JP7094127B2 - Bearing equipment - Google Patents

Description

The present invention relates to a bearing device, and more particularly to a technique for estimating the temperature of the bearing device.

Japanese Patent Application Laid-Open No. 2008-2591 (Patent Document 1) discloses a bearing device capable of directly and accurately measuring the temperature inside a rolling bearing. In this bearing device, a temperature sensor is attached to the inner peripheral surface of the outer ring. The temperature sensor is composed of a substrate and a resistance pattern formed on the substrate. The resistance pattern consists of a single line made of platinum with a narrow line width, and is configured so that the total length changes as the substrate expands or contracts depending on the temperature. Since the resistance value of the resistance pattern changes when the total length of the resistance pattern changes, the temperature can be detected by passing a current through the resistance pattern. The wiring from the temperature sensor is drawn out from the inner peripheral surface of the outer ring via the end surface (see Patent Document 1).

Japanese Unexamined Patent Publication No. 2008-2591

In the bearing device described in Patent Document 1, the temperature of the outer ring is detected by a temperature sensor attached to the inner peripheral surface of the outer ring which is a fixed ring, but the temperature of the inner ring which is a rotating wheel is not measured.

In recent years, in a spindle device of a machine tool or the like, the rotation of the spindle has been increased in order to improve the machining efficiency, and the heat generated from the bearing supporting the spindle has also increased along with the increase in speed. An increase in the temperature of the bearing causes an increase in the preload of the bearing, and an increase in the preload causes various problems such as a decrease in the life of the bearing and an increase in the rotational torque. Therefore, for the following reasons, it is desired to accurately measure or estimate the temperature of the rotating wheel (inner ring).

The preload inside the bearing during bearing rotation is affected by the difference in the amount of expansion in the radial direction between the inner ring and the outer ring. When the inner ring and the outer ring are a rotary ring and a fixed ring, respectively, the temperature of the rotary wheel is higher than the temperature of the fixed ring because the rotary wheel is less likely to dissipate heat than the fixed ring that can be forcibly cooled from the outside. As a result, the radial expansion amount of the rotating wheel becomes larger than the radial expansion amount of the fixed wheel due to the addition of the centrifugal force to the temperature difference. As a result, during rotation of the bearing, the preload inside the bearing increases as compared with when it is stationary, and such an increase in preload leads to a decrease in the life of the bearing and a decrease in the accuracy of life prediction.

Therefore, it is desired to accurately measure the temperature of the rotating wheel and accurately monitor the internal state of the bearing. By accurately measuring the temperature of the rotating wheel, it is possible to estimate the preload and adjust it to an appropriate value, or to improve the accuracy of predicting the life.

It is conceivable to attach a temperature sensor to the rotating wheel to directly detect the temperature of the rotating wheel, but it is necessary to ensure the durability of the sensor and to provide a means for extracting the detected value from the sensor rotating with the rotating wheel in a non-contact manner. There is an increase in cost.

The present invention has been made to solve such a problem, and an object of the present invention is to provide a bearing device capable of measuring the temperature of a rotating wheel in a non-contact and accurate manner.

According to the present invention, the bearing device includes a thermoelectric element and a calculation unit. The thermoelectric element is fixed to the fixed wheel, detects the temperature difference between the fixed wheel and the rotating wheel, and generates electricity by the temperature difference. The arithmetic unit operates by receiving the electric power generated by the thermoelectric element, and estimates the temperature of the rotating wheel from the temperature difference detected by the thermoelectric element and the temperature of the fixed wheel.

Preferably, the fixed ring and the rotary ring are the outer ring and the inner ring of the bearing, respectively. The thermoelectric element is arranged so as to absorb heat from the inner ring side and dissipate heat to the outer ring side.

Preferably, the bearing device further comprises an outer ring spacer provided adjacent to the outer ring and a thermal conductor provided in close contact with the inner peripheral surface of the outer ring spacer. The thermoelectric element is arranged on the surface of the thermal conductor facing the inner ring side.

Further, preferably, the bearing device further includes an outer ring spacer provided adjacent to the outer ring and a heat conductor provided on the inner peripheral side of the outer ring spacer. The thermoelectric element is arranged between the thermal conductor and the outer ring spacer.

Preferably, the heat conductor is arranged at a position shifted from the calculation unit in the circumferential direction of the outer ring spacer.
Preferably, the bearing device further comprises a temperature sensor that operates on the power generated by the thermoelectric element and detects the temperature of the outer ring. The temperature sensor is arranged in the outer ring spacer.

Preferably, the thermoelectric element is an element that generates a voltage according to a temperature difference due to the Zeebeck effect.

