JP2000213615A - Motor-driven cylinder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a miniaturized motor-driven cylinder. SOLUTION: The miniaturized motor-driven cylinder consists of an induction motor 4 having a hollow rotor 3 and a stator 2, a screw shaft 5 which is arranged in the hollow part of the hollow rotor 3 and which is rotated integrally with the hollow rotor 3, a hollow shaft 6 arranged in the hollow part of the hollow rotor 3 so that it can appear and disappear in the axial direction, and a nut 7 which is locked to the hollow shaft 6 to be threadedly engaged with the screw shaft 5. Then, a motor control device 20 is attached to the rear part.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to an electric cylinder.

[0002]

2. Description of the Related Art An electric cylinder for converting the rotation of an electric motor into a linear reciprocating motion of a cylinder rod by a ball screw mechanism or the like is known from Japanese Patent Application Laid-Open Nos. 10-281253 and 10-127008. It is also known from Japanese Patent Application Laid-Open No. 8-261208 and the like to use a spirally magnetized magnetic screw and a magnetic nut instead of a ball screw mechanism to convert a rotary motion into a linear reciprocating motion. .

[0003]

However, the conventional electric cylinder has the following problems. When the electric motor part where the rotor rotates and the cylinder part where the rod moves linearly are connected in series in the axial direction, the axial size of the electric cylinder is almost the sum of the length of the electric motor and the length of the cylinder. Requires a large space for installation. When the electric motor and the cylinder are arranged in parallel and the rotation of the rotor of the electric motor is transmitted to the cylinder by a belt or the like, the size of the electric cylinder increases in a direction orthogonal to the axis. In addition, the motor control device for the electric cylinder is provided on a control panel installed at a position distant from the electric cylinder, so that the adjustment of the electric cylinder and the adjustment of the control panel cannot be performed at one place, which is inconvenient. . An object of the present invention is to reduce the size of an electric cylinder. It is another object of the present invention to integrate the motor control device with the electric motor to make adjustment easier.

[0004]

The present invention to achieve the above object is as follows. (1) An induction motor having a hollow rotor and a stator, a screw shaft disposed in the hollow portion of the hollow rotor and rotating integrally with the hollow rotor, and disposed so as to be able to protrude and retract in the hollow portion of the hollow rotor in the axial direction. An electric cylinder, comprising: a hollow shaft formed as described above; and a nut fixed to the hollow shaft and screwed with the screw shaft. (2) a switch actuating means fixed to the hollow shaft; a forward end switch provided on the stator corresponding to a position of the switch actuating means when the hollow shaft is at a forward end or a backward end; The electric cylinder according to (1), further comprising: a switch. (3) The electric cylinder according to (1), wherein the male screw of the screw shaft and the female screw of the nut are magnetic screws. (4) The electric cylinder according to (1), wherein the male screw of the screw shaft and the female screw of the nut are mechanical screws. (5) The electric cylinder according to (2), further including a motor control device attached to the electric cylinder. (6) The electric cylinder according to (5), wherein the motor control device is attached to a rear part of the electric cylinder and also serves as a cover on a rear part of the electric cylinder.

[0005] In the electric cylinder of the above (1), the rotor is made hollow, a hollow shaft is inserted into the hollow portion of the rotor so as to be able to protrude and retract in the axial direction, the screw shaft is pushed into the hollow shaft, and the screw shaft and the nut are used in the axial direction. Since the hollow shaft is moved, the rotor, hollow shaft, and screw shaft can be arranged in parallel with each other, and the size of the electric cylinder is reduced in the axial direction compared to the conventional configuration in which these are connected in series. Can be In the electric cylinder of (2), the forward end switch and the backward end switch are provided on the stator side, and the switch operating means is provided on the hollow shaft side. Therefore, it is automatically detected that the hollow shaft has reached the forward end and the backward end. be able to. The electric cylinder described in (3) above is a case where a magnetic screw is magnetized in a spiral shape on a screw shaft and a nut, and the screw is a magnetic screw. In the electric cylinder of (4), the screw of the screw shaft and the nut is a mechanical screw formed by cutting or rolling. In the electric cylinder described in (5), since the motor control device is attached to the electric cylinder, adjustment of the control device can be performed at one position of the electric motor. Adjustment is more convenient than in the previous case. The above (6)
In the electric cylinder, since the motor control device is attached to the rear portion of the electric cylinder, the hollow rotor is not exposed from the rear side, and the motor control device can also serve as a cover on the rear side of the electric cylinder. The number of parts can be reduced as compared with the case where the rear cover is provided.

