JP2010115111A - Linear actuator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To change a relationship between an amount of rotation of a rotating shaft of a motor section and an amount of movement of an output rod without modifying the motor section. <P>SOLUTION: A linear actuator includes a motor section 1 including a hollow rotating shaft 2 and an output rod 16-1 that passes through the hollow rotating shaft 2. The linear actuator moves the output rod 16-1 in a linear manner using the rotating movement of the hollow rotating shaft 2. The motor section 1 and a movement converting means that converts the rotating movement of the hollow rotating shaft 2 into the linear movement of the output rod 16-1 are modularized, and removably connected, respectively. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a linear actuator that converts rotational motion of a motor unit into linear motion of an output rod.

FIG. 4 is a longitudinal sectional view showing an example of a conventional linear actuator. In this linear actuator, the motor part A is composed of a hollow rotating shaft B, a rotor C integrally formed on the outer periphery of the rotating shaft B, and a stator D formed on the outer periphery of the rotor C. ing.
A ball screw shaft E, which is an output rod of the linear actuator, passes through the rotary shaft B and is screwed with a screw groove formed over the entire inner peripheral surface of the rotary shaft B via a steel ball F.
Therefore, when the rotating shaft B rotates by energizing the stator D of the motor part A, the ball screw shaft E linearly moves in the left-right direction. That is, the rotational motion of the rotary shaft B is converted into the linear motion of the ball screw shaft E.

Since the linear actuator has a configuration in which the ball screw shaft E is passed through the hollow rotary shaft B, the structure can be simplified and downsized.
However, since a screw groove for transferring the ball screw shaft E is formed on the rotary shaft B itself, there are the following problems.

That is, the relationship between the amount of rotation of the rotary shaft B and the amount of movement of the ball screw shaft E is defined by the pitch of both screws. Not only the pitch of the E screw but also the screw pitch of the rotating shaft B, which is a component of the motor part A, must be changed.
That is, in the conventional linear actuator structure, it is impossible to commonly use the motor part A when manufacturing the linear actuator of another specification described above, which causes an increase in product cost.
In view of such a situation, an object of the present invention is to provide a linear actuator that can change the relationship between the rotation amount of the rotation shaft of the motor unit and the movement amount of the output rod without modifying the motor unit. There is.

  A first invention includes a motor unit having a hollow rotary shaft and an output rod penetrating the hollow rotary shaft, and linearly moves the output rod by utilizing the rotational motion of the hollow rotary shaft. The linear actuator is configured to modularize the motor unit and motion conversion means for converting the rotational motion of the hollow rotary shaft into the linear motion of the output rod, and detachably connect them. Have

  According to a second invention, in the first invention, the motion converting means is detachably connected to a screw rod connected to one end of the output rod, a screw nut screwed to the screw rod, and the rotary shaft, Power transmission means for transmitting the rotational power of the rotating shaft to the screw nut.

  According to a third invention, in the first invention, the output rod is formed in a hollow shape, and the motion converting means is a screw nut provided on an inner peripheral surface of the output rod, and the screw nut is inserted into the output rod. And a power transmission means that is detachably connected to the rotary shaft and transmits the rotational power of the rotary shaft to the screw rod.

  According to a fourth invention, in the first invention, a thread groove is formed on a peripheral surface of the output rod, and the motion conversion means is detachably connected to a screw nut screwed to the output rod and the rotary shaft. And a power transmission means for transmitting the rotational power of the rotary shaft to the screw nut.

  Since the present invention has a configuration in which the motor unit and the motion converting means for converting the rotational motion of the hollow rotating shaft of the motor unit into the linear motion of the output rod are modularized and detachably connected to each other. When manufacturing another type of linear actuator having a different relationship between the rotation amount of the motor unit and the movement amount of the output rod, it is not necessary to modify the motor unit at all. Therefore, it is possible to use the motor unit as a common power module, thereby reducing the cost.

Sectional drawing which showed 1st Embodiment of the linear actuator which concerns on this invention. Sectional drawing which showed 2nd Embodiment of the linear actuator which concerns on this invention. Sectional drawing which showed 3rd Embodiment of the linear actuator which concerns on this invention. Sectional drawing which illustrated the structure of the conventional linear actuator.

  FIG. 1 shows an embodiment of a linear actuator according to the present invention. In this linear actuator, the motor unit 1 includes a hollow rotating shaft 2, a rotor 3 integrally formed on the outer peripheral surface of the rotating shaft 2, and a stator 4 provided around the rotor 3.

  The rotating shaft 2 has a small diameter portion 2a and a large diameter portion 2b. The small diameter portion 2 a is supported by the front housing 6 via the bearing 5, and the large diameter portion 2 b is supported by the rear housing 8 via the bearing 7. Nuts 9 and 10 are screwed onto the outer periphery of the rear end of the large diameter portion 2b, whereby the inner of the bearing 7 is fastened to the large diameter portion 2b.

Since the motor unit 1 has the above-described configuration, the rotating shaft 2 rotates together with the rotor 3 by exciting a field coil (not shown) provided in the stator 4.
A holder transformer 12 is fixed to the outer side surface of the nut 10 via bolts 11, and a holding block 14 is fixed to the inner side surface of the holder transformer 12 via bolts 13.
The holding block 14 is coaxially positioned in the end portion of the large-diameter portion 2 b of the rotary shaft 2, and a screw nut 15 is passed through and fixed to a central portion located on the axis of the rotary shaft 2.

  An output rod 16-1 is slidably inserted into the small diameter portion 2a of the rotating shaft 2. The front end of the output rod 16-1 is supported by the front housing 5 via a known rotation stop bush 17. The output rod 16-1 has a threaded rod 18 connected to the rear end thereof, and the threaded rod 18 is screwed to the threaded nut 15 of the holding block 14.

The linear actuator having the above-described configuration operates as follows. That is, when the rotating shaft 2 of the motor unit 1 rotates, the rotational force is transmitted to the holding block 14 via the nut 10 and the holder transformer 12, and as a result, the screw nut 15 fixed to the holding block 14 is rotated by the rotating shaft. Rotate with 2.
The screw rod 18 is prevented from rotating by the anti-rotation bush 17. For this reason, along with the rotation of the screw nut 15, axial thrust is generated in the screw rod 18, and as a result, the output rod 16-1 moves linearly in the left-right direction.

The linear actuator is used for linear movement of an object. Of course, positioning control of the output rod 16-1 is also possible, and an appropriate sensor for detecting the actual position of the output rod 16-1 is attached to the rear end or the like of the screw rod 18 at that time.
In addition, when adopting a usage pattern in which a guide member is fixed to the output rod 16-1 and the guide member is slid along an external sliding frame (not shown), the guide member and the sliding frame are output. It also has a function as a detent means for the rod 16-1. In this case, it is possible to use a known spline bush that does not have a detent function instead of the detent bush 17.

By the way, in the linear actuator, the screw nut 15 of the holding block 14 is given the same function without giving the rotary shaft 2 of the motor unit 1 the function as the screw nut means. The holding block 14 including the screw nut 15 is detachably provided on the rotary shaft 2 via the bolt 11 and the holder transformer 12.
Therefore, the motion conversion means including the screw rod 18 and the output rod 16-1 can be made independent of the motor unit 1 as a motion conversion module that converts the rotational motion into a linear motion. The holder transformer 12 and the holding block 14 have a function as power transmission means for transmitting the rotational power of the rotary shaft 2 to the screw nut 15.

According to said structure, when manufacturing the linear actuator of another specification from which the relationship between the rotation amount of the motor part 1 and the movement amount of an output rod differs, the change of the structure of the motor part 1 becomes unnecessary.
That is, when manufacturing the linear actuator of the different specification, the screw nut 15 and the screw rod 18 having a screw pitch suitable for each specification are adopted. Therefore, by preparing in advance a motion conversion module having a screw nut 15 and a screw rod 18 suitable for each specification, it is possible to cope with the specification change without any modification to the motor unit 1.
This means that the motor unit 1 in each type of linear actuator can be used as a common power module.

  FIG. 2 shows a second embodiment of the linear actuator according to the present invention. This linear actuator uses a hollow output rod 16-2 instead of the output rod 16-1 shown in FIG. 1, and the output rod 16-2 is separate from the output rod 16-2. The screw rod 20 is inserted so as to be movable.

The output rod 16-2 is slidably inserted into the rotating shaft 2 of the motor unit 1. A screw nut 21 is detachably fitted on the inner peripheral surface of the rear end. On the other hand, the screw rod 20 is screwed into the screw nut 21 of the output rod 16-2, and the base portion is fitted to the central portion of the holding block 22.
The holding block 22 has the same shape as the holding block 14 shown in FIG. 1, and is fixed to the inner surface of the holder transformer 12 via the bolt 13 in the same manner as the holding block 14.

  In this linear actuator, the rotational force of the rotating shaft 2 of the motor unit 1 is transmitted to the screw rod 20 via the holder transformer 12 and the holding block 22. Accordingly, the screw rod 20 rotates together with the rotary shaft 2, and as a result, a thrust is generated in the screw nut 21 screwed to the screw rod 20, and the output rod 16-2 moves linearly in the left-right direction.

