Patent Description:
The present disclosure has been derived from a study conducted as part of Industrial Technology Innovation Project of Korea Evaluation Institute of Industrial Technology of the Ministry of Trade, Industry and Energy [Project Number: <NUM>, Project Name: Development of CFRP Knuckle using Discontinuous Carbon Fiber and Hot Press Process].

Recently, as environmental pollution due to exhaust gas emission becomes serious, various efforts have been made in weight reduction of vehicle parts to achieve improvement in fuel efficiency and reduction in exhaust gas emission.

For example, a knuckle constituting a steering device of a vehicle has been conventionally manufactured using steel material, such as chromium-molybdenum alloy steel, or aluminum material. However, metal material has a problem of a heavy weight.

Accordingly, in response to the weight reduction trend of vehicles, it is required to manufacture a knuckle using lightweight material instead of metal material.

<CIT> and <CIT> each show a vehicle knuckle including a knuckle body made of carbon fiber reinforced plastics (CFRP) and having an assembly hole; and a wheel bearing bushing inserted and joined into the assembly hole of the knuckle body to allow a wheel bearing to be mounted. The wheel bearing bushing includes: a first bushing made of CFRP; a second bushing made of CFRP to be engaged with and joined to the outer circumference of the first bushing; and a third bushing to be engaged with and joined to the inner circumference of the first bushing.

<CIT> shows an overall knuckle comprising a laminated body which is formed by laminating a plurality of random mats, and interposing a uni directional sheet between the random mats.

In response to the weight reduction trend of vehicles, the present disclosure is directed to providing a practically applicable vehicle knuckle comprising a knuckle body which is manufactured using carbon chips, wherein the carbon chip is a new material, which is lighter than metal material and is capable of having the substantially same mechanical properties as metal material.

In particular, the present disclosure is directed to providing a vehicle knuckle in which strength of a portion of a knuckle body for installing or connecting other parts is reinforced with a bushing.

Further, the present disclosure is directed to providing a vehicle knuckle in which a bushing coupled to a knuckle body is firmly coupled without being separated.

The problem is solved by a vehicle knuckle according to claim <NUM> as well as by a manufacturing method according to claim <NUM>.

The vehicle knuckle according to the present disclosure comprises a bushing formed of metal material; and a knuckle body formed of carbon fiber reinforcement plastic material and having at least one bushing hole to which a ball joint is couplable, wherein at least a portion of the bushing may be coupled to the bushing hole of the knuckle body through press-fit.

The knuckle body is formed by hot-press forming carbon chip material comprising carbon fiber reinforcement plastic material.

In one embodiment, the bushing may be made of steel or aluminum material.

In one embodiment, the bushing may comprise a cylinder portion, and at least one groove may be formed on an outer circumferential surface of the cylinder portion in a circumferential direction.

In one embodiment, at least one groove may be formed on an inner circumferential surface of the bushing hole of the knuckle body in a circumferential direction.

In one embodiment, an inner diameter of the bushing hole may be smaller than an outer diameter of the remaining portion of the cylinder portion of the bushing except for the groove, and a difference between the inner diameter of the bushing hole and the outer diameter of the remaining portion of the cylinder portion of the bushing except for the groove may be <NUM> to <NUM>.

In one embodiment, an inner diameter of the bushing hole except for the groove may be smaller than an outer diameter of the cylinder portion of the bushing, and a difference between the inner diameter of the bushing hole except for the groove and the outer diameter of the cylinder portion of the bushing may be <NUM> to <NUM>.

In one embodiment, the bushing may further comprise a flange portion formed to extend from one end portion of the cylinder portion in a radially outward direction.

In one embodiment, a width of the groove formed in the busing may be greater than or equal to <NUM> and may be less than or equal to <NUM>/<NUM> of an entire length of the bushing.

In one embodiment, a bonding agent may be provided at least in the groove between the knuckle body and the bushing.

In one embodiment, the bonding agent may be an epoxy resin.

The axial length of the bushing except for the flange portion is smaller than an axial length of the bushing hole in a cross-section taken along an axial direction of the bushing.

