Canister

Abstract

The present invention provides a canister that can eliminate the unevenness of evaporative gases introduced into the intake system and suppress the leakage of evaporative gases into the atmosphere. [Solution] The canister 1 comprises an adsorbent 6 having the ability to adsorb evaporated fuel generated in the fuel tank, a case 2 containing the adsorbent 6, a tank port 3 connecting the case 2 to the fuel tank and through which vaporized gas containing evaporated fuel flows in from the fuel tank, a purge port 4 connecting the case 2 to the engine's intake system and communicating with the tank port 3 via the adsorbent 6, an air outlet 7 releasing the gas that has passed through the adsorbent 6 to the atmosphere, a bypass chamber 40 forming a bypass space 41 which is part of a bypass flow path connecting the tank port 3 and the purge port 4 so as to bypass the adsorbent 6, and a valve 5 which opens the bypass flow path only when predetermined conditions are met. The flow path area of ​​the bypass space 41 is larger than the flow path area of ​​the tank port 3.

Description

Technical Field

[0001] This invention relates to a canister attached to an engine.

Background Art

[0002] Conventionally, in an engine (internal combustion engine) that obtains power by burning volatile fuel, a canister (charcoal canister, carbon canister, vapor collector) is provided to suppress the emission of evaporated fuel (fuel gas, gasoline vapor, etc.) generated in the fuel tank into the atmosphere. The canister incorporates an adsorbent such as activated carbon or zeolite that temporarily adsorbs the evaporated fuel contained in the evaporated gas flowing in from the passage connecting the fuel tank and the canister. The evaporated fuel adsorbed by the adsorbent desorbs from the adsorbent and is introduced into the combustion chamber when outside air flowing in from the air inlet passes through the adsorbent during engine operation.

[0003] For example, Patent Document 1 discloses a device that adsorbs vapor (evaporated fuel) flowing into the canister from a vapor passage connecting the fuel tank and the canister in the canister, and purges the adsorbed vapor into the engine from a purge passage connecting the canister and the engine intake pipe. This device further includes a bypass passage that bypasses the canister and connects the vapor passage and the purge passage, and an on-off valve provided in the bypass passage. In Patent Document 1, for example, by opening the on-off valve during high engine load, the vapor can be directly purged into the intake pipe through the bypass passage, so it is said that the canister will not become full of evaporated fuel or emit a gasoline odor.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in the device described in Patent Document 1, when the on / off valve is opened, vapor (evaporative gas) from the fuel tank flows directly into the purge passage via the bypass passage, which means that the vapor may be introduced into the intake manifold with uneven pressure (concentration). This may cause instability in engine control when the on / off valve is open. Furthermore, in a configuration that switches the opening and closing of the bypass passage according to the engine's operating state, as in the device described in Patent Document 1, the bypass passage is not necessarily opened when the internal pressure of the fuel tank is high. In other words, in the above configuration, when the internal pressure of the fuel tank is high, a high flow rate of vapor may flow into the canister. In this case, the evaporated fuel contained in the vapor may not be sufficiently captured by the adsorbent, and the vapor may escape into the atmosphere through the air inlet.

[0006] The canister in this invention was devised in light of these challenges, and one of its purposes is to eliminate the unevenness of the evaporative gas introduced into the intake system and to suppress the leakage of evaporative gas into the atmosphere. In addition to this purpose, another purpose of this invention is to achieve effects and advantages that cannot be obtained by conventional technology, which are derived from the various configurations shown in the embodiments for carrying out the invention described later. [Means for solving the problem]

[0007] The disclosed canister can be implemented in the following manner (examples of application) and solves at least some of the above problems. Each of the manners from Manifest 2 onward is an additional manner that can be appropriately selected and each of the manners that can be omitted. None of the manners from Manifest 2 onward disclose any manner or configuration that is essential to this case.

[0008] Embodiment 1. The disclosed canister comprises: an adsorbent having the ability to adsorb evaporated fuel generated in a fuel tank; a case containing the adsorbent; a tank port connecting the case to the fuel tank, through which vaporized gas containing the evaporated fuel flows in from the fuel tank; a purge port connecting the case to the engine's intake system, and communicating with the tank port via the adsorbent; an air port provided in the case for releasing the gas that has passed through the adsorbent to the atmosphere; a bypass chamber forming a bypass space that constitutes part of a bypass flow path connecting the tank port and the purge port so as to bypass the adsorbent; and a valve provided in the bypass chamber that opens the bypass flow path only when predetermined conditions are met, including the internal pressure of the fuel tank being in a high-pressure state exceeding a first threshold. The flow path area of ​​the bypass space is larger than the flow path area of ​​the tank port.

[0009] Embodiment 2. In Embodiment 1 described above, it is preferable that the predetermined conditions further include the condition that the pressure of the intake system is less than a second threshold lower than atmospheric pressure. Embodiment 3. In Embodiment 1 or 2 described above, it is preferable that the valve is a mechanical valve.

[0010] Embodiment 4. In any one of embodiments 1 to 3 above, it is preferable that the adsorbent includes a first adsorbent and a second adsorbent. Furthermore, it is preferable that the case has a first chamber in which the first adsorbent is housed and the tank port is connected, a second chamber in which the second adsorbent is housed and the purge port and the air vent are provided, and a first partition wall separating the first chamber and the second chamber. In this case, it is preferable that the first chamber and the second chamber are arranged adjacent to each other with the first partition wall in between, and that the first partition wall partially partitions the inside of the case while maintaining the communication state of the tank port and the air vent, which communicate with each other via the first adsorbent and the second adsorbent.

[0011] Embodiment 5. In Embodiment 4 described above, it is preferable that the first chamber forms a first connection space that connects the tank port and the bypass chamber and also serves as part of the bypass flow path, and a first containment space that communicates with the tank port via the first connection space and contains the first adsorbent. Furthermore, it is preferable that the second chamber forms a second connection space that connects the bypass chamber and the purge port and also serves as part of the bypass flow path, and a second containment space that communicates with the purge port via the second connection space and contains the second adsorbent. In this case, it is preferable that the first connection space and the second connection space are arranged adjacent to each other and completely separated by the first partition wall, and that the flow path area of ​​at least one of the flow paths of the bypass flow path that passes through the first connection space and the flow path that passes through the second connection space is larger than the flow path area of ​​the tank port.

