Power conversion device and unmanned carrier

Abstract

To provide a power conversion device capable of more accurately detecting a torque applied to an output side and serving as a device that detects the torque.SOLUTION: A power conversion device includes: a shaft that transmits power; a strain sensor mounted on the shaft, for detecting a torque generated on the shaft; a radio apparatus that is connected to the strain sensor, converts an electric signal detected by the strain sensor into digital data, and wirelessly transmits the digital data; and a battery connected to the radio apparatus, for supplying electric power to the radio apparatus and the strain sensor.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a power conversion device such as a reducer, and to an automated guided vehicle having such a reducer interposed between a traveling motor and wheels. [Background technology]

[0002] Automated guided vehicles (AGVs, etc.) carry and transport cargo in factories and warehouses, replacing the transportation tasks that were previously performed by humans.

[0003] In such an automated guided vehicle, if the load exceeds the weight limit, the drive system for driving the vehicle will be damaged, so it is necessary to detect whether the load is overweight. Patent Document 1 discloses a technology in which an automated guided vehicle is equipped with a torque sensor that measures the torque of the driving motor, and stops the motor when it detects that the load is overweight. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Paragraphs 0034 to 0036 of the specification of JP 2020-019312 A Summary of the Invention [Problem to be solved by the invention]

[0005] In an automated guided vehicle, a reducer is interposed between the travel motor and the wheels to increase the load capacity. In this case, detecting the motor torque as in the technique disclosed in Patent Document 1 may not accurately detect overweight.

[0006] Although Patent Document 1 does not disclose the method of arranging the torque sensor, it is necessary to consider the inclusion of such a torque sensor as one of the components of the automated guided vehicle. For example, it is necessary to design the automated guided vehicle taking into consideration the torque sensor's arrangement space, wiring, etc. This increases the number of parts in the automated guided vehicle and requires special space for the torque sensor.

[0007] In view of the above circumstances, an object of the present invention is to provide a power conversion device that can more accurately detect torque applied to the output side and that itself serves as a torque detection device, and an unmanned guided vehicle in which a reducer, which is one aspect of this power conversion device, is interposed between a driving motor and wheels. [Means for solving the problem]

[0008] A power conversion device according to the present invention includes a shaft that transmits power, a strain sensor attached to the shaft for detecting torque acting on the shaft, a radio connected to the strain sensor for converting an electrical signal detected by the strain sensor into digital data and transmitting the digital data wirelessly, and a power storage unit connected to the radio for supplying power to the radio and the strain sensor. A typical example of the power conversion device is a reducer. The present invention can also be applied to a power transmission such as a gearbox. In the power conversion device according to the present invention, torque is detected in the power conversion device close to the output side of the drivetrain, for example, so that torque acting on the output side can be detected more accurately. Furthermore, because the power conversion device itself detects torque and transmits the digital data of the detection results wirelessly, it itself acts as a device for detecting torque, and torque can be detected without increasing the number of parts in the drivetrain, for example, or requiring special space.

[0009] The power conversion device according to the present invention further includes a power generation unit in which a current generating portion for generating electric power rotates together with the shaft, and which supplies the generated electric power to the electric storage unit. In the power conversion device according to the present invention, the power generating unit has a coil that rotates together with the shaft and a magnet for generating a current in the rotating coil, and is a generator that supplies the electric power generated by the coil to the power storage unit. The power storage unit according to the present invention is attached to the shaft side that rotates together with the strain sensor. Therefore, if power is supplied to the power storage unit from an external device using a contact system, the configuration of the power transmission system from the non-rotating side to the rotating side becomes complicated. However, in the present invention, the current generating section for the generated power rotates together with the shaft, and the generated power is supplied to the power storage unit, so a complicated power transmission system configuration is not necessary. Furthermore, particularly if power generated by a generator using a coil that rotates together with the power storage unit is supplied to the power storage unit, energy efficiency is also significantly improved.

[0010] In the power conversion device of the present invention, the strain sensor has a MEMS structure that deforms due to an external force and a microcomputer unit that converts the strain generated in the deformed MEMS structure into the electrical signal in accordance with a variable gain, and the radio receives a command to set the gain wirelessly and sets the gain in accordance with the command. In the present invention, individual differences in the detection sensitivity of strain sensors and errors that occur when attaching a strain sensor to an axis can be calibrated by setting the gain from a PC or the like without performing any connection work.

