JP2009255194A - Parallel mechanism - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a parallel mechanism certainly preventing food or pharmaceutical pollution or the like caused by a leaked lubricant by certainly preventing the leaked lubricant from dropping onto the surfaces of a table and a conveyer even if a lubricant is leaked from the output shaft of a speed reduction gear for any reason. <P>SOLUTION: The speed reduction gear of a drive motor and a fastening plate are oppositely arranged across a motor bracket, and these three members are fastened and fixed. A lubricant receiver is provided in the faying surfaces of the motor bracket and fastening plate, facing a lubricant flowing-down route, thereby catching the lubricant leaked from the output shaft of the speed reduction gear by the lubricant receiver and preventing the leaked lubricant from flowing down any more. A lubricant reservoir is formed in a part of the lubricant receiver, and a sensor detecting the leaked lubricant is arranged to face the lubricant reservoir. Accordingly, lubricant leakage is immediately detected by the sensor, and an alarm device is operated based on a sensing signal. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a parallel mechanism used as, for example, an industrial robot, and more particularly to a rotary parallel mechanism in which an operation head is supported by a plurality of pairs of arm units.

  The basic structure of this type of parallel mechanism is known, for example, from Patent Document 1. There, a parallel mechanism with a base, three servo motors arranged evenly on the lower surface of the base, three arm units driven by the servo motors, and an operation head supported by the three arm units, etc. Is configured. If necessary, a ball spline shaft that transmits rotational power while expanding and contracting between the base and the operation head is added. On the lower surface side of the operation head, a hand for capturing a processing target is provided, and the base frame is disposed above the operation space of the operation head.

  Each arm unit is composed of a drive arm that is swiveled up and down by a servo motor and a rod that transmits the swivel motion of the drive arm to the operation head. The rod is connected to the drive arm and the operation head by a ball joint. It is. The ball spline shaft is composed of a drive shaft and a passive shaft that are connected in a telescopic manner, and upper and lower ends are connected via a universal joint. By changing the drive direction and drive amount of each drive arm, the operation head can be freely displaced in a predetermined three-dimensional space. This type of parallel mechanism can also be seen in Patent Document 2, in which the rotational power of the servo motor is decelerated by a speed reducer (transmission device), and then the drive arm is attached to the flange provided on the output shaft of the speed reducer. It is fixed.

JP 2001-277164 A (paragraph numbers 0006 to 7, FIG. 1) JP 2005-528993 A (paragraph number 0020, FIG. 3)

  In a reduction gear incorporated in a servo motor, a lubricant (grease) for lubricating the reduction gear is filled inside the bearing that supports the output shaft, and the outer surface side of the bearing is sealed with a lubricant seal. It has stopped. In the case of a general speed reducer, the output shaft rotates over 360 degrees, so that the previous lubricant can be evenly distributed over the entire reduction gear, and the lubricant does not leak out. However, the entire turning angle of the drive arm (or output shaft) in the rotary parallel mechanism is only about 90 degrees, and therefore the lubricant cannot be evenly distributed over the entire reduction gear. In addition, the parallel mechanism repeatedly reciprocates the operation head while accelerating and decelerating, for example, at a speed of 120 to 180 cycles / min. It tends to accumulate in the lower part of the rotation trajectory of the reduction gear. Lubricant accumulated below the gear housing is pressurized by the rotation of the reduction gear, passes between the inner and outer rings of the bearing, is carried to the oil seal side, and is further pushed out from the seal lip to leak out to the outside. There is a risk of dripping on the conveyor.

  Incidentally, the rotary parallel mechanism is installed across the work table and the conveyor, and a servo motor is arranged above the work space of the operation head. Therefore, when the parallel mechanism is used in the food industry or the pharmaceutical industry, if there is a lubricant leak as described above, the leaked lubricant may contaminate the food or the medicine, which causes a serious problem. If the leakage of the lubricant from the reducer is surely prevented, the above problem can be solved. However, with the rotary parallel mechanism in which the entire turning angle of the drive arm is only about 90 degrees as described above, there still remains anxiety. .

