Top air inlet type motorcycle frame

Abstract

The utility model discloses a top air inlet type motorcycle frame which comprises a front wheel frame, a bottom fork frame and a supporting frame, the supporting frame is respectively and movably connected with the front wheel frame and the bottom fork frame, a cushion frame with the rear end inclining upwards is fixedly arranged on the supporting frame, an installation position for installing an engine is arranged on the supporting frame, and an installation space is arranged below the cushion frame. A mounting seat is arranged in the mounting space, a port of one end of the air inlet pipe penetrates through the mounting seat and is fixed on the mounting seat, a port of the other end of the air inlet pipe penetrates through the cushion frame from the mounting space and extends into the mounting position from the upper portion of the supporting frame to be connected with the engine, and a sealing cover is arranged at the end, away from the engine, of the air inlet pipe; a plurality of air inlets are formed in the side wall, close to the front wheel, of the air inlet channel, and a control rod for controlling the opening degree of the air inlets is arranged on the air inlet channel. Compared with the prior art, dust, silt and rainwater on the ground are prevented from entering the air inlet pipe, normal use of a spare box of the motorcycle is not occupied, the opening degree of the air inlet can be adjusted, and the combustion efficiency of an engine is optimized.

Description

TECHNICAL FIELD

[0001] The utility model relates to motorcycle technical field especially top air intake type motorcycle frame. BACKGROUND

[0002] As a widely used means of transportation, the performance of the engine of a motorcycle has a crucial influence on the power output and fuel economy of the vehicle. The combustion efficiency of the engine is closely related to the performance of the air intake system, which provides the oxygen required for combustion for the engine and is the key to ensuring full combustion of gasoline. If the air intake is insufficient or contains too many impurities, not only will the engine power decrease, but also the fuel consumption will increase and the service life of the engine will be reduced. The traditional motorcycle air intake system is generally arranged on the lower side of the frame, close to the ground. During driving, the motorcycle will raise dust on the road surface, especially on a dirt road or a muddy road surface. Dust, sand and even rainwater can easily enter the air intake system, thereby reducing the air intake efficiency and affecting the performance of the engine.

[0003] In order to solve the above problems, some high-position air intake system designs have appeared on the market. For example, the Chinese utility model patent "scooter high-position air intake system" with patent announcement number CN209163971U, which comprises a trunk, a partition plate fixedly installed in the middle of the inner cavity of the trunk, an air extraction pipe fixedly installed on the top of the partition plate, a first air pipe fixedly communicated at the bottom of the air extraction pipe, and a net box fixedly communicated at the other end of the first air pipe below the partition plate. The top and bottom of the inner cavity of the net box are movably connected with fixed pipes, and the two fixed pipes are fixedly connected with a filter screen. The right side of the net box is fixedly communicated with a second air pipe, the other end of the second air pipe penetrates through the trunk and extends to the outside of the right side of the trunk and is fixedly communicated with a cylinder.

[0004] In the above-mentioned scheme, the air extraction pipe in the air intake system is arranged in the trunk, which will affect the normal use of the trunk. When other items are placed in the trunk, the air extraction pipe may be blocked, thereby affecting the air intake efficiency of the air intake system and reducing the working efficiency of the engine. UTILITY MODEL CONTENTS

[0005] The utility model is directed to the problem that the air extraction pipe of the motorcycle air intake system is arranged in the trunk, which will affect the normal use of the trunk. When other items are placed in the trunk, the air extraction pipe may be blocked, thereby affecting the air intake efficiency of the air intake system and reducing the working efficiency of the engine. The technical problem to be solved by the utility model is to provide a top air intake type motorcycle frame to solve the above problems.

[0006] The utility model discloses a technical scheme that solves the above technical problem is as follows: including front wheel frame, flat fork frame and support frame, support frame front end and front wheel frame swing joint, rear end and flat fork frame swing joint, be equipped with the seat frame that is located flat fork frame top and rear end is inclined upward on support frame, be equipped with the installation site for installing engine on support frame, the installation space of having located support frame rear end below seat frame, be equipped with the intake pipe and the mounting seat fixed on seat frame in installation space, one end port of intake pipe passes through mounting seat and is fixed on mounting seat, and the other end port passes through seat frame from installation space and from support frame top and stretches into the installation site with the throttle valve of engine and is connected, the one end port of intake pipe is away from engine and is equipped with the cover, the side of cover and mounting seat hinged, and the other side is fixed on mounting seat through the lock catch, intake pipe has the air intake passage that extends to the outside, be equipped with a plurality of air inlets on the side wall of air intake passage close to front wheel, the outer end of air intake passage is equipped with the control rod that stretches into air intake passage to control the opening amount of air inlet.

[0007] The utility model further provides a preferred scheme: the intake pipe is the V type structure that opens downward, be equipped with the through -port on mounting seat, the seat frame has the installation port that communicates with installation space, one pipe arm of intake pipe stretches into installation space from installation port and extends through -port, and another pipe arm of intake pipe stretches into the installation site from the top of support frame and is connected with the throttle valve.

[0008] The utility model further provides a preferred scheme: the one end port of intake pipe close to mounting seat is equipped with the annular baffle that extends outward along the port, and the annular baffle is abutted at the edge of through -port of mounting seat, and the edge of the side of annular baffle away from mounting seat has the flanging, and the cover has the annular wall that is inserted into intake pipe and is attached to the inner wall of flanging with flanging cooperation.

[0009] The utility model further provides a preferred scheme: the air intake passage is located on the pipe wall of intake pipe at installation space, and the booster driven by engine is arranged in the intake pipe.

[0010] The utility model further provides a preferred scheme: the control rod stretches into air intake passage and is connected with air intake passage screw thread, and the position of control rod in air intake passage can be communicated or disconnected with air intake passage by rotating.

[0011] The utility model further provides a preferred scheme: the air inlet has the horn -shaped flared mouth that extends to the outside.

[0012] The further preferred scheme of the utility model is that the two sides of the cushion frame are provided with support rods extending to the lower two sides of the support frame, the ends of the two support rods are fixed on the corresponding side support frames respectively, the upper ends of the mounting seats are fixed on the lower two sides of the cushion frame through bolts, and the lower ends of the mounting seats are fixed on the ends of the two support rods through bolts.

[0013] The further preferred scheme of the utility model is that the outer end of the air inlet channel penetrates to the outer side wall of the mounting seat, and the outer end of the control rod is provided with an operating handle.

[0014] The further preferred scheme of the utility model is that the support frame comprises a main beam pipe, the front end of the main beam pipe is provided with a steering pipe, the steering pipe is movably connected with the front wheel frame, two lower bent pipes are arranged on the upper side of the main beam pipe and are provided with openings facing the main beam pipe, a connecting pipe is arranged between the ends of the two lower bent pipes, the rear end of the main beam pipe is provided with two upper bent pipes with openings facing the two lower bent pipes, and the main beam pipe, the steering pipe, the two lower bent pipes, the two upper bent pipes and the connecting pipe form the mounting position.

[0015] The further preferred scheme of the utility model is that the front ends of the two sides of the cushion frame are fixed on the upper sides of the two upper bent pipes respectively, the lower ends of the two support rods are fixed on the lower sides of the two upper bent pipes respectively, the two sides of the flat fork frame are rotatably connected to the lower sides of the two upper bent pipes and are located below the connecting rod.

[0016] Compared with the prior art, the utility model has the following advantages:

[0017] 1. The air inlet pipe is installed below the cushion frame and in the mounting space at the rear end of the support frame, so that the air inlet channel is away from the ground, the dust, sand and even rainwater on the ground can be prevented from entering the air inlet pipe, the installation position is compact and reasonable, and the normal use of the trunk of the motorcycle is not occupied.

[0018] 2. The air inlet channel extending outward is arranged on the outer side of the air inlet pipe, a plurality of air inlets are arranged on the side wall close to the front wheel of the air inlet channel, the outer end of the air inlet channel is provided with a control rod extending into the air inlet channel to control the opening amount of the air inlets, the opening amount of the air inlets can be flexibly adjusted through the control rod, so that the air inlet amount is accurately controlled according to different driving conditions, such as acceleration, uniform driving or climbing, the combustion efficiency of the engine is optimized, and the fuel economy and power performance are improved. The air inlets are arranged on the side wall close to the front wheel of the air inlet channel, the direction of the air inlets is opposite to the direction of the wind during the driving process of the motorcycle, and the air inlet amount of the wind is further improved. BRIEF DESCRIPTION OF DRAWINGS

[0019] The utility model will be further described in detail below in combination with the drawings and preferred embodiments, but the skilled in the art will appreciate that these drawings are only drawn for the purpose of explaining the preferred embodiments and therefore should not be regarded as limiting the scope of the utility model, in addition, the drawings only schematically show the composition or structure of the described object conceptually and can contain exaggerated display, and the drawings are not necessarily drawn to scale, unless specifically indicated.

[0020] Figure 1 It is the three-dimensional structure schematic diagram of the frame of the preferred embodiment of the utility model after installing other components of the motorcycle;

[0021] Figure 2 It is the three-dimensional structure schematic diagram of the frame of the preferred embodiment of the utility model after installing the engine;

[0022] Figure 3 It is the three-dimensional structure schematic diagram of the frame of the preferred embodiment of the utility model after installing other components of the motorcycle; Figure 2 It is the three-dimensional structure schematic diagram of the frame of the preferred embodiment of the utility model after installing other components of the motorcycle;

[0023] Figure 4 It is the three-dimensional structure schematic diagram of the frame of the preferred embodiment of the utility model after installing other components of the motorcycle;

