JP2008307626A - Arm lock device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an arm lock device capable of sufficiently increasing locking force to prevent rotation of an arm in compact constitution. <P>SOLUTION: A transfer cylinder 26 is stored in a cylinder of cylindrical housing 20 free to rotate and a second arm 14 is connected to the transfer cylinder 26. An output shaft 24 of an electric motor 23 is connected to the transfer cylinder 26 through a disc 25. A first load receiving cylinder 31 and a second load receiving cylinder 32 are stored in the housing 20 between a flange 29 formed on the disc 25 and a flange 30 formed on the transfer cylinder 26. A roller bearing 35 is interposed between a first flank 331 formed on the first load receiving cylinder 31 and a second flank 341 formed on the second load receiving cylinder 32. The first load receiving cylinder 31 is held at a locking position by spring force of a torsion spring 40 and the spring force of the torsion spring 40 is converted to a thrust load for locking through the roller bearing 35. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an arm lock device that locks rotation of an arm that is rotatably connected to a connecting portion.

  In a robot arm mechanism in which the second arm is rotatably connected to the first arm (see, for example, Patent Document 2), when specifying the rotation position of the second arm with respect to the first arm as a desired rotation position, this specification is performed. It is necessary to lock the second arm with respect to the first arm at the rotated position. As a locking device for performing such locking, for example, a clamping device disclosed in Patent Document 1 can be adopted.

In the clamp device disclosed in Patent Literature 1, an elastic case that surrounds an annular output flange and the output flange are fastened (locked) to each other by elastically deforming an elastically deformable elastic member by high pressure. The elastic member is elastically deformed by directly receiving the fluid pressure (hydraulic pressure or air pressure) supplied to the pressure chamber.
Japanese Patent Laid-Open No. 11-210715 JP 2002-160188 A

  In order to obtain a large force for fastening (locking) the case and the output flange to each other by fluid pressure, it is difficult to make the fluid pressure output mechanism large. Moreover, it is necessary to efficiently transmit the fluid pressure per unit area to the contact portion of the elastic member with respect to the case and the output flange, but unlike the liquid that can directly transmit the fluid pressure per unit area to other parts, the elastic member This is difficult to achieve.

Therefore, it is difficult to sufficiently increase the torsional rigidity between the first arm and the second arm in the locked state (locking force that prevents rotation of the other arm with respect to one arm).
An object of the present invention is to provide an arm lock device capable of sufficiently increasing a lock force for preventing rotation of an arm with a compact configuration.

  According to a first aspect of the present invention, there is provided an arm, a rotation output unit provided on the arm, a rotation driving means for rotating the rotation output unit, and a first rotation unit rotatably provided around a rotation axis of the rotation output unit. A first load receiving portion, a second load receiving portion provided so as to face the first load receiving portion and capable of being pressed against the rotation output portion, the first load receiving portion, and the second load receiving portion. And a load increasing means for converting a driving force for normal rotation of the first load receiving portion into a thrust load by the wedge effect and transmitting the thrust load to the second load receiving portion, and the first load receiving portion by the thrust load. And a switching mechanism that switches and arranges the first load receiving portion between a lock position where the load receiving portion is pressed against the rotation output portion and a lock release position where the load receiving portion can be rotated forward toward the lock position. Features.

  When the arm support unit is connected to the rotation output unit, the arm rotates relative to the arm support unit when the rotation output unit rotates. When the second arm is connected to the rotation output unit, the second arm rotates relative to the first arm when the rotation output unit rotates. When the first load receiving portion is disposed at the lock position, the rotation output portion and the arm are locked. Since the load increasing means for converting the rotational force into the thrust load by the wedge effect generates a large thrust load, the locking force for preventing the rotation of the arm can be sufficiently increased. Further, such a load increasing means can be configured compactly.

  In a preferred example, the load increasing means is provided on a facing surface of the first load receiving portion facing the second load receiving portion so as to become a descending slope toward the forward rotation direction. A second inclined surface provided on the facing surface of the second load receiving portion facing the first load receiving portion so as to become an ascending slope toward the normal rotation direction, the first inclined surface, and the first And a roller bearing interposed between the two inclined surfaces.

  The load increasing means including the first inclined surface, the second inclined surface, and the roller bearing is particularly suitable for converting the rotational force into a large thrust load with a compact configuration and for easily releasing the locked state.

