External gear set and small-tooth-difference reducer

Abstract

The utility model discloses a kind of outer gear set and few-tooth difference speed reducer, belong to speed reducer technical field.The outer gear set includes: at least two outer gears, each the outer gear includes gear body, central shaft hole and be used for detachably connecting multiple connection matching parts are equipped on the gear body, the connection matching part does not interfere with the stress area of the gear tooth of the gear body, and be configured as can be fixedly connected by an external connecting piece The at least two outer gears are connected into a rigid gear combination body.Compared with prior art, the outer gear set of the utility model can form a rigid gear combination body by connection matching part and carry out profile machining, improve profile machining precision and consistency, simplify processing tooling, reduce production cost, and avoid the precision damage problem such as scratch, deformation in positioning process Inner wall of pinhole.

Description

Technical Field

[0001] This utility model relates to an external gear set and a reducer with a small tooth difference, belonging to the field of reducer technology. Background Technology

[0002] A low-tooth-difference reducer is a transmission device that achieves a high reduction ratio and compact structure by using an internal gear and an external gear to form an internal meshing gear pair with a small tooth difference. Its core transmission process involves an eccentric shaft as the input component, driving two external gears with a phase difference to operate synchronously. Both external gears mesh with the same fixed internal gear, utilizing the small tooth difference between the internal and external gears to achieve speed reduction output.

[0003] Since the two external gears are driven by the same eccentric shaft, they need to synchronously complete their revolution around the internal gear and their own rotation. Therefore, their tooth profile parameters must be completely identical to ensure a uniform meshing clearance between the two gears and the internal gear. If there are differences in the tooth profile, one external gear will mesh too tightly with the internal gear, while the other will mesh too loosely, leading to meshing interference and uneven load distribution. This can result in reduced transmission efficiency and increased operating noise, or even more serious issues such as accelerated localized wear of the gears, jamming, and tooth surface cracking, severely impacting the service life and operational reliability of the low-tooth-difference reducer.

[0004] In existing manufacturing processes, to ensure the consistency of the tooth profile of two paired external gears, positioning is typically achieved using the shaft hole at the center of the gear body and the circumferentially arranged pin holes. The two gear blanks are then stacked together for simultaneous finishing (such as gear grinding). However, because the pin hole dimensions vary between different specifications or batches of external gears, the corresponding gear grinding fixtures need to be equipped with various sizes of bushings (or liner bushings) to accommodate different pin holes for positioning. This increases the complexity of the gear grinding fixtures and reduces processing efficiency and flexibility. Furthermore, when using pin holes for positioning during gear grinding, the close contact between the positioning pin and the inner wall of the pin hole can cause scratches on the inner wall of the pin hole, compromising the transmission accuracy of the pin hole. Utility Model Content

[0005] To solve the above-mentioned technical problems, this utility model provides an external gear set that is easy to machine and a reducer with a small tooth difference.

[0006] The technical solution of this utility model is: This utility model provides an external gear set for use in a low tooth difference reducer, comprising at least two external gears, each of which includes a gear body. The gear body is provided with a central shaft hole and multiple connecting parts for detachable connection. The connecting parts do not interfere with the force-bearing area of ​​the gear teeth of the gear body and are configured to be able to fix the at least two external gears into a rigid gear assembly by means of an external connector.

[0007] Optionally, the connecting part includes a connecting hole formed on the gear body, the connecting hole including a first connecting hole and a second connecting hole that cooperate with each other.

[0008] Optionally, the external gear set includes a first external gear and a second external gear, wherein a first connecting hole on the first external gear corresponds to a second connecting hole on the second external gear, and vice versa.

[0009] Optionally, the first connection hole includes a countersunk section and a through-hole section communicating with the countersunk section, the countersunk section being configured to receive the head of the external connector.

[0010] Optionally, the second connecting hole is a threaded hole.

[0011] Optionally, a plurality of pin holes for transmission engagement are provided outside the force-bearing area of ​​the gear teeth of the gear body, and the connecting engagement part is a connecting hole provided between two adjacent pin holes.

[0012] Optionally, the diameter of the pin hole is 3 to 10 times the maximum diameter of the connecting hole.

[0013] Optionally, the gear body has multiple machining areas for forming pin holes outside the tooth force-bearing area, and the connecting mating part is disposed between two adjacent machining areas.

[0014] Optionally, the gear body includes a first end face and a second end face disposed opposite to each other, the first end face being a plane, and the second end face having an annular clearance portion located outside the connecting mating portion.