The manufacturing method of a vehicle knuckle according to another aspect of the present disclosure comprises preparing a bushing formed of metal material; preparing a knuckle body formed of carbon fiber reinforcement plastic material and having at least one bushing hole; applying a bonding agent on an outer circumferential surface of the bushing; and coupling at least a portion of the bushing to the bushing hole of the knuckle body through press-fit, wherein an inner diameter of the bushing hole may be smaller than an outer diameter of the bushing.

The manufacturing method further comprises forming a through-hole in the bushing.

The preparing of the knuckle body comprises forming the knuckle body by hot-press forming carbon chip material comprising carbon fiber reinforcement plastic material.

In one embodiment, the preparing of the bushing may comprise manufacturing the bushing by machining steel or aluminum material.

In one embodiment, in the preparing of the knuckle body and the preparing of the bushing, the knuckle body and the bushing may be manufactured such that a difference between an inner diameter of the bushing hole and an outer diameter of the bushing is <NUM> to <NUM>.

In one embodiment, in the preparing of the bushing, at least one groove may be formed on an outer circumferential surface of the bushing in a circumferential direction.

In one embodiment, the preparing of the knuckle body may comprise filling a mold with carbon chip material; hot-press forming the carbon chip material filled in the mold; and separating a formed knuckle from the mold.

In one embodiment, the preparing of the bushing may comprise forming a recess at one end surface of the bushing, and the coupling of at least a portion of the bushing to the bushing hole of the knuckle body may comprise inserting a portion of a press device into the recess and aligning the bushing and the bushing hole of the knuckle body in an axial direction.

In accordance with a vehicle knuckle and a manufacturing method thereof according to various embodiments of the present disclosure, a lightweight knuckle manufactured using carbon chips can be practically provided.

Further, since a bushing for installing or connecting other parts is firmly coupled to a knuckle body, it is possible to stably install or connect the other parts to the knuckle body and to prevent a problem that the bushing is separated together with the other parts when the other parts are replaced.

The following drawings, which are incorporated herein, illustrate embodiments of the present disclosure and serve to provide a further understanding of the present disclosure together with the detailed descriptions of the present disclosure. Accordingly, it should be construed that the present disclosure is not limited to embodiments illustrated in the drawings.

Embodiments of the present disclosure are exemplified for the purpose of describing aspects of the present disclosure. The scope of the claims according to the present disclosure is not limited to the embodiments described below or to the detailed descriptions of these embodiments.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning commonly understood by those skilled in the art to which the present disclosure pertains. All terms used herein are selected for the purpose of more clearly describing the present disclosure and not limiting the scope of the present disclosure defined by appended claims.

Unless the phrase or sentence clearly indicates otherwise, terms "comprising," "including," " having," "taking," and the like used herein should be construed as openended terms encompassing the possibility of including other embodiments.

The singular form described herein may include the plural form unless the context clearly dictates otherwise, and this is equally applied to the singular form set forth in the claims.

Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. In the accompanying drawings, same reference numerals are assigned to same or corresponding components. Further, in the following descriptions of the embodiments, duplicate descriptions of same or corresponding components may be omitted. However, even though descriptions on a component are omitted, such a component is not intended to be excluded in any embodiment.

<FIG> and <FIG> illustrate a vehicle knuckle <NUM> according to one embodiment of the present disclosure. As shown in <FIG> and <FIG>, the vehicle knuckle <NUM> according to one embodiment of the present disclosure comprises a knuckle body <NUM> and bushings <NUM>, <NUM>, <NUM>, <NUM> and <NUM> coupled to the knuckle body <NUM>.

In order for weight reduction of the knuckle <NUM>, the knuckle body <NUM> may be manufactured using carbon chips.

The carbon chip is a chip-shaped material obtained by dividing carbon fiber reinforcement plastic film material into a predetermined size (e.g., a length ranging from <NUM> to <NUM> and a width ranging from <NUM> to <NUM>) so as to have mechanical strength and excellent productivity required for vehicle parts. The knuckle body <NUM> may be manufactured by filling a mold with the above-described carbon chips and then hot-press forming the carbon chips under high temperature and high pressure environment.

When manufacturing a knuckle using conventional carbon fiber reinforcement plastic films (continuous fiber), the carbon fiber reinforcement plastic films are cut according to a shape of the knuckle, the cut carbon fiber reinforcement plastic films are stacked according to orientation of fiber texture, and then the carbon fiber reinforcement plastic films are hot-press formed. However, such a manufacturing method has a problem that the productivity of the knuckle is degraded since the manufacturing processes of cutting and stacking the carbon fiber reinforcement plastic films are complicated and strength of the manufactured knuckle is degraded in a specific direction (e.g., a direction perpendicular to a stacking direction) due to the directional property of the fiber texture of the carbon fiber reinforcement plastic film.

