JP3094785B2 - Linear drive - Google Patents

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 in which a rotor shaft of a motor is used as a movable shaft and linearly moves while rotating the movable shaft.

[0002]

2. Description of the Related Art A conventional linear drive device is used, for example, for opening and closing a valve of a water heater.
As shown in Japanese Patent Publication No. 51, a structure is employed in which a movable shaft is screwed into a female screw portion rotatable by a rotor, and the movable shaft passes through a fixed D-hole portion and moves linearly in a non-rotating state. .

[0003]

However, in the above linear drive device, since the movable shaft is forcibly stopped from rotating by the D hole portion, if the wear or deformation of the portion progresses, the D hole will not work. There is a problem that a high load is applied to the portion and the movable shaft bites into the D-hole portion (locked state of rotation). In addition, a high load due to the wedge action applied to the D hole increases the frictional resistance between the D hole and the movable shaft, so that there is a problem that torque crossing occurs. In addition, this type of linear drive device is used for driving valves of water heaters,
Used in many fields, but with the movement of the movable shaft,
Since the size of the linear drive device in the axial direction tends to be large, miniaturization is required in any field. In a linear drive device, when the dimension in the axial direction is increased, the usable range of the linear drive device is greatly limited. Therefore, it is a technical problem that downsizing in the axial direction is always required. In addition, since parts around the movable shaft are special mechanical elements, there is a disadvantage in that processing of parts and assembly of products becomes complicated and complicated.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a linear drive device which has the disadvantages of the prior art, that is, prevents the above-mentioned biting of the movable shaft and the occurrence of torque loss, thereby achieving compactness in the axial direction and general-purpose parts. Is to be assembled.

[0005]

In order to achieve the above object, the present invention comprises a rotor (17) inserted inside a stator (21) of a motor (5a).
A movable shaft (2) that can move in the axial direction and is rotatable as a rotation shaft of the shaft, and the outer side of the movable shaft (2) can be moved in the axial direction by a bearing (4) integrated with the stator (21).
In the linear drive device (1) rotatably supported by
A state formed inside the rotor (17) between a part of the outer peripheral surface of the movable shaft (2) and a part of the inner peripheral surface of the center of the rotor (17) and allowing the linear movement of the movable shaft (2). And the rotor (1
Transmission mechanism (18) for transmitting the rotation of (7) to the movable shaft (2)
Between the inner peripheral surface of the cylindrical portion (8) fixed to a portion integral with the stator (21) of the motor (5a) inside the rotor (17) and a part of the outer peripheral surface of the movable shaft (2). and a conversion mechanism for converting rotary motion into linear motion of the movable shaft (2) of the formed rotor (17) (6), the transform transfer mechanism (18)
The mechanism (6) and the movable shaft (2) are arranged side by side in the axial direction.
One side of the rotor (17) is sandwiched by a cylindrical portion with the structure (18) interposed therebetween.
(8) It is supported rotatably by the end and
The other side of the table (17) is rotatable by the movable shaft (2).
Part of the movable shaft (2) supporting and forming the conversion mechanism (6)
The outer peripheral surface of the movable shaft (2) is circular at a position other than the above and at a position other than a part of the movable shaft (2) forming the transmission mechanism (18), and the circular portion of the movable shaft (2) is ), And the linear motion is performed while rotating the movable shaft (2) by the rotational motion of the rotor (17).

In the above linear drive device (1), the transmission mechanism (18) is constituted by a spline mechanism (18), and a part of the inner peripheral surface of the center of the rotor (17) and one of the movable shaft (2). It is provided between the outer peripheral surface of the portion. The conversion mechanism (6) inside the rotor (17) includes a female screw (9) provided on one of the movable shaft (2) and the stator yoke (20), and a movable shaft (2) and a stator yoke ( 20), and a male screw part (10) screwed to the female screw part (9).

[0007]

Embodiment 1 As shown in FIG. 1 and FIG.
The linear drive device 1 includes a spline mechanism 18 as a transmission mechanism, a conversion mechanism 6, and a step motor 5a as a motor, and performs a linear motion while rotating the movable shaft 2. That is, the rotor 17 is inserted into the stator 21 of the stepping motor 5a. As the rotation axis of the rotor 17, the movable shaft 2 that can move in the axial direction can move in the motor case 5b by the bearing 4 in the axial direction. It is rotatably supported. Bearing part 4
Are integrated with the stator 21 via the motor case 5b, and support the outside of the movable shaft 2.

The spline mechanism 18 transmits the rotation of the rotor 17 to the movable shaft 2 which is movable in the axial direction. The spline mechanism 18 is provided on the outer peripheral surface of a part of the movable shaft 2 while allowing the linear movement of the movable shaft 2. It comprises a row of projections 7 formed and a row of grooves 16 formed on the inner peripheral surface of a part of the center of the rotor 17.

The conversion mechanism 6 is provided between the inner peripheral surface of the cylindrical portion 8 fixed to the stator yoke 20 integral with the stator 21 of the motor 5 a inside the rotor 17 and a part of the outer peripheral surface of the movable shaft 2. The movable shaft 2 is configured to convert the rotational motion of the rotor 17 into a linear motion of the movable shaft 2. The male thread portion 10 is formed on the outer peripheral surface of a part of the movable shaft 2, and the cylindrical portion located on the retreat side of the movable shaft 2. 8 formed on the inner peripheral surface. Here, the conversion mechanism 6 (the female thread portion 9 and the male thread portion 1)
0) also serves as a bearing for the rear end side of the movable shaft 2. Thus, the transmission mechanism 18 and the conversion mechanism 6 are movable
They are arranged in the axial direction of the shaft 2. Also, the rotor 17
With the transmission mechanism 18 interposed therebetween, one end of the cylindrical portion 8
The other side of the rotor 17 is rotatably supported by the
(Outside of the movable shaft 2) rotatably supported by the movable shaft 2
Is held.

In this way, the movable shaft 2 is connected to the conversion mechanism 6
The outer peripheral surface is configured to be circular at positions other than the part forming the cylindrical part 8 and the part other than the part forming the cylindrical portion 8, so that it can be supported by the general-purpose bearing portion 4 at the outer side, that is, at the tip end projecting outside. . As a result, the circular portion of the movable shaft 2 is inserted into the bearing hole of the bearing portion 4, and is movable in the axial direction and is rotatable.

A stopper mechanism 3 for stopping the movable shaft 2 at the limit position is provided inside the motor case 5b. The stopper mechanism 3 includes a missing gear 11 integrally formed with the rotor 17 and a Geneva gear 12 meshing with the missing gear 11, and regulates the range of linear movement of the movable shaft 2 by regulating the rotation range of the Geneva gear 12. The missing gear 11 has two teeth, a thick tooth portion 15 and a thin continuous tooth 11c.
The Geneva gear 12 is rotatably supported by a motor case 5b.
A thin tooth portion 19a, a thick tooth portion 19b, and a stopper portion 19 that mesh with the missing gear 11 are formed in a portion corresponding to the linear motion range of.

Next, the operation will be described. In the initial stage of driving, in order to return the movable shaft 2 to the retreat limit, that is, to the home position of the mechanical system, a larger number of pulses than the necessary number of pulses, that is, pulses of the number of oversteps, are supplied to the step motor 5a by a drive circuit (not shown). To rotate the rotor 17 in the reverse direction. As a result, the movable shaft 2 returns to the retreat limit, that is, returns to the mechanical origin position and stops. At this point, the origin of the electric system of the drive circuit (not shown) matches the origin of the mechanical system. This origin adjustment ensures the position control.

Next, when a necessary pulse is sent from a drive circuit (not shown) to the step motor 5a to rotate the rotor 17 forward, the rotation of the rotor 17 is transmitted to the movable shaft 2 by the spline mechanism 18. The rotational motion of the movable shaft 2 is converted into a linear motion by screwing the male screw portion 10 and the female screw portion 9 of the cylindrical portion 8. Therefore, the movable shaft 2 moves forward while rotating, operates a load, for example, a valve of a water heater, outside the movable shaft 2 and stops at a target position.

On the other hand, every time the missing gear 11 makes one rotation, the Geneva gear 12 rotates by two teeth. After this rotation, the continuous teeth 11c come into contact with the two thick tooth portions 19b to keep the Geneva gear 12 from rotating.

As described above, since the movable shaft 2 is configured to perform the linear motion while rotating, the conventional D-hole portion is not required, and therefore, it is possible to prevent the movable shaft 2 from biting or generating torque loss. Also, the stopper mechanism 3
Since it is composed of the Geneva gear 12 and the missing gear 11, no biting occurs between the female screw portion 9 and the male screw portion 10. Further, in the drive circuit, it is only necessary to send the pulse for returning to the origin to the step motor 5a and then send the pulse of the necessary over-step number in the reverse direction, so that the configuration of the drive circuit can be simplified. .

[0016]

Embodiment 2 As shown in FIG. 3 and FIG.
The stopper mechanism 3 according to the first aspect of the present invention includes a Geneva gear 12 meshed with the missing gear 11, an engaging portion 13 integrally formed with the Geneva gear 12, and a rotating region of the Geneva gear 12 engaged with the engaging portion 13. And a stopper portion 14 for performing the operation.

The Geneva gear 12 has large thin teeth 15a and small thin teeth 15b alternately on the outer peripheral surface, and has an engaging portion 13 protruding in a semicircular shape on the end surface. The stopper portion 14 is formed by cutting and raising a part of the motor case 5b, and the engaging portion 13 contacts the stopper portion 14 to restrict the rotation range of the Geneva gear 12, thereby restricting the linear motion range of the movable shaft 2. I do.

The operation of the second embodiment will be described. Missing gear 11
Each time is rotated by one tooth, the Geneva gear 12 is rotated by the number of two teeth by the two teeth of the tooth portion 15 and the continuous teeth 11c, and the engaging portion 13 integrally formed with the Geneva gear 12 is also rotated. When the portion 14 hits, the rotation of the Geneva gear 12 is stopped, and the movable shaft 2 is stopped at the limit position.

In the second embodiment, the missing gear 11 is composed of two teeth, but the number of teeth is determined as necessary. The large thin teeth 15a and the small thick teeth 15b of the Geneva gear 12 also change accordingly.

[0020]

Other Embodiments The transmission mechanism may be constituted by a square hole formed in the rotor 17 and a square axis formed in the movable shaft 2 instead of the spline mechanism 18. The conversion mechanism 6 includes a screw hole formed in the movable shaft 2, a female screw portion 9 of the screw hole, a screw rod fixed to the stator yoke 20, and an external screw portion 10 of the screw rod. Is also good. Further, the stopper mechanism 3 may be provided outside the motor case 5b.

[0021]

As is clear from the above description, according to the present invention, the following effects can be obtained. That is, since the rotary motion of the rotor is converted into the linear motion of the movable shaft, and the linear motion is performed while rotating the movable shaft, the torque loss occurs due to biting of the movable shaft (locked state of rotation) and an increase in frictional resistance. Can be prevented.

In particular, according to the present invention, the transmission mechanism is formed between the outer peripheral surface of the movable shaft and the inner peripheral surface of the rotor, and both the transmission mechanism and the conversion mechanism are formed inside the rotor. The linear drive device can be downsized in the direction of the movable shaft, that is, in the direction of the stroke of the reciprocating motion of the movable shaft, and a stable linear drive device that can be incorporated in a narrow space or the like can be provided. Transmission mechanism and conversion mechanism
They are arranged side by side in the direction of the movable axis inside the rotor.
Thus, the length can be sufficiently reduced in the direction of the movable shaft of the rotor.
In addition, the rotor (17)
At one end of the cylinder and at the other end of the rotor
Because it is rotatably supported by a movable shaft, the rotor
Are supported at two fixed points at a suitable axial distance
Therefore, uniform motor performance and smooth movement of the movable shaft are ensured.
Can be maintained.

Further, the outer peripheral surface of the movable shaft is formed in a circular shape except for a portion forming a part of the conversion mechanism and the transmission mechanism. Therefore, the movable shaft protruding from the inside of the rotor to the outside has a circular shape, and the outer peripheral surface of the movable shaft facing the bearing portion normally disposed outside the rotor also has a circular shape. Therefore, it is not necessary to perform special processing on the bearing portion, and the bearing portion can be constituted by a general-purpose product. Also, when the linear drive device is used for opening and closing a valve of a water heater, for example, the outer peripheral surface of the movable shaft on the outer side is circular as an O-ring used to prevent water from entering the inside of the motor. O-rings can be used.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a linear drive device according to a first embodiment. In the drawing, with respect to the center line of the movable shaft, the upper part of the movable shaft shows a state at the forward limit position, and the lower part of the movable shaft shows a state at the backward limit position.

FIG. 2 is an enlarged front view showing the stopper mechanism of FIG. 1;

FIG. 3 is a front view illustrating a stopper mechanism according to a second embodiment.

FIG. 4 is a configuration diagram showing the Geneva gear of FIG. 3;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Linear drive device 2 Movable shaft 3 Stopper mechanism 4 Bearing part 5a Step motor 5b Motor case 6 Conversion mechanism 7 Projection row 8 Cylindrical part 9 Female thread part 10 Male thread part 11 Missing gear 11c Continuous tooth 12 Geneva gear 13 Engagement part 14 Stopper portion 15 Tooth portion 15a Large thin tooth portion 15b Small thick tooth portion 16 Groove row 17 Rotor 18 Spline mechanism as transmission mechanism 19 Stopper portion 19a Thin tooth portion 19b Thick tooth portion 20 Stator yoke 21 Stator

Claims (2)

(57) [Claims] 1. A stator (21) of a motor (5a).
PartRotatableWith inserted rotor (17)
(17) can be axially movable and rotatable
Movable shaft (2), and the outer side of the movable shaft (2) is
Bearing (4) integral with the bearing (21)Can be moved in the axial direction
Rotatable with nohSupport linear drive (1)
And a part of the outer peripheral surface of the movable shaft (2) inside the rotor (17).
It is formed between a part of the center of the rotor (17) and the inner peripheral surface.
The rotor (1) is moved in a state where the linear movement of the movable shaft (2) is allowed.
Transmission mechanism (18) for transmitting the rotation of (7) to the movable shaft (2)
And the stator of the motor (5a) inside the rotor (17)
Inner peripheral surface of cylindrical portion (8) fixed to part integral with (21)
And a rotor formed between the movable shaft and a part of the outer peripheral surface of the movable shaft.
Convert the rotational motion of (17) into a linear motion of the movable shaft (2)
A conversion mechanism (6),The transmission mechanism (18) and the conversion mechanism (6) are connected to the movable shaft (2).
The transmission mechanism (18) is arranged side by side in the axial direction, and the rotor
One side of (17) is rotatable by the end of the cylindrical portion (8)
And the other side of the rotor (17) is
Rotatably supported by (2),  Other than a part of the movable shaft (2) forming the conversion mechanism (6)Rank
PlaceAnd a movable shaft forming a transmission mechanism (18)
The outer peripheral surface of the movable shaft (2) is circular at a position other than (2),
Insert the circular part of the movable shaft (2) into the bearing hole of the bearing (4)
And movable by the rotation of the rotor (17).
It is characterized by linear movement while rotating the shaft (2).
Linear drive (1). 2. A spline mechanism (18) is provided between a part of the inner peripheral surface of the center of the rotor (17) and a part of the outer peripheral surface of the movable shaft (2) as a transmission mechanism (18). (1
The internal conversion mechanism (6) of (7) includes a female screw (9) provided on one of the movable shaft (2) and the stator yoke (20), and the movable shaft (2) and the stator yoke (20).
And a male screw part (10) which is provided on the other of the two and is screwed to the female screw part (9).
The linear drive (1) as described.