US20170023956A1 - Motor driving device and detection method for detecting malfunction in heat radiation performance of heatsink - Google Patents
Motor driving device and detection method for detecting malfunction in heat radiation performance of heatsink Download PDFInfo
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- US20170023956A1 US20170023956A1 US15/213,631 US201615213631A US2017023956A1 US 20170023956 A1 US20170023956 A1 US 20170023956A1 US 201615213631 A US201615213631 A US 201615213631A US 2017023956 A1 US2017023956 A1 US 2017023956A1
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- Prior art keywords
- change
- temperature
- driving device
- motor driving
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Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F28—HEAT EXCHANGE IN GENERAL
- F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
- F28F3/00—Plate-like or laminated elements; Assemblies of plate-like or laminated elements
- F28F3/02—Elements or assemblies thereof with means for increasing heat-transfer area, e.g. with fins, with recesses, with corrugations
-
- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05D—SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES
- G05D23/00—Control of temperature
- G05D23/19—Control of temperature characterised by the use of electric means
- G05D23/1919—Control of temperature characterised by the use of electric means characterised by the type of controller
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/40—Testing power supplies
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
- G01M99/00—Subject matter not provided for in other groups of this subclass
- G01M99/002—Thermal testing
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F28—HEAT EXCHANGE IN GENERAL
- F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
- F28F27/00—Control arrangements or safety devices specially adapted for heat-exchange or heat-transfer apparatus
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K7/00—Constructional details common to different types of electric apparatus
- H05K7/20—Modifications to facilitate cooling, ventilating, or heating
- H05K7/2039—Modifications to facilitate cooling, ventilating, or heating characterised by the heat transfer by conduction from the heat generating element to a dissipating body
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K7/00—Constructional details common to different types of electric apparatus
- H05K7/20—Modifications to facilitate cooling, ventilating, or heating
- H05K7/2089—Modifications to facilitate cooling, ventilating, or heating for power electronics, e.g. for inverters for controlling motor
- H05K7/20909—Forced ventilation, e.g. on heat dissipaters coupled to components
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K7/00—Constructional details common to different types of electric apparatus
- H05K7/20—Modifications to facilitate cooling, ventilating, or heating
- H05K7/2089—Modifications to facilitate cooling, ventilating, or heating for power electronics, e.g. for inverters for controlling motor
- H05K7/20945—Thermal management, e.g. inverter temperature control
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F28—HEAT EXCHANGE IN GENERAL
- F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
- F28F2200/00—Prediction; Simulation; Testing
Definitions
- the invention relates to a motor driving device for detecting abnormalities in the heat radiation performance of a heatsink, and a detection method.
- a heatsink and a fan for generating an air flow in the heatsink are attached to the electronic device. It has been known that, in such an electronic device, the thermal resistance of the heatsink is calculated from the temperature of the electronic device, and abnormalities in the performance of the heatsink are detected (see, for example, Japanese Unexamined Patent Publication (Kokai) No. 2009-130223).
- a motor driving device for driving a motor embedded in, for example, a machine tool can control electric power to be supplied to the motor so that the electric power greatly varies in a short period of time.
- the temperature of the motor driving device greatly varies in a short period of time.
- the temperature of the electronic device should be detected when remaining in a steady state.
- a motor driving device includes a heat generating element, a heatsink which cools the heat generating element, an electric power detecting part which detects a consumed power of the heat generating element, a temperature detecting part which detects a temperature of the motor driving device, and a temperature change calculating part which calculates an amount of change in the temperature within a predetermined time as a detected amount of change, based on the temperature detected by the temperature detecting part.
- the motor driving device includes a reference determination part which determines a reference amount of change in the temperature based on the temperature detected by the temperature detecting part and the consumed power detected by the electric power detecting part, and a temperature change judging part which compares the reference amount of change determined by the reference determination part with the detected amount of change calculated by the temperature change calculating part, and judges whether the detected amount of change is different from the reference amount of change.
- the temperature change judging part may judge that the detected amount of change is different from the reference amount of change when the detected amount of change is out of an allowable range predetermined so as to include the reference amount of change.
- the temperature change judging part may judge whether the detected amount of change is different from the reference amount of change when the consumed power is zero and the detected amount of change is a negative value.
- the motor driving device may include a fan which generates an air flow in the heatsink, a rotation number detecting part which detects a rotation number of the fan, and a rotation number judging part which judges whether the rotation number detected by the rotation number detecting part is different from a predetermined reference rotation number of the fan when the temperature change judging part judges that the detected amount of change is different from the reference amount of change.
- the motor driving device may further include a malfunction signal generating part which generates a signal indicating that a malfunction occurs in the performance of the heatsink when the temperature change judging part judges that the detected amount of change is different from the reference amount of change.
- the malfunction signal generating part may generate a signal indicating that a malfunction occurs in the performance of the heatsink when the temperature change judging part judges that the detected amount of change is different from the reference amount of change and the rotation number judging part judges that the rotation number is not different from the reference rotation number.
- the malfunction signal generating part may generate a signal indicating that a malfunction occurs in the operation of the fan when the temperature change judging part judges that the detected amount of change is different from the reference amount of change and the rotation number judging part judges that the rotation number is different from the reference rotation number
- the motor driving device may further include a steady state judging part which judges whether a temperature change of the motor driving device is in a steady state.
- the temperature change calculating part may calculate the detected amount of change when the steady state judging part judges that the temperature change of the motor driving device is not in a steady state.
- the steady state judging part judges that the temperature change of the motor driving device is in a steady state when the consumed power is constant for a predetermined period of time.
- the motor driving device may include a thermal resistance calculating part which calculates a thermal resistance of the motor driving device based on the consumed power and the temperature detected by the temperature detecting part when the steady state judging part judges that the temperature change of the motor driving device is in a steady state.
- the motor driving device may further include a thermal resistance judging part which judges whether the thermal resistance calculated by the thermal resistance calculating part is different from a predetermined reference thermal resistance.
- a method of detecting a malfunction in the heat radiation performance of a heatsink provided at a motor driving device includes detecting a consumed power of a heat generating element provided at the motor driving device, detecting a temperature of the motor driving device, and calculating an amount of change in the temperature within a predetermined time as a detected change, based on the detected temperature.
- the method includes determining a reference amount of change in the temperature based on the detected consumed power and the detected temperature, and comparing the determined reference amount of change with the calculated detected amount of change, and judging whether the detected amount of change is different from the reference amount of change.
- FIG. 1 is a perspective view of a motor driving device according to an embodiment of the invention
- FIG. 2 is a view of a heatsink assembly provided at the motor driving device shown in FIG. 1 ;
- FIG. 3 is a view of the heatsink assembly shown in FIG. 2 as seen from the direction indicated by arrow III in FIG. 2 ;
- FIG. 4 is a block diagram of the motor driving device shown in FIG. 1 ;
- FIG. 5 is a graph showing a relationship between the temperature of the motor driving device and time, and a relationship between the consumed power of the heat generating element and time, wherein the temperature is in a steady state;
- FIG. 6 is a graph showing a relationship between the temperature of the motor driving device and time, and a relationship between the consumed power of the heat generating element and time, wherein the temperature varies in a short period of time;
- FIG. 7 is a flowchart showing an example of a processing flow of the motor driving device shown in FIG. 4 ;
- FIG. 8 is a block diagram of a motor driving device according to another embodiment of the invention.
- FIG. 9 is a flowchart showing an example of a processing flow of the motor driving device shown in FIG. 8 ;
- FIG. 10 is a block diagram of a motor driving device according to still another embodiment of the invention.
- FIG. 11 is a flowchart showing an example of a processing flow of the motor driving device shown in FIG. 10 .
- the motor driving device 10 supplies electric power to a main motor (not shown) built in a machine tool, etc., in order to drive the main motor.
- the motor driving device 10 includes a housing 12 , a controller 14 , a heatsink assembly 16 , heat generating elements 24 , and a temperature detecting part 26 .
- the housing 12 is a box member made of e.g. a resin, and defines an inner space therein.
- the controller 14 includes e.g. a CPU, and is mounted in the inner space of the housing 12 .
- the controller 14 directly or indirectly controls each component of the motor driving device 10 .
- the heatsink assembly 16 is provided to be adjacent to the housing 12 . As shown in FIGS. 2 and 3 , the heatsink assembly 16 includes a heatsink 20 and a fan 22 .
- the heatsink 20 is a rectangular member having a longitudinal direction along the z-axis direction in the Cartesian coordinate system shown in FIGS. 2 and 3 .
- the heatsink 20 has a first end part 20 a in the z-axis direction and a second end part 20 b opposite the first end part 20 a.
- the heatsink 20 includes a plurality of heat radiation fins 28 .
- Each of the heat radiation fins 28 is a plate member having a predetermined length in the z-axis direction, a predetermined thickness in the y-axis direction, and a predetermined width in the x-axis direction.
- Each of the heat radiation fins 28 extends between the first end part 20 a and the second end part 20 b .
- the heat radiation fins 28 are arranged to align in the y-axis direction at substantially equal intervals.