[0012] Embodiment 6. In Embodiment 5 described above, it is preferable that the case has a second partition wall that partially partitions the second containment space while maintaining the communication state of the bypass chamber and the air outlet, which are in communication with each other via the second adsorbent. Embodiment 7. In Embodiment 5 or 6 described above, it is preferable that the second chamber is provided with ribs extending from the edge of the air outlet to the second adsorbent. [Effects of the Invention]

[0013] According to the disclosed canister, it is possible to eliminate the unevenness of the evaporative gas introduced into the intake system and suppress the leakage of evaporative gas into the atmosphere. [Brief explanation of the drawing]

[0014] [Figure 1] This is a longitudinal cross-sectional view illustrating the configuration of a canister as an example. [Figure 2] Figure 1 is a cross-sectional perspective view showing the main components of the canister. [Figure 3] This is a longitudinal cross-sectional view illustrating the configuration of a modified canister. [Modes for carrying out the invention]

[0015] The canister will be described as an embodiment with reference to the drawings. The embodiments shown below are merely illustrative, and there is no intention to exclude various modifications or applications of techniques not explicitly shown in the embodiments below. Each component of these embodiments can be modified in various ways without departing from their intended purpose. Furthermore, components can be selected or combined as needed.

[0016] The disclosed canister is attached to an engine and can be implemented by the following embodiments. The engines referred to herein include various internal combustion engines that operate on volatile fuels, such as gasoline engines and jet engines. The canisters of these embodiments are attached to engines mounted in vehicles. Regarding the definition of direction in the embodiments, unless otherwise specified, the direction of the components and parts constituting the canister refers to the direction when it is mounted in a vehicle.

[0017] [1. Overall Structure] Figure 1 is a longitudinal cross-sectional view illustrating the configuration of a canister 1 as an embodiment. The canister 1 may be mounted on the vehicle while maintaining the orientation (vertical direction) shown in Figure 1, or it may be mounted on the vehicle at a slight inclination relative to the vertical direction. The canister 1 comprises an adsorbent 6, a case 2, a tank port 3, a purge port 4, an air outlet 7, a bypass chamber 40, and a valve 5. In this embodiment, a canister 1 further comprising a cover 9 is provided as an example.

[0018] The adsorbent 6 is a substance that has the ability to adsorb evaporated fuel generated in a fuel tank (not shown). Specific examples of the adsorbent 6 include activated carbon and zeolite. The adsorbent 6 may be a solid porous body (molded product), or it may be a powder or granular material sealed in a breathable bag. In this embodiment, the adsorbent 6 includes the first adsorbent 6A and the second adsorbent 6B, which will be described later, and will hereinafter also be referred to as "adsorbent 6A, 6B".

[0019] Case 2 is a container that houses (builds in) the adsorbent 6 inside and forms a part of the outer shell of the canister 1. The tank port 3 is a connection port for communicating the case 2 with the fuel tank, and is the part where the evaporated gas containing the evaporated fuel flows from the fuel tank into the case 2. The tank port 3 and the fuel tank are connected by an evaporation fuel pipe material (not shown). The purge port 4 is a connection port for communicating the case 2 with the intake system (not shown) of the engine, and communicates with the tank port 3 through the adsorbent 6. The purge port 4 and the intake system are connected by a purge pipe material (not shown). Note that a purge valve (not shown) may be installed in the purge pipe material. In this case, the opening and closing of the purge valve may be controlled in conjunction with the purge control by an engine control device (not shown). Alternatively, a configuration without a purge valve in the purge pipe material may also be used. In this case, gas will flow from the purge port 4 into the intake system according to the magnitude of the negative pressure in the intake system.

[0020] The air vent 7 is an opening that releases the gas that has passed through the adsorbent 6 among the evaporated gas that has flowed into the case 2 to the atmosphere, and is provided in the case 2. The bypass chamber 40 is a chamber that forms a bypass space 41 that forms a part of the bypass flow path R that connects the tank port 3 and the purge port 4 so as to bypass the adsorbent 6. The configuration of the bypass chamber 40 and the bypass flow path R will be described later. The valve 5 is a normally closed valve provided in the bypass chamber 40, and opens the bypass flow path R only when a predetermined condition is satisfied. The configuration of the valve 5 will also be described later.

[0021] As shown in FIG. 1, the case 2 shown in this embodiment is formed in a stepped hollow cylindrical shape with openings formed at both ends and the outer dimensions changing in the vertical direction in FIG. 1. In this embodiment, a stepped cylindrical case 2 is illustrated. The case 2 has a small-diameter portion 2a with a small outer diameter dimension provided above a large-diameter portion 2c with a larger outer diameter dimension than this, and has a stepped portion 2b connecting these small-diameter portion 2a and large-diameter portion 2c.

[0022] The opening of the small-diameter portion 2a (the upper opening in FIG. 1) is blocked by the bypass chamber 40, and the opening of the large-diameter portion 2c (the lower opening in FIG. 1) is blocked by the cover 9 which is a lid member of the case 2. That is, the bypass chamber 40 is fixed to the upper end of the case 2, and the cover 9 is fixed to the lower end of the case 2. The stepped portion 2b is a surface portion connecting the lower end edge of the small-diameter portion 2a and the upper end edge of the large-diameter portion 2c, and extends in a direction (the horizontal direction in FIG. 1) orthogonal to the vertical direction (center line C) of the case 2. The stepped portion 2b has a disk shape with a circular hole 2d at the center when viewed from the vertical direction of the case 2. This hole 2d functions as an opening that connects the space of the small-diameter portion 2a and the space of the large-diameter portion 2c. Thus, the outer shell of the canister 1 of the present embodiment is composed of the case 2 (small-diameter portion 2a, stepped portion 2b, large-diameter portion 2c), the bypass chamber 40, and the cover 9.

[0023] The internal space of the case 2 is formed by the inner peripheral surfaces of the small-diameter portion 2a and the large-diameter portion 2c of the case 2, the lower surface of the stepped portion 2b of the case 2, the lower surface of the bypass chamber 40 (the lower surface in FIG. 1), and the upper surface of the cover 9 (the upper surface in FIG. 1). In the present embodiment, from the upper part to the middle part of this internal space, it is separated into two chambers by the first partition wall 8 extending downward from the lower surface of the bypass chamber 40 (the lower surface of the bottom surface portion 42 described later).

