JP6545005B2 - Linear actuator - Google Patents

Description

  The present invention relates to a linear actuator provided with a feed screw mechanism, and more particularly to a linear actuator used for medical equipment, care equipment and the like.

  2. Description of the Related Art Conventionally, an electric linear actuator has been used for medical equipment, nursing equipment and the like in order to reduce the burden on patients and carers. Specifically, the linear actuator is used for raising and lowering operation and reclining operation of a bed, and further for raising and lowering operation of a rising assistant chair. Such a linear actuator is described, for example, in Patent Document 1.

  The linear actuator described in Patent Document 1 is formed substantially in a rod shape, and includes a motor device, a reduction gear, and a linear motion device (feed screw mechanism). The motor device, the reduction gear device and the linear motion device are coaxially arranged. Thus, the rotation of the motor device is decelerated by the reduction gear to increase the torque, and the increased torque is transmitted to the linear motion device. Therefore, a relatively heavy drive target can be easily operated.

  And the electric motor which forms a motor apparatus is accommodated in a motor case, and the reduction gear (reduction mechanism) which forms a reduction gear is accommodated in the 1st, 2nd reduction gear case. Further, the shaft (shaft member) forming the linear motion device is accommodated inside the reinforcing cylinder, and the reinforcing cylinder is attached to a case formed of two parts having a vertically split shape.

JP, 2010-263670, A

  However, in the linear actuator described in Patent Document 1 described above, one bearing is provided in a portion where there is a joint mechanism that connects the speed reduction mechanism and the shaft member. And the reduction mechanism side along the axial direction of the shaft member is rotatably supported only by this one bearing.

  As a result, when an external force (bending moment) that causes the shaft member to tilt acts on the linear actuator, the reduction mechanism side along the axial direction of the shaft member may be twisted with insufficient strength, and the joint mechanism may be tilted. When the joint mechanism is inclined, this external force is also transmitted to the reduction gear mechanism. Therefore, the meshing state of the plurality of gears forming the speed reduction mechanism is deteriorated, and when the meshing state is loose, the operation noise of the reduction gear becomes large, and when the meshing state is tight, the operation resistance of the reduction gear becomes large.

  An object of the present invention is to provide a linear actuator that can realize smooth operation and low noise without transmitting a bending moment acting on a shaft member to a reduction mechanism.

In one aspect of the present invention, a motor having a rotating shaft, a reduction mechanism for reducing the rotation of the rotating shaft, a shaft member connected to an output member of the reduction mechanism, and an external thread of the shaft member are screwed. A female screw member moved in the axial direction of the shaft member with the rotation of the shaft member, a motor case accommodating the motor, and a reduction mechanism case connected to the motor case and accommodating the reduction mechanism. a feed screw mechanism case accommodating said shaft member and said female screw member, the provided female screw member, a piston and out to the feed screw mechanism case, is attached to the speed reduction mechanism casing, rotate the output member A bearing for an output member freely supported , and a connecting member for connecting the reduction gear case and the feed screw mechanism case are provided .

In another aspect of the present invention, the output member side along the axial direction of the shaft member is rotatably supported by at least one shaft member bearing mounted on the reduction gear case.

  In another aspect of the present invention, at least two bearings for shaft members are provided, and the two bearings for shaft members are separated from each other by a collar attached to the shaft members.

In another aspect of the present invention, a motor having a rotating shaft, a reduction mechanism for reducing the rotation of the rotating shaft, a shaft member connected to an output member of the reduction mechanism, and a screw connection with an external thread of the shaft member A female screw member moved in the axial direction of the shaft member with the rotation of the shaft member, a motor case for housing the motor, and a reduction gear case connected to the motor case for housing the reduction gear mechanism , and the shaft member and the feed screw mechanism case accommodating the female screw member, the provided female screw member, a piston and out to the feed screw mechanism case, is attached to the speed reduction mechanism casing, the axis of said shaft member At least two shaft member bearings rotatably supporting the output member side along the direction, and a connecting member connecting the speed reduction mechanism case and the feed screw mechanism case;
Equipped .

  In another aspect of the present invention, the at least two shaft member bearings are separated from each other by a collar mounted on the shaft member.

In another aspect of the present invention, the output member is rotatably supported by an output member bearing attached to the reduction mechanism case.

  According to the present invention, since the output member is rotatably supported by the output member bearing attached to the case, the bending moment acting on the shaft member can be prevented from being transmitted to the speed reduction mechanism.

  Further, according to the present invention, since the output member side along the axial direction of the shaft member is rotatably supported by at least two shaft member bearings mounted on the case, bending moment acting on the shaft member can be reduced. It can be prevented from being transmitted to the speed reduction mechanism.

  Therefore, smooth operation and low noise of the linear actuator can be realized. Furthermore, since no large rotational force is applied to the speed reduction mechanism, abnormal wear and the like of the speed reduction mechanism can be reliably suppressed, and consequently, the life of the linear actuator can be prolonged.

