Connecting piece, connecting method, vehicle lower vehicle body structure and vehicle wheelbase adjusting method

Abstract

The invention discloses a connecting piece, a connecting method, a lower vehicle body structure of a vehicle and a vehicle wheelbase adjusting method. The connecting piece comprises a bottom plate and a connecting structure arranged on the surface of the bottom plate, the bottom plate is of a central symmetry structure and is used for being fixedly connected with a first component. The connecting structure is used for being fixedly connected with a second component; if the connecting structure is rotated by 180 degrees around the first shaft, the position state of the connecting structure after rotation can be coincided with the position state before rotation after translation in the first direction; the first shaft passes through the symmetry center of the bottom plate and is perpendicular to the plate face of the bottom plate, and the first direction is parallel to the plate face of the bottom plate. By rotating the connecting piece around the first shaft, the position state of the bottom plate is not changed before and after rotation, only the position of the connecting structure is translated before and after rotation, and other positions are not changed; therefore, under the condition that the structures of the first component, the second component and the adapter are not changed, two integral structures are formed after final connection.

Description

Technical Field

[0001] The present invention relates to the technical field of installation and connection, and in particular to a connecting piece, a connecting method, a vehicle lower body structure and a vehicle wheelbase adjustment method. Background Art

[0002] The main function of a connector is to achieve a connection transition between two components. When the structures of the two connected components remain unchanged, there is usually only one corresponding connection method, that is, the overall structure formed after the connection is unique. It cannot be applied to application scenarios where two components are connected by the same connector and the relative positions of the two components can be adjusted in a certain direction. Summary of the invention

[0003] The problem to be solved by the present invention is to provide a connecting piece, a connecting method, a vehicle lower body structure and a vehicle wheelbase adjustment method. When the connecting piece connects two parts, it can form two final overall structures by rotating itself.

[0004] In order to solve the above technical problems, the present invention provides a connecting member, including a bottom plate and a connecting structure arranged on the bottom plate surface; the bottom plate is a centrally symmetrical structure, used for fixedly connecting with a first component; the connecting structure is used for fixedly connecting with a second component;

[0005] If the connection structure is rotated 180° around the first axis, the position state of the connection structure after rotation can be translated along the first direction to coincide with the position state before rotation; the first axis passes through the symmetry center of the bottom plate and is perpendicular to the bottom plate surface, and the first direction is parallel to the bottom plate surface;

[0006] When the connecting piece is used to connect the first component and the second component, two connection states can be formed. The first component and the second component in the two connection states have different relative positions in the first direction, and the first component and the second component in the two connection states only have different relative positions in the first direction, and are the same in other aspects.

[0007] In the above-mentioned connecting member, when the connecting member is rotated around the first axis, the position state of the base plate before and after the rotation remains unchanged due to the central symmetric structure, that is, the connection with the first component before and after the rotation can remain unchanged; and since the position state of the connecting structure before and after the rotation can be overlapped by translation along the first direction, the connection with the second component before and after the rotation only undergoes a translation change in position, and the rest remains unchanged; therefore, when the connecting member is used to connect the first component and the second component, the connecting member is rotated 108° around the first axis, so that the second component is translated relative to the first component in the first direction for a certain distance while the base plate on the first component is kept fixed in position and unchanged in state, that is, the first component and the second component can form two connection states, and the relative positions of the two components in the first direction are different in these two connection states.

[0008] In the case that the structures of the first component, the second component and the adapter remain unchanged, there are two overall structures after the final connection, which is suitable for the connection situation where the relative position of the first component and the second component needs to be adjustable in the first direction.

[0009] It should be noted that the connection between the connecting member and the first component and the second component will not be affected by the rotation of the connecting member, that is, compared with before rotation, the second component needs to be translated before connecting to the connecting member, and there will be no interference or other situations that affect the connection.

[0010] As an improvement of the connecting piece of the present invention, the connecting structure includes a plurality of connecting units, and the connecting units are evenly spaced and arranged on one side of the symmetrical center of the bottom plate.

[0011] The connection structure is formed by connecting units arranged in a uniformly spaced arrangement, and each connecting unit has the same structure, so that it is easy to achieve the overlap of the position states before and after rotation around the first axis through translation.

[0012] Furthermore, the arrangement direction of the plurality of connection units is perpendicular to the first direction. Preferably, the symmetry center of the bottom plate is located on the symmetry plane of the arrangement of the connection units.

[0013] Furthermore, the connecting unit includes a boss disposed on a side surface of the bottom plate, and a mounting hole for fixed connection with the second component is formed on a top surface of the boss.

[0014] Preferably, the mounting hole is a threaded hole with an axis perpendicular to the bottom plate surface; the boss is a cylindrical structure and is coaxial with the mounting hole.

[0015] Preferably, ribs are provided between each side surface of the boss and the bottom plate surface to increase structural strength.

[0016] As another improvement of the connector of the present invention, the bottom plate and the first component are connected by welding or riveting. Preferably, the welding points or riveting points are symmetrical about the symmetry center of the bottom plate.

[0017] In order to solve the above technical problems, the present invention provides a connection method based on the above connecting piece, comprising:

[0018] determining a target connection posture of the connector according to a target relative position relationship between the first component and the second component in the first direction;

[0019] According to the target connection posture of the connecting member, the connecting member is fixedly connected to the first component through the bottom plate;

[0020] According to the target connection posture of the connecting member, the connecting member is fixedly connected to the second component through the connecting structure;

[0021] There are two connection postures of the connection piece, and the connection structures of the two connection postures are respectively located on both sides of the symmetry center of the bottom plate in the first direction.

[0022] In the above connection method, according to the relative position requirement in the first direction when the first component and the second component are connected, it is determined that one of the two connection postures is selected as the target connection posture when the connector is connected to perform the connection.

[0023] In order to solve the above technical problems, the present invention also provides a vehicle underbody structure on the one hand, including a left longitudinal beam, a right longitudinal beam, a CTC battery pack assembly and a rear floor assembly; the CTC battery pack assembly includes a battery cell and a front floor, and both side edges are fixedly connected to the left longitudinal beam and the right longitudinal beam respectively; the front end sides of the rear floor assembly are fixedly connected to the left longitudinal beam and the right longitudinal beam respectively, and the fixed connection position can be adjusted along the longitudinal direction of the vehicle body; the middle part of the front end of the rear floor assembly is fixedly connected to the rear end of the CTC battery pack assembly through the connecting piece as mentioned above; the first direction is along the longitudinal direction of the vehicle body.

[0024] Preferably, the CTC battery pack assembly uses CTC technology to integrate the front floor and seat crossbeam on the upper box cover of the battery pack; the battery pack uses a square battery module.

