JP2010019282A - Planetary differential type motion converting mechanism and power device having the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a planetary differential type motion converting mechanism and a power device having the planetary differential type motion converting mechanism capable of restraining the occurrence of partial abrasion and a chipped part in a screw formed on a planetary shaft and a screw meshing with the screw caused when the planetary shaft inclines. <P>SOLUTION: This planetary differential type motion converting mechanism 100 is used in a state of always making a load F act on a sun shaft 20. The planetary differential type motion converting mechanism 100 is divided into a differential screw 21a in which the screw arranged on the sun shaft 20 is displaced in the axial direction according to the rolling of the planetary shaft 30 and a non-differential screw 21b in which the screw is not displaced in the axial direction according to the rolling of the planetary shaft 30. The non-differential screw 21b is installed non-rotatable with respect to a sun shaft body 20a and slidable in the axial direction between the differential screw 21a in the sun shaft body 20a and a rear side sun gear 22b positioned in the opposite direction of the action direction of the load F. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention includes an annular rotor, a sun shaft inserted in the rotor, and a planetary shaft interposed between the rotor and the sun shaft, and screws formed on these members and meshing with each other. The present invention relates to a planetary differential motion conversion mechanism that converts the rotational motion of a rotor into a linear motion of a sunshaft by using the action of the above, and a power device including the same.

  A power converter that displaces the control shaft in the axial direction using the rotational force of the motor is equipped with a motion conversion mechanism that converts the rotational motion of the motor into linear motion of the control shaft. For example, as such a motion conversion mechanism, in Patent Document 1, a sun shaft is inserted into an annular rotor that is rotationally driven by a motor, and a plurality of planetary shafts are interposed between the rotor and the sun shaft. A planetary differential motion conversion mechanism is described in which screws provided on the respective members are engaged with each other.

  This planetary differential motion conversion mechanism has a so-called differential screw, and the lead angles of the screw formed on the planetary shaft and the screw formed on the sun shaft are different. As a result, when the planetary shaft rolls on the outer peripheral surface of the sun shaft as the rotor rotates, the sun shaft is displaced in the axial direction by the difference in the lead angle.

In such a planetary differential motion conversion mechanism, a pair of planetary gears are provided at both ends of the planetary shaft so as to sandwich the screw formed on the planetary shaft, and a sun gear formed on the outer peripheral surface of the sunshaft These are meshed with both ring gears formed on the inner peripheral surface of the rotor, and the rotational force of the rotor is transmitted to the planetary shaft via these gears. According to such a configuration, since the rotational force is reliably transmitted via the gear, the slippage at the meshing portion of the screw is suppressed, and the efficiency of converting the rotational motion of the rotor to the linear motion of the sun shaft is improved. be able to.
JP 2007-177912 A

  By the way, when a planetary differential motion conversion mechanism is used under a situation where an axial load is applied to the sun shaft, it is rotated by a planetary shaft interposed between the rotor and the sun shaft. The acting force acts, and the planetary shaft tilts between the rotor and the sun shaft.

  Specifically, when a load F acts on the sun shaft 20 toward the right side of FIG. 8 as indicated by an arrow on the right side of FIG. 8, the screw of the sun shaft 20 in the screw 31 of the planetary shaft 30. A load f1 in the direction toward the right side in FIG. On the other hand, a load f <b> 2 in the direction toward the left side in FIG. 8 acts on the portion of the screw 31 of the planetary shaft 30 that meshes with the screw 11 of the rotor 10 due to the resistance force received from the rotor 10. As a result, the planetary shaft 30 is subjected to a force that rotates the planetary shaft 30 counterclockwise as indicated by an arrow in the center of FIG.

  When the planetary shaft 30 is tilted by the action of the rotational force, a portion (enclosed by a broken line in FIG. 8) located on the acting direction side of the load F in the portion where the screw 11 of the rotor 10 and the screw 31 of the planetary shaft 30 are in contact with each other. In the part X), these screws come into contact with each other in an inclined state and come into contact with each other. As a result, uneven wear and loss of the screw are likely to occur at this portion, and the durability of the planetary differential motion conversion mechanism may be reduced.

  Further, the screw 21 of the sunshaft 20 prevents the screw threads of the screw 21 from coming into contact with the planetary gears 32 a and 32 b formed at both ends of the planetary shaft 30 when the sunshaft 20 is displaced in the axial direction. As shown in FIG. 8, the overall length is set shorter than that of the screw 11 and the screw 31. Therefore, as shown in FIG. 8, when the sun shaft 20 is extended in the direction in which the load F acts, the portion of the planetary shaft 30 opposite to the load F in the screw 31 (enclosed by a broken line in FIG. 8). In the part Y), the support by the screw 21 of the sun shaft 20 is lost. For this reason, when the sun shaft 20 is being extended in the direction in which the load F is applied in this way, the planetary shaft 30 is particularly inclined due to the action of the rotational force described above, and uneven wear and defects of the screw are generated. Becomes more prominent.

  The present invention has been made in view of the above circumstances, and the purpose thereof is that uneven wear and defects occur in the screw formed on the planetary shaft and the screw meshing with the screw due to the inclination of the planetary shaft. It is an object of the present invention to provide a planetary differential motion conversion mechanism capable of suppressing the above-described problem, and a power device including the planetary differential motion conversion mechanism.

