JP6485507B2 - Fuel vapor treatment equipment - Google Patents

Description

  The present invention relates to a fuel vapor processing apparatus.

  In the fuel tank of a vehicle, the fuel tank is connected to the atmosphere via a vapor passage connected to the canister, and the fuel vapor generated from the fuel tank is adsorbed by the canister, and the inside of the fuel tank becomes too high in pressure. Is to prevent. The fuel adsorbed by the canister is guided to the intake system of the engine via the purge passage.

  When the purge flow rate increases, abnormal noise may occur due to large pulsations in the fuel tank. To prevent (suppress) this abnormal noise, the valve element is held against the vapor passage. A control valve having a back pressure chamber which is partitioned by a diaphragm and opened to the atmosphere is connected, and the pulsation is suppressed by this control valve.

  Patent Document 1 discloses a configuration in which the back pressure chamber of the control valve is connected to the input portion side of the canister, and a second communication passage 45 that supplies a part of fuel vapor to the back pressure chamber is formed in the diaphragm. Has been.

Japanese Patent Laid-Open No. 2006-166575

  By the way, when the back pressure chamber of the diaphragm type control valve provided in the vapor passage is opened to the atmosphere, the diaphragm cannot completely shut off the fuel vapor. Will escape to the atmosphere.

  In the thing of patent document 1, since a back pressure type is connected to the input part side of a canister, it becomes a preferable thing at the point that the fuel vapor which permeate | transmitted the diaphragm can be adsorb | sucked to a canister. However, in the thing of patent document 1, since the fuel vapor | steam from a fuel tank is positively introduce | transduced into a back pressure chamber and the back pressure chamber is connected to the input part of the canister, The pressure fluctuation is unavoidable, and the pulsation reducing effect by the control valve is reduced.

  On the other hand, recently, the capacity of canisters has been increased so that fuel vapor can be sufficiently adsorbed. However, since a large capacity canister inevitably increases in size, how to secure a space for installing the canister in the vehicle becomes a new problem.

  The present invention has been made in view of the above circumstances, and its purpose is to prevent leakage of fuel vapor to the atmosphere through the back pressure chamber of the control valve, prevention of pressure fluctuations in the back pressure chamber, and a large capacity. It is an object of the present invention to provide a fuel vapor processing apparatus that can satisfy the requirements of increasing the degree of freedom in selecting a canister installation space.

In order to achieve the above object, the following solution is adopted in the present invention. That is, as described in claim 1,
A plurality of canisters are connected in series to a vapor passage communicating with the atmosphere inside the fuel tank,
A control valve for suppressing pulsation having a back pressure chamber defined by a diaphragm holding a valve body is connected to the vapor passage,
The back pressure chamber is connected to a specific position of the vapor passage;
The specific position of the vapor passage is a position between a first canister and a second canister adjacent to each other in the passage direction of the vapor passage among the plurality of canisters.
It is like that.

  According to the above solution, the pressure fluctuation from the fuel tank side is transmitted to the back pressure chamber in a state where the pressure fluctuation is sufficiently reduced through some canisters. The pulsation reduction effect by the control valve is high. Further, a small amount of fuel vapor that has passed through the diaphragm and leaked into the back pressure chamber is adsorbed by another canister and is not released to the atmosphere. Further, even when the canister has a large capacity as a whole, since it has a divided configuration of a plurality of canisters, the degree of freedom in selecting the arrangement position is high (improvement in mounting on a vehicle).

A preferred mode based on the above solution is as described in claim 2 and the following. That is,
The first canister is positioned closer to the fuel tank in the direction of the vapor passage than the second canister;
The capacity of the first canister is larger than the capacity of the second canister;
(Corresponding to claim 2). In this case, the number of canisters can be kept to a minimum while a plurality of canisters are provided. Further, by setting the capacity of the first canister close to the fuel tank to be large, it is preferable for sufficiently exhibiting the effect corresponding to the first aspect described above.

  A purge passage connected to the intake system of the engine is connected to the first canister (corresponding to claim 3). In this case, the purge is performed preferentially from the canister having a large capacity, which is preferable in effectively (effectively) purging.

Three or more canisters are provided,
The specific position is a position between the canister adjacent to the atmosphere side canister located closest to the atmosphere side in the passage direction of the vapor passage among the plurality of canisters,
(Corresponding to claim 4). In this case, the effect corresponding to the first aspect is preferable in order to fully exhibit the effect.

