JP2023036315A - Planetary gear mechanism - Google Patents

Abstract

To provide a planetary gear mechanism having a reasonable structure which is excellent in attachability.SOLUTION: A planetary gear mechanism P is provided at a linear motion device including: a housing 4; a drive part M; and a rod 3 which is formed with a screw part 10 to which a driving force is transmitted from the drive part M and which reciprocates along an axis X with rotation restricted. The planetary gear mechanism P includes: a first carrier K1 which threadedly engages with a nut 2 while contacting with an inner member 11a of a bearing part 11; a second carrier K2 which is attached to the first carrier K1 and holds a planetary gear P2; and a removal prevention ring 14 which is attached to an inner surface of the housing 4 so as to fix an outer member 11b of a bearing part 11 to the housing 4, so that the nut 2 which threadedly engages with the screw part 10, the bearing part 11 which rotatably supports the nut 2 on the housing 4, and a carrier K which holds the planetary gear P2 are fixedly inserted into the housing 4 in a state that the bearing part 11 is located at the depth side.SELECTED DRAWING: Figure 2

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a planetary gear mechanism that transmits rotational drive of a drive section to a rod that reciprocates in a state where rotation is restricted in a linear motion device.

Conventionally, such a planetary gear mechanism is disclosed, for example, in Patent Document 1 (see [0006], [0024] and FIG. 2).

The linear motion mechanism includes a housing 1a connected to the suspension mechanism, an electric motor accommodated inside the housing 1a, a planetary gear mechanism for reducing the output of the electric motor, and a rod 2 to be driven. are provided. A carrier that holds the planetary gear 32 of the planetary gear mechanism also serves as a nut member 36 that is screwed onto the rod 2 . The rod 2 has a magnet block 50 for measuring displacement, and the magnet block 50 is guided by the inner surface of the housing 1a, so that the rod 2 reciprocates while its rotation is restricted.

Among them, the planetary gear mechanism is fixed to the housing 1a as follows. The innermost sun gear 31 is integrally formed with the hollow rotary shaft 20 of the electric motor. The outermost ring gear 33 is non-rotatably supported by a cylindrical holder 34, and the holder 34 is non-rotatably supported on the inner surface of the housing 1a. At that time, the snap ring 14 is held in the annular groove 10a formed in the inner surface of the housing 1a, and one position of the ring gear 33 is defined.

Between the sun gear 31 and the ring gear 33, a carrier formed integrally with a nut member 36 and supporting the three planetary gears 32 is arranged. A bearing 37 is provided between the outer end screen of the carrier and the inner surface of the holder 34 . The inner member 37a of the bearing 37 is fixed in position by spacers 37c attached to grooves on the end face of the carrier and the outer face of the carrier. The outer member 37b of the bearing 37 is positionally fixed by the stepped portion of the holder 34 and the connecting cover 11 attached so as to cover the end opening of the housing 1a. As a result, the outer member 37b of the bearing 37, the holder 34, and the ring gear 33 are firmly sandwiched between the snap ring 14 and the connecting cover 11, and are held non-rotatably with respect to the housing 1a.

JP 2016-60393 A

In the conventional planetary gear mechanism described above, the carrier and the nut member 36 have an integrated structure. Therefore, in order to improve the thrust force and durability of the linear motion mechanism, it was necessary to change the trapezoidal thread formed on the nut member 36 so as to be screwed with the rod 2 to a highly wear-resistant material such as brass. . If the entire carrier were made of brass, the weight of the direct-acting mechanism would increase and the cost would also increase.

Further, in this planetary gear mechanism, a holder 34 is used to fix the ring gear 33 to the housing 1a. It is presumed that this is because the holder 34 for simultaneously holding the large-diameter ring gear 33 and the small-diameter bearing 37 is provided in order to fix the bearing 37 having a smaller diameter than the ring gear 33 . However, the provision of such a holder 34 increases the number of parts and the number of assembling man-hours, resulting in an increase in cost.

