JP3407325B2 - Throttle control device for internal combustion engine - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a throttle control device for an internal combustion engine, and more particularly to learning a fully closed position of a throttle valve driven by a throttle actuator. 2. Description of the Related Art Conventionally, when the driving wheels of a vehicle are about to spin, the engine output torque and the braking force are controlled to prevent the wheels from spinning. A system called a traction control system has been put to practical use (see Japanese Patent Application Laid-Open No. 4-58049). In the traction control system, generally, a second throttle valve, which is opened and closed by a throttle actuator such as a stepping motor, is provided separately from the first throttle valve linked to accelerator operation. When the engine output torque needs to be reduced for traction control, normally, the second throttle valve is fully opened.
The second throttle valve is closed. In the control of the second throttle valve, a throttle sensor for detecting the opening of the second throttle valve is provided, and the opening of the second throttle valve is set with high accuracy based on the detection result of the sensor. Although the feedback control is applied to the opening, the second throttle valve is forcibly controlled to be fully closed immediately after the key switch is turned on in order to prevent the accuracy of the opening control from deteriorating due to variation or deterioration of the sensor. By learning the sensor output at this time as a fully closed position equivalent value, the accuracy of the opening control using the throttle sensor is maintained. Here, as described above, instead of providing the first throttle valve and the second throttle valve respectively,
As disclosed in JP-A-3-61654, if a single throttle valve is used to open and close the throttle valve in response to an accelerator operation, while forcibly closing the throttle valve in response to a traction control request, The system configuration can be simplified. [0006] However, in the above-described configuration in which traction control is realized by a single throttle valve, the throttle valve whose first fully closed position is changed according to the engine temperature. When an idle cam is attached, the key switch is turned on.
The learning value of the fully closed position immediately after the engine temperature rises may not be suitable for the actual situation, and the intended traction control may not be able to be performed with high accuracy. In the first idle cam, the fully closed position of the throttle valve is forcibly changed by a wax pellet (temperature sensing member) which is thermally displaced in response to the temperature of the cooling water of the engine. As a side, the air amount necessary for the idling operation can be secured.
Here, since the fully closed position learning needs to be performed early and surely, it is performed once immediately after the key switch is turned on (before the engine is started), which has no effect even if the forced fully closed control is performed. However, when a cold start is performed and the fully closed position is offset to the open side by the first idle cam, the fully closed position shifted to the open side by the first idle cam is learned. . When the engine has been warmed up and the throttle valve is closed to its original fully closed position, control is performed to close the throttle valve fully in response to a traction control request. However, since the fully-closed control is performed using the fully-closed position learned when the key switch is turned on as an index, it is actually closed only up to the state where the first idle cam is opened to the intermediate opening degree, and the desired output torque is obtained. Control cannot be performed, and a problem arises in that a load is imposed on braking force control. SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems. Even if the full-close learning is performed when the fully-closed position of the throttle valve is offset to the open side in a cold state by the first idle cam, the temperature of the throttle valve after that is learned. An object of the present invention is to make it possible to perform close control of a throttle valve to a true fully closed position in an ascended state, and to reliably perform traction control by full throttle control of the throttle valve. Therefore, a throttle control device for an internal combustion engine according to the present invention is configured as shown in FIG. In FIG. 1, a throttle actuator drives a throttle valve interposed in an engine intake system, and a throttle sensor outputs a detection signal corresponding to the opening of the throttle valve. The fully closed position learning means controls the throttle actuator to forcibly fully close the throttle valve immediately after power is turned on, and outputs a detection signal of the throttle sensor during the fully closed control to the throttle actuator. Learn as a value equivalent to the fully closed position of the valve. On the other hand, the first idle control means changes the fully closed position of the throttle valve to the opening direction as the engine is colder by a temperature-sensitive member thermally displaced in response to the engine temperature. [0012] In addition, the engine temperature detection means detecting the engine temperature
And a learning value correction means for the first idle control means based on the engine temperature detected by the engine temperature detection means.
Estimate the offset amount in the opening direction of the fully closed position by the
The offset amount is calculated based on the total amount learned by the fully closed position learning means.
Subtraction is performed from the detection signal corresponding to the closed position. Further, the target opening setting means sets the target opening of the throttle valve according to operating conditions, and the opening / closing control means reduces the target opening by the learning value correction means.
