JP2004052665A - Opening detection system for throttle valve - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an opening detection system for a throttle valve, having conformity between the reduction of cost and security of reliability. <P>SOLUTION: An electronic control throttle device includes a throttle valve driven to open and close by a brushless motor. A rotation pulse signal formed at every designated angle of rotation of the motor is generated from a rotor position detection signal of the motor. The rotation pulse signal is input to a rotating direction detecting part 42 and an up-down counter 43. The rotating direction of the motor and the pulse integration number are input to a throttle opening estimating part 44, and a throttle opening is estimated from the motor rotating angle in consideration of a reduction gear ratio. The shaft rotating angle of a throttle valve is calculated by an A/D conversion and angle computing part 45 receiving an output signal from a Hall IC of a sensor part. An angle sensor failure detecting part 46 compares the estimated opening of the throttle valve with the detected opening of the Hall IC to detect a failure of the Hall IC. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an opening detection system for a throttle valve of an engine, and more particularly, to an opening detection of a throttle valve driven by a brushless motor.
[0002]
[Prior art]
2. Description of the Related Art In recent years, so-called electronically controlled throttle devices that drive a throttle valve of an engine by a motor have been widely used with the digitization of automobile parts. Here, the throttle valve is controlled by an electric signal instead of the mechanical operation by the conventional accelerator wire. The accelerator depression amount is electrically detected by a potentiometer or the like, and a motor is driven according to the value to open and close the throttle valve.
[0003]
In such an electronically controlled throttle device, the opening of the throttle valve is determined by attaching a magnet to a shaft on which the valve body is fixed, and detecting a change in magnetic flux with a magnetic detection element such as a Hall element. Japanese Patent No. 2920177 discloses a magnetic position sensor using a Hall element in consideration of use in an automobile. In this patent, a cylindrical yoke having a permanent magnet attached to the inner circumference is fixed to a drive shaft for which angular velocity is to be measured. A stator is arranged inside the magnet, and a Hall element is accommodated in a slit-shaped magnetic gap provided in the stator. When the permanent magnet rotates together with the drive shaft, the magnetic flux around the Hall element changes, and a signal corresponding to the change is output from the Hall element. This signal change corresponds to the rotation angle of the drive shaft. Therefore, the rotation angle of the drive shaft can be calculated based on the signal from the Hall element, and the opening of the throttle valve can also be detected using this magnetic position sensor.
[0004]
However, in the magnetic position sensor disclosed in Japanese Patent No. 2920179, since only one Hall element is mounted on each sensor, if the Hall element fails, the rotation angle of the drive shaft cannot be detected at all. That is, it is impossible to grasp the throttle opening at all, which causes serious trouble in controlling the engine, which is the heart of the vehicle. Therefore, in a rotation angle sensor for detecting a throttle opening, a redundant design is provided in which another backup hall element is provided in preparation for a failure of the hall element. For example, Japanese Patent Application Laid-Open No. 2001-208510 and Japanese Patent Application Laid-Open No. 2001-289610 show a rotation angle detection device in which two Hall ICs are arranged in a configuration similar to that of Japanese Patent No. 2920179.
[0005]
FIG. 8 is an explanatory diagram showing a configuration of a conventional rotation angle detecting device. A hub 51 is attached to a shaft to which the throttle valve is fixed, and an iron rotor core 52 is attached to the inner periphery thereof. A magnet 53 is further fixed to the inner peripheral side of the rotor core 52. A stator core 54 is arranged inside the magnet 53 coaxially with the hub 51. A slit 55 is provided at the center of the stator core 54, and two Hall ICs 56 are arranged therein. From the Hall ICs 56a and 56b, a voltage signal corresponding to the magnetic flux density interlinking is output, and the outputs of the two Hall ICs 56a and 56b are compared with each other to confirm whether there is any abnormality and to determine the rotation angle of the hub 51, That is, the opening of the throttle valve is detected.
