JPH07127758A - Proportional control valve - Google Patents

Abstract

PURPOSE:To provide a reliable proportional control valve wherein a valve element does not bite into a valve seat and stress on a transmission system is eliminated by installing a rotation restricting mechanism acting mechanically on a stepping motor. CONSTITUTION:In a proportional control valve to vary a flow path resistance between an inlet port and an output port 28 by driving a valve element to and apart from a valve seat by a stepping motor, a Geneva wheel 7 provided with a groove-less tooth 12 is provided to restrict the rotational range of the stepping motor 2. Thus the movable range of the valve element is restricted, and any trouble such as binding of valve due to biting of the valve element into the valve seat, etc., stress on a drive system, etc., is not produced. The stepping motor thus obtained can be used also for the other applications.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a proportional control valve in which a valve body is precisely driven to enable fine adjustment of fluid flow rate, and more specifically, a movable range of the valve body is restricted. The present invention relates to a proportional control valve that is provided so as to eliminate the bite into the valve seat and the like caused by excessive movement of the valve body.

[0002]

2. Description of the Related Art Conventionally, in order to supply hot water of an appropriate temperature to a bathroom or the like, hot water (about 80 ° C.) that has passed through a heat exchanger that is heated by a gas burner and cold water supplied from a water supply or the like are appropriately used. The flow rate is controlled by a proportional control valve in order to mix at a ratio. This is because temperature control by controlling the output of the gas burner is insufficient in terms of responsiveness and accuracy. Normally, such a proportional control valve is adapted to precisely adjust the degree of opening by a valve body driving means provided separately. Hot water used in bathrooms requires subtle temperature adjustments due to factors such as differences in individual tastes, but the sensible temperature of hot water is greatly affected by the slight difference in the opening of the proportional control valve. Because.

Here, an electric motor is used as the valve body driving means, and the valve body is driven by converting it into a rectilinear motion by a pinion gear or a serration mechanism and a screw mechanism. The one using the serration mechanism and the screw mechanism is superior in accuracy of valve opening control to the one using the pinion gear. As the electric motor, a step motor that can surely drive only the intended amount is used, and the step motor is provided separately or integrally with the proportional control valve. For example, Japanese Utility Model Publication No. 3-25469 discloses a valve device in which an ordinary electric motor, which is not a step motor, is attached to drive a valve element.

[0004]

However, there have been the following problems in the prior art. The movement of the valve element in this type of proportional valve is regulated by abutting one on the valve seat and the other by abutting on the body of the valve device pivotally supporting the valve body drive shaft. That is, the movable range of the valve body naturally has upper and lower limits. On the other hand, the step motor, which is the valve body driving means, can usually rotate endlessly, and the step motor itself has no limitation on the movable range. Therefore, for example, even after the valve body comes into contact with the valve seat, the step motor tries to continue rotating, which causes a step-out phenomenon, and the step-out phenomenon is repeated as long as the drive pulse is applied. Similarly, when the proportional valve is fully opened, when the valve body comes into contact with the body, the step motor causes a step-out phenomenon.

Although the step motor has not so much torque, the valve body is often made of a flexible material such as rubber from the viewpoint of ensuring the airtightness when the valve is closed. If it continues, it may be slightly deformed and may be caught in the valve seat or the like. When the bite state occurs, an excessive driving torque is required when the valve body is driven next in the opening direction. In particular, when the valve body is left open for a long time after the occurrence of the bitten state and the valve body is stuck in the bitten state, a very large drive torque is required.

However, since the stepper motor usually has a relatively low driving torque as described above, it is often impossible to open the valve from the engaged state. In addition, even if the valve can be opened, plastic deformation often remains in the valve body, which may cause a problem in the relationship between the valve body position and the flow passage cross-sectional area, resulting in failure of flow rate control thereafter. is there. Further, the vibration associated with the step-out phenomenon also puts a burden on the transmission system member such as the screw portion for transmitting the drive from the step motor, which causes a shortening of the life of the transmission system member.

As measures against these, for example, a position sensor for detecting the position of the valve body is provided, and when it is detected that the valve body has reached a predetermined upper limit or lower limit position by the output of the position sensor, a drive pulse to the step motor is given. It is possible to stop. In a proportional control valve used for hot water supply control, etc., it is not always necessary to close the valve body by tightly adhering it to the valve seat.
This is because by setting the lower limit position at a position where the valve body does not yet contact the valve seat, it is possible to prevent the valve body from being caught.
However, in this case, there is a problem in that the number of parts is increased, and particularly the control circuit system requires a complicated configuration.

The present invention has been made to solve the problems of the proportional control valve with a step motor according to the above-mentioned prior art. By providing a rotation restricting mechanism that acts mechanically on the step motor side, the valve is provided. An object of the present invention is to provide a highly reliable proportional control valve in which the body is prevented from abutting against a valve seat or the like, and thereby biting or deformation of the valve body and stress on the transmission system are eliminated.

[0009]

In order to achieve the above object, the present invention provides a body in which an inlet port and an outlet port are opened, a valve chamber formed inside the body, and a valve formed in the valve chamber. A proportional control valve having a seat, a valve body that approaches or separates from the valve seat to change a flow passage area between an inlet port and an outlet port, and a step motor that drives the valve body,
A Geneva wheel having a plurality of teeth rotatably mounted on a Geneva shaft provided in parallel with the rotor of the step motor and having a groove formed in a radial direction in the teeth except at least one of the plurality of teeth, And a pin for providing intermittent drive to the Geneva wheel by being eccentrically provided on the rotor of the step motor and rotating with the rotation of the rotor to enter or leave the groove formed in the teeth of the Geneva wheel. The rotation of the rotor is restricted by the contact of the pin with the tooth of the Geneva wheel on which the groove is not formed, and the upper and lower limits are set in the moving range of the valve body.

Further, the present invention is the above proportional control valve, wherein the lower limit of the moving range of the valve body is set to a position where it does not come into contact with the valve seat. Further, the present invention is a step motor having a stator and a rotor rotatably provided inside thereof and rotated by a predetermined angle by sequential excitation of the stator, which is rotatable on a Geneva shaft provided in parallel with the rotor. A Geneva wheel having a plurality of teeth attached to a plurality of teeth and at least one of the plurality of teeth having grooves formed in a radial direction; and a Geneva wheel that is eccentrically provided on the rotor and rotates with rotation of the rotor. A pin for applying an intermittent drive to the Geneva wheel by entering or leaving a groove formed in the teeth of the Geneva wheel, and abutting the pin to a tooth in which the groove of the Geneva wheel is not formed causes the rotor to move. The rotation range is regulated.

[0011]

In the proportional control valve of the present invention having the above construction, when the rotor of the step motor is rotated, the pin eccentrically provided on the rotor rotates in a circular locus. When the pin rotates into the groove formed in the teeth of the Geneva wheel, the Geneva wheel also rotates. When the pin disengages from the groove, rotation of the Geneva wheel is stopped. Due to such intermittent driving, the Geneva wheel makes one revolution per tooth while the rotor makes one revolution. Rotation of the rotor is stopped when the pin abuts the ungrooved tooth of the Geneva wheel. On the other hand, the valve body in the valve chamber is driven by the rotation of the rotor of the step motor, and the valve body approaches or separates from the valve seat,
The flow passage area between the inlet port and the outlet port opened in the body is changed. When the rotation of the rotor is stopped by the contact between the pin and the grooveless tooth of the Geneva wheel as described above, the movement of the valve body is also stopped.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is embodied as a proportional control valve with a step motor will be described below with reference to the drawings.
FIG. 1 shows a proportional control valve 1 with a step motor according to this embodiment.
The schematic of the hot-water supply apparatus which uses is shown. The water heater shown in FIG. 1 is a water supply channel 40 that receives water from a water source such as water supply.
Is provided with a heat exchanger 41 that is heated by the gas burner 43 and the like, and a sub-water passage 42 is provided in parallel with the heat exchanger 41. The sub-water passage 42 is provided with a step motor-equipped proportional control valve 1 so that the flow rate in the sub-water passage 42 can be adjusted as desired.

In the hot water supply apparatus shown in FIG. 1, the water that has flowed into the water supply passage 40 is branched and partly flows toward the heat exchanger 41 and the rest flows into the sub water passage 42. The water flowing into the side of the heat exchanger 41 is heated by the combustion heat of the gas burner 43 or the like to become high-temperature hot water (about 80 ° C.), the water flowing into the sub-water passage 42 flows as it is, and these are mixed to become a suitable temperature hot water. Etc. is supplied with hot water. Therefore, the temperature of the hot water supplied can be adjusted to a desired temperature by operating the proportional control valve with a step motor 1 to adjust the flow rate of the sub water passage 42. Figure 2
A sectional view of the proportional control valve 1 with a step motor provided in the sub water passage 42 is shown in FIG. Proportional control valve with step motor 1
Is composed of a step motor portion 2 and a proportional control valve portion 3 in appearance. The detailed configuration will be described below.

First, the step motor portion 2 will be described. The step motor portion 2 has an outer frame 4, a stator 5 fixed to the outer frame 4, and a rotor 6 rotatably held inside the stator 5. Stator 5
Is composed of a material of high magnetic permeability such as a thin steel plate,
An energizing coil 8 in which a conductive wire is densely wound is provided inside thereof. The energizing coil 8 is provided according to the number of teeth of the stator 5. The rotor 6 has a magnet 10 fitted on the outer periphery thereof. The stator 5 and the rotor 6 form a step motor. A plate 9 for mounting a Geneva wheel 7, which will be described later, is provided on the upper surface of the stator 5. In addition, a fitting hole 11 that does not penetrate is formed from below in the rotor 6 in order to transmit drive to a proportional control valve portion 3 described later, and a serration groove is cut in the peripheral wall thereof.

A Geneva wheel 7 is provided above the step motor portion 2. The Geneva wheel 7 sets a limit on the rotation of the rotor 6, and prevents the valve body 29 of the proportional control valve portion 3 described below from excessively moving and causing a problem. FIG. 3 shows a view of the proportional control valve with step motor 1 viewed from above with the outer frame 4 removed. The Geneva wheel 7 is rotatably attached to a Geneva shaft 20 provided on the plate 9 of the stator 5 in parallel with the rotor 6. FIG. 4 shows an enlarged view of the Geneva wheel 7.
The Geneva wheel 7 is a plate-shaped member in which a large number of teeth are formed, and a groove 14 is formed in each tooth in the radial direction except one tooth. In this embodiment, the tooth 12 having no groove is formed.
7 and a total of 6 teeth 13 having a groove 14 are formed. A side 18 between the teeth is formed in an arc shape.

Returning to FIG. 3, the tip portion 16 of the rotor 6 of the step motor projects in the center of the plate 9. The outer peripheral surface 17 of the tip portion 16 has a curvature equal to that of the teeth 18 of the Geneva wheel 7 and a side 18 between the teeth, and these are engaged with each other. A pin 15 is erected on the rotor 6 at a position off the central axis. When the rotor 6 rotates, the pin 15 rotates accordingly and draws a circular locus. When the pin 15 is in the right part in the figure due to the rotation of the rotor 6, the pin 1 is inserted into the groove 14 of the tooth 13 of the Geneva wheel 7.
5, the rotation of the rotor 6 is transmitted to the Geneva wheel 7, and the Geneva wheel 7 is intermittently driven as described later. A notch 19 is formed in the tip portion 16 of the rotor 6 on the side close to the pin 15. This is because the teeth 13 are cleared when the Geneva wheel rotates. As described above, since the Geneva wheel 7 has one tooth 12 having no groove, when the pin 15 comes into contact with the tooth 12, neither the rotor 6 nor the Geneva wheel 7 can rotate any more, and the rotation is restricted. .

Next, the proportional control valve portion 3 will be described. The proportional control valve portion 3 is located below the step motor portion 2, and the body 25 has its outer shape. A hollow cylindrical valve chamber 26 is formed inside the body 25. An inlet port 27 and an outlet port 28 that open the valve chamber 26 to the outside are opened in the body 25. Furthermore,
On the inlet port 27 side of the valve chamber 26, there is formed a valve seat 30 that approaches or separates from a truncated cone-shaped valve body 29 described later.

A substantially columnar adapter 31 as a guide member is fixedly fitted in the valve chamber 26. Adapter 3
1, a through hole 32 is formed so as to penetrate therethrough. Through hole 32
The drive rod 23 is fitted in the shaft so as to be slidable in the axial direction. Although the through hole 32 and the fitting portion of the drive rod 23 have a substantially circular cross section, a female screw is formed in the through hole 32 and a male screw is formed in the drive rod 23 and fitted therein. As described above, the tip head 24 is provided on the upper end of the drive rod 23, and a serration ridge that is fitted into the serration groove of the fitting hole 11 of the rotor 6 is cut on the peripheral surface of the tip head 24. . The valve element 29 is held at the lower end of the drive rod 23. An O-ring 33 is mounted between the body 25 and the adapter 31, and O-rings 34, 34 are mounted between the adapter 31 and the drive rod 23, so that the fluid in the valve chamber 26 is located above the step motor portion. It is prevented from leaking to the side of 2.

The rotor 6 of the step motor portion 2 and the tip head 24 of the drive rod 23 are serrated to each other as described above. Therefore, when the step motor portion 2 is operated to rotate the rotor 6, the drive rod 23 also rotates accordingly. Since the drive rod 23 is screwed into the through hole 32 of the adapter 31 as described above, the drive rod 23 moves up and down due to the screw movement when rotated. Drive rod 2
By the vertical movement of 3, the valve element 29 at the lower end approaches or separates from the valve seat 30. When the valve body 29 approaches the valve seat 30, the flow passage cross-sectional area between the inlet port 27 and the outlet port 28 decreases, and when the valve body 29 separates from the valve seat 30, the flow passage cross-sectional area increases. Since the valve body 29 has the truncated cone shape as described above, the flow passage cross-sectional area changes substantially in proportion to the distance from the valve seat 30, and the flow passage resistance between the inlet port 27 and the outlet port 28 also changes. It changes almost linearly.

Next, the operation of the proportional control valve with a step motor 1 having the above construction will be described. The proportional control valve with step motor 1 is used by connecting a known pulse drive circuit (not shown). By sequentially energizing the energizing coil 8 of the stator 5 by the pulse drive circuit to sequentially excite each tooth of the stator 5, the rotor 6 can be reliably rotated by a desired angle.

When the rotor 6 rotates, the pin 15 shown in FIG. 3 also rotates and the Geneva wheel 7 is intermittently driven as described above. This operation will be described. First, consider a state in which the pin 15 is in contact with the grooveless tooth 12 of the Geneva wheel 7 as shown in FIG. From this state, the rotor 6 is rotated counterclockwise in FIG. Then, the pin 15 draws a circular locus and rotates as shown by an arrow in the figure, and separates from the Geneva wheel 7. At this time, the outer peripheral surface 17 of the tip portion 16 of the rotor 6 meshes with the teeth 18 of the Geneva wheel 7 and the side 18 between the teeth, so that the Geneva wheel 7 does not rotate.

When the rotor 6 is further rotated, as shown in FIG. 5, the pin 15 reaches the tooth 13 next to the ungrooved tooth 12 of the Geneva wheel 7, and the groove 14 of the tooth 13 is reached.
Break into. At this time, the notch 19 of the tip portion 16 of the rotor 6 is engaged with the Geneva wheel 7, and the Geneva wheel 7 is rotatable. Therefore, the Geneva wheel 7 is pushed by the pin 15 that has entered the groove 14 and rotated clockwise in the drawing. When the rotor 6 is further rotated and the pin 15 reaches the position of the arrow A in FIG. 5, the Geneva wheel 7 makes one seventh rotation from the initial state, and the pin 15 comes out of the groove 14. At this time, the outer peripheral surface 17 of the tip portion 16 again meshes with the side 18 between the teeth of the Geneva wheel 7, and the rotation of the Geneva wheel 7 is stopped. When the rotor 6 is further rotated, the pin 15 enters the next groove 14 and the Geneva wheel 7 is further rotated 1/7. By repeating this, the Geneva wheel 7 is driven intermittently.

When the rotor 6 rotates 6 times from the initial state,
The ungrooved teeth 12 of the Geneva wheel 7 reach the position of arrow B in FIG. Then, after about a further half rotation, the pin 15 contacts the grooveless tooth 12 as shown in FIG. In this state, both the rotor 6 and the Geneva wheel 7 cannot rotate any more and are forcibly stopped. That is, the rotation of the step motor is restricted. When the rotor 6 is rotated counterclockwise from the state shown in FIG.
By the action of the groove 14 and the groove 14, the Geneva wheel 7 is intermittently driven clockwise by one seventh rotation. Then, when the rotor 6 rotates about 6.5 times from the state of FIG. 7, the pin 15 and the grooveless tooth 12 come into contact again as shown in FIG. 3, and the rotation of the rotor 6 is forcibly stopped. Thus, both ends of the rotation range of the step motor are regulated.

Next, the operation of the proportional control valve portion 3 driven by the rotation of the rotor 6 will be described. The rotor 6 of the step motor portion 2 and the drive rod 23 of the proportional control valve portion 3 are serrated as described above. Therefore,
When the rotor 6 rotates, the drive rod 23 also rotates accordingly. On the other hand, since the drive rod 23 is screwed to the adapter 31, the drive rod 23 moves up and down by screwing while rotating.

When the rotation of the rotor 6 is the forward direction (the counterclockwise direction in FIG. 3 is the forward direction), the drive rod 23 moves upward. Therefore, the valve element 29 moves in the valve chamber 26 in the direction away from the valve seat 30, and the opening degree of the proportional control valve portion 3 increases. When the forward operation of the rotor 6 is further continued, the distance between the valve element 29 and the valve seat 30 increases, and the flow resistance from the inlet port 27 to the outlet port 28 decreases. Then, in the water heater of FIG. 1, the flow rate of the cold water flowing through the sub water passage 42 increases, and the temperature of the mixed hot water supplied decreases. On the other hand, when the rotor 6 is rotated in the opposite direction, the drive rod 23 moves downward due to the screw movement. Therefore, the valve element 29 moves toward the valve seat 30, and the flow resistance from the inlet port 27 to the outlet port 28 increases. Therefore, in the hot water supply apparatus of FIG. 1, the flow rate of the sub water passage 42 decreases and the temperature of the mixed hot water supplied rises.

Since both ends of the rotation range of the rotor 6 are regulated by the Geneva wheel 7, the upper and lower ends of the movement range of the drive rod 23 and the valve body 29 are regulated. That is, when the rotor 6 is fully rotated in the forward direction to the state shown in FIG. 7, the valve element 29 becomes the most distant from the valve seat 30. A cross-sectional view in this state is shown in FIG. In this state, the valve element 29 is largely separated from the valve seat 30, and is not further separated. Even in this state,
There is a considerable margin between the valve element 29 and the adapter 31.
On the other hand, when the rotor 6 is rotated in the opposite direction to the full extent of the regulation and brought into the state of FIG. 3, the valve element 29 is in the state closest to the valve seat 30. The sectional view shown in FIG. 2 shows this state. In this state, the valve element 29 is approaching the valve seat 30 just before the contact, and does not approach further.
In FIG. 2, the valve body 29 seems to be in contact with the valve seat 30, but in reality, a minute gap remains.

The step motor-equipped proportional control valve 1 of this embodiment having the configuration and operation described above has the following features. First, the valve element 29 that changes the flow path resistance is
The step motor portion 2 is rotated by a predetermined angle to drive only a desired amount through screw movement. Therefore, the flow path resistance of the proportional control valve portion 2 can be changed without excess or deficiency in combination with the valve body 29 having a truncated cone shape. Therefore,
In the hot water supply apparatus of FIG. 1, the flow rate of the sub water passage 42 is appropriately adjusted and the temperature of the hot water supplied is adjusted as desired.

Second, since the Geneva wheel 7 for restricting both ends of the rotation range of the rotor 6 is provided, the moving range of the valve body 29 has upper and lower limits, and the valve body 29 has the valve seat 30 and the adapter 3.
It does not come into contact with the first grade. Therefore, even after the valve element 29 comes into contact with the valve seat 30 or the like, the stepping motor is driven to prevent the valve element 29 from being bitten. This prevents troubles such as the inability to open the valve due to the biting of the valve element 29 and the flow rate fluctuation due to the deformation of the valve element 29.
Since the valve body 29 does not contact the valve seat 30, the adapter 31, etc., an excessive stress is applied to the transmission system even if the rotation of the rotor 6 is stopped by the Geneva wheel 7 and the step-out phenomenon of the step motor occurs. It will not be done.

Further, by changing the number of teeth of the Geneva wheel 7, the moving range of the valve body 29 can be determined. The moving range of the valve element 29 may be determined in consideration of the shape of the valve chamber 26, the required maximum flow rate, and the like. The step motor portion 2 used in this embodiment is not only optimal as the valve body driving means of the proportional control valve as described above, but can also be used for other purposes as a step motor.

It should be noted that the above embodiments do not limit the present invention at all, and it is needless to say that various modifications and improvements can be made without departing from the gist of the present invention. For example, in the proportional control valve with step motor of the above embodiment, the rotor 6 of the step motor and the tip head 24 of the drive rod 23 are used.
Although the drive rod 23 and the through hole 32 of the adapter 31 are screw-coupled to each other by the serration mechanism, the serration and the screw may be exchanged. Further, as a guide member for guiding the drive rod 23, an adapter 31 separate from the body 25 is fixedly fitted in the valve chamber 26.
Although the through hole 32 is provided in the drive rod 23, the body 25
The drive rod 23 may be fitted and inserted by forming the through hole 32 using a part of itself as a guide member. Further, the type of step motor and its control method are not particularly limited, and those suitable for the application may be selected and used. Further, the intermittent rotation of the Geneva wheel 7 can be used to supply a signal to a display device or the like that displays the opening of the proportional control valve.

[0031]

As described in detail above, in the proportional control valve of the present invention, the step motor that can reliably drive only the desired amount of the valve element is provided, and the rotation regulating mechanism that mechanically acts is provided on the step motor side. Therefore, the rotation range of the step motor and the movement range of the valve body have upper and lower limits, and the valve body does not come into contact with the valve seat or the like. Therefore, the valve body does not bite into the valve seat or the like to increase the valve opening load, and the valve body does not deform so that the flow control does not occur. Further, the stress of the transmission system is eliminated and the life of the components of the transmission system is extended.
Thus, the present invention can provide a highly reliable proportional control valve. Further, the step motor in the present invention is, of course, very suitable as the valve body driving means of the proportional control valve as described above, but even in applications other than such applications, only the desired angle can be accurately adjusted. It is ideal for applications that can be driven and require regulation of the rotatable range.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a hot water supply device using a proportional control valve according to the present invention.

FIG. 2 is a sectional view showing a configuration of a proportional control valve according to the present invention.

FIG. 3 is a view of the proportional control valve in the state shown in FIG. 2 viewed from above.

4 is an enlarged view of the Geneva wheel in FIG. 3. FIG.

FIG. 5 is a diagram showing a state in which a pin enters a groove and a Geneva wheel is driven by rotation of a rotor.

6 is a cross-sectional view showing an open state of the proportional control valve shown in FIG.

7 is a view of the proportional control valve in the state shown in FIG. 5 viewed from above.

[Explanation of symbols]

 1 Proportional control valve with step motor 2 Step motor part 3 Proportional control valve part 6 Rotor 7 Geneva wheel 12 Groove tooth 13 Groove tooth 14 Groove 15 Pin 20 Geneva shaft 25 Body 26 Valve chamber 27 Inlet port 28 Outlet port 29 Valve body 30 valve seat

Claims (3)

[Claims] 1. A body in which an inlet port and an outlet port are opened, a valve chamber formed inside the body, a valve seat formed in the valve chamber, and an inlet port that is close to or away from the valve seat. In a proportional control valve having a valve body that changes a flow passage area with an outlet port and a step motor that drives the valve body, the proportional control valve is rotatably attached to a Geneva shaft provided in parallel with a rotor of the step motor. A Geneva wheel having a plurality of teeth, wherein at least one of the plurality of teeth has a groove formed in a radial direction; and a rotor of the step motor, which is eccentrically provided and rotates with the rotation of the rotor. And a pin for intermittently driving the Geneva wheel by entering or leaving the groove formed in the tooth of the Geneva wheel, and to a tooth in which the groove of the Geneva wheel is not formed. The proportional control valve characterized in that the rotation of the rotor is restricted by the contact of the pin, and upper and lower limits are set in the moving range of the valve body. 2. The proportional control valve according to claim 1, wherein the lower limit of the moving range of the valve body is set to a position where it does not come into contact with the valve seat. 3. A step motor having a stator and a rotor rotatably provided inside thereof and rotating by a predetermined angle by sequential excitation of the stator, wherein the step motor is rotatably attached to a Geneva shaft provided in parallel with the rotor. A Geneva wheel having a plurality of teeth, wherein at least one of the plurality of teeth has a groove formed in a radial direction, and the Geneva wheel is eccentrically provided on the rotor and rotates with the rotation of the rotor. A pin for intermittently driving the Geneva wheel by entering or leaving a groove formed in the tooth of the Geneva wheel, and the rotor by the contact of the pin with the tooth of the Geneva wheel in which the groove is not formed. A step motor having a regulation of a rotation range of the step motor.