JPH0953521A - Fuel vapor treating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a fuel vapor treating device with high adsorptive capacity and a low pressure loss structure by introducing fuel vapor in cells having their adsorptive capacity. SOLUTION: The inside space of a container H provided with a fuel vapor introducing passage H1 communicated with the fuel tank and an atmosphere introducing passage H2 communicated with the atmosphere is partitioned in plural cells S1 to Sn in the flow direction of fuel vapor. And adsorptive material layer 1 is formed in each of those plural cells. Respective cells except the last cell Sn are provided with bypass passages 3 each of which communicates a cell located upstream and a cell located downstream and each opening/closing valve 4 for opening/closing those bypass passages. Pressure loss reduction is planned by opening the opening/closing valve 4 by means of an opening/closing valve operator 5 for sending fuel vapor to cell S2 located downstream through bypass passage 3 when the saturation of cell S1 is detected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel vapor processing apparatus for adsorbing fuel vapor from a fuel tank and preventing the vapor from being discharged outside the vehicle.

[0002]

2. Description of the Related Art Such a fuel vapor processing apparatus has a basic structure in which a container is filled with an adsorbent such as activated carbon so that one end of the container is connected to a fuel tank and the other end is connected to the atmosphere. The fuel vapor generated in the fuel tank is introduced into the container to be adsorbed by the adsorbent.
The one end is further in communication with the intake passage of the engine, and the steam introduced into the container is desorbed by the atmosphere introduced into the atmosphere communication port due to the negative pressure in the intake passage of the engine during engine operation. It is separated and sucked into the intake passage.

[0003]

If, for example, the liquid seal refueling method is adopted to prevent the discharge of fuel vapor during refueling, the amount of vapor flowing from the fuel tank into the fuel vapor processing apparatus increases. Therefore, it is required to improve the adsorption capacity of the fuel vapor processing device.
In this case, it is also necessary that the pressure loss at the time of steam inflow is sufficiently low so that the internal pressure of the fuel tank does not rise excessively.

However, when the size of the apparatus is increased to increase the adsorption amount and the ratio of the diameter of the container filled with the adsorbent to the port diameter of the vapor introduction section becomes large, a part of the adsorbent layer directly below the port is formed. The vapor flow is concentrated to increase the pressure loss and reduce the adsorption efficiency. Therefore, it is conceivable to arrange a baffle plate on the upstream side of the adsorbent layer to allow the vapor flow to flow into the adsorbent layer evenly, but the increase in cost due to the increase in the number of parts and the large pressure loss There is.

On the other hand, it is known that increasing the ratio L / D of the length L and the diameter D of the container is effective for improving the adsorption efficiency. The container diameter D is about 10 times the port diameter. It is conceivable that the required amount of adsorbent is obtained by increasing the container length L to a value not more than that. However, since the pressure loss is proportional to the container length L, if the container length is increased to secure the required adsorption amount, the pressure loss becomes large.

An object of the present invention is to solve the above problems and an object thereof is to provide a fuel vapor treatment apparatus having a high adsorption capacity and a low pressure loss structure.

[0007]

1 (a) and 1 (b) show the structure of the present invention for solving the above problems, the fuel vapor introducing passage H1 communicating with a fuel tank and the atmosphere. In a fuel vapor processing apparatus in which an adsorbent for fuel vapor is filled in a container H provided with an air introduction passage H2 to form an adsorbent layer 1, a plurality of cells S1 are formed in the container H in the flow direction of the fuel vapor. ~ Sn, these plurality of cells S1 ~ Sn
The adsorbent layer 1 is formed on each of the above. Then, for each cell except the last cell Sn, the bypass passage 3 that connects the upstream side cell and the downstream side cell, and the bypass passage 3
And an opening / closing valve 4 for opening and closing, and detecting whether or not the cell is saturated, and opening the opening / closing valve 4 of the bypass passage 3 that connects the upstream side and the downstream side of the cell where saturation is detected,
The valve opening / closing means 5 is provided for sending the fuel vapor to the cell on the downstream side through the bypass passage 3 (claim 1).