In a preferred example, three or more pairs of the first slope and the second slope are provided around the rotation axis.
In such a configuration, the thrust load is distributed around the rotation axis so as not to be an uneven load.

  In a preferred example, the switching mechanism includes a linear actuator and a driving force transmission mechanism that converts the linear driving force of the linear actuator into a rotational driving force that rotates the first load receiving portion in a direction opposite to the normal rotation direction. And.

Since the load increasing means generates a large thrust load, the linear driving force of the linear actuator can be small.
In a preferred example, the switching mechanism includes a spring member for urging the first load receiving portion in the forward rotation direction, and the spring is in the state where the first load receiving portion is disposed at the lock position. The member holds the first load receiving portion in the locked position by its spring force.

The configuration in which the first load receiving portion is held at the lock position by the spring force of the spring member is simple in order to hold the arm lock.
In a preferred example, the arm includes a cylindrical case serving as an outer shell, and the linear actuator is accommodated in the cylindrical case.

  In a preferred example, the linear actuator is a fluid pressure cylinder, and the rotation output portion and the fluid pressure cylinder are provided on a proximal end side and a distal end side of the arm, respectively, and the pair of fluid pressure cylinders The pressure chambers are common.

  Such a configuration contributes to the compactness of the arm lock device.

  The arm lock device of the present invention has an excellent effect that the lock force for preventing the rotation of the arm can be sufficiently increased with a compact configuration.

Hereinafter, an embodiment embodying the present invention will be described with reference to FIGS.
FIG. 1 shows an articulated robot 10. The articulated robot 10 is connected to a base 11, an arm support 12 fixed on the base 11, a first arm 13 rotatably supported by the arm support 12, and a first arm 13 rotatably. And the second arm 14.

2A and 2B show the internal structure of the first arm 13 on the tip side.
As shown in FIG. 2A, a pressure chamber forming cylinder 16 is fitted and fixed in a cylindrical case 15 which is an outer shell of the first arm 13, and one end side of the pressure chamber forming cylinder 16 [FIG. The cylinder 17 is fitted and fixed to the left side in FIG. A pressure chamber 161 is formed in the pressure chamber forming cylinder 16. The pressure chamber 161 communicates with a supply source (not shown) of pressure fluid (pressure oil or pressure air) via a supply port 162 and an electromagnetic three-way valve (not shown). A piston 18 is slidably accommodated in the cylinder 17. The pressure chamber 161, the cylinder 17 and the piston 18 constitute a fluid pressure cylinder which is a linear actuator.

  A cam plate 19 is integrally formed with the piston 18 so as to extend in the sliding direction of the piston 18, and a cam groove 191 is formed in the cam plate 19. A cylindrical housing 20 is connected and fixed to a distal end of the cylindrical case 15 (left end in FIG. 2A) with a screw 21 (shown in FIG. 1).

  As shown in FIG. 2B, an attachment plate 22 is connected and fixed to the end of the cylindrical housing 20, and an electric motor 23 is attached to the attachment plate 22. The electric motor 23 is a servo motor with a built-in speed reducer. An output shaft 24 of the electric motor 23 penetrates the mounting plate 22 and enters the cylindrical housing 20, and a disk 25 is fixed to the output shaft 24 in the housing 20. The disc 25 is rotatably supported by the housing 20 via a radial bearing 28. A transmission cylinder 26 is fitted and fixed to the disc 25. The central axis 261 of the transmission cylinder 26 is made to coincide with the rotation axis 241 of the output shaft 24. That is, the central axis 261 is the rotational axis of the transmission cylinder 26. The transmission cylinder 26 is rotatably supported by the housing 20 via a radial bearing 28.

  The second arm 14 is connected to a transmission cylinder 26 as a rotation output unit. The transmission cylinder 26 and the second arm 14 are integrally rotated about the central axis 261 by the operation of the electric motor 23 as the rotation driving means. The position of the second arm 14 shown by the chain line in FIG. 1 shows an example of the rotation and movement from the position of the second arm 14 shown by the solid line.

  As shown in FIG. 2B, a flange 29 is integrally formed on the outer peripheral surface of the disc 25, and a flange 30 is integrally formed on the outer peripheral surface of the transmission cylinder 26. A first load receiving cylinder 31 and a second load receiving cylinder 32 are coaxially accommodated in the housing 20 between the flange 29 and the flange 30. The first load receiving cylinder 31 is rotatable with respect to the housing 20, and a thrust bearing 36 is interposed between the first load receiving cylinder 31 and the flange 29.

