KR20220138678A - Stub shaft and shaft connection structure including the same - Google Patents

Abstract

The present invention relates to a stub shaft and a shaft connection structure including the same, and more particularly, to a shaft connection structure which provides excellent connection force between two shafts made of different materials. A stub shaft according to the present invention includes a connection part having screw threads formed on the outer circumferential surface thereof; and a joint part formed at one end of the connection part to have a larger diameter than the connection part and having teeth on the surface thereof.

Description

Stub shaft and shaft coupling structure including the same

The present invention relates to a stub shaft and a shaft coupling structure including the same, and more particularly, to a shaft coupling structure that provides excellent coupling force between two shafts made of different materials.

The vehicle's drivetrain is configured to transmit power from the engine to the drive wheels through a transmission. Since the shaft in the drive train must be able to withstand rotational force and strong torsional torque, steel has been conventionally applied as its material. However, in recent years, the application of composite materials such as alloys and carbon fibers is increasing in order to improve fuel efficiency or power transmission performance and to reduce weight.

When a composite material is used, a bond between the steel and the composite material, ie between dissimilar materials, is required. When bonding between dissimilar materials, there are several problems to be solved, such as securing bonding strength and eliminating noise generation.

For example, a carbon fiber reinforced plastic (CFRP) material is actually applied to a propeller shaft to which a steel material has been generally applied. As shown in Figures 1a to 1c, a serration (S) is applied to the coupling of the tube 810 made of CFRP and the stub shaft 830 made of steel in the CFRP propeller shaft 800 (Fig. see 2). The stub shaft 830 is press-fitted into the tube 810 through the serration S, and a torsional torque is transmitted between the dissimilar material coupling portions.

However, in this CFRP propeller shaft, the spline meshing structure within the joint between dissimilar materials causes joint noise. As the driving distance of the vehicle increases, the phenomenon of pressing each other's spline teeth in the spline meshing structure is repeated. At this time, backlash occurs at the spline coupling portion and causes noise when torque is applied (eg, accelerator pedal tip-in).

In the case of the CFRP drive shaft, which is currently under research and development, compared to the CFRP propeller shaft, the applied torque is larger, so the backlash becomes larger and the noise can be more severe.

Registered Patent Publication No. 10-2216918 (Registration Date: 2021.02.10)

The present invention has been devised to solve the above problems,

An object of the present invention is to provide a stub shaft capable of preventing backlash, which causes noise, and a shaft coupling structure including the same.

Another object of the present invention is to provide a stub shaft capable of contributing to weight reduction of a drive train and a shaft coupling structure including the same.

The object of the present invention is not limited to the object mentioned above, and other objects not mentioned are clearly understood by those of ordinary skill in the art to which the present invention belongs from the description below (hereinafter referred to as "those skilled in the art"). it could be

In order to achieve the object of the present invention as described above and perform the characteristic functions of the present invention to be described later, the features of the present invention are as follows.

A stub shaft according to some embodiments of the present invention includes a coupling portion having a thread formed on an outer circumferential surface; and a bonding portion formed at one end of the coupling portion with a larger diameter than the coupling portion, and including a tooth on the surface.

A shaft coupling structure according to some embodiments of the present invention includes: a hollow tube made of a first material; and a stub shaft respectively coupled to both ends of the tube and made of a second material different from the first material, wherein the stub shaft includes a thread formed on an outer circumferential surface, and is configured to be rotationally inserted into the tube a coupling part; and an abutment adjacent to the coupling portion, extending radially outward than the coupling portion, and contacting the tube.

According to the present invention, there is provided a stub shaft capable of preventing backlash, which is a cause of noise, and a shaft coupling structure including the same.

According to the present invention, a stub shaft capable of greatly contributing to weight reduction of a drive train and a shaft coupling structure including the same are provided.

The effects of the present invention are not limited to those described above, and other effects not mentioned will be clearly recognized by those skilled in the art from the following description.

1a shows a drive train of a vehicle;
Fig. 1b shows a partial cross-sectional view in the longitudinal direction of the vehicle shown in Fig. 1a;
Figure 1c is a partial enlarged view of the area indicated by the dotted line in Figure 1b,
2 is a view showing the serration of an exemplary stub shaft, and shows a coupling cross-sectional view between a tube made of a dissimilar material and a stub shaft;
3 shows a shaft coupling structure according to an embodiment of the present invention;
4 shows a coupling structure between a stub shaft and a tube according to an embodiment of the present invention;
5 shows a stub shaft according to an embodiment of the present invention;
6 shows a side view of a stub shaft according to an embodiment of the present invention;
7 shows a front view of a stub shaft in accordance with some embodiments of the present invention;
8 shows a front view of a stub shaft in accordance with some embodiments of the present invention;
9 is a partially enlarged view of FIG. 8;
10 shows a drive shaft according to an embodiment of the present invention;
11 shows a mounting method of the stub shaft at each position of the drive shaft of FIG.
12A-12D show front views of each stub shaft at each position shown in FIG. 11 .

Specific structural or functional descriptions presented in the embodiments of the present invention are only exemplified for the purpose of describing embodiments according to the concept of the present invention, and the embodiments according to the concept of the present invention may be implemented in various forms. In addition, it should not be construed as being limited to the embodiments described herein, and should be understood to include all modifications, equivalents, and substitutes included in the spirit and scope of the present invention.

Meanwhile, in the present invention, terms such as first and/or second may be used to describe various components, but the components are not limited to the above terms. The above terms are used only for the purpose of distinguishing one component from other components, for example, within the scope not departing from the scope of the rights according to the concept of the present invention, the first component may be named as the second component, Similarly, the second component may also be referred to as the first component.

When a component is referred to as being “connected” or “connected” to another component, it should be understood that it may be directly connected or connected to the other component, but other components may exist in between. something to do. On the other hand, when an element is referred to as being “directly connected” or “in direct contact with” another element, it should be understood that no other element is present in the middle. Other expressions for describing the relationship between elements, that is, expressions such as "between" and "immediately between" or "adjacent to" and "directly adjacent to", should be interpreted similarly.

Like reference numerals refer to like elements throughout. Meanwhile, the terms used herein are for the purpose of describing the embodiments and are not intended to limit the present invention. In this specification, the singular form also includes the plural form unless specifically stated in the phrase. As used herein, “comprises” and/or “comprising” means that the stated component, step, operation and/or element is the presence of one or more other components, steps, operations and/or elements. or addition is not excluded.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

3 and 4 , the shaft coupling structure according to the present invention includes a hollow tube 100 and a stub shaft 200 .

The tube 100 is included in a drive train of a vehicle through coupling with the stub shaft 200 , and may be applied as a propeller shaft or a drive shaft.

The tube 100 is configured to have a larger diameter than the stub shaft 200 , and a part of the stub shaft 200 is inserted into the hollow of the tube 100 .

The tube 100 and the stub shaft 200 are made of different materials. As a non-limiting example, the tube 100 may be made of a composite material or a CFRP material, and the stub shaft 200 may be made of metal or steel. As will be described in detail below, according to the present invention, it is possible to prevent backlash by forming a strong coupling structure between the tube 100 and the stub shaft 200 even though it is a combination between different materials, and ultimately to block the occurrence of noise. .

As shown in FIG. 5 , the stub shaft 200 has a cylindrical shape as a whole, and according to an embodiment of the present invention, the stub shaft 200 includes a coupling part 220 and a joint part 240 .

The coupling part 220 is a part directly connected to the tube 100 . The coupling part 220 is inserted into the hollow of the tube 100, and more specifically, is inserted and coupled into the hollow by rotation. To this end, according to the embodiment of the present invention, the coupling portion 220 includes a screw thread 222 on the outer circumferential surface. According to an embodiment of the present invention, the screw thread 222 may be a right-hand thread or a left-hand thread, and the direction may be set in consideration of the relative rotation direction during mounting. This will be described later.

The coupling part 220 may be tapered so that its diameter decreases toward the end of the stub shaft 200 . Due to the tapered shape of the coupling part 220 , when the stub shaft 200 is inserted into the tube 100 , it may be more easily aligned.

The junction 240 is adjacent to the coupler 220 . That is, the junction 240 extends from the coupler 220 , but has a larger diameter than the coupler 220 . Due to this, the junction 240 functions as a stopper that prevents the tube 100 from moving any more when the tube 100 and the stub shaft 200 are coupled. The end of the tube 100 is in direct contact with the junction 240 , and as the rotational insertion of the stub shaft 200 proceeds, the tube 100 digs into the junction 240 . Accordingly, since the tube 100 and the stub shaft 200 are coupled to each other and the rotation is locked, the occurrence of backlash can be fundamentally eliminated.

The joint portion 240 has a predetermined thickness in the axial direction of the stub shaft 200 , and includes an opposing surface 242 , which is a side facing the joint portion 220 . The opposing surface 242 corresponds to a portion extending radially outward from the outer periphery of the coupling portion 220 .

