Drive transmission mechanism

Abstract

The present invention provides a drive transmission mechanism that prevents motor overload when external forces are applied, while eliminating the need for manual correction of misalignment. [Solution] The drive transmission mechanism 300 includes a drive plate 314 fixed to the rotating shaft of the motor 400 and provided with a shaft portion 315b substantially parallel to the rotating shaft; a driven plate 324 rotatable in the direction of rotation of the rotating shaft and connected to the object to be driven, and provided with a shaft portion 325b substantially parallel to the rotating shaft; a clamping portion 353b that is movable along the direction of rotation of the rotating shaft and can contact the shaft portions 315b and 325b; a clamping portion 354b that is movable along the direction of rotation of the rotating shaft and can contact the shaft portions 315b and 325b from the opposite side of the clamping portion 353b; and a spiral spring 355 that biases the clamping portions 353b and 354b toward the shaft portions 315b and 325b, respectively.

Description

Technical Field

[0001] The present invention relates to a drive transmission mechanism that transmits the driving force of a motor to a driving object.

Background Art

[0002] As a remote control device that enables remote operation of construction machinery and the like, there is one that drives an operation unit that operates an operation lever or the like of a construction machine with an actuator such as a pneumatic or electric motor.

[0003] For example, in a machine that moves a lever described in Patent Document 1 that drives an operation unit with a motor, a first actuator and a second actuator composed of motors are provided, and the output of the first output shaft (orthogonal to the second output shaft) of the first actuator that rotates around the second output shaft of the second actuator is transmitted to a lever, which is a driving object, by a drive transmission mechanism including a link mechanism and an operation unit including a connector, and the lever can be moved in two orthogonal directions.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] By the way, when driving a driving object with a motor, if the setting of the movable range is inappropriate, an obstacle appears, an external force acts, and it becomes impossible to drive with the output of the motor, it is necessary to protect the motor from torque overload (overcurrent).

[0006] However, if a commercially available torque limiter (overload protection device) is interposed between the motor's rotating shaft and the control unit, a misalignment will occur between the motor's rotating shaft and the control unit when the limiter activates and the input / output is disconnected. This necessitates a recovery operation to restore the rotational position of the rotating shaft and the three-dimensional position of the control unit to their predetermined correspondence.

[0007] This invention has been made in view of the above circumstances, and aims to provide a drive transmission mechanism that prevents motor overload when an external force is applied, while eliminating the need for positional correction work. [Means for solving the problem]

[0008] To solve the above problems, the drive transmission mechanism according to the present invention comprises: a drive unit fixed to the rotating shaft of a motor and provided with a first shaft portion substantially parallel to the rotating shaft; a driven unit rotatable in the rotational direction of the rotating shaft and connected to an object to be driven, and provided with a second shaft portion substantially parallel to the rotating shaft; a first clamping portion movable along the rotational direction and capable of contacting the first shaft portion and the second shaft portion; a second clamping portion movable along the rotational direction and capable of contacting the first shaft portion and the second shaft portion from the opposite side of the first clamping portion; and the first clamping portion and the second clamping portion respectively... The device comprises a shaft portion and an elastic body that biases toward the second shaft portion, and when the rotating shaft rotates and the drive unit is driven, if no constant external force is acting on the driven unit, the second shaft portion moves toward the first shaft portion while the first shaft portion and the second shaft portion are held by the first clamping portion and the second clamping portion, causing the driven unit to rotate, and when a constant external force is acting on the driven unit, the first shaft portion and the second shaft portion separate against the biasing force of the elastic body, releasing the clamping of the first shaft portion and the second shaft portion by the first clamping portion and the second clamping portion.

[0009] According to this drive transmission mechanism, when the rotating shaft rotates and the drive unit is driven, if a certain external force is acting on the driven unit, the first shaft and the second shaft separate against the biasing force of the elastic body, and the clamping between the first shaft and the second shaft by the first clamping part and the second clamping part is released. As a result, the external force acting on the driven unit is not directly transmitted to the drive unit, and motor overload can be prevented.

[0010] On the other hand, if a constant external force is no longer applied to the driven part, the first shaft and the second shaft will return to a state where they are clamped by the first and second clamping parts, and the second shaft will follow the first shaft, causing the driven part to rotate, thus eliminating the need for correcting the misalignment.

