JP2000320348A - Throttle control device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely prevent freezing of throttle valves. SOLUTION: If an engine started up is in a status of having potential icing (or step 103 is 'Yes'), a target throttle opening angle TAtg is varied over such a range between a first swivel angle taH and a second swivel angle taL as has no effect on the engine start-up quality in steps 110, 111 and 105. The throttle valve is thus swiveled across the target throttle opening angle TAtg so that freezing of the periphery of the throttle valve can be barred out.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a throttle control device for an internal combustion engine for preventing freezing of a throttle valve.

[0002]

2. Description of the Related Art An apparatus of this type is disclosed in, for example,
There is one described in JP-A-9-188050. In this device, a target throttle opening corresponding to the operating state of the internal combustion engine is obtained, and the opening of the throttle valve is adjusted to the target throttle opening by an actuator. By swinging in the vicinity of the opening, the throttle valve is prevented from freezing and sticking.

[0003]

However, in the above-described conventional apparatus, the throttle valve is swung to such an extent that the output torque of the internal combustion engine does not fluctuate, and the throttle valve is swung at a small angle. It's just that. Therefore, although icing is eliminated in a range near the target throttle opening, icing cannot be eliminated over a wide range in which the throttle valve is opened and closed. For this reason, when the target throttle opening greatly changes and the opening of the throttle valve greatly changes, ice may bite into the throttle valve, and the throttle valve may stick.

The present invention has been made in view of the above-mentioned conventional problems, and has as its object to provide a throttle control device for an internal combustion engine that can more reliably prevent icing of a throttle valve.

[0005]

SUMMARY OF THE INVENTION In order to solve the above-mentioned conventional problems, the present invention controls the opening of a throttle valve of an internal combustion engine so that it becomes a target throttle opening according to the engine operating state. When the engine temperature is low, a throttle control device for an internal combustion engine that executes additional control for swinging the throttle valve with respect to the target throttle opening determines whether or not the internal combustion engine is at a start before a complete explosion occurs. The control device includes a start-time determination unit and a permission unit that executes the additional control when the start-time determination unit determines that the start is before a complete explosion occurs.

According to the present invention, at the time of starting before a complete explosion occurs, additional control for swinging the throttle valve with respect to the target throttle opening is executed. At this start,
Even if the throttle valve is largely swung, the fluctuation of the output torque of the internal combustion engine is not greatly affected, and freezing can be eliminated over a wide range by the large swing of the throttle valve.

Further, the present invention controls the opening of a throttle valve of an internal combustion engine so as to be a target throttle opening in accordance with the operating state of the engine. In a throttle control device for an internal combustion engine that executes additional control for swinging, a fuel supply stop determination unit that determines whether or not fuel supply to the internal combustion engine is stopped, and a fuel supply stop determination unit When it is determined that the fuel supply has been stopped, a permission means for executing the additional control is provided.

According to the present invention, when the fuel supply to the internal combustion engine is stopped, the additional control for swinging the throttle valve with respect to the target throttle opening is executed. When the fuel supply is stopped, a change in the amount of intake air supplied to the internal combustion engine does not significantly affect the fluctuation in the output torque of the internal combustion engine. Therefore, the throttle valve can be largely swung, and icing can be eliminated over a wide range by the large swing of the throttle valve.

Further, the present invention controls the opening of a throttle valve of an internal combustion engine so as to be a target throttle opening in accordance with the operating state of the engine. In a throttle control device for an internal combustion engine that executes additional control for swinging, a rotational speed load determining means for determining whether the rotational speed of the internal combustion engine is low and the load on the internal combustion engine is high, and the rotational speed load determination A permission unit for executing the additional control when the rotation speed is determined to be low and the load is high by the means.

According to the present invention, when the rotational speed of the internal combustion engine is low and the load on the internal combustion engine is high, additional control for swinging the throttle valve with respect to the target throttle opening is executed. At such low rotation speed and high load, the opening range of the throttle valve in which the output torque of the internal combustion engine does not substantially fluctuate with the change in the opening degree of the throttle valve becomes large. Therefore, if the throttle valve is swung within this opening range, icing within the opening range can be eliminated without a change in output torque.

