JPH06193699A - Automatic decelerating device - Google Patents

Abstract

PURPOSE:To provide an automatic decelerating device which is able to prolong the service life in the constituent parts by smoothly outputting the commensurable turning power with the increase of load torque in an output shaft. CONSTITUTION:This automatic decelerating device is so constituted that the rate of axial travel in relation to a unit turning angle of a shift ring 7 is reduced to some extent, whereby turning power can be outputted in conformity with the load torque to be produced in the output shaft 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic deceleration mechanism, and more particularly to an automatic deceleration mechanism adapted to automatically reduce the rotational speed of an output shaft as load torque increases.

[0002]

[Prior art example] Conventionally, as an automatic deceleration mechanism, an actual reduction gear 62-
There is one described in No. 107145. This automatic speed reduction mechanism is configured such that a power transmission device from an input shaft to an output shaft includes a plurality of conical wheels that make planetary motions, and a speed change gear that frictionally engages an inclined surface and an inner peripheral surface of the conical wheels. Set up a ring,
When one end of the plurality of spring rods supported at the casing side is engaged with the shift ring and the shift ring is rotated by a reaction force due to the load torque of the output shaft, the shift ring moves the The length of the spring rod is constrained, and the spring rod is forcibly pulled by the bending amount of the spring rod to move downward in the axial direction.

[0003]

However, according to the screw tightening machine having the automatic speed reducing mechanism constructed as described above, when the output shaft is locked by the seating of the screw, the speed change ring has the torque of the output shaft. The spring rod is rotated while being bent by the reaction force, and is moved in the axial direction from the high speed side to the low speed side by the restraint of the spring rod.

In this case, the amount of movement of the transmission ring in the axial direction with respect to the unit rotation angle is small at the initial stage of rotation and increases as the rotation angle increases. That is, as the load torque of the output shaft increases due to the seating of the screw,
The amount of movement in the axial direction with respect to the rotation angle of the speed change ring becomes a large ratio, and the contact point between the speed change ring and the tapered roller is not smoothly moved from the high speed side to the low speed side, but is moved in an unreasonable state. There is a problem of shortening the life.

The present invention is proposed in view of the above problems, and an object of the present invention is to set the ratio of the axial movement amount to the rotation angle of a transmission ring that rotates with the generation of load torque on the output shaft to the lower speed side. It is an object of the present invention to provide an automatic deceleration mechanism that can smoothly move the speed change ring from the high speed side to the low speed side by reducing the number, and consequently can prolong the life of parts.

[0006]

In order to achieve the above object, the present invention provides a power transmission device in which a plurality of conical wheels make planetary motions in a stationary member having an input shaft and an output shaft rotatably. The output shaft is driven via the transmission device, and a transmission ring having an inner peripheral surface that constantly frictionally engages with one inclined surface of each conical wheel is provided to increase the load torque on the output shaft. An automatic speed reduction mechanism configured to change the engagement position between the conical wheel and the speed change ring in the axial direction by the rotation of the speed change ring to automatically reduce the rotational speed of the output shaft. , A plurality of arms that urge the shift ring toward the upper stationary member side with an ammunition, and that have an inclination of a predetermined angle between the stationary member and the shift ring and are engaged so that the angle can change. A rod is installed to increase the load torque of the output shaft. At this time, the tilt angle of the arm rod decreases with the rotation of the speed change ring, so that the amount of movement of the speed change ring in the axial direction decreases in inverse proportion to the rotation angle of the speed change ring. It is what

Further, the automatic reduction mechanism is provided between the outer peripheral surface of the transmission ring and the inner peripheral surface of the stationary member facing the transmission ring.
A spiral groove having a predetermined lead angle is formed oppositely, and a steel ball is fitted into the spiral groove to form a ball screw structure so that the ratio between the rotation angle of the speed change ring and the movement amount in the axial direction is constant. It is characterized by doing so.