[0025] CTC (Cell to Chassis) battery and "chassis" integrated technology, that is, eliminating the Pack design and directly integrating the battery cell into the lower body, is a physical-level structural innovation that integrates the battery and body structure at the same time. It removes redundancy to obtain more battery cell layout space and is an effective way to increase vehicle range. However, there is currently no body structure on the market that uses an integrated CTC battery pack to achieve wheelbase expansion without changing the integrated body parts. Therefore, for different wheelbase models, the corresponding body structure and CTC battery pack must be customized, and new molds must be invested, which is very expensive.

[0026] In the above-mentioned vehicle lower body structure, the rear floor assembly and the CTC battery pack assembly are transitionally connected by a connector. During installation, the connector can be rotated and adjusted to allow the two to have two connection states. Since the first direction is along the longitudinal direction of the vehicle body, the two connection states have different total lengths along the longitudinal direction of the vehicle body. Therefore, during the installation process, when adjusting the installation position of the rear floor assembly relative to the left and right longitudinal beams along the longitudinal direction of the vehicle body, the installation gap between the rear floor assembly and the CTC battery pack assembly caused by the position adjustment can be compensated by rotating and adjusting the connector, keeping the CTC battery pack assembly, the rear floor assembly, and the connector structure unchanged. The vehicle wheelbase can be adjusted without developing new products or molds, saving costs.

[0027] As an improvement to the lower body structure of the vehicle of the present invention, the position of the connecting member fixed on the rear floor assembly can be adjusted along the longitudinal direction of the vehicle body, that is, the position of the connecting member on the rear floor assembly can be adjusted within a certain range in both the front and rear states of the connecting member.

[0028] During the installation process, when adjusting the installation position of the rear floor assembly relative to the left and right longitudinal beams along the longitudinal direction of the vehicle body, the connecting piece is rotated to adjust the position of the bottom plate fixed on the rear floor assembly along the longitudinal direction of the vehicle body. This can compensate for the installation gap between the rear floor assembly and the CTC battery pack assembly caused by the position adjustment of the rear floor assembly within a certain size range, thereby ultimately achieving a wider adjustable range of the vehicle wheelbase and making the actual adjustable wheelbase design more flexible.

[0029] Preferably, the rear floor assembly includes a rear floor body, and a connecting plate is provided at the front end of the rear floor body; one side surface of the connecting plate is horizontal, and the horizontal surface is used to fit and fix with the surface of the bottom plate, and the position of the bottom plate fixed on the horizontal surface can be adjusted along the longitudinal direction of the vehicle body. Preferably, the bottom surface of the connecting plate is fit and fixed with the bottom plate.

[0030] The bottom plate is fixed on the horizontal plate surface of the connecting plate, and the fixing connection is easy and the position is convenient to adjust along the longitudinal direction of the vehicle body. It should be noted that the position of the bottom plate fixed on the connecting plate is adjusted along the longitudinal direction of the vehicle body without affecting the connection between the connector and the CTC battery pack assembly.

[0031] As another improvement of the lower body structure of the vehicle of the present invention, a first bolt hole group is provided at the end of the left longitudinal beam, the first bolt hole group includes a plurality of bolt holes evenly spaced along the longitudinal direction of the vehicle body, the first bolt hole group is used for fixed connection with the front end side of the rear floor assembly, and the number of bolt holes in the first bolt hole group is greater than the number of bolt holes corresponding to the rear floor assembly.

[0032] During installation, by changing the specific fastening bolt holes used when connecting the rear floor assembly to the first bolt hole group, the fixed connection position of the rear floor assembly to the left longitudinal beam can be adjusted along the longitudinal direction of the vehicle body.

[0033] Furthermore, a second bolt hole group is provided at the end of the right longitudinal beam, the second bolt hole group includes a plurality of bolt holes evenly spaced along the longitudinal direction of the vehicle body, the second bolt hole group is used to be fixedly connected to the front end side of the rear floor assembly, and the number of bolt holes in the second bolt hole group is greater than the number of bolt holes corresponding to the rear floor assembly. The structure of the right longitudinal beam is symmetrical to that of the left longitudinal beam.

[0034] Furthermore, a left connecting beam and a right connecting beam are respectively provided on both sides of the front end of the rear floor body, and the left connecting beam is used for fixed connection with the end of the left longitudinal beam; the right connecting beam is used for fixed connection with the end of the right longitudinal beam.

[0035] Preferably, the left connecting beam, the right connecting beam and the connecting plate are arranged in a concave shape. The main body of the left connecting beam is fixedly connected to the inner side of the left longitudinal beam; the main body of the right connecting beam is fixedly connected to the inner side of the right longitudinal beam.

[0036] As another improvement to the lower body structure of the vehicle of the present invention, the fixed connection position of the CTC battery pack assembly on the left longitudinal beam and the right longitudinal beam can be adjusted along the longitudinal direction of the vehicle body.

[0037] By rotating the adjustment connector, the position of the bottom plate fixed on the horizontal surface of the connecting plate is adjusted longitudinally along the vehicle body, and the fixed position of the CTC battery pack assembly on the left longitudinal beam and the right longitudinal beam is adjusted longitudinally along the vehicle body, so that the rear floor assembly has a larger adjustment range relative to the left longitudinal beam and the right longitudinal beam, thereby further widening the vehicle wheelbase adjustment range.

[0038] Furthermore, the vehicle lower body structure also includes a cabin assembly, and the two sides of the rear end of the cabin assembly are respectively fixedly connected to the left longitudinal beam and the right longitudinal beam; the middle part of the rear end of the cabin assembly is fixedly connected to the front end of the CTC battery pack assembly through the connecting piece as mentioned above.

[0039] Preferably, the position at which the connecting member is fixed to the cabin assembly can be adjusted along the longitudinal direction of the vehicle body.

[0040] The front end of the CTC battery pack assembly is connected to the cabin assembly through a connector, which can make up for the gap caused by the adjustment of the CTC battery pack assembly relative to the longitudinal beam. Together with the connector at the rear end, it further enables the vehicle to have a wider adjustable wheelbase range.

[0041] Preferably, the fixed connection positions of the two sides of the rear end of the cabin assembly with the left longitudinal beam and the right longitudinal beam are respectively unadjustable. The cabin assembly involves the installation of many parts such as the cab, so it is better to design it to be unadjustable relative to the longitudinal beam.

[0042] Furthermore, a third bolt hole group is provided in the middle portion of the left longitudinal beam, and the third bolt hole group includes a plurality of bolt holes evenly spaced along the longitudinal direction of the vehicle body, and the third bolt hole group is used for fixed connection with one side of the CTC battery pack assembly, and the number of bolt holes in the third bolt hole group is greater than the number of bolt holes corresponding to the CTC battery pack assembly.

[0043] During installation, by changing the specific fastening bolt holes used when connecting the CTC battery pack assembly to the left longitudinal beam, the fixed connection position of the CTC battery pack assembly and the left longitudinal beam can be adjusted along the longitudinal direction of the vehicle body.