- Flow paths 30 are each defined between two heat radiation fins 28 adjacent to each other in the y-axis direction. Each flow path 30 extends in the z-axis direction between the first end part 20 a and the second end part 20 b , and opens to the outside at the first end part 20 a and the second end part 20 b.
- the fan 22 is attached to the first end part 20 a of the heatsink 20 .
- the fan 22 includes a rotator (not shown) with a plurality of vanes, and a fan motor (not shown) which rotates the rotator.
- the fan motor rotates the rotator of the fan 22 in accordance with a command from the controller 14 .
- an air flow in e.g. the z-axis positive direction in FIG. 2 is generated in the flow paths 30 .
- outside air is flown into the openings of the flow paths 30 at the second end part 20 b , passes through the flow paths 30 in the z-axis positive direction, and is discharged from the openings of the flow paths 30 at the first end part 20 a .
- the heatsink 20 is cooled by the air flowing through the flow paths 30 as described above, thereby the motor driving device 10 is cooled.
- the heat generating elements 24 and the temperature detecting part 26 are disposed on an outer surface 20 c of the heatsink 20 .
- the heat generating elements 24 includes e.g. a power element, and generates electric power in accordance with a command from the controller 14 .
- the controller 14 supplies the electric power generated by the heat generating elements 24 to the main motor of e.g. a machine tool so as to drive the main motor.
- the temperature detecting part 26 includes a temperature sensor, and detects the temperature at a position at which the temperature detecting part 26 is disposed, in accordance with a command from the controller 14 .
- the temperature detecting part 26 sends data of the detected temperature to the controller 14 .
- the motor driving device 10 further includes an electric power detecting part 32 , a storage 34 , a timer 36 , and an alarm output part 38 .
- the electric power detecting part 32 detects the consumed power of the heat generating elements 24 , and sends data of the detected consumed power to the controller 14 .
- the electric power detecting part 32 is installed so as to detect the consumed power of one of the heat generating elements 24 .
- the electric power detecting part 32 may be installed so as to detect the consumed power of the whole of a power amplifier (not shown) comprised of a plurality of heat generating elements 24 .
- the storage 34 is comprised of e.g. a non-volatile memory which can electrically delete/record data, such as an EEPROM (trademark), or a random access memory which can rapidly read/write data, such as a DRAM, a SRAM, etc.
- a non-volatile memory which can electrically delete/record data
- EEPROM trademark
- random access memory which can rapidly read/write data, such as a DRAM, a SRAM, etc.
- the storage 34 is connected to the controller 14 so as to communicate with the controller 14 , and stores data received from the temperature detecting part 26 and the electric power detecting part 32 , and a reference amount of change that will be described later.
- the storage 34 may be built in the controller 14 , or may be built in an external device (e.g., a server) which is installed outside of the controller 14 and which is connected to the controller 14 so as to communicate with the controller 14 via a network.
- the timer 36 times an elapsed time from a predetermined time point in accordance with a command from the controller 14 .
- the alarm output part 38 includes e.g. a speaker or display, and outputs a sound wave or an image in accordance with a command from the controller 14 .
- the timer 36 may be built in the controller 14 , or in an external device installed outside of the controller 14 so as to be communicably connected to the controller.
- the motor driving device 10 detects whether a malfunction occurs in the heat radiation performance of the heatsink 20 , based on an amount of change in the temperature detected by the temperature detecting part 26 with respect to time.
- FIGS. 5 and 6 The concept of a method of detecting a malfunction in the heat radiation performance of the heatsink 20 of the motor driving device 10 will be described below with reference to FIGS. 5 and 6 .
- Each of the graphs in the upper sections of FIGS. 5 and 6 shows a relationship between temperature T detected by the temperature detecting part 26 and time t, while each of the graphs in the lower sections of FIGS. 5 and 6 shows a relationship between electric power P detected by the electric power detecting part 32 and time t.
- each of solid lines 42 and 46 in FIGS. 5 and 6 represents a characteristic in a case where foreign substances do not accumulate in the flow paths 30 of the heatsink 20 , and the heat radiation performance of the heatsink 20 is normal (hereinafter referred as “normal product”).
- each of dashed-dotted lines 40 and 44 in FIGS. 5 and 6 represents a characteristic in a case where foreign substances accumulate in the flow paths 30 of the heatsink 20 , thereby an air flow in the flow paths 30 are disturbed so that the heat radiation performance of the heatsink 20 is reduced (hereinafter referred as “malfunction product”).
- the temperature T also varies in a short period of time so as to follow the variation of the consumed power P, thereby does not shift to a steady state. In this case, it is not possible to accurately calculate the thermal resistance of the motor driving device 10 .
- the consumed power varies in a short period of time, and therefore the temperature T greatly varies in a short period of time as shown in the upper graph of FIG. 6 .
- the degree of decrease in the temperature with respect to time of the malfunction product i.e., dashed-dotted line 44
- that of the normal product i.e., solid line 46 .
- the gradient (or time-derivative coefficient) of the characteristic of the malfunction product when the temperature increases and when the temperature decreases is remarkably different from that of the normal product.
- the motor driving device 10 detects whether a malfunction occurs in the heat radiation performance of the heatsink 20 by comparing an amount of change in the temperature with respect to time of the normal product (a reference amount of change) with an amount of change in the temperature detected by the temperature detecting part 26 with respect to time (a detected amount of change).
- the processing flow shown in FIG. 7 is started when the controller 14 receives a motor drive command for driving the main motor built in a machine tool, etc., from e.g. a user or a host controller (e.g., a machine tool controller).
- a host controller e.g., a machine tool controller
- the controller 14 starts to time an elapsed time. Specifically, the controller 14 sends a timing start command to the timer 36 .
- the timer 36 times an elapsed time from the time point when it has received the timing starting command from the controller 14 .
- the controller 14 repeatedly executes a loop of steps S 2 to S 7 at a period ⁇ (e.g., one second) until it judges “YES” at step S 6 or S 8 .
- a period ⁇ e.g., one second
- the controller 14 detects a temperature T n of the motor driving device 10 . Specifically, the controller 14 transmits a command to the temperature detecting part 26 so as to detect a temperature at the position where the temperature detecting part 26 is disposed. The controller 14 records data of the temperature acquired from the temperature detecting part 26 onto the storage 34 .
- the controller 14 detects a consumed power P n of the heat generating elements 24 . Specifically, the controller 14 transmits a command to the electric power detecting part 32 so as to detect a consumed power of the heat generating elements 24 . The controller 14 records data of the consumed power acquired from the electric power detecting part 32 onto the storage 34 .
- the controller 14 functions as a temperature change calculating part 48 ( FIG. 4 ) which calculates the detected amount of change ( ⁇ T n , ⁇ T n / ⁇ t).
- the controller 14 determines a reference amount of change ⁇ T ref based on the temperature T n acquired at step S 2 and the consumed power P n acquired at step S 3 .
- the reference amount of change ⁇ T ref is a parameter corresponding to a degree of temperature change with respect to time of the normal product (solid line 46 ) in FIG. 6 .
- the reference amount of change ⁇ T ref is set as a parameter corresponding to a temperature change within the time ⁇ of the characteristic of the normal product in FIG. 6 .
- the reference amount of change ⁇ T ref is set as a parameter corresponding to a gradient (time-derivative coefficient) of the characteristic of the normal product in FIG. 6 .
- the reference amount of change ⁇ T ref is pre-stored in the storage 34 in association with the this step S 5 , the controller 14 reads out from the storage 34 a reference amount of change associated with the temperature T n acquired at step S 2 and the consumed power P n acquired at step S 3 , and determines it as the reference amount of change ⁇ T ref .
- the reference amount of change ⁇ T ref is defined as a function of the temperature T and the consumed power P.
- the controller 14 calculates the reference amount of change ⁇ T ref from the temperature T n acquired at step S 2 and the consumed power P n acquired at step S 3 .
- the controller 14 functions as a reference determination part 50 ( FIG. 4 ) which determines the reference amount of change ⁇ T ref based on the temperature T n detected by the temperature detecting part 26 and the consumed power P n detected by the electric power detecting part 32 .
- the controller 14 compares the detected amount of change ( ⁇ T, ⁇ T n / ⁇ t) calculated at step S 4 with the reference amount of change ⁇ T ref determined at step S 5 , and judges whether the detected amount of change is different from the reference amount of change ⁇ T ref .
- the controller 14 judges that the detected amount of change ⁇ T n , ⁇ T n / ⁇ t is different from the reference amount of change ⁇ T ref (i.e., judges “YES”), and proceeds to step S 10 .
- the controller 14 determines that the reference amount of change ⁇ T ref (i.e., judges “NO”), and proceeds to step S 7 .
- the controller 14 judges whether the detected amount of change ⁇ T n , ⁇ T n / ⁇ t falls within an allowable range which is predetermined so as to include the reference amount of change ⁇ T ref (e.g., within a range of ⁇ 5% of the reference amount of change ⁇ T ref ).
- the controller 14 judges that the detected amount of change is different from the reference amount of change ⁇ T ref (i.e., judges “YES”), and proceeds to step S 10 .
