JPH10176548A - Throttle control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the erroneous detection of an open wire in icing by detecting the open circuit of a motor when the parameter of the operation signal is detected to be the first prescribed value or above for the prescribed time or longer, and largely changing the prescribed time when the temperature near a throttle valve is as low as the icing temperature. SOLUTION: A throttle control device 1 drives a motor 30 via an ECU50 receiving the output signals of a throttle sensor 15, a temperature sensor 60, and an accelerator sensor 70 and controls the opening of a throttle valve 10 via an electromagnetic clutch 20. The ECU 50 judges the motor 30 to be abnormal when the output of the throttle sensor 15 is kept at the prescribed value or above for the prescribed time or longer. When the detected value TH by the temperature sensor 60 is lower than the prescribed temperature THW, the possibility that icing occurs is large, and the value of the prescribed time used for judging the motor abnormality is largely changed. The erroneous detection of a motor lock due to icing is prevented.

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, and more particularly to a throttle control device for increasing the possibility of returning from icing when the engine temperature is low.

[0002]

2. Description of the Related Art Japanese Patent Publication No. 6-37862 relates to a monitoring device for an electronically controlled throttle valve for detecting an abnormality of a throttle valve. The device described in this publication determines that the throttle valve is abnormal when the state in which the operation signal to the motor driving the throttle valve is equal to or more than the predetermined limit value continues for a predetermined time.

[0003]

However, in the above publication,
When the motor drives the throttle valve while the throttle valve is icing, it is recognized that the throttle valve may escape from the icing state due to the driving force and heat of the motor after a certain amount of time has passed. I haven't. That is, in the device disclosed in the above publication, even when the throttle valve is icing, the parameters of the operation signal to the motor (for example, when the motor is PWM controlled, the duty ratio If) is equal to or greater than the predetermined limit value, it is determined that the motor is locked. Therefore, even if there is a possibility that the throttle valve can escape from the icing, it is determined without any consideration that the motor is locked uniformly.

Further, in the above prior art, when the duty ratio of the current flowing through the motor for driving the throttle valve is low, it is difficult to accurately determine that the motor is disconnected. This is because, when the motor for driving the throttle valve is driven by the PWM method, if the duty ratio of the operation signal of the motor is small, the offset error of the operational amplifier for detecting the motor current influences.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem, and has an object to provide an abnormality (that is, the motor is locked) when the engine temperature is so low that the throttle valve is iced. It is an object of the present invention to provide a throttle control device that does not determine that a recoverable motor lock by icing is a motor lock by extending the time until the determination is made.

It is another object of the present invention to provide a throttle control device for accurately detecting disconnection of a motor for driving a throttle valve without being affected by an offset error of an operational amplifier.

[0007]

A throttle control device according to the present invention controls an opening signal of a throttle valve to a target opening by changing an operation signal supplied to a motor for driving the throttle valve. A throttle control device for detecting that the parameter of the operation signal is equal to or greater than a first predetermined value for a predetermined time or more; Means for increasing the predetermined time, whereby the object is achieved.

[0008] In one embodiment, the parameter is a second parameter.
The current flowing through the motor is equal to or greater than a predetermined value, and
There is further provided a means for detecting that the value is equal to or less than a predetermined value.

[0009]

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

FIG. 1 is a diagram showing a configuration of a throttle control device 1 according to the present invention. The throttle control device 1 includes a throttle valve 10, a throttle sensor 15, a motor 30 for driving the throttle valve 10, an electromagnetic clutch 20 for controlling connection / disconnection between the throttle valve 10 and the motor 30, and a motor 30. , An electronic control unit (ECU) 50 for controlling the driver 40, and a temperature sensor 6
0 and an accelerator sensor 70.

The driver 40 is, for example, a switching circuit having a power transistor as a switching element, but is not limited to this. The ECU 50 applies a control voltage for turning on / off the switching element of the driver 40 to a control terminal of the switching element. In this embodiment, the motor 30 is controlled by a pulse width modulation (PWM) method. In the PWM control, a ratio of a period during which a current flows to the motor 30 to one cycle of the drive pulse is referred to as a duty ratio D. The duty ratio D is one of the parameters of the operation signal given to the motor 30. As the duty ratio D increases, the opening of the throttle valve 10 increases almost linearly.

