Power supply device and bearing device

Abstract

A power supply device (17) according to the present invention is provided with a first circuit (61) and a converter (53). The first circuit (61) converts an AC voltage into a first DC voltage and outputs the first DC voltage. The converter (53) outputs, to the electronic circuit (54), a second DC voltage that adjusts the first DC voltage to a first voltage range. The input voltage of the converter (53) is determined to be within a second voltage range. The first circuit (61) converts the AC voltage to a first DC voltage adjusted to a second voltage range.

Description

Technical Field

[0001] The present disclosure relates to a power supply device and a bearing device. Background Art

[0002] Japanese Patent Publication No. 2021-127831 (Patent Document 1) discloses a bearing device, which includes a bearing, a rotating member, and a generator that generates electricity according to the rotation of the rotating member. The bearing device also includes a sensor for monitoring the bearing state and a wireless communication circuit. The wireless communication circuit wirelessly sends the output of the sensor to an external device. The electricity generated by the generator is used to drive the sensor and the wireless circuit. Prior art literature Patent Literature

[0003] Patent Document 1: Japanese Patent Application Publication No. 2021-127831 Summary of the invention Technical problem to be solved by the invention

[0004] In the electronic circuits such as the above-mentioned sensors and wireless circuits, a voltage range required to drive the electronic circuits is specified. In addition, the effective value of the AC voltage based on the generator varies depending on the rotation speed of the rotating shaft, etc. In the above-mentioned bearing device, there may be a problem that a voltage within the specified voltage range cannot be supplied to the electronic circuit.

[0005] The present invention has been made to solve the above-mentioned problems, and provides a power supply device and a bearing device that supply a voltage within a predetermined voltage range to an electronic circuit. Technical solutions to technical problems

[0006] The power supply device of the present disclosure is mounted on a bearing device to drive an electronic circuit. The bearing device includes a rotating member and a generator that generates an AC voltage according to the rotation of the rotating member. The input voltage of the electronic circuit is determined to be within a first voltage range. The power supply device includes a first circuit and a second circuit. The first circuit converts the AC voltage into a first DC voltage and outputs it. The second circuit outputs a second DC voltage that adjusts the first DC voltage to the first voltage range to the electronic circuit. The input voltage of the second circuit is determined to be within a second voltage range. The first circuit converts the AC voltage into a first DC voltage that is adjusted to the second voltage range. Effects of the Invention

[0007] According to the present disclosure, it is possible to provide a power supply device that supplies a voltage within a predetermined voltage range to an electronic circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 It is a perspective view of the entire bearing device according to the first embodiment. Figure 2 It is a cross-sectional view of the bearing. Figure 3 It is a figure for demonstrating a cage. Figure 4 This is a diagram showing the bearing device as viewed from the sensor unit side. Figure 5 It is a diagram for explaining a configuration example of a power supply device. Figure 6 It is a diagram showing a configuration example of a voltage doubler rectifier circuit. Figure 7 It is a diagram showing a configuration example of a limiting circuit. Figure 8 It is a diagram showing a configuration example of a converter. Fig. 9 This is a diagram showing a configuration example of a power supply device according to the second embodiment. Fig.10 It is a diagram showing the equivalent circuit of the generator and the load. Fig.11 It is a diagram showing the relationship between the rotation speed of the rotating member and the power generation voltage. Fig.12 It is a diagram showing a configuration example of a step-down circuit. Fig.13 It is a diagram showing a configuration example of another step-down circuit. Fig.14 It is a diagram showing a configuration example of another step-down circuit. DETAILED DESCRIPTION

[0009] Hereinafter, the embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. In the embodiments described below, when referring to the number, amount, etc., the scope of the present disclosure is not necessarily limited to the number, amount, etc., unless otherwise specified. The same reference numbers are given to the same parts and equivalent parts, and there are cases where repeated descriptions are not repeated. It is intended from the beginning that the structures in the embodiments will be used in appropriate combinations. In addition, in the present embodiment, "A to B" used in the expression of voltage range, etc. means any one of "above A and below B", "larger than A and below B", "above A and less than B", and "larger than A and less than B".

[0010] <Implementation method 1> [Structure of bearing device] Figure 11 is a perspective view of the entire bearing device 1 of embodiment 1. The bearing device 1 can be mounted on any device, for example, on a machine tool. The bearing device 1 includes a bearing 2, a sensor unit 6, and a magnetic ring 7. The bearing 2 includes an outer wheel 3 and an inner wheel 4. In the bearing 2, for example, the outer wheel 3 is a stationary wheel, and the inner wheel 4 is a rotating wheel. The bearing 2 is described by taking a deep groove ball bearing as an example, but the type of the bearing 2 is not limited to a deep groove ball bearing.

[0011] Here, the bearing 2 is a standard bearing whose main dimensions (inner diameter, outer diameter, width, etc.) are recorded in a specific specification. The so-called standard bearing is, for example, a bearing with dimensions recorded in ISO specifications or JIS specifications. The bearing 2 is a radial bearing, and the main dimensions of the bearing 2 are the dimensions specified in ISO15 or JISB1512-1.

[0012] The sensor unit 6 includes a stator 5 and a cover 14. The cover 14 is a non-metallic resin component that protects the inside of the sensor unit 6. The magnetic ring 7 is a magnetic component that alternately magnetizes the N pole and the S pole in the circumferential direction. The stator 5 is fixed to the outer wheel 3, and the magnetic ring 7 is fixed to the inner wheel 4. The stator 5 and the magnetic ring 7 constitute an AC generator (hereinafter referred to as "generator G"). The generator G is a claw pole type generator, but it can also be a generator of other structures. Figure 1 The single-dot chain line is the rotation axis O of the bearing 2.

[0013] Figure 2 It is a cross-sectional view from above of the rotating axis O including the bearing 2. The bearing 2 includes an outer ring 3, an inner ring 4, a rotating body 8, a retainer 9, and a seal 10. The bearing 2 can be selected from the size of the standard bearing model in which the distance W between the end face 11 of the bearing 2 and the rolling body 8 can accommodate the sensor unit 6 and the magnetic ring 7. The end face 11 is also the end face of the outer ring 3.

[0014] A first cutout portion 3a with a step is formed on the inner circumferential surface of one end of the outer ring 3 as a recessed portion at the end of the outer ring 3. A second cutout portion 4a with a step is formed on the outer circumferential surface of one end of the inner ring 4 in a manner opposite to the first cutout portion 3a as a recessed portion at the end of the inner ring 4. In the axial direction (also referred to as the axial direction) of the bearing 2, an annular space formed by an annular recessed portion 50 cut toward the rolling element 8 by the first cutout portion 3a and the second cutout portion 4a is formed from the outer ring 3 to the inner ring 4.

[0015] The sensor unit 6 includes a holding member 12, a circuit substrate 13, a stator 5, and a cover 14. The holding member 12 is a magnetic material having a partition wall 12a that divides the holding member 12 into a first area 12b and a second area 12c in the radial direction (also referred to as the radial direction) of the bearing 2. The circuit substrate 13 is fixed to the inner bottom surface 12d of the first area 12b, and the stator 5 is arranged in the second area 12c. The cover 14 protects the circuit substrate 13 fixed to the inner bottom surface 12d. Instead of the cover 14, a resin sealing material can be used to seal the circuit substrate 13.

[0016] The outer diameter surface of the first region 12b side of the retaining member 12 is fitted and fixed to the first cutout portion 3a formed in the outer ring 3. The retaining member 12 is pressed or bonded in a manner that does not protrude from the end surface 11 of the outer ring 3. In addition, the retaining member 12 can be fixed by both pressing and bonding, or by methods other than these. When the retaining member 12 is fixed to the first cutout portion 3a, a certain gap is ensured between the rolling element 8 and the retaining member 12. As a result, even if axial displacement occurs, the rolling element 8 and the retaining member 12 can be prevented from contacting each other through the gap.

[0017] The stator 5 includes two magnetic members 21 and 22, a bobbin 23, and a coil 24. The portion of the holding member 12 including the second region 12c serves as the magnetic member 21 of the stator 5.

[0018] The magnetic ring 7 includes a core rod 7a and a multi-pole magnet 7b. The multi-pole magnet 7b is a magnet formed by, for example, vulcanizing and bonding a magnetic material formed by mixing magnetic powder and rubber to a core rod 7a, and then alternately magnetizing N poles and S poles in the circumferential direction of the bearing 2. In order to improve the rigidity, the core rod 7a of the magnetic ring 7 has a flange portion 7c. The magnetic ring 7 is fixed to the outer diameter surface 4b of the inner wheel 4 by pressing in or the like. The flange portion 7c is housed in the second cutout portion 4a formed in the inner wheel 4. The magnetic ring 7 is configured so as not to be exposed from the end surface 20 of the inner wheel 4.

[0019] Inside the annular recess 50, the magnetic ring 7, the stator 5 and the circuit substrate 13 are arranged so as not to overlap each other in the axial direction of the bearing 2. As a result, the various components can be arranged inside the annular recess 50, so the size of the bearing 2 can be suppressed. Moreover, in the bearing device 1, for example, the magnetic ring 7 is fixed to the inner wheel 4, and the stator 5 is fixed to the outer wheel 3 at a relative position. The generator G generates alternating current according to the rotation speed of the rotating component (the inner wheel 4 in this embodiment). For example, the greater the rotation speed of the rotating component, the greater the effective value of the alternating current. In addition, since the variation of the inner wheel 4 and the outer wheel 3 in the axial direction of the bearing 2 is smaller than that of the retainer 9, the generator G can ensure a stable power generation, and the size of the bearing device can be suppressed while also being able to function normally.

