JP2000283861A - Torque detector - Google Patents

Abstract

(57) [Problem] To provide a torque detecting device capable of eliminating a variation in steering feeling caused by a characteristic difference of a sensor unit for detecting torque. SOLUTION: Before assembling a sensor unit to an actual vehicle, a difference between an inductance of the sensor unit and a reference inductance is determined.
It is stored in an EEPROM in the ECU as an individual difference due to processing accuracy of the sensor unit, variation in magnetic material, and the like. Then, the microcomputer in the ECU responds to the torque signal T taken from the sensor unit via the I / F circuit unit, by causing variations in the characteristics of the sensor unit and the I / F circuit unit due to environmental temperature, machining accuracy, assembly errors, and the like. The correction corresponding to is performed. At this time, the torque signal sensor unit characteristic difference correction 36 performs a correction corresponding to the characteristic difference of the sensor unit.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a torque detecting device for detecting a steering torque generated by operating a steering wheel, and more particularly to a torque detecting device used in an electric power steering device for assisting a steering torque by a driving force of an electric motor. It is suitable as a device.

[0002]

2. Description of the Related Art Conventionally, as a torque detecting device used in the electric power steering device, for example, FIGS.
0 is known. FIG. 19 is an explanatory view showing a structure of a steering mechanism of the electric power steering apparatus including a partial cross section, and FIG. 20 is an electric configuration of a torque detection apparatus provided in the steering mechanism shown in FIG. FIG. 4 is an explanatory diagram showing by a block. First, the structure of the steering mechanism is shown in FIG.
This will be described with reference to FIG. The steering mechanism 70 includes a hollow shaft 72 connected to a steering wheel (not shown) of the vehicle, and a lower portion of the shaft 72 is inserted into an upper portion 73 a of the housing 73. A shaft 74 is inserted through a lower portion 73b of the housing 73, and a pinion P that meshes with the rack R is attached to a lower portion of the shaft 74. The rack R is configured to transmit the rotational torque of a motor (not shown) that assists the steering force.

[0003] A torsion bar 75 is housed inside the shaft 72.
It is connected to the shaft 72 by a pin 76. The lower end of the torsion bar 75 is spline-engaged with the recess of the shaft 74. A sensor ring 77 made of a magnetic material is provided at an intermediate portion of the shaft 72 located inside the housing 73, and a sensor ring 78 made of a magnetic material is provided on the shaft 74. I have. Sensor ring 7 located inside housing 73
The sensor coils 79 and 78 are spaced apart from the sensor rings 77 and 78 by a predetermined gap at locations facing the outer peripheral surfaces of the sensor coils 79 and 78.
Is provided. That is, the sensor rings 77 and 78
, The sensor coil 79, and the gap between the sensor rings 77, 78 and the sensor coil 79.
1 is configured.

In the steering mechanism 70 having the above structure, when the steering torque is transmitted to the shaft 72 by operating the steering wheel, the torsion bar 75 is twisted to cause a relative displacement between the shaft 72 and the shaft 74, and a sensor is provided. The amount of overlap between the rings 77 and 78 is displaced, and the inductance generated in the sensor coil 79 changes. The inductance is detected by an interface circuit section (hereinafter, referred to as an I / F circuit section) 80 provided in the housing 73, converted into a torque signal, and transmitted to a microcomputer (hereinafter, referred to as a microcomputer) provided in the vehicle. Is output.

Next, the operation of the I / F circuit section 80 will be described with reference to FIG. The DC current supplied from the power supply input is converted into a reference voltage by a regulator circuit 83 after an extra harmonic component is removed by a filter circuit 82. Then, the oscillation circuit 84 generates a sine wave signal based on the reference voltage generated from the regulator circuit 83, and applies the sine wave signal to the sensor coil 79. Then, since a sine wave voltage proportional to the inductance of the sensor coil 79 is generated at both ends of the sensor coil 79, the AC component of the sine wave voltage is converted to a DC cut circuit 8
5, and further, by extracting the amplitude of the AC component by the detection circuit 86, the signal is converted into a signal having a DC voltage proportional to the amplitude, and is input to the addition circuit 87.

The sine wave voltage generated at both ends of the sensor coil 79 is also input to a temperature compensation circuit 88, and is converted into a temperature drift signal indicating the amount by which the inductance of the sensor coil 79 drifts under the influence of temperature. You. Then, the temperature drift signal is input as a compensation signal to an addition circuit 87. The addition circuit 87 extracts the difference between the signal output from the detection circuit 86 and the compensation signal output from the temperature compensation circuit 88, and obtains the temperature drift signal. A torque component signal of only the torque component whose component has been canceled is output to the scaling circuit 89. Subsequently, the scaling circuit 89 converts the gain of the torque component signal. The gain-converted torque component signal is amplified by the output amplifier circuit 90, and further amplified as a torque signal to an A / D input port of a microcomputer (not shown). Is output.

