Lifting assist device

Abstract

To reduce the occurrence of a hunting phenomenon in which stopping and restarting are repeated in a lifting assist device.SOLUTION: The lifting assist device includes a main body that engages with the lifting rail, an advancing / retracting mechanism that raises and lowers the main body, a control device that controls the advancing / retracting mechanism, an attachment portion that connects a lanyard of a fall arrest device, and an elastic member that connects the attachment portion to the main body. The elastic member can be in a first state with little stretch or contraction, a second state with more stretch or contraction, and a third state with even more stretch or contraction. The control device puts the advancing / retracting mechanism in a drivable state when the elastic member changes from the first state to the second state, drives the advancing / retracting mechanism to be advanced / retracted when the elastic member is in the drivable state and the second state, and puts the advancing / retracting mechanism in a disabled state when the elastic member reaches the third state. The disabled state is not released until the elastic member, which has reached the third state, returns to the first state and then returns to the second state.SELECTED DRAWING: Figure 9

Description

[Technical Field]

[0001] The present disclosure relates to a lift assist device. [Background technology]

[0002] Conventionally, workers performing work on steel towers and the like have sometimes used a climbing assist device to reduce fatigue associated with ascending and descending ladders. For example, Patent Document 1 discloses a technology in which a hook of the climbing assist device, which ascends and descends along a rail fixed to the ladder, is connected to a lanyard of the worker's fall prevention device, and part of the worker's weight is supported by the climbing assist device when ascending and descending the ladder, thereby reducing the burden on the worker.

[0003] The lift assist device assists the worker in ascending or descending the ladder by ascending or descending at a position higher than the worker's hands. The lift assist device is also equipped with a spring-type load limiter that stops the device when a load greater than a predetermined value is applied to the hook (when the spring elongation exceeds a predetermined value) and resumes the lift the moment the load is released (when the spring elongation falls below a predetermined value). Because the lift assist device does not support the entire weight of the worker, the load limiter reacts to loads less than the worker's weight. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 2701199 Summary of the Invention [Problem to be solved by the invention]

[0005] In the conventional technology disclosed in Patent Document 1, for example, if the lift-assist device rises faster than the worker, the lift-assist device stops at a position a predetermined distance above the worker (a position where the spring stretches to a predetermined value) and waits for the worker. If the worker climbs the ladder in this state, the lift-assist device resumes rising the moment the distance to the worker falls below the predetermined distance, and then stops again immediately thereafter, repeating this process. In other words, with the above conventional technology, there is a risk of the lift-assist device repeatedly stopping and restarting, resulting in a hunting phenomenon.

[0006] The present disclosure makes it possible to reduce the occurrence of a hunting phenomenon in which a lift assist device repeatedly stops and restarts. [Means for solving the problem]

[0007] According to one aspect of the present disclosure, there is provided a lifting assist device that assists a worker in ascending and descending along a vertically extending lifting rail with a fall arrest device attached thereto. The lifting assist device includes a main body that slidably engages with the lifting rail. The lifting assist device also includes an advancing / retracting mechanism that moves the main body up and down by driving the main body forward and backward along the lifting rail. The lifting assist device also includes a control device that controls the advancing / retracting drive of the advancing / retracting mechanism. The lifting assist device also includes an attachment part to which a lanyard of the fall arrest device can be connected. The lifting assist device also includes an elastic member that connects the attachment part and the main body and expands and contracts within a predetermined expansion / contraction range in response to tension applied from the lanyard to the attachment part. The elastic member can be in a first state in which the amount of expansion / contraction deformation is relatively small, a second state in which the amount of expansion / contraction deformation is greater than that in the first state, and a third state in which the amount of expansion / contraction deformation is greater than that in the second state. The control device sets the advancing / retreating mechanism to a driveable state in which it can be driven to advance and retreat when the elastic member changes from the first state to the second state. The control device drives the advancing / retreating mechanism to advance and retreat when the elastic member is in the driveable state and the second state. The control device sets the advancing / retreating mechanism to a disabled state in which driving the advancing / retreating mechanism to advance and retreat is prohibited when the elastic member changes to the third state. The control device does not release the disabled state until the elastic member, which has changed to the third state, returns to the first state and returns to the second state.

[0008] According to the above aspect, the lift-assist device sets the driveable state when the worker places part of their weight on the lift-assist device and the elastic member expands and contracts to the second state, and then raises and lowers the main body to assist the worker in lifting and lowering. Furthermore, when the lift-assist device becomes too far from the worker and the elastic member expands to the third state, the lift-assist device stops lifting and sets the drive-disabled state and waits for the worker. This drive-disabled state is not released until the worker approaches the lift-assist device and returns the elastic member to the first state, and then the worker places part of their weight on the lift-assist device and expands the elastic member to the second state. This aspect reduces the occurrence of a hunting phenomenon in which the lift-assist device repeatedly stops and restarts.

[0009] According to another aspect, the lift assist device includes an advancing / retreating member provided on an elastic member and adapted to advance / retreat within a retractable region set corresponding to the expansion / contraction region as the elastic member expands and contracts, and a plurality of detection switches arranged along the advancing / retreating region. The advancing / retreating region includes a first region in which the advancing / retreating member is positioned when the elastic member changes from a first state to a second state, a second region in which the advancing / retreating member is positioned when the elastic member is in the second state, and a third region in which the advancing / retreating member is positioned when the elastic member is in the third state. The plurality of detection switches includes a first switch, which is a one-way contact detection switch, that detects the advancing / retreating member when the advancing / retreating member approaches and contacts the main body side but does not detect the advancing / retreating member when the advancing / retreating member approaches and contacts the mounting portion side in the first region. The plurality of detection switches also includes a second switch that detects the advancing / retreating member in the second region and a third switch that detects the advancing / retreating member in the third region. The control device executes a plurality of types of control, including the following: The multiple types of control include control to place the advancing / retreating mechanism in a driveable state when the first switch detects the advancing / retreating member, control to drive the advancing / retreating mechanism in a driveable state when the second switch detects the advancing / retreating member, and control to stop the advancing / retreating drive of the advancing / retreating mechanism and set the drive disabled state when the third switch detects the advancing / retreating member.

