JPH0138182B2 - - Google Patents

Description

[Detailed Description of the Invention] (a) Industrial Application Field The present invention is mainly used for controlling 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. The present invention relates to an air-fuel ratio control device.

(b) Prior art As this type of air-fuel ratio control device,
As shown in No. 16804, it is detected whether or not the vehicle is decelerating by measuring engine speed, throttle opening, etc., and when it is determined that the vehicle is decelerating, an intervention is made in the slow system passage of the carburetor. The installed fuel cut valve is switched to the fuel cut position to suppress wasteful fuel consumption, and at the same time, a large amount of unburned gas is led to the exhaust system path during deceleration and burns in the catalyst bed, causing the inconvenience of causing so-called catalyst overheating. There are things that can be done to prevent this.

By the way, recently, for the purpose of reducing engine fuel consumption, the closing position of the throttle valve when the accelerator pedal is released has been changed to the normal idling state (engine speed is 800~800 rpm).
This refers to a state where the speed is approximately 1000 rpm. same as below. ) By setting the position closer to the closed position than the corresponding closed position, the engine speed during idling can be reduced.
Attempts have been made to lower the speed to around 600 rpm.

However, the engine speed at idling
If the speed is reduced to about 600 rpm and the fuel cut valve is operated during deceleration as in the prior art, the following problems will occur. In other words, if the closing position of the throttle valve is set further to the closed position than the closing position corresponding to normal idling operation in order to lower the engine speed during idling, the accelerator pedal will be released. When the automobile is decelerated by so-called engine braking, the negative pressure downstream of the throttle valve exhibits a value very close to vacuum. Therefore, if the fuel supply is cut during such deceleration, all the fuel in the flow system passage will be sucked out, leaving the inside of the slow port and intake manifold in a dry state, and the air-fuel ratio will rise to an abnormally high value. I get used to it. As a result, when moving from a decelerated state to steady or accelerated running, there is a time delay in the return of fuel, causing the engine to temporarily stutter or stop, resulting in poor drivability.

As shown in the previously filed Japanese Patent Application No. 57-189414, one way to solve this problem is to provide the aforementioned carburetor with an idle up mechanism so that the throttle valve can be adjusted to the set value from the idle switch. When a signal indicating that the throttle valve is closed is output and it is determined that the vehicle is in a deceleration mode, a fuel cut is performed and the idle up mechanism is activated to return the throttle valve to a normal idling operating state. There are some that are designed to open up to the vicinity of the corresponding position.

However, in this device, the idle switch that detects the opening degree of the throttle valve and the idle up mechanism that opens the throttle valve are provided independently of each other, so there is a problem that assembly and adjustment are difficult. In other words, in such a device, the idle position of the throttle valve, the idle up position, and the switching position of the idle switch must be set separately and have a certain relationship among them, so the idle up mechanism and There is a problem in that it takes a lot of effort to adjust the mounting position of the idle switch. If the adjustment is incorrect or the installation position is misaligned during use, and the idle switch switching position and idle up position are reversed, chattering may occur and normal control may not be possible. Therefore, there are disadvantages in that driveability deteriorates and catalyst overheating is likely to occur. In other words, if the setting position is reversed and the idle up position shifts to the open side rather than the idle switch switching position, the vehicle enters deceleration mode and the idle switch switches to the close signal output state, causing the fuel cut Immediately after the idle switch is turned on and the idle up is performed, the idle switch returns to the open signal output state and the fuel cut and idle up are released. The above operations are repeated while the vehicle continues to decelerate, making normal control impossible. Therefore, in such devices, a relatively large distance is provided between the idle up position and the idle switch switching position, or the idle switch is provided with hysteresis to make it difficult for the set position to reverse. However, it is not possible to reliably prevent such a reversal phenomenon.

(c) Purpose of the Invention The present invention has been made with attention to the above-mentioned circumstances, and it is easy to adjust, and moreover, the idle up position and the idle switch switching position are reversed and normal control cannot be performed. The inconvenience of
It is an object of the present invention to provide an air-fuel ratio control device during deceleration that can reliably prevent the fuel cut region from being unduly narrowed.

