CN118293198A - Gear box and design method and processing method thereof - Google Patents

Abstract

The invention discloses a gear box, a design method and a processing method thereof, wherein the gear box comprises: the worm gear assembly comprises an outer part and an inner part, the outer part is arranged on the outer peripheral side of the inner part and is suitable for rotating synchronously with the inner part, and the outer periphery of the outer part is provided with an external tooth part; a worm adapted to intermesh with the external teeth of the outer member to drive rotation of the outer member and the inner member; and the shell is used for accommodating the worm wheel assembly and the worm in a relatively rotatable manner. Through setting up worm wheel subassembly as the assembly of outer part and interior part to make interior part use metal material, the outer part can use plastic material to pass through injection molding or insert molding, and then can reduce worm wheel subassembly's processing cost, improves worm wheel subassembly's production efficiency, so that the whole manufacturing cost and the time cost of gear box can be reduced.

Description

Gear box and design method and processing method thereof

Technical Field

The invention relates to the technical field of automobile accessories, in particular to a gear box, a design method and a processing method thereof.

Background

The gear box is a common mechanism for adjusting the position of a seat on an automobile, is arranged between the seat and the bottom of a carriage and is used for realizing transmission connection cooperation between the seat and a bottom guide rail of the carriage, and the motor can enable the seat to move along the guide rail direction through the gear box during operation, so that the aim of adjusting the position of the seat is fulfilled. The existing gear box generally adopts worm and gear transmission to enable the automobile seat to move stably, in order to improve the comfort of the automobile seat during movement, the worm and the gear are required to have higher precision, and noise generated during mutual meshing rotation is small.

However, in manufacturing high-precision, low-noise worm gears and worms, expensive high-end hobbing machines are required, and the tools need to be replaced and regrinded at a high frequency, resulting in high tool costs. That is, the gear hobbing machine is used for manufacturing the worm wheel and the worm, so that the investment period is long, the cost recovery is slow, the production efficiency of the gear hobbing machine is low, and the production period of the gear box is prolonged.

Disclosure of Invention

An object of the present invention is to provide a gear box that improves the productivity of a worm wheel and reduces the manufacturing cost of the worm wheel.

Another object of the present invention is to provide a design method for designing the above gearbox.

Another object of the present invention is to provide a machining method for machining the worm gear assembly of the gear box.

In order to achieve at least one of the above objects, the present invention adopts the following technical scheme: a gearbox, comprising: the worm gear assembly comprises an outer part and an inner part, wherein the outer part is arranged on the outer peripheral side of the inner part and is suitable for rotating synchronously with the inner part, and the outer periphery of the outer part is provided with an external tooth part; a worm adapted to intermesh with the external gear of the outer member to drive rotation of the outer member and the inner member; and the shell is used for accommodating the worm wheel assembly and the worm in a relatively rotatable manner.

Preferably, the intermediate region of the outer peripheral side of the inner part has a plurality of first mating parts distributed in the circumferential direction; the inner peripheral side of the outer member has a plurality of second gaps distributed circumferentially therearound, and the first mating portion is adapted to interengage with the second gaps to permit the outer member and the inner member to rotate together.

Preferably, the outer peripheral side of the inner member further has a flange portion protruding in a radial direction, and the end face of the outer member is adapted to abut against the flange portion in the axial direction.

Preferably, a side of the flange facing the outer member has a first end face, the first end face is a conical surface, the first end face is gradually inclined outwards from one end of the flange facing the outer member to one end facing away from the outer member, and a side of the outer member facing the flange has a second end face, and the second end face is suitable for being attached to the first end face.

Preferably, the double-sided taper of the first end surface is denoted as alpha, and alpha is 80 degrees or more and 140 degrees or less.

Preferably, the length of the outer peripheral surface of the flange portion in the axial direction is L _F,0.1mm≤L_F mm or less.

Preferably, the external tooth part is a half-ring gear tooth or a ring gear tooth.

Preferably, the outer member is molded to the outer periphery of the inner member by an insert molding process.

