JP2007046734A - Linear actuator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a linear actuator generating high linear motion output from small input torque by conversion into linear motion through a differential mechanism, in particular, without using a specific (expensive) machine element, and performing precise positioning by proportionally converting rotational quantity into linear motion. <P>SOLUTION: In this linear actuator, two supporting members 2, 3 are provided with two rotating shafts 4 and one moving shaft 5 in parallel with each other, the rotating shafts 4 have first gears 12 and second male screw portions 13, and the moving shaft 5 has a second gear 14, a first male screw portion 15, and a head portion 28, and is provided with a moving member 6 relatively movable to the supporting members 2. The axial moving quantity of the moving shaft 5 is equal to the difference between a moving distance of the moving member 6 and the moving shaft 5 in one axial direction x in accompany with the rotation of the rotating shafts 4, and a moving distance in the axial direction y opposite to the axial direction x, of the moving shaft 5 to the moving member 6 by rotation of the moving shaft 5 when the rotation of the rotating shafts 4 is transmitted to the moving shaft 5 through first and third transmitting means 12, 14. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a linear actuator, and in particular, uses a rotational force of an electric motor or the like as a power source and converts it into a linear motion via a differential mechanism without using special (expensive) mechanical elements, thereby reducing a small input torque. A large linear motion output is generated, and the amount of rotation is proportionally converted to linear motion to accurately position the machine, and it is necessary to completely stand still. The present invention relates to a linear motion mechanism that can be used for a manipulator device that requires a linear force greater than that of a component, taking advantage of the ability to reduce the size of an object moving device and the like.

Conventionally, as a linear motion force generating mechanism in a material testing machine or a heavy machine, when a required force is very large, a hydraulic cylinder is used, while a required force may be relatively small. In some cases, a combination of a screw and nut, a gear, a link, etc. is generally used as a mechanism for converting the rotational motion into a linear motion. In particular, the latter is further classified as follows.
(1) A combination of screws and nuts directly (2) A differential screw mechanism (3) A rack and pinion mechanism (4) A worm mechanism (5) A crank mechanism (6) Using a pantograph mechanism

  First, hydraulic cylinders are widely used in large-scale material testing machines and heavy equipments because a large load of several hundred kN or more can be generated by increasing the cylinder diameter. However, the hydraulic cylinder has the disadvantage that it is very difficult to control the displacement. Further, when the displacement is stopped, the oil leakage from the cylinder packing cannot be completely prevented due to the mechanism of the hydraulic cylinder, so the load gradually decreases. Further, in the material test, when the stress in the test material is reduced due to a creep phenomenon or the like when the displacement is stopped, the stop position is changed accordingly.

  For this reason, in material tests that require precise displacement control, as described in the previous section (1), a screw is rotated by the power of a motor or the like, and a crosshead with a nut screwed to the screw is attached. In many cases, a mechanism is used that moves the head and converts it into linear motion (FIG. 1). However, in the apparatus using the screw and nut of the preceding item (1), it is necessary to decelerate using a gear box having a large volume in order to convert a small rotational torque into a large linear motion force. Further, in order to obtain a large linear motion force, it is necessary to use a thick screw. However, since the pitch increases as the screw becomes thicker, precise displacement control becomes difficult. That is, it is difficult for the device of the above item (1) to achieve both a large linear motion force and precise displacement control.

  Similarly, the advantages and disadvantages of the mechanisms described in the preceding items (2) to (6) using screws, gears, etc. will be described.

  As shown in FIG. 2, the apparatus using the differential screw mechanism of the previous item (2) has different pitches of the two screw portions, so that when these screw portions are simultaneously rotated, The distance between the attached needles can be precisely changed, and as a result, the rotation can be converted into a minute linear motion. However, in this method, in order to take out the difference of the relative linear amount of movement, all the needles move with respect to the screw shaft to be rotated, and it is difficult to incorporate them into the apparatus. In addition, in order to combine screws having different pitches, a complicated process in manufacturing is required. Furthermore, the maximum linear motion force depends on the screw having the smaller pitch, and there is a problem that the practical strength of the screw thread is lowered by the smaller pitch.

  The apparatus using the rack and pinion mechanism of the preceding item (3) is widely used when roughly moving a relatively light object as shown in FIG. Although it is common as a mechanism for converting rotational motion into linear motion, the gear meshing region is limited to a small size, and therefore is not suitable for use in transmitting a large force.

  As shown in FIG. 4, the device using the mechanism combining the worm gear and the screw of the preceding item (4) actually uses a mechanism for converting rotational motion into linear motion. The advantages of the worm gear are that a large reduction ratio can be obtained compared to a spur gear and that the holding force at the time of stopping is large. However, since the worm gear is in sliding contact and easily generates heat, the wear easily progresses and the backlash increases. Moreover, since mechanical efficiency is low, it has the fault that load capacity is small compared with a spur gear. Furthermore, when trying to downsize the device, the meshing of the worm gear is reduced, so that the strength and durability are lowered.