A terminal for supplying power to the driver 40 is connected to a power supply 44 via a resistor 42. The resistance 42 generates a voltage proportional to the current flowing from the power supply 44 to the motor 30 at both ends thereof. The operational amplifier 46 receives the voltage generated across the resistor 42 at its non-inverting input terminal and inverting input terminal, amplifies the voltage, and outputs the amplified voltage. The amplified signal I is input to the ECU 50, and is used, for example, for determining disconnection of the motor. This signal I is
Is an electrical signal corresponding to the current flowing through the device.

The throttle sensor 15 outputs an electric signal V corresponding to the actual position of the throttle valve 10 to the ECU 50.
Output to The accelerator sensor 70 is connected to the accelerator pedal 7.
The accelerator position is detected in accordance with the amount of depression of step 2, and an electric signal corresponding to the accelerator position is output to the ECU 50. Temperature sensor 60 outputs an electric signal TH corresponding to the temperature near throttle valve 10 to ECU 50.

During normal running, the ECU 40 controls the motor 3
The rotation shaft of the motor 30 is connected to the throttle valve 10 so that a driving force of 0 is transmitted to the throttle valve 10.

FIG. 2 is a diagram showing the configuration of the ECU 50. The ECU 50 includes a central processing unit (CPU) 52,
A read only memory (ROM) 54 and a random access memory (RAM) 56 are included. CPU52, ROM
The RAM 54 and the RAM 56 are connected to each other by a bus, and can exchange data. ROM
54 is a lock for the motor 30 and a motor 3
Stores a program for detecting a disconnection of 0, and the like. RAM
Reference numeral 56 stores temporary variables necessary for the throttle control device 1.

An A / D converter (not shown) for converting an analog output output from each of the throttle sensor 15, the operational amplifier 46, and the temperature sensor 60 into a digital value is provided in the CPU 52, for example. As a result, an analog signal from a sensor or the like
Can be handled.

Hereinafter, a routine for detecting abnormality of the motor 30 executed by the CPU 52 will be described. Here, as the “abnormality of the motor 30”, (i) locking (fixing) of the motor 30 due to icing of the throttle valve 10 at an extremely low temperature and (ii) disconnection of the motor 30 will be considered. The lock of the motor 30 in the above (i) includes:
Some are caused by biting of gears.

FIG. 3 is a flowchart showing the entire motor control. In step S300, it is determined whether an ignition switch (IGSW) is on. If the IGSW is on, the process proceeds to step S302. If the IGSW is off, the process proceeds to step S320.

In step S302, the accelerator pedal 7
2 based on the output from the accelerator sensor 70 for detecting the position of the throttle valve 10 corresponding to the accelerator position.
The throttle command value is calculated so that the opening degree is obtained.

In step S304, step S302
Duty ratio D corresponding to the throttle command value obtained in
Is calculated. In step S306, the motor 30 is driven by the obtained duty ratio D. In the flow when the IGSW is on, step S308 is executed after step S306.

In step S308, a motor disconnection detection described later is performed. In step S310, a motor lock detection described later is performed. After step S310, the control returns to step S300. By repeating this loop, the motor 30 is driven so that the throttle valve 10 opens according to the accelerator position.

Steps S320 to S326 are performed in the IGSW
This is a routine when it is detected that is turned off.
These steps are for controlling the throttle valve 10 to smoothly return to the initial position at the end of the electronic throttle control.

In the conventional electronically controlled throttle system, when the electronic throttle control ends (FIG. 1)
In the system shown in (1), the power supply to the motor 30 is cut off when the electromagnetic clutch 20 is turned off). The throttle valve 10 returns to a mechanical initial position (also referred to as a stopper position) vigorously by the restoring force of the spring.
The initial position is, for example, an opener position that is opened about 4 ° from the fully closed position. According to the prior art, the throttle valve 1
As a result, the zero hit the mechanical stopper vigorously, resulting in an impulsive sound. Further, due to this impact, the position of the stopper may be shifted in the long term.

In steps S320 to S326, the throttle valve 10 smoothly returns to the initial position.
The problem caused by the impact accompanying the return to the initial position in the prior art does not occur in the throttle control device of the present invention.

When it is detected in step S300 that the IGSW is off, in step S320, the throttle command value is set to the initial position V1. This initial position V1
Is performed immediately after the IGSW is turned on.
This is a value obtained by learning in the initialization operation of U50. The initial position V1 corresponds to the position of the throttle valve 10 at which the above-mentioned mechanical stopper acts. In step S320, a deadline timer is started at the same time. This timer may be realized by hardware built in the CPU 52, or
May be realized by software executed by the software.

