JP7427236B2 - actuator - Google Patents

Description

The present invention relates to an actuator that includes a device body on which a driven shaft is disposed and a rotational drive source, and that rotates the driven shaft around its axis by driving the rotational drive source.

Some actuators of this type include a device body in which a driven shaft is disposed and a rotational drive source arranged side by side. According to this actuator, since the dimension in the longitudinal direction can be suppressed, there are advantages such as improved operability (see, for example, Patent Document 1).

Japanese Patent Application Publication No. 2015-40571

By the way, actuators have different required specifications such as the rotational speed and torque of the driven shaft depending on the purpose, so it is preferable to prepare actuators with different configurations of electric motors and speed reduction mechanisms. However, electric motors and speed reduction mechanisms with different configurations do not necessarily have the same external dimensions. For this reason, it is necessary to prepare a plurality of types of device main bodies depending on the required specifications, which is not necessarily desirable when manufacturing costs are taken into consideration.

SUMMARY OF THE INVENTION In view of the above circumstances, an object of the present invention is to provide an actuator that can be manufactured in a plurality of types with different required specifications while reducing manufacturing costs.

In order to achieve the above object, an actuator according to the present invention includes a driven shaft rotatably disposed inside a device main body, and an output shaft that is parallel to the axis of the driven shaft through a case. and a power transmission mechanism provided between an output shaft of the rotary drive source and the driven shaft, the power transmission mechanism being driven by the rotary drive source. The actuator is configured to rotate the driven shaft around the axis via a mechanism, wherein the device main body is provided with a case mounting part for supporting the case, and the case mounting part and the case are connected to each other. An adjustment member configured separately from the case mounting portion and the case is interposed between the case mounting portion and the case.

Further, the present invention is characterized in that, in the actuator described above, the adjustment member is provided so as to surround the periphery of the case, and the case attachment portion is provided so as to surround the periphery of the adjustment member. do.

Further, in the actuator of the present invention, the adjustment member is configured to have an outer shape that is rotationally symmetrical about the axis of the output shaft when attached to the case, and the adjustment member is configured to have an outer shape that is rotationally symmetrical about the axis of the output shaft, and The inner shape is characterized in that it is configured to be rotationally symmetrical about an axis that is parallel to the axis of the driven shaft.

Further, the present invention is characterized in that, in the above-mentioned actuator, the support portion of the case to which the adjustment member is attached is configured to have an outer shape that is rotationally symmetrical about the axis of the output shaft. do.

Further, the present invention is characterized in that, in the actuator described above, the power transmission mechanism is configured to include a friction-type torque limit mechanism.

Further, in the actuator of the present invention, the rotational drive source includes an electric motor and a speed reduction mechanism, and the final output shaft of the speed reduction mechanism is the output shaft, and the motor output shaft of the electric motor is and a final output shaft of the speed reduction mechanism are arranged on the same axis.

Furthermore, in the actuator described above, the driven shaft has a spiral groove on its outer circumferential surface, and the driven shaft is slidable along the axial direction and restricted from rotating around the axial center. The present invention is characterized in that a slide member is provided which is screwed into the spiral groove in a state where the slide member is in the spiral groove.

Furthermore, in the actuator described above, the slide member is provided with a plunger, and the device main body is provided with a plunger opening that exposes the plunger to the outside in a portion that is an extension of the driven shaft. It is characterized by being

According to the present invention, by changing the adjustment member, it becomes possible to attach rotary drive sources with different external dimensions to a common device main body, and it becomes possible to suppress manufacturing costs.

FIG. 1 shows an actuator according to an embodiment of the present invention, in which (a) is a perspective view as seen from one end, and (b) is a perspective view as seen from the other end. 2 shows the actuator shown in FIG. 1, in which (a) is a plan view, (b) is a front view, (c) is one end view, and (d) is the other end view. FIG. 3 is a cross-sectional view taken along the line XX in FIG. 2(d), in which (a) shows the plunger in a retracted state, and (b) shows the plunger in an advanced state. FIG. 4 is an enlarged sectional view of a main part of the actuator shown in FIG. FIG. 5 shows a rotational drive source applied to the actuator shown in FIG. 1, in which (a) is an external view and (b) is a partially cutaway view. FIG. 6 is an enlarged view of FIG. 2(d) with the power transmission mechanism omitted.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of an actuator according to the present invention will be described in detail below with reference to the accompanying drawings.

1 to 3 show an actuator that is an embodiment of the present invention. Although the actuator exemplified here is not clearly shown in the figure, it is applied as a drive device for an electric syringe that pushes and moves the piston of a cartridge filled with a drug solution to discharge the drug solution from the tip of the injection needle. , a screw shaft (driven shaft) 10 is provided inside the device main body 1. The screw shaft 10 has a cylindrical base 11 with a spiral groove 11a on its outer circumferential surface, and a support shaft 12 provided at the base end of the base 11. By interposing two thrust bearings 13 between the device body 1 and the device body 1, the device body 1 is rotatably supported around its own axis.

The screw shaft 10 is provided with a nut (slide member) 14 and a plunger 15 at the base 11, and an input gear ( (power transmission mechanism and torque limit mechanism) 16.

The nut 14 constitutes a sliding screw together with the screw shaft 10, and is screwed onto the base 11 of the screw shaft 10 via a spiral groove (not shown) provided on the inner peripheral surface. Although not clearly shown in the figure, this nut 14 is housed in a guide hole 2 provided on the outer periphery of the screw shaft 10 in the device main body 1 in a state where relative rotation with the screw shaft 10 is restricted. When the screw shaft 10 rotates around the axis, it is possible to move inside the guide hole 2 along the axial direction of the screw shaft 10. In this embodiment, the nut 14 is made of resin, and a fluorine-based wet/dry lubricant is applied between the nut 14 and the screw shaft 10. The screw shaft 10 is made of metal and has leads that are larger than the standard pitch. The plunger 15 has a cylindrical shape with its base end open and its distal end closed, and the inner diameter of the center hole 15a is formed to a size that allows the base 11 of the screw shaft 10 to be inserted therein. The plunger 15 has its base end fixed to the nut 14 with the screw shaft 10 inserted into the center hole 15a, and its tip end exposed to the outside through the plunger opening 3 provided in the device body 1. It is possible to move with the nut 14 relative to the screw shaft 10. A guide collar 4 for guiding the movement of the plunger 15 is installed between the plunger opening 3 provided in the device body 1 and the plunger 15. A seal member 5 that slides into contact with the outer circumferential surface of the plunger 15 is disposed on the inner circumferential surface of the guide collar 4 .

The input gear 16 is a spur gear fitted to the base end of the screw shaft 10 so as to be relatively rotatable. As shown in FIG. 604, this input gear 16 is provided with a pressure ring (torque limit mechanism) 17 on the proximal side, and a pressure spring on the distal side between it and the thrust bearing 13. 18 are provided. The press ring 17 is an annular member attached to the screw shaft 10 in such a manner that relative rotation thereof is prevented and movement in the axial direction is prevented. The pressing spring 18 is disposed in a compressed state between the input gear 16 and the thrust bearing 13, and presses the input gear 16 against the pressing ring 17 by elastic restoring force. The spring force of the pressure spring 18 is such that when the rotational load applied to the screw shaft 10 is less than a preset threshold, the friction force acting between the input gear 16 and the pressure ring 17 causes the input gear 16 to rotate. It is set to a size that causes slippage between the input gear 16 and the pressing ring 17 when the rotational load transmitted to and applied to the screw shaft 10 exceeds a threshold value.

A rotational drive source 20 is disposed at a side of the screw shaft 10 in the main body 1 of the apparatus. As shown in FIG. 5, the rotational drive source 20 includes an electric motor 21 and a speed reduction mechanism 22, and the final output shaft of the speed reduction mechanism 22 is an output shaft 23. The electric motor 21 is configured such that a motor output shaft 21b protrudes from the center of one end surface of a cylindrical motor body 21a. The deceleration mechanism 22 decelerates the rotation of the motor output shaft 21b caused by the drive of the electric motor 21. In this embodiment, the speed reduction mechanism 22 is constructed by connecting two sets of planetary gear mechanisms in series and housing them inside a case 24. The case 24 is molded from resin, and a portion 24a that accommodates the speed reduction mechanism 22 has a cylindrical shape with approximately the same outer diameter as the motor body 21a, and a portion 24b that surrounds the output shaft 23 has a cylindrical shape with a small diameter. It is configured so that Although not clearly shown in the figure, a thread groove is formed on the outer periphery of the portion 24b surrounding the output shaft 23. The rotary drive source 20 connects the case 24 to the motor body 21a with the output shaft 23 disposed on the same axis as the motor output shaft 21b of the electric motor 21 and on an extension of the motor output shaft 21b. It is unitized as a single part. The unitized rotary drive source 20 is connected via a metal adjustment nut (adjustment member) 30 attached to the outer periphery of the case 24 with the axis of the output shaft 23 parallel to the axis of the screw shaft 10. It is supported by the case mounting portion 1a of the device main body 1.

As shown in FIG. 406, the adjustment nut 30 has a substantially square outer shape and has a screw hole 30a in a portion that is a rotationally symmetrical axis, and the axis of the screw hole 30a matches the axis of the output shaft 23. In this state, it is screwed into a portion of the case 24 surrounding the output shaft 23. The case mounting portion 1a of the device main body 1 has a substantially square mounting hole 1b configured with an axis parallel to the axis of the screw shaft 10 as a rotationally symmetrical axis, into which an adjustment nut 30 can be fitted. It is formed to the dimensions.

A drive gear (power transmission mechanism) 25 is attached to the output shaft 23 of the rotational drive source 20 . The drive gear 25 is a spur gear having a smaller diameter than the input gear 16 and meshes with the input gear 16.

In the actuator configured as described above, when the electric motor 21 is driven, the rotation of the motor output shaft 21b is outputted to the output shaft 23 via the reduction mechanism 22, and the rotation of the output shaft 23 is transferred to the input gear via the drive gear 25. 16. Now, assuming that the rotational load applied to the screw shaft 10 is below the threshold value mentioned above, the rotation of the input gear 16 is transmitted to the screw shaft 10 via the press ring 17, and the rotation of the screw shaft 10 causes the plunger 15 to move toward the main body of the device. 1 and moved in a straight line. Therefore, although not shown in the figure, if a cartridge filled with a chemical solution is attached to the device main body 1 so as to be located at the tip of the plunger 15, and the electric motor 21 is driven from this state, the device main body 1 On the other hand, when the plunger 15 moves forward, the piston of the cartridge is pushed and moved, and the medicinal liquid sealed inside can be discharged from the tip of the injection needle. At this time, if the piston does not move due to a malfunction on the cartridge side, for example, and the rotational load on the screw shaft 10 becomes large and exceeds a threshold value, slippage occurs between the input gear 16 and the pressure ring 17, causing the actuator and cartridge to slip. It is possible to prevent situations that could cause damage to the equipment. Note that even after slipping occurs, if the rotational load on the screw shaft 10 becomes less than the threshold value, the rotation of the input gear 16 is transmitted to the screw shaft again, and the plunger 15 moves.

Here, in this actuator, as described above, the rotational drive source 20 is attached to the case attachment portion 1a of the device main body 1 via the adjustment nut 30. Therefore, if the required specifications such as the rotational speed and torque of the screw shaft 10 are changed, this can be done by changing the rotational drive source 20 without changing other parts. Moreover, even if the external dimensions of the new rotary drive source 20' do not match, by preparing an adjustment nut 30' that corresponds to the new rotary drive source 20', the case attachment part of the same device main body 1 can be adjusted. It becomes possible to attach it to 1a. In other words, if adjustment nuts 30' are prepared that are approximately square in size and have the same outer dimensions, but have different inner diameters for the screw holes 30a into which the rotational drive source 20 is screwed, they can be attached to the case mounting portion 1a of the device main body 1 as described above. becomes possible. This makes it possible to reduce manufacturing costs and prepare a plurality of types of actuators with different required specifications such as the rotational speed and torque of the screw shaft 10.