  The device using the crank mechanism of the previous section (5) has been used for a long time as a mechanism for converting rotational motion into reciprocating linear motion, and is most widely used as a compression force transmission mechanism of a press machine (FIG. 5). . However, in the device of the preceding item (5), the force that can be generated varies depending on the stroke position due to its mechanism, and the applied pressure becomes the smallest at the center of the stroke. That is, it is not suitable for the purpose of stopping or shifting in the middle of a stroke, and displacement control is difficult.

  As shown in FIG. 6, the apparatus using the pantograph mechanism of the preceding item (6) has the advantages that the number of parts is small and a large linear motion force can be obtained without using a special speed reduction mechanism. However, in the device of the above item (6), since the rotation amount and the linear displacement are not proportional, it is difficult to perform precise displacement control.

  For this reason, the present inventors have studied to achieve both a large linear motion force and precise displacement control using a differential screw mechanism.

  For example, Patent Document 1 discloses an input shaft, an intermediate shaft having two screw portions, an output shaft that is arranged in parallel with the intermediate shaft and has a screw portion at a part of the shaft, and one screw of the intermediate shaft. It is described that a displacement is controlled using a differential action of two screw portions, which includes a nut that is screwed to a screw portion and a column that connects a nut screwed to a screw portion of an output shaft.

  The displacement control method described in Patent Document 1 generates a differential action due to a difference in lead between two screw portions provided on the same rotation shaft (intermediate shaft). It is a mechanism, and is not a mechanism that converts rotational torque into linear motion force.

  In addition, Patent Document 2 describes a sub-micromanipulator for performing linear fine displacement using a differential lever and positioning with high accuracy. In order to achieve precise linear motion, A linear motion lever having a gear with a large radius and a worm with a small pitch are required, resulting in a complicated configuration.

  Further, Patent Document 3 has a configuration in which an intermediate actuator member is mounted between the housing and the drive sleeve, and the rotation is converted into linear motion by a screw mechanism, and the linear momentum is proportional to the rotation amount. Although a differential linear actuator that can be changed is described, the intermediate actuator member has a complicated configuration and has a problem that it is difficult to process.

  Furthermore, Patent Document 4 has a configuration in which the rotational drive motion of the planetary gear transmission is converted into a linear motion, and the movement output ratio of the input linear motion is changed by changing the number of gear teeth and the screw pitch. The brake operation device is described in which the linear movement amount can be changed proportionally with respect to the rotation amount. However, since this brake device requires two electric motors, the size of the device can be reduced. There is a problem that it is difficult to reduce the weight and weight.

In addition, Patent Document 5 includes a base, a support plate, a movable body, a main shaft motor, a screw shaft, a differential cylinder having a first screw, a second screw, and a differential cylinder as a support plate and a screw shaft. And a press device provided with a differential mechanism that moves the differential cylinder up and down relative to the support plate together with the screw shaft by rotation of the motor. One motor is required, which is disadvantageous in terms of downsizing and weight reduction of the apparatus.
JP 59-77162 A JP 61-131882 A JP-A-6-323394 JP 2000-507332 A JP 2005-66652 A

  An object of the present invention is to convert a small input torque to a large linear force by converting a linear motion through a differential mechanism without using special (expensive) mechanical elements, particularly using a rotational force of an electric motor or the like as a power source. Workpiece moving device in material testing machines, precision hoisting machines, and cutting machines that need to be positioned precisely by generating motion output and converting the amount of rotation to linear motion proportionally and completely stationary Further, it is to provide a linear actuator that can be miniaturized.

In order to achieve the above object, the gist of the present invention is as follows.
(I) The at least one support member is provided with at least one rotating shaft that is rotatably supported and at least one moving shaft that is rotatably supported in the axial direction,
The rotation shaft has first transmission means on at least one side thereof, and has a second transmission means that rotates in the same direction together with the first transmission means at a predetermined portion of the rotation shaft,
The moving shaft has, on at least one side thereof, third transmitting means that engages with the first transmitting means provided on the rotating shaft, and a first male screw that rotates in the same direction together with the third transmitting means on a predetermined portion of the moving shaft Having a head part that performs positioning control in the axial direction at the tip,
At least a first female screw hole into which the first male screw portion of the moving shaft is screwed and a fourth transmission means for linking operation with the second transmission means of the rotating shaft, and relative movement with respect to the support member along the first male screw portion Providing at least one moving member capable of
The amount of movement of the moving shaft in the axial direction is determined by the distance traveled in one axial direction of the moving member and the moving shaft accompanying the rotation of the rotating shaft, and the rotation of the rotating shaft transmitted to the moving shaft through the first and third transmission means. A linear actuator characterized in that a difference between a moving axis and a distance that the moving axis moves in an axial direction opposite to the one axial direction with respect to the moving member by rotating the moving axis.