In the following, means for achieving the above object and its effects are described.
According to the first aspect of the present invention, a plurality of planetary shafts are interposed between an annular rotor and a sun shaft inserted in the rotor, and a pair of planetary gears provided at both ends of the planetary shaft are provided. A pair of ring gears provided on the inner peripheral surface of the rotor and a pair of sun gears provided on the outer peripheral surface of the sun shaft respectively mesh with each other, and the pair of planetary gears on the outer peripheral surface of the planetary shaft The planetary shaft screw is engaged with each other by engaging the screw provided between the screw provided on the inner peripheral surface of the rotor and the screw provided on the outer peripheral surface of the sun shaft. The rotational motion of the rotor is changed to a straight line of the sun shaft by utilizing the difference between the lead angle of the sun shaft and the lead angle of the screw of the sun shaft meshing with the lead angle. In the planetary differential motion conversion mechanism for converting motion, the planetary differential motion conversion mechanism is used under a situation in which a load directed to one of the axial directions is always applied to the sun shaft. The screw of the shaft is different in the lead angle from the screw of the planetary shaft to be engaged, and the differential screw portion that is displaced in the axial direction as the planetary shaft rolls, and the screw and the lead angle of the screw of the planetary shaft to be engaged are equal. In the sun shaft main body, which is divided into a non-differential screw portion that is not displaced in the axial direction as the planetary shaft rolls, and the non-differential screw portion is fixed to the differential screw portion and the pair of sun gears. Between the differential screw portion and the sun gear located on the opposite side of the load acting direction, relative rotation with respect to the sun shaft main body is impossible and sliding in the axial direction is possible. Capable to be attached comprising as its gist.

  According to the above configuration, the non-differential screw portion is attached so as not to be rotatable relative to the sun shaft and slidable in the axial direction, and so as not to be displaced in the axial direction as the planetary shaft rolls. The lead angle is set. Therefore, the non-differential screw portion slides in the axial direction with respect to the sunshaft main body even when the sunshaft main body is displaced in the axial direction as the planetary shaft rolls. In other words, the position is maintained without being displaced in the axial direction. Therefore, according to the configuration of the first aspect, even when the sunshaft body is extended in the load acting direction and the differential screw portion is displaced toward the load acting direction, there is no difference. The moving screw portion is held at a position opposite to the direction of the load. This makes it possible to always support the portion of the planetary shaft on the side opposite to the direction in which the load acts regardless of the axial position of the sunshaft body by the non-differential screw portion. Can be suitably suppressed. That is, according to the first aspect of the present invention, it is possible to suppress the occurrence of uneven wear and defects in the screw formed on the planetary shaft and the screw meshing with the screw due to the inclination of the planetary shaft. Will be able to.

  According to a second aspect of the present invention, in the planetary differential motion conversion mechanism according to the first aspect, the screw provided on the planetary shaft is configured so that the non-differential screw portion is engaged with the differential screw portion. Is formed as one screw portion having a uniform lead angle over a portion meshing with the planetary shaft, and the differential screw portion is set so that the lead angle is different from the lead angle of the screw of the planetary shaft. The non-differential screw has a lead angle that is set equal to the lead angle of the planetary shaft screw so that the planetary shaft rolls. The gist of the present invention is that it is formed so as not to be displaced in the axial direction.

  Specifically, the lead angle of the differential screw portion is made different from that of the planetary shaft screw whose lead angle is set uniformly over the entire length as in the invention described in the second aspect of the invention. The differential screw portion is displaced in the axial direction as the planetary shaft rolls by setting the lead angle of the dynamic screw portion to be equal, while the non-differential screw portion is not displaced in the axial direction. The configuration of the invention can be embodied.

  According to a third aspect of the present invention, in the planetary differential motion conversion mechanism according to the first or second aspect, the non-differential screw is on a side opposite to a direction in which the load acts on the planetary shaft screw. The gist of the present invention is that it is assembled so as to mesh with the screw of the planetary shaft at the end of the.

  According to the said structure, the screw of a planetary shaft is always supported by the non-differential screw part in the edge part on the opposite side to the action direction of the said load. As a result, the planetary shaft is supported at a position away from a position serving as a fulcrum of the rotational force acting on the planetary shaft due to the action of the load. Therefore, according to the structure of the said Claim 3, the inclination of a planetary shaft can be more effectively suppressed now by a non-differential screw part.

  According to a fourth aspect of the present invention, the planetary differential motion conversion mechanism according to any one of the first to third aspects is provided, and the sun shaft is pivoted by rotating the rotor by a driving force of a motor. It is a power unit that is displaced in the direction.

  Specifically, the planetary differential motion conversion mechanism according to any one of claims 1 to 3 as described above is combined with a motor that rotates the rotor, and the sun shaft is axially utilized using the rotational force of the motor. It is applied to the power equipment to be displaced.

  The invention according to claim 5 is combined with a valve characteristic changing mechanism of an internal combustion engine that changes the maximum lift amount and lift period of the engine valve in accordance with the axial displacement of the control shaft, and the sunshaft is used as the control shaft. The power unit according to claim 4, wherein the power unit is applied as a power unit that displaces the control shaft in an axial direction by being connected.

