JP2019095017A - Planetary gear drive and process of manufacture of planetary gear drive - Google Patents

Abstract

To provide a technology capable of easily attaining a desired bearing characteristic even if environmental temperature is changed when coefficients of linear expansions of a casing and a carrier are different from each other.SOLUTION: This invention relates to a planetary gear drive comprising a casing provided with an internal gear, an external gear engaged with the internal gear, a carrier installed at an axial side part of the external gear, a main bearing installed between the casing and the carrier. The main bearing is of a type to which a preload is applied. The casing and the carrier are composed of raw material having different linear coefficients of expansion. A carrier unit is composed of the casing, carrier and the main bearing. When it is defined that a load applied to rotary bodies of the main bearing is defined as a rotary body energizing load Fbrg, the carrier unit is constituted in such a way that the rotary body energizing load Fbrg may become within a temperature range Rb of about 3.0 kgf to 25.0 kgf at a temperature range of about -10°C to 50°C.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a planetary gear device and a method of manufacturing the same.

  In Patent Document 1, a casing provided with an internal gear, an external gear meshing with the internal gear, a carrier disposed on an axial side of the external gear, and a casing and a carrier are provided. A planetary gear set with a main bearing is disclosed. In this planetary gear device, the external gear is made of an iron-based material, and the casing is made of an aluminum alloy having a linear expansion coefficient larger than that of the external gear.

JP, 2014-9808, A

  The main bearing may be preloaded to obtain the required bearing characteristics. The required bearing characteristics here are, for example, the moment stiffness of the main bearing.

  Moreover, a casing and a carrier may be comprised using the raw material from which a linear expansion coefficient differs. In this case, if the environmental temperature around the gear unit changes, the preload applied to the main bearing changes due to the difference in volume change caused by the temperature change of the casing and the carrier, and the required bearing characteristics There is a fear that can not be obtained. The gear device of Patent Document 1 does not take measures for such a problem, and its improvement is desired.

  An embodiment of the present invention is made in view of such a situation, and one of its purposes is to make it possible to easily obtain the required bearing characteristics even if the environmental temperature changes when the linear expansion coefficients of the casing and the carrier are different. It is to provide.

  One embodiment of the present invention relates to a planetary gear device, and a casing provided with an internal gear, an external gear meshing with the internal gear, a carrier disposed on an axial side of the external gear, and the casing And a main bearing disposed between the carriers, wherein the main bearing is a bearing of a type to which a preload is applied, and the casing and the carrier have a linear expansion coefficient In a carrier unit composed of different materials and comprising the casing, the carrier and the main bearing, the load applied to the rolling elements of the main bearing when the casing starts rotating with respect to the carrier is the rolling element starting load When the carrier unit is loaded, the rolling element starting load in the temperature range of -10.degree. C. to 50.degree. C. falls within the allowable range of 3 kgf to 25 kgf. Constructed.

  According to the present invention, when the linear expansion coefficients of the casing and the carrier are different, it is easy to obtain the required bearing characteristics even if the environmental temperature changes.

It is side surface sectional drawing which shows the planetary gear apparatus of 1st Embodiment. It is an enlarged view which shows a part of carrier unit of 1st Embodiment. It is a graph which shows the unit temperature of a carrier unit, and the relationship of rolling element starting load. It is a figure which shows the relationship between axial amount, ie, amount, and rolling element starting load. It is side surface sectional drawing which shows the planetary gear apparatus of 2nd Embodiment.

  Hereinafter, in the embodiment and the modification, the same reference numerals are given to the same components, and the overlapping description will be omitted. Further, in each drawing, for convenience of explanation, a part of the constituent elements is appropriately omitted, or the dimensions of the constituent elements are appropriately enlarged and reduced.

First Embodiment
FIG. 1 is a side sectional view showing a planetary gear device 10 according to the first embodiment. The planetary gear device 10 of the present embodiment causes rotation of one of the internal gear and the external gear by swinging the external gear that meshes with the internal gear, and causes the generated motion component to be output from the output member. It is an eccentric oscillation gear device that outputs to a drive device.

  The planetary gear unit 10 mainly includes an input shaft 12, an external gear 14, an internal gear 16, carriers 18, 20, a casing 22, main bearings 24, 26, that is, an amount adjusting member 28; Equipped with Hereinafter, the direction along the central axis La of the internal gear 16 is referred to as “axial direction”, and the circumferential direction and the radial direction of a circle centered on the central axis La are “circumferential” and “radial”, respectively. Do. Further, hereinafter, for convenience, one side in the axial direction (right side in the drawing) is referred to as an input side, and the other side (left side in the drawing) is referred to as a non-input side.

  The input shaft 12 is rotated about a rotation center line by rotational power input from a drive device (not shown). The planetary gear device 10 of the present embodiment is a center crank type in which the rotation center line of the input shaft 12 is provided coaxially with the center axis line La of the internal gear 16. The drive device is, for example, a motor, a gear motor, an engine or the like.

  The input shaft 12 of the present embodiment is a crankshaft having a plurality of eccentric portions 12 a for swinging the external gear 14. The axis of the eccentric portion 12 a is eccentric with respect to the rotation center line of the input shaft 12. In the present embodiment, two eccentric portions 12 a are provided, and the eccentric phases of the adjacent eccentric portions 12 a are shifted by 180 °.

  The external gear 14 is individually provided corresponding to each of the plurality of eccentric portions 12a. The external gear 14 is rotatably supported by the corresponding eccentric portion 12 a via the eccentric bearing 30. The external gear 14 is formed with a pin hole 14 a through which the pin member 32 passes. A clearance is provided between the pin member 32 and the pin hole 14a to be a play for absorbing the oscillation component of the external gear 14. The pin member 32 and the inner wall surface of the pin hole 14a come in contact with each other.

  The internal gear 16 meshes with the external gear 14. The internal gear 16 of the present embodiment has a plurality of outer pins 16 a supported on the inner peripheral portion of the casing 22 and constituting the internal teeth of the internal gear 16. The number of internal teeth (the number of outer pins 16 a) of the internal gear 16 is one more than the number of external teeth of the external gear 14 in the present embodiment.