[0044] Preferably, a fourth bolt hole group is provided in the middle portion of the right longitudinal beam, and the fourth bolt hole group includes a plurality of bolt holes evenly spaced along the longitudinal direction of the vehicle body, and the fourth bolt hole group is used for fixed connection with one side of the CTC battery pack assembly, and the number of bolt holes in the fourth bolt hole group is greater than the number of bolt holes corresponding to the CTC battery pack assembly.

[0045] As another improvement to the lower body structure of the vehicle of the present invention, both side edges of the bottom plate are along the longitudinal direction of the vehicle body, and a first reinforcing plate is respectively arranged on the two side edges; the plate surface of the first reinforcing plate is perpendicular to the bottom plate, and is used to be fixedly connected to the rear floor assembly; a second reinforcing plate is also arranged on the bottom plate, the plate surface of the second reinforcing plate is perpendicular to the bottom plate, and both ends are respectively fixed to one of the first reinforcing plates; a rib plate is arranged between the second reinforcing plate and the bottom plate.

[0046] The first reinforcing plate and the second reinforcing plate increase the structural strength of the entire connecting member and the reliability of the connection with the rear floor assembly.

[0047] Preferably, the rear floor assembly is provided with a mounting surface which is fitted and fixedly connected to the first reinforcement plate.

[0048] As another improvement of the vehicle lower body structure of the present invention, the cabin assembly, the left longitudinal beam, the right longitudinal beam, the rear floor assembly and the connecting parts are all formed by integrated die casting.

[0049] The traditional body manufacturing route adopts a process method of stamping a single piece first and then welding it into a body assembly. A car is welded from about 500 parts of different shapes and materials. Before the whole vehicle is officially mass-produced, it generally goes through three rounds of matching and debugging for six months, strictly checking and solidifying the manufacturing status materials, tooling equipment, process, product qualification rate, packaging, transportation, etc. of these more than 500 parts, so as to ensure that the final body quality meets the assembly requirements. Recently, one-piece die-casting technology has become a new trend in body manufacturing. One-piece die-casting, one-time molding, without the complicated process of stamping first and then welding. The manufacturing process is extremely simple, with only one part, no need to develop too much tooling equipment, and no error accumulation caused by the connection of a large number of parts. The manufacturing accuracy is controllable. There is no need to check the manufacturing status of each part, which can not only shorten the complex body manufacturing process, but also greatly reduce the manufacturing cost of the body.

[0050] Preferably, the connecting piece and the rear floor assembly are made of aluminum and are fixedly connected by riveting.

[0051] In order to solve the above technical problems, the present invention provides a vehicle wheelbase adjustment method based on the above vehicle lower body structure, comprising: the position of the front end of the rear floor assembly fixedly connected to the left longitudinal beam and the right longitudinal beam is adjusted along the longitudinal direction of the vehicle body, and the gap between the front end of the rear floor assembly and the rear end of the CTC battery pack assembly due to the position adjustment is eliminated by a first method; wherein, the first method comprises rotating the connector fixed to the rear floor assembly by 180° around the first axis. Here, it means that the connector rotates 180° around the first axis on itself.

[0052] Furthermore, the first method also includes: moving and adjusting the connecting piece fixed on the rear floor assembly along the longitudinal direction of the vehicle body, adjusting the fixed connection position of the CTC battery pack assembly on the left longitudinal beam and the right longitudinal beam along the longitudinal direction of the vehicle body, rotating the connecting piece fixed on the cabin assembly 180° around the first axis and moving and adjusting the connecting piece fixed on the cabin assembly along the longitudinal direction of the vehicle body.

[0053] The beneficial effect of the present invention is that when the above-mentioned connecting member is used to connect the first component and the second component, the connecting member is rotated 108° around the first axis, so that the second component can be translated relative to the first component by a certain distance in the first direction while keeping the fixed position and state of the bottom plate on the first component unchanged, that is, the first component and the second component can form two connection states, and the relative position of the first component and the second component in the first direction can be adjusted. The above-mentioned vehicle lower body structure and vehicle wheelbase adjustment method have the advantages of the above-mentioned connection structure, and can adjust the vehicle wheelbase without changing the components of the vehicle lower body structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] In the attached picture:

[0055] Figure 1 This is a structural diagram of the connecting piece of the present invention.

[0056] Figure 2 The connecting member of the present invention is Figure 1 Structural diagram of the state rotated 180° around the first axis.

[0057] Figure 3 This is a bottom structural diagram of the connecting piece of the present invention.

[0058] Figure 4 It is a structural diagram of the lower body structure of the vehicle of the present invention.

[0059] Figure 5 It is a disassembled structural diagram of the lower body structure of the vehicle of the present invention.

[0060] Figure 6 This is a structural diagram of the rear floor assembly of the vehicle lower body structure of the present invention.

[0061] Figure 7 This is a structural diagram of the connection member of the vehicle lower body structure of the present invention installed at the bottom of the rear floor assembly.

[0062] Figure 8 for Figure 7 Schematic diagram of the splitting.

[0063] Fig. 9 for Figure 7 Structural diagram after the connecting member in FIG. is rotated 180° around the first axis.

[0064] Fig.10 It is a structural diagram of the left longitudinal beam of the lower body structure of the vehicle of the present invention.

[0065] Fig.11 This is a bottom structural diagram of the left longitudinal beam of the lower body structure of the vehicle of the present invention.

[0066] Fig.12 This is a structural diagram of the CTC battery pack assembly of the lower body structure of the vehicle of the present invention.

[0067] Fig.13 The figure is a schematic diagram of the connection of the components of the vehicle wheelbase adjustment method of the present invention.

[0068] Fig.14 This is a schematic diagram of the first connection state of two components of the connection method of the present invention.

[0069] Fig.15 This is a schematic diagram of the second connection state of two components of the connection method of the present invention.

[0070] In the figure, 1. left longitudinal beam; 11. first bolt hole group; 12. third bolt hole group; 13. fifth bolt hole group; 101. outer rectangular beam; 102. inner rectangular beam; 2. right longitudinal beam; 3. CTC battery pack assembly; 31. fixed connecting ear; 4. rear floor assembly; 41. rear floor body; 42. left connecting beam; 43. right connecting beam; 44. connecting plate; 5. cabin assembly; 6. connecting part; 61. bottom plate; 62. boss; 621. mounting hole; 63. first reinforcing plate; 64. second reinforcing plate; 651. connecting rib; 652. combined rib; 66. connecting structure; 71. first axis; 72. first direction; 73. first component; 73. second component. DETAILED DESCRIPTION

[0071] The specific embodiments of the present invention are further described below in conjunction with the accompanying drawings. It should be noted that the description of these embodiments is used to help understand the present invention, but does not constitute a limitation of the present invention.

[0072] Example 1

[0073] Figure 1-3A connecting member 6 of the present invention is shown. Figure 1-3 As shown, the connecting member 6 includes a bottom plate 61 and a connecting structure arranged on the surface of the bottom plate 61; the bottom plate 61 is a centrally symmetrical structure, used for fixed connection with the first component; the connecting structure is used for fixed connection with the second component. If the connecting structure is rotated 180° around the first axis 71, the position state of the connecting structure after rotation can be translated along the first direction 72 to coincide with the position state before rotation; the first axis 71 passes through the symmetry center of the bottom plate 61 and is perpendicular to the surface of the bottom plate 61, and the first direction 72 is parallel to the surface of the bottom plate 61.

[0074] When in use, the first component and the second component have two connection states, and the corresponding connecting members 6 are respectively as follows: Figure 1 and Figure 2 In the two states shown in FIG. 1 , in the two connection states, the connection structure between the first component and the bottom plate 61 is the same, and the connection structure between the second component and the connection structure is also the same. The only difference is that the relative positions of the first component and the second component in the first direction are different, such as Figure 7 and Fig. 9 as shown in .

[0075] In some embodiments, the connection structure includes a plurality of connection units, which are arranged evenly at intervals on one side of the symmetry center of the bottom plate 61. The arrangement direction of the connection units is perpendicular to the first direction 72. The symmetry center of the bottom plate 61 is located on the symmetry plane of the connection units. The connection structure is formed by the connection units arranged evenly at intervals, and each connection unit has the same structure, so that it is easy to achieve the overlap of the position state before and after the rotation around the first axis 71 through translation.

[0076] In some embodiments, the connection unit includes a boss 62 disposed on a side surface of the bottom plate 61 , and a mounting hole 621 for fixed connection with the second component is formed on the top surface of the boss 62 .

[0077] Optionally, the mounting hole 621 is a threaded hole with an axis perpendicular to the surface of the bottom plate 61 ; the boss 62 is a cylindrical structure and is coaxial with the mounting hole 621 .

[0078] Optionally, ribs are provided between the side surface of each boss 62 and the surface of the bottom plate 61 to increase structural strength.

[0079] In some embodiments, the bottom plate 61 is connected to the first component by welding or riveting, and the connection structure is simple, which has little effect on the fixed connection between the second component and the connection structure after movement.

[0080] Optionally, the welding points or riveting points between the base plate 61 and the first component are symmetrical about the symmetry center of the base plate 61, so that the positions of the welding points or riveting points are constant before and after rotation, that is, the connection operation between the base plate 61 and the first component remains unchanged before and after the connecting member 6 rotates.

[0081] Example 2

[0082] The present invention provides a connection method based on the above-mentioned connection member 6, comprising the following steps S10-S30. Figure 1 and Figure 2 There are two connection postures of the connecting member 6. The connection structures 66 of the two connection postures are respectively located on both sides of the symmetric center of the bottom plate 61 in the first direction, correspondingly forming Fig.14 and Fig.15 The two connection states shown in FIG. 7 form two relative positional relationships between the first component 73 and the second component 74 in the first direction. Fig.14 and Fig.15 The first component 73, the second component 74 and the connecting member 6 are abstracted, mainly expressing the relative positions and connection relationships in the first direction, and the dotted lines represent fixed connections.

[0083] Step S10: Determine the target connection posture of the connector 6 according to the target relative position relationship between the first component 73 and the second component 74 in the first direction. There are two types of target relative position relationships between the first component 73 and the second component 74 in the first direction. One type is a distance d1, such as Fig.14 As shown, the corresponding connection structure 66 of the connection member 6 is located on the right side of the supporting center of the bottom plate 61; another distance d2, such as Fig.15 As shown, the corresponding connection structure 66 of the connection member 6 is located on the left side of the supporting center of the bottom plate 61.

[0084] Step S20 : ​​According to the target connection posture of the connecting member 6 , the connecting member 6 is fixedly connected to the first component 73 via the bottom plate 61 .

[0085] Step S30 : According to the target connection posture of the connecting member 6 , the connecting member 6 is fixedly connected to the second component 74 via the connecting structure 66 .

[0086] When connecting, first determine one of the two connection postures as the target connection posture when the connector is connected based on the relative position relationship requirement in the first direction when the first component 73 and the second component 74 are connected, that is, the target relative position relationship, and then connect. Note that in both connection states, the connection position and method of the base plate 61 of the adapter 6 and the first component 73 remain unchanged. Similarly, the connection position and method of the connection structure 66 of the adapter 6 and the second component 74 remain unchanged.

[0087] Example 3

[0088] Figure 1-12 FIG. 1 shows a vehicle lower body structure of the present invention. Figure 1-12As shown, the lower body structure of the vehicle includes a left longitudinal beam 1, a right longitudinal beam 2, a CTC battery pack assembly 3 and a rear floor assembly 4; the CTC battery pack assembly 3 includes a battery cell and a front floor, and both side edges are fixedly connected to the left longitudinal beam 1 and the right longitudinal beam 2 respectively; the front end sides of the rear floor assembly 4 are fixedly connected to the left longitudinal beam 1 and the right longitudinal beam 2 respectively, and the fixed connection position can be adjusted along the longitudinal direction of the vehicle body; the front end middle part of the rear floor assembly 4 is fixedly connected to the rear end of the CTC battery pack assembly 3 through the above-mentioned connecting member 6; the first direction is along the longitudinal direction of the vehicle body.

[0089] When adjusting the fixed connection position between the rear floor assembly 4 and the left longitudinal beam 1 and the right longitudinal beam 2, the rear wheel axle and corresponding suspension structures can be installed at the bottom of the rear floor assembly 4, so the vehicle wheelbase can be adjusted; and while keeping the fixed connection position between the CTC battery pack assembly 3 and the left longitudinal beam 1 and the right longitudinal beam 2 unchanged, the connector 6 is rotated to make up the gap between the rear floor assembly 4 and the CTC battery pack assembly 3 to ensure the sealing of the vehicle floor after adjusting the wheelbase.

[0090] On the basis of the above structure, if the fixed connection position of the CTC battery pack assembly 3 and the left longitudinal beam 1 and the right longitudinal beam 2 is adjustable, and the position of the connecting member 6 fixed on the rear floor assembly 4 is adjustable, the vehicle wheelbase will have a larger adjustable range.

[0091] like Fig.10 and Fig.11 As shown, a feasible structure of the left longitudinal beam 1 is illustrated. The structure of the right longitudinal beam 2 is symmetrical to that of the left longitudinal beam 1. The structures of the left longitudinal beam 1 and the right longitudinal beam 2 are described in detail below.

[0092] First, the connection structure between the longitudinal beam and the rear floor assembly 4 is described. A first bolt hole group 11 is provided at the end of the left longitudinal beam 1. The first bolt hole group 11 includes a plurality of bolt holes evenly spaced along the longitudinal direction of the vehicle body. The first bolt hole group 11 is used to be fixedly connected to the front end side of the rear floor assembly 4, and the number of bolt holes in the first bolt hole group 11 is greater than the number of bolt holes corresponding to the rear floor assembly 4. Similarly, a second bolt hole group is provided at the end of the right longitudinal beam 2. The second bolt hole group includes a plurality of bolt holes evenly spaced along the longitudinal direction of the vehicle body. The second bolt hole group is used to be fixedly connected to the front end side of the rear floor assembly 4, and the number of bolt holes in the second bolt hole group is greater than the number of bolt holes corresponding to the rear floor assembly 4.

[0093] During installation, by changing the specific fastening bolt holes used by the rear floor assembly 4 and the first bolt hole group 11 and the second bolt hole group, the fixed connection position of the rear floor assembly 4 and the left longitudinal beam 1 can be adjusted along the longitudinal direction of the vehicle body. Fig.10The first bolt hole group 11 shown in the figure has five fastening bolt holes. Assuming that the rear floor assembly 4 has three bolt installation holes corresponding to the left longitudinal beam 1 and the right longitudinal beam 2, then when the rear floor assembly 4 is installed and fastened, the first three bolt holes, the middle three bolt holes, and the rear three bolt holes of the left longitudinal beam 1 and the right longitudinal beam 2 are used in sequence, which will make the rear floor assembly 4 gradually move toward the rear end of the vehicle body relative to the left longitudinal beam 1 to achieve adjustment.

[0094] Next, the connection structure between the longitudinal beam and the CTC battery pack assembly 3 is described. A third bolt hole group 12 is provided in the middle of the left longitudinal beam 1. The third bolt hole group 12 includes a plurality of bolt holes evenly spaced along the longitudinal direction of the vehicle body. The third bolt hole group 12 is used to be fixedly connected to one side of the CTC battery pack assembly 3, and the number of bolt holes in the third bolt hole group 12 is greater than the number of bolt holes corresponding to the CTC battery pack assembly 3.

[0095] Similarly, a fourth bolt hole group is provided in the middle of the right longitudinal beam 2, and the fourth bolt hole group includes a plurality of bolt holes evenly spaced along the longitudinal direction of the vehicle body. The fourth bolt hole group is used to be fixedly connected to one side of the CTC battery pack assembly 3, and the number of bolt holes in the fourth bolt hole group is greater than the number of bolt holes corresponding to the CTC battery pack assembly 3.

[0096] Similar to the first bolt hole group 11 and the second bolt hole group, during installation, the CTC battery pack assembly 3 can be adjusted along the longitudinal direction of the vehicle body by adjusting the bolt holes corresponding to the left longitudinal beam 1 and the right longitudinal beam 2 of the CTC battery pack assembly 3.

[0097] The fixed connection position of the CTC battery pack assembly 3 on the left longitudinal beam 1 and the right longitudinal beam 2 can be adjusted along the longitudinal direction of the vehicle body. By rotating and adjusting the connecting piece 6, the position of the bottom plate 61 fixed on the horizontal plate surface of the connecting plate 44 is adjusted along the longitudinal direction of the vehicle body, and then the fixed position of the CTC battery pack assembly 3 on the left longitudinal beam 1 and the right longitudinal beam 2 is adjusted along the longitudinal direction of the vehicle body, so that the rear floor assembly 4 has a larger adjustment range relative to the left longitudinal beam 1 and the right longitudinal beam 2, thereby further widening the vehicle wheelbase adjustment range.

[0098] Next, the connection structure between the longitudinal beam and the cabin assembly 5 is described. Since the cabin assembly 5 involves the installation of many parts such as the cab, it is better to design the position relative to the longitudinal beam to be non-adjustable, and generally fixedly connected by bolts. Specifically, a fifth bolt hole group 13 is set at the front end of the left longitudinal beam 1, and a sixth bolt hole group is set at the front end of the right longitudinal beam 2, which are used to be fixedly connected to both sides of the rear end of the cabin assembly 5.

[0099] Finally, the longitudinal beam structure itself is described. The present invention does not limit the structural style of the left longitudinal beam 1 and the right longitudinal beam 2, because in theory, any longitudinal beam structure that can achieve the connection relationship with other components of the present invention and meet the design requirements of vehicle strength can be used. Fig.10and Fig.11 The structure of the left longitudinal beam 1 in the figure is only a schematic diagram of a feasible solution. The left longitudinal beam 1 includes an outer rectangular beam 101 and a smaller inner rectangular beam 102. The first bolt hole group 11, the third bolt hole group 12 and the fifth bolt hole group 13 are arranged at both ends and in the middle of the inner rectangular beam 102. In addition, Fig.10 The left longitudinal beam 1 structure is compared with Figure 5 There are some differences in the diagram, which are caused by removing some connection structures with the frame. There are similar differences in the front and rear figures of other parts, which does not affect the understanding of the present invention.

[0100] like Fig.12 As shown, a feasible structure of the CTC battery pack assembly 3 is illustrated. The CTC battery pack assembly 3 uses CTC technology to integrate the front floor and the seat crossbeam on the upper box cover of the battery pack; the battery pack uses a square battery module. CTC technology is currently developing rapidly and has been widely used in complete machine manufacturers such as BYD, Leapmotor and Tesla. It will not be discussed in depth. The following mainly describes the connection structure of the CTC battery pack assembly 3 and other components of the present invention.

[0101] The entire CTC battery pack assembly 3 is rectangular, and a plurality of fixed connection ears 31 are provided on each outer side. Each fixed connection ear 31 is provided with a mounting through hole for fixed connection with the left longitudinal beam 1, the right longitudinal beam 2, the connecting member 6 on the rear floor assembly 4, and the connecting member 6 on the cabin assembly 5. Usually, the fixing and installation is performed by driving bolts, and the mounting through holes on the fixed connection ears 31 are threaded through holes. The bolt holes of the corresponding third bolt hole group 12 on the left longitudinal beam 1, the bolt holes of the corresponding fourth bolt hole group on the right longitudinal beam 2, the corresponding mounting holes 621 on the rear floor assembly 4, and the corresponding mounting holes 621 on the cabin assembly 5 are all threaded blind holes. After the CTC battery pack assembly 3 is placed in place, a screw is screwed into the mounting through hole on each fixed connection ear 31, and finally tightened into the corresponding bolt holes of the corresponding third bolt hole group 12 on the left longitudinal beam 1, the bolt holes of the corresponding fourth bolt hole group on the right longitudinal beam 2, the corresponding mounting holes 621 on the rear floor assembly 4, or the corresponding mounting holes 621 on the cabin assembly 5 to achieve fixed installation.

[0102] like Figure 6-9 As shown, a feasible structure of the rear floor assembly 4 is illustrated. First, the connection structure between the rear floor assembly 4 and the bottom plate 61 is described. The rear floor assembly 4 includes a rear floor body 41, and a connecting plate 44 is provided at the front end of the rear floor body 41; one side of the connecting plate 44 is horizontal, and the horizontal plate surface is used to fit and fix with the plate surface of the bottom plate 61, and the position of the bottom plate 61 fixed on the horizontal plate surface can be adjusted along the longitudinal direction of the vehicle body. The two plates are easily fitted and fixed, and the fixed position is convenient to adjust along the longitudinal direction of the vehicle body, and can be directly translated.