Preferably, the bearing device further comprises a power supply. The power supply unit receives the electric power generated by the thermoelectric element, boosts it to the operating voltage of the arithmetic unit, and supplies power to the arithmetic unit.

Preferably, the bearing device further comprises a transmitter. The transmission unit is configured to wirelessly transmit temperature information including the temperature of the rotating wheel estimated by the calculation unit to the outside using infrared rays.

Preferably, the bearing device further comprises a receiver. The receiving unit is configured to receive temperature information transmitted from the transmitting unit using infrared rays. The receiving unit includes a display unit that displays the received temperature information.

According to the present invention, it is possible to provide a bearing device capable of measuring the temperature of a rotating wheel in a non-contact manner with high accuracy.

It is sectional drawing along the rotation axis of the bearing apparatus according to Embodiment 1. FIG. It is an enlarged view around the arrangement place of the temperature sensor shown in FIG. It is sectional drawing of the bearing apparatus along the line III-III in FIG. It is a figure which showed the relationship between the open circuit voltage of the thermoelectric element shown in FIG. 1 and a temperature difference. It is a figure which showed the transition of the open circuit voltage of the thermoelectric element in the temperature steady state. It is a figure which showed the voltage change of the storage part in the substrate which is charged by the electric power generated by a thermoelectric element. It is a block diagram which shows the structure of the substrate shown in FIG. It is a functional block diagram of the microcomputer regarding the temperature estimation of the inner ring. It is a block diagram which shows the structure of the receiving part shown in FIG. FIG. 5 is a cross-sectional view orthogonal to the rotation axis of the bearing device according to the second embodiment. It is sectional drawing of the bearing apparatus along the line XI-XI in FIG. It is sectional drawing of the bearing apparatus along line XII-XII in FIG. FIG. 3 is a cross-sectional view orthogonal to the rotation axis of the bearing device according to the third embodiment. It is sectional drawing of the bearing apparatus along the XIV-XIV line in FIG.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same or corresponding elements are designated by the same reference numerals, and detailed description thereof will not be repeated.

[Embodiment 1]
<Bearing device configuration>
The configuration of the bearing device according to the first embodiment of the present invention will be described with reference to FIGS. 1 to 3. FIG. 1 is a cross-sectional view taken along the rotation axis of the bearing device 1 according to the first embodiment, and FIG. 2 is an enlarged view of the periphery of the arrangement location of the temperature sensor 14 shown in FIG. FIG. 3 is a cross-sectional view of the bearing device along the line III-III in FIG.

With reference to FIG. 1, the bearing device 1 includes a pair of angular contact ball bearings (hereinafter, each angular contact ball bearing is also simply referred to as a “bearing”). Each bearing includes an outer ring 2, an inner ring 4, and a rolling element 6. The outer ring 2 and the inner ring 4 are a fixed ring and a rotating ring, respectively, and a plurality of rolling elements 6 are provided between the outer ring 2 and the inner ring 4.

The bearing device 1 further includes an outer ring spacer 8, an inner ring spacer 10, a bearing housing 12, and a temperature sensor 14. The outer ring spacer 8 is made of a metal having good heat transfer properties, and is arranged between the two bearings in contact with the end surface of the outer ring 2. The inner ring spacer 10 is also made of a metal having good heat transfer properties, and is arranged between the two bearings in contact with the end surface of the inner ring 4. The outer ring 2 and the outer ring spacer 8 are fitted and fixed to the inner peripheral surface of the bearing housing 12. The inner ring 4 and the inner ring spacer 10 are fitted and fixed to the outer peripheral surface of the rotating body 38 supported by the bearing device 1. A predetermined amount of lubricant is sealed inside the bearing device 1. As the lubricant, grease, lubricating oil and the like are used, but the lubricant is not limited thereto.

The temperature sensor 14 is provided on the outer ring spacer 8. Specifically, the temperature sensor 14 is embedded in the outer ring spacer 8 at the end surface of the outer ring spacer 8, and is arranged so that the sensor detection surface abuts on the outer ring 2. The temperature of the outer ring 2 can be measured by the temperature sensor 14, and the temperature sensor 14 generates a voltage corresponding to the temperature of the outer ring 2 and arranges it in the through hole formed in the outer ring spacer 8 and the heat conductor 18. It is output to the substrate 30 through the provided electric wire 16.

With reference to FIG. 2, a stepped hole 40 is formed on the end surface of the outer ring spacer 8, and the compression coil spring 44, the substrate 42, and the temperature sensor 14 arranged in order from the back side of the hole 40 are sealed. The board stopper 46 is fixed with screws so as to do so. When the compression coil spring 44 pushes the substrate 42 by the compression repulsive force, the detection surface of the temperature sensor 14 comes into contact with the outer ring 2. As a result, the temperature of the outer ring 2 can be accurately detected by the temperature sensor 14. As the temperature sensor 14, for example, a semiconductor temperature sensor is used.