  The control shaft of the valve characteristic changing mechanism of the internal combustion engine that changes the maximum lift amount and the lift period of the engine valve is displaced in a direction to reduce the maximum lift amount and the lift period of the engine valve by the reaction force of the valve spring. A load always acts. For this reason, in a power unit that drives the control shaft of such a valve characteristic changing mechanism, a load in one direction always acts on the sun shaft connected to the control shaft, and the durability resulting from the action of this load The decrease in the value becomes particularly remarkable. Therefore, as in the invention described in claim 5, it is desirable to apply the power apparatus described in claim 4 as the power apparatus of such a valve characteristic changing mechanism.

  Hereinafter, a planetary differential motion conversion mechanism according to the present invention is mounted on a power device that drives a valve characteristic changing mechanism that changes the maximum lift amount and lift period of an intake valve of an internal combustion engine. One embodiment embodied as will be described with reference to FIGS.

  FIG. 1 is a cross-sectional view showing the internal structure of the planetary differential motion conversion mechanism 100 according to the present embodiment. In the following description, the right side in FIG. 1 is described as the front side in the planetary differential motion conversion mechanism 100, and the left side in FIG. 1 is described as the rear side.

  As shown in FIG. 1, the planetary differential motion conversion mechanism 100 of the present embodiment has a sun shaft 20 inserted into a cylindrical rotor 10 and a plurality of planetary shafts between the sun shaft 20 and the rotor 10. 30 is interposed. In the planetary differential motion conversion mechanism 100 of the present embodiment, nine planetary shafts 30 are disposed at equal angular intervals so as to surround the sun shaft 20.

  Hereinafter, the internal structure of the planetary differential motion conversion mechanism 100 will be described in more detail. As shown in FIG. 1, the inner periphery of the rotor 10 is formed with a screw 11 composed of five left-hand screws that advance counterclockwise from the front side toward the rear side. Further, a front side ring gear 12 a and a rear side ring gear 12 b are fixed to the inner peripheral surface of the rotor 10 so as to sandwich the screw 11. Each of the ring gears 12 a and 12 b is a spur gear whose teeth are extended along the extending direction of the central axis of the rotor 10.

  On the other hand, on the outer peripheral surface of the sunshaft 20 inserted in the rotor 10, four right-hand screws that advance clockwise from the front side to the rear side at positions facing the screws 11 formed in the rotor 10. The differential screw part 21a which consists of is formed. A front-side sun gear 22a and a rear-side sun gear 22b are formed on the outer peripheral surface of the sun shaft 20 so as to sandwich the differential screw portion 21a. Each of the sun gears 22 a and 22 b is a spur gear that has a tooth line extending along the extending direction of the central axis of the sun shaft 20.

  Further, as shown in FIG. 1, a non-differential screw portion 21b composed of three right-hand screws is provided between the rear-side sun gear 22b and the differential screw portion 21a in the sun shaft 20. The non-differential screw portion 21b is attached to the sun shaft body 20a to which the differential screw portion 21a and the sun gears 22a and 22b are fixed so as not to rotate and to be slidable in the axial direction. Specifically, the slide shaft portion 20b into which the non-differential screw portion 21b is extrapolated in the sun shaft main body 20a has a quadrangular cross-sectional shape as shown in FIG. 2 is a cross-sectional view taken along the line AA in FIG. As shown in FIG. 2, the non-differential screw portion 21b has a rectangular bearing hole 25 formed slightly larger than the slide shaft portion 20b, and the slide shaft portion 20b is formed in the bearing hole 25. Is attached to the sun shaft main body 20a so as not to rotate and to be slidable in the axial direction.

  As shown in FIG. 1, the outer peripheral surface of each planetary shaft 30 interposed between the sun shaft 20 to which the non-differential screw portion 21 b is attached and the rotor 10 is disposed on the inner peripheral surface of the rotor 10. A screw 31 is formed that meshes with both the screw 11 formed on the outer peripheral surface of the sun shaft 20 and the differential screw portion 21a and the non-differential screw portion 21b formed on the outer peripheral surface of the sun shaft 20. The screw 31 is a single left-hand screw that proceeds counterclockwise from the front side toward the rear side.

  Further, as shown in FIG. 1, each planetary shaft 30 is formed with a front planetary gear 32a at the front end and a rear planetary gear 32b at the rear end so as to sandwich the screw 31. Has been. Each of the planetary gears 32 a and 32 b is a spur gear that has a tooth line extending along the direction of extension of the central axis of the planetary shaft 30. The front planetary gear 32 a meshes with both the front ring gear 12 a formed on the rotor 10 and the front sun gear 22 a formed on the sun shaft 20, and the rear planetary gear 32 b is formed on the rotor 10. The rear side ring gear 12b and the rear side sun gear 22b formed on the sun shaft 20 are meshed with each other.

