JP2021110448A - Actuator and sliding switchgear - Google Patents

Abstract

[Problem] To provide an actuator equipped with a ball screw mechanism, which has a stroke equal to the length of the actuator and has a large load-bearing capacity in a direction perpendicular to the screw shaft. [Solution] The actuator 10 comprises a nut unit 20, a screw shaft 30, a motor unit 40, and a board unit 50. The screw shaft 30 has four helical screw grooves 31 on its surface, into which a plurality of non-circulating balls housed in a nut in the nut unit 20 are fitted. The nut is provided with a plurality of through holes each for housing a ball, and the opening diameter on the outer surface side of the through holes is equal to or larger than the diameter of the ball, and the opening diameter on the inner surface side is smaller than the diameter of the ball. As a result, the amount of protrusion of the ball from the inner surface side of the through hole is set so as to obtain an optimal fitting state for the depth and cross-sectional shape of the screw groove 31. [Selected Figure] Figure 1

Description

The present invention relates to an actuator provided with a ball screw mechanism and a slide-type switchgear using the actuator as a driving means.

A ball screw type actuator in which a nut engaged in a screw groove is linearly moved by rotation of a screw shaft is applied in various technical fields. The market demands that such actuators be miniaturized as a whole without reducing the mechanical strength. In order to meet this demand, various ball screw type actuators have been developed (see, for example, Patent Document 1).

As shown in FIG. 14, the motor type actuator 170 of Patent Document 1 has a motor case 171, a housing 187, and a base 189, and bearings 172 and 173 provided at the front and rear ends of the base 189 have a ball screw shaft. 175 is axially supported. The ball screw shaft 175 has a double-threaded groove structure in which spiral thread grooves 177 and 179 are formed on the outer peripheral surface. The output shaft 183 of the motor 181 housed in the motor case 171 is connected to the ball screw shaft 175 via a coupling 185. Further, a nut slider 191 is movably engaged with the ball screw shaft 175 in the axial direction, and a pair of end caps 193 are fixed to both ends of the nut slider 191.

Four guide return paths (not shown) are formed on the side surface of the end cap 193, and a spiral nut groove 196 is formed on the inner peripheral surface of the screw shaft through hole 195 that penetrates the nut slider 191 in the axial direction. ing. The load circulation path 197 and 199 are formed by the spiral screw groove 177 and 179 of the ball screw shaft 175 and the spiral nut groove 196. By providing the load circulation paths 197 and 199 on the side surface of the nut slider 191 in this way, it is possible to reduce the size of the motor actuator 170 without lowering the mechanical strength.

Further, a technique for an opening / closing device such as a door using such an actuator as a driving means has been developed (see, for example, Patent Document 2). As shown in FIG. 15, the door opening / closing device 201 of Patent Document 2 includes a feed screw 202, a nut 203 screwed into the feed screw 202, a rotational force transmitting means 210 for forward / reverse rotation of the feed screw 202, and a door. A connecting member 204 that guides and slides 221 along the base member 206, a bracket 220 that is connected to the connecting member 204 and fixed to the door 221 and a engagement member that is fixed to the nut 203 and engages with the connecting member 204. A combination member 205 is provided.

With such a configuration, the door opening / closing device 201 slides the door 221 by remotely controlling the rotational force transmitting means 210 with the operation button 215 in a state where the connecting member 204 and the engaging member 205 are engaged. It can be opened and closed. On the other hand, the door 221 can be manually opened and closed in a state where the connecting member 204 and the engaging member 205 are disengaged.

However, the actuator 170 shown in FIG. 14 has a structure in which the ball screw shaft 175 is rotated by the motor 181 in the motor case 171 provided at one end to move the nut slider 191 in the axial direction. Therefore, the stroke (movable range) of the nut slider 191 is shorter than the total length of the actuator 170 by the length of the installation portion of the motor case 171.

In addition, the actuator 170 employs a ball screw mechanism in which a load circulation path 197, 199 is provided to circulate the ball. Due to its structure, such a ball circulation type ball screw mechanism is vulnerable to stress applied in a direction perpendicular to the axial direction of the ball screw shaft 175. Therefore, there is a problem that the load capacity in the direction perpendicular to the moving direction of the nut slider 191 becomes small.

Further, the feed screw 202 and the nut 203 of the switchgear 201 shown in FIG. 15 also have a ball screw mechanism of a type for circulating balls, similarly to the actuator 170 described above. Therefore, the load capacity in the direction perpendicular to the axial direction of the lead screw 202, that is, in the vertical direction in FIG. 15 is reduced. Therefore, when the weight of the door 221 is large, the door 221 cannot be moved to the left or right at a predetermined speed defined by the rotational speed of the rotational force transmitting means 210, and the weight of the door 221 that can be opened and closed is also limited. There was a problem.

Therefore, in order to eliminate the weakness of the ball screw mechanism of the ball circulation type, a ball screw mechanism of a method (non-circulation type) in which the ball is rotated on the spot without being circulated has been developed (for example, Patent Document 3). See). The non-circulating ball screw described in Patent Document 3 is composed of a screw having a spiral screw groove and a nut attached to the screw. The nut includes a retainer that holds the ball and a sleeve that has a retainer groove into which the ball fits and is mounted on the outer circumference of the retainer.

The holding body has a tubular holding portion, and the holding portion is provided with a holding hole for holding the ball so as to be rollable. On the other hand, the inner peripheral surface of the sleeve is provided with a single circumferential holding groove into which the ball is fitted. A non-circulating ball screw is formed by mounting the sleeve on the outer periphery of the holding body while fitting the ball in the holding groove on the inner peripheral surface in a state where the ball is held in the holding hole.

JP-A-2019-052717 Japanese Unexamined Patent Publication No. 2001-28001 Japanese Unexamined Patent Publication No. 2016-211606

However, the ball screw nut described in Patent Document 3 has a configuration in which a sleeve having a single circumferential holding groove is mounted on the outer periphery of a holding body that holds the ball. Therefore, the number of balls that can be arranged per the angle in the circumferential direction of the nut and the length in the axial direction is limited, and the density of the balls cannot be increased. As a result, the stress related to the ball screw cannot be effectively dispersed, so that the stress is particularly vulnerable to the stress applied in the direction perpendicular to the axial direction. Therefore, although it is a non-circulation type ball screw, there is a problem that the load capacity in the direction perpendicular to the axial direction of the screw shaft and the nut becomes small.

The present invention has been made under the above circumstances, and is an actuator provided with a non-circulating ball screw mechanism, which is easy to assemble, has a stroke corresponding to the length of the actuator, and is perpendicular to the screw axis. It is an object of the present invention to provide an actuator having a large load capacity in a direction.

Another object of the present invention is to provide a slide-type switchgear that has a long slidable stroke and can open and close a heavy object to be opened and closed at a set speed.

In order to achieve the above object, the actuator according to the first aspect of the present invention is
A screw shaft with a spiral thread groove on the outer peripheral surface,
A plurality of balls fitted in the thread groove and
A nut for accommodating the plurality of balls and
An actuator having a rotational force transmitting means for transmitting a rotational force to the nut.
The nut is a through hole in which the plurality of balls are housed one by one, and the opening diameter on the inner surface side is smaller than the diameter of the ball and the opening diameter on the outer surface side is equal to or larger than the diameter of the ball. A first tubular member provided with a ball and a second tubular member mounted on the outside of the first tubular member and holding the ball contained in the through hole so as not to come out. ,
By transmitting the rotational force to the nut, the rotational force transmitting means relatively moves the screw shaft and the nut along the axial direction of the screw shaft.

The thickness of the tubular wall portion of the first tubular member is thinner than the diameter of the ball, and the inner surface of the second tubular member is provided with a recess that contacts a portion of the ball that protrudes outward from the through hole. It is preferable that it is.

The shape of the recess is preferably substantially conical.

The opening diameter on the inner surface side of the through hole is preferably in the range of 75% (72%) or more and 95% (97%) or less of the diameter of the ball.

It is preferable that a portion of the ball within a range of 15% or more and 40% or less of the diameter protrudes from the opening on the inner surface side of the through hole.

It is preferable that the screw shaft is provided with a plurality of the screw grooves or more, and six or more balls are arranged per circumference of the inner surface of the first tubular member.

It is preferable that the pitch of the screw groove changes along the axial direction of the screw shaft.

The rotational force transmitting means has a clutch mechanism that switches between a state in which a rotational force is transmitted to the nut, a state in which the rotational force is not transmitted to the nut, and a state in which the rotational force is transmitted to the nut in the reverse direction. Is preferable.

In order to achieve the above object, the slide type switchgear according to the second aspect of the present invention is characterized by including any one of the above-mentioned actuators as a driving means.

The slide-type switchgear preferably has a nut fixing means for fixing the nut of the actuator in the vicinity of the object to be slid, and a screw shaft attaching means for attaching the screw shaft to the object to be slid.