[0024] Hereinafter, of the two chambers, one chamber (the left chamber in FIG. 1) is called the first chamber 10, and the other chamber (the right chamber in FIG. 1) is called the second chamber 20 (the right chamber in FIG. 1). The first chamber 10 and the second chamber 20 are arranged adjacent to each other with the first partition wall 8 interposed therebetween. The first partition wall 8 of the present embodiment is provided as a surface portion including the center line C of the case 2, but it may be provided offset from the center line C. Also, the first partition wall 8 may be a flat portion extending in the vertical direction of the case 2, or a curved surface portion having a uniform cross section in the vertical direction of the case 2. In the canister 1 shown in FIG. 1, the lower end portion of the first partition wall 8 is located at the vertical middle portion of the large-diameter portion 2c, but the lower end portion of the first partition wall 8 may be further below the illustrated position.

[0025] The first chamber 10 is a chamber that houses the first adsorbent 6A and to which the tank port 3 is connected. In this embodiment, the first chamber 10 is formed by a part of the bottom surface 42 of the bypass chamber 40 (the left part in Figure 1), a part of the case 2 (the left outer shape in Figure 1), the first partition wall 8 and a virtual interface extending from it to the cover 9, and a part of the cover 9 (the left part in Figure 1).

[0026] On the other hand, the second chamber 20 is a chamber that houses the second adsorbent 6B and to which the purge port 4 is connected. In this embodiment, the second chamber 20 is formed by the other part of the bottom surface 42 of the bypass chamber 40 (the right-hand part in Figure 1), a part of the case 2 (the right-hand outer shape in Figure 1), the first partition wall 8 and a virtual interface extending from it to the cover 9, and the other part of the cover 9 (the right-hand part in Figure 1). An air inlet 7 is provided in the second chamber 20.

[0027] The following provides further details about Room 10 and Room 20. The first chamber 10 forms a first connecting space 11, which is part of the internal space of the small-diameter portion 2a of case 2 (the space on the left in Figure 1), and a first housing space 12, which is part of the internal space of the large-diameter portion 2c of case 2 (the space on the left in Figure 1). In other words, the internal space of the first chamber 10 is composed of these two spaces 11 and 12.

[0028] The first connection space 11 is a space that connects the tank port 3 and the first storage space 12. In this embodiment, the first connection space 11 is semi-cylindrical in shape. The first containment space 12 is a space that communicates with the tank port 3 via the first connection space 11 and contains the first adsorbent 6A. In other words, the adsorbent 6 contained in the first containment space 12 is the first adsorbent 6A. The first containment space 12 is the part of the internal space of the first chamber 10 excluding the first connection space 11. Inside the first containment space 12, in addition to the first adsorbent 6A, first filters 13t and 13b are provided so as to sandwich the first adsorbent 6A from above and below. The shapes of the first adsorbent 6A and the first filters 13t and 13b correspond to the shape of the first containment space 12.

[0029] The second chamber 20 forms a second connecting space 21, which is part of the internal space of the small-diameter portion 2a of case 2 (the space on the right in Figure 1), and a second accommodating space 22, which is part of the internal space of the large-diameter portion 2c of case 2 (the space on the right in Figure 1). In other words, the internal space of the second chamber 20 is composed of these two spaces 21 and 22.

[0030] The second connection space 21 is the space that connects the bypass chamber 40 and the purge port 4. The second connection space 21 in this embodiment is also semi-cylindrical in shape. The second containment space 22 is a space that communicates with the purge port 4 via the second connection space 21 and contains the second adsorbent 6B. In other words, the adsorbent 6 contained in the second containment space 22 is the second adsorbent 6B. Although the first adsorbent 6A and the second adsorbent 6B are located in different chambers, their functions and materials are the same. The second containment space 22 is the part of the second chamber 20 that is obtained by removing the second connection space 21. Inside the second containment space 22, in addition to the second adsorbent 6B, second filters 23t and 23b are provided so as to sandwich the second adsorbent 6B from above and below. The shapes of the second adsorbent 6B and the second filters 23t and 23b correspond to the shape of the second containment space 22.

[0031] In this embodiment, the tank port 3 is provided on the side of the small-diameter section 2a (the left side in Figure 1), opening the first connection space 11 to the outside of the case 2. The tank port 3 is positioned so as to overlap with the stepped section 2b when viewed from above. The purge port 4 in this embodiment is provided on the side of the small-diameter section 2a (the right side in Figure 1), opening the second connection space 21 to the outside of the case 2. The purge port 4 is also positioned so as to overlap with the stepped section 2b when viewed from above. The tank port 3 and the purge port 4 communicate with each other via adsorbent materials 6A and 6B, or via the bypass space 41.

[0032] In this embodiment, the air inlet 7 is provided on the upper surface of the portion of the stepped section 2b that forms the second chamber 20, opening the second containment space 22 to the outside of the case 2. Gas (gas from which evaporated fuel has been removed) that flows in from the tank port 3 and passes through the adsorbent 6 flows out from the air inlet 7. Furthermore, outside air is drawn into the case 2 from the outside through the air inlet 7. The tank port 3 and the air inlet 7 are in communication with each other via the first adsorbent 6A and the second adsorbent 6B, or via the bypass space 41, the second connection space 21 and the second adsorbent 6B. Also, the bypass chamber 40 (bypass space 41) and the air inlet 7, and the purge port 4 and the air inlet 7 are in communication with each other via the second connection space 21 and the second adsorbent 6B, respectively. In the canister 1 of this embodiment, the second filter 23t is positioned in contact with the air inlet 7. Note that in Figure 1, for convenience, the cross-sections of the tank port 3, the purge port 4 and the air inlet 7 are shown in a single figure. The layout of each port 3, 4 and the air outlet 7 does not necessarily have to be set to be located on the same plane; they may be offset as appropriate.

[0033] As described above, the first partition wall 8 is a wall member that separates the first chamber 10 and the second chamber 20. The first partition wall 8 has the function of increasing the distance that the vaporized gas flowing in from the tank port 3 passes through the adsorbents 6A and 6B by partitioning the space where the adsorbent 6 is placed (the space of the large diameter section 2c) from its upper end to the middle in the vertical direction. Furthermore, the first partition wall 8 in this embodiment also has the function of preventing the vaporized gas flowing in from the tank port 3 from directly flowing out from the purge port 4 or the air outlet 7 by completely partitioning the space where the adsorbent 6 is not placed (the space of the small diameter section 2a and the space where the filters 13t and 23t are placed) in the vertical direction.