  In the planetary shaft 30, the rear planetary gear 32 b is formed so as to be detachable from the shaft body 35 of the planetary shaft 30. Specifically, as shown in FIG. 1, the planetary shaft 30 includes a shaft main body 35 in which a screw 31 and a front planetary gear 32a are integrally formed, and a rear planetary gear 32b. The rear planetary gear 32b is formed with a bearing hole 34 that extends along the central axis thereof. On the other hand, the shaft body 35 has a shaft portion that is inserted into the bearing hole 34 at the tip of the screw 31 side. 33 is provided. Thereby, in the planetary shaft 30, the rear planetary gear 32b and the shaft main body 35 are connected by inserting the shaft part 33 formed in the shaft main body 35 into the bearing hole 34 of the rear planetary gear 32b. Yes.

  Further, in the planetary differential motion conversion mechanism 100 of the present embodiment, as shown on the left side of FIG. 1, the lid 40 that closes the rotor 10 is fitted to the rear end of the rotor 10. . As shown in FIG. 1, the lid body 40 is disposed so as to face the rear planetary gear 32 b by being fitted to the inner peripheral surface of the rotor 10, and closes the rear-side opening portion of the rotor 10. This prevents the rear planetary gear 32b from falling off.

  In the planetary differential motion conversion mechanism 100 of the present embodiment configured as described above, each of the rotor 10, the sun shaft 20, and the planetary shaft 30 is mutually connected via a screw and a gear formed on each member. Meshed. Therefore, by rotating the rotor 10 relative to the sun shaft 20, the rotational force of the rotor 10 is transmitted to the planetary shaft 30 through these screws and gears, and the planetary shaft 30 is connected to the inner peripheral surface of the rotor 10. It rolls along the outer peripheral surface of the sun shaft 20.

  Here, in the screw 11 of the rotor 10 and the screw 31 of the planetary shaft 30, the ratio of the pitch circle diameter and the ratio of the number of screw threads are both set to “5: 1”. Thus, the lead angles of the screw 11 of the rotor 10 and the screw 31 of the planetary shaft 30 are the same. Therefore, when the planetary shaft 30 rolls along the inner peripheral surface of the rotor 10, no relative axial displacement occurs between the rotor 10 and the planetary shaft 30.

  Further, in the screw 31 of the planetary shaft 30 and the non-differential screw portion 21b of the sun shaft 20, both the pitch circle ratio and the screw thread ratio are set to "1: 3". Thereby, even if it exists in the screw 31 of the planetary shaft 30, and the non-differential screw part 21b of the sun shaft 20, the lead angle is equal. Therefore, when the planetary shaft 30 rolls along the outer peripheral surface of the sun shaft 20, no relative displacement in the axial direction occurs between the planetary shaft 30 and the non-differential screw portion 21b.

  On the other hand, in the screw 31 of the planetary shaft 30 and the differential screw portion 21a of the sun shaft 20, the ratio of the pitch circle diameter is different from the ratio of the number of screw threads. Specifically, while the ratio of the pitch circle diameters is set to “1: 3”, the number of screw threads of the screw 31 of the planetary shaft 30 is one, and the differential screw of the sun shaft 20. Since the number of screw threads of the portion 21a is 4, the ratio of the number of screw threads is set to “1: 4”. As a result, the differential screw portion 21a of the sun shaft 20 and the screw 31 of the planetary shaft 30 have different lead angles, and when the planetary shaft 30 rolls along the outer peripheral surface of the sun shaft 20, this lead The differential screw portion 21a and the planetary shaft 30 are displaced in the axial direction by the difference in angle, and the relative position thereof changes.

  In short, in the planetary differential motion conversion mechanism 100, the planetary shaft 30 moves along the inner peripheral surface of the rotor 10 and the outer peripheral surface of the sun shaft 20 by rotating the rotor 10 relative to the sun shaft 20. The sunshaft 20 is displaced in the axial direction as the differential screw portion 21a is displaced by the difference in the lead angle. Therefore, the rotational motion input to the rotor 10 can be converted into the linear motion of the sun shaft 20 and output through the planetary differential motion conversion mechanism 100. At this time, no relative displacement occurs between the non-differential screw portion 21 b and the planetary shaft 30, so the non-differential screw portion 21 b slides relative to the sunshaft main body 20 a and moves relative to the planetary shaft 30. The position is maintained without being relatively displaced.

  Hereinafter, an assembling method of the planetary differential motion conversion mechanism 100 of this embodiment will be described with reference to FIGS. FIG. 3 is an exploded perspective view of the sun shaft 20. As shown in FIG. 3, the sun shaft body 20a is provided with a front sun gear 22a and a differential screw portion 21a. The portion on the rear side of the differential screw portion 21a in the sun shaft main body 20a is the slide shaft portion 20b having a quadrangular cross section as described above, and the tip portion thereof is fitted with a smaller diameter than the slide shaft portion 20b. It is a shaft portion 20c.

  As shown by a broken line in FIG. 3, a non-differential screw portion 21b is extrapolated to the slide shaft portion 20b of the sun shaft main body 20a, and the rear-side sun gear 22b is fitted to the fitting shaft portion 20c. The inner diameter of the bearing hole 26 formed in the rear sun gear 22b is set to be approximately equal to the outer diameter of the fitting shaft portion 20c. Then, the rear-side sun gear 22b is fixed to the sun shaft main body 20a so as not to be rotatable and slidable in a state where the rear sun gear 22b is fitted to the fitting shaft portion 20c, so that the non-differential screw portion 21b is fixed to the sun shaft main body 20a. Completes the assembly of the sunshaft 20 that is non-rotatable and slidably mounted.