  The casing 22 has a cylindrical shape as a whole, and an internal gear 16 is provided on the inner periphery thereof. An annular flange portion 22 a is provided on the outer peripheral portion of the casing 22. The flange portion 22 a is provided radially outward with respect to the meshing position of the internal gear 16 and the external gear 14. In the flange portion 22a, a female screw hole 22b into which a screw member can be screwed is formed at an interval in the circumferential direction.

  Carriers 18, 20 are disposed on the axial side of external gear 14. The carriers 18 and 20 include an input side carrier 18 disposed on the input side of the external gear 14 and a non-input side carrier 20 disposed on the non-input side of the external gear 14. Be The carriers 18 and 20 have a disk shape and rotatably support the input shaft 12 via an input shaft bearing 34.

  The input side carrier 18 and the non-input side carrier 20 are connected via a pin member 32. The pin member 32 axially penetrates the plurality of external gears 14 at a position radially offset from the axial center of the external gear 14. The pin member 32 of this embodiment is provided as a part of the same member as the non-input side carrier 20, but may be provided separately from the carriers 18, 20. A plurality of pin members 32 are provided at intervals around the central axis La of the internal gear 16.

  The pin member 32 of the present embodiment is formed with a female screw hole 32 a that opens at the end face in the axial direction. The input side carrier 18 is formed with a stepped insertion hole 38 through which the screw member 36 is inserted from the side opposite to the pin member 32 with the input side carrier 18 interposed therebetween. The pin member 32 is fixed to the input side carrier 18 by screwing the screw member 36 into the female screw hole 32a. In addition, the pin hole 40 in which the front-end | tip part of the pin member 32 is inserted is formed in the input side carrier 18 of this embodiment.

  A member that outputs rotational power to the driven device is an output member, and a member fixed to an external member for supporting the planetary gear device 10 is a fixed member. The output member in this embodiment is the casing 22, and the fixed member is the non-input side carrier 20. The output member is rotatably supported by the fixed member via the main bearings 24 and 26.

  FIG. 2 is an enlarged view showing the main bearings 24 and 26 together with part of the peripheral structure. The main bearings 24 and 26 include an input-side main bearing 24 disposed between the input-side carrier 18 and the casing 22 and a non-input-side main bearing 26 disposed between the non-input-side carrier 20 and the casing 22. included. In the present embodiment, the pair of main bearings 24 and 26 are arranged in a so-called back-to-back combination, and intersect at their respective operation lines Lw (described later) offset to the main bearings 24 and 26 radially outward. Do.

  The main bearings 24, 26 of the present embodiment include a retainer 44 in addition to the plurality of rolling elements 42. The plurality of rolling elements 42 are provided at intervals in the circumferential direction. The rolling element 42 of the present embodiment is a spherical body. The retainer 44 holds the relative positions of the plurality of rolling elements 42 and rotatably supports the plurality of rolling elements 42.

  The main bearings 24 and 26 of the present embodiment include an outer ring 48 provided with an outer rolling surface 46 on which the rolling element 42 rolls, and an inner ring provided with an inner rolling surface 50 on which the rolling element 42 rolls. Absent. Instead, the inner rolling surface 50 is provided on the outer peripheral surface of the carriers 18, 20. The outer rolling surface 46 is provided radially outward of the rolling element 42, and the inner rolling surface 50 is provided radially inward of the rolling element 42. The outer ring 48 is integrated with the casing 22 by fitting such as an interference fit or an intermediate fit.

  The main bearings 24 and 26 are bearings of a type to which a preload Fp is applied. It can be said that the main bearings 24, 26 are types of bearings that require adjustment of the preload Fp. In this embodiment, an angular contact ball bearing is illustrated as this type of bearing. Other types of bearings of this type include rolling bearings such as tapered roller bearings and angular roller bearings described later. The preload Fp is mainly applied to secure bearing characteristics such as moment rigidity of the main bearings 24 and 26.

  The preload Fp is applied in the direction along the line of action Lw of the load acting on the rolling element 42. The action line Lw is a straight line connecting the contact point between the rolling element 42 and the inner rolling surface 50 and the contact point between the rolling element 42 and the outer rolling surface 46 when the rolling element 42 is a spherical body. In the main bearings 24 and 26 of the present embodiment, the working line Lw is inclined with respect to the orthogonal plane orthogonal to the axial direction, and the contact angle θ between the working line Lw and the orthogonal plane is more than 0 degrees. . The contact angle θ in the present embodiment is in the range of 40 ° to 55 °, preferably in the range of 45 ° to 55 °.

  That is, the amount adjusting member 28 is used to adjust the preload Fp of the main bearings 24 and 26. That is, the amount in which the rolling elements 42 pack in the direction along the aforementioned action line Lw (the amount of contraction) after the internal clearance of the main bearings 24 and 26 becomes zero is the amount in the axial direction. I assume. The preload Fp of the main bearings 24, 26 is adjusted by adjusting the axial amount, that is, by using the amount adjusting member 28.

  That is, the amount adjusting member 28 is provided separately from the casing 22 and the carriers 18 and 20. That is, the amount adjusting member 28 of the present embodiment is a plate-like shim separate from the component parts of the main bearings 24 and 26, and the axial amount is adjusted by changing the thickness thereof. The amount adjustment member 28 of this embodiment is disposed between the axial end face of the pin member 32 and the input side carrier 18. When arranged at such a place, that is, as the thickness of the amount adjusting member 28 is reduced, the axial amount can be increased.

The casing 22 and the carriers 18, 20 are made of materials having different linear expansion coefficients [1 / K]. In the present embodiment, the casing 22 is made of an aluminum-based material, and both the input side carrier 18 and the non-input side carrier 20 are made of an iron-based material. For example, the linear expansion coefficient of an aluminum-based material is 20 × 10 ^{−6 to} 25 × 10 ⁻⁶ [1 / K], and the linear expansion coefficient of an iron-based material is 10 × 10 ⁻⁶ to 15 × 10 ^−6. It is [1 / K]. The casing 22 is made of a material having a linear expansion coefficient larger than that of the carriers 18 and 20. In the present embodiment, components of the main bearings 24 and 26 (in this example, the rolling elements 42 and the outer ring 48) are also made of the same iron-based material as the carriers 18 and 20. More specifically, the components of the carrier 18 and the main bearings 24 and 26 are made of bearing steel, and the carrier 20 is made of chromium molybdenum steel specified by SCM 420 in JIS.