With reference to FIG. 1 again, the bearing device 1 further includes a thermal conductor 18, a thermoelectric element 20, an electric wire 26, a unit housing 28, and a substrate 30. The heat conductor 18 is made of metal and is provided in close contact with the inner peripheral surface of the outer ring spacer 8. The thermal conductor 18 is made of a material having high thermal conductivity, and is composed of, for example, a forged product of copper, a sintered alloy mainly composed of copper (copper alloy), or the like.

The thermoelectric element 20 is an element that generates (generates) a voltage according to the temperature difference between both sides of the element due to the Zeebeck effect. The thermoelectric element 20 is typically a Pelche element, but a spin-seebeck element may be adopted. The thermoelectric element 20 is arranged on a surface of the thermal conductor 18 facing the inner ring side (inner ring 4 and / or inner ring spacer 10), and the surface 22 on the high temperature side (endothermic side) faces the inner ring side and the low temperature side (inner ring 4 and / or the inner ring spacer 10). The surface 24 on the heat dissipation side) is fixed so as to be in contact with the heat conductor 18. Silicon grease or the like having high thermal conductivity may be applied between the thermoelectric element 20 and the thermal conductor 18.

The temperature difference between the inner ring 4 and the outer ring 2 can be measured by the thermoelectric element 20, and the thermoelectric element 20 generates a voltage corresponding to the temperature difference between the surface 22 on the high temperature side and the surface 24 on the low temperature side to generate an electric wire. It is output to the substrate 30 through 26. The thermal conductor 18 is provided by the thermoelectric element 20 in order to accurately detect the temperature difference between the inner ring 4 and the outer ring 2. That is, by providing the thermal conductor 18, the surface 24 on the low temperature side of the thermoelectric element 20 can be brought close to the temperature of the outer ring 2, while the surface 22 on the high temperature side can be brought close to the inner ring 4. In addition, in order to further improve the detection accuracy of the temperature difference, the surface on the inner ring side facing the thermoelectric element 20 may be black. As a result, the heat emissivity from the inner ring side can be increased, and the temperature of the surface 22 of the thermoelectric element 20 can be brought close to the temperature of the inner ring 4.

The unit housing 28 is provided on the inner peripheral side of the heat conductor 18. Specifically, with reference to FIG. 1 and FIG. 3, a recess is provided in a part of the inner peripheral surface of the thermal conductor 18 (preferably at a position close to the thermoelectric element 20), and the unit housing 28 is placed in the recess. It is fixed. The unit housing 28 is made of, for example, resin, and the substrate 30 is arranged inside the unit housing 28.

The substrate 30 includes a power supply unit, a power storage unit, a control unit, a signal transmission unit, and the like (none of them are shown). With reference to FIG. 1 again, the electric wire 16 from the temperature sensor 14 is connected to the substrate 30, and the electric wire 26 from the thermoelectric element 20 is connected to the substrate 30. The substrate 30 receives the electric power generated by the thermoelectric element 20 and supplies the electric power to the temperature sensor 14.

The substrate 30 estimates the temperature difference between the inner ring 4 and the outer ring 2 based on the output voltage of the thermoelectric element 20. Further, the substrate 30 detects the temperature of the outer ring 2 based on the output voltage of the temperature sensor 14. Then, the substrate 30 estimates the temperature of the inner ring 4 from the estimated value of the temperature difference between the inner ring 4 and the outer ring 2 and the detected value of the temperature of the outer ring 2. The configuration of the substrate 30 will be described in detail later.

The bearing device 1 further includes a light emitting unit 32, a light receiving unit 34, and a receiving unit 36. The light emitting unit 32 is composed of an infrared light emitting element, and the light emitting state is controlled by the substrate 30. The substrate 30 receives temperature information including an estimated value of the temperature of the inner ring 4, an estimated value of the temperature difference between the inner ring 4 and the outer ring 2, a detected value of the temperature of the outer ring 2, and the like by infrared communication using the light emitting unit 32. Send to 36.

The light receiving unit 34 can receive light from the light emitting unit 32 through the through hole 35 formed in the unit housing 28, the outer ring spacer 8, and the bearing housing 12, and converts the received infrared signal into an electric signal to the receiving unit 36. Output. The receiving unit 36 receives the temperature information transmitted from the substrate 30 through the light emitting unit 32 and the light receiving unit 34. Then, the receiving unit 36 executes predetermined various operations. For example, the receiving unit 36 can estimate the preload inside the bearing based on the temperature information of the bearing device 1, and can predict the life of the bearing device 1 based on the estimation result of the preload.

