JPH05180038A - Air amount control device for engine - Google Patents

Abstract

PURPOSE:To prevent an idle speed from its excessive rise according to misoperation of an air control valve by connecting a subthrottle valve, mechanically associated with a throttle valve (main throttle valve), in series in a subpassage provided with the air control valve. CONSTITUTION:An intake passage 2 branches to a main passage 3 and a subpassage 4 to provide a main throttle valve 6, mechanically connected to an accelerator pedal, in the main passage 3 and an air control valve 11 in the subpassage 4. A subthrottle valve, arranged series to the air control valve 11 and further mechanically associated with the main throttle valve 6, is provided in the subpassage 4. The air control valve 11 is driven by a control unit so that engine generated torques before and after switching are equalized at the time of switching to lean air-fuel ratio.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine air amount control device.

[0002]

2. Description of the Related Art When an air-fuel mixture having a leaner air-fuel ratio than the stoichiometric air-fuel ratio is operated, the combustion efficiency is better than that of the stoichiometric air-fuel mixture, and the fuel efficiency is improved.
When a certain condition is satisfied, feedback control to the stoichiometric air-fuel ratio (or control to an output air-fuel ratio richer than the stoichiometric air-fuel ratio) is stopped, and an air-fuel ratio leaner than the stoichiometric air-fuel ratio (hereinafter referred to as lean air-fuel ratio). Is controlled as a goal. When the lean air-fuel ratio is reached, the air control valve provided in the auxiliary passage bypassing the throttle valve is opened to increase the air amount.

However, when the stoichiometric air-fuel ratio (or output air-fuel ratio) is switched to the lean air-fuel ratio, the torque that is transiently generated in the engine changes, and a torque step at the time of this switching causes a driving shock or rattling vibration. It may occur.

Therefore, as disclosed in Japanese Unexamined Patent Publication No. 63-50641, it is proposed to open the above air control valve corresponding to a predetermined target air-fuel ratio when switching to the lean air-fuel ratio. Has been done.

This is because the target air-fuel ratio changes stepwise with a step when switching to the lean air-fuel ratio, so the target air-fuel ratio is calculated with a waveform that changes with a first-order response delay so as not to occur, and this target air-fuel ratio is calculated. In response to the above, by increasing or decreasing the amount of air flowing through the sub passage, the driving shock due to the torque step at the time of switching is alleviated.

[0006]

By the way, in order to maintain the engine torque accurately and constant when switching to the lean air-fuel ratio, the flow passage area controllable by the air control valve is about 40% of the throttle valve area. And have to be quite big.

Therefore, the electronically controlled air control valve is
If the maximum opening is reached due to an erroneous signal, or if the air control valve is stuck in the fully open position, a large amount of air will be supplied to the cylinder from the auxiliary passage even if the throttle valve is returned to the fully closed position. Therefore, the idle rotation goes up too much.

Therefore, according to the present invention, an auxiliary throttle valve mechanically interlocking with a throttle valve (main throttle valve) is connected in series to the auxiliary passage provided with the air control valve, so that an idle operation caused by a malfunction of the air control valve is achieved. The purpose is to prevent excessive rise in rotation.

[0009]

According to a first aspect of the present invention, there is provided an intake passage branched into a main passage and a sub passage, a main throttle valve provided in the main passage and mechanically connected to an accelerator pedal, and the auxiliary passage. A sub-throttle valve provided in the passage and mechanically interlocking with the main throttle valve, an air control valve provided in the sub-passage in series with the sub-throttle valve, and a lean air-fuel ratio as a target of the control air-fuel ratio. The control device drives the air control valve so that the engine generated torque before and after the switching becomes the same when switching to the air-fuel ratio.

According to a second aspect of the present invention, the sub-passage is branched from the upstream side of the air flow meter in the first aspect.

According to a third aspect of the invention, in the first aspect of the invention, the air control valve comprises a diaphragm valve that opens and closes a sub passage in response to an operating pressure, and a three-way valve that switches the operating pressure supplied to the diaphragm valve. did.

