JP2005321029A - Linear actuator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a linear actuator, securing a fixed moving stroke area S1 (S) in a rotor 3 even in the case of a structure in which a projection area is not entirely secured or enough secured on the outside of the actuator on the output shaft 4 rear side, for example, the rear end side of the output shaft 4 by sealed by a partition 53 while the output shaft 4 is composed of a threaded shaft part 41 and a whirl-stop shaft part 42. <P>SOLUTION: In the shaft hole 31, a screw carving part 311 formed in one side area and engaged with the screw carving part 41 and a guide part 313 for guiding a whirl-stop shaft part 42 formed in the other side area at a predetermined intermediate area 312 in the state of regulating the rotation are respectively provided in the divided areas to move forward and backward the whirl-stop shaft part 42 in a moving stroke area in the shaft hole 31. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a linear actuator in which an output shaft screwed into a central shaft hole of a rotor is reciprocally driven by a screw feed mechanism accompanying rotation of the rotor without rotating between predetermined strokes.

In general, this type of direct acting actuator (motor) consists of a screw shaft and a non-rotating shaft notched in a circular arc (D) shape, and the non-rotating shaft is the bearing part of the motor case. Is inserted into the D-shaped rotation restricting hole provided in the guide, and the anti-rotation part protrudes from the motor. When the motor case side is set on the base, the output shaft moves forward and backward, and the output When the shaft is fixed, the motor case itself moves forward and backward (see Reference 1, FIG. 3).
For example, this configuration can be used when a sealed structure with a flow path in a refrigeration device, a boiler, or the like is required, or when other functional members such as a sensor are disposed on the axis of the detent shaft. The desired projecting stroke area of the output shaft on the side (non-rotating shaft portion) cannot be secured (reference document 2, reference document 3).

Therefore, a conventional linear actuator is fixed to a sleeve (15) integrally provided in a rotor (C) as a rotor in a stepping motor structure, for example, as disclosed in Reference Document 2. A tubular needle valve (5) as an output shaft is inserted into the shaft stop (23), and the internal thread (21) 21) provided on the inner periphery of the rotor (C) is rotated and raised by the rotor (C). This has been dealt with by a configuration in which the needle valve (5) is opened and closed by a screw feed action with a male screw pipe (18) provided on the outer periphery of the needle valve (5).
However, in the case where the needle valve (5) is driven to move up and down depending on the rotation of the rotor (C), the moving stroke is not generated due to the movement of the rotor (C) up and down. A rotor that is elongated in the vertical direction only has to be manufactured, and the output shaft is composed of a plurality of members such as a joint structure between the shaft stopper (23) and the tubular needle valve (5) and a male screw pipe (18). In addition, the upper and lower limit regulating pins (30, 30 ′) of the rotor (C) are provided, resulting in a problem that the number of parts is large and the structure is complicated. Furthermore, in this case, the flow rate of a fluid such as a refrigerant in a relatively narrow flow path is controlled, and the valve opening and closing can be used for a short stroke of about several millimeters, but about 10 to 30 mm. There is a problem that it is structurally difficult to adopt for those requiring a long stroke reciprocating drive.

Japanese Patent Laid-Open No. 10-38075 JP-A-9-196194 Japanese Patent Laid-Open No. 2001-231241

  The present invention was devised to eliminate the above-described problems, and even if a structure that cannot secure a projecting area to the outside of the actuator on the rear end side of the output shaft is forced. Provided is a direct acting actuator that can secure a constant moving stroke area in the rotor and can drive a relatively long stroke by non-rotating without reciprocating the output shaft especially outside the yoke. The purpose is to do.

  The technical means employed by the present invention in order to solve the above-described problems include a stator that forms a cylindrical yoke, a multipole magnetized rotor that is rotatably provided in the stator, and a center of the rotor. A linear motion actuator that includes an output shaft that is screwed into a shaft hole and is capable of moving forward and backward along with its rotation, wherein the output shaft is formed by a threaded shaft portion and a non-rotating shaft portion, In the shaft hole, a threaded portion formed in one side region and screwed with the threaded shaft portion, and a rotation shaft portion formed in the other side region with a predetermined intermediate region are rotated. Guide portions that are guided in a restricted state are divided into regions, and the shaft holes are formed so that the output shaft has the screw shaft portion and the rotation shaft portion in the middle region, and the rotation in the guide portion region. The stop shaft is configured to move forward and backward as the movement stroke area in each shaft hole. It is characterized in.

In the linear motion actuator according to the present invention, the output shaft that is screwed into the shaft hole of the rotor and reciprocally driven is constituted by a general screw shaft portion and a rotation stop shaft portion. Even if it is forced to have a structure that does not provide a protruding area outside the actuator on the rear end side of the shaft, or a structure that does not ensure sufficient, a constant moving stroke area can be secured in the rotor. The reciprocating drive of the output shaft can be performed only by the stroke area in the rotor or by setting the joint stroke area with the space area that can be secured outside the yoke, and it is not necessary to secure an unnecessary area outside the yoke. The whole apparatus can be simplified and made compact.

DESCRIPTION OF THE PREFERRED EMBODIMENTS A linear actuator that exemplifies an embodiment of the present invention as a preferred embodiment will be described below in detail with reference to the drawings.
FIG. 1 is an overall configuration diagram of a linear motion actuator. As shown in the figure, reference numeral 1 denotes a linear motion actuator having a stepping motor structure. The linear motion actuator 1 has a cylindrical shape in which a coil bobbin 201 and an excitation coil 202 are mounted on a pair of yoke blocks 21 and 21, respectively. Yoke (stator) 2, a multi-pole magnetized rotor 3 rotatably provided in the yoke 2, and screwed into the central shaft hole 31 of the rotor 3, and moves forward and backward as it rotates. A possible output shaft 4 is provided.
The yoke 2 is formed of iron, magnetic stainless steel or the like, and a plurality of concave and convex pole teeth (not shown) corresponding to the magnetic pole spacing of the rotor 3 are formed at a constant pitch on the inner peripheral surface of the yoke block 21. A so-called two-phase coil unit is configured, and the yoke blocks 21 and 21 are assembled with their pole teeth displaced by a step angle.
Further, the rotor 3 is disposed on a cylindrical body 32 made of resin, such as resin, brass, copper, or aluminum having a shaft hole 31 at the center thereof, and an outer peripheral surface of the body 32. A ring-shaped magnet (which may be a hysteresis material (semi-hard magnetic material)) 33 in which S poles and N poles alternately magnetized are alternately provided, and the output shaft 4 has a shaft length. The screw shaft portion 41 as a male screw is formed in the first half portion, the rotation shaft portion 42 is formed in the second half portion, and the rotor 3 is excited by exciting the pole teeth to a predetermined polarity of S or N. The output shaft 4 is configured to rotate and reciprocate by advancing and retracting a predetermined stroke by a feed screw mechanism. These configurations are generally known techniques as a basic configuration of a linear motion actuator.

  In the embodiment shown in FIG. 1, the flow rate of the linear actuator 1 according to the present invention is controlled by closing and opening the gas flow path 51 of the boiler by the valve body 52 provided at the tip of the output shaft 4. It is provided in the flow rate control device 5 and is firmly screwed through a mounting motor flange 22 integrally provided on the lower surface of the yoke 2, and the inner peripheral surface of the yoke 2, the rotor 3 and the like. In this gap, a cylindrical lid-shaped partition wall 53 formed of a nonmagnetic metal is interposed and sealed so that the rear end side of the output shaft 4 is fitted, and the gas from the flow path 51 to the outside of the yoke 2 is sealed. Prevents leakage and prevents leakage. The partition wall 53 is formed of a peripheral surface portion 531 and a cover surface portion 532 that is fixedly fitted to the peripheral surface portion. The rotor 3 is inserted into the partition wall 53 from the rear end side of the output shaft 4. Then, it is mounted so as to be fitted, assembled into the flow control device 5 for assembly, and the yoke 2 is fitted and set.

  On the other hand, in the shaft hole 31, a threaded portion 311 that is formed in one side (front side) region and is screwed with the threaded shaft portion 41, and an inner diameter larger than the threaded portion 311. A guide portion 313 that guides the non-rotating shaft portion 42 formed in the other side (rear side) region in a rotation-restricted state with a predetermined intermediate region 312 formed in the space, respectively, is a shaft hole region. The output shaft 4 is provided with the screw shaft portion 41 and the non-rotating shaft portion 42 in the intermediate region 312 and the non-rotating shaft portion 42 in the guide portion 313 region. Each shaft hole is configured to move forward and backward as a moving stroke area. The threaded portion 311 may be provided on the rear side, the guide portion 313 may be provided on the front side, and the threaded shaft portion 41 and the rotation preventing shaft portion 42 may be reversely arranged.

  In other words, the guide portion 313 is formed in a cylindrical shape into which the anti-rotation shaft portion 42 is inserted in the lower surface area of the lid surface portion 532 of the partition wall 53, and has a guide groove 313 a formed so as to face the axial direction of the inner periphery thereof. The guide piece 421 provided at the rear end portion of the detent shaft portion 42 is slidably guided in the guide groove 313a by being inserted into the shaft hole 31. In particular, in this embodiment, since the movement stroke of the output shaft 4 is set to about 25 mm, the setting of the movement stroke area S of the guide portion 313 is set to the inner area S1 of the shaft hole 31 and the inner area S2 of the partition wall 53. When the movement stroke is set to about 15 mm, it is not necessary to extend the lid surface portion 532 of the inner region S2 of the partition wall 53. Further, a stopper piece 43 for restricting upper and lower limits is provided at a boundary portion between the threaded shaft portion 41 and the non-rotating shaft portion 42. The stopper piece 43 has an output shaft 4 having a maximum stroke S (the dotted line portion shown in the figure). In order to improve safety, it is provided as necessary to stop the step-out when there is an abnormality exceeding (including).

Reference numeral 6 denotes a magnet provided at the rear end of the output shaft 4 (non-rotating shaft portion 42). The magnet 6 is connected to a communication hole 61 formed in communication with the stroke S2 region of the guide portion 313. The non-rotating shaft portion 42 is inserted by moving the valve body 52 to the uppermost position (reverse) beyond the normal opening / closing stroke S for flow control, and when it reaches a predetermined position, it is provided at an arbitrary position on the outer periphery of the guide portion 313. A sensor (including a ferromagnetic sensor) 62 detects the magnetism of the magnet 6 in the partition wall 53 and generates a voltage to detect the origin position. The detection operation of the magnetic sensor 62 as the origin detection sensor is to recognize the origin position by resetting the operation start position when the power is turned on or when an abnormality due to any cause or power down occurs due to the characteristics of the stepping motor. is there. If a servo motor is used, it is unnecessary because it is performed by a built-in encoder.

  In the form of the embodiment of the present invention configured as described above, the valve body 52 provided at the tip of the output shaft 4 is now screwed with the rotation of the threaded portion 311 by the rotation of the rotor 3. It is transmitted to the engraved shaft portion 41 as a thrust, and is moved forward and backward between predetermined strokes for closing and opening the flow path 51, and the flow rate of the gas is controlled by the opening displacement. The actuator 1 is formed in the shaft hole 31 on the other side region with a threaded portion 311 formed in one side region thereof and screwed with the threaded shaft portion 41, and a predetermined intermediate region 312. A guide portion 313 for guiding the non-rotating shaft portion 42 in a rotation-restricted state is provided to be divided into regions, and the shaft hole 31 has the output shaft 4 in the middle region 312 and the screw shaft portion 41 in the middle region 312. And the detent shaft portion 42 in the guide portion 313 area S. The serial detent shaft portion 42, are constructed so as to advance and retreat without rotation as a respective shaft holes 31 within the movement stroke range.

  Therefore, the output shaft 4 screwed into the shaft hole 31 of the rotor 3 and driven to reciprocate is constituted by a general screw shaft portion 41 and a rotation stop shaft portion 42. In this way, the structure is incapable of securing a protruding region outside the actuator on the rear end side of the output shaft 4 at all or sufficiently, such as being provided in the flow control device 5 and sealing the rear end side of the output shaft 4 by the partition wall 53. Even if it is done, a certain movement stroke area S1 (S) can be secured in the rotor 3. That is, the opening / closing stroke of the valve body 52 may be set to a very short opening / closing stroke of about several millimeters for the flow control of the fluid (refrigerant) in the relatively thin flow path 51 such as the refrigeration equipment. Can be handled only by the stroke area S1 in the rotor of the guide portion 313, and a long stroke setting of about 10 to 30 mm is used for flow control of fluid (refrigerant) in a relatively thick flow path 51 such as a boiler. Therefore, for example, in the case of 15 mm or less, the setting of the guide portion 313 area stroke S is set only in the rotor inner stroke area S1, and in the case of 15 mm or more, the common stroke area is allocated to the partition wall 53 inner area stroke S2. This can be handled by setting (S1 + S2), and it is not necessary to secure an unnecessary area outside the yoke. As a result, not only a short stroke but also a long stroke can be dealt with, and the rotor itself is raised and lowered as in the prior art, and the output shaft has a joint structure with two members of a shaft body and a tubular body. Thus, the increase in the number of parts and the complexity of the structure due to such as can be avoided, and the entire apparatus can be simplified and made compact.

  Further, the guide portion 313 has a guide groove 313a formed in the axial direction, and a guide piece 421 provided on the detent shaft portion 42 slides along the guide groove 313a. Therefore, there is no problem of meshing due to misalignment of the screw shaft due to screwing tolerance or rotation blur caused by the fitting configuration of a general D-shaped or long-diameter shaft and the shaft hole, and the stroke. It is possible to smoothly guide between S with the rotation restricting member, and the output shaft 4 (valve body 52) can be driven to reciprocate without rotation without causing blurring.

  Moreover, although the guide portion 313 may be provided directly in the shaft hole 31, the guide portion 313 is provided as a separate member on the lower surface region of the lid surface portion 532 in the partition wall 53, and is inserted into the shaft hole 31. Even if different settings are required for the setting of the moving stroke S depending on the specifications such as the flow rate control, only the guide portion 313 needs to be manufactured and changed, and the stroke of the linear actuator 1 of any size can be achieved. Variations can be achieved by preparing several types with different settings. Furthermore, even if a long set stroke S that cannot be formed only by the stroke S1 in the shaft hole 31 is required, it can be dealt with by setting a joint stroke area (S1 + S2) allocated to the inner stroke S2 of the partition wall 53. The shape of the partition wall 53 may be arbitrarily changed, for example, by making the cross-section substantially U-shaped and integrally molding the peripheral surface portion 531 and the cover surface portion 532. At that time, the guide portion 313 provided in the lower surface area of the lid surface portion 532 is formed by a separate member and provided in the partition wall 53.

Further, while the magnet 6 is provided at the rear end of the output shaft 4, when the output shaft 4 is most moved (reversed) and the magnet 6 approaches, the origin is detected to detect the displacement of the magnetic flux density and generate a voltage. Since the magnetic sensor 62 for detection is provided, the characteristic of the magnetic sensor 62 can be used to provide the lid surface portion 532 outside the partition wall 53, and the sensor is disposed inside the partition wall 53. It is possible to perform the home return operation.

FIG. 3 is an overall vertical configuration diagram of a linear actuator used in a flow control device. The top view of a linear actuator.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Linear motion actuator 2 Yoke 201 Coil bobbin 202 Excitation coil 21 Yoke block 22 Motor flange 3 Rotor 31 Shaft hole 311 Screw part 312 Intermediate area 313 Guide part 313a Guide groove 32 Trunk part 33 Magnet 4 Output shaft 41 Screw shaft part 42 Non-rotating shaft portion 421 Guide piece 43 Stopper piece 5 Flow rate control device 51 Flow path 52 Valve element 53 Bulkhead 531 Circumferential surface portion 532 Cover surface portion 6 Magnet 61 Communication hole 62 Magnetic sensor S Moving stroke S1 Stroke area in rotor S2 Stroke area in bulkhead

Claims (7)

A stator that forms a cylindrical yoke, a multi-pole magnetized rotor that is rotatably provided in the stator, and is screwed into the central shaft hole of the rotor so that it can move forward and backward as the rotor rotates. A linear motion actuator having an output shaft, wherein the output shaft is formed by a threaded shaft portion and a non-rotating shaft portion, while the shaft hole is formed in one side region of the screw shaft portion. A threaded portion that is screwed with the scored shaft portion and a guide portion that guides the anti-rotation shaft portion formed in the other side region with a predetermined intermediate region in a rotation-restricted state are provided in divided regions. The shaft hole advances and retracts with the output shaft moving in the middle region of the threaded shaft portion and the non-rotating shaft portion, and in the guide portion region of the non-rotating shaft portion as a movement stroke region within each shaft hole. A linear actuator characterized by being configured appropriately. 2. The guide portion according to claim 1, wherein the guide portion includes a guide groove formed in an axial direction, and a guide piece provided on the detent shaft portion slides in the guide groove. A linear actuator. 3. The linear actuator according to claim 1, wherein the linear actuator is provided in a flow rate control device that provides a valve body at a tip of the output shaft and controls a flow rate by opening and closing a fluid flow path by the valve body. A linear motion actuator characterized in that a cylindrical lid-shaped partition wall is interposed in a gap with a rotor so that the rear end side of the output shaft is fitted and sealed. 4. The linear actuator according to claim 3, wherein the guide portion is provided in a lower surface area of the lid surface portion in the partition wall and is fitted and inserted into the shaft hole. 5. The linear motion actuator according to claim 4, wherein the guide portion extends between the lid surface portion and the rotor, and is allocated to the shaft hole inner region and the partition wall inner region. 6. The straight line according to claim 1, wherein a magnet is provided at a rear end of the output shaft, and an origin detection sensor that detects a magnetism and generates a voltage when the magnet approaches the output shaft. Moving actuator. The linear motion actuator according to claim 6, wherein the position detection sensor is provided on a lid surface portion outside the partition wall.