JP2000291768A - Actuator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the reverse rotation by a load, while minifying a size and weight. SOLUTION: In an actuator 10, the shaft supported to the shaft insertion part 14 of a housing 11 rotatably is normally/reversely rotated and driven by the motor 60 with a worm gear reduction device through a drive side bevel gear and driven side bevel gear 47. A female member 18 connected a moving cylinder 22 moving in the axial direction is screwed with the male screw part 16 of the outer periphery of the shaft 15 advancably/retreatably and the front side end of the moving cylinder 22 is connected to the load. The brake member 80 with a big friction coefficient is slide-contacted to the axial direction end surface of the rotary shaft 65 of the motor 60. By obstructing the rotation against the external force by which the brake torque by the brake member 80 rotates the rotary shaft forcedly, the advance/retreat of the female screw member can be prevented when a big force is applied from a load side to the female screw member 18. Thereby, as the brake member is not interposed to the shaft, the size and weight of the actuator can be set to be small.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an actuator, and more particularly to an electric feed screw type actuator, and more particularly to an actuator effectively used for erecting or falling down a bed of a medical bed.

[0002]

2. Description of the Related Art In a medical bed, in order to reduce the burden of sleeping and eating on a patient, the bed of the bed is raised or lowered by an electric feed screw type actuator.

[0003] As a conventional actuator of this type, a shaft inserted in a shaft insertion portion of a housing and rotatably supported is driven by a motor via a reduction gear in forward and reverse rotations. A female screw member connected to a moving cylinder that moves in the axial direction is threadably engaged with a male screw portion formed on the outer periphery of the moving cylinder, and the front end of the moving cylinder is configured to be connected to a load. There is something.

When such an actuator is used in a medical bed, the movable cylinder extends to erect the bed and support the patient's weight, so that the shaft has its own weight or the patient's weight. As a result, an external force that attempts to reversely rotate the shaft (hereinafter, sometimes referred to as a load-side reverse rotation acting force) always acts. Therefore, when such an actuator is used in a medical bed, a brake device and a one-way clutch for preventing reverse rotation are interposed on the shaft.

[0005] Japanese Patent Application Laid-Open No. 6-109094 discloses an example of this type of conventional actuator.

[0006]

However, in an actuator having a brake device and a one-way clutch interposed on a shaft for preventing reverse rotation, the size and weight of the actuator are increased by the amount of the brake device and the one-way clutch. Would. Also, when viewed from the load side, the brake device and the one-way clutch are in a state before deceleration, so that the brake device and the one-way clutch are directly subjected to the rotating action force due to the load, and as a result, the brake device needs to be designed large, and the size and weight of the actuator are Becomes even larger.

An object of the present invention is to provide an actuator capable of preventing reverse rotation due to a load while reducing the size and weight.

[0008]

In the actuator according to the present invention, a male screw portion is formed on the outer periphery of a shaft driven forward and reverse by a motor via a reduction gear, and a female screw member is formed on the male screw portion in the axial direction. In the actuator screwed forward and backward, a brake member having a large friction coefficient is slidably brought into contact with an axial end surface of a rotating shaft of the motor.

In the above-mentioned means, when a large force for moving the female screw member is applied to the female screw member from the load side, the shaft is rotated in reverse by the screwing relationship between the female screw member and the male screw part. The external force acting from the load side acts as an external force for forcibly rotating the rotating shaft of the motor via the reduction gear. However, since the braking torque of the brake member on the axial end surface of the rotating shaft prevents the rotation against the external force forcing the rotating shaft to rotate, the rotating shaft is rotated by the reverse rotation acting force from the load side. Can be prevented. Therefore, even when a large force for moving the female screw member forward and backward is applied to the female screw member from the load side, it is possible to prevent a phenomenon that the female screw member is advanced and retracted.

According to the above-described means, since the brake member is not provided on the shaft, the size and weight of the actuator can be reduced. Moreover, when viewed from the motor on the driving side, the brake torque acts before deceleration, and acts as a large braking force after deceleration. Therefore, even with a small brake member, the reverse rotation action from the load side occurs. Force can be braked efficiently. That is, the brake member can efficiently brake the reverse rotation acting force from the load side while suppressing the reduction of the driving force of the motor.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings.