(II) The linear actuator according to (I), wherein the first and third transmission means are both gears.

(III) The rotating shaft and the moving shaft are arranged in parallel, the second transmission means is a second male screw portion, and the fourth transmission means is a second female screw hole.・ Actuator.

(IV) The amount of axial movement of the head portion of the moving shaft is determined by the pitch ratio of the first and second male screw portions and the tooth number ratio of the first and third transmission means.・ Actuator.

(V) The second male screw portion of the rotating shaft is formed of a right screw or a left screw, the first male screw portion of the moving shaft is formed of a screw opposite to the second male screw portion, and the first transmission means is integrated. When rotating in the direction, the rotating shaft co-rotates with the first transmission means to advance the moving member, and the moving member moves in the direction of moving the moving shaft forward along the second male screw portion of the rotating shaft. The third transmission means rotates in the direction opposite to the first transmission means in the engaging operation with the first transmission means, and the moving shaft is configured to move in the direction opposite to the moving direction of the moving member. Linear actuator as described in (III) or (IV).

(VI) Fifth transmission means in which the second male screw portion of the rotating shaft and the first male screw portion of the moving shaft are both formed by right-hand threads, and engage with and operate between the first transmission means and the third transmission means. When the first transmission means is rotated in one direction, the rotation shaft co-rotates with the first transmission means to advance the moving member, and the moving member advances the movement shaft along the second male screw portion of the rotation shaft. At the same time, the third transmission means rotates in the same direction as the first transmission means by the engaging operation with the first transmission means via the fifth transmission means, and the moving shaft moves the moving member. The linear actuator according to (III) or (IV), wherein the linear actuator is configured to move in a direction opposite to the direction.

(VII) The linear actuator according to any one of the above (I) to (VI), wherein the number of moving axes is one and the number of rotating axes is two.

(VIII) Sixth transmission means engaged with the first transmission means of both rotary shafts on the opposite side of the third transmission means of the moving shaft across the first transmission means of the two rotary shafts arranged in parallel. The linear actuator according to (VII) above, wherein the sixth transmission means is connected to the drive means via a drive shaft.

(IX) The linear actuator according to (I) or (II), wherein the rotating shaft and the moving shaft are arranged orthogonally, the second transmission means is a pinion, and the fourth transmission means is a rack.

  According to the present invention, a rotational motion is converted into a linear motion via a differential mechanism without using a special (or expensive) mechanical element, thereby generating a large linear motion output from a small input torque and rotating. The position can be precisely controlled by converting the quantity into a linear motion proportionally.

  Further, if the structure is such that the rotation axis and the movement axis are arranged in parallel, the entire actuator can be made compact.

  Further, according to the present invention, the moving amount of the moving shaft in the axial direction is a distance that the moving member and the moving shaft move in one axial direction, and the axial direction in which the moving shaft is opposite to the one axial direction with respect to the moving member. Since the pitch of the second male screw portion of the rotating shaft and the first male screw portion of the moving shaft can be set large, a large load can be applied.

  Furthermore, if the actuator according to the present invention is mainly composed of a combination of a transmission means such as a gear and a screw such as a rotating shaft or a moving shaft, the structure becomes simple, and these members are inexpensive. It can be obtained.

  Previously, it was possible to manufacture high-precision and high-power linear actuators by using screws made of expensive materials and finished with high precision, but using such expensive screws However, the normal ball screw has high accuracy but high output is difficult, and the widely used inexpensive trapezoidal screw has high output, but the lead angle is large, so the accuracy is poor. As a result, it was difficult to satisfy both high output and high accuracy even when a screw that was ground with high accuracy was used. In contrast, the present invention has an effect that the displacement can be controlled with relatively high accuracy even if an inexpensive trapezoidal screw is used.

  In addition, if a small displacement is to be obtained using a trapezoidal screw, the trapezoidal screw must be rotated very slowly, so the frictional force fluctuations caused by switching between static friction and dynamic friction and the motor rotation speed are reduced. In the present invention, due to the adoption of the differential mechanism, even when the displacement is small, the moving speed on the screw surface is relatively small compared to the axial movement amount of the moving shaft. Since the speed can be increased, the fluctuation of the frictional force is suppressed, and the rotational speed of the motor can be maintained at a high speed, and as a result, precise positioning control is possible.

Embodiments according to the present invention will be described below with reference to the drawings.
FIG. 7 shows the configuration of the main part of the linear actuator according to the present invention. FIGS. 8 (a) to 8 (c) show the AA, BB and CC sections of FIG. 7, respectively. It is shown.

  The linear actuator 1 of the present invention is mainly composed of at least one support member, in FIG. 7, four support members 2, 3, 7, and 8, a rotating shaft 4, a moving shaft 5, and a moving member 6. .

