Non-backlash gear and assembling method thereof

Abstract

To provide a non-backlash gear which eliminates a conventional problem caused by a constitution which indispensably needs bolts for fastening two pieces of gears by reducing a size of a phase-aligning jig, and arbitrarily constituting the bolts for fastening the two pieces of gears, and an assembling method thereof.SOLUTION: A non-backlash gear comprises an elastic body 4 for connecting two pieces of gears 2, 3, and energizing the gear 3 to the gear 2 in a circumferential direction, and a phase-aligning mechanism 5 for holding a state that phases of teeth 2a, 3a coincide with each other by relatively rotating the two piece of gears 2, 3. The phase-aligning mechanism 5 comprises a telescopic interval holding jig 11 which can hold the state by a prescribed length, and long holes 15, 16 which are formed at the two pieces of gears 2, 3 so as to be capable of fitting the interval holding jig 11 therein. The phases of the two pieces of teeth 2a, 3a coincide with each other by elongating and contracting the interval holding jig 11 in the long holes 15, 16 against an elastic force of the elastic body 4.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a non-backlash gear that makes it possible to suppress backlash that occurs in drive transmission by gears, and to an assembly method thereof. [Background technology]

[0002] As shown in FIG. 3, an example of such a non-backlash gear is known that includes two gears (32) and (33) having the same diameter and the same number of teeth (32a) and (33a), a plurality of tension coil springs (34) (six in the figure) that serve as elastic bodies that connect the two gears (32) and (33) and urge the gear (33) in the circumferential direction relative to the other gear (32), and a jig (35) and a bolt (36) that serve as a phase holding mechanism that rotates the two gears (32) and (33) relative to each other to hold the phases of the teeth (32a) and (33a) in agreement.

[0003] According to this non-backlash gear (31), a counterclockwise elastic force acts on one gear (32) and a clockwise elastic force acts on the other gear (33) by the tension coil spring (34), so that the phase of the two gears (32) and (33) is shifted. With this phase shift eliminated by the jig (35) and the bolt (36), the two gears (32) and (33) are positioned to mesh with the mating gear (41). After that, by removing the jig (35) and the bolt (36), the teeth (32a) and (33a) of the two gears (32) and (33) pinch the teeth (41a) of the mating gear (41) via the elastic force, so that there is no backlash. Generally, as shown in the figure, two gears (32) and (33) have a large diameter, and a mating gear (41) has a small diameter.

[0004] Although the two gears (32), (33) are in phase with each other in FIG. 3, they are out of phase with each other before they are meshed. When assembling such a non-backlash gear (31), it is necessary to assemble the two gears (32), (33) and the mating gear (41) in a state in which the phases of the two gears (32), (33) are aligned with high precision.

[0005] The non-backlash gear (31) shown in FIG. 3 uses a phase holding mechanism consisting of a jig (35) and bolts (36). First, the two gears (32) and (33) are clamped by the jig (35) and the two gears (32) and (33) are rotated relative to each other in a direction to align the phase against the elastic force of the elastic body (34) to perform rough positioning. Furthermore, special bolts (36) with multiple tapered tips are screwed into multiple holes provided in the two gears (32) and (33), respectively, to perform high-precision positioning and fixation.

[0006] Furthermore, Patent Document 1 discloses a phase holding mechanism in which a first screw hole is provided in one gear and a second screw hole and an inclined surface are provided in the other gear, and when a bolt is screwed into both gears, the bolt rubs against the inclined surface while being screwed in, thereby changing the phase. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2020-46052 A DISCLOSURE OF THEINVENTION [Problem to be solved by the invention]

[0008] In assembling the conventional non-backlash gear described above, a jig (35) for clamping the two gears (32) and (33) is used, but this has the problem that the jig (35) becomes large in size in order to accommodate the two large-diameter gears (32) and (33). Also, a bolt for fastening the two gears together is an essential component, and this bolt is a special-purpose item with a special shape.