As shown in FIG. 1, the actuator according to the present embodiment is configured to raise and lower a bed of a medical bed (hereinafter, referred to as a bed). That is, the housing 11 on the fixed end side of the actuator 10 is rotatably supported on the frame 2 of the bed 1 by the pivot 3, and the distal end of a moving cylinder 22 described later on the free end side of the actuator 10 is connected to the bed 4. It is rotatably connected to a link 5 for raising and lowering by a connecting pivot 30 described later. With the actuator 10 shortened, the bed 4 of the bed 1 is horizontally laid down as shown in FIG.
When is extended, the bed 4 is erected as shown in FIG. 1 (b).

As shown in FIG. 2, the actuator 10 includes a housing 11,
Is constructed by combining a pair of shells 12 on the left and right. Both shells 12 and 12 are formed in a generally rectangular dish shape that is symmetrical to each other using resin.
The motor mounting portion 13 and the shaft insertion portion 14 are formed between the mating surfaces that have been centered. The two shells 12, 12 are fastened by a screw member in a state where they are assembled in the middle, and the outer periphery of a fitting portion formed outside one end (hereinafter, referred to as a front end) opening of the shaft insertion portion 14. Is fitted with a metal band 12a. The left and right shells 12, 12 are formed by the band 12a.
Of the shaft insertion portion 14 in the left-right direction is prevented. At opposite positions of the left and right shells 12, 12, a pair of window holes 12b, 12b for exposing a support hole 87 described later are opened.

As shown in FIG.
A male screw portion 16 for feeding is formed on the front side of the shaft 15 inserted into the shaft insertion portion 14 of the first shaft, and a nut 18 as a female screw member with a female screw portion 17 screwed into the male screw portion 16 is advanced and retracted. It is freely attached. A support cylinder 19 is arranged concentrically with the shaft 15 outside the nut 18 in the shaft insertion portion 14 of the housing 11, is sandwiched between the left and right shells 12, 12, and is prevented from falling off by the fixing portion 20. The nut 18
9 is slidably fitted in the cylinder center direction.

As shown in FIGS. 3 and 4, the nut 18 is provided with a moving cylinder 22 and the shaft 15 and the supporting cylinder 1.
The connecting member 24 is mounted on the front end of the movable cylinder 22 so as to adjust the connecting position of the bed 1 to the bed 4. That is, in the inner periphery of the front end of the movable barrel 22, at a position slightly closer to the rear from the front end than the length of the connecting tool 24,
A female screw portion 25 for position adjustment is engraved, and a pair of long holes 26 extending in the cylindrical direction are provided at a central position closer to the front end from the female screw portion 25 for position adjustment and extend in the cylindrical direction opposite to each other. Each has been established as follows. That is, both slots 2
Reference numerals 6 and 26 are not provided in the position adjusting internal thread portion 25. Therefore, the position adjusting female screw portion 25 maintains a precisely processed state without lowering the accuracy of burrs, screw threads and valleys.

On the other hand, the connecting member 24 is formed in a cylindrical shape having an outer diameter substantially equal to that of the movable barrel 22, and a position adjusting male screw portion 27 is engraved on the outer periphery of one end. A connection hole 29 for inserting a connection pin is formed in the center of the connection tool 24 so as to penetrate in a direction perpendicular to the axis. That is,
A connection hole 29 is formed in the connection tool 24 at a position apart from the position adjusting male screw portion 27. Therefore, the position adjusting male screw portion 27 maintains a precisely machined state without lowering the accuracy of burrs, threads and valleys. Connector 24
A tool engaging portion 28 for engaging a tool such as a wrench is submerged on each of the front and rear end surfaces.

The connecting member 24 is inserted into the movable barrel 22 with the position adjusting male screw 27 facing rearward, and is screwed to the position adjusting female screw 25. In this state, the connecting tool 24 is mounted on the front end of the movable barrel 22 so that the position in the axial direction can be adjusted, and the connecting hole 29 is formed by adjusting the rotational position thereof. ,
26.

The outer diameter of the connecting hole 29 and both long holes 26, 26
Are set to be equal to the width in the short direction, and are set to be substantially equal to the outer diameter of the connecting pivot 30. As shown in FIG. 4, the connecting pin 30 has the elongated hole 26 and the connecting hole 2.
9 and is also set so as to be able to be inserted into the connection hole 32 formed in the bracket 31 on the bed side of the bed, and the flange portion 30a and the outer side of the bracket 31 in the inserted state. It is configured to be retained by the split pin 33.