[0008]

With the above construction, when a load torque is generated on the output shaft and the reaction ring rotates the transmission ring, the friction contact point between the transmission ring and the tapered roller is short on the high speed side. Since it engages with the circumferential portion, the amount of rolling of the conical wheel per unit rotation angle of the transmission ring is large, and the sliding resistance can be small even if the amount of movement of the transmission ring in the axial direction is large. Further, as the speed change ring moves toward the low speed side, it engages with the long diameter portion of the conical roller, so the amount of rolling of the conical wheel per unit rotation angle of the speed change ring decreases, and the speed change ring moves in the axial direction. Moving it causes a large amount of slip resistance, but since the amount of movement of the speed change ring in the axial direction per unit rotation angle during this period is reduced, the speed change ring can be smoothly moved from the high speed side to the low speed side. No ring or conical wheel damage.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An automatic deceleration mechanism of the present invention will be described based on the embodiments of the drawings. FIG. 1 is a sectional view of the automatic speed reduction mechanism of the first embodiment. The automatic reduction mechanism is roughly classified into a cylindrical casing 1, an input bearing body 2 fixed to the upper end of the casing 1, and an output bearing body 4 fixed to the lower end of the casing 1, and a stationary member, and the input bearing. An input shaft 3 supported by the body 2, an output shaft 5 supported by the output bearing body 4,
A power transmission device 6 interposed between the input shaft 3 and the output shaft 5, and a speed change ring 7 frictionally engaged with the power transmission device 6.
And an ammunition 8 for urging the speed change ring 7 toward the input bearing body 2 forming an upper stationary member, and a plurality of arm rods 9 for moving the speed change ring 7 in the axial direction.

The casing 1 is composed of a relatively thin tubular body, and is configured such that input and output bearing bodies 2 and 4 which will be described later are watertightly fitted and fixed to upper and lower end portions of an inner peripheral surface thereof. ing. The input bearing body 2 is composed of a block body having an oil supply hole 2a on the upper surface and a circular cross section in the horizontal direction, and a ring portion projecting inward, and the outer peripheral surface of the block body is the inner peripheral surface of the upper end portion of the casing 1. It is configured to be watertightly fitted and fixed via an O-ring 2f, and the bearing 2b and the oil seal 2c are inserted and fitted on the inner peripheral surface thereof. Further, a notch 2h having an inclined surface 2g for holding an arm rod 9 which will be described later is cut in the ring portion, and the arm rod 9 is provided in the notch 2h.
One end of the arm rod 9 is formed in a spherical shape so that the arm can be swung, and the arm rod 9 is supported by a locking hole 2 provided at a position continuous with the notch 2h of the block body.

The input shaft 3 is composed of a stepped shaft body, and the stepped portion is inserted into and supported by the bearing 2b of the input bearing body 2 and the oil seal 2c, and the curved surface is formed at the lower end portion thereof. There is provided an input disc 3a forming 3c. The output bearing body 4 is composed of a block body having a circular horizontal cross section, is watertightly fitted and fixed to the inner peripheral surface of the lower end portion of the casing 1 through an O-ring 4a, and the inner peripheral surface thereof is a bearing. Four
b and the oil seal 4c are inserted and fitted.

The output shaft 5 comprises an elongated first shaft 5a having a stepped portion and a second shaft 5b connected to the first shaft 5a so as not to rotate relative to the first shaft 5a. The portion is fitted in the bearing 4b and the oil seal 4c of the output bearing body 4 and is rotatably and watertightly held. Further, a V-shaped notch surface is formed in a position facing the upper end surface of the second shaft 5b and the lower end surface of the cam disk 5d described later, and the steel ball 10 is inserted so as to be sandwiched by the notch surface. Moreover, a spring is fitted and inserted between the first shaft 5a and the cam disk 5d, and a pressure adjusting mechanism is constituted by these respective parts.

A power transmission device 6 is interposed between the input shaft 3 and the output shaft 5. The power transmission device 6 generally adopts a planetary transmission structure, and is composed of a plurality of conical wheels 6a each having an outer peripheral surface that is an inclined conical surface. The conical wheels 6a are arranged at equal intervals in the circumferential direction on a retainer 6b which is rotatably supported on the upper end of the output shaft 5, and the generatrix on the conical surface 6c is vertical. The concave curved surface 6d formed on the base shaft portion of the conical wheel 6a is engaged with the curved peripheral surface 3c of the input disc 3a of the input shaft, while the output shaft 5 is held on the back surface of the conical wheel 6a. By engaging the transmission peripheral surface 5e of the disk-shaped cam disk 5d, the rotational power from the input shaft 3 is transmitted to the output shaft 5 by the planetary motion of the conical wheel 6a.

The speed change ring 7 is composed of an annular body having a short length that is loosely fitted to the inner peripheral surface of the casing 1, and has an annular projecting surface 7a on the inner peripheral surface of which the diameter is reduced from the inner peripheral surface. The projection surface 7a is frictionally engaged with the conical surface 6c of each conical roller 6a in the power transmission device 6. Further, an ammunition machine 8 is hung between the upper surface of the speed change ring 7 and the lower surface of the input bearing body 2 so that the speed change ring 7 is always pulled upward and urged, while the upper surface of the speed change ring 7 is provided with a plurality of bullets. Concave portions 7b forming a concave spherical surface are formed at equal intervals, and the concave portion 7b is configured to guide the other end of the arm rod 9 whose one end is guided to the engaging hole 2e in a spherical shape. There is.

The arm rod 9 is made of a linear elastic wire rod having a relatively large diameter, and when the output shaft 5 is in an unloaded state, it is inclined at a predetermined angle θ between the engaging hole 2e and the recess 7b. In this state, the bullet 2 is attached so as to stretch between the two 2e and 7b. When a load is applied to the output shaft 5, the conical surface 6c of the conical roller 6a and the annular projection 7a of the speed change ring 7 are frictionally engaged with each other by the speed change ring 7a.
Rotate.

As the tilt angle θ of the arm rod 9 decreases, the speed change ring 7 moves downward in the axial direction against the bias of the bullet 8. In this case, the shift amount of the transmission ring 7 in the axial direction with respect to the unit rotation angle decreases as the inclination angle θ decreases. That is, as the rotation angle of the speed change ring 7 increases, the amount of rolling of the conical roller 6a decreases with respect to the unit rotation angle of the speed change ring 7 and the sliding resistance in the axial direction of the speed change ring 7 increases, but The ring 7 for a unit rotation angle of 7
The engagement position between the annular projection 7a and the conical surface 6c of the conical wheel 6a is reduced from the high speed side (small circumference major axis side) to the low speed side (large circumference major axis side), and the unit of the transmission ring 7 is reduced. The slip resistance with respect to the rotation angle does not increase, the movement is smooth, and when the load on the output shaft 5 increases as shown in FIG. 3, the rotation speed of the output shaft 5 decreases and the rotation of the output shaft 5 stops. At this time, the maximum torque can be output without fluctuation of the output torque due to the sliding resistance between the transmission ring 7 and the conical wheel 6a.

Further, the interior of the casing 1 assembled as described above is filled with traction oil to increase the friction coefficient to improve the transmission efficiency and to perform the lubricating action to prevent the seizure of the members. Is made. Next, the operation of the first embodiment constructed as above will be described. The embodiment is mainly applied to an automatic screw fastening machine for fastening screws.

In this case, a tool such as a driver bit is set on the output shaft 5, the tool is engaged with a driver groove of a screw or the like, and rotational power is applied to the input shaft 3 by a drive source (not shown). . The input shaft 3 to which the rotational power is applied rotates the conical wheel 6a through the input disc 3a,
The cam disk 10, the pressure adjusting mechanism, and the output shaft 5 are connected to the input disk 3
Rotate in the opposite direction to the rotation direction of a.

As the screws that are screwed by the rotational drive of the output shaft 5 approach the fastening, the load on the output shaft 5 increases and the transmission ring 7 frictionally engaged with the conical wheel 6a rotates. The tilt angle θ of the arm rod 9 decreases in the vertical direction.
That is, the lower end of the arm rod 9 swings in the vertical direction while drawing a circular arc locus with the locking hole 2e as a fulcrum.

As a result, the speed change ring 7 pushed down by the arm rod 9 moves the engagement position of the conical roller 6a from the high speed side to the low speed side, and reduces the rotational speed thereof. Moreover, at this time, as the rotation angle of the transmission ring 7 increases, the amount of movement in the axial direction with respect to the unit rotation angle decreases in inverse proportion. Therefore, the amount of rolling of the tapered roller 6a per unit rotation angle of the speed change ring 7 is reduced, and the amount of axial movement is reduced to reduce the amount of rolling in the tapered roller 6a and the speed change ring 7.
The ratio of the amount of slip to the amount of rolling between and is reduced, and the slip resistance is reduced to prevent an increase in the slip resistance per unit rotation angle of the speed change ring 7 to prevent the speed change ring 7 and the tapered roller 6a from being damaged on the low speed side. Becomes

Next, the automatic deceleration mechanism of the second embodiment will be described. FIG. 2 is a sectional view of the automatic speed reduction mechanism of the second embodiment. The automatic reduction mechanism is roughly divided into a cylindrical casing 100, an input bearing body 200 fixed to the upper end of the casing 100, and an output bearing body 400 fixed to the lower end of the casing 100, and a stationary member. The input shaft 300 supported by the bearing body 200 and the output bearing body 4
00, a power transmission device 6 interposed between the input shaft 300 and the output shaft 500, a transmission ring 700 frictionally engaged with the power transmission device 6, and the transmission ring 700. Input bearing body 2 which forms the upper stationary member
The ball screw structure described later is provided between the inner peripheral surface of the casing 100 and the outer peripheral surface of the transmission ring 700.

The casing 100 is composed of a tubular body having a spiral groove 100a, which will be described later, formed on the inner peripheral surface thereof, and the input and output bearings 200 and 4 described below are provided on the upper and lower ends of the inner peripheral surface.
00 is watertightly fitted and fixed. The input bearing body 200 is composed of a block body having an oil supply hole 200a on its upper surface and having a circular horizontal cross section. The outer peripheral surface of the block body is watertightly fitted to the inner peripheral surface of the upper end portion of the casing 100 via an O-ring 200f. The bearing 200b and the oil seal 200c are inserted into the inner peripheral surface of the bearing 200b and fixed together.

The input shaft 300 is composed of a stepped shaft body, and the stepped portion is inserted into the bearing 200b and the oil seal 200c to be rotatably and watertightly supported. An input disc 300a having a curved surface 300c is provided at the lower end thereof. The output bearing body 40
Reference numeral 0 denotes a block body having a circular horizontal cross section, the outer peripheral surface of which is watertightly fitted and fixed to the inner peripheral surface of the lower end portion of the casing 100 via an O-ring 400a, and the inner peripheral surface of which has a bearing 400b. , And the oil seal 400c are inserted.

The output shaft 500 is an elongated first stepped member.
It comprises a shaft 500a and a second shaft 500b connected to the first shaft 500a so as not to rotate relative to the first shaft 500a. The stepped portion of the first shaft 500a is inserted into the bearing 400b of the output bearing body 400 to be rotatable. And it is kept watertight. Further the second axis 500
A V-shaped notch surface is cut at a position opposite to the upper end surface of b and the lower end surface of the cam disk 500d described later, and the steel ball 10 is fitted so as to be sandwiched by the notch surface. One shaft 500a and cam disk 500d
A spring is fitted between and, and these parts constitute a pressure adjusting mechanism.

A power transmission device 6 is interposed between the input shaft 300 and the output shaft 500. The power transmission device 6 is composed of a plurality of conical wheels 6a each having a conical surface with an inclined outer peripheral surface by a planetary transmission structure which is exactly the same as that of the first embodiment described above. The retainer 6b rotatably supported on the upper end of the shaft 500 is arranged at equal intervals in the circumferential direction and the generatrix on the conical surface 6c is in the vertical direction. The input disc 300a on the input shaft 300 is formed on the formed concave curved surface 6d.
While engaging the curved peripheral surface 300c, the conical wheel 6a
The transmission peripheral surface 500e of the disk-shaped cam disk 500d held by the output shaft 500 is engaged with the rear surface of the shaft, and the rotational power from the input shaft 300 is transmitted to the output shaft 500 by the planetary motion of the conical wheel 6a. Is made to do.

The speed change ring 700 is composed of an annular body having a short length that is loosely fitted to the inner peripheral surface of the casing 100, and the inner peripheral surface of the annular projecting surface 7 is reduced in diameter from the inner peripheral surface.
00a, and the protruding surface 700a is frictionally engaged with the conical surface 6c of each conical roller 6a in the power transmission device 6. Further, the spiral groove 10 having a predetermined lead angle is provided between the outer peripheral surface of the speed change ring 700 and the inner peripheral surface of the casing 100 opposed thereto.
0a, 900 are formed, a steel ball 900a is rollably fitted between the spiral grooves 100a, 900 to form a ball screw structure, and when the transmission ring 700 rotates in the circumferential direction, the ball screw Depending on the structure, it is designed to move simultaneously in the axial direction.

On the other hand, on the lower surface of the transmission ring 700,
The speed change ring 70 is provided between the upper surface of the output bearing body 400 and the spring bearing ring 800b having the bearing 800a.
A compression ammunition 800 for urging 0 to the upper stationary member side is interposed. When a load is generated on the output shaft 500,
When the speed change ring 700 rotates, the speed change ring 700 moves axially downward along the lead angles of the spiral grooves 100a and 900 to pressurize the compression ammunition 800.

