JP2003118984A - Driving device for lifting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a driving device capable of preventing a collision of a table against a base side due to a natural drop of the table even at the time of an abnormality such as a possibility of damaging a table lifting device due to the natural drop of the table when a brake incorporated into a driving motor is carelessly released due to any trouble in a conventional way, in the table lifting device interposing an X-shaped lifting arm between the base and the table, making the lifting arm perform an extending/contracting operation in the vertical direction by a screw shaft device and the driving motor and vertically elevating/lowering the table in parallel to the base. SOLUTION: A regulating claw moved by centrifugal force at a time when rotational speed of the screw shaft 21 reaches a fixed value and engaged to a screw shaft supporting part side is provided between the screw shaft 21 and a screw shaft supporting part 50 for rotating and supporting the screw shaft 21. By the regulating claw, rotation of the screw shaft 21 at the time of the abnormality is locked and thereby high speed lowering of the table 2 is prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drive device for a table lift device for moving a table up and down in parallel to a base, for example, a drive motor such as an electric motor or a hydraulic motor and a screw operated by the drive motor. The present invention relates to a drive device including a shaft device.

[0002]

2. Description of the Related Art Generally, a table lift device 1 of this type is used.
For example, as shown in FIG. 3 and FIG. 4, the base 3 and the table 2 are interposed between the base 3 and the table 2, and the two arms 5 and 6 are connected to each other by the connection fulcrum 7. A pair of left and right lift arms 4 and 4 which are rotatably connected to each other via an X-shape, and the lift arms 4 and 4 are vertically expanded and contracted to move the table 2 up and down in parallel with the base 3. The drive device 10 is provided. The drive device 10 includes a screw shaft device 20 interposed between one arm 5 side of the lift arm 4 and the other arm 6 side thereof, and a drive motor 30 for driving the screw shaft device 20. There is. Screw shaft device 20
Includes a screw shaft 21 rotatably supported via a screw shaft support portion 24, and a nut 23 mounted between the other arms 6 and 6 via a connecting sleeve 22 and meshed with the screw shaft 21. The lift arms 4 and 4 are vertically extended and contracted by the movement of the nut 23 as the screw shaft 21 rotates. Although omitted in FIG. 4, a power transmission mechanism 40 including a sprocket and a chain is interposed between the output shaft of the drive motor 30 and the screw shaft 21. Therefore, when the drive motor 30 is started, the screw shaft 21 rotates around the shaft via the power transmission mechanism 40. The drive motor 30 has a built-in electric brake 30a for stopping the table 2 at the rising end position or a position in the middle of rising.
The screw shaft support portion 24, the power transmission mechanism 40, and the drive motor 30 are unitized to form the one arm 5, 5
It is attached to a connecting rod 8 mounted in a spanning manner so as to be vertically tiltable.

[0003]

In the table lift device 1 thus constructed, for example, the power transmission mechanism 4 is used.
When an abnormality occurs, such as when the 0 chain is broken or the built-in brake 30a of the drive motor 30 is inadvertently released, the ascending end or the ascending table 2 immediately descends. If the friction between the screw shaft 21 and the nut 23 can be ignored, the table 2 descends at a high speed in a substantially free fall state. If the table 2 falls freely, it may collide with the base 3 at the time when the table 2 reaches the descending end position, resulting in a large impact or the like, which may cause damage to the table lift device 1. The present invention has been made in view of this problem, and it is possible to prevent damage to the lift device by preventing free fall of the table even in an abnormal case such as when the chain of the power transmission mechanism is cut. It is an object of the present invention to provide a drive device that can be used.