[0034] The first partition wall 8 partially partitions the inside of the case 2 while maintaining the communication between the tank port 3 and the air outlet 7, which are in communication with each other via the first adsorbent 6A and the second adsorbent 6B. In other words, the first partition wall 8 is provided so as not to obstruct the communication between the tank port 3 and the air outlet 7. As described above, the first partition wall 8 in this embodiment is set to a length such that it completely partitions the first connection space 11 and the second connection space 21, while not completely partitioning the first accommodation space 12 and the second accommodation space 22. That is, the length of the first partition wall 8 should be such that it completely partitions the first connection space 11 and the second connection space 21, which are located adjacent to each other, and partially partitions the first accommodation space 12 and the second accommodation space 22, which are located adjacent to each other.

[0035] In the canister 1 of this embodiment, the lower end of the first partition wall 8 is located in the middle of the large diameter section 2c in the vertical direction, so the lower part of the first adsorbent 6A and the lower part of the second adsorbent 6B are in surface contact (or integrated) with each other. For this reason, although the vaporized gas flowing in from the tank port 3 can flow through the adsorbents 6A and 6B, a communication section 32 is provided at the lower end of the case 2, forming a communication space 31 that connects the first chamber 10 and the second chamber 20. The communication section 32 is, for example, a hollow cylindrical member, and forms a communication space 31 connecting the first containment space 12 and the second containment space 22 inside it. The communication section 32 is provided across both the first chamber 10 and the second chamber 20, and its upper surface is in surface contact with the lower surface (the lower surface in Figure 1) of the first filter 13b and the second filter 23b, and the cover 9 is in surface contact with its lower surface. Multiple through-holes are provided on the upper surface of the communication section 32. These through-holes connect the first containment space 12 (first chamber 10) to the communication space 31, and also function as passages connecting the communication space 31 to the second containment space 22 (second chamber 20). No adsorbent material or filter is placed inside the communication section 32.

[0036] According to the above configuration, for example, evaporated fuel contained in the vaporized gas flowing into case 2 from tank port 3 can be temporarily adsorbed by adsorbents 6A and 6B contained in the first containment space 12 and second containment space 22. Furthermore, when the engine is running, the evaporated fuel adsorbed on adsorbent 6 can be desorbed from adsorbent 6 by outside air flowing in from atmospheric port 7 in response to the engine's negative pressure (or when the purge valve is opened) and passing through adsorbent 6, and can be introduced into the engine's intake system from purge port 4. Hereinafter, the flow path through which the evaporated fuel flows in this case will be referred to as the "normal flow path." That is, the normal flow path means a flow path in which tank port 3 and purge port 4 are connected via adsorbent 6.

[0037] [2.Main part configuration] Figure 2 is a cross-sectional perspective view showing the main components of the canister 1 in Figure 1 (bypass chamber 40 and valve 5, etc.). Note that in Figure 2, the stepped portion 2b of the case 2 and the portion below it are not shown, and only the portion of the first partition wall 8 located within the small diameter portion 2a of the case 2 is shown.

[0038] In this embodiment, the canister 1 is provided with a bypass channel R, indicated by a thick arrow in Figure 2. Unlike the normal channel described above, the bypass channel R bypasses the adsorbent 6. The bypass channel R allows the vaporized gas flowing in from the tank port 3 to flow out from the purge port 4 without passing through the adsorbent 6. The bypass chamber 40 constitutes a part of this bypass channel R.

[0039] The bypass chamber 40 shown in this embodiment is a chamber that forms a bypass space 41 that connects the first connection space 11 and the second connection space 21 by bypassing the adsorbent material 6 (i.e., the first containment space 12 and the second containment space 22). In addition to functioning as a chamber that forms the bypass space 41, the bypass chamber 40 in this embodiment also functions as a cover member that forms part of the outer shell of the canister 1.

[0040] The bypass chamber 40 in this embodiment is cylindrical with a center line C and has approximately the same outer diameter as the small diameter portion 2a. The bypass chamber 40 has a disc-shaped bottom portion 42 and top portion 44, and a cylindrical side portion 43 connecting the periphery of the bottom portion 42 and the periphery of the top portion 44. The bottom portion 42 is the upper surface of the first chamber 10 (first connection space 11) and the second chamber 20 (second connection space 21). The bypass space 41 is a cylindrical space formed by the top surface of the bottom portion 42, the inner circumferential surface of the side portion 43, and the bottom surface of the top portion 44. The bypass chamber 40 is provided separately from the case 2 and added later.

[0041] The bypass chamber 40 has a first communication hole 45 that penetrates the bottom surface 42 and connects the bypass chamber 40 (bypass space 41) to the first chamber 10 (first connection space 11), and a second communication hole 46 that penetrates the bottom surface 42 and connects the bypass chamber 40 (bypass space 41) to the second chamber 20 (second connection space 21). In other words, the bottom surface 42 is provided with a first communication hole 45 and a second communication hole 46 that penetrate in the vertical direction. The first communication hole 45 is provided in the part of the bottom surface 42 that forms the upper surface of the first chamber 10, and the second communication hole 46 is provided in the part of the bottom surface 42 that forms the upper surface of the second chamber 20. In other words, the bypass space 41 is a space that connects the first connection space 11 of the first chamber 10 and the second connection space 21 of the second chamber 20 without going through the first accommodation space 12 and the second accommodation space 22.

[0042] In this embodiment, the canister 1 is equipped with a bypass chamber 40, thereby forming a "bypass flow path R" with a part of the first connection space 11, the bypass space 41, and a part of the second connection space 21. In other words, the first connection space 11 can be said to be a space that connects the tank port 3 and the bypass chamber 40 and also serves as a part of the bypass flow path R. Similarly, the second connection space 21 can be said to be a space that connects the bypass chamber 40 and the purge port 4 and also serves as a part of the bypass flow path R.

[0043] With the canister 1 having the bypass passage R formed in this way, the evaporated fuel contained in the vaporized gas flowing from the tank port 3 into the case 2 can be directly (without passing through the adsorbent 6) from the first connection space 11 to the second connection space 21 via the bypass space 41. In this case, the vaporized gas is introduced directly (without passing through the adsorbent 6) into the engine's intake system from the purge port 4 connected to the second connection space 21 in response to the negative pressure in the intake system (or when the purge valve is opened).

