Split nut gear assembly and gear box thereof

Abstract

The utility model discloses a split nut gear assembly and a gearbox thereof.The split nut gear assembly comprises an outer part and an inner part, the outer part is arranged on the peripheral side of the inner part and suitable for synchronously rotating with the inner part, and the periphery of the outer part is provided with an outer tooth part; the worm is suitable for being meshed with the outer tooth part of the outer part so as to drive the outer part and the inner part to rotate; and the shell is used for accommodating the split nut gear assembly and the worm in a relatively rotating manner. According to the split nut gear assembly, the split nut gear assembly is arranged to be the combination of the outer part and the inner part, so that the inner part is made of metal materials, the outer part is made of plastic materials through injection molding or plastic embedding molding, the machining cost of the split nut gear assembly is reduced, and the production efficiency of the split nut gear assembly is improved; therefore, the overall manufacturing cost and the time cost of the gearbox are reduced.

Description

Technical Field

[0001] The invention relates to the technical field of automobile accessories, in particular to a split nut gear assembly and a gear box thereof. Background Art

[0002] The gearbox is a common mechanism used to adjust the seat position in cars. It is set between the seat and the bottom of the car to achieve the transmission connection between the seat and the guide rail at the bottom of the car. When the motor is working, it can move the seat along the guide rail through the gearbox, thereby achieving the purpose of adjusting the seat position. Existing gearboxes usually use worm gear transmission to make the car seat move smoothly. In order to improve the comfort of the car seat when moving, the worm gear and worm are required to have high precision and generate less noise when they rotate in mesh with each other.

[0003] However, when manufacturing high-precision, low-noise worm gears and worms, expensive high-end gear hobbing machines are required, and the tools need to be replaced and reground more frequently, resulting in high tool costs. In other words, using gear hobbing machines to manufacture worm gears and worms not only has a long investment cycle and slow cost recovery, but also has low production efficiency, which will extend the production cycle of gearboxes. Summary of the invention

[0004] An object of the present invention is to provide a split nut gear assembly, which can improve the production efficiency of the worm gear in the gear box and reduce the manufacturing cost.

[0005] An object of the present invention is to provide a gear box having the above-mentioned split nut gear assembly.

[0006] In order to achieve at least one of the above purposes, the technical solution adopted by the present invention is: a split nut gear assembly, comprising: an outer component and an inner component, the outer component is arranged on the outer peripheral side of the inner component and is suitable for synchronous rotation with the inner component, the outer periphery of the outer component has an external tooth portion, and the inner peripheral side of the inner component has an internal tooth portion.

[0007] Preferably, the middle area of ​​the outer circumferential side of the inner component has a plurality of first matching parts distributed along the circumferential direction; the inner circumferential side of the outer component has a plurality of second gaps distributed along the circumferential direction, and the first matching parts are suitable for engaging with the second gaps so that the outer component and the inner component rotate together.

[0008] As a preference, the outer peripheral side of the inner component further has a flange portion protruding in the radial direction, and the end surface of the outer component is suitable for abutting against the flange portion in the axial direction.

[0009] Preferably, the flange portion has a first end face on a side facing the outer component, the first end face is a conical surface, gradually inclining outward from an end of the flange portion facing the outer component to an end away from the outer component, and the outer component has a second end face on a side facing the flange portion, the second end face is suitable for fitting with the first end face.

[0010] As a preference, the double-sided taper of the first end face is denoted as α, 80°≤α≤140°.

[0011] As a preference, the axial length of the outer peripheral surface of the flange portion is denoted as L, and 0.1 mm≤L≤1 mm.

[0012] Preferably, the outer tooth portion is a semi-annular worm gear tooth or annular worm gear teeth.

[0013] As a preferred embodiment, the outer component is formed on the outer periphery of the inner component by an insert molding process.

