JPH0637549U - Canister device - Google Patents

Abstract

(57) [Abstract] [Purpose] To reduce the size and improve the water resistance of the closing means that closes the atmosphere open passage of the canister. A small-diaphragm type negative pressure operating valve 16 having excellent water resistance is provided in an atmosphere opening passage 12 of a canister C, and is connected to a negative pressure chamber 28 of the negative pressure operating valve 16 and an intake passage 5 of an engine E. The surge tank 18 and the solenoid valve 19
Connect through. The charge solenoid valve 14 provided in the charge passage 7 and the purge solenoid valve 15 provided in the purge passage 8 are opened, the solenoid valve 19 is opened, and the negative pressure operating valve 16 is closed. A negative pressure of 5 is applied to the fuel tank T, and the depressurized state is monitored by the fuel tank internal pressure sensor 20 to detect a perforated failure of the canister device.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention has a canister containing an adsorbent inside, a charge passage connecting the canister to the fuel tank, a purge passage connecting the canister to the intake passage of the engine, and an atmosphere release passage connecting the canister to the atmosphere. The present invention relates to a canister device including a closing means capable of closing an atmosphere opening passage.

[0002]

[Prior art]

 The fuel vapor generated in the fuel tank is adsorbed by the adsorbent of the canister, and the atmospheric pressure is introduced into the canister by the negative pressure generated in the intake system during engine operation. Canister devices for supplying to a system for combustion are well known.

In recent years, it has been proposed to prevent the release of fuel vapor into the atmosphere by detecting a perforated failure of the canister device and issuing a warning to the driver (for example, Japanese Unexamined Patent Application Publication No. Hei 2 (1999) -211). -102360 gazette).

[0004]

[Problems to be solved by the device]

 By the way, as a method for detecting the perforated failure of the canister device, after closing the atmosphere opening passage of the canister with the closing means, the negative pressure of the intake system is applied to the inside of the fuel tank through the canister to change the internal pressure of the fuel tank. It is possible to detect leaks by monitoring.

In this case, it is conceivable to use a solenoid valve as a means for closing the atmosphere release passage of the canister. However, since the atmosphere release passage of the canister has a large diameter, not only the solenoid valve becomes large, but also the open bottom In a canister of a type, the solenoid valve is located below the vehicle body, so water or mud may adhere to the solenoid valve and cause malfunction.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to reduce the size and reliability of the closing means for closing the atmosphere opening passage of the canister.

[0007]

[Means for Solving the Problems]

 In order to achieve the above object, the present invention provides a canister containing an adsorbent therein, a charge passage connecting the canister to a fuel tank, a purge passage connecting the canister to an intake passage of an engine, and a canister to the atmosphere. In a canister device having an atmosphere opening passage communicating with each other and a closing means capable of closing the atmosphere opening passage, the closing means is constituted by a negative pressure operating valve, and a negative pressure chamber and a negative pressure source of the negative pressure operating valve are provided. Is connected via an on-off valve.

[0008]

【Example】

 An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows a first embodiment of the present invention, in which fuel pumped from a fuel tank T through a filter 1 and a fuel pump 2 passes through a feed passage 3 and a fuel injection valve of an engine E. 4 is supplied. The upper space of the fuel tank T and the downstream position of the throttle valve 6 provided in the intake passage 5 of the engine E are connected by a charge passage 7 and a purge passage 8, and a lower end is provided between the charge passage 7 and the purge passage 8. An open-bottom canister C that is open is installed.

The canister C stores activated carbon 11 as an adsorbent between the upper and lower filters 9 and 10. The charge passage 7 on the fuel tank T side is opened inside the activated carbon 11 and the purge on the engine E side is performed. The passage 8 opens into the upper space of the upper filter 9, and the lower space of the lower filter 10 communicates with the atmosphere via the atmosphere opening passage 12.

A two-way valve 13 is interposed in the charge passage 7 that connects the fuel tank T and the canister C. The two-way valve 13 opens when the internal pressure of the fuel tank T rises above the atmospheric pressure by a predetermined value, and the internal pressure of the fuel tank T drops below the internal pressure of the canister C by a predetermined value. In this case, the valve is opened to allow the fuel tank T and the canister C to communicate with each other. Note that the canister C side may have a negative pressure during purging, in which case the two-way valve 13 is kept closed.

A charge solenoid valve 14 is connected in parallel to the two-way valve 13. Therefore, when the charge solenoid valve 14 opens, the fuel tank T and the canister C communicate with each other without the two-way valve 13.

A purge solenoid valve 15 is provided in a purge passage 8 that connects the canister C and the intake passage 5 of the engine E. Therefore, when the purge solenoid valve 15 is opened, the canister C communicates with the intake passage 5, and when the purge solenoid valve 15 is closed, the communication between the canister C and the intake passage 5 is cut off.