  The object of the present invention is to reliably prevent the leaking lubricant from dropping on the upper surface of the table or conveyor even if the lubricant leaks from the output shaft of the speed reducer. The object is to provide a parallel mechanism that can reliably prevent contamination and the like. The purpose of the present invention is to allow leakage lubricant to be stored for a certain period of time, to protect foods and pharmaceuticals due to leakage lubricant multiple times, and to detect and warn that the lubricant has leaked. It is to provide a parallel mechanism capable of accurately dealing with lubricant leakage.

  In the parallel mechanism of the present invention, a base is arranged above the work area of the operation head, and a drive motor for turning the drive arm up and down is mounted on a motor bracket fixed to a plurality of locations on the base. The turning motion of the drive arm is transmitted to the operation head via the rod. The drive motor is equipped with a reduction gear. The speed reducer and the fastening plate are opposed to each other with the motor bracket interposed therebetween, and the three members, the speed reducer, the motor bracket, and the fastening plate, are integrally fastened and fixed. A lubricant receiver for receiving the leaked lubricant is provided on the joint surface between the motor bracket and the fastening plate facing the flow path of the lubricant leaked from the output shaft of the speed reducer.

  A lubricant reservoir is provided in any one of the motor bracket, the fastening plate, and the motor cover that is fixed to the motor bracket and covers the outer surface of the drive motor.

  A control circuit that controls the operating state of the drive motor and a display device that displays the state of the control circuit are provided. A sensor for detecting the leaked lubricant is disposed in a part of the lubricant holding path from the lubricant receiver to the lubricant reservoir. The control circuit is configured to receive the output signal from the sensor that has detected the leaked lubricant and to stop the drive motor and / or display the stop on the display device.

  The end peripheral surface of the reduction gear housing and the end peripheral surface of the drive arm fixed to the output shaft of the reduction gear are surrounded by an arm opening provided in the fastening plate. In the lower half of the inner peripheral surface of the arm opening, a lubricant receptacle is cut out and formed on the side of the joint surface with the motor bracket, and a lubricant reservoir is recessed to face the lubricant receptacle. The sensor is mounted on the fastening plate facing the lubricant reservoir.

  The sensor is provided in the vicinity of the light projecting unit, the light receiving unit, and the lubricant reservoir, and includes a lens unit that collects detection light from the light projecting unit toward the lubricant reservoir, a light projecting unit, and a light receiving unit. It is composed of an optical sensor including a driving circuit for driving. Accordingly, the reflected light or transmitted light of the detection light irradiated from the light projecting unit toward the lubricant reservoir is received by the light receiving unit, and the presence or absence of the leaking lubricant is detected by the light amount change in the light receiving unit.

  In the parallel mechanism of the present invention, the reduction gear of the drive motor and the fastening plate are disposed opposite to each other with the motor bracket interposed therebetween, and these three members are fastened and fixed together. In addition, a lubricant receiver is provided on the joint surface between the motor bracket and the fastening plate facing the lubricant flow path so that the lubricant leaking from the output shaft of the speed reducer is received by the lubricant receiver. Thus, according to the parallel mechanism of the present invention, even if the lubricant leaks from the output shaft of the speed reducer, the leaked lubricant is received by the lubricant receiver, and the leaked lubricant further flows down. Or it can prevent dissipating. Therefore, it is possible to reliably prevent leaking lubricant from dripping onto the top surface of tables, conveyors, etc., especially in the manufacturing process where sanitation standards are strict, such as food and medicine that must not be contaminated by leaking lubricant. Therefore, it is possible to provide a parallel mechanism suitable for the above.