[0011] In the power conversion device according to the present invention, the strain sensor has a MEMS temperature sensor and a temperature calibration function for autonomously adjusting the gain in accordance with the temperature detected by the MEMS temperature sensor. While temperature drift of the sensor is likely to occur during use of the power conversion device, the provision of the temperature calibration function according to the present invention makes it possible to calibrate detection errors due to temperature drift.

[0012] The power conversion device according to the present invention further includes a vibration detection sensor, typically a MEMS sensor, attached to the shaft for detecting vibrations occurring on the shaft. The wireless device is connected to the vibration detection MEMS sensor, converts the electrical signal related to the vibration detected by the vibration detection MEMS sensor into digital vibration data, and transmits the digital vibration data wirelessly. This makes the power conversion device according to the present invention a device that detects vibrations, and can detect vibrations without increasing the number of parts in the drivetrain or requiring special space. The vibration sensor also includes an acceleration sensor, etc.

[0013] In the power conversion device according to the present invention, the shaft is the output shaft of the power conversion device, which makes it possible to more accurately detect the torque acting on the output side.

[0014] An automated guided vehicle according to the present invention comprises a motor for running, wheels, a shaft interposed between the motor and the wheels for transmitting power, a strain sensor attached to the shaft for detecting torque generated on the shaft, a radio connected to the strain sensor for converting an electrical signal detected by the strain sensor into digital data and transmitting the digital data wirelessly, a reducer connected to the radio and having a power storage unit for supplying power to the radio and the strain sensor, and detection means for receiving the transmitted digital data and detecting an abnormality based on the received digital data. The automated guided vehicle according to the present invention is an "automated guided vehicle" in the broad sense that includes not only AGVs (Automatic Guided Vehicles) but also AMRs (Autonomous Mobile Robots) and the like. [Effects of the Invention]

[0015] According to the present invention, it is possible to provide a power conversion device that can more accurately detect torque applied to the output side and that itself serves as a device for detecting torque. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a schematic configuration diagram of a power transmission system using a reducer according to an embodiment of the present invention. [Figure 2] 1 is a diagram showing a part of the internal configuration of the output side of a reducer having an output shaft and a gear attached to the output shaft of the reducer according to an embodiment of the present invention. FIG. [Figure 3] 1 is a block diagram showing a configuration of a detection system including a sensor unit according to an embodiment of the present invention. [Figure 4] 1 is a block diagram showing a configuration of a MEMS strain sensor according to an embodiment of the present invention. [Figure 5] 1 is a block diagram showing a configuration of a radio device according to an embodiment of the present invention; [Figure 6] 1 is a diagram showing a schematic configuration of an automated guided vehicle according to an embodiment of the present invention; DETAILED DESCRIPTION OF THE INVENTION

[0017] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram of a power transmission system using a reducer according to one embodiment of the present invention. As shown in the figure, a power transmission system 1 has a reducer 4 interposed between a motor 2 and a load side such as wheels 3.

[0018] The reducer 4 has an input shaft 5 and an output shaft 6 as shafts for transmitting power, and the rotating shaft 7 of the motor 2 is connected to the input shaft 5 of the reducer 4, while a shaft 8 on the load side, such as the wheels 3, is connected to the output shaft 6 of the reducer 4. The reducer 4 reduces the rotation speed of the motor 2 with gears 9, and obtains high torque on the load side, such as the wheels 3.

[0019] FIG. 2 is a diagram showing a part of the internal configuration of the output side of the reducer 4, which has the output shaft 6 of the reducer 4 and a gear 9 attached to this output shaft 6. As shown in FIG. As shown in the figure, the output shaft 6 rotates integrally with the rotation of the gear 9 . The sensor unit 10 and the coil 12 of the generator 11 are attached to the output shaft 6. The sensor unit 10 and the coil 12 of the generator 11 are preferably disposed inside the housing 22 of the reducer 4.

[0020] The sensor unit 10 includes a MEMS strain sensor 13, a wireless device 14, a battery 15, and a MEMS sensor 16 for detecting vibrations. The MEMS strain sensor 13 is attached to a region of the output shaft 6 where torsion occurs. The region of the output shaft 6 where torsion occurs does not include the surface of the tip of the output shaft 6, etc. A groove 17 with a flat bottom is provided at the position on the output shaft 6 where the MEMS strain sensor 13 is to be attached, and the MEMS strain sensor 13 is attached to the bottom of the groove 17 via a metal plate-like member 18, and the MEMS strain sensor 13 is sealed with a sealing member 19. The MEMS strain sensor 13 is adhered to the surface of the plate-like member 18 with an adhesive, for example, and attached to a screw hole (not shown) in the bottom surface of the groove 17 with a bolt (not shown) via a hole (not shown) drilled in the plate-like member 18. The MEMS strain sensor 13 may also be attached directly to the output shaft 6, for example.