<Temperature estimation of the rotating wheel (inner ring 4)>
FIG. 4 is a diagram showing the relationship between the open circuit voltage V1 of the thermoelectric element 20 shown in FIG. 1 and the temperature difference ΔT. The temperature difference ΔT is the temperature difference between the surface 22 on the high temperature side and the surface 24 on the low temperature side of the thermoelectric element 20. With reference to FIG. 4, the larger the temperature difference ΔT, the higher the open circuit voltage V1. By acquiring the relationship between the open circuit voltage V1 and the temperature difference ΔT in advance, the temperature difference ΔT can be detected based on the output voltage of the thermoelectric element 20.

In the first embodiment, by providing the thermal conductor 18, the surface 24 on the low temperature side of the thermoelectric element 20 is brought close to the temperature of the outer ring 2, and the surface 22 on the high temperature side is brought close to the inner ring 4. The temperature difference ΔT corresponds to the temperature difference between the inner ring 4 and the outer ring 2. Actually, there is a gap between the surface 22 on the high temperature side of the thermoelectric element 20 and the inner ring 4, and the heat conductor 18 and the outer ring spacer 8 are interposed between the surface 24 on the low temperature side and the outer ring 2. Therefore, the temperature difference detected by the thermoelectric element 20 may be multiplied by a correction coefficient to obtain the temperature difference between the inner ring 4 and the outer ring 2.

FIG. 5 is a diagram showing a transition of the open circuit voltage V1 of the thermoelectric element 20 in a steady temperature state. With reference to FIG. 5, the line k1 shows the transition of the open circuit voltage V1 when the temperature difference ΔT is ΔT1. The line k2 shows the transition of the open circuit voltage V1 when the temperature difference ΔT is ΔT2 (ΔT2> ΔT1). The line k3 shows the transition of the open circuit voltage V1 when the temperature difference ΔT is ΔT3 (ΔT3> ΔT2).

As shown in FIG. 4, although the magnitude of the open circuit voltage V1 differs depending on the magnitude of the temperature difference ΔT, the open circuit voltage V1 becomes a constant level according to the magnitude of the temperature difference ΔT at any temperature difference. ..

FIG. 6 is a diagram showing a voltage change of the power storage unit in the substrate 30 charged by the electric power generated by the thermoelectric element 20. FIG. 6 shows the voltage of the power storage unit after the power storage unit is once discharged in a steady temperature state and charging is started by the generated power of the thermoelectric element 20. In FIG. 6, the time “0” on the horizontal axis is the time when the above charging is started.

With reference to FIG. 6, the line k4 shows the transition of the stored voltage when the temperature difference ΔT is ΔT1. The line k5 shows the transition of the stored voltage when the temperature difference ΔT is ΔT2 (ΔT2> ΔT1). The line k6 shows the transition of the stored voltage when the temperature difference ΔT is ΔT3 (ΔT3> ΔT2).

As shown in the figure, the larger the temperature difference ΔT, the shorter the time until the voltage of the storage unit reaches a predetermined voltage Vth. By acquiring the relationship between the temperature difference ΔT and the charging time of the power storage unit in advance, it is possible to estimate the temperature difference ΔT based on the charging time of the power storage unit. Alternatively, using the above relationship, it is also possible to estimate the temperature difference ΔT based on the voltage of the power storage unit after a lapse of a predetermined time from the start of charging.

FIG. 7 is a block diagram showing the configuration of the substrate 30 shown in FIG. With reference to FIG. 7, the substrate 30 includes a converter 60, a microcomputer 62, a capacitor 64, and a transmission circuit 66.

The converter 60 constitutes a power supply unit of the substrate 30. The converter 60 receives the electric power generated by the thermoelectric element 20, boosts the voltage to the operating voltage of the microcomputer 62, etc., and supplies power to the microcomputer 62, the capacitor 64, and the temperature sensor 14. The converter 60 can be operated by the electric power generated by the thermoelectric element 20, and after the capacitor 64 is stored, the converter 60 receives the electric power from the capacitor 64 and operates.

The microcomputer 62 constitutes a control unit of the substrate 30. The microcomputer 62 includes a CPU (Central Processing Unit), a memory, and input / output ports for inputting / outputting various signals (none of which are shown). The microcomputer 62 operates by receiving electric power from at least one of the converter 60 and the capacitor 64.

The microcomputer 62 receives the output voltage V1 of the thermoelectric element 20 and the output voltage V2 of the temperature sensor 14. Then, the microcomputer 62 estimates the temperature T3 of the inner ring 4 from the output voltage V1 of the thermoelectric element 20 and the output voltage V2 of the temperature sensor 14 by using the program and the map stored in the memory.