The present invention controls the opening of a throttle valve of an internal combustion engine so as to be a target throttle opening in accordance with the operating state of the engine. In a throttle control device for an internal combustion engine that performs additional control for swinging, an engine control amount of the internal combustion engine is controlled so as to offset a change in output torque of the internal combustion engine due to the additional control when the additional control is performed. It has a control means for changing.

According to the present invention, the engine control amount of the internal combustion engine is varied so as to cancel the variation of the output torque of the internal combustion engine accompanying the additional control. That is, even when the throttle valve swings, the output torque of the internal combustion engine does not fluctuate. As a result, the throttle valve can be largely swung, and icing can be eliminated over a wide range.

[0013]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a schematic diagram showing an embodiment of a throttle control device according to the present invention. In FIG. 1, an internal combustion engine (hereinafter referred to as an engine) 1 has a throttle valve 4
Is provided. This throttle valve 4 is provided with a throttle actuator 5 as an electronic control actuator.
Adjusts the opening degree, thereby adjusting the amount of air taken into the engine 1.

A piston 9 which reciprocates in the vertical direction in the figure is disposed in a cylinder 8 constituting a cylinder of the engine 1, and the piston 9 is connected to a crankshaft 11 via a connecting rod 10. Above the piston 9, a combustion chamber 13 defined by the cylinder 8 and the cylinder head 12 is formed. The combustion chamber 13 communicates with the intake pipe 2 and the exhaust pipe 3 via the intake valve 14 and the exhaust valve 15.

An intake port 17 of the engine 1 is provided with an electromagnetically driven injector 18 to which fuel (gasoline) is supplied from a fuel tank (not shown). The air supplied from the upstream of the intake pipe 2 and the injected fuel supplied by the injector 18 are mixed at the intake port 17, and the mixture becomes inside the combustion chamber 13 (in the cylinder 8) as the intake valve 14 opens. Flows into.
The air-fuel mixture that has flowed into the combustion chamber 13 is compressed therein, and is ignited by an ignition spark emitted from a spark plug 19 to explode. The engine 1 obtains rotational torque by this explosion. The gas after combustion is
The exhaust gas is exhausted to the exhaust pipe 3 via the exhaust valve 15.

Further, the cylinder 8 (water jacket)
Is provided with a water temperature sensor 21 for detecting the engine water temperature. Further, the crankshaft 11 outputs a pulse signal at every 720 ° CA (crank angle) according to the rotation state, and outputs a pulse signal at every constant crank angle (for example, 30 ° CA). A rotation speed sensor 23 is provided.

Further, an air flow meter 24 for detecting the amount of intake air and an intake temperature sensor 2 for detecting the temperature of the intake air (intake temperature) are provided upstream of the intake pipe 2.
9 are provided. An accelerator sensor 26 for detecting the amount of depression of the accelerator pedal 25 is provided on the accelerator pedal 25 which is depressed by the driver. A transmission (not shown) is provided with a shift sensor 28 for detecting a shift position of the transmission.

The cylinder head 12 is provided with a variable valve timing mechanism 27. The variable valve timing mechanism 27 adjusts the opening / closing timing of the intake valve 14 and the opening / closing timing of the exhaust valve 15 in response to the control of the ECU 30.

On the other hand, the ECU 30 has a well-known CPU, RO
It is mainly configured by a microcomputer including an M, a RAM, an I / O circuit, and the like. The ECU 30 includes a water temperature sensor 21, a reference position sensor 22, a rotation speed sensor 2,
3. Input detection signals of the air flow meter 24, the accelerator sensor 26, the shift sensor 28, and the intake air temperature sensor 29, and based on these various detection signals, the engine water temperature, the clan angle, the engine speed, the intake air amount, the accelerator opening degree. ,
Detects shift position and intake air temperature.

The ECU 30 calculates a fuel injection amount (or fuel injection time), an ignition timing, a target throttle opening, a valve timing, and the like based on various detection outputs from the sensor group. ,
The ignition of the ignition plug 19, the opening of the throttle valve 4 by the throttle actuator 5, and the opening and closing timing of the intake and exhaust valves by the variable valve timing mechanism 27 are controlled.

Now, in the device having such a configuration, the starting state of the engine 1, the state in which the rotation speed of the engine 1 is low and the load is high, and the state of the normal operation of the engine 1 are distinguished. The throttle valve 4 is swung in the mutually different opening degree ranges, thereby preventing icing of the throttle valve 4. The swing control of the throttle valve 4 for preventing icing will be described below with reference to the flowcharts shown in FIGS.