[0006]
[Problems to be solved by the invention]
However, since the Hall IC used in such a rotation angle detection device needs to compensate for the temperature characteristics of the magnet, that is, the change in the magnetic flux density of the magnet due to the temperature change, a temperature-compensated linear output Hall IC is used. There is a need to. This type of Hall IC is very expensive compared to the general type, and using two of them increases the cost of the device. While temperature compensation is required for accurate angle detection, multiple Hall ICs are required for backup against failures, and the development of a system that can achieve both cost reduction and reliability is desired. I was
[0007]
SUMMARY OF THE INVENTION It is an object of the present invention to provide a throttle valve opening detection system that can achieve both cost reduction and reliability.
[0008]
[Means for Solving the Problems]
An opening detection system for a throttle valve according to the present invention is an opening detection system for the throttle valve in an electronically controlled throttle device including a throttle valve driven to be opened and closed by a brushless motor, wherein the throttle valve is fixed and the brushless A shaft that is rotationally driven by a motor, a hub that is attached to the shaft and includes a magnet that rotates with the shaft, a magnetic sensing element, and a stator core that is arranged coaxially with the hub; and An opening calculating means for calculating an opening of the throttle valve based on an output signal of the magnetic detecting element which changes according to an opening degree; and an opening estimation for estimating an opening of the throttle valve based on a rotor position detection signal of the brushless motor. Means, the detected opening of the throttle valve and the opening estimation by the opening calculating means Characterized in that by comparing the estimated opening degree of the throttle valve according to stages and a failure detection unit that performs failure detection of the magnetic detection element.
[0009]
In the throttle valve opening detection system of the present invention, the throttle valve opening is estimated from the rotor position detection signal of the brushless motor, and the estimated value is calculated based on the output signal of the magnetic detection element. It is possible to control the opening degree of the throttle valve while performing the failure diagnosis of the magnetic detection element as compared with the case of FIG. Therefore, it is possible to determine a failure without using two expensive temperature-compensation type linear output Hall ICs, and it is possible to reduce the cost of the apparatus by reducing one Hall IC while ensuring reliability. It becomes.
[0010]
In the throttle valve opening detection system, the opening estimating means calculates a rotation angle of the shaft based on a rotation pulse signal generated from the rotor position detection signal and formed every time the brushless motor rotates a predetermined angle. A throttle valve opening detection system, which calculates and estimates the opening of the throttle valve.
[0011]
In the throttle valve opening detection system, a rotor core formed of a magnetic material in a cylindrical shape on the hub and having the magnet fixed to an inner peripheral surface thereof is provided, and the stator core is formed of a magnetic material, and the inside of the magnet is formed inside the magnet. And one magnetic detection element may be attached.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a cross-sectional view showing a configuration of an electronic control throttle valve to which an opening detection system according to the present invention is applied, and FIG. 2 is a cross-sectional view taken along line AA of FIG. The electronically controlled throttle valve of FIG. 1 is arranged in the intake passage of the engine, and controls the intake air amount of the engine by the opening degree of the throttle valve 1. The throttle valve 1 is fixed to a shaft 2 and is driven by a brushless motor 3 (hereinafter abbreviated as motor 3) via a speed reduction mechanism 15 including gears 11 to 14.
[0013]
The shaft 2 is rotatably supported by bearings 16a and 16b fixed to a metal housing 4. A cover 5 made of a synthetic resin is attached to an upper portion of the housing 4 in FIG. A torsion coil spring 17 is attached to the gear 11 fixed to the shaft 2. The shaft 2 is urged in a predetermined rotational direction by the torsion coil spring 17, and the urging force causes the throttle valve 1 to automatically return to the fully closed position.
[0014]
At the end of the shaft 2, a sensor unit 6 for detecting the opening of the throttle valve 1 is provided. FIG. 3 is an explanatory diagram illustrating the configuration of the sensor unit 6. In the sensor unit 6, a hub 20 made of a synthetic resin is fixed to an end of the shaft 2. The hub 20 is formed in a stepped cylindrical shape, and a rotor core 21 formed of a magnetic material such as iron is attached to the inner peripheral side. A magnet 22 is further fixed to the inner periphery of the rotor core 21. The magnet 22 is formed in a cylindrical shape by two magnets, an upper half part and a lower half part, and has a so-called radial magnetization in which the direction of the line of magnetic force is in the radial direction. The upper half portion of the magnet 22 is magnetized such that the inner peripheral side has an N pole and the outer peripheral side has an S pole, and the lower half portion has been magnetized such that the inner peripheral side has an S pole and the outer peripheral side has an N pole. .
[0015]
A substrate 23 is fixed inside the cover 5, and a stator core 25 on which a Hall IC 24 is arranged is attached to the substrate 23. The stator core 25 is also formed of a magnetic material such as iron in a columnar shape, and has a slit 26 at the center. As shown in FIG. 3, the stator core 25 is vertically divided into two parts by the slits 26, and an air gap is formed at the center. When the cover 5 is attached to the housing 4, the stator core 25 is disposed coaxially with the hub 20 inside the magnet 22. Thereby, a uniform air gap is formed between the outer peripheral surface of the stator core 25 and the inner peripheral surface of the magnet 22.
[0016]
One Hall IC 24 is arranged in the slit 26 forming the air gap. The Hall IC 24 is an IC in which a Hall element (magnetic detection element) and a signal amplifier circuit are integrated, and is a temperature-compensated linear output Hall IC that corrects temperature characteristics. From the Hall IC 24, a voltage signal corresponding to the magnetic flux density passing through the slit 26 and interlinking with the Hall IC 24 is output.
[0017]
As shown in FIG. 1, the motor 3 is a so-called inner rotor type brushless motor in which a rotor 32 is rotatably arranged inside a stator 31. The stator 31 includes a drive coil 33 and a stator core 34 around which the coil 33 is wound, and is fixed to the substrate 23. The stator core 34 is formed by laminating metal plates, and the winding is formed by winding the drive coil 33 around salient poles projecting from the inner peripheral side. The substrate 23 is provided with a Hall IC (not shown) for detecting the rotational position of the rotor 32. The Hall IC outputs a rotor position detection signal as the rotor 32 rotates.
[0018]
The rotor 32 includes a rotor shaft 35, a rotor core 36 fixed to the rotor shaft 35, and a rotor magnet 37 fixed to the outer periphery of the rotor core 36. The rotor magnet 37 is formed in a cylindrical shape, and has two poles of N and S (the number of pole pairs is 1). The rotor shaft 35 is rotatably supported by bearings 38a and 38b. The bearing 38a is attached to the cover 5 and the bearing 38b is attached to a bracket 39 attached to the housing 4. On the rotor core 36, a columnar magnet mounting portion 36a and the gear 14 are formed. The gear 14 meshes with the gear 13 of the idler gear 18. The idler gear 18 is rotatably supported by a gear shaft 19 fixed to a bracket 39. The idler gear 18 is formed with a gear 12 integrally with the gear 13, and the gear 12 meshes with the gear 11 fixed to the shaft 2. Thereby, the rotation of the rotor 32 in the motor 3 is reduced and transmitted to the shaft 2.
[0019]
In such an electronically controlled throttle valve, an output signal from the Hall IC 24 of the sensor unit 6 and a rotor position detection signal from the Hall IC of the motor 3 are sent to a control device having a control system as shown in FIG. FIG. 4 is a block diagram showing a configuration of a control system in the electronically controlled throttle valve. The control device (CPU) 41 calculates the rotation angle of the hub 20, that is, the rotation angle (valve opening) of the throttle valve 1 based on the output signal from the Hall IC 24. In addition, the rotation angle of the hub 20 is estimated based on the rotor position detection signal, and the results of the two are compared with each other to determine whether there is any abnormality and to control the opening of the throttle valve 1.
[0020]
The control device (CPU) 41 receives rotation pulse signals (1) to (6) generated based on a rotor position detection signal of the motor 3. FIG. 5 is an explanatory diagram showing the configuration of the rotation pulse signal. The rotation pulse signal is a one-shot pulse signal output every time the motor 3 rotates by a predetermined angle. As shown in FIG. 5, the rotation pulse signal of each phase (U, V, W) of the rotor position detection signal (sensor signal) is used. Generated by capturing rising and falling edges. That is, the rotation pulse signal (1) is generated by the rising edge of the U-phase sensor signal, the rotation pulse signal (2) by the falling edge of the W-phase sensor signal, and the rotation pulse signal (3) by the rising edge of the V-phase sensor signal. Is generated. Next, a rotation pulse signal (4) is generated by the fall of the U-phase sensor signal, a rotation pulse signal (5) by the rise of the W-phase sensor signal, and a rotation pulse signal (4) by the fall of the V-phase sensor signal. 6 ▼ is generated. Since the motor 3 is a three-phase full-wave energized DC brushless motor having one pole pair, the rotation pulse signal is output every electrical angle of 60 °.