In step S304, based on the initial position V1 set in step S320, the motor 3
The duty ratio for driving 0 is calculated.

In step S306, the motor 30 is driven based on the calculated duty ratio. In the flow when the IGSW is off, step S322 is executed after step S306.

In step S322, it is determined whether the value T of the deadline timer is equal to or greater than a predetermined value T1. If the value T of the deadline timer is equal to or greater than the value T1, that is, if the throttle valve 10 does not return to the initial position even after the predetermined time has elapsed, the motor energization is forcibly cut off in step S326. Jump to If the value T of the deadline timer is less than the value T1, the process proceeds to step S324 to determine whether the throttle valve 10 has returned to the initial position.

In step S324, it is determined whether or not the throttle valve 10 is near the initial position. Specifically, the value V output from the throttle sensor 15
Is in the range of (initial position V1 ± width ΔV). If (V1-.DELTA.V) .ltoreq.V.ltoreq. (V1 + .DELTA.V), it is determined that the throttle valve 10 has sufficiently returned to the initial position, and the flow advances to step S326 to cut off motor energization. If the throttle valve 10 is in the vicinity of the initial position, a large impact does not occur even if the motor power is cut off. If the current flowing through the motor 30 is interrupted in step S326, the electronic throttle control ends.

On the contrary, (V1−ΔV) ≦ V ≦ (V1 + ΔV)
Is not satisfied, it is determined that the throttle valve 10 has not sufficiently returned to the initial position, and the process proceeds to step S304. After step S304, the throttle valve 1
The motor 30 is driven again to control the opening of the throttle valve 10 so that 0 returns to the initial position V1.

A routine for detecting a motor lock according to the present invention will be described below with reference to FIG.

FIG. 4 is a flowchart of the motor lock detection according to the present invention. The routine in FIG. 4 corresponds to step S310 in FIG. Therefore, if the control is shifted to step S310 in FIG. 3, the motor lock detection in FIG.
When the control reaches the "normal control" of step S3 in FIG.
Control returns to 10.

In step S400, it is determined whether the duty ratio D of the pulse signal for driving the motor 30 is equal to or greater than a predetermined value D1. Where D and D1 are P
The ratio of the period during which the current flows through the motor 30 to one cycle of the WM control pulse is represented by “%”. If the duty ratio D is equal to or more than the predetermined value D1, it is considered that the motor 30 is being driven to some extent,
Proceed to 402. Conversely, if the duty ratio D is less than the predetermined value D1, it is considered that the motor 30 is not being driven very much, the process proceeds to step S420, the detection timer is cleared, and then the process returns to the normal control (ie, FIG. The control moves to step S310 and subsequent steps.

If it is determined in step S400 that D ≧ D1, it is determined in step S402 whether or not the throttle valve 10 is operating. Specifically, the time change (dV / dt) of the signal V output from the throttle sensor 15
Is smaller than or equal to the predetermined value ΔV1, it is determined that the throttle valve 10 has not moved much, and the routine proceeds to step S404. Here, the time change (dV / dt) may be obtained by differentiating the signal V, or, for simplicity, a difference of the signal V in a very short time may be used instead of the differentiation. vice versa,
Time change of the output signal V from the throttle sensor 15 (d
If (V / dt) is larger than the predetermined value ΔV1, it is determined that the throttle valve 10 is moving to some extent, the process proceeds to step S420, and the detection timer is also cleared.
Return to normal control.

In step S404, the detection timer is incremented. This detection timer enters a motor lock detection routine, is incremented each time control is transferred to step S404, and its value is stored even after returning to normal control. Unless the determination results in steps S400 and S402 are both “Y”, the processing is cleared in step S420 before returning to the normal control. Therefore, the detection timer measures the elapsed time from when both the determination results in steps S400 and S402 become “Y”.

In step S406, it is determined whether or not the output value TH from the temperature sensor 60 is lower than a predetermined temperature THW. The values TH and THW both represent temperature (° C.). Here, the temperature sensor 60 measures the temperature near the throttle valve. The “temperature near the throttle valve” is, for example, the temperature of the cooling water of the engine, the atmospheric temperature,
The temperature of the engine itself. Here, the temperature sensor 60
Is assumed to reflect the temperature of the cooling water, but is not limited to this. If the temperature TH is equal to or lower than the value THW, it is determined that icing is likely to occur, and the process proceeds to step S408. Conversely, the temperature TH becomes the value TH
If it is larger than W, it is determined that icing has not occurred, and the process proceeds to step S418.

