JPH0739104A - Linear driving device - Google Patents

Abstract

PURPOSE:To prevent the sticking of the movable shaft of a linear driver and the generation of torque loss. CONSTITUTION:The title linear driver concerns one 1 having a movable shaft 2, movable in the axial direction, as the rotating shaft of the rotor 17 of a motor 5a, and has a transmitting mechanism 18 for transmitting the rotation of the rotor 17 to the movable shaft 2, and a converting mechanism 6 for converting the rotational motion of the rotor 17 to the linear motion of the movable shaft 2, and linear motion is generated by rotating the movable shaft 2.

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 which moves a movable shaft in a straight line while rotating the 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. A movable shaft is screwed into a female screw portion rotatable by a rotor, and the movable shaft penetrates a fixed D hole portion. The structure is such that it moves linearly in a non-rotating state.

[0003]

However, in the above-mentioned linear drive device, when the wear or deformation of the linear drive device progresses, the movable shaft is forcibly stopped from rotating by the D hole portion. There is a problem that a high load is applied to the portion and the movable shaft bites against the D hole. Further, since the high load applied to the D hole increases the friction between the D hole and the movable shaft, there is a problem that torque cross occurs.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to prevent biting of a movable shaft and occurrence of torque cross in a linear drive device.

[0005]

In order to achieve the above object, the present invention provides a linear drive device having a movable shaft that is movable in the axial direction as a rotary shaft of a rotor of a motor.
A transmission mechanism that transmits the rotation of the rotor to the movable shaft that is movable in the axial direction, and a conversion mechanism that converts the rotational movement of the rotor into the linear movement of the movable shaft, and the linear movement is performed while rotating the movable shaft. As a transmission mechanism, a spline mechanism is provided between the rotor and the movable shaft, and the conversion mechanism is a female screw portion provided on one of the movable shaft and the stator yoke.
The movable shaft and the stator yoke are provided on the other side of the movable shaft and the male screw portion screwed into the female screw portion.

[0006]

[Embodiment 1] As shown in FIG. 1 and FIG.
The linear drive device 1 according to (1) includes a spline mechanism 18 as a transmission mechanism, a conversion mechanism 6, and a step motor 5a as a motor, and is configured to make a linear motion while rotating the movable shaft 2. That is, the rotor 17 is inserted inside the stator 21 of the step motor 5a, and the movable shaft 2 which is movable in the axial direction as the rotation shaft of the rotor 17 moves axially in the motor case 5b via the bearing portion 4. It is possible and rotatably supported.

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 formed on the outer peripheral surface of the movable shaft 2 and on the inner peripheral surface of the rotor 17. The groove array 16 is formed. The conversion mechanism 6 converts the rotational movement of the rotor 17 into the linear movement of the movable shaft 2, and fixes the cylindrical portion 8 to the male screw portion 10 formed on the outer peripheral surface of the movable shaft 2 and the stator yoke 20. It is composed of a threaded portion 9 to be formed on the inner peripheral surface of the tubular portion 8.

Further, a stopper mechanism 3 for stopping the movable shaft 2 at the forward / backward 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. The stopper mechanism 3 regulates the rectilinear motion range of the movable shaft 2 by regulating the rotation range of the Geneva gear 12. The partial gear 11 has two teeth, a thick tooth portion 15 and a thin continuous tooth 11c.
The Geneva gear 12 is rotatably supported by the motor case 5b, and the movable shaft 2 is attached to the outer peripheral surface of the Geneva gear 12.
A thin tooth portion 19a, a thick tooth portion 19b, and a stopper portion 19 that mesh with the partial gear 11 are formed in a portion corresponding to the linear movement region of.

Next, the operation will be described. In order to return the movable shaft 2 to the backward limit, that is, to the home position of the mechanical system at the initial stage of driving, a number of pulses larger than the required number of pulses by a margin, that is, an overstep number of pulses, is applied to the step motor 5a by a drive circuit (not shown). Then, the rotor 17 is rotated in the reverse direction. As a result, the movable shaft 2 returns to the backward limit, that is, the origin position of the mechanical system, and stops. At this point, the origin of the electric system of the drive circuit (not shown) and the origin of the mechanical system match. This origin adjustment ensures position control.

Next, when a necessary pulse is sent from the drive circuit (not shown) to the step motor 5a to rotate the rotor 17 in the forward direction, the rotation of the rotor 17 is transmitted to the movable shaft 2 by the spline mechanism 18. The rotary motion of the movable shaft 2 is converted into a rectilinear motion by screwing the male screw portion 10 of the movable shaft 2 and the female screw portion 9 of the tubular portion 8. Therefore, the movable shaft 2 moves forward while rotating and stops at the target position.

On the other hand, the Geneva gear 12 rotates by the number of two teeth each time the missing gear 11 rotates once. After this rotation, the continuous teeth 11c are in 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 made to move linearly while being rotated, the conventional D hole portion is unnecessary, and therefore, the biting of the movable shaft 2 and the occurrence of torque cross can be prevented. Further, the stopper mechanism 3 is
Since it is composed of the Geneva gear 12 and the missing gear 11, biting does not occur between the female screw portion 9 and the male screw portion 10. Further, in the drive circuit, it is sufficient to send the number of pulses for returning to the origin to the step motor 5a, and then send the required number of overstep pulses in the reverse direction, so that the configuration of the drive circuit can be simplified. .

[0013]

[Embodiment 2] As shown in FIGS.
The stopper mechanism 3 according to the present invention regulates the rotation range of the Geneva gear 12 by engaging the Geneva gear 12 that meshes with the missing gear 11, the engaging portion 13 integrally formed with the Geneva gear 12, and the engaging portion 13. And a stopper portion 14 that operates.

The Geneva gear 12 has large thin tooth portions 15a and small thin tooth portions 15b alternately on the outer peripheral surface thereof, and an engaging portion 13 protruding in a semicircular shape on the end surface thereof. Further, the stopper portion 14 is formed by cutting and raising a part of the motor case 5b, and the engaging portion 13 hits the stopper portion 14 to regulate the rotation range of the Geneva gear 12, thereby regulating the linear movement range of the movable shaft 2. To do.

The operation of the second embodiment will be described. Missing gear 11
Each time the gear rotates once, the Geneva gear 12 rotates by the number of two teeth by the two teeth of the tooth portion 15 and the continuous tooth 11c, the engaging portion 13 integrally formed with the geneva gear 12 also rotates, and the stopper When it hits the portion 14, the rotation of the Geneva gear 12 is blocked, and the movable shaft 2 is stopped at the advance / retreat position.

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

[0017]

Other Embodiments The transmission mechanism may be composed of a square hole formed in the rotor 17 and a square shaft formed in the movable shaft 2 instead of the spline mechanism 18. Further, the conversion mechanism 6 is formed by forming a screw hole in the movable shaft 2, fixing the screw rod to the female screw portion 9 of this screw hole, and the stator yoke 20, and forming the male screw portion 10 of this screw rod. Good. Further, the stopper mechanism 3 may be provided outside the motor case 5b.

[0018]

As is apparent 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, it is possible to prevent biting of the movable shaft and occurrence of torque cross.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a linear drive device according to a first embodiment. In the figure, the upper part of the movable shaft is in the forward limit position and the lower part of the movable shaft is in the backward limit position with the center line of the movable shaft as a boundary.

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

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

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

[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 screw part 10 Male screw part 11 Missing gear 11c Continuous tooth 12 Geneva gear 13 Engaging 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 (transmission mechanism) 19 Stopper portion 19a Thin tooth portion 19b Thick tooth portion 20 Stator yoke 21 Stator

Claims (2)

[Claims] 1. A linear drive device (1) having a rotor (17) of a motor (5a) as a rotating shaft and having a movable shaft (2) movable in the axial direction, wherein the rotor (17) is rotated by a movable shaft (2). 2) to the transmission mechanism (18) and the rotor (1
And a conversion mechanism (6) for converting the rotational movement of (7) into a rectilinear movement of the movable shaft (2), wherein the rotational movement of the rotor (17) causes the rectilinear movement of the movable shaft (2) to rotate. And linear drive device (1). 2. A transmission mechanism (18) is provided with a spline mechanism (18) between a rotor (17) and a movable shaft (2), and a conversion mechanism (6) is provided with a movable shaft (2) and a stator yoke (2). 20) from a female screw part (9) provided on one side and a male screw part (10) provided on the other side of the movable shaft (2) and the stator yoke (20) and screwed into the female screw part (9). A linear drive device (1) according to claim 1, characterized in that it is constructed.