[0004]

For this reason, the present invention provides a drive device having the structure described in each of the claims. According to the drive device of claim 1, when the ascending / descending object starts to descend in a substantially free fall state due to some trouble or the like, the screw shaft starts to rotate at a preset abnormal rotation speed, whereby the operation restricting means is generated. Is activated to regulate the rotation of the screw shaft with respect to the screw shaft support portion (rotational speed of the screw shaft) to reduce the descending speed of the ascending / descending object or stop the descending of the ascending / descending object. According to the drive device of the second aspect, the lift device vertically expands and contracts by the drive device, whereby the table moves up and down. The screw shaft device of the drive device is provided with a screw shaft and a nut that meshes with the screw shaft, and the moving speed of the nut and thus the ascending / descending speed of the table changes according to the rotation speed of the screw shaft.
When the table descends in a substantially free-fall state due to some trouble, the rotation speed of the screw shaft reaches a preset rotation speed at the time of abnormality, and at this time, the operation restricting means operates. When the operation restricting means operates, the rotation of the screw shaft is restricted, so that the descending speed of the table is restricted, thereby avoiding the collision of the table with the base and preventing the lift device from being damaged. According to the drive device of claim 3, since the rotation of the screw shaft is regulated by a purely mechanical structure, the lift device does not increase in cost and does not increase in size. Can be prevented from being damaged.

[0005]

According to the present invention, the lift device is prevented from free fall even in an abnormal case such as when the chain of the power transmission mechanism is broken. Can be prevented.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION Next, an embodiment of the present invention will be described with reference to FIGS. The drive device 100 according to the present embodiment is provided with X-shaped lift arms 4 and 4 formed by connecting two arms 5 and 6 rotatably between the base 3 and the table 2. Then, the case where it is applied to the table lift device 1 which moves the table 2 up and down in parallel with the base 3 by expanding and contracting the lift arms 4 and 4 will be exemplified. Therefore, the drive device 100 of the present embodiment
The table lift device including the
Drive device 10 as compared to table lift device 1 with zero
Since the configurations other than 0 are the same, the same symbols are used and the description thereof is omitted.

The drive device 100 of the present embodiment is provided with a screw shaft device 101 interposed between one arm 5 side of the lift arm 4 and the other arm 6 side thereof, and for driving the screw shaft device 101. A drive motor 30 is provided. The drive motor 30 has a built-in electric brake 30a. A drive side sprocket 41 is attached to the output shaft of the drive motor 30. Screw shaft device 10
1 includes a screw shaft 21 and a nut 23 that meshes with the screw shaft 21. Similar to the conventional structure, the nut 23 is mounted between the other arms 6 and 6 via the connecting sleeve 22 so as to be vertically rotatable and not rotatable around its axis (see FIGS. 3 and 4). ). The tilting proximal end side of the screw shaft 21 is rotatably supported by the screw shaft support portion 50. The driven sprocket 4 is attached to the tip end of the screw shaft 21 on the tilting base end side.
2 is attached. This driven sprocket 42
Between the drive side sprocket 41 and the drive side sprocket 41
Has been bridged.

The screw shaft support portion 50 is a cylindrical case 5.
1 is provided. The case 51 is supported by a connecting rod 8 mounted in a bridging manner between one of the left and right lift arms 4 and 4 so as to be vertically tiltable via a support shaft 52. A cylindrical bearing case 53 is attached to the mouth side of the case 51. Two bearings 54 and 55 are attached to the inner peripheral side of the bearing case 53. The screw shaft 21 is rotatably supported around the shafts via the two bearings 54 and 55. Further, as shown in FIG. 2, the peripheral surface 2 of the bearing case 53 is
Engagement window portions 53a, 53a are formed so as to penetrate through the points at positions symmetrical with respect to each other. The engagement window portions 53a, 53
a will be described later. The screw shaft 21 has
When the rotation speed of the screw shaft reaches a constant value, the operation restricting means 60 for restricting the rotation of the screw shaft 21 with respect to the screw shaft support portion 50 is attached. This operation regulation means 60
Includes a support block 61 that is fixed to the screw shaft 21 and rotates integrally with the screw shaft 21, and two restricting claws 62 and 62 that are rotatably supported by the support block 61.