It is a perspective view of a linear actuator concerning the present invention. It is sectional drawing in alignment with the longitudinal direction of the linear actuator of FIG. It is an expanded sectional view which expands and shows the motor part of FIG. (A) is sectional drawing in alignment with the AA of FIG. 2, (b) is sectional drawing in alignment with the BB line of FIG. It is an expanded sectional view which expands and shows the deceleration mechanism part of FIG. It is a perspective view showing a feed screw mechanism case, a connection member, and a reduction mechanism case. (A), (b), (c) is a partial expanded sectional view explaining the assembly procedure to the deceleration mechanism case of a connection member. (A), (b), (c) is a partial expanded sectional view explaining an assembly procedure of a feed screw mechanism to a reduction gear case with which a connection member was attached. It is a top view which shows the state when the external force F which bends a linear actuator (at the time of maximum contraction) acts. It is an expanded sectional view showing the state when external force F which makes a linear actuator (at the time of maximum extension) bend is applied. FIG. 7 is a plan view showing a linear actuator of Embodiment 2; FIG. 10 is a partial enlarged cross-sectional view showing a linear actuator of Embodiment 3; FIG. 16 is a partial enlarged cross-sectional view showing a linear actuator of Embodiment 4; FIG. 16 is a partial enlarged cross-sectional view showing a linear actuator of Embodiment 5;

  Hereinafter, Embodiment 1 of the present invention will be described in detail with reference to the drawings.

  1 is a perspective view of the linear actuator according to the present invention, FIG. 2 is a sectional view along the longitudinal direction of the linear actuator of FIG. 1, and FIG. 3 is an enlarged sectional view showing the motor part of FIG. 4 (a) is a cross-sectional view taken along the line A-A in FIG. 2, (b) is a cross-sectional view taken along the line B-B in FIG. 2, and FIG. 5 is an enlarged cross-section showing the speed reduction mechanism of FIG. FIG. 6 is a perspective view showing the feed screw mechanism case, the connecting member and the reduction mechanism case, respectively.

  The linear actuator 10 shown in FIG. 1 is a feed screw type linear actuator using an electric motor, and is used, for example, as a driving source for raising or lowering the bottom plate (not shown) of a care bed. The linear actuator 10 is mounted on a frame (not shown) of a nursing bed and driven by operation of a hand switch (not shown).

  The linear actuator 10 is formed in a substantially rod shape, and fixing portions 11 and 12 are provided at both ends in the longitudinal direction. And the fixed pin (not shown) provided in the flame | frame and bottom plate of the bed for nursing care is rotatably mounted to each fixing | fixed part 11 and 12. FIG. Thus, for example, the bottom plate is raised by driving the linear actuator 10 so as to extend, and the bottom plate is laid down by driving the linear actuator 10 so as to contract.

  As shown in FIG. 1, the linear actuator 10 includes a drive mechanism 20 and a feed screw mechanism 50, and the drive mechanism 20 and the feed screw mechanism 50 are coaxially arranged, and a connection member 60 is provided. Are connected to each other with a predetermined pull-out strength.

  As shown in FIG. 2, the drive mechanism unit 20 is formed of a motor unit 30 and a reduction mechanism unit 40. The motor unit 30 includes a motor case (case) 31 formed in a substantially cylindrical shape by a magnetic material. A pair of permanent magnets 32 (only one is shown in the figure) having a substantially arc-shaped cross section is fixed to an inner wall near the speed reduction mechanism 40 along the longitudinal direction of the motor case 31. Here, in order to make it easy to understand the arrangement of the permanent magnets 32, in the drawing, the permanent magnets 32 are shaded.

  An armature (rotor) 34 on which the coil 33 is wound is rotatably provided on the inner side in the radial direction of each permanent magnet 32 via a predetermined gap (air gap). Further, an armature shaft (rotational shaft) 35 is fixed to penetrate the rotation center of the armature 34. As described above, the armature 34 and the armature shaft 35 are rotatably accommodated inside the motor case 31.

  At a portion closer to the fixed portion 11 than the armature 34 of the armature shaft 35, a commutator 37 in sliding contact with the pair of brushes 36 is provided. Further, an end of the coil 33 is electrically connected to the commutator 37. As a result, drive current is supplied to the coil 33 of the armature 34 via the brush 36 and the commutator 37. Thus, an electromagnetic force is generated in the armature 34, and the armature 34 rotates with the armature shaft 35 in a predetermined rotational direction and rotational speed. Here, the motor of the present invention is configured by the permanent magnets 32, the coil 33, the armature 34, the armature shaft 35, the brushes 36, and the commutator 37.

  As shown in FIG. 1, a connector connection portion 21 to which an external connector (not shown) is connected is provided on the side of the drive mechanism portion 20. Then, in addition to the operation signal from the hand switch, a drive current for driving the motor unit 30 (see FIG. 2) is supplied from the external connector. The connector connection portion 21 is fixed to a cover member 38 that closes one side of the motor case 31 in the axial direction. In addition, the fixing portion 11 is integrally provided on one side in the axial direction of the cover member 38.

  As shown in FIG. 2, one side (right side in the figure) of the armature shaft 35 in the axial direction is rotatably supported by a first bearing member (ball bearing) 39. The first bearing member 39 is fixed to the cover member 38. Thereby, one axial direction side of the armature shaft 35 can be rotated smoothly without rattling inside the motor case 31.

  The other axial direction side (left side in the drawing) of the armature shaft 35 is extended to the inside of the reduction mechanism case (case) 41 forming the reduction mechanism portion 40. The other axial end of the armature shaft 35 is rotatable by a second bearing member (ball bearing) 42 mounted on the reduction mechanism case 41 via a sun gear 43a (see FIG. 5) of the first reduction mechanism 43. It is supported by As a result, the other axial side of the armature shaft 35 can also rotate smoothly without rattling inside the motor case 31.