[0015] This utility model also provides a reducer with a small tooth difference, including an eccentric shaft, an internal gear, and the aforementioned external gear set. The external gear set is disposed on the eccentric shaft and meshes with the internal gear.

[0016] The beneficial technical effects of this utility model are: This invention relates to external gear sets in reducers with small tooth difference. By providing multiple detachable connecting parts on the gear body of each external gear that do not interfere with the force-bearing area of ​​the teeth, at least two external gears can be fixedly connected into a rigid gear assembly using external connectors. This allows the two external gears to undergo tooth profile finishing (such as gear grinding) as a single, immovable rigid unit, significantly improving tooth profile machining accuracy and consistency. Furthermore, the detachable design balances machining flexibility with subsequent installation convenience. Compared to traditional pin hole positioning methods, it eliminates the need for multi-specification bushings, simplifying machining tooling, shortening machining preparation time, and greatly improving production efficiency. It also avoids precision damage issues such as scratches and deformation of the pin hole inner wall during positioning, extending the service life of the external gears and reducer. In addition, because the connecting parts can fix at least two external gears into a rigid gear assembly, the external gear set can be sequentially machined for pin hole machining and tooth profile grinding in a machining center with a single fixing, or transferred between different specialized machines without realignment, greatly improving efficiency and quality stability, and providing possibilities for subsequent automated machining of external gear sets. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the external gear assembly conforming to a preferred embodiment of the present utility model; Figure 2 yes Figure 1 A schematic diagram of the structure of the first external gear; Figure 3 yes Figure 1 A structural schematic diagram of the first external gear from another perspective; Figure 4 This is a schematic diagram of the structure of a low-tooth-difference reducer conforming to a preferred embodiment of the present utility model; Figure 5 yes Figure 4 A sectional view.

[0018] Explanation of reference numerals in the attached figures: A reducer with a small tooth difference 100, housing 10, eccentric shaft 20, internal gear 30, external gear set 40, first external gear 41, second external gear 42, gear body 43, central shaft hole 44, connecting mating part 45, first connecting hole 451, countersunk section 4511, through hole section 4512, second connecting hole 452, pin hole 46, first end face 47, second end face 48, annular clearance part 481, output flange 50, support flange 60, and first bearing 70. Detailed Implementation

[0019] In order to better understand the technical means of this utility model and to implement it in accordance with the contents of the specification, the specific embodiments of this utility model will be further described in detail below with reference to the accompanying drawings and examples. The following examples are used to illustrate this utility model, but are not intended to limit the scope of this utility model.

[0020] Example 1 Please refer to Figures 1 to 3. This embodiment provides an external gear set 40 for a low-tooth-difference reducer 100. The external gear set 40 includes at least two external gears, which have identical structures and can be precisely paired for use. Each external gear includes a gear body 43, with a central shaft hole 44 at its center. This central shaft hole 44 is used for assembly with the eccentric shaft 20 of the low-tooth-difference reducer 100, and its inner wall is precision ground to ensure fitting accuracy. In this embodiment, the external gear set 40 includes two external gears, namely a first external gear 41 and a second external gear 42. In other embodiments, the external gear set 40 may also include three or more external gears; this invention does not limit this.

[0021] The gear body 43 is provided with multiple connecting parts 45 specifically for detachable connection. In this embodiment, there are 12 connecting parts 45, which are evenly distributed circumferentially along the central shaft hole 44. These connecting parts 45 are only used to achieve detachable fixing of the two external gears, do not undertake any transmission function, and do not interfere with the force-bearing area of ​​the gear teeth of the gear body 43. This arrangement avoids the radial and circumferential range of the core load-bearing area when the teeth mesh, ensuring that the gear transmission strength is not affected.

[0022] In this embodiment, the connecting part 45 is a connecting hole formed on the gear body 43. In other embodiments, other connecting structures may also be used, such as snap-fit. By providing a connecting hole, the weight of the gear body 43 can be reduced, achieving a lighter weight for the low-tooth-difference reducer 100.

[0023] The connecting holes include a first connecting hole 451 and a second connecting hole 452 that mate with each other. Each gear body 43 is provided with 6 first connecting holes 451 and 6 second connecting holes 452. The first connecting holes 451 and the second connecting holes 452 are distributed alternately along the circumference of the central shaft hole 44 to form a symmetrical layout to ensure uniform locking force.

[0024] The first connecting hole 451 on the first external gear 41 and the second connecting hole 452 on the second external gear 42 are coaxially corresponding. Similarly, the second connecting hole 452 on the first external gear 41 and the first connecting hole 451 on the second external gear 42 are also coaxially corresponding. During assembly, external connectors (counterhead bolts in this embodiment, but other fasteners in other embodiments) pass through the first connecting hole 451 of one external gear in sequence and then engage with the second connecting hole 452 of the other external gear, securely locking the two external gears together to form a rigid gear assembly.

[0025] The first connecting hole 451 is a stepped hole, comprising a countersunk section 4511 with a larger diameter and a through-hole section 4512 communicating with the countersunk section 4511. The countersunk section 4511 is specially constructed to accommodate the head of the external connector, ensuring that the head of the external connector does not protrude from the end face of the gear body 43 after assembly, thus avoiding interference with other internal components of the low-tooth-difference reducer 100. The through-hole section 4512 is a cylindrical hole with a clearance fit between its diameter and the screw diameter of the external connector, ensuring smooth assembly.

[0026] The second connecting hole 452 is a threaded hole. The nominal diameter of the threaded hole is perfectly matched with the external thread specification of the external connector (e.g., an M5 threaded hole is compatible with an M5 countersunk bolt). The threaded engagement enables detachable locking and fixing. Compared with other connection methods, the threaded connection has a stronger locking force and is easy to disassemble, balancing reliability and flexibility.

[0027] Outside the force-bearing area of ​​the gear teeth on the gear body 43, multiple pin holes 46 for transmission engagement are provided. In this embodiment, there are 12 pin holes, evenly distributed circumferentially along the central shaft hole 44. The connecting parts 45 (first connecting hole 451 and second connecting hole 452) are all located between two adjacent pin holes 46. This arrangement fully utilizes the circumferential unused space of the gear body 43 and avoids interference between the connecting parts 45 and the pin holes 46 during machining or transmission, ensuring that the transmission function of the pin holes 46 and the locking function of the connecting parts 45 do not affect each other.

[0028] Furthermore, the diameter of the pin hole 46 is 3 to 10 times the maximum diameter of the connecting hole (first connecting hole 451) (the large end diameter of the countersunk section 4511). For example, it can be 3 times, 6 times, or 10 times. This setting ensures the torque transmission strength of the pin hole 46 while avoiding weakening the strength of the gear body 43 by making the connecting hole diameter too large.

[0029] Furthermore, the gear body 43 includes a first end face 47 and a second end face 48 disposed opposite to each other. The first end face 47 is a plane to improve the flatness and positioning accuracy of the two external gear sets 40. The second end face 48 is provided with an annular clearance portion 481 (radially outward) located outside the connecting mating portion 45 to avoid bearing components during assembly, prevent mechanical interference, and reserve heat dissipation space.

[0030] In this embodiment, during the machining of the external gear assembly 40, multiple countersunk screws are used as external connectors. These screws pass through the first connecting hole 451 on one gear and are screwed into the corresponding second connecting hole 452 (threaded hole) on the other gear. After all the screws are tightened, the two external gears are fixedly connected into a rigid gear assembly. Then, the assembly is directly transferred to a gear grinding machine for synchronous gear grinding without additional positioning. This ensures tooth profile consistency and avoids the problem of pin hole 46 precision damage caused by traditional pin hole positioning.

[0031] Example 2 This embodiment is basically the same in structure as Embodiment 1. The core difference is that multiple machining areas for forming pin holes 46 are provided outside the force-bearing area of ​​the gear teeth of the gear body 43. These machining areas are the preset machining positions for the pin holes 46 and have not yet been drilled or reamed. The connecting mating parts 45 (the first connecting hole 451 and the second connecting hole 452) are also provided between two adjacent machining areas and are located radially outside the machining areas to avoid interference with the subsequent machining path of the pin holes 46.

[0032] The processing flow of this embodiment is as follows: First, the first external gear 41 and the second external gear 42 are locked into a rigid assembly using countersunk bolts. Then, using the central shaft hole 44 as a reference, the processing areas of the two external gears are simultaneously drilled and reamed to form pin holes 46 with completely identical dimensions and positions in one operation. After the pin holes 46 are processed, the assembly can be ground directly on the same machine or transferred to a gear grinding machine without disassembling. This process enables continuous operation with multiple processes completed in a single fixed operation, providing the possibility for subsequent automated gear grinding.