The atmosphere opening passage 12 is provided with a normally open negative pressure operating valve 16 as a closing means capable of opening and closing the atmosphere opening passage 12. A negative pressure chamber 28 is defined by a diaphragm 27 inside a casing 26 of the negative pressure actuated valve 16 formed of a water-resistant synthetic resin, and a valve element 29 connected to the diaphragm 27 is attached to a valve seat 30. Opposing to sit down.

A surge tank 18 is connected to the intake passage 5 of the engine E via a check valve 17, and a solenoid valve 19 is provided between the surge tank 18 and the negative pressure chamber 28 of the negative pressure operating valve 16. Is installed. Therefore, when the solenoid valve 19 is opened, negative pressure acts on the negative pressure chamber 28 of the negative pressure actuating valve 16 to deform the diaphragm 27, and the valve body 29 is seated on the valve seat 30 to open the atmosphere opening passage. 12 is closed. The negative pressure actuated valve 16 is inevitably laid out in the lower part of the vehicle body due to the restriction of laying out the canister C on the vehicle body, whereas the solenoid valve 19 connected to the negative pressure actuated valve 16 through a pipe is hard to be splashed with water. It can be laid out on the top of the car body.

The surge tank 18 is decompressed by the negative pressure generated in the intake passage 5, and the negative pressure state is held by the check valve 17. Therefore, when the solenoid valve 19 is opened, the negative pressure operating valve 16 is closed by the negative pressure of the surge tank 18, and the communication between the atmosphere opening passage 12 and the atmosphere can be cut off.

The fuel tank T is provided with a fuel tank internal pressure sensor 20 for detecting the internal pressure of the fuel tank T.

In addition to the fuel tank internal pressure sensor 20, the electronic control unit U including a microcomputer includes an oxygen concentration sensor 21 for detecting the oxygen concentration O ₂ in the exhaust gas of the engine E, and an opening θ of the throttle valve 6. A throttle opening sensor 22 that detects _TH , an absolute intake pipe pressure sensor 23 that detects the absolute pressure Pb of the intake passage 5, a rotation speed sensor 24 that detects the rotation speed Ne of the engine E, and a cooling water temperature Tw of the engine E. The water temperature sensor 25 is connected. The electronic control unit U processes the signals from the sensors 21 to 25 according to a program given in advance, performs feedback control or open loop control of the fuel injection time of the fuel injection valve 4, and controls the canister device. The solenoid valve 19 for operating the negative pressure operating valve 16 to be controlled, the charge solenoid valve 14, and the purge solenoid valve 15 are controlled in operation.

Next, the operation of the embodiment of the present invention having the above configuration will be described.

While the engine E is stopped, both the charge solenoid valve 14 and the purge solenoid valve 15 are kept closed, and the negative pressure operating valve 16 is kept open. In this state, when the temperature of the fuel tank T rises and the internal pressure of the fuel tank T rises due to the evaporation of fuel, the two-way valve 13 opens and the fuel vapor flows into the canister C through the charge passage 7, Therefore, the activated carbon 11 is prevented from being adsorbed and leaking to the outside. At the same time, the internal pressure of the fuel tank T is released to the outside from the negative pressure operating valve 16 provided in the atmosphere opening passage 12 of the canister C, and the internal pressure of the fuel tank T is prevented from rising excessively. Further, when the internal pressure of the fuel tank T 1 drops due to the temperature drop while the engine E is stopped, it is possible to prevent the internal pressure of the fuel tank T from excessively dropping due to the introduction of outside air into the fuel tank T in the route opposite to the above. To be done.

From the time when the engine E is started to the time when the operating condition becomes stable, that is, the oxygen concentration sensor 21 is activated, the cooling water temperature rises, and the engine speed becomes equal to or higher than a predetermined value, the idling condition is maintained. Until it is released, the fuel injection amount of the fuel injection valve 4 is open-loop controlled by the electronic control unit U. In this open loop control state, the purged fuel from the canister C becomes a disturbance factor that fluctuates the air-fuel ratio, so the adsorbed fuel in the canister C is not purged, and the charge solenoid valve is the same as when the engine E is stopped. 14 and the purge solenoid valve 15 are kept closed, and the negative pressure operating valve 16 is kept open.

When a predetermined time elapses after the engine E is started, the fuel injection amount of the fuel injection valve 4 is switched from the open loop control to the feedback control. This feedback control is performed by feeding back the oxygen concentration output by the oxygen concentration sensor 21, multiplying the basic injection time by a feedback correction coefficient, and determining the fuel injection time.

In the feedback control region, both the charge solenoid valve 14 provided in the charge passage 7 and the purge solenoid valve 15 provided in the purge passage 8 are opened, and the fuel tank T and the canister C are connected via the two-way valve 13. However, the canister C and the intake passage 5 of the engine E communicate with each other. In this state, the air introduced from the atmosphere opening passage 12 of the canister C due to the negative pressure generated in the intake passage 5 is sucked through the purge solenoid valve 15 of the purge passage 8 to the activated carbon 11 of the canister C. The adsorbed fuel that has been adsorbed is purged and supplied to the intake pipe 5. During that time, the negative pressure of the intake passage 5 acts on the fuel tank T via the opened charge solenoid valve 14, so that the internal pressure of the fuel tank T becomes atmospheric pressure or lower when the engine E is stopped. As a result, even if the cap of the fuel tank T is opened for refueling immediately after the engine E is stopped, the fuel vapor is not released to the atmosphere.