[0010] According to the above aspect, the control device for the lift assist device can be a simple one that performs control based on the detection results of a plurality of detection switches.

[0011] According to another aspect, the second switch is a non-contact switch that detects, without contact, that the retractable member is in the second region.

[0012] According to the above aspect, wear and positional displacement of the second switch due to contact with the retractable member can be reduced, and the occurrence of a problem in which the second switch does not properly detect the retractable member can be suppressed.

[0013] According to another aspect, the lift-assist device includes a transmission wheel that is attached to the main body and engages with the lift rail, rotating forward and reverse in accordance with the elevation of the main body. The lift-assist device also includes a centrifugal weight that rotates together with the transmission wheel and extends radially outward of the transmission wheel in response to centrifugal force acting as the transmission wheel rotates. The lift-assist device also includes a stopper that can move between two positions: a non-interference position where it does not interfere with the transmission wheel, and an abutment position where it abuts against an abutment portion provided on the transmission wheel to brake the rotation of the transmission wheel. The lift-assist device also includes a biasing member that biases the stopper in a direction from the non-interference position toward the abutment position. The lift-assist device also includes a locking member that engages with the stopper in the non-interference position to lock the stopper from moving to the abutment position. The centrifugal weight rotates on a trajectory that does not interfere with the locked locking member when the rotational speed of the transmission wheel is below a predetermined value, and rotates on a trajectory that hits the locked locking member and releases the locked state when the rotational speed is above a predetermined value.

[0014] In the conventional technology disclosed in Patent Document 1, the lift-assist device is equipped with a centrifugal brake that prevents a sudden descent when a worker loses their footing, etc. This centrifugal brake has a keeper bearing that rotates in accordance with the descent of the lift-assist device, and prevents a sudden descent by pressing a brake shoe that slides radially outward against a brake housing in response to the centrifugal force acting as the bearing rotates. However, the above conventional technology has a problem in that the function of the centrifugal brake decreases when the descent speed of the lift-assist device is slow.

[0015] In contrast, according to the above aspect, the centrifugal weight that protrudes radially outward due to the centrifugal force of the transmission wheel as the main body rises and falls is used to unlock the stopper that stops the rotation of the transmission wheel. Because the stopper is biased by the biasing member, it brakes the rotation of the transmission wheel regardless of the descent speed of the lift-assist device. This allows the above aspect to more reliably brake the descent of the lift-assist device.

[0016] According to another aspect, the contact portion is provided on the transmission wheel via a torque limiter that releases torque above a predetermined value by idling.

[0017] According to the above aspect, even when the stopper abuts on the abutment portion and the rotation of the transmission wheel is braked, if an excessive load is applied to the transmission wheel, the excess load is released by the idling of the torque limiter. As a result, in the above aspect, the impact load applied to the worker as a reaction to the impact load from the worker to the lift-assist device can be alleviated.

[0018] According to another aspect, the lift-down assist device includes a bumper extending longitudinally along the upper or lower edge of the main body. The lift-down assist device also includes a spacing member that exerts a biasing force to separate the bumper and the main body. The lift-down assist device also includes a first link and a second link that are arranged to intersect with each other and connect the bumper to the main body. The lift-down assist device also includes a connecting pin that rotatably connects the first link and the second link at their intersecting portion. The joint of the first link on the main body side and the joint of the second link on the bumper side are each pin joints with one rotational degree of freedom. The joint of the second link on the main body side and the joint of the first link on the bumper side are each sliders with one linear degree of freedom extending along the longitudinal direction of the bumper. The control device controls the advancing / retracting mechanism to stop its advancing / retracting drive when an external force acts to bring the bumper and the main body closer together against the biasing force of the biasing member.

[0019] In the conventional technology disclosed in Patent Document 1, the lifting assist device moves up and down following the worker's movement, positioned higher than the worker's hands. For example, if a worker stops walking while descending the ladder, the worker's hand may become pinched between the lifting assist device, which moves down following the worker, and the rung the worker is holding. To address this issue, the conventional technology provides a bumper on the bottom of the lifting assist device, which activates a pinch prevention mechanism when the bumper is pushed in.

[0020] In the conventional technology, the bumper is attached to the main body of the lift-assist device via a pair of left and right linear shafts. The pushing of the bumper is detected by a microswitch detecting the pushing of the right linear shaft. Therefore, the conventional technology has a problem in that the detection accuracy of the pushing of the bumper decreases when, for example, the pushing of the bumper is biased toward the left side.

[0021] In contrast, according to the above aspect, two opposing reciprocating slider lever mechanisms are interposed between the bumper and the main body. These reciprocating slider lever mechanisms share the first and second links that intersect with each other, so that an external force that tries to move the bumper closer to the main body moves the entire bumper closer to the main body, regardless of which part of the bumper is subjected to the external force. This makes it possible to avoid a decrease in the accuracy of detecting whether the bumper is being pushed in.