[0011] In the drive transmission mechanism according to the present invention, the drive unit and the driven unit may be plate-shaped and stacked in the thickness direction, thereby allowing the drive unit and the driven unit to be compactly housed in the direction of the motor's rotation axis.

[0012] The first clamping portion and the second clamping portion may be plate-shaped, which allows the first clamping portion and the second clamping portion to be compactly housed in the direction of the motor's rotation axis.

[0013] The first shaft portion and the second shaft portion may be cylindrical in shape, and as a result, the first clamping portion and the second clamping portion will be in contact with a cylindrical surface, so that the contact state can be stably maintained whether the second shaft portion follows the first shaft portion or moves away from the first shaft portion without following it.

[0014] The elastic body may be a spiral spring, which allows the first clamping portion and the second clamping portion to be easily biased toward the first shaft portion and the second shaft portion.

[0015] Furthermore, the object to be driven may be the operating lever of a construction machine, which prevents motor overload when an external force is applied to the driven part from the operating lever in a construction machine. [Effects of the Invention]

[0016] According to the drive transmission mechanism of the present invention, it is possible to prevent an overload of the motor when an external force acts and eliminate the need for a position deviation restoration operation.

Brief Description of the Drawings

[0017] [Figure 1] It is a perspective view showing a hydraulic excavator equipped with a remote control device including a drive transmission mechanism according to an embodiment for carrying out the invention. [Figure 2] It is a front view showing a hydraulic excavator. [Figure 3] It is a perspective view showing a remote control device. [Figure 4] It is a front view showing a remote control device. [Figure 5] It is a side view showing a remote control device. [Figure 6] It is a plan view showing the internal structure of the base of a remote control device. [Figure 7] It is a perspective view showing a support fitting of a remote control device. [Figure 8] It is a perspective view showing a motor and a drive transmission mechanism in a remote control device. [Figure 9] It is a perspective view showing the drive transmission mechanism disassembled. [Figure 10] It is a perspective view showing a remote control device with the drive transmission mechanism disassembled. [Figure 11] It is a perspective view showing a drive plate. [Figure 12] (a) is a bottom view showing a motor and a drive transmission mechanism, and (b) is a cross-sectional view taken along line A-A of (a). [Figure 13] It is a perspective view showing a driven plate. [Figure 14] It is a perspective view showing a driving mechanism and a driven mechanism. [Figure 15] It is a perspective view showing a spiral spring in a clamping mechanism. [Figure 16] It is a perspective view showing a clamping mechanism. [Figure 17]This is an explanatory diagram showing the drive plate, driven plate, and clamping part under overload conditions. [Figure 18] (a) is an explanatory diagram showing an example of current without an overload protection mechanism, and (b) is an explanatory diagram showing an example of current with an overload protection mechanism. [Modes for carrying out the invention]

[0018] Embodiments of the present invention will be described with reference to the drawings.

[0019] As shown in Figures 1 and 2, the drive transmission mechanism 300 according to this embodiment is used in a remote control device 200 that remotely operates the travel levers 110L, 110R and work levers 120L, 120R, which are the operating levers of the hydraulic excavator 100. It is interposed between the motor 400 (described later) and the work lever operating unit 250L that operates the work lever 120L, and transmits the driving force (output) of the motor 400 to the work lever operating unit 250L.

[0020] The hydraulic excavator 100 has crawler tracks 130L and 130R for travel, a cab 140, and a boom 150, with an arm and bucket (not shown in the illustration) attached to the tip of the boom 150.

[0021] An antenna (not shown in the diagram) is provided on the roof 141 of the cab 140 to receive control signals transmitted from a remote control 210 located outside the remote control device 200 (drive transmission mechanism 300), and a cockpit 160 is provided inside the cab 140. A cockpit 161 for the pilot to sit in is installed on the floor 162 of the cockpit 160.

[0022] In front of the cockpit 161, travel levers 110L and 110R for operating the crawler tracks 130L and 130R are provided, extending upward from the floor 162. To the left and right of the cockpit 161, work levers 120L and 120R for operating the boom 150, arm, and bucket are provided, with their upper parts tilted inward when viewed from the front. The hydraulic excavator 100 operates by rotating the crawler tracks 130L and 130R to move forward, backward, or rotate by operating the travel levers 110L and 110R, and by operating the work levers 120L and 120R to operate the boom 150, arm, and bucket to perform excavation work, etc.