This downward movement causes the output shaft 500 to move.
The rotational speed of is reduced and the output torque is increased. The lead angle of the spiral groove 900 is set to an angle that enables smooth deceleration. In addition, the casing 100 assembled as described above is filled with traction oil to increase the coefficient of friction to improve the transmission efficiency and to perform the lubricating action to prevent the seizure of the member. ing.

Next, the operation of the second embodiment will be described.
This embodiment is applied to a screw tightening machine which mainly tightens screws as in the first embodiment described above. In this case, output shaft 5
For example, a tool (not shown) such as a driver bit is set to 00, and the tool is engaged with a driver groove of screws, and rotational power is applied to the input shaft 300 by a drive source (not shown).

The input shaft 300 to which the rotational power is applied causes the conical roller 6a to rotate on its own via the drive transmission 300a to rotate the output shaft 500 in the direction opposite to the input direction via the cam disk 500d. As the screws that are screwed by the rotational drive of the output shaft 500 approach the tightening, the load torque on the output shaft increases, and the speed change ring 70 frictionally engaged with the tapered roller 6a.
0 rotates in the revolving direction of the conical wheel 6a.

By this rotation, the transmission ring 700 moves axially downward by the action of the ball screw structure without changing the amount of movement in the axial direction with respect to the unit rotation angle of the transmission ring 700, and engages with the conical roller 6a. The position is comfortably moved to reduce the rotation speed, and a predetermined torque is output from the output shaft 500. Although the spiral groove is formed on the inner peripheral surface of the casing in the second embodiment, it may be formed separately for processing.

[0032]

As described above, according to the present invention, when the engagement position between the speed change ring that determines the reduction ratio and the tapered roller is moved, the amount of movement of the speed change ring in the axial direction per unit rotation angle is Since it is configured to be constant on the high-speed side and low-speed side, or to decrease on the low-speed side, the amount of rolling of the conical roller per unit rotation angle of the speed-change ring is reduced, and the slip resistance due to the axial movement of the speed-change ring is reduced. The speed change ring can be gradually moved on the low speed side, and the damage to the speed change ring and the conical wheels is eliminated, and there is no torque fluctuation of the output shaft due to this extra sliding resistance. The effect that the output torque can be output is obtained.

[Brief description of drawings]

FIG. 1 is a side sectional view of a first embodiment of the present invention.

FIG. 2 is a side sectional view of a second embodiment of the present invention.

FIG. 3 is a diagram showing a relationship between a rotation speed and an output torque of an output shaft.

[Explanation of symbols]

 3 input shaft 5 output shaft 6 power transmission device 6a conical wheel 7 speed change ring 8 ammunition machine 9 arm rod 900 spiral groove 100a spiral groove

Claims (2)

[Claims] 1. A power transmission device in which a plurality of conical wheels make planetary motions is provided in a stationary member having an input shaft and an output shaft rotatably, and the output shaft is driven via the transmission device. A gearshift ring having an inner peripheral surface that is always in frictional engagement with one inclined surface of each conical roller is provided, and the gearshifting with the conical roller is performed by rotation of the gearshift ring as the load torque on the output shaft increases. An automatic deceleration mechanism configured to automatically reduce the rotational speed of the output shaft by varying the engagement position with the ring in the axial direction, wherein the transmission ring is mounted on the upper stationary member side. A plurality of arm rods having a predetermined angle of inclination and engaged so as to be capable of changing the angle are arranged between the stationary member and the speed change ring, and the load torque of the output shaft is When increased,
As the tilt angle of the arm rod decreases with the rotation of the speed change ring, the amount of movement of the speed change ring in the axial direction decreases in inverse proportion to the rotation angle of the speed change ring. Automatic reduction mechanism. 2. A power transmission device in which a plurality of conical wheels make a planetary motion is provided in a stationary member that rotatably has an input shaft and an output shaft, and the output shaft is driven via the transmission device. A gearshift ring having an inner peripheral surface that is always in frictional engagement with one inclined surface of each conical roller is provided, and the gearshifting with the conical roller is performed by rotation of the gearshift ring as the load torque on the output shaft increases. An automatic deceleration mechanism configured to automatically reduce the rotational speed of the output shaft by varying the engagement position with a ring in the axial direction, the outer peripheral surface of the transmission ring facing the outer peripheral surface of the transmission ring. A spiral groove having a predetermined lead angle is formed between the stationary member and the inner peripheral surface of the stationary member, and a steel ball is inserted into the spiral groove to form a ball screw structure. To keep the ratio with the movement amount of Automatic transmission mechanism, characterized in that the.