In order to achieve at least one of the above objects, the present invention adopts the following technical scheme: a design method for designing the gear box comprises the following steps:

a1, determining the transmission ratio of a worm wheel component and a worm of a gear box and the dimensional parameters of a screw rod;

A2, determining the size parameters of the external tooth part of the outer part, the size parameters of the internal tooth part of the inner part and various parameters of the worm according to the transmission ratio and the size of the screw rod, wherein the parameters comprise: center distance a, modulus m, number of teeth z ₂ of the external tooth portion, root circle diameter df ₂ of the external tooth portion, root circle diameter df ₃ of the internal tooth portion, and number of worm heads z ₁;

A3, determining the dimension parameters of the outer part and the dimension parameters of the inner tooth part according to the dimensions of the outer tooth part and the inner tooth part, wherein the dimension parameters comprise: an outer diameter D _N of the inner member, an axial length L ₁ of the first fitting portion, an outer diameter D _F of the flange portion, an axial dimension L _F of the outer peripheral surface of the flange portion, a double-sided taper α of the first end surface, and an axial length L _W of the outer member;

and A4, determining the size parameters of the shell according to the sizes of the worm wheel assembly and the worm.

In order to achieve at least one of the above objects, the present invention adopts the following technical scheme: a processing method for processing the worm gear assembly comprises the following steps:

S1: molding an inner member of the worm gear assembly;

s2: and through an insert molding process, the outer part of the worm wheel assembly is arranged outside Zhou Chengxing of the inner part.

Compared with the prior art, the invention has the beneficial effects that:

Through setting up worm wheel subassembly as the assembly of outer part and interior part to make the interior part use the metal material, the exterior part can use plastic materials through moulding plastics or insert moulding, that is to say, worm wheel subassembly's external tooth portion can be through moulding plastics or insert moulding, has avoided adopting high-end gear hobbing machine to machine the shaping, and then can reduce worm wheel subassembly's processing cost, improves worm wheel subassembly's production efficiency, so that gear box's overall manufacturing cost and time cost can be reduced.

Drawings

FIG. 1 is an exploded view of a gearbox according to some embodiments of the present application.

Fig. 2 is a schematic structural view of an inner member mounted to a housing according to some embodiments of the present application.

Fig. 3 is a schematic view of a worm gear assembly mounted to a housing according to some embodiments of the application.

Fig. 4 is a schematic structural view (from the right) of an outer member according to some embodiments of the present application.

Fig. 5 is a schematic structural view (from the left) of an outer member according to some embodiments of the present application.

Fig. 6 is a front view of an outer member according to some embodiments of the present application.

Fig. 7 is a schematic structural view of an inner member according to some embodiments of the present application.

Fig. 8 is a front view of an inner member according to some embodiments of the application.

Fig. 9 is a partial enlarged view at a in fig. 8.

Fig. 10 is a dimensional map of a worm gear assembly according to some embodiments of the application.

In the figure: 1. a gear box; 2. a worm gear assembly; 21. an inner member; 211. an internal tooth portion; 212. a first mating portion; 213. a first gap; 214. a flange portion; 2141. a first end face; 215. a collar portion; 22. an outer member; 221. external tooth part; 222. an extension section; 2221. a second end face; 223. a gate; 224. a second mating portion; 225. a second gap; 3. a worm; 4. a collar; 5. a shaft sleeve; 6. a housing; 7. and a shock absorbing member.

Detailed Description

The present invention will be further described with reference to the following specific embodiments, and it should be noted that, on the premise of no conflict, new embodiments may be formed by any combination of the embodiments or technical features described below.

In the description of the present invention, it should be noted that, for the azimuth words such as terms "center", "lateral", "longitudinal", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc., the azimuth and positional relationships are based on the azimuth or positional relationships shown in the drawings, it is merely for convenience of describing the present invention and simplifying the description, and it is not to be construed as limiting the specific scope of protection of the present invention that the device or element referred to must have a specific azimuth configuration and operation.

It should be noted that the terms "first," "second," and the like in the description and in the claims are used for distinguishing between similar objects and not necessarily for describing a particular sequential or chronological order.

The terms "comprises" and "comprising," along with any variations thereof, in the description and claims, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.

