JP2013061031A - Planetary rotation/linear motion conversion device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a planetary rotation/linear motion conversion device that facilitates assembling, can reduce costs by decreasing parts count, can improve durability by suppressing the twist of a planetary shaft, and can convert motion from rotation motion to liner motion.SOLUTION: A sun shaft protrusion 44, a planetary shaft recess 36 and a ring shaft protrusion 26 are formed at a sun shaft 40, a planetary shaft 30 and a ring shaft 20, and the planetary shaft recess 36, the sun shaft protrusion 44 and the ring shaft protrusion 26 are engaged with one another. A flat gear or a helical gear of a first planetary gear mechanism is intermittently formed of a pair of side faces of the sun shaft protrusion 44, the planetary shaft recess 36 and the ring shaft protrusion 26, and spiral teeth of a second planetary gear mechanism are intermittently formed of a pair of the other side faces. A tooth number ratio of the flat gear or the helical gear of the sun shaft 40 with respect to the planetary shaft 30 and a string number ratio of teeth of spiral strings, and a tooth number ratio of the ring shaft 20 with respect to the planetary shaft 30 and a string number ratio are equal to each other in one tooth number ratio and one string number ratio, and different from each other in the other tooth ratio and the other string number ratio.

Description

  The present invention relates to a planetary rotation-linear motion conversion device that converts rotational motion into linear motion using a planetary gear mechanism, and more specifically, the tooth surfaces of two gears are formed on the sun shaft, the planet shaft, and the ring shaft, respectively. The present invention relates to a planetary-linear motion conversion device.

  In recent years, a planetary-linear motion conversion device has been proposed as a new machine element. This device is provided with a spur gear or a helical gear and a screw gear having helical teeth on the sun shaft, the planetary shaft, and the ring shaft, respectively, and is constituted by a spur gear or a helical gear. A rotational movement is converted into a linear movement by providing a difference in reduction ratio between one planetary gear mechanism and a second planetary gear mechanism constituted by a screw gear. This device is a completely new machine element and has many possibilities.

  For example, Patent Document 1 discloses the principle of this mechanism and shows some configuration examples. In particular, the configuration example shown in FIG. 6 is a combination of a concave sun gear in which spur gears and screw gears are mixed with a convex planet, and is extremely excellent in terms of mechanism.

  That is, FIG. 6A is a cross-sectional view showing a cross section along the rotation axis 112. FIG. 6B is a cross-sectional view showing a cross section perpendicular to the rotation axis 112 at the central portion in the axial direction. FIG. 6C is a right side view showing the main part of the sun shaft 114. In FIGS. 6A to 6C, cross-sectional hatching is not shown.

  As shown in FIGS. 6A to 6C, the planetary-linear motion conversion device 110 is provided with both tooth portions 164 having a tooth surface of a spur gear and a tooth surface of a screw gear on the sun shaft 114. It has been. Each planetary shaft 120 is provided with both tooth portions 166 having a tooth surface of a spur gear and a tooth surface of a screw gear.

  Inside the ring shaft 116, large diameter portions are formed on both sides of the central small diameter portion. On the inner surface of the small-diameter portion of the ring shaft 116, threaded gears 144 of both tooth portions 166 of the planetary shaft 120 are formed. Ring gear members 142 and 160 are fixed to the inner surface of the large-diameter portion of the ring shaft 116 by press-fitting while being spaced apart from each other along the rotation axis 112. Spur gear internal teeth are formed on the inner surfaces of the ring gear members 142 and 160. The internal teeth of the ring gear members 142 and 160 mesh with the tooth surfaces of the spur gears of both the tooth portions 166 at both ends of each planetary shaft 120.

  Further, in Patent Document 2, as shown in the perspective view of FIG. 7, a planetary rotation-linear motion conversion device in which a spur gear 211 and a screw gear 212 are formed in a convex shape on the outer peripheral surface of the sun shaft 201. Is disclosed.

JP 2007-56952 A JP 2010-156452 A

  In order for the planetary rotation-linear motion conversion device to be used for general purposes, an invention that conforms to the principle and can overcome the difficulty is indispensable.

  For example, as shown in FIG. 6, a combination of a concave sun shaft in which a spur gear and a screw gear are mixed and a convex planetary shaft is extremely superior in terms of mechanism. However, in order to process the concave sun shaft into a shaft shape, it must be processed by so-called through rolling, which is very difficult to process.

  Further, the screw-shaped gear formed in the convex shape of the planetary shaft meshes with the screw-shaped gear 144 of the ring shaft 116, and the spur gear formed in the convex shape of the planetary shaft is the two ring gear members in the ring shaft 116. It meshes with 142 and 160 spur gears. That is, the ring shaft 116 includes a total of three gears: two spur gears of the ring shaft 116 and a screw gear 114. These gears have different meshing. By meshing with the screw gear 114, a force that causes the planetary shaft 120 to tilt in the circumferential direction acts on the planetary shaft 120, and the force is received by the meshing of the two spur gears of the ring shaft 116. Therefore, the spur gear of the ring shaft 116 and the portions that mesh with the spur gear of the ring shaft 116 at both ends of the planetary shaft 120 are likely to wear.