If the holder 34 is omitted, the outer diameters of the ring gear 33 and the bearing 37 are too different, so that the mounting portion of the bearing 37 is particularly complicated. That is, the inner member 37a of the bearing 37 is secured to the carrier while the outer member 37b of the bearing 37 is secured to the housing 1a. In this case, the position of the large-diameter ring gear 33 and the position of the small-diameter bearing 37 are close to each other along the longitudinal direction of the rod 2. It is necessary to have a configuration that narrows greatly toward the Also, in this case, when fixing the positions of both ends of the outer member 37b of the bearing 37, it is extremely difficult to fix the ends because the large-diameter ring gear 33 exists in the vicinity of one side.

As described above, the conventional planetary gear mechanism has various problems to be solved in order to simplify the mechanism itself or to easily mount the mechanism. was sought.

(characteristic configuration)
The characteristic configuration of the planetary gear mechanism according to the present invention is
a housing;
a driving portion provided in the housing;
a rod that reciprocates along an axis while being prevented from rotating with respect to the housing, the linear motion device having a threaded portion to which a driving force is transmitted from the output gear of the driving portion;
a nut screwed onto the threaded portion;
a bearing that rotationally supports the nut on the housing;
a carrier for holding a planetary gear, and a carrier that is inserted into and fixed to the housing with the bearing facing toward the back;
a first carrier that is in contact with the inner member of the bearing and is screwed with the nut;
a second carrier attached to the first carrier and holding the planetary gear;
a retainer ring fixed to the inner surface of the housing so as to fix the outer member of the bearing portion to the housing.

(effect)
When a planetary gear mechanism composed of a plurality of members such as a carrier for holding planetary gears, a bearing portion, and a nut is inserted and fixed in the inner part of a housing, the order of assembling the components becomes complicated.

Therefore, in this configuration, the carrier that holds the planetary gear is divided into a first carrier and a second carrier, so that the second carrier is attached instead of the bearing portion and the retainer ring that are arranged on the back side of these carriers. can be done before. Since the bearing is fixed by fixing the retainer ring to the inner surface of the housing, the sizes of the bearing and the retainer ring are not restricted by the size of the carrier. Therefore, the size of the bearing portion can be reduced, and the planetary gear mechanism can be configured compactly.

Moreover, in this configuration, the nut and the carrier are configured separately, so that they can be configured using appropriate materials. As a result, it is possible to obtain a light weight and low cost planetary gear mechanism as compared with the conventional case where the whole is made of brass material.

In the planetary gear mechanism according to the present invention, the outer diameter of the second carrier can be made larger than the inner diameter of the retainer ring.

(effect)
As a result of separating the first carrier and the second carrier as in this configuration, it is possible to perform the work of attaching the bearing portion before performing the attachment of the second carrier. Therefore, as in this configuration, the outer diameter of the second carrier can be set larger than the inner diameter of the retainer ring, increasing the degree of freedom in selecting the dimensions of the second carrier. This simplifies the procedure for attaching the bearings, etc., and improves the efficiency of the assembly work.

Moreover, as a result of being able to set the size of the bearing portion and the size of the second carrier separately, the degree of freedom in setting the components of the planetary gear mechanism increases.

In the planetary gear mechanism according to the present invention, the first carrier is provided with a fixed screw portion that meshes with the nut, and the bearing portion is a bulging portion protruding from the surface of the nut, The inner member of the bearing portion may be sandwiched between the end surface of the first carrier and the first carrier.

(effect)
With this configuration, fixing of the bearing portion to the nut and fixing of the first carrier are simplified, and these assembly operations can be made more efficient.

In the planetary gear mechanism according to the present invention, the first carrier and the second carrier are connected in two stages along the axial direction by a first fitting portion and a second fitting portion. Advantageously, the second fitting is a splined fitting.

(effect)
With a configuration in which the first carrier and the second carrier are fitted along the direction of the axis, as in this configuration, the attachment of the second carrier becomes extremely easy.

In addition, by forming the fitting portion in two stages of a first fitting portion and a second fitting portion, and by forming one of the second fitting portions into a spline shape, the first carrier and the second carrier can be can stably rotate together, and the rotation of the planetary gear can be reliably transmitted to the nut.

