KR20000076588A - Screw-Driven Linear Actuator - Google Patents

Abstract

It provides a quiet, high-speed operation while providing a screw-driven linear actuator with low power consumption.

A drive nut 5 rotatably supported by the housing 1, a screw shaft 6 which is screwed into the drive nut and linearly moves back and forth in the axial direction by the rotation thereof, and an outer side of the drive nut 5; An input shaft rotated freely by the driven helical gear 8 and the housing 2 so that the driving nut 5 and the central axis intersect three-dimensionally so as to rotate integrally with the circumference thereof. 12) and a drive helical gear 13 which is provided so as to rotate integrally with the driven helical gear 8 and which transmits rotation from the input shaft 12 side to the drive nut 5 in engagement with the driven helical gear 8.

Description

Screw-Driven Linear Actuator

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a screw-driven linear actuator used for lifting a heavy object, and more particularly, to a linear actuator for moving the screw shaft at high speed.

Background Art Conventionally, a screw-driven linear actuator is widely used for lifting and lifting of heavy materials. 4 and 5 show an example of a screw-driven linear actuator incorporating a conventional worm reduction mechanism, wherein the driving nut A4 is freely supported by the bearings A2 and A3 in the housing A1. The screw nut A5 is screwed on the drive nut A4 in a state in which rotation is restricted with respect to the housing A1 side.

A worm wheel A6 is integrally formed on the outer circumference of the driving nut A4, and the worm wheel A6 is formed on the input shaft A9 freely supported by the housing A1 as the bearings A7 and A8. It meshes with the installed worm A10.

When the input shaft A9 is rotated by being connected to a rotational drive (not shown), the rotation is transmitted to the driving nut A4 through the worm A10 and the worm wheel A6, and the screw shaft A5. It moves forward and backward in this axial direction.

At the front end of the screw shaft A5, a connecting screw portion A11 is formed to be connected to a load supporting member (not shown), and the thrust load transmitted to the screw shaft A5 through the connecting screw portion A11 is a screw. It is supported by the driving nut A4 which is fitted.

6 and 7 show an example of a screw driven linear actuator incorporating a bevel gear reduction mechanism, which is a driven bevel gear B2, a holding cylinder B3, and a driving nut in a housing B1. (B4) is integrally connected as the same shaft, and the holding cylinder (B3) and the boss (B5) of the driven bevel gear (B2) are rotatably held in the housing (B1) as bearings (B6, B7), respectively. .

The screw shaft B8 penetrates through the center of the center of the boss B5 of the driven bevel gear B2, the holding cylinder B3, and the driving nut B4, and the screw shaft B8 is The screw is fitted to the drive nut B4, and the retraction is provided freely in the axial direction while the rotation is restricted with respect to the housing B1 side.

The housing B1 is rotatably supported by the bearings B10 and B11 so that the screw shaft B8 and the center axis line are perpendicular to each other, and the housing B1 of the input shaft B9 is supported. At the inner end portion thereof, a driving bevel gear B12 meshing with the driven bevel gear B2 is fixed.

Similarly to the screw-driven linear actuator incorporating the worm reduction mechanism described above, when the input shaft B9 is connected to a rotation drive source (not shown) and rotates, this rotation is driven from the driven bevel gear B12 to the driven bevel gear B2. ), The drive nut (B4) is rotated, the screw shaft (B8) is driven back and forth in the axial direction.

Then, lifting and lowering of the heavy object is performed via a load supporting member (not shown) connected to the connecting screw portion B13 at the front end of the screw shaft B8.

In the conventional screw-driven linear actuator as described above, when the worm reduction mechanism is used, the reduction ratio between the worm and the worm wheel is large, so it is not suitable when the screw shaft needs to be moved back and forth at high speed. In order to move back and forth at high speed, the number of rotations on the input shaft side must be increased. However, in the engagement operation of the worm and the worm wheel, there is a problem in that the transmission efficiency is low and the power waste is severe because the relative slip amount between the teeth to be engaged is large.

In addition, when the bevel gear reduction mechanism is used, the reduction ratio between the driving bevel gear and the driven bevel gear is relatively small, and the screw shaft can be moved back and forth at high speed, but the engagement noise between these bevel gears increases during operation. In particular, there is a problem that it is difficult to use, for example, lifting and lowering of a stage device whose absolute condition is low noise.

In addition, in the linear actuator using the bevel gear reduction mechanism, since the screw shaft and the center axis line of the input shaft are orthogonal to each other, the input shaft can only be projected to one side of the housing. By projecting to both sides of the housing, one protruding end of the input shaft is connected to the rotary drive source, the other protruding end is connected to the input shaft of the other linear actuator, and the plural linear actuators are operated synchronously in a common rotary drive source, or Can not be used to connect to the protruding end of both sides of the input shaft, there is a problem that the use form is limited.

In addition, in the case of using the worm reduction mechanism or bevel gear reduction mechanism as described above, there is a problem that the manufacturing cost increases due to a large amount of hand, for example, in tooth cutting of worms, worm wheels, or bevel gears.

In addition, although not shown, the input shaft and the screw shaft are arranged in parallel in an adjacent position, and the reduction gear is formed by installing cylindrical gears, such as spur gears and helical gears, on the input shaft and a drive nut screwed to the screw shaft, respectively. Although a linear actuator having a has been conventionally manufactured, there is a problem in that the degree of freedom of the arrangement of the rotation driving source is limited or it is difficult to synchronously drive a plurality of linear actuators of the same kind.

Accordingly, an object of the present invention is to provide a screw-driven linear actuator that can solve the problems in the prior art as described above, which can perform quiet operation and high speed, and which has low power consumption.

1 is a longitudinal sectional view showing an embodiment of the linear actuator of the present invention;

2 is a cross-sectional view seen in the direction of the arrow from the line A-A of FIG.

Figure 3 is a cross-sectional view showing another embodiment of the linear actuator of the present invention,

4 is a longitudinal sectional view showing an example of a screw-driven linear actuator incorporating a conventional worm reduction mechanism;

5 is a cross-sectional view seen in the direction of the arrow from the position B-B in FIG. 4,

6 is a longitudinal sectional view showing an example of a screw-driven linear actuator incorporating a conventional bevel gear reduction mechanism;

FIG. 7 is a plan view of the screw driven linear actuator shown in FIG. 6. FIG.

<Explanation of symbols for main parts of drawing>

1,1 ': linear actuator 2,2': housing

2A: Screw shaft cover 2B: Motor mounting surface

2C, 2'B, 2'C: outer side 3,4,9,10,11,9 ', 10': bearing

5: Driving nut 6: Screw shaft

7: Connecting thread part 8: Driven helical gear

12,12 ': Input shaft 12A, 12C, 12'C, 12'D: End

12B: Connecting Groove 13: Driven Helical Gear

14: electric motor (rotary drive source) 14A: motor shaft

14B: projecting connection T, t: tooth

In order to achieve the above object, the linear actuator of the present invention includes a drive nut freely supported on the housing, a screw shaft which is screwed with the drive nut, and linearly moves back and forth in the axial direction by the rotation of the drive nut; And a driven helical gear installed at the outer circumference of the driving nut to rotate integrally therewith, the input shaft being freely supported by the housing so that the driving nut and the central axis intersect three-dimensionally, and being rotated as a rotation driving source, and on the input shaft. It is installed so as to rotate integrally with the driven helical gear is provided with a drive helical gear for transmitting rotation to the drive nut on the input shaft side.

It is preferable that the driven helical gear and the driving helical gear are each formed with a twist angle of about 45 degrees in the same direction.

When the input shaft is rotated by a rotation drive source such as an electric motor, the driving helical gear provided on the input shaft rotates integrally with the rotation, and the rotation is transmitted to the driving nut through the driven helical gear engaged with the driving helical gear.

The rotation of the drive nut causes the screw shaft to move back and forth in the axial direction, and loads and lifts the heavy material on the upper end of the screw shaft in the vertical direction, or the driven member connected to the front end by installing the screw shaft in a desired direction. Can move forward and backward.

Since the driving nut is rotated by the engagement of the driving helical gear and the driven helical gear, the retraction operation of the screw shaft is performed at a high speed as compared with the linear actuator using the worm reduction mechanism.

In addition, similarly to the engagement between the worm and the worm wheel, since both helical gears are engaged with each other while being slid together, power transmission is performed from the input shaft to the driving nut, so that the engagement noise generated between the gears during operation is small.

(Example)

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of this invention is described based on drawing. 1 is a longitudinal cross-sectional view showing an embodiment of the linear actuator of the present invention, Figure 2 is a cross-sectional view seen in the direction of the arrow in the AA line position of Figure 1, the linear actuator 1 shown in these figures, the housing 2 The drive nuts 5 are freely supported by the bearings 3 and 4, and the screw shafts 6 are screwed through the inside of the drive nuts 5.

The linear actuator 1 of this embodiment is provided with the screw shaft 6 vertically for use for lifting a heavy object. The upper end of the screw shaft 6 is not shown for supporting a heavy object. A connecting screw portion 7 for attaching a load supporting member is provided.

In addition, the lower part of the screw shaft 6 is accommodated in 2 A of cylindrical screw shaft covers provided below the housing 2. As shown in FIG.

In the outer circumference of the drive nut 5, a driven helical gear 8 having a torsional angle of the tooth T "an angle formed between the direction of the center axis of the drive nut 5 and the direction of the tooth T" is 45 degrees. It is formed.

The helical gear 8 has a pair of driving helical gears 13 provided at both sides thereof in the housing 2 as a bearing 9 and an input shaft 12 freely supported by rotation as bearings 10 and 11. Is interlocked.

The driving helical gear 13 has a tooth shape T which is twisted at a torsion angle of 45 degrees in the same direction as the driven helical gear 8, and the input shaft 12 is formed so that the central axis of the two crosses three-dimensionally at an angle of 90 degrees. This is arranged.

The input shaft 12 traverses in the radial direction of the input shaft 12 to the end portions 12A supported as bearings 10 and 11, and is provided with a motor attaching surface 2B formed outside the housing 2. The connection groove 12B which opens to the outside is formed.

On the other hand, attachment and detachment of the electric motor 14 as the rotation driving source is freely attached to the motor attachment surface 2B by a fastening member (not shown). On the front end side of the motor shaft 14A of the electric motor 14, a flat protrusion connecting portion 14B is formed to fit the connecting groove 12B and transmit the rotation.

On the other hand, the end portion 12C opposite to the side where the coupling groove 12B of the input shaft 12 is formed protrudes from the outer side surface 2C opposite to the motor attachment surface 2B of the housing 2. This part is connected to the input shaft 12 of the linear actuator 1 and the other linear actuator of the same type via a shaft joint member, or when the power supply to the electric motor 14 is interrupted by a power failure or the like, the input shaft 12 is manually operated. It is used to connect an operating mechanism for rotating the shaft or a rotary encoder for indirectly detecting the lifted position of the screw shaft 6.

In addition, in the linear actuator 1 of the present invention, as the load torque acting on the driven helical gear 8 side when the electric motor 14 is stopped, the driving helical gear 13 side is prevented from rotating. To this end, the electric motor 14 is equipped with an electromagnetic brake that prevents the rotation of the motor shaft 14A when the current is cut off.

In addition, in this embodiment, the electromagnetic brake has a structure which can be opened manually so that the input shaft 12 can be rotated from the outside in case of power failure.

Next, operation | movement of the linear actuator 1 comprised as mentioned above is demonstrated. When the electric motor 14 is energized, the built-in electromagnetic brake (not shown) opens the motor shaft 14A, and the motor shaft 14A starts to rotate.

Rotation of the motor shaft 14A is transmitted to the input shaft 12, with which the drive helical gear 13 rotates. The rotation of the drive helical gear 13 is transmitted to the driven helical gear 8 engaged therewith by deflecting the direction of the rotation axis by 90 degrees, and the drive nut 5 integral with this rotates.

In this embodiment, the gear ratio between the drive helical gear 13 and the driven helical gear 8 is 1: 2, and the rotation speed of the input shaft 12 is decelerated to 1/2 to the drive nut 5. Delivered.

On the other hand, the screw shaft 6 screwed into the drive nut 5 restricts rotation around its central axis on the side of the load supporting member (not shown) attached to the connecting screw portion 7 at the upper end. When the driving nut 5 rotates in the forward or reverse direction, the driving nut 5 moves up or down in accordance with the rotational direction, and the weight supporting member supported by the load supporting member is lifted.

Next, Fig. 3 is a cross sectional view showing another embodiment of the linear actuator of the present invention, in which the linear actuator 1 'of this embodiment is not connected to the housing 2' by a rotation driving source such as an electric motor. End portions 12'C and 12'D on both sides of the input shaft 12 'protrude from both sides 2'B and 2'C of the housing 2, respectively.

The input shaft 12 'is freely supported on the housing 2' by the bearings 9 'and 10' on both sides of the drive helical gear 13 in the axial direction. In addition, the structure of the member etc. which are shown by the same number as FIG. 2 in FIG. 3 is the same structure as that of the Example shown in FIG. 1 and FIG. 2 mentioned above.

In the linear actuator 1 'of this embodiment, an electric motor provided independently on the linear actuator 1' on either or both of the ends 12'C, 12'D on both sides of the input shaft 12 '. The input shaft 12 'can be driven by connecting to a rotational drive such as a hydraulic motor.

In this case, an input shaft of another linear actuator of the same type as that of the linear actuator 1 is connected to the end of the input shaft 12 'of the side not connected to the rotary drive source, similarly to the linear actuator 1 of the above-described embodiment. Or a rotary drive for indirectly detecting the lift position of the screw shaft 6, or the like, when the rotary drive source cannot be driven by a power failure or the like, or manually rotating the input shaft 12 '. Used for.

In addition, in the present embodiment, for example, when a stage device or the like is operated by lifting three or more linear actuators 1 'together, the linear actuators 1' disposed between two linear actuators 1 'are lifted. ) Connects both ends 12'C and 12'D of the input shaft 12 'to the input shaft 12 of the adjacent two linear actuators 1' and the shaft coupling member, so that the adjacent linear actuators ( The lifting operation of the screw shafts 6 'can be synchronized with each other, and the number of rotation driving sources can be made smaller than that of the linear actuator 1'.

In addition, in the linear actuator of the present invention, each screw surface of the screw shaft and the driving nut can be formed by a square screw or an angled screw, as in the conventional linear actuator of this type, but in order to reduce power waste, A ball screw mechanism with a drive nut as the ball nut may be used.

In the case of using a ball screw mechanism, when the thrust load acting on the screw shaft is large, the helical gear with a small reduction ratio may be reversed without stopping, as in the case of using the worm reduction mechanism, 1 and 2 described above, it is preferable to use a rotation drive source such as an electric motor incorporating an electromagnetic brake or use a brake device for stopping the rotation of the input shaft.

In each of the above-described embodiments, the screw shaft is installed vertically in order to move the heavy object as a linear actuator. However, the screw shaft is installed in the horizontal or inclined direction, and the front end of the screw shaft is arm crane. It may be used to operate by connecting to a driven member such as a back.

In each of the embodiments, the driven helical gear and the driving helical gear are used in which each tooth is formed at a torsion angle of about 45 degrees in the same direction, but the torsion angles may be slightly different.

In such a case, the center axis line of the input shaft and the center axis of the driving nut or the screw shaft may not only be arranged three-dimensionally at right angles as in the case of using the worm reduction mechanism, but may also cross three-dimensionally at an angle, thereby rotating the rotation drive source in a horizontal position. Alternatively, the screw shaft can be moved forward and backward in the inclined direction as it is installed in the vertical position.

As described above, according to the invention of claim 1, it is possible to carry out the retraction operation of the screw shaft at a high speed and to select the reduction ratio in comparison with the conventional linear actuator using the reduction mechanism composed of the worm and the worm gear. It is possible to make it wider and to increase the transmission efficiency of the driving force.

Moreover, the linear actuator can be simply speeded up by using the housing of the linear actuator using the existing worm reduction mechanism.

In addition, since the engagement between the gears is continuously performed as compared with the use of the reduction mechanism constituted by the bevel gear, the engagement noise between the gears can be reduced, and the center axis of the input shaft can be arranged in the rotational surface of the driven helical gear. Therefore, unlike bevel gears that are engaged in a state where the central axis intersects in the same plane, the engagement of the helical gears allows the input shaft to protrude to both sides of the housing. By connecting the input shafts to the synchronous operation, or by connecting the rotary drive source to each of the protruding end of the both sides of the input shaft can be operated as a rotating drive source of small capacity.

In addition, in the case of manufacturing the helical gear, it is possible to lower the manufacturing cost without requiring any special equipment or mechanism, such as in the case of manufacturing the bevel gear, the interlocking teeth of the worm and the worm gear.

In addition, according to the invention of claim 2, since the driven helical gear and the driving helical gear can be formed at the same torsion angle in the same direction, the processing is easy and the productivity can be improved, and the manufacturing cost can be further reduced. have.

Claims (2)

A drive nut freely supported by the housing for rotation; A screw shaft which is screwed with the drive nut and linearly moves back and forth in the axial direction by rotation of the drive nut; A driven helical gear installed at the outer circumference of the drive nut to rotate integrally with this, An input shaft freely supported by the housing such that the drive nut and the central axis cross each other in three dimensions and rotated by a rotation driving source; And a drive helical gear installed on the input shaft so as to rotate integrally therewith, the drive helical gear being engaged with the driven helical gear to transmit rotation to the drive nut on the input shaft side. 2. The screw-driven linear actuator according to claim 1, wherein the driven helical gear and the driving helical gear are formed with each tooth having a twist angle of about 45 degrees in the same direction.