JP2014040857A - Linear actuator and classification method of linear actuator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a linear actuator that can obtain a desired thrust without increasing overall dimensions and without increasing the number of components.SOLUTION: A speed reducer 31 is interposed between a ball screw mechanism 2 and a servo motor 30, and a large thrust is obtained by the servo motor 30 having a small output capacity. When the diameter of an output shaft 31a of the speed reducer 31 and the diameter of a male screw 2a of the ball screw mechanism 2 are represented by D and d respectively, an equation D=d×K is satisfied (where K is 1 or more and 2 or less). If K is less than 1, it is difficult to obtain a necessary thrust because the output torque of the speed reducer 31 is too small. If K is more than 2, the whole linear actuator is upsized because it is necessary to upsize a coupling 21 and a coupling housing 20. When K is set to 1 or more and 2 or less, a desired thrust can be obtained without upsizing the linear actuator.

Description

  The present invention relates to a linear actuator that moves an object back and forth by a ball screw mechanism and a classification method of the linear actuator.

  In order to realize linear operations such as opening and closing of doors and raising and lowering of tables, linear actuators have been used. For example, Patent Document 1 discloses a linear actuator including a ball screw mechanism, a servo motor connected to the ball screw mechanism, and a rod coupled to a nut portion of the ball screw mechanism.

  The output shaft of the servo motor is connected to the male screw of the ball screw mechanism through a coupling. The coupling is housed in a coupling housing, and a motor flange is provided between the coupling housing and the servo motor to connect the two.

  The motor flanges are designed differently depending on the size or output capacity of the servo motor. When one servo motor is selected from a plurality of servo motors having different sizes or capacities and connected to one coupling housing, a motor flange corresponding to the selected servo motor is used.

  Therefore, any servo motor having a different size or output capacity can be connected to the coupling housing simply by changing the motor flange.

JP 2009-118624 A

  In order to increase the thrust of the linear actuator, it is necessary to increase the output capacity of the servo motor. However, when a servo motor with a large output capacity is used, the servo motor becomes larger, and accordingly, the motor flange, coupling, and coupling housing are also enlarged, and the entire linear actuator is enlarged.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a linear actuator capable of obtaining a desired thrust without enlarging the overall dimensions and a classification method of the linear actuator. To do.

  A linear actuator according to the present invention includes a motor, a speed reducer that decelerates rotation of the motor, and a male screw of a ball screw mechanism that is coupled to the output shaft of the speed reducer. D and the diameter d of the male screw satisfy D = d × K (where K is 1 or more and 2 or less).

  In the present invention, a reduction gear is interposed between the ball screw mechanism and the motor, and a large thrust is obtained with a motor having a small output capacity. When the diameter of the output shaft of the speed reducer is D and the diameter of the male screw of the ball screw mechanism is d, D = d × K (where K is 1 or more and 2 or less). When K is smaller than 1, the output torque of the reduction gear becomes too small and it becomes difficult to obtain a required thrust. When K is larger than 2, it is necessary to enlarge the coupling and the coupling housing, and the entire linear actuator increases in size. By setting K to 1 or more and 2 or less, the linear actuator can obtain a desired thrust without increasing its size.

  The linear actuator according to the present invention is characterized in that a reduction ratio of the reduction gear is 1/10 or more and 1/3 or less.

  In the present invention, the reduction ratio of the speed reducer is set to 1/10 or more and 1/3 or less to achieve both avoidance of enlargement and securing of thrust.

  The linear actuator classifying method according to the present invention is characterized in that the diameter d of the male screw is made to correspond to the diameter D of one or a plurality of the output shafts, and different codes are assigned according to the number of the corresponding diameters D. To do.

  In the present invention, when a series of linear actuators is created for each diameter d of the male screw, classifications are created according to the number of diameters D, and different codes are assigned to the created classifications for distinction.

  In the linear actuator according to the present invention, a reduction gear is interposed between the ball screw mechanism and the motor, and a large thrust is obtained with a motor having a small output capacity. Further, when the diameter of the output shaft of the speed reducer is D and the diameter of the male screw of the ball screw mechanism is d, the linear actuator is set so that D = d × K (where K is 1 or more and 2 or less). design. When K is smaller than 1, the output torque of the reduction gear becomes too small and it becomes difficult to obtain a required thrust. When K is larger than 2, it is necessary to enlarge the coupling and the coupling housing, and the entire linear actuator increases in size. By setting K to 1 or more and 2 or less, the linear actuator can obtain a desired thrust without increasing its size.