Since the connecting member 24 is connected to the bed side of the bed, the nut 18 and the moving cylinder 22 are prevented from rotating with respect to the supporting cylinder 19. In this state, the rotation is stopped against the movement.
To move linearly.

As shown in FIGS. 3 and 4, a cylindrically shaped nut stopper 35 is coaxially arranged and fixed to the front end of the shaft 15, and the nut stopper 35 is It is slidably supported on the inner peripheral surface. Internal thread 2 for position adjustment of moving cylinder 22
A position regulating member 36 also serving as a damper is fixed on the inner periphery of the front end near the rear end from 5 so that the position can be adjusted. That is, the position regulating member 36 is formed of a rubber or resin elastic material, and is formed in a columnar shape having an outer diameter equal to the inner diameter of the movable cylinder 22. An insertion hole 37 for inserting a rivet is formed in an intermediate portion of the position regulating member 36 in a direction orthogonal to the axis. A concave portion 38 is provided on the rear end surface of the position regulating member 36 to escape a convex portion of the shaft 15 protruding from the nut stopper 35. On the other hand, an insertion hole 39 for inserting a rivet is provided at a position at the front end of the movable cylinder 22 which is appropriately separated from the female screw portion 25 for position adjustment so as to penetrate in a direction orthogonal to the cylinder core.

Then, with the connecting tool 24 removed and the insertion holes 37 and 39 aligned with a mounting jig (not shown), the position regulating member 36 is inserted into the movable cylinder 22. The insertion holes 37 and 3 are inserted through the front end opening.
The rivet 40 is inserted into the movable barrel 9 and caulked to fix the movable barrel 22 at a desired adjustment position shown in FIGS. 3 and 4.

As shown in FIGS. 3 and 4, a cylindrical cap 41 having outward flanges at front and rear ends is fitted into the front end opening of the support cylinder 19,
The rear end of the cap 41 is fixed to the support cylinder 19 by engaging a flange on the rear end side of the cap 41 with an annular groove provided in the inner periphery of the support cylinder 19. The cap 41 is configured to seal the inside of the support cylinder 19 by sliding the inner circumference against the outer circumference of the movable cylinder 22.

As shown in FIGS. 3 and 4, the rear end portion (hereinafter, referred to as a driven portion) 42 of the shaft 15 is not formed with the male screw portion 16 for feeding. A step 43 is provided at a position adjacent to the feed male thread 16 of the driven portion 42 at a constant width and a constant depth, and a ring 44 is fitted around the step 43. The ring 44 is fixed to a gear case 63 of a motor (hereinafter, referred to as a motor) 60 with a worm gear reduction device, which will be described later, in a shaft insertion chamber 64 having a larger diameter than the support cylinder 19. The rear end face of the step of the male screw portion 16 of the shaft 15 is abutted.

Inside the shaft insertion chamber 64, a chamfered portion 45 is formed on the outer periphery of the intermediate portion of the driven portion 42, and a driven bevel gear 47 driven by a driving bevel gear 46 is integrally formed on the chamfered portion 45. It is fitted so as to rotate. The inner race of the radial rolling bearing 48 is fitted on the outer periphery of the driven bevel gear 47, and the outer race of the radial rolling bearing 48 is fixed on the inner periphery of the shaft insertion chamber 64. That is, the driven portion 42, which is the rear end of the shaft 15, is connected to the motor 6 via the radial rolling bearing 48.
The gear case 63 is rotatably supported by the gear case 63.

A chamfered portion 49 is formed on the rear outer periphery of the driven side bevel gear 47 of the driven portion 42, and a thrust plate 50 is fitted to the chamfered portion 49 so as to rotate integrally. The rotating race of the thrust rolling bearing 51 is fixed to the thrust plate 50, and the fixed race of the thrust rolling bearing 51 is fixed to the rear end of the shaft insertion chamber 64. Therefore, the driven portion 42, which is the rear end of the shaft 15, is rotatably supported by the gear case 63 of the motor 60 via the thrust rolling bearing 51 while the axial movement thereof is restricted.