  A screw 37 for position regulation is screwed to the second load receiving cylinder 32 through a position regulation hole 201 penetrating the cylindrical housing 20. A position regulating cylinder 38 is fitted in the position regulating hole 201, and the position regulating cylinder 38 is fixed to the outer peripheral surface of the second load receiving cylinder 32 by tightening a screw 37. The position restricting cylinder 38 fitted in the position restricting hole 201 prevents the rotation of the second load receiving cylinder 32 around the center axis 261, and the second load receiving cylinder 32 cannot rotate around the center axis 261. It is. A brake pad 39 is provided between the second load receiving cylinder 32 and the flange 30.

  A plurality of first inclined surfaces 331 are formed on an end surface 33 that is a facing surface of the first load receiving cylinder 31 that faces the second load receiving cylinder 32, and the second load receiving cylinder that faces the first load receiving cylinder 31. A plurality of second inclined surfaces 341 are formed on the end surface 34 that is the opposing surface of the second surface 32. The first slope 331 has a shape that becomes a descending slope as it goes in the direction indicated by the arrow R in FIGS. 2A and 2B, and the second slope 341 becomes an ascending slope as it goes in the direction indicated by the arrow R. Shape. The first slope 331 and the second slope 341 are parallel to each other.

  A roller bearing 35 is interposed between each first slope 331 and each second slope 341. As shown in FIGS. 6 and 7, in the present embodiment, four first inclined surfaces 331 and two second inclined surfaces 341 are provided. That is, four pairs of the first inclined surface 331 and the second inclined surface 341 are provided around the central axis 261.

  As shown in FIG. 2B, a torsion spring 40 is accommodated in the cylinder of the first load receiving cylinder 31. The stationary end 401 of the torsion spring 40 as a spring member is locked to the housing 20, and the movable end 402 of the torsion spring 40 is locked to the first load receiving cylinder 31. As shown in FIG. 2A, one end of a rod 41 is connected and fixed to the first load receiving cylinder 31, and a rotor 42 is attached to the other end of the rod 41. The rotor 42 is engaged with the cam groove 191. The reciprocation of the piston 18 is transmitted to the rod 41 and the first load receiving cylinder 31 through the engagement of the cam groove 191 and the rotor 42, and the first load receiving cylinder 31 rotates around the central axis 261. .

  The spring force of the torsion spring 40 urges the first load receiving cylinder 31 in the direction of arrow R (hereinafter referred to as the forward rotation direction R). That is, the spring force of the torsion spring 40 urges the rod 41 in the forward rotation direction about the central axis 261, and the piston 18 is applied toward the pressure chamber forming cylinder 16 by the spring force of the torsion spring 40. It is energized.

  2A and 2B show a state where the pressure chamber 161 is not at the pressure of the pressure fluid. In this state, the piston 18 is disposed at the standby position approaching the pressure chamber forming cylinder 16 by the spring force of the torsion spring 40, and the first load receiving cylinder 31 is disposed at the lock position shown in FIGS. 2 (a) and 2 (b). Is done. This lock position is a forward rotation limit position at which the first load receiving cylinder 31 cannot normally rotate in the forward rotation direction R. When the first load receiving cylinder 31 is disposed at the lock position, the spring force of the torsion spring 40 (the driving force that causes the first load receiving cylinder 31 to rotate forward) is applied to the first inclined surface 331, the roller bearing 35, and the second inclined surface 341. It is converted into a thrust load (a load acting in the axial direction of the central axis 261) by the wedge effect. 2A and 2B, the transmission cylinder 26 and the second arm 14 cannot rotate with respect to the first arm 13.

  FIG. 8A is a developed view schematically showing the positional relationship between the first load receiving cylinder 31 and the second load receiving cylinder 32 when the first load receiving cylinder 31 is in the locked position. When the first load receiving cylinder 31 is in the locked position, the thrust load obtained by converting the spring force of the torsion spring 40 (indicated by an arrow F in FIG. 8A) increases so as to be larger than the spring force of the torsion spring 40. Is done. This increase rate depends on the magnitude of the inclination angle θ of the first slope 331 and the second slope 341 (shown in FIG. 8A).

  The thrust load F presses the second load receiving cylinder 32 against the brake pad 39 and presses the brake pad 39 against the flange 30. Thereby, the transmission cylinder 26 is locked. The reaction force of the thrust load F is received by the flange 29 via the thrust bearing 36.