  In the example of FIG. 6, it is theoretically possible to use a spur gear (straight tooth) as a helical gear. However, even if one ring gear member 142 can be inserted into the ring shaft 116, It becomes very difficult to insert the other ring gear member 160. This is because when one of the two ring gear members 142 and 160 is inserted into one of the ring shafts 116, the phase of the planetary shaft is determined between the screw-shaped gear and the helical gear. When the other of 160 and 160 is to be inserted, it must be inserted while rotating spirally, and the assemblability is extremely poor. Therefore, the ring gear members 142 and 160 cannot use helical teeth and must be spur gears. Since the spur gear has a small meshing rate, it may not be converted continuously into linear motion during rotation-linear motion conversion, resulting in a stepwise linear displacement.

  In the example of FIG. 7, the processing of the solar shaft 201 is facilitated by making the solar shaft 201 convex. However, a screw 142 is formed between the spur gears 241 on the planetary shaft 204. Two ring gears 205 are inserted into the nut 202 so as to mesh with the two spur gears 241 of the planetary shaft 202. Assembling the ring gear 205 is extremely difficult.

  In view of such circumstances, the problems to be solved by the present invention are as follows: (a) easy assembly, (b) the number of parts can be reduced and the cost can be reduced, and (c) the torsion of the planetary shaft can be suppressed and the durability can be reduced. It is an object of the present invention to provide a planetary rotation-linear motion conversion device that can realize improvement and conversion from smooth rotational motion to linear motion.

  In order to solve the above problems, the present invention provides a planetary rotation-linear motion conversion device configured as follows.

  The planetary rotation-linear motion converter includes (a) a sun axis having a rotation axis parallel to each other, a plurality of planet axes, a ring axis, and (b) rotatably holding the planet axis, And a cage that is rotatable with respect to the ring shaft. On the outer peripheral surface of the planetary shaft, a plurality of planetary shaft recesses that are retreated radially inward from the outer peripheral surface and have two pairs of side surfaces are formed apart from each other. On the outer peripheral surface of the sun shaft, a plurality of sun shaft convex portions projecting radially outward from the outer peripheral surface and having two pairs of side surfaces and meshing with the planetary shaft concave portion are formed apart from each other. On the inner peripheral surface of the ring shaft, a plurality of ring shaft convex portions that protrude radially inward from the inner peripheral surface, have two pairs of side surfaces, and mesh with the planetary shaft concave portion are formed apart from each other. A pair of side surfaces of the planetary shaft concave portion, the sun shaft convex portion, and the ring shaft convex portion are, in order, a spur gear or a helical gear, and cooperate with each other to constitute a first planetary gear mechanism, The tooth surfaces of planetary gears and ring gears are formed intermittently. The other pair of side surfaces of the planetary shaft concave portion, the sun shaft convex portion, and the ring shaft convex portion are screw gears having helical teeth in this order and cooperate with each other to constitute a second planetary gear mechanism. The tooth surfaces of the threaded sun gear, the threaded planetary gear, and the threaded ring gear are intermittently formed. (I) The ratio of the number of teeth of the spur gear or the helical gear of the sun gear to the planetary gear is different from the ratio of the number of helical teeth of the threaded sun gear to the screw planetary gear, and the planetary gear. The ratio of the number of teeth of the spur gear or the helical gear of the ring gear to the gear is equal to the ratio of the number of helical teeth of the threaded ring gear to the screw planetary gear. Or (II) the ratio of the number of teeth of the spur gear or the helical gear of the sun gear to the planetary gear is equal to the ratio of the teeth of the helical teeth of the threaded sun gear to the threaded planetary gear, and The gear ratio of the spur gear or the helical gear of the ring gear to the planetary gear is different from the gear ratio of the helical teeth of the screw ring gear to the screw planetary gear.

  According to the above configuration, in the case of (I), in the state where a plurality of planetary shafts are assembled to the ring shaft so that the ring shaft convex portion and the planetary shaft concave portion are fitted, the sun shaft is rotated to the center. By disposing the solar shaft, the solar shaft can be inserted while the solar shaft convex portion is engaged with the planetary shaft concave portion. In the case of (II), in a state where a plurality of planetary shafts are assembled to the sun axis so that the sun axis convex part and the planetary axis concave part are fitted, The ring shaft can be covered while engaging the convex portion of the ring shaft with the concave portion of the planetary shaft. Therefore, the planetary rotation-linear motion conversion device can be easily assembled.

  Also, depending on the planetary shaft recess, a planetary gear that is a spur gear or a helical gear and a screw-type planetary gear are integrated to form a planetary shaft, and a sun gear that is a spur gear or a helical gear is formed by the sunshaft convex portion. And the threaded sun gear are integrated to form the sun shaft, and the ring gear that is a spur gear or a helical gear is integrated with the ring shaft convex portion to form the threaded ring gear on the ring shaft. The number of parts can be reduced and the cost can be reduced.

  Furthermore, by forming the planetary shaft concave portion on the planetary shaft, the planetary shaft has higher rigidity than the case where the outer peripheral surface of the planetary shaft is formed with a convex portion protruding radially outward. As a result, twisting of the planetary shaft is suppressed, and the planetary rotation-linear motion conversion device can improve durability and smooth linear motion.

