JPS624666Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an air-fuel ratio control device during deceleration, which is used to control the air-fuel ratio of the air-fuel mixture supplied from the carburetor to the combustion chamber of the engine during deceleration of an automobile. .

Vehicles equipped with exhaust gas purification measures using catalysts have the disadvantage that they are prone to so-called catalyst heating during deceleration. In other words, in a normal engine, an operating condition that is likely to occur when the vehicle is decelerated by engine braking, that is, an operating condition in which the boost pressure is closer to vacuum than approximately 580 mmHg (shown with diagonal lines in Figure 1) (see area)
Misfires are likely to occur under these conditions. When a misfire occurs, a large amount of unburned gas is guided into the exhaust system and burns on the catalyst bed, causing an inconvenience in that the temperature of the exhaust system rises abnormally. Therefore, recently, a fuel cut valve is inserted into the slow system passage of the carburetor to cut the amount of fuel supplied from the slow system passage during deceleration, or to limit the amount of fuel supplied from the slow system passage to a very small value. Fuel tanks that prevent overheating and minimize wasteful fuel consumption are becoming more common.

On the other hand, in a car equipped with an air conditioner and the compressor of the air conditioner driven by engine power, the throttle valve of the carburetor is set to the normal idling position only while the air conditioner is operating. Operating status (engine rotation speed
This refers to a state where the speed is approximately 800 to 1000 rpm. (The same applies hereafter) A device that can increase the idling speed of the engine by shifting it to the open side by a predetermined angle, for example, about 7 degrees, from the closed position corresponding to the closed position, that is, a device equipped with a so-called idle up function. There are quite a few.

However, in a vehicle that has both the fuel cut function and idle up function described above, there is a risk that inconveniences may occur during deceleration. In other words, when the engine brake is applied and the fuel cut function is activated when the engine idles up, the opening of the throttle valve is relatively large and the slow system passage is blocked or nearly blocked, so the main system of the carburetor is Fuel flows out of the circuit and is supplied to the engine. In this case, for example, as shown in Figure 1, even if the throttle valve is opened by about 7 degrees due to idle up, the engine rotates at a speed of approximately 3000 rpm or more due to the urging force from the wheels during engine braking. Under such conditions, the boost pressure is -580
Because it is closer to vacuum than mmHg, the engine is more likely to misfire. Therefore, even though slow system fuel cut is performed, a large amount of unburned gas due to gasoline sucked out from the main nozzle may be led to the exhaust system path and cause catalyst heating.

Furthermore, with such a configuration, there is also the disadvantage that engine braking becomes difficult to apply due to increased idle.

Furthermore, these phenomena are particularly noticeable in engines whose idle speed has been lowered to about 600 rpm in recent years to improve fuel efficiency.

The present invention was developed by focusing on the above-mentioned circumstances, and uses a carburetor that has a fuel cut valve in the middle of the slow system passage, and a case where the state of power transmission from the engine to the wheels is maintained. OFF to
A judgment circuit that is connected in parallel with a clutch switch and a vacuum switch that turns OFF when the boost pressure moves closer to vacuum than a predetermined value, and a judgment circuit that is connected to a power supply through this judgment circuit. a fuel cut control means for switching a fuel cut valve to a fuel cut state when the fuel cut valve is in a non-conducting state; All of the above-mentioned inconveniences can be overcome by providing an idle-up control means for shifting the closed position of the throttle valve of the carburetor from the closed position corresponding to normal idling operation to the open side. To provide an air-fuel ratio control device during deceleration, which can solve the problem and also reduce the possibility of engine stop when the fuel cut is released and expand the fuel cut area easily and reliably.

Hereinafter, one embodiment of the present invention will be described with reference to FIG.

