JP2000257689A - Screw-driven linear working machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a screw-driven linear working machine capable of performing the quiet and high-speed operation and having small power loss. SOLUTION: A screw-driven linear working machine is provided with a drive nut 5 rotatably supported on a housing 1, a screw shaft 6 to be axially and linearly reciprocated by the rotation by being screwed with the drive nut, a driven helical gear 8 provide on the outer periphery of the drive nut 5 so as to be integrally rotated together with it, an input shaft 12 rotatably supported on the housing 2 so that its central axis may intersect with the central axis of the drive nut 5 each other, and to be rotated by a rotational driving source, and a driving helical gear 13 provided so as to be integrally rotated together with it and for transmitting the rotation from the input shaft 12 side to the drive nut 5 by being meshed with the driven helical gear 8.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a screw driven linear actuator used for lifting and lowering heavy objects, and more particularly to a linear actuator for moving a screw shaft forward and backward at a high speed.

[0002]

2. Description of the Related Art Conventionally, screw driven linear actuators have been widely used for lifting and lowering heavy objects. FIG. 4 and FIG.
This shows an example of a conventional screw-driven linear actuator having a built-in worm reduction mechanism, in which a drive nut A4 is rotatably supported by bearings A2 and A3 in a housing A1. Are screwed together with the screw shaft A5 restricted in rotation with respect to the housing A1 side.

A worm wheel A6 is integrally formed on the outer periphery of the drive nut A4.
Is engaged with a worm A10 provided on an input shaft A9 rotatably supported by bearings A7 and A8 in a housing A1.

When the input shaft A9 is connected to a rotary drive source (not shown) and driven to rotate, the worm A1
The rotation is transmitted to the drive nut A4 via the worm wheel A6 and the worm wheel A6, and the screw shaft A5 is driven forward and backward in the axial direction.

[0005] At the tip of the screw shaft A5, there is formed a connecting screw portion A11 connected to a load supporting member (not shown), and a thrust load transmitted to the screw shaft A5 via the connecting screw portion A11 is applied to the screw shaft A5. It is adapted to be supported by the mating drive nut A4.

FIGS. 6 and 7 show an example of a screw-driven linear actuator incorporating a bevel gear reduction mechanism, which is driven in a housing B1 by driven bevel gears B2 and B2.
The holding cylinder B3 and the driving nut B4 are coaxially and integrally connected, and the holding cylinder B3 and the boss B5 of the driven bevel gear B2 are rotatably held in the housing B1 by bearings B6 and B7, respectively.

A screw shaft B8 extends through the driven bevel gear B2, the holding cylinder B3, and the central axis of the boss B5 of the drive nut B4, and the screw shaft B8 is
It is screwed to the drive nut B4, and is provided so as to be able to advance and retreat in the axial direction in a state where the rotation is restricted with respect to the housing B1 side.

An input shaft B9 is mounted on the housing B1 so that the central axis is orthogonal to the screw shaft B8.
A drive bevel gear B12 meshing with the driven bevel gear B2 is fixed to an end of the input shaft B9 in the housing B1.

When the input shaft B9 is connected to a rotary drive source (not shown) and driven to rotate, similarly to the above-described screw-driven linear actuator having a built-in worm speed reduction mechanism, the rotation is transmitted from the drive bevel gear B12. The transmission is transmitted to the driven bevel gear B2, the drive nut B4 is rotated, and the screw shaft B8 is driven forward and backward in the axial direction.

Then, the connecting screw portion B at the tip of the screw shaft B8
The lifting / lowering operation of a heavy object is performed via a load support member (not shown) connected to the load 13.

[0011]

In a conventional screw-driven linear actuator as described above, the one using a worm speed reduction mechanism has a large reduction ratio between the worm and the worm wheel. It is not suitable when it is necessary to move the screw shaft at high speed, and in order to move the screw shaft at high speed, it is necessary to increase the number of revolutions on the input shaft side. In this case, there is a problem that the transmission efficiency is low due to a large relative slip amount between the meshing teeth, and a large power loss occurs.

[0012] In the case of using the bevel gear reduction mechanism,
The reduction ratio between the driving bevel gear and the driven bevel gear is relatively small,
Although the screw shaft can move forward and backward at high speed, the noise of meshing between these bevel gears during operation becomes large, and it is difficult to use it for elevating and lowering stage equipment, especially when low noise is an absolute condition. was there.