  In FIG. 7, the two support members 2 and 3 are arranged in parallel with each other at a predetermined interval. Further, in order to increase the strength of the support members 2 and 3, both ends of the support members 2 and 3 are connected. In this example, two additional support members 7 and 8 that are connected to each other are provided, and a total of four support members 2, 3, 7, and 8 form a rectangular planar shape as a whole. In addition, about the number, shape, etc. of these support members, it can change suitably as needed.

  Further, at least one rotating shaft 4 (two in FIG. 7) that is rotatably supported without being moved in the axial direction and these linear support members 2 and 3 are supported so as to be linearly movable in the axial direction. At least one (one in FIG. 7) moving shaft 5 is provided in parallel.

  As means for rotatably supporting the rotating shaft 4 without moving it in the axial direction, for example, as shown in FIGS. 7 and 8 (a), through-holes 9 are formed in the support members 2 and 3, respectively. The bearing 10 made of a plurality of hard spheres is disposed on the inner peripheral surface of these through-holes 9 so that the rotary shaft 4 is rotatably supported and both sides of the rotary shaft 4 adjacent to the support members 2 and 3 are provided. It is preferable to provide the flange part 11 which expanded the outer diameter as a stopper in a part.

  The means for supporting the moving shaft 5 so as to be linearly movable in the axial direction may be configured similarly to the means for supporting the rotating shaft 4 except that the flange portion is not provided.

  The rotary shaft 4 has the first transmission means 12 on at least one side thereof, preferably a gear, and the first transmission means 12 is provided at a predetermined portion of the rotary shaft, that is, between the support members 2 and 3 in FIG. The second transmission means, which rotates in the same direction, has a second male screw portion 13 in FIG. The second male screw portion 13 is formed by threading in a specific direction around the axis, for example, in a direction that becomes a right screw when viewed from the right side of the drawing in FIG.

  The moving shaft 5 has, on at least one side thereof, third transmitting means 14 that engages with the first transmitting means 12 provided on the rotating shaft 4, preferably a gear, and a predetermined portion of the moving shaft, which is a support member in FIG. The first male screw portion 15 that rotates in the same direction together with the third transmission means 14 is provided at a portion located between the two and the third, and a head portion 28 that performs positioning control in the axial direction is provided at the tip. The first screw portion 15 is formed by threading in a specific direction around the axis, for example, in a direction that becomes a left-hand thread when viewed from the right side of the drawing in FIG.

  The moving member 6 has a second female screw hole 16 as a fourth transmission means, and a second male screw part 13 as a second transmission means of the rotating shaft 4 and a first male screw part 15 of the movement shaft 5 are engaged with each other. The first female screw hole 17 is configured to be movable relative to the support member 2 along the second and first male screw portions 13 and 15.

  In the present invention, the distance by which the movement amount of the moving shaft 5 (and more precisely, the head portion 28) moves in the axial direction x of the moving member 6 and the moving shaft 5 accompanying the rotation of the rotating shaft 4 is as follows. Then, the rotation of the rotary shaft is transmitted to the moving shaft 5 through the first transmission means 12 and the third transmission means 14 and the moving shaft 5 rotates, so that the moving shaft 5 is in one axial direction x with respect to the moving member 6. Is due to the difference in the distance of movement in the opposite axial direction y. By adopting this configuration, it is converted into linear motion via a differential mechanism without using special (expensive) mechanical elements. By doing so, a large linear motion output can be generated from a small input torque, and the rotation amount can be proportionally converted into a linear motion, thereby precisely controlling the positioning.

Next, the operation mechanism of the linear actuator shown in FIG. 7 will be described in detail below.
The linear actuator shown in FIG. 7 includes a first gear by operating a driving means (not shown) such as an electric motor connected to the first transmission means 12 (first gear in FIG. 7). 12 is rotated counterclockwise as viewed from the right side of FIG. FIG. 7 shows a case where the two rotating shafts 4 and 4 are arranged in parallel with the moving shaft 5 interposed therebetween in order to smoothly move the moving member 6 along the rotating shaft 4. As described above, the number of the rotary shafts 4 can be appropriately changed as necessary. In the present invention, a plurality of first gears 12 can be arranged. In this case, if the first gears 12 are simultaneously input at the same rotational speed, the first gear 12 can be provided. Since the load capacity per tooth can be reduced, larger power can be transmitted.

  Next, when the first gear 12 rotates counterclockwise, the rotating shaft 4 that rotates together with the first gear 12 also rotates counterclockwise. At this time, the rotating shaft 4 is rotatably supported by the support members 2 and 3 via the bearing 10.

