or stratified combustion of the direct injection engine may be degraded, and the exhaust gas components may be adversely affected. Problems can be avoided.

[0029]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in more detail with reference to the drawings, with reference to some embodiments and comparative examples.

(Embodiment 1) FIG. 2 shows an embodiment of the fuel vapor recovery apparatus of the present invention. The apparatus shown in FIG. 1 concentrates fuel vapor generated from a fuel tank installed in a vehicle or the like using gasoline or light oil as fuel or fuel vapor including air generated by a canister purge by a membrane separation module. Used in a system that absorbs and recovers fuel from the tank, the main components are a canister 2, a compressor 5, a membrane separation module 6, a negative pressure control valve 7 for controlling the engine negative pressure, and a high concentration of fuel vapor. Is provided with a cooling module 9 for liquefying.

First, the connection between these components will be described. The canister 2 is adsorbed on a container 20, an inflow port 21 connected to a path 11 for introducing the fuel vapor from the fuel tank 1 into the container 20, and activated carbon which is an example of an adsorbing means for adsorbing the inflowing fuel vapor. A gas introduction port 23 for introducing a gas for purging fuel vapor;
An exhaust port 22 for exhausting a gas containing fuel vapor purged inside is provided. The compressor 5 is installed in the middle of the path 12 connecting the discharge port and the membrane separation module. The membrane separation module 6 converts the fuel vapor V containing the air that has been compressed by the compressor 5 and flows in from the discharge port 22 of the canister via the path 12 into an air-rich component A (air containing almost no fuel vapor) and a fuel vapor-rich component. Component V (high concentration fuel vapor).

FIG. 3 is a transverse sectional view and a longitudinal sectional view showing an example of a membrane separation module used in the apparatus of the present embodiment. In the membrane separation module 6, for example, a tubular porous base material is coated with a separation membrane 67, and an O-ring 68 as a spacer is attached to the obtained tubular separation membrane 67 and accommodated in the module case 61, thereby forming an outer casing. A space 65 and an inner space 66 are formed, and the module has a substantially double-pipe structure. Further, the fuel vapor introduction port 62 is connected to the outer space 65, the permeate side gas discharge port (fuel vapor rich component discharge port) 63 is connected to the inner space 66, and the non-permeate side gas discharge port (air rich component discharge port). ) 64 is connected to the intake pipe 4 via the path 15 (see FIG. 2). Therefore,
In the membrane separation module 6, the driving force by the pressurization of the compressor acts so that the gas flows from the outer space 65 to the inner space 66.

In this embodiment, as the separation membrane 67, a hollow fiber module using a polyimide as a base and a crosslinked organosiloxane as a separation active layer is used. The crosslinked organosiloxane that has been surface-treated selectively sorbs fuel vapor from a mixture of air and fuel vapor (hydrocarbon),
It has the function of preferentially transmitting fuel vapor. Therefore, the fuel vapor rich component V is discharged from the permeate-side discharge port 63 and the air-rich component A is discharged from the non-permeate-side discharge port 64 of the membrane separation module 6.

The permeate-side discharge port 63 from which the fuel vapor rich component V is discharged is connected to the cooling module 9 via the path 16.
Is partially liquefied, and the fuel tank 1
A path 17 is provided so that the liquefied fuel L can be recovered. As such a cooling module 9, a module of a type in which a refrigerant used for an air conditioner is introduced into a module container in a serpentine shape to cause heat exchange, cooling air of an air conditioner to be sent to the cooling module, or cooling by an electronic cooling element is used. It is possible. On the other hand, air rich component A
Is connected to the intake pipe 4 of the engine, and the gas is removed to the engine intake pipe by the negative pressure generated in the intake process of the engine.

In the apparatus of this embodiment, the negative pressure control valve 7 is disposed between the non-permeate side discharge port 64 of the membrane separation module 6 and the intake pipe 4, so that the flow rate on the permeate side and the non-permeate Side flow is controlled. It should be noted that the negative pressure control valve 7 can be controlled so as to be opened only when the pressure becomes equal to or lower than a predetermined negative pressure in conjunction with the intake process of the engine.

The operation of the fuel vapor recovery system having such a configuration will be described with reference to the flowchart shown in FIG. First, an ignition (Ig) switch OFF, that is, a phenomenon in which fuel vapor is generated when the engine is in a stopped state, mainly occurs when the fuel temperature inside the fuel tank 1 increases during parking or during refueling. The fuel vapor generated in the fuel tank 1 is adsorbed by the adsorbent in the canister 2 via the inflow port 21 of the canister 2. The tank internal pressure increased by the generation of the fuel vapor flows backward through the gas introduction port 23 of the canister and is released to the atmosphere. In this case, in the illustrated flowchart, if it is determined whether the switch is ON in reading the Ig switch (step 1 (hereinafter abbreviated as “S1” or the like)) (S2), the determination is NO, and the routine of the flowchart ends.

Next, a method of starting the engine and recovering the fuel vapor adsorbed on the canister 2 will be described.
When the engine is started (ignition Ig switch ON), the result of the determination of the Ig switch is YES (S2), the compressor is started (S3), and air in the atmosphere is sent from the gas introduction port 23 to the canister 2 at a predetermined flow rate. The fuel vapor adsorbed by the adsorbent inside the canister 2 starts to be desorbed and is sucked into the compressor 5 from the gas discharge port 22 via the path 12. The sucked gas is pressurized by the compressor and sent to the gas introduction port 62 of the membrane separation module 6.

Subsequently, the concentration of the gas containing the purged fuel vapor is determined (S4). This concentration determination may be performed by arranging and sensing a fuel vapor sensor as an upstream process of the membrane separation module 6, or may be predicted and controlled based on empirical rules such as vehicle experiments. And
In step 5, the fuel vapor concentration is checked, and the ratio between the flow rate on the permeate side and the flow rate on the non-permeate side is determined according to the concentration. The flow rate can be determined by, for example, the following equation (concentration of supplied steam) = (permeate flow rate) / (supply flow rate) (the supply flow rate in the equation indicates (permeate flow rate + non-permeate flow rate)) What is necessary is just to satisfy | fill the formula represented by this. In this way, by determining the flow rate according to the concentration, it is possible to avoid sending high-concentration fuel vapor to the engine, and the permeate-side fuel vapor is efficiently concentrated to improve the liquefaction and recovery efficiency. .

When the concentration of the fuel vapor is 1% or more, the permeation flow rate of the membrane is controlled according to the supplied concentration (S6), and the cooling module 9 is also turned on (S7). Thereby, the separation is started in the membrane separation module 6, and the concentrated fuel component is sent from the permeate discharge port 64 to the cooling module 9 via the path 16 and liquefied, and then returned to the fuel tank 1 and collected. Then, the routine of the flowchart ends. At this time, the non-permeate side of the membrane separation module 6 becomes only the air component or the air component rich and is sent to the intake pipe 4 by the engine negative pressure, but does not affect the air-fuel ratio.

If the above routine is repeated, the purge of the canister may progress and the fuel vapor concentration may become less than 1%. In such a case, it is determined that the purge has been completed and the compressor 5 is turned off. In addition, when the cooling module is ON, the cooling module is turned OFF, and the collection operation is stopped (S8). The reason for stopping is to prevent unnecessary energy from being consumed when there is no need for recovery, and to prevent a decrease in fuel efficiency. Next, a time lapse determination is performed (S
9). The time from when the compressor 5 is turned off is measured, and when a certain time has elapsed, the routine of the flowchart is ended. The determination of the passage of time is made here to avoid frequent ON / OFF of the compressor and concentration check. In the present embodiment, the routine is terminated after 5 minutes have elapsed (S10). Although this time is not particularly limited, setting it too long is not preferable because a large amount of fuel vapor may be adsorbed to the canister while the recovery is stopped.

When the engine is started by the processing based on the above-described flow chart, the fuel vapor stored in the canister is gradually purged by repeating these cycles, so that the fuel can be supplied or the vehicle can be parked for a long time. Can be dealt with appropriately. Further, in the present embodiment, since the concentration is checked every 5 minutes at the longest, the recovery can be started immediately even if the generation amount of the fuel vapor varies due to the operating condition or environmental change.
In addition, the membrane area of the membrane separation module and the capacity of the compressor are as follows: canister capacity, vehicle size, vehicle usage environment,
There is no particular limitation as long as it can be appropriately selected according to the displacement of the engine and the like.

Comparative Example 1 As a comparative example, a case where a vacuum pump is used as a driving force for membrane separation will be described. FIG. 5 is a cross-sectional view of a fuel vapor recovery device using a vacuum pump. The overall configuration is almost the same as that of the first embodiment, except that the vacuum pump 5A is arranged in the middle of the path 16 instead of the compressor 5 arranged in the middle of the path 12. As the separation driving force, the suction force of the vacuum pump 5A attached downstream of the permeation side of the membrane separation module is used. The canister purge utilizes suction by the negative pressure of the engine. As in the case of Example 1, a hollow fiber module having a polyimide-based crosslinked organosiloxane as a separation active layer was used as a separation membrane.

FIG. 6 shows the gas transmission rates of the pressurized type (Example 1) and the vacuum type (Comparative Example 1). A module having a membrane area of about 0.1 m ^2, a commercially available butane gas is used as a simulation gas for fuel vapor, and the gas permeation amount is shown when air is mixed by 50%. The horizontal axis shows the differential pressure and the gas permeation speed. Even when the same module is used, in the case of the same differential pressure, the gas pressure of the pressurized system is larger than that of the vacuum system, and the gas throughput per unit time is larger.
As the differential pressure increases, the difference in the processing speed increases, and the processing speed of the pressurized system is 1.5 to 1.8 times higher at 0.04 MPa or more. In a vacuum system, the differential pressure is 0.08M
Although it can only take about Pa, the pressure system has the advantage that the processing amount per unit time can be increased 3 to 5 times the maximum speed of the vacuum system by increasing the pressure of the compressor.

FIG. 7 shows the relationship between the differential pressure and the separation coefficient. Even in the case of the same module and the same differential pressure, the separation coefficient of the pressurizing system according to the first embodiment is 1.5 to 1.7 times higher, and the efficiency is increased. In particular, in a differential pressure range of 0.08 MPa or more, which cannot be obtained only with a pressurized system, the separation coefficient is 2-3.
To rise twice. This is because, by using a pressurized system, the dissolution of the fuel vapor (hydrocarbon) into the membrane increases,
It is presumed that this was due to an increase in selectivity. According to Henry's law, the amount of dissolution in the membrane increases for any gas with an increase in pressure, but it can be predicted that the rate of increase in dissolution is greater in fuel vapor than in air. It is presumed that the cause is related to the ease of liquefaction (high boiling point) due to the pressure increase of the fuel vapor (hydrocarbon). The increase in the processing speed and the increase in the separation coefficient contribute to the downsizing of the membrane separation module, and can contribute to the layout problem, the weight reduction, and the cost reduction.

(Embodiment 2) FIG. 8 is a sectional view showing another embodiment of the fuel vapor recovery apparatus of the present invention, which has almost the same configuration as the apparatus of Embodiment 1, but is concentrated by a membrane separation module. The method of liquefaction and recovery of fuel vapor has been changed. In this embodiment, a condenser for liquefying fuel vapor (FIG. 9)
Is installed in a canister container (FIG. 10), and heat absorbed by the canister purge is used for cooling for liquefaction of fuel vapor.

The operation of the apparatus according to the present embodiment will be described below.
First, the phenomenon that fuel vapor is generated is the same as in the first embodiment. Next, a method of starting the engine and collecting the fuel vapor adsorbed by the canister 2 will be described. At the same time as the engine starts, the compressor 5 starts. When the compressor 5 starts, the discharge port 22 of the canister
, The suction is performed at a predetermined flow rate, so that air is blown into the canister from the gas introduction port 23. When the air is blown, the fuel vapor adsorbed on the activated carbon inside the canister 2 is purged. The fuel vapor is pressurized by the compressor and flows into the membrane separation module 6 through the path 12. When the purge is started, the temperature of the condenser in the canister decreases due to the heat absorption due to the desorption of the fuel vapor. The fuel vapor concentrated in the membrane separation module is discharged from 64 and sent to the condenser through the passage 14 and the inlet port 91 of the condenser. As the purge proceeds and the condenser cools, it is gradually liquefied and the fuel vapor is recovered through the condenser discharge port 92 and passage 16. The gas that cannot be liquefied is absorbed and recovered by the liquid fuel in the fuel tank. Since the gas that cannot be liquefied is cooled by passing through the condenser, the gas is easily absorbed by the fuel, and the recovery efficiency increases.