A fourth invention is directed to an intake passage branched into a main passage and a sub passage, a main throttle valve biased by a return spring in a valve closing direction and mechanically connected to an accelerator pedal, and the main throttle valve. A sub-throttle shaft provided in parallel with the main throttle shaft for the throttle valve and penetrating the sub-passage, a sub-throttle valve fixed to the sub-throttle shaft, and slidably provided on the sub-throttle shaft, A lever that interlocks with the main throttle valve via a link, an interlocking switching lever that is fixed to the sub-throttle shaft and that abuts the lever by a spring that biases the sub-throttle valve in the valve opening direction, and actuates in the working chamber. In the state where the pressure is not introduced, the rod connected to the interlocking switching lever expands and contracts so as not to interfere with the movement of the auxiliary throttle valve. When dynamic pressure is introduced, a diaphragm actuator that rotates the interlocking switching lever in the valve closing direction through the telescopic rod until the sub-throttle valve settles in the fully closed position, and a three-way direction that switches the operating pressure supplied to the diaphragm actuator. And a valve.

A fifth aspect of the present invention is the fuel cell system according to the first or second aspect, wherein the auxiliary throttle valve is provided with a pressure (for example, VC) near the main throttle valve.
The diaphragm valve is configured to guide (negative pressure) to the working chamber, and the sub-passage is blocked or the flow rate of the sub-passage is reduced to a predetermined value or less when the main throttle valve has a predetermined opening or less.

[0014]

In the first aspect of the invention, the air control valve is fully closed and air flows only through the main passage unless the lean air-fuel ratio is targeted.

However, if the air control valve is suddenly fully opened due to an erroneous signal, the air flowing through the auxiliary passage flows while the accelerator pedal is being depressed, which increases the fuel amount and the engine rotation speed. Suddenly rises.

At this time, when the driver releases the accelerator pedal, the main throttle valve and the sub throttle valve which works in conjunction with the main throttle valve are closed, thereby reducing the amount of air taken into the cylinder, so that the engine speed returns to the original speed. The rotation is returned.

Also, when the air control valve is stuck in the open position due to a change with time, the air flow meter rotation is returned to a predetermined idle rotation by returning the accelerator pedal.

Further, if the air control valve has a variation in the flow rate, the air may enter too much when the intake air amount is low, and the torque may become too large when the lean air-fuel ratio is targeted. This also does not occur because the maximum air volume is limited by the auxiliary throttle valve.

When the auxiliary passage is branched from the upstream side of the air flow meter in the second aspect of the invention, even if the air control valve is opened to increase the air amount while keeping the fuel injection amount constant, the torque change is so small that it can be ignored. Therefore, the air-fuel ratio can be changed only by the air control valve when switching to the lean air-fuel ratio. Conversely, since the fuel injection amount can be kept constant before and after the switching, it is not necessary to synchronize the fuel injection amount and the air amount at the time of switching.

When the air control valve according to the third aspect of the present invention is composed of the diaphragm valve and the three-way valve, it is only necessary to open the diaphragm valve when switching to the lean air-fuel ratio, so that the control is simple and the cost is low. ..

The operation of the second and third inventions described here is in addition to the operation of the first invention.

According to the fourth aspect of the invention, even if the diaphragm actuator malfunctions, the auxiliary throttle valve works in conjunction with the main throttle valve, so that the engine can be restrained to an appropriate idle rotation as in the third aspect of the invention. Further, since the auxiliary throttle valve also serves as the air control valve, the layout is compact.

In the fifth aspect, when the air control valve is suddenly opened due to an erroneous signal and the accelerator pedal is released to return the main throttle valve to the fully closed position, the auxiliary passage is blocked or the auxiliary passage is closed. Is reduced below a predetermined value, which causes the engine to return to idle speed. This action is similar to that of the first or second invention.

[0024]

1 is a throttle housing,
Reference numeral 2 is an intake passage, 5 is a throttle shaft, and 6 is a throttle valve (main throttle valve).

One end of the throttle shaft 5 (the left end in the figure)
The accelerator drum 8 attached to is connected to an accelerator pedal (not shown) via a wire. The main throttle valve 6 is kept in the fully closed position by a return spring 9 which biases the main throttle valve 6 in the valve closing direction when the accelerator pedal is released, but when the accelerator pedal is depressed, it opens in response to this pedal.

The intake passage 2 is branched into a main passage 3 and a sub passage 4, and a disc-shaped sub throttle valve 7 is attached to the throttle shaft 5 which penetrates the sub passage 4 at the same angle as the main throttle valve 6. Be done. As a result, the auxiliary throttle valve 7 moves integrally with the main throttle valve 6.