  The rotary shaft 4 has a second male threaded portion 13 screwed into the second female threaded portion 16 of the moving member 6, and the second male threaded portion 13 is a right-hand thread when viewed from the right side of FIG. As the rotating shaft 4 rotates counterclockwise, the moving member 6 moves along the rotating shaft 4 in the axial direction x (left direction) in FIG. Since the first male screw portion 15 of the moving shaft 5 is screwed to the moving member 6 with the first female screw portion 17 of the moving member 6, the moving member 6 moves as much as the moving distance in the axial direction x of the moving member 6. The shaft 5 also moves in the axial direction x. In the present invention, even one rotating shaft 4 can be operated. However, as shown in FIG. 1, it is preferable to dispose a plurality of rotating shafts 4 in terms of preventing an extra moment acting on the moving member 6. The number of the moving members 6 may be one, but in order to withstand a high linear motion force, the number of teeth of the female screw to be screwed with the male screw portions 13 and 15 of the rotating shaft 4 and the moving shaft 5 is large. In order to achieve this, it is preferable to use a plurality of plates or to increase the plate thickness.

  On the other hand, the moving shaft 5 shown in FIG. 7 is supported by both support members 2 and 3 via a bearing 10 so as to be rotatable and linearly movable (linear movement). The rotational force of the first gear 12 is the first gear. 1 is transmitted to the third transmission means 14 (second gear in FIG. 1), which is rotated clockwise by the rotational force of the first gear 12, and the second gear 14 is rotated clockwise. When the rotary shaft rotates, the moving shaft 5 that rotates together therewith also rotates clockwise. The moving shaft 5 has a first male threaded portion 15 screwed into a first female threaded portion 17 of the moving member 6, and the first male threaded portion 15 is a left-hand thread as viewed from the right side of FIG. As the moving shaft 5 rotates clockwise, the moving shaft 5 moves in the axial direction y (right direction) opposite to the axial direction x in FIG.

  As a result, the moving shaft 5 moves in the axial direction x of the moving member 6 and the moving shaft 5 along with the rotation of the rotating shaft 4, and the rotation of the rotating shaft 4 passes through the first gear 12 and the second gear 14. When the moving shaft is transmitted to the moving shaft and rotated, the moving shaft 5 moves in the axial direction by the difference between the moving shaft 5 and the moving distance in the axial direction y opposite to the one axial direction x. The head portion 28 of the moving shaft is a part that outputs a linear kinetic force in this mechanism, and as a result, the moving shaft 5 has a moving amount in the axial direction x by the moving member 6 described above. A so-called differential output that linearly moves in the axial direction x can be obtained by subtracting the amount of movement in the axial direction y relative to the moving member 6 due to rotation.

  In order to achieve such differential in the axial direction x, the gear ratio between the first gear 12 and the second gear 14, the second male screw portion 13 of the rotating shaft 4, and the first male screw portion 15 of the moving shaft 5. It is necessary to combine the pitch ratios appropriately. For example, when the first gear 12 and the second gear 14 have the same number of teeth, if the pitch of the moving shaft 5 is made smaller than the pitch of the rotating shaft 4, the moving shaft 5 is moved in the axial direction x as a result. be able to. Further, when the pitch of the rotary shaft 4 and the pitch of the moving shaft 5 are equal, if the number of teeth of the second gear 14 is made larger than the number of teeth of the first gear 12, the moving shaft 5 is consequently moved in the axial direction x. Can be moved to.

  In other cases, the gear ratio of each of the gears 12 and 14 and the pitch ratio of the screw portions 13 and 15 of the rotary shaft 4 and the moving shaft 5 are appropriately determined, so that the moving shaft 5 in the axial direction x is determined. It becomes possible to achieve differential.

  In this embodiment, since the second gear 14 moves linearly (moves in the axial direction) together with the moving shaft 5, the engagement state of the second gear 14 and the first gear 12 can be maintained at that time as well. Thus, although the case where the thing of the shape long in an axial direction is used for the 2nd gearwheel 14 is shown, the structure which can maintain the said engagement state should just be maintained, and it is not limited only to the said structure.

  FIG. 9 shows a modification of the arrangement of the two rotating shafts 4 and one moving shaft 5 shown in FIG.

  In this embodiment, the rotation input by one electric motor or the like causes the input gear 19 as the sixth transmission means connected to one side of the input shaft 18 to rotate clockwise in FIG. The input gear 19 is directly meshed with two first gears 12 having the same number of teeth, and simultaneously rotates them counterclockwise. Further, these first gears 12 are directly meshed with the second gears 14 and rotate the second gears 14 clockwise. When the torque of the motor is large, or when the reduction ratio between the input gear 19 and the first gear 12 can be made sufficiently large, the two gears are equal to each other by arranging as in this embodiment. Since the rotation can be given, it is efficient. In addition, the device configuration is reduced in size compared with the case where the rotation shaft 4 and the moving shaft 5 are arranged in a line as in the device configuration of FIG. 8 (c). can do.