[0023] As shown in Figures 3 to 6, the remote control device 200 includes a base 220 attached to the floor surface 162 in front of the cockpit 161, travel lever operating units 230L and 230R provided on the base 220 for operating the travel levers 110L and 110R, support units 240L and 240R provided on the base 220, work lever operating units 250L and 250R supported by the support units 240L and 240R for operating the work levers 120L and 120R, and a control unit 260 that receives control signals from the remote control 210 via an antenna and controls the travel lever operating units 230L and 230R and the work lever operating units 250L and 250R based on these control signals.

[0024] The base 220 has a base body 221 and four legs 222. The base body 221 is provided with travel lever operating sections 230L and 230R via drive transmission mechanisms 300A and 300B, which are substantially the same as the drive transmission mechanism 300, as described later, and is also provided with support sections 240L and 240R. The four legs 222 support the base body 221 at four points: the left front, right front, left rear, and right rear.

[0025] The legs 222 are attached to the base body 221 via ball joints 223, and their mounting angle is adjustable by the ball joints 223. The legs 222 are, in this case, magnetic holder bases, and a switch 222b is provided on the side 222a, allowing the magnetic force of the bottom surface 222c to be switched on or off by operating the switch 222b. The legs 222 are attached to the floor surface 162 by magnetic force, and even if the floor surface 162 is not necessarily flat, they magnetically adhere to the floor surface 162 and contribute to the stable fixing of the base 220.

[0026] The base body 221 has a box-shaped section 224 supported by the legs 222, and a box-shaped section 225 located below the box-shaped section 224 and between the left and right legs 222. An opening 226a is formed on the front surface 226 of the box-shaped section 224, an opening 227a communicating with the box-shaped section 225 is formed on the bottom surface 227, and openings 228 are formed on the sides. The top surface 229 of the box-shaped section 224 is flat, so that it can be made approximately parallel to the floor surface 162 when the base 220 is attached to the floor surface 162 by the legs 222.

[0027] The box-shaped section 225 is provided with motors 400A and 400B controlled by the control unit 260, and drive transmission mechanisms 300A and 300B located near the opening 227a that transmit the driving force of motors 400A and 400B to the travel lever operating sections 230L and 230R. The travel lever operating sections 230L and 230R extend forward of the base body 221, passing through the opening 226a.

[0028] The front ends of the travel lever operating sections 230L and 230R are provided with gripping sections 231L and 231R that grip the travel levers 110L and 110R. The travel lever operating sections 230L and 230R are driven by motors 400A and 400B to move forward and backward, and the gripping sections 231L and 231R tilt the travel levers 110L and 110R they grip in the forward and backward directions to operate them.

[0029] The support sections 240L and 240R are formed by bending or joining cylindrical metal tubes and have arm sections 241L and 241R that extend in the width direction (left-right direction), and arm sections 242L and 242R that extend upward and forward (diagonally upward) from the tips of the arm sections 241L and 241R, and are further bent to extend upward.

[0030] The arm sections 241L and 241R are attached to the bottom surface 227 of the box-shaped section 225 by two mounting brackets 243, with their widthwise position adjusted, and they pass through the opening 228. Two mounting brackets 244 are attached to the upper part of the arm sections 242L and 242R, with their heightwise position adjusted, and plate-shaped support brackets 245 and 246 are attached to the mounting brackets 244.

[0031] As shown in Figure 7, the support bracket 245 has two linear elongated holes 245a arranged vertically and two circular holes 245b arranged vertically, and is attached to the mounting bracket 244 by screws (not shown) that pass through the elongated holes 245a, with the width direction position being adjusted.

[0032] The support bracket 246 has an arc-shaped elongated hole 246a and a round hole 246b. A screw (not shown) is inserted through the elongated hole 246a and fixed to the lower of the two round holes 245b of the support bracket 245, and a screw (not shown) is inserted through the round hole 246b and fixed to the upper of the two round holes 245b of the support bracket 245. However, because the elongated hole 246a is arc-shaped, the angle of inclination of the support bracket 246 relative to the support bracket 245 when viewed from the front changes depending on the insertion position of the screw. Therefore, the support bracket 246 is attached to the support bracket 245 after its angle of inclination has been adjusted.

[0033] The support bracket 246 on the side of the support section 240L supports the work lever operating section 250L via a drive transmission mechanism 300C and a drive transmission mechanism 300, which are substantially the same as the drive transmission mechanism 300. The drive transmission mechanism 300C has a portion corresponding to the driven plate 324 (of the drive transmission mechanism 300) described later attached to the support bracket 246, and transmits the driving force of the motor 400C controlled by the control unit 260 to the drive transmission mechanism 300 as a rotational force in a plane in which the normal direction substantially coincides with the front-rear direction. The drive transmission mechanism 300 is attached to the body 410C of the motor 400C and transmits the driving force of the motor 400 controlled by the control unit 260 to the work lever operating section 250L as a rotational force in a plane in which the normal direction substantially coincides with the width direction.

[0034] The support bracket 246 on the side of the support portion 240R supports the work lever operating portion 250R via a drive transmission mechanism 300D, which is substantially the same as the drive transmission mechanism 300, and a drive transmission mechanism 300E, which is substantially the same as the drive transmission mechanism 300. The portion of the drive transmission mechanism 300D corresponding to the driven plate 324 is attached to the support bracket 246 and transmits the driving force of the motor 400D, controlled by the control unit 260, to the drive transmission mechanism 300E as a rotational force in a plane in which the normal direction substantially coincides with the front-rear direction. The drive transmission mechanism 300E is attached to the main body 410D of the motor 400D and transmits the driving force of the motor 400E, controlled by the control unit 260, to the work lever operating portion 250R as a rotational force in a plane in which the normal direction substantially coincides with the width direction.

[0035] The rear ends of the work lever operating sections 250L and 250R are provided with gripping sections 251L and 251R that grip the work levers 120L and 120R. The work lever operating sections 250L and 250R are driven by motors 400C and 400D to move to the left and right, and by motors 400 and 400E to move forward and backward, thereby tilting the work levers 120L and 120R, which are gripped by the gripping sections 251L and 251R, in the forward, backward, left, and right directions to operate them.

[0036] As shown in Figures 8 to 10, the drive transmission mechanism 300 is attached to the main body 410 of the motor 400 and includes a drive mechanism 310, a driven mechanism 320, a return spring 330, a bracket 340, and a clamping mechanism 350.

[0037] A servo horn 440 is screwed to the rotating shaft 420 of the motor 400 by a screw 430. The return spring 330 is a coil spring and has a coil portion 331 made of steel wire or the like wound in a coil shape, and arm portions 332 and 333 which are made from the ends of the steel wire or the like and extend from the coil portion 331.

[0038] The drive mechanism 310 includes an annular core 311, C-shaped positioning members 312 and 313, and a plate-shaped drive plate 314, the drive plate 314 being provided with a shaft member 315. The coil portion 331 of the return spring 330 is attached to the core 311 and is sandwiched between the positioning members 312 and 313, positioning the arm portions 332 and 333 along the C-shape. With the core 311, positioning members 312 and 313 screwed to the servo horn 440 together with the drive plate 314 by three screws 316.

[0039] More specifically, the core 311 has a circular opening 311a, and with the return spring 330 assembled to the core 311, the coil portion 331 is located at the opening 311a, the arm portion 332 is located on the left side (upper side in Figure 9) of the core 311, and the arm portion 333 is located on the right side (lower side in Figure 9) of the core 311. Furthermore, the arm portion 332 is positioned by contacting the contact surface 312a formed on the lower side (lower left side in Figure 9) of the C-shaped cutout of the positioning member 312, and the arm portion 333 is positioned by contacting the contact surface 313a formed on the upper side (upper right side in Figure 9) of the C-shaped cutout of the positioning member 313.

[0040] As shown in Figure 11, the drive plate 314 has an opening 314a and a round hole 314b, and the shaft member 315 has a head 315a, a cylindrical shaft portion 315b, and a cylindrical insertion portion 315c that is smaller in diameter than the shaft portion 315b. The shaft member 315 is attached to the drive plate 314 by inserting the insertion portion 315c into the round hole 314b so that it passes through the round hole 314b.

[0041] The driven mechanism 320 includes a ball bearing 321, a plate-shaped rotating plate 322, a plate-shaped retaining plate 323 that is thinner than the rotating plate 322, and a plate-shaped driven plate 324 that is thinner than the rotating plate 322, with a shaft member 325 provided on the driven plate 324. The rotating plate 322 has a circular opening 322a, and the driven plate 324 is fixed so as to protrude into the opening 322a. The ball bearing 321 is provided on the outer circumference of the core 311 and on the inner circumference of the opening 322a. As shown in Figure 12, the inner diameter portion 321a is held in place by positioning members 312 and 313, and the outer diameter portion 321b is held in place by the driven plate 324 (the portion that protrudes into the opening 322a) and the retaining plate 323, thereby allowing the rotating plate 322 to rotate freely relative to the drive mechanism 310.