[0021] The flexible wiring 20 of the MEMS strain sensor 13 is connected to the radio 14. The vibration detection MEMS sensor 16 is also connected to the radio 14 via wiring (not shown). The radio 14 is connected to a battery 15 via a power cable (not shown). The battery 15 is connected to the coil 12 of the generator 11. Coil 12 of generator 11 is attached to output shaft 6 and rotates together with output shaft 6. Magnet 21 of generator 11 is attached to the housing 22 side of reducer 4 so as to face coil 12.

[0022] FIG. 3 is a block diagram showing the configuration of a detection system including the sensor unit 10. As shown in FIG. As shown in the figure, the MEMS strain sensor 13 detects the torque generated in the output shaft 6. The vibration detection MEMS sensor 16 detects vibrations occurring in the output shaft 6 . The radio 14 converts the electrical signal detected by the MEMS strain sensor 13 into digital data related to the strain, and also converts the electrical signal detected by the vibration detection MEMS sensor 16 into digital data related to the vibration, and transmits the digital data related to the strain and the digital data related to the vibration wirelessly. The digital data here refers to data converted into numerical values ​​that can be handled by, for example, Microsoft Excel, making it easy to import into a PC at high speed. The battery 15 supplies power to the wireless device 14, the MEMS strain sensor 13, and the vibration detection MEMS sensor 16. The battery 15 supplies power to the wireless device 14 via a power cable 23. The MEMS strain sensor 13 and the vibration detection MEMS sensor 16 are supplied with power from the battery 15 via the wireless device 14.

[0023] The coil 12 of the generator 11 and the magnet 21 of the opposing generator 11 constitute the generator 11. The power generated by the generator 11 is supplied to the battery 15. Of course, the present invention may be configured without such a generator 11 and by charging the battery 15 each time, but having such a generator 11 eliminates the need for charging. Furthermore, while power may be supplied to the battery 15 from an external device using a contact system, such a configuration would complicate the power transmission system between the non-rotating side and the rotating side, and a contactless power supply configuration that transmits power using electromagnetic induction would result in poor energy efficiency. In contrast, in this embodiment, the generator 11 is constituted by the coil 12 that rotates with the output shaft 6 and the magnet 21 that generates current in the rotating coil 12, and power generated by the coil 12 that rotates with the rotating battery 15 is supplied to the battery 15. This eliminates the need for a complex power transmission system and significantly improves energy efficiency.

[0024] The abnormality detection device 24 has a wireless communication unit 25 that communicates wirelessly with the radio 14 on the sensor unit 10 side, and a PLC (Programmable Logic Controller) 26 connected to the wireless communication unit 25, and determines that an abnormality has occurred when the strain detected by the MEMS strain sensor 13 or the vibration detected by the MEMS sensor 16 for temperature or vibration detection exceeds a predetermined threshold, for example.

[0025] The wireless terminal 27, such as a PC, can wirelessly communicate with the wireless device 14 of the sensor unit 10, and can set the gain of the MEMS strain sensor 13, as will be described later. The wireless terminal 27 may also be configured to monitor torque, etc.

[0026] FIG. 4 is a block diagram showing the configuration of the MEMS strain sensor 13. As shown in FIG. As shown in FIG. 4, the MEMS strain sensor 13 includes a MEMS structure 28, a MEMS temperature sensor 29, a microcomputer unit 30, and an input / output unit 31.

[0027] The MEMS structure 28 is deformed by an external force, and when a twist occurs in the output shaft 6, a distortion occurs in the plate-like member 18. The MEMS structure 28 detects the distortion as a twist in the output shaft 6. The MEMS temperature sensor 29 typically detects the temperature of the MEMS strain sensor 13 .

[0028] The microcomputer unit 30 detects the strain generated in the deformed MEMS structure 28 as an electrical signal and converts the detected electrical signal into an electrical signal according to a set gain. The gain set in the microcomputer unit 30 can be changed by an external command. For example, the wireless terminal 27 sets the gain of the microcomputer unit 30 via the wireless device 14. This makes it possible to calibrate individual differences in the performance of the MEMS strain sensor 13. Furthermore, errors that occur when the reducer 4 is attached to the drive and traveling system of an automated guided vehicle, for example, can be calibrated by setting the gain from the wireless terminal 27, such as a PC, without having to perform any work such as connecting the reducer 4 to the reducer 4. The microcomputer unit 30 has a temperature calibration function for autonomously adjusting the gain according to the temperature detected by the MEMS temperature sensor 29. This makes it possible to calibrate drift due to the influence of temperature. In particular, in the reducer 4, frictional heat and the like increases during operation, causing a temperature rise that affects the output of the MEMS structure 28, but this temperature calibration function makes it possible to compensate for this output.