[0044] The flow area of ​​the bypass space 41, which forms part of the bypass flow path R, is larger than the flow area of ​​the tank port 3. The former "flow area" refers to the area of ​​the surface cut in a direction perpendicular to the flow direction of the vaporized gas flowing through the bypass flow path R within the bypass space 41. For example, the area of ​​the surface cut along the dashed line (shown in three places in Figure 2) drawn perpendicular to the bypass flow path R (thick arrow) in Figure 2 is the former flow area. The flow area of ​​the bypass space 41 may change depending on the location within the bypass space 41. On the other hand, the latter "flow area" refers to the area of ​​the surface cut in a direction perpendicular to the extension direction of the tank port 3 (horizontal direction in Figure 2). The flow area of ​​the bypass space 41 is larger than the flow area of ​​the tank port 3 at any location.

[0045] In the canister 1 of this embodiment, the flow area of ​​at least one of the bypass flow paths R, specifically the flow path through the first connection space 11 and the flow path through the second connection space 21, is larger than the flow area of ​​the tank port 3. The former "flow area" refers to the area of ​​the surface obtained by cutting the bypass flow path R in the first connection space 11 and the bypass flow path R in the second connection space 21 in a direction perpendicular to the flow direction of the vaporized gas flowing through them, similar to the flow area of ​​the bypass space 41 described above. For example, the area of ​​the surface obtained by cutting along the dashed line drawn perpendicular to the bypass flow path R (thick arrow) in Figure 2 is the former flow area. In this embodiment, as shown in Figure 2, the flow area of ​​the bypass flow path R excluding the first communication hole 45 and the second communication hole 46 is larger than the flow area of ​​the tank port 3.

[0046] As described above, the bypass chamber 40 is provided with a valve 5 that opens the bypass flow path R only when predetermined conditions are met. The valve 5 shown in this embodiment is positioned to close the first communication hole 45 of the bypass chamber 40, as shown in Figures 1 and 2. The valve 5 is provided so as to be switchable between an open state, in which the first communication hole 45 (i.e., the bypass flow path R) is open, and a closed state, in which it is closed. When the valve 5 is in the closed state, the first communication hole 45 is completely blocked, so the bypass flow path R does not function (evaporative gas does not flow through the bypass flow path R). On the other hand, when the valve 5 is in the open state, the first communication hole 45 is opened, so the bypass flow path R opens, and evaporative gas flows through the bypass flow path R.

[0047] The predetermined conditions (the conditions under which valve 5 is in an open state) include at least the following condition C1 being met. Condition C1: The internal pressure of the fuel tank is in a high-pressure state, exceeding the first threshold. The first threshold is used to determine whether the fuel tank is under high pressure, and it is at least higher than atmospheric pressure. The first threshold is set to an internal pressure value at which vaporized gas does not leak out from the atmospheric inlet 7, even when the bypass channel R is closed. This first threshold is predetermined, for example, through experiments or analysis.

[0048] When the predetermined condition is that condition C1 is met, if the internal pressure of the fuel tank rises and exceeds the first threshold (when it becomes a high-pressure state), valve 5 opens and the bypass passage R is opened. This prevents the vaporized gas from flowing into the adsorbent 6 at a high flow rate and causes it to flow out from the purge port 4, thereby suppressing leakage from the atmospheric outlet 7.

[0049] Furthermore, the above-mentioned predetermined conditions may also be that both the above-mentioned condition C1 and the following condition C2 are satisfied. Condition C2: The intake system pressure is below the second threshold, which is lower than atmospheric pressure. The second threshold is used to determine whether the intake system pressure is lower than atmospheric pressure, creating a negative pressure state, and is predetermined, for example, through experiments or analysis.

[0050] When condition C2 is included in the predetermined conditions, even if the internal pressure of the fuel tank rises and exceeds the first threshold (high pressure state), valve 5 will not open if the negative pressure of the intake system is small (close to atmospheric pressure), and the vaporized gas will flow through the normal passage. Also, when condition C2 is included in the predetermined conditions, even if the negative pressure of the intake system is large, valve 5 will not open unless the fuel tank is in a high-pressure state, and the vaporized gas will flow through the normal passage. In other words, when condition C2 is added to the predetermined conditions, valve 5 opens in accordance with the differential pressure determined by both condition C1 regarding the internal pressure of the fuel tank and condition C2 regarding the negative pressure of the intake system, and the bypass passage R is opened. Furthermore, when condition C2 is added, in the case of a configuration without a purge valve, when valve 5 opens, vaporized gas will always flow out from the purge port 4, suppressing blow-by from the atmospheric outlet 7. On the other hand, in the case of a configuration equipped with a purge valve, the purge valve opens in conjunction with the opening of valve 5, regardless of whether condition C2 is present or not, and as a result, the vaporized gas that has passed through the bypass flow path R flows out from the purge port 4.

[0051] As shown in Figure 2, the valve 5 in this embodiment is a mechanical valve. The valve 5 is, for example, a ball valve or a gate valve, and has a valve body 5A, a support member 5B that supports the valve body 5A, and a biasing member 5C that applies a biasing force to the valve body 5A. The valve body 5A, support member 5B, and biasing member 5C are all arranged in the bypass chamber 40 and close the first communication hole 45 from the bypass chamber 40 side.

[0052] The valve body 5A is formed to a size larger than the diameter of the first communication hole 45 and closes the first communication hole 45 by being pressed against it (i.e., in the direction of gravity). The support member 5B is formed in a hollow cylindrical shape and fixed to the upper surface (lower surface of the upper surface portion 44) and lower surface (upper surface of the bottom surface portion 42) of the bypass chamber 40, and movably supports the valve body 5A between a closed state and an open state. The support member 5B extends directly above (on the extension line of) the first communication hole 45, and its inner diameter is equal to or slightly larger than the diameter of the valve body 5A, and greater than or equal to the inner diameter of the first communication hole 45. The support member 5B has a notch portion 5D (or a plurality of through holes not shown, instead of or in addition to the notch portion 5D) so as not to obstruct the flow of vaporized gas flowing in from the first communication hole 45.