Furthermore, before the second carrier is fitted to the first carrier, the first carrier is screwed to the nut with the spline portion of the first carrier exposed. At this time, the spline portion can serve as the input portion of the fastening tool, so that the work of fixing the first carrier becomes easier.

In the planetary gear mechanism according to the present invention, an annular spacer is provided to prevent contact between the outer member of the bearing portion and the retainer ring, and the spacer is fixed to the inner surface of the housing. be able to.

(effect)
With this configuration, the dimensions of the spacer that prevents the outer member of the bearing from coming off can be set regardless of the dimensions of the second carrier. Therefore, the degree of freedom in designing the portion to which the bearing portion is fixed is increased. In addition, when spacers are used, the spacers can be attached before the second carrier is attached, and the work for attaching the bearings can be made more efficient.

Explanatory drawing showing a usage example of the displacement detection device according to the embodiment of the present invention. Explanatory diagram showing the configuration of the drive unit An exploded perspective view showing the configuration of the drive unit. Side sectional view showing the configuration of the displacement detection device FIG. 2 is a perspective view showing the configuration of main parts of the displacement detection device; Longitudinal cross-sectional view showing the configuration of the main part of the displacement detection device FIG. 3 is a perspective view showing the configuration of the control unit; The perspective view which shows the structure of a spacer board|substrate. A perspective view showing a fitting structure of the first board and the second board. Explanatory diagram showing the grounding structure of the control unit Explanatory diagram showing the heat dissipation structure of the control unit Explanatory drawing showing the seal structure of the control unit

(overview)
The displacement detection device S according to the present invention can be used, for example, in a linear motion mechanism provided in a rear wheel steering device of a vehicle.
In the linear motion mechanism, for example, a tubular nut 2 is rotationally driven by an electric motor 1, which is a driving portion M, and a rod 3 screwed and inserted into the nut 2 is reciprocated. A part of the rod 3 is formed with a sliding surface that abuts against the inner surface of the housing 4 of the linear motion mechanism, so that the rod 3 is configured to reciprocate without rotating.

1 and 2 show the configuration of a linear motion mechanism according to this embodiment. The linear motion mechanism includes a control section C provided on the left side of FIG. 1 and a drive section M provided on the right side. The control unit C has a linear motion sensor 25 for measuring the displacement state of the rod 3 and calculates the position of the rod 3 based on signals from the linear motion sensor 25 and the like. Based on the calculation result, the controller C supplies a drive signal to the driver M to move the rod 3 to the desired position.

(Drive part)
As shown in FIGS. 2 and 3, the drive unit M of this embodiment includes a stator 5 having an axis X along the moving direction of the linear motion mechanism, and a cylindrical rotor 6 rotating inside the stator 5. ing. A rod 3 is inserted through the cylindrical rotor 6 . The rotor 6 is supported by the housing 4 by rotor bearings 7 on both outer sides along the axial center X across a position facing the stator 5 .

(planetary gear mechanism)
A planetary gear mechanism P is connected to one end of the rotor 6 . Specifically, a sun gear P1 is formed on the outer surface of the end portion of the rotor 6 . Three planetary gears P2 mesh with the sun gear P1, and a ring gear P3 fixed to the housing 4 meshes with the planetary gears P2.

The carrier K of the planetary gear P2 is screwed and fixed to the outer peripheral side of the nut 2 that is screwed with the rod 3 . The carrier K has a first carrier K1 fixed to the outer surface of the nut 2 and a second carrier K2 fitted and fixed to the first carrier K1 outside the first carrier K1. Three shaft members 8 that respectively support three planetary gears P2 are fixed to the second carrier K2.

The nut 2 is cylindrical and has a female trapezoidal thread 9a as an output gear 9 of the driving portion M formed on the inner surface thereof. A male trapezoidal screw 10a is formed as a screw portion 10 on the outer surface of one rod 3. As shown in FIG. The nut 2 is made of brass for wear resistance. The rod 3 reciprocates without rotating with respect to the housing 4 by contacting the inner surface of the housing 4 with a sliding contact member 21 which will be described later. A bearing portion 11 using a thrust bearing is fitted on the outer surface of the nut 2 , and the bearing portion 11 is fitted on the inner surface of the housing 4 .