  4A and 4B show a state in which the pressure chamber 161 is at the pressure of the pressure fluid. In this state, when the piston 18 is arranged at the operating position away from the pressure chamber forming cylinder 16 against the spring force of the torsion spring 40, and the piston 18 is arranged from the standby position to the operating position, the first load receiving cylinder. 31 is rotated in the direction opposite to the normal rotation direction. Thereby, the 1st load receiving cylinder 31 is arrange | positioned in the lock release position shown to Fig.4 (a), (b). The pressure of the pressure fluid in the pressure chamber 161 that drives the piston 18 from the standby position to the operating position is a linear driving force that linearly drives the piston 18.

  The lock release position of the first load receiving cylinder 31 is a position where the first load receiving cylinder 31 can be rotated forward in the forward rotation direction R. When the first load receiving cylinder 31 is disposed at the unlock position, the wedge effect of the first inclined surface 331, the roller bearing 35, and the second inclined surface 341 is eliminated, and the spring force of the torsion spring 40 is converted into a thrust load. Absent. 4 (a) and 4 (b), the transmission cylinder 26 and the second arm 14 are rotatable with respect to the first arm 13.

FIG. 8B is a developed view schematically showing the positional relationship between the first load receiving cylinder 31 and the second load receiving cylinder 32 when the first load receiving cylinder 31 is in the unlocked position.
The housing 20, the mounting plate 22 and the transmission cylinder 26 have a rotation output part (transmission cylinder 26) and constitute a connection part 43 provided at one end of the first arm 13. The first load receiving cylinder 31 is a first load receiving section provided rotatably around a rotation axis [center axis 261] of the transmission cylinder 26 as a rotation output section. The second load receiving cylinder 32 and the brake pad 39 are provided so as to face the first load receiving cylinder 31, to be non-rotatable around the central axis 261, and to be able to press against the transmission cylinder 26. Configure the receiving part.

  The electric motor 23 is rotation driving means for rotating the transmission cylinder 26 as a rotation output unit. The first inclined surface 331, the second inclined surface 341, and the roller bearing 35 are provided between the first load receiving cylinder 31 and the second load receiving cylinder 32, and have a driving force for normal rotation of the first load receiving cylinder 31. A load increasing means for converting to a thrust load by the effect and transmitting it to the second load receiving cylinder 32 is configured. The pressure chamber 161, the cylinder 17 and the piston 18 constitute a linear actuator that generates a linear driving force. The torsion spring 40, the rod 41, the rotor 42, the cam groove 191 and the linear actuator have the first load receiving cylinder 31 at a lock position that is a forward rotation limit position in the forward rotation direction and a lock release position that can be rotated forward. A switching mechanism for switching arrangement is configured. The rod 41, the rotor 42, and the cam groove 191 constitute a driving force transmission mechanism that converts the linear driving force of the linear actuator into a rotational driving force and transmits it to the first load receiving cylinder 31.

  As shown in FIGS. 3A and 3B, a connecting portion 43 </ b> A having the same configuration as the connecting portion 43 shown in FIGS. 2A and 2B is also provided on the proximal end side of the first arm 13. Further, the same mechanism as the other mechanisms (rotation drive mechanism, load increasing means, and drive force transmission mechanism) shown in FIGS. 2A and 2B is also provided on the proximal end side of the first arm 13. 3 (a) and 3 (b), the same components as those shown in FIGS. 2 (a) and 2 (b) except for the connecting portion 43 are denoted by the same reference numerals. The pressure of the pressure fluid in the pressure chamber 161 also acts on the piston 18 on the connecting portion 43A side. In other words, the piston 18 constituting the linear actuator on the connecting portion 43 side and the pressure chamber 161 that is the drive source of the piston 18 constituting the linear actuator on the connecting portion 43A side are common.

  The transmission cylinder 26 in the connecting portion 43 </ b> A is connected and fixed to the arm support portion 12. Therefore, when the electric motor 23 provided in the connecting portion 43A is operated, the first arm 13 rotates around the central axis 261 of the transmission cylinder 26 of the connecting portion 43A. The position of the 1st arm 13 shown with a dashed line in Drawing 1 shows an example which rotated and moved from the position of the 1st arm 13 shown with a solid line.

