JP4706065B2 - Reduction gear - Google Patents

Description

  The present invention relates to a reduction device that decelerates and outputs motor rotation without using a gear train or the like, for example, to decelerate rotation of a servo motor and drive a robot arm or leg at an appropriate speed and torque. The present invention relates to a reduction gear used.

Most robots require a speed reducer having a high reduction ratio of about 1/50 to 1/300 in order to convert the rotation of a high-speed, low-torque servo motor into an appropriate speed and torque. As a speed reducer for this purpose, a harmonic drive (trade name) or a planetary gear speed reducer is usually used. However, these are composed of special materials and parts that require high-precision processing, and are generally expensive, thus hindering the low cost and widespread use of robots.
As one means for solving this problem, the speed reducer disclosed in Japanese Patent Application Laid-Open No. 2000-65175 uses a metal flat belt to take out the linear motion of a nut obtained by rotating a screw rod with a servo motor. It is converted into rotational motion by a pulley (hereinafter referred to as “prior art”).

JP 2000-65175 A

  Although the speed reducer according to the above prior art is excellent in that a high reduction ratio can be secured while using inexpensive parts, it is necessary to use a long screw rod to increase the rotation angle, and the moment of inertia of the high speed rotating part is large. It will increase. As a result, the decelerating characteristics are deteriorated, so that there is a problem that it is not suitable for a robot that requires rapid acceleration and rapid deceleration. Further, since the end of the metal flat belt is fixed to the flat pulley at the output stage, it can be rotated only a finite number of times, and cannot be used when an infinite number of rotations are required for output.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a reduction gear that can achieve a high reduction ratio at a low cost and has no restriction on the number of rotations of the output shaft.

In order to achieve the above object, a speed reducer according to the present invention is a speed reducer that decelerates and outputs the rotation of a motor, and a timing belt is stretched between a plurality of timing pulleys including a timing pulley connected to an output shaft. A rack having teeth having a pitch different from the pitch of the timing belt teeth is fixedly provided at a position meshing with the teeth of the belt, and a plurality of eccentric cams are provided at positions facing the rack across the timing belt. Is connected to a motor.
Further, the speed reducer of the present invention is a speed reducer that decelerates and outputs the rotation of the motor, spans a timing belt between a plurality of timing pulleys including a timing pulley connected to an output shaft, An internal gear having teeth with a pitch different from the timing belt teeth is fixedly provided at the meshing position, an eccentric cam is provided at a position facing the internal gear across the timing belt, and the eccentric cam is connected to the motor. It is characterized by.
The speed reducer according to the present invention is a speed reducer that decelerates and outputs the rotation of the motor, and the timing belt 1 is stretched between the eccentric cam connected to the motor and the flat pulley with the tooth surface facing outside, and the timing is reduced. An internal gear is fixedly provided at a position facing the eccentric cam across the belt, and the slider is fixed to the timing belt.

The present invention has the following excellent effects.
(1) The present invention does not need to be configured with special materials such as harmonic drive (trade name) or planetary gear reducer and parts that require high-precision machining, so that the reduction can achieve a high reduction ratio at low cost. You can sell the device. Further, for example, by adopting the speed reducer according to the present invention as a speed reducer for a robot, it is possible to reduce the price and spread of the robot.
(2) Further, according to the present invention, it is possible to obtain a speed reduction device that can achieve a high speed reduction ratio at a low cost without any restriction on the number of rotations of the output shaft.

  The best mode of the speed reducer according to the present invention will be described below with reference to the drawings based on the embodiments.