  Further, each member constituting the actuator of the present invention can be modified as follows.

  A plurality of moving shafts 5 for outputting linear motion can be provided. At this time, since the plurality of moving shafts 5 move linearly at the same time, if a lifting plate is attached to the tip of the plurality of moving shafts 5 via a thrust bearing or the like, it can be used as a lifting device having a high portable force.

  If the second gear 14 only transmits rotation to the moving shaft 5, for example, a ball spline or the like is provided between the moving shaft 5 and the second gear 14, and the second gear 14 moves relative to the moving shaft 5. If the second gear 14 is configured to be slidable, the engagement with the first gear 12 can be maintained without using a second gear 14 that is long in the axial direction, and in addition, the weight can be reduced. When this configuration is adopted, it is possible to use “helical gears” having a larger transmission capacity than the spur gears as the first and second gears 12 and 14.

  In the above embodiment, gears are used as the first and second transmission means 12 and 14, but other transmission means such as an endless belt can be used as long as both linear movement and rotation are allowed. May be used.

  Further, FIG. 7 shows a case where the output of the moving shaft 5 at the head portion 28 generates a linear motion force in the outward direction (the axial direction x in the figure). By setting the relationship between the number ratio and the pitch ratio of the screw portions 13 and 15 of the rotary shaft 4 and the moving shaft 5 to be opposite to that in the case of FIG. 7, the output at the head portion 28 of the moving shaft 5 is achieved. However, it is also possible to change so as to generate a linear motion force in the inward direction (the axial direction y in the figure). For example, the pitch ratio of the first male screw portion 15 of the moving shaft 5 and the second male screw portion 13 of the rotating shaft 4 is made equal, and the number of teeth of the second gear 14 is made smaller than the number of teeth of the first gear 12. it can.

  7 shows a case where both the supporting members 2 and 3 are fixed and the moving member 6 is movable in the axial direction, but on the contrary, the moving member 6 is fixed and both the supporting members 2 and 3 are fixed. Can be configured to be movable.

  Further, FIG. 7 shows a case where the rotational force by the driving means is input to the first gear 12, but it may be configured to be input to the second gear 14.

FIG. 10 shows another embodiment.
FIG. 7 shows a case where the second male screw portion 13 of the rotating shaft 4 is a right-hand screw and the first male screw portion 15 of the moving shaft 5 is a left-hand screw. It is often difficult to obtain.

  In such a case, as shown in FIG. 10 and FIGS. 11A to 11D, the second male screw portion 13 of the rotating shaft 4 and the first male screw portion 15 of the moving shaft 5 are both formed by right-hand screws. A third gear 20 is provided between the first gear 12 and the second gear 14 and is a fifth transmission means connected to a rotary shaft 26 rotatably supported by the support member 2 and another support member 27; When the first gear 12 is rotated in one direction (counterclockwise in FIG. 10), the rotating shaft 4 rotates together with the first gear 12, and the moving member 6 moves along the second male screw portion 13 of the rotating shaft 4. At the same time as moving the moving shaft 5 in the forward direction (axial direction x), the same direction as the first gear 12 is engaged with the first gear 12 via the third gear 20 (counterclockwise in FIG. 10). When the second gear 14 rotates, the moving shaft 5 moves in the direction opposite to the moving direction (axial direction x) of the moving member 6 (axial direction). It may be configured to move in). In the present invention, the case where both the second male screw portion 13 of the rotating shaft 4 and the first male screw portion 15 of the moving shaft 5 are formed by left-hand screws is not excluded, and such a case is also included. Needless to say.

  In the above configuration, when it is necessary to downsize the entire actuator, it is desirable to make the outer diameter dimension of the third gear 20 as small as possible. In that case, it is preferable to arrange a plurality of third gears 20 having the same number of teeth in order to prevent a decrease in transmission torque. Further, if the third gear 20 is long in the axial direction, the second gear 14 having a large outer diameter is not lengthened in the axial direction, and between the gear 12 and the gear 20 and between the gear 14 and the gear 20. Can be maintained, and as a result, the overall weight is reduced.