FIG. 2 is a flowchart showing swing control of the throttle valve 4 when the engine 1 is started.

First, when the ignition key 31 is turned on and the starter motor (not shown) is started, the ECU 30 determines that the engine is in the start mode (step 101, step 101).
Yes), based on a preset function f ₁ (THA),
A water temperature threshold value THWB corresponding to the intake air temperature THA detected by the intake air temperature sensor 29 is obtained (step 10).
2).

FIG. 5 shows the characteristics of the water temperature threshold value THWB with respect to the intake air temperature THA.
Is higher, the water temperature threshold value THWB is lower. If the coolant temperature THW detected by the coolant temperature sensor 21 is equal to or higher than the coolant temperature threshold THWB, no icing occurs around the throttle valve 4 and the coolant temperature T
If HW is less than the water temperature threshold THWB, icing occurs around the throttle valve 4.

The ECU 30 compares the coolant temperature threshold THWB with the coolant temperature THW detected by the coolant temperature sensor 21 (step 103). If the coolant temperature THW is equal to or higher than the coolant temperature threshold THWB (step 103). , N
o) Since there is no icing around the throttle valve 4, the swing angle dHL of the throttle valve 4 is set to 0 (step 104), the swing angle dHL (= 0), the base opening dg, and the water temperature correction. The opening degree dsta is added, and the sum is used as the target throttle opening degree TAtg of the throttle valve 4.
Is set (step 105), and by controlling the drive of the throttle actuator 5, the opening of the throttle valve 4 is adjusted to the target throttle opening TAtg.

The graph of FIG. 6 shows the characteristics of the target throttle opening TAtg at the time of starting with respect to the coolant temperature THW, and shows the characteristics when the swing angle dHL = 0.

The base opening dg is a predetermined constant value.

The water temperature correction opening dsta is determined by the water temperature T of the cooling water.
This is a value that varies according to the HW, and is obtained based on a function set in advance. As the water temperature THW is lower, the water temperature correction opening dsta is increased, and accordingly, the target throttle opening TAtg is increased, and the intake air amount is increased.
Startability is improved.

If the coolant temperature THW is lower than the coolant temperature threshold THWB (step 103, Yes), and there is a possibility that icing may occur around the throttle valve 4, the ECU 30 sets the ignition key 31 The step of starting the ON count value cigon indicating the ON period of is started (step 106). Then, the ECU 30 obtains a first time threshold value cigon1 corresponding to the coolant temperature THW detected by the coolant temperature sensor 21 based on a preset function f ₂ (THA), and calculates the ON count value cigon and the first time threshold value cigon1. Compare the time threshold value cigon1 (Step 1)
07). Immediately after the start of the on-count value cigon, the on-count value cigon becomes equal to the first time threshold value c.
less than icon1 (step 107, Yes). At this time, the ECU 30 sets the period in which the ON count value cigon increases by 8 as one cycle T, and sets the ON count value cigon
Is divided by 8 to determine the remainder of the period T based on the remainder (step 108).

In the first half of the period T (step 108,
Yes), the ECU 30 sets the function f ₃ (T
HW), a first swing angle taH of the throttle valve 4 corresponding to the coolant temperature THW detected by the coolant temperature sensor 21 is determined (step 109), and the swing angle dHL of the throttle valve 4 is determined by the first swing. The angle is set to taH (step 110), the swing angle dHL, the base opening d
g and the water temperature correction opening dsta are added, and the sum is set as a target throttle opening TAtg of the throttle valve 4 (step 105). By controlling the drive of the throttle actuator 5, the opening of the throttle valve 4 is reduced. It is adjusted to the target throttle opening TAtg.

In the latter half of the cycle T (step 1
08, No), the ECU 30 sets the function f ₄ set in advance.
Based on (THW), the second swing angle taL of the throttle valve 4 corresponding to the coolant temperature THW detected by the coolant temperature sensor 21 is determined (step 111), and the swing angle dHL of the throttle valve 4 is determined by the second swing. The moving angle taL is set (step 112), the swing angle dHL, the base opening dg, and the water temperature correction opening dsta are added, and the sum is set as the target throttle opening TAtg of the throttle valve 4 (step 105). ), The opening of the throttle valve 4 is adjusted to the target throttle opening TAtg.