(Embodiment 3) FIGS. 11 and 12 show still another embodiment of the fuel vapor recovery apparatus of the present invention. The apparatus of this embodiment has two canisters 2A and 2B except that it has two canisters 2A and 2B. It has the same configuration as the device of the first embodiment. In this embodiment, the fuel vapor adsorption and the fuel vapor desorption are performed as a swing operation by valve control, and the fuel vapor is collected while the adsorption step and the desorption step are shared by the respective canisters.

First, the connection between the components in the apparatus shown in FIG. 11 will be described. Two canisters 2A and 2B
Are inlet ports 21A and 21B connected to a path for introducing fuel vapor from the fuel tank 1 into each container,
Gas inlet ports 23A and 23B are provided for introducing gas for purging the fuel vapor adsorbed by the adsorbent in each canister. Further, in the present embodiment, since the adsorption and desorption of the fuel vapor are performed by the swing operation, the inflow port 21 is used.
Cross four-way valves 31 and 32 are provided immediately before A and 21B and the gas introduction ports 23A and 23B, respectively, and by switching between them, fuel vapor is adsorbed or desorbed.

The operation of the fuel vapor recovery system having such a configuration will be described with reference to the flowchart shown in FIG. First, when the ignition Ig switch is OFF, that is, when fuel vapor is generated in a state where the engine is stopped, in this embodiment, since two canisters are used while performing a swing operation, here, as shown in FIG. The state in which fuel vapor is set to be adsorbed to the canister 2A via the cross four-way valve 31 will be described.

When the valve is set as shown in FIG. 11, the fuel vapor generated in the fuel tank 1 is adsorbed by the adsorbent in the canister 2A through the inflow port 21A through the cross four-way valve 31. You. At this time, the tank internal pressure is changed from the gas introduction port 23A to the cross four-way valve 32.
Through the pipe 41 to the atmosphere. In this case, in the flowchart shown in FIG. 13, it is determined whether or not the switch is ON by reading the Ig switch (S11) (S1).
2) NO, the routine of the flowchart ends.

Next, a method for starting the engine and recovering the fuel vapor adsorbed on the canister will be described. When the engine starts (ignition Ig switch ON), YES is determined in the Ig switch determination (S12), and if the compressor is OFF (S13), the compressor 5 (S14) is first started. Subsequently, switching determination of the cross four-way valve is performed (S15). It is determined whether five minutes or more have elapsed since the valve switching (S16), and if it has elapsed, the cross four-way valve is switched (S17). 5
The time of minute represents an example of a swing cycle time during engine start, and means that swing adsorption / desorption is repeated every 5 minutes. Here, it is assumed that the vehicle is parked for a long time and the fuel vapor is adsorbed on the canister 2A. In such a situation, it is determined that 5 minutes or more have passed since the cross four-way valve was switched immediately before, and the cross four-way valve is switched.

When the cross four-way valve is switched as shown in FIG. 12, gas flows in the direction of the arrow. The air in the atmosphere enters from the pipe 42 by the suction force of the compressor 5, and is sent to the canister 2A via the gas introduction port 23A via the cross four-way valve 32. The fuel vapor adsorbed by the adsorbent inside the canister 2A is
The desorption is started, discharged from the inflow port 21A, pressurized by the compressor 5 via the cross four-way valve 31, and sent to the gas introduction port 62 of the membrane separation module 6.

On the other hand, the fuel vapor generated from the fuel tank during the start of the engine passes through the cross four-way valve 31,
The adsorbent in the canister 2B is adsorbed from the fuel vapor inflow port 21B. The tank internal pressure that has increased due to the generation of steam flows back through the gas introduction port 23B, and is released from the pipe 41 to the atmosphere via the cross four-way valve 32.

