JP2013096898A - Rotation angle detection apparatus for throttle valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rotation angle detection apparatus for a throttle valve in which reliability can be suppressed from being reduced with the passage of time and error between an actual rotation angle in detection start and a calculated rotation angle can be reduced.SOLUTION: A rotation angle detection apparatus comprises an angle calculation section 60 and an output section 70. The angle calculation section 60 calculates a rotation angle of a magnetism generation section 20 using a first signal and a second signal and performs feedback control in such a manner that a deviation between an actual rotation angle θ of the magnetism generation section 20 and a rotation angle φ obtained by the arithmetic operation can be settled to a predetermined value. The output section 70 outputs a signal corresponding to the rotation angle φ calculated by the angle calculation section 60. The angle calculation section 60 then uses an angle in a fully closed state of a throttle valve 10 as the calculated rotation angle φ in detection start.

Description

  The present invention includes a magnetoelectric conversion element in a magnetic field of a magnetic generation unit that rotates integrally with a throttle valve, and calculates a rotation angle of the magnetic generation unit using a signal output from the magnetoelectric conversion element. The present invention relates to a rotation angle detection device for a throttle valve that detects a rotation angle of a valve.

  Conventionally, for example, Patent Document 1 proposes a throttle valve rotation angle detection device that detects the rotation angle (opening degree) of a throttle valve that controls the amount of intake air taken into the combustion chamber of the engine. In this throttle valve rotation angle detection device, the rotation angle of the throttle valve is detected by detecting the resistance value of the throttle position sensor that changes as the throttle valve rotates.

  For example, Patent Document 2 proposes a rotation angle detection device that calculates a digital angle from a signal output from a rotation detector according to the rotation of a rotating body and performs feedback control using the digital angle.

JP 2002-70587 A JP 2000-353957 A

  However, the throttle valve rotation angle detection device disclosed in Patent Document 1 detects a change in the resistance value of the throttle position sensor, that is, a change in the resistance value of a so-called sliding resistance. There is a problem that the performance is lowered.

  Moreover, in the rotation angle detection apparatus described in Patent Document 2, feedback control using a digital angle is performed to calculate the rotation angle of the rotation detector. For this reason, it is conceivable that such a rotation detection device is applied to a throttle valve rotation angle detection device to suppress a decrease in reliability over time. However, when the rotation angle detection device described in Patent Document 2 is simply applied to detection of the rotation angle of the throttle valve, the calculated rotation angle (feedback angle) at the start of detection is not determined. There is a problem that the error between the actual rotation angle at the start of detection and the calculated rotation angle is large.

  In view of the above points, the present invention can suppress a decrease in reliability over time and can reduce an error between the actual rotation angle at the start of detection and the calculated rotation angle. It aims at providing the rotation angle detection apparatus for valves.

  In order to achieve the above-mentioned problems, the present inventors have intensively studied. The inventors of the present invention pay attention to the fact that the throttle valve is always in a fully closed state at the start of detection. In a rotation detection device that performs feedback control, when the throttle valve is in a fully closed state as a calculation angle at the start of detection. It has been found that the above-mentioned problems can be solved by using the angle.

  For this reason, in the first aspect of the present invention, it is arranged in the magnetic field generated by the magnetic generator (20) that rotates integrally with the throttle valve (10) that controls the flow rate of the medium flowing in the suction passage (12). The second magneto-resistive element (M1) that outputs a first signal according to the rotation of the magnetism generator (20) and the second signal that outputs a second signal having a predetermined phase difference between the first signal and the second signal. A throttle valve for determining the rotation angle of the magnetic generator (20) using the first and second signals output from the first and second magnetoelectric conversion elements (M1, M2). The rotation angle detecting device for use is characterized by the following points.

  That is, the rotation angle of the magnetic generator (20) is calculated using the first signal and the second signal, and the deviation between the actual rotation angle θ of the magnetic generator (20) and the rotation angle φ obtained by the calculation is predetermined. An angle calculation unit (60) that performs feedback control so as to converge to a value, and an output unit (70) that outputs a signal corresponding to the rotation angle φ calculated by the angle calculation unit (60). (60) is characterized in that an angle when the throttle valve (10) is in a fully closed state is used as the calculated rotation angle φ at the start of detection.

  In such a throttle valve rotation angle detection device, the feedback control is performed to calculate the rotation angle of the magnetism generating portion (20), that is, the rotation angle of the throttle valve (10), so that the reliability decreases with time. Can be suppressed.

  In addition, the angle calculation unit (60) uses the angle when the throttle valve (10) is in the fully closed state as the calculated rotation angle φ at the start of detection. Thereby, at the start of detection, an error between the actual rotation angle θ of the throttle valve (10) and the calculated rotation angle φ can be reduced. This is because the throttle valve (10) is always in a fully closed state at the start of detection, that is, immediately before the throttle valve (10) is operated.