[0022] According to another aspect, the lifting assist device includes a guide member fixed to the bumper and extending linearly toward the main body, and an engagement block fixed to the main body and engaging with the guide member so as to be slidable relative to the guide member.

[0023] According to the above aspect, the guide member functions as a linear axis to suppress wobbling of the bumper relative to the main body. Also, by configuring the guide member to extend from the bumper toward the main body, it is possible to prevent the guide member from protruding from the bumper when the bumper and the main body are brought closer together by an external force. [Effects of the Invention]

[0024] According to the present disclosure, it is possible to reduce the occurrence of a hunting phenomenon in which a lift assist device repeatedly stops and restarts. [Brief explanation of the drawings]

[0025] [Figure 1]1 is an explanatory diagram illustrating a state in which a lift assist device 10 according to an embodiment of the present disclosure is used. [Figure 2] 2 is a front view showing the lift assist device 10 of FIG. 1 with a cover 10A and a battery 10B removed. [Figure 3] FIG. 3 is a left side view similar to FIG. 2. [Figure 4] FIG. 3 is a bottom view similar to FIG. 2. [Figure 5] 3 is an enlarged view of part V in FIG. 2, with the main body 11 and the advancing / retracting mechanism 12 omitted. [Figure 6] 6 is an enlarged view of part VI in FIG. 3, with the advancing / retreating mechanism 12 and part of the main body 11 omitted. [Figure 7] FIG. 7 is a cross-sectional view taken along line VII-VII in FIG. 5. [Figure 8] FIG. 8 is an enlarged view of part VIII in FIG. 2. [Figure 9] 9 is an enlarged view similar to FIG. 8, showing the state in which the elastic member 21 stretched to the third state is contracting. [Figure 10] FIG. 3 is an enlarged view of the X portion of FIG. 2. [Figure 11] FIG. 3 is an enlarged view of a portion XI in FIG. 2. DETAILED DESCRIPTION OF THE INVENTION

[0026] A lift-down assist device 10 according to one embodiment of the present disclosure will be described below with reference to Figures 1 to 11. In the following description, the directions of "front," "back," "left," "right," "up," and "down" are defined as directions as seen from a worker 90 when the lift-down assist device 10 shown in Figure 1 is in use.

[0027] As shown in FIG. 1, the lifting assistance device 10 assists a worker 90 wearing a fall arrest device 90A to ascend and descend along an ascending and descending path 91A (see the imaginary line in FIG. 1) set up on a steel tower 91. Here, the steel tower 91 is provided with a lifting rail 91B that extends vertically along the ascending and descending path 91A. A lanyard 90B provided on the fall arrest device 90A is also attached to the lifting assistance device 10. In this state, when the worker 90 ascends or descends the ascending and descending path 91A, the lifting assistance device 10 assists the worker 90 in ascending and descending by lifting the worker 90 along the lifting rail 91B while pulling the worker 90 up via the lanyard 90B of the fall arrest device 90A.

[0028] As shown in Fig. 2, the lifting rail 91B is a long, plate-like rail with a row of cogs along one edge (the left side in Fig. 2) and can function as a mechanical element of a "rack." Such a rail is also commonly called a "toothed rail."

[0029] 2 and 3, the lift assist device 10 includes two batteries 10B, a main body 11, a forward / backward movement mechanism 12, a control device 13, a connection mechanism 20, a transmission wheel 30, and two buffer mechanisms 40 and 50. Of these components, all components except for the buffer mechanisms 40 and 50 are covered from the rear by a cover 10A that is detachably attached to the main body 11.

[0030] Each battery 10B is a supply source of electric energy consumed by each component (mainly the advancing / retreating mechanism 12 and the control device 13) of the lift assist device 10. These batteries 10B are attached to the main body 11 in a detachable and replaceable manner.

[0031] 4, the main body 11 includes two sandwiching members 11A and 11B arranged side by side in the left-right direction. These sandwiching members 11A and 11B sandwich the left and right edges of the lifting rail 91B from the front-rear direction, respectively. This allows the main body 11 to slidably engage with the lifting rail 91B.

[0032] In this embodiment, the main body 11 is covered from below with an operation panel 14 provided with a plurality of operation switches 14A. These operation switches 14A are operated, for example, to turn on and off the power supply from the battery 10B or to switch the rotation direction of a motor 12B (described below, see FIG. 2) of the advance / retract mechanism 12.

[0033] 3, the forward / backward mechanism 12 is configured to rotate the pinwheel 12A forward and backward by a motor 12B equipped with a gearbox 12C. In this embodiment, the rotation direction of the motor 12B can be changed by operating an operation switch 14A on the operation panel 14.

[0034] The pinwheel 12A engages with the lifting rail 91B (specifically, meshes with the cogs of the lifting rail 91B) while attached to the main body 11, thereby converting its forward and reverse rotation into forward and backward movement along the lifting rail 91B. This causes the forward and backward movement mechanism 12 to lift and lower the main body 11 (and ultimately the entire lifting assist device 10).

[0035] The control device 13 controls the forward / backward movement of the forward / backward mechanism 12 based on inputs from various switches provided on the lift-assist device 10. Here, the "various switches" include a plurality of operation switches 14A provided on the operation panel 14. The "various switches" also include a plurality of detection switches (specifically, a first switch 22A, a second switch 22B, and a third switch 22C shown in FIG. 8) provided on the connection mechanism 20. The "various switches" also include a sensor 13A that non-contactly detects a stopper 32 (described below, see FIG. 5) that brakes the rotation of the transmission wheel 30. The "various switches" also include sensors 43A and 53A (described below, see FIGS. 10 and 11) provided on the buffer mechanisms 40 and 50, respectively. Details of the control by the control device 13 will be described later, and a detailed description thereof will be omitted here.