Therefore, in the first half of the cycle T, the swing angle dHL is set as the first swing angle taH, and the target throttle opening TAtg including the first swing angle taH is set. The target throttle opening TAtg including the second swing angle taL is set as the movement angle dHL as the second swing angle taL.

Each time the flow chart of FIG. 2 is repeated, the ON count value cigon continues to advance, so that the first half and the second half of the cycle T are repeated, and accordingly, the opening degree of the throttle valve 4 becomes the first swing angle. The target throttle opening TAtg including taH and the target throttle opening TAtg including the second swing angle taL are alternately adjusted.

The graph of FIG. 7 shows the first swing angle t with respect to the coolant temperature THW detected by the coolant temperature sensor 21.
An aH characteristic curve 41 and a second swing angle taL characteristic curve 42 are shown. Set the target throttle opening TAtg to the second
The first swing angle taH and the second swing angle taL are set so that even if the swing angle is changed within the range from the swing angle taL to the first swing angle taH, the startability of the engine 1 is not hindered.

As described above, the first swing angle taH and the second swing angle taL are alternately added to the target throttle opening TAtg at each cycle T.
Atg increases or decreases, and the throttle valve 4 swings near the target throttle opening TAtg. As a result, icing around the throttle valve 4 is eliminated.

The graph of FIG. 8 shows a characteristic curve 43 of the target throttle opening TAtg and a characteristic curve 44 of the actual throttle opening TA with respect to the ON count value cigon.
As is clear from this graph, the target throttle opening T
Atg increases and decreases periodically.

After the icing around the throttle valve 4 is eliminated in this way, when the ON count value cigon becomes equal to or more than the first time threshold value cigon1 (step 107, N
o), the swing angle dHL of the throttle valve 4 is set to 0 (step 104), and the target throttle opening TAtg including the swing angle dHL (= 0) is set (step 10).
5) Return to the normal control of the throttle valve 4.

That is, in the flowchart of FIG. 2, if icing occurs when the engine 1 is started, the range of the second swing angle taL to the first swing angle taH that does not interfere with the startability of the engine 1. The target throttle opening TAtg is increased or decreased to swing the throttle valve 4 near the target throttle opening TAtg, thereby eliminating icing around the throttle valve 4.

Next, when the engine 1 is operated, the ignition key 31 is turned off, and it is determined that the engine is not in the start mode (step 101, No), the processing shifts to the processing in the flowchart of FIG.

FIG. 3 is a flowchart showing the swing control of the throttle valve 4 when the engine 1 is running at a low speed and the load is high.

First, the ECU 30 obtains a water temperature threshold value THWB corresponding to the intake air temperature THA detected by the intake air temperature sensor 29 based on a preset function f ₅ (THA) (step 201). Based on the obtained function f ₆ (THA), a vehicle speed threshold value SPDH corresponding to the intake air temperature THA is obtained (step 202).

The ECU 30 controls the shift sensor 28
The actual vehicle speed SP based on the shift position detected by the engine and the engine speed detected by the speed sensor 23.
D is obtained, and the actual vehicle speed SPD is compared with a vehicle speed threshold SPDH (step 203). If the actual vehicle speed SPD exceeds the vehicle speed threshold SPDH (step 203, Y
es), the ECU 30 sets the vehicle speed continuation count value cspdh to 1
The vehicle speed continuation count value cspdh is updated by adding 0 (step 204). If the actual vehicle speed SPD is equal to or lower than the vehicle speed threshold SPDH (step 203, N
o), the ECU 30 calculates 1 from the vehicle speed continuation count value cspdh.
Is subtracted to update the vehicle speed continuation count value cspdh (step 205).

Therefore, every time the flowchart of FIG. 3 is repeated, if the actual vehicle speed SPD exceeds the vehicle speed threshold value SPDH, the vehicle speed continuation count value cspdh increases, and the actual vehicle speed SPD becomes the vehicle speed threshold value. If SPDH or less, the vehicle speed continuation count value cspdh decreases.

Next, the ECU 30 determines a second time threshold value c corresponding to the coolant temperature THW detected by the coolant temperature sensor 21 based on a function f ₇ (THW) set in advance.
spdh2 is obtained, and the vehicle speed continuation count value cspdh is compared with the second time threshold value cspdh2 (step 20).
6). The vehicle speed continuation count value cspdh is equal to the second time threshold value c.
If it is less than spdh2 (step 206, No), E
The CU 30 compares the water temperature threshold value THWB obtained in Step 201 with the coolant temperature THW detected by the coolant temperature sensor 21 (Step 207). And
The vehicle speed continuation count value cspdh is equal to the second time threshold value cspd.
If h2 or more (Step 206, Yes), or if the coolant temperature THW is less than the coolant temperature threshold THWB (Step 207, Yes), the ECU 30 continues icing, which indicates the duration of the state in which icing occurs. Count value cas
Step ti (step 208). If the coolant temperature THW is equal to or higher than the coolant temperature threshold THWB (step 207, No), the ECU 30 ends the process of the flowchart in FIG. 3 and returns to step 101 in FIG.

As described above, in steps 201 to 207, the actual vehicle speed SPD exceeds the vehicle speed threshold value SPDH, and the vehicle speed continuation count value cspdh is changed to the second time threshold value csp.
spdh2 or more (step 206, Yes),
The state in which the vehicle speed at which the engine 1 is sufficiently cooled continues for a long time, or the coolant temperature THW is equal to the coolant temperature threshold THW
The state of being less than B (step 207, Yes) is determined. In such a state, icing occurs around the throttle valve 4.

If the icing continuation count value casti indicating the continuation time of the icing generation state is less than 3 seconds (step 209, No), the ECU 30 terminates the processing of the flowchart of FIG. 3 and proceeds to step 101 of FIG. Return to Also, E
If the icing continuation count value casti is 3 seconds or more (Step 209, Yes), the CU 30 opens and closes the intake / exhaust valve set by the engine speed NE detected by the speed sensor 23 and the valve timing variable mechanism 27. Using the timing Vt, a preset function f
_{8 A} dead throttle opening TA _PMWOT is _obtained based on (NE, Vt) (step 210).

The graph of FIG. 9 shows a characteristic curve 51 of the dead throttle opening TA _{PMWOT with} respect to the engine speed NE. The characteristic curve 51 of the dead throttle opening TA _{PMWOT is} a curve that _separates a sensitive region 54 where the intake air amount changes with respect to the throttle opening and a dead region 55 where the intake air amount does not substantially change. When the opening is set, that is, when the throttle opening is set in the dead zone 55, the intake air amount does not substantially change with a change in the throttle opening.

When the rotation speed of the engine 1 is low and the load is high (low rotation and high load), the dead zone 55 is expanded.

When the opening / closing timing Vt of the intake / exhaust valve is changed, the contents of the graph in FIG. 9 change.

In step 210, the detected engine speed NE and the intake / exhaust valve opening / closing timing V
The dead throttle opening TA _PMWOT corresponding to t is obtained.

After _{obtaining the} dead throttle opening TA _PMWOT in this manner, the ECU 30 obtains a temporary target throttle opening based on various detection outputs (operational states of the engine 1) by the sensor groups as described above. Target throttle opening t
-Compare TAtg with dead throttle opening TA _PMWOT (step 211). Then, the provisional target throttle opening degree t
If -TAtg is _{equal to} or greater than the dead throttle opening TA _PMWOT (step 211, Yes) and the tentative target throttle opening t-TAtg falls within the dead zone 55, that is, the rotational speed of the engine 1 is low and the load is high. Sometimes E
The CU 30 determines that the freezing continuation count value casti is 8
The period of time of increase is defined as one cycle T, and the icing continuation count value c
The value of the remainder obtained by dividing asti by 8 is determined, and it is determined whether the former is the latter half or the latter half of the cycle T based on this remainder (step 212).

In the first half of the period T (step 212,
Yes), the ECU 30 calculates the dead throttle opening TA
_PMWOT is set as the target throttle angle TAtg (step 213), and if it is the latter half of the cycle T (step 212, No), the fully opened throttle opening TA _imax is set as the target throttle angle TAtg (step 21).
4) By controlling the drive of the throttle actuator 5, the opening of the throttle valve 4 is adjusted to the target throttle opening TAtg.