  In any of the above embodiments, the moving shaft 5 rotates linearly and simultaneously. Such rotation can prevent the rotation of the action target by connecting the movement axis 5 and the action target via a thrust bearing, but when it is desired not to rotate the movement axis 5 itself, for example, As shown in FIGS. 12 and 13 (a) to 13 (d), a pair of support members 2 and 3 are fixed, and these support members 2 and 3 constitute a fourth gear serving as a pair of fourth transmission means. The rotary input shaft 22 and the moving shaft 5 connected to 21a and 21b are carried, and two pairs of rotating members 23a and 23b and 24a and 24b carried by the moving shaft 5 and the rotating shaft 4 are arranged for rotational input. Ring-shaped fifth gears 25a and 25b are rotatably disposed between the fourth gears 21a and 21b of the shaft 22 and the first gears 12a and 12b of the three rotary shafts 4 so that the rotary input shaft 22 The input rotational force is transmitted to the fifth gears 25a and 25b via the fourth gears 21a and 21b, and rotates in the direction of the arrow shown in FIG. 13 (c), and the rotation of the fifth gears 25a and 25b. As a result, the three first gears 12a and 12b rotate and roll around the second gears 14a and 14b, so that the rotating members 23a, 23b, 24a and 24b and the moving member 6 rotate around the moving shaft 5. The amount of movement of the moving member 6 in one axial direction (axial direction x) due to rotation of the rotating shaft 4 and the axial direction of the moving shaft 5 opposite to the moving member 6 due to rotation around the moving shaft 5 A differential in the axial direction x of the moving shaft 5 can be achieved by the difference from the amount of movement in the (axial direction y).

Further, the positional relationship between the moving member 6 and the supporting members 2 and 3 is not limited to the case where the moving member 6 is between the supporting members 2 and 3 as shown in FIG. As shown to a)-(d), it can also arrange | position outside the supporting members 2 and 3. FIG.
Furthermore, as another embodiment, the rotating shaft 4 and the moving shaft 5 can be configured to be supported by only one support member 33 as shown in FIGS. 15 (a) to (d). .

  Up to this point, the case where the rotation axis and the movement axis are arranged in parallel has been described, but in the present invention, as shown in FIGS. 16 (a) to (d), the rotation axis is set with respect to the movement axis. They can also be arranged orthogonally. In this case, it is preferable that the second transmission means is a pinion 29 instead of the second male screw portion 13 and the fourth transmission means is configured as a rack instead of the second female screw hole 16.

  The above description is merely an example of the embodiment of the present invention, and various modifications can be made within the scope of the claims.

  According to the present invention, a large linear motion output is generated from a small input torque and a rotation amount is proportional by converting to a linear motion via a differential mechanism without using a special (or expensive) mechanical element. Therefore, the position can be precisely controlled by converting it into linear motion.

  Further, the entire actuator can be made compact by adopting a structure in which the rotation axis and the movement axis are arranged in parallel.

  Further, according to the present invention, the moving amount of the moving shaft in the axial direction is moved in the axial direction opposite to the moving direction of the moving member and the moving shaft in the one axial direction and the moving shaft relative to the moving member. Therefore, the pitch of the second male screw portion of the rotating shaft and the first male screw portion of the moving shaft can be set large, so that a large load can be applied.

  Furthermore, since the actuator of the present invention is mainly composed of a combination of a transmission means such as a gear and a screw such as a rotating shaft or a moving shaft, the structure is simple, and these members are It can be obtained at low cost.

  In the past, high-precision and high-power linear actuators could be manufactured using expensive materials and high-precision ground screws, but such screws can be used. Applications are limited, and normal ball screws have high accuracy but high output is difficult, and widely used inexpensive trapezoidal screws have high output but poor accuracy. Even using screws that have been ground precisely, both high output and high accuracy could not be satisfied. In contrast, the present invention has an effect that the displacement can be controlled with relatively high accuracy even if an inexpensive trapezoidal screw is used.

  In addition, if a small displacement is to be obtained using a trapezoidal screw, the trapezoidal screw must be rotated very slowly, so the frictional force fluctuations caused by switching between static friction and dynamic friction and the motor rotation speed are reduced. In the present invention, due to the adoption of the differential mechanism, even when the displacement is small, the moving speed on the screw surface is relatively small compared to the axial movement amount of the moving shaft. Since the speed can be increased, the fluctuation of the frictional force is suppressed, and the rotational speed of the motor can be maintained at a high speed, and as a result, precise positioning control is possible.