  According to this linear actuator, the screw rod 20 and the screw nut 21 can be modularized as a motion converting means for converting a rotational motion into a linear motion. Therefore, the effect similar to that of the linear actuator shown in FIG. Is advantageous in that it is possible to cope with the specification change without any modification.

Further, since the screw rod 20 is accommodated in the output rod 16-2, it is advantageous for preventing the screw rod 18 from being dust-proof, and even when the output rod 16-2 is retracted as shown, the holder transformer Since the output rod 16-2 does not protrude to the rear side of 12, there is no need to secure an interference avoidance space on the rear side, and the degree of freedom of arrangement is high accordingly.
Note that the fact that the output rod 16-2 does not protrude rearward is advantageous in improving the safety of the user.

  Since the linear actuators shown in FIGS. 1 and 2 have no thread grooves formed on the peripheral surfaces of the output rods 16-1 and 16-2, the output rods 16-1 and 16-2 are rotated. It is also possible to equip the outside with a regulating means, which is advantageous in expanding the user's selection range.

FIG. 3 shows a third embodiment of the linear actuator according to the present invention. This linear actuator uses an output rod 16-3 made of a known ball screw rod in place of the output rod 16-1 shown in FIG.
The output rod 16-3 is movably inserted into the rotating shaft 2 of the motor unit 1. The front end portion is supported on the front housing 5 via a known ball spline nut 23 and the rear end portion is screwed into a known ball screw nut 24.
The ball screw nut 24 is coaxially positioned in the large-diameter portion 2 b of the hollow rotary shaft 2 and is fixed to the inner surface of the holder transformer 12 via a bolt 13.

In this linear actuator, the rotational force of the rotating shaft 2 of the motor unit 1 is transmitted to the holder transformer 12 and the ball screw nut 24, so that the ball screw nut 24 rotates together with the rotating shaft 2.
Since the rotation of the output rod 16-3 is suppressed by the ball spline nut 23, the output rod 16-3 linearly moves in the left-right direction as the ball screw nut 24 rotates.

According to the linear actuator of this embodiment, the ball screw nut 24 and the output rod 16-3 can be modularized as motion conversion means for converting rotational motion into linear motion. Therefore, the linear actuator shown in FIGS. Similar to the actuator, there is an effect that the motor unit 1 can cope with the specification change without any change.
Moreover, since a general-purpose screw rod or a ball screw rod can be used as the output rod 16-3, it is possible to answer various user requirements regarding cost, function, and the like.
Since this linear actuator incorporates a sensor 25 such as a pulse encoder that outputs a pulse signal corresponding to the amount of rotation of the rotary shaft 2, the positioning of the output shaft 16-3 is based on the output pulse of this sensor 25. Control and speed control can be performed.

DESCRIPTION OF SYMBOLS 1 Motor part 2 Hollow rotary shaft 2a Large diameter part 2b Small diameter part 3 Rotor 4 Stator 6 Front housing 8 Rear housing 9, 10 Nut 11, 13 Bolt 12 Holder transformer 14 Holding block 15 Screw nut 16-1 to 16-3 Output Rod 17 Non-rotating bush 18 Screw rod 20 Screw rod 21 Screw nut 22 Holding block 23 Ball spline nut 24 Ball screw nut

Claims (4)

A linear actuator comprising a motor unit having a hollow rotary shaft and an output rod penetrating the hollow rotary shaft, and linearly moving the output rod using the rotational motion of the hollow rotary shaft Because
A linear actuator characterized in that the motor unit and a motion conversion means for converting the rotational motion of the hollow rotary shaft into the linear motion of the output rod are modularized and detachably connected.   The motion converting means is a screw rod connected to one end of the output rod, a screw nut screwed to the screw rod, and a removably connected to the rotating shaft, and power for transmitting the rotational power of the rotating shaft to the screw nut. The linear actuator according to claim 1, further comprising a transmission unit.   The output rod is formed in a hollow shape, and the motion conversion means is attached to and detached from the rotary shaft, a screw nut provided on the inner peripheral surface of the output rod, a screw rod inserted into the output rod and screwed into the screw nut, and The linear actuator according to claim 1, further comprising: a power transmission unit that is freely connected to transmit the rotational power of the rotary shaft to the screw rod.   A thread groove is formed on a peripheral surface of the output rod, and the motion conversion means is detachably connected to the rotation shaft and a rotation nut of the rotation shaft to the rotation nut. The linear actuator according to claim 1, further comprising power transmission means for transmitting.

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