  The operation of the above-described planetary gear device 10 will be described. When rotational power is transmitted from the drive device to the input shaft 12, the eccentric part 12a of the input shaft 12 rotates around a rotation center line passing through the input shaft 12, and the external gear 14 is swung by the eccentric part 12a. At this time, the external gear 14 swings such that its own axis rotates around the rotation center line of the input shaft 12. When the external gear 14 swings, the meshing positions of the external gear 14 and the internal gear 16 sequentially shift. As a result, each time the input shaft 12 makes one rotation, rotation of one of the external gear 14 and the internal gear 16 occurs corresponding to the difference in the number of teeth between the external gear 14 and the internal gear 16.

  As in the present embodiment, when the casing 22 serves as an output member and the non-input side carrier 20 is fixed to an external member, rotation of the internal gear 16 occurs. On the other hand, when the non-input side carrier 20 is an output member and the casing 22 is fixed to the external member, rotation of the external gear 14 occurs. The rotation of the input shaft 12 is decelerated at a reduction ratio corresponding to the difference in the number of teeth of the external gear 14 and the internal gear 16 and output from the output member to the driven device.

  Here, in the planetary gear device 10 of the present embodiment, in order to manage the preload Fp applied to the rolling element 42, the rolling element activation load Fbrg of the carrier unit 52 is used. The carrier unit 52 is a unit comprising a casing 22, a pair of carriers 18 and 20, and a pair of main bearings 24 and 26. FIG. 2 is also a side sectional view showing a part of the carrier unit 52. As shown in FIG. The carrier unit 52 includes a quantity adjusting member 28 in addition to the pin member 32 and the screw member 36 connecting the pair of carriers 18 and 20. The carrier unit 52 is obtained by removing the components of the planetary gear device 10 other than the components of the carrier unit 52, and includes the input shaft 12, the external gear 14, the input shaft bearing 34, the oil seal (not shown), etc. Not included. The carrier unit 52 can be obtained by assembling the components of the carrier unit 52 after disassembling the planetary gear device 10 and removing the input shaft 12 and the external gear 14 and the like.

  The rolling element activation load Fbrg refers to a load applied to the rolling elements 42 of the main bearings 24 and 26 when the casing 22 starts to rotate with respect to the pair of carriers 18 and 20 in the carrier unit 52. The rolling element activation load Fbrg has a positive correlation with the preload Fp applied to the rolling elements 42 of the main bearings 24 and 26. For this reason, the preload Fp applied to the rolling element 42 can be managed by using the rolling element activation load Fbrg.

  FIG. 3 is a graph showing the relationship between the unit temperature Tu, which is the temperature of the carrier unit 52, and the rolling element starting load Fbrg. Here, the carrier unit 52 of the present embodiment is characterized in that the rolling element starting load Fbrg in the temperature range Ra of -10 ° C to 50 ° C falls within the predetermined allowable range Rb. Here, "in the temperature range Ra of -10 ° C to 50 ° C" means that the conditions mentioned in the temperature range Ra of -10 ° C to 50 ° C are satisfied.

  A temperature at which components of the planetary gear set 10 are assumed to be satisfied when used in an environmental temperature range assumed to be satisfied when the planetary gear set 10 is used, with the temperature range Ra of -10 ° C to 50 ° C It is defined as a range. The environmental temperature range here assumes the range of -10 degreeC-40 degreeC. When used in this environmental temperature range, the component parts of the planetary gear device 10 are affected by the meshing position of the internal gear 16 and the external gear 14 and the heat generation at the rolling surfaces 46 and 50 of the main bearings 24 and 26. , It is assumed that it is heated from its environmental temperature. Therefore, the temperature range Ra here is set to a temperature range of -10 ° C to 50 ° C obtained by adding the maximum heating temperature (10 ° C) assumed in advance to the upper limit value of the assumed environmental temperature range. ing.

  The allowable range Rb of the rolling element activation load Fbrg is set to 3 kgf to 25 kgf. When the rolling element activation load Fbrg is less than 3 kgf, little or no preload may be applied to the main bearings 24, 26 under the influence of variations in dimensional error and the like. In this case, the required moment rigidity may not be obtained. If the rolling element start-up load exceeds 25 kgf, the preload applied to the main bearings 24 and 26 becomes excessive, and the life of the main bearings 24 and 26 may be reduced, so that the required life may not be obtained. In the case of 3 kgf to 25 kgf, the main bearings 24 and 26 can be preloaded even under the influence of variations, and the required moment rigidity can be stably obtained. Moreover, the situation where excessive preload is applied to the main bearings 24, 26 can be avoided, and the life of the required main bearings 24, 26 can be secured.

  When the main bearings 24 and 26 are angular contact ball bearings, a preferable allowable range Rc of the rolling element starting load Fbrg is set to 3 kgf to 15 kgf. In the case of an angular ball bearing in which the rolling elements 42 make point contact with the rolling surfaces 46, 50, compared with the roller bearings in which the rolling elements 42 make linear contact with the rolling surfaces 46, 50, A heavy load is applied to the contact point. Therefore, in the case of angular contact ball bearings, it is preferable that the preload to be applied to the main bearings 24 and 26 be smaller than the roller bearings described later, from the viewpoint of avoiding a decrease in the life of the main bearings 24 and 26. From this viewpoint, the upper limit value of the allowable range is set to 15 kgf. The reason for the lower limit value of the preferable allowable range Rc is the same as that described above.

  This figure shows a temperature-load characteristic C1 showing the relationship between the unit temperature Tu obtained by measurement from a specific carrier unit 52 and the rolling element starting load Fbrg. Thus, the temperature-load characteristic C1 of the carrier unit 52 has a specific correlation. In this example, an example is shown in which there is a negative correlation in which the rolling element starting load Fbrg decreases as the unit temperature Tu increases. Therefore, in order to satisfy the load condition that the rolling element starting load falls within the allowable range Rb in the above temperature range Ra, the carrier unit 52 allows the rolling element starting load in the allowable range at the minimum value and the maximum value in this temperature range. It will be good if it fits in Rb. In other words, the carrier unit 52 is configured such that the rolling element starting load Fbrg at -10 ° C is within the allowable range Rb, and the rolling element starting load Fbrg at 50 ° C is within the allowable range Rb. It will be good.

