JP2018128028A - Cooling unit and cooling system including the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cooling unit which can cool a bearing without using a cooling device which receives power or electric power from the outside.SOLUTION: A cooling unit includes: a power generation part 95 which generates power by a temperature difference between an inner ring and an outer ring of a bearing; cooling parts 94A, 94B which use the electric power generated by the power generation part 95 to cool the bearing; and a spacer which houses the power generation part 95 and the cooling parts 94A, 94B. The spacer includes: an inner ring spacer 34 which contacts with the inner ring; and an outer ring spacer 33 which contacts with the outer ring. The power generation part 95 includes: a power generation element 25 which utilizes seebeck effect caused by a temperature difference to generate power; and a first heat sink 96 which contacts with a first surface of the power generation element 25. A second surface of the power generation element 25 contacts with the outer ring spacer 33, and heat of the outer ring is conducted by the outer ring spacer 33. The cooling parts 94A, 94B include cooling elements 90A, 90B which utilize peltier effect to perform cooling.SELECTED DRAWING: Figure 8

Description

  The present invention relates to a cooling unit that cools a bearing, and more specifically, a cooling unit that generates power by using a temperature difference generated in the bearing and cools the bearing by effectively using the generated power, and a cooling including the cooling unit. About the system.

  Bearings used for machine tool spindles and the like generate a large amount of heat because they rotate at high speed. Therefore, a cooling device is provided outside the spindle to forcibly cool (water cooling, oil cooling) from the outside.

  Japanese Patent Laying-Open No. 2014-62616 (Patent Document 1) discloses a cooling structure for a bearing device that cools an inner ring using compressed air. This prior art cooling structure discharges compressed air into the housing by connecting piping from a compressor or the like installed outside the bearing housing.

JP 2014-62616 A

  In the cooling structure disclosed in Japanese Patent Application Laid-Open No. 2014-62616, installation cost and space for a compressor and the like are required, and costs for piping work and the like are required.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a cooling unit that can cool a bearing without using a cooling device that receives power or electric power from the outside, and the cooling unit. A cooling system is provided.

  A cooling unit that cools a bearing according to the present disclosure includes a power generation unit that generates power based on a temperature difference between an inner ring and an outer ring of the bearing, and a cooling unit that cools the bearing using electric power generated by the power generation unit.

  Preferably, the cooling unit further includes a spacer that houses the power generation unit and the cooling unit. The spacer includes an inner ring spacer that contacts the inner ring and an outer ring spacer that contacts the outer ring. The power generation unit has a first surface and a second surface, a power generation element that generates power using the Seebeck effect from a temperature difference between the first surface and the second surface, and a first surface that contacts the first surface of the power generation element Including heat sink. The second surface of the power generation element abuts on the outer ring spacer, and heat of the outer ring is conducted by the outer ring spacer.

More preferably, the cooling unit includes a cooling element that performs cooling using the Peltier effect.
More preferably, the cooling element has a third surface that becomes a high temperature side and a fourth surface that becomes a low temperature side when a current is passed. The cooling unit further includes a second heat sink that contacts the third surface of the cooling element. The cooling element is disposed such that the fourth surface is in contact with the outer ring spacer.

  More preferably, the cooling unit further includes a second heat sink that contacts the outer ring. The cooling element has a third surface that becomes a high temperature side and a fourth surface that becomes a low temperature side when a current is passed. The cooling element is arranged such that the fourth surface contacts the second heat sink and the third surface contacts the first heat sink.

  More preferably, the cooling element has a third surface that becomes a high temperature side and a fourth surface that becomes a low temperature side when a current is passed. The cooling unit further includes a second heat sink that contacts the fourth surface of the cooling element. The cooling element is disposed such that the third surface is in contact with the outer ring spacer.

  Preferably, the cooling unit includes a power supply circuit that boosts the power generated by the power generation unit, a power storage device that is charged with a voltage boosted by the power supply circuit, and a threshold value that is set for the power storage voltage of the power storage device. A discharge controller is further provided for discharging at the time of reaching and setting the voltage after discharge according to the temperature of the bearing.

  Preferably, the cooling unit includes a temperature sensor that detects the temperature of the bearing, a memory that stores information on the temperature detected by the temperature sensor, and a light emitting unit that transmits the information stored in the memory by infrared communication. Further prepare.

  The cooling system according to the present disclosure includes any one of the cooling units described above and a temperature monitoring unit disposed outside the apparatus in which the bearing is used. The temperature monitoring unit includes a light receiving unit that receives infrared light from the light emitting unit, a display unit that displays information, and a monitoring control unit that controls the light receiving unit and the display unit.