  Here, the motor case 31, the reduction mechanism case 41 and the cover member 38 are integrally assembled by a pair of fastening bolts BT. The pair of fastening bolts BT are disposed inside and radially outward of the motor case 31 and further disposed between a pair of permanent magnets 32 provided to face the inside of the motor case 31. As a result, the motor case 31 is prevented from increasing in size (diameter increase) in the radial direction.

  Inside the reduction mechanism case 41 and near the second bearing member 42 along the longitudinal direction, there are a first reduction mechanism (reduction mechanism) 43 and a second reduction mechanism (reduction mechanism) 44 consisting of a planetary gear reducer. It is housed. Here, in the present embodiment, by overlapping the first reduction gear mechanism 43 and the second reduction gear mechanism 44 set to a predetermined reduction ratio in two steps, the enlargement of the entire reduction gear mechanism in the radial direction is suppressed. , A large reduction ratio is obtained. Thereby, the enlargement of the motor unit 30 and the reduction mechanism unit 40 in the radial direction is suppressed, and the radial dimension of the drive mechanism unit 20 is made substantially the same as the radial dimension of the feed screw mechanism unit 50. The entire shape of the linear actuator 10 is a straight shape without any step.

  As shown in FIGS. 4A and 5, the first reduction gear mechanism 43 meshes with the sun gear 43a fixed to the other side in the axial direction of the armature shaft 35 and the sun gear 43a and rolls around the sun gear 43a. Three planetary gears 43b, a carrier 43c for supporting each planetary gear 43b, and a ring gear 43d formed on the inner wall of the reduction mechanism case 41 and engaged with each planetary gear 43b. As a result, the rotation of the armature shaft 35 is decelerated and the torque is increased, and output from the carrier 43 c to the second reduction mechanism 44.

  Further, as shown in FIGS. 4B and 5, the second reduction gear mechanism 44 engages with the sun gear 44 a integrally provided on the carrier 43 c of the first reduction gear mechanism 43 and the sun gear 44 a so as to surround the sun gear 44 a. It includes three planetary gears 44b which roll, a carrier (output member) 44c which supports each planetary gear 44b, and a ring gear 44d which is formed on the inner wall of the reduction mechanism case 41 and which is engaged with each planetary gear 44b. Thus, the rotation of the carrier 43c of the first reduction mechanism 43 is decelerated and the torque is increased, and the carrier 44c is output from the carrier 44c to the feed screw mechanism 50.

  Here, the ring gear 43d of the first reduction gear mechanism 43 and the ring gear 44d of the second reduction gear mechanism 44 both have teeth of the same size (the same module). Therefore, the ring gears 43d and 44d can be simultaneously formed on the inner wall of the speed reduction mechanism case 41, and the forming operation of the ring gears 43d and 44d will not be complicated.

  As shown in FIG. 2, a third bearing member (bearing for output member) 45 and a fourth bearing member (shaft member) are provided inside the reduction gear mechanism case 41 and near the feed screw mechanism 50 along the longitudinal direction. And a bearing 46) are provided coaxially.

  The third bearing member 45 is a ball bearing having an outer ring 45a, an inner ring 45b, and a plurality of steel balls 45c. The outer ring 45 a of the third bearing member 45 is mounted on the speed reduction mechanism case 41. The inner ring 45 b of the third bearing member 45 is fixed to the carrier 44 c of the second reduction gear mechanism 44. That is, the third bearing member 45 rotatably supports the carrier 44 c of the second reduction mechanism 44.

  Thus, the sun gear 43a of the first reduction gear mechanism 43 is rotatably supported by the second bearing member 42, and the carrier 44c of the second reduction gear mechanism 44 is rotatably supported by the third bearing member 45. In the inside of the reduction gear mechanism case 41, meshing of gears forming the first reduction gear mechanism 43 and the second reduction gear mechanism 44 (two-step reduction gear mechanism) is made smooth. Therefore, the operation noise of the two-stage reduction mechanism can be reduced and the life can be prolonged, and the loss of power transmission from the motor unit 30 to the feed screw mechanism unit 50 can be minimized.

  The fourth bearing member 46 is a ball bearing having an outer ring 46a, an inner ring 46b and a plurality of steel balls 46c. The outer ring 46 a of the fourth bearing member 46 is mounted on the speed reduction mechanism case 41. The inner ring 46b of the fourth bearing member 46 is fixed to one side in the axial direction of the shaft 52 forming the feed screw mechanism 50, that is, on the side of the carrier 44c along the axial direction of the shaft 52. More specifically, the inner ring 46 b is fixed to the small diameter mounting portion 52 a on one side in the axial direction of the shaft 52. That is, the fourth bearing member 46 rotatably supports the carrier 44 c side along the axial direction of the shaft 52.

  Thereby, at the time of operation of the linear actuator 10, the rotational runout of the axial direction one side of the shaft 52 is effectively suppressed. Therefore, the linear actuator 10 can be operated smoothly, and the operation noise generated from the linear actuator 10 is reduced.

  Here, an involute serration 52 b is provided on one side in the axial direction of the shaft 52, and the involute serration 52 b is fitted to the carrier 44 c of the second reduction mechanism 44 so as to be able to transmit a rotational force. Thereby, the driving force from the carrier 44 c is efficiently transmitted to the shaft 52.

  As shown in FIG. 2, the feed screw mechanism unit 50 includes a feed screw mechanism case (case) 51 formed of a hollow pipe. The feed screw mechanism case 51 is provided coaxially with the motor case 31 and the reduction mechanism case 41, and has a length dimension longer than the motor case 31 as shown in FIG. Specifically, the length dimension of the feed screw mechanism case 51 is determined by the amount of expansion and contraction of the piston tube 54.