The microcomputer calculates an assist amount by the electric motor based on the magnitude of the input torque signal, and outputs a drive signal corresponding to the calculated assist amount from the motor drive circuit to the electric motor. The rotation torque of the motor is transmitted to the rack R (FIG. 19), and the steering torque is assisted. Further, since the scaling circuit 89, the output amplifier circuit 90, and the like constituting the I / F circuit section 80 are analog circuits, the output of the torque signal may fluctuate due to variations in the characteristics of the semiconductor elements. When such a change occurs, the assist amount calculated by the microcomputer changes, which may lead to a feeling of strangeness in the steering operation. Therefore, conventionally, the scaling circuit 89
And a potentiometer 89a in the output amplifier circuit 90,
By providing 90a, the output of each circuit can be finely adjusted so that the above-mentioned uncomfortable feeling does not occur.

[0008]

However, in the case where the torque to be detected varies from one sensor unit 71 to another due to variations in the mechanical processing accuracy of the sensor rings 77 and 78 and the sensor coil 79 or variations in the characteristics of the material. There is. That is, conventionally, since there is a characteristic difference in the sensor unit 71, even if the applied steering torque is the same, the assist amount calculated by the microcomputer is different for each electric power steering device. The rings could have been different.

SUMMARY OF THE INVENTION It is an object of the present invention to eliminate variations in steering feeling caused by a difference in characteristics of a sensor unit for detecting torque.

[0010]

Means for Solving the Problems, Functions and Effects of the Invention
In order to achieve the above object, the invention according to claims 1 to 3 includes a sensor unit for detecting a steering torque generated by operating a steering wheel connected to a steering mechanism, and based on an output of the sensor unit. Operating the electric motor by a drive signal corresponding to the calculated steering torque, and operating the electric power steering device to supplement the steering torque by the driving force of the electric motor. In a torque detecting device for detecting torque, a characteristic difference data storage unit for storing characteristic difference data indicating a characteristic difference of the sensor unit, and the characteristic difference data storage for a steering torque calculated by the steering torque calculation unit. Correction means for performing a correction corresponding to the characteristic difference data stored in the means. Adopt the technical means that.

The characteristic difference data storage means stores characteristic difference data indicating a characteristic difference of a sensor for detecting a steering torque generated by operating a steering wheel connected to the steering mechanism. The correction means corresponds to the characteristic difference data stored in the characteristic difference data storage means with respect to the steering torque calculated by the steering torque calculation means for calculating the steering torque based on the output of the sensor unit. Make corrections. Therefore, the calculated steering torque is
Since the variation due to the characteristic difference of the sensor unit can be eliminated, the situation in which the steering feeling varies even in the same vehicle model can be eliminated.

For example, when the sensor section is provided with a magnetic circuit whose inductance changes in response to the change in the steering torque, the difference from the reference inductance is indicated. The inductance difference is stored as characteristic difference data. Then, a correction corresponding to the inductance difference stored in the characteristic difference data storage unit is performed on the calculated steering torque.
As a result, the calculated steering torque can be prevented from varying due to the variation in the inductance of the magnetic circuit, so that the situation in which the steering feeling varies even in the same vehicle type can be eliminated.

In particular, according to the third aspect of the present invention, since the rewriting means for rewriting the characteristic difference data stored in the characteristic difference data storage means is provided, for example, the characteristics of the sensor section change due to aging or the like. Even if the characteristic difference has changed, the characteristic difference data can be rewritten, so that the calculated steering torque can be corrected according to the rewritten characteristic difference data. It is possible to eliminate a situation in which the steering feeling varies with the same model due to aging.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a torque detecting device according to the present invention will be described below with reference to the drawings. FIG. 1 is an explanatory diagram showing the structure of the steering mechanism including a partial cross section. FIG.
FIG. 2A is a block diagram illustrating an electric configuration of an electric power steering apparatus having the steering mechanism shown in FIG.
FIG. 2B is an explanatory diagram showing the storage contents of the EEPROM 29 shown in FIG.

As shown in FIG. 1, the steering mechanism 60 is
9 has substantially the same structure as the conventional steering mechanism 70 shown in FIG.
This embodiment is different in that the I / F circuit section 80 is not provided. The I / F circuit unit is provided in an electronic control unit (hereinafter, referred to as an ECU) 100 provided in the vehicle, as indicated by reference numeral 50 in FIG.
The I / F circuit unit 50 is connected to the microcomputer 20,
The microcomputer 20 is connected to a motor drive circuit 102 that drives the electric motor M. Also, the ECU 100 includes:
An EEPROM 29 is provided.
Are connected to the microcomputer 20. EEPROM 29
Stores various data to be described later used for correcting the torque value when the microcomputer 20 calculates the torque value.

