Pull-out and folding combined rear expansion structure for recreational vehicle

Abstract

A pull-out and folding combined rear expansion structure (100) for a recreational vehicle, comprising side plates (110), a rear plate (120), bottom plates (130), a top plate (140), and guide rails (150). The side plates comprise a left side plate (111) and a right side plate (112); the left side plate, the right side plate and the rear plate are connected to form a rigid frame; the bottom plates comprise a front bottom plate (131) and a rear bottom plate (132); the front end of the front bottom plate is rotatably connected to the bottom of a cabin (200); the rear end of the front bottom plate is rotatably connected to the front end of the rear bottom plate; the rear end of the rear bottom plate is rotatably connected to the frame; the frame is connected to the cabin by means of the guide rails; the top plate is located on the outer side of the frame, and has the upper end rotatably connected to the top of the cabin. The structure occupies a small space, and can be expanded and retracted conveniently.

Description

Pull-out and foldable rear expansion structure of combined RV

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on January 12, 2024, with application number 202410046381.0, and invention name “Pull-out and foldable combined RV rear expansion structure”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present invention relates to a recreational vehicle expansion structure, and more particularly to a pull-out and foldable combined recreational vehicle rear expansion structure. Background Art

[0003] Currently, demand for RVs is growing in both domestic and international markets, with spacious, fully-featured motorhomes and trailers increasingly favored. A quality RV must offer both comfortable driving and ample space when parked. Therefore, maximizing the efficiency of the RV's interior space and utilizing various methods to expand it are key considerations in RV layout design. Rear expansion is a very common method of RV expansion. Traditionally, there are two types of rear expansion solutions for RVs: a pull-out structure and a folding structure.

[0004] Common pull-out structural solutions include Chinese patents CN 202144223 U and CN 113799678 A. In CN 202144223 U, the motor drives the rack and pinion mechanism through a reduction mechanism (pulley), so that the expansion box fixed to the rack can perform telescopic movement along the guide rail. Although this structure can easily achieve telescopic expansion through the motor, it occupies a large space inside the carriage, has a complex structure, high cost, and is difficult to waterproof and seal the joint between the expansion box and the carriage; in CN 113799678 A, a connecting rod mechanism connected to the expansion box is used to balance the force when the expansion box is extended. The structure is complex and also has problems such as large internal space occupation and difficulty in waterproofing and sealing the joint between the expansion box and the carriage.

[0005] Common folding structural solutions include Chinese patents CN 109109727 A and CN 105966299 B. CN 109109727 A, previously applied for by the applicant, builds a rear expansion box by sequentially flipping the top panel, side panels, bottom frame, and rear panel. The advantage is a simple structure, but it also has disadvantages such as complex operation, large internal space occupied after folding, and high labor consumption. CN 105966299 B designs the side panels into a folding structure and provides guide rails on the first movable panel. When opening the expansion box, the first movable panel is flipped first, and the third movable panel and side panel are unfolded through the linkage action, and then the second movable panel is flipped. The advantages are small space occupied after folding and relatively simple operation, but the structure is complex and the reliability is low. In addition, two hinge joints are added to each side panel, making it difficult to achieve waterproofing, sound insulation, and heat insulation.

[0006] In summary, there is an urgent need to develop a new RV rear expansion structure to solve the above-mentioned technical problems.

[0007] Summary of the Invention

[0008] In view of this, the present invention provides a foldable and retractable rear expansion structure for a combined RV, which can at least partially solve the problems existing in the prior art. In order to achieve the above-mentioned purpose, the technical solution adopted by the present invention is as follows:

[0009] A pull-out and foldable combined RV rear expansion structure is characterized in that it includes side panels, a rear panel, a bottom panel, a top panel and guide rails, the side panels include a left side panel and a right side panel, the left side panel, the right side panel and the rear panel are connected to form a rigid frame, the bottom panel includes a front bottom panel and a rear bottom panel, the front end of the front bottom panel is rotatably connected to the bottom of the car body, the rear end of the front bottom panel is rotatably connected to the front end of the rear bottom panel, the rear end of the rear bottom panel is rotatably connected to the frame, the frame is connected to the car body through the guide rails, and the top panel is located on the outside of the frame and the upper end is rotatably connected to the top of the car body.