  Next, as shown in FIG. 4, the shaft body 35 with the rear planetary gear 32b removed is disposed around the sunshaft 20 thus assembled, and the front sun gear 22a and the front planetary gear 32a are connected. At the same time, the screw 31 is engaged with the differential screw portion 21 a and the non-differential screw portion 21 b of the sun shaft 20. At this time, the position of the non-differential screw portion 21b is adjusted so that the non-differential screw portion 21b meshes with the rear side end portion of the screw 31, and these are engaged.

  As shown in FIG. 3, the sun shaft 20 and the shaft main body 35 are covered with the rotor 10 from the rear side in this state, and the screw 11 is screwed into the screw 31 of the shaft main body 35 while rotating the rotor 10.

  After the sun shaft 20, the shaft main body 35, and the rotor 10 are engaged with each other and assembled together, the front side ring gear 12a and the rear side ring gear 12b are respectively attached to the inner peripheral surface of the rotor 10 as shown in FIG. Fix it. Then, after attaching the ring gears 12a and 12b, as shown in FIG. 5, the rear side planetary gear 32b is engaged with the rear side planetary gear 32b while engaging the rear side planetary gear 32b with both the rear side ring gear 12b and the rear side sun gear 22b. The shaft portion 33 of the shaft main body 35 is inserted into the shaft 34 and these are connected.

  The rear planetary gear 32b is assembled in this way, and the rotor 10, the sun shaft 20 and the planetary shaft 30 are brought into mesh with each other by the formed gears and screws, and then a lid is attached to the rear end of the rotor 10. The body 40 is fitted. By fixing the lid 40 to the rear side end of the rotor 10 in this way, the assembly of the planetary differential motion conversion mechanism 100 is completed.

  The planetary differential motion conversion mechanism 100 is mounted on a power unit that drives a control shaft of a valve characteristic changing mechanism that changes the maximum lift amount and lift period of an intake valve of an internal combustion engine. Specifically, a permanent magnet is attached on the outer peripheral surface of the rotor 10, and the rotor 10 is configured to function as a rotor of the electric motor. And the front-end | tip part 24 of the sun shaft 20 shown by the right side of FIG.1 and FIG.3 is connected with the control shaft of a valve characteristic change mechanism. The valve characteristic changing mechanism changes the maximum lift amount and the lift period of the engine valve in accordance with the axial displacement of the control shaft. 1 and 3, straight splines 23 are formed on the outer peripheral surface of the sun shaft 20. The straight spline 23 is meshed with a straight spline formed in an opening portion of the casing of the internal combustion engine when the planetary differential motion conversion mechanism 100 is fixed to the internal combustion engine as a power device of the valve characteristic changing mechanism. . Thus, the sun shaft 20 is allowed to move in the axial direction by the action of the straight spline 23, but the rotation is restricted.

  As described above, the planetary differential motion conversion mechanism 100 of the present embodiment is applied to the power device of the valve characteristic changing mechanism and attached to the internal combustion engine, thereby controlling the rotational motion of the motor through the planetary differential motion conversion mechanism 100. It is converted into a linear motion in the axial direction of the shaft, and the axial position of the control shaft can be adjusted. That is, by controlling the rotation amount of the motor, the valve characteristic changing mechanism can be controlled to arbitrarily change the maximum lift amount and the lift period of the intake valve.

  By the way, the control shaft of the valve characteristic changing mechanism of the internal combustion engine that changes the maximum lift amount and the lift period of the engine valve is arranged in a direction to reduce the maximum lift amount and the lift period of the engine valve by the reaction force of the valve spring. The displacement load always acts. Therefore, a unidirectional load F acts on the sun shaft 20 connected to the control shaft, for example, as shown by an arrow in FIG. When the axial load F acts on the sun shaft 20, the planetary shaft 30 is inclined so that the front side end portion is close to the rotor 10 side and the rear side end portion is close to the sun shaft 20 side. The rotational force to act comes to act.

  On the other hand, in the planetary differential motion conversion mechanism 100 of this embodiment, when the planetary shaft 30 rolls on the outer peripheral surface of the sun shaft 20 as the rotor 10 rotates as described above. The non-differential screw portion 21b that does not cause relative displacement in the axial direction between the planetary shaft 30 and the planetary shaft 30 is provided. Therefore, even if the sun shaft 20 is located on the rear side as shown in FIG. 6A, the sun shaft 20 is located on the front side as shown in FIG. 6B. Even in this case, the rear side portion of the planetary shaft 30 is always supported from the inner peripheral side of the planetary differential motion conversion mechanism 100 by the non-differential screw portion 21b.

  Hereinafter, with reference to FIG. 6A and FIG. 6B, the operation of the non-differential screw portion 21b in the planetary differential motion conversion mechanism 100 of the present embodiment will be described in more detail. 6A is a schematic diagram showing a state when the sun shaft 20 of the planetary differential motion conversion mechanism 100 according to the embodiment is located on the rear side, and FIG. It is a schematic diagram which shows a state when the sun shaft 20 is located in the front side. 6 (a) and 6 (b), the difference in the lead angle of each screw is schematically shown by the difference in the inclination angle of the oblique lines.