[0053] The biasing member 5C is a member that exerts a biasing force to maintain the valve body 5A in a closed state. The biasing member 5C is installed inside the support member 5B so as to be expandable and contractible (vertically) along the support member 5B, with one end fixed to the valve body 5A and the other end fixed to the lower surface of the upper surface portion 44. The biasing force of the biasing member 5C is set to a value such that the valve body 5A will be in an open state only when the above predetermined conditions are met. In other words, the biasing force of the biasing member 5C is such that the valve body 5A can continue to be biased towards the closed state when the predetermined conditions are not met. Thus, the valve 5 of this embodiment switches between an open state and a closed state depending on whether the predetermined conditions are met or not by appropriately setting the biasing force of the biasing member 5C. Note that the valve 5 shown in Figure 1 is in the closed state, and the valve 5 shown in Figure 2 is in the open state.

[0054] As shown in Figure 1, Case 2 of this embodiment further includes a second partition wall 24 that partially partitions the second containment space 22 while maintaining the communication between the bypass chamber 40 and the air outlet 7, which are in communication with each other via the second adsorbent 6B. The second partition wall 24 of this embodiment extends from the lower surface of the stepped portion 2b (for example, the edge of the hole 2d) to below the lower end of the first partition wall 8. The second partition wall 24 has the function of preventing direct leakage from the air outlet 7 even if vaporized gas flowing from the bypass chamber 40 into the second chamber 20 (second connection space 21) flows into the second containment space 22 side without flowing out from the purge port 4.

[0055] In this embodiment, the second partition wall 24 completely separates the space where the adsorbent 6 is not placed (in this embodiment, the space where the second filter 23t is placed in the second connection space 21 and the second containment space 22) from the air inlet 7 in the vertical direction. Furthermore, the second partition wall 24 in this embodiment extends from the upper end to near the lower end of the second adsorbent 6B. This increases the distance that the evaporated gas that has flowed from the bypass chamber 40 into the second containment space 22 travels to the air inlet 7 (the distance it passes through the second adsorbent 6B).

[0056] The second partition wall 24 should have a shape that does not obstruct communication between the bypass chamber 40 and the air inlet 7. For example, the second partition wall 24 may be a flat portion extending in the vertical direction of the case 2, or a curved portion having a uniform cross-section in the vertical direction of the case 2. The second partition wall 24 should have a length that completely divides the space in which the second filter 23t is placed into two, and partially divides the space in which the second adsorbent 6B is placed.

[0057] [3. Effect] In the canister 1 described above, the only inlet for the vaporized gas to flow into case 2 is the tank port 3, but there are two outlets for the gas to flow out of case 2: the purge port 4 and the air outlet 7. Furthermore, the flow path from the inlet (tank port 3) to the outlet (purge port 4 or air outlet 7) can be broadly divided into two parts: the normal flow path and the bypass flow path R.

[0058] When valve 5 is closed, the vaporized gas flowing in from the inlet normally passes through the flow path. That is, the vaporized gas flows from the tank port 3 into the first connection space 11, flows into the first containment space 12 which is in communication with it, passes through the first adsorbent 6A, and flows through the portion below the first partition wall 8 to the second adsorbent 6B in the second containment space 22. As a result, the evaporated fuel contained in the vaporized gas is temporarily captured by the adsorbent 6, and the remaining gas flows out from the air outlet 7, which is the outlet. Also, when the negative pressure in the intake system becomes large (for example, when the engine is operating under high load, when purge control is performed on the engine side, or when the purge valve is opened), outside air flows in from the air outlet 7, and the evaporated fuel that was captured by the adsorbent 6 is introduced into the intake system along with the outside air. Depending on the magnitude of the negative pressure in the intake system, the gas that has passed through the adsorbents 6A and 6B may flow out from the purge port 4 instead of the air outlet 7.

[0059] When valve 5 is open, the vaporized gas flowing in from the inlet flows through the bypass channel R instead of the normal channel. This is because the bypass channel R has less resistance than the normal channel. In this case, the vaporized gas flows from the tank port 3 through the first connection space 11, through the first communication hole 45 into the bypass space 41, and then flows out through the second connection space 21 via the second communication hole 46 and out through the purge port 4. Depending on the magnitude of the negative pressure in the intake system, the vaporized gas may not flow out of the purge port 4, but even in that case, the vaporized gas will not flow out of the air outlet 7 until it has passed through at least the second adsorbent 6B.

[0060] [4. Effects] (1) The canister 1 described above is provided with a valve 5 that opens the bypass passage R only when predetermined conditions are met, including the internal pressure of the fuel tank being in a high-pressure state exceeding a first threshold. That is, the bypass passage R is opened only when predetermined conditions such as the internal pressure of the fuel tank being in a high-pressure state exceeding a first threshold (condition C1) are met. As a result, when high-pressure (high-concentration) vaporized gas flows into the canister 1, the vaporized gas flows directly to the purge port 4 through the bypass passage R (without passing through the adsorbent 6). In other words, when the fuel tank is in a high-pressure state, it is possible to create a condition in which vaporized gas can flow directly from the tank port 3 to the purge port 4 without passing through the adsorbent 6. Therefore, the blow-out of evaporated fuel into the atmosphere can be suppressed.

[0061] Furthermore, the canister 1 described above is provided with a bypass space 41 having a larger flow area than the flow area of ​​the tank port 3, and when the valve 5 is opened, the vaporized gas flows through this bypass space 41. In other words, the high-pressure (high-concentration) vaporized gas that enters the case 2 from the tank port 3 is first passed through the bypass space 41, thereby equalizing the pressure (concentration) of the vaporized gas within the bypass space 41 before it can be discharged from the purge port 4. Therefore, it is possible to eliminate the non-uniformity of the vaporized gas introduced into the intake system. Thus, the canister 1 described above can eliminate the non-uniformity of the vaporized gas introduced into the intake system and suppress the leakage of vaporized gas into the atmosphere.

[0062] Furthermore, when high-pressure (high-concentration) vaporized gas flows into the bypass space 41, the pressure of the vaporized gas decreases, and the flow rate of the vaporized gas also decreases, and in this state it flows into the second connection space 21. Therefore, even if the vaporized gas that flows from the tank port 3 into the bypass space 41 flows to the atmospheric outlet 7 without flowing out from the purge port 4, the evaporated fuel is more easily adsorbed by the adsorbent 6, and the leakage of evaporated fuel into the atmosphere can be suppressed.