  For example, as in the second aspect of the invention, the first magnetoelectric conversion element (M1) outputs a sin Nθ signal (N is a natural number) according to the rotation of the magnetism generator (20), and the second magnetoelectric conversion element (M2) may be arranged in a magnetic field generated by the magnetic generator (20) in a state where a cosNθ signal (N is a natural number) is output in accordance with the rotation of the magnetic generator (20). Then, the angle calculation unit (60) performs a predetermined calculation on the sinNθ signal and the cosNθ signal output from the first and second magnetoelectric transducers (M1, M2), and sin (Nθ + α) having the same phase difference α. ) And sin (Nθ−α), and then performing a predetermined operation using sin (Nθ + α), sin (Nθ−α) and the rotation angle φ to generate an Asin (Nθ−Nφ) signal, Feedback control can be performed so that the deviation (Nθ−Nφ) based on Asin (Nθ−Nφ) becomes a predetermined value.

  In this case, it is preferable that the angle calculator (60) performs feedback control so that the deviation (Nθ−Nφ) becomes zero, as in the third aspect of the invention.

  As in the invention described in claim 4, the angle calculation unit (60) includes a counter (64) that counts a count value corresponding to the calculated rotation angle φ, and determines whether the deviation (Nθ−Nφ) is positive or negative. It can be determined, and the count value of the counter (64) can be increased or decreased based on the determination result.

  According to this, since the calculated rotation angle φ can be made to correspond to the count value of the counter (64), the calculated rotation angle φ can be calculated with high accuracy.

  Further, as in the fifth aspect of the invention, the angle calculation unit (60) calculates a deviation (Nθ−Nφ) by performing an inverse sine operation on the sin (Nθ−Nφ) signal, and based on the calculation result. Thus, it can be determined whether it is positive or negative.

  Further, as in the invention described in claim 6, when the sin (Nθ−Nφ) signal is greater than 0, the angle calculation unit (60) determines that the deviation (Nθ−Nφ) is positive, and sin When the (Nθ−Nφ) signal is smaller than 0, it can be determined that the deviation (Nθ−Nφ) is negative.

  As in the invention described in claim 7, the angle calculator (60) can use 0 as the calculated rotation angle φ at the start of detection. In addition, as in the invention described in claim 8, the angle calculator (60) is configured to fully close the throttle valve (10) in the intake passage (12) as the calculated rotation angle φ at the start of detection. The angle measured when the state is in use can be used.

  Further, as in the ninth aspect of the invention, the temperatures of the first and second magnetoelectric transducers (M1, M2) are input and output from the first and second magnetoelectric transducers (M1, M2). 1. A temperature characteristic correction unit that corrects the first and second signals according to the temperature of the first and second magnetoelectric transducers (M1, M2) and inputs the corrected signal to the angle calculation unit (60) is provided. Can do.

  According to this, since the temperature characteristic correction is performed according to the temperatures of the first and second magnetoelectric transducers (M1, M2), it is possible to suppress the detection sensitivity from depending on the temperature.

  And like invention of Claim 10, a 1st, 2nd magnetoelectric conversion element (M1, M2) shall be respectively comprised by the magnetoresistive element (R1-R8).

  In addition, the code | symbol in the bracket | parenthesis of each means described in this column and the claim shows the correspondence with the specific means as described in embodiment mentioned later.

1 is a block diagram of a throttle valve rotation angle detection device according to a first embodiment of the present invention. FIG. It is a schematic diagram which shows the arrangement | positioning relationship between a sensor chip and a throttle valve, (a) is a figure which shows the state in which a throttle valve is closed, (b) is a figure which shows the state in which a throttle valve is open. It is a figure which shows typically the structure of the sensor chip | tip shown in FIG. 1, (a) is a top view, (b) is AA arrow sectional drawing of (a). FIG. 4 is a plan view schematically showing the structure of the first AMR sensor shown in FIG. 3. It is a top view which shows typically the structure of the 2nd AMR sensor shown in FIG. FIG. 5 is an equivalent circuit diagram of the first AMR sensor shown in FIG. 4. FIG. 6 is an equivalent circuit diagram of the second AMR sensor shown in FIG. 5. It is a figure which shows each output signal of a 1st, 2nd AMR sensor. It is a figure for demonstrating the action | operation of a detection circuit. It is a figure which shows the relationship between an input angle and an output angle. It is a figure which shows the relationship between actual rotation angle (theta) and the calculated rotation angle (phi). It is a figure which shows the arrangement | positioning relationship between the sensor chip and throttle valve in other embodiment of this invention.