[0010] Furthermore, the guide rails include static guide rails and dynamic guide rails, the static guide rails are fixed to the carriage, the dynamic guide rails are fixed to the frame, and the dynamic guide rails move relative to the static guide rails to achieve extension and retraction of the frame.

[0011] Furthermore, the movable guide rail includes the bottom of the side panel and an overhang extending along the bottom of the side panel, namely, a first movable guide rail and a second movable guide rail. The static guide rail is fixed to the bottom of the carriage, including a first static guide rail and a second static guide rail located on both sides. The upper part of the first static guide rail and the second static guide rail has an opening for accommodating the passage of the side panel.

[0012] Furthermore, the upper front sides of the left and right side panels are provided with extensions protruding upward from the side panels, namely, a first extension and a second extension. When the frame is extended to the external limit position, the first extension, the second extension and the corresponding structure in the car body abut.

[0013] Furthermore, the movable guide rail also includes a middle movable guide rail located between the first movable guide rail and the second movable guide rail, and the middle movable guide rail is connected to the bottom of the rear plate. The static guide rail also includes a middle static guide rail located between the first static guide rail and the second static guide rail, and the middle static guide rail cooperates with the middle movable guide rail.

[0014] Furthermore, there are two middle movable guide rails, namely the third movable guide rail and the fourth movable guide rail, and there are two middle static guide rails, namely the third static guide rail and the fourth static guide rail.

[0015] Furthermore, the movable guide rail and the static guide rail are both square tube structures, and the upper parts of the square tube structures of the first static guide rail and the second static guide rail have openings.

[0016] Furthermore, the movable guide rail is equipped with rollers at the end away from the frame, and the rollers on the movable guide rail are in contact with the upper surface inside the static guide rail. The car is equipped with rollers below the movable guide rail, and when the movable guide rail is extended or retracted, its outer lower surface is in contact with the rollers installed on the car.

[0017] Furthermore, a first connecting member is provided at the bottom of the frame near the rear plate, and the first connecting member is connected to the first moving guide rail, the second moving guide rail, the third moving guide rail, and the fourth moving guide rail. The static guide rail includes a second connecting member near the rear of the car, and the second connecting member is connected to the first static guide rail, the second static guide rail, the third static guide rail, and the fourth static guide rail.

[0018] Furthermore, the front floor and the rear floor, the front floor and the carriage, and the rear floor and the frame are all rotatably connected via hinges.

[0019] Furthermore, one side of the hinge connecting the rear floor and the frame is installed on the upper surface of the first connecting member, and the other side is installed on the rear end surface of the rear floor; one side of the hinge connecting the front floor and the car body is installed on the upper surface of the second connecting member, and the other side is installed on the front end surface of the front floor.

[0020] Furthermore, the static guide rail further includes a third connecting member arranged parallel to the second connecting member, and the third connecting member is connected to the first static guide rail, the second static guide rail, the third static guide rail, and the fourth static guide rail.

[0021] As a preferred embodiment, a first handle is provided in the middle of the front bottom plate near the rear bottom plate, and a window and a second handle are provided in the middle and upper parts of the rear plate respectively.

[0022] As a further preference, the first handle adopts a hidden design.

[0023] As a preferred embodiment, the upper parts of the left and right panels are arranged to be structures inclined relative to the horizontal plane, and the upper rear parts of the left and right panels are respectively provided with extensions protruding backward from the side panels, namely, the third extension and the fourth extension, and the third extension and the fourth extension are respectively provided with rolling parts, and the rolling parts are in contact with the top panel when the frame extends and retracts relative to the car body.

[0024] As a further preference, the top plate has an outward protrusion, and when the frame is extended to the extreme position relative to the vehicle compartment, the protrusion accommodates the upper part of the rolling part.

[0025] As a further preference, a sealing portion is provided on the inner side of the top plate, and a positioning pin is also provided on the upper part of the rear plate. When the frame is extended to the extreme position relative to the vehicle body, the sealing portion covers the upper outer edge of the frame, and the positioning pin passes through the corresponding opening on the sealing portion.

[0026] As a preferred embodiment, the top plate is rotatably connected to the car body through an adapter plate, and the adapter plate includes parallel planes at both ends and a connecting plane in the middle, one end of which is fixedly connected to the rear of the car body, and the other end is connected to the outer flange hinge of the upper end of the top plate.

[0027] As a preferred embodiment, the front portions of the left and right panels have outwardly facing flanges, and the left and right ends and the lower end of the top panel have inwardly facing flanges.

[0028] Compared with the prior art, the present invention has the following obvious advantages:

[0029] 1. It combines the advantages of both pull-out and folding structures. The side panels and rear panels adopt an integrated pull-out structure, and the bottom panel and top panel adopt a folding and flipping structure. When folded, the internal space is small. When opened, push the rear panel handle, and the rear expansion box can be unfolded in one step. When folding, first pull the bottom panel handle, drive the entire structure back through the bottom panel, and finally pull the rear panel handle to return it to the car. The operation is very convenient.

[0030] 2. The two bottom plates are designed as a folding structure. After opening, the two bottom plates are flattened, which can lock the rear expansion structure in the extreme position. When folding, since the handle is located close to the folding hinge, it is very labor-saving to pull back through the front bottom plate handle. In addition, the two bottom plates can assist the guide rail when opening and folding.

[0031] 3. The entire side panel and the rear panel are integrated into one unit, which has excellent waterproof, soundproof and heat-insulating properties. During the opening and closing process, the rear expansion part always remains sealed to the outside, which can effectively prevent the entry of external dust and mosquitoes.

[0032] 4. Move the connecting hinge between the top plate and the box body to the adapter plate, which can effectively prevent rainwater from pouring in from the top plate hinge. Rolling parts are provided on both side panels to reduce friction between the top plate and avoid scratching the top plate. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] FIG1 is a schematic diagram of the partial structure of the present invention when it is installed on a carriage and opened (seen from the front);

[0034] FIG2 is a schematic diagram of the partial structure of the present invention when it is installed on a carriage and opened (seen from the rear);

[0035] FIG3 is a schematic diagram of the partial structure of the present invention when it is installed on a carriage and folded (seen from the front);

[0036] FIG4 is a schematic diagram of the partial structure of the present invention when it is installed on a carriage and folded (seen from the rear);

[0037] FIG5 is a schematic diagram of a partial structure of the connection between the rear base plate and the frame of the present invention;

[0038] FIG6 is a schematic diagram of a partial structure of the connection between the front floor and the carriage according to the present invention;

[0039] FIG7 is a schematic diagram of the frame structure composed of the side panels and the rear panel of the present invention (the skin on the right side panel is omitted);

[0040] FIG8 is a partial enlarged view of point A in FIG7;

[0041] FIG9 is a partial enlarged view of point B in FIG7 ;

[0042] FIG10 is a partial enlarged view of point C in FIG7 ;

[0043] FIG11 is a schematic diagram of the partial structure of the frame and the top plate when the present invention is opened;

[0044] FIG12 is a schematic structural diagram of the top plate of the present invention;

[0045] FIG13 is a schematic diagram of the partial structure of the connection between the top plate and the carriage of the present invention;

[0046] FIG14 is a schematic structural diagram of the present invention when it is installed on a carriage and is opened;

[0047] FIG15 is a front view of the present invention when it is installed on a carriage and opened. DETAILED DESCRIPTION

[0048] The following describes embodiments of the present invention in detail. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to explain the present invention, but are not to be construed as limiting the present invention.

[0049] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0050] As shown in Figures 1 to 4 and Figure 7, a pull-out and foldable combined RV rear expansion structure 100 includes side panels 110, a rear panel 120, a bottom panel 130, a top panel 140 and a guide rail 150. The side panel 110 includes a left panel 111 and a right panel 112. The left panel 111, the right panel 112 and the rear panel 120 are connected to form a rigid frame. The bottom panel 130 includes a front bottom panel 131 and a rear bottom panel 132. The front end of the front bottom panel 131 is rotatably connected to the bottom of the car body 200, the rear end of the front bottom panel 131 is rotatably connected to the front end of the rear bottom panel 132, and the rear end of the rear bottom panel 132 is rotatably connected to the frame. The frame is connected to the car body 200 through the guide rail 150. The top panel 140 is located on the outside of the frame and the upper end is rotatably connected to the top of the car body 200.

[0051] The guide rail 150 includes a static guide rail 151 and a dynamic guide rail 152. The static guide rail 151 is fixed to the carriage 200. It is worth noting that in order to highlight the core technical solution of the present invention, only a part of the carriage 200 is drawn as an example, and the structure is also simplified. The dynamic guide rail 152 is fixed to the frame, and the dynamic guide rail 152 moves relative to the static guide rail 151 to realize the extension and retraction of the frame.

[0052] Furthermore, the outer periphery of the left side plate 111 and the right side plate 112 are welded with square tubes, the moving guide rail 152 includes the bottom of the left side plate 111 and the right side plate 112 and the overhanging portion extending along the bottom of the left side plate 111 and the right side plate 112, namely the first moving guide rail 1521 and the second moving guide rail 1522, and the static guide rail 151 is fixed to the bottom of the carriage 200, including the first static guide rail 1511 and the second static guide rail 1512 located on both sides, and the upper part of the first static guide rail 1511 and the second static guide rail 1512 has openings 1511a and 1512a for accommodating the passage of the side panels.

[0053] Furthermore, the upper front sides of the left side panel 111 and the right side panel 112 are provided with extensions protruding upward from the side panel 110, namely the first extension 1111 and the second extension 1121. When the frame is extended to the external limit position, the first extension 1111, the second extension 1121 and the corresponding structure in the car body 200 abut against each other. At this time, the torque for the overall outward flipping of the rear expansion structure is mainly borne by the corresponding structure on the car body, and the other part is borne by the static guide rail.

[0054] Furthermore, the movable guide rail 152 also includes a middle movable guide rail located between the first movable guide rail 1521 and the second movable guide rail 1522, and the middle movable guide rail is connected to the bottom of the rear plate 120. The static guide rail 151 also includes a middle static guide rail located between the first static guide rail 1511 and the second static guide rail 1512, and the middle static guide rail and the middle movable guide rail cooperate.

[0055] As a preferred embodiment, there are two middle moving guide rails, namely the third moving guide rail 1523 and the fourth moving guide rail 1524, and there are two middle static guide rails, namely the third static guide rail 1513 and the fourth static guide rail 1514. By setting up multiple guide rails, the pulling and pulling movement is smoother and the force is more reasonable.

[0056] As a further preference, the movable guide rail 152 and the static guide rail 151 are both square tube structures, and the upper portions of the square tube structures of the first static guide rail 1511 and the second static guide rail 1512 have openings 1511a and 1512a. Both the static guide rail and the movable guide rail are made of aluminum alloy to further reduce weight.

[0057] As shown in Figures 6 and 8, as a further preference, the moving guide rail 152 is installed with a roller 160 at the end away from the frame. The roller 160 on the moving guide rail 152 contacts and cooperates with the upper surface inside the static guide rail 151. A roller 170 is installed below the moving guide rail 152 at the rear of the car 200. When the moving guide rail 152 is extended or retracted, its outer lower surface contacts and cooperates with the roller 170 installed on the car 200. By providing the roller, the sliding friction is changed to rolling friction, thereby further reducing the friction force when the moving guide rail moves.

[0058] As a preferred embodiment, a first connecting member 180 is provided at the bottom of the frame near the rear plate 120, and the first connecting member 180 is connected to the first moving guide rail 1521, the second moving guide rail 1522, the third moving guide rail 1523, and the fourth moving guide rail 1524, further increasing the connection strength of the moving guide rails. The static guide rail 151 includes a second connecting member 181 near the rear of the carriage 200, and the second connecting member 181 is connected to the first static guide rail 1511, the second static guide rail 1512, the third static guide rail 1513, and the fourth static guide rail 1514, further increasing the connection strength of the static guide rails.

[0059] Furthermore, the front bottom plate 131 and the rear bottom plate 132, the front bottom plate 131 and the car body 200, and the rear bottom plate 132 and the frame are all connected by hinges. With this arrangement, the front and rear bottom plates are unfolded and folded accordingly when the frame is extended or retracted, which simplifies the operation steps.