A gearbox 1, as shown in figures 1-3, comprising: the worm wheel assembly 2, the worm 3 and the housing 6, the worm wheel assembly 2 comprises an outer part 22 and an inner part 21, the outer part 22 is arranged on the outer circumference side of the inner part 21 and is suitable for rotating synchronously with the inner part 21, and the outer circumference of the outer part 22 is provided with an external tooth part 221; the worm 3 is adapted to intermesh with the external tooth 221 of the outer part 22 to drive the rotation of the outer part 22 and the inner part 21; the housing 6 is for relatively rotatably accommodating the worm wheel assembly 2 and the worm 3.

That is, the housing 6 accommodates and supports the worm 3 and the worm wheel assembly 2 such that the worm 3 is engaged with the worm wheel assembly 2 to achieve a transmission. Specifically, the worm 3 is connected with the driving member and rotates under the action of the driving member, further, the worm 3 is meshed with the external tooth part 221 on the external part 22 of the worm wheel assembly 2, so that the worm 3 drives the external part 22 to rotate, the external part 22 drives the internal part 21 to rotate together, further, the inner periphery of the internal part 21 is provided with an internal tooth part 211 penetrating along the axial direction, the internal tooth part 211 is used for being matched with the screw rod, and further, the gear box 1 can move relative to the screw rod under the action of the driving member.

It will be appreciated that by providing the worm gear assembly 2 as a combination of the outer member 22 and the inner member 21 such that the inner member 21 is manufactured by conventional machining methods using a metallic material, the outer member 22 is injection molded or insert molded using a plastic material. It will be appreciated that in this embodiment, the inner member 21 is made of a metal material, so as to reduce wear of the inner member 21 during the movement of the inner member 21 and the screw rod, which is beneficial to prolonging the service life of the inner member 21, compared to the case where the inner member 21 is made of plastic. In addition, compared to the plastic material for the inner member 21 and the outer member 22, the use of the metal material for the inner member 21 in this embodiment is beneficial to improving the overall structural strength of the worm gear assembly 2. It should be noted that the inner member 21 may be made of plastic, and the inner member 21 may be manufactured by other processing methods, which is not particularly limited in the present application.

Further, the outer part 22 is formed by injection molding or insert molding, so that the outer tooth part 221 is prevented from being formed by adopting a high-end gear hobbing machine, and further the processing cost of the worm wheel assembly 2 is reduced on the premise of ensuring the precision and strength of the outer tooth part 221, and the production efficiency of the worm wheel assembly 2 is improved, so that the overall manufacturing cost and the time cost of the gear box 1 are reduced. The outer member 22 may be molded on the outer peripheral side of the inner member 21 by an insert molding process, thereby reducing the number of assembling processes, and being advantageous in improving the coaxiality of the outer member 22 and the inner member 21 and improving the connection strength of the outer member 22 and the inner member 21. It should be noted that the outer member 22 may also be injection molded and then bonded, keyed or otherwise coupled to the inner member 21 to allow the outer member 22 to rotate with the inner member 21.

In some embodiments, as shown in fig. 4-8, the middle region of the outer peripheral side of the inner member 21 has a plurality of first fitting portions 212 distributed in the circumferential direction; the inner peripheral side of the outer member 22 has a plurality of circumferentially distributed second gaps 225, and the first mating portion 212 is adapted to interengage with the second gaps 225 to permit the outer member 22 and the inner member 21 to rotate together. It will be appreciated that the transfer of circumferential forces is achieved by the first engagement portion 212 and the second gap 225 to avoid relative rotation between the inner member 21 and the outer member 22. That is, in the present embodiment, the first fitting portion 212 and the second gap 225 are provided to increase friction, so that the risk of relative rotation between the inner member 21 and the outer member 22 is reduced, as compared to the case where the inner member 21 and the outer member 22 are in plain contact.

In a specific embodiment, a plurality of first engaging portions 212 are circumferentially and uniformly distributed in an intermediate region on the outer peripheral side of the inner member 21, each first engaging portion 212 extends in the axial direction of the inner member 21 and radially protrudes from the outer peripheral surface of the inner member 21, and a recessed first gap 213 is formed between two adjacent first engaging portions 212. Further, a plurality of second gaps 225 are circumferentially and uniformly distributed on the inner peripheral side of the outer member 22, each second gap 225 extends in the axial direction of the outer member 22 and is radially recessed from the inner peripheral surface of the inner member 21, and a convex second fitting portion 224 is formed between two adjacent second gaps 225. It will be appreciated that when the inner member 21 and the outer member 22 are coupled to each other, the first mating portion 212 is adapted to be received in the second gap 225, the second mating portion 224 is adapted to be received in the first gap 213, and further, the first mating portion 212 is adapted to engage with the second mating portion 224, thereby enabling transmission of axial force to allow synchronous rotation of the inner member 21 and the outer member 22.

