Encoder and motor

Abstract

This encoder is provided to a motor and comprises: an encoder-use thermistor resistor for detecting an encoder temperature; a temperature detection processing unit that detects the encoder temperature on the basis of a resistance value of the encoder-user thermistor resistor, and detects a motor temperature on the basis of a resistance value of a motor-use thermistor resistor, which is provided to the motor and which is for detecting the motor temperature; and an abnormality detection unit that, on the basis of the magnitude relationship between the motor temperature and the encoder temperature detected by the temperature detection processing unit, detects an abnormality of the encoder-use thermistor resistor and the motor-use thermistor resistor.

Description

Encoder and motor

[0001] The present invention relates to an encoder and a motor.

[0002] Encoders are used to detect rotational information such as the rotational position and rotational speed of rotating bodies, such as motors installed in machine tools and robots, and objects connected to the motors. Motors generate heat when they are driven to rotate. Excessive heat generation can cause thermal demagnetization of the magnets inside the motor and burn out the windings inside the motor. The encoder attached to the rotating body (the heat source), the motor, also generates heat, and excessive heat can damage the encoder. For this reason, the motor and encoder are each equipped with a thermistor resistor, and information about the motor temperature and encoder temperature is obtained by a temperature detection device via the thermistor resistor. Various measures to deal with excessive heat generation are implemented based on this temperature information.

[0003] For example, a known drive control device for a DC servo motor includes an encoder connected to the DC servo motor and motor temperature detection means for detecting the temperature of the DC servo motor, and a drive unit is configured to control the rotational drive of the DC servo motor based on a drive control signal input from a control unit, and is configured to suspend the rotational drive control of the DC servo motor for a set motor cooling time if it is determined that the detected motor temperature is equal to or higher than a set motor temperature.The drive control device for a DC servo motor is characterized by comprising: encoder temperature detection means for detecting the actual temperature of the encoder; encoder temperature setting and storage means for setting and storing the encoder temperature to be monitored; encoder cooling time setting and storage means for setting and storing the encoder cooling time; second determination means for comparing the detected encoder temperature with the set encoder temperature to determine whether the detected encoder temperature is equal to or higher than the set encoder temperature; and encoder protection and suspension control means for suspending the rotational drive control of the DC servo motor for the encoder cooling time if it is determined that the detected encoder temperature is equal to or higher than the set encoder temperature (see, for example, Patent Document 1).

[0004] For example, a shift range control device (7) that controls a motor (2) connected to a shift range switching mechanism (5) to switch a vehicle's shift range includes a temperature detection unit (81) that detects an actual temperature (Tac) of the shift range control device, a temperature estimation unit (82) that calculates an estimated temperature (Tes) of the shift range control device, an abnormality determination unit (83) that determines whether or not there are signs of abnormality in the temperature detection unit, and a switching prohibition unit (84) that prohibits shift range switching if there are no signs of abnormality in the temperature detection unit and the actual temperature is equal to or higher than a predetermined switching prohibition threshold (Tth1), and also prohibits shift range switching if there are signs of abnormality in the temperature detection unit and the estimated temperature is equal to or higher than the switching prohibition threshold, and a shift range control device is known in which the period during which it is determined that there are no signs of abnormality in the temperature detection unit is defined as a normal period, and the temperature estimation unit calculates the estimated temperature based on the most recent actual temperature during the normal period (see, for example, Patent Document 2).

[0005] For example, a servo control device is known that uses a photoencoder to detect variations in the controlled object, and is characterized by having a means for controlling the motor drive current in accordance with the output level of the photoencoder (see, for example, Patent Document 3).

[0006] For example, a temperature detection device is known that includes a thermistor attached to a heat source, an interface that converts the resistance value of the thermistor into a voltage value, a calculation means that calculates the voltage change rate of the output voltage from the interface when the output voltage from the interface is lower than a set voltage value, and a determination means that compares the voltage change rate calculated by the calculation means with a preset voltage change rate to determine whether the heat source is overheating or the thermistor is shorted (see, for example, Patent Document 4).

[0007] Japanese Patent Laid-Open No. 9-023680 Japanese Patent Laid-Open No. 2021-092293 Japanese Patent Laid-Open No. 58-069481 Japanese Utility Model Laid-Open No. 5-028946

[0008] Thermistor resistors for detecting motor temperature and those for detecting encoder temperature have a resistance value of ∞Ω when they are broken, making it easy to detect a break by monitoring the resistance value. However, if an abnormality occurs in the thermistor resistor that does not result in a break, the resistance value will not be ∞Ω, and the temperature detected by the temperature detection device will merely deviate from the actual temperature, preventing the operator from noticing the abnormality. The problem to be solved by this disclosure is to realize an encoder and motor that can more accurately detect an abnormality in thermistor resistors used for temperature detection.

[0009] According to one aspect of the present disclosure, an encoder provided in a motor includes an encoder thermistor resistor for detecting the encoder temperature, a temperature detection processing unit that detects the encoder temperature based on the resistance value of the encoder thermistor resistor and detects the motor temperature based on the resistance value of a motor thermistor resistor provided in the motor for detecting the motor temperature, and an abnormality detection unit that detects abnormalities in the encoder thermistor resistor and the motor thermistor resistor based on the magnitude relationship between the motor temperature detected by the temperature detection processing unit and the encoder temperature.

[0010] According to one aspect of the present disclosure, the motor includes a motor thermistor resistor for detecting the motor temperature, and the encoder attached to a rotating body consisting of the motor shaft or an object connected to the motor shaft, and detecting rotation information of the rotating body.

[0011] According to one aspect of the present disclosure, it is possible to realize an encoder and a motor that can more accurately detect an abnormality in thermistor resistance for temperature detection.

[0012] FIG. 1 is a diagram showing an encoder and a motor including the same according to a first embodiment of the present disclosure. FIG. 2 is a diagram showing a voltage conversion circuit in a temperature detection processing unit in the first and second embodiments of the present disclosure. FIG. 3 is a flowchart showing an operation flow of abnormality detection processing in an encoder and a motor including the same according to the first embodiment of the present disclosure. FIG. 4 is a diagram showing a specific example of abnormality determination processing in the first embodiment of the present disclosure. FIG. 5 is a diagram showing an encoder and a motor including the same according to a second embodiment of the present disclosure. FIG. 6 is a flowchart showing an operation flow of abnormality detection processing in an encoder and a motor including the same according to the second embodiment of the present disclosure. FIG. 7 is a diagram showing a specific example of abnormality determination processing in the second embodiment of the present disclosure.

[0013] The encoder and motor of the embodiment will be described below with reference to the drawings. In the following description, components having the same or similar functions will be assigned the same reference numerals. Duplicate descriptions of those components may be omitted. In the following description, "connected" means "electrically connected."

[0014] First Embodiment FIG. 1 is a diagram showing an encoder and a motor including the encoder according to a first embodiment of the present disclosure.

[0015] According to the first embodiment of the present disclosure, the motor 2 includes a motor thermistor resistor 21 and an encoder 1 .

[0016] The motor thermistor resistor 21 is used to detect the temperature of the motor 2 (hereinafter referred to as "motor temperature"). The motor thermistor resistor 21 is a resistor whose resistance value between two electrode terminals changes in response to temperature changes. Examples of the motor thermistor resistor 21 include a PTC thermistor and an NTC thermistor. The motor thermistor resistor 21 may be installed near a portion of the motor 2 that is prone to heat generation, such as the iron core or windings. Alternatively, the motor thermistor resistor 21 may be installed near a cooling device installed near the motor 2 in order to check the operating status of the cooling device.

[0017] The encoder 1 is attached to the rotating shaft of the motor 2 (hereinafter referred to as the "motor shaft") or to a rotating body consisting of an object connected to the motor shaft. The encoder 1 detects rotational information such as the rotational position and rotational speed of the rotating body. The encoder 1 includes, for example, an optical or magnetic sensor unit attached to the rotating body such as the motor shaft, and a signal converter unit that converts an analog signal output from the sensor unit into a rectangular wave signal. Note that the motor shaft, the object connected to the motor shaft, the sensor unit, and the signal converter unit are not shown in FIG. 1.

[0018] The encoder 1 according to the first embodiment of the present disclosure includes an encoder thermistor resistor 11 , a temperature detection processing unit 12 , and an abnormality detection unit 13 .

[0019] The encoder thermistor resistor 11 is used to detect the temperature of the encoder 1 (hereinafter referred to as "encoder temperature"). The encoder thermistor resistor 11 is a resistor whose resistance value between two electrode terminals changes in response to temperature changes. Examples of the encoder thermistor resistor 11 include a PTC thermistor and an NTC thermistor. The encoder thermistor resistor 11 may be installed inside or on the surface of a housing (not shown) of the encoder 1, for example.

[0020] The temperature detection processing unit 12 is connected to the motor thermistor resistor 21 and the encoder thermistor resistor 11 via conductors. The temperature detection processing unit 12 detects the motor temperature based on the resistance value of the motor thermistor resistor 21. The temperature detection processing unit 12 also detects the encoder temperature based on the resistance value of the encoder thermistor resistor 11. As will be described in detail below, the temperature detection processing unit 12 has a voltage conversion circuit 31. The voltage conversion circuit 31 generates motor voltage data and encoder voltage data corresponding to changes in the resistance values ​​of the motor thermistor resistor 21 and the encoder thermistor resistor 11, respectively. The temperature detection processing unit 12 further generates motor temperature and encoder temperature based on the motor voltage data and encoder voltage data. The data related to the motor temperature and encoder temperature generated by the temperature detection processing unit 12 is sent to the abnormality detection unit 13.

[0021] The abnormality detection unit 13 detects an abnormality in the motor thermistor resistor 21 based on the magnitude relationship between the motor temperature and the encoder temperature detected by the temperature detection processing unit 12. The abnormality detection unit 13 has a temperature comparison circuit 32 to determine the magnitude relationship between the motor temperature and the encoder temperature.

[0022] Generally, the temperature of the encoder 1 is lower than the temperature of the motor 2, which is a heat source. Therefore, if the motor temperature is lower than the encoder temperature, it can be said that an abnormality has occurred in the motor thermistor resistor 21. Therefore, in the first embodiment of the present disclosure, the abnormality detection unit 13 determines that the motor thermistor resistor 21 is abnormal if the motor temperature detected by the temperature detection processing unit 12 is lower than the encoder temperature. Optionally, the abnormality detection unit 13 may also determine that the motor thermistor resistor 21 is abnormal if the motor temperature detected by the temperature detection processing unit 12 is higher than a predetermined temperature (e.g., 140°C). Optionally, the abnormality detection unit 13 may also determine that the encoder thermistor resistor 11 is abnormal if the encoder temperature detected by the temperature detection processing unit 12 is higher than a predetermined temperature (e.g., 100°C). The values ​​shown here are merely examples, and other values ​​may be used.

[0023] A signal indicating that the motor thermistor resistor 21 is abnormal is sent to, for example, an alarm output unit (not shown). When the alarm output unit receives a signal indicating that the motor thermistor resistor 21 is abnormal from the abnormality detection unit 13, it outputs an alarm signal. The alarm output unit is provided in a motor control device (not shown) that controls the drive of the motor 2, or in a host control device (not shown) of the motor control device. Examples of host control devices include a numerical control device or a robot controller. The output of the alarm signal can, for example, display the abnormality on a display, notify the abnormality with an audio device, or stop the motor control device. This allows an operator to quickly and reliably grasp the abnormality in the motor thermistor resistor 21. This makes it easy for the operator to take appropriate action, such as replacing or repairing the motor thermistor resistor 21.

[0024] An arithmetic processing unit (processor) is provided within the encoder 1. The arithmetic processing unit may be, for example, an IC, an LSI, a CPU, an MPU, or a DSP.

[0025] The abnormality detection unit 13 is configured with an arithmetic processing unit. For example, if the abnormality detection unit 13 is constructed in the form of a software program, the function of the abnormality detection unit 13 can be realized by operating the arithmetic processing unit in accordance with the software program. Alternatively, the abnormality detection unit 13 may be realized as a semiconductor integrated circuit onto which a software program that realizes the function of the abnormality detection unit 13 is written. Alternatively, the abnormality detection unit 13 may be realized as a recording medium onto which a software program that realizes the function of the abnormality detection unit 13 is written.

[0026] The temperature detection processing unit 12 is configured by combining an analog circuit, which is the voltage conversion circuit 31, with a processing unit, which is a temperature conversion circuit that converts voltage data into temperature data. For example, if the process of converting voltage data into temperature data in the temperature detection processing unit 12 is implemented in the form of a software program, the function can be realized by operating the processing unit in accordance with this software program. Alternatively, the temperature detection processing unit 12 may be realized as a semiconductor integrated circuit on which a software program that realizes the process of converting voltage data into temperature data in the temperature detection processing unit 12 is written. Alternatively, the temperature detection processing unit 12 may be realized as a recording medium on which a software program that realizes the process of converting voltage data into temperature data in the temperature detection processing unit 12 is written.

[0027] 2 is a diagram showing a voltage conversion circuit in a temperature detection processing unit according to the first and second embodiments of the present disclosure. The description of FIG. 2 applies not only to the first embodiment of the present disclosure but also to the second embodiment of the present disclosure.

[0028] The motor thermistor resistor 21 and the encoder thermistor resistor 11 in Fig. 1 and Fig. 5 (described later) are indicated as thermistor resistors 50 in Fig. 2. The thermistor resistor 50 is a resistor whose resistance value between two electrode terminals changes in response to temperature changes. Examples of the thermistor resistor 50 include a PTC thermistor and an NTC thermistor.

[0029] The voltage conversion circuit 31 includes a first voltage dividing resistor 41 , a second voltage dividing resistor 42 , an operational amplifier 43 , and an analog-to-digital conversion unit 44 .

[0030] The first voltage dividing resistor 41, the thermistor resistor 50, and the second voltage dividing resistor 42 are connected in series. A predetermined voltage V CC (For example, 5 V) is applied. Either the first voltage dividing resistor 41 or the thermistor resistor 50 may be omitted.

[0031] The two electrode terminals of the thermistor resistor 50 are connected to the non-inverting input (+) and the inverting input (−) of the operational amplifier 43. The potentials appearing at the two electrode terminals of the thermistor resistor 50 are input to the operational amplifier 43.

[0032] The operational amplifier 43, which is a differential amplifier circuit, extracts an analog signal relating to the voltage appearing between the two electrode terminals of the thermistor resistor 50 by taking the difference between the potentials appearing at the two electrode terminals of the thermistor resistor 50, and amplifies and outputs this to a signal level suitable for input to the analog-to-digital converter 44. The analog signal relating to the voltage output from the operational amplifier 43 is sent to the analog-to-digital converter 44.

[0033] The analog-to-digital converter 44 converts the input voltage data in analog signal format into voltage data in digital signal format and outputs it. When the temperature sensed by the thermistor resistor 50 changes, the resistance value between the two electrode terminals of the thermistor resistor 50 changes, and accordingly, the digital signal representing the voltage related to the thermistor resistor 50 output from the analog-to-digital converter 44 also changes. In this way, there is a one-to-one correspondence between the change in the resistance value of the thermistor resistor 50 and the change in the voltage value between the two electrode terminals of the thermistor resistor 50.

[0034] An arithmetic processing device (processor) serving as a temperature conversion circuit provided in the temperature detection processing unit 12 generates temperature-related data based on the voltage data output from the voltage conversion circuit 31. If the thermistor resistor 50 is an NTC thermistor, the resistance value decreases as the temperature increases. If the thermistor resistor 50 is a PTC thermistor, the resistance value increases sharply as the temperature increases, once the Curie temperature is reached. In the process of converting voltage data into temperature data in the temperature detection processing unit 12, temperature-related data is generated based on the voltage data output from the voltage conversion circuit 31 in accordance with the resistance-temperature characteristics of the NTC or PTC thermistor.

[0035] FIG. 3 is a flowchart showing an operation flow of an abnormality detection process in the encoder and the motor including the encoder according to the first embodiment of the present disclosure.

[0036] The abnormality detection process for the encoder 1 is executed regardless of whether the motor 2 provided with the encoder 1 is being rotated or driven.

[0037] In step S101, the temperature detection processing unit 12 detects the motor temperature based on the resistance value of the motor thermistor resistor 21. The temperature detection processing unit 12 also detects the encoder temperature based on the resistance value of the encoder thermistor resistor 11. The data relating to the motor temperature and the encoder temperature generated by the temperature detection processing unit 12 is sent to the abnormality detection unit 13.

[0038] In step S102, the abnormality detection unit 13 determines whether the motor temperature detected by the temperature detection processing unit 12 is lower than the encoder temperature.

[0039] If it is determined in step S102 that the motor temperature is lower than the encoder temperature, then in step S103 the abnormality detection unit 13 determines that the motor thermistor resistor 21 is abnormal. A signal indicating that the motor thermistor resistor 21 is abnormal is sent to the alarm output unit. In response to this, the alarm output unit outputs an alarm signal. The output of the alarm signal may result in, for example, displaying the abnormality on a display, announcing the abnormality through audio equipment, or stopping the motor control device. After step S103, the process ends.

[0040] If it is not determined in step S102 that the motor temperature is lower than the encoder temperature, then in step S104 the abnormality detection unit 13 determines that the motor thermistor resistor 21 is normal. After step S104, the process returns to step S101.

[0041] Steps S101 to S104 are repeatedly executed at a predetermined interval.

[0042] FIG. 4 is a diagram showing a specific example of the abnormality determination process in the first embodiment of the present disclosure. The numerical values ​​shown in FIG. 4 are merely an example. In FIG. 4, as an example, the motor thermistor resistor 21 and the encoder thermistor resistor 11 are NTC thermistors. The temperature displayed on a display unit (not shown) of a numerical control device of a machine tool equipped with the motor 2 is shown as the CNC display temperature. The CNC display temperature is visually confirmed by an operator via the display unit. As an example, the actual temperature of the motor 2 is set to 50°C, and the actual temperature of the encoder 1 is set to 25°C.

[0043] In state A, the resistance value of the motor thermistor resistor 21 is smaller than that of the encoder thermistor resistor 11, which is in line with the characteristics of the NTC thermistor. Also, the CNC display temperatures show the motor temperature at 50°C and the encoder temperature at 30°C, which are normal because they are close to the actual temperatures.

[0044] In state C, the motor thermistor resistor 21 is broken and its resistance value is ∞Ω. Because the motor thermistor resistor 21 is an NTC thermistor, the motor temperature indicated by the CNC temperature display will be, for example, 0°C. The operator can visually confirm from the CNC temperature displayed on the display unit that the motor temperature is showing 0°C, which is not possible, and can therefore understand that the motor thermistor resistor 21 has broken down due to a broken wire.

[0045] On the other hand, in state B, the motor temperature indicated by the CNC display temperature is 10°C. Because the motor temperature is lower than the encoder temperature, some kind of abnormality has occurred in the motor thermistor resistor 21. However, it is difficult for an operator to notice that there is an abnormality in the motor thermistor resistor 21 simply by visually checking that the motor temperature indicated by the CNC display temperature is 10°C. According to the first embodiment of the present disclosure, it is possible to detect an abnormality such as that in state B.

[0046] As described above, according to the first embodiment of the present disclosure, it is possible to more accurately detect an abnormality in the motor thermistor resistor 21 used to detect the motor temperature. According to the first embodiment of the present disclosure, it is possible to detect an abnormality in the motor thermistor resistor 21 that does not result in a disconnection. Furthermore, according to the first embodiment of the present disclosure, both the temperature detection process using the motor thermistor resistor 21 and the temperature detection process using the encoder thermistor resistor 11 are executed by the temperature detection processing unit 12 in the encoder 1. Therefore, the abnormality detection process by the abnormality detection unit 13 can be performed based on the comparison result between the motor temperature and the encoder temperature detected at the same time, thereby improving the accuracy of detecting an abnormality in the motor thermistor resistor 21. Furthermore, when an abnormality occurs in the motor thermistor resistor 21, the temperature detection processing unit 12 and the abnormality detection unit 13 in the encoder 1 can continue to be used simply by replacing the motor thermistor resistor 21, thereby improving maintainability.

[0047] Second Embodiment As described above, the temperature of the encoder 1 is generally lower than the temperature of the motor 2, which is a heat source. If the encoder thermistor resistor 11 is normal, the encoder temperature is lower than the motor temperature. However, if the encoder thermistor resistor 11 is abnormal, the encoder temperature may be higher than the motor temperature. Furthermore, if the encoder temperature is extremely lower than the motor temperature, there is a high possibility that the encoder thermistor resistor 11 is abnormal. Therefore, in a second embodiment of the present disclosure, a motor reference temperature is set based on the motor temperature detected by the temperature detection processing unit 12, and a threshold value is set that is a predetermined temperature lower than the motor reference temperature. If the encoder temperature detected by the temperature detection processing unit 12 is lower than the threshold value, the encoder thermistor resistor 11 is determined to be abnormal. Furthermore, if the encoder temperature detected by the temperature detection processing unit 12 is higher than the motor reference temperature, the encoder thermistor resistor 11 is also determined to be abnormal.

[0048] FIG. 5 is a diagram showing an encoder and a motor including the encoder according to a second embodiment of the present disclosure.

[0049] According to the second embodiment of the present disclosure, the motor 2 includes a motor thermistor resistor 21 and an encoder 1 .

[0050] The motor thermistor resistor 21 is as described in the first embodiment.

[0051] The encoder 1 is attached to a rotating body, which is the motor shaft of the motor 2 or an object connected to the motor shaft. The encoder 1 detects rotational information such as the rotational position and rotational speed of the rotating body. The encoder 1 includes, for example, an optical or magnetic sensor unit attached to the rotating body, such as the motor shaft, and a signal converter unit that converts an analog signal output from the sensor unit into a rectangular wave signal. Note that the motor shaft, the object connected to the motor shaft, the sensor unit, and the signal converter unit are not shown in FIG. 5.

[0052] The encoder 1 according to the second embodiment of the present disclosure includes an encoder thermistor resistor 11 , a temperature detection processing unit 12 , an abnormality detection unit 13 , a reference temperature setting unit 14 , and a threshold value setting unit 15 .

[0053] The encoder thermistor resistor 11 and the temperature detection processing unit 12 are as described in the first embodiment.

[0054] The data relating to the motor temperature generated by the temperature detection processing unit 12 is sent to the abnormality detection unit 13 and the reference temperature setting unit 14. The data relating to the encoder temperature generated by the temperature detection processing unit 12 is sent to the abnormality detection unit 13.

[0055] The reference temperature setting unit 14 sets the motor reference temperature based on the motor temperature detected by the temperature detection processing unit 12. The motor reference temperature may be set appropriately depending on the ambient temperatures of the encoder 1 and motor 2, the installation environment, the operation content, specifications, etc. For example, the motor reference temperature is set to the same value as the motor temperature detected by the temperature detection processing unit 12, or to a value several degrees Celsius to several tens of degrees Celsius lower than the motor temperature detected by the temperature detection processing unit 12 with a safety margin, but it may also be set to a value other than these. Data related to the motor reference temperature set by the reference temperature setting unit 14 is sent to the abnormality detection unit 13 and the threshold setting unit 15.

[0056] The threshold setting unit 15 sets a threshold lower than the motor reference temperature. The threshold may be set appropriately depending on the ambient temperature, installation environment, operation, specifications, etc. of the encoder 1 and motor 2. For example, the threshold is set to a value several tens of degrees Celsius or more lower than the motor reference temperature, but may also be set to a value other than this. Data related to the threshold set by the threshold setting unit 15 is sent to the abnormality detection unit 13. Furthermore, for example, when the motor thermistor resistor 21 and the encoder thermistor resistor 11 are PTC thermistors, it is preferable to set the threshold higher than when the motor thermistor resistor 21 and the encoder thermistor resistor 11 are NTC thermistors.

[0057] The abnormality detection unit 13 detects an abnormality in the motor thermistor resistor 11 based on the magnitude relationship between the motor temperature and the encoder temperature detected by the temperature detection processing unit 12. In particular, in the second embodiment of the present disclosure, the abnormality detection unit 13 determines that the encoder thermistor resistor 11 is abnormal if the encoder temperature detected by the temperature detection processing unit 12 is lower than a threshold value. Furthermore, the abnormality detection unit 13 determines that the encoder thermistor resistor 11 is abnormal if the encoder temperature detected by the temperature detection processing unit 12 is higher than a motor reference temperature. Optionally, the abnormality detection unit 13 may also determine that the motor thermistor resistor 21 is abnormal if the motor temperature detected by the temperature detection processing unit 12 is higher than a predetermined temperature (e.g., 140°C). The values ​​shown here are merely examples, and other values ​​may be used.

[0058] A signal indicating that the encoder thermistor resistor 11 is abnormal is sent to, for example, an alarm output unit (not shown). When the alarm output unit receives a signal indicating that the encoder thermistor resistor 11 is abnormal from the abnormality detection unit 13, it outputs an alarm signal. The alarm output unit is provided in a motor control device (not shown) that controls the drive of the motor 2, or in a host control device (not shown) of the motor control device. Examples of host control devices include a numerical control device and a robot controller. The output of the alarm signal can, for example, display the abnormality on a display, notify the abnormality with an audio device, or stop the motor control device. This allows an operator to quickly and reliably grasp the abnormality of the encoder thermistor resistor 11. This makes it easy for the operator to take action, such as replacing or repairing the encoder thermistor resistor 11.

[0059] An arithmetic processing unit (processor) is provided within the encoder 1. The arithmetic processing unit may be, for example, an IC, an LSI, a CPU, an MPU, or a DSP.

[0060] The anomaly detection unit 13, the reference temperature setting unit 14, and the threshold setting unit 15 are configured by an arithmetic processing device. For example, if the anomaly detection unit 13, the reference temperature setting unit 14, and the threshold setting unit 15 are configured in the form of a software program, the functions of the anomaly detection unit 13, the reference temperature setting unit 14, and the threshold setting unit 15 can be realized by operating the arithmetic processing device in accordance with the software program. Alternatively, the anomaly detection unit 13, the reference temperature setting unit 14, and the threshold setting unit 15 may be realized as a semiconductor integrated circuit on which a software program that realizes the functions of the anomaly detection unit 13, the reference temperature setting unit 14, and the threshold setting unit 15 is written. Alternatively, the anomaly detection unit 13, the reference temperature setting unit 14, and the threshold setting unit 15 may be realized as a recording medium on which a software program that realizes the functions of the anomaly detection unit 13, the reference temperature setting unit 14, and the threshold setting unit 15 is written.

[0061] FIG. 6 is a flowchart showing an operation flow of an abnormality detection process in an encoder and a motor including the encoder according to the second embodiment of the present disclosure.

[0062] The abnormality detection process for the encoder 1 is executed regardless of whether the motor 2 provided with the encoder 1 is being rotated or driven.

[0063] In step S201, the temperature detection processing unit 12 detects the motor temperature based on the resistance value of the motor thermistor resistor 21. The temperature detection processing unit 12 also detects the encoder temperature based on the resistance value of the encoder thermistor resistor 11. Data related to the motor temperature generated by the temperature detection processing unit 12 is sent to the abnormality detection unit 13 and the reference temperature setting unit 14. Data related to the encoder temperature generated by the temperature detection processing unit 12 is sent to the abnormality detection unit 13.

[0064] In step S202, the reference temperature setting unit 14 sets a motor reference temperature based on the motor temperature detected by the temperature detection processing unit 12. Data relating to the motor reference temperature set by the reference temperature setting unit 14 is sent to the abnormality detection unit 13 and the threshold setting unit 15.

[0065] In step S203, the threshold setting unit 15 sets a threshold lower than the reference motor temperature. Data relating to the threshold set by the threshold setting unit 15 is sent to the abnormality detection unit 13.

[0066] In step S204, the abnormality detection unit 13 determines whether the encoder temperature detected by the temperature detection processing unit 12 is lower than a threshold value.

[0067] If it is determined in step S204 that the encoder temperature is lower than the threshold value, the abnormality detection unit 13 determines in step S205 that the encoder thermistor resistor 11 is abnormal.

[0068] If it is not determined in step S204 that the encoder temperature is lower than the threshold value, in step S206, the abnormality detection unit 13 determines whether the encoder temperature detected by the temperature detection processing unit 12 is higher than the motor reference temperature.

[0069] If it is determined in step S206 that the encoder temperature is higher than the motor reference temperature, the abnormality detection unit 13 determines in step S205 that the encoder thermistor resistor 11 is abnormal.

[0070] If it is determined in step S205 that the motor thermistor resistor 21 is abnormal, a signal indicating that the encoder thermistor resistor 11 is abnormal is sent to the alarm output unit. In response to this, the alarm output unit outputs an alarm signal. The output of the alarm signal may result in, for example, displaying the abnormality on a display, announcing the abnormality through audio equipment, or stopping the motor control device. After step S205, the process ends.

[0071] If it is not determined in step S206 that the encoder temperature is higher than the motor reference temperature, then in step S207 the abnormality detection unit 13 determines that the motor thermistor resistor 21 is normal. After step S207, the process returns to step S201.

[0072] Steps S201 to S207 are repeatedly executed at a predetermined cycle. Note that the execution order of steps S204 and S206 may be reversed.

[0073] 7 is a diagram showing a specific example of the abnormality determination process according to the second embodiment of the present disclosure. The numerical values ​​shown in FIG. 7 are merely an example, and other values ​​may be used.

[0074] If the motor temperature detected by the temperature detection processing unit 12 is, for example, 80°C, the motor reference temperature is set to, for example, 80°C. Also, the threshold value is set to 30°C, which is, for example, 50°C lower than the motor reference temperature of 80°C. If the encoder temperature detected by the temperature detection processing unit 12 is in the range of 30°C to 80°C, the abnormality detection unit 13 determines that the encoder thermistor resistor 11 is normal. If the encoder temperature detected by the temperature detection processing unit 12 is higher than 80°C, the abnormality detection unit 13 determines that the encoder thermistor resistor 11 is abnormal. Also, if the encoder temperature detected by the temperature detection processing unit 12 is lower than 30°C, the abnormality detection unit 13 determines that the encoder thermistor resistor 11 is abnormal.

[0075] As described above, according to the second embodiment of the present disclosure, it is possible to more accurately detect an abnormality in the encoder thermistor resistor 11 used to detect the encoder temperature. According to the second embodiment of the present disclosure, it is possible to detect an abnormality in the encoder thermistor resistor 11 that does not result in a disconnection. Furthermore, according to the second embodiment of the present disclosure, both the temperature detection process using the motor thermistor resistor 21 and the temperature detection process using the encoder thermistor resistor 11 are executed by the temperature detection processing unit 12 in the encoder 1. Therefore, the abnormality detection process by the abnormality detection unit 13 can be performed based on the comparison result between the motor temperature and the encoder temperature detected at the same time, thereby improving the accuracy of detecting an abnormality in the encoder 1. Furthermore, when an abnormality occurs in the encoder thermistor resistor 11, the motor thermistor resistor 21 in the motor 2 can continue to be used simply by replacing the encoder 1, thereby improving maintainability.

[0076] Although the embodiments of the present disclosure have been described in detail, the present disclosure is not limited to the individual embodiments described above. Various additions, substitutions, modifications, partial deletions, etc. are possible in these embodiments without departing from the gist of the invention or the spirit of the present invention derived from the content of the claims and their equivalents. For example, in the above-described embodiments, the order of each operation and the order of each process are shown as examples and are not limited to these. The same applies when numerical values ​​or mathematical expressions are used in the description of the above-described embodiments.

[0077] REFERENCE SIGNS LIST 1 Encoder 2 Motor 11 Encoder thermistor resistor 12 Temperature detection processing unit 13 Abnormality detection unit 21 Motor thermistor resistor 31 Voltage conversion circuit 32 Temperature comparison circuit 41 First voltage dividing resistor 42 Second voltage dividing resistor 43 Operational amplifier 44 Analog-to-digital conversion unit 50 Thermistor resistor

Claims

1. An encoder provided to a motor, a thermistor resistor for detecting the temperature of the encoder; a temperature detection processing unit that detects an encoder temperature based on a resistance value of the encoder thermistor resistor, and detects a motor temperature based on a resistance value of a motor thermistor resistor that is provided in the motor and detects a motor temperature; an abnormality detection unit that detects an abnormality in the encoder thermistor resistor and the motor thermistor resistor based on a magnitude relationship between the motor temperature and the encoder temperature detected by the temperature detection processing unit; An encoder comprising:

2. 2 . The encoder according to claim 1 , wherein the abnormality detection section determines that the motor thermistor resistance is abnormal when the motor temperature detected by the temperature detection processing section is lower than the encoder temperature.

3. a reference temperature setting unit that sets a motor reference temperature based on the motor temperature detected by the temperature detection processing unit; a threshold setting unit that sets a threshold value that is lower than the motor reference temperature; Further equipped with 3. The encoder according to claim 1, wherein the abnormality detection section determines that the encoder thermistor resistor is abnormal when the encoder temperature detected by the temperature detection processing section is lower than the threshold value.

4. 4. The encoder according to claim 3, wherein the abnormality detection section determines that the encoder thermistor resistance is abnormal when the encoder temperature detected by the temperature detection processing section is higher than the motor reference temperature.

5. a motor thermistor resistor for detecting the motor temperature; The encoder according to claim 1 or 2, which is attached to a rotating body which is a motor shaft or an object connected to the motor shaft and detects rotation information of the rotating body; A motor comprising: