JP2002303214A - Device for restricting exhaust gas of automobile - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device for restricting exhaust gas of an automobile capable of reducing blowby gas and fuel vaporization gas remaining in an intake system after an engine is stopped to improve startability of the engine, and restricting emission of residual gas components of them to atmospheric air. SOLUTION: This device for restricting exhaust gas is provided with a communication passage 58 communicating an upper space in a fuel tank 35 with a downstream part of an intake manifold 26, a control valve 46 provided at a specified position in the communication passage to be controlled to open/close the communication passage in accordance with vehicle states and engine states, and a check valve 60 to allow flow from the intake manifold side to the fuel tank side only when inside pressure of the fuel tank is negative for prohibiting backflow. When the engine is in a stopped state, with the inner pressure of the fuel tank in a negative state, the control valve is controlled to open to form communication in the communication passage, thereby the gas components are sucked from the intake manifold to the fuel tank.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust gas suppressing device for a motor vehicle, and more particularly to a device for reducing the amount of exhaust gas emitted from the intake system of a motor vehicle into the atmosphere.

[0002]

Generally, as shown in FIG. 3, an intake manifold 1 constituting an intake system of an automobile is used to supply intake air IA filtered by an air cleaner 2 to each cylinder of an engine 3. It is attached to one side surface of the cylinder head 4. The intake manifold 1 uses a PCV valve 6 for forcibly recirculating the blow-by gas BG leaked to the crankcase 5 to the intake system of the engine 3 by using the intake manifold negative pressure during engine operation. A fuel evaporative gas (evaporative gas) E generated in the fuel tank 8 and adsorbed on the activated carbon in the canister 9;
G through the purge passage 10 to the intake manifold 1
The apparatus is provided with a fuel evaporative gas emission suppression device 11 that sucks air into the air, thereby suppressing the emission of CO (carbon monoxide) and HC (hydrocarbon) into the atmosphere. In addition, the code | symbol 12 in a figure is:
Reference numeral 13 denotes a two-way valve for keeping the internal pressure of the fuel tank 8 constant, and reference numeral 13 denotes a purge control valve that is controlled to open and close according to the state of the engine.

The PCV valve 6 automatically adjusts the recirculation amount of the blow-by gas BG by changing the valve opening area in accordance with the intake manifold negative pressure during engine operation. At a high load, the blow-by gas BG exceeding the valve passage amount may be generated in the crankcase 5. Therefore, excessive blow-by gas BG is recirculated to the air intake duct 16 upstream of the throttle valve 15 via the blow-by hose 14 attached to the engine intake system, but is recirculated when the engine does not generate negative intake manifold pressure. The blow-by gas BG may remain in the engine intake system such as the intake manifold 1 and the air intake duct 16. The blow-by gas BG remaining in the engine intake system not only deteriorates the startability of the engine, but may be released to the atmosphere from the intake port 17 upstream of the air cleaner 2 if the engine is stopped.

Further, the fuel evaporative gas EG leaked from an injector 18 mounted downstream of the intake manifold 1 to inject the fuel evaporative gas EG sucked into the intake manifold 1 from the canister 9 and the fuel pumped from the fuel tank 8. Also, there is a possibility that the engine remains in the intake manifold 1 when the engine is stopped. The fuel evaporative gas EG remaining in the intake manifold 1 not only lowers the engine startability but also discharges to the atmosphere from the intake port 17 upstream of the air cleaner 2 when the engine stops, similarly to the residual blow-by gas BG. There is a possibility that it will be. Further, when the purge passage 10 for feeding the fuel evaporative gas EG from the canister 9 to the intake manifold 1 is connected at a substantially central position upstream of the intake manifold 1, the performance difference between the cylinders of the engine 3 and between the left and right banks. Therefore, there is a problem that engine stability is deteriorated during the evaporative purge.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the conventional vehicle exhaust gas suppression apparatus, and has been made to improve the engine stability at the time of an evaporative purge. In order to improve engine startability by reducing blow-by gas and fuel evaporative gas remaining in the intake system after the engine stops, and to suppress the release of these residual gas components to the atmosphere, the latest regulations on automobile exhaust gas have been strengthened. It is an object of the present invention to provide a vehicle emission control device capable of coping with the problem.