[0014] In order to achieve at least one of the above purposes, the technical solution adopted by the present invention is: a gear box, including the split nut gear assembly as described above; a worm gear, suitable for engaging with the outer tooth portion of the split nut gear assembly to rotate the split nut gear assembly; a housing, used to accommodate the split nut gear assembly and the worm gear in a relatively rotatable manner.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] By configuring the split nut gear assembly as a combination of an outer component and an inner component, the inner component can be made of metal material, and the outer component can be made of plastic material by injection molding or insert molding. That is to say, the outer tooth portion of the split nut gear assembly can be molded by injection molding or insert molding, thereby avoiding the use of high-end gear hobbing machines for processing and molding, thereby reducing the processing cost of the split nut gear assembly, improving the production efficiency of the split nut gear assembly, and reducing the overall manufacturing cost and time cost of the gear box. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is an exploded view of a gearbox according to some embodiments of the present application;

[0018] Figure 2 is a schematic diagram of a structure in which an internal component is installed on a housing according to some embodiments of the present application;

[0019] Figure 3 is a schematic diagram of a structure in which a split nut and gear assembly is installed on a housing according to some embodiments of the present application;

[0020] Figure 4 is a schematic structural diagram of an outer component according to some embodiments of the present application (seen from the right);

[0021] Figure 5 is a schematic structural diagram of an outer component according to some embodiments of the present application (viewed from the left);

[0022] Figure 6 is a front view of an outer component according to some embodiments of the present application;

[0023] Figure 7 is a schematic diagram of the structure of the internal components according to some embodiments of the present application;

[0024] Figure 8 is a front view of an inner component according to some embodiments of the present application;

[0025] Fig. 9 yes Figure 8 A partial enlarged view of the middle A;

[0026] Fig.10 This is a dimension diagram of a split nut gear assembly according to some embodiments of the present application.

[0027] In the figure: 1, gear box; 2, split nut gear assembly; 21, inner component; 211, inner tooth portion; 212, first matching portion; 213, first gap; 214, flange portion; 2141, first end face; 215, journal neck; 22, outer component; 221, outer tooth portion; 222, extension section; 2221, second end face; 223, gate; 224, second matching portion; 225, second gap; 3, worm; 4, collar; 5, bushing; 6, housing; 7, shock absorber. DETAILED DESCRIPTION

[0028] The present invention is further described below in conjunction with specific implementation methods. It should be noted that, under the premise of no conflict, the various embodiments or technical features described below can be arbitrarily combined to form a new embodiment.

[0029] In the description of the present invention, it should be noted that directional words, such as the terms "center", "lateral", "longitudinal", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", etc., indicating directions and positional relationships are based on the directions or positional relationships shown in the accompanying drawings, which are only for the convenience of narrating the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and cannot be understood as limiting the specific scope of protection of the present invention.

[0030] It should be noted that the terms "first", "second", etc. in the description and claims of the present application are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence.

[0031] The terms "including" and "having" and any variations thereof in the specification and claims of this application are intended to cover non-exclusive inclusions. For example, a process, method, system, product or apparatus comprising a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to these processes, methods, products or apparatuses.

[0032] A split nut gear assembly 2, such as Figure 1-Figure 10 As shown, it includes an outer part 22 and an inner part 21. The outer part 22 is arranged on the outer peripheral side of the inner part 21 and is suitable for rotating synchronously with the inner part 21. The outer periphery of the outer part 22 has an external tooth portion 221, which is suitable for meshing with the worm 3 of the gear box 1; the inner peripheral side of the inner part 21 has an internal tooth portion 211, which is suitable for cooperating with the screw.

[0033] It is understandable that by setting the split nut gear assembly 2 as a combination of an outer component 22 and an inner component 21, the inner component 21 can be manufactured using metal materials through traditional machining methods, and the outer component 22 can be manufactured using plastic materials through injection molding or insert molding. It is understandable that, compared with the use of plastic to manufacture the inner component 21, in this embodiment, the use of metal materials to manufacture the inner component 21 can reduce the wear of the inner component 21 when the inner component 21 and the screw rod move in coordination, which is beneficial to extending the service life of the inner component 21. In addition, compared with the use of plastic materials for both the inner component 21 and the outer component 22, in this embodiment, the use of metal materials for the inner component 21 is beneficial to improving the overall structural strength of the split nut gear assembly 2. It is worth mentioning that the inner component 21 can also be made of plastic materials, and the inner component 21 can also be manufactured by other processing methods, and this application does not make specific restrictions on this.