On the contrast, when manufacturing a knuckle body using the carbon chips according to the present disclosure, the knuckle body may be manufactured to have light weight as compared with a conventional vehicle knuckle formed of metal material, while securing mechanical strength required to vehicle parts. Further, unlike a conventional case in which a knuckle is formed of carbon fiber reinforcement plastic films (continuous fiber), it is possible in the knuckle according to the present disclosure to remarkably enhance productivity since the knuckle body can be formed through only a simplified process of pouring the carbon chips of a required weight into a mold without cumbersome processes of cutting the carbon fiber reinforcement plastic films and stacking the cut carbon fiber reinforcement plastic films according to orientation of the fiber texture. In addition, the knuckle according to the present disclosure can solve a problem that strength is degraded in a specific direction due to the stacking of the films.

A hub bushing hole <NUM> may be formed to pass through a central portion of the knuckle body <NUM>, and a hub bushing <NUM> may be provided in the hub bushing hole <NUM> to support a wheel bearing device. A caliper bushing <NUM> may be coupled to the bushing hole <NUM>, and thus the knuckle <NUM> may be connected to a brake caliper. According to one embodiment of the present disclosure, when the knuckle body <NUM> is formed of carbon chips, the knuckle body <NUM> to which the bushings <NUM> and <NUM> are integrally coupled may be formed by hot-press forming the carbon chips in a state that the hub bushing <NUM> and the caliper bushing <NUM> are located in a mold.

The knuckle body <NUM> may further comprise at least one bushing hole <NUM>, <NUM> or <NUM>. <FIG> and <FIG> illustrate the knuckle <NUM> at a state in which the bushings <NUM>, <NUM> and <NUM> are coupled to the knuckle body <NUM>. In <FIG> and <FIG>, reference numerals <NUM>, <NUM> and <NUM> for bushing holes indicate positions of the bushing holes <NUM>, <NUM> and <NUM> formed according to one embodiment. The bushing holes <NUM>, <NUM> and <NUM> may be formed as cylindrical paths passing through the knuckle body <NUM>.

The bushings <NUM>, <NUM> and <NUM> may be coupled to the bushing holes <NUM>, <NUM> and <NUM> of the knuckle body <NUM>, and the knuckle body <NUM> may install or connect other parts through the bushings <NUM>, <NUM> and <NUM>. The bushing <NUM> may be coupled to the bushing hole <NUM> such that the knuckle <NUM> may be connected to a tie rod. The bushing <NUM> may be coupled to the bushing hole <NUM> such that the knuckle <NUM> may be connected to a lower control arm constituting a suspension. The bushing <NUM> may be coupled to the bushing hole <NUM> such that the knuckle may be connected to an upper control arm constituting the suspension.

<FIG> is a cross-sectional view illustrating only a portion of the knuckle body <NUM> in a cross-section taken along line II-II shown in <FIG>, and <FIG> is a cross-sectional view illustrating only the bushing <NUM> in a cross-section taken along line II-II shown in <FIG>. Hereinafter, the descriptions will be made based on the bushing hole <NUM> and the bushing <NUM>, but the same may be also applied to the other bushings <NUM> and <NUM> and the other bushing holes <NUM> and <NUM>.

The bushing <NUM> may be made of aluminum or steel material having strength that is larger than that of the knuckle body <NUM>. In the knuckle body <NUM> made of carbon chip material, portions at which other parts are installed or connected have a relatively high risk of abrasion or damage. In the knuckle body <NUM> according to one embodiment of the present disclosure, strength of the portions at which other parts are installed or connected is complemented with aluminum or steel material having strength that is larger than that of the carbon chip material, and thus it is possible to provide an effect which is capable of stably installing or connecting the other parts and increasing durability of the knuckle.

For example, <FIG> illustrates the bushing <NUM> according to one embodiment of the present disclosure. With reference to <FIG>, the bushing <NUM> may comprise a cylinder portion <NUM> and a flange portion <NUM> formed to extend from one end portion of the cylinder portion <NUM> in a radially outward direction. The cylinder portion <NUM> may be inserted into the bushing hole <NUM> of the knuckle body <NUM>, and the flange portion <NUM> may be coupled over a circumferentially outer side of the bushing hole <NUM> when the bushing hole <NUM> is viewed from above.

A circular recess <NUM> may be further provided at a central portion of one end surface of the bushing <NUM>. When the bushing <NUM> is inserted into the bushing hole <NUM>, a portion of a press device is inserted into the recess <NUM> formed at the one end surface of the bushing <NUM> so that the bushing <NUM> and the bushing hole <NUM> may be aligned in an axial direction. In this state, the bushing <NUM> may be easily engaged into the bushing hole <NUM> by pressing the bushing <NUM> toward the bushing hole <NUM> through the press device.

For convenience of illustration (e.g., for illustrating the recess <NUM>), the bushing <NUM> according to one embodiment is illustrated in a state that a through-hole is not formed in <FIG>, <FIG> and <FIG>. That is, as described below, after the bushing <NUM> is coupled to the knuckle body <NUM>, the through-hole is additionally formed in an axial direction of the bushing <NUM> so that the cylinder portion <NUM> may be formed in the form of a hollow cylinder to which a ball joint may be coupled.

The inventors of the present disclosure found a problem that if the bushing is coupled to the knuckle body by only a bonding agent, the bushing (especially, the bushing to which a ball joint is coupled) is separated from the knuckle body when a part connected to the knuckle body are replaced, since a large external force (e.g., <NUM> tons) is applied for replacement of the part connected to the knuckle body. That is, when a large external force acts on the bushing, a layer formed by the bonding agent may be deformed or broken and the bushing may be separated.

Accordingly, the inventors of the present disclosure have derived a new coupling method of the knuckle body and the busing which is capable of preventing the bushing <NUM> from being separated even when an external force is applied to the bushing <NUM> for replacement of the part connected to the knuckle body <NUM>.

According to one embodiment of the present disclosure, at least a portion of the bushing <NUM> may be coupled to the knuckle body <NUM> through press-fit. <FIG> illustrates a state in which the bushing <NUM> is coupled to the bushing hole <NUM> of the knuckle body <NUM> according to one embodiment of the present disclosure.

The carbon fiber reinforcement plastic material has a problem of not being flexibly deformed due to a lack of elasticity. However, the inventors of the present disclosure have made the bushing to be press-fitted into the bushing hole of the knuckle body by optimizing dimensions related to an inner diameter of the bushing hole of the knuckle and an outer diameter of the bushing and forming a groove for the bonding agent on an outer circumferential surface of the bushing. Since stress acting on the knuckle during the press-fit process may be partially alleviated in the groove for the bonding agent, it is possible to prevent the knuckle from being broken. Further, even when an external force for replacement of the part connected to the knuckle body <NUM> is applied, the bushing <NUM> can be reliably prevented from being separated from the knuckle body <NUM> since both of a bonding force due to the bonding agent and a press-fitting force due to the press-fit are provided.

A configuration for simultaneously applying the bonding force due to the bonding agent and the press-fitting force due to the press-fit will be described in detail below.

A size of the bushing hole and a size of the bushing may be limited according to other requirements of the vehicle and should provide sufficient resistance to the external force in the limited sizes. For example, at least one groove <NUM> may be formed on an outer circumferential surface of the cylinder portion <NUM> of the bushing <NUM> and a bonding agent (not shown) may be provided in the groove <NUM> so that the bonding force due to the bonding agent may be provided between the knuckle body <NUM> and the bushing <NUM>. The groove <NUM> may be provided as a single groove instead of a plurality of grooves. In this case, a width of the groove <NUM> may be increased in the bushing hole <NUM> having a limited height (as compared with a case of forming a plurality of grooves) so that a degree of breakage of the bonding agent may be reduced and large adhesion may be maintained.

According to one embodiment, a width W (see <FIG>) of the groove <NUM> may be greater than or equal to <NUM>. Further, in order to provide an acting force due to the press-fit in addition to an acting force due to the bonding agent, the width W of the groove <NUM> may not exceed <NUM>/<NUM> of an entire length of the bushing <NUM>. When the width of the groove <NUM> exceeds <NUM>/<NUM> of the entire length of the bushing <NUM>, a press-fitting force between the bushing <NUM> and the knuckle body <NUM> becomes insufficient so that a press-fitting force due to a load of, for example, at most <NUM> tons, may not be supported.

