JPH0577870B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a throttle valve control device for an engine, and particularly to a throttle valve control device that feedbacks the throttle valve opening in order to obtain a predetermined intake air amount with respect to an accelerator operation amount that indicates a required engine output. Concerning improvements to things that are controlled.

(Prior Art) Conventionally, as a technology for controlling the amount of intake air supplied to the engine to a predetermined amount in response to the amount of accelerator operation indicating the required engine output, as shown in Japanese Patent Application Laid-Open No. 51-138235, Accelerator operation amount detection means for detecting the operation amount; and target throttle valve opening setting means for receiving the output of the accelerator operation amount detection means and setting a target value of the throttle valve opening so that a preset air-fuel ratio is achieved. and throttle valve opening control means that receives the output of the target throttle valve opening setting means and controls the opening of the throttle valve to a target value, and determines the target throttle valve opening according to the accelerator operation amount. It is known that the throttle valve opening degree is feedback-controlled so that the throttle valve opening degree becomes the target throttle valve opening degree. Then, the air-fuel ratio of the engine is set to the target value by supplying the fuel amount to the engine so that the air-fuel ratio is set in advance according to the intake air amount based on the throttle valve opening degree. .

(Problem to be Solved by the Invention) By the way, instead of using the target throttle valve opening setting means as described above, the target value of the intake air amount may be set so that the air-fuel ratio is set in advance according to the accelerator operation amount. A target intake air amount setting means may be provided to determine the target intake air amount according to the accelerator operation amount, and the opening degree of the throttle valve may be feedback-controlled so as to reach the target intake air amount, which is the same control as the conventional example described above. is possible.

In this way, when performing feedback control of the opening degree of the throttle valve to bring the intake air amount to the target value, the feedback control of the throttle valve must be performed in consideration of sudden fluctuations in the intake air amount or from a fail-safe perspective. It is preferable to set a correction limit value for the feedback value (correction value) and limit the feedback value to a predetermined range so as not to exceed the correction limit value, thereby improving the control accuracy of the feedback control of the throttle valve.

However, for engines that recirculate a portion of the exhaust gas into the engine intake passage as part of engine exhaust gas purification, there may be variations in the operation of the exhaust recirculation control valve during exhaust gas recirculation, the magnitude of the exhaust pressure of the recirculated exhaust gas, etc. Since the amount of exhaust gas recirculation changes due to this, the range of fluctuation in the intake amount of fresh air, which is reduced by the amount of exhaust gas recirculation, increases. For this reason, even the feedback value that should originally be adopted may exceed the correction limit value, and in this case, there is a problem that the feedback control of the throttle valve is not performed with high accuracy. In particular, when performing so-called learning correction, in which the target intake air amount itself is sequentially feedback corrected to an appropriate value based on the status of throttle valve feedback control, the learning correction coefficient as a feedback value in throttle valve feedback control is used for the correction. As a result of exceeding the limit value, the learning correction of the target intake air amount will not be performed with high accuracy, and the control accuracy of the intake air amount will deteriorate.

The present invention has been made in view of the above, and an object of the present invention is to control the correction limit value of the feedback control during exhaust gas recirculation when performing feedback control of the throttle valve in order to adjust the intake air amount to the target intake air amount as described above. By making the value larger than when the exhaust gas recirculation is stopped, the feedback value can be appropriately selected and the control accuracy of the throttle valve feedback control during the exhaust gas recirculation can be improved, thereby improving the control accuracy of the intake air amount regardless of the presence or absence of the exhaust gas recirculation. The aim is to improve the

(Means for Solving the Problems) In order to achieve the above object, the solving means of the present invention, as shown in FIG. Target intake air amount setting means 3 that sets a target intake air amount A _C1 taken into the engine in accordance with
9, an intake air amount detection means 20 for detecting the actual measured value A _CR of the intake air amount, and an output α of the accelerator operation amount detection means 19, and a target intake air amount is set from the target intake air amount setting means 39 according to the accelerator operation amount α. The intake air amount A _C1 is determined, and the opening degree θ _R of the throttle valve is adjusted between the target intake air amount A _C1 and the actual measured value so that the actual measured value A _CR of the intake air amount obtained from the intake air amount detection means 20 becomes the target intake air amount A _C1 . The basic configuration of the engine throttle valve control device includes a feedback control means 40 that performs feedback control using a correction amount related to a feedback correction control amount calculated based on the deviation from A _CR . In addition to this, an exhaust gas recirculation detection means 25 detects when exhaust gas is recirculated to the engine.
Then, the correction amount by the feedback control means 40 is limited to a predetermined range by a correction limit value, and in response to the output of the exhaust gas recirculation detecting means 25, the correction limit value is set to be larger during exhaust gas recirculation than when exhaust gas recirculation is stopped. Correction limit value changing means 38
The configuration includes the following.