FIG. 8 is a functional block diagram of the microcomputer 62 regarding the temperature estimation of the inner ring 4. With reference to FIG. 8, the microcomputer 62 includes a voltage-temperature (VT) conversion unit 70, a voltage-temperature difference (V-ΔT) conversion unit 72, and an inner ring temperature estimation unit 74. The VT conversion unit 70 calculates the temperature T2 of the outer ring 2 from the output voltage V2 of the temperature sensor 14 by using a map or a relational expression showing the relationship between the output voltage V2 of the temperature sensor 14 and the temperature T2 of the outer ring 2. .. A map or a relational expression showing the relationship between the output voltage V2 of the temperature sensor 14 and the temperature T2 of the outer ring 2 is prepared in advance by an experiment or the like and stored in the memory of the microcomputer 62.

The V—ΔT conversion unit 72 uses a map or a relational expression showing the relationship between the output voltage V1 of the thermoelectric element 20 and the temperature difference ΔT1 between the inner ring 4 and the outer ring 2 from the output voltage V1 of the thermoelectric element 20 to the inner ring 4. And the temperature difference ΔT1 between the outer ring 2 and the outer ring 2 are calculated. A map or a relational expression showing the relationship between the output voltage V1 of the thermoelectric element 20 and the temperature difference ΔT1 is prepared in advance by an experiment or the like and stored in the memory of the microcomputer 62.

The inner ring temperature estimation unit 74 receives the calculated value of the temperature T2 of the outer ring 2 from the VT conversion unit 70, and receives the calculated value of the temperature difference ΔT1 between the inner ring 4 and the outer ring 2 from the V—ΔT conversion unit 72. Then, the inner ring temperature estimation unit 74 calculates the temperature T3 of the inner ring 4 by adding the temperature difference ΔT1 between the inner ring 4 and the outer ring 2 to the temperature T2 of the outer ring 2. As described above, in the bearing device 1 according to the first embodiment, the temperature sensor 14 for detecting the temperature of the outer ring 2 which is a fixed ring and the thermoelectric element 20 for detecting the temperature difference between the inner ring 4 and the outer ring 2 are used. , The temperature of the inner ring 4, which is a rotating wheel, is estimated.

With reference to FIG. 7 again, the capacitor 64 constitutes a storage unit of the substrate 30. The capacitor 64 stores electric power boosted to a predetermined voltage by the converter 60. Then, the capacitor 64 supplies the stored electric power to the converter 60, the microcomputer 62, and the transmission circuit 66. Although not shown, the electric power stored in the capacitor 64 may be supplied to the temperature sensor 14. The capacitor 64 is composed of, for example, an electric double layer capacitor.

The transmission circuit 66 constitutes a transmission unit of the substrate 30. The transmission circuit 66 operates by receiving electric power from at least one of the converter 60 and the capacitor 64. Then, the transmission circuit 66 receives temperature information (in addition to the estimated temperature T3 of the inner ring 4, the temperature T2 of the outer ring 2, the temperature difference ΔT1 between the inner ring 4 and the outer ring 2, etc.) from the microcomputer 62, and the received temperature. The light emitting state of the light emitting unit 32 is controlled so that the information is wirelessly transmitted to the receiving unit 36 (FIG. 1) using infrared rays. As a communication method using infrared rays, for example, various known methods using a carrier wave having a predetermined period can be used.

FIG. 9 is a block diagram showing the configuration of the receiving unit 36 shown in FIG. With reference to FIG. 9, the receiving unit 36 includes a control unit 80, a display unit 82, and a storage unit 84. The control unit 80 includes a CPU, a memory, and input / output ports for inputting / outputting various signals (none of them are shown).

The control unit 80 receives the temperature information transmitted from the substrate 30 through the light receiving unit 34 and outputs it to the storage unit 84. The control unit 80 is in a sleep state (power consumption suppression mode) when the light receiving unit 34 does not receive a signal, and when the light receiving unit 34 receives a signal, the control unit 80 is activated from the sleep state and receives the signal. The temperature information is output to the storage unit 84. Then, after the output of the received temperature information to the storage unit 84 is completed, if the state in which the light receiving unit 34 does not receive the signal for a predetermined time continues, the control unit 80 goes into the sleep state again. The light receiving unit 34 is always on standby in a receivable state.

The control unit 80 can execute various processes using the received temperature information. For example, when a user (a worker who handles a bearing device 1) wants to check the temperature history of the inner ring 4 and the outer ring 2, the control unit 80 is activated in response to a request from the user and also activates the display unit 82 to store the temperature. The temperature information can be read from the unit 84 and the temperature history can be displayed on the display unit 82.