When the amount of supplied fuel is constant and the sub passage 4 is opened by the rotary valve 11 which will be described later, the amount of air increases, so that the air-fuel mixture sucked into the cylinder becomes lean. Sub passage 4
Is close to the theoretical air-fuel ratio (14.7)
Lean air-fuel ratio (for example, 2
2 to 24), the sub passage 4 is opened at the same time.

By the way, if there is a torque step when switching to the lean air-fuel ratio, the drivability deteriorates, so the torque must be constant before and after the switching. Considering when switching to the lean air-fuel ratio, the change in the actual air-fuel ratio has a substantially first-order response delay waveform, and accordingly, the amount of air flowing into the cylinder has a substantially first-order response delay as shown in FIG. It is necessary to control the amount of air flowing through the sub passage 4 so as to increase. Therefore, at the opening of the sub passage 4,
A duty-controllable rotary valve (a pneumatic control valve, one of linear solenoid valves) 11 is provided. The rotary valve 11 is electronically controlled by a microcomputer or the like.

The rotary body 11a has a cylindrical portion protruding so as to block the sub passage 4, and a triangular slit 11b is formed in the cylindrical portion in the circumferential direction as shown in FIG. When the rotating body 11a is rotated in the direction of the arrow in FIG. 2, the overlapping portion (hatched portion) of the slit 11b and the sub passage 4 becomes large. The flow passage area of the sub passage 4 is changed by increasing or decreasing the overlapping portion (hatched portion).

On the other hand, O given to the solenoid coil 11c
The larger the duty value (ON time ratio) of the N-OFF pulse (ON / OFF at a constant cycle), the larger the rotation angle of the rotating body 11a (the rotation angle in the arrow direction in FIG. 2). The amount of air flowing through the passage 4 increases.

Therefore, at the time of switching to the lean air-fuel ratio, if the duty value is given to the rotary valve 11 so that the amount of air flowing to the cylinder increases in synchronization with the air-fuel ratio with a first-order lag, the torque is changed before and after the switching. It can be kept constant. Further, when the lean air-fuel ratio is changed to the stoichiometric air-fuel ratio or the like, by giving a duty value to the rotary valve 11 so that the amount of air flowing to the cylinder decreases with a primary delay, the torque is also constant before and after the change. Can be kept. When targeting the theoretical air-fuel ratio or the output air-fuel ratio, the rotary body 11a is returned to the position where the above-mentioned overlapping portion disappears, and the rotary valve 11 is closed.

The main throttle valve 6 has the same diameter as that of the base engine (normal three-way catalyst engine), and the sub-throttle valve 7 has an area so that a constant torque can be realized up to an air-fuel ratio of 22. It is about 40% of the main throttle valve 6.

FIG. 3 is a sectional view taken along the line AA in FIG. 1, in which a bypass air adjusting screw 13 is provided in a passage 12 that bypasses the auxiliary throttle valve 7 in order to adjust the flow rate when the auxiliary throttle valve 7 is fully closed. There is. Here, the operation of this example will be described.

Unless a lean air-fuel ratio is targeted, the rotary valve 11 is fully closed and air flows only through the main passage 3. At this time, the amount of air flowing into the cylinder is controlled by the main throttle valve 6 which works in conjunction with the accelerator pedal. According to the driver's will, if the accelerator pedal is depressed, the engine speed will increase, and if the accelerator pedal is returned, the engine speed will decrease.

However, even if the accelerator pedal is kept constant, if the rotary valve 11 is suddenly fully opened due to an erroneous signal, the air flowing through the sub passage 4 flows in addition to the air flowing through the main passage 3. In response to this, the fuel amount increases and the engine speed suddenly rises. Such a rise in engine speed is unexpected for the driver, but when the driver feels this and releases the accelerator pedal, the engine speed returns to the original speed. Even if the rotary valve 11 is opened, the sub-throttle valve 7 located in series therewith downstream thereof.
Since the flow rate of the sub passage 4 is controlled also by the above, when the main throttle valve 6 is closed by returning the accelerator pedal, the sub throttle valve 7 is also closed in conjunction with the main throttle valve 6 and thereby flows to the cylinder. The amount of air can be reduced.