In the above structure, the fuel vapor introduced into the container H through the fuel vapor introducing passage H1 is first adsorbed and held on the adsorbent layer 1 of the most upstream cell S1. When the adsorbent layer 1 of the cell S1 is saturated and breakthrough due to the progress of adsorption, the valve opening / closing means 5 detects this and opens the opening / closing valve 4. Therefore, the fuel vapor flows into the bypass passage 3 and the cell S1
It is introduced into the downstream cell S2. Thereafter, similarly, the saturated cells are bypassed and the fuel vapor sequentially flows into the cells on the downstream side.

As described above, the fuel vapor is directly sent to the downstream cell having the adsorption capacity without flowing through the saturated cell having a large pressure loss, so that the pressure loss can be greatly reduced. Therefore, each cell can be shaped so that the adsorption efficiency is maximized, so that it is possible to achieve both high adsorption capacity and low pressure loss.

An air layer 2 is provided between the adjacent cells S1 to Sn.
(Claim 2), and by providing the air layer 2, the diffusion of the adsorbed fuel vapor can be prevented.
When the valve opening / closing means 5 is provided with a means for detecting purge air from the atmosphere introducing passage and the opening / closing valve is closed when the purge air is detected (Claim 3), the saturated adsorbent layer 1 can be efficiently purged. You can

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1A, the inside of the cylindrical container H whose both ends are closed is divided into a plurality of layers in the flow direction of the fuel vapor, and the first layer cell S1 and the second layer cell S are sequentially arranged from the upstream side.
2 ... The final layer cell Sn is formed. Activated carbon C is filled in each of the cells S1 to Sn to form the adsorbent layer 1.

At one end surface (left end surface in the drawing) of the container H, a fuel vapor introducing passage H1 communicating with a fuel tank (not shown) is provided.
However, the other end surface (the right end surface in the figure) is provided with an atmosphere introduction path H2 communicating with the atmosphere. An air layer 2 is formed between the cells S1 to Sn, and between the first layer cell S1 and the final layer cell Sn and the container H.

In the first layer cell S1, at a position opposite to the fuel vapor introduction path H1, the adsorbent layer 1 is penetrated to extend in the axial direction, and the air layer 2 upstream of the first layer cell S1 and the air layer 2 downstream thereof are provided. A bypass passage 3 that connects the air layer 2 is formed. The diameter of the bypass passage 3 is approximately the same as the diameter of the fuel vapor introduction passage H1.

An opening / closing valve 4 for opening and closing the bypass passage 3 is provided at the rear end portion of the bypass passage 3. The opening / closing valve 4 is adapted to be opened / closed by an opening / closing valve actuating device 5 which is a valve opening / closing means installed at the upstream end of the second layer cell S2. ) Is closed. The on-off valve actuating device 5 includes a temperature detection unit that detects the heat of adsorption generated during the adsorption of the fuel vapor and an actuator function that opens and closes the on-off valve. When the temperature detection unit detects the heat of adsorption, The on-off valve 4 is opened on the assumption that the first layer cell S1 is saturated.

In the second layer cell S2 as well, a similar bypass passage 3 is formed so as to face the bypass passage 3 of the first layer cell S1, and thereafter, in the same manner, in each cell except the final layer cell Sn, A bypass passage 3 that connects the upstream air layer 2 and the downstream air layer 2 is formed. Further, the same on-off valve 4 and on-off valve actuating device 5 are provided in each of the bypass passages 3 so that the saturated cells are bypassed and the fuel vapor sequentially flows into the cells on the downstream side.

The on-off valve actuating device 5 is provided with a redundant function between the temperature detecting portion and the actuator, and keeps the valve open until a reverse flow having a flow velocity higher than a certain level flows into the cell. . There are two cases in which the backflow flows into the cell during engine purging and when the vehicle is left uncooled, and the flow velocities differ greatly when the engine is purged: 5 to 30 l / min and when the vehicle is left: 0.05 l / min or less. Therefore, if the discriminant value is set to, for example, 1 l / min and the valve is closed at the time of engine purging with a large desorption action, the cells in the saturated state can be efficiently purged.

Further, if the valve closing determination is made from both the reverse flow and the desorption cooling, the valve closing progresses sequentially from the upstream side cell with respect to the purge, and the purge flow bypasses the cells being opened. Since it passes through the passage, it is possible to reduce the resistance at the time of desorption.

Next, the operation of the fuel vapor processing apparatus having the above structure will be described. When fuel vapor is generated in the fuel tank at the time of refueling or the like, the fuel vapor is introduced into the container H through the fuel vapor introduction passage H1 and is adsorbed and held on the adsorbent layer 1 of the first layer cell S1. As the adsorption progresses, the adsorbent layer 1 of the first-layer cell S1 is saturated and breakthrough, the fuel vapor flows into the second-layer cell S2, and when the temperature detector of the on-off valve operating device 5 detects the heat of adsorption, On the assumption that the upstream first layer cell S1 is saturated, the on-off valve 4 is opened. Therefore, the fuel vapor flows into the bypass passage 3 having a small ventilation resistance, is once diffused in the air layer 2, and is then introduced into the second layer cell S2.

When the second layer cell S2 is saturated and breached, the on-off valve operating device installed in the third layer cell (not shown) opens the bypass passage 3. Thereafter, similarly, the saturated cells are bypassed and the fuel vapor sequentially flows into the cells on the downstream side.
Then, the fuel vapor is directly sent to the downstream cell having the adsorbing power without flowing through the cell having the large ventilation resistance, so that the pressure loss can be sufficiently reduced.

By the way, the longer the length of each cell, the higher the adsorption efficiency, but at the end of the adsorption, the saturated layer becomes long and a large amount of vapor passes through, resulting in a large ventilation resistance.
Also, since a large amount of purge flow passes, the purge resistance also increases.

Then, when the relationship between the progress of adsorption of the adsorbent layer 1 and the pressure loss was examined, it was found that the pressure loss increased with the progress of the adsorption portion 11, as shown in FIG. this is,
As shown in FIG. 3, adsorption of vapor to the adsorbent layer 1 is performed in order from the vapor introduction side in a saturated layer, an adsorption layer, and a non-adhesion layer. Is large, and the flow rate of only air that is not adsorbed in the non-adhered layer is small and pressure loss does not occur.

In the present invention, in order to eliminate this waste, a plurality of elongated cells are arranged in series, and the fuel vapor (or purge air) is introduced into the cell having adsorption capacity (or purge capacity) and the bypass passage 3 It is designed to be introduced directly via. That is, the fuel vapor bypasses the saturated layer in FIG. 3 so as to always flow into the adsorption layer, whereby both high adsorption / desorption ability and low pressure loss can be achieved.

Further, the adsorbed fuel vapor diffuses through the adjacent activated carbons with the passage of time. In the above structure, however, an air layer is provided between the cells so that the activated carbons of the adjacent cells do not come into contact with each other. Therefore, the diffusion of the fuel vapor in the pores can be suppressed, and the deterioration of the adsorption capacity and the release of the fuel vapor to the atmosphere when the vehicle is left for a long time can be prevented.

In the above embodiment, the cells are arranged coaxially, but the arrangement of the cells is not limited to this, and it is sufficient that the cells are connected in series. In the embodiment shown in FIG.
The first layer cell S1 to the third layer cell S3 are arranged in a container H side by side. Further, as in the embodiment shown in FIG. 5, the first layer cell S1 to the third layer cell S3 have different volumes,
The bypass passage 3 may be formed in a curved shape, and the same effects as those of the first embodiment can be obtained in either case.

It is also possible to determine whether the on-off valve is opened or closed by calculating from the relationship between the flow rate and the pressure, and making the determination through the solenoid valve. In the embodiment of FIG. 6, the number of cells is 3 in the basic configuration of FIG. 1, and the first layer cell S1 and the second layer cell S2 are included.
Has a bypass passage 3 penetrating therethrough. The opening / closing valve 4 of the bypass passage 3 is opened / closed by an actuator 6 arranged in the air layer 2.

A pressure gauge 71 and a flow meter 72 for controlling the opening and closing of the on-off valve 4 at the time of adsorption are arranged in the fuel vapor introducing passage H1, and these measured values are input to the control device 7. It is designed to work. The control device 7 compares the ratio of pressure to vapor flow rate with prestored data to detect which cell has reached a saturated state, activates the actuator 6 and opens the on-off valve 4 as necessary. Speak.

A pressure gauge 81 and a flowmeter 82 for controlling the closing of the on-off valve 4 at the time of purging are provided in the atmosphere introducing passage H2.
Is installed. Then, the control device 8 determines which cell should be closed based on the ratio of the steam flow rate to the pressure, operates the actuator 6 and closes the on-off valve 4 as necessary.

[0028]

According to the present invention, by providing a bypass passage and introducing a fuel vapor into a cell having an adsorption ability, a fuel vapor treatment apparatus capable of obtaining a high adsorption amount and significantly reducing pressure loss is realized. it can. Therefore, it is possible to reliably prevent the fuel vapor from being released into the atmosphere, and the utility value is great.

[Brief description of drawings]

FIG. 1 (a) is a schematic sectional view of a fuel vapor processing apparatus showing an embodiment of the present invention, and FIG. 1 (b) is a diagram for explaining the operation of the fuel vapor processing apparatus.

FIG. 2 is a diagram showing a pressure loss characteristic of a fuel vapor processing apparatus.

FIG. 3 is a diagram for explaining a progress state of adsorption of the fuel vapor processing apparatus.

FIG. 4 is a schematic sectional view of a fuel vapor processing apparatus showing a second embodiment of the present invention.

FIG. 5 is a schematic sectional view of a fuel vapor processing apparatus showing a third embodiment of the present invention.

FIG. 6 is a schematic sectional view of a fuel vapor processing apparatus showing a fourth embodiment of the present invention.

[Explanation of symbols]

 H container H1 Fuel vapor introduction path H2 Atmosphere introduction path C Activated carbon S1-Sn cell 1 Adsorbent layer 2 Air layer 3 Bypass passage 4 Open / close valve 5 Open / close valve operating device (valve opening / closing means)

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tokio Obama 14 Iwatani, Shimohakaku-cho, Nishio-shi, Aichi Japan Auto Parts Research Institute (72) Inventor Katsuo Kurokami 14 Iwatani, Shimohakaku-cho, Nishio-shi, Aichi Stock Within Japan Auto Parts Research Institute

Claims (3)

[Claims] 1. A fuel vapor processing apparatus in which an adsorbent for fuel vapor is filled in a container provided with a fuel vapor introducing passage communicating with a fuel tank and an atmosphere introducing passage communicating with the atmosphere to form an adsorbent layer. In, the inside of the container is divided into a plurality of cells in the flow direction of the fuel vapor, and the adsorbent layer is formed in each of the plurality of cells. For each cell except the last cell, its upstream side and downstream side A bypass passage communicating with the cell on the side and an opening / closing valve for opening and closing the bypass passage are provided, and it is detected whether or not the cell is saturated, and the upstream and downstream cells of the cell in which saturation is detected are communicated with each other. A fuel vapor processing apparatus comprising a valve opening / closing means for opening an opening / closing valve of a bypass passage and sending fuel vapor to a cell on a downstream side through the bypass passage. 2. The fuel vapor processing apparatus according to claim 1, wherein an air layer is provided between the adjacent cells. 3. The valve opening / closing means has a means for detecting purge air from the atmosphere introducing passage, and the opening / closing valve is closed when the purge air is detected.
The described fuel vapor treatment device.