According to one embodiment, it is preferable that an inner diameter D1 (see <FIG>) of the bushing hole <NUM> is smaller than an outer diameter D2 (see <FIG>) of the remaining portion of the cylinder portion <NUM> of the bushing <NUM> except for the groove <NUM> and a difference between the inner diameter D1 of the bushing hole <NUM> and the outer diameter D2 of the remaining portion of the cylinder portion <NUM> of the bushing <NUM> except for the groove <NUM> is <NUM> to <NUM>. When the difference between the inner diameter D1 and the outer diameter D2 is smaller than <NUM>, the press-fitting force due to the press-fit is insufficient and the bushing <NUM> may be separated when an external force is applied. Further, when the difference between the inner diameter D1 and the outer diameter D2 is larger than <NUM>, breakage may occur in carbon fibers of the carbon chip constituting the knuckle body <NUM> when the bushing <NUM> is press-fitted to the knuckle body <NUM>, and thus strength of the knuckle <NUM> may be degraded or the knuckle <NUM> may be broken.

Table <NUM> shows a press-fitting load and a minimum separation load which are measured according to the difference between the inner diameter D1 of the bushing hole <NUM> and the outer diameter D2 of the remaining portion of the cylinder portion <NUM> of the bushing <NUM> except for the groove <NUM> (the difference may be defined as a press-fitted amount in Table <NUM>). The press-fitting load is a range of a load applied until the bushing <NUM> is fully press-fitted into the knuckle body <NUM>, and the minimum separation load is a minimum load applied for separating the bushing <NUM> press-fitted into the knuckle body <NUM>.

According to the measurement result, when the press-fitted amount is smaller than <NUM>, a load ranging from <NUM> to <NUM> ton was applied until the bushing <NUM> is fully press-fitted into the knuckle body <NUM>, and a minimum separation load for separating the coupled bushing <NUM> from the knuckle body <NUM> was measured as <NUM> ton. In a case that the press-fitted amount is less than <NUM>, when an external force (approximately <NUM> tons) is applied to replace the part connected to the knuckle body <NUM>, the bushing <NUM> is separated together with the part to be replaced. In the meantime, when the press-fitted amount exceeds <NUM>, the knuckle <NUM> was broken and a crack was generated while the bushing <NUM> is press-fitted into the knuckle body <NUM>.

On the other hand, when the press-fitted amount is <NUM> to <NUM>, a load ranging from <NUM> to <NUM> ton was applied until the bushing <NUM> is fully press-fitted into the knuckle body <NUM>, and a minimum separation load for separating the coupled bushing <NUM> from the knuckle body <NUM> was measured as <NUM> tons. That is, when the press-fitted amount according to one embodiment of the present disclosure is applied, a load of at least <NUM> tons is required to separate the bushing <NUM> from the knuckle body <NUM>. Accordingly, even when an external force (approximately <NUM> tons) is applied for replacement of the part connected to the knuckle body <NUM>, the bushing <NUM> may be reliably prevented from being separated from the knuckle body <NUM>.

In the present disclosure, the dimensions of the bushing <NUM> and the bushing hole <NUM> refer to dimensions before being deformed by the press-fit, that is, before the bushing <NUM> is press-fitted to the bushing hole <NUM> of the knuckle body <NUM>.

According to one embodiment, the bushing <NUM> may be press-fitted to the knuckle body <NUM> in a state that a bonding agent is applied to the outer circumferential surface of the cylinder portion <NUM> of the bushing <NUM>. Accordingly, the bonding agent may be further provided between the bushing hole <NUM> of the knuckle body <NUM> and the bushing <NUM>, particularly at least in the groove <NUM>.

According to one embodiment, the bonding agent may be an epoxy resin. Since the epoxy resin may provide large adhesion to a surface of material while being cured, the epoxy resin may further increase the coupling force in addition to the press-fitting force due to the press-fit of the knuckle body <NUM> and the bushing <NUM>.

As described above, after the bushing <NUM> is coupled to the knuckle body <NUM>, the through-hole may be formed in the axial direction of the bushing <NUM> and a ball joint may be coupled to the through-hole. For example, <FIG> is a cross-sectional view illustrating a state in which a ball stud <NUM> of the ball joint is coupled to the knuckle body <NUM> and the bushing <NUM> according to one embodiment of the present disclosure when viewed from a cross-section taken along the axial direction of the bushing.

As shown in <FIG>, the ball stud <NUM> is additionally fixed to the knuckle <NUM> in the axial direction by engaging a ball stud assembly nut <NUM> to the ball stud <NUM> from one side of the knuckle body <NUM>. In a cross-sectional view taken along the axial direction of the bushing <NUM>, an axial length L1 of the bushing <NUM> except for the flange portion <NUM> may be smaller than an axial length L2 of the bushing hole <NUM>. Accordingly, the ball stud assembly nut <NUM> is not in contact with the bushing <NUM> and is in contact with only the knuckle body <NUM> so that a load transmitted from the ball stud <NUM> is transmitted to only the knuckle body <NUM> in a direction of an arrow P and is not transmitted to the bushing <NUM>. That is, an influence of the load transmitted by the ball stud <NUM> at the coupling portion between the bushing <NUM> and knuckle body <NUM> may be significantly reduced, and a risk in that the bushing <NUM> is separated from the knuckle body <NUM> may be further reduced.

Alternatively, a groove <NUM>' for a bonding agent may be formed on an inner circumferential surface of a bushing hole of a knuckle body <NUM>' into which a bushing <NUM>' is inserted instead of an outer circumferential surface of a cylinder portion of the bushing <NUM>'. <FIG> is a cross-sectional view illustrating a state in which the bushing <NUM>' is coupled to a portion of the knuckle body <NUM>' according to another embodiment. As a result, similar to the case of forming the groove <NUM> on the bushing <NUM>, it is possible to obtain an effect of alleviating stress acting on the knuckle body <NUM>' during the press-fit and improving the coupling force between the bushing <NUM>' and the knuckle body <NUM>' due to the bonding agent.

In the above-described embodiments, shapes of the grooves <NUM> and <NUM>' for the bonding agent may be replaced with a groove <NUM> having a smooth curved shape at both ends in the width direction, at which the knuckle body is in contact with the bushing, as shown in <FIG>. Consequently, it is possible to solve a stress concentration problem of the knuckle caused by edges of the grooves <NUM> and <NUM>' when the bushing <NUM> and <NUM>' are inserted into the bushing holes of the knuckle bodies <NUM> and <NUM>'.

<FIG> is a flowchart illustrating a manufacturing method of a vehicle knuckle according to one embodiment of the present disclosure. With reference to <FIG>, the manufacturing method of a vehicle knuckle according to one embodiment may comprise preparing a bushing <NUM> formed of metal material (S100); preparing a knuckle body <NUM> formed of carbon fiber reinforcement plastic material and having at least one bushing hole <NUM> formed on the knuckle body <NUM> (S200); applying a bonding agent onto an outer circumferential surface of the bushing <NUM> (S300); coupling the bushing <NUM> to the bushing hole <NUM> of the knuckle body <NUM> through press-fit (S400); and forming a through-hole in the bushing <NUM> (S500).

In the preparing of the bushing <NUM> (S100), the bushing <NUM> may be formed by machining steel or aluminum material.

The preparing of the knuckle body <NUM> (S200) may comprise material filling operation of filling a mold with carbon chip material as much as a weight required for a knuckle forming; a hot-press forming operation of hot-press forming the carbon chip material filled in the mold; and a separation and trimming operation of separating the formed knuckle from the mold and trimming to remove surplus material attached to an outside of the formed knuckle.

Unlike a conventional case in which a knuckle is formed of carbon fiber reinforcement plastic films (continuous fiber), when the knuckle body <NUM> is formed of the carbon chips according to the present disclosure, productivity of the knuckle can be remarkably improved, since the knuckle body can be formed through only a simplified process of pouring the carbon chips of a required weight into the mold without cumbersome processes of cutting the carbon fiber reinforcement plastic films according to a shape of the knuckle and stacking the cut carbon fiber reinforcement plastic films according to orientation of the fiber texture.

In the preparation of the bushing <NUM>, the bushing <NUM> may be formed to comprise the cylinder portion <NUM> and the flange portion <NUM> formed to extend from one end portion of the cylinder portion <NUM> in a radially outward direction.

The preparing of the knuckle body <NUM> (S200) may further comprise forming at least one bushing hole <NUM> in the knuckle body <NUM>. The inner diameter D1 of the bushing hole <NUM> may be formed to be smaller than the outer diameter D2 of the remaining portion of the cylinder portion <NUM> of the bushing <NUM> except for the groove <NUM>, and a difference between the inner diameter D1 of the bushing hole <NUM> and the outer diameter D2 of the remaining portion of the cylinder portion <NUM> of the bushing <NUM> except for the groove <NUM> may be formed to range from <NUM> to <NUM>.

When the bushing hole <NUM> and the bushing <NUM> are formed as described above and then the bushing <NUM> is press-fitted into the bushing hole <NUM>, a sufficient press-fitting force may be obtained between the knuckle body <NUM> and the bushing <NUM> without deformation of the carbon fibers in the carbon chips of the knuckle body <NUM>.

The preparing of the bushing <NUM> (S100) may further comprise forming at least one groove <NUM> on an outer circumferential surface of the cylinder portion <NUM> in a circumferential direction. The groove <NUM> may be formed to have a width greater than or equal to <NUM> and less than or equal to <NUM>/<NUM> of the entire length of the bushing <NUM>.

The coupling of the bushing <NUM> to the bushing hole <NUM> of the knuckle body <NUM> through press-fit (S400) may further comprise inserting a portion of a press device into the recess <NUM> and aligning the bushing <NUM> and the bushing hole <NUM> of the knuckle body <NUM> in the axial direction. In this state, the bushing <NUM> may be easily coupled to the bushing hole <NUM> by pressing the bushing <NUM> toward the bushing hole <NUM> using the press device.

Before the coupling of the bushing <NUM> to the bushing hole <NUM> of the knuckle body <NUM> through press-fit (S400), the applying of the bonding agent onto the outer circumferential surface of the cylinder portion782 of the bushing <NUM> (S300) may be further provided. As the sufficient bonding agent is provided on the outer circumferential surface of the bushing <NUM>, particularly in the groove <NUM>, the bonding agent may increase the coupling force between the knuckle body <NUM> and the bushing <NUM> while the bonding agent provided between the bushing <NUM> and the knuckle body <NUM> is cured during the press-fit.

After the knuckle body <NUM> and the bushing <NUM> are completely coupled, the formation of a through-hole (not shown) in the bushing <NUM> (S500) may be further provided. The through hole is a feature for assembling the ball joint which connects another vehicle part to the knuckle <NUM> and may be formed so as to pass through in an axial direction X of the bushing <NUM>.

Alternatively, the preparing of the knuckle body <NUM>' (S200) may further comprise forming the groove <NUM>' for the bonding agent on the inner circumferential surface of the bushing hole <NUM>.

The manufacturing method of a vehicle knuckle according to one embodiment of the present disclosure and the vehicle knuckle manufactured according to such a manufacturing method may provide the following advantages.

Since the vehicle knuckle is formed by hot-press forming the carbon chips, the knuckle may be manufactured in a considerably light weight as compared with a conventional metal knuckle product. Further, unlike a conventional case in which a knuckle is formed of carbon fiber reinforcement plastic films (continuous fiber), a forming preparation may be completed through only a simplified process of pouring the carbon chips of a required weight into a mold without cumbersome processes of cutting the carbon fiber reinforcement plastic films according to a shape of the knuckle and stacking the cut carbon fiber reinforcement plastic films according to orientation of the fiber texture. Therefore, productivity can be significantly improved and mass production can be implemented.

Claim 1:
A vehicle knuckle, comprising:
a bushing formed of metal material; and
a knuckle body formed of carbon fiber reinforcement plastic material and having at least one bushing hole to which a ball joint is couplable,
wherein at least a portion of the bushing is coupled to the bushing hole of the knuckle body through press-fit,
wherein an axial length of the bushing except for a flange portion is smaller than an axial length of the bushing hole in a cross-section taken along an axial direction of the bushing, and
wherein the knuckle body is manufactured by filling a mold with carbon chip material comprising carbon fiber reinforcement plastic material and then hot-press forming the carbon chip material filled in the mold under high temperature and high pressure environment.