[0020] Figure 39 is a diagram for explaining the retainer 9. In the retainer 9, recesses 93 are formed at predetermined intervals along the circumferential direction of the axial end surface 91 of the annular retainer body. A pair of claws 94, 94 are formed to protrude from the opening ends of the recess 93 that are opposite to the circumferential direction. The recess 93 and the pair of claws 94, 94 form a structure for accommodating the Figure 2 The pocket 95 of the rolling element 8 is shown. Thus, the shape of the retainer 9 is a shape in which one end face 91 is open and the other end face 92 is connected. The retainer 9 is a resin member, and is arranged so that the sensor unit 6 and the magnetic ring 7 are not exposed from the end faces 11 and 20 on the open side.

[0021] Figure 4 This is a diagram showing the bearing device 1 as viewed from the sensor unit 6 side. Figure 4 In order to make the interior of the sensor unit 6 clear, a part of the cover 14 is omitted for illustration. One or more sensors for monitoring the state of the bearing 2 are mounted on the circuit substrate 13. For example, an acceleration sensor 15 and a temperature sensor 16 are mounted on the circuit substrate 13. In addition, the temperature sensor 16 can also be inserted from a hole (not shown) provided on the inner bottom surface 12d of the retaining member 12, and mounted on the back side of the circuit substrate 13 so as to approach (or contact) the end surface of the first cutout portion 3a of the outer ring 3. As a result, the temperature sensor 16 is close to the outer ring 3, and the temperature of the bearing 2 can be accurately measured.

[0022] In addition, a power supply device 17 and a wireless communication circuit 18 are mounted on the circuit board 13 .

[0023] The power supply device 17 rectifies the AC power generated by the generator G and converts it into DC power. The electronic circuit 54 (acceleration sensor 15, temperature sensor 16 and wireless communication circuit 18) uses the DC power converted by the power supply device 17. The circuit board 13 is provided with terminals 25.

[0024] The wireless communication circuit 18 includes an antenna portion 18a. The wireless communication circuit 18 uses the antenna portion 18a to wirelessly send the outputs of the acceleration sensor 15 and the temperature sensor 16 that monitor the state of the bearing 2 to the outside. The circuit substrate 13 is fixed to the retaining member 12 by a plurality of screws 19. In addition, the circuit substrate 13 can also be adhesively fixed to the retaining member 12. The circuit substrate 13 on which the wireless communication circuit 18 is mounted is arranged relative to the resin cover 14. As a result, the wireless communication circuit 18 becomes a structure that is not sealed by conductive materials such as metal. Therefore, wireless communication can be performed using the antenna portion 18a in the wireless communication circuit 18. As described above, in the present embodiment, the power supply device 17 is mounted inside the bearing device 1. In addition, the power supply device 17 can also be mounted outside the bearing device 1.

[0025] [Structure of power supply device] Figure 5 1 is a diagram for explaining a configuration example of the power supply device 17. As described above, the power supply device 17 and the electronic circuit 54 are mounted on the circuit substrate 13. In addition, the acceleration sensor 15, the temperature sensor 16, and the wireless communication circuit 18 are mounted in the electronic circuit 54. That is, the electronic circuit 54 monitors the state of the bearing 2 through the acceleration sensor 15 and the temperature sensor 16, and transmits the detection values ​​of these sensors to the outside through the wireless communication circuit 18. In addition, a voltage range (first voltage range) required to drive the electronic circuit 54 is specified. In the present embodiment, the first voltage range is 3.3V or more and 5V or less.

[0026] The power supply device 17 has a first circuit 61 and a buck-boost DC (Direct Current) converter. The buck-boost DCDC converter is also referred to as "converter 53". Converter 53 corresponds to the "second circuit" of the present disclosure. A voltage range based on a withstand voltage is specified in the input voltage of converter 53. This voltage range corresponds to the "second voltage range" of the present disclosure. In the present embodiment, the second voltage range is greater than 15V and less than 20V. In addition, the second voltage range is composed of a lower limit value and an upper limit value, and the upper limit value is also referred to as "withstand voltage".

[0027] The first circuit 61 converts the AC voltage from the generator G into a DC voltage, and outputs the DC voltage to the converter 53. The first circuit 61 includes a voltage doubler rectifier circuit 51 and a limiter circuit 52.

[0028] The voltage doubler rectifier circuit 51 converts the AC voltage into a boosted DC voltage and outputs the DC voltage. The output DC voltage is provided to the limiting circuit 52. Specifically, the voltage doubler rectifier circuit 51 boosts the effective value of the AC voltage to N (N is an integer greater than 2) times and rectifies it to provide it to the limiting circuit 52. In this embodiment, N is 2. In addition, the voltage doubler rectifier circuit 51 can also be other circuits as long as it is a circuit that can increase the effective value of the AC voltage.

[0029] Next, the limiter circuit 52 adjusts the DC voltage from the voltage doubler rectifier circuit 51 to a DC voltage in the second voltage range by reducing the voltage value of the DC voltage from the voltage doubler rectifier circuit 51 and outputs the DC voltage. The DC voltage in the second voltage range corresponds to the "first DC voltage" of the present disclosure.

[0030] The converter 53 adjusts the first DC voltage (the DC voltage from the limiter circuit 52) ​​within the first voltage range. Then, the converter 53 outputs the adjusted DC voltage (the second DC voltage) to the electronic circuit 54. The electronic circuit 54 is driven by the DC voltage.

[0031] As described above, the voltage range (first voltage range) required to drive the electronic circuit 54 is defined. The first voltage range is 3.3 V to 5 V. Therefore, the output voltage of the converter 53 is preferably within the first voltage range of 3.3 V to 5 V.

[0032] In addition, as described above, the effective value of the AC voltage generated by the generator G varies depending on the rotation speed of the rotating component. For example, there is a case where the effective value of the AC voltage is less than 2V when the rotation speed of the rotating component is slow, and is more than 50V when the rotation speed of the rotating component is fast. In the converter 53, although a certain degree of boosting can be performed, when the effective value of the AC voltage is too small, the voltage from the converter 53 sometimes cannot reach the first voltage range. Therefore, in addition to the converter 53, the voltage doubling rectifier circuit boosts the AC voltage. Therefore, for example, even when the effective value of the AC voltage from the generator G is too small, the voltage from the converter 53 can reach the first voltage range.

[0033] In addition, a configuration in which the power supply device 17 does not include the limiting circuit 52 but includes the converter 53 (the configuration of the first comparative example) can be considered. In the configuration of the first comparative example, it is necessary to assume that the effective value of the AC voltage from the generator G becomes too large. In this assumption, in the configuration of the first comparative example, it is necessary to set the upper limit value of the second voltage range of the converter 53 to be greater than the maximum value of the effective value of the AC voltage of the generator G. Therefore, in the configuration of the first comparative example, the cost of the converter 53 increases. Therefore, by including the limiting circuit 52 in the power supply device 17, a cheaper converter 53 can be used compared to the configuration of the first comparative example.

[0034] In addition, a configuration in which the power supply device 17 includes the limiting circuit 52 but does not include the converter 53 (the configuration of the second comparative example) can be considered. In the configuration of the second comparative example, when the input voltage of the limiting circuit 52 is too large, in order to make the output voltage of the limiting circuit 52 equal to or less than the upper limit value of the first voltage range of the electronic circuit 54, it is necessary to consume the voltage of the input-output potential difference only by the limiting circuit 52. For example, when the input voltage of the limiting circuit 52 is 50V and the upper limit value of the first voltage range is 5V, it is necessary to consume the voltage of the input-output potential difference of 45V. Therefore, in the configuration of the second comparative example, it is necessary to have a heat dissipation member for releasing the heat generated by the voltage consumption of the input-output potential difference, which increases the cost.

[0035] In addition, the heat generated by the element (i.e., the limiting circuit 52) ​​that generally requires a heat dissipation member is proportional to the power consumption. In addition, the input current of the limiting circuit 52 is substantially equal to the output current of the limiting circuit 52. Therefore, the power consumption is the value obtained by multiplying the above-mentioned input-output potential difference by the input current. Therefore, if the input voltage to the limiting circuit 52 increases, the power consumption of the limiting circuit 52 also increases.

[0036] The power consumption of the converter 53 is based on the efficiency of the converter 53. Here, the case where the efficiency of the converter 53 is 100% is considered. In this case, the power consumption of the converter 53 is not generated. Therefore, in this case, in the converter 53, input current×input voltage=output current×output voltage. If the output current×output voltage is considered to be a constant value, if the input voltage to the converter 53 increases, the input current to the converter 53 decreases.

[0037] Here, the case where the output voltage of the limiting circuit 52 is large is described. This case is, for example, the case where the output voltage of the limiting circuit 52 is near the upper limit value (withstand voltage) of the second voltage range of the converter 53 and is a value less than the upper limit value. In this case, it is considered that the power input to the converter 53 (the product of the input current of the converter 53 and the input voltage of the converter 53) is constant. When the output voltage of the limiting circuit 52 is large, that is, when the input voltage of the converter 53 is large, the input current of the converter 53 becomes small. The small input current of the converter 53 means that the output current of the limiting circuit 52 is small. As described above, the input current of the limiting circuit 52 is approximately equal to the output current of the limiting circuit 52. Therefore, the input current of the limiting circuit 52 becomes small. In addition, if the input-output potential difference of the limiting circuit 52 becomes small, the power consumption becomes small according to the square value of the current. Therefore, the power consumption in the limiting circuit 52 can be greatly reduced. In this way, by setting the output voltage of the limiting circuit 52 to the upper limit value (near the upper limit value) of the second voltage range of the converter 53, the power consumption of the limiting circuit 52 can be reduced.

[0038] Next, the processing of the power supply device 17 is described using specific numerical values. In the present embodiment, it is assumed that the AC voltage (amplitude) generated by the generator G is 2V to 30V. In this case, if the loss of the components (such as the two diodes described later) included in the voltage doubler rectifier circuit 51 is set to 0.5V×2, the output voltage of the voltage doubler rectifier circuit 51 is 3V to 59V. In addition, the loss voltage of the limiting circuit 52 is set to 1V, and the limiting voltage set by the limiting circuit 52 is set to 20V. In this case, the output of the limiting circuit 52 is 2 to 19V. Therefore, a converter 53 with a withstand voltage of 20V can be used. As described above, the output voltage of the converter 53 is 3.3V to 5V, and the converter 53 is of a small size that can be assembled into the bearing device 1. Typically, the withstand voltage of such a converter 53 is 15V to 20V. In addition, the output voltage of the limiting circuit 52 is 15V to 20V.

[0039] As described above, the power supply device 17 includes the first circuit 61 and the converter 53. The first circuit 61 converts the AC voltage from the generator G into the first DC voltage and outputs it to the converter 53. Then, the converter 53 outputs the second DC voltage adjusted to the first voltage range to the electronic circuit 54. Therefore, the power supply device 17 can provide the electronic circuit 54 with the DC voltage (second DC voltage) adjusted to the first voltage range specified by the electronic circuit 54. Therefore, the power supply device 17 can provide the electronic circuit 54 with the DC voltage within the voltage range specified by the electronic circuit 54. In addition, the first circuit 61 provides the first DC voltage adjusted to the voltage range (second voltage range) specified by the converter 53. Therefore, the first circuit 61 can provide the converter 53 with the DC voltage within the voltage range specified by the converter 53.

[0040] In addition, the first circuit 61 includes a limiting circuit 52. The limiting circuit 52 adjusts (steps down) the DC voltage input to the limiting circuit 52 to a first DC voltage in the second voltage range. Then, the limiting circuit 52 outputs the first DC voltage to the converter 53. Therefore, even when the AC voltage generated by the generator G is excessive, an appropriate voltage can be supplied to the converter 53.

[0041] In addition, the first circuit 61 is provided with a voltage doubling rectifier circuit 51 in the front section of the limiting circuit 52. The voltage doubling rectifier circuit 51 converts the AC voltage generated by the generator G into a boosted DC voltage and outputs it. Therefore, even when the AC voltage generated by the generator G is too small, an appropriate voltage can be provided to the converter 53. That is, since the power supply device 17 includes the voltage doubling rectifier circuit 51, the limiting circuit 52 and the converter 53, a stable voltage can be provided to the electronic circuit 54 regardless of whether the rotating component rotates at a high speed or a low speed. Moreover, since the circuit structure of the power supply device 17 is simple and can be miniaturized, the heat generated by the power supply device 17 can also be reduced, so the circuit substrate 13 can be mounted in a small space such as the inside of the bearing device 1.

[0042] The second voltage range of the converter 53 (output of the limiter circuit 52 ) is 15 V to 20 V. Therefore, the designer's freedom of choice of the converter 53 can be increased, and the amount of heat generated in the limiter circuit 52 can be reduced.

[0043] In addition, the electronic circuit 54 is equipped with sensors (acceleration sensor 15 and temperature sensor 16 in this embodiment) for monitoring the state of the bearing 2, and a wireless communication circuit 18 for wirelessly transmitting the detection value of the sensor to an external device. Therefore, the power supply device 17 can convert the AC power generated by the generator G into DC power within an appropriate voltage range and supply it to the acceleration sensor 15, the temperature sensor 16 and the wireless communication circuit 18.

[0044] Figure 6 2 is a circuit diagram showing an example of a voltage doubler rectifying circuit 51. The voltage doubler rectifying circuit 51 includes a diode D1, a diode D2, a capacitor C1, and a capacitor C2 connected in series with the capacitor C1.

[0045] The first input terminal 511 of the voltage doubler rectifier circuit 51 is connected to the anode of the diode D1. The cathode of the diode D1 and the capacitor C1 are connected to the output terminal 513 of the voltage doubler rectifier circuit 51. The anode of the diode D2 is connected to the capacitor C2. The cathode of the diode D2 is connected to the first input terminal 511. The connection node of the capacitors C1 and C2 is connected to the second input terminal 512 of the voltage doubler rectifier circuit 51.

[0046] When the AC voltage is positive, the diode D1 is turned on and the diode D2 is turned off, and the capacitor C1 is charged. In addition, when the AC voltage is negative, the diode D1 is turned off and the diode D2 is turned on, and the capacitor C2 is charged. In this way, the capacitor C1 and the capacitor C2 are charged alternately, so that the charge is accumulated in the capacitor C1 and the capacitor C2. Since the capacitor C1 and the capacitor C2 are connected in series, the voltage doubler rectifier circuit 51 can output a DC voltage that is twice the peak value of the AC voltage.

[0047] Figure 7 : is a circuit diagram showing an example of a limiting circuit 52. The limiting circuit 52 includes a resistor R1, a Zener diode D3, a transistor Q1, and a transistor Q2. An input terminal 521 of the limiting circuit 52 is connected to one end of the resistor R1, the collector of the transistor Q1, and the collector of the transistor Q2. In addition, the anode of the Zener diode D3 is grounded, and the cathode of the Zener diode D3 is connected to the other end of the resistor R1 and the base of the transistor Q2. In addition, the emitter of the transistor Q2 is connected to the base of the transistor Q1. The emitter of the transistor Q1 is connected to the output terminal 522 of the limiting circuit 52.

[0048] When the voltage input to the limiting circuit 52 is less than the Zener voltage of the Zener diode D3, the voltage from the connection node of the resistor R1 and the Zener diode D3 is applied to the base of the transistor Q2. In addition, the voltage is supplied from the emitter of the transistor Q2 to the base of the transistor Q1. Thus, the input DC voltage is output.

[0049] In addition, when the voltage input to the limiting circuit 52 is greater than the Zener voltage, the voltage applied to the base of the transistor Q2 is limited because the anode of the Zener diode D3 is grounded. Therefore, the voltage applied to the base of the transistor Q1 is also limited. As a result, the voltage output from the limiting circuit 52 is limited. Figure 7 , an example of a Darlington transistor composed of transistor Q1 and transistor Q2 is shown. However, the limiting circuit 52 may also be composed of a circuit using a transistor instead of a Darlington transistor or a field effect transistor (FET). In addition, the limiting circuit 52 may be a dedicated voltage limiting IC (Integrated Circuit) or an LDO (Low Dropout) linear regulator.

[0050] Figure 8 is a circuit diagram showing an example of the converter 53. Figure 8 In the example of FIG. 5 , the converter 53 is a buck-boost chopper. Figure 8 In the example of FIG. 5 , there are switching elements S1, S2, S3, S4, and a reactor L. In addition, although not particularly shown, the converter 53 includes a sensor for detecting the input voltage of the converter 53, a sensor for detecting the output voltage of the converter 53, and a control circuit. The control circuit switches the switching elements S1 to S4 on and off according to the input voltage and the output voltage.

[0051] exist Figure 8In the example of FIG. 5 , one end of the switching element S1 is connected to the input terminal 531 of the converter 53. The other end of the switching element S1 is connected to one end of the switching element S2. The other end of the switching element S2 is grounded.

[0052] One end of the switching element S3 is connected to the output terminal 532 of the converter 53. The other end of the switching element S3 is connected to one end of the switching element S4. The other end of the switching element S4 is grounded.

[0053] For example, when the input voltage is greater than the output voltage, the input voltage is stepped down in a step-down mode, and the control circuit turns on the switch element S3 and turns off the switch element S4. At the same time, the control circuit repeatedly switches to the following first and second states. The first state is a state in which the switch element S1 is turned on and the switch element S2 is turned off. The second state is a state in which the switch element S1 is turned off and the switch element S2 is turned on.

[0054] In addition, when the input voltage is lower than the output voltage, the input voltage is boosted in a boost mode, and the control circuit turns on the switch element S1 and turns off the switch element S2. At the same time, the control circuit repeatedly shifts to the following third and fourth states. The third state is a state in which the switch element S3 is turned on and the switch element S4 is turned off. The fourth state is a state in which the switch element S3 is turned off and the switch element S4 is turned on. Thus, the converter 53 can adjust the input voltage of the converter 53 to a DC voltage in the first voltage range and provide it to the electronic circuit 54.

[0055] <Implementation method 2> Fig. 9 FIG. 2 shows a configuration example of a power supply device 17A according to Embodiment 2. Fig. 9 In the embodiment, the power supply device 17A includes a first circuit 61A instead of the first circuit 61. The first circuit 61A includes a step-down circuit 55. Fig. 9 In the embodiment, a step-down circuit 55 is arranged between the voltage-doubling rectifier circuit 51 and the limiting circuit 52. The larger the DC voltage outputted from the voltage-doubling rectifier circuit 51, the more the step-down circuit 55 steps down the voltage. The DC voltage stepped down by the step-down circuit 55 is outputted to the limiting circuit 52.

[0056] Next, the reason for providing the limiting circuit 52 will be described. Fig.10 2 is an equivalent circuit of the generator G and the load 26. The load 26 corresponds to the circuit board 13, for example. Fig.10 V2 in the figure represents the no-load electromotive force of the generator G, which generates a voltage proportional to the rotation speed of the rotating member (inner wheel 4). R2 represents the winding resistance, and L1 represents the winding inductance. Vo is the generated voltage when the load 26 is connected.

[0057] Fig.11: is a graph showing the relationship between the rotation speed of the rotating component and the generated voltage Vo. The horizontal axis represents the rotation speed of the rotating component, and the vertical axis represents the generated voltage Vo. Fig.11 In the example of FIG. 1 , the solid line indicates a case where the load 26 is not loaded, the dotted line indicates a case where the load 26 is lightly loaded, and the single-dot chain line indicates a case where the load 26 is heavily loaded.

[0058] exist Fig.11 In the example, when the load 26 is unloaded, the generated voltage Vo becomes the unloaded electromotive force V2, and as shown by the solid line, becomes a voltage roughly proportional to the rotation speed. Next, the case where the load 26 is a heavy load is described. This case refers to the case where the impedance of R3 is smaller than the combined impedance of L2 and R2 (the load is heavier). In this case, Fig.11 As shown by the dashed line, even if the speed increases, the generated voltage Vo does not increase. Next, the case where the load 26 is a light load is described. This case refers to the case where the impedance of R3 is larger than the combined impedance of L2 and R2 (the load is lighter). In this case, Fig.11 As shown by the single-dot chain line, as the rotation speed increases, the generated voltage Vo also increases.