FIG. 1 is a perspective view schematically illustrating an entire embodiment 1 according to the speed reducer of the present invention.
The timing belt 1 is formed of a toothed belt having teeth 25 formed on the inner surface thereof, and is passed between the timing pulleys 2 and 3 and the teeth 26 and 26 on the peripheral surface of the timing pulleys 2 and 3. It is driven while meshing. The timing belt 1 is made of rubber, urethane or the like.
A plurality of eccentric cams 4, 5, so as to be close to the outer surface of the linear portion of the timing belt 1 and to have a rotation axis in a direction parallel to the outer surface of the timing belt 1 and perpendicular to the moving direction thereof. 6, 7, and 8 are provided. Further, a rack 9 fixed to the apparatus is provided at a position close to the inside of the straight portion of the timing belt 1 and facing the eccentric cams 4, 5, 6, 7, and 8 with the timing belt 1 interposed therebetween. . The plurality of eccentric cams 4, 5, 6, 7, and 8 are configured in such a manner that the protrusions thereof are sequentially shifted by 90 degrees counterclockwise with respect to the eccentric cam 4. For this reason, when the plurality of eccentric cams 4, 5, 6, 7, and 8 are rotated, the outer surface of the timing belt 1 is sequentially pressed toward the rack 9, and the teeth 25 of the timing belt 1 and the teeth 27 of the rack 9 are brought together. It is set so that it may mesh sequentially.

  A servo motor 10 has an output shaft connected to a rotating shaft of the eccentric cam 4 to drive the eccentric cam 4 to rotate. The eccentric cam 4 and the other eccentric cams 5, 6, 7, 8 are connected by a crank rod 11, and the rotational driving force of the eccentric cam 4 is transmitted to the other eccentric cams 5, 6, 7, 8.

  Now, when the servo motor 10 rotates the eccentric cam 4, the rotation is transmitted to the other eccentric cams 5, 6, 7, 8 via the crank rod 11. As the five eccentric cams 4, 5, 6, 7, and 8 rotate, the timing belt 1 is pressed against the rack 9 fixed to the apparatus in order from the end. Since the teeth 27 of the rack 9 and the teeth 25 of the timing belt 1 have different tooth pitches (interval between adjacent teeth), that is, the number of teeth in a unit distance, the timing belt 1 advances by a different number of teeth per one rotation of the eccentric cam 4. . The movement of the timing belt 1 is transmitted to the timing pulley 2 and rotates the arm 13 via the turning shaft 12.

2 (1) to 2 (5) show the positional relationship among the timing belt 1, the eccentric cams 4 to 8 and the rack 9 which are the core of the speed reducer shown in FIG.
First, the basic configuration will be described with reference to FIG.
Since the eccentric cams 4 to 8 are coupled by the crank rod 11 shown in FIG. 1, they rotate in the same direction at the same speed. Here, the eccentric cams 4 to 8 are rotated clockwise as indicated by arrows. The eccentric positions of the five eccentric cams 4-8 are such that the timing belt 1 is pressed against the rack 9 in order, as shown in FIG. The projecting portions are sequentially offset 90 degrees counterclockwise.
As a result, in the state of FIG. 2 (1), the timing belt 1 is pressed against the rack 9 by the eccentric cam 4 and the eccentric cam 8.

Here, the tooth pitch of the teeth 27 of the rack 9 does not coincide with the tooth pitch of the teeth 25 of the timing belt 1, and in the example of this figure, the number of teeth of the rack 9 is 24, whereas the rack 9 The number of teeth of the timing belt 1 provided in the same length as 25 is 25. For this reason, the rack 9 and the timing belt 1 cannot be engaged with each other over the entire length. 2 (1), the eccentric cams 4 and 8, the state (2), the eccentric cam 5, the state (3), the eccentric cam 6, and the state (4). In the state (5), the eccentric cams 4 and 8 are obtained again.
When reaching from (1) to (5), the timing belt 1 may be in a state of being shifted from the rack 9 by just one tooth pitch (the tooth pitch means an interval between adjacent teeth). It can be seen by the mark 14 attached to the timing belt 1.
As described above, when the eccentric cam 4 makes one rotation, the timing belt 1 moves so as to be shifted by one tooth pitch of the teeth 27 of the rack 9. This motion is converted into a rotational motion by the timing pulley 2 of FIG. 1 and rotates the arm 13 via the shaft 12.
For example, if the number of teeth of the timing pulley 2 is 100, when the eccentric cam 4 rotates 100 times, the timing pulley 2 rotates once and a 1/100 speed reduction is realized.
In order to reduce the shearing force generated between the eccentric cams 4 to 8 and the timing belt 1, it is desirable to provide friction reducing means such as attaching a thin bearing (not shown) to the outer periphery of the eccentric cams 4 to 8.