The support block 61 is provided with two flange portions 61a, 61a which are parallel to each other with a constant space. As shown, these two flange portions 61a, 6
1a is housed on the inner peripheral side of the bearing case 53.
Support shafts 63, 63 are attached in a bridging manner between the flange portions 61a, 61a at two points that are point-symmetric with respect to the axis of the screw shaft 21. These two support shafts 6
The two restricting claws 62, 62 are supported via 3, 63 so as to be rotatable within a certain range in the radial direction of the screw shaft 21. As shown in FIG. 2, the two restricting claws 62, 62 each have a generally arcuate shape when seen in a plan view, and the ends of the restricting claws 62, 62 are supported by the support block 61 via a support shaft 63. The claw portions 6 are respectively provided on the outer peripheral sides of the restriction claws 62, 62.
2a is formed so as to project laterally. The both regulating claws 62, 62 are radially outward (the claw portion 62a is engaged with the engaging window portion 5) by a torsion spring 64 mounted on the support shaft 63.
It is urged in the direction of entering 3a, hereinafter referred to as the "regulating direction".

Further, the lower surface side of both the regulating claws 62, 62 (see FIG. 1)
A detent mechanism 65 is attached to the left side surface in FIG. The detent mechanism 65 includes a compression spring 65.
a steel ball 65b that is urged in the direction of protruding from the lower surface side of the restriction claw 62 by a.
Is pressed against the upper surface (right side in FIG. 1) of the flange portion 61a on one side (left side in FIG. 1) of the support block 61 by the urging force of the compression spring 65a. On the upper surface of the one flange portion 61a of the support block 61, two lock concave portions 61 are provided corresponding to both detent mechanisms 65, 65.
b, 61b are formed. The relative positions of the lock recesses 61b and 61b with respect to the detent mechanism 65 are such that the restriction pawls 62 and 62 are retracted toward the inner peripheral side against the torsion spring 64 (the pawl portion 62a is disengaged from the engagement window portion 53a). (In a state in which it is kept), the steel ball 65 of the detent mechanism 65
It is set at a position where b is fitted. Lock recess 61b
The state in which the steel ball 65b is fitted in is held by the urging force of the compression spring 65a, so that both the restricting claws 62, 62 are held in the retracted position shown by the solid line in FIG. Therefore, the biasing forces of the torsion spring 64 and the compression spring 65a are appropriately set so that the holding force of the detent mechanism 65 is larger than the biasing force of the torsion spring 64.

On the other hand, when the screw shaft 21 rotates, both regulating pawls 6
A centrifugal force (a force that rotates the restriction claw 62 in the restriction direction) is applied to the reference numerals 2 and 62. When the centrifugal force acting on both regulating pawls 62, 62 reaches a certain value, the holding state by the detent mechanism 65 is released, whereby both regulating pawls 62, 62 rotate in the regulating direction by the torsion spring 64 and the centrifugal force, respectively. To do. When both the restricting pawls 62, 62 rotate in the restricting direction, the respective pawl parts 62a enter into the engaging window parts 53a of the bearing case 53, whereby the rotation of the screw shaft 21 with respect to the screw shaft supporting part 50 is blocked, and by extension, The table 2 is prevented from descending. The holding state is released by the detent mechanism 65 by the steel ball 65b retracting to the right in FIG. 1 against the biasing force of the compression spring 65a. The biasing force of the compression spring 65a (holding force of the detent mechanism 65) is set to be smaller than the total of the constant centrifugal force and the biasing force of the torsion spring 64. In the present embodiment, this constant centrifugal force is set to the centrifugal force generated when the screw shaft 21 rotates at the rotation speed when the table 2 descends in a substantially free fall state. Hereinafter, the centrifugal force at the stage when the detent mechanism 65 is released and the operation restricting means functions (the stage where the rotation of the screw shaft 21 is blocked) is particularly referred to as “the centrifugal force at the time of abnormality”. Further, the rotation speed of the screw shaft 21 for generating the centrifugal force at the time of abnormality is particularly referred to as "rotation speed at the time of abnormality".

According to the drive device 100 of the present embodiment having the above-mentioned configuration, the drive motor 30 is activated to the rising side,
In addition, when the built-in brake 30a is released, both lift arms 4 and 4 extend upward, and thereby the table 2 rises. On the other hand, when the drive motor 30 starts to move downward and the built-in brake 30a is released, the table 2 slowly descends at a speed according to the rotation speed of the drive motor 30. When the screw shaft 21 rotates at a lower speed than the normal rotation speed, a large centrifugal force does not act on the restricting pawls 62 and 62, and therefore the restricting pawl 62 does not move. , 62, the steel ball 65b is recessed 6
It is held at the position where it entered 1b. In this way, when the table 2 slowly descends at the normal speed, the motion restricting means 60 does not operate, so that the table 2 descends to the descending end.