[0059] exist Fig.11 In the example of FIG. 1 , when the rotation speed is 5000 rpm, the power generation voltage Vo is about twice as large when the load 26 is lightly loaded as when the load 26 is heavily loaded. When designing the generator G, if the designer wants to achieve a high power generation voltage at a slow rotation speed, an excessive voltage will be generated at a fast rotation speed, and a voltage exceeding the withstand voltage of the circuit substrate 13 may be supplied to the circuit substrate 13. More specifically, even when the rotation speed of the rotating member is the maximum rotation speed, the voltage input to the limiting circuit 52 is preferably a relatively small voltage.

[0060] Therefore, if Fig. 9 As shown, the inventors arranged a step-down circuit 55 between the voltage doubler rectifier circuit 51 and the limiter circuit 52. The step-down circuit 55 suppresses a voltage drop when the rotation speed of the rotating member is slow, and increases a voltage drop when the rotation speed of the rotating member is fast.

[0061] Fig.12 is a circuit diagram showing an example of the step-down circuit 55. Fig.12 In the example of , the step-down circuit 55 includes a resistor R4 and a Zener diode D4. An input terminal 551 and an output terminal 552 of the step-down circuit 55 are connected to one end of the resistor R4. In addition, the other end of the resistor R4 is connected to the cathode of the Zener diode D4. In addition, the anode of the Zener diode D4 is grounded.

[0062] exist Fig.12In the example, when the input voltage to the step-down circuit 55 becomes extremely large and exceeds the Zener voltage of the Zener diode D4, an extremely large current flows through the resistor R4, and power is consumed in the resistor R4 and the Zener diode D4.

[0063] As described above, the power supply device 17A includes a step-down circuit 55. Thus, the power supply device 17A suppresses the voltage drop when the DC voltage output from the voltage doubler rectifier circuit is small (when the rotation speed of the rotating component is slow). In addition, the power supply device 17A increases the voltage drop when the DC voltage output from the voltage doubler rectifier circuit is large (when the rotation speed of the rotating component is fast). Therefore, components with low withstand voltage can be used in the circuit substrate 13. In addition, when components with low withstand voltage are generally used, the voltage drop of the component also becomes smaller. Therefore, the power supply device 17A can ensure the voltage when the rotation speed of the rotating component is slow, and can achieve the driving of the electronic circuit 54 when the rotation speed is even slower.

[0064] Fig.13 1 is a circuit diagram showing an example of another step-down circuit 55A. The step-down circuit 55A includes a resistor R5 and a plurality of diodes (in Fig.13 In the example, there are three diodes D11, D12, and D13).

[0065] An input terminal 551 and an output terminal 552 of the step-down circuit 55A are connected to one end of the resistor R5. In addition, the other end of the resistor R5 is connected to the anode of the diode D11. In addition, the cathode of the diode D13 is grounded.

[0066] In the step-down circuit 55A, the total value of the forward voltages of the diodes D11, D12, and D13 is used. For example, when the forward voltages of the diodes D11, D12, and D13 are 0.6V, the total value is 1.8V.

[0067] exist Fig.13 In the example of , only when the input voltage to the step-down circuit 55A becomes extremely large and exceeds the total value, a very large current flows through the diodes D11, D12, and D13 due to the static characteristics of the diodes. Therefore, in this case, the step-down circuit 55A can consume power through the resistor R5 and the diodes D11, D12, and D13.

[0068] Fig.14 : is a circuit diagram showing an example of another step-down circuit 55B. Step-down circuit 55B includes resistors R6, R7, R8 and transistor Q4. One end of resistor R6 and one end of resistor R8 are connected to input terminal 551 and output terminal 552 of step-down circuit 55A. The other end of resistor R6 is connected to one end of resistor R7. The other end of resistor R7 is grounded.

[0069] A connection node of the resistor R6 and the resistor R7 is connected to the base of the transistor Q4, the emitter of the transistor Q4 is grounded, and the collector of the transistor Q4 is connected to the other end of the resistor R8.

[0070] When the input voltage to the step-down circuit 55B becomes extremely large, a voltage Vb is applied to the base of the transistor Q4. As a result, since the transistor Q4 is turned on, power is consumed by the resistor R4 and the transistor Q4. In addition, the voltage Vb applied to the base of the transistor Q4 is determined by the ratio of the resistor R6 to the resistor R7. For example, when Vb exceeds 0.6V, the transistor Q4 is turned on.

[0071] <Modification> (1) The first circuit 61 may be any other circuit as long as it is a "circuit that converts an AC voltage into a first DC voltage adjusted within a second voltage range." For example, the first circuit 61 may be configured to have only the limiting circuit 52 and not the voltage doubler rectifier circuit 51. In addition, the first circuit 61 may be configured to have only the voltage doubler rectifier circuit 51 and not the limiting circuit 52.