Next, the electrical configuration of the sensor section 71, the I / F circuit section 50 and the microcomputer 20 will be described with reference to FIG. The sensor unit 71 includes a sensor coil 79, sensor rings 77 and 78 (FIG. 1), a sensor coil 79 and sensor rings 77 and 78.
It is composed of a magnetic circuit consisting of a gap between them. I
/ F circuit section 50 includes a torque detection circuit 5 for detecting torque.
1 and a failure detection circuit 56 for detecting an abnormality of the torque detection circuit 51. The main oscillation circuit 52 constitutes an LR oscillation circuit by its own resistance and the inductance generated in the sensor coil 79, and oscillates a pulse signal having a cycle corresponding to the inductance generated in the sensor coil 79. The pulse signal oscillated from the main oscillation circuit 52 is shaped by a pulse shaping circuit 53, and the shaped pulse signal is input to the timer input 20a of the microcomputer 20 as a torque signal T.

The temperature detection circuit 54 extracts a DC component from the AC / DC superimposed signal generated in the sensor coil 79, adds necessary scaling to the extracted DC component, and outputs a signal obtained by adding the scaling to a temperature characteristic signal (hereinafter, referred to as a temperature characteristic signal). A / D input 2 of microcomputer 20 as Vt
0b and the differential amplifier circuit 65. Further, the torque detection circuit 51 is provided with a temperature sensor 55 for detecting a circuit temperature of the I / F circuit section 50. A circuit temperature signal th detected by the temperature sensor 55 is supplied to the A / D Output to input 20c. In the present embodiment, a thermistor is used as the temperature sensor 55.

The fail detection circuit 56 includes a sub-oscillation circuit 57 having substantially the same configuration as the main oscillation circuit 52 provided in the torque detection circuit 51. Similarly to the main oscillation circuit 52, the sub-oscillation circuit 57 has a low resistance due to its own resistance and the inductance of the sensor coil 79.
An R oscillation circuit is formed, and a pulse signal having a cycle corresponding to the inductance of the sensor coil 79 is oscillated at the oscillation timing of the main oscillation circuit 52.

The signal oscillated from the sub-oscillator 57 is shaped by a pulse shaping circuit 58, and the shaped signal is output to the timer input 20d of the microcomputer 20 as a monitor 1 signal. Further, the failure detection circuit 5
6 is provided with a temperature detection circuit 59 having substantially the same configuration as the temperature detection circuit 54 provided in the torque detection circuit 51. The temperature detection circuit 59 extracts a DC component from the AC / DC superimposed signal generated in the sensor coil 79, adds necessary scaling to the extracted DC component, and outputs a signal obtained by adding the scaling to the differential amplifier circuit 65. .
The output from the differential amplifier circuit 65 is input to the A / D input 20e of the microcomputer 20 as a monitor 2 signal.

Here, the main flow from steering operation to steering torque assist will be described. When the steering wheel is operated, the torsion bar 75 (FIG. 1) is twisted, so that the shaft 72 and the shaft 7 are rotated.
4, a relative displacement occurs, the amount of overlap between the sensor rings 77 and 78 changes, and the inductance of the sensor coil 79 changes. The main oscillation circuit 52 oscillates a pulse signal having a cycle corresponding to the inductance, and the pulse signal undergoes waveform shaping by a pulse shaping circuit 53 to become a torque signal T as a timer input 20 of the microcomputer 20.
is input to a. Then, the microcomputer 20 calculates a torque value based on the cycle of the received torque signal T. Subsequently, the torque value is applied to the motor drive circuit 102 (FIG. 2).
(A)), the motor drive circuit 102 outputs a drive signal corresponding to the torque value to the electric motor M. Then, the electric motor M rotates, and the rotation torque
(FIG. 1), and the steering torque is assisted.

The microcomputer 20 corrects the torque signal T due to a change in the temperature of the sensor unit 71 using the taken temperature characteristic signal Vt, and corrects the change in the temperature of the I / F circuit unit 50 using the circuit temperature signal th. The torque signal T is corrected.
Further, the microcomputer 20 controls the torque signal T and the monitor 1
The signals are monitored, and if a predetermined difference occurs between the two signals, it is determined that an abnormality has occurred in the main oscillation circuit 52.
The determination is made, for example, by setting the pulse width B of the monitor 1 signal to 2
A value obtained by subtracting the period A of the torque signal from the multiplied value (2B
-A) is performed based on whether or not the predetermined value C is exceeded. Further, the microcomputer 20 monitors the voltage V2 of the monitor 2 signal, and when the voltage V2 is out of a predetermined range,
It is determined that an abnormality has occurred in the temperature detection circuit 54. The determination is made based on, for example, whether or not the voltage V2 is out of the range of VB ≦ V2 ≦ VA.