[0009] In addition, the gear in Patent Document 1 needs to have a certain tooth width to provide an inclined surface in addition to a screw hole in the other gear, which makes it difficult to apply to gears with a narrow tooth width, and the bolt that fastens the two gears is an essential component, and the phase is changed by rubbing the bolt along the inclined surface, so if the elastic force of the spring is increased, the contact pressure between the inclined surface and the bolt becomes large, which causes early wear of the material. Another problem is that a lateral force acts on the spring when the bolt is screwed in, which places restrictions on the design of the spring.

[0010] An object of the present invention is to provide a non-backlash gear and an assembly method thereof which eliminates the conventional problems caused by the necessity of using bolts to fasten two gears together, by making the jig used for phase alignment smaller and allowing the bolts fastening the two gears to have any configuration. [Means for solving the problem]

[0011] The non-backlash gear of this invention is a non-backlash gear in which the teeth of two gears having the same diameter and number of teeth are sandwiched between the teeth of a mating gear via elastic force, eliminating backlash, and comprises an elastic body that connects the two gears and urges one gear in the circumferential direction relative to the other gear, and a phase holding mechanism that rotates the two gears relative to each other to keep the tooth phases aligned, the phase holding mechanism comprising a spacing holding jig that is expandable and contractible and can hold a state at a predetermined length, and elongated holes provided in each of the two gears so that the spacing holding jig can be fitted into them, and the phases can be aligned by expanding and contracting the spacing holding jig within the elongated holes against the elastic force of the elastic body.

[0012] When assembling such a non-backlash gear, the teeth of the two gears are out of phase with each other due to the elastic force of the elastic body, and the spacing jig fitted into the slot is extended or contracted to a predetermined length against the elastic force of the elastic body. This allows the teeth of the two gears to be aligned in phase with each other while the spacing jig prevents the two gears from rotating relative to each other. Then, after the two gears and the mating gear are meshed with each other in this phase-aligned state, the spacing jig is removed, and a non-backlash gear with no backlash is obtained.

[0013] As the spacing jig, various types of jig can be used that are supported by tension between the end face of the long hole of one gear and the end face of the long hole of the other gear using screws, springs, fluid pressure, motors, etc.

[0014] According to the non-backlash gear of the present invention, the spacing jig is sized to be fitted into the elongated hole, so that the jig used for phase alignment can be made compact.

[0015] Furthermore, because the spacing jig is capable of maintaining a state at a specified length, the phase of the teeth of the two gears is maintained in a matched state, so there is no need to fasten the two gears with a bolt. The bolts fastening the two gears together can be of any configuration, which eliminates the conventional problems that arise from the necessity of using bolts fastening the two gears.

[0016] The spacing jig is a screw-type jig consisting of a bolt member and a nut member screwed onto it, and it is preferable that when the biasing force of the elastic body acts on the two gears, the long hole communicates between the two gears and the screw-type spacing jig can be fitted into it.

[0017] In this way, the spacing jig can be expanded or contracted by rotating the nut member while the bolt member is fixed, making assembly easy. Also, versatile bolts and nuts can be used as the bolt members and nut members, making assembly inexpensive.

[0018] It is preferable that the elongated holes have the same shape in the two gears, and when the positions of the elongated holes match between the two gears, the phases of the teeth of the two gears match.

[0019] In this way, the elongated hole also serves as a positioning member when the spacing jig is extended or contracted, making it possible to simplify the non-backlash gear.

[0020] It is preferable that in the phase holding mechanism, the two gears can be fastened together with a bolt while the phases of the teeth of the two gears are in agreement.

[0021] When assembling non-backlash gears, the two gears are prevented from rotating relative to each other by a spacing jig, so it is not necessary to fasten the two gears with bolts, but fastening the two gears with bolts more reliably prevents the two gears from rotating relative to each other, making assembly work safer. Fastening with bolts allows the use of versatile bolts rather than special bolts, because the two gears are prevented from rotating relative to each other by a spacing jig, and does not cause the problems associated with the use of conventional special bolts.

[0022] If fastening is not performed with bolts, the spacing jig will be removed after the two gears and the mating gear are meshed. However, if fastening is performed with bolts, the spacing jig can be removed before meshing the two gears and the mating gear, and the bolts can be removed after meshing the two gears and the mating gear.