(First embodiment)
A first embodiment of the present invention will be described with reference to the drawings. The throttle valve rotation angle detection device of this embodiment is used to detect the rotation angle (opening degree) of a throttle valve that controls the amount of intake air taken into the combustion chamber of the engine. FIG. 1 is a block diagram of a throttle valve rotation angle detection device according to this embodiment.

  As shown in FIG. 1, the rotation angle detection device for a throttle valve includes a sensor chip 1 and a detection circuit 2. The sensor chip 1 includes two anisotropic magnetoresistive sensors (hereinafter simply referred to as first and second AMR sensors) M1 and M2 formed of magnetoresistive elements, and a throttle valve provided in a suction passage. Arranged on the rotation axis. In the present embodiment, the first and second AMR sensors M1 and M2 correspond to the first and second magnetoelectric transducers of the present invention. Hereinafter, the arrangement relationship between the sensor chip 1 and the throttle valve will be briefly described.

  2A and 2B are schematic diagrams showing the positional relationship between the sensor chip 1 and the throttle valve. FIG. 2A is a diagram showing a state where the throttle valve is closed, and FIG. 2B is a diagram showing a state where the throttle valve is open. It is.

  As shown in FIG. 2, the throttle valve 10 that controls the amount of intake air taken into the combustion chamber of the engine is integrated with a shaft 11 that rotates together with the throttle valve 10, and the shaft 11 passes through the intake passage 12. It is provided in the suction passage 12 by being supported by the throttle body 13 to be formed. In the present embodiment, the suction passage 12 has a circular cross section with respect to the direction of intake air flow, and the throttle valve 10 has a circular shape having substantially the same diameter as the suction passage 12 so that the intake air can be shut off when fully closed. It is plate-shaped. Further, the shaft 11 is provided in the throttle body 13 so that one end thereof protrudes outside the suction passage 12, and a permanent magnet 20 corresponding to the magnetic field generator of the present invention is provided at the protruding tip. In the present embodiment, the intake air corresponds to the medium of the present invention.

  In the present embodiment, the permanent magnet 20 has a disk shape and is divided into two in the radial direction. One divided into two is an N-pole permanent magnet 20a, and the other is an S-pole permanent magnet 20b. As shown in FIG. 2B, the shaft 11 is used together with the throttle valve 10. Integrate and rotate.

  The sensor chip 1 is supported by a support member (not shown) in a magnetic field generated by the permanent magnet 20 so as to face the rotating surface 20c along the diameter of the permanent magnet 20, and is fixed so that the arrangement position does not change. It has been. As is well known, since a magnetic field is generated from the N-pole permanent magnet 20a toward the S-pole permanent magnet 20b, the throttle valve 10 is in the state shown in FIG. In this case, the magnetic field B in the left-right direction on the paper surface is applied. In the state shown in FIG. 2B, the magnetic field B in the vertical direction on the paper surface is applied. Further, θ in FIG. 2 (b) is a rotation angle of the throttle valve 10, and an angle rotated from the reference when the throttle valve 10 is in a fully closed state (FIG. 2 (a)). It is.

  Next, a specific structure of the sensor chip 1 will be described. 3A and 3B are diagrams schematically showing the structure of the sensor chip 1. FIG. 3A is a plan view, and FIG. 3B is a cross-sectional view taken along the line AA in FIG.

  As shown in FIG. 3, the sensor chip 1 includes a silicon substrate 40, an insulating film 41 such as a silicon oxide film formed on the surface of the silicon substrate 40, and a plurality of layers formed on the surface of the insulating film 41. First and second AMR sensors M1 and M2 having magnetoresistive elements R1 to R8 are provided. The shapes of the magnetoresistive elements R1 to R8 are drawn larger than the actual dimensions in order to make the formation direction of the elements easy to understand.

  FIG. 4 is a plan view schematically showing the structure of the first AMR sensor M1, and FIG. 5 is a plan view schematically showing the structure of the second AMR sensor M2. FIG. 6 is an equivalent circuit diagram of the first AMR sensor M1, and FIG. 7 is an equivalent circuit diagram of the second AMR sensor M2. FIG. 8 is a diagram showing output signals of the first and second AMR sensors M1 and M2.

  As shown in FIGS. 4 and 5, the magnetoresistive elements R <b> 1 to R <b> 8 are formed in a shape in which a plurality of band-like regions are folded back, that is, in a meander shape (meandering shape). The resistance value changes depending on the intensity and direction of the parallel magnetic field, and a signal having a level corresponding to the resistance value is output. That is, the magnetoresistive elements R1 to R8 are elements that generate an anisotropic magnetoresistive effect. Although not particularly limited, in the present embodiment, the magnetoresistive elements R1 to R8 are formed of a ferromagnetic metal thin film. NiFe (permalloy), NiCo, or the like is used as the ferromagnetic material. The ferromagnetic metal thin film is formed by sputtering or vapor deposition.