[0029] The input / output unit 31 is connected to the flexible wiring 20, and outputs electrical signals related to the detected strain and temperature to the outside via the flexible wiring 20, and also inputs commands from the outside, and is further supplied with power from the outside.

[0030] FIG. 5 is a block diagram showing the configuration of the radio device 14. As shown in the figure, the radio device 14 has first and second input / output units 32 and 33, first and second A / D conversion units 34 and 35, a microcomputer module 36, a power supply connection unit 37, and an antenna 38.

[0031] The first input / output unit 32 inputs electrical signals related to strain and temperature from the MEMS strain sensor 13 via the flexible wiring 20, outputs commands from the outside to the MEMS strain sensor 13, and also supplies power from the outside to the MEMS strain sensor 13. The second input / output unit 33 inputs an electrical signal relating to vibration from the vibration detection MEMS sensor 16, and also supplies power to the vibration detection MEMS sensor 16 from the outside. The first and second A / D converters 34 and 35 convert the electrical signals relating to the strain and the electrical signals relating to the temperature input from the first and second input / output units 32 and 33 into digital data, respectively. The microcomputer module 36 converts the digital signals converted by the first and second A / D converters 34 and 35 into digital data, and transmits the converted digital data wirelessly via an antenna 38 . A power cable 23 from the battery 15 is connected to the power supply connector 37, and power is supplied from the battery 15 to the radio 14. The radio 14 uses this power as its operating power, and also supplies this power to the MEMS strain sensor 13 and the MEMS sensor 16 for vibration detection via the first and second input / output units 32, 33.

[0032] FIG. 6 is a diagram showing a schematic configuration of an automatic guided vehicle 39 in which the reducer 4 configured as above is mounted in its drive and traveling system. As shown in Fig. 6, an automated guided vehicle 39 has four motors 2 for driving, four wheels 3, four reducers 4 interposed between each motor 2 and each wheel 3, a wireless communication unit 25, a PLC 26 that controls various aspects of the automated guided vehicle 39, and a patrol lamp 40. In this example, the four wheels are driven by four motors, but the four wheels may be driven by two motors, or the four wheels may be driven by one motor. Also, the number of wheels does not have to be four.

[0033] In such an automated guided vehicle 39, digital data relating to the distortion corresponding to the torque applied to the output shaft 6 detected by each reducer 4, digital data relating to the temperature corresponding to the temperature detected by the reducer 4, and digital data relating to the vibration corresponding to the vibration detected by the reducer 4 are transmitted to the PLC 26 via wireless communication between each reducer 4 and the PLC 26. The PLC 26 typically monitors these digital data every moment, and if it detects an abnormality in torque, temperature, or vibration, it will, for example, turn on a patrol lamp 40 or forcibly stop the automatic guided vehicle 39 from traveling. This makes it possible to prevent, for example, the load loaded on the automatic guided vehicle 39 from exceeding the weight limit and damaging the driving system for traveling.

[0034] In the automated guided vehicle 39 according to this embodiment, the reducer 4 itself serves as a device for detecting abnormalities in torque, temperature, and vibration, and transmits the detection results wirelessly, so there is no need to consider, for example, the placement space or wiring of a torque sensor when configuring the automated guided vehicle 39. This makes it possible to suppress increases in the number of parts and space required for the automated guided vehicle 39. Furthermore, in the automated guided vehicle 39 according to this embodiment, torque is detected by the reducer 4, particularly by its output shaft 6, so the torque applied to the output side can be detected more accurately.