[0006]

In order to achieve the above object, the present invention provides blow-by gas reducing means for reducing blow-by gas leaked into an engine to an intake system of the engine, and fuel generated in a fuel tank. After storing the evaporative gas in the canister, the vehicle is provided with a fuel evaporative gas emission suppressing means for inhaling the evaporative gas from the purge passage into the intake manifold according to the operating state of the engine. A communication passage communicating the upper space in the fuel tank with the downstream of the intake manifold; and a communication passage provided at a predetermined position of the communication passage, and opening and closing the communication passage in accordance with a preset vehicle state and engine state. A control valve, and when the pressure in the fuel tank is a negative pressure, the pressure increases from the intake manifold side toward the fuel tank side. A check valve for permitting flow and preventing backflow, wherein when the engine is stopped and the inside of the fuel tank is in a negative pressure state, the control valve is controlled to open to communicate with the communication passage. It is characterized in that a gas component is sucked from the intake manifold toward the inside of the fuel tank.

[0007] The fuel evaporative gas emission suppressing means includes an air communication type negative pressure side valve for supplying fresh air into the fuel tank when the internal pressure of the fuel tank becomes a predetermined negative pressure state, The valve is set so as to open later than the check valve.

The purge passage is connected to a predetermined position of the communication passage.

One end of the communication passage is connected to an intake manifold near an injector mounting position where fuel supplied from the fuel tank is injected.

[0010] One end of the communication passage is divergently branched so as to be connected to the vicinity of each injector mounting position of a branch pipe divided into a plurality of streams downstream of the intake manifold.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. FIG. 1 is an explanatory view illustrating the configuration of an exhaust gas suppression device for a vehicle according to the present invention, FIG. 2A is a cross-sectional view illustrating the internal structure of a two-way valve, and FIG. It is sectional drawing explaining.

As shown in FIG. 1, the exhaust gas suppressing device for a vehicle according to the present invention includes a blow-by gas reducing device 34 provided in an engine intake system and a fuel evaporative gas emission suppressing device 57 provided in an engine fuel supply system. And an exhaust gas suppressing device 61 for suppressing the release of the blow-by gas BG and the fuel evaporative gas EG returned to the intake system to the atmosphere.
It is assumed that vehicles to which the present invention is applied include vehicles equipped with North American OBD-II as an in-vehicle diagnostic system.

First, the structure of the engine intake system will be described. The intake air IA to the engine 20 is sucked from an intake port 21 communicating with the atmosphere, filtered by an air cleaner 22, and then filtered by an air intake duct 23 to a throttle body 24. The intake air is introduced into the intake manifold 26 in a state where the amount of intake air is controlled by a throttle valve 25 linked to the accelerator opening.
Intake air IA introduced into intake manifold 26
Is diverted by a plurality of suction pipes 27 on the downstream side of the intake manifold 25 and carried to the cylinder head 28,
The mixture is fed into each cylinder of the engine 20 in a state of being mixed with a predetermined amount of fuel injected from an injector 29 attached to a predetermined position of each suction pipe 27.

The blow-by gas BG that has leaked into the crankcase 30 during operation of the engine is forcibly recirculated to the intake manifold 26 by a PCV valve 31 attached to a predetermined position of the intake manifold 26, and has a valve passing amount equal to or more than the valve passing amount. Of the blow-by gas BG is returned to the air intake duct 23 by the blow-by pipe 32 communicating between the air intake duct 23 and the crankcase 30. An air line 3 is provided between the air intake duct 23 and the crankcase 30 for introducing a part of the intake air IA into the crankcase 30 to scavenge the blow-by gas BG.
3 is attached. These components constitute a blow-by gas returning device 34.

Next, the engine fuel supply system will be described. The fuel contained in the fuel tank 35 is drawn from the mesh filter 36 and then supplied to the fuel pump 37.
To the engine 20 via the delivery passage 38, and the injector 2 adjusts the injection time and injection timing of the engine 20 to the optimum injection time and timing by a control signal from control means (not shown).
9 is injected. Excess fuel from the engine 20 is supplied to the fuel tank 35 through the return passage 39.
Will be returned within. The fuel in the fuel tank 35 is
A pressure sensor (not shown) detects the internal pressure of the fuel tank 35 and outputs it to control means (not shown) while the inside of the tank is transferred by a jet pump 40 utilizing the flow rate of fuel returned from the engine 20. Installed.

When the fuel evaporative gas EG generated in the fuel tank 35 reaches a set pressure, it pushes open a two-way valve 42 provided in the charge passage 41 to open the canister 4
3 and is adsorbed on activated carbon. When the engine 20 is in an operating state, an intake manifold negative pressure is generated by engine boost, and the purge passage 4
5 is controlled by a control means (not shown) to open the purge control valve 46, so that the fuel evaporative gas EG stored in the canister 43
The fresh air introduced from the fresh air introduction passage 44 of No. 3 is separated from the activated carbon and sent to the intake manifold 26 side. The purge passage 45 is connected to a predetermined position of a transfer passage 58 to be described later, and the purge control valve 46 is controlled to open and close according to the engine operating state, so that the intake manifold 26 side and the canister 43 side are connected. Can be communicated or cut off.