- the controller 14 judges that the detected amount of change is not different from the reference amount of change ⁇ T ref (i.e., judges “NO”), and proceeds to step S 7 .
- the controller 14 functions as a temperature change judging part 52 ( FIG. 4 ) which compares the reference amount of change ⁇ T ref with the detected amount of change ( ⁇ T n , ⁇ T n / ⁇ t), and judges whether the detected amount of change is different from the reference amount of change.
- step S 7 the controller 14 judges whether the elapsed time clocked by the timer 36 has reached ⁇ n ( ⁇ : period, n: the number of repetition of the loop).
- ⁇ n period, n: the number of repetition of the loop.
- the controller 14 judges that the elapsed time has reached T ⁇ n (i.e., judges “YES”)
- the controller 14 returns to step S 2 .
- the controller 14 judges that the elapsed time has not reached ⁇ n (i.e., judges “NO”)
- the controller 14 proceeds to step S 8 .
- step S 8 the controller 14 judges whether it has received a stop command for stopping the operation of the When The controller 14 judges that it has received the stop command (i.e., judges “YES”), the controller 14 proceeds to step S 9 . On the other hand, when the controller 14 judges that it has not received the stop command (i.e., judges “NO”), the controller 14 returns to step S 7 .
- the controller 14 When it is judged “YES” at step S 6 , at step S 10 , the controller 14 generates a malfunction notification signal indicating that a malfunction occurs in the heat radiation performance of the heatsink 20 .
- the controller 14 generates the malfunction notification signal in the form of an audio signal of an alarm for a user.
- the controller 14 generates the malfunction notification signal in the form of an image signal of an alarm visible to a user.
- the controller 14 functions as a malfunction signal generating part 53 ( FIG. 4 ) which generates a signal indicating that a malfunction occurs in the performance of the heatsink 20 .
- the controller 14 notifies a user that a malfunction occurs in the heat radiation performance of the heatsink 20 , via the alarm output part 38 .
- the controller 14 transmits the audio signal to the alarm output part 38 .
- the alarm output part 38 includes a speaker and outputs the received audio signal as an alarm sound.
- the controller 14 transmits the image signal to the alarm output part 38 .
- the alarm output part 38 includes a display and displays an alarm image corresponding to the received image signal.
- the controller 14 stops the operation of the motor driving device 10 . Specifically, the controller 14 stops the supply of electric power to the heat generating elements 24 , thereby stops the supply of electric power to the main motor.
- the controller 14 repeatedly executes a loop of steps S 2 to S 7 at the period ⁇ until it judges “YES” at step S 6 or S 8 , and calculates the detected amount of change ( ⁇ T n , ⁇ T n / ⁇ t) with respect to the time ⁇ , at intervals of the predetermined time T,.
- the controller 14 constantly monitors whether the detected amount of change is different from the reference amount of change ⁇ T ref . According to this configuration, it is possible to detect a malfunction in the heat radiation performance of the heatsink 20 , even if the temperature T of the motor driving device 10 varies in a short period of time as shown in FIG. 6 .
- a malfunction in the heat radiation performance of the heatsink 20 is detected, a user is automatically informed of the malfunction by the alarm output part 38 . Accordingly, the user can automatically and reliably recognize that it is necessary to remove foreign substances from the flow paths 30 for maintenance, for example.
- controller 14 may execute step S 6 only when the temperature T of the motor driving device 10 increases or when the temperature T decreases. This configuration will be described below.
- the controller 14 can reliably detect an abnormality in the detected amount of change ( ⁇ T 1 , ⁇ T n / ⁇ t) at step S 6 , if it executes step S 6 when the increase or decrease of the temperature T is detected.
- the controller 14 executes step S 6 when the consumed power P detected at step S 3 has been zero.
- the temperature T detected by the temperature detecting part 26 decreases, and therefore the detected amount of change ( ⁇ T, ⁇ T n / ⁇ t) detected at step S 4 is a negative value.
- the motor driving device 60 includes the housing 12 ( FIG. 1 ), a controller 62 , the heatsink assembly 16 ( FIG. 2 , FIG. 3 ), the heat generating element 24 , the temperature detecting part 26 , the electric power detecting part 32 , the storage 34 , the timer 36 , the alarm output part 38 , and a rotation number detecting part 64 .
- the heatsink assembly 16 includes the heatsink 20 and the fan 22 .
- the rotation number detecting part 64 is comprised of e.g. an encoder, and detects the rotation number of the rotator of the fan 22 .
- the rotation number detecting part 64 sends data of the rotation number of the fan 22 to the controller 62 .
- the controller 62 detects the rotation number of the fan 22 . Specifically, the controller 62 sends a command to the rotation number detecting part 64 so as to detect a rotation number R n of the fan 22 . The controller 62 records onto the storage 34 data of the rotation number R n of the fan 22 received from the rotation number detecting part 64 .
- the controller 62 judges whether the rotation number R n acquired at step S 21 is different from a predetermined reference rotation number R ref .
- the reference rotation number R ref is predetermined as a value required for operating the fan 22 in a regular mode when the motor driving device 60 supplies electric power to the main motor of a machine tool, etc.
- the storage 34 pre-stores the reference rotation number R ref .
- the controller 62 judges whether the rotation number R n acquired at step S 21 falls within a predetermined allowable range (e.g., a range of ⁇ 5% of the reference rotation number R ref ). When the rotation number R n is out of the allowable range, the controller 62 judges that the rotation number R n is different from the reference rotation number R ref .
- a predetermined allowable range e.g., a range of ⁇ 5% of the reference rotation number R ref .
- the controller 62 functions as a rotation number judging part 66 ( FIG. 8 ) which judges whether the rotation number R n of the fan 22 is different from the reference rotation number R ref .
- step S 24 When the controller 62 judges that the rotation number R n is different from the reference rotation number R ref (i.e., judges “YES”), it proceeds to step S 24 . On the other hand, when the controller 62 judges that the rotation number R n is not different from the reference rotation number R ref (i.e., judges “NO”), it proceeds to step S 23 .
- the controller 62 generates a first malfunction notification signal indicating that a malfunction occurs in the heat radiation performance of the heatsink 20 .
- the controller 62 generates a second malfunction notification signal indicating that a malfunction occurs in the operation of the fan 22 .
- the controller 62 transmits the first malfunction notification signal generated at step S 23 or the second malfunction notification signal generated at step S 24 to the alarm output part 38 .
- the alarm output part 38 receives the first malfunction notification signal from the controller 62 , it outputs to a user an alarm sound or image representing the occurrence of a malfunction in the heat radiation performance of the heatsink 20 .
- the alarm output part 38 receives the second malfunction notification signal from the controller 62 , it outputs to a user an alarm sound or image representing the occurrence of a malfunction in the operation of the fan 22 .
- the motor driving device 70 includes the housing 12 ( FIG. 1 ), a controller 72 , the heatsink assembly 16 ( FIG. 2 , FIG. 3 ), the heat generating element 24 , the temperature detecting part 26 , the electric power detecting part 32 , the storage 34 , the timer 36 , and the alarm output part 38 .
- the heatsink assembly 16 includes the heatsink 20 and fan 22 .
- the controller 72 judges whether a temperature change of the motor driving device 70 is in a steady state, and if the temperature change is in a steady state, the controller 72 detects a malfunction in the heatsink based on the thermal resistance of the motor driving device 70 .
- the controller 72 judges whether a temperature change of the motor driving device 70 is in a steady state. As an example, the controller 72 determines that the temperature change of the motor driving device 70 is in a steady state, when the consumed power P acquired at step S 3 is substantially constant for a predetermined period of time.
- the controller 72 determines that the temperature change of the motor driving device 70 is in a steady state, when the variation in the consumed powers P n ⁇ n to P acquired at each step S 3 during the controller T n ⁇ n 72 repeatedly executes step S 7 by “m” times (i.e., a period of ⁇ m) falls within a predetermined range (e.g., a range of ⁇ 5%).
- the controller 72 may determine that the temperature change of the motor driving device 70 is in a steady state, when the temperature T acquired at step S 2 is substantially constant for a predetermined period of time. Specifically, the controller 72 determines that the temperature change of the motor driving device 70 is in a steady state, when the variation in the temperatures T n ⁇ m to T n acquired at each step S 2 during the controller 72 repeatedly executes step S 7 by “m” times (i.e., a period of ⁇ m) falls within a predetermined range (e.g., a range of ⁇ 5%).
- the controller 72 functions as a steady state judging part 74 ( FIG. 10 ) which judges whether the temperature change of the motor driving device 70 is in a steady state.
- step S 32 When the controller 72 judges that the temperature change of the motor driving device 70 is in a steady state (i.e., judges “YES”), it proceeds to step S 32 . On the other hand, when the controller 72 judges that the temperature change of the motor driving device 70 is not in a steady state (i.e., judges “NO”), it proceeds to step S 4 .
- the controller 72 calculates a thermal resistance of the motor driving device 70 . Specifically, the controller 72 calculates a thermal resistance Z n of the motor driving device 70 by substituting the temperature T n acquired at step S 2 in the n-th loop, a reference temperature T o , and the consumed power P n acquired at step S 3 in the n-th loop into Equation 1 below.
