Propeller shaft for vehicle

A propeller shaft for a vehicle in which a tube yoke is connected to a main tube via an adapter and tapered splines are formed at the contact regions between a tube yoke and the main tube to transmit the power output from a transmission to a rear wheel. The tube yoke and the main tube are displaced relative to each other at the tapered splines to break the adapter. The tube yoke and the main tube are thus separated from each other by virtue of the breakage of the adapter.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims under 35 U.S.C. § 119(a) the benefit of priority to Korean Patent Application No. 10-2020-0048387 filed on Apr. 22, 2020, the entire contents of which are incorporated herein by reference.

BACKGROUND

(a) Technical Field

The present disclosure relates to a propeller shaft for a vehicle, and more particularly, to a propeller shaft for a vehicle in which a tube yoke and a main tube are connected to each other via an adapter while being in contact with each other through face splines thereof to improve performance for absorbing impact energy.

(b) Background Art

The recent trend is to extensively develop high-performance vehicles having excellent traveling ability. Most of such high-performance vehicles adopt rear-wheel drive to improve handling and operation performance. For a rear-wheel drive system, a propeller shaft for transmitting power from a transmission to a rear-wheel drive shaft is inevitably required, and, in addition to the rear-wheel drive or high-performance vehicles, a propeller shaft for transmitting power to a rear wheel is also used in a vehicle in which four-wheel drive is optionally applied to a fundamentally front-wheel-drive system for stable traveling on rough roads.

Since the propeller shaft is subjected to strong rotational force and torsion during power transmission, the propeller shaft must be made of a material capable of enduring the strong rotational force and torsion. Particularly, since the propeller shaft extends in the longitudinal direction of a vehicle body, the propeller shaft must be configured to absorb impact energy while the length thereof is shortened to reduce injury of a passenger in the event of a collision of the vehicle.

An assembly structure and a structure for absorbing impact of a conventional propeller shaft will now be described.FIG. 1of the accompanying drawings illustrates a conventional propeller shaft for a vehicle according to the prior art. As illustrated inFIG. 1, the conventional propeller shaft10includes a tube yoke11connected to an output side of a transmission, a front main tube12connected to a rear portion of the tube yoke11, a rear main tube14connected to an input side of a differential gear unit for distributing power to a rear-wheel drive shaft, and a constant-velocity joint (CVJ)13disposed between the front main tube12and the rear main tube14and connected thereto.

For reference, the constant-velocity joint is applied to ensure the power-transmission function of the propeller shaft and to increase the support stiffness of an intermediate portion of the propeller shaft when the length of the vehicle is increased. The propeller shaft10may be greatly deformed, and may thus cause breakage of peripheral components or injury of passengers, due to impact energy applied in the longitudinal direction of the vehicle in the event of a collision of the vehicle. Accordingly, the propeller shaft10has a structure capable of absorbing impact energy in the event of a collision.

As illustrated inFIG. 1, the front main tube12, for example, has a front small-diameter portion12-1and a rear large-diameter portion12-2that are integrally connected to each other. Consequently, when the impact energy caused by a collision is transmitted to the front main tube12, it is possible to absorb the impact energy while the small-diameter portion12-1is pushed into the large-diameter portion12-2.

Furthermore, when the impact energy caused by a collision is transmitted to the front main tube12, it is possible to absorb the impact energy while the connecting portion between the small-diameter portion12-1and the large-diameter portion12-2is bent. However, when the front main tube12includes the small-diameter portion12-1and the large-diameter portion12-2, strength required for power transmission, which is the main function of the front main tube12, decreases due to the decrease in the outside diameter of the small-diameter portion12-1.

Although it is possible to prevent the decrease in strength required for power transmission by increasing the overall diameter of the front main tube12including the small-diameter portion12-1and the large-diameter portion12-2, disadvantageous layout and excessively increased weight are caused, and thus the front main tube12is not efficiently subjected to compressive deformation.

In addition, since the impact energy caused by a vehicle collision is not correctly transmitted in the longitudinal direction of the front main tube12even when the front main tube12includes the small-diameter portion12-1and the large-diameter portion12-2, the small-diameter portion12-1may not be substantially pushed into the large-diameter portion12-2, and the front main tube12may strike the floor of the vehicle body while being bent, thereby increasing damage to the vehicle and injury to passengers in the vehicle.

Furthermore, since the connecting portion between the tube yoke11and the front main tube12, that is, the connecting portion between the rear end of the tube yoke11and the front end of the small-diameter portion12-1of the front main tube12, is integrally formed through friction welding (F), as illustrated inFIG. 1, the tube yoke11and the front main tube12are not absolutely separated from each other by the impact energy caused by the collision of the vehicle, and thus, the connecting portion between the tube yoke11and the front main tube12absorbs the impact energy is not obtained.

Additionally, a structure for absorbing impact energy is also applied to the constant-velocity joint13. For example, it is possible to absorb impact energy by forming a partition wall (not shown) in the constant-velocity joint13, which is capable of being collapsed by the impact energy caused by a vehicle collision. However, since only the partition wall in the constant-velocity joint14is collapsed by the impact energy caused by the collision of the vehicle, and separation and a deformation amount of individual components of the constant-velocity joint are restricted, an effect of absorbing the impact energy becomes less effective.

SUMMARY

The present disclosure provides a propeller shaft for a vehicle, in which a tube yoke may be connected to a main tube via an adapter and tapered splines may be formed at the contact regions between a tube yoke and the main tube to more easily transmit the power output from a transmission to a rear wheel, and in which the tube yoke and the main tube may be displaced relative to each other at the tapered splines to break the adapter, with the result that the tube yoke and the main tube may be separated from each other by virtue of the breakage of the adapter to efficiently absorb impact energy.

In one aspect, the present disclosure provides a propeller shaft for a vehicle that may include an adapter, which is coupled at a front end thereof to an inner surface of a tube yoke and at a rear end thereof to an inner surface of a main tube and which has a breakage-inducing notch formed at a predetermined location between the front end and the rear end of the adapter, first tapered splines, which are formed at a rear end of the tube yoke, and second tapered splines, which are formed at a front end of the main tube and are alternately engaged with the first tapered splines to transmit power. In particular, breakage occurs at the breakage-inducing notch due to the striking force that is generated when the first tapered splines of the tube yoke are displaced relative to the second tapered splines of the main tube by the impact energy caused by a vehicle collision.

In an exemplary embodiment, the inner surface of the tube yoke may include a female threaded portion, and the front end of the adapter may include a male threaded portion to be threadedly engaged with the female threaded portion of the tube yoke. In addition, the inner surface of the main tube may include a locking groove, and the rear end of the adapter may include a plurality of elastic clips to be coupled to the locking groove. Each of rear ends of the plurality of elastic clips may be integrally formed with a hook, which is bent outwards to be fitted into the locking groove.

The propeller shaft may further include an O-ring, which is fitted into the breakage-inducing notch in the adapter to block infiltration of foreign substances. The rear surfaces of the first tapered splines and the front surfaces of the second tapered splines may have tapered surfaces, which are in oblique surface contact with each other.

In particular, the first tapered splines may include a plurality of first teeth and a plurality of first tooth grooves, which are circumferentially and alternately arranged, and a rear surface of each of the plurality of first teeth and the plurality of first tooth grooves may be formed into a first tapered surface, which is inclined outwards from the inner surface to an outer surface of the tube yoke. The second tapered splines may include a plurality of second teeth and a plurality of second tooth grooves, which are circumferentially and alternately arranged, and a front surface of each of the plurality of second teeth and the plurality of second tooth grooves may be formed into a second tapered surface, which is inclined inwards from an outer surface to the inner surface of the main tube.