Alternatively, the control unit 80 estimates the preload based on the temperatures of the inner ring 4 and the outer ring 2, adjusts the preload to an appropriate value when the preload adjustment mechanism is provided, or predicts the life of the bearing device 1. If so, the life prediction value can be modified according to the amount of increase in the preload.

The request from the user can be made, for example, by providing a confirmation button (not shown) and operating the button by the user.

The display unit 82 is configured by, for example, a liquid crystal monitor, and the display state is controlled by the control unit 80. The display unit 82 displays the history of temperature information read from the storage unit 84 according to the user's request, and various calculated values calculated by the control unit 80 (for example, preload estimation value and life prediction of the bearing device 1). It is also possible to display the value etc.). The display unit 82 may also be put into a sleep state after displaying for a predetermined time.

In addition, without providing the display unit 82, data is transferred to a remote PC or the like by wireless communication such as wireless LAN (Wi-Fi (registered trademark)), Bluetooth (registered trademark), ZigBee (registered trademark), etc. The temperature information may be displayed on the display unit of. Alternatively, an RFID tag may be built in the receiving unit 36 so that the temperature information can be read from the outside of the bearing device 1.

As for the method of supplying power to the receiving unit 36, power may be supplied through an electric wire, or if wiring of the electric wire is difficult, a coin-type battery (or button-type battery) holder may be provided from the battery. Power may be supplied. A lithium battery is preferable as the coin-type battery (or button-type battery), but a rechargeable nickel-hydrogen dry battery may be used instead of the coin-type battery.

The receiving unit 36 may have a waterproof structure as appropriate in order to prevent intrusion of coolant and the like used during machining by a device (for example, a spindle device of a machine tool) in which the bearing device 1 is used. For the waterproof structure, packing, O-ring, caulking, resin mold and the like can be adopted.

As described above, in the first embodiment, the temperature difference between the inner ring 4 and the outer ring 2 is estimated using the detection value of the thermoelectric element 20, and the temperature of the outer ring 2 is detected by the temperature sensor 14. Then, the temperature of the inner ring 4 is estimated from the above temperature difference and the temperature of the outer ring 2. Therefore, according to the first embodiment, the temperature of the inner ring 4, which is a rotating wheel, can be measured accurately without contact.

Further, in the first embodiment, the substrate 30 and the temperature sensor 14 operate using the electric power generated by the thermoelectric element 20. Therefore, according to the first embodiment, the temperature of the inner ring 4 can be measured without supplying electric power from the outside of the bearing device 1.

Further, in the first embodiment, by providing the thermal conductor 18, the surface 24 on the low temperature side of the thermoelectric element 20 is brought close to the temperature of the outer ring 2, and the surface 22 on the high temperature side is brought close to the inner ring 4. can. Therefore, according to the first embodiment, the thermoelectric element 20 can accurately measure the temperature difference between the inner ring 4 and the outer ring 2.

Further, according to the first embodiment, since the temperature sensor 14 is provided on the outer ring spacer 8 adjacent to the outer ring 2, the temperature of the outer ring 2 is measured by the temperature sensor 14 without changing the configuration of the outer ring 2. It can be detected with high accuracy.

Further, according to the first embodiment, the temperature information acquired inside the bearing device 1 can be wirelessly taken out to the external receiving unit 36 by using infrared rays. Then, the receiving unit 36 can appropriately display the extracted temperature information.

[Embodiment 2]
The bearing device 1A according to the second embodiment has a different structure of the thermal conductor and the unit housing from the bearing device 1 of the first embodiment.

The configuration of the bearing device 1A according to the second embodiment will be described with reference to FIGS. 10 to 12. FIG. 10 is a cross-sectional view orthogonal to the rotation axis of the bearing device 1A according to the second embodiment. 11 is a cross-sectional view of the bearing device 1A along the line XI-XI in FIG. 10, and FIG. 12 is a cross-sectional view of the bearing device 1A along the line XII-XII in FIG.

With reference to FIGS. 10 to 12, the bearing device 1A replaces the unit housing 28 and the heat conductor 18 with respect to the bearing device 1 shown in FIGS. 1 to 3, respectively, in place of the unit housing 50 and the heat conductor 52. And further comprises a compression coil spring 54.

The unit housing 50 is made of resin, for example, and is fixed to the inner peripheral surface of the outer ring spacer 8. The heat conductor 52 is provided in a part of the unit housing 50 and is arranged so as to abut on the inner peripheral surface of the outer ring spacer 8. Specifically, the substrate 30 is provided inside the unit housing 50, and the heat conductor 52 is arranged at a position shifted from the substrate 30 in the circumferential direction of the outer ring spacer 8 (FIG. 10). The heat conductor 52 can be arranged in the direction along the rotation axis direction with respect to the substrate 30, but in that case, in order to secure the arrangement space of the heat conductor 52, the outer ring spacer 8 (and the outer ring spacer 8) It is necessary to expand the inner ring spacer 10) in the direction of the rotation axis. In the second embodiment, since the heat conductor 52 and the substrate 30 are arranged along the circumferential direction of the outer ring spacer 8, the outer ring spacer 8 (and the inner ring spacer 10) is expanded in the rotation axis direction. No need.

The compression coil spring 54 presses the heat conductor 52 against the outer ring spacer 8 by its compression repulsive force. As a result, the heat conductor 52 comes into contact with the inner peripheral surface of the outer ring spacer 8. Then, the thermoelectric element 20 is arranged on the surface of the thermal conductor 52 opposite to the contact surface with the outer ring spacer 8 (FIGS. 10 and 12).

The parts not described above are basically the same as the bearing device 1 of the first embodiment.

Also in the second embodiment, the temperature of the inner ring 4 which is a rotating wheel can be measured accurately without contact. Further, also in the configuration of the second embodiment, the thermal conductor 52 can bring the surface 24 on the low temperature side of the thermoelectric element 20 close to the temperature of the outer ring 2 and the surface 22 on the high temperature side close to the inner ring 4. .. Therefore, even in the second embodiment, the temperature difference between the inner ring 4 and the outer ring 2 can be accurately measured by the thermoelectric element 20.

Then, according to the second embodiment, since the heat conductor 52 is arranged at a position shifted from the substrate 30 in the circumferential direction of the outer ring spacer 8, the outer ring is arranged in order to secure the arrangement space of the heat conductor 52. It is not necessary to extend the spacer 8 (and the inner ring spacer 10) in the direction of the axis of rotation.

[Embodiment 3]
The bearing device 1B according to the third embodiment has a different arrangement of the thermoelectric element 20 from the bearing device 1A of the second embodiment.

A configuration of the bearing device 1B according to the third embodiment will be described with reference to FIGS. 13 and 14. FIG. 13 is a cross-sectional view orthogonal to the rotation axis of the bearing device 1B according to the third embodiment. FIG. 14 is a cross-sectional view of the bearing device 1B along the line XIV-XIV in FIG. Since the cross-sectional view of the bearing device 1B along the line XI-XI in FIG. 13 is the same as the cross-sectional view shown in FIG. 11, the description will not be repeated.

With reference to FIGS. 13 and 14, in this bearing device 1B, the thermoelectric element 20 is arranged between the heat conductor 52 and the outer ring spacer 8. The compression coil spring 54 presses the heat conductor 52 against the outer ring spacer 8 by its compression repulsive force, so that the surface 22 on the high temperature side (endothermic side) of the thermoelectric element 20 comes into contact with the heat conductor 52 and dissipates heat. The surface 24 on the side) comes into contact with the outer ring spacer 8. The heat conductor 52 is formed so as to extend to a position close to the inner ring 4 so that the heat of the inner ring 4 can be sufficiently absorbed (FIG. 14).

In the third embodiment, the heat on the inner ring side is transferred to the surface 22 on the high temperature side of the thermoelectric element 20 through the heat conductor 52. The surface 24 on the low temperature side of the thermoelectric element 20 is in contact with the inner peripheral surface of the outer ring spacer 8. As a result, the thermoelectric element 20 generates a voltage corresponding to the temperature difference between the inner ring 4 and the outer ring 2. Also in the third embodiment, in order to further improve the detection accuracy of the temperature difference, the surface on the inner ring side facing the heat conductor 52 may be black.

Also in the third embodiment, since the heat conductor 52 is arranged at a position shifted from the substrate 30 in the circumferential direction of the outer ring spacer 8 (FIG. 13), the outer ring spacer 8 (and the inner ring spacer 10) are arranged. ) Does not need to be extended in the direction of the axis of rotation.

As described above, the same effect as that of the second embodiment can be obtained by the third embodiment.
In each of the above embodiments, the temperature sensor 14 for detecting the temperature of the outer ring 2 is provided, but the temperature of the outer ring 2 may be estimated without providing the temperature sensor 14. For example, the temperature of the outer ring 2 may be estimated from the temperature of the environment in which the bearing devices 1, 1A, 1B are installed, or when the environment in which the bearing devices 1, 1A, 1B are used is predetermined. May be a predetermined temperature obtained by measuring the temperature of the outer ring 2 in advance.