  As shown in FIG. 2, at one axial side of the feed screw mechanism case 51, a fitting portion 51 a to be fitted to the small diameter main body portion 41 a of the speed reduction mechanism case 41 is provided. Here, the thickness dimension t1 of the fitting portion 51a is set to be slightly smaller than the step dimension t2 (see FIG. 6) formed by the large diameter main body portion 41b and the small diameter main body portion 41a of the reduction gear mechanism case 41. (T1 <t2). As a result, when the feed screw mechanism case 51 and the reduction mechanism case 41 are connected, the overall shape of the linear actuator 10 can be made substantially straight.

  As shown in FIG. 2, a shaft (shaft member) 52 rotated by the carrier 44 c of the second reduction gear mechanism 44 is rotatably accommodated in the feed screw mechanism case 51. A male screw portion 52c is formed on the outer peripheral portion of the shaft 52, and a screw nut (female screw member) 53 is screwed to the male screw portion 52c. That is, the screw nut 53 moves in the axial direction of the shaft 52 as the shaft 52 rotates. Specifically, when the shaft 52 is rotated forward, the screw nut 53 moves to the right in the figure, and the linear actuator 10 is reduced accordingly. On the other hand, when the shaft 52 is reversely rotated, the screw nut 53 moves to the left in the figure, and thus the linear actuator 10 is extended.

  Here, on the outer peripheral portion of the screw nut 53, a recessed groove (not shown) extending in the axial direction is formed. On the other hand, on the inner peripheral portion of the feed screw mechanism case 51, a convex portion (not shown) extending in the axial direction is formed. The screw nut 53 is not rotated by the rotation of the shaft 52 by causing the concave groove of the screw nut 53 and the convex portion of the feed screw mechanism case 51 to be slidably engaged with each other in a sliding manner. It is designed to move only in the axial direction.

  One axial direction side of a piston tube (piston) 54 formed of a hollow pipe is fixed to the screw nut 53. The piston tube 54 is provided between the feed screw mechanism case 51 and the shaft 52, and the piston tube 54 can freely move in and out of the feed screw mechanism case 51. Here, a feed screw mechanism is configured by the shaft 52, the screw nut 53 and the piston tube 54.

  The outer peripheral side of the piston tube 54 is movably supported by a tube guide 55 fixed to the other side of the feed screw mechanism case 51 in the axial direction. The tube guide 55 is fixed by the fixing cap 56 on the other side of the feed screw mechanism case 51 in the axial direction.

  On the other side in the axial direction of the shaft 52, an annular sliding contact member 57 in sliding contact with the inner peripheral side of the piston tube 54 is provided. The sliding contact member 57 is configured to rotate with the shaft 52 inside the piston tube 54. Here, on the outer peripheral portion of the sliding contact member 57, a sliding ring (not shown) is provided which makes sliding on the piston tube 54 smooth. As this slip ring, for example, one made of polytetrafluoroethylene resin (PTFE) is used. The sliding contact member 57 also has a function of suppressing rotational runout of the shaft 52 on the other side in the axial direction by preventing the axial center of the shaft 52 from shifting with respect to the axial center of the piston tube 54.

  A plug 58 for closing the other axial direction side of the piston tube 54 is inserted in the other axial direction side of the piston tube 54, and the plug 58 is fixed to the piston tube 54 so as not to be rotatable relative to the piston tube 54. The plug 58 is provided with a fixing portion 12 to which a fixing pin provided on a frame or a bottom plate of a care bed is attached.

  As shown in FIGS. 5 and 6, the connecting member 60 is formed in a tubular shape by cutting a pipe made of a steel plate into a predetermined length, and the length dimension of the connecting member 60 is the first reduction gear mechanism 43 and the second reduction gear mechanism. The length dimension is set to be slightly shorter than the length dimension obtained by overlapping 44 in two stages. The connecting member 60 connects the speed reduction mechanism case 41 and the feed screw mechanism case 51, and the first side of the connecting member 60 is opposed to the first side of the connecting member 60 in the radial direction of the connecting member 60. An engagement claw 61 is provided.

  Further, on the other side in the axial direction of the connecting member 60, two second engaging claws 62 are provided so as to face each other in the radial direction of the connecting member 60. The first and second engagement claws 61 and 62 are formed by cutting and raising a part of the connection member 60 by performing press processing in the plate thickness direction of the connection member 60.

  Each first engagement claw 61 is protruded toward the side of the feed screw mechanism case 51 along the axial direction of the connecting member 60. On the other hand, each second engagement claw 62 is protruded toward the reduction mechanism case 41 along the axial direction of the connection member 60. That is, the tip end sides of the first and second engagement claws 61 and 62 face each other along the axial direction of the connecting member 60. Further, the front end sides of the first and second engagement claws 61 and 62 are bent inward in the radial direction of the connecting member 60 when the first and second engagement claws 61 and 62 are formed.

  Then, in a state where the linear actuator 10 is assembled, the first engagement claws 61 are engaged with the first annular groove 41 c formed in the outer peripheral portion of the large diameter main portion 41 b of the reduction mechanism case 41. . On the other hand, each second engagement claw 62 is engaged with a second annular groove 51 b formed in the outer peripheral portion of the fitting portion 51 a of the feed screw mechanism case 51.

  Next, an assembling procedure of the linear actuator 10 formed as described above, particularly, a connecting procedure of the drive mechanism 20 and the feed screw mechanism 50 using the connecting member 60 will be described in detail with reference to the drawings.

  7 (a), (b) and (c) are partial enlarged cross-sectional views for explaining the assembling procedure of the connecting member to the reduction mechanism case, and FIGS. 8 (a), (b) and (c) are the connecting member The partial enlarged sectional view which respectively demonstrates the assembly procedure of the feed screw mechanism with respect to the speed-reduction mechanism case which was assembled is shown.

  As shown by the broken line arrow M1 in FIG. 7A, first, the first engaging claws 61 side of the connecting member 60 are made to face the large diameter main portion 41b of the speed reduction mechanism case 41. Next, as shown in FIG. 7B, the connecting member 60 is fitted to the large-diameter main portion 41b in a state in which the axial center of the connecting member 60 and the axial center of the speed reduction mechanism case 41 coincide with each other. To go. As a result, as indicated by the broken line arrow M2, the first engagement claws 61 are elastically deformed, and the connection member 60 is fitted to the large diameter main portion 41b under the state.

  Thereafter, as shown in FIG. 7C, by continuously advancing the fitting of the two, one axial direction side of the connecting member 60 abuts on the first stopper wall 41 d of the reduction gear mechanism case 41. Along with this, each of the first engagement claws 61 elastically deformed by the large diameter main body portion 41b is returned to the original as shown by the dashed arrow M3 and engaged with the first annular groove 41c. Thereby, the assembly | attachment to the deceleration mechanism case 41 (drive mechanism part 20) of the connection member 60 is completed.

  Thus, the connection member 60 can be assembled to the reduction mechanism case 41 with one touch only by sliding the connection member 60 in one direction with respect to the reduction mechanism case 41. In addition, since the tip end side of each first engagement claw 61 is engaged with the first annular groove 41 c in a tensioning direction with respect to the direction in which the connection member 60 is disengaged from the reduction mechanism case 41, sufficient disengagement strength is ensured. Can.

  Next, as shown by the broken line arrow M4 in FIG. 8A, the fitting portion 51a of the feed screw mechanism case 51 is made to face the speed reduction mechanism case 41 to which the connecting member 60 is assembled. At this time, while keeping the axis of the feed screw mechanism 50 and the axis of the reduction mechanism case 41 coincident with each other, in the annular gap CS between the small diameter main body 41 a of the reduction mechanism case 41 and the connecting member 60. , And the fitting portion 51a is inserted. As a result, as shown by the broken line arrow M5 in FIG. 8B, each second engagement claw 62 is elastically deformed, and the fitting portion 51a is fitted to the small diameter main body portion 41a under the state. .

  Thereafter, as shown in FIG. 8C, by continuously advancing the fitting of the two, one axial direction side of the fitting portion 51 a abuts on the second stopper wall 41 e of the reduction mechanism case 41. Along with this, each of the second engagement claws 62 elastically deformed by the fitting portion 51a returns to the original state as shown by the broken line arrow M6 and is engaged with the second annular groove 51b. Thus, the connection between the drive mechanism 20 and the feed screw mechanism 50 is completed.

  As a result, the feed screw mechanism case 51 can be assembled to the reduction mechanism case 41 with one touch only by sliding the feed screw mechanism case 51 in one direction with respect to the reduction mechanism case 41. In addition, since the tip end side of each second engaging claw 62 is engaged with the second annular groove 51b so as to be tensioned in the disengaging direction of the feed screw mechanism case 51 with respect to the decelerating mechanism case 41, sufficient disengaging strength is ensured. can do.

  Next, the external force F acting on the linear actuator 10 when the linear actuator 10 is used will be described in detail with reference to the drawings.

  FIG. 9 is a plan view showing a state in which an external force F for bending a linear actuator (at the maximum reduction) acts, and FIG. 10 shows a state in which an external force F for bending a linear actuator (at the maximum extension) is applied. The enlarged sectional view is shown, respectively.

  As shown in FIG. 9, the linear actuator 10 is a long object, and fixed to the frame or bottom plate of the care bed via the fixing portions 11 and 12 on both sides in the longitudinal direction of the linear actuator 10. The pins are rotatably mounted respectively. Therefore, when the linear actuator 10 is extended from the minimum reduction state, an external force (bending moment) F is applied to each of the fixed portions 11 and 12 in the direction of bending the linear actuator 10 about the bending center O. . Here, the bending center O of the linear actuator 10 is provided at a connection portion between the drive mechanism 20 and the feed screw mechanism 50, that is, at a portion where the connection member 60 is present.

  In the present embodiment, the first engagement claws 61 and the second engagement claws 62 of the coupling member 60 are arranged in the extending direction of the orthogonal reference line DR extending in the direction orthogonal to the axial direction of the bending center O It is done. Thereby, when the drive mechanism 20 and the feed screw mechanism 50 are bent at the relative angle α ° around the bending center O by the external force F, for example, the respective first engagement claws 61 and the respective second engagements A relatively large load is applied to the joint claws 62, respectively. However, in the present embodiment, since sufficient pull-out strength is secured by the connection member 60 as described above, the connection state between the drive mechanism 20 and the feed screw mechanism 50 is not released.

  Here, even if the connection between the drive mechanism 20 and the feed screw mechanism 50 is loosened, the linear actuator 10 is subjected to a load in a direction to reduce the linear actuator 10. As a result, the connection between the drive mechanism 20 and the feed screw mechanism 50 is not released.