[0042] As shown in Figure 13, the driven plate 324 has an arc-shaped elongated hole 324a and a round hole 324b, and the shaft member 325 has a head 325a, a cylindrical shaft portion 325b, and a cylindrical insertion portion 325c that is smaller in diameter than the shaft portion 325b. The shaft member 325 is attached to the driven plate 324 by inserting the insertion portion 325c into the round hole 324b.

[0043] As shown in Figure 14, the shaft portion 315b of shaft member 315 and the shaft portion 325b of shaft member 325 are substantially parallel to the rotating shaft 420 of motor 400, and the insertion portion 315c that protrudes through the round hole 314b of drive plate 314 enters the elongated hole 324a of driven plate 324, thereby restricting the relative rotation range of driven plate 324 with respect to drive plate 314.

[0044] The bracket 340 is made by bending a metal plate and has a contact portion 340a and an upright portion 340b that rises from the contact portion 340a. The contact portion 340a has two screw holes 340c and is attached to the main body 410 of the motor 400 in contact with it by screws (not shown) that pass through the screw holes 340c. The upright portion 340b has a recess 340d and a groove 340e, through which the arm portion 332 of the return spring 330 is inserted, and through which the arm portion 333 of the return spring 330 is inserted.

[0045] In Figure 14, the drive mechanism 310 and the driven mechanism 320 are in a neutral position around the rotation axis 420 of the motor 400, and both can rotate from this neutral position in the forward direction (clockwise in Figure 14) and the reverse direction (counterclockwise in Figure 14). When the rotation axis 420 rotates and the drive mechanism 310 rotates in the forward direction, the arm portion 333 is pressed against the contact surface 313a of the positioning member 313, causing the return spring 330 to rotate in the same direction, and the arm portion 332 is restricted from rotating by the recess 340d of the bracket 340 (pressed against the bottom of the recess 340d), causing the return spring 330 to elastically deform. When the rotation axis 420 stops in this state, the elastic force of the return spring 330 causes the arm portion 333 to push back against the positioning member 313 (contact surface 313a), and the drive mechanism 310 returns to the neutral position. Furthermore, when the rotating shaft 420 rotates and the drive mechanism 310 rotates in the opposite direction, the arm portion 332 is pressed against the contact surface 312a of the positioning member 312, causing the return spring 330 to rotate in the same direction. The arm portion 333 is restricted from rotating by the groove portion 340e of the bracket 340 (pressed against the end of the groove portion 340e), causing the return spring 330 to elastically deform. When the rotating shaft 420 stops in this state, the elastic force of the return spring 330 causes the arm portion 332 to push back against the positioning member 312 (contact surface 312a), and the drive mechanism 310 returns to its neutral position.

[0046] The clamping mechanism 350 includes a frame 351, a plate-shaped circular plate 352, a plate-shaped clamping plate 353, a plate-shaped clamping plate 354, a spiral spring 355 as an elastic body, a shaft member 356, and a circlip 357.

[0047] The frame 351 is made by bending a metal plate and has opposing parts 351a and 351b that face each other, and a connecting part 351c that connects them. The opposing part 351a is provided with a circular opening 351d, and the opposing part 351b is provided with two circular holes 351e.

[0048] The circular plate 352 is provided with two circular holes 352a. The clamping plate 353 has a circular portion 353a and a clamping portion 353b protruding from the circular portion 353a, and the circular portion 353a is provided with two circular holes 353c. The clamping plate 354 has a curved portion 354a that curves in an arc shape, a clamping portion 354b protruding from the curved portion 354a, and an engaged portion 354c formed to stand upright relative to the curved portion 354a.

