JPS5849403Y2 - Fuel evaporative gas purge device - Google Patents

Description

[Detailed explanation of the idea] This invention relates to an improvement of a fuel evaporative gas purging device.

Conventionally, in automobiles, the fuel evaporative gas generated in the fuel tank is adsorbed in a fuel evaporative gas adsorption canister, and then sucked out by negative intake pressure from the purge port opened in the intake passage while the engine is running and sent to the engine. It was then burnt and treated with a rainbow.

However, in such conventional fuel evaporative gas purge systems, the purge flow rate is proportional to the intake pipe negative pressure, so when the intake flow rate is low, the purge flow rate increases, which has a large effect on the engine operating condition. Therefore, there was an inconvenience that a large amount of purge could not be performed.

Furthermore, in order to completely comply with regulations on the release of fuel evaporative gas into the atmosphere, the capacity of the canister must be increased, and in this case, the purge flow rate must also be increased, which the conventional purge system described above cannot do. There is a disadvantage that it cannot correspond to

This invention was made to solve the above-mentioned conventional inconveniences, and the purpose is to provide a fuel evaporative gas purge device that can purge a large amount of fuel evaporative gas without affecting the operating condition of the engine. do.

In other words, this invention controls the amount of fuel evaporative gas purge using back pressure that is proportional to the intake flow rate of the engine.

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

An EGR valve 5 is provided in the middle of an EGR pipe 4 that connects the exhaust pipe 2 and intake pipe 3 of the engine 1 and recirculates exhaust gas from the exhaust system to the intake system.

This EGR valve 5 includes a constant pressure chamber 1 connected to the exhaust pipe 2 side via a throttle 6, a control valve body 9 that comes into contact with and separates from a valve seat 8 provided between this constant pressure chamber 7 and the intake pipe 3 side, and Control valve body 9
It has a diaphragm mechanism 10 that operates the diaphragm mechanism 10.

A spring 13 is provided in a negative pressure chamber 12 defined by the diaphragm 11 of the diaphragm mechanism 10 to bias the diaphragm 11 and the control valve body 9 toward the valve seat 8 .

The negative pressure chamber 12 includes an EGR vacuum modulator 14 and a bimetallic vacuum switching valve (hereinafter referred to as B).
The intake pipe 3 is connected to the intake pipe 3 through a negative pressure line 16 having VSV (VSV) 15 in series, so that intake negative pressure is introduced.

The gGR vacuum modulator 14 is connected to the negative pressure pipe 1
6, and this bleed pipe 1T has a throttle 18 and an atmosphere communication port 19 located closer to the EGR valve 5 than the throttle 18.

A control valve body 20 whose opening area can be changed is provided to the atmosphere communication port 19 and supported by a diaphragm 21 .

Atmospheric communication port 19 defined by this diaphragm 21
The atmospheric pressure chamber 22 on the side has an air filter 23 and a communication port 24.
Further, a pressure chamber 25 on the opposite side from the atmospheric pressure chamber 22 is connected to the constant pressure chamber γ of the EGR valve 5 via a pressure pipe 26.

Reference numeral 27 in the figure represents a spring that biases the diaphragm 21 toward the pressure chamber 25, 28 represents a throttle valve, and 29 represents a negative pressure port that connects the negative pressure line 16 to the intake pipe 31.

This negative pressure port 29 is downstream of the throttle valve 28 when the opening degree is above a certain level, and negative pressure is applied thereto.

R7d Note 8 V SV 15 is attached to the intake pipe 3 downstream of the throttle valve 28, and includes a bimetal 32 in a chamber 31 that communicates with the inside of the intake pipe 3 via a communication hole 30.

The negative pressure pipe 16 passes adjacent to the chamber 31 with a bimetal 32 in between, and when the bimetal 32 bends to the right in the figure and contacts the O-ring 33, communication with the chamber 31 is cut off by the bimetal 32. When the temperature of the intake air passing through the intake pipe 3 is below a certain value, for example 15° C. or below, the chamber 31 and the negative pressure pipe 16 are brought into communication when the bimetal 32 is reversed to the left in the figure. There is.

A purge port 34 is formed in the intake pipe 3 slightly downstream from the throttle valve 28 .

This purge port 34 is connected to a charcoal canister 36 via a purge passage 35.

A vacuum control valve (hereinafter referred to as VCV 5) 37 is interposed in the middle of this purge passage to turn on/off the purge and increase/decrease the amount of purge.

This VCV 37 is a diaphragm 39 equipped with a valve body 38 for opening/closing or controlling the degree of opening of the purge passage 35.
The diaphragm 39 connects the negative pressure in the negative pressure chamber 41 formed on the opposite side of the opening 40 of the purge passage 35 with the spring 4.
2, the valve body 38 closes the opening 40 when the negative pressure in the negative pressure chamber 41 is below a certain value, and when the negative pressure is above a certain value, the valve body 38 closes the opening 40 according to the value of the negative pressure. The valve body 38 is moved away from the opening 40.

The negative pressure chamber 41 of the VCV 37 is connected to the negative pressure pipe 16 between the negative pressure chamber 12 of the EGR valve 5 and the EGR vacuum modulator 14 via a negative pressure pipe 43, and the negative pressure is transmitted to the EGR valve 5. The same negative pressure is transmitted.