In another exemplary embodiment, the first tapered splines may include a plurality of first teeth and a plurality of first tooth grooves, which are circumferentially and alternately arranged, and a rear surface of each of the plurality of first teeth and the plurality of first tooth grooves may be formed into a first tapered surface, which is inclined inwards from an outer surface of the tube yoke to the inner surface thereof. The second tapered splines may include a plurality of second teeth and a plurality of second tooth grooves, which are circumferentially and alternately arranged, and a front surface of each of the plurality of second teeth and the plurality of second tooth grooves may be formed into a second tapered surface, which is inclined outwards from the inner surface to the outer surface of the main tube.

It should be understood that the appended drawings are not necessarily to scale, presenting a somewhat simplified representation of various exemplary features illustrative of the basic principles of the disclosure. The specific design features of the present disclosure as disclosed herein, including, for example, specific dimensions, orientations, locations, and shapes will be determined in part by the particular intended application and use environment. In the figures, the reference numbers refer to the same or equivalent parts of the present disclosure throughout the several figures of the drawing.

DETAILED DESCRIPTION

Hereinafter, reference will now be made in detail to various exemplary embodiments of the present disclosure, examples of which are illustrated in the accompanying drawings and described below. While the disclosure will be described in conjunction with exemplary embodiments, it will be understood that the present description is not intended to limit the disclosure to those exemplary embodiments. On the contrary, the disclosure is intended to cover not only the exemplary embodiments, but also various alternatives, modifications, equivalents and other exemplary embodiments, which may be included within the spirit and scope of the disclosure as defined by the appended claims.

Hereinafter, preferred embodiments of the present disclosure will be described in detail with reference to the accompanying drawings.FIG. 2Ais an exploded perspective view of a propeller shaft for a vehicle according to an exemplary embodiment of the present disclosure, which is partially illustrated in section.FIGS. 3, 4, and 5Aare perspective views illustrating an assembly procedure of the propeller shaft for a vehicle according to the exemplary embodiment of the present disclosure, which are partially illustrated in section. In the drawings, reference numeral “100” denotes an adapter.

The adapter100may connect a tube yoke110, which is connected to the output side of a transmission, among components of the propeller, to a main tube120, which extends the input side of a differential gear unit and is oriented in the longitudinal direction of the vehicle. In other words, the adapter100may have a cylindrical shape, the front end of which may be coupled to the inner surface of the tube yoke110and the rear end of which may be coupled to the inner surface of the main tube120to connect the tube yoke110to the main tube120.

Accordingly, the adapter100may include at the front end thereof a male threaded portion101and at the rear end thereof a plurality of elastic clips103, a breakage-inducing notch102being formed between the front end and the rear end thereof, as illustrated inFIGS. 1A and 1B. More specifically, the male threaded portion101may be formed in the outer surface of the front end of the adapter100, and the plurality of elastic clips103may be circumferentially arranged at regular intervals at the rear end of the adapter10and project rearwards. The breakage-inducing notch102may be formed in the outer surface of the adapter100between the front end and the rear end thereof so as to have a “V”-shaped section.

Each of the elastic clips103may be integrally provided at the rear end thereof with a hook104, which is bent outwards for coupling with the main tube120. In particular, the inner surface of the tube yoke110may be formed with a female threaded portion111, with which the male threaded portion101of the adapter100may be threadedly engaged, and the inner surface of the main tube120may be formed with a locking groove121, into which the hooks104formed on the elastic clips103of the adapter100may be fitted.

Accordingly, when the male threaded portion101of the adapter100is threadedly engaged with the female threaded portion of the tube yoke110and the main tube120is pushed toward the rear end of the adapter100, as illustrated inFIGS. 3 and 4, the elastic clips103may be fitted into the main tube120while being bent inwards, and then the hooks104of the elastic clips103may be moved outwards by virtue of the elastic restoring force and may be locked in the locking groove121, with the result that the tube yoke110is integrally connected to the main tube via the adapter100, as illustrated inFIGS. 5A and 5B.