On the other hand, for example, when the built-in brake 30a is inadvertently released in a state where the drive motor 30 is not energized (idling state, no resistance is generated when the table 2 is lowered), Alternatively, even when the chain 43 of the power transmission mechanism 40 is broken irrespective of the energization state of the drive motor 30, the operation restriction means 60 prevents the table 2 from freely falling and the table lift device concerned. It is possible to prevent 100 from being damaged. That is, the load of the table 2 (including the load of the loaded luggage) is increased by the lift arms 4, 4, the screw shaft device 101,
It is added to the built-in brake 30 a of the drive motor 30 via the power transmission mechanism 40. Therefore, for example, the power transmission mechanism 4
In the idle state where the chain 43 of 0 is cut and the drive motor 30 is not energized, the load of the table 2 cannot be received and the table 2 descends in a substantially free fall state. In the conventional case, the table 2 could fall freely and collide with the base 3 side, resulting in damage to the table lift device 1. However,
According to the drive device 100 of the present embodiment, when the table 2 starts to descend in a substantially free fall state, the screw shaft 21 has both the restriction pawls 62, 62 of the operation restriction means 60 for rotating at the rotation speed at the time of abnormality. The centrifugal force at the time of abnormality is applied, and as a result, both the restriction claws 62, 62 rotate in the restriction direction while releasing the detent mechanisms 65, 65 by the centrifugal force at the time of abnormality and the biasing force of the torsion spring 64. When both the restricting claws 62, 62 rotate in the restricting direction, the respective claw parts 62a enter the engaging window part 53a of the bearing case 53, and immediately after that, the claw part 62a.
a engages with the end of the engagement window 53a, and at this stage, the rotation of the support block 61 with respect to the bearing case 53 is locked, whereby the rotation of the screw shaft 21 with respect to the screw shaft support 50 is locked and the table 2 Is prevented from falling.

As described above, the drive device 100 according to the present embodiment.
According to this, when the table 2 is lowered in a substantially free fall state due to the chain 43 of the power transmission mechanism 40 being cut or the like, the rotation of the screw shaft 21 is locked and the fall of the table 2 is prevented. Therefore, it is possible to prevent damage to the table lift device. Further, since the free fall of the table 2 is prevented only by the pure mechanical and compact structure without using, for example, an expensive rotation speed detection sensor or a large lock device, a large cost increase or a large lift device is required. It is possible to obtain a reliable table lock function without incurring any change.

Various changes can be made to the embodiment described above. For example, the case where the present invention is applied to the table lift device that moves up and down the table by the expansion and contraction operation of the lift arm 4 in which the two arms 5 and 6 are connected in an X-shape has been exemplified, but the drive device according to the present invention is not limited to this. The same can be applied to a lift device that operates a screw shaft device interposed between a table and a base to directly move the table up and down (without a lift arm). In this case, for example, a screw shaft is rotatably supported on the base side in a standing manner, a nut that meshes with the screw shaft is fixed to the object side to be lifted, and the screw shaft is rotated by a drive motor to move the object vertically. Can be made. This configuration corresponds to the embodiment of the invention described in claim 1.