[0034] Furthermore, the outer component 22 is formed by injection molding or insert molding, which avoids the use of high-end gear hobbing machines to process and mold the outer tooth portion 221, thereby reducing the processing cost of the split nut gear assembly 2 and improving the production efficiency of the split nut gear assembly 2 while ensuring the accuracy and strength of the outer tooth portion 221, so that the overall manufacturing cost and time cost of the gearbox 1 can be reduced. The outer component 22 can be molded on the outer peripheral side of the inner component 21 by insert molding, thereby reducing the assembly process, and at the same time, it is beneficial to improve the coaxiality of the outer component 22 and the inner component 21, and improve the connection strength of the outer component 22 and the inner component 21. It is worth mentioning that the outer component 22 can also be formed by injection molding, and then connected to the inner component 21 by bonding, key connection or other methods, so that the outer component 22 can rotate with the inner component 21.

[0035] In some embodiments, Figure 4-Figure 8 As shown, the middle area of ​​the outer circumference of the inner part 21 has a plurality of first matching parts 212 distributed along the circumferential direction; the inner circumference of the outer part 22 has a plurality of second gaps 225 distributed along the circumferential direction, and the first matching parts 212 are adapted to engage with the second gaps 225 so that the outer part 22 and the inner part 21 rotate together. It can be understood that the transmission of circumferential force can be achieved through the first matching parts 212 and the second gaps 225 to avoid relative rotation between the inner part 21 and the outer part 22. In other words, compared with the pure smooth surface contact between the inner part 21 and the outer part 22, in this embodiment, the first matching parts 212 and the second gaps 225 are provided to increase friction, which is conducive to reducing the risk of relative rotation between the inner part 21 and the outer part 22.

[0036] In a specific embodiment, a plurality of first matching portions 212 are uniformly distributed along the circumferential direction in the middle area of ​​the outer peripheral side of the inner member 21, each first matching portion 212 extends along the axial direction of the inner member 21, and is radially protruded from the outer peripheral surface of the inner member 21, and a concave first gap 213 is formed between two adjacent first matching portions 212. Further, a plurality of second gaps 225 are uniformly distributed along the circumferential direction on the inner peripheral side of the outer member 22, each second gap 225 extends along the axial direction of the outer member 22, and is radially recessed from the inner peripheral surface of the inner member 21, and a protruding second matching portion 224 is formed between two adjacent second gaps 225. It can be understood that when the inner member 21 and the outer member 22 are connected to each other, the first matching portion 212 is suitable for being accommodated in the second gap 225, and the second matching portion 224 is suitable for being accommodated in the first gap 213. Further, the first matching portion 212 is suitable for being fitted with the second matching portion 224, thereby realizing the transmission of axial force, so that the inner member 21 and the outer member 22 rotate synchronously.

[0037] It is understandable that the cross section of the first matching portion 212 may be a triangle, a semicircle, a trapezoid or other shapes, and the present application does not impose any specific restrictions on this. In addition, the first matching portion 212 may extend along the axial direction of the inner component 21, may extend in a spiral manner, or may be arranged in other ways, and the present application does not impose any specific restrictions on this.

[0038] It is worth mentioning 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 matching portion 224 is directly molded in the first gap 213, and a second gap 225 is formed between the two matching portions, so that the first matching portion 212 and the second matching portion 224 fit more closely. It can be understood that, compared with molding the inner member 21 and the outer member 22 separately and then combining them, in this embodiment, by insert molding the outer member 22, it is possible to avoid designing a clearance fit for easy installation, thereby helping to reduce the risk of wear caused by relative movement between the outer member 22 and the inner member 21; and it is possible to avoid designing an interference fit to improve the connection reliability, thereby helping to reduce the risk of stress caused by extrusion in the outer member 22. In other words, by insert molding, it is possible to reduce the number of installation steps and improve the connection reliability and connection strength between the inner member 21 and the outer member 22.

[0039] Furthermore, Fig.10 As shown, the length of the first matching portion 212 along the axial direction is L1, the length of the second gap 225 along the axial direction is L2, and the length of the outer member 22 along the axial direction is L W , satisfying: L1=L2<L W In combination with the above-mentioned first matching portions 212 radially protruding from the outer circumference of the inner member 21, and the second gaps 225 radially recessed from the inner circumference of the inner member 21, it can be understood that a plurality of first matching portions 212 radially protrude from the outer circumference of the inner member 21 as a whole, a plurality of second gaps 225 radially recessed from the inner circumference of the outer member 22 as a whole, and the axial length L2 of the second gaps 225 is less than the axial length L W That is, at least one end of the inner circumferential surface of the inner component 21 is not provided with the second gap 225, so that it can be fitted with the outer circumferential surface of the inner component 21 which is not provided with the first matching portion 212, thereby positioning the inner component 21 and the outer component 22 in the axial direction.

[0040] Specifically, in one specific embodiment, one end of the inner circumference 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, and then the end that is penetrated by the second gap 225 is axially sleeved on the first matching portion 212 of the inner member 21, and the inner member 21 and the outer member 22 are positioned in the axial direction through the end that is not provided with the second gap 225. In another specific embodiment, the second gap 225 is not provided at both ends of the inner circumference of the outer member 22, and then when the outer member 22 is insert-molded on the outer circumference of the inner member 21, the circumferential positioning and axial positioning of the inner member 21 and the outer member 22 are achieved.

[0041] In some embodiments, Figure 5-Figure 10As shown, the outer peripheral side of the inner component 21 also has a flange portion 214 protruding in the radial direction, and the end face of the outer component 22 is suitable for abutting against the flange portion 214 in the axial direction. It can be understood that the flange portion 214 is located on one side of the first matching portion 212, and when the inner component 21 and the outer component 22 are connected to each other, the second gap 225 of the outer component 22 is suitable for combining with the first matching portion 212, and the end face of the outer component 22 is suitable for abutting against the end face of the flange portion 214, thereby enabling the inner component 21 and the outer component 22 to be positioned in the circumferential direction and the axial direction through the first matching portion 212 and the second gap 225, and further enabling the inner component 21 and the outer component 22 to be positioned in the axial direction through the flange portion 214.

[0042] Specifically, especially when the inner component 21 and the outer component 22 are separately molded and then installed, the outer component 22 can be axially sleeved on the inner component 21 from the end away from the flange portion 214, and the axial positioning is achieved through the flange portion 214 to facilitate the installation operation. In addition, when the outer component 22 is insert-molded on the outer periphery of the inner component 21, the flange portion 214 can provide axial positioning to facilitate the determination of the molding position of the outer component 22 during injection molding. It is worth mentioning that the structural strength of the split nut gear assembly 2 along the axial direction can be improved by the flange portion 214 and the inner component 21 offsetting each other, which is conducive to reducing the risk of damage to the split nut gear assembly 2 when the car collides, and better maintaining the safety of the driver and passengers.

[0043] In some embodiments, Figure 4-Figure 6 As shown, the inner component 21 further has an extension section 222, which is located at least on one side of the outer tooth portion 221 in the axial direction, and the extension section 222 is connected to the outer tooth portion 221. When the inner component 21 and the outer component 22 are connected to each other, an extension section 222 is located between the flange portion 214 and the outer tooth portion 221, and is suitable for abutting against the flange portion 214. It is worth mentioning that when the outer component 22 is insert molded, the gate 223 can be set on the outer peripheral surface of the extension section 222, and can also be set on the end surface of the outer component 22 away from the flange portion 214.

[0044] In a specific embodiment, the extension section 222 is located on one side of the outer tooth portion 221, so that a gate 223 can be opened on the outer periphery of the extension section 222. Furthermore, the outer diameter of the extension section 222 is consistent with the diameter of the tooth top circle of the outer tooth portion 221, so that the projection of the outer tooth portion 221 along the axial direction falls into the projection area of ​​the extension section 222 along the axial direction, and the extension section 222 is helpful to improve the structural strength of the outer tooth portion 221. It can be understood that the outer diameter of the extension section 222 can also be greater than or less than the diameter of the tooth top circle of the outer tooth portion 221. Preferably, the outer diameter of the extension section 222 is consistent with the diameter of the tooth top circle of the outer tooth portion 221, which is beneficial to improve the structural strength of the outer component 22 and make the radial dimension of the outer component 22 smaller.

