JPS6030454Y2 - Solenoid valve for air-fuel ratio control in internal combustion engines - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to a solenoid valve for controlling the air-fuel ratio of an internal combustion engine.

Conventional technologyIn a device that uses a three-way catalyst to react and treat the three harmful components in exhaust gas, carbon monoxide, hydrocarbons, and nitrogen oxides, the air-fuel mixture has a concentration near the stoichiometric air-fuel ratio (A/F = 14.7). If you do not set this, you will not be able to achieve the intended purpose.

Therefore, engines with a carburetor are equipped with a solenoid valve that controls the amount of fuel or air supplied, detects the components in the exhaust gas, and controls the air or fuel by opening and closing the solenoid valve based on the results. , the air-fuel mixture with a concentration close to the stoichiometric air-fuel ratio is always supplied to the engine.

Problems to be Solved by the Invention However, in order to control the air-fuel ratio more accurately, it is desirable to control both fuel and air separately, but this requires two electromagnetic pieces, resulting in a complicated structure. There is a problem with becoming.

However, in order to supply the engine with a rich mixture when the engine temperature is low and a lean mixture when the temperature is high, there is an example of prior art in which separate control of both fuel and air is performed by a single solenoid valve. However, for example, it is described in Japanese Patent Publication No. 47-22027, but according to this, the solenoid valve is provided at the upper part of the float chamber, penetrates the top wall thereof, and has needle valves provided at the upper and lower ends, respectively. so as to engage an auxiliary air valve port located outside the float chamber and simultaneously open an auxiliary fuel valve port located far away from the valve port into the fuel within the float chamber, or vice versa. Because of this, it had the disadvantage of being large and having a complicated structure.

Means for Solving the Problems The object of the present invention is to provide a solenoid valve for controlling the air-fuel ratio of an internal combustion engine, which eliminates the above-mentioned problems and drawbacks.

In addition, in Japanese Patent Application Laid-open No. 49-85425, a case is provided with chambers on both sides of the diaphragm as a partition, valve ports facing each other on both sides of the diaphragm, and one valve port is closed by the diaphragm. A solenoid valve is shown which opens the other valve port at the same time, but this diaphragm connects the chambers on both sides and connects the chamber from one chamber communicating forward to the rear at the throttle point of the intake pipe. The other communicating chamber is provided with an opening for introducing the air from the front side of the intake pipe and further supplying it to the air chamber of the fuel tank.

Example This will be explained below with reference to the drawings.

In FIG. 1, 1 is an air cleaner, 2 is a carburetor, 3 is an air-fuel ratio control solenoid valve according to the present invention, 4 is a float chamber, and 5 is a solenoid valve for controlling air-fuel ratio.
6 is a main jet, and 6 is a fuel bypass, which communicates with the solenoid valve 3.

As shown in FIG. 2, the electromagnetic valve 3 is partitioned into a fuel side valve chamber 8 and an air side valve chamber 9 by a diaphragm 7, and a coil 10 is provided on the inner wall of the chamber 8. The core 11 of is fixed.

Housings 12 and 13 are inserted and fixed in both chambers 8°9, respectively.
Valve ports 14 and 15 provided at the tips of these valve ports are arranged to face each other on both sides of the diaphragm 7.

The diaphragm 7 is biased by a spring 16 and normally closes the valve port 15 of the housing 13 of the air side valve chamber 9.

Further, a bellows 17 is fixed to the diaphragm 7 to partition the chamber 8 and separate it into a fuel side chamber and a coil side chamber.

The bypass 6 is communicated with the fuel side valve chamber 8, and the pipe body 12 is connected to the main jet 5 via the bypass jet 18.
It joins the fuel passage.

On the other hand, the air side valve chamber 9 has a pipe 1 communicating with the air cleaner 1.
9 communicates with each other, and the pipe body 13 is connected to a slow air bleed pipe 20.
It communicates with the air bleed hole 21 of.

The coil 10 is connected via a control device 25 to an oxygen sensor 24 provided upstream of a three-way catalyst 23 in an exhaust passage 22 .

The oxygen sensor 24 operates when the oxygen concentration in the exhaust gas is below a set amount and activates the control device 25 to send current to the coil 10 to excite it, and when the oxygen concentration in the exhaust gas exceeds the set amount, the oxygen sensor 24 is activated. Therefore, the coil 10 is not activated.