Particularly, an O-ring105may be fitted into the breakage-inducing notch102before the tube yoke110is connected to the main tube120via the adapter100, to prevent foreign substances, moisture or the like from entering the tube yoke100and the main tube120. The tube yoke110may include at the rear end thereof first tapered splines130, and the main tube120may include at the front end thereof second tapered splines140, which are alternately engaged with the first tapered splines130and are in oblique surface contact with the second tapered splines140.

The rear surfaces of the first tapered splines130and the front surface of the second tapered splines140may have respective tapered surfaces and thus, the rear surfaces of the first tapered splines130and the front surface of the second tapered splines140may be in oblique surface contact with each other. Accordingly, when the first tapered splines130of the tube yoke110and the second tapered splines140of the main tube120are displaced relative to each other at the oblique surface contact region due to the impact energy caused by a vehicle collision, the first tapered splines130or the second tapered splines140strike the breakage-inducing notch102of the adapter100, and breakage occurs at the breakage-inducing notch102, thereby dividing the adapter100into two pieces.

In one exemplary embodiment for implementing this, the first tapered splines130may include a plurality of first teeth131and a plurality of first tooth grooves132, which are circumferentially and alternately arranged at the rear end of the tube yoke110, and the rear surface of each of the first teeth131. The first tooth grooves132may have a first tapered surface133, which is inclined outwards from the inner surface to the outer surface of the tube yoke110, as illustrated inFIG. 6. Furthermore, the second tapered splines140may include a plurality of second teeth141and a plurality of tooth grooves142, which are circumferentially and alternately arranged at the front end of the main tube120, and the front surface of each of the second teeth141. The second tooth grooves142may have a second tapered surface143, which is inclined inwards from the outer surface to the inner surface of the main tube120, as illustrated inFIG. 6.

Consequently, when the tube yoke110and the main tube120are connected to each other by the adapter100, the first teeth131of the first tapered splines130may be fitted into the second tooth grooves142in the second tapered splines140and engaged therewith, and the first teeth141of the second tapered splines140may be fitted into the first tooth grooves132in the first tape splines130and engaged therewith, whereby the first tapered surfaces133of the first tapered splines130are in oblique surface contact with the second tapered surfaces143of the second tapered splines140, as illustrated inFIG. 7. Since the first teeth131of the first tooth grooves132of the first tapered splines130are respectively engaged with the second tooth grooves142and the second teeth141of the second tapered splines140, the rotational force output from a transmission may be transmitted to a differential gear unit, which is configured to distribute the rotational force to a rear-wheel drive shaft, via the tube yoke110and the main tube120.

Meanwhile, when the impact energy caused by a vehicle collision is transmitted to the tube yoke110, since the first tapered surfaces133of the first tapered splines130are in oblique surface contact with the second tapered surfaces143of the second tapered splines140, the first tapered splines130of the tube yoke110may be displaced outwards while the second tapered splines140of the main tube120are displaced inwards, and thus, the first tapered splines130are displaced relative to the second tapered splines140, as indicated by the arrows inFIG. 8. The reference number I inFIG. 8indicates an impact direction in event of a collision. At the same time, the second tapered splines140may strike and push the breakage-inducing notch102of the adapter100while being displaced inwards, and thus breakage occurs at the breakage-inducing notch102, and thus, the front part and the rear part of the adapter100may be separated from each other.

Particularly, since the adapter100, which connects the tube yoke110to the main tube120, is divided into the front part and the rear part, the tube yoke110, which is threadedly coupled to the front end of the adapter100, and the main tube120, which is connected to the rear end of the adapter100by the elastic clips103, may be separated from each other. Additionally since the front part and the rear part of the adapter100are separated from each other and thus the tube yoke110and the main tube120are also separated from each other by the impact energy caused by a vehicle collision, it may be possible to efficiently absorb the impact energy caused by the vehicle collision.