  As shown in FIG. 6A, the lead angle is different between the screw 31 formed on the planetary shaft 30 and the differential screw portion 21 a of the sun shaft 20. Therefore, when the planetary shaft 30 rolls between the inner peripheral surface of the rotor 10 and the outer peripheral surface of the sun shaft 20 as the rotor 10 rotates, a differential screw portion 21a formed integrally with the sun shaft main body 20a; A relative displacement occurs in the axial direction between the planetary shaft 30 and the sun shaft main body 20a is displaced to the front side as shown in FIG. 6B.

  At this time, as shown in FIG. 6B, the lead angle of the non-differential screw portion 21b slidably attached to the sun shaft main body 20a is set equal to the screw 31 of the planetary shaft 30. Even if the planetary shaft 30 rolls, no axial displacement occurs between the planetary shaft 30 and the planetary shaft 30. Thereby, even when the sun shaft 20 is extended to the front side as shown in FIG. 6B, the non-differential screw portion 21b slides relative to the sun shaft main body 20a, and the planetary shaft 30 The position is held while meshing with the rear side end of the screw 31.

  Thus, in the planetary differential motion conversion mechanism 100 of the present embodiment, even when the sun shaft 20 is displaced in the axial direction, the non-differential screw portion 21b slides relative to the sun shaft main body 20a. And the state which meshed | engaged with the rear side edge part of the screw 31 of the planetary shaft 30 is maintained.

According to the embodiment described above, the following effects can be obtained.
(1) In the planetary differential motion conversion mechanism 100 of the above embodiment, the non-differential screw portion 21b is attached to the sun shaft 20 so as not to rotate relative to the sun shaft 20 and to be slidable in the axial direction. The lead angle is set so as not to be displaced in the axial direction as the planetary shaft 30 rolls. Therefore, the non-differential screw portion 21b slides in the axial direction with respect to the sunshaft body 20a even when the sunshaft body 20a is displaced in the axial direction as the planetary shaft 30 rolls. The planetary shaft 30 is maintained in its position without being displaced in the axial direction. Therefore, even when the sunshaft main body 20a is drawn out in the acting direction of the load F and the differential screw portion 21a is displaced to the acting direction side of the load F, the non-differential screw portion 21b is Is held in the opposite position. As a result, regardless of the position of the sunshaft body 20a in the axial direction, the non-differential screw portion 21b can always support the rear side portion of the planetary shaft 30 opposite to the direction in which the load F acts. Thus, the inclination of the planetary shaft 30 can be suitably suppressed. That is, it is possible to suppress the occurrence of uneven wear and defects in the screw 31 formed on the planetary shaft 30 and the screw 11 meshing with the screw 31 due to the inclination of the planetary shaft 30.

  (2) The screw 31 of the planetary shaft 30 is always supported by the non-differential screw 21b at the rear end opposite to the direction in which the load F acts. As a result, the planetary shaft 30 is supported at a position away from a position serving as a fulcrum of the rotational force acting on the planetary shaft 30 due to the action of the load F. Therefore, the non-differential screw portion 21b can more effectively suppress the inclination of the planetary shaft 30.

  (3) Since the shaft portion 33 of the shaft main body 35 is inserted into the bearing hole 34 of the rear side planetary gear 32b to connect them to form the planetary shaft 30, the bearing hole 34 and the shaft of the rear side planetary gear 32b are connected. A clearance exists between the shaft portion 33 of the main body 35. The existence of such a clearance is also one of the factors that the shaft body 35 of the planetary shaft 30 tends to tilt due to the action of the load F. On the other hand, in the planetary differential motion conversion mechanism 100 of the above-described embodiment, the non-differential screw portion 21b is engaged with the screw 31 in the rear side portion where such clearance exists, and the planetary shaft 30 is The inclination is suppressed. Therefore, it is possible to effectively support the rear side portion of the planetary shaft 30 that is easily inclined toward the inner peripheral side of the planetary differential motion conversion mechanism 100 due to the presence of such clearance, and suppress the inclination. become able to.

In addition, the said embodiment can also be implemented with the following forms which changed this suitably.
In the above embodiment, the configuration in which the non-differential screw portion 21b is arranged so that the non-differential screw portion 21b meshes with the rear side end portion of the screw 31 of the planetary shaft 30 is shown. On the other hand, the non-differential screw portion 21b may be disposed at a position on the rear side of the differential screw portion 21a, that is, a portion on the opposite side to the direction in which the load F acts. However, in order to suitably suppress the inclination of the planetary shaft 30, it is desirable to support the screw 31 of the planetary shaft 30 at a position as far as possible from the fulcrum of the rotational force acting on the planetary shaft 30. Therefore, in order to favorably support the planetary shaft 30 while ensuring both the amount of displacement of the sun shaft 20 and the downsizing of the planetary differential motion conversion mechanism 100, it acts on the planetary shaft 30 as in the above embodiment. It is desirable to dispose the non-differential screw portion 21b so as to mesh with the screw 31 at the rear side end portion that is farthest from the fulcrum of the rotational force to be generated.