  Preferably, the sun gear, the planetary gear, and the ring gear constituting the first planetary gear mechanism are helical gears. The direction of twisting of the teeth of the planetary gear and the direction of twisting of the helical teeth of the threaded planetary gear are opposite to each other. The twist direction of the teeth of the sun gear and the twist direction of the spiral teeth of the screw sun gear are opposite to each other. The twisting direction of the teeth of the ring gear and the twisting direction of the helical teeth of the threaded ring gear are opposite to each other.

  In this case, the angles of the four corners of the planetary shaft concave portion, the sun shaft convex portion, and the ring shaft convex portion are such that the helical direction of the helical gear and the helical direction of the helical gear are the same. Compared to some cases, it is closer to 90 degrees. Therefore, the durability of the planetary rotation-linear motion conversion device is improved.

  Preferably, the cage includes (a) a first holding portion that rotatably holds one end side of the planetary shaft and is rotatable with respect to the sun shaft and the ring shaft; and (b) the planetary gear. A second holding portion that rotatably holds the other end side of the shaft and is rotatable with respect to the sun shaft and the ring shaft; and (c) disposed between the planetary gears adjacent to each other, and A plurality of connecting portions that are fixed to the first holding portion and the second holding portion and prevent relative rotation between the first holding portion and the second holding portion;

  In this case, since the position shift of both ends of the planetary shaft is prevented by the cage, the planetary shaft is prevented from being twisted by a load acting on the tooth surface of the screw-like planetary gear. Thereby, the durability of the planetary rotation-linear motion conversion device is further improved, and the linear motion becomes smoother.

  Preferably, the ratio of the number of teeth of the spur gear or the helical gear of the sun gear to the planetary gear is equal to the ratio of the number of helical teeth of the threaded sun gear to the screw-type planetary gear, and the planetary gear. The gear ratio of the spur gear or the helical gear of the ring gear to the gear is different from the gear ratio of the helical teeth of the screw ring gear to the screw planetary gear. The ring axis moves relative to the planetary axis and the sun axis in parallel with the rotation axis.

  In this case, when the sun axis rotates, the ring axis moves linearly. When the ring axis rotates, the sun axis moves linearly.

  The planetary rotation-linear motion conversion device of the present invention can be (a) easy to assemble, (b) reduce the number of parts and reduce costs, and (c) improve the durability by suppressing torsion of the planetary shaft. Conversion from smooth rotational motion to linear motion can be realized.

It is sectional drawing of a planetary rotation-linear motion converter. Example 1 It is sectional drawing of the ring axis | shaft of a planetary rotation-linear motion converter. Example 1 It is sectional drawing of the planetary axis | shaft of a planetary rotation-linear motion converter. Example 1 It is sectional drawing of the planetary axis | shaft of a planetary rotation-linear motion converter. (Example 2) It is a top view of a planetary-axis recessed part. (Example 2) It is sectional drawing which shows (A) sectional drawing perpendicular | vertical to a rotating shaft of a planetary rotation-linear motion converter, (B) sectional drawing containing a rotating shaft, and (C) principal part of a sun shaft. (Conventional example 1) It is a perspective view of a planetary rotation-linear motion conversion device. (Conventional example 2)

  Hereinafter, embodiments of the present invention will be described with reference to FIGS.

  First Embodiment A planetary rotation-linear motion conversion device 10 according to a first embodiment will be described with reference to FIGS.

  FIG. 1 is a cross-sectional view of a planetary rotation-linear motion conversion device 10. FIG. 2 is a cross-sectional view of the ring shaft 20 of the planetary rotation-linear motion conversion device 10. FIG. 3 is a cross-sectional view of the planetary shaft 30 of the planetary rotation-linear motion conversion device 10.

  As shown in FIGS. 1 to 3, the planetary rotation-linear motion conversion device 10 includes a sun axis 40 having a rotation axis 40x, 30x, and 20x parallel to each other, a plurality of planet axes 30 and a ring axis 20, and a cage. 50.

  As shown in FIG. 1, a plurality of sun shaft convex portions 44 projecting radially outward from the outer circumferential surface 42 of the sun shaft 40 are formed on the outer circumferential surface 42 of the sun shaft 40 so as to be separated from each other. The sun axis convex portion 44 has two pairs of side surfaces and a top surface.

  The pair of side surfaces of the sun shaft convex portion 44 intermittently forms the tooth surface of the spur gear. That is, along the outer peripheral surface 42 of the sun shaft 40, the space is arranged in parallel with the rotation axis 40x, and is arranged at equal intervals in the circumferential direction. The pair of side surfaces serve as tooth surfaces of the “sun gear constituting the first planetary gear mechanism” of the present invention.

  The other pair of side surfaces of the sun shaft convex portion 44 intermittently forms a tooth surface of a screw gear having spiral teeth. That is, it is continuous along the outer peripheral surface 42 of the sun shaft 40 at intervals. The other pair of side surfaces serve as tooth surfaces of the “screw-shaped sun gear constituting the second planetary gear mechanism” of the present invention.

  As shown in FIGS. 1 and 3, a plurality of planetary axes 30 are arranged around the sun axis 40. Both end portions 38a and 38b of the planetary shaft 30 are rotatably supported by the first holding portion 50a and the second holding portion 50b of the cage 50.

  A plurality of planetary shaft recesses 36 are formed on the outer peripheral surface 34 of the main body 32 of the planetary shaft 30 so as to recede radially inward from the outer peripheral surface 34. The planetary shaft recess 36 has two pairs of side surfaces and a bottom surface.

  The pair of side surfaces of the planetary shaft recess 36 intermittently forms the tooth surface of the spur gear. That is, the planetary shaft 30 is arranged along the outer peripheral surface 34 of the main body 32 in parallel with the rotation axis 40x at intervals, and is arranged at equal intervals in the circumferential direction. The pair of side surfaces serve as tooth surfaces of the “planetary gear constituting the first planetary gear mechanism” of the present invention.

  The other pair of side surfaces of the planetary shaft recess 36 intermittently forms a tooth surface of a screw gear having spiral teeth. That is, the planetary shaft 30 is continuous along the outer peripheral surface 34 of the main body 32 with a space therebetween. The other pair of side surfaces serve as tooth surfaces of the “threaded planetary gear constituting the second planetary gear mechanism” of the present invention.

  As shown in FIGS. 1 and 2, a plurality of ring shaft convex portions 26 projecting radially inward from the inner peripheral surface 24 are formed on the inner peripheral surface 24 of the center of the main body 22 of the ring shaft 20 so as to be separated from each other. Has been.

  The pair of side surfaces of the ring shaft convex portion 26 intermittently forms the tooth surface of the spur gear. That is, along the inner peripheral surface 24 of the ring shaft 20, the space is arranged in parallel with the rotation axis 40 x and is arranged at regular intervals in the circumferential direction. The pair of side surfaces serve as tooth surfaces of the “ring gear constituting the first planetary gear mechanism” of the present invention.

  The other pair of side surfaces of the ring shaft convex portion 26 intermittently forms a tooth surface of a screw gear having helical teeth. That is, it is continuous along the inner peripheral surface 24 of the ring shaft 20 at intervals. The other pair of side surfaces serve as tooth surfaces of the “threaded ring gear constituting the second planetary gear mechanism” of the present invention.

  Inner peripheral surfaces 27a and 27b having an inner diameter larger than that of the central inner peripheral surface 24 are formed on both ends 20a and 20b of the ring shaft 20. The first holding portion 50a and the inner peripheral surfaces 27a and 27b are formed on the inner sides of the inner peripheral surfaces 27a and 27b. The second holding portion 50 b is disposed so as to be rotatable with respect to the sun shaft 40 and the ring shaft 20 by providing a gap between the ring shaft 20 and the sun shaft 40. Grooves 27s and 27t extending in the circumferential direction are formed on the inner peripheral surfaces 27a and 27b, and the grooves 27s and 27t prevent the first holding part 50a and the second holding part 50b from moving in the axial direction. The member 52 is fitted.

  A flange 28 is provided on the one end 20 a side of the ring shaft 20, and a through-hole 29 for attachment is formed in the flange 28.

  In the planetary rotation-linear motion conversion device 10, the sun shaft convex portion 44 and the ring shaft convex portion 26 mesh with the planet shaft concave portion 36, and the respective side surfaces abut against each other. At this time, the first planetary gear mechanism is configured by meshing the pair of side surfaces, that is, the planetary gear, the sun gear, and the ring gear. Further, the second planetary gear mechanism is configured by meshing the other pair of side surfaces, that is, the threaded planetary gear, the threaded sun gear, and the threaded ring gear.

  Spur gear ratio in the first planetary gear mechanism and thread ratio in the second planetary gear mechanism (ratio of the number of helical teeth included in one pitch in the rotation axis direction) Is selected as follows.

  In the first case, the ratio of the number of teeth of the spur gear of the sun gear to the planetary gear is different from the ratio of the number of threads of the screw gear, and the ratio of the number of teeth of the spur gear of the ring gear to the planetary gear and the number of threads of the screw gear. Make the ratio equal. In this case, the ring shaft and the planetary shaft do not move relative to each other in the axial direction because the gear ratio and the gear ratio are equal. On the other hand, the sun axis and the planetary axis move relative to each other in the axial direction because the gear ratio and the gear ratio are different. Therefore, the rotational motion of the sun axis can be converted into the linear motion of the ring axis and the planetary axis, and the rotational motion of the ring axis and the planetary axis can be converted into the linear motion of the sun axis.

  In the second case, the ratio of the number of teeth of the spur gear of the sun gear to the planetary gear is equal to the number of threads of the screw gear, and the ratio of the number of teeth of the spur gear of the ring gear to the planetary gear and the number of threads of the screw gear. Make the ratio different. In this case, the sun axis and the planetary axis do not move relative to each other in the axial direction because the gear ratio and the gear ratio are equal. On the other hand, the ring shaft and the planetary shaft move relative to each other in the axial direction because the gear ratio and the gear ratio are different. Therefore, the rotational motion of the sun axis and the planetary axis can be converted into the linear motion of the ring axis, and the rotational motion of the ring axis can be converted into the linear motion of the sun axis and the planetary axis.