As shown in FIG. 3, an insertion hole 52 is formed in the rear wall of the shaft insertion chamber 64, and the driven portion 42 which is the rear end of the shaft 15 is inserted into the insertion hole 52. ing. A stopper 53 for preventing the shaft 15 from coming off in the forward direction is fitted around the outer periphery of the rear end protruding from the insertion hole 52 of the driven portion 42, and is fixed by a retaining ring 54. Behind the driven part 42 which is the rear end of the shaft 15 of the housing 11, a dry cell storage chamber 55 for storing dry cells as an emergency battery uses a space adjacent to the yoke 62 of the motor 60. It is formed. An electric wire 56 that constitutes a path for power for driving the motor 60 and a control signal for control is connected to the upper side of the support cylinder 19 of the housing.

As shown in FIG. 5, a driven bevel gear 46 is meshed with the driven bevel gear 47, and the driven bevel gear 46 is disposed in the gear case 63 so as to be orthogonal to the shaft insertion chamber 64. The output shaft 69 of the motor 60 is fitted so as to rotate integrally. That is, the driven bevel gear 47
, The torque of the motor 60 is converted into a right angle by the driving bevel gear 46 and transmitted. As shown in FIGS. 3 and 5, the motor 60 is housed in the motor mounting portion 13 of the housing 11 of the actuator 10 and is relatively fixed to the housing 11.

As shown in FIG. 3, a motor housing 61 of a motor 60 with a worm gear reduction device is composed of a yoke 62 and a gear case 63 connected in series with each other.
The motor case 13 is mounted with the gear case 63 facing forward. The gear case 63 is rigidly and integrally formed by aluminum die casting, and the shaft insertion chamber 64 is formed at a position where the rear end of the shaft 15 of the gear case 63 passes. As shown in FIG. 6A, the rotating shaft 65 of the motor 60 is rotatable by radial bearings 66, 66 arranged at both ends in the axial direction and a radial bearing 66A arranged at an intermediate portion. It is supported by A worm 67 is formed at the front end of the rotating shaft 65 housed in the gear case 63.
A worm wheel 68 is meshed with 7. As shown in FIG. 5, an output shaft 69 is inserted and fixed to the worm wheel 68, and the driving-side bevel gear 46 is fitted to the opposite end of the output shaft 69 so as to rotate integrally. Have been. As described above, the driving-side bevel gear 46 is meshed with the driven-side bevel gear 47 in the shaft insertion chamber 64.

In FIG. 6A, a first brake member 70 and a second brake member 80 are interposed between the gear case 63 and the yoke 62 at both axial end surfaces of the rotating shaft 65, respectively. The first brake member 70 and the second brake member 80 are each configured to support an axial thrust force acting on the rotating shaft 65 and to apply a braking force to the torque acting on the rotating shaft 65. ing. The first brake member 70 and the second brake member 80 are integrally formed using a resin having a large friction coefficient such as nylon or polyimide resin and having wear resistance and heat resistance.

As shown in FIG. 6B, the first brake member 70 has a small-diameter portion 71 and a large-diameter portion 72, and the large-diameter portion 72 has a circular end face on the rotating shaft 65 side. A ring-shaped contact surface portion 73 is provided to project concentrically. The outer diameter of the contact surface 73 is set substantially equal to the outer diameter of the rotating shaft 65, and the end surface of the contact surface 73 is uniformly slidably contacted with the outer peripheral portion of the end surface of the rotating shaft 65 over the entire circumference. An oval flat plate-shaped flange portion 74 is formed on the outer periphery of the large-diameter portion 72. The flange portion 74 extends axially into a detent hole 66 a formed in an oval hole shape on the opposite end face of the radial bearing 66. It is slidably fitted in a locked state.

The small-diameter portion 71 of the first brake member 70 is inserted into a hollow portion of a cushion member 75 formed of a short and thick cylinder using rubber or resin. It is stored in a storage hole 76 formed on an extension of the rotation shaft 65. The outer periphery of the cushion member 75 is formed in a drum shape with a central portion bulging radially outward. When the cushion member 75 is housed in the housing hole 76 of the gear case 63, its outer peripheral surface is inside the housing hole 76. It is in a state of being pressed against the peripheral surface. The cushion member 75 is set so as to repel the first brake member 70 in the direction of the rotation shaft 65 when stored in the storage hole 76, and the resilient force of the first brake member 70 makes the oval flat plate of the first brake member 70. The flange portion 74 has a detent hole 66a formed on the opposite end face of the radial bearing 66.
It is fitted into and stopped.