It is understood that the cross section of the first mating portion 212 may be triangular, semicircular, trapezoidal or other shape, which is not particularly limited by the present application. Also, the first fitting portion 212 may extend in the axial direction of the inner member 21, may extend spirally, or may be otherwise provided, which is not particularly limited in the present application.

It should be noted that, when the outer member 22 is molded on the outer peripheral side of the inner member 21 by the insert molding process, the second mating portion 224 is directly molded in the first gap 213, and the second gap 225 is formed between the two mating portions, so that the first mating portion 212 and the second mating portion 224 are more tightly adhered. It will be appreciated that, in this embodiment, by insert molding the outer member 22, a clearance fit designed for easy installation is avoided, which is advantageous in reducing the risk of wear due to relative movement between the outer member 22 and the inner member 21, as compared to separately molding the inner member 21 and the outer member 22; and is avoided from being designed as an interference fit to improve connection reliability, thereby facilitating a reduction in the risk of stresses in the outer member 22 due to compression. That is, by insert molding, both the mounting step is reduced and the connection reliability and the connection strength between the inner member 21 and the outer member 22 are improved.

Further, as shown in fig. 10, the length L ₁ of the first engaging portion 212 in the axial direction, the length L ₂ of the second gap 225 in the axial direction, and the length L _W of the outer member 22 in the axial direction satisfy: l ₁=L₂＜L_W. In combination with the above-described arrangement in which the first engaging portions 212 radially protrude from the outer peripheral surface of the inner member 21 and the second gaps 225 radially recess from the inner peripheral surface of the inner member 21, it is to be understood that the plurality of first engaging portions 212 entirely radially protrude from the outer peripheral surface of the inner member 21, the plurality of second gaps 225 entirely radially recess from the inner peripheral surface of the outer member 22, and the length L ₂ of the second gaps 225 in the axial direction is smaller than the length L _W of the outer member 22 in the axial direction, that is, at least one end of the inner peripheral surface of the inner member 21 is not provided with the second gaps 225, so as to be in contact with the outer peripheral surface of the inner member 21 on which the first engaging portions 212 are not provided, thereby achieving positioning of the inner member 21 and the outer member 22 in the axial direction.

Specifically, in one embodiment, one end of the inner peripheral surface of the outer member 22 is not provided with the second gap 225, that is, the second gap 225 penetrates the other end of the inner member 21, so that the end penetrated by the second gap 225 is sleeved on the first fitting portion 212 of the inner member 21 in the axial direction, and the positioning of the inner member 21 and the outer member 22 in the axial direction is achieved by the end not provided with the second gap 225. In another embodiment, the second gaps 225 are not provided at both ends of the inner peripheral surface of the outer member 22, so that the circumferential and axial positioning of the inner member 21 and the outer member 22 are achieved when the outer member 22 is insert molded to the outer periphery of the inner member 21.

In some embodiments, as shown in fig. 5-10, the outer peripheral side of the inner member 21 also has a radially protruding flange portion 214, and the end surface of the outer member 22 is adapted to abut the flange portion 214 in the axial direction. It will be appreciated that the flange portion 214 is located at one side of the first mating portion 212, and that when the inner member 21 and the outer member 22 are connected to each other, the second gap 225 of the outer member 22 is adapted to be coupled to the first mating portion 212, and that the end surface of the outer member 22 is adapted to abut against the end surface of the flange portion 214, whereby positioning of the inner member 21 and the outer member 22 in the circumferential and axial directions is achieved by the first mating portion 212 and the second gap 225, and positioning of the inner member 21 and the outer member 22 in the axial direction is further achieved by the flange portion 214.

