Running net chassis assembly for low-floor buses and manufacturing method thereof

Abstract

The present invention discloses a running chassis assembly for a low-floor bus and a manufacturing method thereof. The running chassis assembly includes: a front frame, on which a front suspension is mounted; a rear frame assembly, on which a battery bracket is mounted, wherein the rear frame assembly includes: a first rear frame, on which a rear suspension is mounted; a second rear frame, which is connected to the first rear frame and on which a radiator is mounted; and a battery bracket frame, on which the battery bracket is mounted and which is connected to the first rear frame through a second joint; and a central frame, which is connected to the front frame and the rear frame assembly through a first joint, wherein a stress distribution caused by the first joint is greater than a stress distribution caused by the second joint.

Description

Technical Field

[0001] Exemplary embodiments of the present invention relate to a running bare chassis assembly for a low-floor bus and a method of manufacturing the same. Background Art

[0002] Electric buses and hydrogen-powered buses are being developed domestically and globally. Among electric buses and hydrogen-powered buses, low-floor double-decker electric buses are also being developed.

[0003] The vehicle is divided into a body and a chassis, and the chassis is formed by assembling a power transmission system, a suspension, and electric vehicle components to a vehicle frame as a basic framework.

[0004] Conventionally, since the body structure of a low-floor bus is formed as a build-up body structure, the body weight is excessively large and workability is very disadvantageous.

[0005] For example, a conventional ultra-low floor frame assembly for a compressed natural gas (CNG) engine has a structure in which a front frame is connected to a center frame using a longitudinal beam. However, since it is impossible to integrally manufacture the front frame and the center frame and separate the front frame from the center frame, assembly work is impossible and the length of the center frame is not easily changed.

[0006] In addition, the conventional ultra-low floor frame assembly has a structure in which the center frame and the rear frame are connected to the longitudinal beams by connecting members. However, since it is also impossible to integrally manufacture the center frame, the rear frame, and the longitudinal beams and separate the center frame, the rear frame, and the longitudinal beams from each other, it is impossible to perform assembly work and the length of the center frame cannot be easily changed.

[0007] In addition, when the stacked body structure is applied, the load of the three-axis air spring of the double-decker electric bus may not be satisfied. The load of the three-axis air spring of the double-decker electric bus is less than or equal to 6,700 kg.

[0008] The contents described in the background art are intended to help understanding the context of the present invention and may include contents that are previously unknown to those skilled in the art to which the present invention belongs. Summary of the invention

[0009] Embodiments of the present invention are directed to a running net chassis assembly for a low-floor bus that is lightweight and has excellent manufacturing workability, and a method for manufacturing the same.

[0010] Other objects and advantages of the embodiments of the present invention can be understood by the following description, and other objects and advantages of the present invention will become apparent with reference to the embodiments of the present invention. Likewise, it will be apparent to those skilled in the art that the objects and advantages of the embodiments of the present invention can be achieved by the claimed means and combinations thereof.

[0011] According to an embodiment of the present invention, there is provided a running net chassis assembly for a low-floor bus, comprising: a front frame on which a front suspension is mounted; a rear frame assembly on which a battery bracket is mounted; and a central frame connected to the front frame and the rear frame assembly by a first joint, wherein the rear frame assembly comprises: a first rear frame on which a rear suspension is mounted; a second rear frame connected to the first rear frame and a radiator is mounted on the second rear frame; and a battery bracket frame on which the battery bracket is mounted and connected to the first rear frame by a second joint, and the stress distribution caused by the first joint is greater than the stress distribution caused by the second joint.

[0012] In addition, the running chassis assembly may further include a central bridge connected between the front frame and the rear frame assembly.

[0013] In addition, the front frame may include: a front suspension mounting portion on which the front suspension is mounted; and an air tank mounting portion formed on the front frame to allow an air tank to be mounted above the front frame.

