Patent Application
20250164285
The present disclosure relates to a sensor device.
Conventional sensor devices detect an angle of rotation of motors.
According to at least one embodiment, a sensor device is capable of continuing to operate at least partially with electric power supplied from a battery during a period when a starting switch is turned off. The sensor device includes a sensor input processor that has a sensor element. This sensor element detects a change in a physical quantity in response to the movement of a detection target. An input processing circuit calculates sensor information according to the detected value of the sensor element. A memory is also included, which stores abnormality information. This abnormality information includes power failure information pertaining to a power failure in which electric power is not supplied from the battery during the period when the starting switch is turned off. Additionally, a voltage holding circuit is provided on a battery feed line, which supplies battery power to the sensor input processor without going through the starting switch. This circuit is capable of applying a voltage to the sensor input processor sufficient to retain at least data in the memory during a temporary voltage drop in the battery. The sensor input processor has an adjustment circuit configured to sequentially stop functions other than data retention in the memory based on a voltage of the voltage holding circuit when the voltage of the voltage holding circuit drops.
The details of one or more embodiments are set forth in the accompanying drawings and the description below. Other features and advantages will be apparent from the description and drawings, and from the claims.
To begin with, examples of relevant techniques will be described.
Conventional sensor devices detect an angle of rotation of motors and other devices. A sensor device according to a comparative example is applied to an electric power steering system and is capable of continuing to operate at least in part with power from a battery during periods when an ignition power is turned off.
In the sensor device of the comparative example, if a battery voltage drops due to a large electric current to a starter at engine startup, for example, when a battery life is approaching, the sensor device may not be able to continue operation. In contrast to the comparative example, according to a sensor device of the present disclosure, operation can at least partially continue when a battery voltage drops.
According to one aspect of the present disclosure, a sensor device is capable of continuing to operate at least partially with electric power supplied from a battery during a period when a starting switch is turned off. The sensor device includes a sensor input processor that has a sensor element. This sensor element detects a change in a physical quantity in response to the movement of a detection target. An input processing circuit calculates sensor information according to the detected value of the sensor element. A memory is also included, which stores abnormality information. This abnormality information includes power failure information pertaining to a power failure in which electric power is not supplied from the battery during the period when the starting switch is turned off. Additionally, a voltage holding circuit is provided on a battery feed line, which supplies battery power to the sensor input processor without going through the starting switch. This circuit is capable of applying a voltage to the sensor input processor sufficient to retain at least data in the memory during a temporary voltage drop in the battery. The sensor input processor has an adjustment circuit configured to sequentially stop functions other than data retention in the memory based on a voltage of the voltage holding circuit when the voltage of the voltage holding circuit drops.
As a result, the sensor device is capable of continuing to operate at least partially even when the battery voltage drops.
Hereinafter, a sensor device according to the present disclosure will be described with reference to the drawings. Hereinafter, in a plurality of embodiments, substantially the same components are denoted by the same reference signs, and the description thereof is omitted.
A first embodiment is shown in
The steering wheel 91 is connected to the steering shaft 92. A torque sensor 94 is provided on the steering shaft 92 to detect a steering torque. The pinion gear 96 is provided at an axial end of the steering shaft 92. The pinion gear 96 meshes with the rack shaft 97. A pair of wheels 98 is coupled to both ends of the rack shaft 97 via, for example, tie rods.
When a driver of a vehicle rotates the steering wheel 91, the steering shaft 92 connected to the steering wheel 91 rotates. A rotational movement of the steering shaft 92 is converted to a linear movement of the rack shaft 97 by the pinion gear 96. The pair of wheels 98 is steered to an angle corresponding to a displacement amount of the rack shaft 97.
The electric power steering apparatus 8 includes a drive device 10 having an ECU 20 and a motor 80, a reduction gear 89 which is a power transmission unit that reduces rotation of the motor 80, and transmits the reduced rotation to the steering shaft 92. That is, the electric power steering apparatus 8 of the present embodiment is a column assist type, in which the steering shaft 92 is an object to be driven. The electric power steering apparatus 8 may be a rack assist type, in which the rotation of the motor 80 is transmitted to the rack shaft 97.
The motor 80 outputs part or all of a torque required for steering, and is driven by a power supplied from a battery 99 (see
As shown in
The sensor device 1 has a sensor input processor 30, a controller 40, and a power storage circuit 51. The sensor input processor 30 has a sensor element 31, an input processing circuit 32, an abnormality diagnosis circuit 33, a power determination circuit 34, a memory circuit 35, a communication circuit 36, a voltage monitor circuit 37, and a power consumption adjustment circuit 38.
The sensor device 1 has a first power supply terminal 301 (Vs) connected to the battery terminal 21 and a second power supply terminal 302 (Vcc) connected to the ignition terminal 25. The sensor device 1 of the present embodiment is configured to continue at least some operations, including counting the number TC of rotations of the motor 80, with power supplied from the battery 99 via the first power supply terminal 301 even when the IG is off.
A voltage generated from a voltage supplied from the battery terminal 21 and supplied to the first power supply terminal 301 is referred to as a sensor power supply voltage Vs, and a voltage generated from a voltage supplied from the ignition terminal 25 and supplied to the second power supply terminal 302 as a Vcc voltage. A wire connecting the battery terminal 21 to the first power supply terminal 301 is a battery feed line Lb, and a wire connecting the ignition terminal 25 to the second power supply terminal 302 is an ignition feed line Lig. A stabilized power supply circuit 61 for sensors, such as a regulator, is provided on the battery feed line Lb, and a stabilized power supply circuit 62 for control is provided on the ignition feed line Lig.
The sensor element 31 is, for example, a magnetic resistance element such as an AMR sensor, a TMR sensor, a GMR sensor, or a Hall element, and detect a magnetic field of a sensor magnet (not shown) that rotates integrally with a shaft of the motor 80, and outputs the detection signal to the input processing circuit 32. In the present embodiment, a plurality of sensor elements 31 are provided.
The input processing circuit 32 calculates a motor rotation angle Om and the number TC of rotations (rotation count TC) of the motor 80 based on the detected values of the sensor element 31. An element used to calculate the motor rotation angle Om and an element used to calculate the rotation count TC may be separated, or the detected values of at least some elements may be shared for the calculation of the motor rotation angle Om and the rotation count TC. The calculation results are stored in the memory circuit 35. The number of rotations TC can be calculated based on a count value, for example, by dividing one rotation of the motor 80 into three or more regions and counting up or down according to a rotation direction each time the region changes. The rotation count TC is used to calculate an absolute angle θa, which is an amount of rotation from a reference position including multiple rotation information. The absolute angle θa is a value that can be converted into a steering angle θs using a gear ratio or the like.
The abnormality diagnosis circuit 33 diagnoses abnormalities in the input processing circuit 32. The abnormality diagnosis results are stored in the memory circuit 35. The power determination circuit 34 determines a power failure in which the electric power supplied directly from the battery 99 via the first power supply terminal 301 is disrupted.
The memory circuit 35 stores information to be sent to the controller 40, such as the motor rotation angle θm, the rotation count TC, the abnormality diagnosis results, and information pertaining to the power failure. A memory area that stores each piece of information can be made redundant as two or more bits to enable anomaly detection by comparison or majority vote. It may also comprise a cyclic redundancy code (CRC), an error correction code (ECC) or an error detection code (EDC). As a result, reliability can be improved and products that require high functional safety can be used.
