JP5468646B2 - Table lift device - Google Patents

Description

  The present invention relates to a table lift device that moves up and down a table on which articles to be lifted and the like are mounted in parallel to a base (base).

This type of lift device, generally referred to as a table lift device, includes a pair of lift arms in which an inner arm and an outer arm are coupled in an X shape so as to be rotatable between a base and a table, and the pair of lift arms. A drive device that vertically expands and contracts the lift arm is interposed, and various drive methods such as an hydraulic / pneumatic type and an electric type have been known for this drive device.
In the following Patent Document 1 and Patent Document 2, two screw shaft mechanisms (a mechanism for linearly moving a nut by rotation of a screw shaft) are arranged between a pair of left and right lift arms, and both screw shaft mechanisms are electric motors. A lift device is described in which left and right lift arms are vertically expanded and contracted by operating in synchronization. According to such a conventional lift device, since a screw shaft mechanism (electric cylinder) operated by an electric motor instead of a hydraulic cylinder is used as a drive device, there is no risk of oil leakage and the like, which is excellent in maintainability.

JP-A-1-104597 JP-A-6-9193

However, the lift device using the conventional electric cylinder as a driving device has the following problems to be solved. The conventional drive device has a configuration in which two screw shaft mechanisms are interposed between the left and right lift arms, and the both screw shaft mechanisms are operated synchronously by one electric motor. For this reason, the rotational power of the electric motor is transmitted to the left and right screw shaft mechanisms via the chain transmission mechanism, and there is a problem that the configuration is complicated mainly in that two chain transmission mechanisms are interposed. .
An object of this invention is to be able to simplify the structure of the said drive device compared with the past, when providing a plurality of sets of screw shaft mechanisms as a drive device.

The above problem is solved by the following invention.
According to a first aspect of the present invention, there is provided a pair of front and rear lift arms formed by connecting an inner arm and an outer arm in an X shape between a base and a table so as to be rotatable relative to each other; A plurality of sets of electric cylinders that move up and down in parallel to the base, each electric cylinder having an electric motor as a drive source, a screw shaft that is rotated by the electric motor, and a screw shaft that has a nut meshed with the screw shaft A table lift device comprising a mechanism and interposed between an inner arm and an outer arm, and configured to stop the electric cylinder based on variations in displacement amounts with respect to screw shafts between nuts of a plurality of sets of electric cylinders It is.
According to a second invention, in the first invention, a driving roller is provided in an intermediate arm supported by the inner arm so as to be pivotable up and down, and the driving roller is linked so as to roll along a guide hole provided in the outer arm. The pair of front and rear intermediate arms are coupled to each other via a roller support, and the nuts of the electric cylinders are connected to the roller support so as to be displaceable within a certain range in the screw shaft direction. The table lift device is configured to detect the displacement of the plurality of nuts with respect to the roller support and to stop the electric cylinders based on variations in the displacement of the nuts.
According to the first or second invention, for a plurality of sets of electric cylinders installed between lift arms, each screw shaft mechanism operates using a unique electric motor as a drive source. In the case of the conventional configuration in which the electric motor is operated as a drive source, there is no need for a chain transmission mechanism having a long distance, and a chain transmission mechanism having a shorter distance is sufficient as compared with the conventional configuration, so that the drive device can be simplified. it can.
According to the first or second invention, it is possible to avoid the asynchronous operation state of the plurality of electric motors by providing each electric cylinder with an individual electric motor. Since the asynchronous operation state of the electric motor set individually for each electric cylinder is avoided, there is no need for an expensive and complicated control servo motor as the electric motor. It can be used as a drive source for the electric cylinder, and thus the cost of the table lift device can be reduced.

It is a top view of the table lift device concerning this embodiment. This figure shows a state where the table is lowered to the lower end position. It is a front view of the table lift device concerning this embodiment. This figure has shown the state in the middle of table raising / lowering. It is a front view of the table lift device concerning this embodiment. This figure shows a state where the table is lowered to the lower end position. It is a figure which shows the operation state of a synchronous driving | operation detection part, and is a top view of a roller support body. This figure shows a state in which power in the upward direction is not transmitted to the roller support in the driving device on the rear side. It is a figure which shows the operation state of a synchronous driving | operation detection part, and is a top view of a roller support body. This figure shows a state in which power in the upward direction is not transmitted to the roller support in the front drive device.

Next, an embodiment of the present invention will be described with reference to FIGS. As shown in FIGS. 1 and 2, the table lift device 1 of the present embodiment is a lift device driven by an intermediate arm, a base 2 installed on the floor F, a table 3 for loading cargo and the like, A pair of front and rear (up and down in FIG. 1) lift arms 10 and 10 interposed between the table 3 and the base 2 and a drive device PW for expanding and contracting the lift arms 10 and 10 up and down are provided. The front and rear lift arms 10 and 10 extend vertically by the drive device PW, and the table 3 moves up and down in parallel with the base 2.
The front and rear lift arms 10 and 10 each have a configuration in which an inner arm 11 and an outer arm 12 are coupled to each other in an X shape via a rotation support shaft 13 at a substantially central portion in the longitudinal direction. The rotation support shafts 13 and 13 in the front and rear lift arms 10 and 10 are arranged coaxially with each other.
The left ends of the front and rear inner arms 11 and 11 are coupled to each other via a coupling member 14, and the right ends are coupled to each other via a coupling member 15. The left ends of the outer arms 12 and 12 are coupled to each other via a coupling member 19, and the right ends are coupled to each other via a coupling member 17. Therefore, the front and rear inner arms 11 and 11 are integrally rotated up and down, and the front and rear outer arms 12 and 12 are integrally rotated up and down. As a result, the front and rear lift arms 10 and 10 are integrally expanded and contracted up and down. .
The left end portions of the front and rear inner arms 11 and 11 are respectively supported by the left end portion of the lower surface of the table 3 via a support shaft 18 so as to be vertically rotatable. Guide wheels 20, 20 are rotatably supported at the right ends of the front and rear inner arms 11, 11. Both guide wheels 20 are supported so as to roll along the upper surface near the right end of the base 2.
The left end portions of the front and rear outer arms 12 and 12 are supported on the upper left end portion of the base 2 via a coupling member 19 so as to be vertically rotatable. Guide wheels 21 and 21 are rotatably supported at the right ends of the front and rear outer arms 12 and 12. Both guide wheels 21 and 21 are supported so as to roll along the lower surface near the right end of the table 3.

One end side of the intermediate arm 46 is supported by the front and rear inner arms 11 and 11 via a common intermediate support shaft 45 so as to be vertically rotatable. Since the front and rear intermediate arms 46 and 46 are coupled to each other via a coupling member 46a, they are integrally tilted up and down. The front and rear intermediate arms 46, 46 are connected to each other via a roller support 47. The rotating front ends of the front and rear intermediate arms 46 and 46 are rotatably coupled to the front and rear end portions of the roller support 47. Drive rollers 48 and 48 are rotatably supported at both front and rear ends of the roller support 47 via support shafts 47a and 47a provided coaxially with each other. Both the drive rollers 48, 48 enter the guide holes 43 provided in the outer arm 12, respectively. As shown in FIG. 2, the guide hole 43 is formed in a slot shape that is long along the longitudinal direction of the outer arm 12 between the rotation support shaft 13 and the coupling member 17.
As shown in FIG. 2, when the drive roller 48 is moved to the left side of the guide hole 43 and the intermediate arm 46 rotates counterclockwise about the intermediate support shaft 45, the outer arm 12 moves the rotation support shaft 13 in the middle. The inner arm 11 is relatively rotated in the clockwise direction while the lift arm 10 is extended upward, so that the table 3 is raised. Conversely, when the drive roller 48 is moved to the right side of the guide hole 43 and the intermediate arm 46 is rotated clockwise around the intermediate support shaft 45, the outer arm 12 is rotated clockwise while the inner arm is rotated. 11 rotates relatively counterclockwise, the lift arm 10 is reduced downward, and the table 3 is lowered.