The sliding opening / closing device preferably has a screw shaft fixing means for fixing the screw shaft of the actuator in the vicinity of the sliding target, and a nut mounting means for attaching the nut to the sliding target.

According to the present invention, it is possible to obtain an actuator that is easy to assemble, has a stroke corresponding to the length of the actuator, and has a large load capacity in the direction perpendicular to the screw axis. Further, according to the present invention, it is possible to obtain a slide-type switchgear that has a long slidable length and can open and close a heavy object to be opened and closed at a set speed.

It is a perspective view which shows the whole structure of the actuator which concerns on Example 1 of this invention. It is a top view which shows the whole structure of the actuator which concerns on Example 1. FIG. It is an exploded perspective view which shows the internal structure of the nut unit of the actuator which concerns on Example 1. FIG. It is sectional drawing which shows the more detailed internal structure of the nut unit of the actuator which concerns on Example 1. FIG. It is a partial vertical cross-sectional view in the axial direction and the cross-sectional view in the direction perpendicular to the shaft which shows the coupling state of the nut and the screw shaft in the actuator which concerns on Example 1. FIG. FIG. 5 is an enlarged cross-sectional view showing the shape and dimensions of a ball holding portion formed on a nut in the actuator according to the first embodiment, and an enlarged cross-sectional view showing a modified example of the first embodiment. FIG. 5 is an enlarged cross-sectional view showing the shape and dimensions of a ball holding portion formed on a nut in the actuator according to the second embodiment of the present invention. It is an enlarged cross-sectional view which shows the shape of the ball holding part formed in the nut in the actuator which concerns on Example 3 of this invention. It is a top view which shows the whole structure of the actuator which concerns on Example 4 of this invention. It is a schematic diagram explaining the movement of a screw shaft at the time of operation of the actuator which concerns on Example 4. FIG. It is a partial cross-sectional view and the left and right side views which show the internal structure of the actuator which concerns on Example 5 of this invention. It is a schematic diagram which shows 1st specific example of the slide type switchgear which concerns on Example 6 of this invention, and uses the actuator of Example 1. FIG. It is a schematic diagram which shows the 2nd specific example of the slide type switchgear which concerns on Example 7 of this invention, and uses the actuator of Example 1. FIG. It is sectional drawing which shows the whole structure of the motor type actuator by the prior art. It is a schematic diagram which shows the whole structure of the door opening and closing device by a prior art.

The actuator according to the embodiment of the present invention includes at least a screw shaft provided with a spiral screw groove on the outer peripheral surface, a plurality of balls fitted in the screw groove, and a nut accommodating the plurality of balls. , The nut is provided with a rotational force transmitting means for transmitting a rotational force. Then, as the nut rotates, the nut and the screw shaft move relative to each other. That is, the actuator according to the present embodiment includes both a method in which the nut is fixed and the screw shaft moves linearly in the axial direction, and a method in which the screw shaft is fixed and the nut moves linearly in the axial direction. Is done.

In the actuator according to the present embodiment, a plurality of balls fitted in the screw grooves are housed one by one in the through holes provided in the first tubular member, and are placed on the spot without moving from the through holes. Roll with. That is, the actuator according to the present embodiment has a non-circulating ball screw mechanism.

Further, the nut is a through hole in which a plurality of balls are housed one by one, and the opening diameter on the inner surface side is less than the diameter of the ball and the opening diameter on the outer surface side is equal to or larger than the diameter of the ball. It includes a first tubular member provided, and a second tubular member mounted on the outside of the first tubular member and holding the ball contained in the through hole so as not to come out.

The screw shaft, ball, first tubular member, and second tubular member, which are parts constituting the actuator according to the present embodiment, may be made of a metal material such as brass, aluminum, and stainless steel. It may be composed of a thermoplastic resin such as polyethylene, polypropylene or polystyrene, or a fluororesin such as polytetrafluoroethylene. All of these parts may be made of the same material, or may be made of different materials for each part.

Here, the through hole provided in the first tubular member has an opening diameter smaller than the diameter of the ball on the inner surface side of the first tubular member and larger than the diameter of the ball on the outer surface side. That is, the ball is inserted into the through hole from the outer peripheral surface side of the first tubular member and cannot pass through to the inner peripheral surface side. In this way, the plurality of through holes are designed so that the ball can be inserted from the outside of the first tubular member and the ball does not fall inside.

The opening diameters on the outer surface side and the inner surface side of the through hole and the cross-sectional shape are important factors that influence the characteristics of the actuator according to the present embodiment. In particular, the amount of protrusion of the ball toward the inner surface side, that is, the screw shaft side is defined by the ratio of the opening diameter on the inner surface side of the through hole to the diameter of the ball. An optimum fitting state can be obtained by appropriately setting the amount of protrusion of the ball with respect to the depth and cross-sectional shape of the screw groove provided on the screw shaft.

The opening diameter on the inner surface side of the through hole is preferably in the range of 75% (72%) or more and 95% (97%) or less of the diameter of the ball. By setting the opening diameter on the inner surface side within this range, the ball does not fall from the through hole into the first tubular member, and a certain percentage or more of the ball can be projected. The opening diameter on the inner surface side of the through hole is more preferably in the range of 80% or more and 92% or less of the diameter of the ball, and further preferably in the range of 84% or more and 88% or less.

The proportion of the ball protruding from the inner wall of the first tubular member is preferably in the range of 15% or more and 40% or less of the diameter of the ball. By setting the protruding ratio of the ball within this range, it is possible to obtain an appropriate fitting state with respect to the screw groove provided on the screw shaft. The proportion of the balls protruding is more preferably in the range of 20% or more and 35% or less of the diameter of the balls, and further preferably in the range of 25% or more and 30% or less.

Further, the actuator according to the present embodiment is a member of the first tubular member in order to prevent the ball from coming out of the through hole toward the outside of the first tubular member and to keep the ball protruding inward. It has a second tubular member that is mounted on the outside. It is preferable that the inner diameter of the second tubular member mounted for such a purpose is substantially the same as the outer diameter of the first tubular member. If the thickness of the tubular wall of the first tubular member is adjusted to the length obtained by subtracting the amount of protrusion from the through hole from the diameter of the ball, the outer top of the ball almost matches the outer diameter of the first tubular member. do. In this case, the inner surface of the second tubular member is preferably a smooth surface.

On the other hand, when the thickness of the tubular wall portion of the first tubular member is made smaller than the length obtained by subtracting the amount of protrusion from the through hole to the inner surface from the diameter of the ball, the outer top portion of the ball is the outer peripheral surface of the first tubular member. Protruding from. In this case, it is preferable to provide a recess on the inner surface of the second tubular member at a position where the outer top of the ball hits. Further, it is preferable that the shape of the concave portion follows the shape of the outward protruding portion of the ball. By holding the ball in a recess along the shape of the ball in this way, the contact area between the ball and the second tubular member becomes large, and a larger friction coefficient can be obtained. As a result, the efficiency of transmitting the rotational force between the second tubular member and the screw shaft via the ball is increased.

The shape of the concave portion provided on the inner surface of the second tubular member may be substantially conical. As a result, the outer protruding portion of the ball comes into contact with the substantially conical concave portion in a circumferential shape at one place, so that the contact area becomes large. Further, since a gap is formed between the tip of the substantially conical recess and the ball, it is possible to reduce the friction when the ball rolls by holding the lubricating oil in this portion. Further, if a lubricating oil supply port communicating with a substantially conical recess is provided at one location of the second tubular member, lubricating oil can be replenished to the other substantially conical recess through the screw groove of the screw shaft. can.

In the actuator according to the present embodiment, the spiral thread groove provided on the outer peripheral surface of the screw shaft may be a single groove which is a single groove over the entire length of the screw shaft, and two or more grooves are spaced apart from each other. It may be a plurality of grooves provided in the above. The thread groove pitch can be arbitrarily set according to the application of the actuator and the required characteristics. The depth and cross-sectional shape of the thread groove are set so that an optimum fitting state can be obtained according to the diameter of the ball to be fitted and the amount of protrusion toward the screw shaft side.

Further, the pitch of the screw grooves does not necessarily have to be constant over the entire length of the screw shaft, and the pitch may be changed along the axial direction. That is, the pitch of the screw grooves may be gradually reduced or gradually increased. The rate of change in pitch may be constant, or the pitch may change significantly in a specific portion of the screw shaft and may be small in other portions. As a result, even if the rotation speed of the nut is constant, the speed at which the screw shaft moves linearly can be changed depending on the position.

As an effect obtained by changing the pitch of the screw groove, for example, if the pitch is increased at the center of the screw shaft and decreased near both ends, even if the rotation speed of the nut is constant, the end of the screw shaft The movement speed decreases as it approaches the nut. This makes it possible to prevent the screw shaft from coming off the nut without using a stopper.

As described above, the actuator according to the present embodiment can linearly move (slide) the screw shaft or the nut by transmitting the rotary motion transmitted from a drive source such as a motor to the nut. In particular, in the method of fixing the nut side and sliding the screw shaft, the actuator according to the present invention can easily and compactly realize that the nut is rotated to move the screw shaft forward and backward as compared with the actuator using the conventional ball screw. As a result, the actuator of the present invention can not only replace the actuator made of a conventional air cylinder or the like, but also control the advancing / retreating position, which was difficult with such a conventional actuator, by controlling the amount of rotation of the nut. It can be done easily.

The rotational force transmitting means in the present invention is specifically a mechanism for transmitting the rotational force to the nut, and may be, for example, a drive source itself such as a motor, or a transmission device such as a gear train connected to the drive source (a transmission device such as a gear train connected to the drive source). It may be a speed reducer or a speed increaser), or it may be provided with both a drive source and a transmission device. By using the ball screw mechanism described above, the actuator according to the present invention becomes compact and has a relatively simple structure, so that the cost can be reduced.

Next, more specific examples of the actuator and the slide type switchgear according to the present invention will be described with reference to the drawings. However, the following examples are for explaining the present invention with more specific examples, and do not limit the contents of the present invention.

[Example 1]
The actuator according to the first embodiment of the present invention will be described with reference to FIGS. 1 to 6. First, a schematic configuration of the actuator according to the first embodiment will be described with reference to FIGS. 1 and 2. FIG. 1 is a perspective view showing the overall structure of the actuator provided with the ball screw mechanism according to the first embodiment of the present invention. FIG. 2 is a plan view showing the overall structure of the actuator according to the first embodiment.

As shown in FIG. 1, the actuator 10 according to the first embodiment includes a nut unit 20, a screw shaft 30, a motor unit 40, and a substrate unit 50. The nut unit 20 has a unit housing 21 and a pair of end covers 22 and 23 attached to both ends thereof. A nut that is combined with the screw shaft 30 to form a ball screw mechanism is housed in the unit housing 21.

The screw shaft 30 has a spiral screw groove 31 on its surface, and the screw groove 31 is formed from a first screw groove 31a, a second screw groove 31b, a third screw groove 31c, and a fourth screw groove 31d. It has a four-row groove structure. A non-circulating ball is fitted in these four threaded grooves 31 as will be described later.

The motor body 41 is housed inside the motor unit 40, and the rotation of the rotation shaft of the motor body 41 is transmitted to the motor shaft 47 via the intermediate portions 44, 45, 46. The electromagnetic clutch built in the intermediate portions 44, 45, 46 can freely switch between a state in which the motor shaft 47 is connected to the rotating shaft of the motor body 41 and a state in which the motor shaft 47 is not connected. Further, as shown in FIG. 2, an encoder 48 for measuring the rotation direction, rotation position, and rotation speed of the motor shaft 47 to control the motor body 41 with high accuracy is attached to the tip of the motor shaft 47. ing.

The motor shaft 47 and the nut sleeve 62 protruding from the nut unit 20 are connected to each other by a pulley 37 on the motor side, a belt 36, and a pulley 35 on the ball screw side so that rotational force can be transmitted. The rotation of the motor shaft 47 becomes the rotation of the pulley 37 on the motor side, and is transmitted to the pulley 35 on the ball screw side by the belt 36. The nut sleeve 62 rotates together with the ball screw side pulley 35, and the rotational force is transmitted to the nut and the screw shaft 30 housed in the nut unit 20.

The nut unit 20, the screw shaft 30, and the motor unit 40 are mounted on the board body 51 of the board unit 50. The board body 51 is provided with a screw through hole 51a for fixing the board body 51 to an arbitrary position with screws, and an elongated mounting hole 51b used for positioning when fixing the board body 51. By screwing the substrate body 51, the actuator 10 according to the first embodiment can be attached to an arbitrary place.

Next, the internal structure of the nut unit 20 according to the first embodiment will be described with reference to FIG. FIG. 3 is an exploded perspective view showing the internal structure of the nut unit according to the first embodiment. The nut 20 inside the nut unit 20 is combined with the screw shaft 30 to form a ball screw mechanism of the actuator 10.

As shown in FIG. 3, through holes 21a, 22a, which penetrate in the longitudinal direction (axial direction of the screw shaft 30), are formed in the unit housing 21 and the pair of end covers 22, 23 forming the outside of the nut unit 20. 23a is provided. The nut 60 is housed in these through holes 21a, 22a, 23a.

The nut 60 includes a nut cover 61 and a sleeve 62, and the nut cover 61 is provided with a screw through hole 61a. The sleeve 62 has a flange portion 63, and the outer circumference of the sleeve 62 is fixed to the inner ring inner surfaces 24a and 25a of the bearings 24 and 25. When the rotational force of the motor body 41 described with reference to FIGS. 1 and 2 is transmitted to the nut 60, the sleeve 62 rotates extremely smoothly by the action of the pair of bearings 24 and 25.

Screw holes 21b are provided at four locations on both end faces of the unit housing 21. The end covers 22 and 23 are fixed to the unit housing 21 by passing screws through the through holes 22b and 23b of the end covers 22 and 23 and screwing them into the screw holes 21b. In this way, the bearings 24 and 25 are sandwiched between the unit housing 21 and the end covers 22 and 23, and the nuts 60 are housed in the through holes 21a, 22a and 23a with both ends of the sleeve 62 protruding. , The nut unit 20 is assembled.

The cross-sectional structure of the nut unit 20 assembled in this manner will be described with reference to FIG. FIG. 4 is a cross-sectional perspective view showing a more detailed internal structure of the nut unit of the actuator according to the first embodiment. The same components as those in FIG. 3 are designated by the same reference numerals, and some description thereof will be omitted.

As shown in FIG. 4, the sleeve 62 of the nut 60 is a tubular member, and a plurality of through holes 62a are provided on the tubular wall surface thereof. One ball 32 is housed in each of the plurality of through holes 62a. As will be described in detail later with reference to FIG. 6, the through hole 62a is manufactured so that the opening diameter on the inner surface side is smaller than the diameter of the ball 32 and the opening diameter on the outer surface side is larger than the diameter of the ball 32. As a result, each ball 32 is held in a state where it does not fall inside the sleeve 62 and a part of the ball 32 protrudes inside the sleeve 62. That is, the sleeve 62 corresponds to the first tubular member in the present invention.

A nut cover 61 having an inner diameter substantially the same as the outer diameter of the sleeve 62 is attached to the outside of the sleeve 62. By mounting the nut cover 61 on the outside, the ball 32 housed in the through hole 62a is suppressed so as not to come out to the outside. Then, a part of the ball 32 is held in a state of protruding inward. That is, the nut cover 61 corresponds to the second tubular member in the present invention.

A nut 60 having such an internal structure is combined with a screw shaft 30 to form a ball screw mechanism of the actuator 10. The configuration of the ball screw mechanism of the actuator 10 will be described with reference to FIG. FIG. 5 is a partial vertical cross-sectional view in the axial direction showing the coupling state of the nut and the screw shaft in the actuator according to the first embodiment, and a cross-sectional view in the direction perpendicular to the shaft.

As shown in FIG. 5A, the through hole 62a provided in the sleeve 62 has an opening diameter on the outer surface side slightly larger than the outer diameter of the ball 32, and the opening diameter on the inner surface side is reduced to a curved surface to form the ball 32. It is smaller than the outer diameter of. The portion of the ball 32 protruding from the inner opening engages with the four thread grooves 31a, 31b, 31c, 31d of the screw shaft 30. The thickness of the sleeve 62 is set so that the outer top of the ball 32 housed in the through hole 62a coincides with the outer peripheral surface of the sleeve 62. Therefore, by attaching the nut cover 61 having a smooth inner surface to the outer circumference of the sleeve 62, the state in which the ball 32 protrudes toward the screw groove 31 and is engaged is maintained.

Further, as shown in FIG. 5B, the through holes 62a are arranged at eight locations around the inner surface of the sleeve 62 at equal angular intervals. By arranging the through holes 62a at close intervals in both the axial direction and the circumferential direction of the sleeve 62 in this way, the number of balls 32 per length increases. As a result, the nut 60 and the screw shaft 30 are firmly combined to form a ball screw mechanism having a large load capacity in the direction perpendicular to the screw shaft.

Further, the opening diameters and the cross-sectional shapes of the outer surface side and the inner surface side of the through hole 62a are important factors that influence the characteristics of the actuator 10 of the first embodiment. In particular, the amount of protrusion of the ball 32 toward the screw shaft 30 is defined by the ratio of the opening diameter on the inner surface side of the through hole 62a to the diameter of the ball 32. The optimum fitting state can be obtained by appropriately setting the protruding amount of the ball 32 with respect to the depth and the cross-sectional shape of the screw groove 31 provided on the screw shaft 30. For that purpose, it is also important to set the cross-sectional shape of the through hole 62a and the thickness of the sleeve 62.

