Sensor device

A sensor device includes sensors and an Electronic Control Unit (ECU). The sensors include sensor elements, a signal comparator, and a signal transmitter. The signal comparator compares a first main detection value from one of the sensor elements, and a first sub detection value from the other of the sensor elements. When the first main detection value matches the first sub detection value, the signal transmitter generates and transmits an output signal that includes a first main signal corresponding to the first main detection value without including a first sub signal corresponding to the first sub detection value. In such manner, the responsiveness of the sensor device may be improved, without deteriorating a reliability of the output signals from the sensor sections.

CROSS REFERENCE TO RELATED APPLICATION

The present application is based on and claims the benefit of priority of Japanese Patent Application No. 2015-148583, filed on Jul. 28, 2015, the disclosure of which is incorporated herein by reference.

TECHNICAL FIELD

The present disclosure generally relates to a sensor device.

BACKGROUND INFORMATION

A sensor device is, as disclosed in a patent document 1 for example, provided with a sensor section that has two detectors and a controller that performs an operation/calculation based on a signal transmitted from the sensor section. More practically, the sensor device in a patent document, Japanese Patent Laid-Open No. 2015-046770 (patent document 1) has a torque sensor and a microcontroller. The torque sensor includes two Hall elements and an interface circuit that generates and transmits an output signal including two detection signals respectively corresponding to detection values from the Hall elements. The microcontroller compares the two detection signals transmitted from the torque sensor, for determining an abnormality of the Hall elements.

In principle, the shorter the length of the output signal transmitted from the torque sensor, the shorter the transmission interval of the output signal from the torque sensor can be, thereby improving responsiveness of the sensor device. However, the device in the patent document 1 transmits two detection signals to the microcontroller by serial transmission, for enabling an abnormality determination of the Hall elements by the microcontroller. Therefore, the device in the patent document 1 has a longer output signal length, in comparison to a transmission of one detection signal, thereby increasing the transmission interval and deteriorating the responsiveness.

SUMMARY

It is an object of the present disclosure to provide a sensor device having an improved responsiveness, which is enabled without deteriorating the reliability of the output signal transmitted from a sensor section.

In an aspect of the present disclosure, the sensor device includes: one or more sensor sections and a controller. The sensor section has a main detector and a sub detector respectively detecting an amount regarding a detection object, a signal comparator comparing a main detection value from the main detector and a sub detection value from the sub detector, and a signal transmitter generating and transmitting an output signal that includes a main signal corresponding to the main detection value without including a sub signal corresponding to the sub detection value, when the main detection value and the sub detection value are matching. The controller includes a signal obtainer that obtains the output signal, and a calculator that performs calculation based on the output signal obtained by the signal obtainer.

According to the present disclosure, the sensor section has the signal comparator that compares the main detection value and the sub detection value. Therefore, the sensor section is enabled to determine abnormality of each of the detectors. Further, when each of the detectors is normal, by generating and transmitting the output signal that includes the main signal without including the sub signal, the signal length of the output signal is reduced, i.e., shortened or shrunk. Therefore, without deteriorating the reliability of the output signal transmitted from the sensor section, the responsiveness of the sensor device is improved.

Throughout the specification and claims, what the main detection value matches the sub detection value means not only a complete matching between the main and sub detection values, but also a partial matching therebetween, i.e., when a difference between the main and sub detection values is equal to or smaller than a preset value. Therefore, in other words, the mismatch of the main and sub detection values means that the difference between the main and sub detection values is greater than the preset value.

DETAILED DESCRIPTION

Hereafter, plural embodiments of the present disclosure are described based on the drawings.

Hereafter, same numerals are assigned to same components in the following embodiments, and descriptions of the same components are not repeated.

First Embodiment

The first embodiment of the present disclosure is described based onFIGS. 1-6.

As shown inFIGS. 1 and 2, a sensor device1is applied to an electric power steering apparatus80, in which an Electronic Control Unit (ECU)85is provided together with a first magnetic sensor50, a second magnetic sensor60, and the like, for example, for assisting a steering operation of a vehicle. The first and second magnetic sensors50,60are “sensor sections” in claims. the ECU85is a “controller” in claims.

The entire configuration of a steering system90having the electric power steering apparatus80is described. As shown inFIG. 1, a steering wheel91as a steering component is connected with a steering shaft92.

The steering shaft92has an input shaft11and an output shaft12. The input shaft11is connected with the steering wheel91. At a position between the input shaft11and the output shaft12, a torque sensor10detecting a torque applied to the steering shaft92is disposed. A pinion gear96is disposed on one end of the output shaft12opposite to the input shaft11. The pinion gear96engages with a rack shaft97. A pair of wheels98is connected with both ends of the rack shaft97via a tie rod etc.

When a driver rotates the steering wheel91, the steering shaft92connected with the steering wheel91rotates. The rotation of the steering shaft92is turned into a translational motion of the rack shaft97by the pinion gear96, and the pair of wheels98is steered by an angle according to an amount of displacement of the rack shaft97.

The electric power steering apparatus80is provided with a motor81that outputs an assist torque for assisting a steering operation of the steering wheel91by the driver, a speed reduction gear82, the torque sensor10, the ECU85and the like. Although the motor81and the ECU85have separate bodies inFIG. 1, they may be combined to have one body.

The speed reduction gear82reduces a rotation speed of the motor81, and transmits the rotation of the motor81to the steering shaft92. That is, although the electric power steering apparatus80of the present embodiment is a so-called “column assistant type”, the apparatus80may also be a “rack assist type” that transmits rotation of the motor81to the rack shaft97. The details of the ECU85are mentioned later.

As shown inFIG. 2, the torque sensor10is provided with the input shaft11, the output shaft12, a torsion bar13, a multipolar magnet15, a magnetic yoke16, a detection object, such as a magnetic flux collection module20, a sensor unit40and the like.

The torsion bar13has one end connected with the input shaft11, and the other end connected with the output shaft12by a pin14, respectively, and connects the input shaft11and the output shaft12on the same axis, i.e., coaxially connects the shaft11and the shaft12on a rotation axis O. The torsion bar13is an elastic member in a rod shape, and converts a torque applied to the steering shaft92into a twist displacement.

The multipolar magnet15is formed in a cylinder shape, and is fixed to the input shaft11. On the multipolar magnet15, an N pole and an S pole are magnetized by turns along a periphery. Although the number of poles may be arbitrarily determined, the number of N poles and S poles is configured to be 12 pairs, having a total of 24 poles in the present embodiment. The magnetic yoke16is held by a yoke attachment component which is formed by a nonmagnetic material, e.g., resin, and which is not illustrated, and forms a magnetic circuit in a magnetic field that is generated by the multipolar magnet15.

The magnetic yoke16includes a first yoke17and a second yoke18, and the first yoke17is disposed on one side of the yoke16close to the input shaft11, and the second yoke18is disposed on the other side of the yoke16close to the output shaft12. Both of the first yoke17and the second yoke18have an annular shape, and are made with a soft magnetic material, and are fixedly attached to the output shaft12on a radius outside of the multipolar magnet15.

The magnetic flux collection module20includes magnetic flux collection rings21and22. The magnetic flux collection rings21and22are arranged on a radius outside of the magnetic yoke16, and collect the magnetic flux from the magnetic yoke16. A first magnetic flux collection ring21is disposed on one side of the module20close to the input shaft11, and a second magnetic flux collection ring22is disposed on the other side of the module20close to the output shaft12. The first magnetic flux collection ring21and the second magnetic flux collection ring22are held by a non-illustrated magnetic flux collection ring holder member that is formed by an insert molding etc.

The first magnetic flux collection ring21comprises (i) a ring part211that is made with the soft magnetic material substantially in a ring shape and (ii) two magnetic flux collecting parts215projecting toward a radius outside from the ring part211. The number of the magnetic flux collecting parts215may be configured to match the number of the magnetic sensors50,60mentioned in the following.

The second magnetic flux collection ring22comprises (i) a ring part221that is made with the soft magnetic material substantially in a ring shape, just like the first magnetic flux collection ring21, and two magnetic flux collecting parts225projecting toward a radius outside from the ring part221.

In the present embodiment, the first magnetic flux collection ring21and the second magnetic flux collection ring22have substantially the same form.

The magnetic flux collecting part215of the first magnetic flux collection ring21and the magnetic flux collecting part225of the second magnetic flux collection ring22are disposed to face each other, and have respective facing surfaces arranged substantially in parallel.

The magnetic sensors50and60are arranged at a position between the magnetic flux collecting parts215and225.

The sensor unit40includes a substrate41and the magnetic sensors50and60. The magnetic sensors50and60are mounted on the same surface of the substrate41.

The first magnetic sensor50outputs, i.e., transmits, a first output signal Sd10to the ECU85, and the second magnetic sensor60outputs, i.e., transmits, a second output signal Sd20to the ECU85.

As shown inFIG. 3, the first magnetic sensor50has a sealed body53and a first chip55, and the second magnetic sensor60has a sealed body63and a second chip65.

The configuration concerning the first magnetic sensor50is hereafter designated as 50-something numbers or 500-something numbers, and the configuration concerning the second magnetic sensor60is hereafter designated as 60-something numbers or 600-something numbers, suggesting that the same last one digit or last two digits indicate the same component/configuration. Hereafter, the description is focused on the first magnetic sensor50, and the same configuration of the sensor60may be not repeated whenever appropriate.

The sealed body53seals the first chip55. The sealed body53has a power supply terminal531, a communication terminal532, and a ground terminal533respectively disposed thereon and projecting therefrom.

The power supply terminal531is connected to the ECU85by a first power source line111, and the communication terminal532thereof is connected to the ECU85by a first communication line112, and the ground terminal533thereof is connected to the ECU85by a first ground line113.

Further, a power supply terminal631is connected to the ECU85by a second power source line121, and a communication terminal632is connected to the ECU85by a second communication line122, and a ground terminal633is connected to the ECU85by a second ground line123.

The voltage adjusted to a predetermined voltage value is supplied to the power supply terminals531and631from a regulator of the ECU85(not illustrated). The ground terminals533and633are connected with the ground via the ECU85.

The communication terminal532and the first communication line112are used for communications between the first magnetic sensor50and the ECU85. According to the present embodiment, the first output signal Sd10is transmitted to the ECU85from the first magnetic sensor50via the communication terminal532and the first communication line112.

Further, the communication terminal632and the second communication line122are used for communications between the second magnetic sensor60and the ECU85. According to the present embodiment, the second output signal Sd20is transmitted to the ECU85from the second magnetic sensor60via the communication terminal632and the second communication line122.

The first chip55includes a first main sensor element551(i.e., a main detector), a first sub sensor element552(i.e., a sub detector), Analog-to-Digital (A/D)-conversion circuits553and554, and a first interface circuit555and the like.

The sensor elements551and552are respectively a magnetic flux detecting element that detects the magnetic flux between the magnetic flux collecting parts215and225. The sensor elements551and552in the present embodiment are respectively implemented as a Hall element. Even though the sensor elements551and552are designated as “main” and “sub” elements in the present embodiment, for a distinction of signal orders, i.e., a sequence of signals, in the first output signal Sd10, the first main sensor element551and the first sub sensor element552are substantially the same element.

The A/D-conversion circuit553performs an A/D conversion of an analog signal indicative of a first main detection value detected by the first main sensor element551. The A/D-conversion circuit554performs an A/D conversion of an analog signal indicative of a first sub detection value detected by the first sub sensor element552.

The first interface circuit555has a signal comparator556and a signal transmitter557. The signal comparator556compares the first main detection value with the first sub detection value. Specifically, it is determined whether the first main detection value and the first sub detection value are matching.

According to the present embodiment, when the difference between both detection values is equal to or less than a predetermined value, it is considered that both detection values are matching, and when the difference between both detection values is larger than the predetermined value, both detection values are mismatched (i.e., it is considered that both (i.e., the two) detection values are not matching, unequal, or different from each other).

The signal transmitter557generates the first output signal Sd10based on the comparison result by the signal comparator556. The first output signal Sd10generated by the transmitter557is transmitted to the ECU85via the communication terminal532by the Single Edge Nibble Transmission (SENT) communication which is a kind of digital communications.

According to the present embodiment, when the first main detection value and the first sub detection value are matching, the signal transmitter557generates and transmits the first output signal Sd10, which includes the first main signal corresponding to the first main detection value, and which does not include the first sub signal corresponding to the first sub detection value.

Further, when the first main detection value and the first sub detection value are not matching, the signal transmitter557generates and transmits the first output signal Sd10including both of the first main signal and the first sub signal. The details of the first output signal Sd10are mentioned later.

The second interface circuit655has the signal comparator656and the signal transmitter657. The signal comparator656compares the second main detection value from a second main sensor element651with the second sub detection value by a second sub sensor element652. Specifically, it is determined whether the second main detection value and the second sub detection value are matching.

According to the present embodiment, when the difference between both detection values is equal to or less than the predetermined value, it is considered that both detection values are matching, and when the difference of both detection values is larger than the predetermined value, it is considered that both, i.e., the two, detection values are not matching.

The signal transmitter657generates the second output signal Sd20based on the comparison result by the signal comparator656. The second output signal Sd20generated by the transmitter657is transmitted to the ECU85by the SENT communication via the communication terminal632.

According to the present embodiment, when the second main detection value and the second sub detection value are matching, the signal transmitter657generates and transmits the second output signal Sd20, which includes the second main signal corresponding to the second main detection value, and which does not include the second sub signal corresponding to the second sub detection value.

Further, when the second main detection value and the second sub detection value are not matching, the signal transmitter657generates the second output signal Sd20including both of the second main signal and the second sub signal. The details of the second output signal Sd20are mentioned later.

Although the process in each of the function sections that is provided in the interface circuits555and655of the present embodiment is a hardware process by a dedicated electronic circuit for such process, the process may be a software process by an execution of a stored program by the CPU.

The ECU85may be a microcontroller or the like, and includes a signal obtainer851, an abnormality determiner855, a calculator858and the like.

The signal obtainer851obtains the output signals Sd10and Sd20that are transmitted from the magnetic sensors50and60.

The abnormality determiner855determines whether the magnetic sensors50and60are normal or abnormal. The details of abnormality determination are mentioned later.

The calculator858performs various operations/calculations based on the output signal transmitted from the magnetic sensor that is determined as normal from among the magnetic sensors50and60.

According to the present embodiment, the calculator858calculates a target value of a steering torque based on the output signal. The calculated target value of the steering torque is used for the drive control of the motor81.

The process in each of the function sections that is provided in the ECU85may be a software process by an execution of a stored program by CPU, or may be a hardware process by the dedicated electronic circuit.

Now, details of the first output signal Sd10are described based onFIG. 4andFIG. 5. Since the first output signal Sd10and the second output signal Sd20are substantially the same, the following description focuses on the first output signal Sd10. Note that the number of bits shown inFIG. 4andFIG. 5is just an example, and may be arbitrarily set up according to the telecommunications standard etc.

The contents of the first output signal Sd10are different depending on the matching between the first main detection value and the first sub detection value. That is, when the first main detection value and the first sub detection value are matching, i.e., the first main detection value is equal to the first sub detection value, the first output signal Sd10is made up from a synchronization signal, a status signal, a first main signal D11, a Cyclic Redundancy Check (CRC) signal, and a pause signal, as shown inFIG. 4, and the first output signal Sd10is outputted as a series of signals in the above-described order.

On the other hand, when the first main detection value and the first sub detection value do not match, i.e., are mismatched or different, or the first main detection value is not equal to the first sub detection value, the first output signal Sd10is made up from the synchronization signal, the status signal, the first main signal D11, first sub signal D12, the CRC signal, and the pause signal, as shown inFIG. 5, and the first output signal Sd10is outputted as a series of signals in the above-described order.

The synchronization signal is a signal for synchronizing the magnetic sensor50and the clock of the ECU85, and is set to 56 tick in the present embodiment. According to the present embodiment, the correction coefficient is calculated based on the length of the synchronization signal, and each signal is corrected by using the correction coefficient. For performing an abnormality determination process described later, the corrected signal that is corrected by the correction coefficient is used.

The first main signal D11and the first sub signal D12are respectively set to have 3 nibbles (=12 bits). The contents of data represented by each signal may have at least 1 nibble, according to the communication standard.

As shown inFIG. 6, the first main signal D11and the first sub signal D12are signals according to the magnetic flux between the magnetic flux collecting parts215and225, and are reversed from each other about a certain center value. In the present embodiment, the certain center value is a 50% value of an output code.

More practically, as shown by a solid line L1, the first main signal D11takes a lower limit value KL when the magnetic flux density is equal to or less than Bmin, and takes an upper limit value KH when the magnetic flux density is equal to or greater than Bmax, and the signal value of D11increases as the magnetic flux density increases from Bmin to Bmax.

Further, as shown by a dashed line L2, the first sub signal D12takes the upper limit value KH when the magnetic flux density is equal to or less than Bmin, and takes the lower limit value KL when the magnetic flux density is equal to or greater than Bmax, and the signal value of D12decreases as the magnetic flux density increases from Bmin to Bmax. Note that the value KL may be equal to 0%, and the value KH may be equal to 100%.

InFIG. 5, the first main signal D11and the first sub signal D12are illustrated as an identical pulse for illustration and simplification purposes. However, the pulses for the signals D11and D12are actually the reversed pulses about a certain center value, according to the detection value of the magnetic flux density.

When a data value indicated by the first main signal D11is designated as a first main data value, and a data value indicated by the first sub signal D12is designated as a first sub data value, according to the present embodiment, since the first main signal D11and the first sub signal D12are reversed from each other, the sum of the first main signal D11and the first sub signal D12is calculated as a preset value (henceforth a “theoretical addition value Va”).

According to the present embodiment, since the first main signal D11and the first sub signal D12are respectively provided as a signal of 3 nibbles, theoretical addition value Va is the maximum value “FFF” which is the maximum of the binary data in 3 digits. Further, when either of the first main signal D11or the first sub signal D12has abnormality, the sum of the first main signal D11and the first sub signal D12is calculated as a different value that is different from theoretical addition value Va.

Returning toFIG. 4, the CRC signal is a signal for detecting the communication error, and the length of the CRC signal is calculated based on the signals D11and D12. The pause signal is a signal outputted in a period before outputting the following synchronization signal.

Next, the process in the interface circuits555and655and the process in the ECU85are described with reference toFIGS. 7-9. These processes are performed when the magnetic sensors50and60and the ECU85are turned ON.

FIG. 7shows the process in the interface circuit555. In Step S101(hereafter, the “step” is omitted and a sign “S” is used) ofFIG. 7, the signal comparator556determines whether the first main detection value and the first sub detection value are matching. When it is determined that the first main detection value and the first sub detection value are matching (S101:YES), the process proceeds to S102. When it is determined that the first main detection value and the first sub detection value are not matching (S101:NO), the process proceeds to S103.

In S102, the signal transmitter557generates and transmits the first output signal Sd10which includes the first main signal D11, and which does not include first sub signal D12.

In S103, the signal transmitter557generates and transmits the first output signal Sd10including the first main signal D11and first sub signal D12.

FIG. 8shows the process in the interface circuit655.

In S111ofFIG. 8, the signal comparator656determines whether the second main detection value and the second sub detection value are matching. When it is determined that the second main detection value and the second sub detection value are matching (S111:YES), the process proceeds to S112. When it is determined that the second main detection value and the second sub detection value are not matching (S111:NO), the process proceeds to S113.

In S112, the signal transmitter657generates and transmits the second output signal Sd20which includes the second main signal D21, and which does not include the second sub signal D22.

In S113, the signal transmitter657generates and transmits the second output signal Sd20including first main signal D21and the second sub signal D22.

FIG. 9shows the process in the ECU85.

In S121ofFIG. 9, the signal obtainer851obtains the output signals Sd10and Sd20.

In S122, the abnormality determiner855determines whether communication of the first output signal Sd10is normal, based on the CRC signal of the first output signal Sd10. When communication of the first output signal Sd10is determined as abnormal (S122:NO), the process proceeds to S125. When communication of the first output signal Sd10is determined as normal (S122:YES), the process proceeds to S123.

In S123, the abnormality determiner855determines whether the first sub signal D12is included in the first output signal Sd10. For example, when the number of pulses between the status signal and the CRC signal is six in the first output signal Sd10, it is determined that first sub signal D12is included in the first output signal Sd10. When it is determined that the first sub signal D12is included in the first output signal Sd10(S123:YES), the process proceeds to S125. When it is determined that the first sub signal D12is not included in the first output signal Sd10(S123:NO), the process proceeds to S124.

In S124, the abnormality determiner855determines that the first magnetic sensor50is normal.

In S125, the abnormality determiner855determines that the first magnetic sensor50is abnormal.

In S126, which is subsequent to S124or S125, the abnormality determiner855determines whether communication of the second output signal Sd20is normal based on the CRC signal of the second output signal Sd20.

When communication of the second output signal Sd20is determined as abnormal (S126:NO), the process proceeds to S129.

When communication of the second output signal Sd20is determined as normal (S126:YES), the process proceeds to S127.

In S127, the abnormality determiner855determines whether the second sub signal D22is included in the second output signal Sd20. For example, when the number of pulses between the status signal and the CRC signal is six in the second output signal Sd20, it is determined that the second sub signal D22is included in the second output signal Sd20. When it is determined that the second sub signal D22is included in the second output signal Sd20(S127:YES), the process proceeds to S129. When it is determined that the second sub signal D22is not included in the second output signal Sd20(S127:NO), the process proceeds to S128.

In S128, the abnormality determiner855determines that the second magnetic sensor60is normal.

In S129, the abnormality determiner855determines that the second magnetic sensor60is abnormal.

In S130, it is determined whether both of the magnetic sensors50and60are abnormal. When both the magnetic sensors50and60are determined as abnormal (S130:YES), the calculation of the steering torque in S131is not performed. When it is determined that at least one the magnetic sensors50and60is normal (S130:NO), the process proceeds to S131.

In S131, the calculator858calculates a steering torque by using the main signal of the output signal transmitted from the magnetic sensor that is determined as normal among the magnetic sensors50and60.

When both the magnetic sensors50and60are normal, an average value of the first main signal D11and the second main signal D21, etc. may be used, or either one of the first main signal D11or the second main signal D21may be used for the steering torque calculation.

As described in full details above, the sensor device1of the present embodiment is provided with two magnetic sensors50and60and the ECU85.

The first magnetic sensor50has two sensor elements551and552and the first interface circuit555, which includes the signal comparator556and the signal transmitter557. The sensor elements551and552detect an amount regarding the detection object, i.e., the magnetic flux density between the magnetic flux collecting parts215and225.

The signal comparator556compares the first main detection value from the first main sensor element551with the first sub detection value from the first sub sensor element552.

When the first main detection value and the first sub detection value are matching, the signal transmitter557generates and transmits the first output signal Sd10, which includes the first main signal D11corresponding to the first main detection value, and which does not include the first sub signal D12corresponding to the first sub detection value.

The second magnetic sensor60is configured in the same manner as the first magnetic sensor50.

The ECU85has the signal obtainer851and the calculator858. The signal obtainer851obtains the first output signal Sd10and the second output signal Sd20.

The calculator858performs the calculation based on the output signals Sd10and Sd20which are obtained by the signal obtainer851.

Since the signal comparators556and656, which compare the main detection value with the sub detection value are provided in the magnetic sensors50and60, the abnormality of the sensor elements551,552,651, and652are determinable in the magnetic sensors50and60.

Further, when the sensor elements551and552are normal, the length of the first output signal Sd10is relatively short by generating and transmitting the first output signal Sd10in a manner that selectively includes the main signal and the sub signal, i.e., by including the main signal, but not including the sub signal. That is, a transmission period Ps1of the first output signal Sd10shown inFIG. 4becomes shorter than a transmission period Ps2of the first output signal Sd10shown inFIG. 5. The same applies to the second output signal Sd20. Therefore, the sensor device1is enabled to have an improved responsiveness, without deteriorating the reliability of the output signals Sd10and Sd20transmitted from the magnetic sensors50and60.

In the first embodiment, when the first main detection value and the first sub detection value are not matching, the signal transmitter557generates and transmits the first output signal Sd10including the first main signal D11and the first sub signal D12.

When the second main detection value and the second sub detection value are not matching, the signal transmitter657generates and transmits the second output signal Sd20including the second main signal D21and the second sub signal D22.

The abnormality determiner855of the ECU85determines that the first magnetic sensor50is abnormal, when the first sub signal D12is included in the first output signal Sd10which is obtained by the signal obtainer851. Further, the abnormality determiner855determines that the second magnetic sensor60is abnormal, when the second sub signal D22is included in the second output signal Sd20which is obtained by the signal obtainer851.

In such manner, the ECU85can determine the abnormality of the magnetic sensors50and60based on whether the sub signals D12and D22exist, i.e., are included, in the output signals Sd10and Sd20.

In the first embodiment, the first chip55has plural, i.e., two or more, sensor elements551and552, and the second chip65has plural, two or more, sensor elements651and652.

Therefore, even when the abnormality is caused in the second magnetic sensor60, the abnormality determiner855is enabled to continue a self-monitoring of the first magnetic sensor50based on the detection values of two or more sensor elements551and552of the first magnetic sensor50which is determined as normal.

Similarly, even when the abnormality is caused in the first magnetic sensor50, the abnormality determiner855is enabled to continue the self-monitoring of the second magnetic sensor60based on the detection values of two or more sensor elements651and652of the second magnetic sensor60which is determined as normal.

Thus, even when the abnormality is caused in one of the two magnetic sensors50and60, the ECU85is enabled to continue the self/abnormality-monitoring of the other, i.e., normal, one of the two magnetic sensors50and60, while calculating, with the same accuracy, the calculation of the steering torque as the both sensors normal time.

Further, the electric power steering apparatus80is provided with the sensor device1, the motor81, and the speed reduction gear82in the first embodiment. The motor81outputs the assist torque, which assists the steering operation of the steering wheel91by the driver. The speed reduction gear82transmits the torque of the motor81to the steering shaft92which is the drive object of the motor81. The ECU85controls the drive of the motor81based on the steering torque.

In the first embodiment, since the steering assist for assisting the steering operation of the steering wheel91by the driver is continuable according to the steering torque, even when the abnormality is caused in one of the magnetic sensors50and60, thereby improving the vehicle safety.

The ECU85may preferably notify the driver of the abnormality by using a warning lamp, a voice guidance or the like, when continuing the steering assist in an abnormality-caused state.

Second Embodiment

The second embodiment of the present disclosure is shown inFIG. 10.

In the second embodiment, the process in the interface circuits555and655is the same as that of the first embodiment, and the abnormality determination process in the ECU85is different from the first embodiment. Hereafter, the abnormality determination process is described with reference to a flowchart shown inFIG. 10.

The process of each of S141-S144inFIG. 10is the same as the process of each of S121-S124inFIG. 9. When a negative determination is performed in S142, and when an affirmation determination is performed in S143, the process proceeds to S145.

In S145, the abnormality determiner855determines whether the main data value indicated by the first main signal D11of the first output signal Sd10and an inverted value of the sub data value indicated by the first sub signal D12shows are matching. When it is determined that the main data value and the inverted value of the sub data value are matching (S145:YES), the process proceeds to S146. When it is determined that the main data value and the inverted value of the sub data value are mismatched (S145:NO), the process proceeds to S147.

In S146, the abnormality determiner855determines that the first magnetic sensor50is, or more specifically, the signal comparator556is, abnormal. The process of each of S147-S150is the same as the process of each of S125-S128inFIG. 9.

When a negative determination is performed in S148, and when an affirmation determination is performed in S149, the process proceeds to S151.

In S151, the abnormality determiner855determines whether the main data value indicated by the second main signal D21of the second output signal Sd20and an inverted value of the sub data value indicated by the second sub signal D22are matching. When it is determined that the main data value and the inverted value of the sub data value are matching (S151:YES), the process proceeds to S152. When it is determined that the main data value and the inverted value of the sub data value are mismatched (S151:NO), the process proceeds to S153.

In S152, the abnormality determiner855determines that the second magnetic sensor60is, or more specifically the signal comparator656is, abnormal.

The process of each of S153-S155is the same as the process of each of S129-S131inFIG. 9.

In the second embodiment as described above, the abnormality determiner855determines that, when (i) the first sub signal D12is included in the first output signal Sd10which is obtained by the signal obtainer851and (ii) the main data value of the first output signal Sd10and the inverted value of the sub data value of the first output signal Sd10are matching, the signal comparator556of the first magnetic sensor50is abnormal. Thereby, the abnormality determiner556in the magnetic sensor50can determine that the signal comparator556is abnormal.

Further, the abnormality determiner855determines that the signal comparator656of the second magnetic sensor60is abnormal, when (i) the second sub signal D22is included in the second output signal Sd20which is obtained by the signal obtainer851and (ii) the main data value of the second output signal Sd20and the inverted value of the sub data value of the second output signal Sd20are matching. Thereby, the abnormality determiner855can determine that the signal comparator656is abnormal.

Third Embodiment

The third embodiment of the present disclosure is shown inFIGS. 11-13. In the third embodiment, the process in the interface circuits555and655is the same as that of the first embodiment, and the abnormality determination process in the ECU85is different from the first embodiment. Hereafter, the abnormality determination process is described with reference to a flowchart shown inFIGS. 11-13.

The process of each of S161-S163inFIG. 11is the same as the process of each of S121-S123inFIG. 9. When a negative determination is performed in S162, and when the affirmation determination is performed in S163, the process proceeds to S169.

In S164, the abnormality determiner855determines whether a first abnormality determination flag Fa is set (i.e., Fa=1), which indicates that the first magnetic sensor50is determined as abnormal.

When it is determined that the first abnormality determination flag Fa is set (S164:YES), the process proceeds to S165ofFIG. 12.

When it is determined that the first abnormality determination flag Fa is not set (i.e., Fa=0) (S164:NO), the process proceeds to S168.

In S165, the abnormality determiner855determines whether a second abnormality determination flag Fb is set (i.e., Fb=1), which indicates that the second magnetic sensor60is determined as abnormal.

When it is determined that the second abnormality determination flag Fb is set (S165:YES), the process proceeds to S169ofFIG. 11.

When it is determined that the second abnormality determination flag Fb is not set (i.e., Fb=0) (S165:NO), the process proceeds to S166.

In S166, the abnormality determiner855determines whether (a) the main data value indicated by the first main signal D11of the first output signal Sd10that is transmitted from the first magnetic sensor50and (b) the main data value indicated by the second main signal D21of the second output signal Sd20that is transmitted from the second magnetic sensor60are matching.

When it is determined that the two main data values are matching (S166:YES), the process proceeds to S167.

When it is determined that the two main data values are mismatched (S166:NO), the process proceeds to S169ofFIG. 11.

In S167, the abnormality determiner855resets the first abnormality determination flag Fa noting that the first magnetic sensor50has recovered from an abnormal state (i.e., Fa=0). The process proceeds to S168ofFIG. 11after S167.

Returning the description toFIG. 11, in S168, and the abnormality determiner855determines that the first magnetic sensor50is normal. The process proceeds to S170after S168.

In S169, the abnormality determiner855determines that the first magnetic sensor50is abnormal, and the first abnormality determination flag Fa is set (i.e., Fa=1). The process proceeds to S170after S169.

The process of each of S170-S171is the same as the process of each of S126-S127inFIG. 9. When a negative determination is performed bin S170, and when an affirmation determination is performed in S171, the process proceeds to S177.

In S172, the abnormality determiner855determines whether the second abnormality determination flag Fb is set (i.e., Fb=1). When it is determined that the second abnormality determination flag Fb is set (S172:YES), the process proceeds to S173ofFIG. 13. When it is determined that the second abnormality determination flag Fb is not set (i.e., Fb=0) (S172:NO), the process proceeds to S176.

In S173ofFIG. 13, the abnormality determiner855determines whether the first abnormality determination flag Fa is set. When it is determined that the first abnormality determination flag Fa is set (i.e., Fa=1) (S173:YES), the process proceeds to S177ofFIG. 11. When it is determined that the first abnormality determination flag Fa is not set (i.e., Fa=0) (S173:NO), the process proceeds to S174.

In S174, the abnormality determiner855determines whether (a) the main data value indicated by the first main signal D11of the first output signal Sd10that is transmitted from the first magnetic sensor50and (b) the main data value indicated by the second main signal D21of the second output signal Sd20that is transmitted from the second magnetic sensor60are matching.

When it is determined that the two main data values are matching (S174:YES), the process proceeds to S175.

When it is determined that the two main data values are mismatched (S175:NO), the process proceeds to S177ofFIG. 11.

In S175, the abnormality determiner855resets the second abnormality determination flag Fb noting that the second magnetic sensor60has recovered from an abnormal state (i.e., Fb=0). The process proceeds to S176ofFIG. 11after S175.

Returning the description toFIG. 11, in S176, the abnormality determiner855determines that the second magnetic sensor60is normal. The process proceeds to S178after S176.

In S177, it is determined that the abnormality determiner855determines that the second magnetic sensor60is abnormal, and the second abnormality determination flag Fb is set (i.e., Fb=1). The process proceeds to S178after S177.

The process of each of S178-S179is the same as the process of each of S130-S131inFIG. 9.

In the third embodiment as described above, the abnormality determiner855determines that, when (a) the first magnetic sensor50is determined as abnormal, (b) the first sub signal D12is not included in the first output signal Sd10that is transmitted from the first magnetic sensor50, (c) the second magnetic sensor60is not determined as abnormal, and (d) the main data value indicated by the first main signal D11of the first output signal Sd10that is transmitted from the first magnetic sensor50, and the main data value indicated by the second main signal D21of the second output signal Sd20that is transmitted from the second magnetic sensor60are matching, the first magnetic sensor50has recovered from an abnormal state, and is now normal.

In such manner, it is determinable that the first magnetic sensor50is normal, after recovery from an abnormal state.

Further, the abnormality determiner855determines that, when (a) the second magnetic sensor60is determined as abnormal, (b) the second sub signal D22is not included in the second output signal Sd20that is transmitted from the second magnetic sensor60, (c) the first magnetic sensor50is not determined as abnormal, and (d) the main data value indicated by the first main signal D11of the first output signal Sd10that is transmitted from the first magnetic sensor50, and the main data value indicated by the second main signal D21of the second output signal Sd20that is transmitted from the second magnetic sensor60are matching, the second magnetic sensor60has recovered from an abnormal state, and is now normal.

In such manner, it is determinable that the second magnetic sensor60is normal after recovery from an abnormal state.

Fourth Embodiment

The fourth embodiment of the present disclosure is shown inFIGS. 14-16. In the fourth embodiment, the process in the interface circuits555and655and the abnormality determination process in the ECU85are both different from the first embodiment. Hereafter, each process is described with reference to flowcharts shown inFIGS. 14-16.

The process ofFIG. 14of S181-S182is the same as the process ofFIG. 7of S101-S102.

In S183, the signal transmitter557generates and transmits the first output signal Sd10including the first main signal D11and a first flag signal D13. The first flag signal D13is a signal which shows that the first main detection value and the first sub detection value are mismatched. In order to distinguish the first flag signal D13from other signals, the pulse length of the first flag signal D13is set up to be different from the pulse length of other signals, for example.

The process of each of S191-S192inFIG. 15is the same as the process of each of S111-S112inFIG. 8.

In S193, the signal transmitter657generates and transmits the second output signal Sd20including the second main signal D21and a second flag signal D23. The second flag signal D23is a signal which shows that the second main detection value and the second sub detection value are mismatched. In order to distinguish the second flag signal D23from other signals, the pulse length of the second flag signal D23is set up to be different from the pulse length of other signals, for example.

The process of each of S201and S202inFIG. 16is the same as the process of each of S121and S122inFIG. 9.

In S203, the abnormality determiner855determines whether the first flag signal D13is included in the first output signal Sd10. When it is determined that the first flag signal D13is included in the first output signal Sd10(S203:YES), the process proceeds to S205. When it is determined that the first flag signal D13is not included in the first output signal Sd10(S203:NO), the process proceeds to S204.

The process of each of S204-S206is the same as the process of each of S124-S126inFIG. 9.

In S207, the abnormality determiner855determines whether the second flag signal D23is included in the second output signal Sd20. When it is determined that the second flag signal D23is included in the second output signal Sd20(S207:YES), the process proceeds to S209. When it is determined that the second flag signal D23is not included in the second output signal Sd20(S207:NO), the process proceeds to S208.

The process of each of S208-S211is the same as the process of each of S128-S131inFIG. 9.

In the fourth embodiment described above, the ECU85may determine the abnormality of the magnetic sensors50and60based on whether the flag signals D13and D23exist, i.e., included, in the signals Sd10, Sd20.

Further, the flag signals D13and D23can make the data size smaller than the sub signals D12and D22. Therefore, when transmitting the flag signals D13and D23as described in the fourth embodiment, the transmission time of the output signals Sd10and Sd20is reduced in comparison to the first embodiment that transmits the sub signals D12and D22.

Fifth Embodiment

The fifth embodiment of the present disclosure is shown inFIGS. 17-19. In the fifth embodiment, the process in the interface circuits555and655and the abnormality determination process in the ECU85are both different from the first embodiment. Hereafter, each process is described with reference to flowcharts inFIGS. 17-19.

The process of each of S221-S222inFIG. 17is the same as the process of each of S101-S102inFIG. 7.

In S223, the signal transmitter557does not transmit the first output signal Sd10. That is, transmission of the first output signal Sd10is stopped.

The process of each of S231-S232inFIG. 18is the same as the process of each of S111-S112inFIG. 8.

In S233, the signal transmitter657does not transmit the second output signal Sd20. That is, transmission of the second output signal Sd20is stopped.

The process of each of S241and S242inFIG. 19is the same as the process of each of S121and S122inFIG. 9.

In S243, the abnormality determiner855determines whether the first output signal Sd10has been obtained. When it is determined that the first output signal Sd10has been obtained (S243:YES), the process proceeds to S244. When it is determined that the first output signal Sd10has not been obtained (S243:NO), the process proceeds to S245.

The process of each of S244-S246is the same as the process of each of S124-S126inFIG. 9.

In S247, the abnormality determiner855determines whether the second output signal Sd20has been obtained. When it is determined that the second output signal Sd20has been obtained (S247:YES), the process proceeds to S248. When it is determined that the second output signal Sd20has not been obtained (S247:NO), the process proceeds to S249.

The process of each of S248-S251is the same as the process of each of S128-S131inFIG. 9.

In the fifth embodiment signal as described above, the signal transmitters557and657stops transmission of the output signals Sd10and Sd20when the main detection value and the sub detection value are not matching, i.e., when the abnormality of the sensor element is suspected, and the ECU85may determine the abnormality of the magnetic sensors50and60based on whether the output signals Sd10and Sd20have been obtained.

Other Embodiments

In other embodiments, while the abnormality of the magnetic sensor may be determined based on the existence of the flag signal as described in the fourth embodiment, the recovery of the magnetic sensor from the abnormal state may be determined at the same time as described in the third embodiment.

That is, the abnormality determiner may determine that one magnetic sensor is now normal after recovery from an abnormal state, when (a) it is determined that one magnetic sensor is abnormal, and (b) the flag signal is not included in the output signal that is transmitted from the one magnetic sensor, and (c) it is not determined that the other magnetic sensor is abnormal, and (d) the data value indicated by the main signal of the output signal that is transmitted from the one magnetic sensor and the data value indicated by the main signal of the output signal that is transmitted from the other magnetic sensor are matching.

In other embodiments, while the abnormality of the magnetic sensor may be determined based on whether the output signal has been obtained as described in the fifth embodiment, the recovery of the magnetic sensor from the abnormal state may be determined at the same time as described in the third embodiment.

That is, the abnormality determiner may determine that one magnetic sensor is now normal after recovery from an abnormal state, when (a) it is determined that one magnetic sensor is abnormal, (b) the signal obtainer obtains the output signal from the one magnetic sensor, (c) it is not determined that the other magnetic sensor is abnormal, and (d) the data value indicated by the main signal of the output signal that is transmitted from the one magnetic sensor, and the data value indicated by the main signal of the output signal that is transmitted from the other magnetic sensor are matching.

The communication error detection signal implemented as the CRC signal in the above-mentioned embodiments may also be implemented in other embodiments as any signal other than the CRC signal, as long as the signal is usable for detecting the communication error in the controller. Further, the output signal does not need to include the communication error detection signal.

Further, in other embodiments, the output signal may include information on an update counter which is updated every time the output signal is transmitted. The information regarding the update counter may be, for example, included in the status signal. By transmitting the information regarding the update counter, it is determinable whether the same data transmitted twice is caused by (a) the two same detection results or (b) due to a data adhesion error.

The first main signal, the first sub signal, the second main signal, and the second sub signal represented by the nibble in the above-mentioned embodiments may also be represented by any form other than the nibble in other embodiments.

The output signal transmitted to the controller by the SENT communication method in the above-mentioned embodiments may also be transmitted to the controller by any method other than the SENT method, as long as the communication method is capable of including, in the output signal, the data signals respectively corresponding to the plural detection values.

In other embodiments, the first output signal and the second output signal may be simultaneously transmitted or may be transmitted one by one, i.e., at the same transmission timing or at the different transmission timings. For example, the transmission timing of the first output signal may be shifted by half signal cycle from the transmission timing of the second output signal, thereby enabling the controller to receive the output signals at every half signal cycle, which improves the communication speed in appearance.

The sensor element implemented as the Hall element in the above-mentioned embodiments may also be implemented in other embodiments as any magnetism detecting elements other than the Hall element, or may also be implemented as the elements which detect a change of physical quantity other than magnetism.

The sensor section serving as a torque sensor detecting a steering torque in the above-mentioned embodiments, may also be serving as a sensor other than the torque sensor, e.g., a pressure sensor detecting a pressure in other embodiments, for example. That is, the physical quantity calculated in the calculator may be a torque other than the steering torque, and may be a physical quantity other than the torque in other embodiments.

The sensing object described as the magnetic flux collection module in the above-mentioned embodiments may also be any matter other than the magnetic flux collection module in other embodiments.

The controller performing the abnormality determination of the second magnetic sensor after the abnormality determination of the first magnetic sensor in the above-mentioned embodiment may also perform, in other embodiments, the abnormality determination of the first magnetic sensor after the abnormality determination of the second magnetic sensor, or the abnormality determination of two or more magnetic sensors may be performed in parallel.

The sensor device applied to the electric power steering apparatus in the above-mentioned embodiments may also be applied to other in-vehicle devices other than the electric power steering apparatus in other embodiments, or may also be applied to other devices which are not disposed in a vehicle.

Although the present disclosure has been described in connection with preferred embodiment thereof with reference to the accompanying drawings, it is to be noted that various changes and modifications will become apparent to those skilled in the art, and such changes, modifications, and summarized scheme are to be understood as is within the scope of the present disclosure as defined by appended claims.