Even when the impact energy caused by the vehicle collision is not correctly transmitted in the longitudinal direction of the propeller shaft, the first tapered splines130and the second tapered splines140may strike and break the notch102in the adapter100while being displaced relative to each other, and the tube yoke110and the main tube120may thus be reliably separated from each other to absorb the impact energy caused by the vehicle collision. Additionally, even when the first tapered surfaces133of the first tapered splines130and the second tapered surfaces143of the second tapered splines140are formed in a reverse manner, it may be possible to realize an effect of absorbing the impact energy.

In another exemplary embodiment for implementing the same, the first tapered splines130may include a plurality of first teeth131and a plurality of first tooth grooves132, which are circumferentially and alternately arranged at the rear end of the tube yoke110, and the rear surface of each of the first teeth131. The first tooth grooves132may be formed into a first tapered surface133, which is inclined inwards from the outer surface to the inner surface of the tube yoke110, as illustrated inFIGS. 9 and 10.

Furthermore, the second tapered splines140may include a plurality of second teeth141and a plurality of second tooth grooves142, which are circumferentially and alternately arranged at the front end of the main tube120, and the front surface of each of the second teeth141. The second tooth grooves142may be formed into a second tapered surface143, which is inclined outwards from the inner surface to the outer surface of the main tube120, as illustrated inFIGS. 9 and 10.

Accordingly, when the impact energy caused by the vehicle collision is transmitted to the tube yoke110, since the first tapered surfaces133of the first tapered splines130are in oblique surface contact with the second tapered surfaces143of the second tapered splines140, the first tapered splines130of the tube yoke110may be displaced inwards while the second tapered splines140of the main tube120are displaced outwards, thus displacing the first tapered splines130relative to the second tapered splines140, as indicated by the arrows inFIG. 11. At the same time, the first tapered splines130may strike and push the breakage-inducing notch102of the adapter100while being displaced inwards, and thus breakage occurs at the breakage-inducing notch102, thereby separating the front part and the rear part of the adapter100from each other. In particular, the tube yoke110, which is threadedly coupled to the front end of the adapter100, and the main tube120, which is connected to the rear end of the adapter100by means of the elastic clips103, may also be separated from each other. The reference number I inFIG. 11indicates an impact direction in event of a collision.

As described above, even when the first tapered surfaces133of the first tapered splines130and the second tapered surfaces143of the second tapered splines140are formed in a reverse manner, the front part and the rear part of the adapter100may be separated from each other and the tube yoke110and the main tube120may also be separated from each other by the impact energy caused by the vehicle collision, thereby making it possible to efficiently absorb the impact energy caused by the vehicle collision.

By virtue of the above-described constructions, the present disclosure offers the following effects.

First, since the tapered splines are formed at the contact portions between the tube yoke and the main tube, it may be possible to transmit the power output from a transmission to a rear wheel. Furthermore, since the tube yoke and the main tube may be displaced relative to each other to cause breakage at the notch in the adapter by the impact energy caused by a vehicle collision, the tube yoke and the main tube may be separated from each other by virtue of the breakage of the adapter, thereby efficiently absorbing the impact energy.

Second, even when the impact energy caused by a vehicle collision is incorrectly transmitted in the longitudinal direction of the propeller shaft, that is, regardless of the direction in which the impact energy is transmitted, the tube yoke and the main tube may be displaced relative to each other at the tapered splines to strike and break the notch in the adapter, and thus, the tube yoke and the main tube may be reliably separated from each other to absorb the impact energy caused by the vehicle collision.

Third, it may be possible to assemble the tube yoke with the main tube more easily using the adapter including a threaded portion and clips.

Fourth, since the O-ring is fitted into the notch in the adapter, it may be possible to prevent foreign substances from entering the propeller shaft and thus to ensure a watertight structure at normal times.