One end of the nut 2 is screwed and fixed via a fixing screw portion 12 in a state in which the first carrier K1 is externally inserted. The other end of the nut 2 is formed with a bulging portion 2a protruding in the radial direction. sandwich along the direction. With this configuration, it becomes easy to fix the bearing portion 11 and the first carrier K1 to the nut 2, and the efficiency of these assembly operations can be improved.

Further outwardly of the first carrier K1, a second carrier K2 holding the planetary gear P2 is externally fitted and fixed. The outer fitting fixing is performed using two types of fitting portions. One is a cylindrical first fitting portion Ka formed on the far side in the fitting direction along the direction of the axis X when viewed from the second carrier K2 side. It is formed by a cylindrical fitting outer surface formed on the outer surface of the first carrier K1 and a cylindrical fitting inner surface formed on the inner surface of the second carrier K2. The other is a spline-shaped second fitting portion Kb adjacent to the first fitting portion Ka on the front side in the fitting direction when viewed from the second carrier K2 side.

The second fitting portion Kb is configured in a star shape as a cross-sectional shape perpendicular to the axis X, for example. As a result, the first carrier K1 and the second carrier K2 do not rotate relative to each other, and a durable carrier K can be configured. Further, when screwing the first carrier K1 into the nut 2, the second fitting portion Kb can be used as an engaging portion of a fastening tool. Note that the first carrier K1 and the second carrier K2 are made of steel instead of conventional brass in order to reduce weight and cost.

In this embodiment, the housing 4 has a narrowed shape, and the bearing 11 needs to be arranged deep inside the carrier K. As shown in FIG. Therefore, the order of attachment is to attach the bearing portion 11 to the nut 2 , sandwich the bearing portion 11 with the first carrier K<b>1 , and then fix them to the housing 4 . After that, the second carrier K2 is attached to the first carrier K1.

To fix the bearing portion 11, an annular spacer 13 that contacts the outer member 11b of the bearing portion 11 and a retainer ring 14 that contacts the spacer 13 and holds the positions of the bearing portion 11 and the spacer 13 are used. . The retainer ring 14 is, for example, a C-shaped snap ring that fits into a groove 15 formed on the inner surface of the housing 4 .

With this configuration, the spacer 13 can be attached before attaching the second carrier K2, and the size of the spacer 13 can be set regardless of the size of the second carrier K2, which tends to have a relatively large diameter. Therefore, the degree of freedom in designing the mounting portion of the bearing portion 11 is increased, and the mounting work of the bearing portion 11 is made efficient. Moreover, as a result of being able to set the size of the bearing portion 11 and the size of the second carrier K2 individually, the degree of freedom in setting the components of the planetary gear mechanism P increases.

By using the spacer 13, even if there is an error in the formation position of the groove portion 15, by using the spacer 13 having an appropriate thickness, the outer member 11b can be fixed to the housing 4 without rattling. Further, by making the spacer 13 a completely annular member, the spacer 13 abuts on the entire circumference of the outer member 11b, thereby improving the effect of preventing the outer member 11b from coming off.

After the fixing of the bearing portion 11 is completed, the second carrier K2 is fitted and fixed to the first carrier K1. The order in which the planetary gears P2 are attached to the second carrier K2 may be before or after the second carrier K2 is attached to the first carrier K1. The ring gear P3 is fitted to the inner surface of the housing 4 as shown in FIG.

(Guide part)
Rotation of the rod 3 is prevented by the housing 4 when the rod 3 is reciprocated by the driving portion M. As shown in FIG. For this purpose, as shown in FIGS. 4 to 6, a guide portion G extending between the rod 3 and the housing 4 is formed on the side of the rod 3 opposite to the threaded portion 10 .

The guide portion G includes a slider 20 provided on the rod 3, a sliding contact member 21 attached to the slider 20, and a guide surface provided on the housing 4 so that the sliding contact member 21 slides over a predetermined distance. 22.

The slider 20 is a member having a U-shaped cross section perpendicular to the axis X as shown in FIGS. 5(a) and 5(b). The slider 20 is fixed to the rod 3 by a mounting bolt, which is a fastening member 23, through a mounting hole 20b provided in a U-shaped bottom portion 20a. As for the mounting procedure, the rod 3 is inserted into the housing 4 , and the slider mounting position of the rod 3 is made to correspond to the position of the mutually opposing guide surfaces 22 formed in the opening of the housing 4 . In this state, the slider 20 to which the sliding contact member 21 is attached in advance is positioned and fastened by the fastening member 23 .

The sliding contact member 21 is attached to the slider 20 by inserting groove-like insertion portions 21a formed in the sliding contact member 21 into a pair of U-shaped projecting portions 20c of the slider 20. As shown in FIG. The inner wall 21b forming the insertion portion 21a of the sliding contact member 21 is formed with a claw portion as an engaging portion 21c, and the pair of protruding portions 20c is provided with a claw portion as the engaged portion 20d. engage the parts. By performing engagement by so-called snap fit in this way, the operation of attaching the sliding contact member 21 to the slider 20 is simplified, and the operation cost can be reduced.

Further, stepped portions 20e are formed by cutting both ends along the direction of the axis X at the tip edge of each projecting portion 20c. As a result, when the insertion portion 21a of the sliding contact member 21 is inserted into the projecting portion 20c, as shown in FIG. and prevents the sliding contact member 21 from rattling along the axial center X direction with respect to the projecting portion 20c.

Further, the outward facing surfaces of the pair of sliding contact members 21 are sliding contact surfaces 21d, which are in sliding contact with the guide surfaces 22 provided on the housing 4 to prevent the rod 3 from rotating. In order to reliably prevent this rotation, the outward facing surfaces of the pair of projecting portions 20c of the slider 20 are formed as planar receiving surfaces 20f, which are formed inside the insertion portions 21a of the sliding contact members 21. surface contact with the flat surface 21e. By providing the receiving surface 20f and the flat surface 21e as described above, the rotation restricting function of the rod 3 can be reliably exhibited, and the torque of the linear motion mechanism can be increased.

The slider 20 is made of a metal material such as steel or stainless steel, and can reliably receive the anti-rotation torque of the rod 3 received as a reaction force from the guide surface 22 when the rod 3 reciprocates. On the other hand, the sliding contact member 21 is made of a material having a low coefficient of friction, such as fluororesin.

Further, by separating the slider 20 and the sliding contact member 21, the sliding contact member 21 can be attached to the slider 20 after the slider 20 is attached to the rod 3. Before the sliding contact member 21 is attached, it becomes easy to fix the fastening member 23 from between the pair of projecting portions 20c. With this configuration, when assembling the slider 20, it is not necessary to change the attitude of the rod 3, such as reversing it, and an efficient assembling work is possible.

(control part)
The position of the rod 3 is detected by the controller C. This detection is performed by a magnet 24 provided between the pair of sliding contact members 21 and a direct-acting sensor 25 provided on the control board 26 so as to approach and oppose the magnet 24 .

As shown in FIG. 5, a long magnet 24 is inserted into a resin material to form a magnet block 24a. The magnet block 24 a is fixed to the rod 3 , but is attached so that an external force preventing the rotation of the rod 3 is not input from the sliding contact member 21 to the magnet 24 .

Specifically, the magnet block 24a is inserted between the pair of sliding contact members 21 as shown in FIG. It is arranged in a state of being in contact with the first seat 20g. As a result, the detection surface of the magnet 24 is set at a predetermined height with respect to the surface of the rod 3 .

Further, projecting portions 24b are provided in the vicinity of both ends of the magnet block 24a. pinch in the direction. At this time, if the second receiving seat 24c is lightly brought into contact with the sliding contact member 21, the magnet block 24a does not rattle when the rod 3 is reciprocated, and the position measurement accuracy of the rod 3 is further improved.

Further, the positioning of the magnet 24 in the width direction, that is, the direction intersecting with the axis X when viewed in a direction perpendicular to the surface of the magnet 24 is performed by the housing 4 . That is, a second guide surface 27 provided parallel to the guide surface 22 in the vicinity of the guide surface 22 in the housing 4 is in sliding contact with the projecting portion 24b to position and guide the movement of the magnet 24. As shown in FIG.

