Mounting unit for a subframe

Abstract

Mounting unit for a subframe for fastening the subframe to a longitudinal member (10) of a vehicle body, comprising: a tube nut (20) installed to be inserted into a through hole (11) of a mounting portion of the longitudinal member (10); a subframe holder (30) fixed under the side member (10) so as to correspond to the pipe nut (20) and having a fastening hole (31a) in which a lower end portion of the pipe nut (20) is fastened; and a reinforcement bracket (40) fixed to an inner side of the longitudinal member (10) and fixing an upper end portion of the pipe nut (20), wherein the subframe holder (30) comprises: a fastening portion (31) provided with the fastening hole (31a) in which the lower end portion of the pipe nut (20) is fastened; a body (33) coupled to a plurality of ribs (33a) radially formed on a periphery of the fixing portion (31); and a coupling portion (35) formed at an upper end of the body (33) and fixed to a lower portion of the longitudinal member (10), and wherein the lower end portion of the pipe nut (20) penetrating the lower portion of the longitudinal member (10) is screwed into the fastening hole (31a) of the fastening portion (31), and a guide surface (31b) is formed obliquely on an inner periphery of an upper end of the fastening hole (31a) and guides the lower end portion of the pipe nut (20) to the fastening hole (31a).

Description

[0001] The invention relates to a subframe mounting unit, and more particularly to a subframe mounting unit that increases the assembly quality, reduces its weight, and improves NVH (noise, vibration, harshness) performance by facilitating assembly between a side member and a subframe.

[0002] Generally, a centrally mounted vehicle has a subframe bolted to a front side member.

[0003] Fig. 1 is a perspective view for describing a method of assembling a general front side member and a subframe.

[0004] With reference to Fig. 1, the subframe 101 is attached to a lower section of front longitudinal members 103 by means of screws 107.

[0005] On the subframe 101, an engine (not shown) and a transmission (not shown) are arranged in the front and rear directions, and since the engine is designed so that it cannot be pushed toward a partition wall of a vehicle body as a rigid body, buckling of the subframe 101 is caused to allow the engine to be lowered, thereby ensuring collision safety.

[0006] The subframe 101 is attached to the lower section of the respective front longitudinal member 103 by means of the screws 107 via a mounting unit 105.

[0007] In order to fix the subframe 101 to the lower portion of the respective front side member 103, the mounting unit 105 has a mounting bracket 109 connected to the lower portion of the front side member 103 and a pipe nut 111 installed between the mounting bracket 109 and the front side member 103.

[0008] That is, the subframe 101 is fastened to the respective front longitudinal member 103 by means of the tubular nut 111 and the screw 107 under the mounting bracket 109.

[0009] However, the mounting unit 105 has a structure in which the pipe nut 111 is simply fixed by means of the mounting bracket 109, which often results in faulty mounting straightness and insufficient connection strength.

[0010] Accordingly, a vehicle can easily be damaged in a frontal collision.

[0011] US 2010 / 0 072 787 A1 describes a subframe mounting unit for fastening the subframe to a side member of a vehicle body, comprising a tube nut installed to be inserted into a through hole above a mounting portion of the side member, a subframe bracket fixed below the side member to correspond to the tube nut and having a mounting hole in which a lower end portion of the tube nut is fixed, and a reinforcing bracket fixed to an inner side of the side member and fixing an upper end portion of the tube nut.

[0012] DE 10 2005 050 967 A1 describes an assembly unit for a subframe for fastening the subframe to a longitudinal member of a vehicle body.

[0013] The invention provides a subframe mounting unit which can ensure the mounting straightness of the pipe nut and improve the connection strength by a reinforcing bracket, wherein a subframe bracket can be cast from an aluminum material and thus has a reduced weight.

[0014] This is achieved according to the invention by a mounting unit for a subframe according to the features of claim 1. Advantageous further developments are described in the subclaims.

[0015] According to the invention, the lower end portion of the pipe nut inserted into the through hole of the side member is bolted to the subframe bracket connected to the lower portion of the side member, and at the same time, the upper end portion of the pipe nut is fixed to the reinforcing bracket fixed to the inner side of the side member, thereby improving the mounting straightness of the pipe nut, thus facilitating the mounting and increasing the connection strength of the subframe.

[0016] As described above, the connection strength between the side member and the subframe can be increased to improve NVH behavior.

[0017] In addition, the subframe bracket is manufactured in such a way that it can be cast in one piece from aluminum, which reduces its weight.

[0018] The invention is explained in more detail with reference to the drawing. The drawing shows: Fig. 1 is a perspective view for describing a method of assembling a general front side member and a subframe; Fig. 2 is a perspective view of a subframe mounting unit according to an exemplary embodiment of the invention in an assembled state; Fig. 3 is a perspective view of a subframe bracket of the subframe mounting unit according to the exemplary embodiment of the invention; Fig. 4 is a perspective view of a reinforcement bracket and a tube nut of the subframe mounting unit according to the exemplary embodiment of the invention installed on the side member; and Fig. 5 a section along the line AA in Fig. 2. In the figures, identical parts are designated by the same reference numerals.

[0019] With reference to the Fig. 2 to 5, a subframe mounting unit according to an exemplary embodiment of the invention includes a tube nut 20, a subframe bracket 30, and a reinforcement bracket 40.

[0020] A threaded portion 23 is formed on an outer peripheral surface of a lower end portion of the pipe nut 20 and inserted into a through hole 11 of a mounting portion of a vehicle body side member 10.

[0021] The subframe bracket 30 is fixed to a lower portion of the side member 10 so as to correspond with the pipe nut 20 and is provided with a fixing hole 31a in which the threaded portion 23 of the pipe nut 20 is fixed.

[0022] That is, the subframe bracket 30 is fixed to the lower portion of the side member 10 by welding and has a fixing portion 31, a body 33 and a coupling portion 35.

[0023] The fastening portion 31 is provided with the fastening hole 31a into which the lower end portion of the pipe nut 20 penetrating the bottom of the side member 10 is screwed, and a guide surface 31b is formed obliquely on an inner periphery of an upper end of the fastening hole 31a to guide the lower end portion of the pipe nut 20 toward the fastening hole 31a.

[0024] The body 33 is coupled to a periphery of the fixing portion 31 via eight ribs 33a formed radially on the periphery of the fixing portion 31.

[0025] In addition, the coupling portion 35 is formed in the shape of a support plate at an upper end of the body 33 and fixes the subframe holder 30 to the side member 10 by being fitted onto and welded to the lower portion of the side member 10.

[0026] That is, the coupling portion 35 is formed such that its shape corresponds to the bottom and the lateral sides of the longitudinal member 10, so that it is placed on and connected to the lower portion of the longitudinal member 10 and is welded to the longitudinal member 10 at its opposite lateral sides.

[0027] In this case, the subframe bracket 30 may be integrally cast from aluminum, and the fixing portion 31 may be formed from a steel material and inserted into the subframe bracket 30 for casting.

[0028] A fixing hole 41 is formed in a center of the reinforcing bracket 40 formed by bending a plate, so that an upper end portion of the pipe nut 20 is inserted into and fixed in the fixing hole 41.

[0029] In addition, the reinforcement bracket 40 is provided along its edge with a connecting flange 43 which is connected to an inner side of the longitudinal member 10.

[0030] That is, the reinforcement bracket 40 is formed in a C-shape such that it is connected to the inside of the side member 10 and is welded to the inner surface of the side member 10 by means of the connecting flange 43.

[0031] Accordingly, as in Fig. 5, the subframe mounting unit having the above-described structure is configured such that the subframe bracket 30 is fixed by welding through the coupling portion 35 under the mounting portion of the side member 10 inserted therein.

[0032] In this case, the fastening portion 31 of the subframe holder 30 is positioned such that it corresponds to the through hole 11 of the mounting portion of the longitudinal member 10.

[0033] In a state where the lower end portion of the pipe nut 20 is inserted into the through hole 11 of the side member 10, the pipe nut 20 is screwed into the fastening hole 31a formed in the fastening portion 31 of the subframe bracket 30.

[0034] In this case, the lower end portion of the pipe nut 20 is guided toward the mounting hole 31a by the guide surface 31b formed in the mounting portion 31, thereby facilitating assembly.

[0035] When the lower end portion of the pipe nut 20 is screwed into the fastening hole 31a of the subframe bracket 30, the pipe nut 20 is fixed to a periphery of the through hole 11 of the side member 10 by welding via a flange portion 21 formed on its lower periphery.

[0036] In this case, the connection strength of the subframe holder 30 is ensured by the eight ribs 33a, via which the fastening portion 31 is supported on the body 33.

[0037] The assembly straightness of the pipe nut 20 is ensured by fixing the upper end portion of the pipe nut 20 by welding while being inserted into the fixing hole 41 of the reinforcement bracket 40.

[0038] Accordingly, in the subframe mounting unit according to the exemplary embodiment of the invention, the subframe bracket 30 may be cast from an aluminum material to reduce the overall weight thereof, and the fixing portion 31 made of a steel material and provided with the fixing hole 31a is employed for casting, thereby preventing abrasion of the thread formed on the inside of the fixing hole 31a and thus improving the joining strength of the pipe nut 20.

[0039] For ease of description and accurate definition in the appended claims, the terms "top", "bottom", "inside" and "outside" are used to describe the features of the exemplary embodiment with reference to the positions of those features in the figures.

Claims

[1] Mounting unit for a subframe for fastening the subframe to a longitudinal member (10) of a vehicle body, comprising: a tube nut (20) installed to be inserted into a through hole (11) of a mounting portion of the longitudinal member (10); a subframe holder (30) fixed under the side member (10) so as to correspond to the pipe nut (20) and having a fixing hole (31a) in which a lower end portion of the pipe nut (20) is fixed; and a reinforcement bracket (40) which is fixed to an inner side of the longitudinal member (10) and fixes an upper end portion of the pipe nut (20), wherein the subframe holder (30) comprises: a fastening portion (31) provided with the fastening hole (31a) in which the lower end portion of the pipe nut (20) is fastened; a body (33) coupled to a plurality of ribs (33a) radially formed on a periphery of the fixing portion (31); and a coupling portion (35) formed at an upper end of the body (33) and fixed to a lower portion of the longitudinal member (10), and wherein the lower end portion of the pipe nut (20) penetrating the lower portion of the longitudinal member (10) is screwed into the fastening opening (31a) of the fastening portion (31), and a guide surface (31b) is formed obliquely on an inner circumference of an upper end of the fastening opening (31a) and guides the lower end portion of the pipe nut (20) to the fastening opening (31a). [2] Mounting unit according to claim 1, wherein the subframe holder (30) is cast in one piece from an aluminum material and is connected to the lower portion of the side member (10) by welding via the coupling portion (35). [3] The mounting unit according to claim 1, wherein the subframe holder (30) is cast from an aluminum material while the fixing portion (31) formed from a steel material is inserted, and is connected to the lower portion of the side member (10) by welding via the coupling portion (35). [4] Mounting unit according to one of claims 1 to 3, wherein the pipe nut (20) is connected to the longitudinal member (10) via a flange portion (21) formed on its lower periphery, while being inserted into the through-hole (11) of the longitudinal member (10). [5] The mounting unit according to any one of claims 1 to 4, wherein a fixing hole (41) is formed in a center of the reinforcement bracket (40) formed by bending a plate so that the upper end portion of the pipe nut (20) is fixedly fitted in the fixing hole (41), and the reinforcement bracket (40) is provided along its periphery with a connecting flange (43) which is connected to an inner side of the longitudinal member (10).

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