  If a lubricant reservoir is provided on any of the motor bracket, fastening plate, or motor cover so that the lubricant guided by the lubricant receiver can be stored in the lubricant reservoir, the leaked lubricant is stored in the lubricant reservoir for a certain period of time. can do. Therefore, even when the amount of lubricant that leaks is abnormally large, emergency measures such as an emergency stop of the drive motor or a stop of the conveyor can be accurately performed with a margin. In addition, since the leaked lubricant can be received by the lubricant receiver and stored in the lubricant reservoir, the dripping of the leaked lubricant can be prevented in multiple ways to prevent food and pharmaceuticals from being damaged by the leaked lubricant and maintain a hygienic state. it can.

  When a sensor is placed in a part of the lubricant holding path from the lubricant receiver to the lubricant reservoir, and when the sensor detects the leaked lubricant, the fact is displayed on the display device, it is quickly confirmed that the lubricant has leaked. It is possible to detect and warn the administrator to prompt the administrator to take emergency measures such as stopping the device. Also, when the sensor detects leaked lubricant, stop the drive motor and display it on the display device, and then take emergency measures to the administrator while preventing further leakage of the lubricant. Can be urged. Therefore, even if a lubricant leakage accident occurs, the subsequent emergency measures can be taken accurately. Also, since it is sufficient to handle the accident before the leaked lubricant fills the lubricant reservoir, emergency measures after the lubricant leak is detected by the sensor can be performed with sufficient time. it can.

  When the lubricant receiver is cut out in the lower half of the opening of the fastening plate arm, the lubricant reservoir is recessed toward the lubricant receptacle, and the sensor is mounted on the fastening plate in the state of facing the lubricant reservoir, lubrication occurs. All of the structure that prevents the dripping of the agent can be concentrated on the fastening plate. Therefore, compared with the case where a lubricant dripping prevention structure is formed on the motor bracket or a part of it is provided on the motor cover, the lubricant dripping prevention structure can be simplified, and processing such as a lubricant receiver and a lubricant reservoir can be performed. Can save time and effort. The seal structure provided accompanying the lubricant receptacle and the lubricant reservoir can be simplified.

  When a sensor is configured with a light projecting unit and a light receiving unit, a lens unit, and a drive circuit that drives the light projecting unit and the light receiving unit, the reflected light or transmitted light of the detection light emitted from the light projecting unit is received by the light receiving unit. Thus, the presence or absence of the leaking lubricant can be detected from the change in the amount of light in the light receiving unit. Therefore, the detection of the leaking lubricant can always be performed reliably in a stable state.

(Example) FIGS. 1-5 shows the Example which applied the parallel mechanism based on this invention to the conveyance robot. As shown in FIG. 2, the parallel mechanism is configured with a high-rigidity base 1 installed in a state straddling a table or a conveyor as a base. Specifically, a base 2 fixed to the upper wall of the gantry 1, three drive motors 3 disposed on the lower surface of the base 2, three arm units 4 driven by the drive motor 3, and each arm unit 4 comprises an operation head 5 supported by 4 and a drive shaft 6 arranged at the center.

  The base 2 is located above the operation space of the operation head 5, and a motor 7 for rotating the drive shaft 6 is provided on the upper surface thereof. As shown in FIG. 4, the drive motor 3 integrally includes a servo motor and a speed reducer 9, and outputs the reciprocating turning power decelerated by the speed reducer 9 via the output shaft 10. Further, a feedback signal is output to the control circuit 11 (see FIG. 1) by a rotary encoder built in the servo motor. The driving motor 3 is controlled in its driving direction, driving amount and driving speed by a command signal from the control circuit 11. The outer surface of the drive motor 3 is hermetically covered by a motor cover 47 fixed to the motor bracket 12. Similarly to the drive motor 3, the motor 7 includes a servo motor and a speed reducer.

  Three motor brackets 12 are fastened and fixed to the lower surface of the base 2 at equal intervals, and the drive motor 3 is assembled to these motor brackets 12. Specifically, the speed reducer 9 and the fastening plate 13 are arranged opposite to each other with the motor bracket 12 interposed therebetween, and four bolts 14 are screwed into the fastening plate 13 from the side of the speed reducer 9, and the drive motor 3, the fastening plate 13, and The motor bracket 12 is integrated (see FIG. 4).