  As shown in FIG. 4, the first AMR sensor M1 includes four magnetoresistive elements R1 to R4. The magnetoresistive elements R <b> 1 to R <b> 4 are arranged so that the angle formed by the extending direction of the strip-shaped elements in the adjacent magnetoresistive elements is 90 °. In other words, the magnetoresistive elements R <b> 1 to R <b> 4 are arranged such that the current direction (easy magnetization axis) of the adjacent magnetoresistive elements forms an angle of 90 °. That is, each set of the magnetoresistive elements R1, R3 and R2, R4 is arranged such that the phase between the output signals is 90 ° different in each set.

  As shown in FIGS. 4 and 6, the magnetoresistive elements R1 and R3 are electrically connected in series to form a half bridge circuit. An output terminal 31 for taking out the midpoint output Vout1 is electrically connected to the midpoint of the half bridge circuit. The magnetoresistive elements R2 and R4 are also electrically connected in series to form a half bridge circuit. An output terminal 32 for taking out the midpoint output Vout2 is electrically connected to the midpoint of the half bridge circuit.

  Both half-bridge circuits are connected in parallel to form a full-bridge circuit that outputs a sin 2θ signal. The full bridge circuit is electrically connected to a power supply terminal 30 for supplying power Vcc and a terminal 33 for electrically connecting to the ground G1. In the full bridge circuit, the magnetoresistive elements R1 and R2 facing each other output (R0 + ΔRsin2θ) signals, and the magnetoresistive elements R3 and R4 output (R0−ΔRsin2θ) signals. R0 is the resistance value of the magnetoresistive element in the absence of a magnetic field, and ΔR is the amount of change in resistance value. In the present embodiment, the sin 2θ signal corresponds to the first signal of the present invention.

  Since each of the midpoint outputs Vout1 and Vout2 vibrates around Vcc / 2, it is possible to suppress an offset of the output waveform caused by a change in environmental temperature or the like. Further, the output terminals 31 and 32 are connected to an amplification unit described later, and the midpoint outputs Vout1 and Vout2 are differentially amplified. Thus, by configuring the first AMR sensor M1, the output amplitude of the first AMR sensor M1 can be doubled compared to the case where the first AMR sensor M1 is configured by one half bridge circuit, and the magnetic The detection sensitivity can be increased.

  As shown in FIG. 5, the second AMR sensor M2 includes four magnetoresistive elements R5 to R8. The magnetoresistive elements R5 to R8 are arranged so that the angle formed by the extending direction of the strip-shaped elements in the adjacent magnetoresistive elements is 90 °. In other words, the magnetoresistive elements R5 to R8 are arranged so that the current direction (magnetization axis) of the adjacent magnetoresistive elements forms an angle of 90 °. That is, each set of magnetoresistive elements R5, R8 and R6, R7 is arranged such that the phase between the output signals is 90 ° different in each set.

  As shown in FIGS. 5 and 7, the magnetoresistive elements R5 and R7 are electrically connected in series to constitute a half bridge circuit. An output terminal 35 for taking out the midpoint output Vout3 is electrically connected to the midpoint of the half bridge circuit. The magnetoresistive elements R2 and R4 are also electrically connected in series to form a half bridge circuit. An output terminal 36 for taking out the midpoint output Vout4 is electrically connected to the midpoint of the half bridge circuit.

  Both half bridge circuits are connected in parallel to form a full bridge circuit that outputs a cos 2θ signal. The full bridge circuit is electrically connected to a power supply terminal 34 for supplying power Vcc and a terminal 37 for electrical connection with the ground G2. In the full bridge circuit, the magnetoresistive elements R5 and R6 facing each other output the (R0−ΔRcos2θ) signal, and the magnetoresistive elements R7 and R8 output the (R0 + ΔRcos2θ) signal. In the present embodiment, the cos 2θ signal corresponds to the second signal of the present invention.

  Since each of the midpoint outputs Vout3 and Vout4 vibrates around Vcc / 2, it is possible to suppress an offset of the output waveform caused by a change in environmental temperature or the like. Further, the output terminals 35 and 36 are connected to an amplifying unit described later, and the midpoint outputs Vout3 and Vout4 are differentially amplified. In this way, by configuring the second AMR sensor M2, the output amplitude of the second AMR sensor M2 can be doubled compared to the case where the second AMR sensor M2 is configured by one half bridge circuit, and the magnetic The detection sensitivity can be increased.

  As shown in FIG. 3A, the magnetoresistive elements R1 to R8 of the first and second AMR sensors M1 and M2 are alternately arranged concentrically. Specifically, the magnetoresistive elements R1 to R4 of the adjacent first AMR sensor M1 and the magnetoresistive elements R5 to R8 of the second AMR sensor M2 are such that the direction of current (magnetization easy axis) forms an angle of 45 °. Is arranged. The amount of change ΔR in the electrical resistance of the anisotropic magnetoresistive element is maximum when the angle between the direction of the current flowing through the metal thin film (magnetization easy axis) and the direction of the magnetic field is 90 ° and 270 °. And is minimized at 0 ° and 180 °.

  From the above, as shown in FIG. 8, the first AMR sensor M1 outputs a sin signal with one wavelength being an electrical angle of 180 °, and the second AMR sensor M2 has a phase difference of 45 ° with respect to the first AMR sensor M1, One wavelength outputs a cos signal having an electrical angle of 180 °. The above is the structure of the sensor chip 1 in the present embodiment.

  Next, the configuration of the detection circuit 2 will be described. As illustrated in FIG. 1, the detection circuit 2 includes an amplification unit 50, an angle calculation unit 60, and an output unit 70.

  The amplifying unit 50 includes first and second differential amplifier circuits 50a and 50b. Then, the first differential amplifier circuit 50a differentially amplifies the output signal sin2θ of the first AMR sensor M1, and the second differential amplifier circuit 50b differentially amplifies the output signal cos2θ of the second AMR sensor M2.

  The angle calculation unit 60 is a tracking loop type digital angle conversion circuit, and includes a signal creation unit 61, a deviation calculation unit 62, a positive / negative determination unit 63, an up / down counter (U / D counter) 64, and an initial angle storage unit. 65. Then, using the signals output from the first and second AMR sensors M1 and M2, the deviation between the rotation angle θ with respect to the permanent magnet 20 (throttle valve 10) and the rotation angle φ obtained by calculation converges to a predetermined value. The rotation angle θ is calculated by performing feedback control. In the present embodiment, this predetermined value is 0.

  The signal generator 61 generates Asin (2θ + α) from the amplified signal of the sin signal output from the first AMR sensor M1, using the signals output from the first and second differential amplifier circuits 50a and 50b. Asin (2θ−α) is generated from the amplified signal of the cos signal output from the 2AMR sensor M2. Then, a predetermined calculation using these Asin (2θ + α) and Asin (2θ−α) is performed to generate a signal 2Asin (2θ-2φ). Note that A is the amplitude and α is the phase difference. In this embodiment, the amplitude A = 1 and the phase difference α = 45 °.

  The deviation calculating unit 62 calculates the deviation (2θ-2φ) using the signal 2Asin (2θ-2φ) output from the signal creating unit 61.

  The positive / negative determining unit 63 determines whether the deviation (2θ−2φ) calculated by the deviation calculating unit 62 is a positive value or a negative value.

  The up / down counter 64 adds (counts up) or subtracts (counts down) the count value according to the determination result of the positive / negative determination unit 63.

  The initial angle storage unit 65 is configured by an EEPROM or the like, and stores an angle when the throttle valve 10 is in a fully closed state as an initial angle. For example, the initial angle is almost zero when the throttle valve 10 is assembled, and can be zero. Further, the initial angle may be an angle measured in the fully closed state when the throttle valve 10 is assembled in consideration of an angle shift when the throttle valve 10 is assembled.

  The output unit 70 outputs a signal obtained by converting the calculated rotation angle φ output from the up / down counter 64 into an analog value.

  Next, the operation of the detection circuit 2 will be described. FIG. 9 is a diagram for explaining the operation of the detection circuit 2. In FIG. 9, each block denoted by reference numerals 61 a to 61 k indicates the content of processing executed by the signal creation unit 61, or a signal or data generated by the processing.

  As shown in FIG. 9, when the permanent magnet 20 (throttle valve 10) rotates θ from the fully closed state, a signal sin2θ is output from the first AMR sensor M1, and a signal cos2θ is output from the second AMR sensor M2. Then, the signal generator 61 generates Asin (2θ + α) (61a) and Asin (2θ−α) (61b) from the signals output from the first and second differential amplifier circuits 50a and 50b, and Asin (2θ + α). ) And Asin (2θ−α) are added to generate a signal 2Asin2θcosα (61c), and Asin (2θ−α) is subtracted from Asin (2θ + α) to generate a signal 2Acos2θsinα (61d). The addition can be performed using a known addition circuit, and the subtraction can be performed using a Kochi subtraction circuit.