[0014] In addition, the center frame may be formed such that longitudinal frames and transverse frames form a grid structure, wherein the longitudinal frames are formed and arranged to be spaced apart from each other in a longitudinal direction of the center frame, and the transverse frames are formed and arranged to be spaced apart from each other in a width direction of the center frame.

[0015] In addition, the first rear frame may include: a lower frame forming a lower portion and having the rear suspension mounted thereon; and an upper frame forming an upper portion, wherein the upper frame may be formed such that the first upper frame and the second upper frame form a grid structure, wherein the first upper frames are formed and arranged to be spaced apart from each other in a longitudinal direction of the first rear frame, and the second upper frames are formed and arranged to be spaced apart from each other in a width direction of the first rear frame.

[0016] In addition, the second rear frame may be formed of a grid-like low-floor frame forming a lower surface and a plurality of vertical frames formed vertically upward from the low-floor frame.

[0017] In addition, each upper end of the plurality of vertical frames may be coupled to a lower end of the first rear frame through the first joint.

[0018] In addition, a module upper side joint portion protruding downward may be formed in the first upper frame to be bolted to the radiator upper side joint portion above the radiator, and a module lower side joint portion protruding upward may be formed in the low-floor frame to be bolted to the radiator lower side joint portion below the radiator.

[0019] In addition, the module upper side joint portion and the radiator upper side joint portion may be connected by bolts passing through the rear frame assembly in the width direction of the rear frame assembly, and the module lower side joint portion and the radiator lower side joint portion may be connected by bolts passing through the rear frame assembly in the height direction of the rear frame assembly.

[0020] Meanwhile, a plate-shaped forklift mounting guide extending in a width direction of the battery bracket frame may be formed in a lower end portion of the battery bracket frame.

[0021] In addition, a guide plate may be coupled to the second upper frame to extend in a longitudinal direction of the second upper frame and to protrude upward from the second upper frame.

[0022] In addition, a stopper may be coupled to the first upper frame to protrude upward from the first upper frame, and a guide pin disposed on the first upper frame may be coupled to one side of the stopper.

[0023] In addition, the first joining may be a welding joining method, and the second joining may be a bolting joining method.

[0024] Additionally, the front suspension may be an independent suspension and the rear suspension may be a rigid axle.

[0025] Next, a method for manufacturing a running chassis assembly for a low-floor bus includes: manufacturing a front frame on which a front suspension is mounted; manufacturing a rear frame assembly, including: connecting a second rear frame on which a radiator is mounted to a first rear frame on which a rear suspension is mounted through a first joint; and connecting a battery bracket frame on which a battery bracket is mounted to the first rear frame through a second joint; manufacturing a central frame to connect the front frame to the rear frame assembly; and connecting the front frame, the rear frame assembly, and the central frame through the first joint, wherein the stress distribution caused by the first joint is greater than the stress distribution caused by the second joint.

[0026] Additionally, the manufacturing method may further include connecting a center bridge between the front frame and the rear frame assembly.

[0027] In addition, the first joining may be a welding joining method, and the second joining may be a bolting joining method.

[0028] Additionally, the front suspension may be an independent suspension and the rear suspension may be a rigid axle. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 is a diagram showing a running net chassis assembly for a low-floor bus according to an embodiment of the present invention.

[0030] Figures 2 to 5 1 is a diagram showing a coupling relationship between various parts of a running net chassis assembly for a low-floor bus according to an embodiment of the present invention.

[0031] Figure 6 1 is a diagram showing a state in which various components are mounted on a rear frame assembly of a running net chassis for a low-floor bus according to an embodiment of the present invention.

[0032] Figure 7 It is shown Figure 6 Part of the diagram.

[0033] Figure 8 1 is a diagram showing a coupling relationship between various parts of a running net chassis assembly for a low-floor bus according to an embodiment of the present invention.

[0034] Fig. 9 : is a view showing a partial cross-sectional shape of a battery bracket frame for a running net chassis of a low-floor bus according to an embodiment of the present invention.

[0035] Fig.10 : is a diagram showing a partial shape of a first rear frame of a running net chassis for a low-floor bus according to an embodiment of the present invention.

[0036] Fig.11 and Fig.12 is a graph showing stress analysis results of a running net chassis for a low-floor bus according to an embodiment of the present invention. DETAILED DESCRIPTION

[0037] Reference should be made to the accompanying drawings illustrating exemplary embodiments of the invention and to the description therein for a fuller understanding of the invention and its operating advantages and objectives attained by practicing the embodiments of the invention.

[0038] In describing the exemplary embodiments of the present invention, known technologies may be reduced or omitted or descriptions may be repeated to avoid unnecessarily obscuring the gist of the present invention.

[0039] Figure 1 is a diagram showing a running net chassis assembly for a low-floor bus according to an embodiment of the present invention, and Figures 2 to 5 1 is a diagram showing a coupling relationship between various parts of a running net chassis assembly for a low-floor bus according to an embodiment of the present invention.

[0040] In the following, reference will be made to Figures 1 to 5 A running net chassis assembly for a low-floor bus and a method of manufacturing the running net chassis assembly according to one embodiment of the present invention are described.

[0041] An embodiment of the present invention relates to a running chassis assembly of a low-floor bus (e.g., a double-decker electric bus), and to minimizing the overall weight and improving assemblability by separately manufacturing a front frame 110, a center frame 120, and a rear frame assembly and then coupling the front frame 110, the center frame 120, and the rear frame assembly.

[0042] The front frame 110 is a chassis module corresponding to the front side of the low-floor bus, and has a structure on which an independent suspension and an air tank are mounted.

[0043] The rear frame assembly is a chassis model corresponding to the rear side of the low-floor bus, connected with the first rear frame 130, the second rear frame 140, the first battery bracket frame 150, the second battery bracket frame 160, and the air-conditioning mounting frame 170, and has a structure on which an in-wheel motor, a low-floor rigid shaft, a PE chamber, a battery bracket, etc. are mounted.

[0044] In addition, a center frame 120 may be connected between the front frame 110 and the rear frame assembly, and a center bridge 180 may be connected between the front frame 110 and the rear frame assembly to prevent deformation during driving.

[0045] That is, the center frame 120 is connected to the lower end of the rear side of the front frame 110 , and is connected to the lower end of the front side of the rear frame assembly.

[0046] like Figure 2 As shown, an air tank mounting portion 111 and a front suspension mounting portion 112 are formed on the front frame 110, and an air tank and a front suspension are mounted on the air tank mounting portion 111 and the front suspension mounting portion 112, respectively. The front suspension mounting portion 112 has an arch structure, and the air tank mounting portion 111 is formed in a hexahedral shape on the upper side of the front frame 110. The front suspension may be an independent suspension.

[0047] The center frame 120 is formed in a structure in which the longitudinal frames 121 are arranged to be spaced apart from each other in the longitudinal direction of the net chassis, and the transverse frames 122 are arranged to be spaced apart from each other in the width direction of the net chassis.

[0048] The lower end of the rear side of the front frame 110 and the front side of the center frame 120 , that is, the front side of the longitudinal frame 121 are coupled by welding as a first joining method.

[0049] Since the connection between the front frame 110 and the center frame 120 is a connection between main members subjected to high stress, the front frame 110 and the center frame 120 are members connected by welding to distribute stress. Such welding can be performed because there is no need to separate the members on site for maintenance, for example, after welding. This stress distribution caused by the first joining method is greater than the stress distribution caused by the second joining method to be described below.

[0050] A conventional ultra-low floor frame assembly for a compressed natural gas (CNG) engine has a structure in which a front frame is connected to a center frame using a longitudinal beam. However, since it is impossible to integrally manufacture the front frame and the center frame and separate the front frame from the center frame, assembly work is impossible and the length of the center frame is not easily changed.

[0051] However, according to the embodiment of the present invention, a structure in which the front suspension can be installed only with the front frame 110 of the embodiment of the present invention is achieved. In addition, this structure is also applicable to 13M electric vehicles, 18M electric vehicles, hydrogen-powered vehicles, etc.