Specifically, especially when the inner member 21 and the outer member 22 are molded and reinstalled separately, the outer member 22 is axially fitted over the inner member 21 from an end remote from the flange portion 214, and is axially positioned by the flange portion 214 to facilitate the installation operation. Further, when the outer member 22 is insert molded to the outer periphery of the inner member 21, the flange portion 214 is provided with axial positioning so as to determine the molding position of the outer member 22 at the time of injection molding. It should be noted that, the flange portion 214 abuts against the inner member 21, so that the structural strength of the worm wheel assembly 2 along the axial direction is improved, and further, the risk of damage to the worm wheel assembly 2 is reduced during the collision of the automobile, and the safety of drivers and passengers is better maintained.

In some embodiments, as shown in fig. 4-6, the inner member 21 further has an extension 222, the extension 222 being axially located on at least one side of the outer tooth portion 221, and the extension 222 being interconnected with the outer tooth portion 221, an extension 222 being located between the flange portion 214 and the outer tooth portion 221 and being adapted to abut the flange portion 214 when the inner member 21 and the outer member 22 are interconnected. It should be noted that, when the outer member 22 is insert molded, the gate 223 may be provided on the outer peripheral surface of the extension 222, or may be provided on an end surface of the outer member 22 at an end remote from the flange 214.

In one embodiment, the extension 222 is located at one side of the external gear 221, so that the gate 223 is formed on the periphery of the extension 222. Further, the outer diameter of the extension section 222 is consistent with the diameter of the addendum circle of the external tooth 221, so that the projection of the external tooth 221 along the axial direction falls into the projection area of the extension section 222 along the axial direction, and the structural strength of the external tooth 221 is improved through the extension section 222. It is understood that the outer diameter of the extension 222 may also be greater or less than the tip circle diameter of the external tooth 221. Preferably, the outer diameter of the extension 222 is identical to the diameter of the tip circle of the external tooth 221, which is advantageous for improving the structural strength of the outer member 22 and also for making the radial dimension of the outer member 22 smaller.

In some embodiments, as shown in fig. 7-9, the side of the flange portion 214 facing the outer member 22 has a first end surface 2141, the first end surface 2141 is tapered, and slopes gradually outwards from the end of the flange portion 214 facing the outer member 22 to the end facing away from the outer member 22, and the side of the outer member 22 facing the flange portion 214 has a second end surface 2221, and the second end surface 2221 is adapted to fit against the first end surface 2141. It will be appreciated that by providing the first end surface 2141 and the second end surface 2221 in an inclined arrangement, the flange portion 214 and the outer member 22 are partially overlapped in the axial direction again, which is advantageous in shortening the overall dimension of the flange portion 214 and the outer member 22 in the axial direction.

It should be noted that, by the first end surface 2141 being disposed obliquely, the axial dimension of the flange portion 214 near the axis is larger, which is beneficial to ensuring the structural strength of the flange portion 214, while the axial dimension of the flange portion 214 far from the axis is smaller, which is beneficial to increasing the axial dimension of the outer peripheral surface of the extension portion 222, so as to facilitate the arrangement of the gate 223. That is, when the outer member 22 is insert molded, the axial dimension of the extension 222 near the axis is made smaller and the axial dimension away from the axis is made larger by the second end surface 2221 mating with the first end surface 2141, so that the gate 223 is advantageously provided on the outer peripheral surface of the extension 222. In addition, the radial wall thickness of the extension section 222 gradually increases from the end close to the flange portion 214 to the end far away from the flange portion 214, that is, the flow channel gradually increases during molding, which is beneficial to mold filling and pressure maintaining, so that the molded outer part 22 is plumter, and further, the strength of the outer part 22, particularly the outer tooth portion 221, is beneficial to improvement.

In a specific embodiment, the second end surface 2221 is located at the inner periphery of the extension section 222, that is, the second end surface 2221 and the outer peripheral surface of the extension section 222 are disposed opposite to each other in the radial direction, so that the second end surface 2221 and the external tooth part 221 are prevented from overlapping in the axial direction, which is beneficial to avoid the influence of the second end surface 2221 on the structural strength of the external tooth part 221. It is understood that when the second end surface 2221 and the external tooth portion 221 overlap in the axial direction, the radial wall thickness between the second end surface 2221 and the root circle of the external tooth portion 221 will decrease, which in turn results in a decrease in the structural strength of the external tooth portion 221.