In step S408, it is determined whether the value of the detection timer is equal to or greater than a predetermined value T2. If the value of the detection timer is equal to or more than the value T2, the process proceeds to step S410. If the value is less than T2, the process returns to the normal control.

In step S418, step S418
Similarly to 408, it is determined whether the value of the detection timer is equal to or greater than a predetermined value T3. If the value of the detection timer is equal to or more than the value T3, the process proceeds to step S410. If the value is less than T3, the process returns to the normal control. Here, the relationship of T2> T3 holds for the values T2 and T3.

In step S410, after it is determined that the motor 30 is locked, the electronic throttle control is stopped.

In the above-described detection of the motor lock, the condition that the duty ratio D of the current flowing through the motor 30 is equal to or more than a predetermined value and the amount of change in the opening degree of the throttle valve 10 per unit time is equal to or less than a predetermined value is determined. If it continues for a certain time, it is determined that the motor is locked, and the electronic throttle control system is brought down. It should be noted that the motor lock state referred to here may be caused by icing,
It also includes those caused by gear biting or the like.

According to the present embodiment, when determining that the motor is locked, it is determined whether the temperature near the throttle valve 10 is equal to or lower than a predetermined temperature.
The time required to determine that the motor is locked is changed according to the result. Specifically, when the temperature is equal to or lower than the predetermined temperature, it is determined that the motor is locked after a longer time T2 has elapsed. That is, the throttle valve 10
If the temperature in the vicinity of is too low to cause icing of the throttle valve 10, the time until it is determined that the motor is locked is set longer than in the other case. As a result, at low temperatures, the time until the determination becomes longer, so that the possibility that the throttle valve 10 can recover from the icing state before the motor lock is determined (that is, the electronic throttle control ends) increases. Elements that contribute to recovery from the icing state include, for example, the torque of the motor 30 and heat generated from the engine. As a result, icing that recovers after waiting for a certain period of time is not determined to be in the motor locked state. In other words, only those that should be determined to be in the motor lock state, such as gears that are unlikely to be recovered even after waiting, are determined as such, and as a result, the motor lock is correctly detected. It works.

When the temperature in the vicinity of the throttle valve 10 is equal to or higher than the predetermined temperature and there is no possibility of the icing state, the time for determining the motor lock state can be shortened. it can. In addition,
In the present embodiment, the duty ratio D of the current flowing through the motor 30 is equal to or greater than a predetermined value and the throttle valve 10
It is determined that the motor is locked when the state in which the amount of change in the opening degree per unit time is equal to or less than a predetermined value continues for a predetermined time, but the duty ratio D of the current flowing through the motor 30 is equal to or more than the predetermined value. If a certain state continues for a predetermined time, it may be determined that the motor is locked. That is, in the motor locked state, it becomes difficult to control the throttle valve 10 to the target opening, and the duty ratio D of the current flowing through the motor 10 always increases, so that this state may be detected.

In this embodiment, the duty ratio D of the current flowing through the motor 30 is used as the parameter of the operation signal applied to the motor 30. This is because the motor is PWM
(Pulse width modulation) It is preferable to be controlled, but not limited to this. For example, when the motor is driven and controlled by changing the magnitude of the current flowing through the motor 30, the parameter of the operation signal of the motor 30 is the value of the current flowing through the motor.

A motor disconnection detection routine according to the present embodiment will be described below with reference to FIGS.

FIGS. 5A and 5B are waveform diagrams showing a time change of the signal I corresponding to the current flowing through the motor 30. FIG. 5A shows a case where the duty ratio D is small, that is, when the opening of the throttle valve 10 is small, and FIG. 5B shows a case where the duty ratio D is large, that is, the opening of the throttle valve 10. Indicates when is large. In FIG. 5, the value IOFF indicates the magnitude of the output signal I when the non-inverting input terminal and the inverting input terminal are short-circuited due to the offset error of the operational amplifier 46. In FIG.
The signals I shown in (a) and (b) both have a saw-tooth-like temporal change because the motor 30 is driven by the PWM method.

As can be seen from FIG. 5, when the duty ratio D is small, it is difficult to determine the disconnection of the motor 30 from the signal I alone. This is because even if the motor 30 is disconnected, the current appears to flow slightly even due to the offset error IOFF of the operational amplifier. In the motor disconnection detection routine according to the present invention, the motor disconnection is detected by using not only the motor current value I but also the duty ratio D, thereby accurately detecting the motor disconnection without being affected by the offset error of the operational amplifier 46. It is possible to detect.

FIG. 6 is a flowchart of the motor disconnection detection according to the present invention. The routine of FIG. 6 corresponds to step S of FIG.
308. Therefore, if the control is shifted to step S308 in FIG. 3, the motor disconnection detection in FIG. 6 starts, and if the control reaches “normal control” in FIG. 6, step S30 in FIG.
Control returns to 8.

In the motor disconnection detection of the present invention, first, in step S600, it is determined whether the duty ratio D is equal to or greater than a predetermined value D2. If D ≧ D2, it is considered that the signal I is sufficiently larger than the offset error of the operational amplifier 46, and the process proceeds to step S602 to perform disconnection detection. On the other hand, if D ≧ D2 is not satisfied, the signal I is not sufficiently large as compared with the offset error of the operational amplifier 46, so that the disconnection is not detected and step S610 is performed.
Return to normal control via. Therefore, the predetermined value D2
If there is no disconnection, the offset error IOFF
It is preferable to select a duty ratio at which a sufficiently large value I is obtained as compared with.

In step S602, it is determined that the signal I is equal to or less than a predetermined value I1. If I ≦ I1, the process proceeds to step S604. If I ≦ I1, the process proceeds to step S610. In step S610, the detection timer is cleared, and thereafter, the process returns to the normal control.

In step S604, the time is measured by incrementing the detection timer. The detection timer is incremented when D ≧ D2 and I ≦
If it is I1, otherwise, the detection timer is cleared and control returns to normal control.

In step S606, it is determined whether the value of the detection timer is equal to or greater than a predetermined value T4. If the value of the detection timer is equal to or longer than T4, the process proceeds to step S608,
It is determined that the motor is disconnected. Conversely, if the value of the detection timer is smaller than T4, the control returns to the normal control.

In step S608, it is determined that the motor is disconnected. If the motor is disconnected, the electronic throttle control ends.

As described above, in the detection of the motor disconnection according to the present embodiment, whether or not the disconnection has occurred is determined not only by the value I representing the current flowing through the motor 30 but by the duty ratio D of the pulse applied to the motor 30. The disconnection determination is performed only when is large to some extent. Therefore, when the offset error of the operational amplifier 46 affects the determination, the disconnection determination can be avoided, and as a result, the motor disconnection can be detected more accurately.

[0054]

According to the present invention, in the motor lock detection, when the engine temperature is low enough to cause the icing of the throttle valve, it is determined that the motor is locked after a longer time than when the engine temperature is not low. judge. That is, when the motor is locked by the icing of the throttle valve, there is provided a time allowance to escape from the icing. as a result,
It often recovers from icing before the motor lock is detected and the electronic throttle control system goes down, enabling more accurate motor lock detection.

Further, according to the present invention, in the detection of the motor disconnection, it is determined whether or not the disconnection has occurred only when the duty ratio of the motor current is large enough not to be affected by the offset error of the operational amplifier. As a result, it is possible to reduce the possibility that the disconnection is erroneously detected due to the offset error of the operational amplifier.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a throttle control device 1 according to the present invention.

FIG. 2 is a diagram showing a configuration of an ECU 50.

FIG. 3 is a flowchart showing the entire motor control.

FIG. 4 is a flowchart of motor lock detection according to the present invention.

FIGS. 5A and 5B are waveform diagrams showing a time change of a signal I corresponding to a current flowing through a motor 30. FIGS.

FIG. 6 is a flowchart of motor disconnection detection according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Throttle control device 10 Throttle valve 15 Throttle sensor 20 Electromagnetic clutch 30 Motor 40 Driver 42 Resistance 44 Power supply 46 Operational amplifier 50 ECU 60 Temperature sensor 70 Accelerator sensor 72 Accelerator pedal

Claims (2)

[Claims] 1. A throttle control device for controlling an opening degree of a throttle valve to a target opening degree by changing an operation signal given to a motor for driving the throttle valve. Is longer than the specified time, the first
A throttle control device comprising: means for detecting that the temperature is equal to or more than a predetermined value; and means for increasing the predetermined time when the temperature near the throttle valve is low enough to cause icing. 2. The throttle control device according to claim 1, further comprising means for detecting that the parameter is equal to or greater than a second predetermined value and that the current flowing through the motor is equal to or less than a third predetermined value.