(d) Structure of the Invention In order to achieve the above object, the present invention determines that the vehicle is in a deceleration state based on a necessary condition that a closing signal is output from the idle switch, and at that time, In a device capable of simultaneously performing fuel cut and idle up, the idle switch is controlled by an actuating member having a fixed contact piece held by the actuating rod and moving back and forth in the direction of an operated lever of the throttle valve, and this actuating member. a driven member with a movable contact piece that is supported so as to be freely movable by a fixed distance (l) in a forward and backward direction and that moves toward and away from the operated lever as the operating member and the operated lever move relative to each other; and a biasing means that biases the movable contact piece in the forward direction to bring the movable contact piece into contact with the fixed contact piece, and when the throttle valve returns to the closed position, the driven member contacts the operated lever. The movable contact piece is pushed back to a position where it is locked to the actuating member, and the movable contact piece is separated from the fixed contact piece by a certain distance (l), while the throttle valve is opened and the actuating member is moved relative to the driven member. The opening signal can be output when the movable contact piece and the fixed contact piece come into contact with each other when the movable contact piece is locked at the most advanced position.

(e) Embodiment Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

In the figure, 1 is a carburetor for an automobile engine. The carburetor 1 has a normal configuration in which a fuel cut valve 2 is inserted in the middle of a slow system passage (not shown).
The closed position a (indicated by the two-dot chain line in Fig. 1) is set further toward the closed side than the closed position corresponding to the normal idling operating state. number is 650rpm
It has been reduced to a certain extent. The carburetor 1 is also provided with an idle-up mechanism 4 that moves the closed position a of the throttle valve 3 to a predetermined idle-up position b (indicated by a dotted line in FIG. 1), which will be described later, during operation. The idle up mechanism 4 is
It is mainly composed of a diaphragm mechanism 5. The diaphragm mechanism 5 activates the actuating rod 5 when atmospheric pressure is introduced into the diaphragm chamber 5a.
b protrudes from the tip 3 of the operated lever 3a provided on the throttle valve 3 via the idle switch 6.
a' to the closed position a of the throttle valve 3.
is moved to the idle up position b. The diaphragm chamber 5a of the diaphragm mechanism 5 is communicated with a portion 8a downstream of the throttle valve 3 in the absorption system 8 via a negative pressure introduction path 7. A VTV (negative pressure delay valve) 9 and a VSV (electric negative pressure switching valve) 11 are inserted in series in the middle. The VSV 11 connects the negative pressure introduction path 7 when the idle up release signal is input to its input terminal 11a, and shuts off the negative pressure introduction path 7 when the idle up signal is input to the input terminal 11a. Atmospheric air is introduced into the diaphragm chamber 5a. Further, the fuel cut valve 2 is maintained in an open state when a fuel cut release signal is input to its input terminal 2a, and when the fuel cut signal is input, the fuel from the slow system passage is completely removed. It is designed to switch to a state in which the fuel is cut off, or a state in which only a small amount of fuel is allowed to pass through. This fuel cut valve 2 and the VSV 11 of the idle up mechanism 4 are controlled to open and close by a control means 12. The control means 12 includes an idle switch 6 and a rotation sensor 13.
The ON and OFF states of the neutral switch 14 and clutch switch 15 are input information, and only when all of these are in the OFF state, a fuel cut signal is output to the fuel cut valve 2, and the fuel cut signal is outputted to the fuel cut valve 2. VSV11
This is an electric circuit configured to output an idle up signal to the idle switch 6, the rotation sensor 13, and the neutral switch 1.
4 and the clutch switch 15.
When in the ON state, a fuel cut release signal is output to the fuel cut valve 2, and an idle up release signal is output to the VSV 11. The rotation sensor 13 detects the rotation speed of the engine, and when the rotation speed exceeds a set rotation speed to be described later, the rotation sensor 13 outputs a high speed signal, that is, becomes an OFF state, and when it falls below, it outputs a low speed signal, that is, It is configured to be in the ON state. Further, the neutral switch 14 is set to be OFF when the transmission is in a position other than neutral and to be ON when the transmission is in neutral. moreover,
The clutch switch 15 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 idle switch 6 is fixed to the tip of the actuating rod 5b of the diaphragm mechanism 5, and is integrated with the actuating rod 5b.
The actuating member 16 moves back and forth in the direction of the operated lever 3a.
and a driven member 18, which is supported by the actuating member 16 so as to be freely movable by a certain distance l in the advancing and retracting direction, and moves toward and away from the operated lever 3a as the actuating member 16 and the operated lever 3a move relative to each other; A biasing means for biasing the driven member 18 in the forward direction is provided, for example, a coil spring 19. The actuating member 16 includes a casing 16a made of a highly conductive material and a bottomed cylindrical insulating body 16 fitted inside the casing 16a.
b, a locking wall 16c made of a highly conductive material riveted to the bottom wall of the insulating body 16b, and the insulating body 16
b and a fixed contact piece 16d made of a highly conductive material and sandwiched between the front wall of the casing 16a. On the other hand, the driven member 18 is formed by molding an insulating material into a rod shape, and the driven member 18 is formed by forming an insulating material into a rod shape.
It is housed in 7. Note that the tip end 18a of the driven member 18 penetrates the front wall of the casing 16a and projects to the outside. Further, a movable contact piece 18b made of a highly conductive material is fixed to the outer periphery of the base end side of the driven member 18, and a movable contact piece 18b made of a highly conductive material is fixed between the movable contact piece 18b and the locking wall 16c. The coil spring 19 is interposed therebetween. Then, this movable contact piece 18b is connected to the first lead wire 2 via the coil spring 19 and the locking wall 16c.
1, and the fixed contact piece 16d is connected to the second lead wire 22 through the casing 16a.
is connected to. Therefore, the driven member 18
is freely movable between a most retracted position where its base end contacts the locking wall 16c and is locked to the actuating member 16, and a most advanced position where the movable contact piece 18b contacts the fixed contact piece 16d. It has become possible to move freely. Therefore, only when the driven member 18 is held at the most advanced position, the idle switch 6 is turned ON, that is, outputs an open signal, and otherwise turns OFF, that is, outputs a close signal.