Next, a characteristic portion of the torque detecting device according to the present embodiment will be described with reference to FIGS. The torque detection device according to the present embodiment includes a sensor 71 and an I / O
In addition to correcting the variation in the torque signal T due to the temperature change and the assembly error of the F circuit unit 50, the variation in the torque signal T due to the characteristic difference of the sensor unit 71 is corrected, and the variation in the steering feeling due to the same vehicle type is reduced. It can be eliminated. In addition, various deviation amounts acquired in each processing described below are determined by the ECU 1
00 in the EEPROM 29 (FIG. 2B).

FIG. 4 is an explanatory diagram showing the flow of processing from the time when the microcomputer 20 takes in the torque signal T, makes the above-described corrections, and calculates the torque value. 5 to 7 are explanatory diagrams showing details of the processing performed in each block shown in FIG. FIGS. 8 to 10 are flowcharts showing the flow of processing executed by the microcomputer 20 in real time. FIG. 8 is a flowchart showing a flow of a torque signal calculation executed based on the torque signal T. FIG. 9 is a flowchart showing a flow of a temperature characteristic signal calculation executed based on the temperature characteristic signal Vt. 5 is a flowchart showing a flow of a circuit temperature calculation executed based on a circuit temperature signal th.

FIGS. 11 to 16 correspond to FIGS.
5 is a flowchart showing a flow of a process performed in advance to acquire data used when executing each process shown in FIG. FIGS. 11 to 13 are flowcharts showing the flow of processing for acquiring data before assembling the I / F circuit unit 50 and the sensor unit 71 to an actual vehicle. FIG.
FIG. 12 is a flowchart illustrating a flow of a process for acquiring data such as a deviation amount of a torque signal due to a temperature change when the I / F circuit unit 50 is used alone. FIG. FIG. 13 is a flowchart illustrating a flow of a process for obtaining data such as a deviation amount of a temperature characteristic signal, and FIG. 13 is a flowchart illustrating a flow of a process for obtaining an inductance difference due to a characteristic difference of the sensor unit 71.

FIGS. 14 to 16 show an I / F circuit section 50.
9 is a flowchart showing a flow of a process for acquiring data after assembling the sensor unit 71 to an actual vehicle. FIG.
FIG. 15 is a flowchart showing a flow of a process for acquiring torque signal data at a normal temperature, FIG. 15 is a flowchart showing a flow of a process for acquiring temperature characteristic signal data at a normal temperature, and FIG. 4 is a flowchart showing a flow of processing for calculating a coefficient for inductance correction.

[Before Assembly] First, the I / F circuit unit 50
A process of acquiring data before assembling the sensor unit 71 to an actual vehicle will be described with reference to FIGS. First, a process for acquiring data such as a deviation amount of a torque signal due to a temperature change when the I / F circuit unit 50 alone is described with reference to FIG. This processing is performed when the I / F circuit unit 50 is completed.
This is performed separately by the I / F circuit unit 50 alone, for example, under a constant temperature environment in a temperature aging process and a burn-in inspection process of the I / F circuit unit 50. Also,
In this process, a sine wave voltage serving as a reference is supplied to the I / F circuit unit 50.
And the torque signal T output from the I / F circuit unit 50 is taken into the microcomputer.

First, an I / O set at an ambient temperature of 20 ° C.
A torque signal (hereinafter, referred to as torque signal T (20)) output from the F circuit unit 50 is fetched (step (hereinafter abbreviated as S) 401), and the fetched torque signal T
The shift amount of the cycle of (20) (hereinafter, referred to as shift amount T (20)) is calculated, and the shift amount T (20) is stored in a memory (for example, a memory built in a microcomputer) (S40).
3). Also, this deviation amount T (20) is
(FIG. 2B). This EEPROM 29
Is used for calculation in the later-described torque signal circuit section offset correction (S101 in FIG. 8, and 21 in FIGS. 4 and 5). Subsequently, the torque signal when the ambient temperature is 80 ° C. (hereinafter, the torque signal T (8
0)) (S405), and the amount of deviation of the cycle of the acquired torque signal T (80) (hereinafter, referred to as deviation amount T (80)) is stored in the memory (S40).
7).

Then, the shift amount T (8
0) minus the deviation amount T (20) (T (80)
-T (20)) is calculated by dividing the temperature difference 60 (80-20) by a value K1 (S409). That is, the shift amount K1 of the cycle per 1 ° C. is obtained. Subsequently, the deviation amount K1 is stored in the EEPROM 29 (S411). This deviation amount K1 is determined by correcting the inclination of the torque signal circuit section described later (S
103 and 22) in FIGS. 4 and 5.