[0036] The connection mechanism 20 is configured to connect the lanyard 90B (see FIG. 1) of the fall arrest device 90A to the main body 11. As shown in FIG. 2, the connection mechanism 20 includes a casing 20A configured as part of the main body 11. In this embodiment, the casing 20A is a long hollow cylindrical pipe arranged to extend in the vertical direction. A slit 20B extending downward from the upper end of the hollow cylindrical pipe is formed on the side surface on the rear side of the hollow cylindrical pipe (the front side of the paper in FIG. 2).

[0037] As shown in Figures 8 and 9, a long metal rod 23A is housed inside the casing 20A and extends vertically. A metal fitting 23B called a "bow shackle" is attached to the lower end of the metal rod 23A (the lower end in Figure 8). As shown in Figure 1, this fitting 23B protrudes downward from the cover 10A of the climbing assistance device 10. A lanyard 90B of a fall arrest device 90A can be connected to this fitting. The structure for connecting a lanyard to a "bow shackle" is well known, and therefore a detailed description thereof will be omitted here.

[0038] Hereinafter, the combined configuration of metal rod 23A and metal fitting 23B will also be referred to as "mounting portion 23." That is, connection mechanism 20 has mounting portion 23 to which lanyard 90B (see FIG. 1) of fall arrest device 90A can be connected.

[0039] Elastic member 21, which is a compression helical spring extending in the vertical direction, is interposed between casing 20A and metal rod 23A of mounting portion 23. Elastic member 21 connects the lower end of casing 20A, which is part of main body 11, to the upper end of metal rod 23A in mounting portion 23. As a result, elastic member 21 is configured to expand and contract within expansion area 21A set in casing 20A in response to the downward tension applied to lanyard 90B (see FIG. 1) of fall arrest device 90A.

[0040] In the following, the expansion / contraction states of the elastic member 21 will be described in three states: a "first state," a "second state," and a "third state." The "first state" is a state in which the amount of contraction deformation of the elastic member 21 is small enough to be ignored by the control device 13. Specifically, the "first state" is the expansion / contraction state of the elastic member 21 when the lanyard 90B is not connected to the attachment portion 23 or when the weight of the worker 90 is not being applied to the lanyard 90B connected to the attachment portion 23. The "second state" is the expansion / contraction state of the elastic member 21 when, for example, the lift-assist device 10 is assisting the worker 90 in ascending or descending. The amount of contraction deformation of the elastic member 21 in the second state is greater than the amount of contraction deformation of the elastic member 21 in the first state. The "third state" is the state of expansion and contraction of the elastic member 21 when, for example, the worker 90 loses his / her footing and a load greater than the load that can be assisted by the lift-assist device 10 is applied to the lanyard 90B. The amount of deformation due to contraction of the elastic member 21 in the third state is greater than the amount of deformation due to contraction of the elastic member 21 in the second state.

[0041] A plate-shaped advancing / retreating member 22 is slidably engaged in the slit 20B of the casing 20A. The advancing / retreating member 22 is provided so as to pass through the slit 20B from the outer rear surface of the elastic member 21 and protrude rearward (toward the front side of the paper in FIG. 8 ) from the rearward outer surface. This allows the advancing / retreating member 22 to advance / retreat within an advancing / retreating region 24 that is set along the slit 20B in correspondence with the stretchable region 21A, as the elastic member 21 stretches and contracts.

[0042] The advancing and retreating region 24 includes a first region 24A, a second region 24B, and a third region 24C (see FIGS. 8 and 9), which will be described below. The first region 24A is the region where the lower end of the advancing and retreating member 22 is located when the elastic member 21 changes from the first state to the second state. The second region 24B is the region where the lower end of the advancing and retreating member 22 is located when the elastic member 21 is in the second state. The third region 24C is the region where the lower end of the advancing and retreating member 22 is located when the elastic member 21 is in the third state.

[0043] The connection mechanism 20 is provided with a switch row in which a plurality of detection switches are arranged along the advance / retract area 24. Each of these detection switches detects the advance / retract member 22 and outputs the detection result to the control device 13. The control device 13 controls the advance / retract drive of the advance / retract mechanism 12 based on the output from each detection switch in the switch row. In this embodiment, the switch row is arranged, from top to bottom, with one first switch 22A, multiple (two in FIG. 8) second switches 22B, and one third switch 22C.

[0044] The first switch 22A is a limit switch with its actuator (the part that receives force from the detected object) positioned in the first region 24A. The actuator of the first switch 22A has a hinge biased to maximize the opening angle. It receives force in the direction that opens the hinge, but bends the hinge when force is applied in the opposite direction. The first switch 22A is positioned so that its "hinge opening direction" is from top to bottom. Therefore, the first switch 22A detects the advancing / retreating member 22 when it approaches and contacts the first region 24A from the side connected to the main body 11 (the upper side in FIG. 8 ). However, it does not detect the advancing / retreating member 22 when it approaches and contacts the first region 24A from the side connected to the mounting portion 23 (the lower side in FIG. 9 ). In other words, the first switch 22A corresponds to a "one-way contact detection switch" in this disclosure.

