JP2021032559A - Applied load detection unit - Google Patents

Abstract

To easily and accurately detect the applied load of an electric actuator.SOLUTION: Each of a first load sensor 541 and a second load sensor 542 is fixed inside of a housing 520 while being loaded with a preload so as to be sandwiched in the axial direction. Each of the first load sensor 541 and the second load sensor 542 is arranged so that the detection value of the first load sensor 541 decreases while the detection value of the second load sensor 542 increases when a load is applied to a shaft body 570 toward one in the axial direction and the detection value of the second load sensor 542 decreases while the detection value of the first load sensor 541 increases when a load is applied to the shaft body 570 toward the other in the axial direction.SELECTED DRAWING: Figure 8

Description

The present invention relates to a load-bearing detection unit.

Japanese Patent Application Laid-Open No. 2014-168373 (Patent Document 1) discloses a configuration of an electric cylinder provided with a load detecting means for detecting a load in the axial direction. In the electric cylinder described in Patent Document 1, the strain detecting portion serving as the load detecting means is provided on a plate-shaped member sandwiched between the first cylinder portion and the second cylinder portion constituting the outer cylinder body. ing.

Japanese Unexamined Patent Publication No. 2014-168373

In an electric actuator such as an electric cylinder, in order to apply a load with high accuracy, it is necessary to periodically measure and calibrate the actually applied load. Therefore, it is required that the load of the electric actuator can be detected easily and accurately.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a load load detection unit capable of easily and accurately detecting the load load of an electric actuator.

The load load detection unit based on the first aspect of the present invention is a load load detection unit that is detachably attached to the tip of a linearly movable portion of the electric actuator to detect the load load of the electric actuator. The load load detection unit includes a housing, a shaft body, a first load sensor, and a second load sensor. The housing is provided with a connecting portion connected to the tip portion. The shaft body extends in the axial direction, and a part of one side in the axial direction is housed inside the housing. Each of the first load sensor and the second load sensor is annular and is arranged in the housing with the shaft body inserted. Each of the first load sensor and the second load sensor is fixed in the housing in a state where a preload is applied so as to be sandwiched in the axial direction. When a load is applied to the shaft body in one of the axial directions, the detection value of the second load sensor increases and the detection value of the first load sensor decreases, and with respect to the shaft body. The first load sensor and the second load sensor so that the detection value of the first load sensor increases and the detection value of the second load sensor decreases when a load is applied toward the other in the axial direction. Each is arranged.

In one embodiment of the present invention, the inner diameter of the housing is partially formed between the position where the first load sensor is arranged and the position where the second load sensor is arranged in the axial direction. It has a reduced diameter portion that is smaller. The shaft body has a male screw portion at a position on one side of the position of the diameter-reduced portion in the axial direction in a state where a part of the shaft body is housed in the housing, and the shaft body has a reduced diameter portion in the axial direction. At a position on the other side of the position, there is a diameter-expanded portion in which the diameter of the shaft body is partially increased. The load load detection unit further includes a locknut that is screwed with the male thread portion of the shaft body. In the housing, the first load sensor located on the one side in the axial direction with respect to the reduced diameter portion and the second load sensor located on the other side in the axial direction with respect to the reduced diameter portion are described. The first load sensor is sandwiched between the reduced diameter portion and the locknut by screwing the male threaded portion of the shaft body inserted toward the one side in the axial direction and the locknut, and the second load sensor is sandwiched between the reduced diameter portion and the locknut. The load sensor is sandwiched between the reduced diameter portion and the expanded diameter portion.

The load load detection unit based on the second aspect of the present invention is a load load detection unit that is detachably attached to the tip of a linearly movable portion of the electric actuator to detect the load load of the electric actuator. The load load detection unit includes a first housing, a second housing, a shaft body, and a load sensor. The first housing is provided with a connecting portion connected to the tip portion. The second housing is fixed to the first housing in a state where the end portion is inserted inside the first housing while being positioned coaxially with the first housing. The shaft body extends in the axial direction, and a part of one side in the axial direction is housed inside the first housing and the second housing. The load sensor is annular and is arranged in the first housing with the shaft body inserted. The load sensor is fixed in the first housing in a state where a preload is applied so as to be sandwiched in the axial direction. When a load is applied to the shaft body in one direction in the axial direction, the detection value of the load sensor increases, and a load is applied to the shaft body in the other direction in the axial direction. The load sensor is arranged so that the detected value of the load sensor increases at that time.

In one embodiment of the present invention, in the first housing, the inner diameter of the first housing is partially reduced at a position on one side in the axial direction with respect to the position where the load sensor is arranged. It has a reduced diameter portion and has a female screw portion on the inner peripheral surface of the position on the other side in the axial direction with respect to the position where the load sensor is arranged. The second housing abuts on the outer peripheral surface of the end portion that has entered the inside of the first housing, the male screw portion that is screwed with the female screw portion, and the other end surface of the first housing in the axial direction. It has a flange part. The shaft body has a male screw portion on one side of the position of the other end of the diameter-reduced portion of the first housing in the axial direction, and the diameter-reduced portion of the first housing is arranged in the axial direction. On the other side of the position, there is a diameter-expanded portion in which the diameter of the shaft body is partially increased. The load load detection unit further includes a locknut that is screwed with the male thread portion of the shaft body. In the first housing, the male screw portion of the shaft body into which the load sensor located on the other side in the axial direction with respect to the reduced diameter portion is inserted toward the one side in the axial direction, and the locknut are screwed. By fitting, the load sensor is sandwiched between the locknut and the enlarged diameter portion. By screwing the male screw portion of the second housing and the female screw portion of the first housing, the end surface of the first housing and the flange portion of the second housing come into contact with each other, and the load sensor has a reduced diameter portion. It is sandwiched between the second housing and the end portion of the second housing.

According to the present invention, the load of the electric actuator can be detected easily and accurately.

It is a partial cross-sectional view which shows the structure of the electric actuator which concerns on Embodiment 1 of this invention. It is a schematic diagram which shows the state which the load is not applied to the movable cylinder. It is a schematic diagram which shows the state which the load lower than the preload is applied to the movable cylinder. It is a schematic diagram which shows the state which the load higher than the preload is applied to the movable cylinder. It is a partial cross-sectional view which shows the structure of the electric actuator which concerns on Embodiment 2 of this invention. It is a partial cross-sectional view which shows the structure of the electric actuator which concerns on Embodiment 3 of this invention. It is a partial cross-sectional view which shows the structure of the electric actuator which concerns on Embodiment 4 of this invention. It is sectional drawing which shows the structure of the load load detection unit which concerns on Embodiment 5 of this invention. FIG. 5 is a partial cross-sectional view showing a state in which the load load detection unit according to the fifth embodiment of the present invention is attached to the electric actuator according to the first embodiment of the present invention. It is sectional drawing which shows the structure of the load load detection unit which concerns on Embodiment 6 of this invention. FIG. 5 is a partial cross-sectional view showing a state in which the load load detection unit according to the sixth embodiment of the present invention is attached to the electric actuator according to the first embodiment of the present invention.

Hereinafter, the electric actuator according to each embodiment of the present invention will be described with reference to the drawings. In the following description of the embodiment, the same or corresponding parts in the drawings are designated by the same reference numerals, and the description thereof will not be repeated.

(Embodiment 1)
FIG. 1 is a partial cross-sectional view showing the configuration of the electric actuator according to the first embodiment of the present invention. As shown in FIG. 1, the electric actuator 100 according to the first embodiment of the present invention includes a drive mechanism, a shaft body 110, a movable nut 160, a housing 120, a first bearing 131, and a second bearing 132. And a first load sensor 141 and a second load sensor 142.

The drive mechanism includes a motor 10 and a speed reduction mechanism unit 12 connected to the output shaft unit 11 of the motor 10. The speed reduction mechanism portion 12 is connected to a rotating shaft portion 115 located at one end of the shaft body 110 in the axial direction. In the present embodiment, the motor 10 and the shaft body 110 are arranged in parallel with each other, but the present invention is not limited to this, and the motor 10 and the shaft body 110 may be arranged in the same linear shape.

The shaft body 110 extends in the axial direction. The shaft body 110 is provided with a rotating shaft portion 115, a male screw portion 114, a cylindrical portion 113, a diameter-expanded portion 112, and a screw shaft portion 111 in this order from one side in the axial direction. In the enlarged diameter portion 112, the diameter of the shaft body 110 is partially increased. The screw shaft portion 111 is a portion that functions as a screw shaft of a so-called ball screw.

The nut 160 is screwed into the screw shaft portion 111 via a ball, and is movable in the axial direction relative to the shaft body 110 by driving the drive mechanism. The nut 160 is a so-called ball screw nut. In the electric actuator 100, a ball screw including a shaft body 110 and a nut 160 is configured.

A movable cylinder 170 is connected to the nut 160. The screw shaft portion 111 of the shaft body 110 is located inside the movable cylinder 170. The movable cylinder 170 can move together with the nut 160 in the axial direction relative to the shaft body 110. A tip metal fitting 171 is attached to the other end of the movable cylinder 170 in the axial direction. In the electric actuator 100 according to the present embodiment, the movable cylinder 170 and the tip fitting 171 serve as a linearly movable portion, and the tip fitting 171 serves as a tip portion of the linearly movable portion.

The housing 120 accommodates a part of the shaft body 110. In this embodiment, the housing 120 has a substantially cylindrical outer shape. The housing 120 is arranged coaxially with the shaft body 110. A cylindrical portion 113 and a diameter-expanded portion 112 of the shaft body 110 are located inside the housing 120. The housing 120 is provided with two through holes 123 extending in the radial direction of the housing 120. From one of the two through holes 123, the lead wiring connected to the first load sensor 141 is pulled out to the outside of the housing 120. From the other of the two through holes 123, the lead wiring connected to the second load sensor 142 is pulled out to the outside of the housing 120.

The housing 20 is arranged on one side of the housing 120 in the axial direction, and the outer cylinder 22 is arranged on the other side of the housing 120 in the axial direction. The housing 120 is connected to each of the housing 20 and the outer cylinder 22 in a state of being sandwiched between the housing 20 and the outer cylinder 22.

The housing 20 is connected to the motor housing of the motor 10. Inside the housing 20, the output shaft portion 11, the speed reduction mechanism portion 12, the rotating shaft portion 115 of the shaft body 110, and the male screw portion 114 are located. A base plate 21 arranged so as to face one end surface of the shaft body 110 in the axial direction is attached to the housing 20. The base plate 21 has a protruding portion protruding in the axial direction, and the protruding portion is provided with an opening 21h.

A bush 23 that closes between the outer cylinder 22 and the movable cylinder 170 is attached to the other end of the outer cylinder 22 in the axial direction. A lubricating member that is in sliding contact with the outer peripheral surface of the movable cylinder 170 is provided on the inner peripheral surface of the bush 23.

The space surrounded by the housing 20, the housing 120, the outer cylinder 22, and the bush 23 is a closed space. The two through holes 123 of the housing 120 are closed by attaching the terminal box 180 or the like to the housing 120, as will be described later.

At least a part of each of the first bearing 131 and the second bearing 132 is arranged in the housing 120 with the shaft body 110 inserted. A cylindrical portion 113 of the shaft body 110 is located inside each of the first bearing 131 and the second bearing 132. Each of the first bearing 131 and the second bearing 132 is, for example, a rolling bearing or a plain bearing. Specifically, each of the first bearing 131 and the second bearing 132 may be a tapered roller bearing.

Each of the first load sensor 141 and the second load sensor 142 is annular and is arranged in the housing 120 with the shaft body 110 inserted. A cylindrical portion 113 of the shaft body 110 is located inside each of the first load sensor 141 and the second load sensor 142. The first load sensor 141 is arranged side by side with the first bearing 131. The second load sensor 142 is arranged side by side with the second bearing 132. In the present embodiment, the first load sensor 141 is in direct contact with the first bearing 131, but may be indirectly in contact with the first bearing 131 via, for example, a washer or the like. The second load sensor 142 is in direct contact with the second bearing 132, but may be indirectly in contact with the second bearing 132, for example, via a washer or the like. Further, the shapes of the first load sensor 141 and the second load sensor 142 are not limited to the annular shape.

Each of the first load sensor 141 and the second load sensor 142 is, for example, a strain gauge type, a piezoelectric type, a magnetostrictive type, a capacitance type, a gyro type, a spring type or a sound fork type load sensor. Each of the first load sensor 141 and the second load sensor 142 may be composed of a so-called load cell.

In the housing 120, the inner diameter of the housing 120 is partially reduced between the position where the first load sensor 141 is arranged and the position where the second load sensor 142 is arranged in the axial direction. It has a reduced diameter portion 122.

Specifically, in the housing 120, the inner peripheral surface 121 surrounding the first bearing 131 and the first load sensor 141 and the inner peripheral surface 121 surrounding the second bearing 132 and the second load sensor 142. A reduced diameter portion 122 having an inner diameter smaller than that of the inner peripheral surface 121 is provided between them. Each of the first load sensor 141 and the second load sensor 142 is arranged side by side with the reduced diameter portion 122 in the axial direction.

The shaft body 110 has a male screw portion 114 at a position on one side of the position of the diameter reduction portion 122 in the axial direction in a state where the cylindrical portion 113 and the diameter expansion portion 112 of the shaft body 110 are housed in the housing 120. In addition, the diameter-expanded portion 112 is provided at a position on the opposite side of the position of the diameter-reduced portion 122 in the axial direction.

The electric actuator 100 further includes a locknut 150 that is screwed with the male threaded portion 114 of the shaft body 110. The first load sensor 141 and the first bearing 131 located on one side in the axial direction with respect to the reduced diameter portion 122, and the second load sensor 142 located on the other side in the axial direction with respect to the reduced diameter portion 122. The first load sensor 141 and the first bearing 131 are contracted by screwing the male screw portion 114 of the shaft body 110 into which the second bearing 132 is inserted toward one side in the axial direction and the locknut 150. It is sandwiched between the diameter portion 122 and the locknut 150, and the second load sensor 142 and the second bearing 132 are sandwiched between the diameter reduction portion 122 and the diameter expansion portion 112. As a result, each of the first load sensor 141 and the second load sensor 142 is fixed in the housing 120 in a state where a preload is applied so as to be sandwiched in the axial direction. That is, the preload is generated by the axial force when the locknut 150 is tightened to the male screw portion 114.

The terminal box 180 includes a main body portion 181, a lid portion 182, a packing 183, and a seal portion 184. The bottom surface of the main body 181 is in contact with the outer peripheral surface of the housing 120 via the seal 184. The housing 120 and the terminal box 180 are airtightly connected by the seal portion 184.

The bottom surface of the main body 181 is provided with openings corresponding to the two through holes 123 of the housing 120. Through the opening and the through hole 123, each of the drawer wiring connected to the first load sensor 141 and the drawer wiring connected to the second load sensor 142 is drawn into the terminal box 180.

Inside the main body 181 is provided a board stand 186 for holding a board and an amplifier stand 187 for holding an amplifier. The main body portion 181 is airtightly closed by the lid portion 182 via the packing 183.

As described above, the terminal box 180 and the like are attached to the housing 120, and the two through holes 123 of the housing 120 are closed, so that the first load sensor 141 and the second load sensor 142 are attached to the housing 120. It can be prevented from being exposed to the outside.

When the motor 10 is driven in the forward direction and the tip fitting 171 pushes the object toward the other in the axial direction, the tip fitting 171 is loaded with the load F1 toward one of the axial directions. The load F1 applied to the tip metal fitting 171 propagates to the nut 160 via the movable cylinder 170. The load F1 propagated to the nut 160 propagates to the screw shaft portion 111 of the shaft body 110 via the ball. The load F1 propagated to the shaft body 110 propagates from the enlarged diameter portion 112 of the shaft body 110 to the second load sensor 142 via the second bearing 132. As a result, the second load sensor 142 detects the load F1.

When the motor 10 reversely drives and the tip fitting 171 pulls the object toward one of the axial directions, the tip fitting 171 is loaded with the load F2 toward the other in the axial direction. The load F2 applied to the tip metal fitting 171 propagates to the nut 160 via the movable cylinder 170. The load F2 propagated to the nut 160 propagates to the screw shaft portion 111 of the shaft body 110 via the ball. The load F2 propagated to the shaft body 110 propagates from the male screw portion 114 of the shaft body 110 to the first load sensor 141 via the locknut 150 and the first bearing 131. As a result, the first load sensor 141 detects the load F2.

Here, a method of calculating the load from the detected values of the first load sensor 141 and the second load sensor 142 to which the preload is applied will be described.

FIG. 2 is a schematic view showing a state in which a load is not applied to the movable cylinder. In FIG. 2, only the configuration around the first load sensor 141 and the second load sensor 142 in the electric actuator 100 is shown, and the tip metal fitting 171 is not shown.

When no load is applied to the movable cylinder 170, only the preload F0 is applied to each of the first load sensor 141 and the second load sensor 142. In this state, the detected values of the first load sensor 141 and the second load sensor 142 are F0. For example, when the preload load F0 = 80 kg, the detected values of the first load sensor 141 and the second load sensor 142 are 80 kg, respectively.

That is, the load applied to the movable cylinder 170 can be calculated to be 80 kg-80 kg = 0 kg by subtracting the detected value of the first load sensor 141 from the detected value of the second load sensor 142.

FIG. 3 is a schematic view showing a state in which a load lower than the preload is applied to the movable cylinder. As shown in FIG. 3, when the movable cylinder 170 pushes an object with a load Fa lower than the preload, the movable cylinder 170 is loaded with the load Fa toward one of the axial directions. In this state, the first load sensor 141 is loaded with the preload load F'0, and the second load sensor 142 is loaded with the preload load F'0 and the load Fa. For example, when the preload load F0 = 80 kg and the load Fa = 20 kg, the detection value of the first load sensor 141 is 70 kg, and the detection value of the second load sensor 142 is 90 kg.

That is, the load applied to the movable cylinder 170 can be calculated to be 90 kg-70 kg = 20 kg by subtracting the detected value of the first load sensor 141 from the detected value of the second load sensor 142.

FIG. 4 is a schematic view showing a state in which a load higher than the preload is applied to the movable cylinder. As shown in FIG. 4, when the movable cylinder 170 pushes an object with a load Fb higher than the preload, the movable cylinder 170 is loaded with the load Fb in one of the axial directions. For example, when the preload load F0 = 80 kg and the load Fb = 200 kg, the detection value of the first load sensor 141 is 0 kg, and the detection value of the second load sensor 142 is 200 kg.

That is, the load applied to the movable cylinder 170 can be calculated to be 200 kg-0 kg = 200 kg by subtracting the detected value of the first load sensor 141 from the detected value of the second load sensor 142.

As described above, the load applied to the movable cylinder 170 can be calculated by subtracting the detected value of the first load sensor 141 from the detected value of the second load sensor 142. If the calculated load value is positive, the movable cylinder 170 is loaded with a load directed in one direction in the axial direction, and if the calculated load value is negative, the movable cylinder 170 is loaded with the above. A load directed to the other in the axial direction is applied.

As described above, in the electric actuator 100 according to the present embodiment, when a load is applied to the shaft body 110 in one of the axial directions, the detection value of the second load sensor 142 is increasing. 1 The detection value of the first load sensor 141 decreases while the detection value of the first load sensor 141 increases when a load is applied to the shaft body 110 toward the other side in the axial direction. Each of the first load sensor 141 and the second load sensor 142 is arranged so that the detected value of the load sensor 142 is reduced.

In the electric actuator 100 according to the first embodiment of the present invention, each of the first load sensor 141 and the second load sensor 142 is placed in the housing 120 in a state where a preload is applied so as to be sandwiched in the axial direction. It is fixed. Further, when a load is applied to the shaft body 110 in one of the axial directions, the detected value of the second load sensor 142 increases and the detected value of the first load sensor 141 decreases. When a load is applied to the shaft body 110 toward the other side in the axial direction, the detection value of the first load sensor 141 increases and the detection value of the second load sensor 142 decreases. Each of the load sensor 141 and the second load sensor 142 is arranged.

Since no load is applied to the movable cylinder 170, the preload is applied to each of the first load sensor 141 and the second load sensor 142, so that the first load sensor 141 and the second load are applied. It is possible to reduce the detection error at the time of detecting a minute load in each of the sensors 142. As a result, the electric actuator 100 can detect the load of both pushing and pulling from the no-load state with high accuracy.

Further, by preventing the first load sensor 141 and the second load sensor 142 from being exposed to the outside of the housing 120, water, dust, etc. adhere to each of the first load sensor 141 and the second load sensor 142. Can be suppressed to increase the reliability of the electric actuator 100.

Further, since it is not necessary to provide a pair of bearings separately from the first bearing 131 and the second bearing 132 that support the shaft body 110, it is possible to suppress the increase in size of the electric actuator 100.

(Embodiment 2)
Hereinafter, the electric actuator according to the second embodiment of the present invention will be described with reference to the drawings. The electric actuator 200 according to the second embodiment of the present invention is different from the electric actuator 100 according to the first embodiment of the present invention mainly in a configuration for applying a drive mechanism and a preload, and therefore, according to the first embodiment of the present invention. The description of the configuration similar to that of the electric actuator 100 will not be repeated.

FIG. 5 is a partial cross-sectional view showing the configuration of the electric actuator according to the second embodiment of the present invention. As shown in FIG. 5, the electric actuator 200 according to the second embodiment of the present invention includes a drive mechanism, a shaft body 110, a movable nut 160, a housing, a first bearing 131, and a second bearing 132. , A first load sensor 141 and a second load sensor 142 are provided.

The electric actuator 200 further includes a rotary wheel 40 that rotates in the circumferential direction of the shaft body 110 when the drive mechanism is driven. Specifically, the drive mechanism includes a motor and a cylindrical worm 30 connected to the output shaft portion of the motor. The cylindrical worm 30 is engaged with a rotating wheel 40, which is a worm wheel. The cylindrical worm 30 and the rotary wheel 40 form a worm gear.

The shaft body 110 is provided with a male screw portion 114, a cylindrical portion 113, and a screw shaft portion 111 in this order from one side in the axial direction. The minimum diameter of the screw shaft portion 111 is larger than the diameter of the cylindrical portion 113.

The housing includes a first housing 230 and a second housing 220 connected to each other. The first housing 230 is located coaxially with the second housing 220, and the end 233 on one side of the first housing 230 in the axial direction is located on the other side of the second housing 220 in the axial direction. It is fixed to the second housing 220 in a state where it is inserted inside the end portion 223. The other end of the inner peripheral surface 221 of the second housing 220 in the axial direction and the outer peripheral surface of the end 233 of the first housing 230 are in contact with each other.

The first housing 230 and the second housing 220 are provided by bolts (not shown) so that the end portion 223 of the second housing 220 and the flange portion 232 of the first housing 230 abut each other in the axial direction. It is fastened and fixed.

The cylindrical worm 30 and the rotary wheel 40 are housed inside the second housing 220. The first load sensor 141 and the first bearing 131 are housed inside the housing while being located on the other side of the rotary wheel 40 in the axial direction. The second load sensor 142 and the second bearing 132 are housed inside the housing while being located on one side in the axial direction with respect to the rotary wheel 40.

In the first housing 230, the inner diameter of the first housing 230 is partially reduced at a position on the other side in the axial direction with respect to the position where the first load sensor 141 and the first bearing 131 are arranged. It has a first reduced diameter portion 234. In the first housing 230, the first reduced diameter portion 234 is adjacent to the inner peripheral surface 231 surrounding the first load sensor 141 and the first bearing 131.

In the second housing 220, the inner diameter of the second housing 220 is partially reduced at a position on one side in the axial direction with respect to the position where the second load sensor 142 and the second bearing 132 are arranged. It has a second reduced diameter portion 222. In the second housing 220, the second reduced diameter portion 222 is adjacent to the inner peripheral surface surrounding the second load sensor 142 and the second bearing 132.

The first load sensor 141 is arranged side by side with the first reduced diameter portion 234 in the axial direction. The second load sensor 142 is arranged side by side with the second reduced diameter portion 222 in the axial direction.

The inner peripheral surface 41 of the rotary wheel 40 is provided with a female threaded portion that is screwed with a male threaded portion 114 provided on the outer peripheral surface of the one-sided end of the shaft body 110 in the axial direction. The shaft body 110 and the rotary wheel 40 are connected to each other by screwing the male screw portion 114 provided on the outer peripheral surface of one end of the shaft body 110 in the axial direction and the female screw portion of the rotary wheel 40. Will be done. In a state where the male screw portion 114 of the shaft body 110 and the female screw portion of the rotary wheel 40 are screwed together, the other end portion of the rotary wheel 40 in the axial direction and the screw shaft portion 111 of the shaft body 110 in the axial direction. The ends on one side are in contact with each other in the axial direction.

The rotary wheel 40 has a tooth portion that engages with the cylindrical worm 30, a first shoulder portion 43 that is located side by side with respect to the tooth portion in the axial direction, and one of the axial directions with respect to the tooth portion. A second shoulder portion 42 located side by side is provided.

The first load sensor 141 and the first bearing 131 are sandwiched between the first reduced diameter portion 234 and the first shoulder portion 43. The second load sensor 142 and the second bearing 132 are sandwiched between the second reduced diameter portion 222 and the second shoulder portion 42. As a result, each of the first load sensor 141 and the second load sensor 142 is fixed in the housing in a state where the preload is applied so as to be sandwiched in the axial direction. That is, the preload is generated by the axial force of a bolt (not shown) that fastens and fixes the first housing 230 and the second housing 220.

When the motor is driven in the forward direction and the tip fitting 171 pushes the object toward the other in the axial direction, the tip fitting 171 is loaded with the load F1 toward one of the axial directions. The load F1 applied to the tip metal fitting 171 propagates to the nut 160 via the movable cylinder 170. The load F1 propagated to the nut 160 propagates to the screw shaft portion 111 of the shaft body 110 via the ball. The load F1 propagated to the shaft body 110 propagates from the screw shaft portion 111 of the shaft body 110 to the rotary wheel 40. The load F1 propagated to the rotary wheel 40 propagates from the second shoulder portion 42 of the rotary wheel 40 to the second load sensor 142 via the second bearing 132. As a result, the second load sensor 142 detects the load F1.

When the motor is driven in reverse and the tip fitting 171 pulls the object toward one of the axial directions, the tip fitting 171 is loaded with the load F2 toward the other in the axial direction. The load F2 applied to the tip metal fitting 171 propagates to the nut 160 via the movable cylinder 170. The load F2 propagated to the nut 160 propagates to the screw shaft portion 111 of the shaft body 110 via the ball. The load F2 propagated to the shaft body 110 propagates from the male screw portion 114 of the shaft body 110 to the first load sensor 141 via the rotary wheel 40 and the first bearing 131. As a result, the first load sensor 141 detects the load F2.

Also in the electric actuator 200 according to the second embodiment of the present invention, the load applied to the movable cylinder 170 can be calculated by subtracting the detected value of the first load sensor 141 from the detected value of the second load sensor 142. it can.

In the electric actuator 200 according to the second embodiment of the present invention, each of the first load sensor 141 and the second load sensor 142 is fixed in the housing in a state where a preload is applied so as to be sandwiched in the axial direction. ing. Further, when a load is applied to the shaft body 110 in one of the axial directions, the detected value of the second load sensor 142 increases and the detected value of the first load sensor 141 decreases. When a load is applied to the shaft body 110 toward the other side in the axial direction, the detection value of the first load sensor 141 increases and the detection value of the second load sensor 142 decreases. Each of the load sensor 141 and the second load sensor 142 is arranged.

Since no load is applied to the movable cylinder 170, the preload is applied to each of the first load sensor 141 and the second load sensor 142, so that the first load sensor 141 and the second load are applied. It is possible to reduce the detection error at the time of detecting a minute load in each of the sensors 142. As a result, the electric actuator 200 can detect the load of both pushing and pulling from the no-load state with high accuracy.

Further, by preventing the first load sensor 141 and the second load sensor 142 from being exposed to the outside of the housing, water and dust may adhere to each of the first load sensor 141 and the second load sensor 142. It can be suppressed and the reliability of the electric actuator 200 can be improved.

Further, since it is not necessary to provide a pair of bearings separately from the first bearing 131 and the second bearing 132 that support the shaft body 110, it is possible to suppress the increase in size of the electric actuator 200.

(Embodiment 3)
Hereinafter, the electric actuator according to the third embodiment of the present invention will be described with reference to the drawings. The electric actuator 300 according to the third embodiment of the present invention is different from the electric actuator 200 according to the second embodiment of the present invention mainly in that the rotary wheel is connected to the nut. The description of the configuration similar to that of the electric actuator 200 will not be repeated.

FIG. 6 is a partial cross-sectional view showing the configuration of the electric actuator according to the third embodiment of the present invention. As shown in FIG. 6, the electric actuator 300 according to the third embodiment of the present invention includes a drive mechanism, a shaft body 110, a nut 360, a housing, a first bearing 131 and a second bearing 132, and a first bearing. It includes a load sensor 141 and a second load sensor 142.

The electric actuator 300 further includes a rotary wheel 40 that rotates in the circumferential direction of the shaft body 110 when the drive mechanism is driven. Specifically, the drive mechanism includes a motor and a cylindrical worm 30 connected to the output shaft portion of the motor. The cylindrical worm 30 is engaged with a rotating wheel 40, which is a worm wheel. The cylindrical worm 30 and the rotary wheel 40 form a worm gear. The shaft body 110 is provided with a screw shaft portion 111.

The housing includes a first housing 330 and a second housing 220 connected to each other. The first housing 330 is located coaxially with the second housing 220, and the end portion 333 on one side of the first housing 330 in the axial direction is located on the other side of the second housing 220 in the axial direction. It is fixed to the second housing 220 in a state where it is inserted inside the end portion 223. The other end of the inner peripheral surface 221 of the second housing 220 in the axial direction and the outer peripheral surface of the end 333 of the first housing 330 are in contact with each other. The other end in the axial direction on the outer peripheral surface of the rotary wheel 40 and the inner peripheral surface 335 of the end 333 of the first housing 330 are in contact with each other.

The first housing 330 and the second housing 220 are fastened by bolts 240 so that the end portion 223 of the second housing 220 and the flange portion 332 of the first housing 330 abut each other in the axial direction. It is fixed.

The cylindrical worm 30 and the rotary wheel 40 are housed inside the second housing 220. The first load sensor 141 and the first bearing 131 are housed inside the housing while being located on the other side of the rotary wheel 40 in the axial direction. The second load sensor 142 and the second bearing 132 are housed inside the housing while being located on one side in the axial direction with respect to the rotary wheel 40.

In the first housing 330, the inner diameter of the first housing 330 is partially reduced at a position on the other side in the axial direction with respect to the position where the first load sensor 141 and the first bearing 131 are arranged. It has a first reduced diameter portion 334. In the first housing 330, the first reduced diameter portion 334 is adjacent to the inner peripheral surface 331 surrounding the first load sensor 141 and the first bearing 131.

In the second housing 220, the inner diameter of the second housing 220 is partially reduced at a position on one side in the axial direction with respect to the position where the second load sensor 142 and the second bearing 132 are arranged. It has a second reduced diameter portion 222. In the second housing 220, the second reduced diameter portion 222 is adjacent to the inner peripheral surface surrounding the second load sensor 142 and the second bearing 132.

The first load sensor 141 is arranged side by side with the first reduced diameter portion 334 in the axial direction. The second load sensor 142 is arranged side by side with the second reduced diameter portion 222 in the axial direction.

The inner peripheral surface of the rotary wheel 40 is provided with a female threaded portion that is screwed with a male threaded portion provided on the outer peripheral surface of one end of the nut 360 in the axial direction. The shaft body 110 and the rotary wheel 40 are connected to each other by screwing the male screw portion provided on the outer peripheral surface of the one end portion of the nut 360 in the axial direction and the female screw portion of the rotary wheel 40. Wheel.

The first load sensor 141 and the first bearing 131 are sandwiched between the first reduced diameter portion 334 and the nut 360. The second load sensor 142 and the second bearing 132 are sandwiched between the second reduced diameter portion 222 and the rotary wheel 40. As a result, each of the first load sensor 141 and the second load sensor 142 is fixed in the housing in a state where the preload is applied so as to be sandwiched in the axial direction. That is, the preload is generated by the axial force of the bolt 240 that fastens and fixes the first housing 330 and the second housing 220.

In the electric actuator 300 according to the third embodiment of the present invention, the shaft body 110 moves to the other side in the axial direction when the motor is driven to rotate in the forward direction and the nut 360 rotates together with the rotating wheel 40. When the motor is driven in reverse and the nut 360 rotates together with the rotary wheel 40, the shaft body 110 moves to one side in the axial direction. In the electric actuator 300 according to the present embodiment, the shaft body 110 is a linearly movable portion.

When the motor is driven in the normal direction and the shaft body 110 pushes the object toward the other in the axial direction, the load F1 is applied to the shaft body 110 toward the other in the axial direction. The load F1 applied to the shaft body 110 propagates to the nut 160 via the ball. The load F1 propagated to the nut 160 propagates to the rotary wheel 40. The load F1 propagated to the rotary wheel 40 propagates to the second load sensor 142 via the second bearing 132. As a result, the second load sensor 142 detects the load F1.

When the motor reversely drives and the shaft body 110 pulls the object toward one of the axial directions, the shaft body 110 is loaded with the load F2 toward the other of the axial directions. The load F2 applied to the shaft body 110 propagates to the nut 160 via the ball. The load F2 propagated to the nut 160 propagates to the first load sensor 141 via the first bearing 131. As a result, the first load sensor 141 detects the load F2.

Also in the electric actuator 300 according to the third embodiment of the present invention, the load applied to the shaft body 110 can be calculated by subtracting the detected value of the first load sensor 141 from the detected value of the second load sensor 142. it can.

In the electric actuator 300 according to the third embodiment of the present invention, each of the first load sensor 141 and the second load sensor 142 is fixed in the housing in a state where a preload is applied so as to be sandwiched in the axial direction. ing. Further, when a load is applied to the shaft body 110 in one of the axial directions, the detected value of the second load sensor 142 increases and the detected value of the first load sensor 141 decreases. When a load is applied to the shaft body 110 toward the other side in the axial direction, the detection value of the first load sensor 141 increases and the detection value of the second load sensor 142 decreases. Each of the load sensor 141 and the second load sensor 142 is arranged.

Since no load is applied to the shaft body 110, the preload is applied to each of the first load sensor 141 and the second load sensor 142, so that the first load sensor 141 and the second load are applied. It is possible to reduce the detection error at the time of detecting a minute load in each of the sensors 142. As a result, the electric actuator 300 can detect the load of both pushing and pulling from the no-load state with high accuracy.

Further, by preventing the first load sensor 141 and the second load sensor 142 from being exposed to the outside of the housing, water and dust may adhere to each of the first load sensor 141 and the second load sensor 142. It can be suppressed and the reliability of the electric actuator 300 can be improved.

Further, since it is not necessary to provide a pair of bearings separately from the first bearing 131 and the second bearing 132 that support the shaft body 110, it is possible to suppress the increase in size of the electric actuator 300.

(Embodiment 4)
Hereinafter, the electric actuator according to the fourth embodiment of the present invention will be described with reference to the drawings. The electric actuator 400 according to the fourth embodiment of the present invention is the same as the electric actuator 100 according to the first embodiment of the present invention because the configuration of the linearly movable portion is mainly different from the electric actuator 100 according to the first embodiment of the present invention. The description of the configuration is not repeated.

FIG. 7 is a partial cross-sectional view showing the configuration of the electric actuator according to the fourth embodiment of the present invention. As shown in FIG. 7, the electric actuator 400 according to the fourth embodiment of the present invention includes a drive mechanism, a shaft body 110, a movable nut 160, a housing 420, a first bearing 131, and a second bearing 132. And a first load sensor 141 and a second load sensor 142.

The drive mechanism includes a motor 10 and a speed reduction mechanism unit 12 connected to an output shaft portion of the motor 10. The speed reduction mechanism portion 12 is connected to a rotating shaft portion 115 located at one end of the shaft body 110 in the axial direction. In the present embodiment, the motor 10 and the shaft body 110 are arranged so as to be orthogonal to each other, but the present invention is not limited to this, and the motor 10 and the shaft body 110 may be arranged in the same linear shape. ..

A tip metal fitting 470 is attached to the nut 160. The tip metal fitting 470 can move together with the nut 160 in the axial direction relative to the shaft body 110. In the electric actuator 400 according to the present embodiment, the tip metal fitting 470 serves as a linear movable portion.

The housing 420 accommodates a part of the shaft body 110. In the present embodiment, the housing 420 has a substantially cylindrical outer shape. The housing 420 is arranged coaxially with the shaft body 110. A cylindrical portion 113 and a male screw portion 114 of the shaft body 110 are located inside the housing 420.

The housing 20 is arranged on one side of the housing 420 in the axial direction, and the outer cylinder 22 is arranged on the other side of the housing 420 in the axial direction. The housing 420 is connected to each of the housing 20 and the outer cylinder 22 in a state of being sandwiched between the housing 20 and the outer cylinder 22.

The first bearing 131 and the second bearing 132 are arranged in the housing 420 with the shaft body 110 inserted. A cylindrical portion 113 of the shaft body 110 is located inside each of the first bearing 131 and the second bearing 132.

Each of the first load sensor 141 and the second load sensor 142 is annular and is arranged in the housing 420 with the shaft body 110 inserted. A cylindrical portion 113 of the shaft body 110 is located inside each of the first load sensor 141 and the second load sensor 142. The first load sensor 141 is arranged side by side with the first bearing 131. The second load sensor 142 is arranged side by side with the second bearing 132.

In the housing 420, the inner diameter of the housing 420 is partially reduced between the position where the first load sensor 141 is arranged and the position where the second load sensor 142 is arranged in the axial direction. It has a reduced diameter portion 422. Specifically, in the housing 420, between the inner peripheral surface surrounding the first bearing 131 and the first load sensor 141 and the inner peripheral surface surrounding the second bearing 132 and the second load sensor 142. A reduced diameter portion 422 having a small inner diameter is provided. Each of the first load sensor 141 and the second load sensor 142 is arranged side by side with the reduced diameter portion 422 in the axial direction.

The shaft body 110 has a male screw portion 114 at a position on one side of the position of the diameter-reduced portion 422 in the axial direction in a state where the cylindrical portion 113 of the shaft body 110 is housed in the housing 420, and the shaft body 110 has the male screw portion 114. The diameter-expanded portion 112 is provided at a position on the opposite side of the position of the diameter-reduced portion 422 in the direction.

The electric actuator 400 further includes a locknut 150 that is screwed with the male threaded portion 114 of the shaft body 110. In the housing 420, the first load sensor 141 and the first bearing 131 located on one side in the axial direction with respect to the reduced diameter portion 422, and the position on the other side in the axial direction with respect to the reduced diameter portion 422. The male screw portion 114 of the shaft body 110 inserted through the second load sensor 142 and the second bearing 132 toward one side in the axial direction and the locknut 150 are screwed together to form the first load sensor 141 and The first bearing 131 is sandwiched between the reduced diameter portion 422 and the locknut 150, and the second load sensor 142 and the second bearing 132 are sandwiched between the reduced diameter portion 422 and the enlarged diameter portion 112. As a result, each of the first load sensor 141 and the second load sensor 142 is fixed in the housing 420 with a preload applied so as to be sandwiched in the axial direction. That is, the preload is generated by the axial force when the locknut 150 is tightened to the male screw portion 114.

In the electric actuator 400 according to the present embodiment, the motor 10 is driven in the normal direction to rotate the screw shaft portion 111 of the shaft body 110, so that the tip metal fitting 470 moves to the other side in the axial direction together with the nut 160. As the motor 10 reversely drives and the screw shaft portion 111 of the shaft body 110 rotates, the tip metal fitting 470 moves to one side in the axial direction together with the nut 160.

When the motor 10 is driven in the forward direction and the tip fitting 470 pushes up the conveyed object toward the other in the axial direction, the tip fitting 470 is loaded with the load F1 toward one of the axial directions. The load F1 applied to the tip metal fitting 470 propagates to the nut 160. The load F1 propagated to the nut 160 propagates to the screw shaft portion 111 of the shaft body 110 via the ball. The load F1 propagated to the shaft body 110 propagates from the enlarged diameter portion 112 of the shaft body 110 to the second load sensor 142 via the second bearing 132. As a result, the second load sensor 142 detects the load F1.

When the motor 10 is driven in reverse and the tip fitting 470 pulls the conveyed object toward one of the axial directions, the tip fitting 470 is loaded with the load F2 toward the other in the axial direction. The load F2 applied to the tip metal fitting 470 propagates to the nut 160. The load F2 propagated to the nut 160 propagates to the screw shaft portion 111 of the shaft body 110 via the ball. The load F2 propagated to the shaft body 110 propagates from the male screw portion 114 of the shaft body 110 to the first load sensor 141 via the locknut 150 and the first bearing 131. As a result, the first load sensor 141 detects the load F2.

Also in the electric actuator 400 according to the fourth embodiment of the present invention, the load applied to the tip metal fitting 470 can be calculated by subtracting the detected value of the first load sensor 141 from the detected value of the second load sensor 142. it can.

In the electric actuator 400 according to the fourth embodiment of the present invention, each of the first load sensor 141 and the second load sensor 142 is inside the housing 420 with a preload applied so as to be sandwiched in the axial direction. It is fixed. Further, when a load is applied to the shaft body 110 in one of the axial directions, the detected value of the second load sensor 142 increases and the detected value of the first load sensor 141 decreases. When a load is applied to the shaft body 110 toward the other side in the axial direction, the detection value of the first load sensor 141 increases and the detection value of the second load sensor 142 decreases. Each of the load sensor 141 and the second load sensor 142 is arranged.

Since no load is applied to the tip metal fitting 470, the preload is applied to each of the first load sensor 141 and the second load sensor 142, so that the first load sensor 141 and the second load are applied. It is possible to reduce the detection error at the time of detecting a minute load in each of the sensors 142. As a result, the electric actuator 400 can detect the load of both pushing and pulling from the no-load state with high accuracy.

Further, by preventing the first load sensor 141 and the second load sensor 142 from being exposed to the outside of the housing 420, water, dust, etc. adhere to each of the first load sensor 141 and the second load sensor 142. Can be suppressed to increase the reliability of the electric actuator 400.

Further, since it is not necessary to provide a pair of bearings separately from the first bearing 131 and the second bearing 132 that support the shaft body 110, it is possible to suppress the increase in size of the electric actuator 400.

(Embodiment 5)
Hereinafter, the load load detecting unit according to the fifth embodiment of the present invention, which is detachably attached to the tip of the linearly movable portion of the electric actuator and detects the load load of the electric actuator, will be described with reference to the drawings.

FIG. 8 is a cross-sectional view showing the configuration of the load-bearing detection unit according to the fifth embodiment of the present invention. FIG. 9 is a partial cross-sectional view showing a state in which the load load detection unit according to the fifth embodiment of the present invention is attached to the electric actuator according to the first embodiment of the present invention.

As shown in FIGS. 8 and 9, the load load detecting unit 500 according to the fifth embodiment of the present invention is detachably attached to the tip of the linearly movable portion of the electric actuator to detect the load of the electric actuator. It is a load detection unit.

The load load detection unit 500 includes a housing 520, a shaft body 570, and a first load sensor 541 and a second load sensor 542.

The housing 520 is provided so as to be connectable to the tip of the movable cylinder 170, which is the tip of the linearly movable portion of the electric actuator 100.

The shaft body 570 extends in the axial direction. The shaft body 570 is provided with a male screw portion 573, a cylindrical portion 572, and a diameter-expanded portion 571 in this order from one side in the axial direction. In the enlarged diameter portion 571, the diameter of the shaft body 570 is partially increased. The enlarged diameter portion 571 is provided with a through hole 571h penetrating in a direction orthogonal to the axial direction. A part of the shaft body 570 on one side in the axial direction is housed inside the housing 520.

In the present embodiment, the housing 520 has a substantially cylindrical outer shape. The housing 520 is arranged coaxially with the shaft body 570. A cylindrical portion 572 and a male screw portion 573 of the shaft body 570 are located inside the housing 520.

Each of the first load sensor 541 and the second load sensor 542 is annular and is arranged in the housing 520 with the shaft body 570 inserted. A cylindrical portion 572 of the shaft body 570 is located inside each of the first load sensor 541 and the second load sensor 542. The shapes of the first load sensor 541 and the second load sensor 542 are not limited to the annular shape.

In the housing 520, the inner diameter of the housing 520 is partially reduced between the position where the first load sensor 541 is arranged and the position where the second load sensor 542 is arranged in the axial direction. It has a reduced diameter portion 522.

Specifically, in the housing 520, between the inner peripheral surface 521 surrounding the first load sensor 541 and the inner peripheral surface 521 surrounding the second load sensor 542, the inner diameter is larger than the inner peripheral surface 521. A small diameter reduction portion 522 is provided. The first load sensor 541 is arranged side by side with the reduced diameter portion 122 in the axial direction. Second load sensor 542 The second load sensor 542 is arranged side by side with the reduced diameter portion 122 in the axial direction. In the present embodiment, the first load sensor 541 is in direct contact with the reduced diameter portion 122, but may be indirectly in contact with the reduced diameter portion 122 via, for example, a washer or the like. The second load sensor 542 is in direct contact with the reduced diameter portion 122, but may be indirectly in contact with the reduced diameter portion 122 via, for example, a washer or the like.

The shaft body 570 has a male screw portion 573 at a position on one side of the position of the diameter reduction portion 522 in the axial direction in a state where the cylindrical portion 572 and the male screw portion 573 of the shaft body 570 are housed in the housing 520. Moreover, a diameter-expanded portion 571 in which the diameter of the shaft body 570 is partially increased is provided at a position on the opposite side of the position of the diameter-reduced portion 522 in the axial direction.

The load load detection unit 500 further includes a lock nut 550 that is screwed with the male thread portion 573 of the shaft body 570. In the housing 520, the first load sensor 541 located on the one side in the axial direction with respect to the reduced diameter portion 522, and the second load sensor 541 located on the other side in the axial direction with respect to the reduced diameter portion 522. The first load sensor 541 has a reduced diameter portion 522 and a locknut 550 by screwing the male screw portion 573 of the shaft body 570 into which the load sensor 542 is inserted toward the one side in the axial direction and the locknut 550. The second load sensor 542 is sandwiched between the reduced diameter portion 522 and the enlarged diameter portion 571. As a result, each of the first load sensor 541 and the second load sensor 542 is fixed in the housing 520 with a preload applied so as to be sandwiched in the axial direction. That is, the preload is generated by the axial force when the locknut 550 is tightened to the male screw portion 573.

A female screw portion 523 for connecting the tip of the movable cylinder 170 of the electric actuator 100 and the load load detecting unit 500 is provided at one end of the inner peripheral surface 521 of the housing 520 in the axial direction. ..

When the motor 10 is driven in the normal direction and the shaft body 570 pushes the object toward the other in the axial direction, the load F1 is applied to the shaft body 570 toward the other in the axial direction. The load F1 loaded on the shaft body 570 propagates to the second load sensor 542. As a result, the second load sensor 542 detects the load F1.

By comparing the detected value of the second load sensor 142 of the electric actuator 100 with the detected value of the second load sensor 542 of the load load detection unit 500, the second load sensor 142 of the electric actuator 100 is calibrated with respect to the load F1. Can be done.

When the motor 10 reversely drives and the shaft body 570 pulls the object toward one of the axial directions, the shaft body 570 is loaded with the load F2 toward the other of the axial directions. The load F2 loaded on the shaft body 570 propagates from the male screw portion 573 of the shaft body 570 to the first load sensor 541 via the locknut 550. As a result, the first load sensor 541 detects the load F1.

By comparing the detected value of the first load sensor 141 of the electric actuator 100 with the detected value of the first load sensor 541 of the load load detection unit 500, the calibration of the first load sensor 141 of the electric actuator 100 with respect to the load F2. Can be done.

As described above, in the load load detection unit 500 according to the present embodiment, the detection value of the second load sensor 542 increases when a load is applied to the shaft body 570 in one of the axial directions. While decreasing the detected value of the first load sensor 541 and increasing the detected value of the first load sensor 541 when a load is applied to the shaft body 570 toward the other in the axial direction. Each of the first load sensor 541 and the second load sensor 542 is arranged so that the detected value of the second load sensor 542 is reduced.

In the load load detection unit 500 according to the fifth embodiment of the present invention, each of the first load sensor 541 and the second load sensor 542 is loaded with a preload so as to be sandwiched in the axial direction of the housing 520. It is fixed inside. Further, when a load is applied to the shaft body 570 in one of the axial directions, the detection value of the second load sensor 542 increases and the detection value of the first load sensor 541 decreases. When a load is applied to the shaft body 570 toward the other side in the axial direction, the detection value of the first load sensor 541 increases and the detection value of the second load sensor 542 decreases. Each of the load sensor 541 and the second load sensor 542 is arranged.

Since no load is applied to the shaft body 570, the preload is applied to each of the first load sensor 541 and the second load sensor 542, so that the first load sensor 541 and the second load are loaded. It is possible to reduce the detection error at the time of detecting a minute load in each of the sensors 542. As a result, the load load detection unit 500 can detect the load load of both pushing and pulling from the no-load state with high accuracy.

In the load load detection unit 500 according to the fifth embodiment of the present invention, the electric actuator 100 is simply operated with the load load detection unit 500 attached to the tip of the linearly movable portion of the electric actuator 100. Load Load can be detected easily and accurately.

In the present embodiment, the load load detection unit 500 is attached to the electric actuator 100 according to the first embodiment of the present invention, but the present invention is not limited to this, and the load load detection unit 500 is attached to the second embodiment of the present invention. It may be attached to the electric actuator according to any one of 4 or may be attached to an electric actuator that does not have a built-in load sensor. When the load load detection unit 500 according to the fifth embodiment of the present invention is attached to an electric actuator that does not have a built-in load sensor, the load detected by the load load detection unit 500 is confirmed to actually attach the load sensor to the electric actuator. You can know the load that is being loaded. This makes it possible to know the relationship between the output value of the motor 10 and the load applied to the electric actuator.

(Embodiment 6)
Hereinafter, a load load detecting unit according to the sixth embodiment of the present invention, which is detachably attached to the tip of a linearly movable portion of the electric actuator and detects the load load of the electric actuator, will be described with reference to the drawings.

FIG. 10 is a cross-sectional view showing the configuration of the load-bearing detection unit according to the sixth embodiment of the present invention. FIG. 11 is a partial cross-sectional view showing a state in which the load load detection unit according to the sixth embodiment of the present invention is attached to the electric actuator according to the first embodiment of the present invention.

As shown in FIGS. 10 and 11, the load load detecting unit 600 according to the sixth embodiment of the present invention is detachably attached to the tip of the linearly movable portion of the electric actuator to detect the load of the electric actuator. It is a load detection unit.

The load load detection unit 600 includes a first housing 620, a second housing 690, a shaft body 670, and a load sensor 641. The load sensor 641 is annular and is arranged in the first housing 620 with the shaft body 670 inserted. The shape of the load sensor 641 is not limited to the annular shape.

The first housing 620 has a reduced diameter portion 622 in which the inner diameter of the first housing 620 is partially reduced at a position on one side in the axial direction with respect to the position where the load sensor 641 is arranged. Moreover, the female screw portion 623 is provided on the inner peripheral surface 621 at the position on the other side in the axial direction with respect to the position where the load sensor 641 is arranged. The first housing 620 is provided so as to be connectable to the tip of the movable cylinder 170, which is the tip of the linearly movable portion of the electric actuator 100.

The second housing 690 includes a male screw portion 692 that is screwed with the female screw portion 623 on the outer peripheral surface of the end portion 693 that is inserted inside the first housing 620, and the other side of the first housing 620 in the axial direction. It has a flange portion 691 that comes into contact with the end face of the.

The second housing 690 is located coaxially with the first housing 620, and the end portion 693 on one side of the second housing 690 in the axial direction is located on the other side of the first housing 620 in the axial direction. It is fixed to the first housing 620 in a state of being inserted inside the end portion 624.

Specifically, the female threaded portion 623 of the first housing 620 and the male threaded portion 692 of the second housing 690 are screwed together to form an end portion 624 of the first housing 620 and a flange portion of the second housing 690. The first housing 620 and the second housing 690 are connected to each other in a state where the 691 is in contact with the second housing.

The shaft body 670 extends in the axial direction. The shaft body 670 is provided with a male screw portion 673, a cylindrical portion 672, and a diameter-expanded portion 671 in this order from one side in the axial direction. In the enlarged diameter portion 671, the diameter of the shaft body 670 is partially increased. In the shaft body 670, a cylindrical portion 672 and a male screw portion 673 are housed inside the first housing 620.

The shaft body 670 has a male screw portion 673 on one side of the position of the other end of the diameter-reduced portion 622 of the first housing 620 in the axial direction, and the contraction of the first housing 620 in the axial direction. On the other side of the position where the diameter portion 622 is arranged, there is a diameter expansion portion 671 in which the diameter of the shaft body 670 is partially increased.

The load load detection unit 600 further includes a lock nut 650 that is screwed with the male thread portion 673 of the shaft body 670. In the first housing 620, the male screw portion 673 of the shaft body 670 and the locknut, in which the load sensor 641 located on the other side in the axial direction with respect to the reduced diameter portion 622 is inserted toward one side in the axial direction. By screwing the 650, the load sensor 641 is sandwiched between the locknut 650 and the enlarged diameter portion 671.

By screwing the male screw portion 692 of the second housing 690 and the female screw portion 623 of the first housing 620, the end surface of the first housing 620 and the flange portion 691 of the second housing 690 come into contact with each other. , The load sensor 641 is sandwiched between the reduced diameter portion 622 and the end portion 693 of the second housing 690.

As a result, the load sensor 641 is fixed in the first housing 620 in a state where a preload is applied so as to be sandwiched in the axial direction. That is, the preload is the axial force when the locknut 650 is tightened to the male screw portion 673 and the shaft when the male screw portion 692 of the second housing 690 is tightened to the female screw portion 623 of the first housing 620. It is generated by force.

When the motor 10 is driven in the normal direction and the shaft body 670 pushes the object toward the other in the axial direction, the load F1 is applied to the shaft body 670 toward the other in the axial direction. The load F1 loaded on the shaft body 670 propagates to the load sensor 641. As a result, the load sensor 641 detects the load F1.

By comparing the detected value of the second load sensor 142 of the electric actuator 100 with the detected value of the load sensor 641 of the load load detection unit 600, the second load sensor 142 of the electric actuator 100 is calibrated with respect to the load F1. be able to.

When the motor 10 reversely drives and the shaft body 670 pulls the object toward one of the axial directions, the shaft body 670 is loaded with the load F2 toward the other of the axial directions. The load F2 loaded on the shaft body 670 propagates from the male screw portion 673 of the shaft body 670 to the load sensor 641 via the locknut 650. As a result, the load sensor 641 detects the load F1.

By comparing the detected value of the first load sensor 141 of the electric actuator 100 with the detected value of the load sensor 641 of the load load detection unit 600, the first load sensor 141 of the electric actuator 100 is calibrated with respect to the load F2. be able to.

As described above, in the load load detection unit 600 according to the present embodiment, the detection value of the load sensor 641 is increased when a load is applied to the shaft body 670 in one of the axial directions. In addition, the load sensor 641 is arranged so that the detected value of the load sensor 641 increases when a load is applied to the shaft body 670 toward the other side in the axial direction.

In the load load detection unit 600 according to the fifth embodiment of the present invention, the load sensor 641 is fixed in the first housing 620 in a state where a preload is applied so as to be sandwiched in the axial direction. Further, when a load is applied to the shaft body 670 in one direction in the axial direction, the detected value of the load sensor 641 increases, and the detection value is directed toward the other side in the axial direction with respect to the shaft body 670. The load sensor 641 is arranged so that the detected value of the load sensor 641 increases when the load is applied.

By applying a preload to the load sensor 641 from the time when no load is applied to the shaft body 670, it is possible to reduce the detection error when the load sensor 641 detects a minute load. As a result, the load load detection unit 600 can detect the load load of both pushing and pulling from the no-load state with high accuracy.

In the load load detection unit 600 according to the sixth embodiment of the present invention, the electric actuator 100 is simply operated with the load load detection unit 600 attached to the tip of the linearly movable portion of the electric actuator 100. Load Load can be detected easily and accurately.

In the present embodiment, the load load detection unit 600 is attached to the electric actuator 100 according to the first embodiment of the present invention, but the present invention is not limited to this, and the load load detection unit 600 is attached to the second embodiment of the present invention. It may be attached to the electric actuator according to any one of 4 or may be attached to an electric actuator that does not have a built-in load sensor. When the load load detection unit 600 according to the sixth embodiment of the present invention is attached to an electric actuator that does not have a built-in load sensor, the load detected by the load load detection unit 600 is confirmed to actually attach the load load detection unit 600 to the electric actuator. You can know the load that is being loaded. This makes it possible to know the relationship between the output value of the motor 10 and the load applied to the electric actuator.

In the present embodiment, since the load load detection unit 600 includes only one load sensor, the load load detection unit is cheaper than the load load detection unit 500 according to the fifth embodiment of the present invention. be able to.

In the description of the above-described embodiment, the configurations that can be combined may be combined with each other.

The embodiments disclosed this time should be considered to be exemplary in all respects and not restrictive. The scope of the present invention is shown by the scope of claims rather than the above description, and it is intended to include all modifications within the meaning and scope equivalent to the scope of claims.

10 motor, 11 output shaft, 12 reduction mechanism, 20 housing, 21 base plate, 21h opening, 22 outer cylinder, 23 bush, 30 cylindrical worm, 40 rotating wheel, 41,121,221,231,331,335, 521,621 Inner peripheral surface, 42 2nd shoulder, 43 1st shoulder, 100,200,300,400 Electric actuator, 110,570,670 Shaft, 111 Thread shaft, 112,571,671 Enlarged part , 113,572,672 Cylindrical part, 114,573,673,692 Male thread part, 115 Rotating shaft part, 120,420,520 Housing, 122,422,522,622 Reduced diameter part, 123,571h Through hole, 131 1st bearing, 132 2nd bearing, 141,541 1st load sensor, 142,542 2nd load sensor, 150,550,650 lock nut, 160,360 nut, 170 movable cylinder, 171,470 tip bracket, 180 terminals Box, 181 main body, 182 lid, 183 packing, 184 seal, 186 board stand, 187 amplifier stand, 220,690 2nd housing, 222 2nd reduced diameter part, 223, 233,333,624,693 end Unit, 230,330,620 1st housing, 232,332,691 Flange part, 234,334 1st reduced diameter part, 240 volts, 500,600 load load detection unit, 523,623 female thread part, 641 load sensor.

Claims (4)

A load load detection unit that is detachably attached to the tip of a linearly movable part of an electric actuator to detect the load of the electric actuator.
A housing provided with a connection portion connected to the tip portion, and
A shaft body extending in the axial direction and accommodating a part of one side in the axial direction inside the housing.
An annular first load sensor and a second load sensor arranged in the housing with the shaft body inserted are provided.
Each of the first load sensor and the second load sensor is fixed in the housing in a state where a preload is applied so as to be sandwiched in the axial direction.
When a load is applied to the shaft body in one direction in the axial direction, the detection value of the second load sensor increases while the detection value of the first load sensor decreases, and the above. The first load is increased so that the detected value of the first load sensor is increased and the detected value of the second load sensor is decreased when a load is applied to the shaft body toward the other side in the axial direction. A load-bearing detection unit in which each of the sensor and the second load sensor is arranged. In the housing, the inner diameter of the housing is partially reduced between the position where the first load sensor is arranged and the position where the second load sensor is arranged in the axial direction. It has a reduced diameter part and
The shaft body has a male screw portion at a position on one side of the position of the reduced diameter portion in the axial direction in a state where the part of the shaft body is housed in the housing, and the shaft body has a male screw portion in the axial direction. A diameter-expanded portion in which the diameter of the shaft body is partially increased is provided at a position on the opposite side of the position of the reduced-diameter portion in the above.
The load load detection unit further includes a locknut that is screwed with the male thread portion of the shaft body.
In the housing, the first load sensor located on the one side in the axial direction with respect to the reduced diameter portion, and the second load sensor located on the other side in the axial direction with respect to the reduced diameter portion. By screwing the male screw portion of the shaft body through which the load sensor is inserted toward the one side in the axial direction and the locknut, the first load sensor has the reduced diameter portion and the locknut. The load load detection unit according to claim 1, wherein the second load sensor is sandwiched between the reduced diameter portion and the enlarged diameter portion. A load load detection unit that is detachably attached to the tip of a linearly movable part of an electric actuator to detect the load of the electric actuator.
A first housing provided with a connecting portion connected to the tip portion, and
A second housing fixed to the first housing with the end portion inside the first housing while being located coaxially with the first housing.
A shaft body extending in the axial direction and accommodating a part of one side in the axial direction inside the first housing and the second housing.
It is provided with an annular load sensor arranged in the first housing with the shaft body inserted.
The load sensor is fixed in the first housing in a state where a preload is applied so as to be sandwiched in the axial direction.
When a load is applied to the shaft body in one direction in the axial direction, the detection value of the load sensor increases, and the load is applied to the shaft body in the other direction in the axial direction. A load load detection unit in which the load sensor is arranged so that the detection value of the load sensor increases when the load sensor is loaded. The first housing has a reduced diameter portion in which the inner diameter of the first housing is partially reduced at a position on one side of the axial direction with respect to the position where the load sensor is arranged. Moreover, it has a female threaded portion on the inner peripheral surface of the position on the other side in the axial direction with respect to the position where the load sensor is arranged.
The second housing has a male screw portion that is screwed with the female screw portion on the outer peripheral surface of the end portion that is inserted inside the first housing, and the other side of the first housing in the axial direction. It has a flange that comes into contact with the end face,
The shaft body has a male screw portion on one side of the position of the other end of the reduced diameter portion of the first housing in the axial direction, and the shaft body has the male screw portion in the axial direction of the first housing. On the other side of the position where the reduced diameter portion is arranged, there is an enlarged diameter portion in which the diameter of the shaft body is partially increased.
The load load detection unit further includes a locknut that is screwed with the male thread portion of the shaft body.
In the first housing, the male screw portion of the shaft body inserted with the load sensor located on the other side in the axial direction with respect to the reduced diameter portion toward the one side in the axial direction. By screwing the locknut, the load sensor is sandwiched between the locknut and the enlarged diameter portion.
By screwing the male screw portion of the second housing and the female screw portion of the first housing, the end face of the first housing and the flange portion of the second housing come into contact with each other. The load load detection unit according to claim 3, wherein the load sensor is sandwiched between the reduced diameter portion and the end portion of the second housing.

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