A carburetor 1 of an automobile engine is provided with fuel cut control means 4 for simultaneously controlling the open/close state of a fuel cut valve 2 and the closed position of a throttle valve 3 of the carburetor 1. The carburetor 1 has a normal configuration in which the fuel cut valve 2 is inserted in the middle of a slow system passage (not shown). ) is in the closed position b (second position) corresponding to the normal idling operating condition.
(shown by the solid line in the figure) is set to the closed side, which reduces the rotational speed during idling to about 600 rpm. On the other hand, the fuel cut control means 4 controls the needle pot 5.
When atmospheric pressure is introduced into the diaphragm chamber 5a of the dart pot 5, the rod 5h protrudes and presses the arm 3a provided on the throttle valve 3 to bring the throttle valve 3 into the closed position. a to near the closed position b. The diaphragm chamber 5a of the dart pot 5 is communicated with a portion 7a of the intake system passage 7 downstream of the throttle valve 3 via a negative pressure introduction passage 6.
A VTV (negative pressure delay valve) 8 and a VSV (electric negative pressure switching valve) 9 are inserted in series in the middle.
The VSV 9 is configured to connect the negative pressure introduction path 6 when the input terminal 9a is energized, and to cut off the negative pressure introduction path 6 and introduce atmospheric air into the diaphragm chamber 5a when the input terminal 9a is turned off. It's summery.
The input terminal 9a of the VSV 9 is connected to a battery 15 through a judgment circuit 13 formed by connecting a clutch switch 11 and a vacuum switch 12 in parallel, and an ignition switch 14 in series. The clutch switch 11 is turned off when the clutch for transmitting engine power to the wheels is in the connected state, and turned on when the clutch is in the disconnected state.
Further, the vacuum switch 12 is turned OFF when the negative pressure in the portion 7a downstream of the throttle valve 3, that is, the boost pressure, reaches a predetermined value, for example, 580 mmHg, to the vacuum side, and the hysteresis is 20 mm.
For items with Hg, when the pressure is more than 560mmHg,
It is set to be ON. Further, when the input terminal 2a is energized, the fuel cut valve 2 is in an open state, that is, a state in which no fuel cut is performed, and when the power is cut off, the fuel cut valve 2 is in a closed state, that is, a state in which a fuel cut is performed. It's meant to be. Note that even in the closed state, this fuel cut valve 2 may allow only a small amount of fuel to pass through, or
It is also possible to completely cut off the passage of fuel. The input terminal 2a of the fuel cut valve 2 is connected to a battery 15 via the determination circuit 13 and the ignition switch 14 in series.

Further, in such a device, the vaporizer 1
An idle up control means 16 is attached to the engine. The idle up control means 16 has a dart pot 17.
The rod 17b is configured to move in the retracting direction when negative pressure is introduced into the diaphragm chamber 17a. And this darth pot 1
When the rod 17b of No. 7 moves in the retracting direction, the actuating rod 18a of the link mechanism 18 moves in the direction of arrow Closed position c set further to the open side than position b
It is beginning to shift to . However,
Diaphragm chamber 17a of this dart pot 17
is connected to a portion 7a downstream of the throttle valve 3 in the intake system passage 7 via a negative pressure introduction passage 19, and a
VSV20 is inserted. When the input terminal 20a of the VSV 20 is energized, the negative pressure introduction path 1
9 is placed in a communicating state, and when electricity is cut off, the negative pressure introduction path 18 is cut off and the diaphragm chamber 17a is opened.
Atmosphere is now being introduced into the atmosphere. The input terminal 20a of this VSV20 is used to turn on the cooling device.
- It is connected to a battery 15 via an OFF switch 21, an idle-up release switch 22, a judgment circuit 13 of the fuel cut control means 4, and an ignition switch 14.

Next, the operation of this device will be explained separately for cases A and B. A: When the air conditioner is not in operation, or when the air conditioner is in operation but the idle release switch 22 is turned OFF.

At this time, since the power to the VSV 20 is cut off, the diaphragm chamber 17 of the dart pot 17
Atmospheric pressure has been introduced to a, and idle up has been canceled. Then, the ignition switch 14 is ON and at least one of the clutch switch 11 or the vacuum switch 12 is ON.
In other words, if the boost pressure is more than 560 mmHg and the clutch is in the connected state, the boost pressure is more than 560 mmHg and the clutch is in the disconnected state, and the boost pressure is on the vacuum side of 580 mmHg and the clutch is in the disconnected state, the fuel cut valve 2 and the
Both VSV9 become energized. Therefore, the state in which fuel cut is not performed is maintained, and the diaphragm chamber 5a of the dart pot 5 is closed.
Negative pressure is introduced into the intake pipe, and the rod 5b of the dart pot 5 is retracted, so that the closed position a of the throttle valve 3 is maintained at the initial setting position shown by the two-dot chain line in FIG. On the other hand, if both the clutch switch 11 and the vacuum switch 12 are turned OFF, in other words, the boost pressure shows a value on the vacuum side of 580 mmHg, such as when decelerating by applying the engine brake, and the clutch is in the connected state. If there is
The fuel cut valve 2 and the VSV
Power to 9 is cut off. Therefore, a fuel cut is performed to limit or stop the supply of fuel from the slow system passage, and at the same time, atmospheric pressure is introduced into the diaphragm chamber 5a of the dart pot 5, causing the rod 5b of the dart pot 5 to protrude and the throttle valve 3 to open. The closed position a is moved to the vicinity of the closed position b, which corresponds to the normal idling operation state.

When the B cooling system is in operation and the idle-up release switch 21 is ON.