[0045] In some embodiments, Figure 7-Figure 9 As shown, the flange portion 214 has a first end face 2141 on the side facing the outer member 22, and the first end face 2141 is a conical surface, which gradually tilts outward from the end of the flange portion 214 facing the outer member 22 to the end away from the outer member 22, and the outer member 22 has a second end face 2221 on the side facing the flange portion 214, and the second end face 2221 is suitable for fitting with the first end face 2141. It can be understood that, by the inclined first end face 2141 and the second end face 2221, the flange portion 214 and the outer member 22 are partially overlapped in the axial direction, which is conducive to shortening the overall size of the flange portion 214 and the outer member 22 in the axial direction.

[0046] It is worth mentioning that, through the inclined first end face 2141, the axial dimension of the flange part 214 near the axis is larger, which is conducive to ensuring the structural strength of the flange part 214, while the axial dimension of the flange part 214 away from the axis is smaller, which is conducive to increasing the axial dimension of the outer peripheral surface of the extension section 222, so as to facilitate the setting of the gate 223. That is to say, when insert molding is used to form the outer component 22, the axial dimension of the extension section 222 near the axis is smaller, while the axial dimension away from the axis is larger, which is conducive to setting the gate 223 on the outer peripheral surface of the extension section 222, through the second end face 2221 matched with the first end face 2141. In addition, the radial wall thickness of the extension section 222 gradually increases from one end close to the flange part 214 to the end away from the flange part 214, that is, the flow channel during insert molding gradually increases, which is conducive to mold filling and pressure holding, so that the outer component 22 formed by insert molding is fuller, and further conducive to improving the strength of the outer component 22, especially the outer tooth part 221.

[0047] In a specific embodiment, the second end face 2221 is located at the inner periphery of the extension section 222, that is, in the radial direction, the second end face 2221 and the outer peripheral surface of the extension section 222 are arranged opposite to each other, and at the same time, the second end face 2221 and the outer tooth portion 221 are prevented from overlapping in the axial direction, thereby facilitating the second end face 2221 from affecting the structural strength of the outer tooth portion 221. It is understandable that when the second end face 2221 and the outer tooth portion 221 overlap in the axial direction, the radial wall thickness between the second end face 2221 and the root circle of the outer tooth portion 221 will be reduced, thereby reducing the structural strength of the outer tooth portion 221.

[0048] In some embodiments, Figure 8 As shown, the double-sided taper of the first end surface 2141 is denoted as α, 80°≤α≤140°, so that the transition of the axial dimension of the flange portion 214 from the axial dimension close to the axis to the axial dimension away from the axis is more reasonable, which can ensure the structural strength of the flange portion 214 and help reduce the overall axial dimension of the flange portion 214 and the outer member 22. Preferably, 100°≤α≤120°

[0049] In some embodiments, Fig. 9 As shown, the length of the outer peripheral surface of the flange portion 214 along the axial direction is denoted as L F , 0.1mm≤L F ≤1mm, so that the edge of the flange portion 214 is not too thin and the strength is not too low, and it is also helpful to reduce the axial size of the flange portion 214, thereby making the structure of the split nut gear assembly 2 more compact. Preferably, 0.2mm≤L F ≤0.8mm.

[0050] In some embodiments, the outer tooth portion 221 is a semi-annular worm gear tooth or annular worm gear tooth, so that the tooth surface of the outer tooth portion 221 and the worm 3 are meshed in line contact, which is beneficial to improve the bearing capacity.

[0051] A gear box 1, such as Figure 1-Figure 3 As shown, it includes: a split nut gear assembly 2, a worm 3 and a housing 6, wherein the worm 3 is suitable for engaging with the outer tooth portion 221 of the outer component 22 of the split nut gear assembly 2 to drive the split nut gear assembly 2 to rotate; the housing 6 is used to accommodate the split nut gear assembly 2 and the worm 3 in a relatively rotatable manner.