  Preferably, the temperature history of the bearing is transmitted from the light emitting unit to the temperature monitoring unit by infrared communication. The monitoring control unit displays the temperature history on the display unit.

  More preferably, the light receiving unit in the temperature monitoring unit is kept in a constantly operating state. When the infrared ray from the light emitting unit is received, the monitoring control unit in the temperature monitoring unit is activated. The monitoring control unit records the temperature history in the memory, and then enters the sleep state again.

  More preferably, the temperature monitoring unit includes a switch. In response to the operation of the switch, the monitoring controller starts from the sleep state, displays the temperature history of the rolling bearing recorded in the memory on the liquid crystal monitor, and again enters the sleep state after a predetermined time.

  Preferably, the light receiving unit and the light emitting unit perform infrared communication using a through hole provided in the cooling unit, the outer ring spacer and the spindle housing as an optical axis of infrared light.

  In the present invention, the bearing can be cooled by effectively using the power generated by the temperature difference between the bearing inner and outer rings.

It is a cross-sectional schematic diagram which shows an example of the mechanical apparatus which concerns on this embodiment. It is a cross-sectional schematic diagram of the mechanical apparatus shown in FIG. It is the top view and sectional drawing of the temperature monitoring unit 70 attached to the machine apparatus shown in FIG. It is a block diagram for demonstrating schematic structure of the control board of the cooling unit in a cooling system, and the control board of an external unit. It is a flowchart for demonstrating the 1st example of starting of the monitoring control part 80 of a temperature monitoring unit, and the transfer to a sleep state. It is a flowchart for demonstrating the 2nd example of starting of the monitoring control part 80 of a temperature monitoring unit, and the transfer to a sleep state. It is a figure which shows a series of flows from the electric power generation of a cooling unit to cooling. FIG. 3 is a diagram illustrating an arrangement of components of the cooling unit according to the first embodiment. It is sectional drawing in IX-O-IX of FIG. It is a figure which shows arrangement | positioning of the component of the cooling unit of Embodiment 2. FIG. It is sectional drawing in XI-O-XI of FIG. It is a fragmentary sectional view of the cooling part in XII-XII of FIG. It is a figure which shows a time-dependent change of a bearing outer ring side temperature and an electrical storage voltage. 5 is a flowchart showing a cooling (discharge) start determination process executed by a microcomputer of a control circuit 27. 5 is a flowchart showing a cooling (discharge) stop determination process executed by a microcomputer of a control circuit 27;

  Embodiments of the present invention will be described below with reference to the drawings. In the following drawings, the same or corresponding parts are denoted by the same reference numerals, and description thereof will not be repeated.

[Embodiment 1]
<Configuration of mechanical device>
With reference to FIGS. 1-3, the structure of the spindle for machine tools which is an example of the machine apparatus to which the cooling device of the bearing which concerns on this embodiment is applied is demonstrated.

  FIG. 1 is a schematic cross-sectional view illustrating an example of a mechanical device according to the present embodiment. FIG. 2 is a schematic cross-sectional view of the mechanical device shown in FIG.

  With reference to FIGS. 1 and 2, a machine tool spindle 50 according to this embodiment includes a rotation shaft 51, a spindle housing 52 arranged to surround the rotation shaft 51, and an outer periphery of the spindle housing 52. It includes an outer peripheral housing 53 that is arranged, and a bearing device that rotatably holds the rotating shaft 51 with respect to the spindle housing 52.

  Two bearing devices are arranged on the outer periphery of the rotating shaft 51. The inner ring 14 and the inner ring spacer 34 of the bearing in the bearing device are fitted and fixed to the side surface of the rotating shaft 51. Further, the outer ring 13 of the bearing and the outer ring spacer 33 are fitted and fixed to the inner peripheral surface of the spindle housing 52. The bearing including the inner ring 14, the outer ring 13, and the rolling elements 15 that are balls disposed between the inner ring 14 and the outer ring 13 is an angular ball bearing.

  The cooling unit 20 is arranged between the inner ring spacer 34 and the outer ring spacer 33 arranged so as to be adjacent to the bearing. Further, between the two bearings (on the side opposite to the side where the cooling unit 20 is disposed), other spacers are fitted and fixed to the rotating shaft 51 and the spindle housing 52, and the inner ring 14 and the outer ring 13 are connected. It has been hit.

