Patent Publication Number: US-2017363484-A1

Title: Rotating device

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2016-119668 filed in Japan on Jun. 16, 2016, the entire contents of which are incorporated herein by reference. 
     FIELD 
     The present disclosure relates to a rotating device. 
     BACKGROUND 
     Rotating devices (motors) that convert electrical energy into mechanical energy are utilized in many applications as a power source for industrial machineries. Such rotating devices have different specifications designed in accordance with the applied environment and the application purpose. In the case of, for example, an application under an ignitable gas atmosphere or an application at a location where the oxygen concentration is high, an explosion-proof type rotating device is chosen. According to such a type of rotating device, since the rotator and the stator are housed in a sealed space, a heat dissipation efficiency is not excellent. Hence, the temperature of the rotator and that of the stator are monitored, and the rotating device is operated in such a way that the respective temperatures do not exceed a certain level. 
     Monitoring of the temperature of the stator is relatively easy, but in order to monitor the temperature of the rotating rotator, for example, it is necessary to take out a signal from a temperature sensor attached to the rotator via a slip ring, or to take our the detection result of the temperature sensor as a wireless signal using a telemeter. 
     When, however, the rotating device is provided with a slip ring, a maintenance at a constant cycle becomes necessary, increasing the running costs of the device. In addition, when an output signal by the temperature sensor is taken out via the slip ring, the slip ring may affect the output signal, resulting in a noise component contained therein. 
     Conversely, in order to take out the detection result as a wireless signal using the telemeter, it is necessary to ensure a space for placing a wireless transmitter and a battery for the rotator. Hence, the manufacturing costs of the rotating device increase. In addition, the number of measurement locations is limited, resulting in a difficulty in precise measurement of the temperature of the entire rotator in some cases. 
     The temperature of the rotator has a correlation with the temperature of the stator to some level. Hence, the temperature of the rotator is predictable from the temperature of the stator. Depending on the applied environment of the rotating device and the surrounding temperature, however, the predicted temperature may contain an error relative to the actual temperature. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view illustrating a rotating device according to an embodiment; 
         FIG. 2  is a diagram illustrating a YZ cross-section of the rotating device; 
         FIG. 3  is a diagram illustrating an arrangement of a temperature sensor; 
         FIG. 4  is a diagram illustrating a temperature sensor and the surroundings therearound in an enlarged manner; 
         FIG. 5  is a perspective view illustrating a fastener; 
         FIG. 6  is a block diagram illustrating a temperature measuring unit; 
         FIG. 7  is a block diagram illustrating a temperature measuring unit according to a modified example; 
         FIG. 8  is a block diagram illustrating a temperature measuring unit according to a modified example; and 
         FIG. 9  is a diagram illustrating a wiring according to a modified example. 
     
    
    
     DETAILED DESCRIPTION 
     A rotating device according to an embodiment includes a temperature detector disposed on a rotator, a transmitter disposed on a rotation axis of the rotator so as to rotate together with the rotator, and transmitting an output signal that indicates the detection result of the temperature detector, and a receiver supported on the rotation axis of the rotator so as to face the transmitter, and receiving the output signal. 
     An embodiment of the present disclosure will be explained below with reference to the figures.  FIG. 1  is a perspective view of a rotating device  10  according to this embodiment. The rotating device  10  is, for example, a three-phase squirrel cage induction motor. As illustrated in  FIG. 1 , the rotating device  10  includes a cylindrical shaft  20  that has the lengthwise direction which is a Y-axis direction, a motor unit  30  that rotates the shaft  20  around a paraxial axis to the Y-axis, and a terminal box  80  connected to an external power supply, control lines, etc. 
       FIG. 2  is a diagram illustrating a YZ cross-section of the rotating device  10 . As illustrated in  FIG. 2  and also  FIG. 1 , the motor unit  10  includes a pair of bearings  33 ,  34  that support the shaft  20  so an to be in parallel with the Y-axis, a rotator  50  fixed to the shaft  20 , a stator  40  disposed so as to encircle the rotator  50 , a casing  31  that houses therein those components, a temperature measuring unit  60  that includes a transmitter  61 , a receiver  62 , etc., and a cover  32  that covers the temperature measuring unit  60 . 
