JPH11280871A - Backlash removing mechanism in gear train - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a backlash removing mechanism which can transmit not only a light rotation torque but the rotation torque with some degree. SOLUTION: Plural grooves having a slant surface in the circumference direction are provided on the equally divided circumferential angle position on the joining surface 12a of one side gear 12 out of a gears 12, 14 having mutually joining surface and the same number of projections are provided in the position corresponding to the grooves on the joining surface 14a of the other gear 14 and steel balls are interposed between the projections and the slant surface of the groove and both gears 12, 14 are tightened through a coned disc spring 16, thereby, enlarges the transmitted rotation torque.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention generally relates to a gear train, and more particularly, to a backlash removing mechanism in a gear train used for a control device such as a servo actuator. 2. Description of the Related Art In a servo actuator, a gear reducer is often used to adjust a motor output and an actuator output. However, in the combination of the gears, a gap is always required for the meshing of the gears, and this gap causes a backlash, which causes an error in control accuracy or a play in output. Although there is a mechanism such as combining two gears to eliminate backlash, there are restrictions due to the shape and load.

[0002]

2. Description of the Related Art FIG. 4 is an exploded perspective view for explaining a conventional backlash removing mechanism between gears. Referring to FIG.
In order to eliminate backlash between the gear 1 and the gear 2, the gear 2 and the gear 4 attached to the common shaft 3 with the gear 2 are provided with mating surfaces 2a, 4a, respectively. A groove 2b for accommodating the coil spring 5 and a hole 2c for inserting the bent end 5a of the coil spring 5 are provided, while a mating surface 4a is provided with a hole 4b for inserting another bent end 5b of the coil spring 5. When the gear 2 and the gear 4 are assembled with the coil spring 5 interposed therebetween and the gear 2 is meshed with the gear 1, the gear 2 is meshed with the gear 1 by shifting the tooth pitch of the gear 2 and the gear 4 by one or more pitches. This provides a preload to eliminate backlash.

[0003]

As shown in FIG. 4, since the space for mounting the coil spring 5 is limited, the spring load cannot be increased, and the torque transmitted by the gear is limited. For example, it can only be used for transmitting rotation with a light torque, such as a rotation amount position detection sensor. Therefore, it is an object of the present invention to provide a backlash removing mechanism capable of transmitting a certain amount of rotational torque as well as transmitting light rotational torque.

[0004]

According to the present invention, a plurality of grooves having circumferentially inclined surfaces are provided on the mating surfaces of a pair of gears having mating surfaces at equal circumferential angles. In a gear train in which a steel ball is interposed between the mating surface of the gear and the inclined surface of the groove so that the two gears are tightened via a disc spring, thereby making it possible to increase the rotational torque transmitted. A backlash removing mechanism is provided. To explain the operation, the load given by the disc spring by tightening the nut engaging with the end screw of the common shaft of both gears, the preload of the rotating torque to the gear through the steel ball and the inclined surface of the groove. This preload gives a much larger value than the conventional spring system.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a side view showing an embodiment of backlash removal in a gear train according to the present invention, FIG. 2 (A) is a front view of a gear 12 of FIG. 1, and FIG. A
FIG. 2 (B) is an enlarged view of a part, and FIG.
2 (D) is an explanatory diagram of the load in FIG. 2 (B). FIGS. 3A and 3B are a side view and a front view of the gear 14 of FIG. 1, respectively. The backlash removing mechanism in the gear train according to the present invention is shown in FIG.
As shown in FIG. 3, a groove 12b having a plurality of circumferentially inclined surfaces 12c at equally circumferential angles on a mating surface 12a of one of the pair of gears 12 and 14 having mating surfaces as shown in FIG. Is provided on the mating surface 14a of the other gear 14 at a position corresponding to the groove 12b, and a steel ball 15 is interposed between the protrusion 14b and the inclined surface 12c of the groove 12b. The two gears 12 and 14 are configured to be tightened via the disc spring 16, thereby making it possible to increase the transmitted rotational torque.

Next, the backlash removing mechanism in the gear train according to the present invention will be described in detail. FIG. 2 (A),
Referring to (B), a plurality of (three in this example) arc-shaped grooves 12b having an inclined surface 12c are provided at equal circumferential angles on the mating surface 12a of the gear 12, and Steel balls 15 slightly smaller and slightly larger in diameter than the groove depth are inserted into each groove 12b, and although not shown, the grooves are filled with grease or the like to prevent wear of the steel balls. On the other hand, FIG.
As shown in FIG. 3 (B), the shaft-like projection 1 is provided on the mating surface 14a of the gear 14 at a position corresponding to the groove 12b of the gear 12.
4b is fixed by driving or press fitting. When these gears 12, 14 are fitted to the shaft 13 as shown in FIG. 1 with the mating surfaces 12a, 14a together, FIG.
As shown in FIG. 2C showing an XX cross section of FIG. 2B, the steel ball 15 has an inclined surface 12 c of a groove 12 b of the gear 12,
It comes into contact with the projection 14 b of the gear 14.
As shown in FIG. 1, a disc spring 16, a flat washer 17, and a nut 18 are sequentially attached to the end threaded portion 13a of the shaft 13.

Next, the operation will be described. As shown in FIG. 1, the gear 12 shown in FIG.
After the teeth of the two gears 12 and 1 are brought into contact with each other, the nut 18 is tightened, and as shown in FIG.
There receives a reaction force L ₂ from L ₁ and the inclined surface 12c of the groove bottom,
L = L ₁ + (vertical component force L ₃ of L _2), and the reaction force of the horizontal component L ₄ of L ₂ becomes a rotational torque in the circumferential direction, serves the preload serves to remove the backlash. This preload is much larger than the preload obtained by the conventional method. However, the disc spring 16 keeps the tightening force constant, and when the load of the gear 1 exceeds a certain value, backlash is generated to prevent the steel ball 15 from being damaged.

[0008]

As described above, by using a disc spring in place of the conventional coil spring, it is possible to generate a high load without backlash without taking a small space and taking up a considerable amount of space. Transmission of rotational torque is possible.

[Brief description of the drawings]

FIG. 1 is a side view showing an embodiment of a backlash removing mechanism in a gear train according to the present invention.

2 (A) is a front view of the gear of FIG. 1, and FIG. 2 (B)
3A is an enlarged view of a portion A in FIG. 3A, FIG. 3C is a cross-sectional view taken along line XX of FIG. 3B, and FIG. 3D is an explanatory view of the load in FIG.

3 (A) is a side view of the gear of FIG. 1, and FIG. 2 (B)
2 is a front view of FIG.

FIG. 4 is an exploded perspective view illustrating a conventional backlash removing mechanism between gears.

[Explanation of symbols]

 12, 14 gears 12a, 14a: mating surface 12b: groove 12c: inclined surface 13: shaft 14b: projection 15: steel ball 16: disc spring

Claims (1)

[Claims] 1. A pair of gears having a mating surface provided with a plurality of circumferentially inclined grooves at equal circumferential angles at a mating surface of one of the gears, and a mating surface of the other gear. The same number of protrusions are provided at positions corresponding to the grooves, steel balls are interposed between the protrusions and the inclined surfaces of the grooves, and the two gears are tightened via disc springs. Backlash removal mechanism in a gear train that allows for a large rotating torque to occur.