When the thrust force from the rotating shaft 65 acts on the cushion member 75 via the first brake member 70, the cushion member 75 is elastically deformed to absorb the thrust force from the rotating shaft 65. Is set to

As shown in FIG. 6C, the second brake member 80 has a small-diameter portion 81 and a large-diameter portion 82, and is provided on the end surface of the large-diameter portion 82 opposite to the rotation shaft 65. Has a circular ring-shaped contact surface 83 projecting concentrically. The outer diameter of the contact surface portion 83 is set substantially equal to the outer diameter of the rotating shaft 65 and larger than the outer diameter of the contact surface portion 73 of the first brake member 70. A thrust plate 85 is accommodated and fixed in a cylindrical accommodation portion 84 at the end of the yoke 62 on the side of the second brake member 80, and the end surface of the contact surface portion 83 is entirely attached to the opposite end surface of the thrust plate 85. It is slid uniformly over the circumference. Note that the thrust plate 85 may be omitted, and the contact surface portion 83 of the first brake member 70 may slide on the bottom surface of the storage portion 84 of the yoke 62.

The small diameter portion 81 of the second brake member 80 is fitted into a holding hole 86 formed in the end surface of the rotating shaft 65 on the second brake member 80 side so as to rotate integrally. Small diameter part 8
1 is inserted into the holding hole 86, the large-diameter portion 82
The end surface opposite to the contact surface portion 83 is in contact with the end surface of the rotating shaft 65. The contact surface 83 of the second brake member 80 is set to be constantly pressed against the thrust plate 85 by the force of the cushion member 75 disposed on the opposite side of the rotation shaft 65 repelling the rotation shaft 65.

As shown in FIG. 5, a gear case 63 which is rigidly and integrally formed by using aluminum die casting.
A pair of support holes 87, 87 are formed on both side surfaces at which the rear end of the shaft 15 is orthogonal to each other so as to be opposed to each other on the same axis, and the actuator 10 is fitted into the pair of support holes 87, 87. A pair of pivots 3 for rotatably supporting the one frame 2 are fitted respectively. The axis connecting both support holes 87, 87 is set so as to pass through the intersection of the driving bevel gear 46 and the driven bevel gear 47, and the actuator 10 is driven by the driving bevel gear 4
6 is reciprocated about the intersection of the driven bevel gear 47 and the driven bevel gear 47.

The operation will be described below.

The actuator 10 is previously assembled to the bed 1 as shown in FIG. That is, as shown by imaginary lines in FIG. 5, the pivots 3, 3 constituted by through bolts are inserted through the frame 2 of the bed 1 and the support holes 87, 87 on both sides of the actuator 10 are formed.
The actuator 1 is screwed into the
0 is pivotally supported on the frame 2 of the bed 1 by a pair of pivots 3,3. The connecting tool 24 of the movable cylinder 22 of the actuator 10 is connected to the bracket 31 on the bed 4 side by inserting the connecting pin 30.

When the motor 60 is rotated in the forward direction from the state shown in FIG. 1A after the actuator 10 is mounted on the bed 1, the driving force of the rotating shaft 65 is increased by the worm 67, the worm wheel 68, and the output. The power is transmitted to the shaft 15 via the shaft 69, the driving-side bevel gear 46, and the driven-side bevel gear 47. When the shaft 15 is rotated forward by the motor 60, the nut 18 is advanced along the support tube 19, and the moving tube 22 connected to the nut 18 is pushed out of the support tube 19. The bed 4 of the bed 1 connected to the connector 24 of the moving cylinder 22 is raised by the advance of the moving cylinder 22.

When the worm wheel 68 rotates in the direction of the arrow P as shown in FIG. 7A during the forward rotation of the motor 60, the forward rotation driving force of the motor 60 is applied to the rotating shaft 65. a second brake member 80 exerts a thrust force F ₁ to be pressed against the thrust plate 85 Te. Since the forward rotation driving force from the motor 60 exceeds a braking torque due to a frictional force between the second brake member 80 and the thrust plate 85, which will be described later, the motor 60 rotates the shaft 15 against the braking torque. Can be. At this time, the second brake member 80 is
To rotate together with the thrust plate 85,
Generates frictional heat. However, since the thrust plate 85 is in contact with the yoke 62 and in contact with the outside air, the friction heat is efficiently dissipated.

The movable cylinder 22 is moved by a required predetermined stroke.
Is extended, the driving electric circuit (not shown) of the motor 60
The operation of the motor 60 is automatically stopped by an automatic stop device or the like interposed in the apparatus.