[0052] In addition, workability is more favorable when assembling the front suspension due to the reduced working space and simplified working range.

[0053] In addition, the conventional ultra-low floor frame assembly for the CNG engine has a structure in which the center frame and the rear frame are connected to the longitudinal beams using connecting members. However, since it is not possible to integrally manufacture the center frame, the rear frame, and the longitudinal beams and separate the center frame, the rear frame, and the longitudinal beams from each other, it is impossible to perform assembly work and the length of the center frame is not easily changed.

[0054] However, the structure of the central frame 120 according to the embodiment of the present invention has the advantage of being easy to change in length. In addition, the central frame 120 is also applicable to 13M electric vehicles, 18M electric vehicles, hydrogen-powered vehicles, etc.

[0055] That is, the length of the center frame 120 may be set by separating or extending the lateral frame 122 in consideration of stress measurement results to be described below.

[0056] Next, Figures 3 to 5 The connection relationship of the rear frame assembly is shown.

[0057] Reference Figure 3 , the first rear frame 130 and the second rear frame 140 may be coupled first.

[0058] The first rear frame 130 forms a lower portion, and an in-wheel motor and a low-floor rigid shaft (as an example of a rear suspension) are mounted on the first rear frame 130. To this end, the first rear frame 130 is formed of a lower frame 131 including an arch structure and an upper frame forming an upper portion, and the upper frame is formed in a shape in which a first upper frame 132 and a second upper frame 133 form a grid shape.

[0059] That is, the upper frames are formed in a structure in which the first upper frames 132 are arranged to be spaced apart from each other in the longitudinal direction of the clean chassis, and the second upper frames 133 are arranged to be spaced apart from each other in the width direction of the clean chassis.

[0060] The second rear frame 140 is formed of a grid-like low-floor frame 141 forming a lower surface and a plurality of vertical frames 142 formed vertically upward from the low-floor frame 141 .

[0061] Therefore, if Figure 4 As shown, the upper end of the vertical frame 142 of the second rear frame 140 may be coupled to the first rear frame 130 , and may be coupled to the lower end of the lower frame 131 of the first rear frame 130 or to a point where the first upper frame 132 and the second upper frame 133 intersect.

[0062] Since the connection between the first rear frame 130 and the second rear frame 140 is a connection between main members subjected to high stress, the first rear frame 130 and the second rear frame 140 are members coupled by welding as a first joining method to distribute stress. Such connection can be performed because there is no need to separate the members for maintenance on site after welding.

[0063] Next, if Figure 5 As shown, the first battery bracket frame 150, the second battery bracket frame 160, and the air conditioner mounting frame 170 are coupled to the first rear frame 130 and the second rear frame 140 coupled to each other.

[0064] The first battery bracket frame 150 and the second battery bracket frame 160 are formed of frames capable of accommodating components of a battery bracket, and the air conditioner is mounted on the air conditioner mounting frame 170 .

[0065] In addition, the lower ends of the first battery bracket frame 150, the second battery bracket frame 160, and the air conditioner mounting frame 170 are coupled to the upper end of the first rear frame 130 by bolting as a second joining method, thereby supplementing the rear frame assembly. Thereafter, the lower end of the front side of the rear frame assembly is welded to the rear end of the center frame 120.

[0066] The connection between the first battery bracket frame 150, the second battery bracket frame 160, the air conditioner mounting frame 170, and the first rear frame 130 may require battery replacement work or air conditioner maintenance on site, and the connection is achieved by bolt connection, so it is easy to connect and disassemble.

[0067] In addition, the positions and the number of bolts of the bolt connections between the first rear frame 130 , the first battery bracket frame 150 , and the second battery bracket frame 160 may be selected based on the stress analysis results.

[0068] Figure 6 The various components are shown installed on the complete rear frame assembly, and Figure 7 Shows Figure 6 part of.