Of the plurality of canisters, the capacity of the canister located closest to the fuel tank in the direction of the vapor passage is made larger than the capacity of other canisters,
A purge passage connected to the intake system of the engine is connected to the canister located closest to the fuel tank.
(Corresponding to claim 5). In this case, the same effects as those corresponding to claims 2 and 3 can be obtained.

  According to the present invention, the fuel vapor through the back pressure chamber is prevented from leaking to the atmosphere, the back pressure chamber is prevented from fluctuating in pressure, and the canister arrangement space is increased when the capacity is increased. Can be satisfied.

The system diagram which shows one Embodiment of this invention and shows the discharge path | route of fuel vapor | steam. Sectional drawing which shows an example of a control valve.

  In FIG. 1, 1 is a fuel tank. The fuel tank 1 is disposed below the rear seat of the vehicle, for example. Fuel is supplied to the fuel tank 1 via the filler pipe 2 (fuel supply).

  A pressure regulating valve 3 is built in the fuel tank 1. When the pressure inside the fuel tank 1 becomes higher than a predetermined pressure, the pressure regulating valve 3 is opened, and fuel vapor is discharged out of the fuel tank 1 through a vapor passage described later. The pressure adjustment valve 3 is of an electromagnetic type, for example, it is opened only during refueling, and closed in other cases (the fuel tank 1 is kept in a sealed state). it can.

  The inside of the fuel tank 1 is opened to the atmosphere via the pressure regulating valve 3 and the vapor passage 10. A main canister 21 and a sub-canister 22 are connected to the vapor passage 10 in series. The main canister 21 is disposed closer to the fuel tank 1 than the sub-canister 22, and the capacity of the main canister 21 is larger than the capacity of the sub-canister 22.

  The vapor passage 10 includes a first passage 11 that connects the fuel tank 1 (pressure regulating valve 3) and the main canister 21 (input portion thereof), an output portion of the main canister 21 and an input portion of the sub-canister 22. It has the 2nd channel | path 12 to connect, and the 3rd channel | path 13 which open | releases the output part of the subcanister 22 to air | atmosphere.

  A diaphragm type control valve 30 (to be described later) and a pressure sensor 41 are connected to the first passage 11 sequentially from the fuel tank 1 side to the main canister 21 side. In addition, a filter 42 for preventing dust intrusion and a failure detection device 43 are sequentially connected to the third passage 13 from the sub-canister 22 side toward the atmosphere side.

  Further, the main canister 21 is connected to a purge passage 15 connected to an engine (not shown). An electromagnetic on-off valve 16 is connected to the purge passage 15. The on-off valve 16 is normally closed and is opened only when purging is performed. It is also possible to connect a separate pump to the purge passage 15 so that the pump can be operated only when purging is performed (the flow of fuel vapor from the main canister 21 toward the engine is formed by the pump).

  FIG. 2 shows an example of the control valve 30. The control valve 30 has a casing 31 having a sealed structure. The casing 31 is partitioned into a back pressure chamber 33 and a flow path chamber 34 by a diaphragm 32. A valve body 32 a is integrally held on the diaphragm 32. The diaphragm 32, that is, the valve body 32 a is urged downward in the figure by a spring 35.

  An outflow cylinder 36 is disposed in the flow path chamber 34 so as to face the valve body 32a. One end portion (upper end portion in the figure) of the outflow cylinder portion 36 is a valve seat portion 36a that is opened and closed (separated and seated) by the valve body 32a. The other end of the outflow cylinder 36 is a connection 36 b to the main canister 21.

  The casing 31 is formed with a connecting portion 34a that is open to the flow path chamber 34, and this connecting portion 34a is connected to the fuel tank 1 (internal pressure regulating valve 3).

  In the casing 31, a connection portion 33 a opened in the back pressure chamber 33 is formed. The connecting portion 33a is connected to the second passage 12 via a communication passage 50 indicated by a broken line in FIG.

  The failure detection device 43 described above detects whether or not the path from the fuel tank 1 to the failure detection device 43 is sealed (the presence or absence of leakage). That is, the failure detection device 43 has an on-off valve and a pressurizing pump, and closes the on-off valve and operates the pressurizing pump to seal the path connected to the fuel tank 1 (for example, The on-off valve 16 is also closed). By checking whether or not the pressure detected by the pressure sensor 41 has fallen by a predetermined value or more within a predetermined time after the inside of the path related to the vapor passage 10 is raised to a predetermined pressure by the pressurizing pump, It is determined whether there is a leak in the route associated with the vapor passage 10. In addition, since such a failure detection apparatus 43 itself is known, further description is abbreviate | omitted.