In this way, after the slider 20 and the slide contact member 21 are fixed to the rod 3 inserted through the housing 4, the magnet block 24a is positioned relative to the slide contact member 21 and the housing 4, so that the magnet 24 is attached to the rod. 3 can be easily installed.

With this configuration, the force that prevents the rod 3 from rotating when the rod 3 reciprocates does not act from the sliding contact member 21 to the magnet 24 . Therefore, the possibility of the magnet 24 being damaged can be eliminated, and a displacement detection device S having a rational structure with enhanced durability can be obtained.

4 and 7 show the configuration of the control section C. FIG. The magnet 24 that constitutes the control unit C is fixed to the rod 3 side, and arranged with its own detection surface facing upward. A direct-acting sensor 25 is placed in close proximity to this magnet so as to face it. The direct-acting sensor 25 is mounted on a first substrate 26a, which will be described later, and detects positional information of the rod 3. As shown in FIG. The controller C calculates the position of the rod 3 based on the signal obtained by the direct-acting sensor 25, and transmits a drive signal to the driver M to move the rod 3 to the desired position.

As shown in FIGS. 7A and 7B, the control unit C includes, for example, a first substrate 26a and a second substrate 26b as the control substrate 26. FIG. The first substrate 26a is a substrate on the side facing the magnet 24, and is a so-called control system substrate on which the linear motion sensor 25 and the like are provided. The second substrate 26b is a so-called power supply system substrate including a power supply circuit and the like.

In this embodiment, an annular spacer substrate 26c having a rectangular overall shape, for example, is provided between the first substrate 26a and the second substrate 26b to electrically connect the first substrate 26a and the second substrate 26b. Connected. The first substrate 26a, the second substrate 26b, and the spacer substrate 26c are attached to the frame member 38 in advance before being fixed to the housing 4. As shown in FIG. The frame member 38 includes a connector 38a for connecting the first substrate 26a and the like to the ECU of the vehicle. By stacking a plurality of substrates in this way, it is possible to reduce the overall planar area of the control unit C, and to improve the mountability of, for example, a direct-acting mechanism or the like on a target device.

As shown in FIG. 8, the spacer substrate 26c is provided with a plurality of relay terminals 30 that connect the soldered portions of the first substrate 26a and the soldered portions of the second substrate 26b. Here, the relay terminal 30 is configured in a linear bar shape. The relay terminal 30 is made of a material having excellent mechanical strength, electrical conductivity, thermal conductivity, and corrosion resistance, such as a Cu alloy-based material or an Fe alloy-based material.

Each relay terminal 30 is arranged to pass through the spacer substrate 26c. For example, a plurality of holes are previously formed in the spacer substrate 26c, and the relay terminals 30 are fitted and inserted. Further, the spacer substrate 26c may be insert-molded with the relay terminals 30 embedded in predetermined positions.

In order to connect the first board 26a and the second board 26b to each relay terminal 30, it is necessary to position the first board 26a and the second board 26b with respect to all the relay terminals 30 accurately. For this reason, as shown in FIG. 9, a first positioning portion 31 for positioning each other is provided between the spacer substrate 26c and the first substrate 26a.

For example, the spacer substrate 26c is provided with a first convex member 31a protruding toward the first substrate 26a, and is fitted into the first fitting hole 31b provided in the first substrate 26a. . On the other hand, the spacer substrate 26c and the second substrate 26b are also provided with a second convex member 32a provided on the spacer substrate 26c as a second positioning portion 32 and a second fitting hole 32b provided on the second substrate 26b. Good to keep.

By providing the first positioning portion 31 and the second positioning portion 32 as described above, the work of connecting the spacer substrate 26c to the first substrate 26a and the second substrate 26b becomes easy, and the work of assembling the substrates in multiple stages becomes efficient. be. Therefore, a low-cost substrate mounting structure can be obtained.