[0069] like Figure 6 As shown, the wheel motor shaft 11 and the low-floor rigid shaft 12 are mounted on the lower frame 131 of the first rear frame 130 , and the radiator (cooling system) and the battery bracket 40 are mounted on the second rear frame 140 .

[0070] In addition, the air tank 30 and the battery bracket 40 are mounted on the first battery bracket frame 150 and the second battery bracket frame 160 .

[0071] As described above, the battery bracket 40 , the low-floor rigid axle 12 , the radiator, and the air tank 30 may be assembled to the rear frame assembly, and thus the rear frame assembly may be extended and applied to other derivative vehicles.

[0072] Meanwhile, according to the related art, the radiator is mounted on the frame and the side panel, but according to an embodiment of the present invention, the radiator is configured to be mounted only on the frame.

[0073] In addition, according to an embodiment of the present invention, Figure 7 As shown, a module upper side joint portion 132-1 protruding downward is formed on the first upper frame 132 of the first rear frame 130 and is bolted to the radiator upper side joint portion 21 above the radiator 20, and a module lower side joint portion 141-1 protruding upward is formed on the low floor frame 141 of the second rear frame 140 and is bolted to the radiator lower side joint portion 22 below the radiator 20.

[0074] In particular, the bolts for connecting the module upper side joint 132-1 and the radiator upper side joint 21 are formed to pass through and connect the module upper side joint 132-1 and the radiator upper side joint 21 in the width direction of the clean chassis, and the bolts for connecting the module lower side joint 141-1 and the radiator lower side joint 22 are formed to pass through and connect the module lower side joint 141-1 and the radiator lower side joint 22 in the height direction of the clean chassis, thereby minimizing the vibration of the fan of the radiator 20.

[0075] At the same time, the first battery bracket frame 150 and the second battery bracket frame 160 are bolted to the upper end of the first rear frame 130. Figure 8 As shown, in order to arrange the first battery bracket frame 150 and the second battery bracket frame 160 on the upper side of the first rear frame 130, or to facilitate the separation of the first battery bracket frame 150 and the second battery bracket frame 160 from the upper side of the first rear frame 130, the first battery bracket frame 150 and the second battery bracket frame 160 are placed into the upper side of the first rear frame 130 from the lateral direction thereof.

[0076] like Fig. 9 As shown, a forklift mounting guide 151 is formed in the lower end portions of the first battery bracket frame 150 and the second battery bracket frame 160 to allow the first battery bracket frame 150 and the second battery bracket frame 160 to be transported by a forklift. That is, the forklift mounting guide 151 capable of being supported on a jig of a forklift is formed in the form of a plate at the lower end portions of the first battery bracket frame 150 and the second battery bracket frame 160 in the width direction.

[0077] like Figure 8 As shown, the first battery bracket frame 150 and the second battery bracket frame 160 are coupled to the upper end of the first rear frame 130 by bolt connection as a second joining method, thereby supplementing the rear frame assembly. Thereafter, the lower end of the front side of the rear frame assembly is welded to the rear end of the center frame 120.

[0078] In addition, the guide pins 191 , the stoppers 192 , and the plurality of guide plates 193 are configured to carry the first battery tray frame 150 and the second battery tray frame 160 on the first rear frame 130 and position the first battery tray frame 150 and the second battery tray frame 160 at correct positions on the first rear frame 130 .

[0079] The longitudinal direction of the guide plate 193 is parallel to the longitudinal direction of the second upper frame 133, and the guide plate 193 is coupled to the upper portion of the second upper frame 133 to protrude upward from the second upper frame 133. Therefore, the front and rear ends of the first and second battery tray frames 150 and 160 are guided to be arranged in the plurality of guide plates 193.

[0080] In addition, the stopper 192 is coupled to protrude upward on the sides of the two first upper frames 132 arranged on the outer sides among the plurality of first upper frames 132. When the first battery bracket frame 150 and the second battery bracket frame 160 are pushed in and transported, the stopper 192 blocks the first battery bracket frame 150 and the second battery bracket frame 160 and helps the first rear frame 130 not to deviate from the arrangement.