Next, the flow of a process for acquiring data such as a deviation amount of a temperature characteristic signal due to a temperature change in the case of the I / F circuit unit 50 alone will be described with reference to FIG. This processing is also performed under the same environment as the processing for obtaining the amount of deviation of the cycle of the torque signal T described above. First, a temperature characteristic signal (hereinafter referred to as a temperature characteristic signal Vt (20)) output from the I / F circuit 50 when the ambient temperature is 20 ° C. is captured (S501), and the captured temperature characteristic signal Vt (20) is acquired. (Hereinafter referred to as a deviation amount Vt (20)), and the deviation amount Vt (20) is stored in a memory (S503). Further, the deviation amount Vt (20) is also stored in the EEPROM 29 (FIG. 2B). The deviation amount Vt (20) stored in the EEPROM 29 is used for the calculation in the temperature correction signal circuit offset correction (S201 in FIG. 9 and 26 in FIGS. 4 and 5) to be described later. Subsequently, a temperature characteristic signal when the ambient temperature is 80 ° C. (hereinafter, referred to as a temperature characteristic signal Vt (80)) is fetched (S505), and the voltage deviation amount of the fetched temperature characteristic signal Vt (80) (hereinafter, referred to as S505) , Deviation amount Vt
(Referred to as (80)) in the EEPROM 29 (S
507).

Then, the deviation amount Vt stored in the memory
(Vt) obtained by subtracting the shift amount Vt (20) from (80)
(80) -Vt (20)) with a temperature difference of 60 (80-20)
Is calculated (S509). That is, 1
The shift amount K2 per ° C is determined. Subsequently, the deviation amount K
2 is stored in the EEPROM 29 (S511). The deviation amount K2 is used for an arithmetic process in the later-described temperature characteristic signal circuit portion inclination correction (S203 in FIG. 9 and 27 in FIGS. 4 and 5).

Next, a flow of processing for obtaining an inductance difference due to a characteristic difference of the sensor unit 71 will be described with reference to FIG.
This will be described with reference to FIG. This processing is also performed under the same environment as the processing for obtaining the amount of deviation of the cycle of the torque signal T described above. First,
An inductance L1 of the sensor coil 79 at an ambient temperature of 20 ° C. is detected (S901), and the detected inductance L1 is stored in a memory (S903). Subsequently, the inductance difference ΔL is calculated by subtracting the reference inductance L0 from the inductance L1 (S905), and the calculated inductance difference ΔL is stored in the EEPROM 29 (FIG. 2).
(B)) (S907). This inductance difference ΔL is used for calculation in the later-described torque signal sensor section characteristic difference correction (S112 in FIG. 8, and 36 in FIGS. 4 and 6).

[After Assembling] Next, FIGS. 14 to 16 show a process for acquiring data serving as a reference for correcting an assembling error when the sensor unit 71 and the I / F circuit 50 are assembled to an actual vehicle. It will be described with reference to FIG. The following processes are performed, for example, at room temperature (10
C. to 20.degree. C.) in a factory inspection process. The following processes are performed by the sensor unit 71 and the I / F
The circuit unit 50 is assembled to an actual vehicle, the steering is steered by a predetermined reference angle, and the steering is performed in a state where a predetermined steering torque is generated.

First, the flow of a process for obtaining torque signal data will be described with reference to FIG. At the normal temperature, the torque signal T output from the I / F circuit unit 50 in the above state
(C) is fetched (S601), and the cycle amount of the fetched torque signal T (c) is shifted (hereinafter referred to as a shift amount T3 (c)).
Is calculated, and the deviation amount T3 (c) is calculated as EEPR
It is stored in the OM 29 (FIG. 2B) (S603). The deviation amount T3 (c) is used for the calculation in the torque signal sensor unit offset correction (S107 in FIG. 8, 31 in FIGS. 4 and 6).

Next, the flow of processing for acquiring temperature characteristic signal data will be described with reference to FIG. This process is also performed in the same state as the torque signal data acquisition process (FIG. 14). I
/ Temperature characteristic signal Vt at normal temperature output from the / F circuit unit 50
(C) is fetched (S701), and the voltage deviation amount of the fetched temperature characteristic signal Vt (c) (hereinafter, deviation amount Vt3)
(Referred to as (c)), and stores the deviation Vt3 (c) in the EEPROM 29 (FIG. 2B) (S70).
3). This deviation amount Vt3 (c) is determined by the temperature correction signal sensor offset correction (S207 in FIG. 9 and 3 in FIGS. 4 and 6).
Used for the calculation in 4).