Subsequently, the concentration of the gas containing the purged fuel vapor is determined (S18). This concentration determination may be performed by arranging and sensing a fuel vapor sensor as an upstream process of the membrane separation module 6, or may be predicted and controlled based on empirical rules such as vehicle experiments. And
In step S19, the fuel vapor concentration is checked, and the permeate-side flow rate and the non-permeate-side flow rate according to the fuel vapor concentration are determined.
The flow rate is adjusted by using, but the method of determining the ratio may be the same as in the first embodiment.

As an example of the case division in the third embodiment, when the concentration of the fuel vapor is 5% or more, the cooling module 9 is also turned off.
N (S21). Thereby, the membrane separation module 6
Then, the separation is started, and the concentrated fuel component is sent from the permeate-side discharge port 63 to the cooling module 9 via the path 14, liquefied, and returned to the fuel tank 1 to be collected. The routine ends.

If the above routine is repeated, the fuel vapor concentration may be less than 5% depending on the environment and operating conditions. In such a case, the purging is not required or the purging is completed. The cross four-way valve is switched (S22), and the density determination (S23) is performed again. In the first and second embodiments, the purging is determined to be less than 1%. However, in this embodiment having two canisters and performing the swing operation, the canister can be switched to the purged canister every 5 minutes, and the capacity is reduced. Since it is possible to obtain a margin, the decision was made at 5%.

When the valve is switched, gas flows as shown in FIG. That is, the fuel vapor of the canister 2B is supplied to the membrane separation module 6, while the vapor of the fuel tank 1 is adsorbed by the canister 2A. When the fuel vapor is adsorbed on the canister 2B, the concentration of the fuel vapor supplied to the membrane separation module 6 increases. At this time, if it is 5% or more, the routine of the flowchart is temporarily terminated (S24), and the detachment of the canister 2B is started from the start. On the other hand, when the concentration of less than 5% continues even after switching, the canister 2A,
It is determined that the fuel vapor adsorption amount is small for both 2B, and both the cooling module and the compressor are turned off (S25), and the fuel vapor recovery is stopped. By stopping at this point, unnecessary energy is not consumed when there is no need for recovery, and a decrease in fuel efficiency can be prevented. Then 5
When the minutes have elapsed (S26, S27), the routine of the flowchart is terminated.

According to the processing based on the above-described flowchart, when the engine is started, these cycles are repeated to gradually purge the fuel vapor stored in the canister, thereby preparing for refueling or parking for a long time. It becomes possible. In this embodiment, the concentration is checked every 5 minutes at most. Therefore, even if the amount of fuel vapor generated varies due to the operating condition or environmental change, a recovery method suitable for the condition is promptly selected. It is possible to collect. In addition, the processing method after being sent to the membrane separation module can be performed in the same manner as in the first and second embodiments.

Further, in this embodiment, the adsorption and desorption can be performed by separate canisters. Therefore, even when the amount of fuel vapor generated from the tank is large, particularly during a traffic jam in summer when the engine is started, the operation can be performed. Unlike the cases of Examples 1 and 2, there is no effect on the desorption process, and since high-concentration fuel vapor is not supplied to the membrane separation module, there is an advantage that the load on the membrane separation module is reduced. is there. Further, when the exhaust emission regulation is strengthened or the capacity of the canister becomes insufficient due to parking for a long time, the cross four-way valve 3 is used even when the engine is stopped.
If control for switching between 1 and 32 at regular time intervals is added, the two canisters can be evenly sucked. In this case, two capacities of the canisters 2A and 2B can be included in the calculation as the adsorption capacity of the fuel vapor generated while the engine is stopped. However, frequent valve switching is not preferable because it consumes the battery.

Further, as described above, since the present embodiment is also of the pressurized type using a compressor, the gas throughput per unit film area can be improved even if the same module and the same differential pressure are used as compared with the vacuum type. Is 1.5-1.8 times, 0.08MP which can be taken only by pressurized type
At a differential pressure equal to or greater than a, the pressure can be increased 3 to 5 times as compared with the maximum speed of the vacuum system. The separation factor is 1.5 to 1.8 compared to the vacuum type by using the pressurized type.
Twice as high, increasing efficiency. In particular, in a differential pressure region of 0.08 MPa or more, which cannot be obtained only by a pressurized system, the selectivity is increased by a factor of 2 to 3 times. Needless to say, the performance improvement contributes to the downsizing of the separation module, and can also contribute to layout problems and weight reduction.