The setting of the opening diameter of the through hole 62a and the thickness of the sleeve 62 in the actuator 10 will be described with reference to FIG. FIG. 6 is an enlarged cross-sectional view showing the shape and dimensions of the ball holding portion formed on the nut in the actuator according to the first embodiment, and an enlarged cross-sectional view showing a modified example of the first embodiment.

As shown in FIG. 6A, the diameter of the ball 32 is D, the thickness of the sleeve 62 is t1, the opening diameter of the through hole 62a on the outer surface side of the sleeve is w1, the opening diameter on the inner surface side is v1, and the ball 32. Let u1 be the protruding length. The through hole 62a has a cross-sectional shape in which the opening diameter is constant from the outer opening to the position of the thickness s1, and the opening diameter is reduced in a curved shape along the spherical surface of the ball 32 from there to the inner opening. ing.

In the actuator 10, the diameter D of the ball 32, the thickness t1 of the sleeve 62, the opening diameter w1 on the outer surface side of the through hole 62a, the uniform opening diameter s1, and the opening diameter v1 on the inner surface side of the through hole 62a are various sizes. The protrusion length u1 of the ball 32 and the fitting state with the screw groove 31 were investigated. First, as a specific example 1, an actuator 10 having t1 = 1.20 mm, w1 = 1.60 mm, s1 = 0.80 mm, and v1 = 1.37 mm was manufactured using a ball 32 having a diameter D of 1.59 mm. ..

The protrusion length u1 of the ball 32 in the actuator 10 manufactured under such design conditions was 0.40 mm, which was a quarter of the diameter D of the ball 32. Since there is a gap of 0.05 mm between the inner surface of the sleeve 62 and the outer peripheral surface of the screw shaft 30, the length of the protruding portion of the ball 32 that engages with the screw groove 31 is 0.35 mm. When the drive test of the actuator 10 was carried out, the screw shaft 30 slid smoothly with respect to the nut 60, and there was almost no noise. The size of the opening diameter v1 in the specific example 1 is 86.2% of the diameter D of the ball 32, and the protrusion length u1 is 25.2% of the diameter D of the ball 32.

Further, as specific examples 2 to 9, the diameter D of the ball 32, the thickness t1 of the sleeve 62, the opening diameter w1 on the outer surface side of the through hole 62a, and the uniform opening diameter s1 are the same, and the inner surface side of the through hole 62a is the same. The actuator 10 was manufactured by changing only the value of the opening diameter v1. The size of the opening diameter v1 is 1.17 mm in the specific example 2, 1.20 mm in the specific example 3, 1.27 mm in the specific example 4, 1.34 mm in the specific example 5, 1.40 mm in the specific example 6, and the specific example. 7 is 1.46 mm, Specific Example 8 is 1.51 mm, and Specific Example 9 is 1.54 mm.

As a result, the protrusion length u1 of the ball 32 in the actuator 10 manufactured under the conditions of Specific Examples 2 to 9 is 0.21 mm in Specific Example 2, 0.24 mm in Specific Example 3, and 0.32 mm in Specific Example 4. Specific Example 5 was 0.37 mm, Specific Example 6 was 0.47 mm, Specific Example 7 was 0.55 mm, Specific Example 8 was 0.63 mm, and Specific Example 9 was 0.66 mm.

When the conditions of Specific Examples 1 to 9 are shown by the ratio of the diameter D of the ball 32 to the diameter D of the ball 32, the specific example 1 is 86%, the specific example 2 is 73%, the specific example 3 is 75%, and the specific example 3 is 75%. Example 4 is 80%, Specific Example 5 is 84%, Specific Example 6 is 88%, Specific Example 7 is 92%, Specific Example 8 is 95%, and Specific Example 9 is 97%. Regarding the protrusion length u1, the specific example 1 is 25%, the specific example 2 is 13%, the specific example 3 is 15%, the specific example 4 is 20%, the specific example 5 is 23%, and the specific example 6 is 30%. , Specific Example 7 is 34%, Specific Example 8 is 40%, and Specific Example 9 is 42%.

A drive test was carried out on the actuator 10 manufactured under the conditions of Specific Examples 2 to 9 in the same manner as in Specific Example 1. Under the conditions of Specific Examples 3 to 8, the screw shaft 30 slid smoothly with respect to the nut 60, and there was almost no noise. In particular, the actuator 10 manufactured under the conditions of Specific Examples 4 to 7 showed the same level of smooth sliding property and quietness as those of Specific Example 1 in the drive test.

On the other hand, the actuator under the condition of Specific Example 2 was inferior in the slidability of the screw shaft 30 with respect to the nut 60 in the drive test. Since the opening diameter v1 on the inner surface side of the through hole 62a is small, it is considered that the protruding length u1 of the ball 32 is insufficient and the engagement with the screw groove 31 is not sufficient. Further, the actuator under the condition of Specific Example 9 became louder in the drive test. Since the opening diameter v1 on the inner surface side of the through hole 62a is large, it is probable that the position of the ball 32 in the through hole 62a was not stable.

From the above results, it can be seen that the opening diameter v1 on the inner surface side of the through hole 62a is preferably in the range of 75% to 95% of the diameter D of the ball 32. By setting the opening diameter v1 on the inner surface side within this range, the balls 32 are stably housed inside the through hole 62a, do not fall to the inner surface side of the sleeve 62, and the balls 32 are contained at a certain ratio or more. It can be in a protruding state. The opening diameter v1 is more preferably in the range of 80% to 92% of the diameter D of the ball 32, and further preferably in the range of 84% to 88%.

Further, from the above results, it can be seen that the protruding length of the ball 32 from the sleeve 62 is preferably in the range of 15% to 40% of the diameter D of the ball 32. By setting the protruding ratio of the ball 32 within this range, it is possible to obtain an appropriate fitting state with respect to the screw groove 31 provided in the screw shaft 30. The proportion of the balls 32 protruding is more preferably in the range of 20% to 35% of the diameter of the balls, and even more preferably in the range of 25% to 30%.

As described above, by setting the opening diameter v1 on the inner surface side of the through hole 62a within the range of 75% to 95% of the diameter D of the ball 32, the protruding length of the ball 32 from the inner wall of the sleeve 62 is the diameter D. It is in the range of 15% to 40%. As a result, the amount of protrusion of the ball 32 becomes an appropriate size with respect to the depth and cross-sectional shape of the screw groove 31 provided on the screw shaft 30, and an optimum fitting state can be obtained. That is, the actuator 10 has a screw shaft 30 that slides smoothly and accurately, has a large load capacity in the direction perpendicular to the screw shaft 30, and has less wear and noise.

Further, as shown in FIG. 6A, the through hole 62a has a constant inner diameter from the outer opening to the thickness s1, and the inner diameter from there to the inner opening is curved along the spherical surface of the ball 32. Has a cross-sectional shape that shrinks. Further, the thickness t1 of the sleeve 62 is set so that the outer upper end when the ball 32 comes into contact with the inner opening of the through hole 62a and the outer peripheral surface of the sleeve 62 coincide with each other. Therefore, the nut cover 61 mounted on the outer circumference of the sleeve 62 suppresses the vertical movement of the ball 32 in the through hole 62a. As a result, the ball 32 rolls without shifting in the vertical direction and engages with the screw groove 31 while maintaining a constant depth.

Next, a modified example of the actuator 10 according to the first embodiment will be described with reference to FIG. 6 (b). As shown in FIG. 6B, the through hole 62b of this modified example has a cross-sectional shape different from that of the through hole 62a. That is, the cross-sectional shape of the through hole 62b is a substantially conical shape in which the inner diameter extends linearly from the inner opening to the outer opening of the sleeve 62. Therefore, in the through hole 62a shown in FIG. 6A, the difference between the opening diameter w1 on the outer surface side and the diameter D of the ball 32 is small, whereas the opening diameter W on the outer surface side of the through hole 62b There is a large difference from the diameter D of the ball 32.

Even in such a modified example, if the diameter D of the ball 32, the thickness t1 of the sleeve 62, and the opening diameter v1 on the inner surface side are set to the same values as those of the above specific examples 1 to 9, the protruding length u1 of the ball 32 is set. It is considered that the same value can be obtained. In addition, the through hole 62a shown in FIG. 6A described above has a cross-sectional shape in which the inner diameter does not change at the portion of s1 and changes on a curved surface below the inner diameter. Therefore, it is considered that at least two steps are required to form the through hole 62a in the sleeve 62. On the other hand, it is easy to pierce the through hole 62b having a substantially conical cross-sectional shape shown in the modified example of FIG. 6 (b).