In this manner, in the front and rear lift arms 10, 10, the tip end portion (drive roller 48) of the intermediate arm 46 interposed between the inner arm 11 and the outer arm 12 is moved along the guide hole 43 to thereby perform the intermediate operation. By rotating the arm 46 up and down around the intermediate support shaft 45, the front and rear lift arms 10 and 10 expand and contract.
The intermediate arms 46 and 46 are rotated up and down by two sets of electric cylinders 50 and 50. Both electric cylinders 50 and 50 are arranged in parallel in the front and rear between the front and rear lift arms 10 and 10. Both electric cylinders 50 and 50 are located at a position avoiding the rotation support shaft 13 of the lift arm 10, and are supported by the coupling member 16 that couples the outer arms 12 and 12 to each other so as to be able to tilt up and down via a tilt shaft 51a. Has been.
The electric cylinder 50 includes an electric motor 52 and a screw shaft mechanism 53. The screw shaft mechanism 53 includes a screw shaft 53a rotated by the electric motor 52 and a nut 53b engaged with the screw shaft 53a. The rotational power of the electric motor 52 is transmitted to the screw shaft mechanism 53 through a power transmission unit 51 having a chain transmission mechanism including a chain with a short distance. An operating sleeve 54 having a long cylindrical shape is coaxially attached to the nut 53b. The screw shaft 53a advances and retreats on the inner peripheral side of the operating sleeve 54.
The right end sides of the operating sleeves 54 are connected to the roller support 47. The roller support body 47 is a coupling member having a long bar shape with a rectangular cross section, and the rotational front ends of the front and rear intermediate arms 46 and 46 are coupled to the front and rear end portions thereof so as to be relatively rotatable.

The roller support 47 is provided with circular insertion holes 47b and 47b through which the operation sleeves 54 and 54 can be inserted so as to penetrate between the two left and right side surfaces facing each other. Both the operating sleeves 54 are inserted into the insertion hole 47b. A stopper flange 54 a is integrally provided on the left side of the roller support 47 of both the operating sleeves 54, 54. The distal end side (right side) of the stopper flange 54a is inserted into the insertion hole 47b. The right end portions of both the operating sleeves 54 and 54 are protruded rightward from the roller support 47 through the insertion holes 47b. Stopper pins 55 are attached to the protruding portions so as to penetrate in the radial direction. Both end portions of the stopper pin 55 are protruded on both sides in the radial direction of the operating sleeve 54. Both the operating sleeves 54, 54 are axially disposed in the insertion hole 47 b within a range in which the stopper flange 54 a contacts the left side surface of the roller support body 47 and the stopper pin 55 contacts the right side surface of the roller support body 47. It is inserted in such a way that it can be relatively displaced in the left-right direction).
When the nuts 53b, 53b and the operating sleeves 54, 54 move to the left with respect to the roller support 47 by the rotation of the screw shafts 53a, 53a in the front and rear electric cylinders 50, 50, the stopper pins 55, 55 are moved to the roller support. The thrust of the front and rear electric cylinders 50, 50 in contact with the right side surface of 47 is applied to the roller support 47, whereby the roller support 47 moves to the left in FIG. As the roller support 47 moves to the left, the intermediate arms 46 and 46 tilt in the counterclockwise direction in FIG. 2, and the front and rear lift arms 10 and 10 extend upward.
As the screw shafts 53a and 53a rotate in the opposite direction and the nuts 53b and 53b and the operating sleeves 54 and 54 move to the right, the roller support 47 is allowed to be displaced to the right. , 46 in FIG. 2 is allowed to tilt in the clockwise direction, and the front and rear lift arms 10 and 10 are reduced downward due to the load of the table 3 and the like. FIG. 3 shows a state where the table 3 is lowered to the lower end position.
Stopper bars 57 to 57 for restricting the lower end position of the table 3 are provided at the four front and rear, left and right corners of the base 2 so as to stand upward. When the table 3 is lowered by the downward contraction of the front and rear lift arms 10 and 10 and reaches the lowered end position, the stopper bars 57 to 57 come into contact with the four lower corners of the table 3 from below as shown in FIG. Thus, the table 3 is held at the lower end position.