(Heat resistant structure)
A large number of electronic components are mounted on the first substrate 26a and the second substrate 26b, and various amounts of heat are generated during normal use. This heat generation can change the dimensions of each board and change the mechanical properties of the heated solder joints. As a result, the relative positions of the soldered portions of the first substrate 26a and the soldered portions of the second substrate 26b are displaced along the planar direction of the substrates, causing problems such as cracking of the soldered portions.

Therefore, the spacer substrate 26c of the present embodiment is provided with a slit 33a as a partition portion 33 for separating the regions A in which a predetermined number of relay terminals 30 are arranged. Specifically, as shown in FIG. 8, a plurality of slits 33a extending in a direction perpendicular to the peripheral portion of the spacer substrate 26c are formed in each region A having a predetermined area. For that purpose, only the portion of the slit 33a is projected toward the center of the spacer substrate 26c, and the slit 33a is formed inside the projecting portion 34. As shown in FIG. This secures connection rigidity between the areas A on both sides of the slit 33a.

With this configuration, the predetermined regions A of the spacer substrate 26c can be displaced relative to each other, and the change in the posture of the relay terminal 30 due to the temperature rise of the first substrate 26a and the second substrate 26b can be absorbed. . Therefore, an excessive bending force or the like does not act on the soldered portions of the first substrate 26a and the second substrate 26b, and the soldered portions can be effectively protected.

(grounding structure)
In the substrate mounting structure of this embodiment, the first substrate 26a and the second substrate 26b are provided with the following grounding structure in order to suppress noise generation. That is, the ground terminal is attached to at least one of the first fixing portion 35a used for fixing to the housing 4 on the first substrate 26a and the second fixing portion 35b used for fixing to the housing 4 on the second substrate 26b. 36 is provided.

The ground terminal 36 is grounded to the frame member 38 by attaching the second substrate 26b and the like to the frame member 38 . Furthermore, the frame member 38 is fixed to the housing 4 using the screw member 39 or the like, so that the second substrate 26b or the like is grounded to the housing 4 .

Specifically, as shown in FIGS. 10A and 10B, a ground terminal 36 formed by bending a metal plate is attached to a fixing screw 37 for fixing the second substrate 26b to a frame member 38, for example. This ground terminal 36 is in contact with the ground circuit of the second substrate 26b. Also, one of the ground terminals 36 is provided with an elastic portion 36 a projecting away from the fixing screw 37 . The elastic portion 36a protrudes outward from the second substrate 26b, and is configured to electrically connect the second substrate 26b and the housing 4 simply by attaching the frame member 38 having the second substrate 26b to the housing 4. I have

With this configuration, it is possible to reduce the influence of noise that the first substrate 26a and the second substrate 26b receive from peripheral devices. In addition, when the first board 26a and the second board 26b are attached to various devices, the grounding work can be performed at the same time. Therefore, it is possible to obtain a board mounting structure with excellent attachment workability and high reliability.

(Heat dissipation structure)
The first substrate 26a and the second substrate 26b of this configuration generate heat during use. In particular, the amount of heat generated by the second substrate 26b, which is a power supply system substrate, is greater than that of the first substrate 26a. If the amount of heat generated becomes excessive, there is a possibility that the components mounted on the second substrate 26b and the soldered portions will be damaged. Therefore, the substrate mounting structure of this configuration has the following heat dissipation structure.

As shown in FIG. 11, a portion of the frame member 38 is formed with a pressing portion 40 that presses, for example, a portion of the second substrate 26b toward the housing 4 side. A heat radiating portion 41 is formed on the back surface of a portion of the second substrate 26 b that faces the pressing portion 40 . It abuts on the provided heat dissipation sheet 42 . That is, at this time, the presser portion 40 is configured to press the back surface of the second substrate 26b so that the heat radiating portion 41 is reliably brought into contact with the heat radiating sheet 42. As shown in FIG.

With this configuration, the heat radiation portion 41 provided on the second substrate 26b can be reliably pressed against the heat radiation sheet 42 of the housing 4 simply by attaching the frame member 38 holding the second substrate 26b and the like in advance to the housing 4, and the heat radiation portion 41 can be reliably pressed against the heat radiation sheet 42 of the housing 4. heat dissipation effect can be obtained.