However, as shown in FIG. 6B, the ball 32 housed in the through hole 62b comes into contact with the sleeve 62 and the nut cover 61 only at the portion corresponding to the periphery of the inner surface side opening and the outer top portion. That is, the area where the ball 32 contacts the sleeve 62 and the nut cover 61 is small. Therefore, it is difficult to efficiently transmit the rotational force from the screw shaft 30 to the sleeve 62 and the nut cover 61 via the ball 32.

On the other hand, as shown in FIG. 6A, the ball 32 housed in the through hole 62a is in contact with the sleeve 62 at a curved surface portion provided along the spherical surface. Therefore, the area where the ball 32 comes into contact with the sleeve 62 and the nut cover 61 is large, and the stress applied from the screw groove 31 is efficiently transmitted through the ball 32. As described above, the actuator 10 according to the first embodiment provided with the through hole 62a having a unique cross-sectional shape exhibits superior characteristics as compared with the case of the through hole 62b having a simple cross-sectional shape shown in the modified example.

[Example 2]
Next, the actuator according to the second embodiment of the present invention will be described with reference to FIG. 7. FIG. 7 is an enlarged cross-sectional view showing the shape and dimensions of the ball holding portion formed on the nut in the actuator according to the second embodiment of the present invention. In FIG. 7, the components common to the actuator of the first embodiment are designated by the same reference numerals as those of the first embodiment.

The actuator according to the second embodiment has a larger contact area between the ball and the member constituting the nut than the actuator of the first embodiment, thereby passing the ball from the thread groove to the nut or from the nut to the thread groove. This is to make it possible to increase the transmission efficiency of the rotational force. As shown in FIG. 7, the actuator according to the second embodiment has a first sleeve 64, a second sleeve 65 mounted on the outer periphery thereof, and a nut mounted on the outer periphery thereof, as members constituting the nut. It has a cover 66 and.

The first sleeve 64 is a tubular member, and a plurality of through holes 64a are provided in the tubular wall surface. One ball 32 is housed in each of the plurality of through holes 64a. The through hole 64a is manufactured so that the opening diameter v2 on the inner surface side is smaller than the diameter D of the ball 32 and the opening diameter w2 on the outer surface side is larger than the diameter D of the ball 32. As a result, the ball 32 is held in a state in which the ball 32 does not fall inside the first sleeve 64 and a part of the ball 32 protrudes inside the first sleeve 64. Therefore, the first sleeve 64 corresponds to the first tubular member in the present invention.

On the outside of the first sleeve 64, a tubular second sleeve 65 having an inner diameter substantially the same as the outer diameter of the first sleeve 64 is mounted. By mounting the second sleeve 65 on the outside, the ball 32 housed in the through hole 64a is suppressed so as not to come out to the outside. Further, by being restrained by the second sleeve 65 from the outside, a part of the ball 32 is held in a state of protruding inside the first sleeve 64. Therefore, the second sleeve 65 corresponds to the second tubular member in the present invention.

The cross-sectional shape of the through hole 64a provided in the first sleeve 64 is slightly different from that of the through hole 62a of the first embodiment, and is curved along the spherical surface of the ball 32 over the entire thickness t2 of the first sleeve 64. ing. Further, the difference between the opening diameter w2 on the outer surface side and the opening diameter v2 on the inner surface side is smaller than the average value of the through hole 62a of the first embodiment. For example, in Specific Example 1 of Example 1, the opening diameter w1 = 1.60 mm, the opening diameter v1 = 1.37 mm, and the difference between w1 and v1 is 0.23 mm. On the other hand, in the second embodiment, w2 = 1.60 mm and v2 = 1.53 mm, and the difference is 0.07 mm. Therefore, the ratio of the protruding length u2 of the ball 32 to the diameter D of the ball 32 is also larger than the average value of Example 1.

The actuator according to the second embodiment is most different from the first embodiment in that the recess 65a is provided on the inner surface of the second sleeve 65. The entire recess 65a is a concave curved surface along the spherical surface of the ball 32. The depth s2 of the recess 65a changes depending on the thickness t2 of the first sleeve 64 and the opening diameter v2 on the inner surface side of the through hole 64a. That is, the depth s2 is set so that the inner surface of the recess 65a comes into contact with the ball 32 according to the length of the ball 32 protruding toward the outer surface side of the through hole 64a. Therefore, the recess 65a corresponds to the "recess that abuts the portion that protrudes outward from the through hole of the ball" in the present invention.

As described above, in the second embodiment, the concave portion 65a is provided on the inner surface of the second sleeve 65, and the concave portion 65a is formed into a curved surface shape along the spherical shape of the portion protruding to the outside of the ball 32. By holding the ball 32 in the recess 65a along the shape of the ball 32 in this way, the contact area between the ball 32 and the second sleeve 65 becomes large, and a larger friction coefficient can be obtained. Thereby, the efficiency of transmitting the rotational force from the second sleeve 65 to the screw shaft 30 or from the screw shaft 30 to the second sleeve 65 via the ball 32 can be improved.

[Example 3]
Next, the actuator according to the third embodiment of the present invention will be described with reference to FIG. FIG. 8 is an enlarged cross-sectional view showing a ball holding portion formed on a nut in the actuator according to the third embodiment of the present invention. The third embodiment can be regarded as a modification of the second embodiment, and the same reference numerals are given to the components common to those in FIG. 7 in FIG. The actuator according to the third embodiment improves the transmission efficiency of the rotational force between the screw groove and the nut constituent member by changing the shape of the concave portion in the actuator of the second embodiment.

As shown in FIG. 8, the actuator according to the third embodiment has a first sleeve 64, a second sleeve 67 mounted on the outer periphery thereof, and a nut mounted on the outer periphery thereof, as in the second embodiment. It has a cover 66. A plurality of recesses 67a are provided on the inner surface of the second sleeve 67. The shape of the recess 67a is considerably different from the shape of the recess 65a of the second embodiment.

That is, as shown in FIG. 8, the inner surface of the recess 67a has a substantially conical shape. Therefore, the portion of the ball 32 protruding outward comes into contact with the inner surface of the recess 67a in a circumferential shape at the portion indicated by reference numeral 67c. Further, a gap 67b is formed between the ball 32 and the substantially conical tip portion of the recess 67a. By holding the lubricating oil in the gap 67b, the friction when the ball 32 rolls can be reduced. Further, if the lubricating oil supply port communicating with the recess 67a is provided at at least one position of the second sleeve 67, the lubricating oil can be supplied to the other recess 67a through the continuous screw groove 31.

As described above, in the third embodiment, the shape of the recess 67a provided on the inner surface of the second sleeve 67 is substantially conical. As a result, the outer protruding portion of the ball comes into contact with the substantially conical recess 67a in a circumferential shape at the portion indicated by the reference numeral 67c, so that the contact area becomes large. Further, by holding the lubricating oil in the gap 67b generated between the tip of the recess 67a and the ball 32, the friction when the ball 32 rolls can be reduced. Further, if the lubricating oil replenishment port communicating with the recess 67a is provided at at least one position of the second sleeve 67, the lubricating oil can be replenished to the other recesses 67a.

[Example 4]
Next, the actuator according to the fourth embodiment of the present invention will be described with reference to FIGS. 9 and 10. FIG. 9 is a plan view showing the overall structure of the actuator according to the fourth embodiment of the present invention, and a graph showing changes in the pitch of the screw grooves. FIG. 10 is a schematic view illustrating a change in the moving speed of the screw shaft when the actuator according to the fourth embodiment is operated.

The actuator according to the fourth embodiment is different from the actuators of the first to third embodiments in that the pitch of the screw groove provided on the screw shaft is not constant, and the pitch of the screw groove depends on the distance from the central portion of the screw shaft. This is a changing point. With such a configuration, in the actuator according to the fourth embodiment, even if the rotation speed on the nut side is the same, the moving speed of the screw shaft changes between the vicinity of the center of the screw shaft and the vicinity of both ends. As a result, the actuator according to the fourth embodiment exerts a special effect.

As shown in FIG. 9, the actuator 11 according to the fourth embodiment includes a nut unit 70, a screw shaft 80, a motor unit 40, and a substrate unit 50, similarly to the actuator 10 of the first embodiment. The nut unit 70 has a unit housing 71 and a pair of end covers 72, 73 attached to both ends thereof. A nut that is combined with the screw shaft 80 to form a ball screw mechanism is housed in the unit housing 71.

The internal structure of the nut unit 70 of the actuator 11 including the nut is the same as that of the first embodiment. That is, the nut unit 70 has the internal structure shown in FIGS. 3 to 5. Therefore, detailed description will be omitted.

A screw shaft 80 is engaged with the nut unit 70, and a screw groove 81 is provided on the surface of the screw shaft 80. The screw groove 81 has a four-row groove structure including a first screw groove 81a, a second screw groove 81b, a third screw groove 81c, and a fourth screw groove 81d. A non-circulating ball is engaged in the nut unit 70 in the nut unit 70 as in the first to third embodiments.

As shown in FIG. 9, unlike the cases of Examples 1 to 3, the pitch of these four threaded grooves 81 is not constant. That is, the pitch of the screw groove 81 is the largest at the central portion of the screw shaft 80, decreases toward the end, and becomes the smallest at both end portions. As shown in the graph in FIG. 9, in the fourth embodiment, the pitch of the screw groove 81 of the screw shaft 80 is continuously changed at a constant rate of change, but the rate of change of the pitch is not constant. May be good. Further, if possible, the pitch of the thread grooves 81 may be changed stepwise, that is, discontinuously.

The board unit 50 has a board body 51, and a nut unit 70, a screw shaft 80, and a motor unit 40 are mounted on the board body 51. Similar to the first embodiment, the board body 51 has a screw through hole 51a for fixing the board body 51 to an arbitrary place with screws, and a mounting slot for positioning when fixing the board body 51. 51b are bored at four places each.

The motor body 41 is housed inside the motor unit 40, and the encoder 48 is attached to the motor shaft 47 of the motor body 41. Further, a motor-side pulley 37 is fixed to the motor shaft 47. A belt 36 for transmitting a rotational force to the ball screw side pulley 35 is hung on the motor side pulley 37. When the ball screw side pulley 35 rotates, a rotational force is applied to the nut in the nut unit 70 via the sleeve 82.

As described above, since the nut unit 70 and the motor unit 40 have the same configuration as that of the first embodiment, the rotation speed of the nut can be controlled by controlling the rotation speed of the motor main body 41 as in the first embodiment described above. In the first embodiment, the moving speed of the screw shaft 30 changes uniformly over the entire length according to the change in the rotation speed of the nut. On the other hand, in the actuator 11 of the fourth embodiment, even if the rotation speed of the motor body 41 is kept constant, the moving speed of the screw shaft 80 automatically changes according to the change in the pitch of the screw groove 31. It has characteristics.

The change in the moving speed of the screw shaft 80 in the actuator 11 will be described with reference to FIG. As shown in FIG. 10A, when the motor body 41 is rotated while the screw shaft 80 is fitted to the nut unit 70 near one end of the screw shaft 80, the screw shaft 80 moves to the left in the figure at an initial velocity V1. Start moving to. Even if the rotation speed of the motor body 41 is constant, the pitch of the screw groove 31 increases as it approaches the center of the screw shaft 80, so that the moving speed of the screw shaft 80 gradually increases. Then, as shown in FIG. 10B, when the central portion of the screw shaft 80 reaches the nut unit 70, the moving speed of the screw shaft 80 reaches the maximum speed V2.

As the screw shaft 80 moves further, the speed gradually decreases to V3, as shown in FIG. 10 (c). Then, when the screw shaft 80 reaches the vicinity of the other end as shown in FIG. 10D, the moving speed is reduced to V1 again. As described in the first embodiment, in the ball screw mechanism, a stopper is usually attached to prevent the screw shaft from coming off the nut. On the other hand, in the actuator 11, if the minimum speed V1 is sufficiently small, the rotation of the motor body 41 is surely stopped and the screw shaft 80 is stopped when the screw shaft 80 comes near the other end. Can be done. As described above, the actuator 11 of the fourth embodiment has a feature that the screw shaft can be reliably prevented from falling off from the nut without using a stopper.

[Example 5]
Next, the actuator according to the fifth embodiment of the present invention will be described with reference to FIG. FIG. 11 is a partial cross-sectional view and left and right side views showing the internal structure of the actuator according to the fifth embodiment of the present invention. Since the configuration of the entire actuator (not shown in FIG. 11) is the same as that of the first to fourth embodiments, detailed description thereof will be omitted. In the actuator according to the fifth embodiment, in addition to the action and effect obtained by the actuators of the first to fourth embodiments, the effect of suppressing backlash when the screw shaft is reversed can be obtained.

As shown in FIG. 11, the actuator 12 of the fifth embodiment has a ball screw mechanism including a nut 90 and a screw shaft 100 having a screw groove 101 formed therein. The thread groove 101 has a four-row groove structure including a first thread groove 101a, a second thread groove 101b, a third thread groove 101c, and a fourth thread groove 101d. A non-circulating ball 102 is fitted into these four threaded grooves 31.

The nut 90 includes a cylindrical outer cylinder portion 91, a fixed holder 95 fixed to the outer cylinder portion 91, a rotary holder 92 that can rotate around the central axis with respect to the outer cylinder portion 91, a collar 104, and an end. It has a lid portion 106. A non-circulating ball 102 is housed in each of the plurality of through holes provided in the fixed holder 95 and the rotating holder 92. Therefore, the fixed holder 95 and the rotating holder 92 correspond to the first tubular member in the present invention. Further, the outer cylinder portion 91 corresponds to the second tubular member in the present invention.

In the fifth embodiment, each member 91, 92, 95, 102, 104, 106 constituting these nuts 90 is made of a metal material. The materials and surface treatments (quenching, plating, etc.) that form each of these members 91, 92, 95, 102, 104, 106 are modified according to the requirements for the nut 90, such as mechanical strength, durability, or price. You may. For example, all or part of each member 91, 92, 95, 102, 104, 106 can be made of a non-metal material such as various synthetic resins or ceramics instead of a metal material.

The outer cylinder portion 91 has a cylindrical tubular portion 91a having a large inner diameter and a long axial direction, and a cylindrical constricted portion 91b having an inner diameter smaller than that of the tubular portion 91a. Further, the outer cylinder portion 91 is provided with four screw holes 91d extending in the axial direction, a through hole 91c penetrating in the radial direction, and four through holes 91e (see the left side view) penetrating in the radial direction. ing. The fixed holder 95 is provided with four through holes 95a at positions corresponding to the four screw holes 91d.

The screw hole 91d is used to attach the fixing holder 95 to the outer cylinder portion 91. The through hole 91c is used for passing a screw that fixes the rotary holder 92 to the outer cylinder portion 91. Further, the through hole 91e is used for passing a screw for fixing the end lid portion 106 to the outer cylinder portion 91. As shown in FIG. 11, the through hole 95a is provided with a counterbore 95b for accommodating the screw head. Similarly, the through hole 91c is also provided with a counterbore for accommodating the screw head.

The fixed holder 95 has a cylindrical tubular portion 93 that is long in the axial direction and a flange portion that has a larger outer diameter than the tubular portion 93. The outer diameter of the tubular portion 93 is substantially the same as the inner diameter of the narrowed portion 91b in the outer cylinder portion 91, and the outer diameter of the flange portion is substantially the same as the outer diameter of the outer cylinder portion 91. The inner diameters of the tubular portion 93 and the flange portion are both set to be slightly larger than the outer diameter of the screw shaft 100 so that the screw shaft 100 can rotate. Further, as shown in the right side view of FIG. 11, the flange portion is provided with four screw holes 91f extending in the axial direction for fixing the nut 90 to the drive target.

Also in the fifth embodiment, as in the first to fourth embodiments, the through hole in which the ball 102 is housed has an opening diameter on the inner surface side smaller than the diameter of the ball 102. As a result, the balls 102 in the through holes do not fall inside the fixed holder 95 and the rotating holder 92. On the other hand, the opening diameter on the outer surface side of the through hole is made larger than the diameter of the ball 102. Therefore, the ball 102 is accommodated in the through hole from the outer peripheral side of the fixed holder 95 and the rotating holder 92.

Further, a cylindrical collar 104 is located on the outer periphery of the fixed holder 95 and the rotating holder 92 in a portion where a through hole is formed. Therefore, the outer top of the ball 102 in the through hole comes into contact with the inner surface of the collar 104. The collar 104 is a cylindrical member, which is rounded at both ends, as shown in FIG. The collar 104 is arranged in a space formed between the tubular portion of the fixed holder 95 and the rotating holder 92 and the tubular portion 91a of the outer tubular portion 91.

The collar 104 is manufactured so that the inner diameter is larger than the outer diameter of the tubular portion of the fixed holder 95 and the rotary holder 92, and the outer diameter is smaller than the inner diameter of the tubular portion 91a of the outer cylinder portion 91. Therefore, a radial gap is formed between the collar 104 and the tubular portion of the fixed holder 95 and the rotary holder 92, and between the collar 104 and the tubular portion 91a of the outer tubular portion 91.

By forming the radial gap in this way, the collar 104 is rotatable around the axis. When the screw shaft 100 is rotated, a force is applied to the collar 104 along the axial direction, and the collar 104 comes into contact with the protruding portion 94 of the rotating holder 92 or the narrowed portion 91b of the outer cylinder portion 91. In this case, since both ends of the collar 104 are rounded, the frictional resistance between the protruding portion 94 of the rotary holder 92 or the narrowed portion 91b of the outer cylinder portion 91 and the end portion of the collar 104 is reduced. The collar 104 can rotate smoothly.