[0035] Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and it goes without saying that various modifications can be made within the scope of the gist of the present invention. The present invention is applicable to various reducers such as planetary gear reducers, worm reducers, gear reducers, and bevel gear reducers. The present invention is applicable not only to speed reducers but also to power transmissions such as gearboxes. The present invention is applicable not only to automated guided vehicles, but also to various devices and systems that employ power transmissions. In the above embodiment, a MEMS strain sensor has been used as an example of a strain sensor, but the present invention is not limited to this. Any sensor that detects the amount of deformation of a material when subjected to an external force may be used as a strain sensor. For example, a strain sensor that detects the deformation of metal in response to an external force using electrical resistance, a strain sensor that uses the piezoelectric effect, or a strain sensor that detects the reflection of light using an optical fiber may be used. In the above embodiment, a battery was used as an example of the power storage unit, but the present invention is not limited to this, and the power storage unit may be anything that can store power to supply power, such as a capacitor or condenser. In the above embodiment, a generator consisting of a pair of coils and a magnet has been used as an example of the power generation unit, but the present invention is not limited to this. The power generation unit may be any unit in which the current generating part for generating power rotates together with the axis and the generated power is supplied to the power storage unit. Examples of power generation units that can be used include vibration power generation, which converts minute vibration energy into electrical energy, temperature difference power generation using a thermoelectric conversion element to generate power from temperature differences, and power generation using solar panels. The power conversion device according to the present invention can be used as a device for detecting torque, temperature, and vibration abnormalities as well as a device for detecting rotation speed. For example, the wireless device 14 may calculate the rotation speed of the output shaft 6 based on periodic changes in vibration detected by the vibration detection MEMS sensor 16 and wirelessly transmit digital data related to the rotation speed. Alternatively, the PLC 26 or wireless terminal 27 may calculate the rotation speed of the output shaft 6 based on periodic changes in digital data related to vibration received. Similarly, the rotation speed of the output shaft 6 may be calculated based on digital data related to strain. [Explanation of symbols]

[0036] 1 Power transmission system 2 motors 3 wheels 4 Reducer 5 Input shaft 6 Output shaft 9. Gears 10 Sensor Unit 11. Generator 12 coils 13 MEMS strain sensor 14 Radio 15 Battery 16 MEMS sensors for vibration detection 17 Groove 18 Plate-shaped member 19 Sealing member 20 Flexible wiring 21 Magnet 22 Reducer housing 24 Anomaly detection device 25 Wireless Communication Unit 26 PLC(Programmable Logic Controller) 27 Wireless terminals 28 MEMS Structure 29 MEMS temperature sensors 30 Microcomputer Section 34 First A / D conversion unit 35 Second A / D conversion section 39 Automated Guided Vehicle 40 Patrol Lamp

Claims

1. a shaft for transmitting power; a strain sensor attached to the shaft for detecting a torque acting on the shaft; a radio connected to the strain sensor, converting an electrical signal detected by the strain sensor into digital data, and transmitting the digital data by radio; a power storage unit connected to the radio for supplying power to the radio and the strain sensor; A power conversion device comprising:

2. 2. The power conversion device according to claim 1, a power generating section for supplying the generated power to the power storage section, the power generating section having a current generating portion for generating the power rotating together with the shaft; The power conversion device further comprises:

3. 3. The power conversion device according to claim 2, The power generating unit is a generator that has a coil that rotates together with the shaft and a magnet for generating a current in the rotating coil, and supplies the electric power generated by the coil to the power storage unit. Power conversion device.

4. The power conversion device according to any one of claims 1 to 3, the strain sensor is a MEMS strain sensor; the MEMS strain sensor includes a MEMS structure that is deformed by an external force, and a microcomputer that converts strain generated in the deformed MEMS structure into the electrical signal in accordance with a variable gain; The radio device receives a command to set the gain wirelessly and sets the gain in response to the command. Power conversion device.

5. 5. The power conversion device according to claim 4, The MEMS strain sensor has a MEMS temperature sensor and a temperature calibration function for autonomously adjusting the gain in accordance with the temperature detected by the MEMS temperature sensor. Power conversion device.

6. The power conversion device according to any one of claims 1 to 5, a vibration detection sensor attached to the shaft for detecting vibrations occurring in the shaft; The wireless device is connected to the vibration detection sensor, converts an electrical signal related to the vibration detected by the vibration detection sensor into digital data of the vibration, and transmits the digital data of the vibration by wireless. Power conversion device.

7. The power conversion device according to any one of claims 1 to 6, The shaft is an output shaft of the power conversion device. Power conversion device.

8. A driving motor; Wheels and a reducer having a shaft interposed between the motor and a wheel for transmitting power, a strain sensor attached to the shaft for detecting torque generated on the shaft, a radio connected to the strain sensor for converting an electrical signal detected by the strain sensor into digital data and transmitting the digital data by radio, and a power storage unit connected to the radio for supplying power to the radio and the strain sensor; a detection means for receiving the transmitted digital data and detecting an abnormality based on the received digital data; An automated guided vehicle equipped with the above.

Images