  In order to configure the load condition described above, first, there is a method of adjusting the axial amount, that is, the amount by the amount adjusting member 28. For example, when the unit temperature Tu and the rolling element starting load have a negative correlation, adjustment is made to reduce the axial amount, that is, when the rolling element starting load Fbrg at -10 ° C exceeds the upper limit of the allowable range Rb. By doing this, the rolling element starting load Fbrg is reduced. Further, when the rolling element starting load Fbrg at 50 ° C. is lower than the lower limit value of the allowable range Rb, the rolling element starting load Fbrg is increased by adjusting to increase the axial blocking amount. When this adjustment method is used, in the example of FIG. 3, the rolling element starting load Fbrg of the temperature-load characteristic C1 changes so as to uniformly increase and decrease over the entire temperature range.

  Also, secondly, the linear expansion coefficients of the casing 22 and the carriers 18, 20 which are considered to affect the inclination of the temperature-load characteristic of the carrier unit 52 when configuring the load condition described above, There is a method of adjusting the dimension condition of the carrier unit 52. Here, the inclination of the temperature-load characteristic means the rate of change of the rolling element starting load Fbrg with respect to the change of the unit temperature Tu. The relationship between the parameters such as the linear expansion coefficient and the dimensional conditions and the inclination of the temperature-load characteristics will be described later. For example, if the rolling element starting load Fbrg at one or both of -10 ° C and 50 ° C falls outside the allowable range Rb, adjust these parameters so that the rolling element starting load Fbrg falls within the allowable range Rb By doing this, the slope of the temperature-load characteristics is reduced.

  When the first adjustment method is used, there is an advantage that the rolling element starting load Fbrg can be easily adjusted without adjusting the materials and dimensions of the casing 22 and the carriers 18, 20. When the second adjustment method is used, there is an advantage that the above-mentioned load condition can be satisfied through the adjustment of the slope of the temperature-load characteristic even when the above-mentioned load condition can not be satisfied by the axial blockage adjustment.

  As described above, the carrier unit 52 of the present embodiment is configured such that the rolling element starting load Fbrg falls within the allowable range Rb in consideration of a change in the environmental temperature. Therefore, when the linear expansion coefficients of the casing 22 and the carriers 18, 20 are different, even if the environmental temperature changes, it is easy to secure the required bearing characteristics with respect to moment rigidity and the like of the main bearings 24, 26.

  Next, a method of measuring the rolling element activation load Fbrg will be described. First, when the casing 22 starts to rotate with respect to the pair of carriers 18 and 20 in a state in which the rotation of the pair of carriers 18 and 20 is restricted by using the carrier unit 52, the predetermined measurement points of the casing 22 are applied. Measure the casing starting load Fm [kgf]. The measurement point is a head 54 a (see FIG. 1) of the screw member 54 fixed to the casing 22 by screwing into the female screw hole 22 b of the casing 22. The casing starting load Fm is measured using a push-pull gauge. The push-pull gauge is attached to the head 54 a of the screw member 54 fixed to the casing 22 and pulled in a tangential direction of a circle passing through the head 54 a of the screw member 54 about the central axis La of the internal gear 16. The maximum tensile load measured by the push-pull gauge is taken as the measurement value of the casing start-up load Fm from the start of pulling the push-pull gauge until the casing 22 starts to rotate.

The half value of the pitch circle diameter of the rolling elements 42 of the main bearings 24 and 26 is Rbrg [m]. The radial distance from the central axis La of the internal gear 16 to the measurement point of the casing activation load Fm is Rm [m]. At this time, the measured value of the casing activation load Fm and the following equation (A) are used to convert the load Fbrg applied to a location passing through the pitch circle of the rolling element 42, and the converted value Fbrg is applied to the rolling element activation load It is a measured value of Fbrg.
Fbrg = Fm × (Rm / Rbrg) (A)

  In measuring the rolling element activation load Fbrg, the temperature of the carrier unit 52 is changed by heating or cooling until the temperatures of the casing 22 of the carrier unit 52 and the carriers 18, 20 become comparable. Then, when the temperature measurement value of the predetermined temperature measurement point of the carriers 18 and 20 is within the range of ± 1 ° C. with respect to the temperature measurement value of the predetermined temperature measurement position of the casing 22, the temperature measurement value of the casing 22 Is used as a measurement value of the unit temperature Tu. The temperature measurement location of the casing 22 here is determined as the outer peripheral surface 22 c of the casing 22 located radially outward with respect to the engagement location of the internal gear 16 with the external gear 14. Also, the temperature measurement points of the carriers 18, 20 are defined as the axial end faces of the carriers 18, 20. The temperature of the temperature measurement point is measured by applying a contact-type thermometer to these temperature measurement points.

  In addition, when measuring rolling element starting load Fbrg, you may use the temperature measurement value obtained through the following procedure as a measurement value of unit temperature Tu. First, the carrier unit 52 is placed in a closed space held at a predetermined temperature, and held for a predetermined holding time sufficient for the temperature of the casing 22 and the carriers 18, 20 of the carrier unit 52 to reach the temperature of the closed space. Do. As a result, the temperature of the casing 22 and the carriers 18, 20 is approximately the same as the temperature of the closed space, so the temperature measurement value of the closed space at that time may be used as the measurement value of the unit temperature Tu.

  Next, a method of setting the control range Rma (see FIG. 3) of the rolling element activation load Fbrg, which was devised to facilitate satisfying the aforementioned load conditions, will be described. In this method, the following two parameters are determined, the slope of the temperature-load characteristic is determined using the two parameters, and the range in which the rolling element starting load Fbrg can be contained based on the slope of the temperature-load characteristic Set the management range Rma. These two parameters are a change in axial amount per unit amount (for example, 1 ° C.) of unit temperature Tu and a change rate of rolling element starting load Fbrg with respect to a change in axial amount.

  First, the amount of change in axial, that is, the amount of change per unit amount of the unit temperature Tu will be described. This is calculated by calculation using an equation described below.