Next, a flow of a coefficient calculation process for inductance correction will be described with reference to FIG. This process is also performed in the same state as the torque signal data acquisition process (FIG. 14). The product (K5 × Vt3 (c)) of the constant K5 and the deviation amount Vt3 (c) obtained in the temperature characteristic signal data acquisition processing (FIG. 15) described above is added to the torque signal data acquisition processing (FIG. 14). A coefficient T7 is calculated by adding the shift amount T3 (c) calculated in S603) (S80).
1) The coefficient T7 is stored in the EEPROM 29 (FIG. 2B).
(S803). This coefficient T7 is used for correcting the inductance of the torque signal sensor unit described later (S10 in FIG. 8).
9, and 32) in FIG. 4 and FIG.

[Flow of Torque Calculation] Next, the microcomputer 2
0 takes in the torque signal T from the I / F circuit unit 50,
FIGS. 4 to 6 and FIGS. 8 to 10 show a flow of calculating an accurate torque value while correcting the taken-in torque signal T using various deviation amounts stored in the EEPROM 29 in the above-described processing. This will be described with reference to FIG. The following description will be made in accordance with the flow shown in FIGS. [Torque signal circuit offset correction 21] microcomputer 20
Takes the torque signal T output from the I / F circuit unit 50 into the timer input 20a, calculates the cycle T (t), and calculates the displacement T (t) stored in the EEPROM 29 in the cycle T (t). 20) due to the correction to add
Is calculated (S101 in FIG. 8).

[Conversion from Voltage to Temperature 24] On the other hand, the microcomputer 20 converts the circuit temperature signal th output from the I / F circuit section 50 into the A / D input 20 in the circuit temperature calculation of FIG.
c, and the voltage of the circuit temperature signal th is set to a circuit temperature corresponding to the voltage (hereinafter, referred to as a circuit temperature tc0).
(S301 in FIG. 10). This conversion is performed using map data in which the voltage th and the temperature tc0 are associated with each other, as shown at 24 in FIG. [100 weighted average 25] Then, the microcomputer 20
The circuit temperature tc weighted using the weighted average of the 00 temperatures tc0 is calculated (S303 in FIG. 10). [Torque signal circuit section inclination correction 22] and microcomputer 2
0 is the value of the EEPROM 29 in the torque signal calculation of FIG.
Is corrected by multiplying the shift amount K1 stored in the step S1 by the weighted circuit temperature tc calculated in S303 of the circuit temperature calculation to calculate K1 · tc, and the K1 · tc is calculated in S101. The cycle T2 is calculated by the correction for adding the cycle T1 (S103 in FIG. 8).

[Temperature Feature Signal Circuit Offset Correction 26] On the other hand, the microcomputer 20 calculates the I / O
The temperature characteristic signal Vt output from the F circuit unit 50 is taken into the A / D input 20b, and the voltage Vt of the temperature characteristic signal Vt is added to E / E.
The voltage Vt1 is calculated by a correction for adding the shift amount Vt (20) stored in the EPROM 29 (S2 in FIG. 9).
01). [Temperature signal signal section inclination correction 27] Subsequently, the microcomputer 20
Is the displacement amount K2 stored in the EEPROM 29,
K2 · tc is corrected by multiplying the weighted circuit temperature tc calculated in S303 of the circuit temperature calculation.
Is calculated, and the voltage Vt2 is calculated by correcting the voltage Vt1 calculated in S201 to K2 · tc (S203 in FIG. 9).

[Torque Signal Circuit Nonlinear Correction 23] The microcomputer 20 responds to the weighted circuit temperature tc in a nonlinear region where the circuit temperature th exceeds a predetermined value, for example, 100 ° C. in the torque signal calculation of FIG. The nonlinear correction is performed by adding the offset amount ΔT2 to the cycle T2 and calculating the cycle T3 (FIG. 8).
S105). The calculation of the offset amount ΔT2 is shown in FIG.
As shown in (23), this is performed using map data in which ΔT2 and tc are associated. [Temperature signal signal section inclination correction 27]
In the non-linear region where the circuit temperature th exceeds a predetermined value, for example, 100 ° C. in the temperature characteristic signal calculation of FIG. 9, the offset amount ΔVt2 corresponding to the weighted circuit temperature tc
Is added to the voltage Vt2 and the voltage Vt3 is calculated to perform the non-linear correction of the temperature characteristic signal circuit section (S20 in FIG. 9).
5). The calculation of the offset amount ΔVt2 is performed by referring to 28 in FIG.
As shown in the above, the process is performed using map data in which ΔVt2 and tc are associated with each other.

[Torque Signal Sensor Offset Correction 3]
1] Then, in the cycle T3 calculated in S105 in the torque signal calculation of FIG.
29 is added to the shift amount T3 (c) stored in
4 is calculated (S107 in FIG. 8). [Torque Signal Sensor Inductance Correction 32] Subsequently, the microcomputer 20 calculates a shift amount K7 with respect to the shift amount T7 stored in the EEPROM 29, and multiplies the shift amount K7 by the cycle T4 calculated in S107 to generate a cycle. T
5 is calculated (S109 in FIG. 8). The calculation of the shift amount K7 is performed using map data in which K7 and T7 are associated with each other, as indicated by 32 in FIG.