  The cage 50 is disposed between the planet shafts 30 adjacent to each other, is fixed to the first holding unit 50a and the second holding unit 50b, and prevents relative rotation between the first holding unit 50a and the second holding unit 50b. And a connecting portion (not shown). Since the relative rotation between the first holding part 50a and the second holding part 50b is prevented, the torsion of the planetary shaft 30 due to the load acting on the tooth surface of the screw-like planetary gear is suppressed. Thereby, the durability of the planetary rotation-linear motion converter 10 is improved, and the linear motion becomes smooth. The cage may be configured such that the connecting portion is eliminated and the first holding portion and the second holding portion are not connected.

  Next, the assembly procedure of the planetary rotation-linear motion conversion device 10 will be described.

  In the case of the first case, that is, when the sun axis 40 is displaced in a linear direction with respect to the ring axis 20 and the planetary axis 30, after assembling other than the sun axis 40, the sun axis 40 is inserted while rotating. Can be assembled by.

  First, a predetermined number of planetary shafts 30 are arranged at a predetermined interval inside the ring shaft 20, the ring shaft convex portion 26 of the ring shaft 20 and the planetary shaft concave portion 36 of the planetary shaft 30 are engaged with each other, and the cage 50. After holding the planetary shaft 30, the retaining member 52 is attached. By the meshing of the planetary shaft concave portion 36 and the ring shaft convex portion 26, the positional relationship of the meshing of the spur teeth and the positional relationship of the meshing of the screw gear can be determined simultaneously.

  Next, the sun shaft convex portion 44 is engaged with the planetary shaft concave portion 36 while rotating the sun shaft 40. By this engagement, the positional relationship between the engagement of the spur teeth and the positional relationship between the engagement of the screw gears are determined simultaneously, so that the positional relationship (transfer relationship) of the planetary shaft 30 with respect to the sun shaft 40 is determined. If the spur gear and the screw gear are processed in advance in the sun shaft 40 so as to mesh with the spur gear and the screw gear of the planetary shaft 30, when the sun gear meshes with the planet gear while rotating the sun shaft 40, Since the sun axis 40 moves in the linear direction, the sun axis 40 can be inserted. That is, the sun axis can be inserted while maintaining the helical engagement.

  In the case of the second case, that is, when the ring axis is displaced in a linear direction with respect to the sun axis and the planet axis, a plurality of planet axes are arranged on the sun axis so that the sun axis convex part and the planet axis concave part are fitted. In a state where the ring shaft is assembled, the ring shaft is arranged on the outer side of the ring shaft so that the ring shaft is rotated. In this case, if the maximum outer diameters of the first holding part and the second holding part are made smaller than the minimum inner diameter of the ring shaft, the assembly is facilitated.

  In the planetary rotation-linear motion conversion device 10, the sun shaft 40, the planet shaft 30, and the ring shaft 20 corresponding to the sun gear, the planet gear, and the ring gear are processed to be uneven. The planetary rotation-linear motion conversion device 10 is easily assembled by integrating a screw gear and a spur gear, which have been separated in the prior art. That is, if the screw gear and the spur gear are separated, for example, the spur gear needs to be inserted after the screw gear is assembled so as to achieve a predetermined meshing, and the number of processes is increased. On the other hand, if the screw gear and the spur gear are integrated, the positional relationship (phase) of the meshing of both the screw gear and the spur gear can be determined at the same time, thereby reducing the number of processes.

  Further, the integration of the screw gear and the spur gear can reduce the number of parts and reduce the cost.

  Furthermore, by forming the planetary shaft concave portion 36 in the planetary shaft 30, the planetary shaft 30 has higher rigidity than the case where the outer peripheral surface 34 of the planetary shaft 30 is formed with a convex portion protruding radially outward. Thereby, since the twist of the planetary shaft is suppressed, the planetary rotation-linear motion conversion device 10 can improve durability and smooth linear motion.

  In particular, when the cage 50 in which the first holding unit 50a and the second holding unit 50a are connected is used, further improvement in durability and smoother linear motion are possible. That is, the planetary shaft is subjected to a force to tilt the planetary shaft, that is, a force to tilt in the circumferential direction by a force acting on the tooth surface of the screw gear. When this force is received by the meshing of the spur gear, the tooth surface is easily worn. Further, when the planetary axis is tilted and the parallel position with the sun axis and the ring axis is shifted, smooth linear motion is hindered. When the cage 50 in which the first holding unit 50 a and the second holding unit 50 a are connected is used, the planetary shaft 30 can be prevented from falling in the circumferential direction, and the planetary shaft 30 and the sun shaft 40 and the ring shaft 20 are parallel to each other. Since the position can be maintained, further improvement in durability and smoother linear motion can be achieved.

  Next, a specific example of Example 1 will be described.

<Specific example 1>
In the following Table 1, the number of teeth of the spur gear of the sun gear, the planetary gear, and the ring gear constituting the first planetary gear mechanism, and the threaded sun gear, the screwed planetary gear constituting the second planetary gear mechanism, The number of spiral teeth of the threaded ring gear (the number of spiral teeth included in one pitch in the rotation axis direction) is shown. In this example, the relative rotation input between the sun axis (shaft) and the ring axis (nut) does not cause the ring axis and planetary axis to move linearly, and the sun axis is linear with respect to the ring axis and planet axis. It is an example of the 1st case which causes displacement in a direction.
In the table, “sun” indicates a sun gear or a threaded sun gear. “Planet” indicates a planetary gear or a screw-type planetary gear. “Internal tooth” indicates a ring gear or a threaded ring gear. “Spur tooth” indicates the number of teeth of the spur gear of the sun gear, the planetary gear, and the ring gear. The “threaded gear” indicates the number of spiral teeth of the threaded sun gear, the threaded planetary gear, and the threaded ring gear.

  In this example, the sun gear, planetary gear, and ring gear that constitute the first planetary gear mechanism have 31 teeth, 10 teeth, and 50 teeth, respectively. The threaded sun gear, the threaded planetary gear, and the threaded ring gear constituting the second planetary gear mechanism have four, one, and five in order.

  In the sun shaft, the spur gear of the sun gear and the tooth surface of the screw gear are formed by the side surface of the sun shaft convex portion which is a convex protrusion. In the planetary shaft, the spur gear of the planetary gear and the tooth surface of the screw-shaped gear are formed by the side surface of the concave portion of the planetary shaft that is a concave depression. As a method for realizing these shapes, there is a mass productivity that is a rolling process. Since the gear has a small outer diameter and can be processed with a relatively short length, it is suitable for sheet rolling.

  The ring shaft is formed with a ring shaft convex portion similar to the sun shaft. The ring shaft convex portion is formed by drawing, honing, shaving processing, broaching processing, and threaded gear teeth to form a spur gear tooth surface. It can be formed by combining with screw processing for forming a surface.

  Looking at the ratio of the number of teeth and the ratio of the number of strips in Table 1, in this example, the ratio of the planetary gear to the internal teeth is 1: 5 for both the spur gear and the screw gear. Therefore, the relative displacement in the linear direction between the planet and the internal teeth does not occur due to the rotation. However, the ratio of the number of teeth between the sun and the internal teeth is 31:50 for spur gears and 4: 5 for screw gears. This difference creates a linear displacement between the sun and internal teeth.

  The number of planets arranged is the common divisor of the sum of the sun and the number of teeth or the number of teeth of the inner teeth. As for the sun and the internal teeth, the flat teeth have 31 teeth and 50 teeth, and the screw gear has 4 and 5 threads, so the sum is 81 and 9, respectively. Therefore, the common divisors are 9, 3, and 1, and in this case, the number of arrangement is 9. That is, the divisor of the greatest common divisor 9 is the number of arranged planetary axes.

<Specific example 2>
The following Table 2 shows the number of teeth of the spur gear of the sun gear, planetary gear, ring gear constituting the first planetary gear mechanism, and the threaded sun gear, screwed planetary gear constituting the second planetary gear mechanism, The number of spiral teeth of the threaded ring gear (the number of spiral teeth included in one pitch in the rotation axis direction) is shown. In this example, the sun gear and the planetary shaft do not move in the linear direction with respect to the relative rotational input of the sun shaft (shaft) and the ring shaft (nut), and the ring shaft is in the linear direction with the sun axis and the planetary axis. It is an example of the 2nd case which causes a displacement.
“Sun”, “planet”, “inner tooth”, “spur tooth”, and “screw gear” in the table are the same as in Table 1.

  In this example, the spur teeth of the sun gear, the planetary gear, and the ring gear that constitute the first planetary gear mechanism have 30 teeth, 10 teeth, and 51 teeth, respectively. The threaded sun gear, the threaded planetary gear, and the threaded ring gear that constitute the second planetary gear mechanism have three, one, and six strips in this order.

  Regarding Table 2, the ratio of the number of teeth and the ratio of the number of streaks indicate that in this example, the ratio between the spur teeth and the screw gears is 1: 3 for the planet and the sun. So by rotation. There is no linear displacement between the planet and the sun. However, the ratio of the number of teeth between the sun and the internal teeth is 30:51, and the screw-shaped gear is 3: 6. The This difference creates a linear displacement between the sun and internal teeth.

  It should be noted that the number of teeth and the number of teeth of the planetary gear are the same as those in the first specific example described above for both the spur and the screw-shaped gear. Therefore, considering processing by rolling, a common planet can be used in different forms (specific examples 1 and 2), so the burden on the mold becomes easier and can be manufactured at low cost.

  <Embodiment 2> A planetary rotation-linear motion conversion device 10a according to Embodiment 2 will be described with reference to FIGS.

  The planetary rotation-linear motion conversion device 10a according to the second embodiment is configured in substantially the same manner as the planetary rotation-linear motion conversion device 10 according to the first embodiment. Below, it demonstrates centering around difference with Example 1, and uses the same code | symbol for the part similar to Example 1. FIG.

  In the planetary rotation-linear motion conversion device 10a of the second embodiment, similarly to the first embodiment, the sun shaft convex portion and the ring shaft convex portion are engaged with the planet shaft concave portion, and the respective side surfaces are in contact with each other. A first planetary gear mechanism is configured by each pair of side surfaces, and a second planetary gear mechanism is configured by the other pair of side surfaces.

  However, in the first embodiment, the sun gear, the planetary gear, and the ring gear constituting the first planetary gear mechanism are spur gears, whereas in the second embodiment, they are helical gears. The second planetary gear mechanism is constituted by a screw gear as in the first embodiment. The gear ratio of the helical gear and the thread ratio of the screw gear are selected in the same manner as in the first embodiment.

  Specifically, as shown in FIG. 4 which is a cross-sectional view of the planetary shaft 30a of the planetary rotation-linear motion conversion device 10a, the outer peripheral surface 34a of the main body 32a of the planetary shaft 30a has a radial direction from the outer peripheral surface 34a. A plurality of planetary shaft recesses 36a retracting inward are formed apart from each other. The planetary shaft recess 36a has two pairs of side surfaces and a bottom surface.

  The pair of side surfaces of the planetary shaft recess 36a intermittently forms a tooth surface of a helical gear. In other words, the planetary shaft 30a is connected to the rotation axis 40x along the outer peripheral surface 34a of the main body 32a with an interval and a space, and is arranged at equal intervals in the circumferential direction. The pair of side surfaces serve as tooth surfaces of the “planetary gear constituting the first planetary gear mechanism” of the present invention.

  As with the first embodiment, the other pair of side surfaces of the planetary shaft recess 36 intermittently forms a tooth surface of a screw gear having helical teeth. In other words, the planetary shaft 30a is continuous with an interval along the outer peripheral surface 34a of the main body 32a. The other pair of side surfaces serve as tooth surfaces of the “threaded planetary gear constituting the second planetary gear mechanism” of the present invention.

  Although not shown, similarly, on the inner peripheral surface of the ring shaft, a plurality of ring shaft convex portions protruding radially inward from the inner peripheral surface are formed apart from each other. The pair of side surfaces of the ring shaft convex portion 26 intermittently forms a tooth surface of the helical gear. The other pair of side surfaces of the ring shaft convex portion intermittently forms a tooth surface of a screw gear having spiral teeth.

  In addition, a plurality of sun shaft convex portions protruding radially outward from the outer surface of the sun shaft are formed on the outer surface of the sun shaft so as to be separated from each other. The pair of side surfaces of the sun shaft convex portion intermittently forms the tooth surface of the helical gear. The other pair of side surfaces of the sun shaft convex portion intermittently forms a tooth surface of a screw gear having spiral teeth.

  The overlapping gear ratio can be increased by changing the sun gear, planetary gear, and ring gear from a spur gear to a helical gear. Since the planetary shaft has a long rod shape, the overlap meshing rate can be easily secured to 1 or more, and smooth rotation can be realized.

  The relationship of the twist direction of the tooth of the sun gear, the planetary gear, and the ring gear is the same as that used in the gears of a normal planetary mechanism. In other words, the twisting direction of the teeth of the sun gear and the twisting direction of the teeth of the planetary gear are opposite directions, and the twisting direction of the teeth of the ring gear and the twisting direction of the teeth of the planetary gear are the same.

  Similarly, the twisting direction of the spiral teeth of the threaded sun gear and the twisting direction of the spiral teeth of the threaded planetary gear are opposite to each other, and the twisting direction of the spiral teeth of the threaded ring gear and the threaded planetary gear. The twisting direction of the helical teeth of the gear is the same direction.

  The twisting direction of the teeth of the sun gear, the planetary gear and the ring gear and the twisting direction of the spiral teeth of the threaded sun gear, the threaded planetary gear and the threaded ring gear may be the same direction. The direction can be reversed, but the direction is preferably reversed.

  For example, as shown in FIG. 5, the helical angle of the helical gear tooth surfaces 61 and 63 formed by a pair of side surfaces of the planetary shaft recess 36a is α, and the other pair of side surfaces of the planetary shaft recess 36a is formed. When the twist angle of the tooth surfaces 62 and 64 of the helical gear is β, the twist direction of the helical gear tooth surfaces 61 and 63 and the twist direction of the screw gear tooth surfaces 62 and 64 are opposite to each other. In some cases, the angles 66 and 67 at the four corners of the planetary shaft recess 36a are 90 ° ± (α−β), which is 90 ° compared to the angle 90 ° ± (α + β) at the four corners when the twist direction is the same. It gets closer to the degree. Therefore, stress concentration near the four corners of the planetary shaft recess 36a is alleviated, and the durability of the planetary shaft is improved. Similarly, the stress concentration in the vicinity of the four corners of the sun shaft convex portion and the ring shaft convex portion is alleviated, so that the durability of the sun shaft and the ring shaft is improved.

  In addition, the force acting on the circumferential surface of the planetary shaft is exerted by the load acting on the tooth surface of the threaded planetary gear, but the torsional direction of the planetary gear is opposite to that of the threaded planetary gear. Thus, the load can be offset by the load acting on the tooth surface of the helical gear. This reduces planetary shaft wear.

  Therefore, the helical direction of the helical gear of the planetary gear and the helical direction of the helical tooth of the screw-like planetary gear are opposite to each other. It is preferable that the twisting direction of the teeth is opposite to each other, and the twisting direction of the helical teeth of the ring gear and the twisting direction of the helical teeth of the threaded ring gear are opposite to each other.

  The planetary rotation-linear motion conversion device 10a according to the second embodiment can be easily assembled by the same method as the planetary rotation-linear motion conversion device 10 according to the first embodiment. By integrating the screw gear and the helical gear, the number of parts can be reduced and the cost can be reduced. In addition, by forming a planetary shaft concave portion on the planetary shaft, the planetary shaft has higher rigidity than the case where a convex portion protruding radially outward is formed on the outer peripheral surface of the planetary shaft, thereby suppressing the twisting of the planetary shaft. As a result, durability and smooth linear motion are possible.