In a linear actuator using a bevel gear reduction mechanism, the screw shaft and the central axis of the input shaft are orthogonal to each other, so that the input shaft can be protruded from only one side of the housing due to its structure. As with the worm reduction mechanism, the input shaft protrudes from both sides of the housing, one protruding end of the input shaft is connected to the rotary drive source, and the other protruding end is connected to the input shaft of another linear actuator. However, there is a problem that a plurality of linear actuators can be synchronously driven by a common rotary drive source, or the drive sources cannot be connected to the projecting ends on both sides of the input shaft for use. Was.

Further, in the case of using the worm speed reduction mechanism or the bevel gear speed reduction mechanism as described above, since the worm, worm wheel or bevel gear tooth cutting is troublesome, the production cost is increased. there were.

Although not shown, an input shaft and a screw shaft are arranged in parallel at adjacent positions, and a cylindrical gear such as a spur gear or a helical gear is provided on the input shaft and a drive nut screwed to the screw shaft, respectively. A linear actuator having a speed reduction mechanism configured by meshing them has been conventionally manufactured.However, in such a linear actuator, the degree of freedom in the arrangement of the rotary drive source is limited, and a plurality of linear actuators of the same type are used. There has been a problem that it is difficult to connect and synchronously drive.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems in the prior art and to provide a screw-driven linear actuator capable of performing a quiet and high-speed operation and having a small power loss. I do.

[0017]

To achieve the above object, a linear actuator according to the present invention comprises a drive nut rotatably supported by a housing, and a screw engaged with the drive nut. Screw shaft that moves linearly forward and backward in the direction, a driven helical gear provided on the outer periphery of the drive nut so as to rotate integrally with it, and the housing is rotatable so that the drive nut and the center axis cross three-dimensionally. An input shaft that is supported by and is rotated by a rotary drive source, and a drive helical gear that is provided on the input shaft so as to rotate integrally therewith, meshes with the driven helical gear, and transmits rotation from the input shaft to the drive nut. It is provided with.

The driven helical gear and the driven helical gear preferably have respective tooth traces formed in the same direction with a twist angle of approximately 45 degrees.

[0019]

When the input shaft is rotated by a rotary drive source such as an electric motor, the drive helical gear provided on the input shaft rotates integrally therewith, and the rotation is driven via the driven helical gear meshing with the drive helical gear. It is transmitted to the nut.

The rotation of the drive nut causes the screw shaft to advance and retreat in the axial direction. A heavy object is placed on the upper end of the vertically oriented screw shaft to lift and lower it, or
The screw shaft is installed in a desired direction, and the driven member connected to the tip can be moved forward and backward.

Since the drive nut is driven to rotate by the engagement between the drive helical gear and the driven helical gear,
The reciprocating operation of the screw shaft is performed at a higher speed as compared with a linear actuator using a worm reduction mechanism.

Similarly to the mesh between the worm and the worm wheel, the two helical gears are continuously meshed with each other while sliding with each other to transmit power from the input shaft to the drive nut. The generated meshing sound is small.

[0023]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a longitudinal sectional view showing one embodiment of the linear actuator of the present invention, and FIG. 2 is a transverse sectional view taken along the line AA in FIG. Actuator 1
A drive nut 5 is rotatably supported in the housing 2 by bearings 3 and 4, and a screw shaft 6 is screwed through the drive nut 5.

The linear actuator 1 of this embodiment is installed with the screw shaft 6 set vertically for use in lifting and lowering heavy objects. A connection screw portion 7 for attaching a load supporting member (not shown) for performing the operation is provided.

The lower portion of the screw shaft 6 is accommodated in a cylindrical screw shaft cover 2A provided below the housing 2.

On the outer periphery of the drive nut 5, a driven helical gear 8 having a torsion angle of the tooth trace T (the angle between the center axis direction of the drive nut 5 and the direction of the tooth trace T) of 45 degrees is integrally formed. I have.

The helical gear 8 is engaged on both sides with a pair of drive helical gears 13 provided on an input shaft 12 rotatably supported by bearings 9 and bearings 10 and 11 in the housing 2.

The driving helical gear 13 has a tooth trace t twisted at a twist angle of 45 degrees in the same direction as the driven helical gear 8.
, And the input shaft 12 is arranged so that the central axes of the two intersect three-dimensionally at an angle of 90 degrees.

The input shaft 12 has a motor mounting surface 2 formed at an end 12 A supported by bearings 10 and 11, which crosses the input shaft 12 in the diameter direction and is formed outside the housing 2.
A connection groove 12B opening outside B is formed.

On the other hand, an electric motor 14 as a rotary drive source is detachably mounted on the motor mounting surface 2B by a fastening member (not shown). The connecting groove 1 is provided at the distal end side of the motor shaft 14A of the electric motor 14.
A flat tongue-shaped connecting portion 14B is formed to fit the 2B and transmit the rotation.

On the other hand, an end 12C of the input shaft 12 opposite to the side where the connection groove 12B is formed projects from an outer surface 2C of the housing 2 opposite to the motor mounting surface 2B. The input shaft of another linear actuator of the same type as the linear actuator 1 is connected via a shaft coupling, or the electric motor 1
When the power to power supply 4 is cut off due to a power failure or the like, input shaft 1
2 is used to connect an operating mechanism for rotating the rotary shaft 2 or a rotary encoder for indirectly detecting the elevation position of the screw shaft 6.

In the linear actuator 1 of the present invention,
In order to prevent the drive helical gear 13 from rotating due to the load torque acting from the driven helical gear 8 when the electric motor 14 is stopped, the electric motor 14 is prevented from rotating the motor shaft 14A when the power is cut off. The built-in electromagnetic brake.

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

Next, the operation of the linear actuator 1 configured as described above will be described. When the electric motor 14 is energized, a built-in electromagnetic brake (not shown) opens the motor shaft 14A, and the motor shaft 14A starts rotating.

The rotation of the motor shaft 14A is transmitted to the input shaft 12, and the driving helical gear 13 rotates together therewith.
The rotation of the driving helical gear 13 is transmitted to the driven-side helical gear 8 meshing with the driving helical gear 8 by deflecting the direction of the rotation axis by 90 degrees, and the driving nut 5 integrated therewith is rotated.

In this embodiment, the driving helical gear 1
The ratio of the number of teeth between the gear 3 and the driven helical gear 8 is 1: 2, and the rotation speed of the input shaft 12 is reduced to １ ／ and transmitted to the drive nut 5.

On the other hand, the screw shaft 6 screwed to the drive nut 5 is restricted from rotating around its central axis from the load support member (not shown) attached to the connecting screw portion 7 at the upper end. Therefore, when the drive nut 5 rotates in the forward direction or the reverse direction, the drive nut 5 moves up or down in accordance with the rotation direction, and the weight supporting member supported by the load supporting member moves up and down.

FIG. 3 is a cross-sectional view showing another embodiment of the linear actuator of the present invention. The linear actuator 1 'of this embodiment has an electric motor or the like mounted on its housing 2'. The rotary drive source is not connected, and both ends 12 ′ C, 12 ′ D of the input shaft 12 ′ are on both side surfaces 2 ′ of the housing 2.
B, protruding from 2'C.

The input shaft 12 'is rotatably supported on the housing 2' by bearings 9 'and 10' on both axial sides of the drive helical gear 13. The other components such as the members indicated by the same reference numerals in FIG. 3 as those in FIG. 2 have the same structures as those in the embodiment shown in FIGS. 1 and 2 described above.

In the linear actuator 1 'of this embodiment,
Either one or both ends 12'C and 12'D of the input shaft 12 'are connected to a rotary drive source such as an electric motor or a hydraulic motor installed independently of the linear actuator 1'. Thus, the input shaft 12 'can be driven, and can be installed with a high degree of freedom.

In this case, another end of the input shaft 12 'which is not connected to the rotary drive source is connected to another end of the same type as the linear actuator 1', similarly to the linear actuator 1 of the above-described embodiment. An operation mechanism for manually connecting the input shaft of the linear actuator or rotating the input shaft 12 ′ when the rotary drive source cannot be driven due to a power failure or the like, or indirectly changing the vertical position of the screw shaft 6. It is used to connect a rotary encoder or the like for detection.

In addition, according to the present embodiment, for example, when a stage device or the like is moved up and down in cooperation with three or more linear actuators 1 ′, it is disposed between the two linear actuators 1 ′. The linear actuator 1 ′ is connected to both ends 1 of the input shaft 12 ′.
2′C and 12′D are connected to the input shaft 12 of both adjacent linear actuators 1 ′ by shaft couplings, respectively, so that the vertical movement of the screw shaft 6 between the adjacent linear actuators 1 ′ can be synchronized, There is an advantage that the number of rotary drive sources can be smaller than the number of linear actuators 1 '.

In the linear actuator according to the present invention, the respective screw surfaces of the screw shaft and the drive nut can be formed by trapezoidal screws or square screws, similarly to this type of conventional linear actuator. In order to reduce power loss, a ball screw mechanism using a drive nut as a ball nut may be used.