This is provided with a so-called fail-safe function for coping with a case where the engine speed increases due to a malfunction of the electronically controlled rotary valve 11 regardless of the driver's intention.

Further, the rotary valve 1 is changed due to a change with time.
Even when 1 is stuck in the open position, it can be lowered to a predetermined idle speed only by operating the accelerator pedal. Even if the rotary valve 11 is stuck at the fully open position, when the accelerator pedal is released, the sub throttle valve 7 that works in conjunction with the main throttle valve 6 is also returned to the fully closed position.
Only a small amount of air flows through the passage 12 that bypasses, and the rotational speed settles down to a value determined by the amount of bypass air.

When the rotary valve 11 is fixed in the fully open position, depressing the accelerator pedal as much as it would normally would increase the flow passage area by the amount of the sub-passage 4 and increase the engine rotation speed quickly. Although,
The engine can be controlled from idle speed to high speed as in the engine without the sub passage 4.

On the other hand, in the conventional example in which the auxiliary throttle valve interlocking with the main throttle valve is not provided in the auxiliary passage, the air control valve is opened due to an erroneous signal or the position where the air control valve is opened due to aging. If stuck at, the amount of air cannot be reduced beyond the flow rate determined by the control valve opening at that time, and idle rotation will increase.

Further, in the conventional example, the air may excessively flow at a low intake air amount due to the variation in the flow rate of the air control valve, and the torque may become too large when the lean air-fuel ratio is targeted. However, since the maximum air amount is limited by the auxiliary throttle valve, this is not the case.

By the way, at the time of switching to the lean air-fuel ratio, by opening or closing the air control valve provided in the auxiliary passage with a primary response delay, the control itself for making the engine generated torque constant before and after switching has already been performed. It has been proposed (see JP-A-63-50641).

To explain this in brief, a control unit 20 composed of a microcomputer is provided as shown in FIG. 5, and an air amount signal from an air flow meter 15 provided upstream of the branch opening 4a of the auxiliary passage 4 and a crank angle sensor 16 are provided.
A crank angle signal from the throttle sensor 17 and a throttle valve opening signal from the throttle sensor 17 are input to the control unit 20.

The control unit 20 controls the amount of air flowing through the sub passage 4 by driving the rotary valve 11 as an air control valve based on the sensor information. The engine speed can be known by counting the pulses representing the crank angle.

FIG. 6 shows an interrupt process in which steps 2 to 4 are executed in synchronization with a clock signal of 10 ms, and step 6 is executed in synchronization with a crank angle reference signal Ref.

In step 2, the target fuel-air ratio (fuel-air ratio is the reciprocal of the air-fuel ratio) is calculated from the operating condition signal by a predetermined program and constant, and the result is stored in Tfbya of the register.

The value of Tfbya changes stepwise as shown in FIG. 4 when the operating condition is switched to the condition where the lean air-fuel ratio is targeted. On the other hand, since the actual fuel-air ratio changes with the first-order response delay in synchronization with the crank angle,
The actual fuel-air ratio that changes with this first-order lag is predicted by the following equation in step 6 (details in FIG. 7), and the result is Dfb of the register.
Store in ya. Dfbya = Tfbya ・ D # + old Dfbya ・ (1-D #) ...

However, in the equation, D # means a weighted average coefficient, and "old" means a previous value.

In step 3, the target duty (control valve opening) TDuty output to the rotary valve 11 is calculated according to the fuel-air ratio predicted value Dfbya thus obtained. Since the degree of the first-order lag taken into consideration in the equation changes depending on the magnitude of the engine load, it is desirable to determine it by also taking into consideration the throttle valve opening (engine load equivalent amount) TVO as shown in FIG. 8 (step 21, 22). The result is the register D
It is stored in the uty and is output to the rotary valve 11 as a duty drive signal (steps 23 and 24). If the lean air-fuel ratio is not met, the rotary valve 1
The target duty TDuty is set to 0 to keep 1 closed (steps 21 and 25).

In this way, when the rotary valve 11 is duty-controlled in accordance with the predicted fuel-air ratio value Dfbya, the amount of air flowing through the sub passage 4 is changed to the primary air-fuel ratio as shown in FIG. It increases with the delay.