Every time the flow chart of FIG. 3 is repeated, the freezing continuation count value casti keeps increasing.
And the target throttle angle TAtg is alternately set to the dead throttle opening TA _PMWOT and the full opening TA _imax , and the throttle valve 4
Swings. As a result, icing around the throttle valve 4 is eliminated.

FIG. 10 is a graph showing the freezing continuation count value cas.
Characteristic curve 4 of target throttle opening TAtg with respect to ti
5 and a characteristic curve 46 of the intake air amount GA. As is clear from this graph, the target throttle opening TA
Although the tg periodically increases and decreases, the target throttle opening TAtg is always in the dead zone 55, so that the intake air amount GA is kept constant.

That is, in the flowchart of FIG. 3, if the vehicle speed at which the engine 1 is sufficiently cooled continues for a long time, or if the coolant temperature THW is sufficiently reduced, icing around the throttle valve 4 occurs. It is considered to occur. The dead zone 55 is expanded in the low-rotation, high-load state, and the provisional target throttle opening degree t−TAt
If g is in the dead zone 55, the target throttle angle TAtg is alternately set to the dead throttle opening TA _PMWOT and the fully opened opening TA _imax , and the throttle valve 4 is swung, whereby the throttle valve 4 The icing has been eliminated.

Next, in a state where the vehicle speed at which the engine 1 is sufficiently cooled continues for a long time, or the coolant temperature THW is sufficiently reduced, and icing occurs around the throttle valve 4, the provisional target throttle opening degree is set. t-TAtg is less than the dead throttle opening TA _PMWOT (step 21).
1, No), if the tentative target throttle opening degree t-TAtg falls within the sensitive area 54, the process proceeds to the flowchart of FIG.

FIG. 4 is a flowchart showing the swing control of the throttle valve 4 in the normal operation state of the engine 1.

First, the ECU 30 uses the engine speed NE detected by the speed sensor 23 and the intake air amount GA detected by the air flow meter 24,
The torque TQ of the engine 1 is determined based on a function f ₉ (NE, GA) set in advance (step 301).

Subsequently, the ECU 30 sets a period in which the freezing continuation count value casti increases by 8 as the cycle proceeds to one cycle T, obtains a value obtained by dividing the freezing continuation count value casti by 8, and calculates the remainder value. It is determined whether the period is the first half or the second half of the cycle T (step 302).

In the latter half of the cycle T (step 302,
No), the ECU 30 determines the tentative target throttle opening t-TAtg based on the various detection outputs (the operating state of the engine 1) by the sensor groups as described above, and sets the tentative target throttle opening t-TAtg as the target. The throttle angle TAtg is set (step 303), and the throttle actuator 5 is drive-controlled to adjust the opening of the throttle valve 4 to the target throttle opening TAtg.

In the first half of the cycle T (step 3
02, Yes), the ECU 30 adds the preset opening K to the temporary target throttle opening t-TAtg, sets the sum as the target throttle angle TAtg (step 304), and sets the opening of the throttle valve 4 to the target throttle angle TAtg. It is adjusted to the target throttle opening TAtg. At the same time, the ECU 30
Is the target throttle opening TA based on a preset function.
determine the amount of intake air GAT corresponding to tg, the intake air amount GAT, the detected rotational speed NE of the engine 1, and using the torque TQ of the engine 1 obtained in step 301, the function f ₁₀ a preset Base spark plug 19
The retard amount rtd with respect to the ignition timing is calculated (step 30).
5) The ignition timing of the ignition plug 19 is shifted by the retard amount rtd.

This retard amount rtd is for keeping the torque TQ obtained in step 301 and not changing it even if the intake air amount is increased by adding the opening degree K. If only the ignition timing of the spark plug 19 is shifted, the torque TQ can be maintained.

Every time the flow chart of FIG. 4 is repeated, the freezing continuation count value casti keeps increasing, so that the cycle T
The first half and the second half are repeated, and accordingly, the target throttle angle TAtg repeatedly increases and decreases by the opening K, and the throttle valve 4 swings. As a result, icing around the throttle valve 4 is eliminated.