  In the above configuration, when the on-off valve 16 is closed and purge is not performed, the fuel vapor from the fuel tank 1 is adsorbed by the main canister 21 from the vapor passage 10. After the adsorption amount in the main canister 21 is saturated, the fuel vapor is adsorbed by the sub-canister 22.

  When the amount of fuel vapor adsorbed by the sub-canister 22 exceeds a predetermined value, purging is executed. This purging is performed by opening the on-off valve 16 during engine operation. The purge of the fuel vapor is performed from the main canister 21, and thereafter the sub canister 22 is performed.

  When the purge flow rate is large, a large pulsation is generated in the fuel tank 1 (large pressure change), and abnormal noise (particularly abnormal noise in the pressure regulating valve 3) may be generated. At this time, the control valve 30 suppresses pulsation by the valve body 32a being seated on and away from the valve seat 36a, thereby preventing or suppressing abnormal noise. Since the main canister 21 is interposed between the back pressure chamber 33 and the fuel tank 1, the back pressure chamber 33 is maintained at substantially atmospheric pressure (the pressure fluctuation in the back pressure chamber 33 is very small). The effect of reducing pulsation (abnormal noise) by the control valve 30 can be sufficiently exhibited.

  Although the amount of fuel vapor from the fuel tank 1 is very small, it may pass through the diaphragm 32 and leak into the back pressure chamber 33. However, since the sub-canister 22 exists between the back pressure chamber 33 and the atmosphere, a very small amount of fuel vapor leaking into the back pressure chamber 33 is adsorbed by the sub-canister 22 and released to the atmosphere. There is no.

  Although the capacity of the entire canister is large, since the main canister 21 and the sub-canister 2 are divided, the arrangement position can be selected with a high degree of freedom. For example, the main canister 21 can be disposed near the rear wheel body near the rear wheel house, and the sub-canister 22 can be disposed immediately behind the rear wheel house.

  Although the embodiments have been described above, the present invention is not limited to the embodiments, and appropriate modifications can be made within the scope of the claims. Three or more canisters may be provided. In this case, the specific position where the back pressure chamber 33 is connected in the vapor passage 10 is defined as the position between the canister located closest to the atmosphere in the passage direction of the vapor passage 10 and a canister adjacent thereto. It is preferable to do this. When three or more canisters are provided, the capacity of a specific canister located closest to the fuel tank 1 in the direction of the vapor passage 10 is made larger than that of the other canisters. On the other hand, it is preferable to connect the purge passage 15. Of course, the object of the present invention is not limited to what is explicitly stated, but also implicitly includes providing what is substantially preferred or expressed as an advantage.

  The present invention can be applied to a vehicle in which fuel vapor from a fuel tank is adsorbed by a canister.

1: Fuel tank 3: Pressure adjusting valve 10: Vapor passage 11: First passage 12: Second passage 13: Third passage 15: Purge passage 21: Main canister 22: Sub-canister 30: Control valve 31: Casing 32 : Diaphragm 32a: Valve body 33: Back pressure chamber 33a: Connection portion 34: Channel chamber 34a: Connection portion 35: Spring 36: Outflow cylinder portion 36a: Valve seat portion 36b: Connection portion 50: Communication passage

Claims (5)

A plurality of canisters are connected in series to a vapor passage communicating with the atmosphere inside the fuel tank,
A control valve for suppressing pulsation having a back pressure chamber defined by a diaphragm holding a valve body is connected to the vapor passage,
The back pressure chamber is connected to a specific position of the vapor passage;
The specific position of the vapor passage is a position between a first canister and a second canister adjacent to each other in the passage direction of the vapor passage among the plurality of canisters.
A fuel vapor processing apparatus. In claim 1,
The first canister is positioned closer to the fuel tank in the direction of the vapor passage than the second canister;
The capacity of the first canister is larger than the capacity of the second canister;
A fuel vapor processing apparatus. In claim 2,
A fuel vapor processing apparatus, wherein a purge passage connected to an intake system of an engine is connected to the first canister. In claim 1,
Three or more canisters are provided,
The specific position is a position between the canister adjacent to the atmosphere side canister located closest to the atmosphere side in the passage direction of the vapor passage among the plurality of canisters,
A fuel vapor processing apparatus. In claim 4,
Of the plurality of canisters, the capacity of the canister located closest to the fuel tank in the direction of the vapor passage is made larger than the capacity of other canisters,
A purge passage connected to the intake system of the engine is connected to the canister located closest to the fuel tank.
A fuel vapor processing apparatus.

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