  For this purpose, a flange 15 to be joined to the fastening seat of the motor bracket 12 is formed in the housing of the speed reducer 9, and a shaft portion 16 that is continuously fitted on the fastening hole of the motor bracket 12 is formed on the flange 15. . The motor bracket 12 is formed with a bolt insertion hole for inserting the bolt 14 and a previous fastening hole. As shown in FIG. 5, the fastening plate 13 is formed of a rectangular frame, has a circular arm opening 18 at the center thereof, and has screw holes 19 for the bolts 14 at the four corners of the frame. It is. The three drive motors 3 are fixed to the base 2 with their central axes constituting each side of an equilateral triangle, and the centers of the equilateral triangles coincide with the axial center position of the motor 7.

  The arm unit 4 includes a drive arm 21 that is swiveled up and down by the drive motor 3 and a rod 22 that transmits a swiveling operation of the drive arm 21 to the operation head 5. An arm boss 23 is fixed to the base end of the drive arm 21, and this arm boss 23 is fixed to the output shaft 10 of the speed reducer 9. In a state where the arm boss 23 is fixed to the output shaft 10, the end peripheral surface of the housing of the speed reducer 9 and the end peripheral surface of the arm boss 23 are surrounded by an arm opening 18 provided in the fastening plate 13 (FIG. 4). reference).

  As shown in FIG. 3, the rod 22 includes a pair of link rods 24 arranged in parallel and a spring unit 25 provided near the upper and lower ends of the link rods 24 and pulling and urging both link rods 24. It is. The drive arm 21, the operation head 5, and the rod 22 are connected by ball joints 26, respectively. As described above, according to the arm unit 4 connected via the ball joint 26, the operation head 5 can be freely moved in a predetermined three-dimensional space by reciprocating the drive arm 21 up and down with the drive motor 3. Can be displaced. Of the space in which the operating head 5 can be displaced three-dimensionally, an operating range having a diameter of 1040 mm and a height of 200 mm on the reference plane is the working area of the operating head 5. A line connecting the ball centers of the opposing ball joints 26 is parallel to the central axis of the previous drive motor 3. The reference plane means the upper surface of the table or conveyor on which the conveyance target is placed.

  The operation head 5 is formed of a triangular plate-like block, and an operation shaft 28 that inherits the rotational power of the drive shaft 6 is rotatably supported at the center thereof. The drive shaft 6 includes a ball spline shaft provided with an upper half drive spline shaft 29 and a lower half passive spline shaft 30. The upper and lower ends of the spline shafts 29 and 30 are connected to the output shaft of the motor 7 and the previous operation shaft 28 via universal joints 31, respectively. A capturing body (not shown) that captures the object to be conveyed is attached to the flange portion at the lower end of the operation shaft 28.

  The shaft end of the output shaft 10 of the speed reducer 9 is formed in a flange shape, and an arm boss 23 is fastened and fixed to the flange portion with six bolts 33. As shown in FIG. 4, the output shaft 10 is supported by a bearing 34, and the outer surface side of the bearing 34 is sealed with an oil seal 35. In preparation for the case where the sealing action of the oil seal 35 is overcome and the lubricant (grease) in the speed reducer 9 may leak, a lubricant receptacle 37 is provided in the flow path of the leaked lubricant, and the lubricant receptacle is further received. A lubricant reservoir 38 for storing the lubricant flowing down along 37 is provided.

