JPS6030459Y2 - Air-fuel ratio compensator for internal combustion engines - Google Patents

Description

[Detailed explanation of the idea] The present invention relates to an air-fuel ratio compensator for an internal combustion engine.

When the engine temperature is low, the fuel supplied from the carburetor is not sufficiently vaporized, so at this time it is preferable to send hot air into the intake passage to promote the vaporization of the fuel.On the other hand, when the engine temperature is high, the fuel vaporization is suppressed. As the air-fuel mixture is sufficiently promoted, the air-fuel mixture supplied into the engine cylinder becomes too rich. Therefore, at this time, auxiliary air is supplied into the intake passage to prevent the air-fuel mixture supplied into the engine cylinder from becoming too rich. It is preferable.

As an air-fuel ratio compensator that can send high-temperature air into the intake passage when the engine is low and supply auxiliary air into the intake passage when the engine temperature is high, the connecting the related auxiliary air supply port to the air cleaner through an auxiliary air supply path, and providing an auxiliary air supply control valve device in the auxiliary air supply path;
A negative pressure diaphragm type switching valve is provided at the inlet of the air cleaner, and the negative pressure diaphragm chamber is connected to the auxiliary air supply control valve device.When the engine temperature is low, the supply of auxiliary air from the auxiliary air supply port is stopped and the switching valve is closed. Air-fuel ratio compensation in which heated air is introduced into the air cleaner by the switching action, while auxiliary air is supplied from the auxiliary air supply port when the engine is at high temperature, and ambient air is introduced into the air cleaner by the switching action of the switching valve. The device is known.

On the other hand, if you stop the engine when the engine temperature is high, the fuel in the carburetor float chamber will evaporate due to the high temperature of the carburetor, and this evaporated fuel will flow into the intake passage through the air vent etc. Fill up.

If you start the engine again in this condition, the air-fuel mixture supplied into the engine cylinders will become too rich, making it difficult to start, and even if the engine starts, an extremely rich mixture will be supplied into the engine cylinders. Idling becomes unstable and the engine stops.

As mentioned above, with conventional air-fuel ratio compensators, auxiliary air is supplied into the intake passage when the engine is at high temperature, but this amount of auxiliary air cannot sufficiently dilute the filtered rich mixture when the engine starts at high temperature; Therefore, there is a problem that a good start cannot be obtained.

The present invention utilizes the conventional air-fuel ratio compensator to increase the amount of auxiliary air supplied when the engine starts at a high temperature, thereby preventing the air-fuel mixture supplied into the engine cylinder from becoming too rich when the engine starts at a high temperature. An object of the present invention is to provide an air-fuel ratio compensating device.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

Referring to FIG. 1, 1 is an intake manifold, 2 is a carburetor fixed on the intake manifold 1, 3 is a carburetor throttle valve, 4 is a main nolls, 5 is an air cleaner mounted on the carburetor 2, 6 Reference numeral 7 indicates an element inserted into the air cleaner 5, 7 indicates an air installation port of the air cleaner 5, 8 indicates a heated air supply conduit arranged around the engine exhaust system, and 9 indicates a switching valve.

The switching valve 9 includes a negative pressure chamber 11 isolated from the atmosphere by a diaphragm 10, and a compression spring 12 for pressing the diaphragm is inserted into the negative pressure chamber 11.

The heated air supply conduit 8 is connected to the air intake lower at its outlet section 13, and the outlet sections 1 and 3 are controlled to open and close by a flow path switching plate 14.

One end portion 15 of the flow path switching plate 14 is rotatably pivoted on the inner wall surface of the air intake lower, and the center portion of the flow path switching plate 14 is connected to the diaphragm 10 via a rod 16.

On the other hand, as shown in FIGS. 1 and 2, an auxiliary air supply control valve device 18 is attached to the lower wall surface 17 of the air cleaner 5, and this auxiliary air supply control valve device 18 has a pair of partition walls 19. 1st chamber 2 divided into 3 by 20
1. It has a second chamber 22 and a third chamber 23.

The first chamber 21 is connected to the inside of the air cleaner 5 via an opening 24 formed in the upper wall surface of the first chamber 21 on the one hand, and to the negative pressure chamber 11 of the switching valve 9 via a conduit 25 on the other hand. Ru.

The second chamber 22 also includes an atmospheric air pipe 26 and an air filter 2.
7 and the third chamber 23 is connected via an auxiliary air supply conduit 30 to an auxiliary air supply port 29 opening into the carburetor air horn 28 downstream of the throttle valve 3 .

