JP3250120B2 - Fuel vapor treatment system for vehicles - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for detecting the presence or absence of a failure in a fuel vapor processing apparatus for a vehicle.

[0002]

2. Description of the Related Art In most vehicles, a check valve v is provided between a fuel tank T and a canister C as shown in FIG.
Are connected through a ventilation passage L ₁ , and the canister C is connected to an intake pipe K of the engine E through a purge passage L _2.
Connected to a purge control valve V controlled by a control unit U and connected to a fuel tank T when the vehicle is stopped or refueled.
The fuel vapor generated within guides with ventilation passage L ₁ to Kiyanisuta C adsorbed by the adsorbent Ca such as activated carbon, controls the control valve V opening by the control unit U according to the operating state of the engine E during running of the vehicle At the same time, the adsorbed fuel in the canister C is sent from the tail end pipe Cb to the intake pipe K under intake of air.

[0003] Then, FIGS if Shimese one check valve v disposed in the middle of the ventilation passage L ₁
The pipe 2 is provided at both ends of the cylindrical case 1.
a cap 2 having a plurality of through-holes 1b is provided in the case 1 and a rubber having a fin 3a and a central through-hole 3b in the center of the partition 1a. The elastic valve element 3 is mounted, and a plate valve 4 having a corrugated projection 4a formed on the peripheral edge of the elastic valve element 3 is provided on the leg end side as shown in FIG. A coil spring 5 is provided between the lower cap 2 and the upper cap 2 and the fuel tank T, and the lower cap 2 is connected to the canister C.

[0004] Therefore, if the vapor pressure within the fuel tank T is more than a certain, its internal pressure is applied to the plate valve 4, which is separated from the elastic valve body 3, the fuel vapor in the tank T is via the ventilation passage L ₁ When the pressure in the tank T becomes negative due to the decrease in fuel or the temperature drop while the fuel flows to the canister C side, the plate valve 4 is pressed against the lower surface of the elastic valve body 3 while the elastic valve body 3 warps. Open the through hole 1b , take in the atmosphere from the tail pipe Cb of the canister C, and ventilate it.
Down passage L ₁ a through feed to the tank T, so that to eliminate the negative pressure state.

[0005]

By the way, in the fuel vapor processing apparatus of the above system, when a large amount of adsorbed fuel is purged as in the case of heavy load and high speed operation of the vehicle, the interior of the canister is purged. Although a large negative pressure may be generated at the connection end side of the ventilation passage of the canister due to the pressure loss based on the charging state, in the above-described conventional fuel vapor processing apparatus, the check valve disposed in the ventilation passage is shown in FIG. In such a case, the negative pressure generated in the canister opens the plate valve and the negative pressure is transmitted to the fuel tank as it is, which may cause damage to the tank.
Further, since the conventional device does not have means for detecting breakage (leakage) of the pipeline, the device may be left with its function deteriorated, which is not preferable in terms of pollution control.

Accordingly, the present invention makes it possible to quickly and accurately detect the presence or absence of a failure of a device when required even if a large negative pressure is generated in a canister without transmitting the negative pressure to a fuel tank. That is the task .

[0007]

SUMMARY OF THE INVENTION In view of the above problems , the present invention provides a fuel vapor processing apparatus for a vehicle, in which, first, a fuel tank and a canister are connected by a ventilation passage while a canister is connected by a purge passage. A body having a first pipe leading to the tank and a second pipe leading to the canister, and a cover having a third pipe in the middle of the ventilation passage connected to a purge control valve attached to the intake pipe and controlled by a control unit. A cylindrical column communicating with the second pipe is provided in the body, and a valve body that opens only to the side of the space between the cylindrical column and the peripheral wall of the body is provided in the communicating portion; a check valve to close the tubular column is disposed by a spring force arranged diaphragm between the atmosphere inside the cover in the middle through the third pipe of the cover Communicates with the or the intake pipe providing communication
While connected to the intake pipe by opening and closing the passage provided with the first switching valve to so that the pipe on the tail pipe Kiyanisuta
A second switching valve for opening and closing is provided, the first and second switching valves are respectively connected to a control unit, and the fuel tank is connected to the control unit via a pressure sensor for detecting an internal pressure. In the meantime, while connecting the fuel tank and canister through the ventilation passage,
A body having a first pipe leading to the tank and a second pipe leading to the canister in the middle of the ventilation passage, and connecting the canister to a purge control valve attached to the intake pipe via a purge passage and controlled by a control unit; A cover having three pipes, a body provided with a cylindrical column communicating with the second pipe in the body, and a valve body configured to open only to the side of the space between the cylindrical column and the body peripheral wall in the communicating portion, A check valve is disposed between the body and the cover so as to close the cylindrical column by a spring force. A third pipe of the cover is opened to the atmosphere and a check valve in the ventilation passage is provided. while the coupling by a bypass passage provided with the first switching valve openable located midway on each side, pipe opening and closing the tail pipe Kiyanisuta The second switching valve is provided, first, second
Connected to the control unit,
The fuel tank is characterized in that it is connected to a control unit via a pressure sensor that detects the internal pressure.

[0008]

[Embodiment] FIG. 1 is illustrates one embodiment of the present invention, the fuel tank T is connected to one end of Kiyanisuta C by ventilation passage L _1, and one end of Kiyanisuta C purge passage arrangement of the points which is connected to the purge control valve V which is controlled by a control unit U through is attached to the intake pipe K of the engine E wire W ₁ by L ₂ is not changed and the conventional device.

By the way, in this embodiment, the upper wall of the fuel tank T is connected a pressure sensor Ps, detects the pressure in the tank, adapted to send the wire W ₄ that information as electrical signals to the control unit U and it has, and in the middle of the ventilation passage L ₁ is disposed a check valve v as described below, the cover 15 of the check valve v
It is connected to the intake pipe K by opening and closing passage L ₃ which is arranged a first switching valve B ₁ in the middle, the first switching valve B ₁ represents are connected by a wire W ₃ with an air intake B _1a in the control unit U Usually, the inside of the cover 15 of the check valve v is communicated with the atmosphere, and at the time of inspection (immediately after the start of the engine or several minutes later, for a few seconds), the control unit U communicates with the intake pipe K. ,
A second switching valve B connected to the control unit U by a wire W ₂ is connected to the tail end pipe Cb of the canister C.
_{2, the} inside of the canister C is normally communicated with the atmosphere, and the control unit U closes the tail end pipe Cb during the above inspection.

The control unit U has a purge control valve V
In addition to controlling the supply amount of the adsorbed fuel in accordance with the operating state of the engine, the inside of the cover 15 of the check valve v immediately after the start of the engine or after a certain period of time (about several minutes) K
The in Kiyanisuta C of to close the tail pipe Cb switching the second switching valve B _2, and after a few seconds with switching the first switching valve B ₁ so as to communicate with the first and second switching valves B _1, B ₂ is set back, and the result of the inspection of the device is received from the pressure sensor Ps, and the result is displayed on an alarm (not shown) in the cab.

[0011] Figure 3, Figure 4 shows the check valve v, 11 is a circular dish-like body made of synthetic resin or light metal, the fuel tank T on the bottom one side by ventilation passage L ₁
Kiyanisuta C likewise the ventilation passage L ₁ on the other side with a first pipe 11a connected to is projected
A second pipe 11b projecting from the second pipe 11b is provided, and a cylindrical column 11c slightly lower than the height of the peripheral wall is erected at the center of the inner side, and a body 1 between the cylindrical column 11c and the second pipe 11b is formed.
A thick base 12 is formed on the bottom of the base 1.

The base 12 has a horizontal through hole 12a communicating with the inside of the cylindrical column 11c. The second pipe 11b is connected to the inside of the cylindrical column 11c through the horizontal through hole 12a. The upper half portion is provided with a plurality of vertical holes 12b which are formed to communicate with the horizontal through-holes 12a and the space between the cylindrical column 11c and the body peripheral wall, and an umbrella-shaped valve body 13 made of an elastic material such as rubber. Is attached to cover the small hole 12b from above.

Reference numeral 15 denotes a cover made of a synthetic resin or light metal similarly to the body 11 and having a downward circular dish shape. A third pipe 15a is protrudingly provided on one upper side, and in this example, the third pipe 15a is provided. by opening and closing the passage L ₃ via is connected to the first switching valve B ₁ and the intake pipe K, thick valve portion 14a in the central portion between the cover 15 and the body 11
The peripheral edge of the diaphragm 14 is sandwiched between the overhanging collar 15b at the lower end of the cover 15 and the overhanging collar 11d at the upper end of the body 11, and is fixed to the three members.

A coil spring 16 having a required spring pressure is disposed between the retainer 14b at the center of the upper surface of the diaphragm 14 and the inner surface of the upper wall of the cover 15, and the central valve portion 14a of the diaphragm is normally operated by the spring pressure. Cylindrical column 1 in body 11
1c is closed by being pressed against the upper end thereof.

[0015] Also, the interior of the usual cover 15 is vented to atmosphere via the first switching valve B _1, ventilation passage L ₁ on the lower side of the diaphragm 14, the first pipe 11a
The pressure in the fuel tank T acts via the second switching valve B
_{2 is} also opened, and the canister C is connected via the tail end pipe Cb.
The atmosphere is made to enter inside.

Therefore, when the vehicle stops or refuels,
If the steam pressure in the fuel tank T becomes larger than the spring force of the coil spring 16 in the check valve v, the diaphragm valve portion 14
a is lifted to open the cylindrical column 11c, and the fuel vapor in the tank enters the body 11 through the first pipe 11a, and the cylindrical column 11c, the horizontal through hole 12a of the base, and the second pipe 11
sequentially through enters Kiyanisuta C and b and ventilation passage L _1, is adsorbed by the adsorbent.

On the other hand, when the pressure in the fuel tank T becomes a negative pressure due to a decrease in fuel or a drop in temperature, the diaphragm valve portion 14a closes the cylindrical column 11c at atmospheric pressure and spring pressure while the tank side is closed. Umbrella-shaped valve 13 on the base 12
Acting on it, it reversely deforms it, and the negative pressure
b, horizontal through hole 12a, second pipe 11b and ventilator
Transmitted to ® emission path L ₁ a through Kiyanisuta C, incorporated air from the tail pipe Cb, fed into the fuel tank T through the line in the opposite, to eliminate the negative pressure in the tank,
When the negative pressure is released, the umbrella-shaped valve 13 returns to its original position and closes the small hole 12b.

When the engine E is started, the negative pressure in the intake pipe K
The fuel adsorbed on the adsorbent of the canister C by the pressure
Purged by air entering from the end pipe Cb,
Passage L_Two Through the intake pipe K,
Depending on the conditions set in control unit U
Immediately after starting the engine E or after a certain time, the first switching
E valve B₁ And the second switching valve B_Two Is switched to the canister
C tail end pipe CbButWhile being closed,Air intake B
_1a And the inside of the cover 15 of the check valve v.
From the normal stateIntake pipe K is open / close passage L_Three Via check valve
v inside the cover 15StateIn the intake pipe K
Negative pressureOpen / close passage L _Three ThroughActs on diaphragm 14
Then, the valve portion 14a is lifted,On both sides of the check valve v
Ventilation passage L ₁ Communicate with the purge passage L
_Two , Canister C, ventilation passage L ₁ (Kani
Star side),A cylindrical column 11c, a first pipe 11a,Ventley
Passage L ₁ (Tank side) through the intake negative pressureFuel tongue
To the tank T, ventilation path L
₁ , Canister C andPurge passage L _Two The whole deviceNegative pressure
State.

The negative pressure state is detected by a pressure sensor Ps connected to the fuel tank T and transmitted to the control unit U, and the negative pressure in the tank T is reduced to a negative pressure required for leak inspection (for example, the intake pipe itself). Negative pressure of -600m
When the pressure becomes -30 mmHg (mHg), the purge control valve V is closed and the state is maintained for several seconds.

Thus, if there is no failure (leak) in the device, a signal indicating that there is no abnormality is sent to the alarm in the cab, and if there is a failure somewhere, the negative pressure detected by the pressure sensor Ps is reduced. It becomes 0 or a state close to this, and a signal indicating that there is an abnormality is sent to the alarm.

Then, regardless of the result of the inspection, after a predetermined time, the purge control valve V is opened by the control unit U and the first and second switching valves B are opened.
₁ and B ₂ are switched to the original positions and returned to the normal operation state.

[0022] Furthermore, during traveling of the vehicle, the more the amount to be purged of adsorbed fuel by operating conditions, when a large negative pressure in the connecting portion of the ventilation passage L ₁ of Kiyanisuta C occurs, the negative pressure is Since the umbrella-shaped valve body 13 and the diaphragm 14 in the check valve v are sucked downward through the ventilation passage L ₁ , the negative pressure is shut off there and is not transmitted to the fuel tank T.

