JP7545853B2 - Nut Assembly and Drive Unit - Google Patents

Description

The present invention relates to a drive device that moves a driven member in a linear direction and a nut assembly that is a part of the drive device, and to a technology that makes it easy to assemble the nut portion and the elastic member to the lead screw.

A drive device is known that converts the rotational force of a motor into linear motion and moves a driven member in a linear direction (see, for example, Patent Document 1). In this drive device, a lead screw 2 is inserted into a first nut portion 31 and a second nut portion 32 that support the movable member, and a coil spring 350 is disposed between the nut portions 31, 32 (Figure 15). In such a drive device, the coil spring 350 biases the nut portions 31, 32 in directions that move them away from each other, eliminating backlash between the nut portions 31, 32 and the lead screw 2.

In the drive device described in Patent Document 1, when the first nut portion 31 and the second nut portion 32 are attached to the movable member, the second support plate portion 617 is disposed between the first nut portion 31 and the coil spring 350, compressing the coil spring 350. In order to obtain this configuration, as shown in FIG. 18, Patent Document 1 sandwiches a jig 200 having the same thickness as the second support plate portion 617 or a slightly thicker thickness, and by pushing the second support plate portion 617 toward the jig 200, the second support plate portion 617 is inserted between the first nut portion 31 and the coil spring 350, and the jig 200, which is movable in a direction perpendicular to the axis of the lead screw 2, is released from the lead screw 2.

WO2018/084312 publication

However, the technology described in Patent Document 1 has a problem in that the process of assembling the first nut portion 31, the second nut portion 32, and the coil spring 350 with the slider is inefficient, resulting in increased manufacturing costs. In addition, the technology described in Patent Document 1 guides the slider with a single guide shaft. This makes the slider's posture unstable.

In this context, the present invention provides a drive device that allows two nut portions and a spring to be easily assembled to a slider.

The present invention provides a nut assembly that is inserted into a lead screw and engages with a slider that is movable in the axial direction of the lead screw, the nut assembly comprising a pair of nut portions spaced apart from each other in the axial direction, and an elastic member disposed between the nut portions , the pair of nut portions being movable toward and away from each other in the axial direction,
This is a nut assembly in which one of the pair of nut portions has an engaging portion and the other of the pair of nut portions has an engaged portion, the engaging portion and the engaged portion face each other in the axial direction via a gap, and when the other nut portion moves away from the one nut portion, the engaged portion and the engaging portion engage with each other.

The present invention also provides a drive device comprising a lead screw, a slider movable in the axial direction of the lead screw, and a nut assembly inserted into the lead screw and engaging with the slider in the axial direction, the nut assembly comprising a pair of nut portions spaced apart from each other in the axial direction and an elastic member arranged between the nut portions , the pair of nut portions being capable of approaching and separating from each other in the axial direction, one of the pair of nut portions comprising an engaging portion and the other of the pair of nut portions comprising an engaged portion, the engaging portion and the engaged portion facing each other via a gap in the axial direction, and when the other nut portion is separated from the one nut portion, the engaged portion and the engaging portion engage with each other.

According to the present invention, the nut assembly is provided with a nut portion and an elastic member, so that the nut assembly can be engaged with the slider, one nut portion can be brought close to the other nut portion to compress the elastic member, and in this state the lead screw can be inserted into the nut portion. This causes the elastic member to return to its original elastic state, eliminating backlash between the nut portion and the lead screw. In this way, the series of operations for assembling the two nut portions and the spring to the slider can be performed manually without using jigs or special tools, making the operation simple and easy to perform.

It is desirable for the elastic member to be compressed against the nut portion when the nut assembly is in place. This fixes the positions of the nut portion and the elastic member, making it easier to handle the nut assembly.

It is preferable to provide the nut parts with a guide part that holds the nut parts so that they can approach and separate from each other. In such a configuration, the guide part makes it difficult for the nut parts to separate from each other, further improving workability. In the present invention, the nut parts are provided with an engagement part that prevents them from separating beyond a predetermined distance. In such a configuration, the nut parts can be held in a state in which the elastic member is compressed.

It is also preferable to provide the nut with a stopper that prevents it from approaching any closer than a certain amount. This allows the worker to apply a certain preload to the elastic member by moving the nut until it is stopped by the stopper, without compressing the elastic member to its limit. In other words, such an operation can be the standard work method.

It is preferable to provide a nut-side engaging portion on one of the slider sides of the nut portion, and provide a slider-side engaging portion on the slider that engages with the nut-side engaging portion in the axial direction. With such a simple configuration, the nut assembly can be engaged with the slider. Specifically, a convex portion that protrudes toward the slider side can be provided on one of the nut portions, and a concave portion into which the convex portion fits can be provided on the slider. It is also possible to provide a convex portion that protrudes toward the nut portion on the slider, and a concave portion into which the convex portion fits on one of the nut portions.

It is preferable that the slider and nut are made of the same resin material. This prevents rattling caused by differences in the thermal expansion coefficients of the slider and nut. Examples of resin materials that can be used include POM (polyacetal), PPS (polyphenylene sulfide), PBT (polybutylene terephthalate), PA (polyamide), and PEEK (polyether ether ketone). A configuration in which the slider and nut are made of POM is preferable because it has excellent sliding properties and is inexpensive. Alternatively, when considering an environment with a large load and high environmental temperature, a configuration in which the slider and nut are made of PPS is preferable.

Alternatively, the slider and the nut can be made of different resin materials. For example, one of the slider and the nut can be made of PPS, and the other can be made of PBT. Also, one of the slider and the nut can be made of PEEK, and the other can be made of PPS. Although these resins have different thermal expansion coefficients, depending on the operating environment temperature and the fitting size, the amount of play that occurs is only slightly different from the amount of play that occurs when the nut and the slider are made of the same resin, so that the combination of such resins can also suppress the play. The type of resin is appropriately used depending on the operating conditions. The resins exemplified above have a linear expansion coefficient of 1 to 3 x 10 ^-5 /°C, so if the fitting size is, for example, 1 mm and the environmental temperature rises by 75°C, the amount of play that occurs is small, at 0.75 to 2.25 μm.

The pair of nut parts can be made to have the same shape. This allows them to be injection molded using the same mold, which reduces the number of types of molds required and simplifies the manufacturing process for the nut parts, thereby reducing manufacturing costs.

The slider can be configured to move in the axial direction by having legs through which a guide shaft extending in the axial direction of the lead screw passes. The configuration for passing the guide shaft can be such that a through hole is formed in the leg or a groove is formed on the side of the leg.

Another feature of the present invention is a drive device comprising: a lead screw; a slider movable in the axial direction of the lead screw; and a nut portion inserted into the lead screw and engaging with the slider in the axial direction, wherein the slider has at least a pair of holes formed therein through which a guide shaft extending in the axial direction of the lead screw is inserted, and the cross-sectional shapes of the holes perpendicular to the axial direction are different from each other, and the pair of nut portions can approach and separate from each other in the axial direction, one of the pair of nut portions has an engaging portion and the other of the pair of nut portions has an engaged portion, the engaging portion and the engaged portion face each other via a gap in the axial direction, and when the other nut portion moves away from the one nut portion, the engaged portion and the engaging portion engage with each other .

In such a drive unit, by fitting a guide shaft into one hole and inserting another guide shaft into the other hole with a gap, it is possible to suppress friction with the holes caused by assembly accuracy of the guide shaft. For example, by making the cross-sectional shape of one hole a perfect circle and the cross-sectional shape of the other hole an ellipse that is long in the horizontal direction, the positional accuracy of the slide is ensured by the perfect circular hole and guide shaft, and the vertical tilt of the slide is regulated by the elliptical hole and guide shaft.

Another feature of the present invention is a drive device comprising a lead screw, a slider that can move in the axial direction of the lead screw, and a nut portion that is inserted into the lead screw and engages with the slider in the axial direction, the slider having legs that extend in the axial direction, and a sliding portion provided on the bottom surface of the legs that makes point contact or line contact along the axial direction with the running surface of a frame on which the slider is placed.

In such a drive device, the slider is supported on the running surface of the frame by the sliding part, so the guide shaft can be omitted or its number can be reduced. And because the sliding part makes point contact or line contact along the axial direction with the running surface of the frame, frictional resistance with the running surface is small, allowing the slider to move smoothly. Here, "point contact" refers to the case where the diameter of the part of the sliding part that comes into contact with the running surface is 5 mm or less. Also, "line contact" refers to the case where the width of the part that comes into contact with the running surface is 5 mm or less.

The present invention has the advantage that the two nuts and the spring can be easily attached to the slider.

FIG. 2 is a perspective view showing the drive device of the first embodiment. FIG. 2 is a top view of the drive device according to the first embodiment. FIG. 2 is a front view of the drive device according to the first embodiment. FIG. 2 is a side cross-sectional view of the drive device of the first embodiment. FIG. 2 is a side view of the drive device according to the first embodiment. 1A is a cross-sectional view taken along line A-A in FIG. 1B, showing the state in which the nut assembly is attached to the slider; FIG. 1B is a front view of FIG. 1A; and FIG. 1C is a cross-sectional view showing the state immediately before the nut assembly is attached to the slider and the lead screw is inserted. 5A is a perspective view of the slider in the first embodiment, FIG. 5B is a rear view thereof, and FIG. 5C is a rear view showing a modified example. 8A is a rear view showing the slider in the modified example of FIG. 7, FIG. 8B is the modified example, and FIG. 8C is another modified example. 1A is a perspective view showing a nut assembly in a first embodiment, FIG. 1B is a top view thereof, FIG. 1C is a side view thereof, and FIG. 4A is a perspective view showing the second nut portion in the first embodiment, FIG. 4B is a perspective view showing the first nut portion, and FIG. 4C is a perspective view showing the second nut portion from a different direction. 1A is a rear view showing a slider in a second embodiment of the present invention, FIG. 1B is a modified example thereof, and FIG.

1. First embodiment (1) Overall configuration The overall configuration of a drive device 100 according to a first embodiment of the present invention will be described with reference to Figures 1 to 8. Note that in Figure 1 and other figures, arrows of orthogonal X-axis, Y-axis, and Z-axis are shown to indicate directions. In the following description, the direction in which the arrows point is the positive direction, and the opposite direction is the negative direction.

Figure 1 shows a driving device 100 according to a first embodiment of the present invention. The driving device 100 moves a driven member (not shown) linearly in the Y-axis direction. The driving device 100 has a base plate 101 that serves as a skeleton. The base plate 101 is fixed to an object to which the driving device 100 is fixed by fastening members (screws or other known fastening means). The base plate 101 is made of a metal plate. There are no particular limitations on the material of the base plate 101, so long as it is easy to process and sufficient strength can be ensured.

The end of the base plate 101 on the positive side in the Y-axis direction and the end on the non-positive side in the Y-axis direction are bent upward (in the positive direction of the Z-axis) in FIG. 1, and a front frame 101a and a rear frame 101b are formed integrally with the base plate 101. One end of the lead screw 102, which is the drive shaft, is rotatably supported by a bearing 105 on the front frame 101a. The lead screw 102 is a cylindrical member with a male thread 102a formed on the outer periphery. The lead screw 102 rotatably passes through the rear frame 101b, and its tip is rotatably supported via a bearing 106 on a motor frame 110 made of resin of the motor 107 described later.

In addition, cylindrical guide shafts 103, 104 are fixed to the front frame 101a and the rear frame 101b. The guide shafts 103, 104 function as guides that regulate the movement of the slider 120 (described below) in the axial direction of the lead screw 102.

A motor 107 is fixed to the rear frame 101b. The motor 107 is a claw-pole type PM stepping motor, but the type is not limited thereto. The motor 107 is fixed to a plate 108, which is fixed to the rear frame 101b by welding. The plate 108 can also be attached to the rear frame 101b with bolts and nuts. A lead screw 102 is fixed to the axial center of the rotor 109 of the motor 107. With this structure, when the rotor 109 of the motor 107 rotates, the lead screw 102 rotates.

A nut assembly 200, which includes a front nut portion 220 and a rear nut portion 240 (see FIG. 6) with internally formed female threads, is engaged with the male thread 102a of the lead screw 102. The lead screw 102, the front nut portion 220, and the rear nut portion 240 are engaged with each other in a manner similar to that of a normal bolt and nut. The configuration of the nut assembly 200 will be described in detail later.

The nut assembly 200 is engaged with a slider 120 that moves together with the nut assembly 200 in the axial direction of the lead screw. Figure 7 is a diagram showing the details of the slider. The slider 120 is made of resin and has legs 121 and 122 that are spaced apart in the axial direction of the lead screw. The legs 121 and 122 are formed in pairs on the negative side and the positive side of the Y direction in Figure 1, and a through hole 120a is formed in the leg 121, and a through hole 120b is formed in the leg 122. The cross-sectional shape of the through hole 120a is a perfect circle, and the cross-sectional shape of the through hole 120b is an ellipse that is long in the X-axis direction. The guide shaft 103 is slidably fitted into the through hole 120a, and the guide shaft 104 slidably passes through the through hole 120b with a gap in the X-axis direction.

As shown in FIG. 7(C), instead of through holes 120a and 120b, grooves 120c can be formed on the side surfaces of legs 121 and 122. Leg 122 is shown in FIG. 7(C), but groove 120c is also formed in leg 121. Similarly, as shown in FIG. 8(A), through holes 120b with an elliptical cross section can be formed in leg 122 (121), and as shown in FIG. 8(B), through holes 120a with a circular cross section can be formed in leg 122 (121). Furthermore, as shown in FIG. 8(C), through holes 120d with a diamond cross section can be formed in leg 122 (121). The configuration of FIG. 8(C) can also be combined with the configurations of FIG. 8(A) and (B).

A recess 123 is formed on the inside of the slider 120 (see FIG. 4), and the nut assembly 200 is placed in the recess 123. The nut assembly 200 is rectangular when viewed from the X-axis direction relative to the slider 120, and its top surface is in contact with the slider 120 or there is a small gap between them, so that it cannot rotate relative to the slider 120.

A resin cover 130 is supported on the slider 120 in a rotatable state by an axis 134. That is, the cover 130 is supported on the slider 120 in a state in which it can swing left and right with the axis 134 as a fulcrum relative to the slider 120 when viewed from the X-axis direction. The range of this swing is small, but this swing changes the relative position of the cover 130 on the Y-axis with respect to the slider 120. That is, the cover 130 moves on the Y-axis with respect to the slider 120, although it is not a parallel movement. A space 135 is formed inside the cover 130, and a coil spring contact portion 124 is positioned extending upward (in the Z-axis direction) from the slider 120 so as to divide the space 135 in half.

The coil spring contact portion 124 is provided with a protrusion 125 that protrudes toward the negative side of the Y axis direction in FIG. 4, and the protrusion 125 is fitted inside the coil spring 126. By fitting the protrusion 125 into the coil spring 126, the coil spring 126 is positioned relative to the coil spring contact portion 124.

The tip of the coil spring 126 is in contact with the inside of the front wall portion 131 of the cover 130. A recess 136 is formed in the portion of the front wall portion 131 where the coil spring 126 is in contact. The tip of the coil spring 126 is fitted into the recess 136, thereby positioning the coil spring 126 relative to the front wall portion 131.

The cover 130 also has a rear wall portion 132. The rear wall portion 132 is provided at a position spaced apart from the front wall portion 131 on the positive side in the Y-axis direction. The gap between the rear wall portion 132 and the coil spring contact portion 124 of the slider 120 forms a holding portion 133 that holds a driven member (not shown).

The slider 120 has a columnar limit switch contact portion 127 that protrudes upward. The limit switch contact portion 127 comes into contact with the limit switch 128, electrically detecting the reference position of the slider 120 in the Y-axis direction. The limit switch 128 is fixed to a limit switch mounting base 114 that extends from the upper end of the rear frame 101b toward the cover 130.

The output terminal from the limit switch 128 and the drive signal terminal provided on the motor 107 are soldered to the connection terminal board 115. A connector that transmits the motor drive signal from the outside and the detection signal from the limit switch 128 is connected to the connection terminal board 115.

(2) Nut Assembly Figures 9 and 10 are diagrams showing details of the nut assembly 200. The nut assembly 200 includes a front nut portion (nut portion) 220 and a rear nut portion (nut portion) 240, and is configured by disposing a coil spring (elastic member) 250 between the front nut portion 220 and the rear nut portion 240 in a compressed state.

Figure 10 (B) shows the front nut part 220. The front nut part 220 is made of the same resin material as the slider 120 (e.g. POM), and reference numeral 221 in the figure indicates the nut part main body. One of the slider 120 and the front nut part 220 can be made of PPS, and the other can be made of PBT. Also, one of the slider 120 and the front nut part 220 can be made of PEEK, and the other can be made of PPS. The nut part main body 221 is rectangular, and arms 222 protruding in the Y-axis direction are formed at the four corners.

The end faces of the arms 222 function as stoppers by abutting against the end faces of the arms 242 of the rear nut part 240 described below. The inner diameter of the four arms 222 is set to be slightly larger than the outer diameter of the coil spring 250. In addition, a guide (guide part) 223 that protrudes in the Y-axis direction is formed on one side of the nut part main body 221. A slit 223a is formed in the guide 223, which extends to just before its tip, and the part beyond the slit 223a is an inclined engagement part 223b.

A female screw 224 is formed in the center of the nut body 221, penetrating in the Y-axis direction. A pair of protrusions 225 protruding in the Z-axis direction positive side are formed on one surface of the nut body 221. Meanwhile, a recess 129 into which the protrusions 225 fit is formed on the slider 120 (see FIG. 6). A groove 226 is formed between the protrusions 225. For example, when the nut assembly 200 is arranged as shown in FIG. 6, the groove 226 is formed with a claw portion (engagement portion) 227, whose surface facing the Y-axis negative side in FIG. 6 is perpendicular to the groove 226 and whose inclination is downward toward the Y-axis positive side.

Next, the rear nut part 240 will be described with reference to FIG. 10(A). The rear nut part 240 is made of the same resin (e.g. POM) as the front nut part 220 and has the same shape. One of the slider 120 and the rear nut part 240 can be made of PPS and the other can be made of PBT. Also, one of the slider 120 and the rear nut part 240 can be made of PEEK and the other can be made of PPS. In the figure, the reference numeral 241 denotes the nut part main body. The nut part main body 241 is rectangular, and arms 242 protruding in the negative Y-axis direction are formed at its four corners. The inner diameter of the four arms 242 is set slightly larger than the outer diameter of the coil spring 250. Also, a guide 243 protruding in the negative Y-axis direction is formed on one side of the nut part main body 241. The guide 243 has a slit 243a that extends to just before its tip, and the part beyond the slit 243a is an inclined engagement part 243b.

A female thread 244 is formed in the center of the nut body 241, penetrating in the Y-axis direction. A pair of protrusions 245 protruding to the negative side in the Z-axis direction are formed on one surface of the nut body 241, and a groove 246 is formed between the protrusions 245. For example, when the nut assembly 200 is arranged as shown in FIG. 6, the groove 246 is formed with a claw portion 247 whose surface facing the positive side in the Y-axis direction is perpendicular to the groove 246 and whose surface is inclined toward the negative side in the Y-axis direction.

(3) Method of assembling and attaching the nut assembly When assembling the front nut part 220 and the rear nut part 240, the coil spring 250 is sandwiched between them, and the guide 243 of the rear nut part 240 is fitted into the groove 226 of the front nut part 220, and at the same time, the guide 223 of the front nut part 220 is fitted into the groove 246 of the rear nut part 240. When the two nut parts 220, 240 are brought close to each other in this state, the engaging part 243b of the guide 243 of the rear nut part 240 rides over the claw part 227 of the front nut part 220 and engages with it, and at the same time, the engaging part 223b of the guide 223 of the front nut part 220 rides over the claw part 247 of the rear nut part 240 and engages with it, and the front nut part 220, the coil spring 250, and the rear nut part 240 become one body. In this state, the coil spring 250 is slightly compressed by the two nut parts 220, 240.

The nut assembly 200 (see FIG. 9(A)) assembled as described above is placed in the recess 123 of the slider 120, and the protrusion 225 is fitted into the recess 129 of the slider 120 (see FIG. 6(A)). Then, the nut parts 220, 240 are brought close to each other against the biasing force of the coil spring 250 (see FIG. 6(C)), and the arm part 222 of the front nut part 220 and the arm part 242 of the rear nut part 240 are brought into contact with each other. In this state, the lead screw 102 is inserted through the female thread 244 of the rear nut part 240 and the female thread 224 of the front nut part 220.

Next, when the force applied to both nut parts 220, 240 is removed, the repulsive force of the coil spring 250 urges both nut parts 220, 240 in the opposite direction of the Y axis, and the female thread 224 of the front nut part 220 is pressed against the male thread 102a of the lead screw 102, and the female thread 244 of the rear nut part 240 is pressed against the male thread 102a of the lead screw 102. This eliminates the backlash of both nut parts 220, 240 against the lead screw 102.

4, when the driven member (not shown) is not held by the holding portion 133, the gap dimension of the holding portion 133 in the Y-axis direction is smaller than the dimension of the driven member in the Y-axis direction. In this state, the coil spring 126 is compressed, and the repulsive force generated by this compression urges the cover 130 in the counterclockwise direction as viewed in FIGS.

When the driven member is pushed into the holding portion 133 from above (in the positive direction of the Z axis), the gap between the coil spring contact portion 124 and the rear wall portion 132 (the gap in the Y-axis direction of the holding portion 133) is expanded, and a force acts in the direction in which they move apart. As a result, the cover 130 rotates slightly clockwise around the axis 134 in FIG. 4. As a result, the front wall portion 131 and the coil spring contact portion 124 approach each other in the Y-axis direction, and the coil spring 126 is further compressed in the Y-axis direction. The compressed coil spring 126 generates a repulsive force that tries to move the front wall portion 131 and the coil spring contact portion 124 apart in the Y-axis direction, which generates a biasing force that tries to narrow the gap between the coil spring contact portion 124 and the rear wall portion 132, and the driven member is sandwiched between the coil spring contact portion 124 and the rear wall portion 132. In other words, the driven member is sandwiched between the coil spring contact portion 124 and the rear wall portion 132 due to the repulsive force of the coil spring 126.

(5) Operation When a drive signal is supplied to the motor 107 to rotate the motor 107, the lead screw 102 rotates. Since the nut assembly 200 cannot rotate relative to the slider 120, when the lead screw 102 rotates, a drive force is generated by the action of the screw that moves the nut assembly 200 in the Y-axis direction relative to the lead screw 102. As a result, the nut assembly 200 moves relative to the lead screw 102 along the extension direction of the axis of the lead screw 102.

For example, suppose that the rotation of the lead screw 102 causes the nut assembly 200 to move in the Y-axis direction positive side (to the right in FIG. 4) relative to the lead screw 102. In this case, the female thread 224 of the front nut part 220 is pushed by the male thread 102a of the lead screw 102 and attempts to move in the Y-axis direction positive side. Then, because the convex part 225 of the front nut part 220 is engaged with the concave part 129 of the slider 120, the slider 120 moves in the Y-axis direction positive side together with the front nut part 220.

Meanwhile, suppose that the rotation of the lead screw 102 causes the nut assembly 200 to move in the negative Y direction (to the left in FIG. 4) relative to the lead screw 102. In this case, the rear nut part 240 is pressed against the lead screw 102 in the positive Y direction by the repulsive force of the coil spring 250, so the female thread 244 of the rear nut part 240 is pushed by the male thread 102a of the lead screw 102 and tries to move in the negative Y direction. This movement is transmitted to the front nut part 220 via the coil spring 250, and the slider 120 moves in the negative Y direction together with the front nut part 220.

The repulsive force of the coil spring 250 is set to be sufficiently larger than the resistance when moving the slider 120. Therefore, when the rear nut part 240 moves to the negative side in the Y-axis direction, the coil spring 250 is not further compressed and transmits the movement of the rear nut part 240 directly to the front nut part 220. In this way, the slider 120 moves while maintaining a state without backlash between the female threads 224, 244 of the front nut part 220 and the rear nut part 240 and the male thread 102a of the lead screw 102, and the accuracy of the axial movement control of the slider 120 by the rotation of the lead screw 102 is ensured.

(6) Effects In the driving device 100 configured as above, the nut assembly 200 includes the front nut portion 220, the rear nut portion 240, and the coil spring 250. Therefore, the nut assembly 200 can be engaged with the slider 120, the rear nut portion 240 can be brought close to the front nut portion 220 to compress the coil spring 250, and in this state, the lead screw 102 can be inserted through the front nut portion 220 and the rear nut portion 240. As a result, the coil spring 250 elastically returns to its original position, thereby eliminating backlash between the front nut portion 220 and the rear nut portion 240 and the lead screw 102. In this way, the front nut portion 220, the rear nut portion 240, and the coil spring 250 are assembled to the slider 120, and a series of operations for applying a preload to the coil spring 250 can be easily performed manually without using any jigs or special tools, making the operations simple and easy to perform.

In particular, in the first embodiment, the front nut part 220 is provided with a guide 223 and a groove 226, and the rear nut part 240 is provided with a guide 243 and a groove 246. By fitting the guides 223 and 243 into the grooves 226 and 246, the nut assembly 200 is difficult to disassemble and can be handled as a single unit, further improving workability.

In addition, in the first embodiment, the front nut part 220 and the rear nut part 240 are provided with the engagement parts 223b, 243b and the claw parts 227, 247, so that the front nut part 220 and the rear nut part 240 can be held in a state in which the coil spring 250 is compressed by engaging the engagement parts 223b, 243b and the claw parts 227, 247.

Furthermore, in the above embodiment, the front nut portion 220 and the rear nut portion 240 are provided with arms 222, 242 that protrude in the axial direction, and the end faces of the arms 222, 242 function as stoppers that prevent the two from approaching each other more than a certain amount. Therefore, by moving the rear nut portion 240 until it stops at the front nut portion 220, the operator can apply a predetermined preload to the coil spring 250 without compressing it to its limit.

In addition, in the above embodiment, as shown in FIG. 7, the cross-sectional shape of the through-hole 120a of the legs 121 and 122 is a perfect circle, through which the guide shaft 103 passes in a slidable state, and the cross-sectional shape of the through-hole 120b of the legs 121 and 122 is an ellipse long in the X-axis direction, through which the guide shaft 104 passes in a slidable state. Therefore, the positional accuracy of the slide 120 in the X-axis direction is ensured by the through-hole 120a and the guide shaft 103, and the inclination of the slide 120 to the positive side in the Z-axis direction is regulated by the through-hole 120b and the guide shaft 104. Furthermore, compared to the case where the through-holes 120a and 120b are both perfect circles in cross section, it is possible to suppress the rubbing (abrasion) between the through-holes 120a and 120b of the guide shafts 103 and 104, which is caused by the assembly accuracy of the guide shafts 103 and 104.

(7) Examples of changes
i) Instead of the guide shafts 103 and 104, a guide portion having a groove, rail, or other known structure may be provided on the base plate 101, along which the slider 120 moves. A specific example of such a configuration will be described in the second embodiment below. Also, the number of guide shafts or guide portions that regulate the movement of the slider 120 may be one, or three or more.

ii) In the above embodiment, as shown in Figure 4, the driven member is configured to be elastically sandwiched between the coil spring contact portion 124 of the slider 120 and the rear wall portion 132 of the cover 130, but the support structure of the driven member is not limited to such a configuration and is arbitrary. For example, a pair of walls spaced apart from each other in the Y-axis direction can be provided on the negative side of the Y-axis direction of the slider 120, and the opposing surfaces of the walls can be inclined surfaces that widen toward the positive side of the Z-axis direction, allowing the driven member to be inserted therein.

2. Second embodiment Fig. 11(A) is a diagram showing a second embodiment of the present invention. In the following description, the same reference numerals are used for the same members as those in the first embodiment, and the description thereof will be omitted. In the second embodiment, the slider 120 is changed, and the other components are the same as those in the first embodiment.

A through hole 102d is formed in the approximate center of the slider 120, and a guide shaft (not shown) is inserted through the through hole 102d. The lower end of the rear leg 122 is formed in a hemispherical shape, and its lower end serves as a sliding part 122a. Although not shown in the figure, the lower end of the front leg 121 is also formed in a hemispherical shape, and its lower end serves as a sliding part.

The sliding parts 122a of the legs 121 and 122 are placed on the base plate 101 and slide on the upper surface of the base plate 101 as the running surface. Since the sliding part 122a is a point on the surface of a sphere, it makes point contact with the running surface. In order to improve the wear resistance of the sliding part 122a, the sliding part 122a is made of a hard resin such as PPS. In addition, it is desirable to reduce frictional resistance of the running surface of the base plate 101 by, for example, mirror-finishing the metal surface.

In a drive device using the slider 120 of the above configuration, the slider 120 is supported on the running surface of the base plate 101 by the sliding part 122a, so the number of guide shafts can be reduced to one. And because the sliding part 122a makes point contact with the running surface, frictional resistance with the running surface is small, allowing the slider 120 to move smoothly.