Although the present invention has been described in detail with reference to some preferred embodiments, the present invention is not limited to these embodiments, and various modifications can be made within the scope of the present invention.

[0062]

As described above, according to the present invention, a pressurizing system for pressurizing air containing fuel vapor generated by purging from a fuel tank or a canister and sending it to a membrane separation module by using a compressor. The use of a separation membrane system has greatly improved the efficiency of fuel vapor recovery and reduced the weight of the equipment, and has no impact on the driving characteristics of automobiles and the components of exhaust gas. It is possible to provide a fuel vapor recovery device that does not discharge into the fuel vapor recovery device.

That is, since air containing fuel vapor generated by purging from a fuel tank or a canister is processed from a vacuum type system to a pressurization type system, the same differential pressure, the same module, and the same film per unit membrane area are used. The gas throughput, differential pressure and selectivity can be improved. The separation factor is higher than that of the vacuum type by using the pressurized type, and the recovery efficiency is increased.This performance improvement also contributes to the downsizing of the separation module, which also contributes to layout problems and weight reduction. it can. In addition, since the membrane separation module uses a fuel selective permeation type separation membrane, even if non-permeate components of the membrane are introduced into the intake pipe of a direct injection engine during stratified charge combustion, the operation characteristics and exhaust gas components will be affected. It is possible to provide a fuel vapor recovery device that has no influence and does not release fuel vapor to the atmosphere even when the amount of generated fuel vapor is large. Further, in general, a pressurized type piping system has an advantage that a pressure loss is smaller than that of a vacuum type, so that the piping diameter can be reduced, and also in this aspect, there is an advantage of reduction in size and weight.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an example of a conventional fuel vapor recovery device.

FIG. 2 is a sectional view showing one embodiment of the fuel vapor recovery device of the present invention.

FIG. 3 is a cross-sectional view and a vertical cross-sectional view illustrating an example of a membrane separation module.

FIG. 4 is a flowchart showing an example of control of the fuel vapor recovery device shown in FIG.

FIG. 5 is a sectional view showing a fuel vapor recovery device of a comparative example.

FIG. 6 is a graph showing the gas processing speeds of an example and a comparative example.

FIG. 7 is a graph showing a separation coefficient between an example and a comparative example.

FIG. 8 is a sectional view showing another embodiment of the fuel vapor recovery device of the present invention.

FIG. 9 is a diagram illustrating an example of a capacitor installed in a canister.

FIG. 10 is a diagram showing an example in which a capacitor is installed in a canister.

FIG. 11 is a sectional view showing still another embodiment of the fuel vapor recovery device of the present invention.

FIG. 12 is a sectional view showing still another embodiment of the fuel vapor recovery device of the present invention.

FIG. 13 is a flowchart showing an example of control of the fuel vapor recovery device shown in FIGS. 11 and 12.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fuel tank 2, 2A, 2B canister 3 Purge control valve 4 Intake pipe 5 Compressor 5A Vacuum pump 6 Membrane separation module 7 Negative pressure control valve 9 Cooling module 11, 12, 14-18 Route 21 Fuel vapor inflow ports 21A, 21B Inflow Port 22 Fuel vapor discharge port 23, 23A, 23B Gas introduction port 31, 32 Cross four-way valve 41, 42 Pipeline 61 Module case 62 Fuel vapor introduction port 63 Permeate side gas discharge port 64 Non-permeate side gas discharge port 65 Outer space 66 Inner space 67 Separation membrane 68 O-ring F Fuel L Liquefied fuel V Absorbed fuel vapor 91 Condenser inlet port 92 Condenser outlet port

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) F02M 37/00 301 F02M 37/00 301H

Claims (15)