(Function) With the above configuration, in the present invention, during exhaust gas recirculation when the fluctuation range of intake air amount is large, the correction limit value for limiting the correction amount in feedback control to a predetermined range is changed to a larger value than when exhaust gas recirculation is stopped. By doing so, the selection of feedback values is always performed appropriately, and the feedback control of the throttle valve becomes appropriate, and as a result, the control accuracy of the intake air amount is improved.

(Example) Hereinafter, an example of the present invention will be described based on the drawings from FIG. 2 onwards.

FIG. 2 shows the overall configuration of an engine control device according to an embodiment of the present invention, in which 1 is a four-cylinder engine, for example, and 2 is an engine with one end opening to the atmosphere via an air cleaner 3 and the other end opening to the engine 1. An intake passage 4 supplies intake air (air) to the engine 1, and an exhaust passage 4 has one end open to the engine 1 and the other end opened to the atmosphere to discharge exhaust gas from the engine 1. Reference numeral 5 denotes an accelerator pedal that is depressed in response to engine output requirements, and 6 a throttle valve that is disposed in the intake passage 2 and controls the amount of intake air. There is no linkage relationship, and as will be described later, it is electrically controlled by the amount of depression of the accelerator pedal 5, that is, the amount of accelerator operation. Reference numeral 7 denotes a throttle actuator consisting of a step motor or the like that opens and closes the throttle valve 6. Reference numeral 8 denotes a catalyst device which is interposed in the exhaust passage 4 and purifies exhaust gas.

Further, 9 has one end opened upstream of the catalyst device 8 of the exhaust passage 4 and the other end opened downstream of the throttle valve 6 of the intake passage 2 to recirculate a part of the exhaust gas of the exhaust passage 4 to the intake passage 2. An exhaust gas recirculation passage; 10 is a recirculation control valve that is interposed in the exhaust gas recirculation passage 9 and is made of a diaphragm device using intake negative pressure as an operating source to control the amount of exhaust gas recirculation; 11 is a recirculation control valve that opens and closes the recirculation control valve 10; It is a solenoid valve that controls.

On the other hand, 12 is a fuel injection valve disposed downstream of the throttle valve 6 in the intake passage 2 to inject and supply fuel. The fuel injection valve 12 is communicated with a fuel tank 16 via a fuel supply passage 15 with a fuel pump 13 and a fuel filter 14 interposed therebetween, and is supplied with fuel from the fuel tank 16 and drains the excess fuel. The fuel is returned to the fuel tank 16 via a return passage 18 with a fuel pressure regulator 17 interposed therebetween, so that fuel at a predetermined pressure is supplied to the fuel injection valve 12.

In addition, 19 is an accelerator pedal position sensor as an accelerator operation amount detection means for detecting the amount of depression of the accelerator pedal 5, that is, the accelerator operation amount α, and 20 is arranged upstream of the throttle valve 6 in the intake passage 2 to detect the amount of intake air. An air flow meter as an intake air amount detection means for detecting Qa _R ; 21 is an intake air temperature sensor also disposed upstream of the throttle valve 6 in the intake passage 2 and detects the intake air temperature; 22 is an intake air temperature sensor for detecting the opening degree of the throttle valve 6; A throttle position sensor 23 is a water temperature sensor that detects the engine coolant temperature _TW , and 24 is a water temperature sensor disposed in the exhaust passage 4 upstream of the catalytic device 8, which detects the air-fuel ratio λ of the engine 1 from the oxygen concentration component in the exhaust gas. The detecting O ₂ sensor 25 is a recirculation sensor attached to the recirculation control valve 10 and serving as an exhaust recirculation detecting means for detecting the exhaust gas recirculation, and these detection signals 19 to 25 are sent to a control unit consisting of an analog computer or the like. 26
is input to the control unit 26.
The throttle actuator 7, solenoid valve 11 and fuel injection valve 12 are controlled by this.
Further, an igniter 27 is input connected to the control unit 26, and receives a signal indicating the number of ignitions, that is, the engine rotational speed Ne. Further, a duplexer 28 and a battery 29 are connected as inputs to the control unit 26, and control the ignition timing and battery voltage, respectively.
The V _B signal is being input.

Next, the operation of the control unit 26 will be explained with reference to FIG. Note that FIG. 3 shows the case of a four-cylinder engine.

In Fig. 3, first, to describe the throttle valve opening control system, M _A1 is set to a target value Qa ₁ of air supplied to the engine 1 so that the air-fuel ratio is set in advance for the accelerator operation amount α. The first map constitutes the target intake air amount setting means 39, and is the first map configured by the accelerator pedal position sensor 1.
9, a target air amount Qa ₁ to be supplied to the engine 1 is set in accordance with the accelerator operation amount α. M _A2 is the engine coolant temperature T _W
This is the second map in which the minimum air amount Qam is set to provide the air-fuel ratio necessary for idle up, and receives the output from the water temperature sensor 23 and corrects the water temperature according to the engine coolant temperature T _W. I am trying to set the minimum air amount Qam for use. 31 is
After receiving the respective outputs of the first map M _A1 and the second map M _A2 , the target air amount Qa ₁ obtained from the first map M _A1 and the minimum air amount Qam for water temperature correction obtained from the second map M _A2 are determined. This is a maximum value selection circuit that selects the maximum value Qa ₂ among them, and when the target air amount Qa ₁ is lower than the minimum air amount Qam for water temperature correction, the minimum air amount Qam for water temperature correction is selected due to idle up.
is selected to ensure good engine drivability. Further, M _A3 is a third map in which the maximum air amount Qa _M determined by the engine speed Ne is set with respect to the engine speed Ne, and it receives the output from the igniter 27 and
The maximum air amount Qa _M is set according to Ne. 32 receives each output of the maximum value selection circuit 31 and the third map M _A3 , and calculates the maximum air amount Qa ₂ determined by the maximum value selection circuit 31 and the third map M A3.
This is a minimum value selection circuit that selects the minimum value Qa ₃ from the maximum air amount Qa _M determined by M _A3 , and the target air amount Qa ₁ exceeds the maximum air amount Qa _M determined by the engine speed Ne. Sometimes, it is meaningless to set the target value to be more than the amount of air that can be sucked in when the throttle valve 6 is fully open.
By selecting Qa _M and limiting the maximum value, a full open signal corresponding to the fully open throttle valve 6 is output to the subsequent stage. As described above, the target air amount Qa ₃ is determined for the accelerator operation amount α, taking into account the correction for the engine coolant temperature T _W and the correction for the maximum air amount when the throttle valve 6 is fully open, which is determined by the engine speed Ne.