As shown in FIG. 6 , the surface of the abutment 240 or the surface of the opposing surface 242 may include teeth, and the teeth may include a plurality of teeth 244 . Teeth are provided on at least a portion, preferably all, of the opposing surface 242 .

Teeth 244 are provided on the opposing surface 242 along the circumferential direction of the joint portion 240, and each tooth 244 is continuously disposed to form a tooth. That is, each tooth 244 extends a certain distance along the opposing surface 242 and protrudes toward the coupling portion 220 while extending in the circumferential direction from the opposing surface 242 while having a progressively larger protrusion length. That is, each tooth 244 includes a tip portion 246 that most protrudes outwardly from the abutment portion 240 .

According to some embodiments of the present invention, the teeth are straight or curved. The straight or curved tooth means the shape of the tip portion 246 observed when the tube 100 is coupled to the stub shaft 200 when the stub shaft 200 is viewed from the tube 100 side. Referring to FIG. 7 , the straight line means that the tip portion 246a, which is the most protruding portion from each tooth 244 toward the coupling portion 220, is straight along the radial direction. Referring to FIG. 8 , the curved shape means that the tip portion 246b forms a curve while extending in the radial direction.

In the case of the straight type, when compared to the curved type, when the end of the tube 100 and the stub shaft 200 are combined, the straight teeth 244 or the tip portion 246a penetrates the end of the tube 100 and the reverse torque. Although the robustness against annealing is relatively small, there is an advantage in that it is easy to process. In the case of the curved type, the processing is difficult compared to the straight type, but the teeth 244 or the tip portion 246b has excellent properties of digging into the end of the tube 100 and has excellent robustness against loosening during reverse torque.

According to the embodiment of the present invention, in the curved shape, the tip portion 246b of each tooth 244 is convex toward the neighboring tooth 244 . According to some embodiments, each tooth 244 is formed convex toward the right neighboring tooth 244 . According to some other embodiments, each tooth 244 is formed convex toward the left neighboring tooth 244 . The direction of the teeth 244 may be set in consideration of the relative rotation direction during mounting, like the direction of the screw thread 222 .

Although the driving direction of the vehicle is the main torque direction, an anti-loosening structure is required in case reverse torque is applied due to reverse torque generated by reverse or regenerative braking. To this end, according to the present invention, teeth for preventing loosening during reverse torque are applied to the joint portion 240 of the stub shaft 200 . That is, the tooth inclination angle is different for each torque direction. As shown in FIG. 9 , the direction in which the stub shaft 200 is rotated and inserted has a small tooth inclination angle, so that assembly is easy. However, in the direction opposite to the rotational insertion direction, the inclination angle is large, so that loosening can be prevented.

Also, according to the present invention, as described above, the direction of the screw thread 222 may be set in consideration of the driving direction of the vehicle, that is, the constant torque direction N of the transmission T. 10 shows drive shafts mounted on the left and right sides of the transmission T as the center. The direction indicated by the rotating arrow means the constant torque direction (N). 11 is a simplified view of the drive shaft of FIG. 10. In order from the left, the stub shaft on the left wheel (LHW) side is denoted by reference numeral 200c, the stub shaft on the left side of the transmission T is denoted by reference numeral 200a, and the transmission T ) The stub shaft on the right is denoted by reference numeral 200b, and the stub shaft on the right wheel (RHW) side is denoted by reference numeral 200d. 12A to 12D are views illustrating the respective stub shafts 200a, 200b, 200c, and 200d as viewed from the tube 100 side.

10 and 11, the stub shafts 200a and 200b on the left and right sides of the transmission T are rotated and assembled in the same direction as the constant torque direction N to be inserted (see FIGS. 12a and 12b, respectively). . When inserted in this way, the robustness can be maintained because the thread is placed in a direction in which the screw thread is further locked when the constant torque is frequently applied. At this time, the thread 222 of the stub shaft 200a on the left side of the transmission T becomes a right-hand thread, and the thread 222 of the stub shaft 200b on the right side of the transmission T becomes a left-hand thread.

Conversely, the stub shafts 200c and 200d on the left wheel (LHW) and right wheel (RHW) side are forward torque transmitted through the tube 100, so that the thread direction is formed to coincide with the forward torque reverse direction (R) (Fig. 12c and 12d). At this time, the thread 222 of the stub shaft 200c on the left wheel LHW side becomes a right-hand thread, and the thread 222 of the stub shaft 200d on the right wheel RHW side becomes a left-hand thread.