[Temperature characteristic signal sensor part offset correction 34]
On the other hand, in the temperature characteristic signal calculation of FIG.
The shift amount Vt3 (c) stored in the EEPROM 29 is added to the voltage Vt3 calculated in 205 to obtain a voltage Vt4.
Is calculated (S207 in FIG. 9). [Conversion from voltage to temperature 44] Subsequently, the microcomputer 20
The voltage Vt4 calculated in S207 is converted into the temperature Vts (S209 in FIG. 9). This conversion is performed using map data in which the voltage Vt4 and the temperature Vts are associated with each other, as indicated by 44 in FIG. [100 weighted average 45] Subsequently, the microcomputer 20
The circuit temperature Vtsa weighted using the weighted average of the 00 temperatures Vts is calculated (S303 in FIG. 10).

[Torque Signal Sensor Temperature Correction 33] The microcomputer 20 calculates the torque signal in FIG.
The deviation ΔT5 of the inductance with respect to the temperature of the sensor coil 79 with respect to the circuit temperature Vtsa calculated in S211 of the temperature characteristic signal calculation is calculated from the deviation ΔT5 of the inductance, and the period T5 calculated in S109 is calculated based on the deviation ΔT5.
Is added to calculate the period T6 (S111 in FIG. 8).

[Torque signal sensor unit characteristic difference correction 36] Subsequently, the microcomputer 20 reads the inductance difference ΔL stored in the EEPROM 29 and uses the map data shown in 36 in FIG. 6 to correspond to the inductance difference ΔL. The correction coefficient K8 is calculated, and the cycle T calculated in S111 is calculated.
8 is multiplied by a correction coefficient K8 to calculate a period T7 (FIG. 8).
S112). In this way, by performing the characteristic difference correction of the torque signal sensor unit, it is possible to eliminate the deviation of the cycle of the torque signal T due to the characteristic difference of the sensor unit 71.

[Conversion from cycle to torque 41, torque value 4
2,100 weighted averages 43] And the microcomputer 20
The cycle T7 calculated in S112 is converted into a torque corresponding to the cycle T7, and a torque value tq100 is calculated (S113 in FIG. 8). This conversion is performed using map data in which the cycle T7 and the torque tq100 are associated with each other, as indicated by 41 in FIG. Subsequently, the microcomputer 20 executes S1
Weighting is performed by performing weighted averaging on the tq100 calculated in step 13 (S115). This weighted tq100
Is sent to the motor drive circuit 102 (FIG. 2A),
The motor drive circuit 102 supplies a drive signal of a cycle corresponding to tq100 to the electric motor M. As a result, the electric motor M rotates, the rotational torque of the electric motor M is transmitted to the rack R (FIG. 1), and the steering torque is assisted.
The microcomputer 20, the EEPROM 29, and the I / F described above.
The circuit section 50 corresponds to the torque detection device of the present invention.

As described above, if the torque detecting device of the present embodiment is used, the deviation of the cycle of the torque signal T due to the characteristic difference of the sensor unit 71 can be corrected by the torque signal sensor unit characteristic difference correction 36.
This can be eliminated by (S112). In addition, variations in characteristics of the sensor unit 71 and the I / F circuit unit 50 due to a change in environmental temperature, processing accuracy, an assembly error, and the like can be eliminated by the above various correction processes. Therefore, it is possible to eliminate a situation in which the steering feeling is different in the same vehicle type in which the torque detecting device is mounted.
In addition, since the correction processing can be automatically executed by software in accordance with the magnitude of the variation, it is not necessary to adjust individual analog circuits.

Next, a torque detecting device according to a second embodiment of the present invention will be described with reference to FIGS. The inductance of the sensor coil 79 of the sensor unit 71 may change with aging. Therefore, for example, the configuration is such that the inductance difference ΔL can be rewritten at the time of vehicle inspection. FIG. 17 is a flowchart showing the flow of the rewriting process, and FIG.
It is an explanatory view showing a steering mechanism to which the torque detection device according to the second embodiment is applied.

As shown in FIG. 18, a detection terminal 62 for detecting the inductance of the sensor coil 79 is provided at the right end of the steering mechanism 61 in the drawing. To detect the inductance L1 of the sensor coil 79. Then, the inductance difference ΔL is obtained by the flow shown in FIG. The inductance L1 of the sensor coil 79 is detected (S92
1), the inductance L1 is stored in the memory (S9).
23), from the inductance L1 to the reference inductance L
0 is subtracted to obtain the inductance difference ΔL (S92
5) The inductance difference ΔL is stored in the EEPROM 29 (S927). As described above, if the torque detection device of the second embodiment is used, the inductance difference ΔL can be rewritten to the latest data even when the inductance of the sensor coil 79 changes due to aging or the like. Therefore, the secular change of the steering feeling can be suppressed.