[0049] As shown in Figure 15, the spiral spring 355 is formed in a spiral shape so that the elastic plate does not come into contact with it. One end of the elastic plate on the center side of the spiral is fixed to the shaft member 356, and the other end of the elastic plate on the outside of the spiral is bent to form an engaging portion 355a. A clamping plate 354 is positioned on the spiral spring 355 such that its engaging portion 355a engages with the engaged portion 354c, and a clamping plate 353 is positioned in the same plane as the clamping plate 354 such that its circular portion 353a fits inside the curved portion 354a. Furthermore, a circular plate 352 is positioned so as to contact the clamping plates 353 and 354 from the opposite side of the spiral spring 355. The circular plate 352 and the clamping plates 353 are fixed to the shaft member 356 (and the spiral spring 355 fixed to the shaft member 356) by screws (not shown) that pass through circular holes 352a and 353c. The clamping portions 353b of the clamping plate 353 and 354b of the clamping plate 354 are biased toward each other by the elastic force of the spiral spring 355.

[0050] A groove 356b is formed in the head 356a of the shaft member 356. The head 356a is inserted through the opening 351d of the frame 351, and the circular plate 352, clamping plate 353, clamping plate 354, and spiral spring 355 are positioned in the opposing space between the opposing parts 351a and 351b of the frame 351. A circlip 357 is then fitted into the groove 356b to prevent it from coming loose, thereby assembling the clamping mechanism 350. As shown in Figure 16, the clamping mechanism 350 is attached to the rotating plate 322 of the driven mechanism 320 by a screw (not shown) that passes through the round hole 351e of the frame 351, with the clamping parts 353b and 354b contacting and clamping the shaft part 315b provided on the drive plate 314 and the shaft part 325b provided on the driven plate 324.

[0051] The work lever operating sections 250L and 250R are provided with arm members 252L and 252R that convert the direction of motion of the output of the drive transmission mechanisms 300 and 300E. Arm member 252L is screwed to the driven plate 324 of the drive transmission mechanism 300 by a screw (not shown) and moves in the forward and backward directions in accordance with the rotation of the motor 400. Arm member 252R is screwed to the part of the drive transmission mechanism 300E corresponding to its driven plate 324 and moves in the forward and backward directions in accordance with the rotation of the motor 400E.

[0052] To elaborate on the driving method in the drive transmission mechanism 300, when the rotating shaft 420 of the motor 400 rotates and the drive mechanism 310 (drive plate 314) is driven, under normal conditions when no constant strong external force is acting on the driven mechanism 320 (driven plate 324), the shaft portion 315b provided on the drive plate 314 and the shaft portion 325b provided on the driven plate 324 are connected to the clamping portion 353b of the clamping plate 353 and the clamping plate 354 While being held by the clamping portion 354b, the shaft portion 325b moves in accordance with the shaft portion 315b, causing the driven mechanism 320 (driven plate 324) to rotate (the shaft portion 325b, which is held by the clamping portions 353b and 354b, rotates together with the clamping portions 353b and 354b as the shaft portion 315b rotates and the clamping portions 353b and 354b that hold it rotate), and consequently the arm member 252L moves in the front-rear direction.

[0053] On the other hand, in the abnormal situation where a certain strong external force is acting on the driven mechanism 320 (driven plate 324), as shown in Figure 17, the shaft member 315 (shaft portion 315b) rotates by pushing the clamping portion 354b due to the driving force of the motor 400. However, the shaft member 325 (shaft portion 325b), which is integrated with the driven mechanism 320 (driven plate 324) under the action of the external force, remains in place against the biasing force of the spiral spring 355 from the clamping portion 353b. As a result, the shaft members 315 (shaft portion 315b) and 325 (shaft portion 325b) separate, and the clamping of the shaft portions 315b and 325b by the clamping portions 353b and 354b is released.

[0054] For example, if the movable range of the work lever 120L is ±45 degrees and the rotation range of the motor 400's rotating shaft 420 is ±60 degrees, then if the rotating shaft 420 continues to rotate even after the work lever 120L has reached its movable limit of ±45 degrees, without an overload prevention mechanism, the current flowing through the motor 400 will increase sharply from i[A] at the ±45-degree mark, as shown in Figure 18(a).

[0055] However, since the drive transmission mechanism 300 is equipped with an overload prevention mechanism consisting of a drive mechanism 310, a driven mechanism 320, and a clamping mechanism 350, even when the working lever 120L reaches its movable limit of ±45 degrees, there is still room for the shaft member 315 (shaft portion 315b) to push in and rotate the clamping portion 354b, and the current flowing through the motor 400 gradually increases from i[A] at ±45 degrees, as shown in Figure 18(b), thus protecting the motor.