According to the present invention, the tube 100 and the stub shaft 200 may be coupled through the following process.

First, the tube 100 is fixed. It is inserted and coupled to the tube 100 while rotating the stub shaft 200 through the thread 222 machined in the coupling portion 220 of the stub shaft 200 . Here, the processing of the thread corresponding to the thread 222 of the coupling part 220 is not required inside the tube 100 . CFRP material is softer than steel material, so that when rotating the tube 100 is inserted while grinding. Thereby, the thread 222 is naturally coupled to the tube 100 without backlash.

When the coupling part 220 is inserted to the end of the tube 100 , the joint 240 or the opposite surface 242 of the stub shaft 200 comes into contact with the end of the tube 100 . In this state, when the stub shaft 200 is continuously rotated and inserted, the coupling is completed in a state in which the junction part 240 digs into the tube 100 , and the stub shaft 200 is in a rotationally locked state.

The present invention can implement different materials not only on the propeller shaft but also on the drive shaft. The drive shaft has twice the amount of torsional torque compared to the propeller shaft, so it is more vulnerable to noise caused by backlash. Since backlash can be blocked through the coupling structure according to the present invention, drive shafts made of different materials can be implemented, and thus, it can contribute to weight reduction of the drive train.

The present invention described above is not limited by the above-described embodiments and the accompanying drawings, and it is common in the technical field to which the present invention pertains that various substitutions, modifications and changes are possible within the scope without departing from the technical spirit of the present invention. It will be clear to those who have the knowledge of

100: tube 200: stub shaft
220: coupling portion 222: thread
240: junction 242: opposing surface
244: teeth 246, 246a, 246b: tip portion
T: Transmission LHW: Left wheel
RHW: Right wheel N: Forward torque direction
R: forward torque reverse direction

Claims (15)

a coupling portion having a screw thread formed on the outer circumferential surface; and
a bonding portion formed at one end of the coupling portion with a larger diameter than the coupling portion, and including a tooth on the surface;
A stub shaft comprising a. The stub shaft according to claim 1, wherein the coupling portion is tapered in a direction away from the abutment portion. The stub shaft according to claim 1, wherein the teeth are formed on an opposite surface of the abutment that is a side facing the engaging portion. The method according to claim 3, wherein the teeth include a plurality of teeth formed spaced apart in a circumferential direction of the joint portion,
Each tooth extends a certain distance in the circumferential direction of the joint portion, and the stub shaft gradually protrudes from the opposite surface toward the engaging portion along the circumferential direction. The stub shaft according to claim 4, wherein the tip of each tooth protruding longest from the joint portion toward the engaging portion is in the form of a straight line in the radial direction. The stub shaft according to claim 4, wherein the tip of each tooth protruding longest from the joint portion toward the coupling portion is convex toward the neighboring teeth. The stub shaft according to claim 6, wherein the thread is formed as a left-hand thread or a right-hand thread based on the orientation of the stub shaft and the direction of torque applied to the stub shaft. The stub shaft of claim 6 , wherein the teeth are configured to be convex toward a direction of torque applied to the stub shaft. a hollow tube made of a first material; and
and a stub shaft coupled to both ends of the tube and made of a second material different from the first material,
The stub shaft is
a coupling portion comprising a thread formed on an outer circumferential surface and configured to be rotationally inserted into the tube; and
and an abutment adjacent to the coupling portion, extending radially outward than the coupling portion, and in contact with the tube. The shaft coupling structure according to claim 9, wherein the first material is a carbon fiber reinforced plastic, and the second material is a steel material. The shaft coupling structure according to claim 9, wherein the abutment portion includes a plurality of teeth disposed along the circumferential direction, which gradually protrude from the surface to the coupling portion on a side surface in contact with the tube. The shaft coupling structure according to claim 11, wherein the teeth are convex toward neighboring teeth. 13. The method of claim 12,
a transmission-side stub shaft mounted on the transmission side of the vehicle to receive rotational force from the transmission;
a tube having one end coupled to the transmission-side stub shaft;
The other end of the tube is coupled, and the shaft coupling structure includes a wheel-side stub shaft mounted on a left wheel or a right wheel side. The shaft coupling structure according to claim 13, wherein a thread of the transmission-side stub shaft is configured to have a forward thread direction in a rotational direction of the transmission. The shaft coupling structure according to claim 13, wherein a thread of the wheel-side stub shaft is configured to have a threaded direction advancing in a direction opposite to a rotational direction of the transmission.

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