Further, in each of the above embodiments, the bearing devices 1, 1A and 1B are provided with a pair of angular contact ball bearings, but instead of the angular contact ball bearings, a bearing device such as a deep groove ball bearing or a cylindrical roller bearing is used. It may be configured. Further, the bearing device may be configured by an angular contact ball bearing or the like that lubricates the rolling surface by mixing compressed air and lubricating oil, which can be used for a machine tool spindle or the like.

Further, in each of the above embodiments, one thermoelectric element 20 is provided in the bearing device, but a plurality of such thermoelectric elements may be provided. Similarly, a plurality of temperature sensors 14 may be provided.

Further, although not particularly described above, the bearing housing 12 may be forcibly cooled with cooling oil or the like. As a result, the outer ring 2 is cooled through the bearing housing 12, so that the temperature difference between the inner ring 4 and the outer ring 2 can be increased. As a result, the amount of power generated by the thermoelectric element 20 can be increased, and the substrate 30 can be operated more stably.

The embodiments disclosed this time should be considered to be exemplary and not restrictive in all respects. The scope of the present invention is shown by the scope of claims rather than the description of the embodiments described above, and is intended to include all modifications within the meaning and scope equivalent to the scope of claims.

1,1A, 1B bearing device, 2 outer ring, 4 inner ring, 6 rolling element, 8 outer ring spacer, 10 inner ring spacer, 12 bearing housing, 14 temperature sensor, 16, 26 electric wire, 18, 52 thermal conductor, 20 thermoelectric Element, 28,50 unit housing, 30,42 board, 32 light emitting part, 34 light receiving part, 35 through hole, 36 receiving part, 38 rotating body, 44,54 compression coil spring, 46 board stopper, 60 converter, 62 microcomputer, 64 capacitors, 66 transmission circuit, 70 V-T conversion unit, 72 V-ΔT conversion unit, 74 inner ring temperature estimation unit, 80 control unit, 82 display unit, 84 storage unit.

Claims (7)

A thermoelectric element that is fixed to a fixed wheel, detects the temperature difference between the fixed wheel and the rotating wheel, and generates electricity by the temperature difference.
It operates by receiving the electric power generated by the thermoelectric element, and includes a calculation unit that estimates the temperature of the rotating wheel from the temperature difference detected by the thermoelectric element and the temperature of the fixed wheel.
The fixed ring and the rotating wheel are an outer ring and an inner ring of a bearing, respectively.
The thermoelectric element is arranged so as to absorb heat from the inner ring side and dissipate heat to the outer ring side, and further.
An outer ring spacer provided adjacent to the outer ring,
A thermal conductor provided in close contact with the inner peripheral surface of the outer ring spacer,
It is equipped with a temperature sensor that operates by receiving the electric power generated by the thermoelectric element and detects the temperature of the outer ring.
The thermoelectric element is arranged on the surface of the thermal conductor facing the inner ring side.
The temperature sensor is a bearing device arranged in the outer ring spacer. A thermoelectric element that is fixed to a fixed wheel, detects the temperature difference between the fixed wheel and the rotating wheel, and generates electricity by the temperature difference.
It operates by receiving the electric power generated by the thermoelectric element, and includes a calculation unit that estimates the temperature of the rotating wheel from the temperature difference detected by the thermoelectric element and the temperature of the fixed wheel.
The fixed ring and the rotating wheel are an outer ring and an inner ring of a bearing, respectively.
The thermoelectric element is arranged so as to absorb heat from the inner ring side and dissipate heat to the outer ring side, and further.
An outer ring spacer provided adjacent to the outer ring,
The heat conductor provided on the inner peripheral side of the outer ring spacer and
It is equipped with a temperature sensor that operates by receiving the electric power generated by the thermoelectric element and detects the temperature of the outer ring.
The thermoelectric element is arranged between the thermal conductor and the outer ring spacer.
The temperature sensor is a bearing device arranged in the outer ring spacer. The bearing device according to claim 1 or 2 , wherein the heat conductor is arranged at a position shifted from the calculation unit in the circumferential direction of the outer ring spacer. The bearing device according to any one of claims 1 to 3 , wherein the thermoelectric element is an element that generates a voltage corresponding to the temperature difference due to the Zeebeck effect. The bearing device according to any one of claims 1 to 4 , further comprising a power supply unit that receives electric power generated by the thermoelectric element, boosts the operating voltage of the calculation unit, and supplies power to the calculation unit. One of claims 1 to 5 , further comprising a transmission unit configured to wirelessly transmit temperature information including the temperature of the rotating wheel estimated by the calculation unit to the outside using infrared rays. The bearing device described in. Further comprising a receiver configured to receive the temperature information transmitted from the transmitter using infrared light.
The bearing device according to claim 6 , wherein the receiving unit includes a display unit that displays the received temperature information.

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