JPH10196411A - Electronically controlled throttle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a degree of opening of a throttle valve from deviating by comparing a sensor signal which indicates a degree of opening of the throttle valve with an estimated sensor signal based on current step of a stepping motor and judging an abnormality in driving the stepping motor in accordance with the results of the comparison. SOLUTION: The current sensor output voltage for the time when a degree of opening of a throttle valve 200 is zero is calculated based on an output voltage of an opening degree sensor 208. The current estimated sensor output for the time when the degree of opening of the throttle valve 200 is zero is calculated based on the number of steps of a stepping motor 202 that an electronic control unit(ECU) 204 recognizes. The sensor output voltage and estimated sensor output voltage are monitored at all times. When an absolute value of the difference between these voltages exceeds a predetermined value, it is judged that a deviation occurs between the degree of opening of the throttle valve 200 that ECU 204 recognizes and actual degree of opening.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronically controlled throttle, and more particularly to an electronically controlled throttle for detecting a displacement of a rotor of a stepping motor.

[0002]

2. Description of the Related Art Conventional techniques (for example, Japanese Patent Application Laid-Open No. 61-8 / 1986)
433), there is known a method of obtaining an initial detection error of a throttle valve position sensor. In the device of the above publication, the sensor value is detected by comparing the sensor value when the throttle valve is at a predetermined position with the sensor value when the throttle valve is stopped at the next position. ing.

[0003]

However, according to the prior art, when the throttle valve is driven by the motor, it is possible to detect that the actual position of the rotor is shifted with respect to the input control signal to the motor. Did not. The reason will be described below.

FIG. 1 is a configuration diagram of a stepping motor. The stepping motor 100 generally has coils A and B, which are stators, and a rotor 102. When the rotor 102 is made of a ferromagnetic material such as iron, there are eight positions C to J where the rotor 102 can stop when a current is passed through the coil A. Even after the position is learned from the throttle position detection signal of the prior art described above, the position of the rotor may shift due to vibration or other disturbance, and as a result, the opening of the throttle valve may shift. For example, it is assumed that an electronic control unit (ECU) that controls the stepping motor 100 outputs a control signal to the stepping motor 100 so that the rotor stops at the position indicated by the solid line in FIG. In practice, the rotor 102
There is a possibility that the vehicle stops at a position shifted by the broken line in FIG. 1 (positions D to F and H to J). In this case, the ECU cannot recognize the displacement of the rotor 102. As a result, in the related art, it is possible that the control is performed while the displacement of the rotor exists. At this time, if the throttle valve is driven to the fully closed or fully opened state, the throttle valve hits the stopper and the stepping motor cannot drive the throttle valve. In such a case, there is a high possibility that the stepping motor loses synchronism and cannot be controlled.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has as its object to drive a stepping motor in which the position of the rotor of the stepping motor shifts, and as a result, the opening of the throttle valve shifts. An object of the present invention is to provide an electronic control throttle for determining an abnormality.

[0006]

An electronically controlled throttle according to the present invention is an electronically controlled throttle which drives a throttle valve by a stepping motor, based on a current step of the stepping motor and a given target step. Control means for driving the stepping motor so that the stepping motor approaches the target step; and means for inputting an initial value to the current step when the position of the throttle valve is at a predetermined opening.
Detecting means for outputting a sensor signal indicating the position of the throttle valve; comparing the sensor signal with a contact sensor signal obtained based on the current step; and driving the stepping motor according to the result of the comparison. Means for determining an abnormality, whereby the above object is achieved.

In one embodiment, the current step is corrected so that the current step corresponds to the position of the throttle valve represented by the sensor signal.

[0008]

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

FIG. 2 is a block diagram of the electronic control throttle of the present invention. The electronic control throttle 20 includes a throttle valve 200, a stepping motor 202 for driving the throttle valve 200, and an ECU 204 for driving the stepping motor 202. The stepping motor 202 controls the throttle valve 200 via a gear 206 in accordance with a control signal output from the ECU 204.
Drive. The gear 206 is connected to the stepping motor 202
After reducing the angular velocity of the rotor of the throttle valve 20
Tell 0. Accelerator sensor 210 outputs a signal corresponding to the amount of depression of accelerator pedal 212 to ECU 204. The opening sensor 208 is connected to the throttle valve 200.
Is output to the ECU 204. The idle contact 209 is a switch that is turned on when the opening of the throttle valve 200 is equal to or less than a reference opening a described later, and is turned off when the opening is larger than the reference opening a. A signal representing 1 and 0 in each case. Is output to the ECU 204.

The ECU 204 includes a central processing unit (CP)
U) 250, a read-only memory (ROM) 252, and a random access memory (RAM) 254. The stepping is performed so that the opening of the throttle valve 200 becomes a desired value in accordance with the depression amount of the accelerator pedal 212. The motor 202 is controlled. ROM 252 is
For example, a procedure for controlling the stepping motor 202 described below is stored. The RAM 254 temporarily stores, for example, parameters necessary for the electronic control throttle 20.

FIG. 3 is a schematic diagram showing the movable range of the throttle valve 200. The vertical axis in FIG. 3 represents the opening of the throttle valve 200, and the opening increases as going upward. A mechanical stopper is provided at each of the fully open position and the fully closed position of the throttle valve 200. These stoppers are attached to the throttle valve 20
0 is located between the fully open position and the fully closed position,
The movement of the throttle valve 200 is mechanically restricted. Assuming that the fully closed position of the throttle valve 200 is about 0 °, the fully open position is about 90 °. A “reference opening a” is set in the throttle valve 200, and the value of the opening a is, for example, about 5 °. This reference opening a is sometimes called an “idle position”.
Just because the opening degree of 0 is equal to the reference opening degree a, the engine is not necessarily in an idling state.

FIGS. 4A and 4B respectively show an opening sensor 208 for the opening of the throttle valve 200.
Showing the change in the voltage outputted by the throttle valve 200 and the number of steps of the stepping motor.
5 is a graph showing a change in the opening degree of the circumstance. (A) and (b) of FIG.
, The opening a is the aforementioned reference opening. In FIG.
As shown in (a), the voltage output from the opening sensor 208 increases linearly with respect to the opening of the throttle valve 200. The slope A [V / degre) in FIG.
e] indicates the magnitude of the output voltage that increases per degree of opening, and corresponds to the slope of the graph. This inclination A is a value determined by the characteristics of the opening sensor 208.

As shown in FIG. 4B, the opening of the throttle valve 200 increases linearly with respect to the number of steps of the stepping motor. The slope B [degree / step] in (b) of FIG. 4 indicates the degree of opening of the throttle valve that increases per step, and corresponds to the slope of the graph. The slope B is a value determined by the throttle valve 200, the stepping motor 202, and the gear 206. In the present invention, as described later, the number of steps of the stepping motor is the number of steps recognized by software executed by the ECU 204.

FIG. 5 is a diagram showing a procedure for learning a reference position. This procedure only needs to be executed when the IG switch (a switch associated with the ignition key) is turned on from off. Here, the reference position refers to the opening degree a described above. According to the electronic control throttle of the present invention, the opening of the throttle valve 200 is set to the reference opening a.
An idle contact 209 is turned on in the following cases, and turned off when it is larger than the reference opening a. When the IG switch is off, the opening of the throttle valve 200 is larger than the reference opening a.

In step S502, the opening sensor 208
Is calculated from the voltage TAAD output from. Opening sensor 20
The voltage TAAD from 8 can take a continuous analog value. The voltage TAAD represents an output voltage from the opening sensor 208 corresponding to the current opening c in FIG.

In step S504, the target step ST
Subtract one from EPT. In step S506, the output WIDL of the idle contact 209 changes from 0 (L level) to 1
(H level). Output WI
DL can take a value of either 0 or 1. If yes (Y), the process proceeds to step S508, and no (N)
In the case of, the process returns to step S504. Output WIDL is 0
, The opening of the throttle valve 200 is larger than the reference opening a. Conversely, when the output WIDL is 1, the opening of the throttle valve 200 is equal to or smaller than the reference opening a. Therefore, the control is transferred from the loop of steps S504 and S506 to step S508 immediately after the output WIDL of the idle contact 209 changes from 0 to 1, that is, the opening of the throttle valve 200 is substantially equal to the reference opening a. Is equal to

In step S508, the voltage T at this time is
These values are initialized by substituting AAD for the variables GTAUP [V], GTADWN [V] and GTA [V]. In step S510, the initial value KSTEPINT is substituted for the current step STEPC. By this step, every time the IG switch is turned on, the value KSTE, which is the value that should originally have at the reference opening a, is
PINIT is assigned to the current step STEPC.
The above variables GTAUP, GTADWN and GTA are:
For example, it can be realized in the form of a variable in a program executed by the ECU 204, and actual data is stored in the RA of the ECU 204.
It is stored in M254.

Here, the current step STEPC is EC
The value used by the program executed by U204 has a value (for example, a non-negative integer value) corresponding to the position of the rotor of the stepping motor 202. Current step ST
When EPC is incrementing one by one, EC
This is when U204 drives the stepping motor 202 one step at a time and rotates the throttle valve 200 in a direction to increase its opening. Current step S
When the TEPC is decrementing one by one, EC
This is when the U 204 drives the stepping motor 202 one step at a time and rotates the throttle valve 200 in a direction in which the opening degree decreases. In other words, it can be said that the current step STEPC is the position information of the rotor of the stepping motor 202, which is recognized by the control program of the ECU 204. Therefore, as described above, when the position of the rotor of the stepping motor 202 is displaced due to disturbance or the like, the step STEPC may have a value that does not reflect the actual position of the rotor.

In step S512, the current step S
A step STEPZ at which the opening of the throttle valve 200 becomes zero is obtained from TEPC, that is, KSTEPINT, and the gradient B shown in FIG. 4B. When the procedure of FIG. 5 ends, the procedure of FIG. 6 is executed thereafter, for example, every 8 ms.

FIG. 6 is a diagram showing a procedure for correcting the number of steps recognized by the ECU 204 based on the voltage from the opening sensor 208. This procedure is executed for a relatively short time, for example, every 8 ms. In step S602, the voltage TAAD from the opening sensor 208 is obtained. In step S604, it is determined whether the output WIDL of the idle contact 209 has changed from 0 to 1. In the case of Y, the process proceeds to step S606, and in the case of N, the process proceeds to step S608. When control is transferred to step S606, that is, when the output WIDL changes from 0 to 1, it is when the opening of the throttle valve 200 shifts from a state larger than the reference opening a to a state equal to or less than the reference opening a. When such a state transition occurs, the voltage TAAD is substituted for a variable GTADWN [V], and the process proceeds to step S611.

In step S608, it is determined whether the output WIDL of the idle contact 209 has changed from 1 to 0. In the case of Y, the process proceeds to step S610, and in the case of N, the process proceeds to step S611. When the control shifts to step S610, that is, when the output WIDL changes from 1 to 0, the opening of the throttle valve 200 becomes equal to the reference opening a.
It is time to move from the following state to a state larger than the reference opening a. When such a state transition occurs, the voltage T
After substituting AAD for the variable GTAUP [V], the process proceeds to step S611.

In step S611, the variable GTADWN
And the average of the values represented by the variables GTAUP are obtained and substituted into the variable GTA [V]. If the determination results in steps S604 and S608 are both N, the variables GTAUP and GT already initialized in step S508
Based on ADWN, voltage TAAD is substituted for variable GTA. Therefore, in steps S602 to S611, based on the output signals from the opening sensor 208 and the idle contact 209, the voltage GTA [V] corresponding to the actual reference opening a shown in FIG. Will be. The reason why the average value is obtained in the above calculation process is to increase the accuracy of the output value from the opening sensor 208 at the reference opening a. As a result, the throttle valve 20
Even when the output voltage from the opening degree sensor 208 when the zero moves has a hysteresis characteristic, the error of the voltage GTA can be reduced.

In step S612, (GTA- (a × A)) is calculated based on the value of the variable GTA and the gradient A [V / degree] shown in FIG.
Substitute for This value corresponds to a value estimated to be output by the opening sensor 208 when the opening is zero. That is, the variable TAZVT obtained in step S612 can be obtained by comparing the output from the opening sensor 208 at the reference opening a with the known reference opening a without the need to actually drive the throttle valve 200 to the state where the opening is zero. , Can be uniquely calculated from the unique inclination A by the opening degree sensor 208.

In step S614, the value TACV is subtracted from the voltage TAAD by subtracting the value of the variable TAZVT.
Calculate T. As shown in FIG. 4A, the value TACVT is obtained by subtracting the voltage TAZVT corresponding to the point where the opening is zero from the voltage TAAD corresponding to the current opening c. This value TACVT represents the current sensor output voltage with respect to the voltage when the opening is zero, which is calculated based on the voltage output from the opening sensor 208.

In step S616, the current step S
Step STEPZ corresponding to zero opening from TEPC
To obtain the difference, and further multiply by the slopes A and B. That is, the opening degree c [degree] is calculated from the steps STEPC and STEPZ and the inclination B, and the voltage TASTPVT corresponding to the opening degree c is obtained by multiplying the inclination A by the degree. This value TASTPVT represents the current estimated sensor output with respect to the voltage when the opening is zero, calculated based on the number of steps of the stepping motor recognized by the ECU 204.

One of the features of the electronic control throttle according to the present invention is that the sensor output voltage TACVT and the estimated sensor output voltage TASTPVT described in the description of steps S614 and S616 are always (about 8 ms in this embodiment).
Each time), when the absolute value of the difference between these voltages becomes larger than a predetermined value, it is determined that there is a deviation between the opening of the throttle valve 200 recognized by the ECU 204 and the actual opening. It is to judge. When this shift occurs, the opening degree of the throttle valve 200 recognized by the ECU 204, that is, the current step STEP
By adding or subtracting the correction value from C, the difference between the actual opening and the opening recognized by the ECU 204 is gradually reduced. Since this operation is repeatedly performed, the ECU 204 can always accurately grasp the actual opening. As a result, according to the present invention, even when the throttle valve 2 is driven to the fully open or fully closed state,
Since 00 does not hit the stopper, step-out of the stepping motor 202 can be prevented.

In step S618, the timer variable CST
It is determined whether PCHG is greater than T1 [ms]. This timer variable CSTPCHG is counted up in real time. If the determination result in step S618 is N, the process proceeds to END, and if it is Y, the process proceeds to step S620. By providing this step S618, it is possible to correct the step STEPC executed after step S620 after a sufficient time (for example, 1 s) has elapsed for the rotor of the stepping motor 202 to move to the target step.

In step S620, the sensor output voltage TACVT and the estimated sensor output voltage TASTPVT
Then, it is determined whether or not the absolute value of the difference is larger than a predetermined value KTAVTF. If the determination result is Y, step S6
Proceed to 22; if N, proceed to END. If the determination result in step S620 is Y, that is, if the absolute value of the difference between the sensor output voltage TACVT and the estimated sensor output voltage TASTPVT is larger than a predetermined value, the actual position of the rotor of the stepping motor 202 and the ECU 204 Is determined to be different from the position of the rotor recognized by the control program (that is, the driving of the stepping motor 202 is in an abnormal state). Based on the determination result, as described later, the step STEPC corresponding to the current rotor position recognized by the control program of the ECU 204 may be corrected, or a process of simply issuing a warning may be performed. If the current step STEPC recognized by the ECU is corrected so as to be closer to the actual rotor step, it is possible to gradually correct the motor drive abnormality while continuing the electronic control of the throttle valve. Is more preferable.

In step S622, the sensor output voltage T
It is determined whether the estimated sensor output voltage TASTPVT is higher than ACVT. When the determination result is Y, the process proceeds to step S624, and when the determination result is N, the process proceeds to step S626.

In step S624, the sensor output voltage T
Since the estimated sensor output voltage TASTPVT is larger than ACVT, the predetermined value KS is calculated from the current step STEPC.
Subtract TPREST (positive integer value). Where the value KST
PREST is, for example, the number of steps of the stepping motor 202 corresponding to the opening degree of the throttle valve 200 of 2.4 °, and corresponds to the minimum number of steps in which the rotor may shift. This value KSPREST is a value determined by the configuration of the stepping motor 202.

In step S626, it is determined whether the sensor output voltage TACVT is higher than the estimated sensor output voltage TASTPVT. If the determination result is Y, the process proceeds to step S628, and if the determination result is N, the process proceeds to END.

In step S628, since the sensor output voltage TACVT is larger than the estimated sensor output voltage TASTPVT, a predetermined value KSTP is added to the current step STEPC.
Add REST (positive integer value).

If any correction has been made to the current step STEPC in step S624 or S628, zero is substituted for the variable CSTPCHG of the count-up timer in step S630, and the timer is cleared.

FIG. 7 is a diagram showing a procedure used by the electronically controlled throttle according to the present invention to drive the stepping motor. This procedure involves switching the energized phase of the stepping motor, that is,
It is executed every time step driving is performed. Step S702
Then, the current step STEPC is the target step STE
It is determined whether it is the same as PT. If the result of the determination is Y, that is, if STEPT = STEPC, the procedure ends because there is no need to drive the stepping motor 202. Conversely, if the determination result is N, that is, if STEPT = STEPC is not satisfied, the stepping motor 202 needs to be driven.
Proceed to 704 to drive.

In step S704, the current step S
It is determined whether TEPC is greater than the target step STEPT. If the determination result is Y, that is, if the current step STEPC is larger than the target step STEPT, it is necessary to rotate the throttle valve 200 to the closing side.
2 is driven to the closing side by one step. Step S70
In step S708 following step 6, the current step STE
The drive result is reflected by subtracting 1 from the PC.

If the result of the determination in step S704 is N, it is determined in step S710 whether the current step STEPC is smaller than the target step STEPT.
If the determination result is Y, that is, the current step STEPC
Is smaller than the target step STEPT, it is necessary to rotate the throttle valve 200 to the open side, so that the stepping motor 202 is driven to the open side by one step in step S712. In step S714 following step S712, the driving result is reflected by adding 1 to the current step STEPC.

The procedure described above can be realized by hardware, software, or a combination thereof.

[0038]

According to the present invention, it is possible to provide an electronically-controlled throttle for determining a drive abnormality of a stepping motor in which the position of the rotor of the stepping motor shifts and as a result, the opening of the throttle valve shifts.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a stepping motor.

FIG. 2 is a configuration diagram of an electronic control throttle of the present invention.

FIG. 3 is a schematic diagram showing a movable range of a throttle valve 200.

FIGS. 4A and 4B are graphs showing a change in voltage output from an opening sensor 208 with respect to the opening of the throttle valve 200, and the opening of the throttle valve 200 with respect to the number of steps of a stepping motor, respectively. It is a graph which shows a change of a degree.

FIG. 5 is a diagram showing a procedure for learning a reference position.

FIG. 6 is a graph showing EC based on a voltage from an opening sensor 208;
It is a figure showing the procedure which corrects the number of steps recognized in U204.

FIG. 7 illustrates a procedure used by an electronically controlled throttle according to the present invention to drive a stepper motor.

[Explanation of symbols]

 Reference Signs List 20 electronic control throttle 200 throttle valve 202 stepping motor 204 ECU 206 gear 208 opening sensor 209 idle contact 210 accelerator sensor 212 accelerator pedal 250 CPU 252 ROM 254 RAM

Claims (2)

[Claims] 1. An electronically controlled throttle for driving a throttle valve by a stepping motor, such that the stepping motor approaches the target step based on a current step of the stepping motor and a given target step. Control means for driving the stepping motor; means for inputting an initial value to the current step when the position of the throttle valve is at a predetermined opening; detection for outputting a sensor signal indicating the position of the throttle valve Means for comparing the sensor signal with an estimated sensor signal obtained based on the current step, and determining a drive abnormality of the stepping motor according to a result of the comparison. throttle. 2. The electronically controlled throttle according to claim 1, further comprising means for correcting said current step so that said current step corresponds to a position of said throttle valve indicated by said sensor signal.