  As shown in FIG. 2, the cooling unit 20 includes a control circuit 27 disposed in an annular housing. Cooling unit 20 further includes a power generation unit, a power supply circuit including a power storage unit, and a cooling unit. The detailed configuration of the bearing device including the cooling unit 20 will be described later.

  In a region facing the control circuit 27 of the cooling unit 20, a through hole penetrating the housing 97 (see FIG. 8), the outer ring spacer 33, the spindle housing 52 and the outer peripheral housing 53 of the cooling unit is formed. A flat portion for fixing the temperature monitoring unit 70 on the surface of the outer peripheral housing 53 is provided at the outer peripheral side end portion of the through hole, and a pedestal 57 is disposed on the flat portion. A substrate 56 is disposed on the pedestal 57.

  The control circuit 27 of the cooling unit 20 is connected to the light emitting element 54. The substrate 56 is connected to the light receiving element 55. For example, the light emitting element 54 is mounted on the control board on which the control circuit 27 is formed, and the light receiving element 55 is mounted on the board 56.

  The light emitting element 54 and the light receiving element 55 are arranged to face each other with the through hole interposed therebetween so that the light emitted from the light emitting element 54 is received by the light receiving element 55 through the through hole. That is, the light emitting element 54 and the light receiving element 55 are arranged so that the optical axis of the light emitted from the light emitting element 54 passes through the through hole. The light transmitted and received between the light emitting element 54 and the light receiving element 55 may have an arbitrary wavelength, but is, for example, infrared light (infrared light). In other words, the light-emitting element 54 is provided so that, for example, infrared light is used as a carrier wave and light on which a signal wave including information related to the temperature of a bearing, which will be described later, is superimposed can be emitted toward the light-receiving element 55. As the light emitting element 54, for example, an infrared light emitting diode is used. As the light receiving element 55, for example, a photodiode is used. The transmission / reception of temperature information may be communication using other light instead of infrared light instead of infrared communication, or communication using radio waves.

  FIG. 3 is a plan view and a sectional view of the temperature monitoring unit 70 attached to the machine apparatus shown in FIG. Referring to FIGS. 2 and 3, cover member 58 is fixed to pedestal 57 so as to cover substrate 56 disposed on pedestal 57. On the substrate 56, a battery 62, which is a power source for driving the circuit of the substrate 56, a monitoring control unit 80, and a liquid crystal monitor 64 are arranged. As the battery 62, for example, a coin-type battery or a button-type battery can be used. Although it is desirable to use a lithium ion battery as the battery 62, other batteries such as a nickel metal hydride battery may be used. A battery holder for fixing such a battery 62 is disposed on the surface of the substrate 56.

  The cover member 58 is formed with a U-shaped elongated hole (a hole in which the fixing bolt is disposed) so that the cover member 58 can be removed from the pedestal 57 simply by loosening the fixing bolt as a connecting member with the pedestal 57. The replacement of the battery 62 can be performed with the cover member 58 removed from the pedestal 57.

  A substrate 56 accommodated in a space sealed by the pedestal 57 and the cover member 58 constitutes a main part of the external unit. The pedestal 57 and the cover member 58 can be added with an arbitrary waterproof structure in order to prevent intrusion of coolant or the like used during processing using the processing machine spindle. As the waterproof structure, for example, packing, O-ring, caulking, resin mold or the like can be used.

  The cover member 58 is preferably provided with a confirmation window so that the display content of the liquid crystal monitor 64 can be visually recognized, or a transparent material is used. Instead of providing the liquid crystal monitor 64, data may be transferred to the outside of the temperature monitoring unit 70 by wireless communication. In this case, a transmitter that performs communication using a wireless LAN (Wi-Fi (registered trademark)), Bluetooth (registered trademark), ZigBee (registered trademark), etc. is prepared, and data indicating the temperature monitoring result on a personal computer or the like May be taken in.

  FIG. 4 is a block diagram for explaining a schematic configuration of the control board of the cooling unit and the control board of the external unit in the cooling system.

  Referring to FIG. 4, microcomputer 59 and light emitting element 54 are mounted on the substrate of control circuit 27 of the cooling unit. The microcomputer 59 is connected to the temperature sensor 9 and can acquire the temperature detected by the temperature sensor 9.

  A battery 62, a monitoring controller 80, a light receiving element 55, a liquid crystal monitor 64, and a switch 66 are mounted on the substrate 56 of the external unit.