Furthermore, 33 is a divider which receives the output from the minimum value selection circuit 32 and divides the target air amount Qa ₃ by the value obtained by doubling the engine speed Ne (Ne×2). Intake amount per cylinder
I'm looking for A _C1 . M _A4 and M _A5 are the fourth and fifth maps in which the throttle valve opening θ ₁ or θ _1E that should be the target intake air amount A _C1 for the engine speed Ne when exhaust gas recirculation is stopped and during exhaust gas recirculation are respectively set. Both maps M _A4 and M _A5 are selected by a recirculation switch 34 which switches between when exhaust recirculation is stopped and when exhaust recirculation is performed according to a signal from the recirculation sensor 25, and receives the output from the divider 33.
The throttle valve opening degree θ ₁ or θ _1E that should be the target intake air amount A _C1 is set. Further, 35 is an intake air amount feedback correction module & learning correction module, of which the intake air amount feedback correction module calculates the target intake air amount from the divider 33.
In addition to receiving the signal of A _C1 , the signal of the actual air amount Qa _R and _the engine speed Ne measured by the air flow meter 20 is received, and the The actual intake air amount A _cR and the target intake air amount A _C1 are compared, and a feedback correction coefficient Ca _FB is sequentially calculated as a feedback correction control amount for feedback correcting the throttle valve opening according to the deviation. . In addition, the above learning correction module is
Based on a zone signal from a zone determination module 51 (to be described later), when, for example, two seconds or more have elapsed after the intake air amount feedback correction condition was established in the intake air amount feedback correction module, the correction amount related to the feedback correction control amount is determined. After setting the intake air volume learning correction coefficient S _TDY to its initial value = 1.0, the following formula S _TDY = S _TDY + 1/8 {(Peak value of Ca _FB of the past 8 times + Bottom value of Ca _FB of the past 8 times) /16-1.0}, and based on the output signal from the recirculation sensor 25, the range of the intake air amount learning correction coefficient S _TDY is changed to S _TDY = S TDY when exhaust recirculation is stopped.
While limited to 1.0±30%, S _TDY during exhaust recirculation
= 1.0±50%, and receives the output from the recirculation sensor 25, and is a correction limit that changes the correction limit value of the intake air amount learning correction coefficient S _TDY during exhaust gas recirculation to a value greater than that when exhaust gas recirculation is stopped. Value changing means 3
8. Further, 36 receives each output from the fourth or fifth map M _A4 , M _A5 and the intake air amount feedback correction module & learning correction module 35, and calculates the target throttle valve opening determined by the map M _A4 , M _A5 . The intake air volume learning correction coefficient S _TDY determined by the learning correction module for the degree θ ₁ or θ _1E
A multiplier 37 calculates the target throttle valve opening θ ₂ by multiplying and correcting the target throttle opening θ ₂ obtained by the multiplier 36 by multiplying the target throttle opening θ 2 obtained by the multiplier 36 by multiplying the target throttle opening θ 2 obtained by the intake air amount feedback correction module & learning correction module 35. The signal of the target throttle valve opening θ ₃ corrected by _the multiplier 37 is outputted to the throttle actuator 7 and the throttle valve 6 The opening degree of the throttle valve is controlled to the target throttle valve opening degree _θ3 . As described above, the feedback control means 40 is constructed which performs feedback control on the throttle valve 6 to bring the air amount to the target value.

Next, referring to the fuel supply amount control system in FIG. 3, M _B6 is set to a target value Qf ₁ of fuel supplied to the engine 1 so that the air-fuel ratio is set in advance for the accelerator operation amount α. The sixth map is the accelerator pedal position sensor 19.
A target fuel amount Qf ₁ to be supplied to the engine 1 is set according to the accelerator operation amount α. M _B7 is the seventh map in which the minimum fuel amount Qfm is set for the engine coolant temperature T _W so that the air fuel ratio required for idle up is obtained for the air amount Qam set in the second map M _A2 .
A map that receives the output of the water temperature sensor 23,
The minimum fuel amount Qfm for water temperature correction is set according to the engine coolant temperature _TW . 39 receives the respective outputs of the sixth map M _B6 and the seventh map M _B7 , and calculates the target fuel amount Qf ₁ obtained from the sixth map M B6 and the seventh map M _B6 .
Minimum fuel amount for water temperature correction determined by Mappu M _B7
This is a maximum value selection circuit that selects the maximum value Qf ₂ from Qfm, and when the target fuel amount Qf ₁ is lower than the minimum fuel amount Qfm for water temperature correction, it selects the minimum fuel amount Qfm for water temperature correction due to the idle increase. This ensures good engine drivability. Moreover, M _B8 is the eighth map in which the maximum fuel amount Qf _M is set for the engine speed Ne so that the maximum air amount Qa _M set in the third map M _A3 becomes the target air-fuel ratio set in advance. It is a map,
The maximum fuel amount Qf _M is set according to the engine speed Ne. 40 receives each output of the maximum value selection circuit 39 and the eighth map M _B8 , and calculates the maximum fuel amount Qf ₂ determined by the maximum value selection circuit 39 and the eighth map M B8.
This is a minimum value selection circuit that selects the minimum value Qf ₃ from the maximum fuel amount Qf _M determined by M _B8 , and the above target fuel amount Qf ₁ exceeds the maximum fuel amount Qf _M determined by the engine speed Ne. In other words, when the target air amount Qa ₁ exceeds the maximum air amount Qa _M determined by the engine speed Ne as described above, and the target value is greater than the amount of air that can be taken in when the throttle valve 6 is fully open. , select the maximum air amount Qa _M and the maximum fuel amount Qf _M above, and then start engine 1.
The target value of the sixth map M _B6 is set so that the preset target air-fuel ratio is achieved for the intake air amount supplied to the
I am trying to correct Qf ₁ . As described above, as in the case of the air amount, the throttle valve 6 determined by the correction for the engine cooling water temperature T _W and the engine speed Ne for the accelerator operation amount α.
The target fuel amount Qf ₃ is determined by considering the correction for the maximum fuel amount at full throttle.