  Further, as shown by the broken line arrow M7 in FIG. 10, when most part of the piston tube 54 is protruded from the feed screw mechanism case 51 by the extension operation of the linear actuator 10, the piston by the external force F shown in FIG. One axial side of the tube 54 is inclined as indicated by a broken arrow M8. Along with this, one side in the axial direction of the shaft 52 is inclined as shown by a broken arrow M9. Here, a thick broken line shown in FIG. 10 shows an image in which the piston tube 54 and the shaft 52 are inclined.

  As described above, although the external force F is loaded on the shaft 52 in the direction in which the shaft 52 is inclined, the small-diameter mounting portion 52a at one axial side of the shaft 52 is supported by the fourth bearing member 46 . Further, the involute serration 52 b on one side in the axial direction of the shaft 52 is supported by the third bearing member 45 via the carrier 44 c of the second reduction mechanism 44.

  Accordingly, since the inclination of one side in the axial direction of the shaft 52 is reliably suppressed, the second reduction mechanism 44 is not twisted, and the smooth operation of the drive mechanism unit 20 is ensured. In addition, smooth entry and exit of the piston tube 54 from the feed screw mechanism case 51 is ensured. As described above, the linear actuator 10 according to the present embodiment is excellent in the quietness of the drive portion, and has a suitable specification for use in a care bed or the like.

  As described above in detail, according to the linear actuator 10 according to the present embodiment, since the carrier 44 c is rotatably supported by the third bearing member 45 mounted on the reduction mechanism case 41, the shaft 52 It is possible not to transmit the acting bending moment (external force F) to the first and second reduction mechanisms 43 and 44.

  Therefore, smooth operation and noise reduction of the linear actuator 10 can be realized. Furthermore, since no large rotational force is applied to the first and second reduction mechanisms 43 and 44, abnormal wear and the like of the first and second reduction mechanisms 43 and 44 can be reliably suppressed, and thus the long life of the linear actuator 10 can be obtained. Can be implemented.

  Further, according to the linear actuator 10 according to the present embodiment, since the carrier 44 c side along the axial direction of the shaft 52 is rotatably supported by the fourth bearing member 46 mounted on the reduction mechanism case 41, the shaft The bending moment (external force F) acting on 52 can be prevented from being more reliably transmitted to the first and second reduction mechanisms 43 and 44.

  Next, a linear actuator according to Embodiment 2 of the present invention will be described in detail using the drawings. The parts having the same functions as those in the first embodiment described above are denoted by the same reference numerals, and the detailed description thereof is omitted.

  FIG. 11 is a plan view showing the linear actuator of the second embodiment.

  As shown in FIG. 11, in the second embodiment, compared with the first embodiment, the first and second engaging claws 61 and 62 provided on the connecting member 60 are at the bending center O of the linear actuator 10. The only difference is that they are arranged axially. That is, the first and second engagement claws 61 and 62 of the connection member 60 in the second embodiment are the same as the first and second engagement claws 61 and 62 (see FIG. 9) of the connection member 60 in the first embodiment. On the other hand, they are arranged at a position shifted by 90 ° in the circumferential direction of the connecting member 60.

  Also in the second embodiment formed as described above, the same effects as those of the first embodiment described above can be obtained. In addition to this, in the second embodiment, since the first and second engagement claws 61 and 62 are arranged in the axial direction of the bending center O of the linear actuator 10, compared to the first embodiment. The load applied to the first and second engagement claws 61 and 62 can be reduced. Therefore, it is possible to reliably prevent rattling of the connection portion between the drive mechanism 20 and the feed screw mechanism 50, and to further improve the quietness.

  Next, a linear actuator according to Embodiment 3 of the present invention will be described in detail using the drawings. The parts having the same functions as those in the first embodiment described above are denoted by the same reference numerals, and the detailed description thereof is omitted.

  FIG. 12 shows a partially enlarged sectional view showing the linear actuator of the third embodiment.

  As shown in FIG. 12, the linear actuator 70 according to the third embodiment is provided with a connecting member integrally with the motor case as compared with the linear actuator 10 according to the first embodiment (see FIG. 2); The only difference is that the first annular groove 41c of the speed reduction mechanism case 41 is omitted.

  Specifically, the linear actuator 70 includes a motor case (case) 71. A cylindrical connecting member 72 is integrally provided at a portion near the reduction mechanism portion 40 along the longitudinal direction of the motor case 71. Two engaging claws 73 are provided on the other longitudinal side (left side in the drawing) of the connecting member 72 so as to face from the radial direction of the connecting member 72. The engagement claws 73 are formed by cutting and raising a part of the connection member 72 by performing press processing in the plate thickness direction of the connection member 72.

  Each engaging claw 73 is protruded toward the motor portion 30 side along the axial direction of the connecting member 72. That is, the projecting direction of each engaging claw 73 is the same as the projecting direction of the second engaging claw 62 in the first embodiment. Further, the tip end side of each engaging claw 73 is bent inward in the radial direction of the connecting member 72 in advance when each engaging claw 73 is formed. Then, in a state where the linear actuator 70 is assembled, the engagement claws 73 are engaged with the second annular groove 51 b formed in the outer peripheral portion of the fitting portion 51 a of the feed screw mechanism case 51.