[0021]
The control device 41 receives these rotation pulse signals (1) to (6), forms a pulse signal by logically synthesizing them, and inputs the pulse signal to the up / down counter 43. On the other hand, the rotation pulse signals (1) to (6) are input to the rotation direction detector 42, and the rotation direction of the motor 3, that is, the operation direction of the throttle valve 1 (open direction or not) is determined from the logical order derived from the input order of each signal. Is determined to be the closing direction). For example, when the rotation pulse signals {circle around (1)} to {circle around (6)} have U, V and W logics as shown in FIG. If signal (1) comes later, it can be determined that the rotation is reversed. The result of this determination is also input to the up / down counter 43, from which the rotation direction and the number of accumulated pulses are input to the throttle opening estimating unit (opening estimating means) 44.
[0022]
The throttle opening estimating unit 44 obtains the rotation angle of the rotor 32 of the motor 3 based on the number of accumulated pulses, and calculates the rotation angle of the shaft 2 from this and the reduction ratio of the reduction mechanism 15. In this case, since the rotation angle of the shaft 2 is 0 to 90 ° corresponding to the valve opening, if the reduction ratio is R, the rotation angle of the rotor 32 is 0 to 90R °. Since one rotation pulse signal is output for each electrical angle of 60 ° by the motor 3 having one pole pair, if the number of pole pairs of the motor 3 is P, the rotation pulse signal is generated for the opening degree of the throttle valve 1 of 90 °. Is 90R × P / 60 = 1.5 × R × P. That is, the throttle opening estimating unit 44 can estimate the opening of the throttle valve 1 with the resolution N = 1.5 × R × P. FIG. 6 is an explanatory diagram showing the relationship between the increase and decrease of the rotation pulse signal and the throttle opening. As shown in FIG. 6, the opening of the throttle valve 1 can be estimated stepwise by adding or subtracting the rotation pulse signal, and the resolution becomes N. In this electronically controlled throttle valve, if the reduction ratio is 10, for example, P = 1, so N = 15, and the opening of the throttle valve 1 can be estimated at 6 ° intervals.
[0023]
On the other hand, an output signal of the Hall IC 24 is input from the sensor unit 6 to the control device 41. The output signal of the Hall IC 24 is input to an A / D conversion and angle calculation unit (opening calculation unit) 45, and the analog signal from the Hall IC 24 is converted into a digital signal. ) Is calculated. In this case, there is a fixed relationship between the output voltage of the Hall IC 24 and the rotation angle of the hub 20, and the rotation angle of the hub 20 can be calculated from the output voltage value of the Hall IC 24.
[0024]
FIG. 7 is an explanatory diagram showing the relationship between the magnetic flux density in the slit 26 and the rotation angle of the hub 20. In the sensor section 6, the magnetic flux density passing through the slit 26 changes according to the rotation angle of the hub 20. Assuming that the position of the magnet 22 as shown in FIG. 3, that is, the position where the polarity switching portion 27 is parallel to the slit 26 is 0 °, a magnetic circuit as shown by a broken line is established there, and the magnetic flux of the magnet 22 is 25 from one side to the other. When the hub 20 rotates, a magnetic flux flows in the opposite direction to the previous case, and the magnetic fluxes cancel each other, so that an amount of magnetic flux corresponding to the difference between the two flows through the slit 26. As the hub 20 rotates, the amount of magnetic flux flowing through the slit 26 changes, and when the hub 20 rotates 90 °, the magnetic flux density becomes zero. As the hub 20 further rotates, the direction of the magnetic flux is reversed and reaches an extreme value at 180 °. Thereafter, when the hub 20 rotates by 270 °, the magnetic flux density becomes 0 again, the direction of the magnetic flux is reversed, and the position returns to the position of FIG. 3 (360 °).
[0025]
When the magnetic flux density passing through the slit 26 changes in this manner, the output of the Hall IC 24 also changes linearly in accordance with the change. The A / D conversion and angle calculation unit 45 has a change in the output of the Hall IC 24 corresponding to a change in the magnetic flux density as shown in FIG. Thus, the rotation angle of the hub 20, that is, the rotation angle (opening) of the throttle valve 1 is calculated from the output voltage value of the Hall IC 24 by referring to a table or the like.
[0026]
The estimated opening of the throttle valve 1 by the throttle opening estimating unit 44 and the detected opening of the throttle valve 1 by the A / D conversion / angle calculating unit 45 are input to an angle sensor failure detecting unit (failure detecting means) 46. The angle sensor failure detection unit 46 determines whether or not the valve opening calculated based on the output voltage of the Hall IC 24 is within a predetermined angle difference from the estimated angle calculated from the rotation angle of the motor 3. . Although the angle difference between the two differs depending on the resolution of the estimated angle, about three rotation pulse signals are set (in the above example, 3 × 6 ° = 18 ° = ± 9 °).
[0027]
If the valve opening determined by the two signals having different output systems falls within a predetermined angle difference, it is determined that the Hall IC 24 is operating normally, and the detection opening in the A / D conversion / angle calculation unit 45 is performed. Is output as a throttle opening signal. The throttle opening signal is sent to a motor driver (not shown) of the control device 41, and the opening of the throttle valve 1 is feedback-controlled based on the accelerator depression amount, the engine temperature, the load, and the like. On the other hand, when the estimated opening and the detected opening are outside the predetermined angle difference, it is determined that the Hall IC 24 has failed, and an abnormality determination signal is output. When the abnormality determination signal is output, a display is immediately displayed to notify the driver of the failure, and the throttle valve 1 is controlled at the estimated angle obtained by the throttle opening estimating unit 44.
[0028]
Note that, between the A / D conversion / angle calculation unit 45 and the up / down counter 43, the initial output voltage of the Hall IC 24 and the initial value of the up / down counter 43 are associated by the initial reset, and the rotation angle of the shaft 2 and the motor 3 Are synchronized. In this case, the initial output voltage of the Hall IC 24 changes depending on how many times the opening degree of the throttle valve 1 is used as a reference, and 0 V is not always the initial value. For example, the output of the Hall IC 24 may be set to zero at the opening of the throttle valve 1 during idle operation (for example, 15 °). Therefore, by resetting the initial values of the A / D conversion / angle calculation unit 45 and the up / down counter 43, the comparison with the estimated value is effective even in such a case, and it is possible to perform a wide range of throttle opening control. Become.
[0029]
As described above, in an apparatus using a brushless motor as a drive source of the throttle valve, the rotor position is detected on the motor side, and the rotation angle of the motor can be detected by using the signal. Once the motor rotation angle is known, the opening of the throttle valve 1 can be estimated by multiplying the motor rotation angle by the reduction ratio, and the opening of the throttle valve 1 can be controlled while performing a failure diagnosis without using a backup Hall IC. It is possible to do. For this reason, one expensive temperature compensation type linear output Hall IC can be reduced, and the cost of the device can be reduced while ensuring reliability.
[0030]
Since the rotation pulse signal obtained from the rotor position detection signal is a one-shot pulse signal output when the motor rotates by a predetermined angle, the opening degree of the throttle valve is a stepwise estimated value having a certain resolution. However, as a value acquired for the failure diagnosis of the Hall IC 24, an estimated value with a resolution of about 10 ° is sufficient, and with this level of resolution, it is possible to perform the minimum engine operation.
[0031]
The present invention is not limited to the above embodiment, and it goes without saying that various changes can be made without departing from the scope of the invention. For example, the number of phases and the number of pole pairs of the motor 3, the reduction ratio of the reduction mechanism 15, and the like are merely examples, and it goes without saying that the system of the present invention is not limited to the above numerical values. Further, in the above-described embodiment, an example has been described in which the magnet 22 is configured by two segment magnets. However, the magnet 22 may be configured by a ring magnet.