[0052] That is to say, the housing 6 can accommodate and support the worm 3 and the split nut gear assembly 2, so that the worm 3 can mesh with the split nut gear assembly 2 to realize transmission. Specifically, the worm 3 is connected to the driving member and rotates under the action of the driving member. Further, the worm 3 meshes with the outer tooth portion 221 on the outer member 22 of the split nut gear assembly 2, so that the worm 3 can drive the outer member 22 to rotate, and the outer member 22 will drive the inner member 21 to rotate together. Furthermore, the inner periphery of the inner member 21 has an inner tooth portion 211 that penetrates along the axial direction, and the inner tooth portion 211 is used to cooperate with the screw, and then under the action of the driving member, the gear box 1 can move relative to the screw.

[0053] In some embodiments, the inner component 21 further includes a journal 215 at both ends, and the flange 214 and the first matching portion 212 are located between the two journals 215; the gearbox 1 further includes a collar 4, which is suitable for being sleeved on the journal 215, and the collar 4 and the flange 214 are located on both sides of the outer component 22 along the axial direction, that is, the collar 4 is arranged on the side of the outer component 22 away from the flange 214. Further, the gearbox 1 further includes a sleeve 5, which is suitable for being sleeved on the journal 215 to support the split nut gear assembly 2 to rotate relative to the housing 6.

[0054] In some embodiments, the gearbox 1 also includes a shock absorber 7, which is installed at the opposite ends of the outer shell 6 along the axial direction of the split nut gear assembly 2. When the gearbox 1 moves to the end of the stroke, the shock absorber 7 can play a role in buffering, shock absorption and noise reduction, which is beneficial to reduce the risk of damage to the gearbox 1 due to impact, further extend the service life of the gearbox 1, and at the same time help to improve the comfort of the car seat.

[0055] The above describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions only describe the principles of the present invention. The present invention may be subject to various changes and improvements without departing from the spirit and scope of the present invention. These changes and improvements fall within the scope of the present invention to be protected. The scope of protection claimed by the present invention is defined by the attached claims and their equivalents.

Claims

1. A split nut gear assembly, characterized in that: include: An outer member and an inner member, wherein the outer member is arranged on the outer circumference side of the inner member and is suitable for rotating synchronously with the inner member, the outer circumference of the outer member has an outer tooth portion, and the inner circumference of the inner member has an inner tooth portion.

2. The split nut gear assembly according to claim 1, characterized in that: The middle area of ​​the outer circumference of the inner component has a plurality of first matching parts distributed along the circumference; the inner circumference of the outer component has a plurality of second gaps distributed along the circumference, and the first matching parts are suitable for engaging with the second gaps to enable the outer component and the inner component to rotate together.

3. The split nut gear assembly according to claim 2, characterized in that: The length of the second gap along the axial direction is L2, and the length of the outer part along the axial direction is L W , satisfying: L2<L W .

4. The split nut gear assembly according to claim 1, characterized in that: The outer peripheral side of the inner component further has a flange portion protruding in the radial direction, and the end surface of the outer component is suitable for abutting against the flange portion in the axial direction.

5. The split nut gear assembly according to claim 4, characterized in that: The flange portion has a first end face on the side facing the outer component, and the first end face is a conical surface, which gradually tilts outward from one end of the flange portion facing the outer component to the end away from the outer component. The outer component has a second end face on the side facing the flange portion, and the second end face is suitable for fitting with the first end face.

6. The split nut gear assembly according to claim 5, characterized in that: The double-sided taper of the first end surface is denoted as α, 80°≤α≤140°.

7. The split nut gear assembly according to claim 4, characterized in that: The axial length of the outer peripheral surface of the flange portion is denoted as L, and 0.1 mm≤L≤1 mm.

8. The split nut gear assembly according to claim 1, characterized in that: The external tooth portion is a semi-annular worm gear tooth or annular worm gear tooth.

9. The split nut gear assembly according to any one of claims 1 to 8, characterized in that: The outer component is formed on the outer periphery of the inner component by an insert molding process.

10. A gear box, characterized in that: include: The split nut gear assembly as described in any one of claims 1 to 9; A worm gear, adapted to mesh with the outer teeth of the split nut gear assembly to drive the split nut gear assembly to rotate; The housing is used to relatively rotatably accommodate the split nut gear assembly and the worm.

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