[0060] As shown in Figures 5 and 6, as a preferred embodiment, one side of the hinge connecting the rear bottom plate 132 and the frame is installed on the upper surface of the first connecting member 180, and the other side is installed on the rear end surface of the rear bottom plate 132. One side of the hinge connecting the front bottom plate 131 and the carriage 200 is installed on the upper surface of the second connecting member 181, and the other side is installed on the front end surface of the front bottom plate 131.

[0061] As shown in Figure 7, as a preferred embodiment, the static guide rail 151 also includes a third connecting member 182 arranged parallel to the second connecting member 181. The third connecting member 182 is connected to the first static guide rail 1511, the second static guide rail 1512, the third static guide rail 1513, and the fourth static guide rail 1514 to further increase the connection strength of the static guide rail.

[0062] As shown in Figure 1, as a preferred embodiment, a first handle 1311 is provided in the middle of the front bottom plate 131 near the rear bottom plate. According to force analysis, pulling the first handle 1311 can easily pull up the front and rear bottom plates and retract the frame at the same time. The middle and upper parts of the rear plate 120 are respectively provided with windows 121 and second handles 122. The window 121 is made as large as possible to increase the experience of viewing the scenery while traveling. The setting of the second handle 122 facilitates pushing and pulling the entire frame. The second handle 122 can adopt a fixed or rotating structure.

[0063] As a further preference, the first handle 1311 adopts a hidden design, which can ensure that the front and rear base plates are located in the same plane after being unfolded, making it convenient to lay a mattress on top.

[0064] As shown in Figures 11, 14 and 15, as a preferred embodiment, the upper parts of the left side panel 111 and the right side panel 112 are set to a structure inclined relative to the horizontal plane. The setting of the inclined structure facilitates the pushing of the top panel on the one hand, and ensures that the top panel is also inclined after unfolding, which is convenient for rainwater drainage. At the same time, the upper rear parts of the left side panel 111 and the right side panel 112 are respectively provided with extensions protruding rearward from the side panels, namely the third extension part 1112 and the fourth extension part 1122. The third extension part 1112 and the fourth extension part 1122 are respectively provided with rolling parts 190. When the frame extends and retracts relative to the car body 200, the rolling part 190 contacts the top panel 140. As shown in Figure 9, the rolling part preferably adopts a rubber-coated bearing, and its upper part and rear part protrude from the third extension part 1112 and the fourth extension part 1122 respectively. The rubber-coated bearing acts as a guide wheel on the one hand, reduces friction between the top panel and the top panel on the other hand, and can avoid scratching the top panel.

[0065] As shown in FIG12 , as a preferred embodiment, the top panel 140 has an outward protrusion 141. When the frame is extended to the extreme position relative to the carriage 200, the protrusion 141 accommodates the upper portion of the rolling portion 190. This ensures that the upper portions of the top panel and the side panels are always in contact with each other when the rear panel is expanded and opened, thereby ensuring sealing.

[0066] As a preferred embodiment, a sealing portion 142 is provided on the inner side of the top plate 140, and a positioning pin 123 is also provided on the upper part of the rear plate 120. There are preferably two positioning pins 123, which are respectively close to the left and right sides of the rear plate 120. When the frame is extended to the extreme position relative to the vehicle body 200, the sealing portion 142 covers the upper outer edge of the frame, and the positioning pin 123 passes through the corresponding opening on the sealing portion 142. The function of the sealing portion 142 is waterproof, soundproof and heat-insulating, and the function of the positioning pin 123 is to prevent the top plate from being opened from the outside to ensure safety.

[0067] As shown in Figure 13, as a preferred embodiment, the top plate 140 is rotatably connected to the car body 200 through an adapter plate 143. The adapter plate 143 includes parallel planes at both ends and a connecting plane in the middle. One end is fixedly connected to the rear of the car body 200, and the other end is hinged to the outer flange 144 at the upper end of the top plate 140. This structure can effectively prevent rainwater from pouring in from the hinge of the top plate.