  Please refer to FIG. A contact point of the casing 22 with the main bearings 24, 26 that restricts the axial displacement of the main bearings 24, 26 is taken as an axial displacement restriction point 56 of the casing 22. The contact points of the carriers 18 and 20 with the main bearings 24 and 26 which restrict the axial displacement of the main bearings 24 and 26 are taken as axial displacement restriction points 58 of the carriers 18 and 20. In the present embodiment, the axial displacement restriction portion 56 of the casing 22 is provided on the casing 22 at a position axially opposed to the outer rings 48 of the main bearings 24 and 26. Further, in the present embodiment, the axial displacement control point 58 of the carriers 18 and 20 is a contact point of the inner rolling surface 50 of the carriers 18 and 20 with the rolling element 42.

The axial distance between the axial displacement restricting portions 56 of the casing 22 corresponding to each of the pair of main bearings 24 and 26 is L0. The amount of change in the axial distance L0 of the casing 22 when the unit temperature Tu changes by ΔT is taken as the amount of axial expansion δL0 of the casing 22. At this time, δL 0 is expressed by the following equation (1). Here, ΔT is a change amount [° C.] from a predetermined reference temperature of the unit temperature Tu, and α 0 is a linear expansion coefficient [1 / K] of the casing 22.
δL0 = L0 × α0 × ΔT (1)

The axial distance between the axial displacement restricting points 58 of the carriers 18 and 20 corresponding to the pair of main bearings 24 and 26 is Li. The amount of change in axial distance Li of the carriers 18 and 20 when the unit temperature Tu changes by ΔT is taken as the amount of axial expansion δLi of the carriers 18 and 20. At this time, δLi is expressed by the following equation (2). Here, αi is the linear expansion coefficient [1 / K] of the carriers 18 and 20.
δLi = Li × αi × ΔT (2)

The difference δL between the axial expansion amount δL0 of the casing 22 and the axial expansion amount δLi of the carriers 18 and 20 is expressed by the following equation (3) using these. As the axial expansion amount δL0 of the casing 22 becomes larger than the axial expansion amount δLi of the carriers 18, 20, the difference δL becomes larger, and it is considered that the axial amount of the rolling element 42 becomes larger accordingly.
δL = δL0−δLi (3)

  The contact point of the casing 22 with the main bearings 24, 26 which restricts the radial displacement of the main bearings 24, 26 is taken as a radial displacement control point 60 of the casing 22. The contact points of the carriers 18 and 20 with the main bearings 24 and 26 which restrict the radial displacement of the main bearings 24 and 26 will be referred to as radial displacement restriction points 62 of the carriers 18 and 20. In the present embodiment, the radial displacement restricting portion 60 of the casing 22 is provided on the inner peripheral surface of the casing 22 at a portion radially opposed to the outer rings 48 of the main bearings 24, 26. In the present embodiment, the radial displacement control point 62 of the carriers 18 and 20 is a contact point of the inner rolling surface 50 of the carriers 18 and 20 with the rolling elements 42.

The radial dimension of the radial displacement restricting portion 60 of the casing 22 is D0 (see also FIG. 1). The amount of change of the radial dimension D0 of the casing 22 when the unit temperature Tu changes by ΔT is taken as the radial expansion amount δD0 of the casing 22. At this time, δD 0 is expressed by the following equation (4).
δD0 = D0 × α0 × ΔT (4)

The radial dimension of the radial displacement control point 62 of the carriers 18, 20 is Di (see also FIG. 1). The amount of change in radial dimension Di of the carriers 18 and 20 when the unit temperature Tu changes by ΔT is taken as the amount of radial expansion δDi of the carriers 18 and 20. At this time, δDi is expressed by the following equation (5).
δDi = Di × αi × ΔT (5)

The difference δD between the radial expansion amount δD0 of the casing 22 and the radial expansion amount δDi of the carriers 18 and 20 is expressed by the following equation (6) using these.
δD = δD0−δDi (6)

The radial component of the amount of jamming of the main bearings 24, 26 is called radial jamming. It is assumed that the contact angle θ of the main bearings 24 and 26 does not change before and after the change in the radial or amount by the difference δD of the radial expansion amounts of the casing 22 and the carriers 18 and 20. At this time, the axial amount of the main bearings 24 and 26 changes by the product of the tangent value (tan θ) of the contact angle θ of the main bearings 24 and 26 and the radial amount D. Assuming that the change amount of the axial expansion amount caused by the difference δD of the radial expansion amounts of the casing 22 and the carriers 18 and 20 is δ′L, this δ′L is expressed by the following equation (7). The negative sign of δD is that when the temperature of the casing 22 and the carriers 18, 20 increases, the rolling element 42 is axially closed due to the difference δL in the axial expansion, while the radial expansion is The rolling element 42 is considered to be loosened in the axial direction due to the difference .delta.D.
δ ′ L = −δD × tanθ (7)

The unit temperature Tu is only ΔT, using the difference δL between the axial expansion of the casing 22 and the carriers 18 and 20 and the change δ′L of the axial expansion due to the difference δD of the radial expansion. The axial change amount ΔL _total when changed is expressed by the following equation (8).
δL _total = δL + δ′L (8)

[delta] L _total, using equation (1) to (8), is expressed by the following equation (9). As described above, the change amount ΔL _total of the axial amount, the linear expansion coefficients α 0 and α i of the casing 22 and the carriers 18 and 20, the contact angle θ of the main bearings 24 and 26, and the axial distance between the pair of main bearings 24 and 26 It is expressed by a relational expression using L0, Li, radial dimensions D0, Di of the main bearings 24, 26, and an amount of change ΔT from the reference temperature of the unit temperature Tu. When this change amount ΔT is a unit amount of unit temperature Tu (for example, 1 ° C.), the following equation (9) represents an axial change amount ΔL _total per unit amount of unit temperature Tu. .
δL _total = ΔT × {(L0 × α0−Li × αi) − (D0 × α0−Di × αi) × tan θ} (9)

  Next, the rate of change of the rolling element starting load Fbrg with respect to the change of the axial amount will be described. In the following, an example will be described which is determined by an experimental method, but may be determined by an analytical method or the like.