[0081] In addition, in order to support the stopper 192, a guide pin 191 is formed to protrude from one side of the stopper 192 to be coupled to the stopper 192 and is placed on the first upper frame 132, thereby preventing the stopper 192 from being pushed by the first and second battery tray frames 150 and 160 being transported.

[0082] As described above, since the weight of the running bare chassis assembly for a low-floor bus according to an embodiment of the present invention can be reduced when compared with a conventional bare chassis, stress concentration can be minimized, and the results of the stress analysis are shown in FIG. Fig.11 and Fig.12 middle.

[0083] That is, it can be confirmed that since the stress is largely distributed due to the first joining method, there is no stress near the portion where the center frame 120 is coupled to the front frame 110 and near the portion where the center frame 120 is coupled to the rear frame assembly. Therefore, the corresponding portion can be determined as a parting line.

[0084] When determining the parting lines of the front frame 110, the center frame 120, and the rear frame assembly, whether they can respond without changes when a derivative vehicle is deployed should be considered, and a module range in which system assembly is to be performed before the parting line should be selected, and a portion that is subjected to the least stress should be selected as the parting line.

[0085] It can be seen from such stress analysis results that, compared with the conventional chassis, the running net chassis assembly for a low-floor bus according to the embodiment of the present invention is subjected to less stress.

[0086] Therefore, in the case of a conventional battery tray frame, the thickness of the cross section is 5.7 mm or 3.2 mm depending on the location, while the thickness of the cross section of the battery tray frame according to the embodiment of the present invention can be changed to 2.3 mm.

[0087] In addition, in the case of the lower frame of the conventional rear frame, the thickness of the cross section is 5.7 mm, but the thickness of the cross section of the lower frame 131 of the first rear frame 130 according to the embodiment of the present invention may be changed to 3.2 mm.

[0088] In addition, in the case of the upper frame of the conventional rear frame, the thickness of the cross section is 3.2 mm, but the thickness of the cross section of the upper frame of the first rear frame 130 according to the embodiment of the present invention may be changed to 2.3 mm.

[0089] According to the structure of the running net chassis for a low-floor double-decker electric bus according to an embodiment of the present invention, since the vehicle floor platform is assembled with five modules to manufacture the body module structure of the net chassis, and then the electric bus electronic components and systems are assembled, the workability can be significantly improved and the weight can be reduced.

[0090] Furthermore, based on the improved processability and reduced weight, the running net chassis can be additionally applied to various environmentally friendly vehicle net chassis models.

[0091] Although the embodiments of the present invention have been described with reference to the accompanying drawings, it is obvious to those skilled in the art that various changes or modifications may be made without departing from the spirit and scope of the present invention, without being limited to the exemplary embodiments disclosed herein. Therefore, it should be noted that such replacement or modification falls within the claims of the present invention, and the scope of the present invention should be interpreted based on the appended claims.

Claims

1. A net chassis assembly, comprising: a front frame on which the front suspension is mounted; A rear frame assembly, on which a battery bracket is mounted, wherein the rear frame assembly comprises: a first rear frame on which a rear suspension is mounted, the first rear frame comprising a lower frame and an upper frame; a second rear frame coupled to the first rear frame and having a radiator mounted on the second rear frame; a battery carrier frame on which the battery carrier is mounted, the battery carrier frame being coupled to the first rear frame via a second joint; the lower frame forming the lower portion and on which the rear suspension is mounted; and the upper frame forming an upper portion, wherein the upper frame comprises a grid structure, wherein the grid structure comprises a first upper frame and a second upper frame, the first upper frames being spaced apart from each other in a longitudinal direction of the first rear frame, and the second upper frames being spaced apart from each other in a width direction of the first rear frame; and A center frame is coupled to the front frame and the rear frame assembly by a first joint, wherein a stress distribution caused by the first joint is greater than a stress distribution caused by the second joint.