[0006]

FIG. 1 shows an electric cylinder according to a first embodiment of the present invention, and FIGS. 2 to 4 show electric cylinders according to a second embodiment of the present invention. Parts that are common or similar in both embodiments are given the same reference numerals in both embodiments.

First, common or similar parts across the electric cylinders of all embodiments of the present invention will be described with reference to FIG.
explain. An electric cylinder 1 according to an embodiment of the present invention includes an induction motor 4 having a stator 2 and a hollow rotor 3 (also referred to as a hollow rotor) that is rotated with respect to the stator 2 and cannot move in the axial direction. Screw shaft 5 which is arranged in the part and rotates integrally with the hollow rotor 3 and is not movable in the axial direction.
And a non-rotatable hollow shaft 6 disposed in the hollow portion of the hollow rotor 3 so as to be movable in the axial direction so as to be able to protrude and retract in the axial direction, and screwed to the screw shaft 5 fixed to the hollow shaft 6 (screw connection) May be a magnetic screw connection or a mechanical screw connection). Screw shaft 5
Projects into the hollow portion of the hollow shaft 6 and is relatively movable in the axial direction with respect to the hollow shaft 6. Hollow rotor 3
Is a cylinder body of the cylinder part of the electric cylinder 1,
The hollow shaft 6 is a rod of a cylinder part of the electric cylinder 1. The nut 7 is movable in the axial direction together with the hollow shaft. The screw shaft 5 and the nut 7 are mechanisms by which the hollow rotor 3 converts a rotational motion into a linear motion of the hollow shaft 6. The front end of the hollow portion of the hollow shaft 6 is closed.

The electric cylinder 1 according to the embodiment of the present invention includes a switch operating means 8 (for example,
And a forward end switch 9 fixedly provided on the stator 2 side corresponding to the position of the switch actuating means 8 (for example, a magnet) when the hollow shaft 6 is at the forward end and the backward end of the stroke. And an end switch 10. Forward end switch 9, Reverse end switch 10
A proximity switch that responds to the The switch actuating means may be a magnet or something other than a magnet, for example, if the proximity switch is a limit switch, it may be a projection that strikes the limit switch. The male screw of the screw shaft 5 and the female screw of the nut 7 may be a magnetic screw or a mechanical screw (including a screw formed by cutting and a screw formed by rolling). In the case of a mechanical screw, a ball screw mechanism may be used. If the screw is a magnetic screw and the proximity switch is a magnetically responsive switch, the hollow shaft 6 is preferably made of aluminum. The reason is that the forward end switch 9,
This is to make it difficult for the backward end switch 10 to respond to the magnetism of the screw.

Next, the operation of the common or similar parts of the electric motor according to all the embodiments of the present invention will be described. When the hollow rotor 3 is rotated in the induction motor 4, the screw shaft 5 is rotated integrally therewith. When the screw shaft 5 rotates, the nut 7 and the hollow shaft 6 to which the nut 7 is fixed linearly move by the screw shaft 5 and the nut 7, and move forward or backward.

In the electric cylinder 1, the rotor 3 is hollow, and the hollow shaft 6 is inserted into the hollow portion of the rotor 3 so as to be able to protrude and retract in the axial direction. The screw shaft 5 is inserted into the hollow shaft 6, and the screw shaft 5 and the nut 7 Since the hollow shaft 6 is moved in the axial direction, the rotor 3, the hollow shaft 6, the screw shaft 5
Can be arranged in parallel with each other. Therefore, the size of the electric cylinder 1 can be reduced in the axial direction as compared with the conventional configuration in which these are connected in series.

When the forward end switch 9 and the backward end switch 10 are provided on the stator 2 side and the magnet 8 is provided on the hollow shaft 6 side, when the hollow shaft 6 comes to the forward end and the backward end by the stroke, the magnet 8 is turned off. Since the forward end switch 9 and the backward end switch 10 are operated in response to the magnetic field lines, it is possible to automatically detect that the hollow shaft 6 has reached the forward end and the backward end. This can be used for automating the operation of the electric cylinder 1.

When the screw of the screw shaft 5 and the nut 7 is a magnetic screw, the magnetic screw is a screw formed by helically magnetizing two threads of an N pole and an S pole, and does not need to have irregularities. In addition, since the size in the radial direction can be kept small, and slip occurs when an excessive axial load is applied, the components can be protected. The screw shaft 5 and the nut 7
Is a mechanical screw, the mechanical screw does not slip in the axial direction, so that the rotation of the rotor 3 and the feed amount of the hollow shaft 6 reliably correspond to each other. In addition, by closing the front end of the hollow portion of the hollow shaft 6, the screw portion is shut off from the outside, and it is possible to prevent the occurrence of operation failure due to the invasion of foreign matter.

Next, the configuration and operation of the parts unique to each embodiment of the present invention will be described. The first embodiment of the present invention is as shown in FIG. 1 and has the configuration and operation as described in the common or similar parts to all the embodiments of the present invention.

In the second embodiment of the present invention, as shown in FIGS. 2 to 4, the electric cylinder 1 further has a motor control device 20 attached to the electric cylinder. The motor control device 20 is such that a part or all of a motor control unit conventionally provided in a control panel is incorporated in the motor control device 20. The motor control device 20 is desirably attached to the rear part of the electric cylinder 1 (the side where the hollow shft 6 protrudes and retracts is the front part, so the opposite part), and also serves as a cover for covering the hollow rotor 3 from the rear part. I have.

FIG. 3 shows a hardware configuration of the motor control device 20. The motor control device 20 rotates the hollow rotor 3 forward (forward rotation of the rotor corresponds to forward movement of the shaft 6).
Forward switch 31, reverse rotation of hollow rotor 3 (reverse rotation of rotor corresponds to retreat of shaft 6) reverse rotation switch 32,
A signal processing unit 33 for determining the input of the forward motion command signal 38 and the backward motion command signal 39 of the shaft 6; an operation determining unit 34 for performing the next determination when the determination of the signal processing unit 33 is ON; The forward rotation switch 31 is executed when the forward end switch 9 is ON, the forward rotation switch 31 is executed when the forward end switch 9 is OFF, and the reverse rotation switch is executed when the backward end switch 10 is ON. 32 OFF and the backward end switch 10 is turned off.
In the case of F, the operation control unit 36 for executing the reverse rotation switch 32 ON, the current detection unit 3 for detecting the current from the three-phase power supply 37
5.

The operation determining section 34 and the operation control section 36 have a program for executing the control of the flowchart of FIG. 4 incorporated therein. Referring to FIG. 4, in step 41, the motor control program is interrupted. At step 42, a forward command is turned on by a command from the control panel (controller).
Is determined, and if YES, the process proceeds to step 44 and N
If O, proceed to step 43. Similarly, at step 43, the reverse command is set to O from the command from the control panel (controller).
N is determined, and if YES, the process proceeds to Step 45,
If NO, the process returns to step 41. In step 4, it is determined whether or not the forward end switch 9 is ON. If YES, the flow advances to step 46 to execute the normal rotation switch 31OFF. If NO, the flow advances to step 47 to execute the normal rotation switch 31ON.
Similarly, in step 5, it is determined whether or not the backward end switch 10 is ON. If YES, the process proceeds to step 49 to execute the reverse rotation switch 32OFF. If NO, the process proceeds to step 48 to execute the reverse rotation switch 32ON.