In each of the above embodiments, the sensor 71
Although the inductance difference ΔL is used to correct the characteristic difference described above, the difference in impedance Z of the sensor unit 71 may be used as ΔZ. The conditions such as the ambient temperature when various data are acquired before and after assembling are not limited to the above-mentioned conditions, and can be changed. The above-described inductance difference ΔL corresponds to the characteristic difference data of the present invention, the EEPROM 29 corresponds to the characteristic difference data storage means, and the microcomputer 20 executes S90 in FIG.
1 to S907 function as the characteristic difference data storage unit of the present invention. 8 executed by the microcomputer 20.
Function as the correcting means of the present invention,
S927 functions as rewriting means.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing a structure of a steering mechanism that functions by a torque detecting device according to an embodiment of the present invention, including a partial cross section.

FIG. 2A is an explanatory diagram showing an electric configuration of an electric power steering apparatus having the steering mechanism shown in FIG. 1 by blocks, and FIG. 2B is a diagram showing FIG. 2A; EEPROM shown in
FIG. 29 is an explanatory diagram showing storage contents of No. 29.

FIG. 3 is an explanatory diagram showing the electrical configuration of a sensor unit 71, an I / F circuit unit 50, and a microcomputer 20 by blocks.

FIG. 4 is an explanatory diagram showing, in a block diagram, a flow of processing until a microcomputer 20 takes in a torque signal T, performs each of the above corrections, and calculates a torque value.

FIG. 5 is an explanatory diagram showing details of processing performed in each block shown in FIG. 4;

FIG. 6 is an explanatory diagram showing details of processing performed in each block shown in FIG. 4;

FIG. 7 is an explanatory diagram showing details of processing performed in each block shown in FIG. 4;

FIG. 8 is a flowchart showing a flow of a torque signal calculation executed based on the torque signal T;

FIG. 9 is a flowchart illustrating a flow of a temperature characteristic signal calculation performed based on the temperature characteristic signal Vt.

FIG. 10 is a flowchart showing a flow of a circuit temperature calculation executed based on a circuit temperature signal th.

FIG. 11 is a flowchart illustrating a flow of a process for acquiring data such as a deviation amount of a torque signal due to a temperature change when the I / F circuit unit 50 is alone.

FIG. 12 is a flowchart illustrating a flow of a process for acquiring data such as a deviation amount of a temperature characteristic signal due to a temperature change when the I / F circuit unit 50 alone is used.

FIG. 13 is a flowchart showing a flow of a process for acquiring an inductance difference due to a characteristic difference of the sensor unit 71.

FIG. 14

5 is a flowchart showing a flow of processing for obtaining torque signal data at normal temperature.

FIG. 15 is a flowchart illustrating a flow of processing for acquiring temperature characteristic signal data at normal temperature.

FIG. 16 is a flowchart showing a flow of processing for calculating a coefficient for inductance correction.

FIG. 17 is a flowchart showing a flow of processing for rewriting the inductance difference ΔL in the second embodiment of the present invention.

FIG. 18 is an explanatory diagram showing a steering mechanism to which the torque detection device according to the second embodiment of the present invention is applied.

FIG. 19 is an explanatory view showing a structure of a steering mechanism of a conventional electric power steering apparatus including a partial cross section.

20 is an explanatory diagram showing in block form an electrical configuration of a torque detection device provided in the steering mechanism shown in FIG. 19;

[Explanation of symbols]

 Reference Signs List 20 microcomputer 29 EEPROM (characteristic difference data storage means) 50 I / F circuit unit 71 sensor unit 77, 78 sensor ring 79 sensor coil

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) B62D 119: 00

Claims (3)

[Claims] A sensor for detecting a steering torque generated by operating a steering wheel connected to a steering mechanism, calculating the steering torque based on an output of the sensor, and corresponding to the calculated steering torque. A driving signal for driving the electric motor, and a torque detecting device for detecting the steering torque in order to function the electric power steering device that supplements the steering torque with the driving force of the electric motor. Characteristic difference data storage means for storing characteristic difference data indicating the following: correction for performing a correction corresponding to the characteristic difference data stored in the characteristic difference data storage means for the steering torque calculated by the steering torque calculation means Means, and a torque detector. 2. The sensor unit includes a magnetic circuit whose inductance changes in response to the change in the steering torque. The characteristic difference data is an inductance difference indicating a difference from a reference inductance. The torque detecting device according to claim 1, wherein: 3. The torque detecting device according to claim 1, further comprising rewriting means for rewriting the characteristic difference data stored in said characteristic difference data storage means.