[0063] (2) In the canister 1 described above, if the predetermined conditions for valve 5 to open the bypass passage R include the above condition C2, the blow-out of evaporated gas into the atmosphere can be further suppressed. This is because, even if the internal pressure of the fuel tank is high, if the pressure of the intake system is close to atmospheric pressure (when the pressure of the intake system is above the second threshold), gas is less likely to flow out of the purge port 4. In other words, by including condition C2 regarding the negative pressure of the intake system in the predetermined conditions, when the negative pressure is small, the high-pressure evaporated gas is directed to the normal passage instead of the bypass passage R, thereby enhancing the effect of suppressing the blow-out of evaporated gas into the atmosphere. Furthermore, by opening valve 5 only when the predetermined conditions are met (when both conditions C1 and C2 are satisfied), it becomes possible to direct the evaporated gas that has flowed through the bypass passage R directly to the purge port 4. Therefore, regardless of which passage the evaporated gas passes through, the blow-out of evaporated fuel into the atmosphere can be suppressed.

[0064] (3) In the canister 1 described above, a mechanical valve 5 is used instead of a solenoid valve to open the bypass passage R. This simplifies the configuration compared to the case where a solenoid valve is used, and also reduces product costs because a power source is not required.

[0065] (4) In the canister 1 described above, a first partition wall 8 is provided separating the first chamber 10 and the second chamber 20 so as to connect the tank port 3 and the air outlet 7 via the adsorbent 6. This allows the vaporized gas flowing in from the tank port 3 to pass through both the first adsorbent 6A and the second adsorbent 6B. For example, when the internal pressure of the fuel tank is about to reach a first threshold (such as just before a predetermined condition is met), the bypass passage R is not opened. However, even in such a case, when the vaporized gas flows through the normal passage, the evaporated fuel is more easily adsorbed by the adsorbent 6, and the leakage of evaporated fuel into the atmosphere can be suppressed.

[0066] (5) In the canister 1 described above, the first connection space 11 and the second connection space 21 each serve as part of the bypass flow path R, and the flow path area of ​​at least one of the bypass flow path R, the flow path through the first connection space 11 and the flow path through the second connection space 21, is larger than the flow path area of ​​the tank port 3. When the flow path area of ​​the flow path through the first connection space 11 is larger than the flow path area of ​​the tank port 3, the high-pressure (high-concentration) vaporized gas that enters the case 2 from the tank port 3 is homogenized by passing through the first connection space 11.

[0067] Furthermore, if the flow path area of ​​the channel passing through the second connection space 21 is larger than the flow path area of ​​the tank port 3, the vaporized gas, whose pressure (concentration) has been homogenized in the bypass space 41, will be further homogenized by passing through the second connection space 21. In this way, the pressure (concentration) of the vaporized gas can be further homogenized not only in the bypass space 41 but also in the first connection space 11 and / or the second connection space 21 before being discharged from the purge port 4. Therefore, the non-uniformity of the vaporized gas introduced into the intake system can be further eliminated.

[0068] Furthermore, as the vaporized gas passes through the first connection space 11 and / or the second connection space 21, which are larger than the flow path area of ​​the tank port 3, the pressure of the vaporized gas decreases, and the flow rate also decreases. Therefore, even if the vaporized gas that flows from the tank port 3 to the bypass space 41 flows to the air outlet 7 without flowing out from the purge port 4, the evaporated fuel is more easily adsorbed by the adsorbent 6, further suppressing the leakage of evaporated fuel into the atmosphere.

[0069] (6) In the canister 1 described above, a second partition wall 24 is provided that partially partitions the second containment space 22. As a result, even if the vaporized gas that has flowed from the bypass chamber 40 to the second chamber 20 does not flow out from the purge port 4, the vaporized gas can pass through the second adsorbent 6B before flowing to the air outlet 7. Therefore, the non-uniformity of the vaporized gas introduced into the intake system can be eliminated, and the blow-through of evaporated fuel into the atmosphere can be further suppressed.

[0070] [5. Variant] The canister 1 described above is just one example and is not limited to that described above. In the embodiment described above, a case in which a second partition wall 24 is provided in case 2 is shown as an example, but the second partition wall 24 is not essential and can be omitted, and the configuration for preventing direct leakage of evaporative gas from the air inlet 7 is not limited to that described above. For example, instead of (or in addition to) the second partition wall 24, a rib 25 extending from the edge of the air inlet 7 to the second adsorbent 6B may be provided in the second chamber 20, as shown in canister 1' in Figure 3. The rib 25 is cylindrical, having the same shape as the air inlet 7 and a length that reaches at least the second adsorbent 6B, and is provided in case 2.

[0071] The rib 25 shown in Figure 3 protrudes downward from the lower surface of the stepped portion 2b of case 2 (the surface facing the second filter 23t). The rib 25 penetrates the second filter 23t vertically and extends to the upper end of the second adsorbent 6B, maintaining communication between the bypass chamber 40 and the air outlet 7, which are in communication with each other via the second adsorbent 6B, while preventing evaporative gas from flowing out without passing through the second adsorbent 6B. Similar to the second partition wall 24 described above, the rib 25 has the function of preventing evaporative gas flowing from the bypass chamber 40 into the second chamber 20 from flowing out directly from the air outlet 7.

[0072] Thus, in the canister 1' according to this modified example, since the second chamber 20 is provided with a rib 25 extending from the edge of the air inlet 7 to the second adsorbent 6B, even if the vaporized gas flowing from the bypass chamber 40 into the second chamber 20 does not flow to the purge port 4, the vaporized gas can pass through the second adsorbent 6B before flowing to the air inlet 7. Therefore, it is possible to eliminate the non-uniformity of the vaporized gas introduced into the intake system while further suppressing the blow-through of evaporated fuel into the atmosphere. In addition, the rib 25 extending from the edge of the air inlet 7 can increase the strength around the air inlet 7 (the strength of case 2).

[0073] In the canister 1' shown in Figure 3, the configuration of the first partition wall 8 has also been changed from the configuration described above. Specifically, the first partition wall 8' shown in Figure 3 is set to a length that completely partitions the internal space of the case 2 in the vertical direction, from the lower surface of the bypass chamber 40 to the upper surface of the communication section 32. With such a first partition wall 8' provided, the vaporized gas flowing through the normal flow path will pass through the first adsorbent 6A from its upper end to its lower end, and then flow through the communication section 32 to the second adsorbent 6B, thus making it easier to replenish evaporated fuel. In the case of canister 1' in which a rib 25 is provided instead of the second partition wall 24, it is preferable to provide the first partition wall 8'.