  The monitoring control unit 80 includes a light receiving monitoring unit 82 that constantly monitors the light receiving element 55, a CPU 86 that is activated from the sleep state by the light receiving monitoring unit 82, and a memory 84 that stores temperature information of the bearing received by the light receiving element 55. including.

  The light receiving element 55 mounted on the substrate 56 in the temperature monitoring unit 70 receives the signal transmitted from the light emitting element 54 and records information in the memory 84 of the monitoring control unit 80.

  However, the CPU 86 in the temperature monitoring unit 70 is set so as to maintain the normal sleep state and to be activated at the timing when the light receiving element 55 and the light receiving monitoring unit 82 receive the signal. The light receiving element 55 and the light reception monitoring unit 82 always stand by in a reception state.

  FIG. 5 is a flowchart for explaining a first example of activation of the monitoring control unit 80 of the temperature monitoring unit and transition to the sleep state. Referring to FIG. 5, monitoring control unit 80 determines whether or not infrared light is received in step S1. If the light reception monitoring unit 82 confirms light reception in step S1, the CPU 86 is activated in step S2. The CPU 86 receives the temperature information from the light emitting element 54 in step S3, and stores the received temperature information in the memory 84 in step S4. When the recording of information in the memory 84 is completed, the CPU 86 shifts to the sleep state again in step S5.

  Further, when the operator who handles the apparatus wants to check the bearing outer ring side temperature, by operating the confirmation switch 66, the CPU 86 is activated and the liquid crystal monitor 64 is operated to display the information.

  FIG. 6 is a flowchart for explaining a second example of activation of the monitoring control unit 80 of the temperature monitoring unit and transition to the sleep state. Referring to FIG. 6, when switch 66 is operated in step S11 (YES in S11), CPU 86 starts in S12, and reads temperature information from memory 84 in step S13. In step S14, the temperature history is displayed on the liquid crystal monitor 64. The display on the liquid crystal monitor 64 is continued until a predetermined time has elapsed in step S15 (NO in S15).

  If the predetermined time has elapsed in step S15 (YES in S15), the CPU 86 turns off the liquid crystal monitor 64 and shifts to the sleep state again in step S17.

  Thus, by putting the CPU 86 and the liquid crystal monitor 64 in the sleep state in the standby state, power consumption can be reduced.

  In the first embodiment, the following configuration is adopted so that the bearing outer ring side temperature can be monitored from the outside of the apparatus (spindle) incorporating the unit.

  First, an infrared light emitting element is mounted on a control board inside the cooling unit, a through hole is provided from the unit to the outer peripheral surface of the spindle housing, and a temperature monitoring unit is provided on the outer peripheral surface. An infrared light receiving element is mounted on the substrate inside the temperature monitoring unit. Second, temperature information is transmitted from the infrared light emitting element and received by the infrared light receiving element. Third, the temperature information is displayed on a liquid crystal monitor mounted on the control board of the temperature monitoring unit. Fourthly, the temperature information makes it possible to know the history so far.

  With this configuration, the temperature on the bearing outer ring side can be monitored outside the unit, so that the reliability of the bearing device is improved and the time for maintenance can be grasped.

<Details of configuration of bearing device and cooling system>
With reference to FIGS. 7-9, the detail of the bearing apparatus and the cooling unit 20 which are used for the mechanical apparatus shown in the said FIG. 1 is demonstrated.

  FIG. 7 is a diagram showing a series of flow from power generation to cooling of the cooling unit. Referring to FIG. 7, cooling unit 20 includes thermoelectric elements (for power generation) 5, power supply circuit 26, control circuit 27, thermoelectric elements (for cooling) 90, power storage device 92, and temperature sensor 9. including.

  The inner and outer rings of the bearing cause a temperature difference relative to the rotation, and the temperature of the inner ring 14 is higher than that of the outer ring 13. The thermoelectric element 25 generates power based on this temperature difference.

The electric power generated by the thermoelectric element 25 is input to the power supply circuit 26 and boosted to a constant voltage. The electric power boosted to a constant voltage is input to the microcomputer or the like of the control circuit 27, and at the same time, charged or stored in a secondary battery or an electric double layer capacitor of the power storage device 92. Further, the stored electric power is input to the control circuit 27. The electric power stored in the power storage device 92 is supplied to the thermoelectric element 90 (for cooling) of the cooling unit by microcomputer control or the like. (Time conditions regarding cooling can be arbitrarily set in advance.)
On the other hand, the output signal of the temperature sensor 9 for detecting the outer ring side temperature is input to the microcomputer of the control circuit 27 and the like.