The communication circuit 36 transmits the motor rotation angle Om, the rotation count TC, the abnormality diagnosis results, and information pertaining to the power failure to the controller 40. The communication circuit 36 also receives various information from the controller 40. When the IG is turned on, the communication circuit 36 transmits to the controller 40 the number of rotations TC during IG off, the results of the abnormality diagnosis, and power failure information in response to a request signal from the controller 40. When the return signal is received from the controller 40, the results of the abnormality diagnosis and information pertaining to the power failure in the memory circuit 35 are cleared. When there are multiple memory areas for storing the abnormality diagnosis results and the power failure information, the determination results of the abnormality diagnosis circuit 33 and the power determination circuit 34 may be stored in multiple areas of memory simultaneously and cleared at different times. For example, if there are two memory areas, after transmitting the power failure information in response to the request signal sent by the controller 40 when the IG is turned on, one memory area is cleared in response to the return signal sent when the controller 40 receives the power failure information, and the other memory area is cleared in response to the return signal sent at any time after cranking is completed, such as the sequence when the IG is turned off.
The voltage monitor circuit 37 monitors the voltage on the battery feed line Lb. In the present embodiment, a charge voltage Vcg between the power storage circuit 51 and the stabilized power supply circuit 61 for the sensors is monitored, but the sensor power supply voltage Vs or a battery terminal voltage may be monitored instead of the charge voltage Vcg. The power consumption adjustment circuit 38 adjusts power consumption within the sensor input processor 30 according to the charge voltage Vcg. Details will be described later.
The controller 40 is mainly composed of a microcomputer and the like, and internally includes, although not shown in the figure, a central processing device (i.e., CPU), a read only memory (i.e., ROM), a random access memory (i.e., RAM), an input-output (i.e., I/O), a bus line for connecting these components, and the like. Each process executed by the controller 40 may be a software process or may be a hardware process. The software process may be implemented by causing the CPU to execute a program. The program may be stored beforehand in a memory device such as a ROM, that is, in a computer-readable, non-transitory, tangible storage medium. The hardware process may be implemented by a special purpose electronic circuit.
The controller 40 performs various calculations related to drive control of the motor 80. The controller 40 also calculates the absolute angle θa using the motor rotation angle θm and the rotation count TC. In the present embodiment, at least one sensor element 31, the input processing circuit 32, and the memory circuit 35 are constantly powered so that the calculation of the rotation count TC continues during a period when the IG is turned off. Thereby, even if the motor 80 is rotated by steering the steering wheel 91 while the IG is turned off, the steering angle θs can be calculated without relearning the reference position. Since the value when the IG is on may be used as the motor rotation angle θm, there is no need to continue calculation by constant power supply.
When the battery 99 is nearing the end of its service life, the sensor input processor 30 may become inoperable if a battery voltage Vbat drops due to a large electric current flowing to a starter during engine startup. If detection of the rotation count TC is interrupted due to the voltage drop, the steering angle θs must be relearned, delaying the start of controls such as an electronic stability control (ESC) and automated driving that use the steering angle θs.
Therefore, in the present embodiment, the power storage circuit 51 is provided so that the sensor input processor 30 can be supplied with a guaranteed operating voltage during a voltage holding period even if the voltage drop occurs in the battery 99 due to driving a load 79 that has a large effect on the battery voltage Vbat, such as a starter motor. The voltage holding period is set according to a time span required for the voltage drop due to the starter drive to recover, for example.
As shown in
As in the reference example shown in
As shown in
In the present embodiment, the sensor input processor 30 has the power consumption adjustment circuit 38. The power consumption adjustment circuit 38 reduces the power consumption by stopping the power supply for each circuit block based on the charge voltage Vcg detected by the voltage monitor circuit 37. As a result, the capacitance required for the capacitor 511 is reduced.
A suppressing process of the power consumption of the present embodiment will be described with reference to a flowchart of
In S101, the power consumption adjustment circuit 38 determines whether the charge voltage Vcg is 3.0 [V] or higher. When it is determined that the charge voltage Vcg is less than 3.0 [V] (S101: NO), the process proceeds to S102 to stop the power failure determination and a write circuit to the memory circuit 35. Since a minimum guaranteed operating voltage of the memory circuit 35 is less than 3.0 [V] (for example, 2.0 [V]), new writing to the memory circuit 35 is stopped, but the information already written is retained. When it is determined that the charge voltage Vcg is 3.0 [V] or more (S101: YES), the process proceeds to S103. In S103, it determines the power failure and allows the write circuit to operate on the memory circuit 35.
