JPS595172Y2 - Auxiliary fuel and fuel vapor control devices in internal combustion engines - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a control device for preventing auxiliary fuel and fuel evaporation in an internal combustion engine.

In an internal combustion engine equipped with an exhaust gas purification device having a thermal reactor, an auxiliary fuel supply device is provided to maintain the reaction in the thermal reactor, and the auxiliary fuel is supplied to the intake passage depending on the operating state of the engine. I have to.

On the other hand, a device equipped with a canister is provided to prevent fuel vapor generated during engine operation from escaping into the atmosphere.

In this device, activated carbon in the canister adsorbs fuel vapor, and when the suction pipe negative pressure exceeds a certain level, the purge control valve opens, sucking the fuel adsorbed by the activated carbon into the suction passage, and It is designed to be combusted.

In an internal combustion engine equipped with such a device, if fuel vapor is purged at the same time as auxiliary fuel is supplied, the air-fuel mixture becomes rich and the concentrations of carbon monoxide and hydrocarbons in the exhaust gas become excessive.

Especially when starting at low temperatures, the choke is activated.
Since the air-fuel mixture is rich, supply of auxiliary fuel and purging of fuel vapor must not be performed at the same time.Therefore, in this invention, when purging fuel vapor, the supply of auxiliary fuel is stopped and the fuel vapor is purged. To provide a device capable of maintaining an exhaust gas purifying effect by supplying auxiliary fuel when steam is not being purged, and stopping both when the choke is closed.

In addition, as an example of related prior art, Japanese Patent Application Laid-Open No. 48488
There is a method described in Publication No. 31, which automatically stops the operation of an engine equipped with an accelerating fuel increase device upon completion of warm-up. cannot prevent the tendency of overconcentration.

In contrast, the present invention stops both the supply of auxiliary fuel and the purge of fuel vapor when starting the engine, which performs choke operation, to prevent the mixture from becoming over-enriched. The fuel-air mixture concentration is always kept almost constant by stopping either the supply of auxiliary fuel or the purge of fuel vapor depending on the operating state of the fuel cell.

This will be explained below with reference to the drawings.

In the figure, 1 is a horizontally opposed cylinder type engine, 2 is an intake pipe, 3 is a carburetor, 4 is an auxiliary fuel supply device, and 5 is a canister.

The auxiliary fuel supply device 4 has a valve lower at the bottom of the float chamber 6, and a valve body 9 that closes the valve opening with a spring 8 is provided.

A pressure responsive device is provided above and opposite the valve body 9.

This device has a piston 11 fitted in a cylinder 10, and the piston is biased downward by a spring 13 provided between a collar 12 at the lower end and the lower wall of the cylinder. 9 to open the valve lower.

The valve lower communicates with the carburetor 3 through a pipe 14, and the negative pressure chamber in the upper part of the cylinder 10 communicates with a port 19 of a temperature switching valve 16 through a pipe 15.

The temperature switching valve includes a temperature sensing section 17 that senses the temperature of the engine coolant, a sliding spool 18 connected to the temperature sensing section, and ports 19, 20, and 21.

The canister 5 contains activated carbon, and the upper space inside the canister 5 communicates with the space inside the fuel tank 23 through a pipe 22, and also communicates with the suction pipe 2 through a purge control valve 24 and a pipe 25.

The purge control valve 24 has a negative pressure chamber 27 partitioned by a diaphragm 26 , and the negative pressure chamber communicates with an electromagnetic three-way valve 30 through a pipe 28 .

A normally open valve port 31 of the electromagnetic three-way valve communicates with the suction pipe 2 through a pipe 32 at an upstream opening 34 of a throttle valve 33, and a normally open valve port 35 communicates with the atmosphere.

The excitation coil of the electromagnetic three-way valve is connected to a power source 38 via a timer 36 and a main switch 37 so that it operates until the engine warms up.

Port 20 of temperature switching valve 16 communicates with pipe 28 through pipe 40, and port 21 communicates with pipe 25 through pipe 41.

Further, the pipe 28 is an advance chamber 42 of a negative pressure response device for controlling ignition timing.
It is communicated with by a pipe 43.

Next, the operation of this device will be explained.

During the time set by the timer 36 until the engine warms up, the timer contact is on, the coil of the electromagnetic three-way valve 30 is energized, the valve port 35 to the atmosphere is open, and the temperature switching valve 16 is open. Valve ports 19 and 21 are in communication.

The upper negative pressure chamber of the cylinder 10 of the auxiliary fuel supply device is connected to the pipe 15.
, valve ports 19, 21. The vacuum chamber 27 of the canister purge control valve 24 communicates with the atmosphere through a pipe 28 and a valve port 35.

When the choke 44 is closed in cold weather, the inside of the suction pipe is under negative pressure, and the piston 11 is lifted by the negative pressure, the valve body 9 is raised by the spring 8, the valve lower is closed, and the supply of fuel is stopped. .