Further, the through hole provided in the tubular portion 93 of the fixed holder 95 and the through hole provided in the rotary holder 92 are provided so as to be displaced in the axial direction by 1/2 of the distance between the through holes. Therefore, as shown in the left and right side views of FIG. 11, the balls 102 project from the eight directions at intervals of 45 degrees around the central axis toward the screw groove 101 side of the screw shaft 100.

In the fifth embodiment, the axial movement of the collar 104 is restricted by the protruding portion 94 of the rotary holder 92 and the narrowed portion 91b of the outer cylinder portion 91, but the axial movement of the collar 104 is restricted by a different method. It is also possible to regulate movement. For example, the tubular portion 93 of the fixed holder 95 may be provided with an outwardly projecting portion to restrict the movement of the collar 104 to the right in FIG. Further, another member may be inserted into the tubular portion 91a of the outer tubular portion 91 to restrict the movement of the collar 104 to the left in FIG. 11.

Here, in a normal ball screw mechanism that does not have the collar 104 as in the fifth embodiment, even if the screw shaft 100 does not rotate, when the screw shaft 100 moves in the axial direction, the screw shaft 100 moves. As a result, the ball 102 moves outward. In this state, when the screw shaft 100 is rotated in one direction and then the rotation direction is reversed, the ball 102 moves inward once immediately after the rotation direction is reversed, and then the ball nut 90 moves until it moves outward. Does not move in the axial direction. Due to such a cause, a phenomenon that the ball nut 90 does not move in the axial direction immediately after the rotation direction of the screw shaft 100 is reversed, that is, backlash occurs.

On the other hand, the ball nut 90 of the fifth embodiment is provided with the collar 104. As a result, when the rotary holder 92 is rotated, the screw groove 101 advances along the axis in the right direction of FIG. 11 on the rotary holder 92 side. When the thread groove 101 advances to the right in FIG. 11, the ball 102 on the rotation holder 92 side is pushed outward and comes into contact with the collar 104. When the rotary holder 92 is rotated while the ball 102 on the rotary holder 92 side is in contact with the collar 104, the ball 102 on the rotary holder 92 side is pushed to the right in FIG. 11 by the screw groove 101, and the rotary holder 92 is pushed. It moves to the right in FIG.

By moving the rotary holder 92 to the right in FIG. 11 in this way, the rotary holder 92 comes into contact with the fixed holder 95. When the rotary holder 92 is further rotated while the rotary holder 92 and the fixed holder 95 are in contact with each other, the screw groove 101 is pushed to the left in FIG. 11 by the ball 102 on the rotary holder 92 side, and the screw shaft 100 is pushed to the left in FIG. Move to the left of. In this way, when the screw shaft 100 moves to the left in FIG. 11, the phase of the screw groove 101 advances to the left in FIG. 11 on the fixed holder 95 side, and the ball 102 on the fixed holder 95 side is pushed out. ..

When the ball 102 on the fixed holder 95 side is pushed outward, the ball 102 on the rotating holder 92 side comes into contact with the collar 140. As a result, the thread groove 101 and the ball 102 come into contact with each other, and the ball 102 and the collar 104 come into contact with each other. As a result, the axial component of the load applied from the screw shaft 100 to the ball 102 is transmitted to the rotary holder 92, and the radial component of the load is transmitted to the collar 104. As a reaction of these loads, a load from the rotary holder 92 to the left in FIG. 11 and a radial load from the collar 104 inward are applied to the ball 102.

Then, a combined load of the load from the fixed holder 95 and the load from the collar 104 is applied from the ball 102 to the screw shaft 100. By applying a load between the fixed holder 95, the rotating holder 92, the collar 104, the ball 102 and the screw shaft 100 (screw groove 101) in this way, the fixed holder 95, the rotating holder 92, the inner surface of the collar 104, and the ball 102. Since the relative positional relationship between the screw groove 101 and the screw groove 101 is fixed, the occurrence of backlash is suppressed.

As described above, the ball nut 90 of the fifth embodiment suppresses the occurrence of backlash by providing the collar 104. Therefore, even if the rotation direction of the screw shaft 100 is reversed, the ball nut 90 follows and moves without causing a time lag. As a result, the actuator can precisely control the moving position of the ball nut 90 or the screw shaft 100.

The actuators of Examples 1 to 5 described above can be used as a driving mechanism for applying a driving force for moving an object in various devices such as a sliding door type door opening / closing device. Further, in addition to the application as such a drive mechanism, various applications can be considered as the application of the actuators of Examples 1 to 5.

For example, as an application to a slide-type length measuring device for measuring the length of a long object or the like, the nut portion of the actuator is attached near the measurement target or directly on the measurement target. On the other hand, a probe indicating a measurement point and a scale capable of reading the moving length of the probe are attached to the screw shaft of the actuator. By sliding the screw shaft, moving the probe along a long object to be measured, and reading the moving length of the probe, the length of the measurement target can be measured accurately. On the contrary, it is of course possible to fix the screw shaft, attach a probe to the nut portion, and slide the nut portion as a length measuring device.

It can also be applied by moving the nut or screw shaft of the actuator in the vertical direction. For example, using two actuators having screw shafts having sufficient thickness and length, the two screw shafts are vertically attached to the outer wall of a building or the like at a predetermined interval. By attaching a cleaning tool between the nuts of the two actuators and moving the cleaning tool vertically by moving the nuts up and down at the same speed, it can be applied to an unmanned cleaning device for high places.

[Example 6]
As an application example of the actuators of Examples 1 to 5, a first slide-type switchgear to which the actuator is applied as a drive mechanism will be described with reference to FIG. FIG. 12 is a schematic view showing a first specific example of the slide switchgear according to the sixth embodiment of the present invention, which uses any of the actuators of the first to fifth embodiments. ..

In the slide-type switchgear according to the sixth embodiment, the manual glass window 111 shown in FIG. 12A has an actuator unit 120 equivalent to any of the actuators 10, 11 and 12 of the first to fifth embodiments. It is a device that can be opened and closed using. That is, as shown in FIG. 12B, according to the slide-type switchgear 110 of the sixth embodiment, the actuator unit 120 including the actuator main body 121 and the screw shaft 123 is attached to the manual glass window 111. By retrofitting the parts, it can be made into an electric glass window.

The actuator unit 120 includes a main body cover 122 and a screw shaft 123 in which the actuator main body 121 is housed. The actuator main body 121 has a structure equivalent to that of the actuators 10, 11 and 12 of any of the first to fifth embodiments, and a nut unit, an electric motor and the like are attached to the substrate. The power cable that supplies current to the electric motor of the actuator body 121 is not shown. As the mounting parts, a window glass mounting plate 114a for mounting the screw shaft 123 on one of the glass windows 111, a screw shaft mounting member 114b, and a universal joint 114c are used.

The slide-type switchgear 110 having such a configuration is attached to the glass window 111 shown in FIG. 12A by the following procedure. First, as shown in FIG. 12B, the main body cover 122 is fixed to the window frame upper portion 111A of the glass window 111 by screwing or the like. Next, the window glass mounting plate 114a is fixed to the window glass 113B of the right window 112B located on the front side. Subsequently, the screw shaft mounting member 114b is attached to the tip of the screw shaft 123. Then, the screw shaft mounting member 114b is fixed to the window glass mounting plate 114a by the universal joint 114c.

The glass window 111 can be opened and closed by moving the screw shaft 123 integrally with the right window 112B with respect to the actuator body 121 fixed to the window frame upper portion 111A in this way. That is, when electric power is supplied from a power cable (not shown) to rotate the electric motor of the actuator main body 121, the screw shaft 123 slides with respect to the actuator main body 121. As a result, the right side window 112B to which the tip of the screw shaft 123 is attached also slides left and right, and the glass window 111 is opened and closed.

Specifically, when the nut in the actuator body 121 is rotated in a predetermined direction while the glass window 111 is closed as shown in FIG. 12B, the screw shaft 123 is integrated with the right window 112B. Slide to the left. This opens the glass window 111 as shown in FIG. 12 (c). When the nut in the actuator body 121 is rotated in the opposite direction, the right window 112B slides to the right together with the screw shaft 123, and the glass window 111 is closed again.

As described above, the slide-type switchgear 110 according to the sixth embodiment can be retrofitted to the manual glass window 111 to form an electric window. Further, as described in the first embodiment, the electric motor of the actuator main body 121 has a built-in electromagnetic clutch. The electromagnetic clutch can freely switch between a state in which the rotating shaft of the motor and the nut are connected and a state in which the nut is not connected. Therefore, by switching the electromagnetic clutch to the unconnected state, the glass window 111 can be manually opened and closed as before.