[0068] As shown in Figures 10 and 12, as a preferred embodiment, the front parts of the left side panel 111 and the right side panel 112 have outward flanges 1113 and 1123. By arranging sealing strips on the flanges 1113 and 1123 and cooperating with the car body frame, further waterproofing, sound insulation and heat insulation can be achieved. The left and right ends and the lower end of the top panel 140 also have inward flanges 145.

[0069] The working process of the rear expansion structure of the foldable and modular RV of the present invention is as follows:

[0070] When opening the rear extension, first open the fixed lock between the top plate and the car body (not shown in the figure), then push the second handle on the rear plate, and the entire frame slides outward along the static guide rail, while driving the front and rear bottom plates to unfold and pushing the top plate to flip, and finally slide to the limit position. At this time, the front and rear bottom plates are flattened, so that the rear extension structure is locked in the limit position, and the pin on the rear plate is inserted into the corresponding opening of the top plate, so that the top plate cannot be opened or pushed back to expand from the outside;

[0071] When expanding after folding, first pull up the first handle on the front bottom plate to make the entire frame slide inward along the static guide rail. After sliding a certain distance, pull up the second handle on the rear plate to make the entire frame return to the extreme position. At this time, the front and rear bottom plates fold upward, the top plate flips over and fits the rear of the car, and finally the top plate is locked to the car with a fixed lock.

[0072] In the description of the present invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely to facilitate the description of the present invention. They are not intended to indicate or imply that the devices or components referred to must have, be constructed, or operate in a specific orientation, and therefore should not be construed as limitations on the present invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0073] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood broadly. For example, they may refer to fixed or detachable connections; mechanical or electrical connections; direct or indirect connections through an intermediary; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention.

[0074] The above embodiments merely illustrate the basic principles and features of the present invention. The present invention is not limited to the above embodiments. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention. Such changes and modifications are intended to fall within the scope of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A pull-out and foldable combined rear extension structure for a motorhome, characterized in that: It includes side plates, a rear plate, a bottom plate, a top plate and guide rails. The side plates include a left side plate and a right side plate. The left side plate, the right side plate and the rear plate are connected to form a rigid frame. The bottom plate includes a front bottom plate and a rear bottom plate. The front end of the front bottom plate is rotatably connected to the bottom of the carriage, the rear end of the front bottom plate is rotatably connected to the front end of the rear bottom plate, and the rear end of the rear bottom plate is rotatably connected to the frame. The frame is connected to the carriage through the guide rails. The top plate is located outside the frame and its upper end is rotatably connected to the top of the carriage.

2. The pull-out and foldable combined rear expansion structure of a recreational vehicle according to claim 1, characterized in that: The guide rails include a static guide rail and a moving guide rail. The static guide rail is fixed to the carriage, and the moving guide rail is fixed to the frame. The moving guide rail moves relative to the static guide rail to realize the extension and retraction of the frame.

3. The pull-out and folding combined rear extension structure of a motorhome according to claim 2, characterized in that: The moving guide rail includes the bottom of the side plates and overhanging parts extending along the bottom of the side plates, namely a first moving guide rail and a second moving guide rail. The static guide rail is fixed to the bottom of the carriage and includes a first static guide rail and a second static guide rail on both sides. The upper parts of the first static guide rail and the second static guide rail have openings for the side plates to pass through.

4. The pull-out and foldable combined rear expansion structure of a recreational vehicle according to claim 3, characterized in that: On the upper sides of the front parts of the left side plate and the right side plate, there are extending parts protruding upward from the side plates, namely a first extending part and a second extending part. When the frame extends to the external limit position, the first extending part, the second extending part and the corresponding structures inside the carriage are in contact.

5. The pull-out and folding combined rear extension structure of a recreational vehicle according to claim 4, wherein: The moving guide rail further includes a middle moving guide rail located between the first moving guide rail and the second moving guide rail. The middle moving guide rail is connected to the bottom of the rear plate. The static guide rail further includes a middle static guide rail located between the first static guide rail and the second static guide rail. The middle static guide rail and the middle moving guide rail cooperate with each other.

6. The pull-out and folding combined rear expansion structure of a motorhome according to claim 5, characterized in that: There are two middle moving guide rails, namely a third moving guide rail and a fourth moving guide rail. There are two middle static guide rails, namely a third static guide rail and a fourth static guide rail.