On the other hand, the fuel injection pulse width Ti given to the injector (provided in the intake port) is calculated by the following equation (step 4). Ti = Tp, Tfbya, Coef, α + Ts ...

Where Tp is the basic injection pulse width determined from the engine speed and the air flow meter output,
Coef is the sum of the increase correction coefficients for increasing the fuel amount at low water temperature or at the time of starting, and α is the correction coefficient for performing feedback control of the air-fuel ratio near the stoichiometric air-fuel ratio to optimally operate the three-way catalyst, Ts Is a correction term (ineffective pulse width) based on the battery voltage.

A constant lean air-fuel ratio condition (for example, 80 ° C.)
When the above-mentioned cooling water temperature, partial load range, etc. are all satisfied), the formula becomes Ti = Tp · Tfbya + Ts, and Ti becomes slightly smaller than that before switching as shown in FIG. This is because the combustion efficiency is better when the fuel is burned at the lean air-fuel ratio, and if the fuel injection amount Ti is constant before and after the switching, there is a slight torque increase after the switching. It is possible to reduce the number before switching. In other words, this fuel difference improves fuel efficiency due to lean combustion.

FIG. 9 shows a second embodiment in which the sub passage 25 is provided so as to bypass the air flow meter 15 as well.

Also in this example, even when the rotary valve 11 is opened due to an erroneous signal or is stuck due to a change over time, the idle speed can be suppressed to an appropriate value, and the influence of variations in the flow rate of the rotary valve 11 can be suppressed. Do not receive This point is the same as in the first embodiment.

By the way, if the sub passage 25 is provided bypassing the air flow meter 15 as well, the air-fuel ratio can be changed by the rotary valve 11 under a constant fuel injection amount. This is because even if the rotary valve is opened with the fuel injection amount kept constant and the air amount is increased, the torque change is negligibly small (only 5 to 8% increase). Thus, if the fuel injection amount can be kept constant before and after the switching, it is not necessary to synchronize the fuel injection amount and the air amount at the time of switching. As a result, the fuel injection amount does not need to be matched (dynamic characteristic matching) so as to have a constant torque before and after the switching, and the switching dynamic characteristics are superior to those in the first embodiment.

An example of feedback controlling the amount of air flowing through the auxiliary passage 25 under the lean air-fuel ratio condition is shown in FIG. 10. Step 32 is performed in synchronization with a clock signal of 10 ms.
~ 34 is executed and the crank angle reference signal Ref is executed.
The air-fuel ratio feedback correction coefficient α is calculated in synchronism with (steps 31, 35, 36).

The air-fuel ratio feedback correction coefficient α is shown in FIG.
The calculation is performed based on the comparison between the target fuel-air ratio Tfbya and the actual fuel-air ratio fbya (the wide-range air-fuel ratio sensor is required to detect the lean air-fuel ratio) as in 1 (steps 43 to 49). The proportional component P and the integral component I are different from when the stoichiometric air-fuel ratio is targeted (step 42).

On the other hand, as shown in FIG. 12 (contents of step 33 in FIG. 10), the basic duty Duty0 is calculated from the target fuel-air ratio Tfbya and the throttle valve opening TVO, and this is multiplied by the air-fuel ratio feedback correction coefficient α, The result is stored in Duty of the register and is output to the rotary valve 11.

The fuel injection pulse width Ti is Ti = Tp.Tfbya.Coef + Ts ... (Step 34 in FIG. 10). Since the amount of air is feedback controlled, α is not included in the formula.

When the stoichiometric air-fuel ratio is set as a target, the fuel injection amount may be feedback-controlled.

FIG. 13 shows a third embodiment. This replaces the rotary valve 11 of FIG. 1 with a diaphragm valve 26 and a three-way valve 27, and only switches between ON and OFF (the diaphragm valve 26 is opened when switching to a lean air-fuel ratio).

In this example, even when the diaphragm valve 26 is stuck in the open state due to a change with time, the idle speed can be suppressed to an appropriate value.

Further, since the diaphragm valve 26 has only two positions, it is not possible to perform fine control according to the air-fuel ratio.
On the other hand, it is low in cost and is not affected by flow rate variations like a rotary valve. Further, since the accuracy of the air amount by the sub throttle valve 7 is better than that of the rotary valve, the variation in torque is small.

