JP2008170010A - Power transmission device provided with torque limiter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To increase designing flexibility of a power transmission device having a gear wheel row and provided with a torque limiter, and to attain cost reduction of the power transmission device provided with the torque limiter. <P>SOLUTION: The torque limiter is constituted by inserting and fitting a cylinder body part applied with slitting of a second rotation shaft 31 press-fitted with an annular spring 41 having a part cut in an axial direction and outwardly biased to a first rotation shaft 21 having a hollow part, and the torque limiter is fixed to the gear positioned at an end of power transmission of the power transmission device having the gear wheel row. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a power transmission device having a gear train, and more particularly to a power transmission device including a torque limiter that limits a torque to a predetermined value or less.

  A reduction gear combined with a plurality of gears is transmitted to a target device (hereinafter referred to as a load device) to drive the rotational force of a motor at a predetermined rotational speed and torque in a vending machine, ATM, curtain opening / closing mechanism, etc. It is widely used to In such a reduction gear, since a large torque is generated in the output rotation shaft with respect to the input rotation shaft to which the rotation of the motor is applied, an excessive torque is applied to the load for some reason. Unexpected accidents such as damage to the gears in the reduction gear or seizure of the motor on the input side may occur.

  In order to prevent the occurrence of such an unexpected accident, it is necessary to limit the torque resistance applied to the output rotation shaft of the reduction gear to a predetermined value or less. As a conventional speed reducer having such a function, one having a torque limiter using a disc spring on one of the shafts of a plurality of gears constituting the speed reducer is known. A typical torque limiter using a disc spring has a structure in which a spur gear loosely fitted on a rotating shaft is sandwiched between two friction plates. One friction plate is integrated with the rotating shaft, but the other friction plate is non-rotating with respect to the rotating shaft but can move parallel to the rotating shaft. The other friction plate is pressed against the spur gear by a disc spring, and the spur gear is also pressed against one of the friction plates. Here, the spring pressure of the disc spring is determined by the position in the direction of the rotating shaft such as a presser ring for pressing the side opposite to the spur gear side that is press-fitted into the rotating shaft.

  With such a configuration, when the load of the spur gear becomes excessive, slip occurs between one friction plate and the spur gear and between the other friction plate and the spur gear, and the spur gear is loosely fitted to the rotating shaft. The torque transmitted to is limited.

  However, in the torque limiter using the conventional disc spring as described above, the diameter of the friction plate and the disc spring is larger than the diameter of the rotating shaft on which the friction plate and the disc spring are mounted. There were restrictions on the location. The spur gear must be larger than the diameter of the friction plate or the like. In other words, the power transmission device provided with a torque limiter using a disc spring has a low degree of design freedom.

  Furthermore, the power transmission device provided with a torque limiter using a disc spring has a large number of parts, which makes it difficult to assemble, increases the number of steps, and increases the cost.

  The present invention has been made in view of the above-described conventional problems, and provides a power transmission device as a speed reducer or speed increasing device provided with a torque limiter that has a high degree of design freedom and can be reduced in cost. It is intended to do.

  The power transmission device of the invention according to the present application has a first rotating shaft provided with a concentric hollow portion, and an outer diameter substantially the same as the inner diameter of the hollow portion of the first rotating shaft, A second rotating shaft having a cylindrical portion that has been slotted from the end, and the second rotating shaft is housed in the cylindrical portion of the second rotating shaft, and is attached so as to increase the inner diameter of the cylindrical portion. A torque limiter having a structure in which a cylindrical portion of the second rotating shaft in which the elastic member is housed is press-fitted into a hollow portion of the first rotating shaft, and an input rotating shaft And a gear mechanism comprising a plurality of rotary shafts for transmitting the rotational force applied to the input rotary shaft to the output rotary shaft via a gear, and at least one of these gear mechanisms. A power transmission device in which the torque limiter is mounted as the rotating shaft And the large diameter part which has an outer shape larger than the outer diameter of this rotating shaft is provided in the edge part by which the said slot process of the said cylindrical body part of the said 2nd rotating shaft was given, The said 2nd When the cylindrical portion of the rotating shaft is press-fitted into the hollow portion of the first rotating shaft, the large diameter portion of the end portion of the cylindrical body protrudes from the end portion of the first rotating shaft and is locked. It is comprised by these.

  According to the present invention, since the torque limiter of the present invention can be loaded on any of a plurality of rotating shafts in the power transmission device, the torque value to be limited can be easily set.

  In addition, since the torque limiter according to the present invention can be housed in the rotating shaft of the power transmission device and can be made extremely small, the design flexibility of the entire power transmission device equipped with such a torque limiter is large, and the size can be reduced. It can contribute greatly. Furthermore, it can contribute to the cost reduction of the speed reducer provided with the torque limiter.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 shows an embodiment in which the present invention is applied to a speed reducer comprising a three-stage gear mechanism. The power from the motor is fixed to the input rotating shaft 11 and transmitted to the spur gear 14a fixed to the rotating shaft 13a of the first stage gear mechanism and the number of teeth n through the motor pinion 12 having the number of teeth m. It is done. Here, in the case of a reduction gear, n is a value larger than m. The rotational speed of the rotary shaft 13a is reduced to m / n of the rotational speed of the input rotary shaft 11. Assuming that there is no energy loss, the torque of the rotating shaft 13a is n / m times the torque of the input rotating shaft 11.

  A pinion 15a is also fixed to the rotary shaft 13a, and the pinion 15a rotates at the same speed as the spur gear 14a. The power of the rotating shaft 13a is transmitted to the spur gear 14b fixed to the rotating shaft 13b of the second gear mechanism through the pinion 15a. Since the number of teeth of the spur gear 14b fixed to the rotating shaft 13b is set to a value larger than the number of teeth of the pinion 15a fixed to the rotating shaft 13a, the rotational speed of the rotating shaft 13b is While decreasing from the rotational speed, the torque of the rotating shaft 13b increases more than the torque of the rotating shaft 13a.

  Similarly, a pinion 15b is also fixed to the rotary shaft 13b, and the pinion 15b rotates at the same speed as the spur gear 14b. The power of the rotating shaft 13b is transmitted to a spur gear 14c fixed to an output rotating shaft 16 as a third stage gear mechanism through a pinion 15b. Since the number of teeth of the spur gear 14c fixed to the output rotating shaft 16 is set to a value larger than the number of teeth of the pinion 15b fixed to the rotating shaft 13b, the rotational speed of the output rotating shaft 16 is set to the rotating shaft. The torque of the output rotating shaft 16 increases more than the torque of the rotating shaft 13b while decreasing from the rotational speed of 13b.

  As a result, through the above three-stage gear mechanism, the rotation speed of the output rotation shaft 16 is greatly reduced from the rotation speed of the input rotation shaft 11, and the torque of the output rotation shaft 16 is larger than the torque of the input rotation shaft 11. Increase greatly. That is, in the speed reducer, the rotation speed of the output rotation shaft is decelerated more than the rotation speed of the input rotation shaft, and a torque larger than the torque applied to the input rotation shaft can be obtained on the output rotation shaft.

  Here, a torque limiter, which will be described in detail later, is attached to the output rotating shaft 16. The torque limiter includes a first rotating shaft 21 and a second rotating shaft 31 that are concentric with each other.

  FIG. 2 shows a first rotating shaft 21 of the torque limiter. The first rotating shaft 21 is provided with a knurled portion 22 for strengthening the coupling between the two when a gear is press-fitted. A first hollow portion 23 is provided coaxially at one end of the first rotating shaft 21. In addition, a second hollow portion 24 having an inner diameter larger than that of the first hollow portion 23 is coaxially provided at an end portion of the first hollow portion 23 opposite to the open end.

  FIG. 3A is a side view showing, in section, a part of the second rotating shaft 31 whose one end is connected to a load device (not shown). The second rotating shaft 31 has substantially the same outer diameter as that of the first rotating shaft 21 shown in FIG. 2, and one end 32 thereof has a part of its outer peripheral surface cut to be flat, and this portion is used as a load device. The rotation output of the speed reducer is transmitted to the load device by being inserted into an insertion hole (not shown) having substantially the same shape as the one end 32 of the second rotation shaft 31. A cylindrical body portion 33 is provided at the other end of the second rotation shaft 31. The cylindrical body portion 33 has an outer diameter that is substantially the same as the inner diameter of the first hollow portion 23 of the first rotating shaft 21, and a large-diameter portion 34 having an outer diameter larger than that of the cylindrical body portion 33 is formed at the tip portion thereof. Is formed. The outer diameter of the large diameter portion 34 is substantially the same as the inner diameter of the second hollow portion 24 of the first rotating shaft 21. Further, the cylindrical body portion 33 is provided with a slit 35 over almost the entire length in the axial direction including the large diameter portion 34. Further, a groove 36 serving as an oil reservoir is provided on a part of the outer periphery of the main body 33. Durability can be improved by lubricating the groove 36.

  FIG. 3B is a plan view of the second rotating shaft 31 as viewed from the end face on the cylindrical body 33 side. An annular spring 41 that is partially cut in the axial direction and biased outward is loaded inside the cylindrical body portion 33 of the second rotating shaft 31. The material of the annular spring 41 is steel, stainless steel or the like, and so-called spring pins can also be used as the annular spring. Further, the annular spring 41 is not limited to the shape and material described above, and may be an elastic body such as rubber. Further, as long as it is an elastic body, the annular spring 41 does not need to be annular and may be solid without a hollow portion. These are collectively referred to as elastic members. By lightly press-fitting the annular spring 41 into the cylindrical body portion 33 of the second rotating shaft 31, the cylindrical body portion 33 provided with the slit 35 is urged outward. This stabilizes the limit torque value in the torque limiter.

  FIG. 4 is a diagram illustrating a state where the first rotating shaft 21 and the second rotating shaft 31 are connected to each other. In the drawing, a part of the lower end portion of the second rotating shaft 31 is shown in a sectional view. The second rotating shaft 31 loaded with the annular spring 41 is inserted into the first hollow portion 23 of the first rotating shaft 21, and the large-diameter portion 34 of the cylindrical body portion 33 of the second rotating shaft 31 is inserted. The first rotary shaft 21 and the second rotary shaft 31 are prevented from being detached by fitting into the second hollow portion 24 of the first rotary shaft 21. In the state where the first rotary shaft 21 and the second rotary shaft 31 are connected, oil is used to prevent seizure when the slip rotation is performed, but the groove 36 of the second rotary shaft 31 is Acts as a sump. The width and the number of strips of the groove 36 can be appropriately determined according to the limit torque value and the durability condition.

  FIG. 5 is a completed view of the torque limiter showing a state in which the first rotating shaft 21 and the second rotating shaft 31 are connected to each other. A force is exerted outwardly from the central axis on the cylindrical portion 33 of the second rotating shaft 31 by the annular spring 41, and the outer wall 33 of the cylindrical portion of the second rotating shaft 31 and the first rotation shaft 21. Friction occurs between the inner wall of the first hollow portion 23, and torque is transmitted to the load device via the one end 32 of the second rotating shaft 31 until the torque reaches a predetermined value. However, when the torque exceeds the frictional force, the outer wall of the main body portion of the cylindrical body portion 33 of the second rotating shaft 31 and the inner wall of the first hollow portion 23 of the first rotating shaft 21 begin to slip and become loaded. The transmitted torque is limited, and the function of the torque limiter works.

  The torque limit value is determined by the contact area between the outer wall of the main body portion of the cylindrical portion 33 of the second rotating shaft 31 and the inner wall of the first hollow portion 23 of the first rotating shaft 21 and the annular spring 41 (elastic member). By controlling the outward urging force due to, it can be made stable with little variation. The contact area is controlled by the length and outer diameter of the cylindrical portion 33 of the second rotating shaft 31, the number and width of the slits 35 provided in the cylindrical portion 33, and the number and width of the grooves 36. can do.

  In the speed reducer described above, the torque limiter is configured by mutually connecting the first rotating shaft 21 and the second rotating shaft 31 having substantially the same outer diameter, and thus is compact as a whole. And since the external appearance similar to the other rotating shaft in a deceleration device is exhibited, the external appearance of the whole apparatus is excellent.

  FIG. 6 is a diagram in which a first rotary shaft 21 and a second rotary shaft 31 which are different from the above-described rotary shafts are fitted and a part thereof is a cross section. In FIG. 6, the reference numerals of the parts having the same functions as the reference numerals in FIGS. 2 to 5 are the same as those in FIGS. The first rotating shaft 21 is provided with a first hollow portion 23 penetrating therethrough. One end of the first rotating shaft 21 is provided with a flat portion 32 that is fixed to a load, and a rotation output is transmitted to the load device. The second rotating shaft 31 is provided with a knurled portion 22 for strengthening the coupling between the two when a gear is press-fitted. The second rotating shaft 31 further includes a cylindrical body portion 33 having a predetermined fitting accuracy with the first hollow portion 23, an oil sump groove 36, and a third length substantially the same as the length of the cylindrical body portion 33. The hollow portion 45, the slit 35 extending over substantially the entire length in the axial direction of the cylindrical body portion 33, and a large diameter portion having a slightly larger outer diameter than the cylindrical body portion 33 at the axial end portion of the cylindrical body portion 33. 34 is formed. The large-diameter portion 34 protrudes from the end of the first rotating shaft 21 and is locked to prevent the first rotating shaft 21 from being detached from the second rotating shaft 31. An annular spring 41 is accommodated in the third hollow portion 45. In the configuration of the rotating shaft shown in FIG. 6, the processing of the second hollow portion 24 shown in FIG. 4 is not necessary, and labor can be saved during the processing. Further, when an abnormal state occurs in the operation as the torque limiter, the large rotation portion 34 is pressed in the direction of the arrow shown in the upper part of FIG. Since 21 can be detached, it has a feature that enables inspection and repair.

  For the sake of convenience, the speed reducer has been described above as an example, but it is apparent that the present invention can also be applied to a speed increasing device and a constant speed device for making the positions of the input rotation shaft and the output rotation shaft different. Further, the present invention can be applied to a power transmission device that uses a bevel gear, a hypoid gear, and the like, and the input rotation shaft and the output rotation shaft are not parallel but have an angle. When applied to the speed increasing device, the torque limiter is used not as an output rotating shaft but as an input rotating shaft, and the power of the motor is input to the torque limiter, and the speed increasing device is placed at the position of the input rotating shaft 11 in FIG. If the output rotation shaft is provided, a preferable result can be obtained practically.

  The input rotation shaft usually indicates the rotation shaft of a motor provided with a pinion. However, even if the power transmission device is a gear that inherits this rotation and does not include the input rotation shaft, the technical idea of the present invention is not limited. Is not different.

  In addition, when the torque limiter according to the present invention is applied to a power transmission device such as a reduction gear, it is clear that the function of the torque limiter is exhibited even if it is used as a rotary shaft at an intermediate stage between input and output. is there.

  Furthermore, it is apparent that the torque limiter according to the present invention is not limited to application to a power transmission device having a gear train, but can be applied to a power transmission device using a belt, for example.

  Furthermore, in the speed reducer described above, the torque limiter is configured by interconnecting the first rotary shaft 21 and the second rotary shaft 31 having substantially the same outer diameter. Needless to say, the second rotating shaft 31 and the second rotating shaft 31 may have different outer diameters.

It is sectional drawing which shows embodiment of the power transmission device of this invention. It is a side view of the 1st rotating shaft in embodiment of the torque limiter in this invention. It is a figure which shows the 2nd rotating shaft in embodiment of the torque limiter in this invention, The figure (A) is a side view which shows a part in cross section, The figure (B) is the 2nd shown in the figure (A). It is the top view which looked at the axis of rotation from the lower part. It is explanatory drawing of the assembly state in embodiment of the torque limiter in this invention. It is a side view which shows one Embodiment of the torque limiter in this invention. It is a side view which shows other embodiment of the torque limiter in this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Input rotating shaft 12 Motor pinion 13 Rotating shaft 14 Spur gear 15 Pinion 16 Output rotating shaft 21 1st rotating shaft 22 Knurled part 23 1st hollow part of 1st rotating shaft 24 2nd of 1st rotating shaft Hollow portion 31 Second rotating shaft 32 Part fixed to load 33 Main body portion of cylindrical body 34 Large diameter portion of cylindrical body 35 Slot 36 groove 41 Annular spring 45 Third hollow portion

Claims (1)

A first rotating shaft provided with a concentric hollow part;
A second rotating shaft having an outer diameter substantially the same as the inner diameter of the hollow portion of the first rotating shaft and having a cylindrical body portion that is slit from the end;
An elastic member housed in the cylindrical body portion of the second rotating shaft and biased so as to expand the inner diameter of the cylindrical body portion;
A torque limiter having a structure in which the cylindrical portion of the second rotating shaft in which the elastic member is accommodated is press-fitted into the hollow portion of the first rotating shaft;
A gear mechanism comprising a plurality of rotary shafts, each of which includes an input rotary shaft and an output rotary shaft, and transmits a rotational force applied to the input rotary shaft to the output rotary shaft via a gear;
A power transmission device in which the torque limiter is mounted as the rotating shaft constituting at least one stage of these gear mechanisms,
An end portion of the cylindrical portion of the second rotating shaft that has been subjected to the slot processing is provided with a large-diameter portion having an outer shape larger than the outer diameter of the rotating shaft, and the second rotating shaft When the cylindrical body portion is press-fitted into the hollow portion of the first rotating shaft, the large-diameter portion of the cylindrical body end portion protrudes from the end portion of the first rotating shaft and is locked. A power transmission device characterized by that.

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