To explain the operation of this embodiment, first, during idling, the tip 3a' of the operated lever 3a of the throttle valve 3 comes into contact with the tip 18a of the driven member 18 of the idle switch 6, and the base end of the driven member 18 is in contact with the locking wall 16c, and the driven member 18 is in the most retracted position with respect to the actuating member 16. In this state, the idle switch 6 is turned OFF because the fixed contact piece 16d and the movable contact piece 18b are separated from each other.
Although the signal is output, the rotation sensor 13, neutral switch 14 and clutch switch 15
is ON, the control means 12 outputs a fuel cut release signal and an idle up release signal. Therefore, a state in which fuel cut is not performed is maintained, and a negative pressure in the intake pipe is introduced into the diaphragm chamber 5a of the diaphragm mechanism 5, so that the operating rod 5b of the diaphragm mechanism 5 is in the retracted position and the throttle valve 3 is closed. It is maintained at the closed position a, which is the initial setting position (see FIG. 3).

During operation, the opening degree of the throttle valve 3 increases, so the driven member 18 moves forward and moves the movable contact piece 18b.
reaches the position where it contacts the fixed contact piece 16d, that is, the most advanced position, and is held at this position. In this state, idle switch 6 is ON, so
Neither fuel cut nor idle up is performed (Figure 4).

During deceleration, the moment you take your foot off the accelerator pedal (not shown), the throttle valve 3 returns to the closed position a, and the driven member 18 of the idle switch 6 is also moved back by being pressed by the operated lever 3a (Fig. 5). ).