The sub passage 4 may be branched from the upstream side of the air flow meter as shown in FIG. In that case, the fine adjustment of the air-fuel ratio needs to be performed by the fuel injection amount.

FIGS. 14 to 16 show a fourth embodiment which is different from the above-mentioned three embodiments in that the auxiliary throttle valve 7 is not always linked with the main throttle valve 6 but only in the lean air-fuel ratio condition. The throttle valve 6 is interlocked, and when the stoichiometric air-fuel ratio is targeted, the interlocking is disconnected and the auxiliary throttle valve 7 is held at the fully closed position. The same parts as those in FIG. 1 are designated by the same reference numerals and the description thereof is omitted.

The throttle shaft 31 to which the sub throttle valve 7 is fixed is dedicated to the sub throttle valve, and is provided in a position parallel to the throttle shaft 5 for the main throttle valve as shown in FIG.

As shown in FIG. 15, the throttle shaft 31 has one end (the left end in the figure) protruding outside the throttle housing 1, and the lever 32 is provided at this protruding portion.
One end (lower end) of the shaft is slidably provided on the shaft 31, and the interlocking switching lever 33 is fixed to the shaft 31 by a nut 34 on the outer side thereof.

The other end (upper end) of the long plate lever 32 is shown in FIG.
As shown in FIG. 4, the accelerator drum 8 and the link 38 are connected to form a parallel motion mechanism.

The lever 32 is attached to one end (right end in FIG. 14) of the interlocking switching lever 33 by a return spring 35 for urging the sub throttle valve 7 in the valve opening direction (counterclockwise in FIG. 14). The ratio adjusting screw 36 is in contact. The elastic force of the spring 35 is made smaller than the elastic force of the return spring 9 that biases the main throttle valve 6 in the valve closing direction.

Therefore, when the accelerator pedal is depressed, the accelerator drum 8 rotates the main throttle valve 5 in the valve opening direction (counterclockwise direction in FIG. 14) against the spring 9. In response to this rotation, the lever 32 also rotates by the same angle via the link 38, and the interlocking switching lever 33 that contacts the lever 32 also rotates by the same angle. This interlocking switching lever 33
Since the sub throttle valve 7 and the sub throttle valve 7 are integrated, the sub throttle valve 7 also rotates by the same amount. That is, the auxiliary throttle valve 7 is linked with the main throttle valve 6. If you release the accelerator pedal from this state,
Due to the elastic force of the spring 9, the two throttle valves 6 and 7 are returned in the valve closing direction.

On the other hand, the interlocking switching lever 33 is connected to the diaphragm actuator 42 fixed to the housing 1 via the telescopic rod 41. One end (bottom end in Fig. 14)
The telescopic rod 41 connected to the interlocking switching lever 33 is
As shown in FIG. 16, the upper end of the telescopic rod 41 is provided so as to be capable of expanding and contracting in the axial direction of the rod 42a, and if the negative pressure is not introduced into the working chamber 42c of the diaphragm actuator 42, the telescopic rod 41 is connected to the interlocking switching lever 33. It does not interfere with movement. That is, in the state where the negative pressure is not introduced, the telescopic rod 41 is not restricted by the half bearing 43 shown in FIG.

On the other hand, when a negative pressure is introduced into the working chamber 42c, the diaphragm spring 42d and the return spring 35 are overcome and the rod 42a is pulled upward in FIG. , The rod 42 with the maximum extension
It is pulled up with a. By pulling up the telescopic rod 41, the interlocking switching lever 33 rotates clockwise in FIG. 14 regardless of the lever 32 that abuts against it, and the sub throttle valve 7 is held at the fully closed position.

In this state, the main throttle valve 6 and the sub throttle valve 7 are disengaged from each other, and the sub throttle valve 6 remains in the fully closed position even when the accelerator pedal is fully depressed. That is, when the negative pressure is introduced into the working chamber 42c, the sub throttle valve 7 is fully closed so that air does not flow in the sub passage 4, and only the main throttle valve 6 is opened and closed in response to the accelerator pedal.

Therefore, a negative pressure is introduced into the diaphragm actuator 42 under the condition that the stoichiometric air-fuel ratio is targeted,
Also, the three-way valve 44 must be switched so that the atmosphere is introduced under the lean air-fuel ratio condition. This switching is shown in FIG.
The opposite of the example.