  7A, the lead angles of the differential screw portion 21a and the non-differential screw portion 21b formed on the sun shaft 20 are made equal, and the screw 31 of the planetary shaft 30 is replaced with the differential screw portion. It is also possible to adopt a configuration in which the first screw portion 31a meshing with 21a and the second screw portion 31b meshing with the non-differential screw portion 21b are divided. In this case, the first screw portion 31a is formed so as to have a different lead angle from the differential screw portion 21a in the same manner as the screw 31 of the above embodiment, while the second screw portion 31b is formed with the non-differential screw portion 21b. The lead angles are formed to be equal.

  Even in the case of adopting such a configuration, the lead angles of the second screw portion 31b and the non-differential screw portion 21b are set to be equal, so that the planetary shaft 30 rolls as shown in FIG. Accordingly, when the differential screw portion 21a is displaced in the axial direction and the sun shaft 20 is displaced to the front side, the position of the non-differential screw portion 21b is held without being displaced in the axial direction.

  When such a configuration is adopted, the screw 11 of the rotor 10 that meshes with the first screw portion 31a and the second screw portion 31b formed on the planetary shaft 30 is also used for the first screw portion 31a and the second screw portion 31b. Therefore, it is necessary to set the lead angle to be equal to these screws. Therefore, in order to suppress complication of the manufacturing process and increase in manufacturing cost, the screw 31 of the planetary shaft 30 is configured as one screw having a uniform lead angle from the front side to the rear side as in the above embodiment, and the sun shaft It is desirable to employ a configuration in which 20 screws are divided into a differential screw portion 21a and a non-differential screw portion 21b.

  In the above embodiment, it has been described that the load F directed to the right in FIG. 1 acts on the sun shaft 20 due to the reaction force of the valve spring. However, depending on the configuration of the valve characteristic changing mechanism, In some cases, a leftward load may be applied. In this case, the direction in which the planetary shaft 30 tilts when a load is applied to the sunshaft 20 is opposite to that in the above embodiment, and the planetary shaft 30 has a planetary differential motion conversion at its front end. While closing to the inner peripheral side of the mechanism 100, a rotational force that tilts the rear side end portion to open to the outer peripheral side acts. Therefore, in this case, a configuration may be adopted in which the non-differential screw portion 21b is provided on the front side of the differential screw portion 21a, contrary to the planetary differential motion conversion mechanism 100 of the above embodiment.

  In the above embodiment, the slide shaft portion 20b has a quadrangular cross section, and the non-differential screw portion 21b having the bearing hole 25 formed slightly larger than the slide shaft portion 20b is extrapolated to the non-differential screw portion 21b. The structure which attached the differential screw part 21b with respect to the sun shaft main body 20a so that rotation was impossible and it was possible to slide to an axial direction was shown. On the other hand, the structure which attaches the non-differential screw part 21b to the sun shaft main body 20a so that rotation and a slide are not possible can be changed suitably. For example, if the slide shaft portion 20b is formed as a shaft having a cross-sectional shape such as a hexagonal shape or a star shape, and the bearing hole 25 is formed to be slightly larger than this and have the same cross-sectional shape, a non-differential screw The portion 21b can be attached to the sun shaft main body 20a so as not to rotate and to be slidable in the axial direction.

  In the above embodiment, the screw 11 formed on the inner peripheral surface of the rotor 10 is the left screw, the differential screw portion 21a and the non-differential screw portion 21b formed on the outer peripheral surface of the sun shaft 20 are the right screw, and the planetary shaft. Although the configuration in which the screw 31 formed on the outer peripheral surface of the screw 30 is a left screw is shown, the direction of these screws may be opposite as long as the relationship of the screws meshing with each other is the same. That is, a right screw can be formed as the screw 11, a left screw can be formed as the differential screw portion 21 a and the non-differential screw portion 21 b, and a right screw can be formed as the screw 31. Even when such a configuration is employed, the sun shaft 20 can be displaced in the axial direction by rotating the rotor 10.

  In addition, the number of threads 11, 21, 31 shown in the above embodiment is the sunshaft that uses the difference between the lead angle of the differential screw portion 21 a and the lead angle of the screw 31 to rotate the rotor 10. It is only an example of a setting mode of the number of screw threads that can be converted into 20 linear motions. That is, the present invention is not limited to the planetary differential motion conversion mechanism 100 having each screw formed with the number of screw threads shown here.

  Although a power unit is illustrated in which a permanent magnet is attached to the rotor 10 of the planetary differential motion conversion mechanism 100 and the rotor 10 itself is configured as a rotor of a motor, the planetary differential motion conversion mechanism 100 according to the present invention is such The present invention is not limited to the power device having the configuration. For example, the planetary differential motion conversion mechanism 100 of the present invention can be applied even to a power unit that transmits the driving force of an electric motor to the rotor 10 via a gear, a belt, a chain, or the like.

  The configuration in which the power device including the planetary differential motion conversion mechanism 100 according to the present invention is applied as the power device that drives the valve characteristic changing mechanism that changes the maximum lift amount and the lift period of the intake valve is illustrated. On the other hand, the power unit provided with the planetary differential motion conversion mechanism 100 of the present invention can also be applied as a power unit of a valve characteristic changing mechanism that changes the maximum lift amount and lift period of the exhaust valve.