When a ball screw mechanism is used,
When the thrust load applied to the screw shaft is large, in the case of a helical gear having a small reduction ratio, the input shaft may reverse without self-locking as in the case of using a worm reduction mechanism. Also, as in the embodiment shown in FIG. 2, it is preferable to use a rotation drive source such as an electric motor having a built-in electromagnetic brake or to use a brake device for stopping the rotation of the input shaft.

Further, in each of the above-mentioned embodiments, the screw shaft is installed and used vertically in order to lift and lower a heavy object by the linear actuator. However, the screw shaft is oriented horizontally or obliquely. It may be installed and used to operate by connecting the tip of the screw shaft to a driven member such as an arm crane.

In each of the embodiments, the driven helical gear and the driving helical gear are formed such that their tooth traces are formed with a helix angle of approximately 45 degrees in the same direction. It may be slightly different.

In this case, the center axis of the input shaft and the center axis of the drive nut or the screw shaft are not only arranged so as to intersect at right angles as in the case of using a worm reduction mechanism, but also obliquely intersect at an angle. It is also possible to move the screw shaft in a diagonal direction while the rotary drive source is installed in a horizontal posture or a vertical posture.

[0048]

As described above, according to the first aspect of the present invention, the advancing and retreating operation of the screw shaft can be performed at a higher speed as compared with a conventional linear actuator using a reduction mechanism constituted by a worm and a worm gear. In addition to the above, the selection range of the reduction ratio can be widened, and the transmission efficiency of the driving force can be increased.

Furthermore, the speed of the linear actuator can be easily increased by diverting the housing of the linear actuator using the existing worm reduction mechanism.

Further, as compared with the case using a reduction mechanism constituted by bevel gears, the meshing between the gears is performed continuously, so that the meshing noise between the gears can be reduced and the center axis of the input shaft can be reduced. Can be arranged in the rotating surface of the driven helical gear, so that it can be made compact and, unlike the bevel gears that mesh with the center axes intersecting in the same plane, the input shaft of the housing is engaged with the meshing of the helical gears. Since it can be protruded on both sides, multiple linear actuators can be operated synchronously by connecting the input shafts to each other, or a small-capacity rotary drive can be made by connecting a rotational drive source to each of the protruding ends on both sides of the input shaft. Can be operated with a source.

Furthermore, when manufacturing a helical gear, no special equipment or tools are required as in the case of manufacturing a bevel gear, a worm and meshing teeth of a worm gear, and the manufacturing cost can be reduced.

According to the second aspect of the present invention, since the driven helical gear and the driving helical gear can be formed with the same twist angle in the same direction, machining can be facilitated, productivity can be improved, and manufacturing costs can be further reduced. Can be lowered.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing one embodiment of a linear actuator according to the present invention.

FIG. 2 is a cross-sectional view as viewed in the direction of the arrow from the position of line AA in FIG.

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

FIG. 4 is a vertical sectional view showing an example of a conventional screw-driven linear actuator incorporating a worm speed reduction mechanism.

FIG. 5 is a transverse cross-sectional view taken in the direction of the arrow from the position of line BB in FIG. 4;

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

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

[Explanation of symbols]

 1,1 'linear actuator 2,2' housing 2A screw shaft cover 2B motor mounting surface 2C, 2'B, 2'C outer surface 3,4,9,10,11,9'10 'bearing 5 drive nut 6 Screw shaft 7 Connecting screw portion 8 Driven helical gear 12, 12 'Input shaft 12A, 12C, 12'C, 12'D End 12B Connecting groove 13 Drive helical gear 14 Electric motor (rotation drive source) 14A Motor shaft 14B Tongue piece Connection part T, t Tooth muscle

Claims (2)

[Claims] A drive nut rotatably supported by a housing; a screw shaft screwed with the drive nut and linearly moving forward and backward in the axial direction by rotation of the drive nut; A driven helical gear provided to rotate integrally, an input shaft rotatably supported by a housing such that a drive nut and a central axis intersect three-dimensionally, and rotated by a rotary drive source; and the input shaft And a drive helical gear that is provided so as to rotate integrally with the drive helical gear, and that meshes with the driven helical gear to transmit rotation from the input shaft side to the drive nut. 2. The screw driven linear actuator according to claim 1, wherein the driven helical gear and the driving helical gear have respective tooth traces formed in the same direction with a twist angle of approximately 45 degrees.