  <Summary> As described above, the sun shaft convex portion, the planetary shaft concave portion, and the ring shaft convex portion forming the tooth surfaces of the spur gear or the helical gear and the screw gear are formed on the sun shaft, the planetary shaft, and the ring shaft. And (b) the number of parts can be reduced and the cost can be reduced by configuring the planetary shaft concave portion, the sun shaft convex portion and the ring shaft convex portion to mesh with each other. It is possible to suppress the torsion of the shaft and improve durability and convert from smooth rotational motion to linear motion.

  The present invention is not limited to the above embodiment, and can be implemented with various modifications.

DESCRIPTION OF SYMBOLS 10,10a Planetary rotation-linear motion converter 20 Ring shaft 20x Rotation axis 22 Main body 24 Inner surface 26 Ring shaft convex part 27a, 27b Inner surface 27s, 27t Groove 28 Flange 29 Through-hole 30, 30a Planetary shaft 30x Rotation Axis 32, 32a Body 34, 34a Outer peripheral surface 36, 36a Planetary shaft concave portion 40 Sun shaft 40x Rotating axis 42 Outer peripheral surface 44 Solar shaft convex portion 50 Cage 50a First holding portion 50b Second holding portion 52 Retaining member

Claims (4)

A sun axis having a rotation axis parallel to each other, a plurality of planet axes, a ring axis,
A holder that rotatably holds the planetary shaft and is rotatable with respect to the sun axis and the ring axis;
With
On the outer peripheral surface of the planetary shaft, a plurality of planetary shaft recesses that are retreated radially inward from the outer peripheral surface and have two pairs of side surfaces are formed apart from each other
The outer peripheral surface of the sun shaft protrudes radially outward from the outer peripheral surface, has two pairs of side surfaces, and a plurality of sun shaft convex portions that mesh with the planetary shaft concave portion are formed apart from each other,
The inner circumferential surface of the ring shaft protrudes radially inward from the inner circumferential surface, has two pairs of side surfaces, and a plurality of ring shaft convex portions that mesh with the planetary shaft concave portion are formed apart from each other,
A pair of side surfaces of the planetary shaft concave portion, the sun shaft convex portion, and the ring shaft convex portion are, in order, a spur gear or a helical gear, and cooperate with each other to constitute a first planetary gear mechanism, The tooth surfaces of planetary gears and ring gears are formed intermittently,
The other pair of side surfaces of the planetary shaft concave portion, the sun shaft convex portion, and the ring shaft convex portion are screw gears having helical teeth in this order and cooperate with each other to constitute a second planetary gear mechanism. The tooth surfaces of the threaded sun gear, threaded planetary gear, and threaded ring gear are intermittently formed,
The ratio of the number of teeth of the spur gear or the helical gear of the sun gear to the planetary gear is different from the ratio of the number of helical teeth of the threaded sun gear to the screw planetary gear, and the ratio to the planetary gear is The gear ratio of the spur gear or the helical gear of the ring gear is equal to the gear ratio of the helical teeth of the screw ring gear to the screw planetary gear,
Alternatively, the ratio of the number of teeth of the spur gear or the helical gear of the sun gear to the planetary gear is equal to the ratio of the number of helical teeth of the screw-shaped sun gear to the screw-shaped planetary gear, and the planetary gear. A planetary rotation-linear line characterized in that the ratio of the number of teeth of the spur gear or the helical gear of the ring gear to the number of spiral teeth of the screw-shaped ring gear with respect to the screw-type planetary gear is different Motion conversion device. The sun gear, the planet gear, and the ring gear constituting the first planetary gear mechanism are helical gears,
The direction of twisting of the teeth of the planetary gear and the direction of twisting of the helical teeth of the threaded planetary gear are opposite to each other,
The twist direction of the teeth of the sun gear and the twist direction of the spiral teeth of the threaded sun gear are opposite to each other,
2. The planetary rotation-linear motion conversion device according to claim 1, wherein the twisting direction of the teeth of the ring gear and the twisting direction of the spiral teeth of the threaded ring gear are opposite to each other. . The cage is
A first holding portion that rotatably holds one end side of the planetary shaft, and is rotatable with respect to the sun shaft and the ring shaft;
A second holding portion that rotatably holds the other end of the planetary shaft and is rotatable with respect to the sun shaft and the ring shaft;
A plurality of connecting portions arranged between the planet gears adjacent to each other, fixed to the first holding portion and the second holding portion, and preventing relative rotation between the first holding portion and the second holding portion. When,
The planetary rotation-linear motion conversion device according to claim 1 or 2, characterized by comprising: The gear ratio of the spur gear or the helical gear of the sun gear to the planetary gear is equal to the gear ratio of the helical teeth of the screw sun gear to the screw planetary gear, and the gear ratio to the planetary gear is The ratio of the number of teeth of the spur gear or the helical gear of the ring gear is different from the ratio of the number of helical teeth of the threaded ring gear to the threaded planetary gear,
4. The planetary rotation-linear motion conversion according to claim 1, wherein the ring axis moves relative to the planetary axis and the sun axis in parallel with the rotation axis. 5. apparatus.