     The casing  31  is a hollow cylindrical member that has the lengthwise direction which is the Y-axis direction. The bearings  33 ,  34  are fixed at the −Y side of this casing  31  and at the +Y side thereof. The shaft  20  is supported by the bearings  33 ,  34  in a freely rotatable manner with both ends in the Y-axis direction protruding from the casing  31 . 
     The rotator  50  includes a rotator core  53 , a pair of short-circuit rings  52 , and a plurality or rotator bars  51 . 
     The short-circuit ring  52  is an annular member formed of copper, aluminum, etc. The short-circuit rings  52  are disposed at both end of the rotator core  53  in the Y-axis direction with the shaft  20  passing completely through the short-circuit rings  52 . 
     The rotator bar  51  a bar-shape member that has the lengthwise direction which is the Y-axis direction. Like the short-circuit ring the rotator bar  51  is formed of copper, aluminum, etc. The both ends of the rotator bar  51  are respectively fixed to the short-circuit rings  52  by, for example, bolts. 
     The rotator core  53  is formed by laminating, in the Y-axis direction, multiple sheet metals each formed with an opening through which the shaft  20  and the rotator bar  51  pass completely. The sheet metal is, for example, silicon steel sheet. 
     As illustrated in  FIG. 2 , the rotator core  53 , the short-circuit rings  52 , and the rotator bars  51  are integrated one another by disposing the respective short-circuit rings  52  at both ends of the rotator core  53  in the Y-axis direction through which the shaft  20  and the rotator bars  51  pass completely, and by fixing the short-circuit rings  52  and the rotator bars  51  together. 
     The stator  40  is disposed so as to encircle the rotator  50 . The stator  40  includes a stator core, a coil, etc. 
     The temperature measuring unit  60  is to measure the temperature of the rotator  50 . The temperature measuring unit  60  includes the transmitter  61 , the receiver  62 , and a plurality at temperature sensors  63 . 
     The transmitter  61  is a device that transmits the measurement result of the temperature sensor  63  to the receiver  62 . The transmitter  61  includes a coil and a rectifier that generate actuation power for the transmitter  61  from received electromagnetic waves, and an antenna that transmits an output signal indicating the measurement result of the temperature sensor  63 . The transmitter  61  is fixed to the substantial center of the end face of the shaft  20  at the +Y side. Hence, even if the shaft  20  rotates, the transmitter  61  remains at the substantially consistent location. 
     The receiver  62  is supported at the position apart from the transmitter  61  by substantially 1-5 mm an the +Y direction so as to face the transmitter  61 . The receiver  62  includes a coil that transmits electromagnetic waves to the transmitter  61 , and an antenna that receives the output signal by the transmitter  61 . This receiver  62  is actuated by power supplied from, for example, an external DC power supply. The receiver  62  outputs electromagnetic waves to the transmitter  61 , and output a the output signal received from the transmitter  61  to an external device, etc. 
     The temperature sensor  63  is, for example, a thermistor that changes a resistance value in accordance with a temperature. The temperature sensor  63  is pasted en the rotator core  53  that forms the rotator  50 .  FIG. 3  is a diagram illustrating an arrangement of the temperature sensor  63 . As illustrated in  FIG. 3 , according to the rotating device  10 , for example, the four temperature sensors  63  are disposed along the circumference around the shaft  20  at an equal pitch. The respective temperature sensors  63  are connected in series by a cable  65 . 
       FIG. 4  is a diagram illustrating the temperature sensor  63  and the surroundings therearound in an enlarged manner. As illustrated in  FIG. 4 , the cable  65  that interconnects the temperature sensors  63  is placed in, for example, a groove  53   a  formed in the rotator core  53 . By placing the cable in the groove  53   a , a displacement, etc., of the cable  65  caused by the rotation of the rotator  50  can be prevented. 