With respect to the operation of the second embodiment of the present invention, the motor control device 20 for executing the above processing is attached to the electric cylinder 1 so that the control device conventionally separated and installed in the control panel can be replaced with the electric cylinder. Since it is integrated into one, adjustment of the control device can be performed at one place of one electric cylinder, and the work and adjustment are easy and convenient. In addition, by attaching the motor control device 20 to the rear portion of the electric cylinder 1, the motor control device 20 can also serve as a cover that covers the hollow rotor 3 from the rear portion. The number of parts is reduced.

[0018]

According to the electric cylinder of the first aspect, the rotor is hollow, the hollow shaft is inserted into the hollow portion of the rotor so as to be able to protrude and retract in the axial direction, and the screw shaft is inserted into the hollow shaft. The shaft and the screw shaft can be arranged in parallel with each other, and the size of the electric cylinder can be reduced in the axial direction as compared with the conventional configuration in which these are connected in series. According to the electric cylinders of claims 2 to 6, in addition to the above effects, the following effects can be obtained. According to the electric cylinder of the present invention, since the forward end switch and the backward end switch are provided on the stator side and the magnet is provided on the hollow shaft side, it is possible to automatically detect that the hollow shaft has reached the forward end and the backward end. Can be. According to the electric cylinder of claim 3,
Since the screw is a magnetic screw, there is no need to provide unevenness,
An increase in the size of the electric cylinder in the radial direction can be suppressed. According to the electric cylinder of claim 4,
Since the screw is a mechanical screw, the rotation of the rotor and the stroke of the shaft can be accurately matched. According to the electric cylinder of claim 5, since the motor control device is attached to the electric cylinder, adjustment of the control device can be performed at one position of the electric motor portion, and is performed at two positions of the electric motor and the control panel. Adjustment is more convenient than in the case. According to the electric cylinder of the sixth aspect, since the motor control device is attached to the rear portion of the electric cylinder, the hollow rotor is not exposed from the rear side, and the motor control device also serves as a cover on the rear portion of the electric cylinder. Therefore, the number of components can be reduced as compared with the case where a rear cover is separately provided.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of an electric cylinder according to a first embodiment of the present invention.

FIG. 2 is a schematic sectional view of an electric cylinder according to a second embodiment of the present invention.

FIG. 3 is a block diagram of a motor control device for an electric cylinder according to a second embodiment of the present invention.

FIG. 4 is a control flowchart of a motor control device for an electric cylinder according to a second embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Electric cylinder 2 Stator 3 Rotor (hollow rotor) 4 Induction motor 5 Screw shaft 6 Hollow shaft (shaft) 7 Nut 8 Switch operating means (for example, magnet) 9 Forward end switch 10 Reverse end switch 20 Motor control device 31 Forward rotation switch 32 reverse switch 33 signal processing unit 34 operation determination unit 35 current detection unit 36 operation control unit

Continued on the front page F term (reference) 5H303 AA30 BB01 BB06 BB11 DD01 DD11 DD25 DD30 FF01 GG02 HH02 HH09 MM02 5H607 AA12 BB01 BB14 BB23 CC03 DD04 DD11 EE53 HH06 HH09

Claims (6)

[Claims] 1. An induction motor having a hollow rotor and a stator, a screw shaft arranged in a hollow portion of the hollow rotor and rotating integrally with the hollow rotor, and capable of protruding and retracting in the hollow portion of the hollow rotor in an axial direction. And a nut fixed to the hollow shaft and screwed to the screw shaft. 2. A switch operating means fixed to said hollow shaft, a forward end switch provided on a stator side corresponding to a position of said switch operating means when said hollow shaft is at a forward end and a backward end, The electric cylinder according to claim 1, further comprising a rear end switch. 3. The electric cylinder according to claim 1, wherein the male screw of the screw shaft and the female screw of the nut are magnetic screws. 4. The electric cylinder according to claim 1, wherein the male screw of the screw shaft and the female screw of the nut are mechanical screws. 5. The electric cylinder according to claim 2, further comprising a motor control device attached to the electric cylinder. 6. The electric cylinder according to claim 5, wherein the motor control device is attached to a rear portion of the electric cylinder and also serves as a cover on a rear side of the electric cylinder.