- the reference temperature T 0 may be a temperature measured by the temperature detecting part 26 before electric power is applied to the heat generating element 24 .
- the reference temperature T 0 may be an ambient temperature around the motor driving device 10 .
- another temperature detecting part for measuring the ambient temperature may be provided.
- the controller 72 functions as a thermal resistance calculating part 76 ( FIG. 10 ) which calculates the thermal resistance of the motor driving device 70 .
- the controller 72 judges whether the thermal resistance Z n calculated at step S 32 is different from a predetermined reference thermal resistance Z ref .
- the reference thermal resistance Z ref is predetermined depending on the temperature T of the motor driving device 70 and the consumed power P of the heat generating element 24 , and is pre-stored in the storage 34 .
- the reference thermal resistance Z ref can be obtained by a theoretical, experimental, or simulation method.
- the controller 72 judges whether the thermal resistance Z n calculated at step S 32 falls within a predetermined allowable range (e.g., a range of ⁇ 5% of the reference thermal resistance Z ref ) . When the thermal resistance Z n is out of the allowable range, the controller 72 judges that the thermal resistance Z n is different from the reference thermal resistance Z ref .
- a predetermined allowable range e.g., a range of ⁇ 5% of the reference thermal resistance Z ref
- the controller 72 functions as a thermal resistance judging part 78 ( FIG. 10 ) which judges whether the thermal resistance Z n calculated at step S 32 is different from the reference thermal resistance Z ref .
- step S 10 When the controller 72 judges that the thermal resistance Z n is different from the reference thermal resistance Z ref (i.e., judges “YES”), it proceeds to step S 10 . On the other hand, when the controller 72 judges that the thermal resistance Z n is not different from the reference thermal resistance Z ref (i.e., judges “NO”), it proceeds to step S 7 .
- this embodiment it is possible to detect a malfunction in the heat radiation performance of the heatsink 20 , both when the temperature of the motor driving device 70 varies in a short period of time and when the temperature of the motor driving device 70 is in a steady state. Due to this, it is possible to reliably detect a malfunction in the heat radiation performance of the heatsink 20 even if the motor driving device 70 is operated in various operation modes.
- the heatsink 20 may have any shape.
- the heatsink may be configured to have a polygonal or circular outer shape.
- the heat generating element 24 may be indirectly attached to the heatsink 20 via another member made of e.g. a heat conducting material.
- the heat generating element 24 may be attached to any element other than the heatsink 20 , which is a component of the motor driving device 10 , 60 , 70 .
- the fan 22 may be omitted.
- the heatsink 20 naturally air-cools the motor driving device. Even in such a case, foreign substances may adhere to the surface of the heatsink 20 , thereby the heat radiation performance of the heatsink 20 may be reduced. According the invention, such a malfunction in the heatsink 20 can be detected.
- controller 14 , 62 , 72 judges “YES” at step S 6 , it may execute step S 9 without carrying out steps S 10 and S 11 . Further, when the controller 14 , 62 , 72 judges “YES” at step S 6 , it may omit step S 9 after executing steps S 10 and S 11 b.
- steps S 21 to S 24 in FIG. 9 can be incorporated in the processing flow in FIG. 7 or 11 .
- steps S 21 to S 24 in FIG. 9 are incorporated in the processing in FIG. 11 , these steps S 21 to S 24 in FIG. 9 can be executed after steps S 6 and S 33 in FIG. 11 .
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Abstract
A motor driving device capable of reliably detecting a malfunction in the performance of a heatsink. The motor driving device includes a heat generating element, a heatsink, an electric power detecting part for detecting a consumed power of the heat generating element, a temperature detecting part for detecting a temperature of the motor driving device, a temperature change calculating part for calculating, as a detected valuation, an amount of change in the temperature within a predetermined time, a reference determination part for determining a reference amount of change in the temperature based on the temperature and the consumed power, and a temperature change judging part for comparing the reference amount of change with the detected amount of change, and judges whether the detected change is different from the reference change.
Description
- 1. Field of the Invention
- The invention relates to a motor driving device for detecting abnormalities in the heat radiation performance of a heatsink, and a detection method.
- 2. Description of the Related Art
- In order to cool an electronic device provided with a heat generating element, such as a power element, a heatsink and a fan for generating an air flow in the heatsink are attached to the electronic device. It has been known that, in such an electronic device, the thermal resistance of the heatsink is calculated from the temperature of the electronic device, and abnormalities in the performance of the heatsink are detected (see, for example, Japanese Unexamined Patent Publication (Kokai) No. 2009-130223).
- A motor driving device for driving a motor embedded in, for example, a machine tool can control electric power to be supplied to the motor so that the electric power greatly varies in a short period of time. In this instance, the temperature of the motor driving device greatly varies in a short period of time.
- In order to calculate the thermal resistance with high precision in the above conventional technology, the temperature of the electronic device should be detected when remaining in a steady state. Thus, in a conventional method, it is difficult to accurately detect abnormalities in the performance of the heatsink in the motor driving device in which the temperature greatly varies in a short period of time.
- In an aspect of the invention, a motor driving device includes a heat generating element, a heatsink which cools the heat generating element, an electric power detecting part which detects a consumed power of the heat generating element, a temperature detecting part which detects a temperature of the motor driving device, and a temperature change calculating part which calculates an amount of change in the temperature within a predetermined time as a detected amount of change, based on the temperature detected by the temperature detecting part.
- Further, the motor driving device includes a reference determination part which determines a reference amount of change in the temperature based on the temperature detected by the temperature detecting part and the consumed power detected by the electric power detecting part, and a temperature change judging part which compares the reference amount of change determined by the reference determination part with the detected amount of change calculated by the temperature change calculating part, and judges whether the detected amount of change is different from the reference amount of change.
- The temperature change judging part may judge that the detected amount of change is different from the reference amount of change when the detected amount of change is out of an allowable range predetermined so as to include the reference amount of change. The temperature change judging part may judge whether the detected amount of change is different from the reference amount of change when the consumed power is zero and the detected amount of change is a negative value.
- The motor driving device may include a fan which generates an air flow in the heatsink, a rotation number detecting part which detects a rotation number of the fan, and a rotation number judging part which judges whether the rotation number detected by the rotation number detecting part is different from a predetermined reference rotation number of the fan when the temperature change judging part judges that the detected amount of change is different from the reference amount of change.
- The motor driving device may further include a malfunction signal generating part which generates a signal indicating that a malfunction occurs in the performance of the heatsink when the temperature change judging part judges that the detected amount of change is different from the reference amount of change.
- The malfunction signal generating part may generate a signal indicating that a malfunction occurs in the performance of the heatsink when the temperature change judging part judges that the detected amount of change is different from the reference amount of change and the rotation number judging part judges that the rotation number is not different from the reference rotation number.
- The malfunction signal generating part may generate a signal indicating that a malfunction occurs in the operation of the fan when the temperature change judging part judges that the detected amount of change is different from the reference amount of change and the rotation number judging part judges that the rotation number is different from the reference rotation number
- The motor driving device may further include a steady state judging part which judges whether a temperature change of the motor driving device is in a steady state. The temperature change calculating part may calculate the detected amount of change when the steady state judging part judges that the temperature change of the motor driving device is not in a steady state.
- The steady state judging part judges that the temperature change of the motor driving device is in a steady state when the consumed power is constant for a predetermined period of time.
- The motor driving device may include a thermal resistance calculating part which calculates a thermal resistance of the motor driving device based on the consumed power and the temperature detected by the temperature detecting part when the steady state judging part judges that the temperature change of the motor driving device is in a steady state.
- The motor driving device may further include a thermal resistance judging part which judges whether the thermal resistance calculated by the thermal resistance calculating part is different from a predetermined reference thermal resistance.
- In another aspect of the invention, a method of detecting a malfunction in the heat radiation performance of a heatsink provided at a motor driving device includes detecting a consumed power of a heat generating element provided at the motor driving device, detecting a temperature of the motor driving device, and calculating an amount of change in the temperature within a predetermined time as a detected change, based on the detected temperature.
- Further, the method includes determining a reference amount of change in the temperature based on the detected consumed power and the detected temperature, and comparing the determined reference amount of change with the calculated detected amount of change, and judging whether the detected amount of change is different from the reference amount of change.
- The aforementioned or other objects, features and advantages of the invention will be clarified in view of the detailed description of exemplary embodiments with reference to the accompanying drawings, in which:
-
FIG. 1 is a perspective view of a motor driving device according to an embodiment of the invention; -
FIG. 2 is a view of a heatsink assembly provided at the motor driving device shown inFIG. 1 ; -
FIG. 3 is a view of the heatsink assembly shown inFIG. 2 as seen from the direction indicated by arrow III inFIG. 2 ; -
FIG. 4 is a block diagram of the motor driving device shown inFIG. 1 ; -
FIG. 5 is a graph showing a relationship between the temperature of the motor driving device and time, and a relationship between the consumed power of the heat generating element and time, wherein the temperature is in a steady state; -
FIG. 6 is a graph showing a relationship between the temperature of the motor driving device and time, and a relationship between the consumed power of the heat generating element and time, wherein the temperature varies in a short period of time; -
FIG. 7 is a flowchart showing an example of a processing flow of the motor driving device shown inFIG. 4 ; -
FIG. 8 is a block diagram of a motor driving device according to another embodiment of the invention; -
FIG. 9 is a flowchart showing an example of a processing flow of the motor driving device shown inFIG. 8 ; -
FIG. 10 is a block diagram of a motor driving device according to still another embodiment of the invention; and -
FIG. 11 is a flowchart showing an example of a processing flow of the motor driving device shown inFIG. 10 . - Embodiments of the invention will be described below in detail with reference to the drawings. First, referring to
FIGS. 1 to 4 , amotor driving device 10 according to an embodiment of the invention will be described. Themotor driving device 10 supplies electric power to a main motor (not shown) built in a machine tool, etc., in order to drive the main motor. - The
motor driving device 10 includes ahousing 12, acontroller 14, aheatsink assembly 16,heat generating elements 24, and atemperature detecting part 26. Thehousing 12 is a box member made of e.g. a resin, and defines an inner space therein. - The
controller 14 includes e.g. a CPU, and is mounted in the inner space of thehousing 12. Thecontroller 14 directly or indirectly controls each component of themotor driving device 10. - The
heatsink assembly 16 is provided to be adjacent to thehousing 12. As shown inFIGS. 2 and 3 , theheatsink assembly 16 includes aheatsink 20 and afan 22. - The
heatsink 20 is a rectangular member having a longitudinal direction along the z-axis direction in the Cartesian coordinate system shown inFIGS. 2 and 3 . Theheatsink 20 has afirst end part 20 a in the z-axis direction and asecond end part 20 b opposite thefirst end part 20 a. - The
heatsink 20 includes a plurality ofheat radiation fins 28. Each of theheat radiation fins 28 is a plate member having a predetermined length in the z-axis direction, a predetermined thickness in the y-axis direction, and a predetermined width in the x-axis direction. Each of theheat radiation fins 28 extends between thefirst end part 20 a and thesecond end part 20 b. Theheat radiation fins 28 are arranged to align in the y-axis direction at substantially equal intervals. -
Flow paths 30 are each defined between two heat radiation fins 28 adjacent to each other in the y-axis direction. Eachflow path 30 extends in the z-axis direction between thefirst end part 20 a and thesecond end part 20 b, and opens to the outside at thefirst end part 20 a and thesecond end part 20 b. - The
fan 22 is attached to thefirst end part 20 a of theheatsink 20. Thefan 22 includes a rotator (not shown) with a plurality of vanes, and a fan motor (not shown) which rotates the rotator. The fan motor rotates the rotator of thefan 22 in accordance with a command from thecontroller 14. - When the rotator of the
fan 22 is rotated, an air flow in e.g. the z-axis positive direction inFIG. 2 is generated in theflow paths 30. In this case, outside air is flown into the openings of theflow paths 30 at thesecond end part 20 b, passes through theflow paths 30 in the z-axis positive direction, and is discharged from the openings of theflow paths 30 at thefirst end part 20 a. Theheatsink 20 is cooled by the air flowing through theflow paths 30 as described above, thereby themotor driving device 10 is cooled. - In this embodiment, the
heat generating elements 24 and thetemperature detecting part 26 are disposed on anouter surface 20 c of theheatsink 20. Theheat generating elements 24 includes e.g. a power element, and generates electric power in accordance with a command from thecontroller 14. Thecontroller 14 supplies the electric power generated by theheat generating elements 24 to the main motor of e.g. a machine tool so as to drive the main motor. - The
temperature detecting part 26 includes a temperature sensor, and detects the temperature at a position at which thetemperature detecting part 26 is disposed, in accordance with a command from thecontroller 14. Thetemperature detecting part 26 sends data of the detected temperature to thecontroller 14. - As shown in
FIG. 4 , themotor driving device 10 further includes an electricpower detecting part 32, astorage 34, atimer 36, and analarm output part 38. - The electric
power detecting part 32 detects the consumed power of theheat generating elements 24, and sends data of the detected consumed power to thecontroller 14. As an example, the electricpower detecting part 32 is installed so as to detect the consumed power of one of theheat generating elements 24. - As another example, the electric
power detecting part 32 may be installed so as to detect the consumed power of the whole of a power amplifier (not shown) comprised of a plurality ofheat generating elements 24. - The
storage 34 is comprised of e.g. a non-volatile memory which can electrically delete/record data, such as an EEPROM (trademark), or a random access memory which can rapidly read/write data, such as a DRAM, a SRAM, etc. - The
storage 34 is connected to thecontroller 14 so as to communicate with thecontroller 14, and stores data received from thetemperature detecting part 26 and the electricpower detecting part 32, and a reference amount of change that will be described later. Thestorage 34 may be built in thecontroller 14, or may be built in an external device (e.g., a server) which is installed outside of thecontroller 14 and which is connected to thecontroller 14 so as to communicate with thecontroller 14 via a network. - The
timer 36 times an elapsed time from a predetermined time point in accordance with a command from thecontroller 14. Thealarm output part 38 includes e.g. a speaker or display, and outputs a sound wave or an image in accordance with a command from thecontroller 14. Thetimer 36 may be built in thecontroller 14, or in an external device installed outside of thecontroller 14 so as to be communicably connected to the controller. - As the
fan 22 is operated so as to cause an air to flow in theflow paths 30 in order to cool themotor driving device 10, foreign substances, such as dusts, can enter theflow paths 30 and accumulate to block theflow paths 30. - In this case, an air flow in the
flow paths 30 is disturbed, thereby the air flow abnormally decreases. Consequently, the heat radiation performance of theheatsink 20 may be reduced to cause themotor driving device 10 to overheat. - The
motor driving device 10 according to this embodiment detects whether a malfunction occurs in the heat radiation performance of theheatsink 20, based on an amount of change in the temperature detected by thetemperature detecting part 26 with respect to time. - The concept of a method of detecting a malfunction in the heat radiation performance of the
heatsink 20 of themotor driving device 10 will be described below with reference toFIGS. 5 and 6 . Each of the graphs in the upper sections ofFIGS. 5 and 6 shows a relationship between temperature T detected by thetemperature detecting part 26 and time t, while each of the graphs in the lower sections ofFIGS. 5 and 6 shows a relationship between electric power P detected by the electricpower detecting part 32 and time t. - Note that, each of
solid lines FIGS. 5 and 6 represents a characteristic in a case where foreign substances do not accumulate in theflow paths 30 of theheatsink 20, and the heat radiation performance of theheatsink 20 is normal (hereinafter referred as “normal product”). - On the other hand, each of dashed-dotted
lines FIGS. 5 and 6 represents a characteristic in a case where foreign substances accumulate in theflow paths 30 of theheatsink 20, thereby an air flow in theflow paths 30 are disturbed so that the heat radiation performance of theheatsink 20 is reduced (hereinafter referred as “malfunction product”). - As shown in
FIG. 5 , when a constant electric power Pmax is applied to theheat generating elements 24 from a time point t1, the temperature T rapidly increases from the time point t1, and then gradually shifts to a steady state (i.e., saturated state). - When the temperature T is in a steady state, there is no remarkable difference between an amount of temperature change with respect to time (i.e., a gradient) of the characteristic of the normal product (solid line 42) and an amount of temperature change with respect to time of the characteristic of the malfunction product (dashed-dotted line 40). In such a steady state, it is possible to detect a thermal resistance of the motor driving device 10 (e.g., the heatsink 20) accurately, based on the temperature T and the electric power P.
- On the other hand, when the electric power P applied to the
heat generating elements 24 varies in a short period of time (for example, when themotor driving device 10 supplies a high-frequency electric power to the main motor) as shown inFIG. 6 , the temperature T also varies in a short period of time so as to follow the variation of the consumed power P, thereby does not shift to a steady state. In this case, it is not possible to accurately calculate the thermal resistance of themotor driving device 10. - As described above, in the
motor driving device 10, the consumed power varies in a short period of time, and therefore the temperature T greatly varies in a short period of time as shown in the upper graph ofFIG. 6 . - Referring to the upper graph of
FIG. 6 , when the temperature increases, the degree of increase in the temperature with respect to time of the malfunction product (i.e., dashed-dotted line 44) is larger than that of the normal product (i.e., solid line 46). - On the other hand, when the temperature decreases, the degree of decrease in the temperature with respect to time of the malfunction product (i.e., dashed-dotted line 44) is smaller than that of the normal product (i.e., solid line 46). In other words, the gradient (or time-derivative coefficient) of the characteristic of the malfunction product when the temperature increases and when the temperature decreases is remarkably different from that of the normal product.
- The
motor driving device 10 according to this embodiment detects whether a malfunction occurs in the heat radiation performance of theheatsink 20 by comparing an amount of change in the temperature with respect to time of the normal product (a reference amount of change) with an amount of change in the temperature detected by thetemperature detecting part 26 with respect to time (a detected amount of change). - Next, the operation of the
motor driving device 10 will be described below with reference toFIG. 7 . The processing flow shown inFIG. 7 is started when thecontroller 14 receives a motor drive command for driving the main motor built in a machine tool, etc., from e.g. a user or a host controller (e.g., a machine tool controller). - At step S1, the
controller 14 starts to time an elapsed time. Specifically, thecontroller 14 sends a timing start command to thetimer 36. Thetimer 36 times an elapsed time from the time point when it has received the timing starting command from thecontroller 14. - As described later, in the processing flow according to this example, the
controller 14 repeatedly executes a loop of steps S2 to S7 at a period τ (e.g., one second) until it judges “YES” at step S6 or S8. Below, an operation when thecontroller 14 executes the n-th loop will be described. - At step S2, the
controller 14 detects a temperature Tn of themotor driving device 10. Specifically, thecontroller 14 transmits a command to thetemperature detecting part 26 so as to detect a temperature at the position where thetemperature detecting part 26 is disposed. Thecontroller 14 records data of the temperature acquired from thetemperature detecting part 26 onto thestorage 34. - At step S3, the
controller 14 detects a consumed power Pn of theheat generating elements 24. Specifically, thecontroller 14 transmits a command to the electricpower detecting part 32 so as to detect a consumed power of theheat generating elements 24. Thecontroller 14 records data of the consumed power acquired from the electricpower detecting part 32 onto thestorage 34. - At step S4, the
controller 14 calculates a detected amount of change which corresponds to an amount of change in the temperature within the time τ (period τ). As an example, thecontroller 14 calculates a difference ΔTn (=Tn−Tn−1) between the temperature Tn acquired at step S2 in the n-th loop and the temperature Tn−1 acquired at step S2 in the (n−1)-th loop (i.e., acquired time τ before the temperature Tn), as a detected amount of change ΔTn. - In another example, the
controller 14 calculates a gradient δTn/δt (=ΔTn/τ) obtained by dividing the above-mentioned difference ΔTn by the time τ, as a detected change τTn/τt. Thus, in this embodiment, thecontroller 14 functions as a temperature change calculating part 48 (FIG. 4 ) which calculates the detected amount of change (ΔTn, τTn/τt). - At step S5, the
controller 14 determines a reference amount of change ΔTref based on the temperature Tn acquired at step S2 and the consumed power Pn acquired at step S3. - The reference amount of change ΔTref is a parameter corresponding to a degree of temperature change with respect to time of the normal product (solid line 46) in
FIG. 6 . - For example, when the difference ΔTn is calculated as the detected amount of change at step S4, the reference amount of change ΔTref is set as a parameter corresponding to a temperature change within the time τ of the characteristic of the normal product in
FIG. 6 . Alternatively, when the gradient τTn/τt is calculated as the detected amount of change at step S4, the reference amount of change ΔTref is set as a parameter corresponding to a gradient (time-derivative coefficient) of the characteristic of the normal product inFIG. 6 . - As an example, the reference amount of change ΔTref is pre-stored in the
storage 34 in association with the this step S5, thecontroller 14 reads out from the storage 34 a reference amount of change associated with the temperature Tn acquired at step S2 and the consumed power Pn acquired at step S3, and determines it as the reference amount of change ΔTref. - In another example, the reference amount of change ΔTref is defined as a function of the temperature T and the consumed power P. In this case, at this step S5, the
controller 14 calculates the reference amount of change ΔTref from the temperature Tn acquired at step S2 and the consumed power Pn acquired at step S3. - Thus, in this embodiment, the
controller 14 functions as a reference determination part 50 (FIG. 4 ) which determines the reference amount of change ΔTref based on the temperature Tn detected by thetemperature detecting part 26 and the consumed power Pn detected by the electricpower detecting part 32. - At step S6, the
controller 14 compares the detected amount of change (ΔT, δTn/δt) calculated at step S4 with the reference amount of change ΔTref determined at step S5, and judges whether the detected amount of change is different from the reference amount of change ΔTref. - As an example, the
controller 14 calculates a difference δ1(=IΔTn−ΔTref|, |δTn/δt−ΔTref|) between the detected amount of change (ΔTn, δTn/δt) and the reference amount of change ΔTref, and judges whether the difference δ1 exceeds a predetermined threshold value α1. - When the difference δ1 exceeds the threshold value α1 (i.e., δ1>α1), the
controller 14 judges that the detected amount of change ΔTn, δTn/δt is different from the reference amount of change ΔTref (i.e., judges “YES”), and proceeds to step S10. On the other hand, when the difference δ1 does not exceed the threshold value α1 (i.e., δ1≧α1), thecontroller 14 determines that the reference amount of change ΔTref (i.e., judges “NO”), and proceeds to step S7. - As another example, the
controller 14 judges whether the detected amount of change ΔTn, δTn/δt falls within an allowable range which is predetermined so as to include the reference amount of change ΔTref (e.g., within a range of ±5% of the reference amount of change ΔTref). - When the detected amount of change ΔTn, δTn/δt is out of the allowable range, the
controller 14 judges that the detected amount of change is different from the reference amount of change ΔTref (i.e., judges “YES”), and proceeds to step S10. - On the other hand, when the detected amount of change ΔTn, δTn/δt falls within the allowable range, the
controller 14 judges that the detected amount of change is not different from the reference amount of change ΔTref (i.e., judges “NO”), and proceeds to step S7. - Thus, in this embodiment, the
controller 14 functions as a temperature change judging part 52 (FIG. 4 ) which compares the reference amount of change ΔTref with the detected amount of change (ΔTn, δTn/δt), and judges whether the detected amount of change is different from the reference amount of change. - At step S7, the
controller 14 judges whether the elapsed time clocked by thetimer 36 has reached τ×n (τ: period, n: the number of repetition of the loop). When thecontroller 14 judges that the elapsed time has reached T×n (i.e., judges “YES”), thecontroller 14 returns to step S2. On the other hand, when thecontroller 14 judges that the elapsed time has not reached τ×n (i.e., judges “NO”), thecontroller 14 proceeds to step S8. - At step S8, the
controller 14 judges whether it has received a stop command for stopping the operation of the When Thecontroller 14 judges that it has received the stop command (i.e., judges “YES”), thecontroller 14 proceeds to step S9. On the other hand, when thecontroller 14 judges that it has not received the stop command (i.e., judges “NO”), thecontroller 14 returns to step S7. - When it is judged “YES” at step S6, at step S10, the
controller 14 generates a malfunction notification signal indicating that a malfunction occurs in the heat radiation performance of theheatsink 20. As an example, thecontroller 14 generates the malfunction notification signal in the form of an audio signal of an alarm for a user. - As another example, the
controller 14 generates the malfunction notification signal in the form of an image signal of an alarm visible to a user. Thus, in this embodiment, thecontroller 14 functions as a malfunction signal generating part 53 (FIG. 4 ) which generates a signal indicating that a malfunction occurs in the performance of theheatsink 20. - At step S11, the
controller 14 notifies a user that a malfunction occurs in the heat radiation performance of theheatsink 20, via thealarm output part 38. As an example, if an audio signal of an alarm is generated at step S10, thecontroller 14 transmits the audio signal to thealarm output part 38. In this case, thealarm output part 38 includes a speaker and outputs the received audio signal as an alarm sound. - As another example, if an image signal of an alarm is generated at step S10, the
controller 14 transmits the image signal to thealarm output part 38. In this case, thealarm output part 38 includes a display and displays an alarm image corresponding to the received image signal. - At step S9, the
controller 14 stops the operation of themotor driving device 10. Specifically, thecontroller 14 stops the supply of electric power to theheat generating elements 24, thereby stops the supply of electric power to the main motor. - As described above, in the processing flow according to this example, the
controller 14 repeatedly executes a loop of steps S2 to S7 at the period τ until it judges “YES” at step S6 or S8, and calculates the detected amount of change (ΔTn, δTn/δt) with respect to the time τ, at intervals of the predetermined time T,. - The
controller 14 constantly monitors whether the detected amount of change is different from the reference amount of change ΔTref. According to this configuration, it is possible to detect a malfunction in the heat radiation performance of theheatsink 20, even if the temperature T of themotor driving device 10 varies in a short period of time as shown inFIG. 6 . - Further, in this embodiment, if a malfunction in the heat radiation performance of the
heatsink 20 is detected, a user is automatically informed of the malfunction by thealarm output part 38. Accordingly, the user can automatically and reliably recognize that it is necessary to remove foreign substances from theflow paths 30 for maintenance, for example. - Note that, the
controller 14 may execute step S6 only when the temperature T of themotor driving device 10 increases or when the temperature T decreases. This configuration will be described below. - As can be seen from the upper graph of
FIG. 6 , the difference between the gradient of the temperature-time characteristic of the normal product and that of the malfunction product is remarkable when the temperature increases or decreases. - Accordingly, the
controller 14 can reliably detect an abnormality in the detected amount of change (ΔT1, δTn/δt) at step S6, if it executes step S6 when the increase or decrease of the temperature T is detected. - As an example, the
controller 14 executes step S6 when the consumed power P detected at step S3 has been zero. In this case, the temperature T detected by thetemperature detecting part 26 decreases, and therefore the detected amount of change (ΔT, δTn/δt) detected at step S4 is a negative value. - If a malfunction occurs in the heat radiation performance of the
heatsink 20 in this case, the difference between the detected amount of change (ΔTn, δTn/δt) calculated at step S4 and the reference amount of change ΔTref determined at step S5 is remarkable. - Therefore, it is possible to reliably detect an abnormality in the detected amount of change (ΔTn, δTn/δt) at step S6.
- Next, a
motor driving device 60 according to another embodiment of the invention will be described with reference toFIG. 8 . Note that, in various embodiments described below, elements similar to those in the already-mentioned embodiments are assigned the same reference numerals, and detailed descriptions thereof will be omitted. - The
motor driving device 60 includes the housing 12 (FIG. 1 ), acontroller 62, the heatsink assembly 16 (FIG. 2 ,FIG. 3 ), theheat generating element 24, thetemperature detecting part 26, the electricpower detecting part 32, thestorage 34, thetimer 36, thealarm output part 38, and a rotationnumber detecting part 64. Theheatsink assembly 16 includes theheatsink 20 and thefan 22. - The rotation
number detecting part 64 is comprised of e.g. an encoder, and detects the rotation number of the rotator of thefan 22. The rotationnumber detecting part 64 sends data of the rotation number of thefan 22 to thecontroller 62. - Next, the operation of the
motor driving device 60 will be described with reference toFIG. 9 . Note that, in the processing flow shown inFIG. 9 , processes similar to those of the processing flow shown inFIG. 7 are assigned the same step numbers, and detailed descriptions thereof will be omitted. - When it is judged “YES” at step S6, at step S21, the
controller 62 detects the rotation number of thefan 22. Specifically, thecontroller 62 sends a command to the rotationnumber detecting part 64 so as to detect a rotation number Rn of thefan 22. Thecontroller 62 records onto thestorage 34 data of the rotation number Rn of thefan 22 received from the rotationnumber detecting part 64. - At step S22, the
controller 62 judges whether the rotation number Rn acquired at step S21 is different from a predetermined reference rotation number Rref. For example, the reference rotation number Rref is predetermined as a value required for operating thefan 22 in a regular mode when themotor driving device 60 supplies electric power to the main motor of a machine tool, etc. Thestorage 34 pre-stores the reference rotation number Rref. - As an example, the
controller 62 calculates a difference δ2 (=|Rn−Rref|) between the rotation number Rn acquired at step S21 and the reference rotation number Rref stored in thestorage 34. Then, thecontroller 62 judges whether the difference δ2 exceeds a predetermined threshold value α2. When the difference δ2 exceeds the threshold value α2 (i.e. δ2<α2), thecontroller 62 determines that the rotation number Rn is different from the reference rotation number Rref. - As another example, the
controller 62 judges whether the rotation number Rn acquired at step S21 falls within a predetermined allowable range (e.g., a range of ±5% of the reference rotation number Rref). When the rotation number Rn is out of the allowable range, thecontroller 62 judges that the rotation number Rn is different from the reference rotation number Rref. - Thus, in this embodiment, the
controller 62 functions as a rotation number judging part 66 (FIG. 8 ) which judges whether the rotation number Rn of thefan 22 is different from the reference rotation number Rref. - When the
controller 62 judges that the rotation number Rn is different from the reference rotation number Rref (i.e., judges “YES”), it proceeds to step S24. On the other hand, when thecontroller 62 judges that the rotation number Rn is not different from the reference rotation number Rref (i.e., judges “NO”), it proceeds to step S23. - At step S23, the
controller 62 generates a first malfunction notification signal indicating that a malfunction occurs in the heat radiation performance of theheatsink 20. On the other hand, at step S24, thecontroller 62 generates a second malfunction notification signal indicating that a malfunction occurs in the operation of thefan 22. - At step S25, the
controller 62 transmits the first malfunction notification signal generated at step S23 or the second malfunction notification signal generated at step S24 to thealarm output part 38. - If the
alarm output part 38 receives the first malfunction notification signal from thecontroller 62, it outputs to a user an alarm sound or image representing the occurrence of a malfunction in the heat radiation performance of theheatsink 20. On the other hand, when thealarm output part 38 receives the second malfunction notification signal from thecontroller 62, it outputs to a user an alarm sound or image representing the occurrence of a malfunction in the operation of thefan 22. - According to this embodiment, it is possible to judge whether the abnormality in the detected amount of change (ΔTn, δTn/δt) is caused due to the
heatsink 20 or thefan 22, when the abnormality in the detected amount of change is detected at step S6. Therefore, a user can accurately recognize the cause of the malfunction in the heat radiation performance of theheatsink 20. - Next, a
motor driving device 70 according to still another embodiment of the invention will be described with reference toFIG. 10 . Themotor driving device 70 includes the housing 12 (FIG. 1 ), acontroller 72, the heatsink assembly 16 (FIG. 2 ,FIG. 3 ), theheat generating element 24, thetemperature detecting part 26, the electricpower detecting part 32, thestorage 34, thetimer 36, and thealarm output part 38. Theheatsink assembly 16 includes theheatsink 20 andfan 22. - Next, the operation of the
motor driving device 70 will be described with reference toFIG. 11 . Note that, in the processing flow shown inFIG. 11 , processes similar to those of the processing flow shown inFIG. 7 are assigned the same step numbers, and detailed descriptions thereof will be omitted. - As described above with reference to
FIG. 5 , when constant electric power P is continuously applied to theheat generating element 24, the temperature T gradually shifts to a steady state (i.e., saturated state). When the temperature T is in the steady state, there is no remarkable difference between the gradient of the characteristic of the normal product (solid line 42) and that of the malfunction product (dashed-dotted line 40). - Therefore, in such a steady state, even in a malfunction product, the difference between the detected amount of change (ΔTn, δTn/δt) and the reference amount of change ΔTref is small, and therefore it is difficult to detect an abnormality in the detected amount of change at step S6.
- In order to address this matter, in this embodiment, the
controller 72 judges whether a temperature change of themotor driving device 70 is in a steady state, and if the temperature change is in a steady state, thecontroller 72 detects a malfunction in the heatsink based on the thermal resistance of themotor driving device 70. - Specifically, at step S31, the
controller 72 judges whether a temperature change of themotor driving device 70 is in a steady state. As an example, thecontroller 72 determines that the temperature change of themotor driving device 70 is in a steady state, when the consumed power P acquired at step S3 is substantially constant for a predetermined period of time. - Specifically, the
controller 72 determines that the temperature change of themotor driving device 70 is in a steady state, when the variation in the consumed powers Pn−n to P acquired at each step S3 during thecontroller T n−n 72 repeatedly executes step S7 by “m” times (i.e., a period of τ×m) falls within a predetermined range (e.g., a range of ±5%). - As another example, the
controller 72 may determine that the temperature change of themotor driving device 70 is in a steady state, when the temperature T acquired at step S2 is substantially constant for a predetermined period of time. Specifically, thecontroller 72 determines that the temperature change of themotor driving device 70 is in a steady state, when the variation in the temperatures Tn−m to Tn acquired at each step S2 during thecontroller 72 repeatedly executes step S7 by “m” times (i.e., a period of τ×m) falls within a predetermined range (e.g., a range of ±5%). - Thus, in this embodiment, the
controller 72 functions as a steady state judging part 74 (FIG. 10 ) which judges whether the temperature change of themotor driving device 70 is in a steady state. - When the
controller 72 judges that the temperature change of themotor driving device 70 is in a steady state (i.e., judges “YES”), it proceeds to step S32. On the other hand, when thecontroller 72 judges that the temperature change of themotor driving device 70 is not in a steady state (i.e., judges “NO”), it proceeds to step S4. - At step S32, the
controller 72 calculates a thermal resistance of themotor driving device 70. Specifically, thecontroller 72 calculates a thermal resistance Zn of themotor driving device 70 by substituting the temperature Tn acquired at step S2 in the n-th loop, a reference temperature To, and the consumed power Pn acquired at step S3 in the n-th loop into Equation 1 below. -
Z n=(T n −T 0)/P n (Equation 1) - Note that, the reference temperature T0 may be a temperature measured by the
temperature detecting part 26 before electric power is applied to theheat generating element 24. Alternatively, the reference temperature T0 may be an ambient temperature around themotor driving device 10. In this case, another temperature detecting part for measuring the ambient temperature may be provided. - Thus, in this embodiment, the
controller 72 functions as a thermal resistance calculating part 76 (FIG. 10 ) which calculates the thermal resistance of themotor driving device 70. - At step S33, the
controller 72 judges whether the thermal resistance Zn calculated at step S32 is different from a predetermined reference thermal resistance Zref. The reference thermal resistance Zref is predetermined depending on the temperature T of themotor driving device 70 and the consumed power P of theheat generating element 24, and is pre-stored in thestorage 34. The reference thermal resistance Zref can be obtained by a theoretical, experimental, or simulation method. - As an example, the
controller 72 calculates a difference δ3 (=|Zn−Zref|) between the thermal resistance Zn calculated at step S32 and the reference thermal resistance Zref. Then, thecontroller 72 judges whether the difference δ3 exceeds a predetermined threshold value α3. When the difference δ3 exceeds the threshold value α3 (i.e., δ3>α3), thecontroller 62 judges that the thermal resistance Zn is different from the reference thermal resistance Zref. - As another example, the
controller 72 judges whether the thermal resistance Zn calculated at step S32 falls within a predetermined allowable range (e.g., a range of ±5% of the reference thermal resistance Zref) . When the thermal resistance Zn is out of the allowable range, thecontroller 72 judges that the thermal resistance Zn is different from the reference thermal resistance Zref. - Thus, in this embodiment, the
controller 72 functions as a thermal resistance judging part 78 (FIG. 10 ) which judges whether the thermal resistance Zn calculated at step S32 is different from the reference thermal resistance Zref. - When the
controller 72 judges that the thermal resistance Zn is different from the reference thermal resistance Zref (i.e., judges “YES”), it proceeds to step S10. On the other hand, when thecontroller 72 judges that the thermal resistance Zn is not different from the reference thermal resistance Zref (i.e., judges “NO”), it proceeds to step S7. - According to this embodiment, it is possible to detect a malfunction in the heat radiation performance of the
heatsink 20, both when the temperature of themotor driving device 70 varies in a short period of time and when the temperature of themotor driving device 70 is in a steady state. Due to this, it is possible to reliably detect a malfunction in the heat radiation performance of theheatsink 20 even if themotor driving device 70 is operated in various operation modes. - Note that, the
heatsink 20 may have any shape. For example, the heatsink may be configured to have a polygonal or circular outer shape. - Further, the
heat generating element 24 may be indirectly attached to theheatsink 20 via another member made of e.g. a heat conducting material. Alternatively, theheat generating element 24 may be attached to any element other than theheatsink 20, which is a component of themotor driving device - Further, the
fan 22 may be omitted. In this case, theheatsink 20 naturally air-cools the motor driving device. Even in such a case, foreign substances may adhere to the surface of theheatsink 20, thereby the heat radiation performance of theheatsink 20 may be reduced. According the invention, such a malfunction in theheatsink 20 can be detected. - Further, when the
controller controller - Further, the features of the above-mentioned various embodiments can be combined. For example, steps S21 to S24 in
FIG. 9 can be incorporated in the processing flow inFIG. 7 or 11 . - If steps S21 to S24 in
FIG. 9 are incorporated in the processing inFIG. 11 , these steps S21 to S24 inFIG. 9 can be executed after steps S6 and S33 inFIG. 11 . - Although the invention has been described above through various embodiments, the embodiments do not limit the inventions according to the claims. Further, a configuration obtained by combining the features described in the embodiments of the invention can be included in the technical scope of the invention. However, all combinations of these features are not necessarily essential for means for solving the invention. Furthermore, it is obvious for a person skilled in the art that various modifications or improvements can be applied to the embodiments.
- Regarding the order of operations, such as actions, sequences, steps, processes, and stages, in the devices, systems, programs, and methods indicated in the claims, specification and drawings, it should be noted that the terms “before”, “prior to”, etc. are not explicitly described, and any order can be realized unless the output of a previous operation is used in the subsequent operation. Regarding the processing in the claims, specification, and drawings, even when the order of operations is described using the terms “first”, “next”, “subsequently”, “then”, etc., for convenience, maintaining this order is not necessarily essential for working the inventions.
Claims (10)
1. A motor driving device comprising:
a heat generating element;
a heatsink which cools the heat generating element;
an electric power detecting part which detects a consumed power of the heat generating element;
a temperature detecting part which detects a temperature of the motor driving device;
a temperature change calculating part which calculates an amount of change in the temperature within a predetermined time as a detected amount of change, based on the temperature detected by the temperature detecting part;
a reference determination part which determines a reference amount of change in the temperature, based on the temperature detected by the temperature detecting part and on the consumed power detected by the electric power detecting part; and
a temperature change judging part which compares the reference amount of change determined by the reference determination part with the detected amount of change calculated by the temperature change calculating part, and judges whether the detected amount of change is different from the reference amount of change.
2. The motor driving device according to claim 1 , wherein the temperature change judging part judges that the detected amount of change is different from the reference amount of change when the detected amount of change is out of an allowable range which is predetermined so as to include the reference amount of change.
3. The motor driving device according to claim 1 , wherein the temperature change judging part judges whether the detected amount of change is different from the reference amount of change when the consumed power is zero and the detected amount of change is a negative value.
4. A motor driving device according to claim 1 , further comprising:
a fan which generates an air flow in the heatsink;
a rotation number detecting part which detects a rotation number of the fan; and
a rotation number judging part which judges whether the rotation number detected by the rotation number detecting part is different from a predetermined reference rotation number of the fan when the temperature change judging part judges that the detected amount of change is different from the reference amount of change.
5. The motor driving device according to claim 1 , further comprising a malfunction signal generating part which generates a signal indicating that a malfunction occurs in a performance of the heatsink when the temperature change judging part judges that the detected amount of change is different from the reference amount of change.
6. The motor driving device according to claim 4 , further comprising a malfunction signal generating part which:
generates a signal indicating that a malfunction occurs in a performance of the heatsink when the temperature change judging part judges that the detected amount of change is different from the reference amount of change and the rotation number judging part judges that the rotation number is not different from the reference rotation number; and which
generates a signal indicating that a malfunction occurs in an operation of the fan when the temperature change judging part judges that the detected amount of change is different from the reference amount of change and the rotation number judging part judges that the rotation number is different from the reference rotation number.
7. A motor driving device according to claim 1 , further comprising a steady state judging part which judges whether a temperature change of the motor driving device is in a steady state, wherein
the temperature change calculating part calculates the detected amount of change when the steady state judging part judges that the temperature change of the motor driving device is not in a steady state.
8. The motor driving device according to claim 7 , wherein the steady state judging part judges that the temperature change of the motor driving device is in a steady state when the consumed power is constant for a predetermined period of time.
9. The motor driving device according to claim 7 , further comprising:
a thermal resistance calculating part which calculates a thermal resistance of the motor driving device based on the consumed power and the temperature detected by the temperature detecting part when the steady state judging part judges that the temperature change of the motor driving device is in a steady state; and
a thermal resistance judging part which judges whether the thermal resistance calculated by the thermal resistance calculating part is different from a predetermined reference thermal resistance.
10. A method of detecting a malfunction in the heat radiation performance of a heatsink provided at a motor driving device, the method comprising:
detecting a consumed power of a heat generating element provided at the motor driving device;
detecting a temperature of the motor driving device;
calculating an amount of change in the temperature within a predetermined time as a detected amount of change, based on the detected temperature;
determining a reference amount of change in the temperature based on the detected consumed power and the detected temperature; and
comparing the determined reference amount of change with the calculated detected amount of change, and judging whether the detected amount of change is different from the reference amount of change.
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US16/549,207 US11125830B2 (en) | 2015-07-21 | 2019-08-23 | Motor driving device and detection method for detecting malfunction in heat radiation performance of heatsink |
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JP2015144124A JP6316777B2 (en) | 2015-07-21 | 2015-07-21 | Motor drive device and method for detecting abnormality in heat dissipation performance of heat sink |
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EP3749076A1 (en) * | 2019-06-08 | 2020-12-09 | Diehl AKO Stiftung & Co. KG | Method for monitoring a cooling effect of an air cooling device |
CN115014832A (en) * | 2022-08-08 | 2022-09-06 | 南昌三瑞智能科技有限公司 | Experimental device and test method for rapidly verifying performance of heat dissipation scheme in motor |
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EP3382863B1 (en) * | 2017-03-30 | 2021-08-11 | ABB Schweiz AG | A method for detecting a rotor bar fault |
JP6953941B2 (en) * | 2017-09-19 | 2021-10-27 | 株式会社明電舎 | Blower abnormality diagnosis device, power device and blower abnormality diagnosis method |
JP7035402B2 (en) * | 2017-09-19 | 2022-03-15 | 株式会社明電舎 | Blower abnormality diagnosis device, power device and blower abnormality diagnosis method |
KR20210113368A (en) * | 2019-03-18 | 2021-09-15 | 도시바 캐리어 가부시키가이샤 | Motor control device and control method |
CN111752315B (en) * | 2019-03-29 | 2022-10-28 | 中国科学院长春光学精密机械与物理研究所 | Temperature control method, temperature controller and temperature control system for vacuum thermal test of spacecraft |
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US11125830B2 (en) | 2021-09-21 |
CN106374814B (en) | 2020-09-01 |
JP2017028833A (en) | 2017-02-02 |
JP6316777B2 (en) | 2018-04-25 |
CN106374814A (en) | 2017-02-01 |
DE102016112923A1 (en) | 2017-01-26 |
US20190377031A1 (en) | 2019-12-12 |
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