The fresh air sucked into the canister 43 is filtered by an air filter 47 and then supplied and controlled by a solenoid valve 48 which is controlled by a control means (not shown) to open and close, and the canister 43 and the solenoid valve 48 are controlled. The fresh air is also supplied to the two-way valve 42 by a bypass passage 49 connected to the fresh air introduction passage 44 between the two. The solenoid valve 48 is set in advance by a control means (not shown) so that valve closing control is performed at the time of OBD-II determination, and valve opening control is always performed except at the time of determination.

Incidentally, the two-way valve 42 is
As shown in (a), regardless of the engine operating state, when the positive pressure in the fuel tank 35 exceeds a set value, the diaphragm 50 pushes up the spring 51 to connect the fuel tank 35 and the canister 43 to the positive pressure side. When the negative pressure in the fuel tank 35 falls below a set value, a valve body 53 compresses a spring 54 to supply fresh air into the fuel tank 35, and an air communication type negative pressure side valve 55 is provided. I have. Reference numeral 56 in the drawing indicates an atmospheric passage that supplies the working chamber of the positive pressure side valve 52 with atmospheric pressure. And
These constitute a fuel evaporative emission control device 57 in the fuel supply system.

In addition to the structure of the blow-by gas reducing device 34 and the fuel evaporative gas emission suppressing device 57, the blow-by gas reducing device 57 communicates the downstream of the intake manifold 26 with the upper space in the fuel tank 35, that is, the upper air chamber, and the purge passage. 45, a transfer passage 58 connected to the transfer passage 58, a solenoid valve 59 provided at an intermediate position of the transfer passage 58, and controlled by an unillustrated control means to open and close the valve, and circulate only from the intake manifold 26 side to the fuel tank 35 side. And a check valve 60 for preventing backflow is provided.

The communication end of the transfer passage 58 on the intake manifold side is multipointed so as to be provided in the vicinity of the mounting position of each injector 29 of the plurality of suction pipes 27 on the downstream side of the intake manifold 26. The evaporative gas EG is directly and substantially directly sent into each cylinder without convection from the upstream side of the intake manifold 26. The solenoid valve 59 is set in advance by a control means (not shown) so that valve closing control is performed at the time of OBD-II determination, valve closing control is performed at the time of engine operation other than the determination, and valve opening control is performed at the time of engine stop other than the determination. Check valve 60
As shown in FIG. 2B, the spring 62 and the valve 6
When the positive pressure in the fuel tank 35 exceeds the positive pressure side set value, the fuel tank 35 and the intake manifold 26 are shut off, while the negative pressure in the fuel tank 35 is reduced to the negative pressure side. When the pressure falls below the set value, the communication between the fuel tank 35 and the intake manifold 26 is established, and the check valve 60 is opened when the negative pressure side valve 56 of the two-way valve 42 is opened. It is set in advance so as to be earlier than the valve timing.

According to this configuration, the blow-by gas BG generated in the crankcase 30 during operation of the engine is
Intake manifold 26 by PCV valve 31
And the blow-by gas BG that is equal to or larger than the valve passing amount is returned to the air intake duct 23 by the blow-by pipe 32. Most of the blow-by gas BG recirculated to the engine intake system is sucked into the engine 20 by the intake manifold negative pressure. During engine operation, if the negative pressure in the fuel tank 35 falls below the set value, the two-way valve 42
Is opened, the fresh air introduced by the air filter 47, the solenoid valve 48, and the bypass passage 49 is sucked into the fuel tank 35 through a part of the charge passage 41, whereby the fuel tank 35 is opened. Is prevented from being deformed.

On the other hand, the heat generated in the fuel tank 35 by the radiant heat from the running vehicle or the road, the outside temperature when the engine is stopped immediately after the running, or the outside air temperature when the vehicle is parked for a long time, and reached the set pressure. The fuel evaporative gas EG pushes open the positive pressure side valve 52 of the two-way valve 42 provided in the charge passage 41, is introduced into the canister 43, and is adsorbed by the activated carbon. Thereafter, the control means (not shown) controls the opening of the purge control valve 46 in accordance with the operation of the engine, so that the fuel evaporative gas EG stored in the canister 43 is activated carbon by the fresh air introduced from the fresh air introduction passage 44. From the suction pipe 27 downstream of the intake manifold 26 via the purge passage 45 and the transfer passage 58, and then sent to the vicinity of the injector mounting position of the intake pipe 27.
Inhaled to zero. At this time, since the intake manifold 26 side of the transfer passage 88 is multipointed,
The fuel evaporative gas EG is smoothly sucked into each cylinder to stabilize engine combustion. During such an engine operation, the solenoid valve 48 is controlled to open to supply fresh air to the canister 43 by a control means (not shown), and the solenoid valve 59 is controlled to close so that the intake manifold 2 is not operated.
6 and the fuel tank 35 side are shut off.

In this state, the engine 20
Is stopped, the intake manifold negative pressure is not generated, so that a part of the blow-by gas BG recirculated to the engine intake system and the fuel evaporative gas EG sent out from the canister 43, or from the injector 29 into the intake manifold 26 The leaked fuel gas EG or the like remains in the engine intake system without being sucked into the engine 20. On the other hand, control means (not shown) corresponding to the stop of the engine closes the purge passage 45 by controlling the valve control of the purge control valve 46, which was previously controlled to be open, so that the intake manifold 26 and the canister 4 are closed.
The third side is set in a non-communication state, and the solenoid valve 59 that has been closed until then is controlled to open. On the other hand, the fuel tank 3
When the fuel temperature in the fuel tank 5 decreases, the fuel tank 3
Liquefaction of the fuel evaporative gas EG in the fuel tank 5 and contraction of the fuel volume occur, and the inside of the fuel tank 35 starts to change from positive pressure to negative pressure.
Then, the negative pressure in the fuel tank 35 is
When the pressure falls below the set value on the negative pressure side, the check valve 60 opens to communicate between the intake manifold 26 side and the fuel tank 35 side.

Then, blow-by gas BG and fuel evaporative gas EG remaining in the engine intake system such as the air intake duct 23 and the intake manifold 26 are sucked from the transfer passage 58 connected to the suction pipe 27 downstream of the intake manifold 26. Thereafter, the inside is sucked into the fuel tank 35 having a predetermined negative pressure. At this time, since the check valve 60 is set to open earlier than the negative pressure side valve 56 of the two-way valve 42, fresh air from the two-way valve 42 is sucked into the fuel tank 35. The blow-by gas BG and the fuel evaporative gas EG in the air intake duct 23 and the intake manifold 26 are sucked in earlier than the air intake duct 23 and the intake manifold 26. When the internal pressure of the fuel tank 35 sucking the residual gas exceeds the negative pressure side set pressure of the check valve 60, the check valve 60 closes to stop the suction of the residual gas into the fuel tank 35. Is done.

As a result, the blow-by gas BG and the fuel evaporative gas EG remaining in the engine intake system when the engine is stopped are sucked into the fuel tank 35 from the intake system by the negative pressure in the fuel tank 35. And the blow-by gas B remaining in the intake system such as the intake manifold 26 and the air intake duct 23 while being prevented from being released into the atmosphere through the opening 21 of the intake system.
G and fuel evaporative gas EG can be reduced,
In addition to improving engine startability, idling during engine operation can be further stabilized. Further, since the transfer passage 58 for transferring the residual gas from the intake system to the fuel tank 35 is shared as a part of the purge passage 45, the structure of the exhaust gas suppressing device 61 can be simplified, and the cost of parts can be reduced. Reduction can be achieved. In addition, since the fuel evaporative gas EG from the canister 43 is smoothly sucked into each cylinder, the engine rotation can be stabilized, and the quality and product appeal can be improved.

At this time, the blow-by gas BG and the fuel evaporative gas EG sucked into the fuel tank 35 from the intake system by the negative pressure in the fuel tank 35 are moved to the intake manifold side, that is, the intake system side by the check valve 60. And the opening timing thereof is set so that only the negative pressure side opens earlier than the opening timing of the two-way valve 42 which is of the air communication type. Residual gas in the engine intake system is sucked and collected in the fuel tank earlier than when fresh air is sucked, thereby preventing the residual gas from being released into the atmosphere.

Further, it is determined whether or not the leakage of the fuel evaporative gas EG is equal to or less than an allowable value. If the leak exceeds the allowable value, measures are taken to prevent the release of the fuel evaporative gas EG to the atmosphere. North American OBD-II evaporative judgment
Solenoid valves 48 and 5 are controlled by a control device (not shown).
When the valve 9 is controlled to close, the fuel evaporative gas EG, the blow-by gas BG, and the like sucked into the fuel tank 35 are maintained at a constant pressure. Is prevented beforehand,
It can also handle the latest tightened regulations.