  Further, the phase difference α can be arbitrarily changed as described above, but it is preferable that the phase difference α is set as follows. FIG. 10 is a diagram showing the relationship between the input angle (rotation angle of the throttle valve 10) and the output angle. As shown in FIG. 10, the calculated rotation angle φ obtained by performing the calculation described later is a signal that changes linearly with respect to the input angle (the rotation angle of the permanent magnet 20) when α is 45 °. When the angle is away from 45 °, an error between the input angle and the calculated rotation angle increases. For this reason, in this embodiment, the phase difference α is set to 45 °.

  Subsequently, as illustrated in FIG. 9, the signal creation unit 61 multiplies the signal 2Asin2θcosα by the signals cos2φ and (1 / cosα) to create the signal 2Asin2θcos2φ (61e, 61i, 61g). The signal creation unit 61 multiplies the signal 2Acos2θsinα by the signals sin2φ and (1 / sinα) to create the signal 2Acos2θsin2φ (61f, 61h, 61j). Each of these multiplications can be performed using a known multiplication circuit.

  Note that (1 / cos α) and (1 / sin α) are coefficients that do not change according to the rotation of the permanent magnet 20 (throttle valve 10). Further, each of cos2φ (61i) and sin2φ (61j) is a variable that varies depending on the count value of the up / down counter 64. However, in the first calculation (at the start of detection) when the detection of the throttle valve 10 is started, φ is a value read from the initial angle storage unit 65 (65). The throttle valve 10 adjusts the intake air amount as described above, and is always in the fully closed state at the start of detection, that is, immediately before the throttle valve 10 is rotated.

  Subsequently, the signal generator 61 subtracts the signal 2Acos2θsin2φ from the signal 2Asin2θcos2φ to generate a sin signal having the signal 2Asin (2θ-2φ), that is, the deviation (2θ-2φ) as a variable (61k). This subtraction can be performed using a known subtraction circuit.

  Next, the deviation calculation unit 62 performs an arc sine operation (arcsine operation) on the signal 2Asin (2θ-2φ) created by the signal creation unit 61 to obtain a deviation (2θ-2φ) (62).

  Subsequently, the positive / negative determining unit 63 determines whether the deviation (2θ−2φ) obtained by the deviation calculating unit 62 is a positive value or a negative value (63).

  Thereafter, if the determination result of the positive / negative determination unit 63 is positive, the up / down counter 64 adds 1 to the least significant bit (LSB) of the counter and adds the count value, and the determination result of the positive / negative determination unit 63 Is negative, 1 is subtracted from the least significant bit of the counter (64). The count value of the up / down counter 64 becomes the digital angle, that is, the calculated rotation angle φ (65).

  Further, the signal creating unit 61 creates signals cos2φ and sin2φ using the calculated rotation angle φ (count value) output from the up / down counter 64 (61i, 61j). These signals are generated by using, for example, a table in which the calculated rotation angle φ (count value) is associated with the data cos2φ and sin2φ, and the data cos2φ and sin2φ associated with the calculated rotation angle φ are read out. The read data can be converted into an analog signal. As described above, in the first calculation (at the start of detection) when the detection of the throttle valve 10 is started, φ is the initial angle (65).

  Then, the signal creating unit 61 again multiplies the signal 2Asin2θcosα by the signals cos2φ and (1 / cosα) to create the signal 2Asin2θcos2φ. Further, the signal 2Acos2θsinα is again multiplied by the signals sin2φ and (1 / sinα) to generate the signal 2Acos2θsin2φ. That is, the deviation (2θ-2φ) is fed back to the signals cos2φ and sin2φ, and the deviation (2θ-2φ) is controlled to be zero.

  The output unit 70 outputs a signal obtained by converting the calculated rotation angle φ output from the up / down counter 64 into an analog value. For example, the output unit 70 converts the calculated rotation angle φ output from the up / down counter 64 into an analog voltage and outputs the analog voltage. FIG. 11 is a diagram illustrating the relationship between the actual rotation angle θ and the calculated rotation angle φ output from the output unit 70.

  As shown in FIG. 11, in such a rotation angle detecting device, the initial angle stored in the initial angle storage unit 65 is read and calculated in the first calculation (at the start of detection) of the rotation angle of the throttle valve 10. Therefore, the error at the start of detection of the actual rotation angle θ and the calculated rotation angle φ can be reduced.

  In the detection circuit 2 as described above, the rotation angle θ can be calculated in the range of 0 to 360 °. In general, the rotation angle θ of the permanent magnet 20 (throttle valve 10) is 0 to 90 °. Therefore, the output range of the output unit 70 may be in a range of 0 to 90 °. Further, the output range of the output unit 70 may be set to a range of 0 to 120 ° in consideration of attachment errors and the like.

  As described above, the rotation angle detection device according to the present embodiment calculates the rotation angle φ calculated by the angle calculation unit 60 and performs feedback control using the calculated rotation angle φ. For this reason, it can suppress that reliability falls over time.

  Further, the angle calculation unit 60 uses an angle when the throttle valve 10 is in a fully closed state as the calculated rotation angle φ at the start of detection. As a result, at the start of detection, the error between the actual rotation angle θ of the permanent magnet 20 (throttle valve 10) and the calculated rotation angle φ can be reduced (see FIG. 11). This is because the throttle valve 10 is always fully closed at the start of detection.

(Other embodiments)
In the first embodiment, the first and second AMR sensors M1 and M2 are formed on the sensor chip 1. However, the following sensors may be formed on the sensor chip 1. That is, a phase difference between a GMR (Giant Magneto-Resistive Effect) sensor that outputs a sin signal having an electrical angle of 360 ° and a GMR sensor is 90 °, and one wavelength is an electrical angle 360. A GMR sensor that outputs a cos signal of ° may be formed. The phase difference between a TMR (Tunnel Magneto-Resistive Effect) sensor that outputs a sin signal having an electrical angle of 360 ° and a TMR sensor is 90 °, and one wavelength is an electrical angle 360. A TMR sensor that outputs a cosine signal of ° may be formed. Similarly, a Hall element that outputs a sin signal having an electrical angle of 360 ° for one wavelength and a Hall element that outputs a cos signal having an electrical angle of 360 ° with a phase difference of 90 ° are formed. May be.

  As described above, when a sensor chip 1 having a GMR sensor, TMR sensor, or Hall element is used, the signal generator 61 performs the same processing as described above, and the deviation is (θ−φ ) Is generated (61k). For this reason, after the positive / negative determining unit 63 determines whether the deviation (θ−φ) is a positive value or a negative value, the count value of the up / down counter 64 is added or subtracted in the same manner as described above. .

  In the first embodiment, the example in which the positive / negative determination unit 63 determines whether the deviation (2θ−2φ) is greater than 0 has been described. That is, the angle calculation unit 60 does not include the deviation calculation unit 62, and the positive / negative determination unit 63 determines that the signal 2Asin (2θ-2φ) is positive when it is greater than 0, and negative when it is less than 0. You may make it determine with it.

  Furthermore, in the first embodiment, the amplification unit 50 may not be provided, and the signals of the first and second AMR sensors M1 and M2 may be input to the angle calculation unit 60 as they are. Although not particularly shown, noise may be removed by a filter or the like.

  In the first embodiment, the temperature characteristic correction may be performed. That is, a temperature detection unit is formed in the sensor chip 1, and the temperature and the correction value for the sensitivity change of the first and second AMR sensors M1 and M2 are associated between the amplification unit 50 and the angle calculation unit 60. You may provide the temperature characteristic correction | amendment part which has data. As a result, the temperature characteristic correction unit can read out the correction value from the temperature detected by the temperature detection unit and perform temperature characteristic correction using the temperature-dependent correction value for the amplified signal. Can be suppressed from depending on temperature.

  Furthermore, in the first embodiment, the first and second AMR sensors M1 and M2 may be configured to have the highest sensitivity at room temperature (25 ° C.).

  In the first embodiment, the sensor chip 1 is disposed in a magnetic field generated by the disk-shaped permanent magnet 20. However, the sensor chip 1 has a magnetic field generated by the permanent magnet 20 as follows. It may be arranged inside. FIG. 12 is a diagram showing an arrangement relationship between the sensor chip 1 and the throttle valve 10.

  As shown in FIG. 12A, the permanent magnet 20 is divided into two parts having the same size in the thickness direction, divided into two parts having the same size in the radial direction, and divided into four parts. Among them, one of the throttle body 13 side is an N-pole permanent magnet 20a and the other is an S-pole permanent magnet 20b, and the portion laminated in the thickness direction of the permanent magnet 20a is an S-pole permanent magnet. A portion laminated in the thickness direction of the permanent magnet 20b may be an N-pole permanent magnet 20e.

  Further, as shown in FIG. 12B, the permanent magnet 20 has a U-shaped cross section having a rectangular plate-like member and projecting portions projecting in the direction perpendicular to the surface direction of the plate-like member at both ends of the member. It may be said.

  Furthermore, as shown in FIG. 12 (c), a rectangular plate member which is a permanent magnet 20 and yoke portions 21 made of iron or the like protruding in the direction perpendicular to the surface direction of the plate member are provided at both ends of the member. The cross section may be U-shaped.