  Threshold values Vth and Tth are provided for the voltage after storage and the output signal of the temperature sensor, respectively, and when both exceed the threshold value, power is supplied from the control circuit 27 to the thermoelectric element 90 for cooling. A temperature difference is generated in the bearing to cool the outer ring side of the bearing. Further, the outer ring side of the bearing is cooled, thereby generating a temperature difference between the inner ring and the outer ring of the bearing, which contributes to power generation by the thermoelectric element 25.

  FIG. 8 is a diagram illustrating an arrangement of components of the cooling unit according to the first embodiment. FIG. 9 is a cross-sectional view taken along the line IX-O-IX in FIG.

  As shown in FIGS. 8 and 9, the outer peripheral surface of the cooling unit 20 is fixed to the inner peripheral surface of the outer ring spacer 33 that is in contact with the end surface of the outer ring 13 of the rolling bearing.

  The cooling unit 20 is an annular housing 97 made of a thermoplastic resin such as PPS (Poly Phenylene Sulfide) resin, and one end in the axial direction is opened and sealed by a lid 99 made of the same kind of material. The lid 99 is fixed to the housing 97 with screws. Further, the cooling unit 20 may be fixed to the bearing stationary ring (outer ring 13).

  Inside the housing 97 of the cooling unit 20, a power generation unit 95, cooling units 94A and 94B, a power supply circuit 26, a control circuit 27, a power storage device 92, a temperature sensor 9, and the like are accommodated along the circumferential direction.

  A thermoelectric element 25 that generates electric power (Seebeck effect) due to a temperature difference is disposed in the power generation unit 95, and a heat conductor (heat sink) 96 is tightly fixed to the high temperature side of the thermoelectric element 25. In addition, the inner peripheral surface of the outer ring spacer 33 is tightly fixed to the low temperature side of the thermoelectric element 25.

  On the other hand, thermoelectric elements 90A and 90B that generate a temperature difference (Peltier effect) by power supply are arranged in the cooling units 94A and 94B, respectively, and heat conductors (heat sinks) 91A and 91B are disposed on the high temperature side of the thermoelectric elements 90A and 90B. Are firmly fixed to each other. Further, the low temperature side of the thermoelectric elements 90 </ b> A and 90 </ b> B is closely fixed to the inner peripheral surface of the outer ring spacer 33.

  The compression coil spring 98 is disposed between the inner peripheral wall of the housing 97 and the heat conductors 96, 91A, 91B. The heat conductors 96, 91 </ b> A, 91 </ b> B are pressed in the outer diameter direction by the repulsive force of the compression coil spring 98, and the thermoelectric elements 25, 90 </ b> A, 90 </ b> B are more closely fixed to the inner peripheral surface of the outer ring spacer 33. Further, the temperature sensor 9 is tightly fixed to the inner peripheral surface of the outer ring spacer 33.

  Note that the inner diameter of the heat conductor 96 of the power generation unit is not in contact with the inner ring spacer 34. If possible, it is desirable to increase the surface area of the heat conductor 96.

  Further, between the inner peripheral surface of the outer ring spacer 33 and the thermoelectric element 25, between the thermoelectric element 25 and the heat conductor 96, between the thermoelectric elements 90A, 90B and the heat conductors 91A, 91B, the thermoelectric elements 90A, In order to improve thermal conductivity (and adhesion) between 90B and the inner peripheral surface of the outer ring spacer 33, heat radiation grease or the like may be applied. Generally, the heat dissipating grease is mainly composed of silicone.

In the first embodiment described above, the cooling unit is mounted on the inner peripheral surface of the outer ring spacer, and the following features (1) to (6) are provided.
(1) A high-temperature side heat conductor and a thermoelectric element for power generation are arranged as a set, and power is generated by the difference between the temperature on the bearing inner ring side and the temperature on the outer ring side.
(2) The high temperature side heat conductor and the cooling thermoelectric element are arranged as a set, and the power obtained by the power generation is supplied to the cooling thermoelectric element, thereby cooling the bearing outer ring side.
(3) A temperature sensor is arranged on the bearing outer ring side to detect the temperature on the bearing outer ring side.
(4) A power supply circuit is provided for boosting the voltage generated by the thermoelectric element.
(5) A storage circuit (including a capacitor or the like) for storing the power generated by the thermoelectric element is provided.
(6) A control circuit (including a microcomputer) for supplying the stored electric power to the cooling thermoelectric element is provided.