[0056] The drive transmission mechanism 300 according to this embodiment includes a drive plate 314 fixed to the rotating shaft 420 of the motor 400 and provided with a shaft portion 315b substantially parallel to the rotating shaft 420, a driven plate 324 rotatable in the rotational direction of the rotating shaft 420 and connected to the work lever 120L via a work lever operating part 250L and provided with a shaft portion 325b substantially parallel to the rotating shaft 420, a clamping portion 353b movable along the rotational direction of the rotating shaft 420 and capable of contacting the shaft portions 315b and 325b, a clamping portion 354b movable along the rotational direction of the rotating shaft 420 and capable of contacting the shaft portions 315b and 325b from the opposite side of the clamping portion 353b, and the clamping portion 353b and The device includes a spiral spring 355, which acts as an elastic body that biases the clamping portion 354b toward the shaft portion 315b and the shaft portion 325b, respectively. When the rotating shaft 420 rotates and the driving plate 314 is driven, if no constant external force is acting on the driven plate 324, the shaft portion 315b and the shaft portion 325b are clamped by the clamping portion 353b and the clamping portion 354b, and the shaft portion 325b moves in accordance with the shaft portion 315b, causing the driven plate 324 to rotate. When a constant external force is acting on the driven plate 324, the shaft portion 315b and the shaft portion 325b separate against the biasing force of the spiral spring 355, and the clamping of the shaft portion 315b and the shaft portion 325b by the clamping portion 353b and the clamping portion 354b is released.

[0057] With this drive transmission mechanism 300, when the rotating shaft 420 of the motor 400 rotates and the drive plate 314 is driven, if a certain external force is acting on the driven plate 324, the shaft portions 315b and 325b separate against the biasing force of the spiral spring 355, and the clamping of the shaft portions 315b and 325b by the clamping portions 353b and 354b is released. As a result, the external force acting on the driven plate 324 is not directly transmitted to the drive plate 314, and overload of the motor 400 can be prevented.

[0058] On the other hand, if a constant external force is no longer acting on the driven plate 324, the shafts 315b and 325b return to a state where they are clamped by the clamping parts 353b and 354b, and the shaft 325b follows the shaft 315b, causing the driven plate 324 to rotate, thus eliminating the need for correcting misalignment.

[0059] In the drive transmission mechanism 300, the drive plate 314 and the driven plate 324 are plate-shaped and stacked in the thickness direction, so they can be compactly housed in the direction of the rotation axis 420 of the motor 400, and the clamping parts 353b and 354b are plate-shaped, so they can be compactly housed in the same direction.

[0060] Furthermore, since the shaft portions 315b and 325b are cylindrical, and the clamping portions 353b and 354b abut against their cylindrical surfaces, the contact state can be stably maintained whether the shaft portion 325b moves with the shaft portion 315b or moves away from the shaft portion 315b without being moved.

[0061] Furthermore, since a spiral spring 355 is used as the elastic body, the clamping portions 353b and 354b can be easily biased toward the shaft portions 325b and 315b.

[0062] The above describes examples of embodiments for carrying out the present invention, but the embodiments of the present invention are not limited to those described above, and may be modified as appropriate without departing from the spirit of the invention.

[0063] For example, in the above embodiment, the drive transmission mechanism 300 was used for remote control of construction machinery, but the drive transmission mechanism according to the present invention may be used for automatic control, for controlling ships, or for other purposes.

[0064] Furthermore, even if a material other than the spiral spring 355 is used as the elastic body, other materials other than the mounting brackets 243, 244, support brackets 245, 246, and ball joint 223 may be used for position adjustment, tilt adjustment, and angle adjustment, and the shapes of the shafts 315b and 325b, clamping parts 353b and 354b, support parts 240L and 240R, bracket 340, etc. may be arbitrary. [Explanation of Symbols]

[0065] 100 Hydraulic Excavator (Construction Machinery) 110L Driving lever (operating lever) 110R Driving Lever (Operating Lever) 120L Operating lever (object to be driven, operating lever) 120R Operation Lever (Operating Lever) 400 motor 420 Rotating shaft 314 Drive plate (drive unit) 315b Shaft (First shaft) 324 Driven plate (driven part) 325b Shaft section (second shaft section) 353b Clamping part (second clamping part) 354b Clamping part (first clamping part) 355 Spiral spring (elastic body)

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