[0032]
【The invention's effect】
According to the throttle valve opening detection system of the present invention, in an electronically controlled throttle device including a throttle valve that is opened and closed by a brushless motor, an output signal of a magnetic detection element that detects rotation of a shaft to which the throttle valve is fixed. Opening calculation means for calculating the opening of the throttle valve based on the throttle valve, opening estimation means for estimating the opening of the throttle valve based on the rotor position detection signal of the brushless motor, and detection of the throttle valve by the opening calculation means Failure detection means for detecting a failure of the magnetic detection element by comparing the opening with the estimated opening of the throttle valve by the opening estimation means is provided, so that the opening of the throttle valve can be determined from the rotor position detection signal of the brushless motor. By estimating and comparing the estimated value with the detected opening of the throttle valve calculated based on the output signal of the magnetic detection element, While performing failure diagnosis of the air-detection element can be controlling the opening degree of the throttle valve. Therefore, abnormality determination can be performed without using two expensive temperature-compensation type linear output Hall ICs, and it is possible to reduce the cost of the apparatus by reducing one Hall IC while ensuring reliability. It becomes.
[Brief description of the drawings]
FIG. 1 is a sectional view showing a configuration of an electronically controlled throttle valve to which an opening detection system according to the present invention is applied.
FIG. 2 is a sectional view taken along line AA of FIG.
FIG. 3 is an explanatory diagram illustrating a configuration of a sensor unit.
FIG. 4 is a block diagram showing a configuration of a control system in the electronically controlled throttle valve of FIG. 1;
FIG. 5 is an explanatory diagram showing a configuration of a rotation pulse signal.
FIG. 6 is an explanatory diagram showing the relationship between the increase and decrease of the rotation pulse signal and the throttle opening.
FIG. 7 is an explanatory diagram showing a relationship between a magnetic flux density in a slit of a stator core and a rotation angle of a hub.
FIG. 8 is an explanatory diagram showing a configuration of a conventional rotation angle detection device.
[Explanation of symbols]
Reference Signs List 1 throttle valve 2 shaft 3 brushless motor 4 housing 5 cover 6 sensor unit 11 to 14 gear 15 reduction mechanism 16a, 16b bearing 17 torsion coil spring 18 idler gear 19 gear shaft 20 hub 21 rotor core 22 magnet 23 substrate 24 Hall IC
25 Stator core 26 Slit 27 Polarity switching section 31 Stator 32 Rotor 33 Drive coil 34 Stator core 35 Rotor shaft 36 Rotor core 36a Magnet mounting section 37 Rotor magnets 38a, 38b Bearing 39 Bracket 41 Controller (CPU)
42 Up / Down Counter 42 Rotation Direction Detector 43 Up / Down Counter 44 Throttle Opening Estimation Unit (Opening Estimation Means)
45 A / D converter / angle calculator (opening calculator)
46 Angle sensor failure detection unit (failure detection means)
Reference Signs List 51 hub 52 rotor core 53 magnet 54 stator core 55 slits 56a, 56b Hall IC

Claims (3)

An opening detection system for the throttle valve in an electronically controlled throttle device including a throttle valve driven to be opened and closed by a brushless motor,
A shaft on which the throttle valve is fixed and which is rotationally driven by the brushless motor;
A hub attached to the shaft and comprising a magnet that rotates with the shaft;
A stator core comprising a magnetic sensing element and arranged coaxially with the hub,
Opening calculation means for calculating an opening of the throttle valve based on an output signal of the magnetic detection element that changes with rotation of the magnet;
Opening degree estimating means for estimating the opening degree of the throttle valve based on a rotor position detection signal of the brushless motor;
Failure detecting means for comparing the detected opening of the throttle valve by the opening calculating means with the estimated opening of the throttle valve by the opening estimating means to detect a failure of the magnetic detecting element; Throttle valve opening detection system. 2. The throttle valve opening detecting system according to claim 1, wherein the opening estimating unit is configured to generate the shaft based on a rotation pulse signal generated from the rotor position detection signal and formed every time the brushless motor rotates a predetermined angle. A rotation angle of the throttle valve is calculated, and an opening of the throttle valve is estimated. 3. The throttle valve opening detection system according to claim 1, wherein the hub includes a rotor core formed of a magnetic material in a cylindrical shape, and the magnet is fixed to an inner peripheral surface of the hub, and the stator core is formed of a magnetic material. 4. A throttle valve opening detection system, wherein the system is formed and arranged inside the magnet and one magnetic detection element is attached.

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