It is the figure which showed the conventional apparatus which combined the screw and the nut directly. It is the figure which showed the conventional apparatus using a differential screw mechanism. It is the figure which showed the conventional apparatus using the rack and pinion mechanism. It is the figure which showed the conventional apparatus using a worm mechanism. It is the figure which showed the conventional apparatus using a crank mechanism. It is the figure which showed the conventional apparatus using the pantograph mechanism. It is a front view which shows the typical linear actuator according to this invention. (a) is AA sectional drawing of FIG. 7, (b) is BB sectional drawing of FIG. 7, (c) is CC sectional drawing of FIG. FIG. 8C is a modification example of FIG. It is a figure which shows other embodiment. 10A is a sectional view taken along line AA in FIG. 10, FIG. 10B is a sectional view taken along line BB in FIG. 10, FIG. 10C is a sectional view taken along line CC in FIG. It is sectional drawing. It is a figure which shows other embodiment. 12A is a sectional view taken along line AA in FIG. 12, FIG. 12B is a sectional view taken along line BB in FIG. 12, FIG. 12C is a sectional view taken along line CC in FIG. It is sectional drawing. (a) is the front view which shows other embodiment, (b) is AA sectional drawing of (a), (b) is BB sectional drawing of (a), and (c) is It is CC sectional drawing of (a). (a) is a front view showing another embodiment, (b) is a sectional view taken along the line AA of (a), (c) is a sectional view taken along the line BB of (a), and (d) is a sectional view taken along the line BB. It is CC sectional drawing of (a). (a) is a front view showing another embodiment, (b) is a plan view when viewed from the direction of arrow A in (a), (c) is a cross-sectional view along BB in (a), And (d) is CC sectional drawing of (a).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Linear actuator 2, 3, 27 Support member 4 Rotating shaft 5 Moving shaft 6 Moving member 7, 8 Support member 9 Through-hole
10 Bearing
11 Flange
12, 12a, 12b First transmission means or first gear
13 2nd male thread
14, 14a, 14b Third transmission means or second gear
15 1st male thread
16 2nd female screw hole
17 1st female screw hole
18 Input shaft
19 Input gear
20 3rd gear
21a, 21b 4th gear
22 Rotation input shaft
23a, 23b, 24a, 24b Rotating member
25a, 25b 5th gear
26 Rotation axis
28 Moving axis head
29 Pinion
30 racks
31 Linear motion guide
32 Rotary linear motion guide
33 Support member

Claims (9)

The at least one support member is provided with at least one rotating shaft that is rotatably supported and at least one moving shaft that is supported so as to be movable in the axial direction,
The rotation shaft has first transmission means on at least one side thereof, and has a second transmission means that rotates in the same direction together with the first transmission means at a predetermined portion of the rotation shaft,
The moving shaft has, on at least one side thereof, third transmitting means that engages with the first transmitting means provided on the rotating shaft, and a first male screw that rotates in the same direction together with the third transmitting means on a predetermined portion of the moving shaft Having a head part that performs positioning control in the axial direction at the tip,
It has at least a first female screw hole into which the first male screw part of the moving shaft is screwed and a fourth transmission means that operates in linkage with the second transmission means of the rotary shaft. Providing at least one possible moving member;
The amount of movement of the moving shaft in the axial direction is determined by the distance traveled in one axial direction of the moving member and the moving shaft along with the rotation of the rotating shaft, and the rotation of the rotating shaft being transmitted to the moving shaft through the first and third transmission means. A linear actuator characterized in that a difference between a moving axis and a distance by which the moving axis moves in an axial direction opposite to one axial direction with respect to the moving member by rotating the moving axis. The linear actuator according to claim 1, wherein each of the first and third transmission means is a gear. 3. The linear actuator according to claim 1, wherein the rotating shaft and the moving shaft are arranged in parallel, the second transmission means is a second male screw portion, and the fourth transmission means is a second female screw hole. 4. The linear actuator according to claim 3, wherein the amount of axial movement of the head portion of the moving shaft is determined by the pitch ratio of the first and second male screw portions and the tooth number ratio of the first and third transmission means. The second male screw portion of the rotating shaft is formed by a right screw or a left screw, the first male screw portion of the moving shaft is formed by a screw opposite to the second male screw portion, and rotates the first transmission means in one direction. Then, the rotating shaft co-rotates with the first transmission means to move the moving member forward, and the moving member moves along the second male screw portion of the rotating shaft in the direction of moving the moving shaft forward. The third transmission means is rotated in the opposite direction to the first transmission means by the engaging operation with the movement member, and the moving shaft is configured to move in the direction opposite to the moving direction of the moving member. 4. The linear actuator according to 4. The second male threaded portion of the rotating shaft and the first male threaded portion of the moving shaft are both formed by right-hand threads, and a fifth power transmitting means for engaging with these is provided between the first power transmitting means and the third power transmitting means, When the first transmission means is rotated in one direction, the rotation shaft rotates together with the first transmission means to advance the moving member, and the moving member advances the movement shaft along the second male screw portion of the rotation shaft. Simultaneously with the movement, the third transmission means is rotated in the same direction as the first transmission means by the engaging operation with the first transmission means via the fifth transmission means, and the moving shaft is the moving direction of the moving member. 5. The linear actuator according to claim 3, wherein the linear actuator is configured to move in a reverse direction. The linear actuator according to claim 1, wherein one moving axis is provided and two rotating axes are provided. Sixth transmission means that engages with the first transmission means of both rotary shafts is provided on the opposite side of the first transmission means of the two rotary shafts arranged in parallel to the third transmission means of the moving shaft, The linear actuator according to claim 7, wherein the sixth transmission means is coupled to the drive means via a drive shaft. 3. The linear actuator according to claim 1, wherein the rotating shaft and the moving shaft are arranged orthogonally, the second transmission means is a pinion, and the fourth transmission means is a rack.

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