2. The clean chassis assembly of claim 1, further comprising a center bridge connected between the front frame and the rear frame assembly.

3. The clean chassis assembly according to claim 1, wherein: The front frame comprises: a front suspension mounting portion on which the front suspension is mounted; and An air tank mounting portion is formed on the front frame and is configured to allow an air tank to be mounted above the front frame.

4. The clean chassis assembly according to claim 1, wherein: The center frame includes a lattice structure, wherein the lattice structure includes longitudinal frames and transverse frames, the longitudinal frames are formed and arranged to be spaced apart from each other in a longitudinal direction of the center frame, and the transverse frames are formed and arranged to be spaced apart from each other in a width direction of the center frame. 5 . The clean chassis assembly according to claim 1 , further comprising a plate-like forklift mounting guide in a lower end portion of the battery bracket frame, the forklift mounting guide extending in a width direction of the battery bracket frame.

6. The clean chassis assembly according to claim 1, wherein: The first joint is a welded joint and the second joint is a bolted joint.

7. The clean chassis assembly according to claim 1, wherein: The front suspension is an independent suspension and the rear suspension is a rigid axle.

8. The clean chassis assembly according to claim 1, wherein: The second rear frame includes a grid-like low-floor frame forming a lower surface and a plurality of vertical frames formed vertically upward from the low-floor frame.

9. The clean chassis assembly according to claim 8, wherein: Each upper end of the plurality of vertical frames is coupled to a lower end of the first rear frame through the first joint.

10. The clean chassis assembly according to claim 9, wherein: A module upper side joint portion protruding downward is formed in the first upper frame and is configured to be bolted to a radiator upper side joint portion above the radiator; A module lower side joint portion protruding upward is formed in the low floor frame and is configured to be bolt-coupled with a radiator lower side joint portion below the radiator.

11. The clean chassis assembly according to claim 10, wherein: The module upper side joint portion and the radiator upper side joint portion are connected by bolts passing through the rear frame assembly in the width direction of the rear frame assembly; The module lower side joint portion and the radiator lower side joint portion are coupled by bolts penetrating the rear frame assembly in a height direction of the rear frame assembly.

12. The clean chassis assembly of claim 1, wherein: The guide plate is coupled to the second upper frame, extends in a longitudinal direction of the second upper frame, and protrudes upward from the second upper frame.

13. The clean chassis assembly according to claim 12, wherein: a stopper coupled to the first upper frame and projecting upwardly from the first upper frame; A guide pin disposed on the first upper frame is coupled to one side of the stopper.

14. A method for manufacturing a net chassis assembly, the method comprising: manufacturing a front frame on which the front suspension is mounted; Manufacturing a rear frame assembly, comprising: coupling a second rear frame having a radiator mounted thereon to a first rear frame having a rear suspension mounted thereon by a first joint; and coupling a battery bracket frame having a battery bracket mounted thereon to the first rear frame by a second joint; manufacturing a center frame to connect the front frame to the rear frame assembly; and The front frame, the rear frame assembly, and the center frame are coupled by the first joint, wherein a stress distribution caused by the first joint is greater than a stress distribution caused by the second joint, Wherein, the first rear frame comprises: a lower frame forming the lower portion and on which the rear suspension is mounted; and an upper frame forming an upper portion, wherein the upper frame comprises a grid structure, wherein the grid structure comprises a first upper frame and a second upper frame, the first upper frames being spaced apart from each other in a longitudinal direction of the first rear frame, and the second upper frames being spaced apart from each other in a width direction of the first rear frame.

15. The method for manufacturing a bare chassis assembly according to claim 14, further comprising connecting a center bridge between the front frame and the rear frame assembly.

16. The method for manufacturing a clean chassis assembly according to claim 15, wherein: The first joining is a welding joining method, and the second joining is a bolting joining method.

17. The method for manufacturing a clean chassis assembly according to claim 14, wherein: The front suspension is an independent suspension and the rear suspension is a rigid axle.

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