  First, using the carrier unit 52 prepared in advance, the rolling element starting load Fbrg is measured under a plurality of conditions in which the axial amount is changed. The axial amount is adjusted by using the amount adjusting member 28. In the present embodiment, in other words, the axial amount is adjusted by changing the thickness of the amount adjusting member 28. The method of measuring the rolling element starting load is as described above. That is, the casing starting load Fm is measured under a plurality of conditions in which the axial amount is changed, and based on the measured value, measured values of the rolling element starting load Fbrg under a plurality of conditions are obtained. FIG. 4 shows the measurement results of the rolling element activation load Fbrg plotted with circles.

  Next, using the measurement values of the plurality of rolling element starting loads Fbrg, a relational expression indicating the relationship between the axial amount L and the rolling element starting loads Fbrg is calculated using an analysis method such as regression analysis. In the present embodiment, a regression line Lr (Fbrg = a × L + b, where b is a constant), which is an example of such a relational expression, is obtained from a plurality of measured values by the least square method or the like. The slope of this equation indicates the rate of change dFbrg / dL of the rolling element starting load with respect to the change of the axial amount. The rate of change dFbrg / dL is represented by the slope a (constant) of the regression line Lr when the regression line Lr as in this example is calculated as a relational expression.

From the above, it is possible to obtain the change amount ΔL _total of the axial amount, ie, the amount per unit amount of the unit temperature Tu, and the change rate dFbrg / dL of the rolling element starting load relative to the change of the axial amount. By using these parameters, a relational expression representing a change rate ΔFbrg of the rolling start load Fbrg with respect to a change of the unit temperature Tu as shown by the following equation (10) can be obtained. The rate of change ΔFbrg is calculated based on δL _total and dFbrg / dL. This relational expression is expressed using the above α0, αi, θ, L0, Li, D0, Di. This ratio indicates the slope of the above-mentioned temperature-load characteristic.
ΔFbrg = (dFbrg / dL) × δL _total (10)

  Next, with reference to FIG. 3, a method of setting the management range Rma of the rolling element starting load Fbrg using the slope ΔFbrg of the temperature-load characteristic will be described. This control range Rma is set as a range of rolling element starting load Fbrg between the control upper limit Rmax and the control lower limit Rmin which increases and decreases with the change of the unit temperature Tu according to the above-mentioned inclination ΔFbr of the temperature-load characteristic. . The control range Rma is set to fall within the allowable range Rb of the rolling element starting load Fbrg in the temperature range Ra of -10 ° C to 50 ° C. The management width Rw, which is the width from the management upper limit Rmax to the management lower limit Rmin of the management range Rma, is set to, for example, 2 to 5 kgf.

  The present inventor conducted the following experimental study to confirm whether the slope of the temperature-load characteristic can be accurately predicted using the control range Rma set in this manner. First, using carrier unit 52 prepared in advance, change rate ΔFbrg of rolling element starting load Fbrg with respect to change of unit temperature is obtained using the above-mentioned equation (10), and a management range Rma shown in the drawing is set.

  Next, using the same carrier unit 52, the rolling element starting load Fbrg was measured under a plurality of conditions in which the unit temperature Tu of the carrier unit 52 was changed. The plot on the temperature-load characteristic C1 in the figure shows the measured value of the rolling element starting load Fbrg. The slopes of the management upper limit Rmax and the management lower limit Rmin of the management range Rma set based on the rate of change ΔFbrg of the rolling element starting load Fbrg substantially coincide with the slope of the temperature-load characteristics C1 indicated by the plurality of measured values. Can understand that From this, it can be understood that the temperature-load characteristics can be accurately predicted by using the control range Rma set based on the change rate ΔFbrg of the rolling element starting load Fbrg described above.

  Hereinafter, a method of manufacturing the planetary gear device 10 using the control range Rma will be described. First, based on the change rate ΔFbrg of the rolling element starting load Fbrg described above, it is assumed that the allowable range Rb of the predetermined rolling element starting load Fbrg can be contained in the temperature range Ra of -10 ° C to 50 ° C. Set the management range Rma. In setting the control range Rma, the aforementioned α0, αi, L0, Li, D0, Di are the same as the positional relationship when the carrier unit 52 to be incorporated into the planetary gear device 10 is at the predetermined reference temperature. Set to and. The reference temperature in this embodiment is assumed to be room temperature, and more specifically 20 ° C.

  The control range Rma falls within the allowable range Rb of the rolling element start load Fbrg in the above temperature range Ra by increasing or decreasing the rolling element start load Fbrg in the control range Rma or increasing or decreasing the control width Rw in the entire temperature range. Set to meet the load condition. Even if this method is used, if the above-mentioned load conditions can not be satisfied, the parameters (α0, αi, etc.) affecting the inclination of the temperature-load characteristics are also adjusted to set the above-mentioned load conditions. Do.

  Next, using the carrier unit 52 to be incorporated into the planetary gear device 10, the rolling element starting load Fbrg of the carrier unit 52 is measured at the reference temperature, and whether the measured value is within the control range at the reference temperature judge. If the measured value of the rolling element activation load Fbrg falls outside the control range Rma at the reference temperature, the carrier unit 52 is disassembled to adjust the axial amount. On the other hand, when the measured value of the rolling element activation load Fbrg falls within the management range Rma at the reference temperature, the axial jamming amount at that time is specified as the appropriate jamming amount. That is, the measurement of the rolling element starting load Fbrg and the adjustment of the axial amount are repeated until the measured value of the rolling element starting load Fbrg falls within the control range Rma at the reference temperature.

  If the measured value of the rolling element starting load Fbrg does not fall within the management range Rma at this reference temperature, that is, the rolling element starting load Fbrg is adjusted through the adjustment of the axial amount by the amount adjusting member 28. For example, when the rolling element activation load Fbrg falls below the lower control limit value Rmin, the axial blockage amount is adjusted to be increased to increase the rolling element activation load Fbrg at the reference temperature. Further, when the rolling element activation load Fbrg exceeds the upper control limit value Rmax, adjustment is made to decrease the axial amount, that is, the rolling element activation load Fbrg at the reference temperature is reduced. In any case, the carrier unit 52 is disassembled, the existing adjusting member 28 is replaced with another adjusting member 28 having a different thickness, the carrier unit 52 is reassembled, and the rolling element starting load described above Measure Fbrg.