  Here, the engagement claws 73 are elastically deformed by the feed screw mechanism case 51 to allow the motor case 71 and the feed screw mechanism case 51 to approach each other. Further, the engagement claws 73 engage with the second annular groove 51b to restrict the motor case 71 and the feed screw mechanism case 51 from being separated from each other. Thus, the connection between the drive mechanism 20 and the feed screw mechanism 50 is completed only by sliding the feed screw mechanism case 51 with respect to the motor case 71 from one direction, and the assembly of the linear actuator 70 is completed.

  Also in the third embodiment formed as described above, the same effects as those of the first embodiment described above can be obtained. In addition to this, in the third embodiment, since the connecting member 72 is integrally provided to the motor case 71, the number of engaging claws 73 provided on the connecting member 72 can be halved compared to the first embodiment. . Therefore, the amount of rattling generated from the connection portion between the drive mechanism 20 and the feed screw mechanism 50 can be halved, and the silence can be further improved. In addition, since a separate connecting member is not required, rationalization of parts management and simplification of the assembly process can be achieved. Furthermore, the appearance of the linear actuator 70 can be made clear, and the appearance can be improved.

  Here, as in the configuration of the second embodiment shown in FIG. 11, the respective engaging claws 73 of the third embodiment can also be arranged in the axial direction of the bending center O. In this case, the load applied to each engagement claw 73 can be reduced. Therefore, occurrence of rattling in the connection portion between the drive mechanism 20 and the feed screw mechanism 50 can be further reliably suppressed, and the quietness can be further improved.

  Further, the connecting member may be integrally provided on the feed screw mechanism case 51. In this case, the connecting member provided in the feed screw mechanism case 51 is provided with an engaging claw having the same projecting direction and shape as the first engaging claw 61 in the first embodiment. Furthermore, for example, the small diameter main body portion 41 a of the reduction gear mechanism case 41 is provided with a groove portion with which the engagement claw is engaged.

  Next, a linear actuator according to Embodiment 4 of the present invention will be described in detail using the drawings. The parts having the same functions as those in the first embodiment described above are denoted by the same reference numerals, and the detailed description thereof is omitted.

  FIG. 13 shows a partially enlarged cross-sectional view showing the linear actuator of the fourth embodiment.

  As shown in FIG. 13, the linear actuator 80 according to the fourth embodiment supports the carrier 44 c of the second reduction gear mechanism 44 compared to the linear actuator 10 according to the first embodiment (see FIG. 10). While the bearing member 45 is omitted, the only difference is that a fifth bearing member (shaft member bearing) 81 is additionally attached to the small diameter attachment portion 52 a of the shaft 52. That is, a total of two of the fourth bearing member 46 and the fifth bearing member 81 are attached to the small diameter attachment portion 52a. Here, the fifth bearing member 81 is the same as the fourth bearing member 46, and is attached to the reduction gear mechanism case 41 and arranged immediately next to each other so as to contact the fourth bearing member 46. . Along with this, the axial length of the small diameter mounting portion 52a is twice as long as that of the first embodiment.

  Also in the fourth embodiment formed as described above, the same function and effect as those of the first embodiment described above can be obtained. In addition to this, in the fourth embodiment, the fourth bearing member 46 and the fifth bearing member 81 having the same specifications suppress the rotational runout on one side of the shaft 52 in the axial direction. Vibration transmission can be suppressed more reliably.

  However, as shown by an imaginary line (two-dot chain line) in FIG. 13, a third bearing member (output member bearing) 45 for supporting the carrier 44 c may be additionally provided. In this case, the drive mechanism unit 20 can be operated more smoothly, and a linear actuator with excellent quietness can be realized.

  Next, a linear actuator according to Embodiment 5 of the present invention will be described in detail using the drawings. The parts having the same functions as those in the first embodiment described above are denoted by the same reference numerals, and the detailed description thereof is omitted.

  FIG. 14 shows a partially enlarged cross-sectional view showing the linear actuator of the fifth embodiment.

  As shown in FIG. 14, the linear actuator 90 according to the fifth embodiment supports the carrier 44 c of the second reduction gear mechanism 44 compared to the linear actuator 10 according to the first embodiment (see FIG. 10). While the bearing member 45 is omitted, the sixth embodiment is different in that a sixth bearing member (shaft member bearing) 91 is additionally attached to the small diameter attachment portion 52a of the shaft 52. Further, a cylindrical tubular member (collar) 92 is interposed between the sixth bearing member 91 and the fourth bearing member 46. That is, the fourth bearing member 46, the cylindrical member 92, and the sixth bearing member 91 are mounted in this order on the small diameter mounting portion 52a. Here, the sixth bearing member 91 is the same as the fourth bearing member 46, and is mounted on the reduction mechanism case 41, and is spaced apart from the fourth bearing member 46 with a separation distance L There is. Along with this, the axial length of the small diameter mounting portion 52a is approximately four times the length of the first embodiment.

  Also in the fifth embodiment formed as described above, the same function and effect as those of the first embodiment described above can be obtained. Further, as compared with the fourth embodiment, the rotational runout on one side of the shaft 52 in the axial direction can be more reliably suppressed, and the vibration transmission of the shaft 52 to the second reduction mechanism 44 can be suppressed more reliably.

  However, as shown by an imaginary line (two-dot chain line) in FIG. 14, a third bearing member (bearing for output member) 45 that supports the carrier 44 c may be additionally provided. In this case, the drive mechanism unit 20 can be operated more smoothly, and a linear actuator with excellent quietness can be realized.

  The present invention is not limited to the above embodiments, and it goes without saying that various changes can be made without departing from the scope of the invention. For example, although the above-mentioned each embodiment showed what used linear actuator 10, 70, 80, 90 as a drive source for making the baseplate of a bed for nursing care rise or fall, the present invention is limited to this Instead, it can also be used as a drive source for adjusting the height of the walker, or a drive source for raising and lowering an auxiliary chair and a lift for movement.

  In each of the above embodiments, two first engaging claws 61, second engaging claws 62 and engaging claws 73 are provided at intervals of 180 ° in the circumferential direction of the connecting members 60 and 72. Although shown, the present invention is not limited to this, and one or three or more engaging claws may be provided in the circumferential direction of the connecting member. When three or more engaging claws are provided, the intervals between them may be equal intervals or not equal intervals in the circumferential direction of the connecting member. In short, the engagement claws can be arbitrarily set in accordance with the removal strength and the like (specification of the linear actuator) required for the linear actuator.

  Furthermore, in the first and second embodiments described above, the connecting member 60 is assembled to the speed reduction mechanism case 41 first, but the present invention is not limited to this. May be assembled first.

  In the fourth and fifth embodiments, the small diameter mounting portion 52a of the shaft 52 has two shaft member bearings (fourth bearing member 46 and fifth bearing member 81, fourth bearing member 46 and sixth bearing member Although the case where 91) is provided is shown, the present invention is not limited to this, and three or more shaft member bearings may be provided in the small diameter mounting portion 52a. The point is that the number of shaft member bearings can be increased according to the rigidity required on the side of the carrier 44c along the axial direction of the shaft 52.

DESCRIPTION OF SYMBOLS 10 linear actuator 11, 12 fixing | fixed part 20 drive mechanism part 21 connector connection part 30 motor part 31 motor case (case)
32 Permanent Magnet (Motor)
33 coil (motor)
34 armature (motor)
35 armature shaft (motor, rotary shaft)
36 Brush (motor)
37 Commutator (motor)
38 cover member 39 first bearing member 40 speed reduction mechanism 41 speed reduction mechanism case (case)
41a small diameter main body portion 41b large diameter main body portion 41c first annular groove 41d first stopper wall 41e second stopper wall 42 second bearing member 43 first reduction mechanism (deceleration mechanism)
43a Sun gear 43b Planetary gear 43c Carrier 43d Ring gear 44 Second reduction mechanism (reduction mechanism)
44a Sun gear 44b Planetary gear 44c Carrier (output member)
44d ring gear 45 third bearing member (bearing for output member)
45a Outer ring 45b Inner ring 45c Steel ball 46 Fourth bearing member (bearing for shaft member)
46a outer ring 46b inner ring 46c steel ball 50 feed screw mechanism 51 feed screw mechanism case (case)
51a fitting portion 51b second annular groove 52 shaft (shaft member)
52a Small diameter mounting portion 52b Involute serration 52c Male thread 53 Screw nut (female thread member)
54 Piston tube (piston)
55 tube guide 56 fixing cap 57 sliding contact member 58 plug 60 connecting member 61 first engagement claw 62 second engagement claw 70 linear actuator 71 motor case (case)
72 connecting member 73 engaging claw 80 linear actuator 81 fifth bearing member (bearing for shaft member)
90 linear actuator 91 sixth bearing member (bearing for shaft member)
92 Tube member (color)
BT Fastening bolt CS Annular gap O Bending center

Claims (6)

A motor having a rotating shaft,
A reduction mechanism that decelerates the rotation of the rotating shaft;
A shaft member connected to an output member of the speed reduction mechanism;
A female screw member screwed to the male screw portion of the shaft member and moved in the axial direction of the shaft member as the shaft member rotates;
A motor case for housing the motor;
A reduction mechanism case connected to the motor case and accommodating the reduction mechanism;
A feed screw mechanism case accommodating said shaft member and said female screw member,
A piston which is provided to the female screw member and which moves in and out of the feed screw mechanism case ;
An output member bearing mounted on the reduction mechanism case and rotatably supporting the output member ;
A connecting member for connecting the speed reduction mechanism case and the feed screw mechanism case;
Equipped with
Linear actuator. In the linear actuator according to claim 1,
The output member side along the axial direction of the shaft member is rotatably supported by at least one shaft member bearing mounted on the reduction gear case.
Linear actuator. In the linear actuator according to claim 2,
At least two shaft member bearings are provided, and the two shaft member bearings are separated from each other by a collar mounted on the shaft member.
Linear actuator. A motor having a rotating shaft,
A reduction mechanism that decelerates the rotation of the rotating shaft;
A shaft member connected to an output member of the speed reduction mechanism;
A female screw member screwed to the male screw portion of the shaft member and moved in the axial direction of the shaft member as the shaft member rotates;
A motor case for housing the motor;
A reduction mechanism case connected to the motor case and accommodating the reduction mechanism;
A feed screw mechanism case accommodating said shaft member and said female screw member,
A piston which is provided to the female screw member and which moves in and out of the feed screw mechanism case ;
At least two shaft member bearings mounted on the speed reduction mechanism case and rotatably supporting the output member side along the axial direction of the shaft member ;
A connecting member for connecting the speed reduction mechanism case and the feed screw mechanism case;
Equipped with
Linear actuator. In the linear actuator according to claim 4,
The at least two shaft member bearings are separated from each other by a collar mounted on the shaft member,
Linear actuator. In the linear actuator according to claim 4 or 5,
The output member is rotatably supported by an output member bearing attached to the reduction mechanism case.
Linear actuator.

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