[0103] The position where the connector 6 is fixed on the rear floor assembly 4 can be adjusted in the longitudinal direction of the vehicle body, that is, the fixed position of the bottom plate 61 of the connector 6 on the rear floor assembly 4 can be adjusted, so that the connector 6 can be flipped between the front and rear states, and the position on the rear floor assembly 4 can be adjusted within a certain range. Therefore, during the installation process, when adjusting the installation position of the rear floor assembly 4 relative to the left longitudinal beam 1 and the right longitudinal beam 2 along the longitudinal direction of the vehicle body, by rotating and adjusting the connector 6, the position where the bottom plate 61 is fixed on the rear floor assembly 4 can be adjusted along the longitudinal direction of the vehicle body, which can compensate for the installation gap between the rear floor assembly 4 and the CTC battery pack assembly 3 caused by the position adjustment of the rear floor assembly 4 within a certain size range, so that the vehicle wheelbase can be adjusted in a wider range, and the actual design of adjustable wheelbase is more flexible.

[0104] In addition, in order to ensure the connection strength, the bottom plate 61 is required to completely overlap with the connecting plate 44 during the movement and adjustment process. The width of the connecting plate 44 along the longitudinal direction of the vehicle body can be designed to be greater than the bottom plate 61, and the excess size is the adjustable range. In addition, it should be noted that the position where the bottom plate 61 is fixed on the connecting plate 44 is adjusted along the longitudinal direction of the vehicle body, which does not affect the connection between the connector 6 and the CTC battery pack assembly 3, and can be easily avoided through structural design. The rear floor assembly 4 is provided with a mounting surface that is fitted and fixedly connected to the first reinforcing plate 63. As shown Figure 8 As shown, vertical plates are vertically arranged on both side edges of the connecting plate 44 for fixed connection with the first reinforcing plate 63 .

[0105] Next, the connection structure between the rear floor assembly 4 and the longitudinal beam is described. A left connecting beam 42 and a right connecting beam 43 are respectively provided on both sides of the front end of the rear floor body 41. The left connecting beam 42 is used to be fixedly connected to the end of the left longitudinal beam 1; the right connecting beam 43 is used to be fixedly connected to the end of the right longitudinal beam 2.

[0106] Finally, the structure of the rear floor main body 41 is described. The present invention does not limit the specific structure of the rear floor assembly 4, but only limits its connection relationship with the bottom plate 61, the left longitudinal beam 1 and the right longitudinal beam 2 to achieve the final adjustable vehicle wheelbase, so the specific structure given in 6-9 is only a feasible structure.

[0107] The bottom surface of the connecting plate 44 is fitted and fixedly connected to the bottom plate 61. The left connecting beam 42, the right connecting beam 43 and the connecting plate 44 are arranged in a concave shape; the two ends of the connecting plate 44 are located at the root bottom surface of the left connecting beam 42 and the right connecting beam 43. The main body outer side surface of the left connecting beam 42 is in an inverted L shape, fitted and fixedly connected to the inner side surface and top surface of the rear end of the left longitudinal beam 1; the main body outer side surface of the right connecting beam 43 is in an inverted L shape, fitted and fixedly connected to the inner side surface and top surface of the rear end of the right longitudinal beam 2. The L-shaped overlapped fixed connection structure is more secure. The first bolt hole group 11 includes bolt holes arranged on the inner side surface and top surface of the rear end of the left longitudinal beam 1.

[0108] like Figure 4 and Figure 5 As shown, the lower body structure of the vehicle also includes a cabin assembly 5, the two sides of the rear end of the cabin assembly 5 are respectively fixedly connected to the left longitudinal beam 1 and the right longitudinal beam 2, and the middle of the rear end is connected to the CTC battery pack assembly 3, forming a complete bottom frame structure.

[0109] In order to make up for the gap caused by the movement of the CTC battery pack assembly 3, the middle of the rear end of the cabin assembly 5 is fixedly connected to the front end of the CTC battery pack assembly 3 through the connecting piece 6 as mentioned above. The position at which the connecting piece 6 is fixed on the cabin assembly 5 can be adjusted along the longitudinal direction of the vehicle body. In this way, the front end of the CTC battery pack assembly 3 is connected and transitioned through the connecting piece 6 like the rear end, which can make up for the larger gap caused by the movement of the CTC battery pack assembly 3, and further make the vehicle have a wider adjustable wheelbase range. The specific connection structure of the connecting piece 6 and the cabin assembly 5 refers to the connection structure with the rear floor assembly 4, and will not be described in detail.

[0110] like Figure 1-3 As shown, in addition to the structure in Embodiment 1, the connecting member 6 needs to be reinforced according to the actual needs in the lower body structure of the vehicle of the present invention. Both sides of the bottom plate 61 are along the longitudinal direction of the vehicle body, and a first reinforcing plate 63 is respectively provided on both sides; the plate surface of the first reinforcing plate 63 is perpendicular to the bottom plate 61, and is used for fixed connection with the rear floor assembly 4; a second reinforcing plate 64 is also provided on the bottom plate 61, and the plate surface of the second reinforcing plate 64 is perpendicular to the bottom plate 61, and the two ends are respectively fixed on one of the first reinforcing plates 63; a rib is provided between the second reinforcing plate 64 and the bottom plate 61.

[0111] The first reinforcing plate 63 and the second reinforcing plate 64 increase the structural strength of the entire connecting member 6 and the reliability of the connection with the rear floor assembly 4. The first reinforcing plate 63 can be in the shape of a triangle.

[0112] In addition, in order to further strengthen the structure of the adapter, the ribs on it are planned and arranged. Figure 1 As shown, the surface of the second reinforcing plate 64 is arranged along the arrangement direction of the connecting units and is spaced a certain distance apart; a connecting rib 651 is provided between the second reinforcing plate 64 and the boss 62 of each connecting unit, one side of the connecting rib 651 is fixed to the side of the boss 62, the other side is fixed to the second reinforcing plate 64, and the bottom is fixed to the bottom plate 61.

[0113] There are four ribs arranged in a cross shape around each boss 62, including a connecting rib 651, and two ribs have plate surfaces along the arrangement direction of the bosses 62. The ribs with plate surfaces along the arrangement direction of the bosses 62 between two adjacent bosses 62 are connected to each other to form a combined rib 652; the two ribs with plate surfaces along the arrangement direction of the bosses 62 at both ends are respectively connected to the first reinforcing plates 63 on the corresponding sides. The ribs between the second reinforcing plate 64 and the bottom plate 61 are respectively cross-intersected with a combined rib 652. This rib structure on the connector 6 is very easy to process by casting, die casting, etc., and has high structural strength.