As shown in FIG. 2, a first valve port 31 and a second valve port 32 are formed on the partition wall 19 and 20, respectively, and a first valve integrally formed in the first valve port 31 and the second valve port 32 is formed in the first valve port 31 and the second valve port 32, respectively. A body 33 and a second valve body 34 are respectively arranged.

The first valve body 33 has a small diameter portion 33a, a conical portion 33b, and a large diameter portion 33c, and a first annular flow path 36 is formed between the first valve body 33 and the first valve port 31.

On the other hand, the second valve body 34 has a small diameter portion 34a, a conical portion 34b, and a large diameter portion 33c, and a second annular flow path 37 is formed between the second valve body 34 and the second valve port 32. .

As can be seen from FIG. 2, the cross-sectional area of the second annular flow path 37 is larger than that of the first annular flow path 36.

An on-off valve 38 for controlling the opening and closing of the opening 34 is integrally formed on the upper end of the small diameter portion 33a of the first valve body 33, and a seal member 39 is fixed on the on-off valve 38.

Further, a compression spring 40 is inserted between the on-off valve 38 and the gap 19, and the on-off valve 38 is always urged upward by the compression spring 40.

Further, the auxiliary air supply control valve device 18 has a temperature-sensitive wax valve 41 , and a temperature-sensing portion 42 of the temperature-sensitive wax valve 41 is disposed within the air cleaner 5 .

A control rod 43 protrudes from the lower end of the wax valve 41 , and the tip of the control rod 43 abuts the on-off valve 38 .

When the temperature inside the air cleaner 5 rises, the control rod 43 moves downward, thereby causing the first valve body 33 and the second valve body 34 to move downward.

The solid line in FIG. 4 shows the relationship between the diameter φ of the circular hole and the temperature T when the first annular flow path 36 formed around the first valve body 33 is converted into an equivalent circular hole. There is.

In FIG. 4, section A shows when the first annular flow path 36 is defined by the large diameter section 33c, and section B shows when the conical section 3
3b indicates the first annular flow path 36, and section C indicates the first annular flow path 36 is defined by the small diameter portion 33a.

From FIG. 4, when the temperature acting on the temperature sensing part 42 of the wax valve 41 is low, the cross-sectional area of the first annular flow path 36 is constant;
It can be seen that when this temperature increases, the cross-sectional area of the first annular flow path 36 increases, and when this temperature further increases, the cross-sectional area of the first annular flow path 36 remains constant.

On the other hand, an electromagnetic on-off valve 45 that is driven and controlled by a solenoid 44 is provided in the atmosphere communication pipe 26 connected to the second chamber 22 , and this solenoid 44 and a starter motor 46 are connected in parallel to a power source 47 .

The connection point between one terminal of the solenoid 44 and one terminal of the starter motor 46 is denoted by 48. A starter switch 49 is inserted between the connection point 48 and the power source 47, and a sensor is connected between the connection point 48 and the solenoid 44. The temperature switch 50 is inserted.

This temperature-sensitive switch 50 is a switch that is turned off when the engine temperature is extremely low, and is turned on at other times.

When the temperature-sensitive switch 50 is turned on, when the starter switch 49 is turned on, the starter motor 4 is turned on.
6 rotates and the solenoid 44 is energized.

When the solenoid 44 is energized, the electromagnetic on-off valve 45 opens, and at this time, the second chamber 22 communicates with the atmosphere via the atmosphere communication pipe 26.

When the engine is operated at a low temperature, the opening/closing valve 38 closes the opening 24, as shown in FIG.

At this time, as shown in FIG. 1, when the throttle valve 3 is closed, a large negative pressure is applied to the auxiliary air supply port 29, and this negative pressure is applied to the third chamber 23, the second chamber 22,
1 and into the negative pressure chamber 11 of the switching valve 9 via the conduit 25.

As a result, the diaphragm 10 rises, and the flow path switching valve 14 moves to the position shown by the broken line.

At this time, air heated by the engine exhaust system is sent from the heated air supply conduit 8 through the air cleaner 5 into the intake manifold 1, thereby promoting vaporization of the fuel.

When the engine temperature rises, the control rod 43 of the wax valve 41
Because of this protrusion, the opening/closing valve 38 opens the opening 24, and the inside of the first chamber 21 becomes approximately atmospheric pressure.

As a result, the negative pressure chamber 11 of the switching valve 9 also becomes almost atmospheric pressure.
The diaphragm 10 is lowered and the flow switching plate 14 closes the outlet 13 of the heated air supply conduit 8 .

Therefore, at this time, surrounding air is sent into the air cleaner 5 via the air intake lower.