  3A and 3B show a state in which the pressure chamber 161 is not at the pressure of the pressure fluid. In this state, the piston 18 on the connecting portion 43A side is disposed at a standby position close to the pressure chamber forming cylinder 16 by the spring force of the torsion spring 40, and the first load receiving cylinder 31 on the connecting portion 43A side is shown in FIG. , (B) is disposed at the lock position. 3A and 3B, the transmission cylinder 26 and the first arm 13 are not rotatable with respect to the arm support portion 12.

  5A and 5B show a state in which the pressure chamber 161 is at the pressure of the pressure fluid. In this state, the piston 18 on the connecting portion 43A side is disposed at the operating position away from the pressure chamber forming cylinder 16 against the spring force of the torsion spring 40, and the first load receiving cylinder 31 on the connecting portion 43A side is shown in FIG. It is arranged at the unlocking position shown in (a) and (b). 5A and 5B, the transmission cylinder 26 and the first arm 13 can rotate with respect to the arm support portion 12.

In the present embodiment, the following effects can be obtained.
(1) The load increasing means for converting the rotational force into the thrust load by the wedge effect generates a large thrust load by appropriately setting the inclination angle θ of the first inclined surface 331 and the second inclined surface 341. Therefore, the locking force that prevents the rotation of the first arm 13 and the second arm 14 can be sufficiently increased. Further, the load increasing means using the wedge effect can be configured compactly.

  (2) The configuration in which the roller bearing 35 is interposed between the first inclined surface 331 and the second inclined surface 341 is to easily reverse the first load receiving cylinder 31 in the locked position from the locked position to the unlocked position side. enable. The first inclined surface 331, the second inclined surface 341, and the roller bearing 35 are particularly suitable for converting the rotational force into a large thrust load with a compact configuration and for easily releasing the locked state.

  (3) The configuration in which four pairs of the first inclined surface 331 and the second inclined surface 341 are provided around the central axis 261 so that the thrust load acting on the second load receiving cylinder 32 is not an unbalanced load. It is suitable for dispersing around.

  (4) Since the load increasing means generates a large thrust load, the linear driving force of the linear actuator, that is, the pressure of the pressure fluid that drives the piston 18 may be small. Further, since the pressure receiving area of the piston 18 does not need to be increased, the diameter of the first arm 13 can be reduced.

  (5) The torsion spring 40 holds the first load receiving cylinder 31 in the locked position by the spring force. The configuration in which the first load receiving cylinder 31 is held in the locked position by the spring force of the torsion spring 40 is a simple configuration in order to always hold the lock of the first arm 13 and the second arm 14 with a constant thrust load. .

  (6) In the configuration in which the fluid pressure cylinder (pressure chamber forming cylinder 16, cylinder 17 and piston 18) is accommodated in the cylindrical case 15, the cylindrical case 15 constituting the first arm 13 supports the fluid pressure cylinder. Used as The configuration in which the first arm 13 is effectively used as an installation space for the fluid pressure cylinder (linear actuator) contributes to the compactness of the first arm 13.

  (7) The configuration in which the pressure chamber 161 of the fluid pressure cylinder on the connection portion 43 side and the pressure chamber 161 that is the drive source of the fluid pressure cylinder on the connection portion 43A side contributes to the compactness of the arm lock device.

In the present invention, the following embodiments are also possible.
The number of pairs of the first slope 331 and the second slope 341 may be 3 pairs or 5 pairs or more.
One end of the rod 41 may be rotatably connected to the first load receiving cylinder 31 and the other end of the rod 41 may be rotatably connected to the piston 18. That is, you may make it the 1st load receiving cylinder 31 and the rod 41 comprise a crank mechanism.

  The first load receiving cylinder 31 is held in the unlocked position by the spring force of the torsion spring 40, and the first load receiving cylinder 31 is held in the locked position when the pressure chamber 161 is pressurized with the pressure fluid. Also good.

○ A tension spring or a compression spring may be used instead of the torsion spring.
○ Only the rotation drive mechanism, the load increasing means and the driving force transmission mechanism attached to the connection portion 43A and the connection portion 43A are provided in the first arm 13, and the connection portion 43 provided in the first arm 13 is provided in the second arm 14. It is also possible to provide the second arm 14 with a rotational drive mechanism, a load increasing means, and a driving force transmission mechanism attached to the connecting portion 43.

  ○ The brake pad 39 may be omitted.