During steady operation, that is, when driving under conditions A, , the clutch switch 1 is
Since either VSV1 or VSV12 is in the ON state, VSV2 of the idle up control means 16
0 is the energized state. Therefore, negative pressure is introduced into the diaphragm chamber 17a of the dart pot 17, the rod 17a is retracted, and the actuating rod 18a protrudes in the direction of arrow Move it to the open side from the position b. In other words, it is in an idle up state. In this case, as explained in A above, fuel cut is not performed. On the other hand, if both the clutch switch 11 and the vacuum switch 12 are turned OFF, in other words, the boost pressure shows a value on the vacuum side of 580 mmHg, such as when decelerating by applying the engine brake, and the clutch is in the connected state. , the VSV of the idle up control means 16
Since the power supply to 20 is cut off, idle up is canceled. At the same time, as described in A, the power to the fuel cut valve 2 and VSV9 is cut off, so the fuel cut is performed and the supply of fuel from the slow system passage is restricted or stopped, and the rod of the dart pot 5 is cut off. 5b protrudes, and the closed position a of the throttle valve 3 is moved to the vicinity of the closed position b, which corresponds to the normal idling operating state. In addition, when the vehicle is stopped or accelerated from such a fuel cut state, for example, by disengaging the clutch, the clutch switch 11 is turned ON at the moment the clutch is disengaged, and the judgment circuit 13 is turned on. Switch. As a result, the dart pot 17 is operated to perform idle up and release the fuel cut. Therefore, it is possible to effectively prevent the engine from stopping due to a delay in the return of fuel at the moment when the clutch is released and the reverse driving force from the wheels to the engine is released.

As described above, both the idle up function and the fuel cut function are performed, but in this device, the boost pressure is increased to 580°C by decelerating the vehicle using the engine brake.
If the temperature becomes closer to vacuum than mmHg, idle up is immediately released. Therefore, to effectively prevent the inconvenience that fuel flows out from the main system passage of the carburetor 1 at the time of fuel cut and is supplied to an engine in a misfiring state, and that unburned gas is led to the exhaust system and causes catalyst overheating. I can do it. Moreover, in the deceleration driving range where the idle up is canceled by this device, the engine speed is maintained at a high value by the urging force from the wheels, so even if the idle up is canceled, the cooling system cannot be operated. You can continue without any inconvenience. Therefore, by adopting this device, the operational range of the cooling device will not be narrowed at all. In addition, by doing this, the throttle valve 3 can be moved to the closed position b corresponding to the normal idling operation state during deceleration.
Since it is held nearby, there is no problem such as difficulty in applying the engine brake when the air conditioner is activated, which is the case with systems equipped with a normal idle up mechanism. Furthermore, if the configuration as described above is adopted, the judgment circuit 1 of the fuel cut control means 4
3 can also be used as a judgment circuit for the idle-up control means 16, so the number of parts is small, the structure is simple, and implementation is easy. Moreover, as mentioned above, if the clutch is disengaged while the air conditioner is operating and deceleration is being performed by engine braking, idle up by the dart pot 17 is immediately resumed and the fuel cut is released. It is possible to prevent the inconvenience of the engine stopping the moment the reverse driving force from the wheels to the engine is cut off. Therefore, it becomes possible to expand the fuel cut area easily and effectively, and the special effect of improving fuel economy is also obtained.

Note that the configuration of the fuel cut control means is of course not limited to that of the embodiment described above, and may be, for example, a normal one that does not have a dart pot 5 or the like for controlling the closing position of the throttle valve 3. Good too.

Since the present invention has the above-described configuration, it is possible to reliably eliminate the inconveniences such as when idle up and fuel cut are executed at the same time, which leads to catalyst heating and engine braking becomes difficult to apply. By properly using the idle up control means, the engine stop that tends to occur when the deceleration state is released can be effectively prevented, and the fuel cut area can be expanded easily and effectively. A fuel ratio control device can be provided.

[Brief explanation of the drawing]

Figure 1 is a diagram to explain the characteristics of the engine.
FIG. 2 is an explanatory circuit diagram showing an embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Carburetor, 2... Fuel cut valve, 3... Throttle valve, 4... Fuel cut control means, 11... Clutch switch, 1
2... Bakyume switch, 13... Judgment circuit,
16... Idle up control means.

Claims (1)

[Scope of claim for utility model registration] A carburetor with a fuel cut valve in the middle of the slow system passage, a clutch switch that turns OFF when power transmission from the engine to the wheels is maintained, and boost pressure. A judgment circuit is connected in parallel with a vacuum switch that turns OFF when the value moves closer to vacuum than a predetermined value. a fuel cut control means for switching a fuel cut valve to a fuel cut state in a certain case; 1. An air-fuel ratio control device during deceleration, comprising idle up control means for shifting the closed position of a tuttle valve to an open side from a closed position corresponding to a normal idling operating state.