[0045] The second switch 22B is a non-contact switch arranged to detect the advancing / retreating member 22 within a predetermined range within the second region 24B without contact. The multiple second switches 22B are arranged so that their detection ranges are shifted in the vertical direction. The multiple second switches 22B work together, and if any one of these second switches 22B detects the advancing / retreating member 22, it outputs a detection result to the control device 13 indicating that "the advancing / retreating member 22 has been detected in the second region 24B."

[0046] The third switch 22C is a limit switch whose actuator is disposed at the boundary between the second region 24B and the third region 24C.

[0047] The control of the control device 13 in response to the outputs from the above-described detection switches will now be described. When the first switch 22A detects the advancing / retreating member 22, the control device 13 controls the advancing / retreating mechanism 12 to be in a driveable state, allowing it to be driven forward and backward. Here, the first switch 22A outputs a detection result indicating that "the advancing / retreating member 22 has been detected" only when the lower end of the advancing / retreating member 22 moves from the first region 24A toward the second region 24B, i.e., when the elastic member 21 changes from the first state to the second state. Therefore, the control of the control device 13 can be rephrased as "control to set the advancing / retreating mechanism 12 in a driveable state when the elastic member 21 changes from the first state to the second state." Note that "when the elastic member 21 changes from the first state to the second state" specifically refers to, for example, "when the worker 90 begins to apply his / her weight to the lanyard 90B to receive assistance from the lift-assist device 10."

[0048] Furthermore, when the second switch 22B detects the advancing / retreating member 22 in the drivable state (that is, when the drivable state and the second state are in), the control device 13 controls the advancing / retreating mechanism 12 to be driven forward and backward.

[0049] Furthermore, when the third switch 22C detects the advancing / retreating member 22 (i.e., when the elastic member 21 has entered the third state), the control device 13 stops the advancing / retreating drive of the advancing / retreating mechanism 12 and controls the advancing / retreating mechanism 12 to enter a disabled state in which advancing / retreating drive is prohibited. This disabled state is released by control that switches the advancing / retreating mechanism 12 to a drivable state, but as described above, this control is executed only when the elastic member 21 changes from the first state to the second state. In other words, the control device 13 does not release the disabled state of the advancing / retreating mechanism 12 until the elastic member 21, which has entered the third state, returns to the first state and enters the second state again.

[0050] 2 and 6, the transmission wheel 30 includes a pinwheel 30B and is rotatably attached to the main body 11. The pinwheel 30B engages with the lifting rail 91B (specifically, meshes with the cogs of the lifting rail 91B), thereby converting the lifting and lowering of the main body 11 along the lifting rail 91B into forward and reverse rotation. As a result, the transmission wheel 30 rotates forward and reverse in accordance with the lifting and lowering of the main body 11.

[0051] 5, the transmission wheel 30 is provided with an abutment portion 30A that brakes the rotation of the transmission wheel 30 when a stopper 32 provided on the main body 11 abuts against the abutment portion 30A. The abutment portion 30A is provided on the transmission wheel 30 via a torque limiter 30C that releases torque above a predetermined level by causing it to spin freely. The magnitude of the torque at which the torque limiter 30C begins to spin freely is set to be greater than the magnitude of the torque that can be applied to the transmission wheel 30 by the lifting and lowering of the lift-assist device 10 by the advancing and retracting mechanism 12.

[0052] In this embodiment, the abutment portion 30A is a single cog provided on the outer circumferential surface of the transmission wheel 30, and the stopper 32 is a pawl configured to be able to engage with the cog of the abutment portion 30A. The stopper 32 and the abutment portion 30A form a ratchet mechanism that applies a brake to only one of the forward and reverse rotations of the transmission wheel 30. In this embodiment, the ratchet mechanism applies a brake only to rotation in the direction corresponding to the descent of the main body 11 (counterclockwise rotation in FIG. 5).

[0053] The stopper 32 is rotatably supported by the main body 11, and is connected to the main body 11 at a position away from the support position via a biasing member 32A (a tension spring in this embodiment). This allows the stopper 32 to move between two positions: a non-interference position where it does not interfere with the transmission wheel 30 (see the stopper 32 shown by the solid line in FIG. 5), and an abutment position where it abuts against and engages with the abutment portion 30A of the transmission wheel 30 (see the stopper 32 shown by the imaginary line in FIG. 5). The biasing member 32A biases the stopper 32 in a direction from the non-interference position toward the abutment position.

[0054] In this embodiment, the stopper 32 is provided with a lever portion 32B as a handle, which makes it possible to forcibly move the stopper 32 from the abutting position to the non-interference position. The lever portion 32B is used, for example, when manually releasing the engagement between the stopper 32 and the abutting portion 30A.

[0055] A locking member 33 is attached to the stopper 32 to lock the stopper 32 from moving from the non-interference position to the abutment position. As shown in Fig. 7, the locking member 33 is attached to the main body 11 via a base 33B, and has a protrusion 33C protruding rearward from the base 33B. The protrusion 33C locks the movement of the stopper 32 by engaging with the stopper 32 in the non-interference position from the abutment position side (the right side in Fig. 5).

[0056] 7, the locking member 33 is pivotally supported on the base 33B so as to be rotatable in the vertical direction, and is connected to the main body 11 via the spring 33A at a position away from the pivotal support position. Therefore, when an external force is applied to the protruding portion 33C of the locking member 33 in the vertical direction, the locking member 33 retracts the protruding portion 33C toward the base 33B, temporarily releasing the locked state (see the imaginary line in FIG. 7).

[0057] As shown in Fig. 5, the transmission wheel 30 is provided with an arc-shaped centrifugal weight 31 that is provided to rotate together with the transmission wheel 30. One end of the centrifugal weight 31 is journaled on the transmission wheel 30, and the other end is attached to the transmission wheel 30 via a tension spring 31A. As a result, the centrifugal weight 31 is configured to protrude radially outward from the transmission wheel 30 (see the imaginary line in Fig. 5) in response to the centrifugal force acting as the transmission wheel 30 rotates.

[0058] Due to the above configuration, the rotational trajectory of the centrifugal weight 31 extends radially outward from the transmission wheel 30 as the rotational speed of the transmission wheel 30 that rotates together with the centrifugal weight 31 increases. In Fig. 5, the rotational trajectory of the centrifugal weight 31 when the centrifugal weight 31 rotates slowly and the effect of its centrifugal force can be ignored is depicted as trajectory 31B. Also, the rotational trajectory of the centrifugal weight 31 when the transmission wheel 30 rotates at a rotational speed faster than that during normal lifting and lowering of the lift-assist device 10 (specifically, for example, 1.2 times or more the rotational speed) is depicted as trajectory 31C.

[0059] Here, trajectory 31B is a trajectory that does not interfere with the locked locking member 33. Furthermore, trajectory 31C is a trajectory that interferes with the locked locking member 33, causing the centrifugal weight 31 to hit the protrusion 33C of the locking member 33 from above. From this, it can be said that when the rotational speed of the transmission wheel 30 is below a predetermined value, the centrifugal weight 31 rotates on a trajectory that does not interfere with the locked locking member 33, and when the rotational speed is above the predetermined value, the centrifugal weight 31 rotates on a trajectory that hits the locked locking member 33 and releases the locked state.

[0060] When the locked state of the locking member 33 is released by the centrifugal weight 31, the stopper 32 moves from the non-interference position to the abutment position by the biasing force of the biasing member 32A, and engages with the abutment portion 30A of the transmission wheel 30, thereby braking the rotation of the transmission wheel 30. This movement of the stopper 32 is detected by a non-contact sensor 13A provided near the stopper 32 (on the left side in FIG. 5). When the sensor 13A detects the movement of the stopper 32, the control device 13 (see FIG. 2) controls the advancing and retracting drive of the advancing and retracting mechanism 12 to stop.

[0061] 10, the buffer mechanism 40 has a bumper 40A that projects above the main body 11, and is configured to receive a collision from above with an obstacle or the like by this bumper 40A. The bumper 40A is disposed so as to extend longitudinally along the upper edge of the main body 11.

[0062] The buffer mechanism 40 includes a first link 41 and a second link 42, each of which connects the bumper 40A to the main body 11. These are arranged to intersect with each other and are rotatably connected at the midpoint of the intersection by a connecting pin 40B, thereby forming a link mechanism.

[0063] In the link mechanism of the shock absorber mechanism 40, the joint of the first link 41 on the main body 11 side (lower side in FIG. 10) is a pin joint 41A with one rotational degree of freedom. The joint of the first link 41 on the bumper 40A side (upper side in FIG. 10) is a slider 41B with one linear degree of freedom that extends along the longitudinal direction of the bumper 40A (left-right direction in FIG. 10). The joint of the second link 42 on the bumper 40A side is a pin joint 42A with one rotational degree of freedom. The joint of the second link 42 on the main body 11 side is a slider 42B with one linear degree of freedom that extends along the longitudinal direction of the bumper 40A. As a result, the link mechanism of the shock absorber mechanism 40 is configured by combining two reciprocating slider lever mechanisms that share the first link 41 and the second link 42, facing each other.

[0064] A tension spring 40C is interposed between the pin joint 41A and the slider 42B, exerting a biasing force in a direction that brings them closer to each other. The link mechanism of the buffer mechanism 40 converts the movement of the tension spring 40C, which moves the slider 42B closer to the pin joint 41A, into a movement that separates the bumper 40A from the main body 11. In this way, the tension spring 40C functions as a spacing member that exerts a biasing force to separate the bumper 40A from the main body 11.

[0065] A cylindrical guide member 43 is fixed to the bumper 40A and extends linearly toward the main body 11. This guide member 43 is inserted into a cylindrical engagement block 43A fixed to the main body 11, and engages with this engagement block 43A so as to be slidable relative to it.

[0066] A sensor 43B is attached to the engagement block 43A, which detects the insertion depth of the guide member 43 and outputs the result to the control device 13 (see FIG. 2). The control device 13 determines the distance between the bumper 40A and the main body 11 based on the output of the sensor 43B, and controls the advancing and retracting mechanism 12 to stop moving forward and backward when this distance is reduced. That is, the control device 13 controls the advancing and retracting mechanism 12 to stop moving forward and backward when an external force acts that moves the bumper 40A and the main body 11 closer together against the biasing force of the tension spring 40C.

[0067] 11, the shock absorbing mechanism 50 has a bumper 50A that projects downward from the main body 11, and is configured to absorb a collision from an obstacle or the like from below by the bumper 50A. The bumper 50A is disposed so as to extend longitudinally along the lower edge of the main body 11.

[0068] Here, the buffer mechanisms 40 and 50 have the same configuration, except that they are upside down so that the buffer mechanism 40 receives a collision from above and the buffer mechanism 50 receives a collision from below. For this reason, the components of the buffer mechanism 50 are assigned reference numerals obtained by adding "10" to the reference numerals assigned to the components of the buffer mechanism 40 in Fig. 10, and detailed description thereof will be omitted.

[0069] The above-described lift-assist device 10 sets the driveable state when the worker 90 places part of their weight on the device and the elastic member 21 expands and contracts to the second state, and then raises and lowers the main body 11 to assist the worker 90 in ascending or descending. Furthermore, when the lift-assist device 10 becomes too far from the worker 90 and the elastic member 21 expands to the third state, the lift-assist device 10 stops the lift-up and sets the drive-disabled state and waits for the worker 90. This drive-disabled state is not released until the worker 90 approaches the lift-assist device 10 and returns the elastic member 21 to the first state, and then the worker 90 places part of their weight on the device and expands the elastic member 21 to the second state. This allows the lift-assist device 10 to reduce the occurrence of a hunting phenomenon in which the device repeatedly stops and restarts operation.

[0070] Furthermore, according to the lift assist device 10, the control device 13 of the lift assist device 10 can be a simple device that performs control based on the detection results of a plurality of detection switches.

[0071] Furthermore, the lift assist device 10 reduces wear and positional deviation of the second switch 22B due to contact with the advancing / retreating member 22, thereby preventing the occurrence of problems in which the second switch 22B does not properly detect the advancing / retreating member 22.

[0072] Furthermore, according to the lift-assist device 10, centrifugal weight 31, which protrudes radially outward due to the centrifugal force of transmission wheel 30 as the main body 11 moves up and down, is used to unlock stopper 32, which stops the rotation of transmission wheel 30. Because stopper 32 is biased by biasing member 32A, it applies a brake to the rotation of transmission wheel 30 regardless of the descent speed of lift-assist device 10. This allows lift-assist device 10 to more reliably apply a brake to the descent.

[0073] Furthermore, according to the lift-assist device 10, even when the stopper 32 abuts against the abutment portion 30A and the rotation of the transmission wheel 30 is braked, if an excessive load is applied to the transmission wheel 30, the torque limiter 30C will run freely to release the excess load. This allows the lift-assist device 10 to mitigate the impact load on the worker 90 as a reaction to the impact load from the worker 90 to the lift-assist device 10.

[0074] Furthermore, according to the lift-assist device 10, two reciprocating slider lever mechanisms facing each other are interposed between the bumper 40A and the main body 11, and between the bumper 50A and the main body 11. These reciprocating slider lever mechanisms share a first link and a second link that intersect with each other, so that an external force that tries to move the bumpers 40A, 50A closer to the main body 11 moves the entire bumpers 40A, 50A closer to the main body 11, regardless of which part of the bumpers 40A, 50A an external force is applied to. This allows the lift-assist device 10 to avoid a decrease in the accuracy of detecting whether the bumpers 40A, 50A are being pushed in.

[0075] Furthermore, according to the lift-assist device 10, the guide members 43, 53 function as linear axes, thereby reducing wobbling of the bumpers 40A, 50A relative to the main body 11. Furthermore, the configuration in which the guide members 43, 53 extend from the bumpers 40A, 50A toward the main body 11 prevents the guide members 43, 53 from protruding from the bumpers 40A, 50A when the bumpers 40A, 50A and the main body 11 are brought closer together by an external force.

[0076] The above-described embodiment has been used to describe the mode for carrying out the present disclosure. However, it will be apparent to those skilled in the art that various substitutions, modifications, and alterations are possible without departing from the scope of the present disclosure. In other words, the mode for carrying out the present disclosure may include all substitutions, modifications, and alterations that do not depart from the spirit and purpose of the claims appended hereto. For example, the following various modes can be implemented as modes for carrying out the present disclosure.

[0077] (1) In the present disclosure, the elastic member connecting the attachment portion and the main body portion is not limited to a compression helical spring that is compressed downward by tension applied through the attachment portion. That is, in the present disclosure, the elastic member may be, for example, a tension spring or elastomer (rubber), which stretches by tension. In this case, the "first state," "second state," and "third state" of the elastic member are set based on the "amount of expansion deformation" rather than the "amount of contraction deformation." Furthermore, in the present disclosure, a mechanism (e.g., a pulley or link mechanism) that changes the direction of force may be interposed between the attachment portion and the elastic member, allowing the elastic member to expand and contract in an appropriately set direction.

[0078] (2) In the present disclosure, a configuration in which a brake shoe provided on a centrifugal weight is pressed against a contact portion formed as a brake housing may be used as a configuration for braking the rotation of a transmission wheel.

[0079] (3) In the present disclosure, a configuration can be adopted in which a spacing member is placed between the bumper and the main body portion, and the biasing force of the spacing member is directly applied to separate the bumper and the main body portion. [Explanation of symbols]

[0080] 10 Lifting assist device 10A Cover 10B battery 11 Main body 11A Clamping member 11B Clamping member 12 Advancement / retraction mechanism 12A Pinwheel 12B motor 12C gearbox 13 Control device 13A sensor 14 Operation panel 14A operation switch 20 Connection mechanism 20A casing 20B slit 21 Elastic member 21A Stretch area 22 Moving member 22A First switch (detection switch, one-way contact detection switch) 22B Second switch (detection switch) 22C Third switch (detection switch) 23 Mounting part 23A Metal Rod 23B metal fittings 24 Advance / retreat area 24A 1st area 24B 2nd area 24C 3rd area 30 Transmission Wheel 30A contact part 30B pinwheel 30C Torque Limiter 31 Centrifugal weight 31A Extension spring 31B Locus 31C locus 32 Stopper 32A biasing member 32B Lever part 33 Locking member 33A Spring 33B pedestal 33C Protrusion 40 Buffer mechanism 40A Bumper 40B connecting pin 40C Extension spring (spacer) 41 Link 1 41A Pin Joint 41B Slider 42 Second Link 42A pin joint 42B slider 43 Guide member 43A Engagement block 43B Sensor 50 Buffer mechanism 50A Bumper 50B connecting pin 50C Extension spring (spacer) 51 First Link 51A Pin Joint 51B slider 52 Second Link 52A pin joint 52B slider 53 Guide member 53A Engagement block 53B Sensor 90 workers 90A Fall arrest equipment 90B Lanyard 91 Steel Tower 91A Elevator Path 91B Lifting rail