[0072] In the above example, the converter 53 is described as a step-up / step-down converter. However, the converter 53 may be a step-up converter or a step-down converter.

[0073] (2) In the above embodiment, the power supply device 17 is mounted on the bearing device 1. However, the power supply device 17 may be mounted on another device having the generator G. Even in such a configuration, when the effective value of the AC voltage of the generator G varies, the power supply device 17 can supply a voltage within a predetermined voltage range to the electronic circuit.

[0074] [Note] (Item 1) The power supply device of the present disclosure drives an electronic circuit. The input voltage of the electronic circuit is determined to be within a first voltage range. The power supply device includes a first circuit and a second circuit. The first circuit converts an AC voltage from a generator into a first DC voltage and outputs the first DC voltage. The second circuit outputs a second DC voltage adjusted from the first DC voltage to the electronic circuit. The input voltage of the second circuit is determined to be within a second voltage range. The first circuit converts an AC voltage into a first DC voltage adjusted to the second voltage range.

[0075] (Item 2) In the power supply device according to Item 1, the first circuit includes a limiter circuit. The limiter circuit adjusts a DC voltage input to the limiter circuit to a first DC voltage within a second voltage range.

[0076] (Item 3) In the power supply device described in Item 2, the first circuit includes a voltage doubling rectifier circuit that converts an AC voltage into a stepped-up DC voltage and outputs the DC voltage.

[0077] (Item 4) In the power supply device described in Item 3, the first circuit has a step-down circuit that steps down the DC voltage output from the voltage doubler rectifier circuit and outputs the step-down circuit to the limiting circuit. The step-down circuit steps down the DC voltage more as the DC voltage output from the voltage doubler rectifier circuit increases.

[0078] (Item 5) In the power supply device described in any one of Items 1 to 4, the second voltage range is greater than or equal to 15V and less than or equal to 20V.

[0079] (Item 6) A bearing device of the present disclosure includes the power supply device described in any one of Items 1 to 4, a rotating member, and a generator that generates an AC voltage according to rotation of the rotating member.

[0080] (Item 7) The bearing device according to Item 6 includes a bearing, a sensor for monitoring a state of the bearing, and a communication circuit for wirelessly transmitting a detection value of the sensor to an external device. The electronic circuit includes the sensor and the communication circuit.

[0081] All contents of the embodiments disclosed this time should be considered as illustrative rather than limiting. The scope of the present invention should be considered to be indicated not by the description of the above embodiments but by the claims, and all changes within the meaning and scope equivalent to the claims are included. Description of symbols

[0082] 1 Bearing device 2 Bearings 3 Outer wheel 4 Inner wheel 5. Stator 6 Sensor unit 7 Magnetic ring 7a Mandrel 7b Multi-pole magnet 7c Flange 8 Rolling elements 9 Retainer 10 Seals 12. Retaining member 13 Circuit board 14 Cover 15 Acceleration sensor 16 Temperature Sensor 17, 17A power supply device 18 Wireless communication circuit 18a Antenna 19 Screws 26 Load 51 Voltage Doubler Rectifier Circuit 52 limiting circuit 53 Converter 54 Electronic Circuits 55, 55A, 55B step-down circuit 61, 61A 1st circuit.

Claims

1. A power supply device for driving an electronic circuit, characterized in that: The input voltage of the electronic circuit is determined to be in the first voltage range, The power supply device comprises: a first circuit that converts an AC voltage from a generator into a first DC voltage and outputs the converted DC voltage; and a second circuit configured to output a second DC voltage adjusted from the first DC voltage to the first voltage range to the electronic circuit; The input voltage of the second circuit is determined to be within a second voltage range. The first circuit converts the AC voltage into the first DC voltage adjusted to the second voltage range.

2. The power supply device according to claim 1, characterized in that: The first circuit includes a limiting circuit, The limiter circuit adjusts a DC voltage input to the limiter circuit to the first DC voltage within the second voltage range.

3. The power supply device according to claim 2, characterized in that: The first circuit includes a voltage doubling rectifier circuit that converts the AC voltage into a stepped-up DC voltage and outputs the stepped-up DC voltage.

4. The power supply device according to claim 3, characterized in that: The first circuit includes a step-down circuit for stepping down the DC voltage output from the voltage doubler rectifier circuit and outputting the stepped-down DC voltage to the limiting circuit. The larger the DC voltage output from the voltage doubler rectifier circuit is, the greater the voltage reduction by the step-down circuit will be.

5. The power supply device according to any one of claims 1 to 4, characterized in that: The second voltage range is greater than or equal to 15V and less than or equal to 20V.

6. A bearing device, characterized in that: include: A power supply device as claimed in any one of claims 1 to 4; Rotating components; as well as The generator generates an AC voltage according to the rotation of the rotating member.

7. The bearing device according to claim 6, characterized in that The bearing device comprises: Bearings; a sensor that monitors a condition of the bearing; and A communication circuit wirelessly transmits the detection value of the sensor to an external device, and the electronic circuit includes the sensor and the communication circuit.

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