The graph of FIG. 11 shows the freezing continuation count value cas.
Characteristic curve 4 of target throttle opening TAtg with respect to ti
7 shows a characteristic curve 48 of the ignition timing retard amount rtd and a characteristic curve 49 of the torque TQ. As is clear from this graph, although the target throttle opening degree TAtg periodically increases and decreases, the torque TQ is kept constant because the ignition timing retard amount rtd is periodically shifted. .

That is, in the flowchart of FIG. 4, the vehicle speed at which the engine 1 is sufficiently cooled continues for a long time, or the water temperature THW of the cooling water is sufficiently reduced to cause icing around the throttle valve 4. So,
When the engine 1 is operating normally, the ignition plug 1
9, while periodically varying the target throttle opening TAtg by the opening K while periodically varying the ignition timing of 9, the throttle valve 4 is oscillated while the torque TQ is kept constant. Freezing around the valve 4 is eliminated.

Instead of the ignition timing of the spark plug 19, the fuel injection amount by the injector 18 or the opening / closing timing of each valve 14, 15 by the valve timing variable mechanism 27 is shifted, or the ignition timing, the fuel injection amount and the valve The throttle valve 4 may be swung while the torque TQ is kept constant by appropriately combining and shifting the opening / closing timing.

As described above, in the present embodiment, when the engine 1 is in the starting state, the target throttle opening degree TAtg is increased or decreased in the range from the second swing angle taL to the first swing angle taH which does not interfere with the startability of the engine 1. When the engine 1 is at a low rotation speed and a high load, the target throttle angle TAtg is alternately set to the dead throttle opening TA _PMWOT and the fully opened opening TA _imax. It repeatedly increases and decreases, thereby preventing freezing of the throttle valve 4.

Although not described in this embodiment, for example, when the vehicle is coasting down a long downhill on a mountain road,
Since the supply of fuel to the engine 1 is cut and the output torque of the engine 1 becomes zero, the throttle valve 4 may be swung. Specifically, the ECU 30 determines that the depression amount detected by the accelerator sensor 26 is 0,
In addition, coasting is determined based on the vehicle speed SPD not being zero, and fuel injection by the injector 18 is stopped to cut off the supply of fuel to the engine 1. Thereafter, the ECU 30
Is determined in steps 201 to 209 in FIG. 3 as to whether or not icing occurs in the vicinity of the throttle valve 4. If icing occurs, the target throttle opening TAtg is set to the fully open position and the fully closed position. And the throttle valve 4 is swung.

The present invention is not limited to the above embodiment, but can be variously modified. For example,
It is preferable to change the contents of each function according to the power characteristics of the engine. Further, each threshold value may be appropriately increased or decreased.

[0071]

As described above, according to the present invention, at the time of starting before a complete explosion occurs, additional control for swinging the throttle valve with respect to the target throttle opening is executed. At the time of this start, even if the throttle valve is largely swung, the fluctuation of the output torque of the internal combustion engine is not largely affected, and freezing can be eliminated over a wide range by the large swing of the throttle valve.

Further, according to the present invention, when the fuel supply to the internal combustion engine is stopped, additional control for swinging the throttle valve with respect to the target throttle opening is executed. When the fuel supply is stopped, a change in the amount of intake air supplied to the internal combustion engine does not significantly affect the fluctuation in the output torque of the internal combustion engine. Therefore, the throttle valve can be largely swung, and icing can be eliminated over a wide range by the large swing of the throttle valve.

Further, according to the present invention, when the rotational speed of the internal combustion engine is low and the load on the internal combustion engine is high, additional control for swinging the throttle valve with respect to the target throttle opening is executed. At such low rotation speed and high load, the opening range of the throttle valve in which the output torque of the internal combustion engine does not substantially fluctuate with the change in the opening degree of the throttle valve becomes large. Therefore, if the throttle valve is swung within this opening range, icing within the opening range can be eliminated without a change in output torque.

Further, according to the present invention, the engine control amount of the internal combustion engine is varied so as to cancel the variation of the output torque of the internal combustion engine accompanying the additional control. That is, even when the throttle valve swings, the output torque of the internal combustion engine does not fluctuate. As a result, the throttle valve can be largely swung, and icing can be eliminated over a wide range.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing one embodiment of a throttle control device of the present invention.

FIG. 2 is a flowchart showing swing control of a throttle valve when the engine shown in FIG. 1 is started.

FIG. 3 is a flowchart showing swing control of a throttle valve when the engine shown in FIG.