On the other hand, the negative pressure chamber 27 of the purge control valve is at atmospheric pressure, the valve is closed, and fuel vapor is not purged.

Further, the advance angle chamber 42 of the ignition timing control device is also at atmospheric pressure and is retarded.

Next, when the engine coolant temperature exceeds the set value, the temperature switching valve 16 is activated, the spool 18 is lowered, and the port 1
9 and 20 are connected.

This causes the upper negative pressure chamber of the cylinder 10 to communicate with the atmosphere via the pipe 15, ports 19, 20, pipe 40.degree. 28, and valve port 35.

Therefore, the piston 11 is deflected downward by the spring 13, hits the valve body 9 and pushes it down, opening the valve lower and supplying auxiliary fuel. On the other hand, in the canister, the negative pressure chamber 27 of the purge control valve becomes large. At atmospheric pressure, the valve closes and no fuel vapor is purged.

Next, when the set time has elapsed and the contact of the timer 36 opens, the electromagnetic three-way valve 30 is demagnetized and the opening relationship of the valve ports changes.

That is, both the upper chamber of the cylinder 10 and the negative pressure chamber 27 are communicated with the suction pipe 2 through the valve port 31 and the pipe 32 .

When the throttle valve 33 is closed, the opening 34 is at atmospheric pressure and the upper chamber above the cylinder 10 is at atmospheric pressure, so that the piston 1
1 is moved downward by a spring 13, lowering the valve body 9 and opening the valve lower, and auxiliary fuel is supplied.

On the other hand, in the purge control valve, the negative pressure chamber 27 is at atmospheric pressure and no purge is performed.

At part load, the negative pressure in the opening 34 is high, so the purge control valve opens, and the fuel adsorbed on the activated carbon in the canister is sucked into the suction pipe through the pipe 25 by the suction pipe negative pressure.

On the other hand, the pressure in the upper chamber of the cylinder 10 becomes negative, the lower valve closes, and the supply of auxiliary fuel stops.

The negative pressure in the opening 34 becomes lower as the opening degree of the throttle valve becomes larger, and the negative pressure in the piston 1 decreases accordingly.
1 descends, pushes down the valve body 9, and fuel begins to be supplied,
Meanwhile, the purge control valve closes and purge is no longer performed.

Note that in place of the timer 36, a temperature switch may be provided that is closed until the engine temperature reaches a set temperature.

As is clear from the above, according to the present invention, depending on the operating state of the engine, fuel vapor purge can be stopped when auxiliary fuel is being supplied, and conversely, purge can be performed when auxiliary fuel is not being supplied. Furthermore, when the choke is closed when the engine is cold after starting, both can be stopped.

Therefore, the mixture concentration can be kept almost constant at all times, and the exhaust gas purification effect can be maintained.

[Brief explanation of the drawing]

The figure is a system diagram showing an embodiment of the present invention. 1...engine, 2...intake pipe, 3.
... Carburizer, 4... Auxiliary fuel supply device,
5... Canister, 6... Float chamber, 7... Valve port, 8... Spring, 9... Valve body, 10... ·····Cylinder,
11... Piston, 12... Tsuba, 13
...Spring, 14.15...Tube,
16...Temperature switching valve, 17...Temperature sensing part, 18...Spool, 19°20.21...
... Port, 24 ... Purge control valve, 25 ... Pipe, 26 ... Diaphragm, 27 ... Negative pressure chamber, 28 ... ··tube,
30... Solenoid three-way valve, 32... Pipe, 3
3... Throttle valve 1, 34...
Opening, 35... Valve port, 36... Timer, 37... Main switch, 38...
power supply.

Claims (1)

[Scope of utility model registration request] An auxiliary fuel supply device responds to the negative pressure in the engine's intake pipe, and when the negative pressure is low, a pressure-responsive device operates to open a valve to supply auxiliary fuel, and when the negative pressure is high, the pressure-responsive device operates to control purge. A fuel evaporation prevention device whose valve opens to purge the fuel vapor absorbed in the canister into the intake pipe, a switching valve and an electromagnetic three-way valve that operate according to changes in engine temperature are provided, and the negative pressure chamber of the auxiliary fuel supply device is It communicates with the suction pipe through the switching valve, and further communicates with the suction pipe or the atmosphere through the solenoid three-way valve, and communicates the negative pressure chamber of the purge control valve with the suction pipe or the atmosphere through the solenoid three-way valve, and controls the engine temperature. When the engine temperature is low, the negative pressure chamber of the auxiliary fuel supply system is connected to the suction pipe, and the negative pressure chamber of the purge control valve is connected to the atmosphere, and when the engine temperature reaches the set temperature, both negative pressure chambers are connected to the suction pipe. An auxiliary fuel and fuel vapor control device for an internal combustion engine, characterized in that the device is configured to communicate with the auxiliary fuel and fuel vapor control device.