  As shown in FIGS. 1 and 5, the lubricant receiver 37 is formed at the lower half portion of the inner peripheral surface of the arm opening 18 by cutting out the wall of the joint surface with the motor bracket 12 in a semicircular shape. . In addition, a vertically recessed long pocket is formed near the center of the lower portion of the lubricant receiver 37, and this pocket portion is used as a lubricant reservoir 38. The formation range angle of the lubricant receiver 37 is approximately twice the total turning angle (around 90 degrees) of the drive arm 21, which effectively prevents the leaked lubricant that has been splashed off from the shaft end of the output shaft 10. It can be received by the lubricant receiver 37. The locations where the lubricant receiver 37 and the lubricant reservoir 38 are formed are sealed with a seal body 39 interposed between the motor bracket 12 and the fastening plate 13.

  A sensor 40 for detecting leaked lubricant is provided in a part of the lubricant holding path from the lubricant receiver 37 to the lubricant reservoir 38. In this embodiment, the sensor 40 is composed of an optical fiber sensor, and the lens portion 41 is screwed and fixed to the fastening plate 13 so as to face the lubricant reservoir 38. The sensor 40 includes a lens unit 41, a light projecting / receiving unit 42 provided outside the base 2, and a pair of optical fibers 43 connecting the lens unit 41 and the light projecting / receiving unit 42. Projected light and reflected light can be transmitted by the pair of optical fibers 43.

  The projection light radiated from the lens unit 41 is received after being reflected by the inner peripheral wall of the lubricant reservoir 38 facing the lens unit 41. However, the reflectance of the projection light is constant when there is no lubricant leakage. However, when the leaking lubricant flows into the lubricant reservoir 38, the light path is blocked by the lubricant film, so that the reflectance of the projected light changes. By detecting that the reflectance has changed beyond the threshold value by the light projecting / receiving unit 42, it is possible to detect that the lubricant has leaked.

  Further, the display device 44 can be operated by a command signal output from the control circuit 11 by sending a detection signal output from the light projecting / receiving unit 42 to the control circuit 11. The display device 44 turns on the warning lamp and simultaneously emits a warning sound from the speaker to notify the administrator that the lubricant is leaking. At the same time, the liquid crystal display of the control device displays that the lubricant is leaking.

  At the same time when the sensor 40 outputs the detection signal, the control circuit 11 stops the driving motor 3 and the motor 7 and stops the parallel mechanism. Thereby, it is possible to reliably prevent the leakage lubricant from dripping from the fastening plate 13. Even if the drive motor 3 cannot be stopped for some reason, the leaked lubricant can continue to be stored until the leaked lubricant overflows from the lubricant reservoir 38. Multiple protection against food and pharmaceutical contamination. Alternatively, the leakage of the lubricant can be dealt with with a sufficient margin until the leaked lubricant fills the lubricant reservoir 38. For example, it is possible to take an emergency measure such as stopping the driving of the conveyor after a predetermined time has elapsed from the time when the sensor 40 outputs the detection signal and then stopping the parallel mechanism.

  As described above, if the light projecting / receiving unit 42 is installed at a location that is cut off from the vibration of the base, it is possible to accurately detect the presence or absence of the leaked lubricant without being affected by mechanical vibration or temperature change. Therefore, the leakage lubricant can be detected reliably in a stable state at all times. In addition, since the projection light and the reflected light are transmitted through the optical fiber 43, there is an advantage that the installation position of the light projecting / receiving unit 42 can be freely selected.

  In the above embodiment, the fastening plate 13 is provided with the lubricant receiver 37 and the lubricant reservoir 38, but this is not necessary. For example, the lubricant receiver 37 and the lubricant reservoir 38 can be provided in the motor bracket 12. In that case, the sensor 40 may be provided on the motor bracket 12. Further, the lubricant reservoir 38 is provided in the motor cover 47, and the lubricant receiver 37 and the lubricant reservoir 38 can be communicated with each other through a passage formed in the motor bracket 12. The lens portion 41 can be provided facing the lubricant receptacle 37, and the lens portions 41 may be provided at a plurality of locations if necessary. A plurality of lubricant reservoirs 38 can be provided.