When the operation of the motor 60 is stopped, the load on the bed 4 of the bed 1 (eg, the weight of the patient) acts as a force in the direction of retracting the nut 18 via the movable cylinder 22. For this reason, the shaft 15 is subjected to a load-side reverse rotation acting force for reverse rotation from the moving cylinder 22, that is, from the load side, by the action of the female screw portion 17 of the nut 18 and the male feed screw portion 16 of the shaft 15. . The load-side reverse rotation acting force applied to the shaft 15 is transmitted to the rotating shaft 65 via the driven-side bevel gear 47, the driving-side bevel gear 46, the output shaft 69, the worm wheel 68, and the worm 67.

As shown in FIG. 7 (b), this load-side reverse rotation acting force exerts an external force for rotating the worm wheel 68 in the direction of arrow M, so that the second brake member 80
The a state exert a thrust force F ₂ for pressing the thrust plate 85. At this time, since the second brake member 80 rotates integrally with the rotating shaft 65, the rotating shaft 65 is in a state where the reverse rotation is prevented by the brake torque due to the frictional force between the second brake member 80 and the thrust plate 85. . In addition, since the outer diameter of the contact surface 83 of the second brake member 80 with the thrust plate 85 is set to be large, the braking torque between the second brake member 80 and the thrust plate 85 increases, and the rotating shaft 65 Is in a state where the reverse rotation is reliably prevented. Therefore, the actuator 10 can always reliably support the load on the bed 4 of the bed 1.

Next, when the motor 60 is rotated in the reverse direction, the reverse rotation driving force of the rotating shaft 65 is applied to the worm 67, the worm wheel 68, the output shaft 69, the driving bevel gear 46 and the driven bevel gear 47. The power is transmitted to the shaft 15 via the shaft 15. As shown in FIG. 7C, the reverse rotation driving force of the motor 60 causes a state in which a thrust force F ₃ that causes the second brake member 80 to separate from the thrust plate 85 is applied to the rotation shaft 65. The brake torque due to the frictional force between the second brake member 80 and the thrust plate 85 is in a state where the rotation shaft 65 is allowed to rotate in the reverse direction. That is, when the shaft 15 is forcibly rotated in the reverse direction by the driving force of the motor 60, the reverse rotation driving force from the motor 60 is applied to the brake by the frictional force between the second brake member 80 and the thrust plate 85. Since the torque is exceeded, the shaft 15 can rotate efficiently in the reverse direction without being hindered by the second brake member 80. Then, the thrust force acting on the rotating shaft 65 at this time becomes “F ₂ −F ₃ ”, so that the current value of the motor 60 decreases.

When the shaft 15 is driven to rotate in the reverse direction in this manner, the nut 18 screwed into the male screw portion 16 so as to be able to advance and retreat and is prevented from rotating by the support cylinder 19 is set in a state of being retracted along the support cylinder 19. Therefore, the moving cylinder 22 connected to the nut 18 is drawn into the supporting cylinder 19. Due to the retreat of the moving cylinder 22, the bed 4 of the bed 1 connected to the connecting tool 24 of the moving cylinder 22 is lowered.

When the bed 4 is lowered to its original position as shown in FIG. 1B, the motor 60 is automatically stopped. In a state where the nut 18 has returned to the original retracted position, the bed 4 is usually mechanically supported by the frame 2 of the bed 1. Never join. However, even if the load side reverse rotation acting force is constantly applied to the shaft 15 in a state where the bed 4 of the bed 1 is lying down,
By the above-described operation, the reverse rotation of the shaft 15 is reliably prevented. That is, the reverse rotation preventing action by the brake torque between the second brake member 80 and the thrust plate 85 is similarly exhibited even when the nut 18 is stopped in the middle of the male screw portion 16.

By the way, the driving bevel gear 46 and the driven bevel gear 47 as the rotation transmission mechanism between the orthogonal shafts are connected to the shaft 15.
When the actuator 10 is disposed outside the support portion on the rear end side, the intersection of the driving bevel gear 46 and the driven bevel gear 47 pivotally supports the actuator 10 to the frame 2 of the bed 1. In some cases, noise may be generated by the rubbing motion of the shaft 15 because the shaft 15 moves away from the pivot 3. This is because when the intersection between the driving side bevel gear 46 and the driven side bevel gear 47 is separated from the pivot shaft 3, the driving side bevel gear 46 and the driven side bevel gear 46 are driven even if the displacement angle itself of the swirling motion of the shaft 15 is small. This is because the amount of displacement at the intersection with the bevel gear 47 becomes large.