As in this configuration, the necessary control boards 26 are divided into the first board 26a for the control system and the second board 26b for the power supply system, and the heat dissipation part 41 is provided on the second board 26b to enhance the heat removal effect. can be done. Moreover, since the control board 26 is divided according to the degree of heat generation, it is possible to more effectively prevent damage to soldered portions due to heat generation, particularly in the second board 26b of the power supply system.

Furthermore, the pressing portion 40 of this configuration only presses the heat radiating portion 41 against the heat radiating sheet 42, and does not restrict thermal expansion of the second substrate 26b and the like along their plane direction. Therefore, no unexpected stress is generated in the second substrate 26b, and damage to the soldered portion can be effectively prevented.

(Seal structure)
The first substrate 26a, the second substrate 26b, and the spacer substrate 26c are fixed to the housing 4 while attached to one surface of the frame member 38, and the opposite surface of the frame member 38 is covered with the cover member 43. When the frame member 38 and the cover member 43 are attached to the housing 4 , there is a gap between the peripheral edge of one surface of the frame member 38 and the housing 4 and between the peripheral edge of the other surface of the frame member 38 and the peripheral edge of the cover member 43 . An annular sealing member 44 is arranged between the parts.

The seal member 44 is made of, for example, various rubber members having a circular cross-sectional shape, and has a planar shape corresponding to the peripheral shape of the frame member 38 . A fixing groove 45 into which a sealing member 44 is fitted is formed in at least one of the frame member 38, the cover member 43, and the housing 4, which are arranged to face each other.

This makes it difficult for the seal member 44 to be displaced when the frame member 38 and the cover member 43 are attached, thereby facilitating the attachment work. In addition, it is possible to prevent the seal member 44 from being dislocated after attachment, and to obtain a substrate mounting structure that is excellent in dustproofness and waterproofness over a long period of time.

INDUSTRIAL APPLICABILITY The planetary gear mechanism of the present invention can be widely used in linear motion devices configured to transmit the rotational driving force of a drive motor to a rod that reciprocates while its rotation is restricted.

2 Nut 2a Bulging portion 3 Rod 4 Housing 9 Output gear 10 Threaded portion 11 Bearing portion 11a Inner member 11b Outer member 12 Fixed screw portion 13 Spacer 14 Retaining ring K Carrier K1 First carrier K2 Second carrier Ka First fitting Part Kb Second fitting part M Driving part P Planetary gear mechanism P2 Planetary gear X Axial center

Claims (5)

a housing;
a driving portion provided in the housing;
a rod that reciprocates along an axis while being prevented from rotating with respect to the housing, the linear motion device having a threaded portion to which a driving force is transmitted from the output gear of the driving portion;
a nut screwed onto the threaded portion;
a bearing that rotationally supports the nut on the housing;
a carrier for holding the planetary gears is inserted and fixed into the inner part of the housing with the bearing facing the inner side;
a first carrier that is in contact with the inner member of the bearing and is screwed with the nut;
a second carrier attached to the first carrier and holding the planetary gear;
a retaining ring attached to the inner surface of the housing to fix the outer member of the bearing to the housing. 2. A planetary gear mechanism according to claim 1, wherein the outer diameter of said second carrier is larger than the inner diameter of said retainer ring. The first carrier has a fixed screw portion that meshes with the nut, and the bearing portion is formed inside the bearing portion by the bulging portion protruding from the surface of the nut and the end face of the first carrier. 3. A planetary gear mechanism according to claim 1 or 2, wherein said planetary gear mechanism is configured to clamp a member. The first carrier and the second carrier are fitted by a first fitting portion and a second fitting portion that are connected in two stages along the direction of the axial center, and the second fitting portion 4. The planetary gear mechanism according to claim 1, wherein is a spline fitting portion. 5. The method according to any one of claims 1 to 4, wherein an annular spacer is provided to prevent contact between the outer member of the bearing portion and the retainer ring, and the spacer is fixed to the inner surface of the housing. Planetary gear mechanism.

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