[Claims] 1. An inflow port for introducing fuel vapor from a fuel tank, an adsorbing means for adsorbing the inflowing fuel vapor,
A gas introduction port for introducing a gas for purging the fuel vapor adsorbed by the adsorption means, a canister having a discharge port for discharging the purged fuel vapor, and a fuel vapor flowing from a discharge port of the canister. A membrane separation module for separating a fuel vapor rich component and an air rich component by a vapor selective permeable separation membrane and discharging each component from an air rich component discharge port and a fuel vapor rich component discharge port; And a compressor for supplying a purged fuel vapor to the membrane separation module and generating a driving force for introducing the gas, supplying the fuel vapor, and performing the membrane separation. The component discharge port is disposed on the permeate side of the separation membrane and connected to the fuel tank, and the fuel vapor The fuel vapor component contained in the pitch component, liquefied and recovered by absorbing the recovery or liquid fuel to the fuel tank, the air rich component exhaust port of the membrane separation module,
A fuel vapor recovery device, which is disposed on the non-permeate side of the separation membrane and is connected to an intake pipe of an engine, and the air-rich component is removed by a negative pressure generated by the engine. 2. A pressure of the compressor at the time of supplying gas to the membrane separation module is set to a gauge pressure of 0.0.
2. The fuel vapor recovery device according to claim 1, wherein the pressure is in a range of 1 MPa to 0.18 MPa. 3. The fuel vapor recovery device according to claim 1, wherein the membrane separation module includes the separation membrane having a separation coefficient between the fuel vapor and air in a range of 4 to 50. 4. A control valve is provided between the air-rich component discharge port of the membrane separation module and the intake pipe of the engine, the control valve being opened only when the pressure becomes lower than a predetermined negative pressure. The fuel vapor recovery device according to any one of claims 1 to 3, wherein 5. The separation membrane connected to an intake pipe of the engine, wherein a ratio of a permeation side flow rate and a non-permeation side flow rate of the separation membrane is changed according to a concentration of fuel vapor supplied to the membrane separation module. The fuel vapor recovery device according to any one of claims 1 to 4, wherein the fuel vapor on the non-permeate side is controlled to a concentration and a flow rate that do not affect stratified combustion. 6. The capacity of the compressor is variable,
The fuel vapor recovery device according to claim 5, wherein the ratio of the permeate-side flow rate and the non-permeate-side flow rate of the separation membrane is controlled by the compressor. 7. A flow control valve is provided upstream or downstream of the non-permeate side of the membrane separation module, and a ratio of a permeate side flow rate and a non-permeate side flow rate of the separation membrane is controlled by the flow rate control valve. The fuel vapor recovery device according to claim 5, wherein: 8. The fuel vapor recovery according to claim 5, wherein the ratio of the permeate-side flow rate to the non-permeate-side flow rate of the separation membrane is controlled while varying the pressure supplied to the separation membrane by a pressure regulating valve. apparatus. 9. The fuel cell system according to claim 1, wherein the canister has two or more canisters, and a fuel vapor adsorption and a fuel vapor desorption are swing-operated for each canister by valve control. The fuel vapor recovery device as described in the above. 10. A fuel component discharge port connected to the permeate side of the membrane separation module is connected to a fuel tank.
The fuel vapor recovery device according to any one of claims 1 to 9, wherein the fuel component is absorbed by the liquid fuel in the fuel tank. 11. A cooling module is provided between a fuel-rich component discharge port of the membrane separation module and the fuel tank, whereby a fuel vapor component is liquefied and returned to the fuel tank. The fuel vapor recovery device according to any one of Items 1 to 10. 12. The condenser is built in the canister, is cooled by utilizing endothermic energy generated when the fuel vapor is purged from the canister, and is generated by at least one of the fuel tank and the fuel system line. The fuel vapor recovery apparatus according to any one of claims 1 to 11, wherein the fuel vapor and the fuel vapor separated and concentrated by the membrane separation module are liquefied and recovered by the condenser. 13. The separation membrane according to claim 1, wherein the separation membrane is surface-treated using a polyimide as a base membrane and a crosslinked polyorganosiloxane as a separation active layer.
Item 13. The fuel vapor recovery device according to any one of Items 12. 14. A direct injection engine system provided with the fuel vapor recovery device according to claim 1. Description: 15. The direct injection engine system according to claim 14, wherein super-lean combustion or stratified combustion is performed.