  Since the shape and the depth of the recess of the lubricant reservoir 38 can be freely set as necessary, the shape is not limited to the shape described in the embodiment. The sensor 40 is provided in the vicinity of a light projecting unit, a light receiving unit, and a lubricant reservoir, and a lens unit that collects detection light from the light projecting unit toward the lubricant reservoir, a light projecting unit, and a light receiving unit. It can be constituted by an optical sensor including a drive circuit for driving the sensor. In that case, the presence or absence of leaking lubricant is detected from the change in the amount of light in the light receiving unit by receiving the reflected light or transmitted light of the detection light emitted from the light projecting unit toward the lubricant reservoir. Can do. The sensor 40 can be installed by separating the light projecting unit and the light receiving unit. Further, the lens unit 41 and the light projecting / receiving unit 42 may be integrated without using an optical fiber. Furthermore, the sensor 40 does not need to be a light emitting / receiving optical sensor, and may be another type of optical sensor such as an image sensor. Further, a level sensor other than the optical sensor may be used. The parallel mechanism can be used with the drive shaft 6 omitted, and can be widely applied to industries other than the food industry and the pharmaceutical industry as needed.

It is sectional drawing which shows a lubricant leakage prevention structure. It is a front view of a parallel mechanism. It is a top view of a parallel mechanism. It is the sectional view on the AA line in FIG. It is a perspective view in the state where a fastening plate was separated.

Explanation of symbols

2 Base 3 Drive motor 5 Operation head 9 Reducer 12 Motor bracket 13 Fastening plate 14 Bolt 21 Drive arm 22 Rod 37 Lubricant receptacle 38 Lubricant reservoir 40 Sensor

Claims (5)

A base is disposed above the work area of the operation head, and a drive motor that pivots the drive arm up and down is mounted on a motor bracket fixed at a plurality of locations on the base. A parallel mechanism for transmitting to the operation head via a rod,
The drive motor is integrally provided with a speed reducer,
The speed reducer and the fastening plate are arranged opposite to each other with the motor bracket interposed therebetween, and the three of the speed reducer, the motor bracket, and the fastening plate are fastened and fixed integrally.
A parallel mechanism, wherein a lubricant receptacle for receiving the leaked lubricant is provided on a joint surface between the motor bracket and the fastening plate facing a flow path of the lubricant leaked from the output shaft of the speed reducer.   A lubricant reservoir for storing the lubricant flowed down by the lubricant receiver is provided in any one of the motor bracket, the fastening plate, and a motor cover fixed to the motor bracket and covering an outer surface of the drive motor. The parallel mechanism according to claim 1, which is provided. A control circuit for controlling the operating state of the drive motor, and a display device for displaying the state of the control circuit;
A sensor for detecting a leaked lubricant is arranged in a part of the lubricant holding path from the lubricant receiver to the lubricant reservoir,
3. The control circuit is configured to receive an output signal from the sensor that has detected a leaking lubricant, and to stop the drive motor and / or display the stop on the display device. The described parallel mechanism. An end peripheral surface of the speed reducer housing and an end peripheral surface of a drive arm fixed to the output shaft of the speed reducer are surrounded by an arm opening provided in the fastening plate,
The lubricant receptacle is notched and formed in the lower half of the inner peripheral surface of the arm opening on the side of the joint surface with the motor bracket, and the lubricant reservoir is recessed to face the lubricant receptacle. ,
The parallel mechanism according to claim 3, wherein the sensor is attached to the fastening plate so as to face the lubricant reservoir. The sensor is provided in the vicinity of a light projecting unit, a light receiving unit, the lubricant reservoir, and a lens unit for condensing detection light from the light projecting unit toward the lubricant reservoir, and the light projecting And an optical sensor including a driving circuit for driving the light receiving unit,
The reflected light or transmitted light of the detection light irradiated toward the said lubricant reservoir from the said light projection part is received by the said light-receiving part, and the presence or absence of the said leaking lubricant is detected by the light quantity change in the said light-receiving part. 4. The parallel mechanism according to 4.

Images