In FIG. 2, the number of teeth of the rack 9 is 24 as an example, but the setting of the number of teeth and the pitch of the general rack 9 will be described below. First, the tooth pitch (interval between adjacent teeth) of the timing belt 1 is set to p (unit mm), and the rack length L (unit mm) can be expressed by the following equation.
L = Np
Here, N is an appropriate integer and is determined according to the desired rack length. On the other hand, the number of teeth of the rack is set to N-1 or N + 1. The rack tooth pitch p ′ (unit: mm) is expressed by the following equation.
p '= L / (N-1) or p' = L / (N + 1)
Further, the reduction ratio (the rotational speed of the rotating shaft 12 / the rotational speed of the servo motor 1) of the speed reducer of the first embodiment is 1 / M, where M is the number of teeth of the timing pulley 2.

  In the first embodiment, transmission means using a gear or another timing belt may be provided between the servo motor 10 and the eccentric cam 4 so as to reduce the first stage or change the arrangement of the servo motor 10. Further, the number of eccentric cams is not limited to five, and may be an arbitrary number of three or more. In this case, the amount of rotation angle deviation between adjacent eccentric cams may be set to 360 ° / (C−1), where C is the number of eccentric cams. Further, the power transmission means of adjacent eccentric cams is not limited to the crank rod 11, and any known method such as another timing belt or gear may be used. Further, in order to increase the rigidity of the output shaft, a metal toothed belt may be used instead of the timing belt 1. In this case, the rigidity may be improved by fixing a metal belt to the timing pulley 2 as shown in the above-mentioned Patent Document 1. However, infinite rotation is impossible.

Next, a second embodiment of the present invention will be described with reference to FIG.
The same reference numerals as those in FIG. 1 denote the same parts unless otherwise specified.
The timing belt 1 having teeth 25 on the inner surface is stretched by three timing pulleys 2, 15, and 16 and is alternately pressed against the internal gear 19 by eccentric cams 17 and 18 that are 180 degrees out of phase. ing. When the eccentric cams 17 and 18 directly connected to the servo motor 10 are rotated by the servo motor 10, the upper half and the lower half of the timing belt 1 are alternately pressed against the internal gear 19. Since the number of teeth on the inner surface of the timing belt 1 along the outer circumference of the two eccentric cams 17 and 18 and the number of teeth of the internal gear 19 are different by one, the timing belt 1 is rotated by the internal gear for half rotation of the eccentric cams 17 and 18. The 19 teeth 28 are advanced by one tooth pitch. The motion of the timing belt 1 is converted into a rotational motion by the timing pulley 2 and rotates the arm 13 via the shaft 12.

4 (1) to 4 (3) show the positional relationship among the timing belt 1, the eccentric cams 17 and 18, the internal gear 19 and the timing pulleys 15 and 16 that form the core of the speed reducer in FIG. Is.
First, the basic configuration will be described with reference to FIG.
The timing belt 1 is deformed between the timing pulleys 15 and 16 along the inside of the internal gear 19 by eccentric cams 17 and 18. Here, in order to simplify the drawing, the timing belt 1, the eccentric cams 17 and 18, and the timing pulleys 15 and 16 are indicated by a one-dot chain line.
In this example, the number of teeth of the internal gear 19 is 26, whereas the number of teeth of the timing belt 1 entering the inside of the internal gear 19 is 25 and only one is designed. In the state of FIG. 4 (1), the timing belt 1 is pressed against the entrance of the internal gear 19 by the eccentric cams 17 and 18 and meshes.
FIG. 4B shows a state in which the eccentric cams 17 and 18 are rotated 90 degrees clockwise by the servo motor 10. In this state, the timing belt 1 is pressed and engaged with the inner gear 19.
In FIG. 4 (3), the eccentric cams 17 and 18 further rotate 90 degrees clockwise, and the meshing position returns to the same position as in FIG. 4 (1). In this process, the timing belt 1 is fed by one tooth pitch in the direction of the white arrow due to the difference in the number of teeth between the timing belt 1 and the internal gear 19 by the mark 20 shown on the timing belt teeth in the figure. .