During the above deceleration, idle switch 6 is turned OFF again.
become. At this time, all other three output signals are also
OFF, that is, the engine speed is above the set value, the transmission is not in neutral, the clutch is engaged,
If all of the above conditions are actually maintained, the control means 12 outputs a fuel cut signal and an idle up mechanism signal. As a result, fuel cut is performed and the supply of fuel from the slow system passage is restricted or stopped, and atmospheric pressure is introduced into the diaphragm chamber 5a of the diaphragm mechanism 5, causing the operation rod 5b of the diaphragm mechanism 5 to be cut off.
protrudes, and the idle switch 6 is integrated with this protrusion.
The actuating member 16 advances, the driven member 18 of the actuating member 16 is pressed and moves forward, and the operated lever 3a is pressed by the driven member 18 and moves, so that the closed position a of the throttle valve 3 is Move to idle up position b (Fig. 6).

In other words, if at least one of ~ is no longer satisfied due to the vehicle stopping, etc., (a)
When at least one of the following three conditions is satisfied: the engine speed is below the set value, (b) the transmission is in neutral, and (c) the clutch is not engaged, the control means 12 issues a fuel cut release signal and an idle up signal. A release signal is output, the fuel cut is released, and at the same time, intake pipe negative pressure is introduced into the diaphragm chamber of the diaphragm mechanism 5, the actuating rod 5b and the idle switch 6 are moved back together, and the idle up is released (7th figure).

In addition, in the above embodiment, the case where a diaphragm mechanism was used as the idle up mechanism was explained, but it goes without saying that the present invention is not limited to such a mechanism. However, if a diaphragm mechanism is used, air enters the diaphragm chamber during startup and holds the operating rod in the protruding position, so the throttle valve does not reach the idle up position. The open position has the advantage of making starting easier.

Further, in the above embodiment, the control means is operated using not only the signal from the idle switch but also the signals from the clutch switch and the neutral switch. The present invention also includes those omitted.
However, if the clutch switch is omitted, the fuel cut may continue even if the clutch is depressed during deceleration, and the engine will stop the moment the biasing force transmitted from the wheels to the engine is cut off. This may cause inconvenience. Also, if the neutral switch is omitted, there is a risk that, for example, when the transmission is set to neutral and the engine is racing without load (the number of revolutions exceeds the set speed of the revolution sensor), a fuel cut will occur and the engine will stop. be. Therefore, in practice, it is desirable not to omit these clutch switches and neutral switches.

(c) Effects of the invention Since the present invention has the above configuration, the following effects () to () can be obtained.

() Since the throttle valve closing position is set closer to the closing position than the closing position corresponding to normal idling operation, the engine speed during idling can be kept low, reducing fuel consumption. be able to.

() When the engine brake is applied to decelerate, the control means as described above operates to switch the fuel cut valve to a closed state that allows only a small amount of fuel to pass through, or a state that cuts off all fuel. The closed position of the throttle valve is moved to the idle up position, which is slightly more open than the initial setting position.
It is possible to alleviate the phenomenon in which the intake pipe negative pressure exhibits a value extremely close to vacuum and the fuel in the slow system passage is sucked out all at once. As a result, the air-fuel mixture may temporarily become rich, leading to catalyst heating, or the inside of the slow port or intake manifold may become dry, making it difficult to restore fuel when decelerating to steady or accelerating driving. It is possible to effectively prevent inconveniences such as deterioration of drivability due to time delays and stalling of the engine when stopping after deceleration.

() When the idle up mechanism operates and the throttle valve moves to the idle up position, the driven member of the idle switch is held in the rearmost position relative to the operating member due to the reaction from the operated lever of the throttle valve. Therefore, the idle switch is kept in the OFF state, that is, in the closing signal output state. In other words, even if the idle is turned up, unless the throttle valve is further opened by a certain distance (l) from the idle up position, the idle switch will switch from the close signal output state to the open signal output state. I don't get it. Therefore, even if an error occurs in the idle up position due to poor adjustment, there is no inconvenience that the idle up position and the idle switch switching position are reversed, and the above-mentioned chatter can be reliably prevented from occurring. It is something that can be done.