     In addition, as illustrated in  FIG. 3 , among the four temperature sensors  63  connected in series, the temperature sensors  63  at both ends are connected to the transmitter  61  by a cable  66 . The cable  66  is drawn to the transmitter  61  from the temperature sensor  63  via, for example, the +Y side end face of the rotator core  53  and the interior of the shaft  20 . As for the wiring at the end face of the rotator core  53 , the cable  66  is fixed to the rotator core  53  by, for example, a fastener  530  illustrated in  FIG. 5 . 
     The fastener  530  includes three portions that are a holding portion  530   a  formed in a U-shape, and a pair of fixing portions  530   b  provided at both ends of the holding portion  530   a . The fastener  530  is attached to the rotator core  53  by welding the fixing portions  530   b  to the rotator core  53  or by fixing the fixing portions  530   b  to the rotator core  53  by screws, etc. The fastener  530  is attached to the rotator core  53  along the drawn path of the cable  66 . In addition, the cable  66  is placed inwardly relative to the holding portion  530   a  that forms the fastener  530 . 
       FIG. 6  is a block diagram of the temperature measuring unit  60 . As illustrated in  FIG. 6 , the receiver  62  outputs electromagnetic waves that are converted into actuation power for the transmitter  61 . Simultaneously, the receiver  62  receives the output signal tirelessly transmitted from the transmitter  61 , and outputs the received output signal to the external device like a control device for the rotating device  10 . 
     The transmitter  61  measures the resistance values of the four temperature sensors  63  connected in series with an actuation power that is the power obtained and converted from the electromagnetic waves from the receiver  62 . Next, the wireless signal indicating the measurement result is output to the receiver  62  as an output signal. 
     That is, according to the rotating device  10 , a wireless power supply is performed from the receiver  62  to the transmitter  61 . In addition, using the power that has been wirelessly supplied, the output signal is wirelessly transmitted from the transmitter  61  to the receiver  62 . 
     The value of the output signal from the receiver  62  to the external device changes in accordance with the resistance value of the temperature sensor  63 . Hence, the external device is capable of measuring the temperature of the rotator core  53  that forms the rotator  50  based on the value or the output signal. According to this embodiment, the four temperature sensors  63  are connected in series. Hence, an average value of the temperatures measured by the respective temperature sensors  63  is obtainable from the output signal. 
     When, for example, the respective resistance values of the four temperature sensors  63  are R1, R2, R3, and R4, the output signal indicates the sum ΣR (R1+R2+R3+R4) or the four resistance values. Hence, a temperature corresponding to a value obtained by dividing ΣR by the number of temperature sensors  63  can be measured as the temperature of the rotator  50 . 
     Returning to  FIG. 1 , the terminal box  80  is connected to the power cable from a commercial three-phase power supply, control lines from the external device, etc. The power cable is connected to the winding that forms the stator  40  via the terminal box  80 . In addition, the control lines are connected to the receiver  62  via the terminal box  80 . 
     According to the rotating device  10  that employs the above structure, when power is supplied to the winding of the stator  40  from the commercial power supply, the shaft  20  rotates. At this time, the receiver  62  of the rotating device  10  outputs the output signal that has a value in accordance with the temperature of the rotator core  53  of the rotator  50 . Hence, the external device is capable of monitoring the temperature of the rotator  50  based on this output signal. 
     As explained above, according to the rotating device  10  of this embodiment, a wireless power supply is performed from the receiver  63  to the transmitter  61 , and the transmitter  61  utilizes the wirelessly supplied power to wirelessly transmit the output signal to the receiver  62 . Hence, unlike a case in which the temperature of the rotator  50  is detected using a telemeter, etc., it becomes unnecessary to load a battery, etc., on the rotator  50  to actuate a telemeter. Accordingly, the device structure for the temperature measurement becomes simple, decreasing the manufacturing costs or the rotating device  10 . In addition, a maintenance work at a constant cycle for replacing a battery is unnecessary, reducing the running costs of the rotating device  10 . 
     In this embodiment, power feeding and signal transmission between the transmitter  61  and the receiver  62  are performed wirelessly. Hence, in comparison with a case in which the signal from the temperature sensor  63  is detected via a slip ring, an adverse effect of noises is little, enabling a precise temperature measurement. 
     In this embodiment, the temperature sensors  63  pasted on the rotator  50  directly measure the temperature of the rotator  50 . Hence, in comparison with a scheme of predicting the temperature of the rotator  50  in accordance with the temperature of the stator and the loaded power, a precise temperature of the rotator  50  is obtainable. Accordingly, an overloading of the rotating device  10  and a defective like overheating of the rotator  50  are precisely detectable. This improves the safety of the rotating device  10  under the explosion-proof environment. 
     Although the embodiment, of the present disclosure has been explained above, the present disclosure is not limited to the above embodiment. For example, in the above embodiment, as illustrated in  FIG. 6 , the explanation has been given of an example case in which the four temperature sensors  63  are connected in series. However, as illustrated in  FIG. 7 , for example, five or more temperature sensors may be connected in series. This increases the number of measurement locations. 
     In the above embodiment, the explanation has been given or an example case in which the temperature sensors  63  are connected in series. However, the temperature sensors  63  may be connected in parallel. When, for example, the temperature sensors  63  are connected in series, and when the cable  63  connected to the temperature sensors  63  is disconnected, a temperature measurement is disabled. When, however, the temperature sensors  63  are connected in parallel, even if the cable  65  becomes disconnected, a temperature measurement is still enabled. 
     In the above embodiment, as illustrated in  FIGS. 6   7 , the explanation has been given or an example case in which the temperature sensor group including the plurality of temperature sensors  63  mutually connected in series or in parallel is connected to the transmitter  61 . When, however, the transmitter  61  has multiple channels to output the output signal, as illustrated in  FIG. 8 , dual temperature sensor groups or equal to or greater than triple temperature sensor groups may be connected to the transmitter  61 . According to this structure, when the cable for the one temperature sensor group is disconnected or the temperature sensor is disconnected or short-circuited, the temperature or the rotator  50  is still measurable based on the measurement result from the other temperature sensor group. In addition, by disposing the temperature sensors  63  at different locations for each temperature sensor group, a local temperature rise of the rotator  50  is detectable. 
     In the above embodiment, the explanation has been given of an example case in which the temperature sensor  63  is a thermistor. However, various sensors, such as a thermocouple and a measured temperature resistor, may be applied as the temperature sensor. 
     In the above embodiment, the explanation has been given of an example case in which the rotating device  10  is a squirrel cage induction motor. However, the rotating device  10  may be rotating devices, such as an induction motor that has windings wound around the rotator, and a synchronous motor. Alternatively, the rotating device may be a rotating device like a power generator. 
     In the above embodiment, as illustrated in  FIG. 3 , the explanation has been given of an example case in which the cable  65  that interconnects the temperature sensors  63  and the cable  66  that connects the temperature sensors  63  and the transmitter  61  are placed on the surface of the rotator core which forms the rotator  50 . However, for example, as illustrated in  FIG. 9 , the cables  65 ,  66  maybe placed in the rotator core  53  or the interior of a duct for cooling the rotator core  53  by air. 
     In the above embodiment, as illustrated in  FIG. 3 , the explanation has been given of an example case in which the temperature sensors  63  are pasted on the surface of the rotator core  53 . However, the temperature sensors  63  may be disposed in the rotator core  53 . 
     In the above embodiment, the rotating device  10  is provided with the terminal box  80  that is to connect both the power cable and the control lines. However, the rotating device  10  may be provided with multiple terminal boxes, such as a terminal box to connect the power cable, and a terminal box to connect the control lines. 
     While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the invention. Indeed, the novel embodiments described herein may be embodied in a variety of other forms. Furthermore, various omissions, substitutions and changes in the form of the embodiments described herein maybe made without departing from the spirit of the invention. The accompanying claims end their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the invention.