  Next, the planetary gear device 10 is assembled such that the axial amount of the main bearings 24, 26 is the appropriate amount. At this time, after the carrier unit 52 used for measuring the rolling element starting load Fbrg is disassembled, the components of the disassembled carrier unit 52, and the planetary gear device 10 such as the input shaft 12 and the external gear 14 etc. The planetary gear set 10 is assembled in combination with the following components. At this time, in order to make the axial blockage amount of the main bearings 24 and 26 an appropriate blockage amount, that is, the adjustment amount of the axial blockage amount by the amount adjusting member 28 is made the same as the condition when the appropriate amount is obtained. Thereby, rolling element starting load Fbrg in temperature range Ra of -10 ° C-50 ° C is stably stored in tolerance level Rb.

  It is to be noted that assembling the planetary gear device 10 after specifying the proper amount, that is, the rolling unit starting load Fbrg has variations due to the influence of dimensional tolerances and the like by the carrier unit 52, so it is not necessary to receive the effects of the variations. This is to obtain bearing characteristics.

  Supplement the second adjustment method to meet the load condition described above. In the temperature-load characteristics of the carrier unit 52, the linear expansion coefficients α0 and αi of the casing 22 and the carriers 18 and 20, and the contact angle θ of the main bearings 24 and 26, as shown in equations (9) and (10). The axial distance L0, Li of the pair of main bearings 24, 26 and the radial dimension D0, Di of the main bearings 24, 26 are affected. Therefore, the rolling element starting load Fbrg falls within the allowable range Rb in the temperature range Ra of -10 ° C to 50 ° C by adjusting the inclination of the temperature-load characteristic of the carrier unit 52 through adjustment and setting of these dimensional conditions. It can be configured to fit.

Second Embodiment
FIG. 5 is a side sectional view showing the planetary gear device 10 of the second embodiment. The planetary gear apparatus of the first embodiment has been described by taking a center crank type eccentric oscillating gear apparatus as an example. The planetary gear device of the present embodiment is a so-called distribution type eccentric oscillation gear device.

  The planetary gear device 10 differs from the first embodiment mainly in that it includes a plurality of input gears 70 and in terms of the input shaft 12 and the main bearings 24 and 26.

  The plurality of input gears 70 are disposed around the central axis La of the internal gear 16. Only one input gear 70 is shown in this figure. The input gear 70 is supported by the input shaft 12 which is inserted into the central portion of the input gear 70, and is rotatably provided integrally with the input shaft 12. The input gear 70 meshes with the external gear of a rotation shaft (not shown) provided on the central axis La of the internal gear 16. The rotational power is transmitted to the rotation shaft from a drive device (not shown), and the rotation of the rotation shaft rotates the input gear 70 integrally with the input shaft 12.

  A plurality of (for example, three) input shafts 12 of this embodiment are arranged at intervals in the circumferential direction at positions offset from the central axis La of the internal gear 16. Only one input shaft 12 is shown in this figure.

  The main bearings 24 and 26 in the present embodiment are tapered roller bearings, that is, roller bearings. The rolling elements 42 of this embodiment are conical rollers. When the main bearings 24 and 26 are roller bearings as in the present embodiment, the main bearings 24 and 26 are usually inner rings 72 provided with the inner rolling surface 50 in addition to the outer ring 48 provided with the outer rolling surface 46. Equipped with When the rolling element 42 is a roller, the above-mentioned action line Lw is a straight line passing through the center of the rotation axis of the roller in a cut surface along the central axis La of the internal gear 16 and orthogonal to the rotation axis Lb It says a straight line.

  The operation of the above-described planetary gear device 10 will be described. When rotational power is transmitted from the drive device to the rotational shaft, rotational power is distributed from the rotational shaft to the plurality of input gears 70, and the respective input gears 70 rotate in the same phase. When each input gear 70 rotates, the eccentric part 12a of the input shaft 12 rotates around the rotation center line passing through the input shaft 12, and the external gear 14 is swung by the eccentric part 12a. When the external gear 14 swings, the meshing position of the external gear 14 and the internal gear 16 is sequentially shifted as in the first embodiment, and one rotation of the external gear 14 and the internal gear 16 occurs. The rotation of the input shaft 12 is decelerated at a reduction ratio corresponding to the difference in the number of teeth of the external gear 14 and the internal gear 16 and output from the output member to the driven device.

  When the main bearings 24 and 26 are roller bearings as in the present embodiment, a preferable allowable range of the rolling element activation load Fbrg is set to 5 kgf to 25 kgf. If it is less than 5 kgf, in the case of a roller bearing, the preload of the main bearings 24, 26 may be insufficient, which may lead to a decrease in the life of the main bearings 24, 26, or a decrease in moment rigidity. The reason for the upper limit value of the allowable range is set in relation to the service life of the main bearings 24 and 26, as described above.

  In the first embodiment, the case where the main bearings 24 and 26 have no inner ring has been described as an example. In the present embodiment, the main bearings 24, 26 include the inner ring 72. In this case, the axial displacement restricting points 58 of the carriers 18 and 20 are provided on the carriers 18 and 20 at positions axially opposed to the inner rings 72 of the main bearings 24 and 26. The radial displacement restricting portions 62 of the carriers 18 and 20 are provided on the outer peripheral surface of the carriers 18 and 20 at locations radially facing the inner rings 72 of the main bearings 24 and 26. Further, along with this, the positions of Di and Li described above are different from the first embodiment. The handling of the other parameters is the same as in the first embodiment.

  The example of the embodiment of the present invention has been described in detail above. The embodiments described above are merely specific examples for implementing the present invention. The contents of the embodiment do not limit the technical scope of the present invention, and many design changes such as changes, additions, and deletions of components can be made without departing from the concept of the invention defined in the claims. It is possible. In the above-mentioned embodiment, although the description of "in the embodiment", "in the embodiment" and the like is given with respect to the content which can be changed in design like this, it is designed to the content without such description Changes are not unacceptable. Further, the hatching attached to the cross section of the drawing does not limit the material of the hatched object.

  The planetary gear device 10 has been described by way of example of an eccentric oscillation gear device, but the type is not particularly limited. For example, a simple planetary gear may be used.