Reference numeral 44 in the figure indicates a fuel tank, and this fuel tank 44
The upper end of the charcoal canister 36 is connected to the charcoal canister 36 via a fuel evaporative gas passage 45.

Further, reference numeral 46 is an outer vent, 47 is an air intake port, and 48 is an outer vent.
49 indicates an exhaust valve, and 49 indicates a piston.

Next, the operation of the above embodiment will be explained.

When EGR is applied to the engine 1, that is, when the throttle opening is above a certain value and the intake air temperature is above a certain value, intake pipe negative pressure is transmitted to the negative pressure chamber 12 of the EGR valve 5 via the negative pressure line 16. be done.

When negative pressure is transmitted to the negative pressure chamber 12, the diaphragm mechanism 10
The diaphragm 11 of is attracted against the spring 13, thereby moving the control valve body 9 in the direction away from the valve seat 8,
As a result, the exhaust gas from the exhaust pipe 2 passes through the throttle 6 and the constant pressure chamber 7.
, will be circulated to the intake pipe 3 via the valve seat 8.

In this case, when the flow rate of exhaust gas is small, that is, when the amount of intake air of the engine is small, the pressure in the constant pressure chamber 7 and the pressure chamber 25 of the El:GR vacuum modulator 14 connected to it via the pipe 26 increases. The diaphragm 21 and control valve body 20 are pushed by the spring 27, the atmosphere communication hole 19 is opened, and the atmosphere is introduced into the negative pressure chamber 12 of the EGR valve 5 through the bleed pipe 11, so that EGR is not performed. .

That is, a negative pressure corresponding to the amount of intake air of the engine is transmitted to the negative pressure chamber 12 of the EGR valve 5, and similarly, a negative pressure corresponding to the amount of intake air of the engine is transmitted to the negative pressure chamber 41 of the VCV 37. become.

Therefore, the valve body 38 is connected to the negative pressure chamber 41 together with the diaphragm 39.
Since the opening 40 is opened according to the value of the negative pressure inside,
The opening degree of the opening 40 corresponds to the intake air amount of the engine.

This opening 40 passes from the charcoal canister 36 through the purge passage 35 to the air intake pipe 3 at the purge port 34.
Since the purge amount of fuel evaporative gas purged into the engine is controlled, this purge amount corresponds to the intake air amount of the engine.

As described above, the present invention is provided in the middle of an exhaust gas recirculation pipe that recirculates exhaust gas from the exhaust system to the intake system of an engine, and the recirculation pipe is opened and closed by a valve operated by a diaphragm mechanism. a diaphragm mechanism that is provided in the middle of a negative pressure pipe that introduces intake negative pressure into the negative pressure chamber of the diaphragm mechanism and that responds to the pressure of exhaust gas; In a fuel evaporative gas purge device for a fuel system of an engine equipped with a back pressure suppression type EGR device including a gGR vacuum modulator equipped with a control valve body for opening and closing atmospheric air introduction to A vacuum control valve is provided in the middle of the purge passage connecting the purge port formed in the negative pressure chamber, and the vacuum control valve opens only when the negative pressure in the negative pressure chamber is above a certain level according to fluctuations in negative pressure, and the vacuum control valve is provided in the negative pressure chamber. Since the intake negative pressure of the engine is introduced through the modulator, there is an excellent effect that a large amount of fuel evaporative gas can be purged without affecting the J-turn characteristics of the engine.

[Brief explanation of drawings]

The figure is a pipe diagram showing an embodiment of the fuel evaporative gas purge device according to the present invention. 1...engine, 2...exhaust pipe, 3...intake pipe,
4... EGR pipe line, 5... EGR valve, 7... Constant pressure chamber, 9... Control body, 10... Diaphragm mechanism,
12...Negative pressure chamber, 16...Negative pressure pipe line, 14...E
GR vacuum modulator, 19... atmospheric communication port,
20... Control valve body, 21... Diaphragm, 34...
...Purge port, 35...Purge passage, 36...
Charcoal canister, 31...VCV (vacuum control valve), 38...valve body, 40...opening, 41...negative pressure chamber, 43...negative pressure conduit.

Claims (1)

[Scope of utility model registration request] An EGR valve is provided in the middle of an exhaust gas recirculation pipe that recirculates exhaust gas from the exhaust system to the intake system of the engine, and opens and closes the recirculation pipe by a valve operated by a diaphragm mechanism; A diaphragm mechanism that is provided in the middle of a negative pressure pipe that introduces intake negative pressure into the negative pressure chamber and that responds to the pressure of exhaust gas, and a control valve body that opens and closes the introduction of atmospheric air into the negative pressure pipe by the diaphragm mechanism. In a fuel evaporative gas purge device for a fuel system of an engine equipped with a back pressure controlled EGR device including an EGR vacuum modulator, a purge passage connecting a fuel evaporative gas adsorption canister and a purge port formed in the intake passage of the engine is used. A vacuum control valve is provided that opens the negative pressure in the negative pressure chamber more than a certain value in response to fluctuations in negative pressure, and the engine intake negative pressure is introduced into the negative pressure chamber via the EGR vacuum generator. Fuel evaporative gas purge device.