[0033] Example 3 As shown in Figures 4 and 5, this embodiment provides a low-tooth-difference reducer 100, which includes a housing 10, an eccentric shaft 20, an internal gear 30, and an external gear set 40. The internal gear 30 is connected to the housing 10 by bolts. The external gear set 40 is mounted on the eccentric shaft 20 through its central shaft hole 44. The central shaft hole 44 is clearance-fitted with the journal of the eccentric shaft 20 (tolerance grade IT7) to ensure that the external gears operate synchronously with the eccentric shaft 20. Both external gears of the external gear set 40 are meshed with the internal gear 30, forming a low-tooth-difference internal meshing gear pair. An output flange 50 and a support flange 60 are respectively disposed on both sides of the external gear set 40 and connected by multiple rotary pins for transmitting torque, and are fixed by multiple support pins. A first bearing 70 is provided between the internal gear 30, the output flange 50, and the support flange 60. The second end face 48 of the external gear faces the first bearing 70 so as to avoid mechanical interference and reserve heat dissipation space by passing through the annular clearance part 481 to avoid the first bearing 70.

[0034] Because the two external gears of the external gear set 40 of this utility model have completely consistent tooth profiles and precise phase relationships after processing, they can achieve uniform and stable meshing with the internal gear 30 during the operation of the reducer. This effectively solves the problems of uneven load, vibration and noise caused by tooth profile differences in traditional structures, thereby significantly improving the transmission accuracy, load-bearing capacity and service life of the small tooth difference reducer 100.

[0035] In summary, the external gear assembly 40 in the low-tooth-difference reducer 100 of this invention, by providing multiple detachable connecting parts 45 on the gear body 43 of each external gear that do not interfere with the force-bearing area of ​​the teeth, allows at least two external gears to be fixedly connected into a rigid gear assembly using external connecting parts. This enables the two external gears to be precision-machined (e.g., ground) as a single, immovable rigid unit, significantly improving the precision and consistency of the tooth profile machining. Furthermore, the detachable design balances machining flexibility with subsequent installation convenience. Compared to the traditional pin-hole positioning method, it eliminates the need for multi-specification bushings, simplifies machining tooling, shortens machining preparation time, significantly improves production efficiency, and avoids precision damage issues such as scratches and deformation of the inner wall of the pin hole 46 during positioning, thus extending the service life of the external gears and the reducer. In addition, since the connecting and mating part 45 can fix at least two external gears into a rigid gear assembly, the external gear set 40 can be fixed in one step to complete the pin hole 46 machining and tooth profile grinding in the machining center, or transferred between different equipment without realignment, which greatly improves efficiency and quality stability and provides the possibility for subsequent automated machining of the external gear set 40.

[0036] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present utility model, and these improvements and modifications should also be considered within the protection scope of the present utility model.

Claims

1. An external gear set for use in a reducer with a small tooth difference, characterized in that, include: At least two external gears, each of which includes a gear body having a central shaft hole and a plurality of connecting parts for detachable connection, the connecting parts not interfering with the force-bearing area of ​​the gear teeth of the gear body, and configured to be able to fix the at least two external gears into a rigid gear assembly by means of an external connector.

2. The external gear set according to claim 1, characterized in that, The connecting part includes a connecting hole formed on the gear body, the connecting hole including a first connecting hole and a second connecting hole that cooperate with each other.

3. The external gear set according to claim 2, characterized in that, The external gear set includes a first external gear and a second external gear. The first connecting hole on the first external gear corresponds to the second connecting hole on the second external gear, and the second connecting hole on the first external gear corresponds to the first connecting hole on the second external gear.

4. The external gear set according to claim 2, characterized in that, The first connection hole includes a countersunk section and a through-hole section communicating with the countersunk section, the countersunk section being configured to receive the head of the external connector.

5. The external gear set according to claim 2, characterized in that, The second connecting hole is a threaded hole.

6. The external gear set according to any one of claims 1 to 5, characterized in that, Outside the force-bearing area of ​​the gear teeth in the gear body, there are also a number of pin holes for transmission engagement, and the connecting engagement part is a connecting hole provided between two adjacent pin holes.

7. The external gear set according to claim 6, characterized in that, The diameter of the pin hole is 3 to 10 times the maximum diameter of the connecting hole.

8. The external gear set according to any one of claims 1 to 5, characterized in that, In addition to the force-bearing area of ​​the gear teeth, the gear body is provided with multiple processing areas for forming pin holes, and the connecting and mating part is arranged between two adjacent processing areas.

9. The external gear set according to claim 1, characterized in that, The gear body includes a first end face and a second end face that are disposed opposite to each other. The first end face is a plane, and the second end face is provided with an annular clearance portion located outside the connecting and mating portion.

10. A reducer with a small tooth difference, characterized in that, It includes an eccentric shaft, an internal gear, and an external gear set as described in any one of claims 1 to 9, wherein the external gear set is disposed on the eccentric shaft and meshes with the internal gear.

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