Here, the slide-type switchgear 110 has a configuration in which the screw shaft 123 linearly moves with respect to the fixed actuator main body 121. Therefore, the right side window 112B can be moved over the entire length of the screw shaft 123, and a sufficient stroke can be obtained. Further, the actuator main body 121 has a structure equivalent to that of the actuators 10, 11 and 12 of any of the first to fifth embodiments, and adopts a non-circulation type ball screw structure in which the ball does not circulate. Therefore, the load capacity is large in the direction perpendicular to the axial direction of the screw shaft 123, that is, in the vertical direction in FIG. 12, and the glass window 111 can be opened and closed smoothly.

In this way, the slide-type switchgear 110 according to the sixth embodiment is a slide-type switchgear that can open and close at a set speed even if the object to be opened and closed has a long slidable stroke and is heavy.

[Example 7]
As a second application example of the actuators of Examples 1 to 5, a second slide-type switchgear to which the actuator is applied as a drive mechanism will be described with reference to FIG. FIG. 13 is a schematic view showing a second specific example of the slide switchgear according to the seventh embodiment of the present invention, which uses any of the actuators of the first to fifth embodiments. ..

As shown in FIG. 13, the slide-type opening / closing device according to the seventh embodiment is a device that enables the manual doors 151a and 151b installed at the entrance / exit 150 of the building to be opened / closed by using an actuator. .. That is, according to the slide type opening / closing device of the seventh embodiment, the actuator unit 140 having the actuator main body 141 and the screw shaft 143 and the mounting parts are retrofitted to the manual doors 151a and 151b to be electrically operated. It can be a door.

The actuator unit 140 includes a main body cover 142 in which the actuator main body 141 is housed and a screw shaft 143. The actuator main body 141 has the same structure as any of the actuators 10, 11 and 12 of Examples 1 to 5, and a nut unit, an electric motor and the like are attached to the substrate. The power cable that supplies the current to the electric motor of the actuator body 141 is not shown. As the mounting parts, a door mounting plate 146 and a screw shaft mounting member 147 for mounting the screw shaft 143 to one of the doors 151a are used.

The slide-type switchgear shown in FIG. 13 having such a configuration is attached to the door 151a by the following procedure. First, as shown in FIG. 13, the main body cover 142 is fixed to the upper part of the doorway 150 by screwing or the like. Next, the door mounting plate 146 is fixed to the left door 151a located on the front side. Then, the screw shaft mounting member 147 is attached to the tip of the screw shaft 143 and fixed to the door mounting plate 146.

With respect to the actuator main body 141 fixed to the upper part of the doorway 150 in this way, the screw shaft 143 can be integrally moved with the left side door 151a to open and close the door 151a. That is, when electric power is supplied from a power cable (not shown) to rotate the electric motor of the actuator main body 141, the screw shaft 143 slides with respect to the actuator main body 141. As a result, the left door 151a to which the tip of the screw shaft 143 is attached also slides left and right to open and close.

As described above, the slide-type switchgear according to the seventh embodiment can be retrofitted to the manual doors 151a and 151b to form an electric door. Further, as described in the first embodiment, the electric motor of the actuator main body 141 has a built-in electromagnetic clutch. The electromagnetic clutch can freely switch between a state in which the rotating shaft of the motor and the nut are connected and a state in which the nut is not connected. By switching the electromagnetic clutch to the unconnected state, the door 151a can be manually opened and closed by putting a hand on the door handle 153a as in the conventional case.

Here, the actuator unit 140 has a configuration in which the screw shaft 143 linearly moves with respect to the fixed actuator main body 141. Therefore, the door 151a can be moved over the entire length of the screw shaft 143, and a sufficient stroke can be obtained. Further, the nut of the actuator body 141 adopts a non-circulation type ball screw structure in which the ball does not circulate. Therefore, the load capacity is large in the direction perpendicular to the axial direction of the screw shaft 143, that is, in the vertical direction in FIG. 13, and the door 151a can be opened and closed smoothly.

In this way, the slide-type switchgear configured mainly on the actuator unit 140 according to the seventh embodiment has a long slidable stroke and can open and close even a heavy opening / closing object at a set speed. It will be a sliding opening and closing device.

Although the embodiments and examples of the present invention have been described above, the present invention is not limited to the above embodiments and examples.

The present invention allows for various embodiments and modifications without departing from the broad spirit and scope of the present invention. The above-described embodiments and examples are for explaining the present invention, and do not limit the scope of the present invention.

The actuator of the present invention has a long stroke and a large load capacity, can be positioned with high accuracy by a ball screw mechanism, and can be applied to various applications such as a sliding automatic door, a sliding length measuring device, and an unmanned cleaning device for high places. Is.

10, 11, 12 Actuators 20, 70, 90, 121, 141 Nut units 21, 71 Unit housings 21a, 22a, 23a Through holes 21b Screw holes 21c Mounting holes 22, 23, 72, 73 Unit end covers 22b, 23b Screws Through holes 24, 25 Bearings 24a, 25a Inner ring inner surfaces 30, 80, 100, 123, 143 Screw shafts 31, 81, 101 Spiral thread grooves 31a, 81a, 101a First thread grooves 31b, 81b, 101b Second threads Grooves 31c, 81c, 101c 3rd screw groove 31d, 81d, 101d 4th screw groove 32, 102 Ball 35 Ball screw side pulley 36 Belt 37 Motor side pulley 40 Motor unit 41 Motor body 45 Clutch part 47 Motor shaft 48 Encoder 50 Board unit 51 Board body 51a Screw through hole 51b Mounting slot 60, 90 Nut 61, 66, 91 Nut cover 61a Screw through hole 62, 82 Sleeve 62a, 64a Through hole 63 Flange 64 1st sleeve 65, 67 2nd Sleeve 65, 67a Recess 67b Void 67c Contact part 91a Nut cover Large diameter part 91b Nut cover Small diameter part 91c, 91f Screw through hole 91d, 91e Screw hole 93 Fixed side sleeve 94 Movable side sleeve 94a Screw hole 95 Fixed side flange part 95a Screw Through hole 95b Counterbore 104 Color 99B Movable side stopper 100 Motor type actuator 101 Motor case 102 Bearing 103 Ball screw shaft 104 Spiral screw groove 106 Fixed block 110 Window (slide target)
111 Window frame 111A Window frame upper surface 112A, 112B Window sash 113A, 113B Window glass 114a Window glass mounting plate 114b, 147 Screw shaft mounting member 114c Flexible joint 120, 140 Sliding opening / closing device 122, 142 Device body case (fixing means)
146 Door mounting plate 150 Door frame 151a, 151b Door (for sliding)
152a, 152b Door window glass 153a, 153b Door handle

Claims (11)

A screw shaft with a spiral thread groove on the outer peripheral surface,
A plurality of balls fitted in the thread groove and
A nut for accommodating the plurality of balls and
An actuator having a rotational force transmitting means for transmitting a rotational force to the nut.
The nut is a through hole in which the plurality of balls are housed one by one, and the opening diameter on the inner surface side is smaller than the diameter of the ball and the opening diameter on the outer surface side is equal to or larger than the diameter of the ball. A first tubular member provided with a ball and a second tubular member mounted on the outside of the first tubular member and holding the ball contained in the through hole so as not to come out. ,
An actuator characterized in that the screw shaft and the nut move relative to each other along the axial direction of the screw shaft by transmitting the rotational force to the nut by the rotational force transmitting means. The thickness of the tubular wall portion of the first tubular member is thinner than the diameter of the ball, and the inner surface of the second tubular member is provided with a recess that contacts a portion of the ball that protrudes outward from the through hole. The actuator according to claim 1. The actuator according to claim 2, wherein the concave portion has a substantially conical shape. The actuator according to any one of claims 1 to 3, wherein the opening diameter on the inner surface side of the through hole is within the range of 75% or more and 95% or less of the diameter of the ball. The actuator according to any one of claims 1 to 4, wherein a portion of the ball in the range of 15% or more and 40% or less of the diameter protrudes from the opening on the inner surface side of the through hole. The method according to any one of claims 1 to 5, wherein a plurality of the screw grooves are provided on the screw shaft, and six or more balls are arranged per circumference of the inner surface of the first tubular member. Actuator. The actuator according to any one of claims 1 to 6, wherein the pitch of the screw groove changes along the axial direction of the screw shaft. The claim having a clutch mechanism for switching between a state in which a rotational force is transmitted to the nut, a state in which the rotational force is not transmitted to the nut, and a state in which the rotational force is transmitted to the nut in the reverse direction. The actuator according to any one of Items 1 to 7. A slide-type switchgear comprising the actuator according to any one of claims 1 to 8 as a driving means. The slide-type switchgear according to claim 9, further comprising a nut fixing means for fixing the nut of the actuator in the vicinity of a sliding target and a screw shaft mounting means for attaching the screw shaft to the sliding target. The slide-type switchgear according to claim 9, further comprising a screw shaft fixing means for fixing the screw shaft of the actuator in the vicinity of a sliding target and a nut attaching means for attaching the nut to the sliding target.

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