Further, in the above-described embodiment, the detent mechanism 65 is released at the rotational speed of the screw shaft 21 when the table 2 falls substantially freely (rotational speed at the time of abnormality), and the regulating claw 6 is released.
Although the configuration in which 2 moves in the regulation direction is illustrated, the operation timing of the movement regulation means can be set to a speed slower than the free fall speed of the table 2. That is,
Even if the chain 43 is not cut, the movement restricting means 60 illustrated in FIG. 2 is operated to operate the table 2 on the base 3 even when the descending speed of the table 2 is not as high as the free falling speed but is abnormally high. Collisions can be avoided. Furthermore, although a configuration in which the claw portion 62a of the regulating claw 62 is engaged with the end portion of the engagement window portion 53a to completely lock the rotation of the screw shaft 21 is shown, for example, the engagement window portion 53a is abolished and regulation is performed. Nail 6
By pressing 2 against the inner peripheral surface of the bearing case 53 by utilizing the biasing force of the torsion spring 64, it is possible to give a rotational resistance to the screw shaft 21 and reduce the descending speed of the table 2. Also, it is possible to prevent the table 2 from colliding with the base 3 and prevent the lift device from being damaged. Further, the table lift device provided with the table for loading a person, an article or the like has been exemplified, but the present invention can also be applied to a lift device in which not a table but other objects are directly moved up and down.

[Brief description of drawings]

FIG. 1 is a view showing an embodiment of the present invention, and is a vertical cross-sectional view of a screw shaft support portion.

FIG. 2 is a sectional view taken along line (2)-(2) of FIG.
It is a cross-sectional view of the motion restricting means.

FIG. 3 is a side view of a table lift device including a drive device mainly including a screw shaft device.

FIG. 4 is a plan view of a table lift device including a drive device mainly including a screw shaft device.

[Explanation of symbols]

1 ... Table lift device 2 ... table, 3 ... base, 4 ... lift arm 10 ... Drive device (conventional) 20 ... Screw shaft device, 21 ... Screw shaft, 23 ... Nut 24 ... Screw shaft support 30 ... Drive motor, 30a ... Built-in brake 40 ... Power transmission mechanism, 43 ... Chain 50 ... Screw shaft support 53a ... Engaging window 60 ... Operation restriction means 61 ... Support block, 61b ... Lock recess 62 ... Regulating claw, 62a ... Claw part 64 ... torsion spring 65 ... Detent mechanism 100 ... Drive device (this embodiment) 101 ... Screw shaft device

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[Procedure amendment]

[Submission date] October 17, 2001 (2001.10.
17)

[Procedure Amendment 1]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 2

[Correction method] Change

[Correction content]

[Fig. 2]

[Procedure amendment]

[Submission date] October 23, 2001 (2001.10.
23)

[Procedure Amendment 1]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 2

[Correction method] Change

[Correction content]

[Fig. 2]

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Claims (3)

[Claims] 1. A drive device in a lift device, wherein a drive device is interposed between a base and an ascending / descending object that moves up and down with respect to the base, and the elevating object is moved up and down by the operation of the drive device. A drive motor, a screw shaft that is rotated by the drive motor, and a nut that meshes with the screw shaft, and the rotation speed of the screw shaft is preset between the screw shaft and a screw shaft support portion that rotatably supports the screw shaft. A drive device comprising an operation restricting means for restricting rotation of the screw shaft with respect to the screw shaft support portion when the set rotational speed at the time of abnormality is reached. 2. A lift arm which is interposed between a base and a table and which has two arms rotatably connected to each other in an X-shape, and the lift arm which is vertically extended and contracted to move the table. A lift device for moving up and down in parallel to the base, a screw shaft device interposed between one arm side of the lift arm and the other arm side, and a drive for driving the screw shaft device. A motor, the screw shaft device includes a screw shaft mounted on the one arm side and rotated by the drive motor, and a nut mounted on the other arm side and meshed with the screw shaft, A drive device for vertically expanding and contracting the lift arm by movement of the nut according to rotation of the screw shaft, the rotation of the screw shaft between the screw shaft and a screw shaft support portion that rotatably supports the screw shaft. When the degree has reached the rotational speed of the abnormal set in advance, the driving device including an operation restriction means for restricting rotation relative to the screw shaft supporting portion of the screw shaft. 3. The drive device according to claim 1, wherein the operation restricting means includes a restricting pawl provided on the screw shaft side and rotatable in a radial direction of the screw shaft, By utilizing the centrifugal force at the time when the rotation speed of the rotation speed reaches the rotation speed at the time of abnormality, the restriction claw is moved in the restriction direction to be engaged with the engagement window portion provided on the screw shaft support portion side. A drive device configured to regulate the rotation of the screw shaft.