[0074] [6. Others] Regarding the predetermined conditions described above, it is sufficient that at least condition C1 is met, and condition C2 is not a mandatory condition. Furthermore, although the valve 5 described above is exemplified as a mechanical valve, any valve that opens the bypass passage R only when the predetermined conditions are met is acceptable, and may be, for example, a solenoid valve. If a solenoid valve is provided, the first and second threshold values ​​described above may be fixed values, or they may be variable values ​​set according to the state of the vehicle or the state of various devices mounted on the vehicle. If the two threshold values ​​are variable values, that is, if the predetermined conditions themselves can change, it is conceivable that a controller that controls the solenoid valve may detect the state of the vehicle, set the predetermined conditions, and determine whether the predetermined conditions are met, and open the solenoid valve only when the predetermined conditions are met. Note that the valve that opens and closes the bypass passage R only needs to be located within the bypass chamber 40 and is not limited to a configuration that closes the first communication hole 45. For example, it may be a valve equipped with a valve body capable of closing the entire bypass passage R within the bypass chamber 40 as shown in Figure 1, or a valve equipped with a valve body that closes the second communication hole 46.

[0075] The air vent 7 only needs to be an opening that can be opened to the atmosphere, and does not have to be an opening directly formed on the side of the case 2 (for example, the stepped portion 2b). For example, the air vent may be formed by an air port or piping material, etc., with a hole formed on the side of the case 2, one end of which is connected to the hole, and the other end of which is open to the atmosphere. Furthermore, although the bypass chamber 40 described above is provided separately from the case 2 as an example, the bypass chamber 40 only needs to have the function of forming a bypass space 41, and for example, the bypass chamber 40 may be integrally formed with the case 2 so that it is composed of a part of the case 2.

[0076] Furthermore, although the case 2 described above illustrates the case in which a communication section 32 is provided inside, the communication section 32 is not an essential component. In the canister 1 described above, the first partition wall 8 does not completely separate the first chamber 10 and the second chamber 20 (the first chamber 10 and the second chamber 20 are in communication), so the communication section 32 may be omitted. In this case, filters 13b and 23b can be omitted. On the other hand, in the canister 1' described above, the first partition wall 8' completely separates the first chamber 10 and the second chamber 20, so a configuration that connects the first chamber 10 and the second chamber 20 is necessary, such as a communication section 32 having a communication space 31.

[0077] The configuration of the first chamber 10 and the second chamber 20 of canister 1,1' described above is just one example. For example, the first connecting space 11 and the second connecting space 21 do not have to be semi-cylindrical in shape, and one or both of these connecting spaces 11 and 21 may be omitted. Also, case 2 of canister 1,1' does not have to be a configuration with two chambers, the first chamber 10 and the second chamber 20, but may be a configuration with three or more chambers. [Industrial applicability]

[0078] This technology is applicable to the manufacturing industry of canisters attached to engines, and to the manufacturing industry of vehicles equipped with engines and canisters. It is also applicable to the manufacturing industry of industrial machinery and power generation equipment equipped with engines and canisters. [Explanation of Symbols]

[0079] 1,1' Canister 2 cases 3 Tank Ports 4 Purge Ports 5 valves 6. Adsorbent 6A First adsorbent 6B Second Adsorbent 7. Air vent 8,8′ First bulkhead 10 Room 1 11. First connection space 12. First Containment Space 20 Second room 21 Second Connection Space 22 Second Containment Space 24 Second bulkhead 25 Ribs 40 Bypass Room 41 Bypass space R Bypass Channel

Claims

1. An adsorbent having the ability to adsorb evaporated fuel generated in the fuel tank, A case containing the aforementioned adsorbent, The case and the fuel tank are connected, and a tank port through which vaporized gas containing the evaporated fuel flows in from the fuel tank, A purge port is provided that connects the aforementioned case to the engine's intake system and communicates with the tank port via the adsorbent material, The case is provided with an air port for releasing the gas that has passed through the adsorbent into the atmosphere, A bypass chamber that forms a bypass space which is part of a bypass channel connecting the tank port and the purge port so as to bypass the adsorbent, The bypass chamber includes a valve that opens the bypass passage only when predetermined conditions are met, including the internal pressure of the fuel tank being in a high-pressure state exceeding a first threshold, The flow area of ​​the bypass space is larger than the flow area of ​​the tank port. A canister characterized by the following features.

2. The aforementioned predetermined conditions further include the condition that the pressure of the intake system is below a second threshold, which is lower than atmospheric pressure. The canister according to claim 1, characterized in that

3. The valve is a mechanical valve. A canister according to claim 1 or 2, characterized in that it is a canister.

4. The adsorbent material includes a first adsorbent and a second adsorbent. The aforementioned case is, A first chamber containing the first adsorbent and connected to the tank port, A second chamber is provided, which contains the second adsorbent and is also provided with the purge port and the air vent. It has a first partition wall separating the first chamber and the second chamber, The first chamber and the second chamber are arranged adjacent to each other, separated by the first partition wall. The first partition wall partially divides the inside of the case while maintaining the communication between the tank port and the air outlet, which are in communication with each other via the first and second adsorbents. The canister according to claim 1, characterized in that

5. The first chamber comprises a first connection space that connects the tank port and the bypass chamber and also serves as part of the bypass flow path, and a first containment space that communicates with the tank port via the first connection space and contains the first adsorbent. The second chamber comprises a second connection space that connects the bypass chamber and the purge port and also serves as part of the bypass flow path, and a second containment space that communicates with the purge port via the second connection space and contains the second adsorbent. The first connecting space and the second connecting space are arranged adjacent to each other and are completely separated by the first partition wall. The flow area of ​​at least one of the bypass channels, specifically the channel passing through the first connection space and the channel passing through the second connection space, is larger than the flow area of ​​the tank port. The canister according to claim 4, characterized in that it is a canister.

6. The case has a second partition wall that partially divides the second containment space while maintaining the communication between the bypass chamber and the air outlet, which are in communication with each other via the second adsorbent. The canister according to claim 5, characterized in that

7. The second chamber is provided with ribs extending from the edge of the air outlet to the second adsorbent. The canister according to claim 5, characterized in that

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