[0023] The method of assembling non-backlash gears according to this invention is a method of assembling non-backlash gears in which the teeth of two gears having the same diameter and number of teeth are sandwiched between the teeth of a mating gear via elastic force, eliminating backlash, and is characterized in that a spacing retaining jig that is expandable and can be maintained at a predetermined length is fitted into an elongated hole provided in each of the two gears, the spacing retaining jig is expanded and contracted within the elongated hole against the elastic force to align the phases of the teeth of the two gears, and the two gears are positioned to mesh with the mating gear while maintaining the length of the spacing retaining jig.

[0024] According to this method of assembling a non-backlash gear, when the phases of the teeth of the two gears are shifted due to the elastic force of the elastic body, the spacing jig fitted into the elongated hole is expanded or contracted to a predetermined length against the elastic force of the elastic body, thereby making it possible to align the phases of the teeth of the two gears while preventing the two gears from rotating relative to each other due to the spacing jig. Then, when the phases are aligned, the two gears are meshed with the mating gear, and the spacing jig is removed, thereby obtaining a non-backlash gear with no backlash.

[0025] According to the method for assembling a non-backlash gear of the present invention, the jig for phase alignment can be made compact because the spacing jig is sized to be fitted into the elongated hole.

[0026] It is preferable that the two gears are fastened together with bolts while maintaining the length of the spacing jig, and then the two gears are positioned to mesh with the mating gear.

[0027] Since the spacing jig prevents the two gears from rotating relative to each other, it is not necessary to fasten the two gears with bolts. However, using bolts to fasten the two gears more reliably prevents the two gears from rotating relative to each other, making the assembly work safer. Fastening with bolts allows the use of versatile bolts rather than special bolts, since the spacing jig prevents the two gears from rotating relative to each other, and does not cause problems associated with the use of conventional special bolts. When fastening with bolts, when arranging the two gears in a position to mesh with the mating gear, the spacing jig may be removed before meshing the two gears with the mating gear, and the bolts may be removed after meshing the two gears with the mating gear. Effect of the Invention

[0028] According to the non-backlash gear and its assembly method of the present invention, the configuration for aligning the phases of two gears makes it possible to align the phases of the two gears by expanding and contracting a spacing jig fitted into a long hole to a predetermined length. This makes it possible to reduce the size of the jig used for phase alignment and also allows the bolts fastening the two gears to be of any configuration, thereby eliminating the problems that arise in the past when the bolts fastening the two gears are a necessary configuration. [Brief description of the drawings]

[0029] [Figure 1] FIG. 1 is a perspective view showing an embodiment of a non-backlash gear according to the present invention. [Diagram 2] Figure 2 is a cross-sectional view showing the spacing retention jig of the phase retention mechanism. (a) shows the state in which the phase of the teeth of the two gears is shifted due to the elastic force of the elastic body, and (b) shows the state in which the phase of the teeth of the two gears is aligned by extending the spacing retention jig. [Diagram 3] FIG. 3 is a perspective view showing an example of a conventional non-backlash gear. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0030] Hereinafter, one embodiment of the present invention will be described with reference to FIGS.

[0031] As shown in FIG. 1, the non-backlash gear (1) of the present invention includes two gears (2) and (3) having the same diameter and the same number of teeth (2a) and (3a), a plurality of tension coil springs (4) (six in the figure) serving as elastic bodies that connect the two gears (2) and (3) and urge the other gear (3) in the circumferential direction relative to the gear (2), and a phase holding mechanism (5) that rotates the two gears (2) and (3) relative to each other to hold the phases of the teeth (2a) and (3a) in agreement.

[0032] The tension coil spring (4) is the same as that shown in FIG. 3. It is fitted into the spring elongated holes (6) formed in each of the gears (2) and (3). One end (4a) of the tension coil spring (4) is attached to one of the gears (2) and the other end (4b) is attached to the other gear (3). By doing so, a counterclockwise elastic force acts on one of the gears (2) and a clockwise elastic force acts on the other gear (3).

[0033] The phase holding mechanism (5) includes a spacing holding jig (11) that is extendable and can hold a predetermined length, and a fixing bolt (12) that fastens the two gears (2) and (3) together.

[0034] A total of three spacing retaining jigs (11) are provided on the radially inner side of the tension coil spring (4), one at a time.

[0035] The spacing jig 11 is of a screw type, which comprises a bolt member 13 having a head 13a and a shaft 13b, and a nut member 14 screwed onto the end of the shaft 13b opposite the head of the bolt member 13. In this embodiment, the bolt member 13 and the nut member 14 are both highly versatile.

[0036] The two gears (2) and (3) are each provided with identical rectangular long holes (15) and (16) that communicate between the two gears, and a spacing jig (11) can be fitted across these long holes (15) and (16).

[0037] The elastic force of the tension coil spring (4) acts to shift the phases of the teeth (2a) and (3a) of the two gears (2) and (3). Although not shown, when the phase holding mechanism (5) is removed, the teeth (2a) and (3a) of the two gears (2) and (3) are out of phase. FIG. 1 shows a state in which the two gears (2) and (3) are rotated relative to each other by the phase holding mechanism (5) to eliminate this phase shift. As shown in the figure, the two gears (2) and (3) are meshed with the mating gear (41), and then the spacing jig (11) and the fixing bolt (12) constituting the phase holding mechanism (5) are removed from the two gears (2) and (3), thereby obtaining a non-backlash gear (1) without backlash in which the teeth (2a) and (3a) of the two gears (2) and (3) sandwich the teeth (41a) of the mating gear (41) through elastic force.

[0038] The spacing jig (11) can be expanded or contracted between a contracted state shown in (a) and an expanded state shown in (b) by fixing the bolt (13) and rotating the nut (14), as shown enlarged in Fig. 2. The expanded state shown in (b) corresponds to the state in which the teeth (2a) and (3a) of the two gears (2) and (3) shown in Fig. 1 are in phase with each other, and the contracted state shown in (a) corresponds to the state in which the teeth (2a) and (3a) of the two gears (2) and (3) are out of phase with each other due to the elastic force of the tension coil spring (4).

[0039] In the contracted state shown in (a), the spacing jig (11) is sandwiched between the clockwise end face (15a) of the long hole (15) of one gear (2) and the counterclockwise end face (16b) of the long hole (16) of the other gear (3). In this state, there is a gap (G) between the clockwise end face (end face of the nut (14)) of the spacing jig (11) and the clockwise end face (16a) of the long hole (16) of the other gear (3), and there is also a gap (G) between the counterclockwise end face (end face of the head (13a) of the bolt (13)) of the spacing jig (11) and the counterclockwise end face (15b) of the long hole (15) of the one gear (2).

[0040] When the spacing jig (11) is extended as shown in (b), the gap (G) that exists in the contracted state as shown in (a) disappears, and the positions of the long holes (15) and (16) are aligned between the two gears (2) and (3).

[0041] After the spacing jig 11 is in the extended state shown in Fig. 2(b), the fixing bolt 12 is inserted into a through hole provided in one gear 2 and screwed into a female screw provided in the other gear 3. The fixing bolt 12 preferably has a ground shaft on the base side.

[0042] When assembling the non-backlash gear (1), the two gears (2) and (3) are prevented from rotating relative to each other by the spacing jig (11), so it is not essential to fasten the two gears (2) and (3) with the fixing bolts (12). However, the biasing force of the elastic body (4) and the biasing force of the spacing jig (11) opposing it both act in the circumferential direction. In addition to this force, by fixing the two gears (2) and (3) to each other with the axial force of the fixing bolts (12), the two gears (2) and (3) are reliably prevented from rotating relative to each other, so that the assembly work can be performed safer.

[0043] When the fixing bolt (12) is fastened, the two gears (2) and (3) are prevented from rotating relative to each other by the spacing jig (11), so only axial forces act on the two gears (2) and (3) and the fixing bolt (12), and no forces perpendicular to the axial direction act on them. Therefore, a versatile bolt can be used instead of a special bolt, and problems associated with the use of conventional special bolts do not occur. Furthermore, when the fixing bolt (12) is screwed into both gears (2) and (3), there is no need to change the phase by screwing it while rubbing it along an inclined surface provided on one of the gears, so there is no problem of early wear due to friction between the two gears (2) and (3) and the fixing bolt (12). In this way, the conventional problems caused by the necessity of a bolt to fasten the two gears are solved.

[0044] In the above embodiment, the elastic body is a plurality of tension coil springs (4), but the elastic body (4) is not limited to tension coil springs and may be a plurality of compression coil springs, or may be a single C-shaped spring.

[0045] In addition, the spacing jig (11) that is extendable and can be fixed to a predetermined length is a screw type (screw type jack), but as the spacing jig (11), various devices that utilize springs, fluid pressure, motors, etc. other than screws (such as what are called jacks, cylinders, tension rods, etc.) can be used. Also, when using a screw type, versatile bolts and nuts may be modified as appropriate rather than being used as is. By using versatile bolts and nuts as the spacing jig (11) and fixing bolts (12), the phase holding mechanism (5) can be made simpler and less expensive.

[0046] Also, a material that is easily deformed and has a large coefficient of friction, such as rubber, may be attached to both ends of the spacing jig (11) to increase the contact area between the spacing jig (11) and the end faces (15a), (15b), (16a), (16b) of the slots (15), (16) of the gears (2), (3), thereby absorbing variations in processing precision through elastic deformation of the rubber and increasing the frictional resistance between the spacing jig (11) and the two gears (2), (3), making it less likely that the spacing jig (11) attached to the two gears (2), (3) will fall off during assembly. This can make the assembly work safer when fixing bolts (12) are not used. [Explanation of symbols]

[0047] (1): Non-backlash gear (2)(3): Gears (2a)(3a):Teeth (4): Tension coil spring (elastic body) (5):Phase holding mechanism (11): Spacing fixture (12): Fixing bolt (13): Bolt parts (14): Nut material (15)(16): Slotted hole (41):Mating gear (41a): Teeth

Claims

1. A non-backlash gear in which the teeth of a mating gear are sandwiched between two gears having the same diameter and number of teeth through elastic force to eliminate backlash. the gears are connected to each other and have an elastic body that urges one gear in a circumferential direction relative to the other gear; and a phase holding mechanism that rotates the two gears relative to each other to hold the tooth phases in agreement, The phase retaining mechanism comprises a spacing retaining jig that is expandable and contractable and can retain a state at a predetermined length, and an oblong hole provided in each of the two gears so that the spacing retaining jig can be fitted into it, and the phase can be matched by expanding and contracting the spacing retaining jig within the oblong hole against the elastic force of the elastic body.

2. The spacing jig is a screw type consisting of a bolt member and a nut member screwed onto the bolt member, 2. The non-backlash gear according to claim 1, characterized in that, when a biasing force of the elastic body is acting on the two gears, the elongated hole communicates with the two gears and the screw-type spacing jig can be fitted into the elongated hole.

3. 3. The non-backlash gear according to claim 2, wherein the elongated holes have the same shape in the two gears, and when the positions of the elongated holes match between the two gears, the phases of the teeth of the two gears match.

4. The non-backlash gear according to any one of claims 1 to 3, characterized in that in the phase holding mechanism, the two gears can be fastened together with a bolt while the phases of the teeth of the two gears are aligned.

5. A method for assembling a non-backlash gear in which the teeth of two gears having the same diameter and number of teeth are sandwiched between the teeth of a mating gear via elastic force to eliminate backlash, comprising the steps of: A method for assembling a non-backlash gear, comprising fitting a spacing retaining jig that is expandable and can maintain a state at a predetermined length into a long hole provided in each of the two gears, expanding and contracting the spacing retaining jig within the long hole against the elastic force to align the phases of the teeth of the two gears, and then positioning the two gears in a position to mesh with the mating gear while maintaining the length of the spacing retaining jig.

6. The method for assembling a non-backlash gear according to claim 5, characterized in that the two gears are fastened to each other with bolts while maintaining the length of the spacing jig, and then the two gears are positioned to mesh with the mating gear.

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