  The cooling unit of the present embodiment having the above characteristics supplies power generated by the thermoelectric element for power generation in the unit to the thermoelectric element for cooling, so that no external power or external device is required, and the apparatus is compact. And contribute to energy saving.

  In addition, by appropriately setting the cooling start time on the bearing outer ring side, the cooling time, the interval, and the like, it is possible to perform optimal cooling according to the use environment. Thereby, the abnormal heat generation of the bearing can be effectively suppressed, and the life of the bearing can be extended.

[Embodiment 2]
The second embodiment is slightly different from the first embodiment in the arrangement of the cooling unit. FIG. 10 is a diagram illustrating an arrangement of components of the cooling unit according to the second embodiment. 11 is a cross-sectional view taken along the line XI-O-XI in FIG. FIG. 12 is a partial cross-sectional view of the cooling unit in XII-XII of FIG.

  As shown in FIGS. 10 to 12, the outer peripheral surface of the cooling unit 20 </ b> A is fixed to the inner peripheral surface of the outer ring spacer 33 that is in contact with the end surface of the outer ring 13 of the rolling bearing.

  The cooling unit 20A is an annular housing 97 made of a thermoplastic resin such as PPS, and one end in the axial direction is opened, and the cooling unit 20A is sealed by a lid 99 made of the same kind of material. The lid 99 is fixed to the housing 97 with screws. Further, the cooling unit 20A may be fixed to the bearing stationary ring (outer ring 13).

  Inside the housing 97 of the cooling unit 20A, a power generation unit 195, a cooling unit, a power supply circuit 26, a control circuit 27, a power storage device 92, a temperature sensor 109, and the like are housed.

  A thermoelectric element 25 that generates power due to a temperature difference is disposed in the power generation unit 195, and a thermal conductor 196 (heat sink) is closely fixed to the high temperature side of the thermoelectric element 25. On the other hand, the low temperature side of the thermoelectric element 25 is tightly fixed to the inner peripheral surface of the outer ring spacer 33.

  When the heat conductor 196 is pressed in the outer diameter direction by the repulsive force of the compression coil spring 98, the thermoelectric element 25 is more closely fixed to the inner peripheral surface of the outer ring spacer 33. The thermoelectric element 190 of the cooling unit is sandwiched between the heat conductor 196 and the heat conductor 191. The heat conductor 196 is integrally formed with the heat conductor on the high temperature side of the power generation unit 195, the heat conductor 191 on the low temperature side is tightly fixed to the end face of the outer ring 13, and the low temperature side of the thermoelectric element 190 is thermally conductive. The body 191 is tightly fixed. In the second embodiment, the heat conductor 196 is pressed by the compression coil spring 198 in the end face direction of the outer ring 13 simultaneously with the pressing of the compression coil spring 98, thereby improving the adhesion of the cooling unit.

Further, the temperature sensor 109 is fixed to the heat conductor 191 in close contact.
Note that the inner diameter of the heat conductor 196 of the power generation unit is not in contact with the inner ring spacer 34. If possible, it is desirable to increase the surface area of the heat conductor 196.

  Further, between the inner peripheral surface of the outer ring spacer 33 and the thermoelectric element 25, between the thermoelectric element 25 and the heat conductor 196, between the thermoelectric element 190 and the heat conductor 196, and between the thermoelectric element 190 and the heat conductor 191. In order to increase thermal conductivity (and adhesion) between the end face of the outer ring 13 and the heat conductor 191, heat radiation grease or the like may be applied.

  FIG. 13 is a graph showing changes over time in the bearing outer ring side temperature and the stored voltage. As the bearing rotates, the inner ring temperature Tin and the outer ring temperature Tout rise from time t1, and the inner ring side temperature Tin with poor heat dissipation becomes higher than the outer ring side temperature Tout with good heat dissipation. It is generally known that when both temperatures reach a certain temperature, they are saturated at Tin1 and Tout1, respectively, when the bearing lubrication state is normal.

  In the example in which the cooling unit shown in the first and second embodiments is mounted, power generation is started by the relative temperature difference between the bearing inner and outer rings, and the generated power increases as the temperature difference increases. When the electric power is continuously stored in the power storage device, the power storage device is fully charged at a constant voltage. Here, threshold values are provided for both the bearing outer ring side temperature and the stored voltage (bearing outer ring side temperature threshold TA and stored voltage threshold VB). FIG. 13 shows an example in which the bearing outer ring side temperature Tout reaches the threshold TA earlier than the stored voltage V reaches the threshold VB.

  FIG. 14 is a flowchart showing a cooling (discharge) start determination process executed by the microcomputer of the control circuit 27. As shown in FIG. 14, the microcomputer 59 determines whether or not the stored voltage V is higher than the threshold value VB in step S21, and determines whether or not the bearing outer ring temperature Tout is higher than the threshold value TA in step S22. . When V> VB and Tout> TA are satisfied (YES in S21 and S22), in step S23, the microcomputer 59 starts cooling (discharging). Note that the process of step S22 is not necessarily performed.

  FIG. 15 is a flowchart showing a cooling (discharge) stop determination process executed by the microcomputer of the control circuit 27. As shown in FIG. 15, the microcomputer 59 determines whether or not cooling (discharge) is currently being performed in step S <b> 31. In step S32, it is determined whether or not the storage voltage V is lower than the threshold value VC. If the condition of V <VC is satisfied during cooling (discharge) (YES in S31 and S32), microcomputer 59 stops cooling (discharge) in step S33.

  Referring back to FIG. 13 again, the microcomputer 59 in the control circuit 27 starts supplying power from the power storage device 92 to the thermoelectric element 90 at time t3, triggered by both reaching the threshold value. When the cooling is started, the storage voltage V decreases, and the bearing inner ring side temperature Tin and the outer ring side temperature Tout also decrease. When discharging for a certain period of time is completed at time t4 by setting a timer or the like inside the microcomputer, charging and storage are subsequently performed from time t4 to t5. When the cooling is completed, the bearing inner ring side and outer ring side temperatures rise again at times t4 to t5.

  On the other hand, a cycle in which discharge (cooling) is started when the power storage device 92 reaches full charge regardless of the temperature may be used. In this case, a temperature sensor is unnecessary.

  The completion of the discharge may be performed by a program that is automatically determined and determined by the microcomputer based on the value of the temperature sensor. Thereby, the bearing temperature can be controlled.

[Embodiment 3]
In the first embodiment, the low temperature side of the thermoelectric elements 90A and 90B is brought into close contact with the outer ring spacer 33, and the high temperature side is brought into close contact with the heat conductors (heat sinks) 91A and 91B. In the third embodiment, the high temperature side of the thermoelectric elements 90A and 90B in FIG. 6 is in close contact with the outer ring spacer 33, and the low temperature side is in close contact with the heat conductors (heat sinks) 91A and 91B.

  As a result, the temperature difference between the inner ring and the outer ring is reduced, and the temperature of the inner ring that is difficult to cool can be lowered. Although the temperature of the outer ring rises, the outer ring is easy to cool, so it can be expected that the temperature of the bearing as a whole decreases.

In the third embodiment, the temperature of the inner ring can be lowered as compared with the prior art.
The bearing to which the cooling unit is applied in the first to third embodiments described above may be a deep groove ball bearing, an angular ball bearing, a cylindrical roller bearing, or the like in which a desired amount of grease is sealed in advance. A plurality of power generation units and cooling units may be provided.

  Since the cooling unit uses electric power generated by the temperature difference between the inner and outer rings of the bearing, it is not necessary to supply electric power from the outside. Therefore, there is no routing of wires from the spindle body to the machine tool body.

  Moreover, each heat conductor (heat sink) uses a metal with high heat conductivity. For example, examples of the heat conductor include gold, silver, and copper, but copper is generally used from the viewpoint of cost. A copper alloy mainly composed of copper may be used. As processing methods, sintering, forging, casting, etc. are advantageous in terms of cost.

  In the case of a spindle for machine tools, the outer peripheral side of the bearing housing is often constantly cooled with cooling water or cooling oil, and can be used in combination with such equipment. Can be expected.

  Although the embodiment of the present invention has been described above, the above-described embodiment can be variously modified. The scope of the present invention is not limited to the above-described embodiment. The scope of the present invention is defined by the terms of the claims, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  9,109 Temperature sensor, 13 Outer ring, 14 Inner ring, 15 Rolling element, 20, 20A Cooling unit, 25, 90, 90A, 90B, 190 Thermoelectric element, 26 Power supply circuit, 27 Control circuit, 33 Outer ring spacer, 34 Between inner ring Seat, 50 spindle for machine tool, 51 rotating shaft, 52 spindle housing, 53 outer peripheral housing, 54 light emitting element, 55 light receiving element, 56 substrate, 57 base, 58 cover member, 59 microcomputer, 62 battery, 64 liquid crystal monitor, 66 Switch, 70 Temperature monitoring unit, 80 Monitoring control unit, 82 Light reception monitoring unit, 84 Memory, 91A, 91B, 96, 191, 196 Thermal conductor, 92 Power storage device, 94A, 94B Cooling unit, 95, 195 Power generation unit, 97 Housing, 98,198 compression coil spring, 99 lid.