  -Moreover, according to the planetary differential type motion conversion mechanism 100 concerning this invention, the inclination of the planetary shaft 30 resulting from an axial load acting on the sun shaft 20 can be suppressed. Therefore, the present invention is not limited to the planetary differential motion conversion mechanism mounted on the power device of the valve characteristic changing mechanism that receives a load in one direction from the control shaft as described above. The present invention can be applied to any planetary differential motion conversion mechanism mounted on a driving power device.

Sectional drawing of the planetary differential type | formula motion conversion mechanism concerning one Embodiment of this invention. Sectional drawing of the AA line direction in FIG. 1 of the planetary differential type | formula motion conversion mechanism concerning the embodiment. The disassembled perspective view of the sun shaft of the planetary differential type | formula motion conversion mechanism concerning the embodiment. The perspective view which shows the assembly | attachment aspect of the sun shaft of the planetary differential type | formula motion conversion mechanism concerning the embodiment, the shaft main body of a planetary shaft, and a rotor. The perspective view which shows the assembly | attachment aspect of the planetary gear of the planetary differential type | formula motion conversion mechanism concerning the embodiment. (A) is a schematic diagram which shows a state when the sun shaft of the planetary differential motion conversion mechanism according to the embodiment is located on the rear side, and (b) is the sun shaft located on the front side. The schematic diagram which shows the state of time. (A) is a schematic diagram showing a state when the sun shaft of the planetary differential motion conversion mechanism according to the modified example of the embodiment is located on the rear side, (b) is the sun shaft is located on the front side The schematic diagram which shows a state when doing. The schematic diagram explaining that a planetary shaft inclines when the load of an axial direction acts on a sun shaft.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Rotor, 11 ... Screw, 12a ... Front side ring gear, 12b ... Rear side ring gear, 20 ... Sun shaft, 20a ... Sun shaft main body, 20b ... Slide shaft part, 20c ... Fitting shaft part, 21a ... Differential Screw part, 21b ... Non-differential screw part, 22a ... Front side sun gear, 22b ... Rear side sun gear, 23 ... Straight spline, 24 ... Tip part, 25 ... Bearing hole, 26 ... Bearing hole, 30 ... Planetary shaft, 31 ... Screw, 31a ... 1st screw part, 31b ... 2nd screw part, 32a ... Front side planetary gear, 32b ... Rear side planetary gear, 33 ... Shaft part, 34 ... Bearing hole, 35 ... Shaft body, 40 ... Cover, 100: Planetary differential motion conversion mechanism.

Claims (5)

A plurality of planetary shafts are interposed between an annular rotor and a sun shaft inserted into the rotor, and a pair of planetary gears provided at both ends of the planetary shaft are provided on the inner peripheral surface of the rotor. A pair of ring gears and a pair of sun gears provided on the outer peripheral surface of the sun shaft, and a screw provided between the pair of planetary gears on the outer peripheral surface of the planetary shaft. Each member is meshed by being engaged with both a screw provided on the inner peripheral surface of the screw and a screw provided on the outer peripheral surface of the sun shaft, and the lead angle of the screw of the planetary shaft is engaged with the lead angle. A planetary differential type that converts the rotational movement of the rotor into the linear movement of the sunshaft by utilizing the difference between the lead angle of the screw of the sunshaft. In the motion conversion mechanism,
The planetary differential motion conversion mechanism is used under a situation in which a load directed in one of the axial directions is always applied to the sunshaft, and the sunshaft screw is engaged with the meshing screw of the planetary shaft. A differential screw portion having a different lead angle and displaced in the axial direction as the planetary shaft rolls, and a lead angle equal to the screw of the planetary shaft that meshes with each other, and not displaced in the axial direction as the planetary shaft rolls. The non-differential screw portion is divided into the differential screw portion in the sun shaft main body to which the differential screw portion and the pair of sun gears are fixed. The planetary gear, wherein the planetary gear is mounted so as not to rotate relative to the sunshaft body and to be slidable in the axial direction between the sun gear located on the opposite side. Differential motion conversion mechanism. The planetary differential motion conversion mechanism according to claim 1,
The screw provided on the planetary shaft is formed as one screw portion having a uniform lead angle from a portion meshing with the differential screw portion to a portion meshing with the non-differential screw portion,
The differential screw portion is formed so that its lead angle is different from the lead angle of the screw of the planetary shaft and is displaced in the axial direction along with the rolling of the planetary shaft. The planetary differential motion characterized in that the moving screw is formed so that its lead angle is set equal to the lead angle of the planetary shaft screw so as not to be displaced in the axial direction along with the rolling of the planetary shaft. Conversion mechanism. In the planetary differential motion conversion mechanism according to claim 1 or 2,
The non-differential screw is assembled so as to be engaged with the screw of the planetary shaft at an end of the planetary shaft screw opposite to the direction in which the load acts. Conversion mechanism.   The planetary differential motion conversion mechanism according to claim 1 is provided, and the sun shaft is pivoted by rotating the rotor about the central axis of the sun shaft by a driving force of a motor. Power device that displaces in the direction. Combined with a valve characteristic changing mechanism of an internal combustion engine that changes the maximum lift amount and lift period of the engine valve in accordance with the axial displacement of the control shaft, and connecting the sun shaft to the control shaft, The power unit according to claim 4, wherein the power unit is applied as a power unit that is displaced in an axial direction.

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