Claims

1. A lifting assist device that assists a worker in ascending and descending, the lifting assist device being attached to a fall arrest device worn by the worker and moving up and down along a lifting rail that extends long in the vertical direction, a main body portion that slidably engages with the lift rail; an advancing / retracting mechanism that moves the main body up and down by driving the main body up and down along the lifting rail; a control device that controls the advance / retract drive of the advance / retract mechanism; An attachment portion to which a lanyard of the fall arrest device can be connected; an elastic member that connects the attachment portion and the main body portion and expands and contracts within a predetermined expansion and contraction range in response to tension applied from the lanyard to the attachment portion; Equipped with The elastic member can be in a first state in which the amount of deformation caused by expansion and contraction is relatively small, a second state in which the amount of deformation caused by expansion and contraction is larger than that in the first state, and a third state in which the amount of deformation caused by expansion and contraction is larger than that in the second state, The control device When the elastic member changes from the first state to the second state, the advancing / retreating mechanism is brought into a drivable state in which it can be driven to advance and retreat; driving the advancing / retracting mechanism forward and backward when the actuator is in the drivable state and the second state; When the elastic member is in the third state, the advancing / retracting mechanism is put into a drive-disabled state in which advancing / retracting driving is prohibited, The non-driveable state is not released until the elastic member, which has been in the third state, returns to the first state and then enters the second state again. Lifting assistance device.

2. The lift assist device according to claim 1, an advancing / retreating member provided on the elastic member, which advances and retreats within an advancing / retreating region set corresponding to the stretching region as the elastic member expands and contracts; a plurality of detection switches arranged along the advance / retreat area; Equipped with The advance / retreat area is: a first region in which the advancing / retreating member is positioned when the elastic member changes from the first state to the second state; a second region in which the advancing / retreating member is positioned when the elastic member is in the second state; a third region in which the advancing and retreating member is positioned when the elastic member is in the third state; Including, The plurality of detection switches include: a first switch that is a one-way contact detection switch that detects the advancing / retreating member when the advancing / retreating member approaches and contacts the first region from the main body side, but does not detect the advancing / retreating member when the advancing / retreating member approaches and contacts the first region from the attachment side; a second switch for detecting the reciprocating member in the second region; a third switch for detecting the reciprocating member in the third region; Contains, The control device a control for bringing the advancing / retreating mechanism into the drivable state when the first switch detects the advancing / retreating member; a control for driving the advancing / retreating mechanism to advance / retreat when the second switch detects the advancing / retreating member in the drivable state; a control to stop the advance / retraction drive of the advance / retraction mechanism and set the drive disabled state when the third switch detects the advance / retraction member; Perform multiple types of control, including Lifting assistance device.

3. The lift assist device according to claim 2, the second switch is a non-contact switch that detects in a non-contact manner that the advancing / retreating member is in the second region. Lifting assistance device.

4. The lift assist device according to claim 1, a transmission wheel that engages with the lifting rail while attached to the main body and rotates forward and backward in accordance with the lifting and lowering of the main body; a centrifugal weight provided to rotate together with the transmission wheel and protruding radially outward from the transmission wheel in response to centrifugal force acting in conjunction with the rotation; a stopper that can move between two positions: a non-interference position that does not interfere with the transmission wheel, and an abutment position that abuts against an abutment portion provided on the transmission wheel to brake the rotation of the transmission wheel; a biasing member that biases the stopper in a direction from the non-interference position toward the abutment position; a locking member that is engaged with the stopper in the non-interference position to lock the stopper from moving to the abutting position; Equipped with When the rotational speed of the transmission wheel is equal to or lower than a predetermined value, the centrifugal weight rotates along a trajectory that does not interfere with the locking member in the locked state, and when the rotational speed is equal to or higher than the predetermined value, the centrifugal weight rotates along a trajectory that comes into contact with the locking member in the locked state and releases the locked state. Lifting assistance device.

5. The lift assist device according to claim 4, The contact portion is provided on the transmission wheel via a torque limiter that releases torque above a predetermined value by idling. Lifting assistance device.

6. The lift assist device according to any one of claims 1 to 5, a bumper extending longitudinally along an upper edge or a lower edge of the main body; a spacing member that exerts a biasing force to separate the bumper and the main body; a first link and a second link arranged to intersect with each other and connecting the bumper and the main body portion, respectively; a connecting pin that rotatably connects the first link and the second link at an intermediate intersection between the first link and the second link; Equipped with the joint of the first link on the main body side and the joint of the second link on the bumper side are each a pin joint with one rotational degree of freedom, the joint of the second link on the main body side and the joint of the first link on the bumper side are each a linear slider with one degree of freedom extending along the longitudinal direction of the bumper, the control device performs control to stop the advancing and retreating drive of the advancing and retreating mechanism when an external force acts to bring the bumper and the main body closer together against the biasing force of the spacing member. Lifting assistance device.

7. 7. The lift assist device according to claim 6, a guide member fixed to the bumper and extending linearly toward the main body; an engagement block fixed to the main body portion and slidably engaged with the guide member; Equipped with Lifting assistance device.

Images