In the present embodiment, the driving-side bevel gear 46
The intersection of the bevel gear 47 and the driven bevel gear 47 is a radial rolling bearing 48
, That is, between the pair of support portions of the shaft 15, the displacement at the intersection of the driving-side bevel gear 46 and the driven-side bevel gear 47 even if the shaft 15 is displaced by a rubbing motion. Since the amount can be kept small, the influence on the meshing between the driving side bevel gear 46 and the driven side bevel gear 47 can be kept small, and as a result, generation of noise is prevented.

Further, a pair of support holes 87 for attaching the pivot 3 are provided with the driving side bevel gear 46 and the driven side bevel gear 4.
Since it is arranged on the axis passing through the intersection with 7, the influence of the sliding motion of the shaft 15 is further reduced. Further, both support holes 87, 87 and the driving-side bevel gear 46
The driven bevel gear 47 and the driven bevel gear 47 are provided in a gear case 63 made of aluminum die-casting, so that the pivot 3, the output shaft 69, and the radial rolling bearing 48 as a rear end side support portion of the shaft 15 are rigidly mounted without rattling. Can be supported,
As a result, it is possible to prevent generation of sound due to the vibration. In addition, the driving side bevel gear 46 and the driven side bevel gear 47
Are both provided in the same gear case 63,
The meshing relationship can be accurately maintained.

In the case of emergency such as a power failure, the dry cell storage 5
The motor 60 is operated by the dry battery stored in the battery 5. The operation in this case is the same as the operation described above. The dry battery may be always installed in the dry battery storage unit 55, or may be prepared so that it can be installed as needed.

According to the present embodiment, the following effects can be obtained. 1) A forward / reverse rotation drive of the shaft via a speed reducer causes a female screw member screwed to a male screw portion on the outer periphery of the shaft to advance and retreat in the axial direction. By doing so, when a large force for moving the female screw member forward or backward is applied to the female screw member from the load side, the reverse rotation acting force on the shaft tries to forcibly rotate the rotating shaft of the motor via the reduction gear. When acting as an external force, the brake torque of the brake member is prevented from rotating against the external force forcibly rotating the rotating shaft, so that the rotating shaft is rotated by the reverse rotating acting force from the load side. Can be prevented. Therefore, even when a large force for moving the female screw member forward and backward is applied to the female screw member from the load side, it is possible to prevent a phenomenon that the female screw member is advanced and retracted.

2) In addition, when viewed from the motor on the driving side, the brake torque acts before deceleration, and acts as a large braking force after deceleration. The reverse rotation acting force from the vehicle can be efficiently braked. That is, the brake member can efficiently brake the reverse rotation acting force from the load side while suppressing the reduction of the driving force of the motor.

3) By arranging a brake member on the axial end face of the rotating shaft of the motor against the reverse rotation acting force applied to the shaft from the load side, the brake device and the one-way clutch on the shaft can be omitted. Therefore, the overall length of the shaft can be reduced, and the size and weight of the actuator can be set small.

4) By shortening the total length of the shaft, an empty space can be relatively set in the housing of the actuator, so that a dry cell storage section can be set, and an emergency battery can be provided. it can. As a result, it is not necessary to attach an emergency battery separately from the actuator, and it is possible to suppress an increase in the cost of the entire system.

5) By shortening the overall length of the shaft, the overall length of the actuator can be reduced, so that the actuator can be reduced in size and weight.

6) Since the intersection of the driving bevel gear and the driven bevel gear as the rotation transmission mechanism between the orthogonal shafts is arranged on the front side of the radial rolling bearing, that is, between the pair of support portions of the shaft, the sliding on the shaft is achieved. Even if a displacement angle occurs due to the sawing motion, the amount of displacement at the intersection between the driving bevel gear and the driven bevel gear is kept small, so the influence on the meshing between the driving bevel gear and the driven bevel gear is also kept small. As a result, generation of sound can be prevented.

7) By arranging a pair of support holes for mounting the pivot on the axis passing through the intersection of the driving side bevel gear and the driven side bevel gear, the influence of the swirling motion of the shaft can be further reduced. be able to.

8) By disposing both the supporting holes, the driving-side bevel gear and the driven-side bevel gear in a gear case made of aluminum die-casting, a pivot for attaching the actuator to the bed frame, an output shaft of the worm gear device, and the like. The radial rolling bearings can be firmly supported without play, and as a result, generation of noise due to their vibrations can be prevented.