In the figure, 26 is a suction passage, and 27 is a slow air jet.

With the above configuration, when the air-fuel ratio of the air-fuel mixture is higher than the stoichiometric air-fuel ratio and the oxygen concentration in the exhaust gas is higher than the set value, the sensor 24 will not operate and the coil 10 will not be excited, so the solenoid valve 3 As shown, the diaphragm 7 closes the valve port 15.

Therefore, the air bleed hole 21 is closed, while the valve port 14
is open, fuel flows from float chamber 4 to bypass 6.
, the air-fuel mixture is sent through the bypass jet 18, increasing the concentration of the air-fuel mixture and reducing the air-fuel ratio to approach the stoichiometric air-fuel ratio.

Further, when the air-fuel mixture becomes smaller than the stoichiometric air-fuel ratio and the oxygen concentration in the exhaust gas decreases, the sensor 24 is activated and the coil 10 is energized, causing the diaphragm 7 to stand biased against the spring 16, causing the valve The port 15 is opened and the valve port 14 is closed. Therefore, the air bleed hole 21 is opened 1 and air is supplied to the slow system, while the bypass 6 is closed, the fuel supply is stopped, the mixture becomes lean, and the air-fuel ratio is reduced. The air-fuel ratio can be increased to approach the stoichiometric air-fuel ratio.

Thus, according to the present invention, the air or fuel sent to the slow air bleed pipe 20 or the bypass jet 18 can be controlled in accordance with the oxygen concentration in the exhaust gas, so that the air-fuel ratio can always be maintained at the stoichiometric air-fuel ratio. .

Effects of the invention Particularly, according to the invention, control of the air and fuel that are supplied according to the oxygen concentration in the exhaust gas to bring the air-fuel ratio to the stoichiometric air-fuel ratio is performed using air that is disposed apart from the carburetor. child's room,
Using a diaphragm, which is a partition wall that separates the fuel supply side chamber, the diaphragm is simply placed separately in each of the above chambers according to the output of the oxygen sensor, and the air located opposite to both sides of the diaphragm is isolated. This is done by closing or opening the valve port that supplies fuel, and at the same time opening or closing the other valve port that supplies fuel, which is different from the above-mentioned prior art needle valve that moves up and down. The structure and operation are completely different, and a long needle valve is not required. Therefore, the structure is compact and simple, and the diaphragm is offset to the fuel supply side chamber, and the air supply side valve port is switched to open. The shock caused by this is alleviated by the fuel, and since the solenoid valve coil is located in the fuel supply side chamber, its temperature rise is suppressed by the fuel, and
Since the diaphragm is not provided with an opening, it can provide advantages such as good durability.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an exhaust gas purification device using a solenoid valve according to the present invention, and FIG. 2 is a sectional view of the solenoid valve according to the present invention. 1... air cleaner, 2... carburetor,
3...Solenoid valve, 4...Float chamber, 5
------- Main jet, 6... Bypass, 7... Diaphragm, 8°9... Chamber, 10... Coil, 11... ...core, 1
2.13...Pipe body, 14.15...Valve port, 16...Sufflink, 17...Bows, 18...Bybus Jet, 19...
...Pipe, 20...Slow air bleed pipe, 21
... Air bleed hole, 22 ... Exhaust passage, 23 ... Three-way catalyst, 24 ... Oxygen sensor, 25 ... Control device , 26...
Suction passage, 27...Slow air jet.

Claims (1)

[Scope of utility model registration request] A housing having a diaphragm as a partition and an air chamber and a fuel chamber that do not communicate with each other on the flow side thereof is arranged at a distance from the carburetor, and the housing has valve ports facing both sides of the diaphragm. A spring is installed in each of these chambers to bias the diaphragm to close one valve port, and an oxygen sensor installed in the exhaust passage compares the output with a set value and outputs an excitation signal when the output is below the set value. A control circuit for opening and closing one valve port is provided on the fuel chamber side, and a coil is provided on the fuel chamber side that operates to open the valve port by biasing the diaphragm against the spring by the excitation signal and simultaneously close the other valve port. The chambers on both sides communicate with the air cleaner and slow air bleed of the carburetor, the float chamber and the bypass jet, respectively, through the housing so that the air is controlled by the opening and closing of the other valve port, and the fuel is controlled by opening and closing the other valve port. A solenoid valve for controlling an air-fuel ratio of an internal combustion engine, characterized in that: