JPH0787704A - Linear driver - Google Patents

Abstract

PURPOSE:To reduce cost by forming a driving circuit in a simple structure. CONSTITUTION:A linear driver 1 converts the rotation of a motor 5 into a linear motion of a movable shaft 2 by engaging a threaded part 9 with a threaded part 10 to linearly move the shaft 2, and comprises an intermittent gear 11 to be rotated by a rotor of the motor 5, a geneva gear 12 to be engaged with the gear 11, and a stopper 14 engaged with an engaging part 13 formed at the gear 12 to regulate a rotating area of the gear 12, wherein a linearly moving area of the shaft 2 is regulated by regulating a rotating area of the gear 12.

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 for converting a rotation of a motor into a rectilinear motion of a movable shaft by screwing a screw portion so as to rectilinearly move the movable shaft.

[0002]

2. Description of the Related Art A linear drive device of this type is used, for example, to open and close a valve of a water supply device. The conventional linear drive device has a structure in which a screw part is rotated by a motor and a non-rotating movable shaft screwed onto the motor is linearly moved, and a screw part fixed while rotating the movable shaft by a motor. There is a structure in which a straight movement is made by screwing.

[0003]

However, in any of the above-described linear drive devices, in order to prevent the screws from falling off and sticking to the screws, the drive circuit for driving the motor and the rotation position or movement position of the movable shaft are used. Is provided and a structure for stopping the movable shaft at the advancing / retreating position based on the detection signal from the sensor is required. Therefore, there is a problem that a complicated drive circuit is required and cost is increased.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and an object thereof is to make a driving circuit a simple structure and to reduce the cost. In the drive unit, biting of the movable shaft with screws,
This is to prevent the occurrence of torque cross on the movable shaft.

[0005]

In order to achieve the above object, the first invention is, in a linear drive device, a toothless gear rotated by a rotor of a motor, a Geneva gear meshing with the toothless gear, and a Geneva gear. The gear has an engaging portion and has a stopper portion that engages with the engaging portion to regulate the rotation range of the Geneva gear, and regulates the rectilinear motion range of the movable shaft by regulating the rotation range of the Geneva gear. It has a structure that

According to a second aspect of the present invention, in a linear drive device, a toothless gear rotated by a motor and a tooth groove meshing with a tooth portion of the toothless gear are provided on an outer peripheral surface of a portion corresponding to a linear motion range of a movable shaft. The formed Geneva gear is provided, and the structure in which the linear motion region of the movable shaft is regulated by regulating the rotation region of the Geneva gear.

[0007]

In the first aspect of the invention, when the motor is driven, the rotation of the motor is converted into the rectilinear motion of the movable shaft by the screwing of the screw portion, and the movable shaft moves in the rectilinear motion. Interlocking with this, the Geneva gear intermittently rotates little by little with each rotation of the missing gear, the engaging part of the Geneva gear hits the stopper part, and the rotation of the Geneva gear stops. , Stop at a predetermined position. In this way, the stopper part stops the rotation of the Geneva gear to stop the linear motion of the movable shaft, so there is no difference between the escape torque and the normal drive torque, and the drive circuit has only the direction reversing function. Is enough. Therefore, the drive circuit can have a simple structure and the cost can be reduced.

According to the second aspect of the present invention, there is provided a partly toothed gear rotated by a motor, and a Geneva gear having a tooth groove meshing with a tooth part of the partly toothed gear formed on an outer peripheral surface of a portion corresponding to a linear motion region of the movable shaft. Since the structure in which the linear movement region of the movable shaft is regulated by regulating the rotation region of the Geneva gear, the engaging portion of the Geneva gear and the stopper portion that engages with the Geneva gear in the first aspect of the present invention are unnecessary. be able to.

[0009]

[Embodiment 1] As shown in FIG. 1 to FIG.
The linear drive device 1 according to 1 is applied to a structure in which the movable shaft 2 is linearly moved in a non-rotating state. More specifically, the movable shaft 2 is rotatably supported by the housing 3 connected to the motor 5 via the bearing 4 so as to be able to move linearly, and is prevented from rotating by the D hole 6. A cylinder portion 8 is coaxially connected to the motor shaft 7, a female screw portion 9 is formed on the inner peripheral surface of the cylinder portion 8, and a male screw portion 10 screwed to the screw portion 9 is a movable shaft. 2 is formed on the outer peripheral surface.

The gist of the first embodiment is that, as a stop mechanism, a missing gear 11 rotated by a motor 5, a Geneva gear 12 meshing with the missing gear 11, and a Geneva gear 1
2, an engaging portion 13 integrally formed with the stopper 2, and a stopper portion 14 that engages with the engaging portion 13 and restricts the rotation range of the Geneva gear 12.
And a structure for restricting the rectilinear motion range of the movable shaft 2 by restricting the rotation range of the Geneva gear 12.

That is, as shown in FIG.
Is fixedly connected to the motor shaft 7 and has a missing gear 11 formed on the outer peripheral surface of the base of the tubular portion 8.
It has one thick tooth portion 15 and thin continuous tooth 11a. Figure 4
As shown in FIG. 5, the Geneva gear 12 is rotatably supported by the housing 3, has large and thin tooth portions 15a and small thick tooth portions 15b alternately on its outer peripheral surface, and has semicircular projections on its end surface. It has an engaging portion 13.

The stopper portion 14 is, for example, a part of a base plate 16 cut and raised, and the engaging portion 13 hits the stopper portion 14 to make the rotation range of the Geneva gear 12 approximately 180 degrees in this embodiment. This restricts the linear motion range of the movable shaft 2. In the case of the first embodiment, the missing gear 11
Is integrally formed with the tubular portion 8, but may be formed as a separate member.

Next, the operation of the first embodiment will be described. First, in order to align the origin of the electric system and the origin of the mechanical system of the drive circuit (not shown), the drive circuit sends to the motor 5 a number of pulses which is larger than the number of pulses required by the margin, that is, an overstep number. When the origin position of the mechanical system is set to, for example, the backward limit position of the movable shaft 2, the screw portion 9 and the missing gear 11 are rotationally driven by rotating the tubular portion 8 in the counterclockwise direction in FIG. 2 by the motor 5.

The rotation of the threaded portion 9 prevents the movable shaft 2 from rotating, and the threaded portion 10 and the threaded portion 9 are screwed together.
Retreat to the left at. For each rotation of the missing gear 11,
The Geneva gear 12 intermittently rotates by the number of two teeth and then stops. At the time of this stop, since the two small thick tooth portions 15b are in sliding contact with the outer peripheral surface of the thin continuous tooth 11a, the Geneva gear 12 is in the rotation stop state.

Eventually, since the Geneva gear 12 is overstepped several times, the end face of the engaging portion 13 contacts the stopper portion 14, the rotation of the Geneva gear 12 is blocked, and the movable shaft 2 is at the backward limit position, that is, the mechanical system. Can be reliably stopped at the origin of. 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 the subsequent position control. At this time, since the gap GP2 is formed in the axial direction between the inner bottom surface of the tubular portion 8 and the end portion of the screw portion 10, the screw portion 9 and the screw portion 10 are formed.
There is no bite between and.

Next, when a pulse of the required number of steps is applied to the motor 5 by the drive circuit to rotate the cylindrical portion 8 in the clockwise direction in FIG. 2 moves forward and stops at the target position.

As described above, since the stopper portion 14 stops the rotation of the Geneva gear 12 to stop the rectilinear motion of the movable shaft 2, there is no difference between the escape torque and the normal drive torque, and the drive torque is reduced. The circuit needs only the direction reversal function. Therefore, the drive circuit can have a simple structure and the cost can be reduced.

In the first embodiment, the partial gear 11 is composed of two teeth, but the number of teeth is determined as needed. The numbers of the large and thin tooth portions 15a and the small and thick tooth portions 15b of the Geneva gear 12 also change accordingly. Further, the origin position of the mechanical system may be the forward limit position, if necessary, instead of the backward limit position. At this time, the gap GP1 is formed in the axial direction, so that the difficult attachment between the screw portion 9 and the screw portion 10 does not occur. Further, the origin alignment can be set by a method of detecting an increase in the current of the motor 5 or a method of detecting the disturbance of the voltage waveform when the movable shaft 2 is stopped at the backward limit or the forward limit.

[0019]

Second Embodiment As shown in FIGS. 5 and 6, the second embodiment
The linear drive device 1 according to 1 is applied to a structure in which the movable shaft 2 is linearly moved while rotating, and includes a spline mechanism 18 and a motor 5 such as a step motor,
The movable shaft 2 is configured to move linearly while rotating. That is, the rotor 17 is inserted inside the stator 21 of the motor 5, and the movable shaft 2 that is movable in the axial direction as the rotation shaft of the rotor 17 is the motor case 5b.
It is axially movable and rotatably supported via the bearing portion 4 and the screw portion 10.

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. It is composed of a groove array. The threaded portion 10 formed on the outer peripheral surface of the movable shaft 2 and the threaded portion 9 formed on the inner peripheral surface of the tubular portion 8 fixed to the stator yoke 20 convert the rotational motion of the rotor 17 into a linear motion of the movable shaft 2. Convert.

Further, as a stop mechanism for stopping the movable shaft 2 in the advancing / retreating position, a missing gear 11 integrally formed with the rotor 17 and a Geneva gear 12 meshing with the missing gear 11 are provided inside the motor cases 5a and 5b. , Geneva gear 12
The linear motion range of the movable shaft 2 is restricted by restricting the rotation range of. The partial gear 11 has a thick tooth portion 15 and thin continuous teeth 11a. 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, which meshes with the partial gear 11, and a tooth groove 19c between these portions, which correspond to the linear motion region of
And a fan-shaped stopper portion 19 is formed.

The stopper mechanism (the missing gear 11 and the Geneva gear 12) may be provided outside the motor cases 5a and 5b. Further, the missing gear 11 may not be integral with the rotor 17 but may be a separate body.

Next, the operation will be described. In order to return the movable shaft 2 to the backward limit, that is, to the original position of the mechanical system at the initial stage of driving, pulses of an overstep number are sent to the motor 5 from a drive circuit (not shown) to rotate the rotor 17 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 pulse required for sending the movable shaft 2 to the target position is sent to the motor 5 by a drive circuit (not shown) to rotate the rotor 17 in the forward direction, the spline mechanism 18
Thus, the rotation of the rotor 17 is transmitted to the movable shaft 2. The rotary motion of the movable shaft 2 is generated by the screw portion 10 and the screw portion 9 of the tubular portion 8.
It is converted into a rectilinear motion by screwing with. Therefore, the movable shaft 2 moves forward while rotating and stops at the target position.
At this time, since the gap GP2 is formed in the axial direction, it is possible to prevent the screw portion 9 and the screw portion 10 from being difficultly attached to each other.

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 thin continuous teeth 11a come into contact with the two thick tooth portions 19b to keep the Geneva gear 12 from rotating. Further, the origin position of the mechanical system may be the forward limit position, if necessary, instead of the backward limit position. At this time, the gap GP1 is formed in the axial direction, so that the difficult attachment between the screw portion 9 and the screw portion 10 does not occur.

The reason why the pulses of the overstep number are sent to the motor 5 is to prevent the deviation between the origin of the mechanical system and the origin of the electrical system. Further, even if a power failure occurs during the operation of the motor 5 or a shift in the feed position of the movable shaft 2 occurs, the feed drive is performed with the above-mentioned number of oversteps to ensure a reliable origin position. Since they can be aligned, there is no malfunction in position control.

As described above, since the movable shaft 2 is made to move linearly while rotating, the conventional D hole is unnecessary, and therefore, the biting of the movable shaft 2 and the occurrence of torque cross can be prevented. Moreover, since the stopper mechanism is composed of the Geneva gear 12 and the missing gear 11, biting does not occur between the screw portion 9 and the screw portion 10.
Further, in the drive circuit, since it is only necessary to send the pulse of the overstep number to the motor 5 and then the pulse of the required step number in the opposite direction, the configuration of the drive circuit can be simplified.

[0028]

Third Embodiment As shown in FIG. 7, the third embodiment is an improvement of the stop mechanism of the second embodiment, in which a concave stop portion 22 is provided on the outer peripheral surface of the stopper portion 19 and the thin continuous teeth 11a. Utilizing the involute tooth surface on both ends of
They are used as the lock portion 23. When the missing gear 11 and the Geneva gear 12 are in the locked state, the stop portion 22 and the lock portion 23 are in contact with each other at two places (a portion and a portion) to disperse the force and prevent partial wear. To prevent. Therefore, at the stop position, since the two contact surfaces contact each other from different directions, there is no partial unevenness and the opposing force at the time of stop can be increased.

[0029]

Other Embodiments The transmission means 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 rotation-linear movement converting means forms a screw hole in the movable shaft 2, and fixes a screw rod in the screw portion 9 of this screw hole and the stator yoke 20.
You may comprise with the screw part 10 of this screw rod.

Each of the stop mechanisms of the first, second and third embodiments may be replaced with either a structure in which the movable shaft 2 moves straight in a non-rotating state, or a structure in which the movable shaft 2 moves straight while rotating. It can also be applied.

[0031]

[Incorporation Example] FIG. 8 shows a specific example in which the linear drive device 1 of the second embodiment is incorporated in the valve 24. The linear drive device 1 is fixed to the mounting surface 26 of the valve body 25 together with the seal member 28 on the motor case 5b side by a mounting screw 27. The movable shaft 2 penetrates through the holes of the bearing portion 4, the seal cap 29, and the seal member 28, faces the fluid passage 30 inside the valve body 25, and comes into contact with the valve seat 32 by the valve 31 fixed at the tip. ing.

Here, the center hole of the bearing portion 4, the seal cap 29 and the seal member 28 is formed to be slightly larger than the outer diameter of the movable shaft 2. As a result, the movable shaft 2 is supported by the rear screw portions 9 and 10, and is supported in the middle portion by the large hole so as to be movable in the radial direction. Therefore, when the valve 31 comes into contact with the valve seat 32, the movable shaft 2 is supported only at two points, that is, the screw portions 9 and 10 at the rear end and the valve 31 at the front end.

On the other hand, if the intermediate bearing portion 4, the seal cap 29, and the central hole of the seal member 28 also support the movable shaft 2, the movable shaft 2 supports three points as a whole. If the axes of the movable shafts 2 do not coincide with each other, the movable shaft 2 may be locked due to an excessive load.

However, with the above-mentioned two-point support, an excessive load is not applied, so that a malfunction does not occur due to a dimensional error or a position shift during assembly, and stable operation can be expected. In this way, the movable shaft 2 is supported at the front and rear ends at two points, and the movement in the radial direction with respect to the center hole of the bearing portion 4 and the seal member 28 is allowed in the middle portion, so that the core during assembly is assembled. The alignment accuracy may be low to some extent, which facilitates manufacturing.

The seal member 28 is the valve body 25.
O-ring 33 is interposed between the movable shaft 2 and
An O-ring 34 is interposed between the fluid passage 30 and the linear drive device 1 to block water intrusion.

The lead wire 36 of the coil 35 of the stator 21 is led out to the outside of the motor case 5b while being sandwiched by an elastic material 37 such as sponge or a rubber sheet.
When the linear drive device 1 is attached to the attachment surface 26, the elastic member 37 is attached to the attachment surface 26 and the waterproof cover 5c.
Since the lead wire 36 is elastically pressed against the lead wire 36, it is possible to obtain a reliable waterproof function at the lead-out portion of the lead wire 36. Conventionally, the lead wire position was adjusted and pressure-welded to a high-precision elastic material that matched the thickness and number of lead wires, but by using such a soft thick sheet material, it is easy to completely waterproof. Is obtained. It should be noted that, for further safety, it is possible to add another sheet between the waterproof cover 5c and the lead wire 36. The elastic material 37 eliminates direct contact between the circuit board 38 incorporated in the motor case 5a and the lead wire 36, and also helps prevent a short circuit accident.

[0037]

According to the first aspect of the present invention, a partly gear that rotates by a rotor of a motor, a Geneva gear that meshes with the partly gear, and an engaging portion are formed on the geneva gear. In addition, the structure has a stopper portion that restricts the rotation range of the Geneva gear, and restricts the linear movement range of the movable shaft by restricting the rotation range of the Geneva gear. Therefore, by stopping the rotation of the Geneva gear, the linear motion of the movable shaft can be stopped. As a result, there is no difference between the escape torque and the normal drive torque, and the drive circuit only needs the direction reversing function. Therefore, the drive circuit can have a simple structure and the cost can be reduced.

Further, according to the second aspect of the present invention, the Geneva is formed by forming the toothed gear rotated by the motor and the toothed portion meshing with the toothed portion of the toothed gear on the outer peripheral surface of the portion corresponding to the linear motion range of the movable shaft. Since it has a gear and has a structure that regulates the linear motion range of the movable shaft by regulating the rotation range of this Geneva gear,
The engaging portion of the Geneva gear and the stopper portion that engages with this can be made unnecessary in the first invention. Further, 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.

Further, in the case where the missing gear and the Geneva gear are in contact with each other on the two surfaces to be in the locked state, the partial abrasion is less and the opposing force at the time of locking can be increased.

[Brief description of drawings]

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

FIG. 2 is a front view showing a main part of a linear drive device.

FIG. 3 is a configuration diagram showing a cylindrical portion and a toothless gear thereof.

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

FIG. 5 is a cross-sectional view showing a linear drive device according to a second embodiment. In this figure, the upper part of the movable shaft is in the forward limit and the lower part of the movable shaft is in the backward limit with the center line of the movable shaft as a boundary.

FIG. 6 is an enlarged front view of a missing gear and a Geneva gear.

FIG. 7 is an enlarged front view of a missing gear and a Geneva gear according to a third embodiment.

FIG. 8 is a sectional view of an example in which the linear drive device according to the second embodiment is incorporated in a valve.

[Explanation of symbols]

1 Linear Drive Device 19 Stopper Part 2 Movable Shaft 19a Thin Tooth Part 3 Housing 19b Thick Tooth Part 4 Bearing Part 19c Tooth Groove 5 Motor 20 Stator Yoke 5a Motor Case 21 Stator 5b Motor Case 22 Stop Part 5c Waterproof Cover 23 Lock Part 6 D Hole 24 Valve 7 Motor shaft 25 Valve body 8 Tube 26 Mounting surface 9 Screw 27 Mounting screw 10 Thread 28 Seal member 11 Missing gear 30 Fluid passage 11a Thin continuous tooth 31 Valve 12 Geneva gear 32 Valve seat 13 Engagement 33 O-ring 14 Stopper part 34 O-ring 15 Tooth part 35 Coil 15a Large thin tooth part 36 Lead wire 15b Small thickness tooth part 37 Elastic material 16 Base plate 38 Circuit board 17 Rotor GP1 Gap 18 Spline mechanism GP2 Gap

Claims (3)

[Claims] 1. A toothless gear (11) rotated by a rotor (17) of a motor (5), a tubular portion (8) formed with a screw portion (9) rotated by the rotor (17), and the screw portion. A movable shaft (2) which forms a screw portion (10) to be screwed into (9) and is capable of linearly moving in the axial direction of the motor (5).
And a Geneva gear (12) that meshes with the missing gear (11)
And an engaging portion (13) formed on the Geneva gear (12)
And the Geneva gear (12) by engaging with the engaging portion (13).
And a stopper portion (14) for restricting the rotation range of the movable shaft (2) by restricting the rotation range of the Geneva gear (12). 1). 2. A female screw part (9) and a male screw part (1).
The rotation of the motor (5) is screwed with the movable shaft (2).
In the linear drive device (1) for converting the linear movement of the movable shaft (2) to the linear motion of the movable shaft (2), the toothless portion (11) rotated by the motor (5) and the tooth portion (15) of the toothless gear (11). A Geneva gear (12) having tooth portions (19a, 19b) meshing with each other formed on the outer peripheral surface of a portion corresponding to the linear motion region of the movable shaft (2), and said Geneva gear (12)
A linear drive device (1) characterized in that the linear movement region of the movable shaft (2) is regulated by regulating the rotation region of the linear drive device (1). 3. A female screw part (9) and a male screw part (1).
The rotation of the motor (5) is screwed with the movable shaft (2).
In a linear drive device (1) for converting a linear movement of a movable shaft (2) into a linear motion, a missing gear (11) rotated by a motor (5) meshes with the missing gear (11), The Geneva gear (12) is provided with a stop portion (22) that engages with two surfaces of the lock portion (23) of (11) to stop, and the movable shaft (12) is regulated by the rotation range of the Geneva gear (12). A linear drive device (1), which is characterized in that it regulates the rectilinear motion range of 2).