Figure 11 (B) shows a modified example of the above embodiment. The slider 120 shown in this figure has the lower end of the leg 122 with a triangular cross section. As a result, the sliding part 122b is linear along the Y-axis direction and makes line contact with the running surface. The front leg 121 is similarly configured. A drive device using such a slider 120 also achieves the same effects and advantages as the second embodiment. The lower end of the leg 122 can also be triangular pyramid, square pyramid, or cone-shaped to make point contact with the running surface.

Figure 11 (C) shows yet another modified example. The slider 120 shown in this figure has the lower end of the leg 122 with a cross section shaped like two arcs joined together. This makes the sliding part 122c linear along the Y-axis direction and makes linear contact with the running surface. The front leg 121 is similarly configured. A drive device using such a slider 120 not only achieves the same effects and functions as the second embodiment, but also has the advantage that the sharp edge of the sliding part 122c is maintained for a longer period of time.

In addition, the claims state an invention related to a drive device, but the specification also states the following invention, which is therefore appended below.
[Additional Notes]

<Invention 1>
A nut assembly that is inserted into a lead screw and engages with a slider that is movable in an axial direction of the lead screw,
A pair of nut portions spaced apart from each other in the axial direction;
An elastic member disposed between the nut portions;
A nut assembly equipped with

<Invention 2>
2. The nut assembly according to claim 1, wherein the elastic member is compressed by the nut portion.

<Invention 3>
3. A nut assembly according to claim 1, wherein the nut portions are provided with guide portions that hold the nut portions so that the nut portions can move toward and away from each other.

<Invention 4>
4. A nut assembly according to any one of claims 1 to 3, wherein the nut portions are provided with engagement portions that prevent the nut portions from being separated from each other by more than a predetermined distance.

<Invention 5>
A nut assembly according to any one of claims 1 to 4, wherein the nut portions are provided with stopper portions for preventing the nut portions from approaching each other more than a predetermined distance.

<Invention 6>
A nut assembly according to any one of claims 1 to 5, wherein a nut-side engaging portion is provided on the slider side of either of the nut portions, and a slider-side engaging portion that engages with the nut-side engaging portion is provided on the slider.

<Invention 7>
A nut assembly according to any one of claims 1 to 6, wherein a convex portion protruding toward the slider is provided on any one of the nut portions, and a concave portion into which the convex portion fits is provided on the slider.

<Invention 8>
The nut assembly according to any one of claims 1 to 7, wherein the slider and the nut portion are molded from the same resin material.

<Invention 9>
9. The nut assembly according to claim 8, wherein the resin material is polyacetal.

<Invention 10>
The nut assembly according to any one of claims 1 to 7, wherein the slider and the nut portion are molded from different resin materials.

<Invention 11>
A nut assembly according to claim 10, wherein the slider is made of polyacetal and the nut portion is made of polyphenylene sulfide.

<Invention 12>
12. The nut assembly according to any one of claims 1 to 11, wherein the pair of nut portions have the same shape.

<Invention 13>
A nut assembly as described in any one of Inventions 1 to 12, wherein the slider has at least a pair of holes through which a guide shaft extending in the axial direction of the lead screw is inserted, and the cross-sectional shapes of the holes perpendicular to the axial direction are different from each other.

<Invention 14>
A nut assembly according to claim 13, wherein the cross-sectional shape of one of the holes is a perfect circle and the cross-sectional shape of the other hole is an ellipse that is long in the horizontal direction.

<Invention 15>
15. A nut assembly according to any one of claims 1 to 14, wherein the slider has a leg portion through which a guide shaft extending in the axial direction passes.

<Invention 16>
A nut assembly as described in invention 15, wherein a sliding portion is provided on the bottom surface of the leg portion, which makes point contact or line contact along the axial direction with the running surface of a frame on which the slider is placed.

<Invention 17>
A lead screw and
a slider movable in an axial direction of the lead screw;
a nut assembly that is inserted onto the lead screw and engages with the slider;
Equipped with
The nut assembly includes:
A pair of nut portions spaced apart from each other in the axial direction;
An elastic member disposed between the nut portions;
A drive unit comprising:

<Invention 18>
18. The drive device according to claim 17, wherein the elastic member is compressed by the nut portion.

<Invention 19>
19. A drive device according to invention 17 or 18, wherein the nut portions are provided with guide portions for holding the nut portions so that the nut portions can move toward and away from each other.

<Invention 20>
20. A drive device according to any one of inventions 17 to 19, wherein the nut portions are provided with engagement portions that prevent the nut portions from moving apart from each other by more than a predetermined distance.

<Invention 21>
21. A drive device according to any one of inventions 17 to 20, wherein the nut portions are provided with stopper portions for preventing the nut portions from approaching each other more than a predetermined distance.

<Invention 22>
22. A drive device according to any one of inventions 17 to 21, wherein a nut-side engaging portion is provided on the slider side of either of the nut portions, and a slider-side engaging portion that engages with the nut-side engaging portion is provided on the slider.

<Invention 23>
23. The drive device according to any one of inventions 17 to 22, wherein a convex portion protruding towards the slider is provided on any one of the nut portions, and a concave portion into which the convex portion fits is provided on the slider.

<Invention 24>
24. The drive unit according to any one of claims 17 to 23, wherein the slider and the nut portion are molded from the same resin material.

<Invention 25>
25. The drive device according to claim 24, wherein the resin material is polyacetal.

<Invention 26>
24. The drive unit according to any one of claims 17 to 23, wherein the slider and the nut portion are molded from different resin materials.

<Invention 27>
27. A drive device according to claim 26, wherein the slider is made of polyacetal and the nut portion is made of polyphenylene sulfide.

<Invention 28>
28. The drive device according to any one of claims 17 to 27, wherein the pair of nut portions have the same shape.

<Invention 29>
A drive device as described in any one of inventions 17 to 28, wherein the slider has at least a pair of holes through which a guide shaft extending in the axial direction of the lead screw is inserted, and the cross-sectional shapes of the holes perpendicular to the axial direction are different from each other.

<Invention 30>
30. A drive device according to claim 29, wherein the cross-sectional shape of one of the holes is a perfect circle and the cross-sectional shape of the other of the holes is an ellipse that is long in the horizontal direction.

<Invention 31>
31. The drive device according to any one of claims 17 to 30, wherein the slider has legs through which a guide shaft extending in the axial direction passes.

<Invention 32>
A drive device according to invention 31, wherein a sliding portion is provided on the bottom surface of the leg portion, which makes point contact or line contact along the axial direction with a running surface of a frame on which the slider is placed.

<Invention 33>
A lead screw and
a slider movable in an axial direction of the lead screw;
a nut portion that is inserted onto the lead screw and engages with the slider;
Equipped with
The slider is formed with at least a pair of holes through which a guide shaft extending in the axial direction of the lead screw is inserted,
A drive device in which the holes have different cross-sectional shapes perpendicular to the axial direction.

<Invention 34>
A drive device according to invention 33, wherein the cross-sectional shape of one of the holes is a perfect circle and the cross-sectional shape of the other of the holes is an ellipse that is long in the horizontal direction.

<Invention 35>
A drive device according to invention 33 or 34, wherein a nut assembly is constituted by a pair of the nut portions spaced apart from each other in the axial direction and an elastic member disposed between the nut portions.

<Invention 36>
36. The drive device according to claim 35, wherein the elastic member is compressed by the nut portion.

<Invention 37>
A drive device according to invention 35 or 36, wherein the nut portions are provided with guide portions for holding the nut portions so that the nut portions can move toward and away from each other.

<Invention 38>
38. A drive device according to any one of inventions 35 to 37, wherein the nut portion is provided with an engagement portion that prevents the nut portion from separating from the nut portion by more than a predetermined distance.

<Invention 39>
39. The drive device according to any one of inventions 35 to 38, wherein the nut portion is provided with a stopper portion for preventing the nut portion from approaching beyond a predetermined distance.

<Invention 40>
A drive device according to any one of inventions 33 to 39, wherein a nut-side engaging portion is provided on the slider side of either of the nut portions, and a slider-side engaging portion that engages with the nut-side engaging portion is provided on the slider.

<Invention 41>
41. The drive device according to any one of inventions 33 to 40, wherein a convex portion protruding towards the slider is provided on any one of the nut portions, and a concave portion into which the convex portion fits is provided on the slider.

<Invention 42>
42. The drive unit according to any one of inventions 33 to 41, wherein the slider and the nut portion are molded from the same resin material.

<Invention 43>
43. The drive device according to claim 42, wherein the resin material is polyacetal.

<Invention 44>
42. The drive unit according to any one of inventions 33 to 41, wherein the slider and the nut portion are molded from different resin materials.

<Invention 45>
45. The drive device according to claim 44, wherein the slider is made of polyacetal and the nut portion is made of polyphenylene sulfide.

<Invention 46>
The drive device according to any one of inventions 33 to 45, wherein the pair of nut portions have the same shape.

<Invention 47>
47. The drive device according to any one of claims 33 to 46, wherein the at least one pair of holes are formed in legs provided on the slider.

<Invention 48>
48. A moving device according to any one of inventions 33 to 47, wherein a sliding portion is provided on the bottom surface of the leg portion, which makes point contact or line contact along the axial direction with the running surface of a frame on which the slider is placed.

<Invention 49>
A lead screw and
a slider movable in an axial direction of the lead screw;
a nut portion that is inserted onto the lead screw and engages with the slider;
Equipped with
The slider has a leg portion through which a guide shaft extending in an axial direction passes,
A drive device in which a sliding portion is provided on the bottom surface of the leg portion, which makes point contact or line contact along the axial direction with the running surface of a frame on which the slider is placed.

<Invention 50>
A drive device according to Invention 49, wherein a nut assembly is constituted by a pair of the nut portions spaced apart from each other in the axial direction and an elastic member disposed between the nut portions.

<Invention 51>
51. The drive device according to claim 50, wherein the elastic member is compressed by the nut portion.

<Invention 52>
52. A drive device according to invention 50 or 51, wherein the nut portions are provided with guide portions for holding the nut portions so that the nut portions can move toward and away from each other.

<Invention 53>
53. A drive device according to any one of inventions 50 to 52, wherein the nut portion is provided with an engagement portion that prevents the nut portion from separating from the nut portion by more than a predetermined distance.

<Invention 54>
54. A drive device according to any one of inventions 50 to 53, wherein the nut portion is provided with a stopper portion for preventing the nut portion from approaching beyond a predetermined distance.

<Invention 55>
55. A drive device according to any one of inventions 50 to 54, wherein a nut-side engaging portion is provided on the slider side of either of the nut portions, and a slider-side engaging portion that engages with the nut-side engaging portion is provided on the slider side.

<Invention 56>
56. A drive device according to any one of inventions 50 to 55, wherein a convex portion protruding towards the slider is provided on any one of the nut portions, and a concave portion into which the convex portion fits is provided on the slider.

<Invention 57>
57. The drive device according to any one of inventions 49 to 56, wherein the slider and the nut portion are molded from the same resin material.

<Invention 58>
58. The drive mechanism according to claim 57, wherein the resin material is polyacetal.

<Invention 59>
57. The drive device according to any one of inventions 49 to 56, wherein the slider and the nut portion are molded from different resin materials.

<Invention 60>
60. A drive device according to claim 59, wherein the slider is made of polyacetal and the nut portion is made of polyphenylene sulfide.

<Invention 61>
61. The drive device according to any one of Inventions 49 to 60, wherein the pair of nut portions have the same shape.

<Invention 62>
A drive device described in any of inventions 49 to 61, wherein the slider has at least a pair of holes through which a guide shaft extending in the axial direction of the lead screw is inserted, and the cross-sectional shapes of the holes perpendicular to the axial direction are different from each other.

<Invention 63>
A drive device according to Invention 62, wherein the cross-sectional shape of one of the holes is a perfect circle and the cross-sectional shape of the other of the holes is an ellipse that is long in the horizontal direction.

