JP2002374652A - Linear driver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a linear driver ensuring accurate positional detection by detecting an output shaft, i.e., a movable shaft, directly. SOLUTION: A linear driver comprising means for converting the rotational motion of the rotor of a motor into the linear motion of a drive shaft 24 is provided, on the movable shaft 24 thereof, with means 7 for detecting the position of the movable shaft 24 directly. The converting means comprises a female screw and a male screw provided, respectively, on the movable shaft 24 and the rotor to mesh each other, and means for blocking rotation of the movable shaft 24 wherein the means for blocking rotation comprises a guide section 5 formed in a containing case 4, and a member 6 coupled with the movable shaft 24 to perform linear motion along with the movable shaft 24 and guided by the guide section 5 to block rotation of the movable shaft 24.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a linear drive device capable of converting a rotary motion of a drive source into a linear motion of a drive shaft, for example, opening and closing a valve of a water supply device and opening and closing a drain plug of a bath. It can be used as an actuator or the like.

[0002]

2. Description of the Related Art For example, various linear drive devices have been proposed which can be used as an actuator for opening and closing a valve of a water supply device and for opening and closing a drain plug of a bath. Actual opening 57
The invention described in JP-127567 is an example thereof. The invention described in the above-mentioned publication is characterized in that an output shaft which is restricted in movement in the rotation direction and is movable in the thrust direction and has an external thread formed therein, a female screw formed on the rotor of the motor and meshing with the external thread of the output shaft, and one end of the motor rotor , A gear that meshes with the pinion, a convex portion formed on the gear for rotation control, and a rotational region of the gear that is provided on a support base and interferes with the convex portion to restrict the rotation region of the gear. And a protrusion that restricts the rotation area of the gear, thereby restricting the linear movement stroke of the output shaft. In addition, a position detecting sensor is fixed to a support table arranged in parallel with the gear, and detects an origin position in a rotation region of the gear.

[0003]

Problems to be Solved by the Invention
In the invention described in Japanese Patent No. 7567, a sensor for detecting the position of the output shaft is fixed to a support for fixing the motor, and the position of the output shaft is detected between a shaft fixed to a gear meshing with the rotor and the sensor. It has a structure to do. For this reason, a rotor, a gear, or the like is interposed between the output shaft and the sensor, which is affected by component accuracy and component integration accuracy, and there is a problem that accurate position detection is difficult.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art, and is a linear drive device having conversion means for converting the rotational motion of a motor rotor into a linear motion of a drive shaft. It is another object of the present invention to provide a linear drive device capable of directly detecting the position of a movable shaft that is an output shaft and capable of accurately detecting the position.

[0005]

According to the first aspect of the present invention,
In a linear drive device having conversion means for converting the rotational movement of a motor rotor into a linear movement of a drive shaft, a position detection means is provided on the movable shaft for directly detecting the position of the movable shaft. The position of the movable shaft can be directly detected by the position detecting means.

According to a second aspect of the present invention, in the first aspect of the present invention, the conversion means has a female screw and a male screw provided on the movable shaft and the rotor and meshing with each other, and a rotation preventing means for preventing rotation of the movable shaft. The rotation preventing means has a guide portion formed in the storage case, and a rotation preventing member coupled to the movable shaft so as to move linearly with the movable shaft and guided by the guide portion to prevent rotation of the movable shaft. The rotation detecting member is provided with the position detecting means.

According to a third aspect of the present invention, in the second aspect of the present invention, the position of the movable shaft is detected by a pair with the position detecting unit provided on the movable shaft. First detecting means arranged oppositely, and second detecting means capable of detecting the position of the movable shaft by a detection signal difference between when the first detecting means is opposed to the position detecting means and when it is not opposed to the position detecting means; And the second detection means is provided directly or indirectly on the member on which the guide portion is formed.

According to a fourth aspect of the present invention, in the third aspect, the first detecting means is disposed on a substrate, and the substrate is fixed to a member having a guide portion.

According to a fifth aspect of the present invention, in the third aspect of the present invention, the second detecting means is disposed on a substrate, and the substrate is fixed to a member having a guide portion.

According to a sixth aspect of the present invention, in the third, fourth or fifth aspect, the position detecting means comprises a magnet, and the first detecting means and the second detecting means comprise magnetic sensors. .

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a linear drive device according to the present invention will be described with reference to the drawings. 1 and 2, reference numeral 13 denotes a cylindrical case having a bottom, and reference numeral 4 denotes a cover fixed to an open end of the case 13. A motor as a drive source is incorporated in the case 13. Motor is bobbin 19, drive coil 2
0, a stator including a stator core 21, a motor case 18, and the like, and a rotor including a rotor 16, a rotor magnet 17, and the like.

The stator core 21 has a plurality of pole teeth on the inner peripheral side so as to form a cylindrical shape at equal intervals in the circumferential direction. The stator cores 21 are arranged as a set of two and opposed to each other so that the pole teeth are alternately arranged in the circumferential direction. A bobbin 19 around which a drive coil 20 is wound is fitted around the outer circumference of these pole teeth. The two stator sets each including the stator core 21, the bobbin 19, and the drive coil 20 are overlapped and coupled in the axial direction to form a stator. The stator thus configured is housed and fixed in a bottomed cylindrical motor case 18.

The rotor 16 has a central tube shaft portion 25 serving as an output shaft of the motor, and a large-diameter cylindrical portion 26 formed integrally with about half of the central tube shaft portion 25 in the axial direction. I have. A cylindrical rotor magnet 17 is fitted and fixed to the outer periphery of the large-diameter cylindrical portion 26. The rotor magnet 17 has magnetic poles at equal intervals in the circumferential direction. In the case 13, a main plate 22 is fixed to an open end of the motor case 18 so as to face an end face of the stator. A radial bearing 23 is fitted in a center hole of the base plate 22, and the radial bearing 23 rotatably supports the central tube shaft portion 25 of the rotor 16. A cap 15 is fitted to the other end (the right end in FIG. 1) of the rotor 16.
The cap 15 has a spherical surface, and the spherical surface hits the thrust receiver 14 arranged at the center of the fixed portion of the motor case 18 so that a load in the thrust direction applied to the rotor can be received. At the center of the inner bottom of the motor case 18, the thrust receiver 14 and the central tube shaft 25 of the rotor 16 are provided.
A cylindrical portion is formed surrounding the end.

A female lead screw 27 is formed on the inner peripheral side of the distal end portion of the central tube shaft portion 25 of the rotor 16, and a pinion 28 is formed near the radial bearing 23, which is an intermediate portion in the axial direction. The end of the movable shaft 24 is inserted into the center tube shaft 25. A male lead screw is formed on the outer periphery of the end of the movable shaft 24. This male lead screw meshes with the female lead screw 27 of the rotor 16. The distal end of the movable shaft 24 protrudes from the distal end surface of the cover 4. The movable shaft 24 is provided with a movable shaft 24
A rotation stopper 6 extending in the radial direction from the center is fixed. The guide shaft 5 is fixed in the cover 4 in parallel with the movable shaft 24. The rotation stopper 6 is fitted on the guide shaft 5 so as to be slidable along the guide shaft 5.

The motor having the stator and the rotor is a stepping motor. When a pulsed power is supplied to the drive coil 20, the rotor rotates by a predetermined angle. When the central tube shaft 25 constituting the rotor rotates in one direction, the female lead screw 27 of the central tube shaft 25 engages with the male lead screw of the movable shaft 24, and the movable shaft 24 is rotated by the rotation stopper 6.
The movable shaft 24 is linearly moved in the axial direction while being guided by the guide shaft 5. When the center tube shaft 25 reverses, the movable shaft 24 linearly moves in the opposite direction. Therefore, the female lead screw 27 of the central tube shaft portion 25, the male lead screw of the movable shaft 24, the rotation stopper 6, and the like constitute conversion means for converting the rotational motion of the motor rotor into the linear motion of the movable shaft 25. .

A magnet piece 7 is attached to the rotation stopper 6. Since the rotation stopper 6 is an integral member with the movable shaft 24, the magnet piece 7 can be said to be provided directly on the movable shaft 24, or it can be said that the magnet piece 7 is provided indirectly on the movable shaft 24. it can. In addition, the magnet piece 7 constitutes a position detecting means together with a magnetic sensor described below.

Magnetic sensors 2 and 3 for detecting the linear movement limit of the movable shaft 24 are arranged opposite to the movement locus of the magnet piece 7. The magnetic sensors 2 and 3 form a pair with the magnet piece 7 to constitute a position detecting means. The magnetic sensor 2 detects the forward limit of the movable shaft 24, and the magnetic sensor 3 detects the backward limit of the movable shaft 24. The magnetic sensors 2 and 3 are arranged on a circuit board 8, and the circuit board 8 is fixed in a member on which the guide shaft 5 as a guide portion is formed, that is, in the cover 4. More specifically, the circuit board 8 is inserted into an insertion groove or the like formed in the cover 4, and one end of the circuit board 8 is fixed to the inner bottom surface of the cover 4, and the other end is fixed in the cover 4 by hitting the base plate 22. ing.

The movable shaft 24 moves forward, and the sensor 2
Is detected, the driving of the motor is stopped to stop the advance of the movable shaft 24, and the movable shaft 24 is retracted by the reverse rotation of the motor. When the sensor 3 detects the magnet piece 7, the driving of the motor is stopped and Stop the retreat. Assuming that the magnetic sensor 2 as the position detecting means is a first detecting means and the magnetic sensor 3 is a second detecting means, the magnetic sensor 2 as the first detecting means
Detecting the position of the movable shaft 24 based on the detection signal difference between the magnetic sensor 2 and the magnetic sensor 3 as the second detecting means when the magnetic sensor 7 is opposed to the magnet piece 7 as the position detecting means Is also possible. First magnetic sensor 3
The detection means and the magnetic sensor 2 may be used as the second detection means, and the position of the movable shaft 24 may be similarly detected based on the difference between the two detection signals.

In order to increase the moving stroke of the movable shaft 24 from the forward limit to the backward limit and to obtain a sufficient force, it is necessary to increase the rotation speed of the motor. For this purpose, in the illustrated embodiment, an American winding stop mechanism is provided. 2 and 3 show an example of an American winding stop mechanism incorporated in the above-described linear movement mechanism.

In FIG. 2 and FIG.
A first gear 29 that meshes with the pinion 28 and a second gear 31 that meshes with the first gear 29 are disposed on the outer peripheral side of the pinion 28 formed in the first gear 29. Each of the first gear 29 and the second gear 31 is attached to the
0, it is held rotatably about the axis 32. The first gear 29 and the second gear 31 are formed to have different numbers of teeth.

The embodiment shown in FIGS. 1 and 2 is an example of a linear drive device for automatically opening and closing a drain plug of a bath.
The total stroke of the movable shaft 24 is about 18 mm, and the stroke between the two sensors 2 and 3 is 15.2 mm.
The number of teeth of the pinion 28 formed on the output shaft of the motor is 1
6, the number of teeth of the first gear 29 is 24, and the number of teeth of the second gear 31 is 25. The first gear 29 is integrally formed with a protrusion 33 whose thickness is increased by the number of two teeth. On the other hand, the second gear 31 is integrally formed with a projection 34 so as to overlap one tooth space. The protrusion 33 and the protrusion 34
By projecting from the same surface side of the gears 29, 31, the projections 33, 34 interfere with each other when the tips of the projections 33, 34 face each other. Projections 33, 34
Are within the range where they do not interfere with each other, both the first gear 29 and the second gear 31 can rotate. Therefore, the projection 33 and the projection 34 constitute a blocking portion that allows the first gear 29 and the second gear 31 to make a plurality of rotations and interferes with each other to prevent the rotation of the rotor.

As described above, the number of teeth of the first gear 29 is two.
4. When the number of teeth of the second gear 31 is 25, which is one tooth difference, as shown in FIG. 3 (a), the projection 33 and the projection 34 interfere with each other to prevent rotation, In order for the projection 33 and the projection 34 to interfere with each other again from the opposite directions to prevent the rotation as shown in FIG. 3B, the first gear 29 is rotated by the number of rotation allowable teeth of the second gear 31. After rotating. In the case of the above-described embodiment, the movable shaft 24 moves from one rotation preventing position to the other rotation preventing position.
Of the first gear 29 is N1, the first
The number of teeth of the gear 29 is Z1, the number of rotations of the pinion 28 is Np,
If the number of teeth of the pinion 28 is Zp, it can be obtained by the following calculation. N1 = 25-1 = 24 (If the blocking portion 33 of the first gear 29 is one tooth, the rotation speed of the first gear 29 is 25. In the illustrated embodiment, the blocking portion 33 has two teeth. Np = N1 × Z1 / Zp = 24 × 24/16 = 36 If the pitch of the lead screw 27 is 0.5 mm, the stroke L is L = 36 × 0.5 = 18 (mm).

In practice, the position at which the projections 33 and 34 interfere with each other is about 1.5 teeth before the center axis of the two gears 29 and 31, so that L = 1 in a strict calculation.
7.9 (mm). In this way, the mechanism in which the gears having different numbers of teeth are engaged with each other, and a part in which both of the gears are provided with a blocking portion that interferes with each other is called an American winding stop mechanism. In comparison, there is a feature that the number of rotations of the gear from the rotation limit in one direction to the rotation limit in the other direction can be increased. American winding with such features
According to the illustrated embodiment using the stop mechanism, the linear movement stroke of the movable shaft 24 can be lengthened, and a sufficiently large force can be obtained.

In the embodiment described above, the American
The stroke of the movable shaft 24 detected and regulated by the two magnetic sensors 2 and 3 is slightly smaller than the stroke of the movable shaft 24 regulated by the winding stop mechanism. This usually involves two magnetic sensors 2, 3
This is to restrict the linear movement of the movable shaft 24 by the American winding stop mechanism even if the regulation by the magnetic sensors 2 and 3 stops working due to runaway or the like.
As a result, the linear driving device itself and the device driven by the linear driving device can be protected. Note that the stroke of the movable shaft may be regulated only by the American winding stop mechanism without using a sensor for regulating the stroke of the movable shaft. Further, one movement position of the movable shaft may be regulated by a detection signal from a sensor, and the other movement position may be regulated by an American winding stop mechanism.

The magnetic sensors 2, 3 in the illustrated embodiment
May be a Hall IC, a magnetoresistive element, or any other element capable of detecting magnetism. Further, the detecting means is not limited to the magnetic sensor, but optically or by a change in capacitance.
Any other device can be used as long as it can be detected by an appropriate principle. Further, in the illustrated embodiment, the magnet piece 7 to be detected is provided directly or indirectly on the movable shaft 24, and the magnetic sensors 2 and 3 as detection means are fixed to the case 4 side, and the position of the movable shaft is Is detected directly,
A sensor serving as a detecting means is provided on the movable shaft 24 side.
A magnet piece or the like to be detected may be provided on the side.

In the illustrated embodiment, the positioning and fixing of the substrate 8 is performed by the insertion groove formed in the case 4, the inner bottom portion of the case 4, and the base plate 22, but the screwing, welding, bonding or the like is used. May go. Also, instead of the above groove,
The positioning and fixing of the substrate may be performed using protrusions or ribs.

[0027]

According to the first aspect of the present invention, in the linear drive device, since the position detecting means is provided on the movable shaft for directly detecting the position of the movable shaft, the position of the movable shaft can be accurately detected. be able to.

According to the second aspect of the present invention, the converting means has the female screw and the male screw provided on the movable shaft and the rotor and meshing with each other, and the rotation preventing means for preventing the rotation of the movable shaft. A guide portion formed in the storage case, and a rotation preventing member coupled to the movable shaft so as to move linearly with the movable shaft and guided by the guide portion to prevent rotation of the movable shaft. Since the member is provided with the position detecting means, the converting means for converting the rotational movement of the rotor into the linear movement and the position detecting means can be realized with a simple configuration.

According to the third aspect of the present invention, the position detecting means is provided opposite to the movement locus of the position detecting means so that the position of the moving axis can be detected in pairs with the position detecting means provided on the movable shaft. A second detecting means for detecting a position of the movable shaft by a detection signal difference between when the first detecting means faces the position detecting means and when the first detecting means does not face the position detecting means; Since the detecting means is provided directly or indirectly on the member on which the guide portion is formed, the positional accuracy between the position detecting means and the second detecting means can be easily secured.

Also in the case of the invention according to claims 4 and 5, the first detecting means or the second detecting means is disposed on a substrate, and the substrate is fixed to a member having a guide portion, so that position detection is performed. It is possible to easily secure the positional accuracy between the means and the first detecting means or the second detecting means.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing an embodiment of a linear drive device according to the present invention.

FIG. 2 is a front view showing a part of an American winding stop mechanism with a cover removed in the embodiment.

FIG. 3 shows the operation of the American winding stop mechanism, wherein (a) shows one rotation limit;
(B) is a front view showing the other rotation limit.

[Explanation of symbols]

 2 Magnetic sensor as detecting means 3 Magnetic sensor as detecting means 4 Cover 5 Guide shaft as guide part 6 Rotation preventing means 7 Magnet piece as position detecting means 8 Circuit board 14 Movable shaft

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3H065 BA01 BA07 BB16 5H607 BB01 BB11 CC01 CC03 CC07 DD08 EE52 HH01 JJ02 5H611 AA01 BB01 PP01 QQ03 RR02 TT01 UA01 UB01

Claims (6)

[Claims] 1. A linear drive device having a conversion means for converting the rotational motion of a motor rotor into a linear motion of a drive shaft, wherein the movable shaft is provided with position detection means for directly detecting the position of the movable shaft. A linear drive device characterized by the above-mentioned. 2. The converting means includes female and male screws provided on the movable shaft and the rotor and meshing with each other, and rotation preventing means for preventing rotation of the movable shaft. The rotation preventing means is formed in a storage case. A guide portion; and a rotation preventing member coupled to the movable shaft so as to move linearly with the movable shaft and guided by the guide portion to prevent rotation of the movable shaft. The linear drive device according to claim 1, further comprising a detection unit. 3. A first detecting means arranged in opposition to a movement trajectory of the position detecting means so as to detect a position of the movable shaft in a pair with a position detecting means provided on the movable shaft; (1) second detection means capable of detecting the position of the movable shaft by a detection signal difference between when the detection means faces the position detection means and when the detection means does not face the position detection means, wherein the second detection means has a guide portion 3. The linear drive device according to claim 2, wherein the linear drive device is provided directly or indirectly on the member. 4. The linear drive device according to claim 3, wherein the first detecting means is disposed on a substrate, and the substrate is fixed to a member having a guide portion. 5. The linear drive device according to claim 3, wherein the second detecting means is disposed on a substrate, and the substrate is fixed to a member having a guide portion. 6. The linear drive device according to claim 3, wherein the position detecting means comprises a magnet, and the first detecting means and the second detecting means comprise magnetic sensors.