7. The pull-out and folding combined rear expansion structure of a recreational vehicle according to claim 6, characterized in that: Both the moving guide rail and the static guide rail are square tube structures, and the upper parts of the square tube structures of the first static guide rail and the second static guide rail have openings.

8. The pull-out and folding combined rear expansion structure of a motorhome according to claim 7, wherein: Rollers are installed at the ends of the moving guide rail far from the frame. The rollers on the moving guide rail are in contact and cooperation with the upper surface inside the static guide rail. Rollers are installed on the carriage below the moving guide rail. When the moving guide rail expands and contracts, its outer lower surface is in contact and cooperation with the rollers installed on the carriage.

9. The pull-out and folding combined rear expansion structure of a motorhome according to claim 8, wherein: A first connecting piece is provided at a position on the bottom of the frame close to the rear plate. The first connecting piece is connected to the first moving guide rail, the second moving guide rail, the third moving guide rail and the fourth moving guide rail. The static guide rail includes a second connecting piece close to the rear of the carriage. The second connecting piece is connected to the first static guide rail, the second static guide rail, the third static guide rail and the fourth static guide rail.

10. The pull-out and foldable combined rear expansion structure of a motorhome according to claim 9, wherein: The front bottom plate and the rear bottom plate, the front bottom plate and the carriage, and the rear bottom plate and the frame are all rotatably connected by hinges.

11. The pull-out and foldable combined rear expansion structure of a motorhome according to claim 10, characterized in that: One side of the hinge connecting the rear bottom plate and the frame is installed on the upper surface of the first connecting piece, and the other side is installed on the rear end face of the rear bottom plate. One side of the hinge connecting the front bottom plate and the carriage is installed on the upper surface of the second connecting piece, and the other side is installed on the front end face of the front bottom plate.

12. The pull-out and foldable combined rear expansion structure of a recreational vehicle according to claim 11, wherein: The static guide rail further includes a third connecting member disposed parallel to the second connecting member, and the third connecting member is connected to the first static guide rail, the second static guide rail, the third static guide rail, and the fourth static guide rail.

13. The pull-out and foldable combined rear expansion structure of a motorhome according to claim 1, characterized in that: A first handle is provided at a position near the rear bottom plate in the middle of the front bottom plate, and a window and a second handle are respectively provided in the middle and upper part of the rear plate.

14. The pull-out and folding combined rear expansion structure of a recreational vehicle according to claim 13, characterized in that: The first handle adopts a concealed design.

15. The pull-out and folding combined rear expansion structure of a motorhome according to claim 1, wherein: The upper parts of the left side plate and the right side plate are arranged in a structure inclined relative to the horizontal plane, and extension parts protruding rearward from the side plates, namely a third extension part and a fourth extension part, are respectively provided on the upper sides of the rear parts of the left side plate and the right side plate. Rolling parts are respectively provided on the third extension part and the fourth extension part, and the rolling parts contact the top plate when the frame extends out of and retracts into the carriage.

16. The pull-out and foldable combined rear expansion structure of a recreational vehicle according to claim 15, characterized in that: The top plate has a protruding part facing outward. When the frame extends out to the limit position relative to the carriage, the protruding part accommodates the upper part of the rolling part.

17. The pull-out and foldable combined rear expansion structure of a motorhome according to claim 1, characterized in that: A sealing part is provided inside the top plate, and a positioning pin is further provided on the upper part of the rear plate. When the frame extends out to the limit position relative to the carriage, the sealing part covers the outer edge of the upper part of the frame, and the positioning pin passes through the corresponding opening on the sealing part.

18. The draw-out and foldable combined rear expansion structure of a motorhome according to claim 17, characterized in that: The top plate is rotatably connected to the carriage through an adapter plate. The adapter plate includes parallel planes at both ends and a connecting plane in the middle. One end of the adapter plate is fixedly connected to the rear part of the carriage, and the other end is hinge-connected to the flanging on the upper end of the top plate facing outward.

19. The pull-out and foldable combined rear expansion structure of a motorhome according to claim 1, characterized in that: The front parts of the left side plate and the right side plate have flangings facing outward, and the left and right ends and the lower end of the top plate have flangings facing inward.

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