100 ... drive device, 101 ... base plate 101a ... front frame, 101b ... rear frame, 102 ... lead screw, 102a ... male screw, 103 ... guide shaft, 104 ... guide shaft, 105 ... bearing, 106 ... bearing, 107 ... motor, 108 ... plate, 109 ... rotor, 110 ... motor frame, 111 ... nut, 112 ... nut, 113 ... coil spring, 114 ... limit switch mounting base, 120 ... slider, 120a, 120b, 120d ... through hole, 120c ... groove, 121 ... leg, 122 ... leg, 122a, 122b, 122c ... sliding portion, 123 ... recess, 124 ... coil spring contact portion, 125 ... convex portion, 126 ... coil spring, 127 ... limit switch contact portion, 128...limit switch, 129...recess, 130...cover, 131...front wall portion, 132...rear wall portion, 133...retaining portion, 134...shaft, 135...space, 136...recess, 200...nut assembly, 220...front nut portion (nut portion), 221...nut portion main body, 222...arm portion, 223...guide (guide portion), 223a...slit, 223b...engagement portion, 224...female thread, 225...convex portion, 226...groove, 227...claw portion (engagement portion), 240...rear nut portion (nut portion), 241...nut portion main body, 242...arm portion, 243...guide, 243a...slit, 243b...engagement portion, 244...female thread, 245...convex portion, 246...groove, 247...claw portion (engagement portion), 250...coil spring (elastic member).

Claims (20)

A nut assembly that is inserted into a lead screw and engages with a slider that is movable in an axial direction of the lead screw,
A pair of nut portions spaced apart from each other in the axial direction;
An elastic member disposed between the nut portions;
Equipped with
The pair of nut portions are movable toward and away from each other in the axial direction,
One of the pair of nut portions has an engagement portion,
The other nut portion of the pair of nut portions includes an engaged portion,
The engaging portion and the engaged portion face each other across a gap in the axial direction,
When the other nut portion is separated from the one nut portion, the engaged portion and the engaging portion engage with each other.
Nut assembly. The nut assembly according to claim 1, wherein the elastic member is compressed by the nut portion. The nut assembly according to claim 1 or 2, in which the nut parts are provided with a guide part that holds the nut parts so that they can move toward and away from each other. 4. The nut assembly according to claim 1, wherein the nut portions are provided with a stopper portion for preventing the nut portions from approaching each other more than a predetermined distance. 5. A nut assembly according to claim 1 , wherein a nut-side engaging portion is provided on one of the nut portions on the slider side, and a slider-side engaging portion is provided on the slider for engaging with the nut-side engaging portion. 6. The nut assembly according to claim 1, wherein a convex portion protruding toward the slider is provided on any one of the nut portions, and a concave portion into which the convex portion fits is provided on the slider. The nut assembly according to any one of claims 1 to 6 , wherein the pair of nut portions have the same shape. A lead screw and
a slider movable in an axial direction of the lead screw;
a nut assembly that is inserted onto the lead screw and engages with the slider;
Equipped with
The nut assembly includes:
A pair of nut portions spaced apart from each other in the axial direction;
An elastic member disposed between the nut portions;
Equipped with
The pair of nut portions are movable toward and away from each other in the axial direction,
One of the pair of nut portions has an engagement portion,
The other nut portion of the pair of nut portions includes an engaged portion,
The engaging portion and the engaged portion face each other across a gap in the axial direction,
When the other nut portion is separated from the one nut portion, the engaged portion and the engaging portion engage with each other.
Drive unit. The drive unit according to claim 8 , wherein the slider and the nut portion are molded from the same resin material. The drive unit according to claim 9 , wherein the resin material is polyacetal. The drive unit according to claim 9 , wherein the resin material is polyphenylene sulfide. The drive unit according to claim 8 , wherein the slider and the nut portion are molded from different resin materials. 13. The drive device according to claim 12 , wherein one of the slider and the nut portion is made of polybutylene terephthalate, and the other is made of polyphenylene sulfide. The drive device according to claim 13, wherein one of the slider and the nut portion is made of polyether ether ketone, and the other is made of polyphenylene sulfide. 15. A drive device as described in any one of claims 8 to 14, wherein the slider has a leg portion through which a guide shaft extending in the axial direction is inserted, and a sliding portion is provided on a bottom surface of the leg portion, which makes point contact or line contact along the axial direction with a running surface of a frame on which the slider is placed. A lead screw and
a slider movable in an axial direction of the lead screw;
a nut portion that is inserted through the lead screw and engages with the slider in the axial direction;
Equipped with
The slider has at least a pair of holes through which a guide shaft extending in the axial direction of the lead screw is inserted,
The cross-sectional shapes of the holes perpendicular to the axial direction are different from each other ,
The pair of nut portions are movable toward and away from each other in the axial direction,
One of the pair of nut portions has an engagement portion,
The other nut portion of the pair of nut portions includes an engaged portion,
The engaging portion and the engaged portion face each other across a gap in the axial direction,
When the other nut portion is separated from the one nut portion, the engaged portion and the engaging portion engage with each other.
Drive unit. 17. The drive unit according to claim 16 , wherein the cross-sectional shape of one of the holes is a perfect circle, and the cross-sectional shape of the other of the holes is an ellipse that is long in the horizontal direction. 18. The drive unit according to claim 16 , wherein the at least one pair of holes are formed in a leg portion of the slider. A lead screw and
a slider movable in an axial direction of the lead screw;
a nut portion that is inserted onto the lead screw and engages with the slider;
Equipped with
The slider has a leg portion through which a guide shaft extending in an axial direction passes,
A drive device in which a sliding portion is provided on the bottom surface of the leg portion, which makes point contact or line contact along the axial direction with the running surface of a frame on which the slider is placed. The engagement portion has a slit formed therein that extends in the direction of the rotation axis,
In the rotation axis direction, the tip end of the slit and the engaged portion face each other with a gap therebetween.
The nut assembly according to claim 1.

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