On the other hand, as described above, since the first chamber 21 has almost atmospheric pressure, the air in the first chamber 21 flows through the second chamber 22, the third chamber 23, and the auxiliary air supply conduit 30 to the auxiliary air supply port 29.
is supplied into the air horn 28 from.

The auxiliary air flow rate is then determined by the first annular flow path 36.

When the engine temperature further increases, the control rod 43 of the wax valve 41 protrudes further, causing the first valve body 33 to move further downward.

As a result, as shown in FIG. 4, the flow area of the first annular flow path 36 becomes larger, so that the amount of auxiliary air supplied from the auxiliary air supply port 29 is increased.

On the other hand, when the engine is stopped when the engine is at high temperature, and then the starter switch 49 is turned on to start the engine again, the electromagnetic on-off valve 45 opens as described above, so that the second chamber 22 becomes atmospheric pressure. .

Therefore, at this time, the air in the second chamber 22 flows into the second annular flow path 37.
Air is also supplied into the air horn 28 from the auxiliary air supply port 29 via the third chamber 23 .

As described above, the cross-sectional area of the second annular flow path 37 is larger than that of the first annular flow path 36, so that a larger amount of auxiliary air is supplied into the air horn 28 when the engine is started at a high temperature than when the engine is idling at a high temperature.

As a result, even if fuel vapor accumulates in the intake anifold 1, the air-fuel mixture is diluted by the auxiliary air, thus preventing the air-fuel mixture supplied into the engine cylinders from becoming too rich.

The broken line in FIG. 4 shows the relationship between the diameter φ of the circular hole and the temperature T when the second annular flow path 37 is converted into an equivalent circular hole.

It can be seen from FIG. 4 that the cross-sectional area of the second annular flow path 37 changes as the temperature T increases in the same way as the first annular flow path 36.

In FIG. 3, the time required for starting is plotted on the vertical axis T, and the above-mentioned equivalent diameter φ is plotted on the horizontal axis, indicating the ease of starting.

It can be seen from FIG. 3 that there is an upper limit to the equivalent diameter φ in order to obtain good starting.

Taking these upper and lower limits into consideration, the equivalent diameter φ is kept constant in sections A and C in FIG. 4.

In the embodiment shown in FIG. 1, the temperature sensing part 42 of the wax valve 41 is disposed inside the air cleaner 5, but
2 can also be located in the carburetor float chamber or in the engine water jacket.

As described above, according to the present invention, it is possible to prevent the air-fuel mixture supplied into the engine cylinder from becoming too rich when the engine is started at a high temperature, so that a good start can be obtained and stable idling operation can be achieved after the engine is started. can be secured.

Furthermore, since the second valve body and the second valve port need only be provided in the conventional auxiliary air supply control valve device, there is an advantage that the conventional auxiliary air supply control valve device can be used without major changes.

[Brief explanation of the drawing]

Fig. 1 is a side sectional view of the engine intake system according to the present invention, Fig. 2 is an enlarged side sectional view of the auxiliary air supply control valve device of Fig. 1, and Fig. 3 is a diagram showing the time required for starting. FIG. 4 is a diagram showing changes in flow path cross-sectional area of the first valve body and the second valve body. 2... Carburizer, 3... Throttle valve,
9...Switching valve, 18...Auxiliary air supply control valve device, 24...Opening hole, 33...
First valve body, 34...Second valve body, 38...
・On-off valve, 45...Solenoid on-off valve, 49...
・Starter switch.

Claims (1)

[Scope of utility model registration request] An auxiliary air supply port opening in the intake passage downstream of the throttle valve is connected to the atmosphere via an auxiliary air supply passage, and an auxiliary air supply control valve device is provided in the auxiliary air supply passage to control the auxiliary air supply. a first valve body that cooperates with a first valve port formed in the auxiliary air passageway to control a flow cross-sectional area of the first valve port; In the air-fuel ratio compensator, the air-fuel ratio compensator includes a drive device that drives and controls a valve body, and increases the flow passage cross-sectional area of the first valve port as the engine temperature rises.
A second valve port is formed in the auxiliary air supply passage between the valve port and the auxiliary air supply port, and cooperates with the second valve port to increase the flow rate of the first valve port as the flow cross-sectional area of the first valve port increases. The second valve body that increases the flow passage cross-sectional area of the two valve ports is attached to the first valve body.
An on-off valve integrally formed with the valve body and connected to an auxiliary air supply passage between the first valve port and the second valve port and responsive to a starter switch is provided in the atmosphere communication pipe, and the starter switch is connected to the atmosphere communication pipe. An air-fuel ratio compensator for an internal combustion engine, which opens one on-off valve when turned on.