Claims (14)

A cooling unit for cooling the bearing,
A power generation unit that generates power by a temperature difference between the inner ring and the outer ring of the bearing;
A cooling unit comprising: a cooling unit that cools the bearing using electric power generated by the power generation unit. A spacer for accommodating the power generation unit and the cooling unit;
The spacer is
An inner ring spacer that contacts the inner ring;
An outer ring spacer that contacts the outer ring,
The power generation unit
A power generating element having a first surface and a second surface, and generating power using a Seebeck effect from a temperature difference between the first surface and the second surface;
A first heat sink contacting the first surface of the power generating element,
The cooling unit according to claim 1, wherein the second surface of the power generation element abuts on the outer ring spacer, and heat of the outer ring is conducted by the outer ring spacer.   The cooling unit according to claim 2, wherein the cooling unit includes a cooling element that performs cooling using a Peltier effect. The cooling element has a third surface that becomes a high temperature side and a fourth surface that becomes a low temperature side when a current is passed therethrough,
The cooling unit further includes a second heat sink contacting the third surface of the cooling element,
The cooling unit according to claim 3, wherein the cooling element is disposed such that the fourth surface is in contact with the outer ring spacer. A second heat sink that contacts the outer ring;
The cooling element has a third surface that becomes a high temperature side and a fourth surface that becomes a low temperature side when a current is passed therethrough,
The cooling unit according to claim 3, wherein the cooling element is disposed such that the fourth surface abuts on the second heat sink and the third surface abuts on the first heat sink. The cooling element has a third surface that becomes a high temperature side and a fourth surface that becomes a low temperature side when a current is passed therethrough,
The cooling unit further includes a second heat sink contacting the fourth surface of the cooling element,
The cooling unit according to claim 3, wherein the cooling element is disposed such that the third surface is in contact with the outer ring spacer. A power supply circuit for boosting the power generated by the power generation unit;
A power storage device charged with a voltage boosted by the power supply circuit;
A discharge control unit that sets a threshold value for the storage voltage of the power storage device, discharges when the storage voltage reaches the threshold value, and sets the voltage after the discharge according to the temperature of the bearing. The cooling unit according to any one of the above. A temperature sensor for detecting the temperature of the bearing;
A memory for storing information on the temperature detected by the temperature sensor;
The cooling unit according to any one of claims 1 to 7, further comprising a light emitting unit for transmitting the information stored in the memory by infrared communication. The cooling unit includes a cooling element that performs cooling using the Peltier effect,
The cooling unit is
A temperature sensor for detecting the temperature of the bearing;
A power supply circuit for boosting the power generated by the power generation unit;
A power storage device charged with a voltage boosted by the power supply circuit,
2. The cooling unit according to claim 1, wherein a current flows through the cooling element when a storage voltage of the power storage device reaches a threshold voltage and when a temperature of the temperature sensor reaches a threshold temperature. A cooling unit according to claim 8;
A temperature monitoring unit disposed outside the device in which the bearing is used;
The temperature monitoring unit is
A light receiving portion for receiving infrared light from the light emitting portion;
A display unit for displaying the information;
A cooling system including a light receiving unit and a monitoring control unit that controls the display unit. The temperature history of the bearing is transmitted from the light emitting unit to the temperature monitoring unit by infrared communication,
The cooling system according to claim 10, wherein the monitoring control unit displays the temperature history on the display unit. The light receiving unit in the temperature monitoring unit is always kept in an operating state, and by receiving infrared rays from the light emitting unit, the monitoring control unit in the temperature monitoring unit is activated,
The cooling system according to claim 11, wherein the monitoring control unit records the temperature history in the memory, and then enters a sleep state again. The temperature monitoring unit includes a switch,
The monitoring control unit starts from a sleep state according to the operation of the switch, displays the temperature history of the rolling bearing recorded in the memory on a liquid crystal monitor, and enters the sleep state again after a certain time. The cooling system described.   14. The infrared light communication according to claim 10, wherein the light receiving unit and the light emitting unit perform infrared communication using a through-hole provided in the cooling unit, the outer ring spacer and the spindle housing as an optical axis of infrared light. The cooling system described.

Images