Now, an inspection as to whether or not there is a leak in the canister device including the fuel tank T, the charge passage 7, the canister C, the purge passage 8 and the atmosphere opening passage 12 is performed as follows.

During operation of the engine, the charge solenoid valve 14 and the purge solenoid valve 15 are opened by a command from the electronic control unit U, and at the same time, the normally open negative pressure operating valve 16 provided in the atmosphere opening passage 12 is closed. . The negative pressure operating valve 16 is operated by opening the electromagnetic valve 19 connected to the surge tank 18 and transmitting the negative pressure of the surge tank 18 to the negative pressure operating valve 16.

Since the introduction of air from the atmosphere opening passage 12 is shut off by closing the negative pressure operating valve 16, the negative pressure in the intake passage 5 of the engine E is directly transmitted to the fuel tank T and the fuel tank T Reduce the internal pressure. The internal pressure of the fuel tank T is detected by a fuel tank internal pressure sensor 20, and the tendency of the internal pressure of the fuel tank T to decrease from the moment the negative pressure operating valve 16 is closed is monitored. At this time, if the internal pressure of the fuel tank T does not exhibit a predetermined depressurization tendency, that is, if the internal pressure of the fuel tank T does not rapidly decrease, it can be determined that there is a leak in the canister device.

As a method for checking the leak down, it is possible to adopt the following method. That is, after the internal pressure of the fuel tank T is reduced in the same manner as described above, the purge solenoid valve 15 is closed to seal the fuel tank T, and in this state, the internal pressure of the fuel tank T is monitored by the fuel tank internal pressure sensor 20. To do. As a result, if the internal pressure of the fuel tank T rises, it can be determined that there is a leak in the canister device.

Therefore, the opening / closing means of the atmosphere opening passage 12 which is inevitable to be wet with water due to layout restrictions is constituted by a negative pressure operating valve 16 having high water resistance, and the negative pressure operating valve 16 is exposed to water. Since it is operated by the solenoid valve 19 installed at a high position where it is hard to get wet, the solenoid valve 19 can be downsized and its durability can be improved compared to the case where the atmosphere opening passage 12 is directly opened and closed by a large solenoid valve. it can.

FIG. 2 shows a second embodiment of the negative pressure operation valve 16. In this embodiment, the inflow of water from the negative pressure operated valve 16 is prevented, and the valve body 19 is composed of a float. Therefore, when water flows in from below, the valve body 19 made of float floats up and sits on the valve seat 30, and the atmosphere opening passage 12 can be closed.

FIG. 3 shows a third embodiment of the negative pressure operating valve 16. In this embodiment, dust is prevented from entering from the negative pressure operation valve 16. By providing the labyrinth passage 31 at the lower end of the casing 26, the flow velocity of the air passing therethrough is reduced to lower the dust. Can be dropped into.

Although the embodiment of the present invention has been described in detail above, the present invention is not limited to the above embodiment, and various design changes can be made.

For example, although the open bottom type canister C is illustrated in the embodiment, the present invention can be applied to a closed bottom type canister.

[0033]

[Effect of device]

 As described above, according to the present invention, the closing means capable of closing the atmosphere opening passage of the canister is constituted by the negative pressure operating valve, and the negative pressure chamber of this negative pressure operating valve and the negative pressure source are connected via the opening / closing valve. As a result, it is not necessary to configure the air-opening passage obstruction means, which is inevitably wet with water, by a large solenoid valve having poor water resistance, and this enables miniaturization and improvement of durability of the obstruction means. .

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of a canister device.

FIG. 2 is a diagram showing a second embodiment of a negative pressure operated valve.

FIG. 3 is a diagram showing a third embodiment of a negative pressure operated valve.

[Explanation of symbols]

 5 Intake passage 7 Charge passage 8 Purge passage 11 Adsorbent 12 Atmosphere release passage 16 Negative pressure actuation valve (blocking means) 18 Surge tank (negative pressure source) 19 Electromagnetic valve (open / close valve) 28 Negative pressure chamber C Canister E Engine T Fuel tank

Claims (1)

[Scope of utility model registration request] 1. A canister (C) containing an adsorbent (11) inside, a charge passage (7) connecting the canister (C) to a fuel tank (T), and a canister (C) connecting an engine (E). A purge passage (8) connected to the intake passage (5), an atmosphere opening passage (12) communicating the canister (C) with the atmosphere, and a closing means (16) capable of closing the atmosphere opening passage (12). In the provided canister device, the closing means (16) is constituted by a negative pressure operated valve, and the negative pressure chamber (28) and the negative pressure source (18) of the negative pressure operated valve are connected via an opening / closing valve (19). A canister device characterized by being connected.