In some embodiments, as shown in FIG. 8, the double sided taper of the first end surface 2141 is denoted as α, 80+.α+.140°, to make the transition of the flange portion 214 from an axial dimension near the axis to an axial dimension away from the axis more reasonable, both to ensure structural strength of the flange portion 214 and to facilitate a reduction in the overall axial dimension of the flange portion 214 and the outer member 22. Preferably, alpha is more than or equal to 100 degrees and less than or equal to 120 degrees

In some embodiments, as shown in fig. 9, the length of the outer peripheral surface of the flange portion 214 along the axial direction is L _F,0.1mm≤L_F -1 mm, so that the edge of the flange portion 214 is not too thin and too low in strength, and the axial dimension of the flange portion 214 is also reduced, so that the structure of the worm wheel assembly 2 is more compact. Preferably, L _F is less than or equal to 0.2mm and less than or equal to 0.8mm.

In some embodiments, the external tooth part 221 is a half-ring gear tooth or a ring gear tooth, so that the external tooth part 221 and the tooth surface of the worm 3 mesh in line contact, which is beneficial to improving the bearing capacity.

In some embodiments, as shown in fig. 1-3 and 7, the inner member 21 further includes journal portions 215 at both ends, with the flange portion 214 and the first mating portion 212 being located between the two journal portions 215; the gearbox 1 further comprises a collar 4, which collar 4 is adapted to fit over the journal portion 215, the collar 4 and the flange portion 214 being located on both sides of the outer member 22 in the axial direction, i.e. the collar 4 is arranged on the side of the outer member 22 facing away from the flange portion 214. Further, the gearbox 1 further comprises a sleeve 5 adapted to be sleeved on the journal portion 215 for supporting the worm gear assembly 2 for rotation relative to the housing 6.

In some embodiments, the gear case 1 further includes a damper 7, where the damper 7 is mounted at two opposite ends of the housing 6 along the axial direction of the worm wheel assembly 2, and when the gear case 1 moves to the end of the stroke, the damper 7 has the effects of buffering, damping and noise reduction, which is beneficial to reducing the risk of damage to the gear case 1 due to impact, further prolonging the service life of the gear case 1, and improving the comfort of the car seat.

A design method for designing the above gear case 1, comprising the steps of:

A1, determining the transmission ratio of a worm wheel assembly 2 and a worm 3 of a gear box 1 and the size parameters of a screw rod;

A2, determining the size parameters of the external tooth part 221 of the outer part 22, the size parameters of the internal tooth part 211 of the inner part 21 and various parameters of the worm 3 according to the transmission ratio and the size of the screw rod, wherein the parameters comprise: center distance a, modulus m, number of teeth z ₂ of external tooth portion 221, root circle diameter df ₂ of external tooth portion 221, root circle diameter df ₃ of internal tooth portion 211, and number of heads z ₁ of worm 3;

A3, determining the size parameters of the outer member 22 and the size parameters of the inner tooth portion 211 according to the sizes of the outer tooth portion 221 and the inner tooth portion 211, including: the outer diameter D _N of the inner member 21, the axial length L ₁ of the first fitting portion 212, the outer diameter D _F of the flange portion 214, the axial dimension L _F of the outer peripheral surface of the flange portion 214, the double-sided taper α of the first end surface 2141, and the axial length L _W of the outer member 22;

A4, determining the size parameters of the shell 6 according to the sizes of the worm wheel assembly 2 and the worm 3.

It can be appreciated that in the design process, only the parameters of the cross-sectional shape of the first mating portion 212 and the axial length L ₁ of the first mating portion 212 need to be determined, and the second gap 225 and the second mating portion 224 can be directly formed by means of the first mating portion 212 during injection molding.

In one embodiment, the outer diameter D _N of the inner member 21 is 10mm, the axial length L ₁ of the first mating portion 212 is 9mm, the outer diameter D _F of the flange portion 214 is 15.2mm, the axial dimension L _F of the outer peripheral surface of the flange portion 214 is 0.2mm, the double-sided taper α of the first end surface 2141 is 110 °, and the axial length L _W of the outer member 22 is 13mm.

A machining method for machining the worm wheel assembly 2, comprising the steps of:

s1: an inner member 21 of the molded worm gear assembly 2;

S2: the outer part 22 of the worm gear assembly 2 is secured to the outer Zhou Chengxing of the inner part 21 by an insert molding process.

Specifically, the inner member 21 may be of a metal material, and the flange portion 214, the first fitting portion 212, and the internal tooth portion 211 are formed by machining or the like, and the inner member 21 is further placed in a mold to form the external tooth portion 221 by injection molding of the outer periphery of the inner member 21 by an insert molding process. The inner part 21 may also be of plastic material and thus be over-molded to obtain the worm gear assembly 2. It will be appreciated that the outer part 22 is formed directly on the outer periphery of the inner part 21 by an insert moulding process, which reduces the number of installation steps, is advantageous for improving the production efficiency of the gearbox 1, and improves the reliability and strength of the connection between the inner part 21 and the outer part 22.

The foregoing has outlined the basic principles, features, and advantages of the present invention. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, and that the above embodiments and descriptions are merely illustrative of the principles of the present invention, and various changes and modifications may be made therein without departing from the spirit and scope of the invention, which is defined by the appended claims. The scope of the invention is defined by the appended claims and equivalents thereof.

Claims (10)

1. A gearbox, comprising:

the worm gear assembly comprises an outer part and an inner part, wherein the outer part is arranged on the outer peripheral side of the inner part and is suitable for rotating synchronously with the inner part, and the outer periphery of the outer part is provided with an external tooth part;

A worm adapted to intermesh with the external gear of the outer member to drive rotation of the outer member and the inner member;

and the shell is used for accommodating the worm wheel assembly and the worm in a relatively rotatable manner.

2. A gearbox according to claim 1, wherein the intermediate region of the outer peripheral side of the inner member has a plurality of first mating portions distributed in the circumferential direction; the inner peripheral side of the outer member has a plurality of second gaps distributed circumferentially therearound, and the first mating portion is adapted to interengage with the second gaps to permit the outer member and the inner member to rotate together.

3. A gearbox according to claim 1, characterised in that the outer peripheral side of the inner part also has a radially protruding flange portion, the end face of the outer part being adapted to abut against the flange portion in the axial direction.

4. A gearbox according to claim 3, wherein the side of the flange portion facing the outer member has a first end face which is tapered, tapering outwardly from the end of the flange portion facing the outer member to the end facing away from the outer member, and wherein the side of the outer member facing the flange portion has a second end face which is adapted to engage with the first end face.

5. The gearbox of claim 4, wherein the double sided taper of the first end face is denoted as α,80 ° or less α or less 140 °.

6. A gear box according to claim 3, wherein the length of the outer peripheral surface of the flange portion in the axial direction is L _F,0.1mm≤L_F -1mm.

7. The gearbox of claim 1, wherein the external tooth portion is a half-ring gear tooth or a ring gear tooth.

8. A gearbox according to any of claims 1-7, wherein the outer part is moulded to the outer periphery of the inner part by an insert moulding process.

9. A design method for designing a gear box according to any one of claims 1-8, comprising the steps of:

a1, determining the transmission ratio of a worm wheel component and a worm of a gear box and the dimensional parameters of a screw rod;

A2, determining the size parameters of the external tooth part of the outer part, the size parameters of the internal tooth part of the inner part and various parameters of the worm according to the transmission ratio and the size of the screw rod, wherein the parameters comprise: center distance a, modulus m, number of teeth z ₂ of the external tooth portion, root circle diameter df ₂ of the external tooth portion, root circle diameter df ₃ of the internal tooth portion, and number of worm heads z ₁;

A3, determining the dimension parameters of the outer part and the dimension parameters of the inner tooth part according to the dimensions of the outer tooth part and the inner tooth part, wherein the dimension parameters comprise: an outer diameter D _N of the inner member, an axial length L ₁ of the first fitting portion, an outer diameter D _F of the flange portion, an axial dimension L _F of the outer peripheral surface of the flange portion, a double-sided taper α of the first end surface, and an axial length L _W of the outer member;

and A4, determining the size parameters of the shell according to the sizes of the worm wheel assembly and the worm.

10. A method of machining a worm gear assembly as claimed in any one of claims 1 to 8, comprising the steps of:

S1: molding an inner member of the worm gear assembly;

s2: and through an insert molding process, the outer part of the worm wheel assembly is arranged outside Zhou Chengxing of the inner part.