Then, the target fuel amount Qf ₃ signal from the maximum value selection circuit 40 is applied to the fuel injection via the divider 41, the first to third multipliers 42 to 44, the fuel cut switch 45 and the fuel injection valve correction circuit 46. valve 12
is output to. The divider 41 receives the output from the minimum value selection circuit 40 and divides the target fuel amount Qf ₃ into 2
Assuming that fuel is injected into each cylinder at the same time, calculate the amount of fuel supplied per cylinder by dividing by the engine speed Ne.
This is to calculate Qfi. Further, the first multiplier 42 converts the target fuel supply amount Qfi obtained by the divider 41 into a water temperature correction coefficient C _TW and an enrichment correction module 47 for the engine cooling water temperature T _W obtained from the ninth map M _B9 . Multiply and correct the enrichment correction coefficient C ER obtained by _ER to obtain the target fuel supply amount.
This is to calculate Qfi ₁ . This enrichment correction module 47 adjusts the engine speed based on a zone signal from a zone determination module 51, which will be described later.
When the intake air amount Ac ₁ with respect to Ne is in the enrichment line region, an enrichment correction coefficient C _ER (for example, 1.08) is output in order to uniformly increase the fuel supply amount by, for example, 8%.

Further, the second multiplier 43 includes a first multiplier 4
Target fuel supply amount Qfi ₁ obtained in step 2, learning correction coefficient C _STD obtained in fuel learning correction module 48
The target fuel supply amount Qfi ₂ is calculated by performing multiplication correction. This fuel learning correction module 48 is
A zone signal from a zone determination module 51 and a fuel feedback correction module 49, which will be described later.
Based on the fuel feedback correction coefficient Cf _FB signal from the fuel feedback correction module 49
When, for example, 2 seconds or more have passed after the fuel feedback correction conditions were met, the fuel learning correction coefficient C _STD
After setting the initial value to 1.0, use the following formula C _STD = C _STD + 1/8 {(Peak value of Cf _FB of the past 8 times + Bottom value of Cf _FB of the past 8 times)/16−1.0} Therefore, it is sequentially updated and output.

Further, the third multiplier 44 includes the second multiplier 43
The target fuel supply amount Qfi ₂ obtained in the above is multiplied and corrected by the fuel feedback correction coefficient _CfFB obtained by the fuel feedback correction module 49 to calculate the target fuel supply amount Qfi ₃ . The fuel feedback correction module 49 operates based on the zone signal from the zone determination module 51 and the air-fuel ratio λ signal from the O ₂ sensor 24 under the following conditions, for example: Engine cooling water temperature T _W >60°C Intake air amount Ac ₁ ≧Cylinder stroke volume 10% of the intake air amount Ac ₁ relative to the engine speed Ne is outside the enrichment line and fuel cut zone. When the _O2 sensor 24 is active, the fuel feedback correction coefficient is set to feedback control the fuel supply amount. Cf _FB (e.g.
0.8≦Cf _FB ≦1.25, proportional constant P=0.06, integral constant I=0.05/sec).

Furthermore, the fuel cutter switch 45 is
The opening/closing is controlled by the output signal from the fuel cut control module 50. This fuel cut control module 50 receives the zone signal from the zone determination module 51 and the target intake amount.
Based on the Ac ₁ signal, for example, when the following conditions are met: Engine cooling water temperature T _W > 60℃, Intake air amount Ac ₁ < 10% of cylinder stroke volume, Engine speed Ne > 1000 rpm, the fuel cut is activated to cut fuel injection. This controls the switch 45 to open. Here, the zone determination module 51
is for creating condition determination signals (zone signals) for each of the control modules 35, 47 to 50, based on the engine speed Ne, target intake air amount Ac ₁ , engine coolant temperature _TW , and air-fuel ratio λ. It is.