The relative displacements of the two operating sleeves 54 and 54 with respect to the roller support 47 are detected by the synchronous operation detectors 58 and 58. Both synchronous operation detectors 58 and 58 are constituted by the stopper pin 55 and a sensor (limit switch) 56, respectively. The sensor 56 is supported on the right side of the roller support 47. By detecting the displacement of the stopper pin 55 by the sensors 56, 56, the relative displacement of the operating sleeve 54 with respect to the roller support 47 is indirectly detected.
The relative displacement of the front and rear working sleeves 54 and 54 with respect to the roller support 47 is detected by the sensor 56, whereby the front and rear electric cylinders 50 and 50 are operated synchronously. When variations occur in the starting timing and rotational speed of the electric motors 52, 52 in the front and rear electric cylinders 50, 50, the timing of starting movement and the moving speed of the operating sleeves 54, 54 vary through the rotation of the screw shafts 53a, 53a. As a result, as shown in FIGS. 4 and 5, the relative positions of the front working sleeve 54 and the rear sleeve 54 with respect to the roller support 47 are different.
In the state shown in FIG. 4, the front operating sleeve 54 is displaced to the left and the stopper pin 55 is in contact with the right side surface of the roller support 47, but the rear operating sleeve 54 is displaced to the right and the stopper flange 54 a is in contact with the left side surface of the roller support body 47, so that the stopper pin 55 is separated from the right side surface of the roller support body 47. When the stopper pin 55 is in contact with the right side surface of the roller support 47, the sensor 56 is turned on, and when it is separated, the sensor 56 is turned off. In this state, the operating states of the front and rear electric cylinders 50, 50 are not synchronized, the contraction amount of the rear lift arm 10 is insufficient compared to the front side, and the table 3 slightly moves to the back side (rear side). There is a risk of tilting in a downward direction.

In the state shown in FIG. 5, the rear working sleeve 54 is displaced to the left and the stopper pin 55 is in contact with the right side surface of the roller support 47, but the front working sleeve 54 is displaced to the right and the stopper flange 54 a is in contact with the left side surface of the roller support body 47, so that the stopper pin 55 is separated from the right side surface of the roller support body 47. Even in this state, the operating states of the front and rear electric cylinders 50, 50 are not synchronized, and the amount of contraction of the front lift arm 10 is less than that of the rear side, so that the table 3 slightly falls to the front side (front side). There is a risk of being inclined in the direction.
As described above, when the operation states of the front and rear electric cylinders 50 and 50 are varied and deviated from the synchronous operation state, the table 3 may be slightly tilted, and the drive device including the electric cylinders 50 and 50 is included. There is a risk of causing damage to the PW or damage to the front and rear lift arms 10, 10, and as a result, the durability of the table lift device 1 may be impaired. Such troubles can occur both when the table 3 is raised and when it is lowered.
In the table lift device 1 of the present embodiment, synchronous operation detection units 58 and 58 are provided in order to avoid such a trouble in advance. The relative positions of the front and rear working sleeves 54 and 54 with respect to the roller support 47 are detected by the sensors 56 and 56 by the two synchronous operation detection units 58 and 58. In this embodiment, the state in which the front and rear stopper pins 55 and 55 are both in contact with the right side surface of the roller support 47 and the front and rear sensors 56 and 56 are both turned on is the synchronous operation state. In the control device of the drive device PW, the operation of the front and rear electric cylinders 50 and 50 is stopped by determining that the operation is asynchronous when the one sensor 56 is turned off.