FIG. 4 is a flowchart showing swing control of a throttle valve in a normal operation state of the engine of FIG. 1;

FIG. 5 is a graph showing characteristics of a water temperature threshold THWB with respect to an intake air temperature THA of the engine of FIG. 1;

6 is a graph showing characteristics of a target throttle opening degree TAtg at the time of starting with respect to a coolant temperature THW of the engine cooling water of FIG. 1;

7 is a graph showing a characteristic of a first swing angle taH of a throttle valve with respect to a coolant temperature THW of the engine shown in FIG.
It is a graph which shows the characteristic of swing angle taL.

8 is a diagram showing a target throttle opening TAtg of the engine shown in FIG. 1;
5 is a graph showing characteristics of the actual throttle opening TA.

FIG. 9 is a graph showing characteristics of a dead throttle opening TA _{PMWOT with} respect to a rotation speed of the engine of FIG. 1;

10 is a diagram showing a target throttle opening TAt of the engine shown in FIG. 1;
7 is a graph showing characteristics of g and intake air amount GA.

11 is a diagram showing a target throttle opening TAt of the engine shown in FIG. 1;
6 is a graph showing characteristics of g, ignition timing retard amount rtd, and torque TQ.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Internal combustion engine (engine) 2 Intake pipe 3 Exhaust pipe 4 Throttle valve 5 Throttle actuator 8 Cylinder 9 Piston 10 Connecting rod 11 Crankshaft 12 Cylinder head 13 Combustion chamber 14 Intake valve 15 Exhaust valve 17 Intake port 18 Injector 19 Spark plug 21 Water temperature sensor 22 Reference Position Sensor 23 Speed Sensor 24 Air Flow Meter 25 Accelerator Pedal 26 Accelerator Sensor 27 Variable Valve Timing Mechanism 28 Shift Sensor 29 Intake Temperature Sensor 30 ECU 31 Ignition Key

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Katsura Masuda 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Corporation (72) Inventor Naoto Kushi 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Corporation F Terms (reference) 3G065 CA36 EA01 EA08 EA12 GA05 GA09 GA10 GA18 GA27 GA31 GA32 GA46 JA04 JA09 JA11 KA02 3G084 BA05 CA01 DA00 FA02 FA06 FA07 FA13 FA20 FA33 FA36

Claims (4)

[Claims] An additional control for controlling the opening of a throttle valve of an internal combustion engine so as to be a target throttle opening in accordance with an engine operating state, and swinging the throttle valve with respect to the target throttle opening when the engine temperature is low. In a throttle control device for an internal combustion engine that performs control, a start-time determination unit that determines whether or not the start is before a complete explosion of the internal combustion engine occurs; A throttle control device for an internal combustion engine, comprising: permission means for executing the additional control when it is determined that the engine is starting. 2. The method according to claim 1, further comprising controlling an opening of a throttle valve of the internal combustion engine to a target throttle opening in accordance with an operating state of the engine, and swinging the throttle valve with respect to the target throttle opening when the engine temperature is low. In a throttle control device for an internal combustion engine that performs control, a fuel supply stop determination unit that determines whether fuel supply to the internal combustion engine is stopped is stopped, and fuel supply is stopped by the fuel supply stop determination unit. A throttle control device for an internal combustion engine, comprising: a permission unit that executes the additional control when it is determined that the vehicle is in the state of performing the additional control. 3. The throttle valve of the internal combustion engine is controlled so as to have a target throttle opening in accordance with the operating state of the engine, and the throttle valve swings with respect to the target throttle opening when the engine temperature is low. In a throttle control device for an internal combustion engine that performs control, a rotational speed load determining unit that determines whether a rotational speed of the internal combustion engine is low and a load of the internal combustion engine is high, And a permission means for executing the additional control when it is determined that the load is low and the load is high. 4. An additional method for controlling the opening of a throttle valve of an internal combustion engine so as to attain a target throttle opening in accordance with an engine operating state, and swinging the throttle valve with respect to the target throttle opening when the engine temperature is low. In a throttle control device for an internal combustion engine that performs control, a control unit that changes an engine control amount of the internal combustion engine so as to cancel a change in output torque of the internal combustion engine due to the additional control when the additional control is performed. A throttle control device for an internal combustion engine provided.