In this example, even if the diaphragm actuator 42 cannot pull up the telescopic rod 41 due to a malfunction, the auxiliary throttle valve 7 works in conjunction with the main throttle valve 6, so that FIG.
Similar to 3, the idle speed can be suppressed to an appropriate value, and the auxiliary throttle valve 4 also serves as an air control valve, so that the layout can be made compact.

Further, since the air amount when the sub throttle valve is fully closed can be adjusted by loosening the lock nut 37 and moving the adjusting screw 36 in and out, the bypass passage 12 shown in FIG. 3 (same in the example of FIG. 13) can be used. It is not necessary to provide the bypass air adjusting screw 13 again, and the layout is compact in this respect as well.

Furthermore, since the sub-throttle valve 7 that also serves as an air control valve seals when the sub-passage 4 is shut off under the condition that the stoichiometric air-fuel ratio is the target, a seal like the diaphragm valve 26 in FIG. It eliminates the need for valves that require reliability.

FIG. 17 shows the fifth embodiment. This is
In place of the auxiliary throttle valve 7 in FIG. 9 and FIG. 9, a normally closed diaphragm valve 51 is provided, and a VC negative pressure downstream of the throttle valve (main throttle valve) 6 in the working chamber 51a (at atmospheric pressure, throttle valve opening is (The pressure that gradually approaches the intake pipe pressure as it increases)
Is introduced through the negative pressure passage 52, and when the throttle valve 6 becomes equal to or smaller than a predetermined opening (that is, at the time of idling), the diaphragm valve 51 is closed and the sub passage 4 is shut off. 53
Is an opening hole for adjusting the idle speed.

Also in this example, when the rotary valve 11 is suddenly opened due to an erroneous signal, the accelerator pedal is released to return the throttle valve 6 to the fully closed position, so that the diaphragm valve 51 is closed.
Is closed and the engine is returned to idle speed.

In this example, the auxiliary passage 4 is cut off when the throttle valve 6 has a predetermined opening or less, but the flow passage area of the auxiliary passage 4 is reduced to a predetermined value or less when the throttle valve 6 has a predetermined opening or less. You can also At this time, since the idle rotation is determined by the amount of air flowing through the diaphragm valve portion, the opening hole 53 becomes unnecessary. The sub passage 4 may be branched from the upstream of the air flow meter.

Although the rotary valve 11 shown in FIGS. 1, 9, and 17 is driven by a linear solenoid, it may be driven by a step motor.

[0082]

As described above, according to the first aspect of the invention, the intake passage branched into the main passage and the sub passage, the main throttle valve provided in the main passage and mechanically connected to the accelerator pedal, and the sub passage. A sub-throttle valve provided mechanically with the main throttle valve, an air control valve provided in the sub-passage in series with the sub-throttle valve, a different air-fuel ratio as a target of the control air-fuel ratio, and a lean air-fuel ratio. At the time of switching to the fuel ratio, the control device that drives the air control valve so that the torque generated by the engine before and after the switching is the same is provided, so the air control valve is stuck due to being opened by an erroneous signal or being opened due to aging. Even in such a case, the idling speed can be suppressed to an appropriate value and the flow rate of the air control valve is not affected.

In the second aspect of the present invention, the auxiliary passage is branched from the upstream side of the air flow meter in the first aspect of the invention. Therefore, in addition to the effect of the first aspect of the invention, the fuel injection amount is kept constant when switching to the lean air-fuel ratio. Therefore, the dynamic characteristics of switching can be improved.

According to a third aspect of the present invention, the air control valve in the first aspect comprises a diaphragm valve that opens and closes the sub passage in response to an operating pressure, and a three-way valve that switches the operating pressure supplied to the diaphragm valve. Therefore, even when the diaphragm valve sticks in the open state due to aging, it can be suppressed to an appropriate idling speed and the cost is low.

In the fourth aspect of the invention, the main throttle valve and the sub-throttle valve are interlocked by using the parallel motion mechanism only under the condition that the lean air-fuel ratio is aimed, and under the other conditions, the interlocking is separated by the diaphragm actuator and the sub-throttle valve is disconnected. Since the valve is held in the fully closed position, even if the diaphragm actuator does not operate due to a malfunction, the idle speed can be suppressed to an appropriate value as in the third aspect of the invention, and the layout is compact. it can.