According to the table lift device 1 configured as described above, two sets of electric cylinders 50 and 50 are arranged in parallel between the base 2 and the table 3. Both electric cylinders 50 and 50 are each provided with an electric motor 52 and a screw shaft mechanism 53. For this reason, as compared with the conventional configuration in which two sets of screw shaft mechanisms are operated synchronously by one electric motor, it is not necessary to use a chain having a long distance, and the power transmission mechanism is simplified.
In addition, the synchronous operation state of the electric motors 52 and 52 in the front and rear electric cylinders 50 and 50 is mainly detected indirectly by the sensors 56 and 56, and the operation is stopped when the asynchronous operation state is detected. Has been. As a result, excessive lifting and lowering operations of the table 3 are avoided and the drive device PW is protected, so that a servo motor that requires expensive and complicated control is used as its drive source (electric motors 52 and 52). Needless to say, an inexpensive and easily available induction motor can be used, and as a result, the cost of the table lift device 1 can be reduced.
Various modifications can be added to the embodiment described above. For example, although the drive device PW including two sets of electric cylinders 50 and 50 is illustrated, the present invention can be similarly applied to a drive device including three or more sets of electric cylinders.
Moreover, although the structure which incorporates the chain transmission mechanism as the power transmission part 51 of both the electric cylinders 50 and 50 was illustrated, the electric cylinder which equipped the power transmission mechanism by meshing | engagement of a gear is also applicable. Furthermore, it is good also as a structure using the electric cylinder which directly connected the screw shaft to the electric motor (geared motor) which equipped the reduction gear train internally. In any case of the electric cylinder, the power transmission distance can be further shortened as compared with the conventional configuration in which a plurality of sets of electric cylinders are operated synchronously by a common electric motor. Can be simplified.
Furthermore, the limit switch is used as the sensor 56 of the synchronous operation detection unit 58, and the configuration in which the relative position of the operation sleeve 54 is detected by the sensor 56 is illustrated. However, another type of sensor such as an optical sensor may be used, For example, instead of the sleeve 54, for example, the inclination of the table 3 may be directly detected to determine the synchronous operation state of the drive device PW.
Moreover, the intermediate arm drive type table lift device 1 that extends and contracts the lift arms 10 and 10 by tilting the pair of front and rear intermediate arms 46 and 46 up and down by the drive device PW is illustrated. Instead, a wedge roller is sandwiched between the cam plates provided on the inner arm and the outer arm, and the wedge roller is displaced by the driving device PW, so that it is applied to a cam-driven electric table lift device that expands and contracts the lift arm up and down. can do.

DESCRIPTION OF SYMBOLS 1 ... Table lift apparatus 2 ... Base 3 ... Table PW ... Drive apparatus 10 ... Lift arm (intermediate arm drive type)
DESCRIPTION OF SYMBOLS 11 ... Inner arm 12 ... Outer arm 13 ... Rotating support shafts 14, 15 ... Coupling member 18 ... Support shaft 20 ... Guide wheel 43 ... Guide hole 45 ... Intermediate support shaft 46 ... Intermediate arm 47 ... Roller support, 47a ... Support shaft , 47b ... insertion hole 48 ... drive roller 50 ... electric cylinder 51 ... power transmission part, 51a ... tilting shaft 52 ... electric motor 53 ... screw shaft mechanism, 53a ... screw shaft, 53b ... nut 54 ... operating sleeve, 54a ... stopper flange 55 ... Stopper pin 56 ... Sensor, 56a ... Bracket 57 ... Stopper bar 58 ... Synchronous operation detector

Claims (2)

A pair of front and rear lift arms in which an inner arm and an outer arm are connected to each other in an X shape between the base and the table so that they can rotate with each other; Multiple sets of electric cylinders that move up and down in parallel,
Each electric cylinder includes an electric motor as a drive source, a screw shaft mechanism that includes a screw shaft that is rotated by the electric motor, and a nut that is meshed with the screw shaft, and is provided between the inner arm and the outer arm. Is intervening,
Each nut of the plurality of sets of electric cylinders is connected to a roller support interposed between the pair of front and rear lift arms so as to be independently displaceable within a certain range in the screw axis direction,
A table lift device configured to detect a displacement of each of the plurality of nuts relative to the roller support in the screw shaft direction and stop the electric cylinder based on a variation in a displacement amount of each nut . 2. The table lift device according to claim 1, wherein a driving roller is provided on an intermediate arm supported by the inner arm so as to be pivotable up and down, and the driving roller rolls along a guide hole provided in the outer arm. capable being linked, the is between front after the pair of intermediate arm roller support table lifting apparatus and configuration coupled to one another via.

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