Furthermore, the fuel injection valve correction circuit 46 includes:
Upon receiving the target fuel supply amount Qfi ₃ signal from the third multiplier 44 and the battery voltage V _B signal from the battery 29, a pulse signal is sent as a target fuel supply amount signal to the fuel injection valve 12 according to the battery voltage V _B. is corrected and output to the fuel injection valve 12. As described above, the fuel injection valve 12 is driven for a predetermined period of time in synchronization with ignition, and the fuel supply amount is controlled to the target value.

Therefore, in the above embodiment, the target intake air amount to be supplied to the engine 1 is determined according to the accelerator operation amount α, and the opening degree of the throttle valve 6 is feedback-controlled so as to reach this target intake air amount.
A target intake air amount is supplied to the engine 1.

In that case, when exhaust gas is recirculated to the engine 1, the amount of exhaust gas recirculated varies due to variations in the operation of the recirculation control valve 10, the magnitude of the exhaust pressure of the recirculated exhaust gas, etc. Therefore, the intake air amount feedback correction module & learning correction The feedback correction coefficient Ca _FB calculated by the module 35 fluctuates greatly, and the fluctuation range of the intake air amount learning correction coefficient S _TDY also increases. However, during this exhaust gas recirculation, the learning correction module 35
Since the limit value of the intake air volume learning correction coefficient S _TDY is significantly changed from 1.0 ± 30% when exhaust gas recirculation is stopped to 1.0 ± 50%, the intake air volume learning correction coefficient S _TDY , which should be the basis of learning correction, is at its limit. It is output as is to the multiplier 36 without exceeding the value, and is used in the multiplier 36 for learning correction of the target throttle valve opening θ ₁ or θ _1E corresponding to the target intake air amount Ac ₁ , and as a result, the multiplier 36 3
In step 6, the target throttle valve opening degree θ ₁ or θ _1E is learned and corrected to an appropriate value, thereby improving the control accuracy of the intake air amount.

In addition, a target air amount and a target fuel amount are respectively determined for the accelerator operation amount α, and based on the determined target values, the intake air amount and fuel supply amount are set to the target values simultaneously and in parallel. As a result, the intake air amount and fuel supply amount both change to the target value at the same time without any time lag in response to changes in the accelerator operation amount α, so even during transient operation of the engine, the amount of fuel is The air-fuel ratio of the engine can be accurately controlled to the target air-fuel ratio without causing a response delay, and thus the acceleration performance and driving performance of the engine can be improved.

(Effects of the Invention) As explained above, according to the present invention, during exhaust gas recirculation, the correction limit value for limiting the correction amount related to the feedback correction control amount in throttle valve feedback control to a predetermined range is Since the change is made larger than when the engine is stopped, and the feedback values are appropriately selected, the feedback control of the throttle valve can be made appropriate, and the control accuracy of the intake air amount can be improved. It is something.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of the present invention. 2 and 3 show an embodiment of the present invention, with FIG. 2 being a general schematic diagram and FIG. 3 being a block diagram showing the operational flow of the control unit. 1...engine, 5...accelerator pedal, 6...
... Throttle valve, 7... Throttle actuator, 19... Accelerator pedal position sensor,
20... Air flow meter, 26... Control unit, 25... Reflux sensor, 38... Correction limit value changing means, 39... Target intake air amount setting means,
40...Feedback control means.

Claims (1)

[Scope of Claims] 1. Accelerator operation amount detection means for detecting an accelerator operation amount; target intake air amount setting means for setting a target intake air amount to be drawn into the engine in advance in accordance with the accelerator operation amount; an intake air amount detection means for detecting an actual measured value of , and an output from the accelerator operation amount detection means, a target intake amount is determined from the target intake air amount setting means according to the accelerator operation amount, and a target intake amount is obtained from the intake air amount detection means. Feedback control that performs feedback control on the opening degree of the throttle valve using a correction amount related to a feedback correction control amount calculated based on the deviation between the target intake amount and the actual measurement value so that the actual measured value of the intake air amount becomes the target intake amount. an engine throttle valve control device comprising: an exhaust gas recirculation detecting means for detecting when exhaust gas is recirculating to the engine; and limiting the correction amount by the feedback control means to a predetermined range by a correction limit value. . A throttle valve control device for an engine, comprising: correction limit value changing means for receiving the output of the exhaust gas recirculation detecting means and changing the correction limit value to be larger during exhaust gas recirculation than when exhaust gas recirculation is stopped.