According to a fifth aspect of the present invention, in the first or second aspect of the present invention, the sub-throttle valve is a diaphragm valve that guides the pressure in the vicinity of the main throttle valve to the working chamber. Since the passage is blocked or the flow rate of the auxiliary passage is reduced to a predetermined value or less, the same effect as the first aspect of the invention can be obtained.

[Brief description of drawings]

FIG. 1 is a sectional view of a throttle housing portion of a first embodiment.

FIG. 2 is a perspective view of a rotary valve rotating body.

3 is a cross-sectional view taken along the line AA of FIG.

FIG. 4 is a waveform diagram for explaining the operation of the first embodiment.

FIG. 5 is a system diagram of the first embodiment.

FIG. 6 is a flowchart showing job interruption processing.

FIG. 7 is a flowchart showing a subroutine of FIG.

FIG. 8 is a flowchart showing a subroutine of FIG.

FIG. 9 is a sectional view of a throttle valve portion according to a second embodiment.

FIG. 10 is a flowchart showing job interruption processing.

11 is a flowchart showing a subroutine of FIG.

FIG. 12 is a flowchart showing a subroutine of FIG.

FIG. 13 is a sectional view of a throttle housing portion of a third embodiment.

FIG. 14 is a sectional view of a throttle housing portion of a fourth embodiment.

15 is a cross-sectional view taken along the line AA of FIG.

FIG. 16 is a sectional view of a diaphragm rod.

FIG. 17 is a sectional view of a throttle valve portion according to a fifth embodiment.

[Explanation of symbols]

 2 Intake passage 3 Main passage 4 Sub passage 5 Throttle shaft 6 Main throttle valve 7 Sub throttle valve 11 Rotary valve (Air control valve) 15 Air flow meter 16 Crank angle sensor (engine speed sensor) 17 Throttle sensor 20 Control unit 25 Sub passage 26 diaphragm valve 27 three-way valve 31 auxiliary throttle shaft 32 lever 33 interlocking switching lever 35 return spring 38 link 41 telescopic rod 42 diaphragm actuator 44 three-way valve 51 diaphragm valve 52 negative pressure passage

Claims (5)

[Claims] 1. An intake passage branched into a main passage and a sub passage, a main throttle valve provided in the main passage and mechanically connected to an accelerator pedal, and a main throttle valve provided in the sub passage and the machine. Engine that has different air-fuel ratios as a target of the control air-fuel ratio and that has a different air-fuel ratio as the target of the control air-fuel ratio. An air amount control device for an engine, comprising: a control device that drives the air control valve so that generated torques are the same. 2. The air quantity control device for an engine according to claim 1, wherein the auxiliary passage is branched from an upstream side of the air flow meter. 3. The air control valve comprises a diaphragm valve that opens and closes a sub passage in response to an operating pressure, and a three-way valve that switches the operating pressure supplied to the diaphragm valve. The air volume control device for the engine described. 4. An intake passage branched into a main passage and a sub passage, a main throttle valve biased in a valve closing direction by a return spring and mechanically connected to an accelerator pedal, and a main throttle valve for this main throttle valve. A sub-throttle shaft provided in parallel with the main throttle shaft and penetrating the sub-passage, a sub-throttle valve fixed to the sub-throttle shaft, and slidably provided on the sub-throttle shaft,
A lever that interlocks with the main throttle valve via a link, an interlocking switching lever that is fixed to the sub-throttle shaft and that abuts the lever by a spring that biases the sub-throttle valve in the valve opening direction, and actuates in the working chamber. In the state where no pressure is introduced, the rod connected to the interlocking switching lever expands and contracts so as not to interfere with the movement of the sub-throttle valve. An engine air characterized by comprising a diaphragm actuator for rotating the interlocking switching lever in a valve closing direction until the sub-throttle valve is settled to a fully closed position, and a three-way valve for switching an operating pressure supplied to the diaphragm actuator. Quantity control device. 5. The sub-throttle valve is constituted by a diaphragm valve that guides the pressure in the vicinity of the main throttle valve to the working chamber, and shuts off the sub-passage when the main throttle valve has a predetermined opening or less or the flow rate of the sub-passage is less than a predetermined value. The air amount control device for an engine according to claim 1 or claim 2, wherein