It is a plane sectional view which shows a straight line actuator roughly. It is a top view which shows schematically the linear actuator which uses another reduction gear.

Hereinafter, the present invention will be described in detail with reference to the drawings illustrating a linear actuator according to an embodiment. FIG. 1 is a plan sectional view schematically showing a linear actuator.
The linear actuator accommodates the ball screw mechanism 2 and the rod 3, the frame 1 extending in the moving direction of the ball screw mechanism 2, the servo motor 30 that supplies power to the ball screw mechanism 2, and the rotation of the servo motor 30 , A coupling 21 that couples the reduction gear 31 and the ball screw mechanism 2, and a coupling housing 20 that houses the coupling 21.

  The frame 1 has openings 1a and 1b at both ends. A male screw 2 a of the ball screw mechanism 2 is provided in the frame 1 along the longitudinal direction of the frame 1. A large diameter portion 2c is formed in the middle of the male screw 2a. A nut portion 2b is screwed to one end portion side of the male screw 2a via a rolling element (not shown). The nut portion 2 b is provided with a rod 3 extending along the longitudinal direction of the frame 1, and the rod 3 protrudes from one opening 1 a of the frame 1. The other end of the male screw 2 a protrudes from the other opening 1 b of the frame 1.

  A guide ring 4 for guiding the rod 3 is fitted in the one opening 1a. The rod 3 is slidably fitted to the guide ring 4. A bearing housing portion 10 for housing the bearing 13 is provided in the other opening 1b. The bearing accommodating portion 10 includes a cylindrical portion 11 having stepped holes 11 a and 11 a at both end portions, and a flange portion 12 that protrudes radially outward from an outer surface in a middle portion of the cylindrical portion 11.

  Bearings 13 and 13 are fitted in both ends of the cylindrical portion 11, respectively, and the bearings 13 and 13 are locked to the step portions of the stepped holes 11a and 11a. The cylinder portion 11 fixes the outer rings of the bearings 13 and 13. The aforementioned large-diameter portion 2 c is in contact with one end portion of the cylindrical portion 11. A fixing ring 14 for fixing the bearing 13 to the stepped hole 11 a is provided at the other end portion of the cylindrical portion 11. The inner rings of the bearings 13 and 13 are fixed by the fixing ring 14 and the large diameter portion 2c.

  One end portion of the cylindrical portion 11 is fitted into the other opening 1 b of the frame 1. The male screw 2a protruding from the frame 1 is rotatably fitted in a bearing 13 accommodated in the cylindrical portion 11, and its tip portion protrudes from the fixing ring 14 in the axial length direction. The flange portion 12 and the frame 1 are bolted.

  The speed reducer 31 has a cylindrical shape, and the output shaft of the servo motor 30 is connected to the input side (one end side) of the speed reducer 31. The servo motor 30 and the speed reducer 31 are unitized. The reduction gear 31 houses a planetary gear, and an output shaft 31 a protrudes from the output side (the other end side) of the reduction gear 31. The rotation of the servo motor 30 is decelerated by the speed reducer 31 and is output from the output shaft 31a. The reduction gear 31 is not limited to one using a planetary gear, and a parallel shaft gear reduction gear, a worm reduction gear, a bevel gear reduction gear, a helical reduction gear, a hypoid reduction gear, a ball reduction gear, a roller reduction gear, or the like is used. Also good. The output shaft 31a of the speed reducer 31 may be a solid shaft or a hollow shaft.

  The coupling housing 20 has a cylindrical shape having openings 20a and 20b at both ends. The coupling housing 20 accommodates a cylindrical coupling 21 that can rotate about an axis. A coupling ring 22 that couples the speed reducer 31 is fitted in one opening 20 a of the coupling housing 20. The output side of the reduction gear 31 is fitted into the connecting ring 22, and the output shaft 31 a is fitted into one end of the coupling 21.

  The other end portion of the cylindrical portion 11 is fitted in the other opening 20 b of the coupling housing 20. The coupling housing 20 is bolted to the flange portion 12. The tip of the male screw 2 a protruding from the fixing ring 14 is fitted into the other end of the coupling 21. The output shaft 31 a of the speed reducer 31 and the end of the male screw 2 a are connected via a coupling 21.

  The rotation of the servo motor 30 is decelerated by the speed reducer 31 and is output from the output shaft 31a. The rotation of the output shaft 31a is transmitted to the male screw 2a, and the nut portion 2b reciprocates in the axial direction by the rotation of the male screw 2a. The rod 3 provided on the nut portion 2 b advances from the frame 1 or retreats into the frame 1. Since the speed reducer 31 is interposed between the ball screw mechanism 2 and the servo motor 30, a large thrust can be obtained with the servo motor 30 having a small output capacity.

As shown in FIG. 1, when the diameters of the output shaft 31a fitted into the coupling 21 and the end of the male screw 2a are D and d, respectively, both satisfy the following relationship.
D = d × K (where K is 1 or more and 2 or less)

  When K is smaller than 1, the output torque of the speed reducer 31 becomes too small, and it becomes difficult to obtain the necessary thrust. When K is larger than 2, it is necessary to enlarge the coupling 21 and the coupling housing 20, and the entire linear actuator increases in size. By setting K to 1 or more and 2 or less, the linear actuator can obtain a desired thrust without increasing its size.

  In addition, since D only needs to satisfy the above-described relationship, the diameter D of one or more output shafts 31a can correspond to one diameter d. Therefore, for example, as shown in Table 1 below, linear actuators can be classified. In Table 1, d1 <d2 <d3 and D1 <D2 <D3 <D4 <D5. Further, in the column D, the portion with ◯ indicates Dn corresponding to dn (n = 1, 2,...), And the portion with − indicates Dn that does not correspond.

  As shown in Table 1, D1 corresponds to d1, D2 and D3 correspond to d2, and D3 to D5 correspond to d3. The numbers of Dn corresponding to dn are 1 to 3, respectively, and series 1 to series 3 (symbols) are assigned as classifications according to the number of corresponding diameters D.

  Since different codes are assigned, the user can easily grasp the number of diameters D of the output shaft 31a that can be handled in each series indicated by the codes. As described above, since the servo motor 30 and the speed reducer 31 are unitized, the number of diameters D of the output shaft 31a that can be handled also means the number of servo motors 30 that can be handled. The diameter of the output shaft 31 a corresponds to the output capacity of the servo motor 30. Therefore, the user can easily grasp the number of servo motors 30 having different output capacities and corresponding to the diameter d by the code. The code is attached to, for example, a linear actuator or listed in a pamphlet.

  The dimensions of the frame 1 are affected by the diameter d of the male screw 2a. As described above, the number of the diameters D of the output shaft 31a corresponding to the diameter d of the male screw 2a is limited (in other words, the number of the speed reducers 31 is limited). The speed reducer 31 is limited so that it can be combined with the common frame 1. As a result, it is possible to share components such as the frame 1 while ensuring the necessary thrust.

  Series 1 to Series 3 are merely examples of symbols, and other symbols such as hiragana, alphabet, kanji, symbols, symbols, or marks may be used.

  The reduction gear 31 is not limited to a linear shape. FIG. 2 is a plan view schematically showing a linear actuator using another speed reducer. As shown in FIG. 2, the linear actuator may use a speed reducer 32 having an L shape in plan view. The reduction gear 32 includes a planetary gear and a bevel gear, and the input direction and the output direction of the reduction gear 32 are substantially orthogonal. Convenience can be improved by changing the reduction gears 31 and 32 used according to installation space. Note that a reduction gear 32 combining a gear and a belt may be used.

  Also in this case, the diameter D of the output shaft of the speed reducer 32 and the diameter d of the end of the male screw 2a satisfy the relationship D = d × K (where K is 1 or more and 2 or less), and the linear actuator is large. It is possible to obtain a desired thrust without being converted.

  Although the linear actuator according to the embodiment uses the servo motor 30, another motor such as a stepping motor may be used.

  It should be thought that embodiment disclosed this time is an illustration and restrictive at no points. The scope of the present invention is intended to include all modifications within the scope of the claims and the scope equivalent to the scope of the claims.

DESCRIPTION OF SYMBOLS 1 Frame 2 Ball screw mechanism 2a Male screw 2b Nut part 3 Rod 10 Bearing accommodating part 13 Bearing 20 Coupling housing 21 Coupling 30 Servo motor (motor)
31, 32 Reducer 31a Output shaft

Claims (3)

In a linear actuator comprising a motor, a speed reducer that decelerates rotation of the motor, and a male screw of a ball screw mechanism connected to the output shaft of the speed reducer,
The diameter D of the output shaft and the diameter d of the external thread are:
D = d × K (where K is 1 or more and 2 or less)
A linear actuator characterized by satisfying The reduction gear ratio of the reduction gear is 1/10 or more and 1/3 or less. A method for classifying linear actuators according to claim 1 or 2,
A method for classifying linear actuators, wherein a diameter D of one or a plurality of the output shafts is made to correspond to a diameter d of the male screw, and a different code is assigned according to the number of the corresponding diameters D.

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