The throttle actuator is controlled based on the calculated detection signal corresponding to the fully closed position and the detection signal from the throttle sensor so that the opening of the throttle valve matches the target opening. According to this configuration, the fully closed position of the throttle valve is configured to change in accordance with the engine temperature by the first idle control means. Then, the fully closed position offset to the open side is learned by the first idle control means. Here, since the offset of the fully closed position by the first idle control means is in accordance with the engine temperature, the offset amount of the fully closed position can be estimated based on the engine temperature. Therefore, the fully closed position learned immediately after the power is turned on is reduced by the offset.
By calculation to, and so the learning value is obtained which corresponds to the fully closed position after warm-up. Embodiments of the present invention will be described below. In FIG. 2 showing the system configuration of the present embodiment, the internal combustion engine 1 includes:
Air cleaner 2, throttle valve 3, intake manifold 4
Air is inhaled through. An electromagnetic fuel injection valve 5 is provided for each cylinder in a branch portion of the intake manifold 4, and a fuel-air mixture is formed by fuel intermittently supplied from the fuel injection valve 5. The opening of the fuel injection valve 5 is controlled by a control unit 6 containing a microcomputer. The control unit 6 includes, for fuel injection control, an intake air flow rate signal Q from an air flow meter 7, a rotation signal N from a crank angle sensor 8, and a cooling representing the engine temperature from a water temperature sensor 9 (engine temperature detecting means). A water temperature signal Tw or the like is input, the fuel injection amount is calculated based on these detection signals, and the fuel injection valve 5 is intermittently opened according to the calculated injection amount. The throttle valve 3 is configured to be opened and closed in conjunction with the operation of an accelerator pedal 10, and the throttle valve 3 is made of a wax pellet (temperature-sensitive member) that thermally displaces in response to the temperature of the cooling water of the engine. A first idle cam 11 (first idle control means) for forcibly changing the fully closed position of the camera is provided. In the present embodiment, the control unit 6 also functions as a control unit of a traction control system. For such traction control, a drive wheel rotation sensor 12 and a non-drive wheel rotation sensor are provided. 13 and input these signals to these rotation sensors 12, 13
The wheel spin of the drive wheel is determined on the basis of the detection signal, and when the wheel spin is likely to occur, the opening of the throttle valve 3 is forcibly reduced to reduce the engine output torque and to reduce the brake force on the drive wheel side. To prevent wheel spin from occurring in the drive wheels. Here, for the traction control, a throttle actuator such as a stepping motor can be used regardless of the opening degree of the throttle valve 3 regardless of the accelerator operation.
There is a configuration that can be automatically controlled by 14. In order to drive-control the throttle valve 3 to a target opening by the throttle actuator 14, the throttle valve 3
Is provided with a potentiometer type throttle sensor 15 for detecting the opening TVO, and performs feedback control to a target opening based on a detection signal output from the sensor 15 corresponding to the opening TVO. ing. As described above, the control unit 6
A function of setting a target opening of the throttle valve 3 for reducing the engine output torque at the time of traction control operation and performing feedback control of the throttle actuator 14 in accordance with a detection signal of the throttle sensor 15 so as to reach the target opening. Have. Therefore, in the present embodiment, the control unit 6 has functions as target opening degree setting means and opening / closing control means. However, since the detection characteristics of the throttle sensor 15 vary and the output characteristics may change due to deterioration, the detection signal of the throttle sensor 15 corresponding to the fully closed position of the throttle valve 3 is learned. By doing so, highly accurate opening control can be performed.
The state of the fully closed position learning will be described with reference to the flowchart of FIG. In the present embodiment, the functions of the fully closed position learning means and the learning value correction means are provided by software in the control unit 6 as shown in the flowchart of FIG. FIG. 3 is a flowchart showing a routine executed when the control unit 6 is turned on by turning on the key switch. First, in S1,
The lower limit of the target opening in the opening control using the throttle actuator 14 is set according to the cooling water temperature Tw detected by the water temperature sensor. That is, in the present embodiment, since the first idle cam 11 that mechanically regulates the fully closed position of the throttle valve 3 is provided, when the engine is cold, the throttle valve is moved below the fully closed position determined by the first idle cam 11. 3 cannot be closed. On the other hand, in the apparatus of this embodiment, when the throttle actuator 14 is feedback-controlled so that the opening detected by the throttle sensor 15 matches the target opening, the opening near the target opening is actually determined. If you can not get
The throttle actuator 14 has a self-diagnosis function for determining that an abnormality has occurred in a drive system or a control system. Therefore, when the opening degree below the fully closed position determined by the first idle cam 11 is set as the control target, and the throttle actuator 14 is controlled based on the set target opening degree, the target opening degree is controlled. Therefore, although there is actually no abnormality, the abnormality is determined by the self-diagnosis. Here, since the fully closed position determined by the first idle cam 11 changes according to the cooling water temperature (engine temperature) Tw, the fully closed position previously determined by the first idle cam 11 for each cooling water temperature Tw is determined. The opening degree slightly exceeding such a fully closed position is set as the lower limit value of the target opening degree (see FIG. 4). [0023] Even if the opening degree below the lower limit is learned as the fully closed position learning value,
When an opening smaller than the lower limit is set as the target opening, the target opening is reset to the lower limit, and at least a target opening that is lower than a fully closed position that can be actually closed is set. So that they can be avoided. Next S
In step 2, the throttle actuator 14 is controlled to forcibly close the throttle valve 3 fully, and the throttle valve 3 is controlled to the fully closed position regardless of the accelerator operation. Such full-close control is performed immediately after the power is turned on. Even if the throttle valve 3 is forcibly closed irrespective of the accelerator operation, there is no problem in driving. In S3, a detection signal output from the throttle sensor 15 at the time of the full-close control is read, and the detection signal is learned as a value corresponding to the full-close position. In such fully closed position learning, the throttle actuator 14
Is controlled in the closing direction of the throttle valve 3, and a throttle sensor
It is preferable to sample the output when the detected opening degree by 15 becomes minimum as a value corresponding to the fully closed position. Here, when the engine is cold, it is offset by the first idle cam 11 to the fully closed position corresponding to the engine temperature (water temperature). The fully closed position learned by the learning has an opening degree higher than that at the time of complete warming (see FIG. 4). Therefore, when the warm-up progresses and the fully closed position determined by the first idle cam 11 changes to a more closed side, when the fully closed control is performed at the time of the traction control operation based on the fully closed position learned at the time of turning on the power, However, it can only be closed up to the fully closed position when the power is turned on. Therefore, in the next S4, the cooling water temperature T
Referring to a map storing the offset of the fully closed position by the first idle cam 11 according to w, it is determined how much the fully closed position is offset to the open side by the first idle cam 11 in the temperature state at the time of power-on. (See FIG. 4). Then, by subtracting the offset corresponding to the cooling water temperature Tw from the fully closed position learned value learned in S3, a learning value corresponding to the fully closed position after warm-up in which the first idle cam 11 does not function is obtained. to correct. In the next step S5, the fully closed control by the throttle actuator 14 for learning the fully closed position is cancelled, and the throttle valve 3 is opened and closed normally according to the accelerator operation. As described above, in this embodiment, immediately after the power is turned on, the throttle valve 3 is forcibly controlled to be fully closed by the throttle actuator 14, and the output of the throttle sensor 15 at that time is regarded as a fully closed position equivalent value. If the fully closed position is offset by the first idle cam 11 at this time, the learned fully closed position is a value corresponding to the temperature state at the time of power-on, and the warm-up proceeds. It does not become the value equivalent to the fully closed position in the closed state. Therefore, the amount of offset of the fully closed position by the first idle cam 11 to the open side is estimated based on the cooling water temperature Tw, and the offset is subtracted from the learning value to obtain the fully closed position after warm-up. Is corrected to a signal level corresponding to. Then, the operation of the engine 1 is started,
When, for example, the throttle valve 3 is controlled to be fully closed by the operation of the traction control, the actual fully closed position changes because the throttle actuator 14 is feedback-controlled with the corrected fully closed position equivalent value after warm-up as a target. During and after warm-up, the throttle valve 3 can be controlled to be fully closed. However, while the first idle cam 11 is functioning, the target opening is limited to the lower limit value set in S1, and when the traction control is performed to perform the fully closed control, the fully closed control after warm-up is performed. Instead of the position, the control is performed with the target being the fully closed position actually determined by the first idle cam 11, so that it is not possible to perform feedback control to the target opening degree and to perform abnormality diagnosis. The correction of the learning value of the fully closed position in S4 is performed by estimating the offset of the fully closed position by the first idle cam 11 based on the cooling water temperature Tw at that time, so that the learning is performed with high accuracy. It is difficult to correct the value. Then, after the cooling water temperature Tw detected by the water temperature sensor 9 becomes equal to or higher than the predetermined temperature and the offset of the fully closed position to the open side by the first idle cam 11 is not performed, the fully closed learning is performed again. It is desirable that the learning value after the warm-up be updated and set as a fully closed learning value used for controlling the opening of the throttle valve 3. That is, the fully closed position determined by the first idle cam 11 varies, and the water temperature sensor 9
Cooling water temperature Tw and first idle cam
There is also a case where the deviation is generated between the temperature affecting the properties of 11, from the detection result of the water temperature sensor 9, that either accurately estimate how much the fully closed position by the first idling cam 11 is offset Can not. Therefore,
By learning the fully closed position again after the first idle cam 11 no longer offsets the fully closed position to the open side, it is possible to perform more accurate opening control after warm-up. The fully closed learning after the warm-up is performed when the throttle sensor 15 outputs an output having an opening degree lower than a fully closed learning value learned at power-on and corrected according to the cooling water temperature Tw. The sensor output may be updated as a value equivalent to the fully closed position, or the throttle actuator 14 may be fully closed under operating conditions that do not affect even if the throttle valve 3 is forcibly closed. What is necessary is just to make an output sample. As described above, according to the present invention, when learning the fully closed position of the throttle valve when turning on the power,
Even if the fully closed position of the throttle valve is offset to the open side according to the engine temperature, the offset amount is subtracted from the learning value.
By doing so , a value equivalent to the fully closed position after warm-up can be obtained. For example, when traction control is activated after the engine temperature rises, the throttle valve can be reliably controlled to the fully closed position by the throttle actuator. Has the effect of becoming

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing a configuration of the present invention. FIG. 2 is a system schematic diagram showing one embodiment of the present invention. FIG. 3 is a flowchart showing learning of a fully closed position in the embodiment. FIG. 4 is a diagram showing a fully closed position characteristic in the embodiment. [Description of Signs] 1 Internal combustion engine 3 Throttle valve 6 Control unit 9 Water temperature sensor 10 Accelerator pedal 11 First idle cam 14 Throttle actuator 15 Throttle sensor

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-4-179848 (JP, A) JP-A-2-275033 (JP, A) JP-A-3-23324 (JP, A) JP-A-4-233 63950 (JP, A) JP-A-4-58049 (JP, A) JP-A-3-61654 (JP, A) JP-A-62-639 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) F02D 17/00-17/04 F02D 29/00-29/06 F02D 41/00-45/00

Claims (1)

(57) [Claim 1] A throttle actuator for driving a throttle valve interposed in an engine intake system, a throttle sensor for outputting a detection signal according to an opening of the throttle valve, and a power supply A fully closed position at which the throttle actuator is controlled to forcibly fully close the throttle valve immediately after closing, and a detection signal of the throttle sensor at the time of the fully closed control is learned as a value corresponding to the fully closed position of the throttle valve. Learning means; first idle control means for changing the fully closed position of the throttle valve to an opening direction as the temperature is cold by a temperature-sensitive member thermally displaced in response to the engine temperature; and engine temperature detection means for detecting the engine temperature. Based on the engine temperature detected by the engine temperature detecting means.
Open direction of fully closed position by first idle control means
Estimate the offset amount to, the offset amount, the
Detection signal equivalent to fully closed position learned by fully closed position learning means
Learning value correction means for subtracting from the target value, target opening degree setting means for setting a target opening degree of the throttle valve in accordance with operating conditions, a detection signal corresponding to a fully closed position subtracted by the learning value correction means, and the throttle. An opening / closing control unit that controls the throttle actuator so that the opening of the throttle valve matches the target opening based on a detection signal from a sensor; and a throttle control device for an internal combustion engine, comprising: