JP2017005825A - Linear actuator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a linear actuator capable of enhancing versatility.SOLUTION: By engaging first and second engagement claws 61, 62 provided in a cylindrical coupling member 60 with first and second annular grooves 41c, 51b, a reduction gear mechanism case 41 and a feed screw mechanism case 51 are prevented from coming off, and sufficient withdrawal strength can be ensured. Since the first and second engagement claws 61, 62 are formed by cutting and raising a part of the coupling member 60, while forming the coupling member 60 of a pipe material consisting of a steel plate, thickening of the linear actuator can be suppressed at the part of the coupling member 60. The whole shape of the linear actuator is thereby made straight by eliminating the step, while thinning, and versatility can be enhanced.SELECTED DRAWING: Figure 6

Description

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

  Conventionally, electric linear actuators have been used in medical devices, care devices, and the like in order to reduce the burden on patients and caregivers. Specifically, the linear actuator is used for a lifting / lowering operation of a bed, a reclining operation, and a lifting / lowering operation of a standing auxiliary chair. Such a linear actuator is described in Patent Document 1, for example.

  The linear actuator described in Patent Document 1 is formed in a substantially rod shape, and includes a motor device, a reduction device, and a linear motion device (feed screw mechanism). These motor device, reduction gear device, and linear motion device are arranged coaxially. As a result, 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, it is possible to easily operate a driving object that is relatively heavy.

  And the electric motor which forms a motor apparatus is accommodated in a motor case, and the reduction gear which forms a reduction gear is accommodated in the 1st, 2nd reduction gear case. Further, the linear motion mechanism that forms the linear motion device is housed inside the reinforcing cylinder, and the reinforcing cylinder is attached to a case made of two vertically-divided parts.

JP 2010-263670 A

  However, in the linear actuator described in the above-mentioned Patent Document 1, in order to ensure sufficient pulling strength with respect to the case of the reinforcing cylinder, a substantially half portion along the longitudinal direction of the reinforcing cylinder is formed with a relatively thick case. It is covered with. Therefore, the thickness of the reinforcing cylinder side along the longitudinal direction of the linear actuator is reduced, and the thickness of the case side along the longitudinal direction of the linear actuator is increased. Therefore, the entire shape of the linear actuator becomes a stepped shape, which causes a problem that versatility of the linear actuator is reduced.

  In other words, in order to increase the versatility of the linear actuator, not only ensure sufficient disconnection strength at the connecting part of the case, but also the overall shape of the linear actuator is made straight without any steps, and its thickness is increased. It is desirable to make it thinner.

  The objective of this invention is providing the linear actuator which can improve versatility.

  In one aspect of the present invention, a motor having a rotation shaft, a speed reduction mechanism that reduces the rotation of the rotation shaft, a first case that houses the motor and the speed reduction mechanism, and a male screw portion that is rotated by the speed reduction mechanism. A shaft member, a second case that is provided coaxially with the first case, accommodates the shaft member, and is screwed to the male screw portion, and moves in the axial direction of the shaft member as the shaft member rotates. A female screw member, a piston member that is provided on the female screw member and enters and exits from the second case, and a cylindrical connecting member that connects the first case and the second case, and the connecting member includes: A pair of engaging claws projecting radially inward are elastically deformed by the first case and the second case, so that the first case and the second case are mutually connected. Close Allowing the, by engaging a groove provided in each of the first case and the second case, to restrict the first case and the second case are separated from each other.

  In another aspect of the present invention, a motor having a rotation shaft, a speed reduction mechanism that reduces the rotation of the rotation shaft, a first case that houses the motor and the speed reduction mechanism, and a male screw portion that is rotated by the speed reduction mechanism A shaft member that is provided coaxially with the first case, and is screwed to the male screw portion in the axial direction of the shaft member as the shaft member rotates. A female screw member that is moved, a piston member that is provided on the female screw member, and that moves in and out of the second case; and a cylindrical connecting member that connects the first case and the second case; The engaging claw protruding radially inward and provided on one of the first case and the second case, the engaging claw being one of the first case and the second case. No By being elastically deformed by the other, the first case and the second case are allowed to approach each other, and engage with a groove provided in the other of the first case and the second case. This restricts the first case and the second case from separating from each other.

  In another aspect of the present invention, the linear actuator includes a bending center that is a center when bent by an external force load, and the engaging claw is disposed in an axial direction of the bending center.

  According to the present invention, the engaging claw provided on the cylindrical connecting member is engaged with the groove portion, thereby preventing the first case and the second case from coming off each other, thereby ensuring sufficient pulling strength. I did it. While forming the connecting member with a tubular material made of steel plate, etc., it is possible to cut and raise a part of the tube material to form the engaging claw, so that the thickness of the linear actuator is increased in the portion where the connecting member is present. Can be suppressed. Accordingly, the overall shape of the linear actuator can be reduced to a straight shape without a step, and the thickness thereof can be reduced, thereby improving versatility.

It is a perspective view of the linear actuator which concerns on this invention. It is sectional drawing which follows 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 which follows the AA line of FIG. 2, (b) is sectional drawing which follows 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 which shows a feed screw mechanism case, a connection member, and a deceleration mechanism case. (A), (b), (c) is the elements on larger scale explaining the assembly | attachment procedure to the deceleration mechanism case of a connection member. (A), (b), (c) is a partial expanded sectional view explaining the assembly | attachment procedure of the feed screw mechanism with respect to the deceleration mechanism case with which the connection member was assembled | attached. It is a top view which shows a state when the external force F which bends a linear actuator (at the time of shrinking | reduction) acts. It is an expanded sectional view which shows a state when the external force F which bends a linear actuator (at the time of the maximum extension) acts. FIG. 5 is a plan view showing a linear actuator according to a second embodiment. FIG. 6 is a partial enlarged cross-sectional view showing a linear actuator according to a third embodiment. FIG. 6 is a partial enlarged cross-sectional view showing a linear actuator according to a fourth embodiment. FIG. 10 is a partial enlarged cross-sectional view showing a linear actuator of a fifth embodiment.

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

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

  A 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 drive source for raising or lowering a bottom plate (not shown) of a care bed. The linear actuator 10 is mounted on a frame (not shown) of the care bed and is driven by operating a hand switch (not shown).

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

  As shown in FIG. 1, the linear actuator 10 includes a drive mechanism unit 20 and a feed screw mechanism unit 50, and the drive mechanism unit 20 and the feed screw mechanism unit 50 are arranged coaxially and are connected to each other. Are connected to each other with a predetermined pulling strength.

  As shown in FIG. 2, the drive mechanism unit 20 is formed of a motor unit 30 and a speed reduction mechanism unit 40. The motor unit 30 includes a motor case (first case) 31 formed of a magnetic material in a substantially cylindrical shape. A pair of permanent magnets 32 (only one is shown in the figure) are fixed to the inner wall of the motor case 31 near the speed reduction mechanism 40 along the longitudinal direction. Here, in order to facilitate understanding of the arrangement relationship of the permanent magnets 32, the permanent magnets 32 are shaded in the drawing.

  Inside each permanent magnet 32 in the radial direction, an armature (rotor) 34 around which a coil 33 is wound is rotatably provided via a predetermined gap (air gap). In addition, an armature shaft (rotating shaft) 35 is fixed through the rotation center of the armature 34. As described above, the armature 34 and the armature shaft 35 are rotatably accommodated in the motor case 31.

  A commutator 37 with which the pair of brushes 36 are slidably contacted is provided on a portion of the armature shaft 35 closer to the fixed portion 11 than the armature 34. Further, the end of the coil 33 is electrically connected to the commutator 37. As a result, a drive current is supplied to the coil 33 of the armature 34 via the brush 36 and the commutator 37. Therefore, an electromagnetic force is generated in the armature 34, and the armature 34 rotates with the armature shaft 35 in a predetermined rotation direction and rotation speed. Here, each permanent magnet 32, coil 33, armature 34, armature shaft 35, each brush 36, and commutator 37 constitute a motor of the present invention.

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

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

  The other side (left side in the figure) of the armature shaft 35 extends to the inside of a speed reduction mechanism case (first case) 41 that forms the speed reduction mechanism 40. The other side of the armature shaft 35 in the axial direction is rotatably supported by a second bearing member 42 attached to the speed reduction mechanism case 41 via a sun gear 43a (see FIG. 5) of the first speed reduction mechanism 43. Yes. Thereby, the other side in the axial direction of the armature shaft 35 can also rotate smoothly without rattling inside the motor case 31.

  Here, the motor case 31, the speed 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 is arranged inside the motor case 31 and radially outside, and is further arranged between a pair of permanent magnets 32 provided so as to face the motor case 31. As a result, the motor case 31 is prevented from increasing in size (increasing in diameter) in the radial direction.

  A first reduction mechanism (deceleration mechanism) 43 and a second reduction mechanism (deceleration mechanism) 44 made of a planetary gear speed reducer are provided inside the reduction mechanism case 41 and near the second bearing member 42 along the longitudinal direction. Contained. Here, in the present embodiment, the first reduction mechanism 43 and the second reduction mechanism 44 that are set to a predetermined reduction ratio are stacked in two stages, thereby suppressing an increase in the size of the entire reduction mechanism in the radial direction. A large reduction ratio is obtained. Thereby, the enlargement in the radial direction of the motor unit 30 and the speed reduction mechanism unit 40 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 overall shape of the linear actuator 10 is a straight shape with no steps.

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

  Further, as shown in FIGS. 4B and 5, the second reduction mechanism 44 includes a sun gear 44 a integrally provided on the carrier 43 c of the first reduction mechanism 43, and meshes with the sun gear 44 a to surround the sun gear 44 a. There are provided three planetary gears 44b that roll, a carrier 44c that supports each planetary gear 44b, and a ring gear 44d that is formed on the inner wall of the speed reduction mechanism case 41 and meshes with each planetary gear 44b. As a result, the rotation of the carrier 43c of the first reduction mechanism 43 is decelerated and the torque is increased, and output from the carrier 44c toward the feed screw mechanism 50.

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

  As shown in FIG. 2, a third bearing member 45 and a fourth bearing member 46 are coaxially provided inside the speed reduction mechanism case 41 and near the feed screw mechanism portion 50 along the longitudinal direction. Yes.

  The third bearing member 45 rotatably supports the carrier 44c of the second reduction mechanism 44. As described above, the sun gear 43a of the first speed reduction mechanism 43 is rotatably supported by the second bearing member 42, and the carrier 44c of the second speed reduction mechanism 44 is rotatably supported by the third bearing member 45. In the inside of the speed reduction mechanism case 41, meshing of the gears forming the first speed reduction mechanism 43 and the second speed reduction mechanism 44 (two-stage speed reduction mechanism) is made smooth. Therefore, the operating noise of the two-stage reduction mechanism can be reduced and the life can be extended, 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 rotatably supports one axial direction side of the shaft 52 that forms the feed screw mechanism portion 50. Specifically, the fourth bearing member 46 is mounted on a small-diameter mounting portion 52 a on one side in the axial direction of the shaft 52. Thereby, when the linear actuator 10 is actuated, the rotational vibration on one side in the axial direction of the shaft 52 is effectively suppressed. Therefore, the linear actuator 10 can be operated smoothly, and the operation sound 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 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 (second case) 51 made of a hollow pipe. The feed screw mechanism case 51 is provided coaxially with the motor case 31 and the speed reduction mechanism case 41, and has a length longer than that of 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 / contraction of the piston tube 54.

  As shown in FIG. 2, a fitting portion 51 a that is fitted to the small-diameter main body portion 41 a of the speed reduction mechanism case 41 is provided on one side in the axial direction of the feed screw mechanism case 51. Here, the thickness t1 of the fitting portion 51a is set to be slightly smaller than the step size t2 (see FIG. 6) formed by the large diameter main body 41b and the small diameter main body 41a of the speed reduction mechanism case 41. (T1 <t2). Thereby, when the feed screw mechanism case 51 and the speed 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 that is rotated by a carrier 44 c of the second reduction mechanism 44 is rotatably accommodated inside 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 side in the drawing, and the linear actuator 10 is reduced. On the other hand, when the shaft 52 is rotated in the reverse direction, the screw nut 53 moves to the left in the drawing, and the linear actuator 10 is extended.

  Here, a concave groove (not shown) extending in the axial direction is formed in the outer peripheral portion of the screw nut 53. On the other hand, a convex portion (not shown) extending in the axial direction is formed on the inner peripheral portion of the feed screw mechanism case 51. Then, the concave groove of the screw nut 53 and the convex portion of the feed screw mechanism case 51 are slidably engaged with each other so that the screw nut 53 does not rotate by the rotation of the shaft 52, and the screw nut 53 is It moves only in the axial direction.

  An axial direction side of a piston tube (piston member) 54 made 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 enter and leave the feed screw mechanism case 51. Here, the shaft 52, the screw nut 53, and the piston tube 54 constitute a feed screw mechanism.

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

  On the other side in the axial direction of the shaft 52, an annular sliding contact member 57 that is in sliding contact with the inner peripheral side of the piston tube 54 is provided. The slidable contact member 57 rotates together with the shaft 52 inside the piston tube 54. Here, a sliding ring (not shown) that smoothly slides on the piston tube 54 is provided on the outer peripheral portion of the sliding contact member 57. In addition, as this sliding ring, the thing made from a polytetrafluoroethylene resin (PTFE) is used, for example. Further, the sliding contact member 57 also has a function of suppressing the rotational shake of the shaft 52 on the other side in the axial direction so that the shaft center of the shaft 52 is not shifted from the shaft center of the piston tube 54.

  A plug 58 that closes the other axial direction of the piston tube 54 is inserted on the other axial side of the piston tube 54, and the plug 58 is fixed so as not to rotate relative to the piston tube 54. The plug 58 includes a fixing portion 12, and a fixing pin provided on a frame or a bottom plate of the care bed is attached to the fixing portion 12.

  As shown in FIG. 5 and FIG. 6, the connecting member 60 is formed into a cylindrical shape by cutting a pipe made of a steel plate into a predetermined length, and the length dimension thereof is the first reduction mechanism 43 and the second reduction mechanism. The length is set to be slightly shorter than the length 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 two first parts are arranged on one side in the axial direction of the connecting member 60 so as to face each other in the radial direction of the connecting member 60. An engagement claw (engagement claw) 61 is provided.

  Further, two second engaging claws (engaging claws) 62 are provided on the other side in the axial direction of the connecting member 60 so as to face each other in the radial direction of the connecting member 60. These first and second engaging claws 61 and 62 are formed by cutting and raising a part of the connecting member 60 by pressing in the thickness direction of the connecting member 60.

  Here, the first and second engaging claws 61 and 62 on one side (upper side in the figure) with respect to the axis of the connecting member 60 and the other side (lower side in the figure with respect to the axis of the connecting member 60). The first and second engaging claws 61 and 62 in the above form a pair of engaging claws according to the present invention. That is, in this embodiment, two sets of the pair of engaging claws according to the present invention are provided.

  Each first engagement claw 61 protrudes toward the feed screw mechanism case 51 side along the axial direction of the connecting member 60. On the other hand, each of the second engaging claws 62 protrudes toward the speed reduction mechanism case 41 along the axial direction of the connecting member 60. That is, the distal end sides of the first and second engaging claws 61 and 62 are opposed to each other along the axial direction of the connecting member 60. Further, the distal end sides of the first and second engaging claws 61 and 62 are bent in advance radially inward of the connecting member 60 when the first and second engaging claws 61 and 62 are formed.

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

  Next, the assembly procedure of the linear actuator 10 formed as described above, in particular, the connection procedure between the drive mechanism unit 20 and the feed screw mechanism unit 50 using the connection member 60 will be described in detail with reference to the drawings.

  7 (a), (b), and (c) are partially enlarged sectional views for explaining the procedure for assembling the connecting member to the speed reduction mechanism case, and FIGS. 8 (a), (b), and (c) are connecting members. FIG. 4 is a partially enlarged cross-sectional view for explaining an assembling procedure of a feed screw mechanism with respect to a speed reduction mechanism case in which is assembled.

  7A, first, each first engagement claw 61 side of the connecting member 60 is made to face the large-diameter main body 41b of the speed reduction mechanism case 41. Next, as shown in FIG. 7 (b), the coupling member 60 is fitted to the large-diameter main body portion 41b in a state where the axis of the coupling member 60 and the axis of the speed reduction mechanism case 41 are aligned. To go. As a result, the first engaging claws 61 are elastically deformed as indicated by the dashed arrow M2, and the connecting member 60 is fitted into the large-diameter main body 41b under this state.

  Thereafter, as shown in FIG. 7C, the one side in the axial direction of the connecting member 60 comes into contact with the first stopper wall 41 d of the speed reduction mechanism case 41 by continuing the fitting of both. Accordingly, each first engaging claw 61 that has been elastically deformed by the large-diameter main body portion 41b is returned to the original state and engaged with the first annular groove 41c as indicated by a broken line arrow M3. Thereby, the assembly | attachment to the deceleration mechanism case 41 (drive mechanism part 20) of the connection member 60 is completed.

  Here, each of the first engaging claws 61 is elastically deformed by the speed reduction mechanism case 41 to allow the speed reduction mechanism case 41 and the feed screw mechanism case 51 to approach each other. Each first engaging claw 61 is engaged with the first annular groove 41c to restrict the speed reduction mechanism case 41 and the feed screw mechanism case 51 from being separated from each other.

  Thereby, the connection member 60 can be assembled to the speed reduction mechanism case 41 by one touch only by sliding the connection member 60 from one direction with respect to the speed reduction mechanism case 41. Moreover, since the front end side of each 1st engagement nail | claw 61 is engaged with the 1st annular groove 41c so that it may stretch with respect to the removal direction with respect to the deceleration mechanism case 41 of the connection member 60, it ensures sufficient removal | strength intensity | strength. Can do.

  Next, as shown by a 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, the annular clearance CS between the small-diameter main body portion 41a of the speed reduction mechanism case 41 and the connecting member 60 is maintained while the shaft center of the feed screw mechanism portion 50 is aligned with the axis of the speed reduction mechanism case 41. The fitting part 51a is inserted. As a result, as indicated by a 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 this state. .

  Thereafter, as illustrated in FIG. 8C, the fitting side 51 a is brought into contact with the second stopper wall 41 e of the speed reduction mechanism case 41 by continuously advancing the fitting of the both, thereby causing one side in the axial direction of the fitting portion 51 a to abut. Along with this, each second engaging claw 62 that has been elastically deformed by the fitting portion 51a returns to the original and is engaged with the second annular groove 51b as indicated by the broken line arrow M6. Thereby, the connection between the drive mechanism unit 20 and the feed screw mechanism unit 50 is completed.

  Here, each of the second engaging claws 62 is elastically deformed by the feed screw mechanism case 51 to allow the speed reduction mechanism case 41 and the feed screw mechanism case 51 to approach each other. Further, each second engagement claw 62 is engaged with the second annular groove 51b to restrict the speed reduction mechanism case 41 and the feed screw mechanism case 51 from being separated from each other.

  Thus, the feed screw mechanism case 51 can be assembled to the speed reduction mechanism case 41 with a single touch only by sliding the feed screw mechanism case 51 from one direction with respect to the speed reduction mechanism case 41. Further, since the distal end side of each second engagement claw 62 is engaged with the second annular groove 51b so as to be stretched with respect to the removal direction of the feed screw mechanism case 51 with respect to the speed reduction mechanism case 41, sufficient removal 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 when an external force F that bends the linear actuator (at the time of maximum reduction) is applied, and FIG. 10 shows a state when an external force F that is bent at the time of the linear actuator (at the time of maximum extension) is applied. Enlarged sectional views are 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 nursing bed via the fixing portions 11 and 12 on both sides in the longitudinal direction of the linear actuator 10. Each pin is rotatably mounted. Therefore, when the linear actuator 10 is extended from the most contracted state, an external force F is applied to each of the fixing portions 11 and 12 in the direction in which the linear actuator 10 is bent with the bending center O as the center. Here, the bending center O of the linear actuator 10 is provided at a connection portion between the drive mechanism portion 20 and the feed screw mechanism portion 50, that is, a portion where the connection member 60 is present.

  In the present embodiment, the first engaging claws 61 and the second engaging claws 62 of the connecting 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. Has been. As a result, when the drive mechanism 20 and the feed screw mechanism 50 are bent at a relative angle α °, for example, with the bending force O as the center by the external force F, the first engagement claws 61 and the second engagements. A relatively large load is applied to each of the claws 62. However, in the present embodiment, as described above, a sufficient pulling strength is secured by the connecting member 60, so that the connection state between the drive mechanism unit 20 and the feed screw mechanism unit 50 is not released.

  Here, even if the connection state of the drive mechanism unit 20 and the feed screw mechanism unit 50 is loosened, the linear actuator 10 is loaded in the direction in which the linear actuator 10 is reduced. Therefore, the connection state between the drive mechanism unit 20 and the feed screw mechanism unit 50 is not released.

  Further, as shown by a 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 extending operation of the linear actuator 10, the piston F is caused by the external force F shown in FIG. One side in the axial direction of the tube 54 is inclined as shown by a broken line arrow M8. Along with this, one side in the axial direction of the shaft 52 is inclined as shown by a broken line arrow M9. Here, the 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, the external force F is applied to the shaft 52 in the direction in which the shaft 52 is inclined. However, the small-diameter mounting portion 52 a on one axial direction 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.

  Therefore, since the inclination of the shaft 52 on one side in the axial direction is reliably suppressed, the second speed reduction mechanism 44 is not swung and the smooth operation of the drive mechanism unit 20 is ensured. Further, the smooth entry / exit of the piston tube 54 from the feed screw mechanism case 51 is ensured. Thus, the linear actuator 10 which concerns on this Embodiment is excellent in the silence of a drive part, and becomes a specification suitable for using for a nursing bed etc.

  As described above in detail, according to the linear actuator 10 according to the present embodiment, the first and second engaging claws 61 and 62 provided on the tubular connecting member 60 are connected to the first and second annular grooves 41c. , 51b to prevent the speed reduction mechanism case 41 and the feed screw mechanism case 51 from coming out of each other, thereby ensuring sufficient removal strength. Since the first and second engaging claws 61 and 62 are formed by cutting and raising a part of the connecting member 60 while the connecting member 60 is formed of a pipe member made of a steel plate, the linear actuator It can suppress that the thickness of 10 becomes thick. Therefore, the overall shape of the linear actuator 10 can be reduced to a straight shape without a step, and the thickness thereof can be reduced, thereby improving versatility.

  Next, a linear actuator according to Embodiment 2 of the present invention will be described in detail with reference to the drawings. Note that portions having the same functions as those of the first embodiment described above are denoted by the same reference numerals, and 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 to the first embodiment, the first and second engaging claws 61 and 62 provided on the connecting member 60 are the bending center O of the linear actuator 10. The only difference is that they are arranged in the axial direction. That is, the first and second engaging claws 61 and 62 of the connecting member 60 in the second embodiment are replaced with the first and second engaging claws 61 and 62 (see FIG. 9) of the connecting member 60 in the first embodiment. In contrast, the connecting member 60 is disposed at a position shifted by 90 ° in the circumferential direction.

  In the second embodiment formed as described above, the same operational effects as those of the first embodiment described above can be obtained. In addition to this, in the second embodiment, the first and second engaging claws 61 and 62 are arranged in the axial direction of the bending center O of the linear actuator 10, and therefore, compared to the first embodiment. The load applied to the first and second engaging claws 61 and 62 can be reduced. Therefore, it is possible to reliably prevent rattling from occurring at the connecting portion between the drive mechanism unit 20 and the feed screw mechanism unit 50, thereby further improving quietness.

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

  FIG. 12 is a partial enlarged cross-sectional view showing the linear actuator of the third embodiment.

  As shown in FIG. 12, the linear actuator 70 according to the third embodiment has a connecting member integrally provided in the motor case as compared with the linear actuator 10 according to the first embodiment (see FIG. 2). Accordingly, 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 (first case) 71. A cylindrical connecting member 72 is integrally provided at a portion near the speed reduction mechanism 40 along the longitudinal direction of the motor case 71. Two engaging claws 73 are provided on the other side in the longitudinal direction of the connecting member 72 (left side in the drawing) so as to face each other in the radial direction of the connecting member 72. These engaging claws 73 are formed by cutting and raising a part of the connecting member 72 by pressing in the plate thickness direction of the connecting member 72.

  Each engagement claw 73 protrudes toward the motor part 30 side along the axial direction of the connecting member 72. That is, the protruding direction of each engaging claw 73 is the same as the protruding direction of the second engaging claw 62 in the first embodiment. Further, the front end side of each engagement claw 73 is bent in advance in the radial direction of the connecting member 72 when each engagement claw 73 is formed. Then, under the assembled state of the linear actuator 70, each engagement claw 73 is 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, each engaging claw 73 is 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, each engaging claw 73 is engaged 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. As a result, simply sliding the feed screw mechanism case 51 from one direction with respect to the motor case 71 completes the connection between the drive mechanism unit 20 and the feed screw mechanism unit 50, and the assembly of the linear actuator 70 is completed.

  Also in the third embodiment formed as described above, the same operational effects as those of the first embodiment described above can be obtained. In addition, in the third embodiment, since the connecting member 72 is provided integrally with 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 connecting portion between the drive mechanism unit 20 and the feed screw mechanism unit 50 can be halved, and quietness can be further improved. Further, since a separate connecting member is not required, it is possible to rationalize parts management and simplify the assembly process. Furthermore, the appearance of the linear actuator 70 can be refreshed, and the appearance can be improved.

  Here, similarly to the configuration of the second embodiment shown in FIG. 11, the engaging claws 73 of the third embodiment can be arranged in the axial direction of the bending center O. In this case, the load applied to each engaging claw 73 can be reduced. Therefore, it is possible to more reliably suppress the occurrence of rattling in the connecting portion between the drive mechanism unit 20 and the feed screw mechanism unit 50, and to further improve the quietness.

  Further, the connecting member can be provided integrally with 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 protruding direction and shape as the first engaging claw 61 in the first embodiment. Further, for example, the small diameter main body portion 41a of the speed reduction mechanism case 41 is provided with a groove portion that engages with the engaging claw.

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

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

  As illustrated in FIG. 13, the linear actuator 80 according to the fourth embodiment supports the carrier 44 c of the second reduction mechanism 44 as compared with the linear actuator 10 according to the first embodiment (see FIG. 10). The only difference is that the bearing member 45 is omitted and the fifth bearing member 81 is additionally mounted on the small diameter mounting portion 52a of the shaft 52. Here, the fifth bearing member 81 is the same as the fourth bearing member 46, and is arranged side by side so as to contact the fourth bearing member 46. Accordingly, the axial length of the small diameter mounting portion 52a is twice as long as that of the first embodiment.

  In the fourth embodiment formed as described above, the same operational effects as those of the first embodiment can be obtained. In addition, in the fourth embodiment, the fourth bearing member 46 and the fifth bearing member 81 having the same specifications suppress the rotational vibration on one side of the shaft 52 in the axial direction. Vibration transmission can be more reliably suppressed. However, as indicated by an imaginary line (two-dot chain line) in FIG. 13, a third bearing member 45 that supports the carrier 44c may be provided. In this case, the drive mechanism unit 20 can be operated more smoothly, and a linear actuator excellent in quietness can be realized.

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

  FIG. 14 is a partially enlarged sectional view showing the linear actuator of the fifth embodiment.

  As shown in FIG. 14, the linear actuator 90 according to the fifth embodiment is a third one that supports the carrier 44 c of the second reduction mechanism 44 compared to the linear actuator 10 according to the first embodiment (see FIG. 10). The bearing member 45 is omitted, and the sixth bearing member 91 is additionally mounted on the small diameter mounting portion 52a of the shaft 52. A cylindrical collar member 92 is interposed between the sixth bearing member 91 and the fourth bearing member 46. Here, the sixth bearing member 91 is the same as the fourth bearing member 46 and is arranged side by side with a separation distance L with respect to the fourth bearing member 46. Accordingly, the axial length of the small-diameter mounting portion 52a is approximately four times that of the first embodiment.

  In the fifth embodiment formed as described above, the same operational effects as those of the first embodiment described above can be obtained. Further, as compared with the fourth embodiment, it is possible to more reliably suppress the rotational vibration of the shaft 52 on one side in the axial direction, and it is possible to more reliably suppress the vibration transmission of the shaft 52 to the second reduction mechanism 44. However, as indicated by an imaginary line (two-dot chain line) in FIG. 14, a third bearing member 45 that supports the carrier 44c may be provided. In this case, the drive mechanism unit 20 can be operated more smoothly, and a linear actuator excellent in quietness can be realized.

  It goes without saying that the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the invention. For example, in each of the above-described embodiments, the linear actuators 10, 70, 80, 90 are used as drive sources for raising or lowering the bottom plate of the care bed. However, the present invention is not limited to this. It can also be used as a drive source for adjusting the height of a walker, a drive source for raising and lowering a stand-up auxiliary chair or a moving lift, and the like.

  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, respectively. Although shown, the present invention is not limited to this, and one or three or more engaging claws can be provided in the circumferential direction of the connecting member. When three or more engaging claws are provided, the interval between them may be equal in the circumferential direction of the connecting member or may be unequal. In short, the engagement claw can be arbitrarily set in accordance with the pull-out strength required for the linear actuator (specifications of the linear actuator).

  Further, in the first and second embodiments, the connecting member 60 is assembled to the speed reduction mechanism case 41 first. However, the present invention is not limited to this, and the connecting member 60 is connected to the feed screw mechanism case 51. It may be assembled first.

DESCRIPTION OF SYMBOLS 10 Linear actuator 11, 12 Fixed part 20 Drive mechanism part 21 Connector connection part 30 Motor part 31 Motor case (1st case)
32 Permanent magnet (motor)
33 Coil (motor)
34 Armature (motor)
35 Armature shaft (motor, rotating shaft)
36 Brush (motor)
37 Commutator (motor)
38 Cover member 39 First bearing member 40 Deceleration mechanism 41 Deceleration mechanism case (first case)
41a Small-diameter body part 41b Large-diameter body part 41c First annular groove (groove part)
41d 1st stopper wall 41e 2nd stopper wall 42 2nd bearing member 43 1st deceleration 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 44d Ring gear 45 Third bearing member 46 Fourth bearing member 50 Lead screw mechanism 51 Lead screw mechanism case (second case)
51a Fitting part 51b 2nd annular groove (groove part)
52 Shaft (shaft member)
52a Small-diameter mounting part 52b Involute serration 52c Male thread part 53 Screw nut (female thread member)
54 Piston tube (piston member)
55 Tube guide 56 Fixed cap 57 Sliding member 58 Plug 60 Connecting member 61 First engaging claw (engaging claw)
62 Second engaging claw (engaging claw)
70 Linear actuator 71 Motor case (first case)
72 connecting member 73 engaging claw 80 linear actuator 81 fifth bearing member 90 linear actuator 91 sixth bearing member 92 collar member BT fastening bolt CS annular gap O bending center

Claims (4)

A motor having a rotating shaft;
A speed reduction mechanism for decelerating the rotation of the rotary shaft;
A first case that houses the motor and the speed reduction mechanism;
A shaft member rotated by the speed reduction mechanism and having a male screw part;
A second case provided coaxially with the first case and containing the shaft member;
A female screw member screwed to the male screw portion and moved in the axial direction of the shaft member as the shaft member rotates;
A piston member provided on the female screw member and entering and exiting from the second case;
A cylindrical connecting member for connecting the first case and the second case;
With
The connecting member has a pair of engaging claws protruding radially inward,
The pair of engaging claws are elastically deformed by the first case and the second case, thereby allowing the first case and the second case to approach each other. The first case and the second case are restricted from being separated from each other by engaging with a groove provided in each.
Linear actuator. The linear actuator according to claim 1,
The linear actuator includes a bending center that is a center when bent by an external force load, and the engaging claw is disposed in an axial direction of the bending center.
Linear actuator. A motor having a rotating shaft;
A speed reduction mechanism for decelerating the rotation of the rotary shaft;
A first case that houses the motor and the speed reduction mechanism;
A shaft member rotated by the speed reduction mechanism and having a male screw part;
A second case provided coaxially with the first case and containing the shaft member;
A female screw member screwed to the male screw portion and moved in the axial direction of the shaft member as the shaft member rotates;
A piston member provided on the female screw member and entering and exiting from the second case;
A cylindrical connecting member for connecting the first case and the second case;
With
The connecting member has an engaging claw protruding radially inward, and is provided in any one of the first case and the second case,
The engaging claw is elastically deformed by either one of the first case and the second case, thereby allowing the first case and the second case to approach each other, and the first case and The first case and the second case are prevented from being separated from each other by engaging with a groove provided on the other of the second cases.
Linear actuator. The linear actuator according to claim 3, wherein
The linear actuator includes a bending center that is a center when bent by an external force load, and the engaging claw is disposed in an axial direction of the bending center.
Linear actuator.

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