  By configuring the magnetism generating portion as shown in FIGS. 12B and 12C, the magnetic field B is generated in the direction from one of the portions protruding from the plate member to the other. Since the magnetic field B is applied in a direction parallel to the planar direction of the substrate 40, it is possible to suppress partial variations in the direction of the applied magnetic field.

DESCRIPTION OF SYMBOLS 1 Sensor chip 2 Detection circuit 10 Throttle valve 12 Suction passage 20 Permanent magnet 60 Angle calculation part 61 Signal preparation part 62 Deviation calculation part 63 Positive / negative judgment part 64 Up / down counter 70 Output part

Claims (10)

Arranged in a magnetic field generated by a magnetic generator (20) that rotates integrally with a throttle valve (10) that controls the flow rate of the medium flowing in the suction passage (12), and rotates the magnetic generator (20). A first magnetoelectric conversion element (M1) that outputs a first signal in response, and a second magnetoelectric conversion element (M2) that outputs a second signal having a predetermined phase difference between the first signal and the first signal. ,
In the throttle valve rotation angle detection device for determining the rotation angle of the magnetism generator (20) using the first and second signals output from the first and second magnetoelectric transducers (M1, M2),
Using the first signal and the second signal, the rotation angle of the magnetic generator (20) is calculated, and the deviation between the actual rotation angle θ of the magnetic generator (20) and the rotation angle φ obtained by the calculation is calculated. An angle calculation unit (60) that performs feedback control so that is converged to a predetermined value;
An output unit (70) for outputting a signal corresponding to the rotation angle φ calculated by the angle calculation unit (60),
The said angle calculating part (60) uses the angle when the said throttle valve (10) is a fully-closed state as the calculated rotation angle (phi) at the time of a detection start, The rotation angle detection apparatus for throttle valves characterized by the above-mentioned. The first magnetoelectric transducer (M1) outputs a sin Nθ signal (N is a natural number) according to the rotation of the magnetic generator (20), and the second magnetoelectric transducer (M2) is connected to the magnetic generator (20). ) In a state where a cosNθ signal (N is a natural number) is output in accordance with the rotation of the magnetic generator (20),
The angle calculation unit (60) performs a predetermined calculation on the sinNθ signal and the cosNθ signal output from the first and second magnetoelectric transducers (M1, M2) and has the same phase difference α. After generating (Nθ + α) and sin (Nθ-α), the Asin (Nθ-Nφ) signal is obtained by performing a predetermined calculation using the sin (Nθ + α), the sin (Nθ-α) and the rotation angle φ. 2. The throttle valve rotation angle detection device according to claim 1, wherein feedback control is performed so that a deviation (Nθ−Nφ) based on Asin (Nθ−Nφ) becomes the predetermined value.   The rotation angle detection device for a throttle valve according to claim 1 or 2, wherein the angle calculation unit (60) performs feedback control so that the deviation (Nθ-Nφ) becomes zero.   The angle calculation unit (60) includes a counter (64) that counts a count value corresponding to the rotation angle φ, and determines whether the deviation (Nθ−Nφ) is positive or negative, and based on the determination result, the counter ( 64. The throttle valve rotation angle detection device according to any one of claims 1 to 3, wherein the count value of 64) is increased or decreased.   The angle calculation unit (60) calculates the deviation (Nθ-Nφ) by performing an inverse sine operation on the sin (Nθ-Nφ) signal, and determines the positive or negative based on the calculation result. The rotation angle detection device for a throttle valve according to claim 4.   The angle calculation unit (60) determines that the deviation (Nθ-Nφ) is positive when the sin (Nθ-Nφ) signal is greater than 0, and the sin (Nθ-Nφ) signal is greater than 0. 5. The throttle valve rotation angle detecting device according to claim 4, wherein the deviation (Nθ−Nφ) is determined to be negative when the value is smaller.   The rotation angle detection device for a throttle valve according to any one of claims 1 to 6, wherein the angle calculation unit (60) uses 0 as the calculated rotation angle φ at the start of detection.   The angle calculation unit (60) is an angle measured when the throttle valve (10) is assembled in the suction passage (12) and is fully closed as the calculated rotation angle φ at the start of detection. The rotation angle detecting device for a throttle valve according to any one of claims 1 to 7, wherein:   The temperature of the first and second magnetoelectric transducers (M1, M2) is inputted and the temperature is applied to the first and second signals output from the first and second magnetoelectric transducers (M1, M2). The throttle valve for a throttle valve according to any one of claims 1 to 8, further comprising a temperature correction unit that performs correction in accordance with the temperature and inputs the corrected signal to the angle calculation unit (60). Rotation angle detection device. The throttle according to any one of claims 1 to 9, wherein each of the first and second magnetoelectric transducers (M1, M2) is configured by a magnetoresistive element (R1 to R8). Valve rotation angle detector.

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