JP2556715B2 - Stroke type step motor - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a step motor that converts a rotational movement of a rotor into a linear movement via a lead screw, and in particular detects abnormal operation (step-out) and the origin of the lead screw. The present invention relates to a stroke type step motor having a built-in switch suitable for position detection.

[Prior Art] Generally, since a step motor can obtain an angle proportional to a digital amount, it is widely used industrially as an actuator suitable for positioning control. However, in this type of motor, a step out phenomenon that the rotor does not rotate in synchronization with a command signal from the controller may occur for various reasons, and it is necessary to detect some step out depending on the system. In addition, there are actuators using a stroke type step motor, which require the position detection of the lead screw. The conventional detection method as described above uses a rotary encoder as disclosed in Japanese Patent Laid-Open No. 61-185096, and measures the rotation detection pulse signal of the encoder.

[Problems to be Solved by the Invention] In the above-mentioned conventional technique, the space required for mounting the rotary encoder on the step motor is secured, the mounting and mounting accuracy, the degree of freedom in designing the step motor, and the like are restricted. There were problems such as the price increase of the encoder body and the complexity of the detection circuit.

An object of the present invention is to detect the position of the lead screw and the abnormal operation of the step motor by using a switch mechanism that is opened and closed (ON / OFF) by the lead screw in a stroke type step motor.

[Means for Solving the Problems] In the stroke type step motor for converting the rotational movement of the rotor into the linear movement via the lead screw, a switch mechanism is provided on one end side of the lead screw, By the linear motion of the lead screw, the switch mechanism is turned on and off to detect the position of the lead screw and the abnormal operation of the step motor, and further, the switch mechanism enables adjustment of the contact gap. This is achieved by having a mechanism and easily performing position detection adjustment with a counterpart device equipped with a step motor.

[Operation] The present invention turns on in cooperation with the linear movement of the lead screw.
By providing a simple switch mechanism for turning off at one end side of the lead screw, it becomes possible to have both the origin position detection of the lead screw and the abnormal operation detection function of the step motor. The initial position of the lead screw of the step motor can be detected by operating the step motor in the direction in which the switch mechanism is turned on at the time of initial operation and moving the lead screw until the switch mechanism is pressed and turned on. For example, if the system is reset by a level change when this switch mechanism turns ON, normal positioning control becomes possible from that point. Also, after that, the step motor is operated and the switch mechanism becomes OF
Normal or abnormal operation of the step motor can be detected by operating the lead screw for x pulses in the F direction, then reversing the direction and counting the operation pulses until the switch is turned on again.

[Embodiment] An embodiment of the present invention will be described below with reference to Figs.

FIG. 1 is a vertical sectional view of a stroke type step motor showing an embodiment according to the present invention. Due to the rotating magnetic fields of the coils 15a, 15b in the stators 14a, 14b, N poles in the circumferential direction,
A rotor 4 having magnets 5 which are alternately magnetized into S poles has a ball bearing 7 on one side and a plain metal 8 on the other side. The rotor 4 is supported by the housing 1 and the end cover 2 to rotate.

The magnet 5 is formed integrally with the rotor 4 here. A female screw is formed in the center hole of the rotor 4, and the male screw of the lead screw 6 is engaged with the meshing mechanism 16.
Is configured. A slider 21 having a polygonal outer shape is fixed to one end of the lead screw 6, and a slightly larger polygonal hole similar to the outer shape of the slider 21 is formed in the housing 1. hand,
The slider 21 and the lead screw 6 are non-rotatable and movable in the axial direction.

When the rotor 4 described above rotates, the lead screw 6
Will move on the axis without rotating. For example, in the embodiment shown in FIG. 1, when the rotor 4 rotates clockwise as viewed from the direction of arrow A, the lead screw 6 moves leftward, and when it rotates counterclockwise, the lead screw 6 moves axially rightward. Next, the slider 21 of the lead screw 6
The switch mechanism 10 is formed in the direction of one end 18 on the opposite side. The switch mechanism 10 is composed of a movable plate 10a having a contact point 17a, a fixed plate 10b having a contact point 17b, and an insulator 12 for insulating and fixing the two plates, and is fixed to the end cover 2. One end 18 of the lead screw 6 and the movable plate 10 of the switch mechanism 10
The movable plate 10a is located between the movable plate 10a and
A push rod 9 for pressing is provided.
The push rod 9 is fitted in the center hole of the end cover 2 so as not to loosely move, moves along the axis in the center hole, and the push rod 9 is not pressed by the lead screw 6. In the state,
It is pressed against the end cover by the movable plate 10a. Originally, it is possible to omit the push rod 9 and extend the lead screw 6 in the axially upward direction to directly press the movable plate 10a, but in consideration of insulation and contact wear of the movable plate 10a, etc. Then, it is better to provide the push rod 9 and use synthetic resin as the material.

FIG. 2 is a longitudinal sectional view showing a state where the switch mechanism 10 of the stroke type step motor shown in FIG. 1 is turned on. The lead screw 6 moves to the right on the axis, and the one end 18 presses the movable plate 10a via the push rod, and the contact 17a of the movable plate 10a.
Shows a state in which the switch mechanism 10 is turned on by contacting the contact 17b of the fixed plate 10b with. This switch mechanism
When the system is reset by the level change in which 10 is turned on, that point is the origin position, and from that point, regular positioning control of the lead screw 6 becomes possible. Further, after that, the step motor is operated to move the lead screw 6 leftward, that is, in the direction in which the switch mechanism is turned off by x pulses, and then the moving direction is transferred and the operation pulse until the switch mechanism 10 is turned on again. Normal or abnormal operation of the step motor can be easily detected by counting and checking the minutes.

Next, when this stepping motor is mounted on a device, the ON / OFF operating point of the switch mechanism 10 may be different from the counterpart device 19 of FIG. 2 due to the accumulated error of the constituent parts, particularly in the axial direction. The B dimension between the slider 3 and the slider 3 may vary. In order to deal with this, there is a limit to the correction on the system side (controller) software. With this step motor, the cap 13 made of the elastic body of the switch cover 3 is removed after the device is attached to the device, and the contacts 17a, 17b are An adjustment mechanism for adjusting the contact gap by pressing and moving the fixed plate by an adjusting screw 11 provided on the insulator 12 is provided. Further, in order to prevent loosening, the groove portion 20 of the insulator 12 is filled with an adhesive and fixed, and the cap 13 is attached to the switch cover after the above adjustment is completed. With these, matching with the counterpart device 19 can be easily and quickly measured.

The cap 13 is a dustproof and waterproof means for the step motor, and the switch cover 3 is attached to the housing 1 while pressing the stators 14a, 14b and the end cover 2 in the axial direction inside the housing 1. It is fixed with screws.

As described above, in the present invention, the simple switch mechanism and the mechanism for adjusting the contact gap of the switch mechanism are provided to detect the origin position of the lead screw and the positioning control from the origin, the abnormal operation detection of the step motor, and the mounting. It is easy to match with the other device.

[Effects of the Invention] As described above, according to the present invention, a stroke-type step that does not use an expensive rotary encoder and a complicated detection circuit accompanying it, does not require much mounting and mounting accuracy, and has a degree of freedom in designing a step motor A motor is obtained.

[Brief description of drawings]

1 is a vertical and vertical sectional view of a stroke type step motor showing an embodiment according to the present invention, and FIG. 2 is a vertical sectional view showing the stroke type step motor of FIG. 1 when a switch mechanism is ON. 1 …… Housing, 2 …… End cover, 3 …… Switch cover, 4 …… Rotor, 5 …… Magnet, 6 …… Lead screw, 7 …… Ball bearing, 8 …… Plain metal, 9 …… Push rod , 10 …… Switch mechanism, 10a …… Movable plate, 10
b …… Fixing plate, 11 …… Adjust screw, 12…
… Insulator, 13 …… Cap, 14a, 14b …… Stator, 15a, 15
b …… coil, 16 …… meshing mechanism, 17a, 17b …… contact, 18 ……
One end, 19 …… Mating device, 20 …… Groove, 21 …… Slider

Claims (5)

(57) [Claims] 1. A stroke type step motor provided with a lead screw for converting rotational motion of a rotor into linear motion via a screw meshing mechanism, wherein linear motion of the lead screw is provided on one end side of the lead screw. A stroke type step motor comprising: a switch mechanism composed of a fixed plate and a movable plate for opening and closing contacts according to the switch mechanism; and an adjusting mechanism for adjusting the contact position on the fixed plate side. 2. The stroke type stepping motor according to claim 1, wherein the opening / closing operation of the switch mechanism is configured to be performed via a push rod that co-operates with the linear movement of the lead screw. . 3. The push rod is located on the axial center line of the lead screw.
The stroke type step motor described in the item. 4. One plate constituting the switch mechanism is moved by the push rod, and the other plate has an adjusting screw mechanism for adjusting a gap between contacts of the contacts mounted on each plate. The stroke type stepping motor according to any one of claims 1 to 3, characterized in that: 5. The switch mechanism is located in a space formed by an end cover for supporting one bearing of a rotor and a switch cover for protecting the switch mechanism, and the end cover is made of an insulator. The switch cover is provided with a working hole for adjusting the adjusting mechanism and a cap made of an elastic body that is attachable to and removable from the working hole. ~ The stroke type step motor according to the fourth item.