() When manufacturing an idle switch, the free movement (l) of the driven member relative to the actuating member is determined, that is, the distance from the most retracted position where the driven member is locked to the actuating member when the operated lever is pressed, to the most advanced position. As long as the distance is accurately set in advance, the relative positional relationship between the idle up position and the switch switching position can be accurately defined. Therefore, the idle up mechanism and idle switch are integrated, and the above-mentioned reversal phenomenon cannot occur, making assembly and adjustment much easier than with conventional systems. It will be done.

() Also, since it is not necessary to set the idle up position and the idle switch switching position at positions separated from each other in consideration of the safety factor of preventing reverse rotation, the degree of freedom in position setting is increased and control is optimized. It is something that can be done. In particular, this device outputs an opening signal indicating that the throttle valve is open only when the driven member is locked at the most advanced position relative to the operating member and is in contact with the movable contact piece. There is. In other words, from the stage when the throttle valve approaches the closed position, the operated lever touches the driven member, and the movable contact piece separates from the fixed contact piece, the operated lever and driven member are actually activated by the actuating member. In a region corresponding to a certain distance (l) until the throttle valve is locked, a closing signal indicating that the throttle valve is closed is output, so that fuel cut is possible. Therefore, by appropriately setting the certain distance (l), the fuel cut region can be relatively freely defined without being restricted to the idle up position. That is, for example, a normal idle switch is provided at the tip of the actuating member in which a fixed contact piece and a movable contact piece contact and switch when the operating rod is pushed a certain distance, and the operating rod of the idle switch operates the throttle valve. When locking the operated lever of
The play in the operating lever of the idle switch does not play any role, and a closing signal can only be obtained when the throttle valve is completely locked. Therefore, the closing signal, which is a condition for performing fuel cut, is uniformly determined in accordance with the idle up position, making it impossible to freely expand the fuel cut region. In contrast, according to the present invention, by appropriately selecting the certain distance (l), the fuel cut area can be set relatively freely regardless of the idle up position. It is also possible to expand the fuel economy without difficulty and improve fuel economy.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, with FIG. 1 being a schematic circuit explanatory diagram, FIG. 2 being a front sectional view showing essential parts, and FIGS. 3 to 7 being action explanatory diagrams. 1... Carburetor, 2... Fuel cut valve, 3
... Throttle valve, 4... Idle up mechanism,
5b...Operating rod, 6...Idle switch, 12
...control means, 16...operating member, 16d...fixed contact piece, 18...driven member, 18b...movable contact piece, 19...
Biasing means (coil spring).

Claims (1)

[Claims] 1. A carburetor which is provided with a fuel cut valve in the middle of a slow system passage, and in which the closing position of the throttle valve is set further to the closed position than the closing position corresponding to the normal idling operation condition;
An idle-up mechanism is attached to this carburetor and moves the actuating rod toward the operated lever of the throttle valve during operation to shift the closed position of the throttle valve to a predetermined idle-up position, and detects the throttle opening. an idle switch that outputs an opening signal or a closing signal; and, on the condition that the idle switch outputs a closing signal, the fuel cut valve is switched to the fuel cut position and the idle up mechanism is activated. An air-fuel ratio control device during deceleration, comprising a control means for switching,
The idle switch is supported by an actuating member with a fixed contact that is held by the actuating rod and moves back and forth in the direction of the operated lever of the throttle valve, and is supported by the actuating member so as to be movable by a certain distance (l) in the forward and backward direction. a driven member with a movable contact piece that moves toward and away from the operated lever as the operating member and the operated lever move relative to each other; and a driven member with a movable contact piece that moves toward and away from the operated lever; and a biasing means for bringing the throttle valve into contact with the actuating member. While the movable contact piece is separated from the fixed contact piece by a certain distance (l), the throttle valve is opened and the actuating member is locked at the most forward position relative to the driven member, and the movable contact piece and the fixed contact piece are separated. An air-fuel ratio control device during deceleration, characterized in that it is capable of outputting the opening signal when the two contact each other.