FIG. 2 shows another embodiment. In this case, the third pipe 15a provided on the cover 15 is kept open to the atmosphere without connecting the cover 15 of the check valve v to the intake pipe K. Further, the position corresponding to both sides of the check valve v ventilation passage L _1, the wire W ₃
Connected to control unit U but air intake
Opening / closing first switching valve B ₁ ′ with no opening
The bypass passage L ₄ Are connected by

Usually, the bypass passage L_Four No. on
1 switching valveB ₁ 'Is closed while the tail of canister C is closed.
Second switching valve B on end pipe Cb_Two Open as above
Similarly, when the vehicle is stopped, the fuel vapor in the fuel tank T is discharged.
It is led to the canister C and is adsorbed by the adsorbent when the vehicle is running.
Purged fuel and send it to the intake pipe K.
Ventilation passage L of canister C₁ Raw at the connection
Negative pressure is shut off by check valve v(Valve 13 and valve portion 14a
Is closed)And don't tell the fuel tank T
In addition, at the time of inspection immediately after the start of the engine E or after a predetermined time
, The first switching valve by the control unit UB
₁ 'To switch the bypass passage L_Four While the second switch
E valve B_Two Is switched to close the tail end pipe Cb,
Purging the negative pressure in the pipe K with the purge passage L_Two , Ventilation passage
L₁ , Bypass passage L_Four To the fuel tank T through
To do.

Thus, the method of detecting the negative pressure state by the pressure sensor Ps, maintaining the inside of the apparatus at a required pressure state for several seconds, and confirming the presence or absence of a failure is the same as that described above.

In the example shown in the figure, the means that communicates with the atmosphere in the body when the fuel tank has a negative pressure is constituted by a vertical hole and an umbrella-shaped valve body. It is good also as a valve body.

[0027]

Since the present invention is configured as described above as a fuel vapor processing apparatus for a vehicle, fuel vapor generated in a fuel tank can be appropriately sent to an intake pipe without being released to the outside. and it is possible to smoothly eliminate the negative pressure generated in a fuel tank, not only it, the negative pressure generated in the Kiyanisuta during traveling of the vehicle is not transmitted to the fuel tank can be reliably blocked by the check valve, a fuel tank Damage to the engine, and
During the inspection after a certain period of time, the inside of the device can be maintained at the required negative pressure for a while , and the signal from the pressure sensor can be maintained.
By using the signal, it is possible to quickly know whether or not there is a failure in the apparatus, which is useful for securing the function of the processing apparatus.

[Brief description of the drawings]

FIG. 1 is a systematic explanatory diagram of an embodiment of the present invention.

FIG. 2 is a systematic explanatory diagram of another embodiment of the present invention.

FIG. 3 is a sectional view of a check valve.

FIG. 4 is a plan view taken along the line XX of FIG. 3;

FIG. 5 is a systematic explanatory diagram of a conventional device.

FIG. 6 is a sectional view of a conventional check valve.

FIG. 7 is a plan view of a half portion taken along the line YY of FIG. 6;

[Explanation of symbols]

B _1, B ₁ 'first switching valve B ₂ second switching valve C Kiyanisuta E engine K intake pipe L ₁ ventilation passage L ₂ purge passage L ₃ closing passage L ₄ bypass passage Ps pressure sensor T fuel tank U Control unit V Purge control valve v Check valve

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) F02M 25/08

Claims (2)

(57) [Claims] 1. A fuel tank and a canister are connected by a ventilation passage, while a canister is connected by a purge passage to a purge control valve attached to an intake pipe and controlled by a control unit. A body having a first pipe communicating with the canister, a second pipe communicating with the canister, and a cover having a third pipe, wherein a cylindrical column communicating with the second pipe is provided in the body, and the cylindrical column and the body are formed in the communicating portion. A valve body is provided only on the side of the space between the peripheral walls, and a check valve is provided between the body and the cover so as to close the cylinder by spring force. The cover is opened to the atmosphere through the third pipe on the way, or
Is connected to the intake pipe by an opening / closing passage provided with a first switching valve connected to the intake pipe, while a tail pipe of the canister is provided with a second switching valve for opening and closing the pipe, and A fuel vapor processing device for a vehicle, wherein a switching valve is connected to each of the control units, and the fuel tank is connected to the control unit via a pressure sensor for detecting an internal pressure. 2. A fuel tank and a canister are connected by a ventilation passage, while a canister is connected by a purge passage to a purge control valve attached to an intake pipe and controlled by a control unit. A body having a first pipe communicating with the canister, a second pipe communicating with the canister, and a cover having a third pipe, wherein a cylindrical column communicating with the second pipe is provided in the body, and the cylindrical column and the body are formed in the communicating portion. A valve body is provided only on the side of the space between the peripheral walls, and a check valve is provided between the body and the cover so as to close the cylinder by spring force. The third pipe of the cover is opened to the atmosphere, and the positions of both sides of the check valve in the ventilation passage are opened and closed.
The first switching valve is connected by a bypass passage, while the tail end pipe of the canister has a second cut-off for opening and closing the pipe.
A fuel vapor processing device for a vehicle, comprising a replacement valve , connecting the first and second switching valves to a control unit, and connecting the fuel tank to the control unit via a pressure sensor for detecting an internal pressure. .