Moreover, if the screw hole 30a of the adjustment nut 30 is provided at a position that is a rotationally symmetrical axis of the outer shape, the axis of the output shaft 23 with respect to the axis of the screw shaft 10 can be adjusted before and after changing the rotational drive source 20. Since the center positions match, the drive gear 25 of the rotary drive source 20 can be meshed with the input gear 16 of the screw shaft 10 as is. Thereby, it is not necessary to prepare the device main body 1 and the input gear 16 according to the type of the rotary drive source 20, and it is possible to reduce manufacturing costs by sharing these parts.

Note that in the embodiment described above, an actuator suitable for an electric syringe that discharges a drug solution sealed in a cartridge by advancing and moving the plunger 15 is exemplified, but the present invention is not limited to this. In this case, the actuator only needs to include a driven shaft, and does not necessarily need to include a slide member.

Further, in the above-described embodiment, the rotary drive source 20 includes a built-in deceleration mechanism 22, but the present invention is not necessarily limited to this. Moreover, although the power transmission mechanism is illustrated as consisting of the input gear 16 and the drive gear 25, other power transmission mechanisms may be applied. Furthermore, although the example includes a torque limit mechanism, the present invention is not limited thereto.

Furthermore, in the embodiment described above, the adjustment member is configured to have an outer shape that is rotationally symmetrical about the axis of the output shaft 23 when attached to the case 24, and the inner shape of the case mounting portion 1a. However, since the adjustment nut 30 is configured to be rotationally symmetrical about the axis parallel to the axis of the driven shaft, the power transmission mechanism can also be shared as described above. However, the adjustment member and the case attachment portion 1a do not necessarily have to have a rotationally symmetrical shape.

1 Device main body 1a Case mounting part 3 Plunger opening 10 Screw shaft 11a Spiral groove 14 Nut 15 Plunger 16 Input gear 17 Pressing ring 18 Pressing spring 20 Rotation drive source 21 Electric motor 21b Motor output shaft 22 Reduction mechanism 23 Output shaft 24 Case 25 Drive Gear 30 Adjustment nut 30a Screw hole

Claims (7)

a driven shaft rotatably disposed inside the device body;
a rotary drive source installed in parallel with the device main body via a case in a state where the output shaft is parallel to the axis of the driven shaft;
a power transmission mechanism provided between the output shaft of the rotational drive source and the driven shaft, the drive of the rotational drive source rotates the driven shaft around the axis via the power transmission mechanism. An actuator configured to cause
The apparatus main body is provided with a case mounting part for supporting the case,
An adjustment member configured separately from the case attachment portion and the case is interposed between the case attachment portion and the case ,
The adjustment member is provided so as to surround the periphery of the case,
The actuator is characterized in that the case mounting portion is provided so as to surround the adjustment member . The adjustment member is configured to have an outer shape that is rotationally symmetrical about the axis of the output shaft when attached to the case,
2. The actuator according to claim 1 , wherein the inner shape of the case mounting portion is configured to be rotationally symmetrical about an axis parallel to the axis of the driven shaft. 3. The actuator according to claim 2 , wherein a support portion of the case to which the adjustment member is attached has an outer shape that is rotationally symmetrical about the axis of the output shaft. The actuator according to claim 1, wherein the power transmission mechanism includes a friction-type torque limit mechanism. The rotational drive source includes an electric motor and a speed reduction mechanism, and the final output shaft of the speed reduction mechanism is the output shaft, and the motor output shaft of the electric motor and the final output shaft of the speed reduction mechanism are The actuator according to claim 1, wherein the actuator is arranged on the same axis. The driven shaft has a spiral groove on the outer peripheral surface,
Claim 1, wherein the driven shaft is provided with a slide member that is slidable along the axial direction and that is screwed into the helical groove in a state where rotation around the axis is restricted. Actuator described in. The slide member is provided with a plunger,
7. The actuator according to claim 6 , wherein the device main body is provided with a plunger opening that exposes the plunger to the outside in a portion that is an extension of the driven shaft.

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