[0058]

As described above, according to the present invention,
Since the reverse rotation due to the applied load can be prevented while reducing the size and weight, the state of the bed can always be stably maintained.

[Brief description of the drawings]

FIG. 1 is a front view showing a main part of a medical bed using an actuator according to an embodiment of the present invention,
(A) shows a lying state and (b) shows a standing state.

2A and 2B show an actuator according to an embodiment of the present invention, wherein FIG. 2A is a plan view and FIG. 2B is a front view.

FIG. 3 is a front sectional view thereof.

FIG. 4 is a partially cut-away perspective view showing a main part.

FIG. 5 is a sectional view taken along the line VV of FIG. 2 (b).

FIG. 6 is a plan sectional view showing a motor.

FIG. 7 is an explanatory diagram for explaining an operation of a brake member.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Bed (medical bed), 2 ... Frame, 3 ... Axis, 4 ... Bed, 5 ... Link, 10 ... Actuator, 1
DESCRIPTION OF SYMBOLS 1 ... Housing, 12 ... Shell, 12a ... Band, 12
b: window hole, 13: motor mounting part, 14: shaft insertion part, 15: shaft, 16: male screw part for feeding, 17: female screw part, 18: nut for feeding (female screw member), 19: support cylinder, 20 ... Fixed part, 22: moving cylinder, 23: screw connection part, 24: coupling tool, 25: female screw part for position adjustment, 26 ...
Long hole, 27 ... male screw part for position adjustment, 28 ... tool engagement part,
29 ... connecting hole, 30 ... connecting pin, 30a ... flange, 31 ...
Bracket, 32: connection hole, 33: split pin, 35: nut stopper, 36: position regulating member, 37: insertion hole, 38
... Recess, 39 insertion hole, 40 rivet, 41 cap, 42 follower (rear end of shaft), 43 step, 44 ring, 45 chamfer, 46 driving bevel gear, 47 … Driven bevel gear, 48… radial rolling bearing,
49: chamfered portion, 50: thrust plate, 51: thrust rolling bearing, 52: insertion hole, 53: stopper, 54
... retaining ring, 55 ... dry cell storage room (battery storage room),
56 ... assembled wire, 60 ... motor (motor with worm gear reducer), 61 ... motor housing, 62 ... yoke,
63 ... gear case, 64 ... shaft insertion chamber, 65 ... rotating shaft, 66, 66A ... radial bearing, 66a ... detent hole, 67 ... worm, 68 ... worm wheel, 69 ...
Output shaft, 70: first brake member, 71: small diameter portion, 72
... Large diameter part, 73 ... Contact surface part, 74 ... Flange part, 75 ... Cushion member, 76 ... Storage hole, 80 ... Second brake member, 8
DESCRIPTION OF SYMBOLS 1 ... Small diameter part, 82 ... Large diameter part, 83 ... Contact surface part, 84 ... Storage part, 85 ... Thrust plate, 86 ... Holding hole, 87 ...
Support holes.

Claims (5)

[Claims] 1. An actuator in which a male screw portion is formed on the outer periphery of a shaft driven forward and reverse by a motor via a reduction gear, and a female screw member is screwed to the male screw portion so as to be able to advance and retreat in the axial direction. An actuator, wherein a brake member having a large friction coefficient is slidably contacted with an axial end surface of a rotation shaft of the motor. 2. The brake device according to claim 1, wherein the brake member is disposed on an axial end face on which the rotary shaft is pressed when a reverse rotation acting force is applied to the female screw member from a load side. An actuator according to claim 1. 3. The brake member is disposed on an axial end face on both sides of the rotary shaft, and is a shaft on which the rotary shaft is pressed when a reverse rotation acting force is applied to the female screw member from a load side. The brake torque of the brake member arranged on the direction end face is set to be larger than the brake torque of the brake member on the opposite side.
An actuator according to claim 1. 4. The actuator according to claim 3, wherein the radius of the brake member on the side where the brake torque is large is set to be larger than the radius of the brake member on the side where the brake torque is small. 5. The medical device according to claim 1, wherein a moving cylinder arranged concentrically with the shaft is connected to the female screw member, and the moving cylinder is linked to a bed of a medical bed. 5. The actuator according to 3 or 4.