[0114] In addition, the cabin assembly 5, the left longitudinal beam 1, the right longitudinal beam 2, the rear floor assembly 4, and the connecting piece 6 are all formed by integrated die casting. The connecting piece 6 and the rear floor assembly 4 are made of aluminum and are fixedly connected by riveting.

[0115] The traditional body manufacturing route adopts a process method of stamping a single piece first and then welding it into a body assembly. A car is welded from about 500 parts of different shapes and materials. Before the whole vehicle is officially mass-produced, it generally goes through three rounds of matching and debugging for six months, strictly checking and solidifying the manufacturing status materials, tooling equipment, process, product qualification rate, packaging, transportation, etc. of these more than 500 parts, so as to ensure that the final body quality meets the assembly requirements. Recently, one-piece die-casting technology has become a new trend in body manufacturing. One-piece die-casting, one-time molding, without the complicated process of stamping first and then welding. The manufacturing process is extremely simple, with only one part, no need to develop too much tooling equipment, and no error accumulation caused by the connection of a large number of parts. The manufacturing accuracy is controllable. There is no need to check the manufacturing status of each part, which can not only shorten the complex body manufacturing process, but also greatly reduce the manufacturing cost of the body.

[0116] For convenience, the left longitudinal beam 1 and the right longitudinal beam 2 are collectively referred to as longitudinal beams. In summary, when the vehicle wheelbase is adjusted using the above-mentioned vehicle lower body structure, since the fixed position of the cabin assembly 5 on the longitudinal beam cannot be adjusted, that is, the position of the vehicle's front wheel axle relative to the longitudinal beam remains unchanged, first adjust the installation position of the rear floor assembly 4 on the longitudinal beam through the first bolt hole group 11 and the second bolt hole group to make the vehicle wheelbase reach the set value; then, by using the position adjustment and rotation adjustment of a connecting member 6 on the rear floor assembly 4, the position adjustment of the CTC battery pack assembly 3 on the longitudinal beam, and the position adjustment and rotation adjustment of another connecting member 6 on the cabin assembly 5, the longitudinal gap between the mounting parts caused by the adjustment of the rear floor assembly 4 can be compensated to ensure reliable floor sealing.

[0117] Example 4

[0118] Fig.13The present invention shows a vehicle wheelbase adjustment method based on the above vehicle lower body structure, including: the position of the front end of the rear floor assembly 4 fixedly connected to the left longitudinal beam 1 and the right longitudinal beam 2 is adjusted along the longitudinal direction of the vehicle body, and the gap between the front end of the rear floor assembly 4 and the rear end of the CTC battery pack assembly 3 due to the position adjustment is eliminated by the first method; wherein the first method includes ① rotating the connector 6 fixed on the rear floor assembly 4 by 180° around the first axis. Here, it means that the connector 6 rotates 180° around the first axis on itself.

[0119] Optionally, the first method also includes: ② moving and adjusting the connecting member 6 fixed on the rear floor assembly 4 along the longitudinal direction of the vehicle body, ③ adjusting the fixed connection position of the CTC battery pack assembly 3 on the left longitudinal beam 1 and the right longitudinal beam 2 along the longitudinal direction of the vehicle body, ④ rotating the connecting member 6 fixed on the cabin assembly 5 180° around the first axis and ⑤ moving and adjusting the connecting member 6 fixed on the cabin assembly 5 along the longitudinal direction of the vehicle body.

[0120] It should be noted that the specific operation methods ①-⑤ in the above-mentioned first method are independent of each other. During a vehicle wheelbase adjustment process, any one or several of the first methods can be used to eliminate the gap between the front end of the rear floor assembly 4 and the rear end of the CTC battery pack assembly 3 due to position adjustment.

[0121] In order to more vividly describe the adjustment process of the vehicle wheelbase, Fig.13 As shown, the various components of the vehicle lower body structure are abstracted, and only the dimensions and relative positional relationships along the vehicle body axis are retained. Fig.13 In the figure, the dotted line indicates a fixed connection between two components, a range interval with a dimension mark at one end of the dotted line indicates that the fixed connection position of the two components is adjustable, and a range interval without a dimension mark at both ends of the dotted line indicates that the fixed connection position of the two components is not adjustable.

[0122] For example, in Fig.13 In the figure, a represents the adjustable range of the fixed position of the rear floor assembly 4 on the left longitudinal beam 1 and the right longitudinal beam 2 along the longitudinal direction of the vehicle body. Since the left longitudinal beam 1 and the right longitudinal beam 2 are connected to the rear floor assembly 4 and the position is adjusted through the bolt hole group, a is a set interval composed of a series of point values, for example, the point values ​​included in a are: 30mm, 50mm, 100mm, 150mm, etc. Note that the adjustment value here is the difference compared to the minimum wheelbase. If the minimum wheelbase is 2800mm, the corresponding wheelbases that can be adjusted are: 2800mm, 2830mm, 2850mm, 2900mm, 2950mm.

[0123] b represents the adjustable range of the fixed position of the bottom plate 61 on the rear connecting plate 44 along the longitudinal direction of the vehicle body, which is a continuous range with the bottom plate 61 fixed at the front end of the connecting plate 44 as the zero reference. For example, b is 0, 100 mm.

[0124] c represents the adjustable range of the fixed position of the CTC battery pack assembly 3 on the left longitudinal beam 1 along the longitudinal direction of the vehicle body, which is a continuous range with the front end position of the CTC battery pack assembly 3 fixed on the left longitudinal beam 1 as the zero reference. For example, c takes the value of 0, 100mm.

[0125] In addition, the connecting member 6 on the rear floor assembly 4 and the cabin assembly 5 can be adjusted by a fixed value d along the longitudinal direction of the vehicle body by rotating around their own first axes. Fig.13 In the state arrangement shown, the connecting structure is at the front end, and the positions of other components remain unchanged. By rotating the connecting member 6 as a whole 180° around the first axis, the fixed connection between the bottom plate 61 and the rear floor assembly 4 remains unchanged, but there will be a gap between the rear end of the CTC battery pack assembly 3 and the connecting structure. To make up for the gap, the position where the rear floor assembly 4 is fixed on the longitudinal beam can be moved forward to shorten the wheelbase. Alternatively, the methods of moving the CTC battery pack assembly 3 and the cabin assembly 5 backward can be combined to keep the wheelbase unchanged.

[0126] In summary, after adjusting the position of the rear floor assembly 4 installed on the longitudinal beam to achieve wheelbase adjustment, the following can be done: ① Rotate the connector 6 fixed on the rear floor assembly 4 180° around the first axis; ② Move and adjust the connector 6 fixed on the rear floor assembly 4 along the longitudinal direction of the vehicle body; ③ Adjust the fixed connection position of the CTC battery pack assembly 3 on the left longitudinal beam 1 and the right longitudinal beam 2 along the longitudinal direction of the vehicle body; ④ Rotate the connector 6 fixed on the cabin assembly 5 180° around the first axis; ⑤ Move and adjust the connector 6 fixed on the cabin assembly 5 along the longitudinal direction of the vehicle body. Any one of these five methods or any combination of them can be used to achieve matching adjustment to ensure the integrity of the floor.