As described above, the motion of the timing belt 1 is converted into the rotational motion by the timing pulley 2. Here, if the number of teeth of the timing pulley 2 is 100, when the eccentric cam rotates 50 times, the timing pulley 2 rotates once, and 1/50 deceleration is realized.
In order to reduce the shearing force generated between the eccentric cams 17 and 18 and the timing belt 1, it is desirable to provide friction reducing means such as attaching a thin bearing to the outer periphery of the eccentric cams 17 and 18.

  In the second embodiment, transmission means using gears or other timing belts may be provided between the servo motor 10 and the eccentric cams 17 and 18 to reduce the first stage or change the arrangement of the servo motors. . Further, the shape of the eccentric cam is not limited to the eccentric cam, and any shape may be used as long as the timing belt is appropriately deformed. In order to increase the rigidity of the output shaft, a metal toothed belt may be used instead of the timing belt. In this case, as shown in Patent Document 1, the metal belt may be fixed to the timing pulley 2 to improve the rigidity. However, infinite rotation is impossible.

Next, Embodiment 3 of the present invention will be described with reference to FIG.
The same reference numerals as those in FIG. 3 denote the same parts unless otherwise specified.
In this example, the same mechanism as in the second embodiment is used, but the point that the output is taken out as a linear motion is different. The timing belt 1 is stretched between the eccentric cams 17, 18 and the flat pulley 21 with the tooth surface facing outside. The slider 22 is fixed to the timing belt 1 and slides on the guide rail 23. As described in the second embodiment, the servomotor 10, the eccentric cams 17 and 18, and the internal gear 19 displace the timing belt 1 per two rotations of the tooth 28 of the internal gear 19 per one rotation of the servomotor 10. Can be taken out as a linear motion decelerated by the slider 22.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view schematically illustrating the entirety of a first embodiment relating to a reduction gear device of the present invention. FIG. 2 is an explanatory diagram illustrating the positional relationship among a timing belt, an eccentric cam, and a rack that form the core in the speed reduction device of FIG. 1 in order with time. It is a perspective view which roughly illustrates the whole Example 2 concerning a reduction gear of the present invention. FIG. 4 is an explanatory diagram showing the positional relationship among a timing belt, an eccentric cam, an internal gear, and a timing pulley that form the core of the reduction gear in FIG. It is a perspective view which roughly illustrates the whole Example 3 which concerns on the reduction gear apparatus of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Timing belt 2, 3 Timing pulley 4-8 Eccentric cam 9 Rack 10 Servo motor 11 Crank rod 12 Shaft 13 Arm 15, 16 Timing pulley 17, 18 Eccentric cam 19 Internal gear 21 Flat pulley 22 Slider 23 Guide rail 25-28 tooth

Claims (3)

  In a reduction gear that decelerates and outputs motor rotation, a timing belt is stretched between a plurality of timing pulleys including a timing pulley connected to an output shaft, and the teeth of the timing belt are engaged with the teeth of the timing belt. A rack having teeth with a tooth pitch different from the pitch is fixedly provided, a plurality of eccentric cams are provided at positions facing the rack across the timing belt, and the plurality of eccentric cams are connected to a motor. To reduce the speed.   In a reduction gear that decelerates and outputs motor rotation, a timing belt is stretched between a plurality of timing pulleys including a timing pulley connected to an output shaft, and the teeth of the timing belt are engaged with the teeth of the timing belt. An internal gear having teeth with a tooth pitch different from the pitch is fixedly provided, an eccentric cam is provided at a position facing the internal gear across the timing belt, and the eccentric cam is connected to a motor. To reduce the speed. In a reduction gear that decelerates and outputs the rotation of a motor, the timing belt 1 is stretched between the eccentric cam connected to the motor and the flat pulley with the tooth surface facing outside, and is opposed to the eccentric cam with the timing belt interposed therebetween. A speed reducer comprising a fixedly provided internal gear having teeth having a tooth pitch different from the tooth pitch of the timing belt, and a slider fixed to the timing belt.

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