In S104, the power consumption adjustment circuit 38 determines whether the charge voltage Vcg is 4.3 [V] or higher. When it is determined that the charge voltage Vcg is less than 4.3 [V] (S104: NO), the process proceeds to S105 to stop the sensor element 31 and the input processing circuit 32. When it is determined that the charge voltage Vcg is 4.3 [V] or higher (S104: YES), the process proceeds to S106. In S106, the power consumption adjustment circuit 38 allow operation of the sensor element 31 and the input processing circuit 32.
In S107, the power consumption adjustment circuit 38 determines whether the charge voltage Vcg is 5.5 [V] or higher. When it is determined that the charge voltage Vcg is less than 5.5 [V] (S107: NO), the process proceeds to S108 and stops the communication circuit 36. When it is determined that the charge voltage is 5.5 [V] or higher (S107: YES), the process proceeds to S109 to allow the communication circuit 36 to operate.
In S110, the power consumption adjustment circuit 38 determines whether the charge voltage Vcg is 8.0 [V] or higher. When it is determined that the charge voltage Vcg is less than 8.0 [V] (S110: NO), the process proceeds to S111 to stop the abnormality diagnosis circuit 33. When it is determined that the charge voltage Veg is 8.0 [V] or higher (S110: YES), the process proceeds to S112 and allows the operation of the abnormality diagnosis circuit 33.
In the present embodiment, the minimum operating voltage to be operated for each function is determined from the functional aspect, and the operation is stopped according to the charge voltage Vcg. The determination thresholds of S101, S104, S107, and S110 in
As described above, the sensor device 1 of the present embodiment is able to continue to operate at least partially with the electric power supplied from the battery 99 during the period when the starting switch 26 is turned off. The sensor device 1 includes the sensor input processor 30 and the power storage circuit 51.
The sensor input processor 30 has the sensor element 31, the input processing circuit 32, and the memory circuit 35. The sensor element 31 detects the change in physical quantity in response to the operation of the motor 80. The input processing circuit 32 calculates the motor rotation angle Om and the rotation count TC as sensor information according to the detection value of the sensor element 31. The memory circuit 35 stores abnormality information, including the power failure information pertaining to the power failure in which the electric power is not supplied from the battery 99 while the starting switch 26 is off, and the results of the sensor input calculation processing.
The power storage circuit 51 is provided on the battery feed line Lb that supplies the electric power from the battery 99 to the sensor input processor 30 without going through the starting switch 26, and can apply the voltage to the sensor input processor 30 that can hold at least the data of the memory circuit 35 during a temporary voltage drop of the battery 99. In detail, by providing the power storage circuit 51, even when the voltage of the battery 99 drops, the voltage that can hold the data in the memory circuit 35 is maintained for the voltage holding period which is set according to the cranking period. As a result, the sensor processing circuit results, the abnormality diagnosis results, and the power failure information during IG off can be retained even when the battery voltage Vbat is temporarily low due to the cranking.
The power storage circuit 51 has the capacitor 511 that is connected to the battery feed line Lb. The electric power stored in the capacitor 511 can be used to properly maintain the sensor power supply voltage Vs when the battery voltage Vbat drops.
The sensor input processor 30 has the power consumption adjustment circuit 38 that sequentially stops functions other than data retention in the memory circuit 35 according to the charge voltage Vcg when the charge voltage Vcg, the voltage of the power storage circuit 51, drops. As a result, a time during which the sensor power supply voltage Vs can be held at or above the guaranteed operating voltage is lengthened. The capacity of the power storage circuit 51 (specifically capacitor 511) can also be lowered.
A second embodiment will be described with reference to
A suppressing process of the power consumption of the present embodiment will be described with reference to a flowchart of
In S126, the power consumption adjustment circuit 38 determines whether the charge voltage Vcg is 5.5 [V] or higher. When it is determined that the charge voltage Vcg is less than 5.5 [V] (S126: NO), the process proceeds to S127, and when it is determined that the charge voltage Vcg is 5.5 [V] or more (S126: YES), the process proceeds to S129.
In S127, which is shifted to when the charge voltage Vcg is greater than 4.3 [V] and less than 5.5 [V], the power consumption adjustment circuit 38 sets the sensor element 31 and the input processing circuit 32 to intermittent operation. The intermittent operation means, for example, that a circuit that normally operates at 100 μs is designed to operate at 1 ms. In S128, which is shifted to when the charge voltage Vcg is less than 5.5 [V], the power consumption adjustment circuit 38 stops the communication circuit 36.
In S129, which is shifted to when the charge voltage Vcg is determined to be 5.5 [V] or higher (S126: YES), the communication circuit 36 is allowed to operate, and the sensor element 31 and the input processing circuit 32 are set to normal operation (operation at 100 μs in the example above). The processing of S130 to S132 is the same as the processing of S110 to S112 in
In the present embodiment, the sensor element 31 and the input processing circuit 32 are operated intermittently in a predetermined voltage range (for example, between 4.3 [V] and 5.5 [V]) above the minimum operating voltage for detection operation, which stops the operation of the sensor element 31 and the input processing circuit 32 with relatively high power consumption. By reducing the frequency of operation of the sensor element 31 and the input processing circuit 32, the power consumption can be further reduced when the battery voltage is low. In addition, the same effects as those of the above embodiments are exerted.
A third embodiment will be described with reference to
The suppressing process of the power consumption based on the sensor power supply voltage Vs is explained based on the flowchart in
In S154, the power consumption adjustment circuit 38 determines whether the sensor power supply voltage Vs is 2.5 [V] or higher. When it is determined that the sensor power supply voltage is less than 2.5 [V] (S154: NO), the process proceeds to S155, and when it is determined that the sensor power supply voltage Vs is 2.5 [V] or more (S154: YES), the process proceeds to S156. Processes of S155, S156 are similar to the processes of S105, S106 in
In S157, the power consumption adjustment circuit 38 determines whether the sensor power supply voltage Vs is 3.0 [V] or higher. When it is determined that the sensor power supply voltage Vs is less than 3.0 [V] (S157: NO), the process proceeds to S158 to stop the communication circuit 36 and the abnormality diagnosis circuit 33. When it is determined that the sensor power supply voltage Vs is 3.0 [V] or higher (S157: YES), the process proceeds to S159 to allow the communication circuit 36 and the abnormality diagnosis circuit 33 to operate.
In the present embodiment, the sensor power supply voltage Vs is monitored instead of the charge voltage Vcg, and the power consumption adjustment circuit 38 sequentially stops functions other than data retention in the memory circuit 35 according to the sensor power supply voltage Vs. The same effects as those of the above embodiments can be obtained even in the configuration described above.
A fourth embodiment is illustrated in
The diodes 523, 524 are both installed so that the anode is connected to the battery and the cathode is connected to the sensor power supply. A diode 523 of the diodes 523, 524 is provided between the battery terminal 21 and the secondary battery 521, and the diode 524 of the diodes 523, 524 is provided between the secondary battery 521 and the stabilized power supply circuit 61 for the sensors.
When the battery voltage Vbat is sufficiently high, the electric power is supplied to the sensor input processor 30 via a wire La connecting the cathode of diodes 523, 524. On the other hand, when the battery voltage Vbat drops, the electric power from the secondary battery 521 is supplied to the sensor input processor 30 via the diode 524.
As shown in
In the present embodiment, the power storage circuit 52 has the secondary battery 521 that is connected to the battery feed line Lb. As a result, the sensor power supply voltage Vs can be properly maintained by using the electric power from the secondary battery 521 when the battery voltage Vbat drops. In addition, the same effects as those of the above embodiments are exerted.
A fifth embodiment is shown in
A sixth embodiment is shown in
As shown in
The booster circuit 53 may be replaced by a booster circuit 54 with a charge pump configuration shown in
The battery voltage Vbat does not actually drop to 0 [V], but remains around 2 [V] when the voltage of the battery 99 drops due to driving a load 79 such as a motor that consumes a large amount of power, such as a starter. Therefore, in the present embodiment, the remaining power of the battery 99 is utilized by providing the booster circuits 53, 54. A type of booster circuit can be other than those shown in the booster circuits 53,54.
As shown in
In the present embodiment, the booster circuits 53, 54 are provided on the battery feed line Lb as voltage holding circuits. As a result, the sensor power supply voltage Vs can be properly maintained even when the battery voltage Vbat drops. In addition, the same effects as those of the above embodiments are exerted.
In the embodiment, the memory circuit 35 corresponds to a “storage unit”, the power storage circuits 51, 52 and the booster circuits 53, 54 correspond to a “voltage holding circuit,” and the motor 80 corresponds to a “detection object”. The motor rotation angle Om and the rotation count TC of the motor 80 correspond to “sensor information”.
In the above embodiment, the stabilized power supply circuit for the sensors is located outside the sensor input processor. In other embodiments, a stabilized power supply circuit for the sensors may be provided within the sensor input processor. The same is true for the booster circuit of the fourth embodiment. In addition, in the sensor input processor, components other than inductors and capacitors, which are difficult to integrate into ICs, can be integrated into a single IC and packaged together in a single package, thereby enabling miniaturization.
In the above embodiment, the voltage monitor circuit or the control unit monitors the charge voltage or the boost voltage, and the power consumption adjustment circuit performs the suppressing process according to the voltage. In other embodiments, the power consumption adjustment circuit may be omitted and the voltage-based suppressing process may not be performed, especially when a booster circuit is provided.
In the above embodiments, the sensor device detects the rotation of the motor. In other embodiments, the sensor device may be something other than a motor rotation angle sensor, such as a torque sensor or a steering sensor. In the above embodiments, one control unit is provided for one sensor input processor. Other embodiments may have multiple controllers for one sensor input processor, or multiple sensor input processors for one controller.
In the above-described embodiments, the motor is a three-phase brushless motor. In other embodiments, the motor is not limited to the three-phase brushless motor, and any motor may be used. Further, the motor may also be a motor generator, or may be a motor-generator having both of a motor function and a generator function, i.e., not necessarily be limited to the rotating electric machine. In the above embodiment, the sensor device is applied to the electric power steering apparatus. In one or more other embodiments, the sensor device may be applied to other apparatuses different from the electric power steering apparatus.
The control circuit and method described in the present disclosure may be implemented by a special purpose computer which is configured with a memory and a processor programmed to execute one or more particular functions embodied in computer programs of the memory. Alternatively, the controller described in the present disclosure and the method thereof may be implemented by a dedicated computer configured as a processor with one or more dedicated hardware logic circuits. Alternatively, the controller and method described in the present disclosure may be implemented using one or more dedicated computers, which include a combination of a processor consisting of one or more hardware logic circuits, and a processor and memory programmed to perform one or more functions. The computer programs may be stored, as instructions to be executed by a computer, in a tangible non-transitory computer-readable medium. The present disclosure is not limited to the embodiment described above but various modifications may be made within the scope of the present disclosure.
While the present disclosure has been described with reference to embodiments thereof, it is to be understood that the disclosure is not limited to the embodiments and constructions. To the contrary, the present disclosure is intended to cover various modification and equivalent arrangements. In addition, while the various elements are shown in various combinations and configurations, which are exemplary, other combinations and configurations, including more, less or only a single element, are also within the spirit and scope of the present disclosure.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2022-117824 | Jul 2022 | JP | national |
The present application is a continuation application of International Patent Application No. PCT/JP2023/026029 filed on Jul. 14, 2023, which designated the U.S. and claims the benefit of priority from Japanese Patent Application No. 2022-117824 filed on Jul. 25, 2022. The entire disclosures of all of the above applications are incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/JP2023/026029 | Jul 2023 | WO |
| Child | 19035414 | US |