[0127] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit its protection scope. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the field should understand that after reading the present invention, those skilled in the art can still make various changes, modifications or equivalent substitutions to the specific implementation methods of the invention, but these changes, modifications or equivalent substitutions are all within the protection scope of the pending claims of the invention.

Claims

1. A connecting piece (6), characterized in that: It comprises a bottom plate (61) and a connection structure arranged on the surface of the bottom plate (61); the bottom plate (61) is a centrally symmetrical structure and is used for fixed connection with a first component; the connection structure is used for fixed connection with a second component; If the connection structure is rotated 180° around the first axis, the position state of the connection structure after rotation can be overlapped with the position state before rotation by translating along the first direction; the first axis passes through the symmetry center of the bottom plate (61) and is perpendicular to the surface of the bottom plate (61), and the first direction is parallel to the surface of the bottom plate (61); When the connecting member (6) is used to connect the first component and the second component, two connection states can be formed, and the relative positions of the first component and the second component in the first direction are different in the two connection states.

2. A connecting piece (6) according to claim 1, characterized in that: The connection structure comprises a plurality of connection units, which are arranged evenly at intervals on one side of the symmetrical center of the bottom plate (61).

3. A connecting piece (6) according to claim 2, characterized in that: The arrangement direction of the plurality of connection units is perpendicular to the first direction.

4. A connecting piece (6) according to claim 2, characterized in that: The connection unit comprises a boss (62) arranged on a side surface of the bottom plate (61), and a mounting hole (621) for fixed connection with the second component is formed on the top surface of the boss (62).

5. A connection method based on the connection piece (6) according to any one of claims 1 to 4, characterized in that: include: Determining a target connection posture of the connecting member (6) according to a target relative position relationship between the first component and the second component in a first direction; According to the target connection posture of the connection member (6), the connection member (6) is fixedly connected to the first component via the bottom plate (61); According to the target connection posture of the connection member (6), the connection member (6) is fixedly connected to the second component via the connection structure; There are two connection postures of the connection member (6), and the connection structures of the two connection postures are respectively located on both sides of the symmetry center of the bottom plate (61) in the first direction.

6. A vehicle underbody structure, characterized in that: It includes a left longitudinal beam (1), a right longitudinal beam (2), a CTC battery pack assembly (3) and a rear floor assembly (4); The two side edges of the CTC battery pack assembly (3) are respectively fixedly connected to the left longitudinal beam (1) and the right longitudinal beam (2); The front ends of the rear floor assembly (4) are fixedly connected to the left longitudinal beam (1) and the right longitudinal beam (2) respectively, and the fixed connection position can be adjusted along the longitudinal direction of the vehicle body; the front end middle part of the rear floor assembly (4) is fixedly connected to the rear end of the CTC battery pack assembly (3) through the connecting member (6) as described in any one of claims 1 to 4; the first direction is along the longitudinal direction of the vehicle body.

7. A vehicle underbody structure according to claim 6, characterized in that: The position at which the connecting member (6) is fixed to the rear floor assembly (4) can be adjusted in the longitudinal direction of the vehicle body.

8. The vehicle underbody structure according to claim 6, characterized in that: A first bolt hole group (11) is provided at the end of the left longitudinal beam (1), the first bolt hole group (11) comprising a plurality of bolt holes evenly spaced apart in the longitudinal direction of the vehicle body, the first bolt hole group (11) being used for fixed connection with the front end side of the rear floor assembly (4), and the number of bolt holes in the first bolt hole group (11) is greater than the number of bolt holes corresponding to the rear floor assembly (4).

9. The vehicle underbody structure according to claim 6, characterized in that: The fixed connection position of the CTC battery pack assembly (3) on the left longitudinal beam (1) and the right longitudinal beam (2) can be adjusted along the longitudinal direction of the vehicle body.

10. The vehicle underbody structure according to claim 9, characterized in that: It also includes a cabin assembly (5), the two sides of the rear end of the cabin assembly (5) are respectively fixedly connected to the left longitudinal beam (1) and the right longitudinal beam (2); the middle part of the rear end of the cabin assembly (5) is fixedly connected to the front end of the CTC battery pack assembly (3) through a connecting piece (6) as described in any one of claims 1 to 4.

11. A vehicle underbody structure according to claim 10, characterized in that: The position at which the connecting member (6) is fixed to the cabin assembly (5) can be adjusted along the longitudinal direction of the vehicle body.

12. The vehicle underbody structure according to claim 9, characterized in that: A third bolt hole group (12) is provided in the middle of the left longitudinal beam (1), the third bolt hole group (12) comprising a plurality of bolt holes evenly spaced along the longitudinal direction of the vehicle body, the third bolt hole group (12) being used for fixed connection with one side of the CTC battery pack assembly (3), and the number of bolt holes in the third bolt hole group (12) is greater than the number of bolt holes corresponding to the CTC battery pack assembly (3).

13. The vehicle underbody structure according to claim 6, characterized in that: Both sides of the bottom plate (61) are along the longitudinal direction of the vehicle body, and a first reinforcing plate (63) is respectively provided on each side of the bottom plate (61); the plate surface of the first reinforcing plate (63) is perpendicular to the bottom plate (61) and is used for being fixedly connected to the rear floor assembly (4); A second reinforcing plate (64) is also provided on the bottom plate (61); the plate surface of the second reinforcing plate (64) is perpendicular to the bottom plate (61), and both ends of the second reinforcing plate (64) are respectively fixed to one of the first reinforcing plates (63); and a rib plate is provided between the second reinforcing plate (64) and the bottom plate (61).

14. A vehicle wheelbase adjustment method based on the vehicle lower body structure according to any one of claims 6 to 13, characterized in that: include: The front end of the rear floor assembly (4) is fixedly connected to the left longitudinal beam (1) and the right longitudinal beam (2), and the position thereof is adjusted along the longitudinal direction of the vehicle body, and a gap between the front end of the rear floor assembly (4) and the rear end of the CTC battery pack assembly (3) caused by the position adjustment is eliminated by a first method; The first method comprises rotating a connection member (6) fixed to the rear floor assembly (4) by 180° around a first axis.

15. The vehicle underbody structure according to claim 14, characterized in that: The first method also includes: moving and adjusting the connecting member (6) fixed on the rear floor assembly (4) along the longitudinal direction of the vehicle body, adjusting the fixed connection position of the CTC battery pack assembly (3) on the left longitudinal beam (1) and the right longitudinal beam (2) along the longitudinal direction of the vehicle body, rotating the connecting member (6) fixed on the cabin assembly (5) 180 degrees around the first axis and moving and adjusting the connecting member (6) fixed on the cabin assembly (5) along the longitudinal direction of the vehicle body.

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