  In the embodiment, the output member is the casing 22 and the carriers 18 and 20 are fixed to the outer member. Besides, the output member is the carrier 18, 20, and the casing 22 may be fixed to the outer member.

  The casing 22 and the carriers 18 and 20 may be made of materials having different coefficients of linear expansion, and the specific material is not particularly limited. For example, one material may be a resin material and the other material may be a metal material. Further, the linear expansion coefficients may be made different by using both materials as iron-based materials and making the carbon content of the materials different. Further, in the present embodiment, the casing 22 has been described as being formed of a material having a larger linear expansion coefficient than the carriers 18 and 20, but may be formed of a material having a smaller linear expansion coefficient than the carriers 18 and 20.

  In the first embodiment, although the case where the main bearings 24 and 26 include the outer ring 48 has been described as an example, the main bearings 24 and 26 may not include the outer ring 48. In this case, the outer rolling surface 46 of the rolling element 42 is provided on the inner peripheral surface of the casing 22. In this case, the axial displacement restricting portion 56 and the radial displacement restricting portion 60 of the casing 22 become contact points with the rolling elements 42 of the outer rolling surface 46 of the casing 22.

  That is, although the example in which the amount adjustment member 28 is separate from the components of the main bearings 24 and 26 has been described, the components of the main bearings 24 and 26 may be configured. For example, when the outer rings of the main bearings 24 and 26 constitute the amount adjustment member 28, the axial amount is adjusted by changing the axial dimension which is the thickness of the outer ring. In addition, in the case where the quantity adjustment member 28 is a shim, the arrangement position thereof is not particularly limited.

  In the embodiment, when setting the control range Rma as a range in which the rolling element starting load Fbrg in the temperature range Ra of -10 ° C to 50 ° C can be contained in the allowable range Rb, the rate of change ΔFbrg of the rolling element starting load Fbrg An example has been described. Besides this, without using the change rate ΔFbrg of the rolling element starting load Fbrg, the range of the rolling element starting load at the reference temperature that can satisfy the conditions is determined by experiment etc., and the obtained range is set as the management range Rma. You may

DESCRIPTION OF SYMBOLS 10 Planetary gear system 14 External gear 16 Internal gear 18, Carrier 20 Casing 24, main bearing 28 Amount adjusting member 42 Rolling element 52 Carrier unit.

Claims (8)

A casing provided with an internal gear;
An external gear meshing with the internal gear;
A carrier disposed on an axial side of the external gear;
A planetary gear device comprising: a main bearing disposed between the casing and the carrier;
The main bearing is a type of bearing to which a preload is applied,
The casing and the carrier are made of materials having different coefficients of linear expansion,
In a carrier unit comprising the casing, the carrier, and the main bearing, when a load applied to the rolling elements of the main bearing when the casing starts rotating with respect to the carrier is a rolling element starting load,
The planetary gear device, wherein the carrier unit is configured such that the rolling element starting load in a temperature range of −10 ° C. to 50 ° C. falls within an allowable range of 3 kgf to 25 kgf. The amount by which the rolling element is clogged in the direction along the line of action of the load acting on the rolling element is the blocking amount
Assuming that the axial component of the amount is the axial amount,
It is provided separately from the casing and the carrier, and has an adjustable amount or an adjustable member for adjusting the axial amount.
The planetary gear set according to claim 1, wherein the carrier unit is adjusted in axial axial amount by the amount adjusting member such that the rolling element starting load in the temperature range falls within the allowable range. The carrier includes a pair of carriers disposed on both axial sides of the external gear.
The main bearing includes a pair of main bearings disposed between each of the pair of carriers and the casing,
The carrier unit has a linear expansion coefficient of the casing and the carrier, a contact angle of the main bearing, and an axial distance between the pair of main bearings such that the rolling element starting load in the temperature range falls within the allowable range. The planetary gear device according to claim 1, wherein a radial dimension of the main bearing is set. The main bearing is an angular contact ball bearing,
The planetary gear device according to any one of claims 1 to 3, wherein the allowable range is set to 3 kgf to 15 kgf. The main bearing is a tapered roller bearing,
The planetary gear device according to any one of claims 1 to 3, wherein the allowable range is set to 5 kgf to 25 kgf. A casing provided with an internal gear;
An external gear meshing with the internal gear;
A carrier disposed on an axial side of the external gear;
A method of manufacturing a planetary gear set, comprising: a main bearing disposed between the casing and the carrier;
The main bearing is a type of bearing to which a preload is applied,
The casing and the carrier are made of materials having different coefficients of linear expansion,
In a carrier unit including the casing, the carrier, and the main bearing, a load applied to the rolling elements of the main bearing when the casing starts rotating with respect to the carrier is a rolling element starting load.
The amount by which the rolling element is clogged in the direction along the line of action of the load acting on the rolling element is the blocking amount
Assuming that the axial component of the amount is the axial amount,
The rolling element starting load of the carrier unit is measured at a predetermined reference temperature, the axial amount is adjusted until the measured value falls within a predetermined control range, and the axial amount when falling within the control range is appropriate Identifying as a quantity;
Assembling the planetary gear set so that the axial amount or the amount of the main bearing is appropriate or not,
The method of manufacturing a planetary gear device, wherein the control range is set as a range in which the rolling element starting load in a temperature range of −10 ° C. to 50 ° C. can be contained in an allowable range of 3 kgf to 25 kgf. The control range is between a control upper limit value and a control lower limit value that increases and decreases with a change in unit temperature of the carrier unit according to a change rate of the rolling element starting load with respect to a change in unit temperature of the carrier unit determined in advance. Set as a range,
The rate of change is calculated based on the amount of change in axial amount per unit amount of the unit temperature obtained in advance and the rate of change of the rolling element starting load with respect to the change in axial amount obtained in advance. The manufacturing method of the planetary gear apparatus of Claim 6. The carrier includes a pair of carriers disposed on both axial sides of the external gear.
The main bearing includes a pair of main bearings disposed between each of the pair of carriers and the casing,
The amount of change in axial amount per unit amount of the unit temperature is the linear expansion coefficient of the casing and the carrier, the contact angle of the main bearing, the axial distance between the pair of main bearings, and the diameter of the main bearing The method of manufacturing a planetary gear device according to claim 7 calculated based on a direction dimension.

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