As a result, the emission of CO, HC and the like to the atmosphere can be suppressed, and the reduction of the emission can enhance the protection of the environment and the protection of the user.

In the present embodiment, the communication end of the transfer passage 58 on the intake manifold side is provided near the mounting position of each injector 29 on the downstream side of the intake manifold 26 to provide a multipoint. The purge passage 45 is connected to the intake passage 45, but the invention is not limited to this. The purge passage 45 is extended so as to communicate the intake manifold 26 with the canister 43, and the purge passage 45 is connected to the intake manifold side. An end is provided near the mounting position of each injector 29 on the downstream side of the intake manifold 26 to provide a multipoint.
The transfer path 58 may be connected to a predetermined position of the transfer path 58.

[0030]

As described above, according to the vehicle exhaust gas suppression apparatus of the present invention, a transfer passage is provided for communicating the vicinity of the injector mounting position on the downstream side of the intake manifold with the upper space in the fuel tank. A purge passage from the canister is connected to the transfer passage, and a solenoid valve that is controlled to open and close according to the vehicle state and the engine operation state is provided. As a result, the fuel evaporative gas from the canister can be almost directly fed into the cylinder without convection from the upstream side of the intake manifold, so that the engine stability at the time of the evaporative purge can be maintained. Moreover,
Residual gas components of the intake system such as the intake manifold and air intake duct can be sucked into the fuel tank by the volume reduction effect when the fuel temperature in the fuel tank falls, so blow-by gas remaining in the intake system after the engine stops. Emission control system that can reduce engine and fuel evaporative emissions to improve engine startability, suppress the release of these residual gas components to the atmosphere, and respond to the latest tightening of regulations on vehicle exhaust emissions. Can be provided.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram illustrating a configuration of an exhaust gas suppression device for a vehicle according to the present invention.

2A is a cross-sectional view illustrating an internal structure of a two-way valve, and FIG. 2B is a cross-sectional view illustrating an internal structure of a check valve.

FIG. 3 is an explanatory diagram illustrating a configuration of a conventional vehicle exhaust gas suppression device.

[Explanation of symbols]

 Reference Signs List 20 engine 26 intake manifold 29 injector 34 blow-by gas reducing device 35 fuel tank 42 2-way valve 43 canister 45 purge passage 55 negative pressure valve 57 fuel evaporative gas emission suppression device 58 transfer passage 59 solenoid valve 60 check valve 61 emission gas suppression device

Claims (5)

[Claims] 1. A blow-by gas reducing means for reducing blow-by gas leaked into an engine to an intake system of the engine, and a fuel evaporative gas generated in a fuel tank is stored in a canister, and the blow-by gas is stored in a canister. An exhaust gas suppression device for a vehicle, comprising: a fuel evaporative gas emission suppression unit that causes the intake manifold to be sucked into the intake manifold from the purge passage. The exhaust gas suppression device communicates an upper space in the fuel tank with a downstream of the intake manifold. A communication passage, a control valve provided at a predetermined position of the communication passage, for opening and closing the communication passage in accordance with a preset vehicle state and an engine state; and A check valve for permitting flow only from the fuel tank to the fuel tank side and preventing backflow. When the fuel tank is stopped and the fuel tank is in a negative pressure state, the control valve is controlled to open to communicate with the communication passage, and the gas component flows from the intake manifold toward the inside of the fuel tank. A vehicle exhaust gas suppression device characterized by sucking air. 2. The fuel-evaporated-gas emission suppressing means includes an atmosphere-communication-type negative pressure-side valve that supplies fresh air into the fuel tank when the internal pressure of the fuel tank reaches a preset negative pressure state. The exhaust gas suppression device for an automobile according to claim 1, wherein the negative pressure side valve is set to open later than the check valve. 3. The exhaust gas suppression device for an automobile according to claim 1, wherein the purge passage is connected to a predetermined position of the communication passage. 4. The vehicle according to claim 1, wherein one end of the communication passage is connected to an intake manifold near an injector mounting position at which fuel supplied from the fuel tank is injected. Emission control device. 5. The multi-branch according to claim 4, wherein one end of the communication passage is branched so as to be connected to the vicinity of each injector mounting position of a branch pipe divided into a plurality of branches downstream of the intake manifold. Car emission control device.