The perspective view which shows one Embodiment. (A) is sectional drawing which shows the state which hold | maintained the 1st load receiving cylinder in the lock position. (B) is the sectional view on the AA line of Fig.2 (a). (A) is sectional drawing which shows the state which hold | maintained the 1st load receiving cylinder in the lock position. (B) is the BB sectional drawing of Fig.3 (a). (A) is sectional drawing which shows the state which hold | maintained the 1st load receiving cylinder in the lock release position. (B) is CC sectional view taken on the line of Fig.4 (a). (A) is sectional drawing which shows the state which hold | maintained the 1st load receiving cylinder in the lock release position. (B) is the DD sectional view taken on the line of Fig.5 (a). The partial perspective view which shows the state which hold | maintained the 1st load receiving cylinder in the lock position. The partial perspective view which shows the state which hold | maintained the 1st load receiving pipe | tube in the lock release position. (A) is a schematic diagram which shows the state which hold | maintained the 1st load receiving cylinder in the lock position. (B) is a schematic diagram which shows the state which hold | maintained the 1st load receiving cylinder in the lock release position.

Explanation of symbols

  13 ... 1st arm. 15 ... A cylindrical case as an outer shell. 161 A pressure chamber constituting a fluid pressure cylinder as a linear actuator. 17: A cylinder constituting a fluid pressure cylinder as a linear actuator. 18: A piston constituting a linear actuator. 20 A housing constituting the connecting portion. 191 ... Cam groove constituting a driving force transmission mechanism. 22: A mounting plate constituting the connecting portion. 23: An electric motor as rotation driving means. 241: A rotational axis. 26: A transmission cylinder as a rotation output unit. 261: A central axis as a rotation axis. 31 ... 1st load receiving cylinder as 1st load receiving part, 32 ... 2nd load receiving cylinder which comprises 2nd load receiving part. 331: A first slope constituting load increasing means. 341 ... A second slope constituting the load increasing means. 33, 34 ... End faces as opposed surfaces. 35 ... Roller bearing constituting load increasing means. 39 ... Brake pads constituting the second load receiving portion. 40 ... A torsion spring as a spring member constituting the switching mechanism. 41 ... A rod constituting a driving force transmission mechanism. 42: A rotor constituting a driving force transmission mechanism. 43, 43A ... Connection part. R: Forward direction.

Claims (7)

Arm,
A rotation output section provided on the arm;
Rotation drive means for rotating the rotation output unit;
A first load receiving portion rotatably provided around a rotation axis of the rotation output portion;
A second load receiving portion provided so as to face the first load receiving portion and capable of being pressed against the rotation output portion;
Provided between the first load receiving portion and the second load receiving portion, a driving force for normal rotation of the first load receiving portion is converted into a thrust load by a wedge effect and transmitted to the second load receiving portion. Load increasing means to
A switching mechanism that switches and arranges the first load receiving portion between a lock position where the second load receiving portion is pressed against the rotation output portion by the thrust load and a lock release position where the second load receiving portion can be rotated forward toward the lock position; Arm lock device equipped with.   The load increasing means includes a first slope provided on a facing surface of the first load receiving portion facing the second load receiving portion so as to be a descending slope toward the forward rotation direction, and the first load receiving portion. A second inclined surface provided on the facing surface of the second load receiving portion facing the load receiving portion so as to form an ascending slope toward the forward rotation direction, and between the first inclined surface and the second inclined surface. The arm lock device according to claim 1, further comprising a roller bearing interposed in the arm.   The arm lock device according to claim 2, wherein three or more pairs of the first slope and the second slope are provided around the rotation axis.   The switching mechanism includes a linear actuator and a driving force transmission mechanism that converts the linear driving force of the linear actuator into a rotational driving force that rotates the first load receiving portion in a direction opposite to the normal rotation direction. The arm lock device according to any one of claims 1 to 3.   The switching mechanism includes a spring member for urging the first load receiving portion in the forward rotation direction. When the first load receiving portion is disposed at the lock position, the spring member The arm lock device according to claim 4, wherein the first load receiving portion is held at the lock position by force.   The arm lock device according to claim 4 or 5, wherein the arm includes a cylindrical case serving as an outer shell, and the linear actuator is accommodated in the cylindrical case.   The linear actuator is a fluid pressure cylinder, and the rotation output portion and the fluid pressure cylinder are provided on the proximal end side and the distal end side of the arm, respectively, and the pressure chambers of the pair of fluid pressure cylinders are: The arm lock device according to any one of claims 4 to 6, which is common.

Images