[0024] Figure 5 It is the three-dimensional structure schematic diagram of the frame of the preferred embodiment of the utility model after installing other components of the motorcycle;

[0025] Figure 6 It is the three-dimensional structure schematic diagram of the frame of the preferred embodiment of the utility model after installing other components of the motorcycle;

[0026] Figure 7 It is the three-dimensional structure schematic diagram of the frame of the preferred embodiment of the utility model after installing other components of the motorcycle;

[0027] In the drawing: 1, front wheel support; 2, flat fork support; 3, support frame; 31, main beam pipe; 32, steering pipe; 33, lower elbow pipe; 34, connecting pipe; 35, upper elbow pipe; 4, cushion support; 41, support rod; 42, installation port; 5, installation position; 6, installation space; 7, air inlet pipe; 71, air inlet channel; 72, horn-shaped flared mouth; 73, annular retaining wall; 74, control rod; 75, operating handle; 8, mounting seat; 81, through port; 9, cover; 10, lock catch; 11, engine; 12, throttle valve. DETAILED DESCRIPTION

[0028] The preferred embodiments of the utility model will be described in detail below with reference to the drawings, and the skilled in the art will appreciate that these descriptions are only descriptive, exemplary and should not be interpreted as limiting the protection scope of the utility model.

[0029] It should be noted that similar labels in the following figures indicate similar items; therefore, once an item is defined in one figure, it may not be further defined and explained in subsequent figures.

[0030] This embodiment mainly describes the top-intake motorcycle frame, as detailed below:

[0031] like Figures 1 to 7 As shown, the top-intake motorcycle frame includes a front wheel frame 1, a swingarm frame 2, and a support frame 3. The front end of the support frame 3 is movably connected to the front wheel frame 1, and the rear end is movably connected to the swingarm frame 2. A seat frame 4, located above the swingarm frame 2 and tilted upwards at the rear end, is fixedly mounted on the support frame 3. The seat frame 4 provides comfortable support for the rider, and its upward tilting design at the rear end is ergonomic, better conforming to the rider's body and improving riding comfort. The support frame 3 also has a mounting position 5 for mounting the engine 11. As the power core of the motorcycle, the engine 11 is firmly fixed to the frame through the mounting position 5, ensuring its stable operation during riding. Below the seat frame 4 is a mounting space 6 located at the rear end of the support frame 3. This mounting space 6 provides a reasonable layout for the intake system and other related components, making full use of the internal space of the frame and making the frame structure more compact. The mounting space 6 contains an intake pipe 7 and a mounting seat 8 fixed to the seat frame 4. The intake pipe 7 is a key component for achieving the intake function. One end of its port passes through the mounting base 8 and is fixed to the mounting base 8. The other end of its port passes through the mounting space 6, through the seat frame 4, and extends from above the support frame 3 into the mounting position 5 to connect with the throttle valve 12 of the engine 11. This unique top-intake method avoids the drawbacks of traditional intake methods, reduces the possibility of dust and debris entering the intake pipe 7, and improves the intake quality. A cover 9 is provided at the end of the intake pipe 7 furthest from the engine 11. One side of the cover 9 is hinged to the mounting base 8, and the other side is fixed to the mounting base 8 by a latch 10. This structural design makes the opening and closing of the cover 9 convenient, facilitating inspection and maintenance of the inside of the intake pipe 7. The intake pipe 7 has an outwardly extending intake channel 71. Multiple air inlets are provided on the side wall of the intake channel 71 near the front wheel. A control lever 74 extends into the intake channel 71 to control the opening amount of the air inlets. The opening amount of the air intake can be flexibly adjusted via the control lever 74, thereby precisely controlling the intake volume according to different driving conditions, such as acceleration, constant speed driving, or climbing, optimizing the combustion efficiency of the engine 11, and improving fuel economy and power performance. The air intake is positioned on the side wall of the intake passage 71 near the front wheel, so that during motorcycle operation, the air intake faces the direction of the wind, further increasing the amount of air intake.

[0032] like Figure 6As shown, the air intake pipe 7 is a downwardly open V-shaped structure, which makes the air intake pipe 7 more reasonable in spatial layout and better adapt to the structural features of the frame, and is also conducive to the smooth flow of air intake. The mounting seat 8 is provided with a through port 81, the seat cushion frame 4 has a mounting port 42 communicating with the mounting space 6, one arm of the air intake pipe 7 extends into the mounting space 6 from the mounting port 42 and extends out of the through port 81, and the other arm extends into the mounting space 5 from the top of the support frame 3 and is connected with the throttle valve 12 of the engine 11. This connection mode ensures the firm connection between the air intake pipe 7 and the frame and the engine 11, and ensures the sealing and stability of the air intake passage 71, avoids air leakage and other problems during air intake, and further improves the reliability and efficiency of the air intake system.

[0033] As shown in the drawings, Figure 7 The air intake pipe 7 is provided with an annular baffle 73 extending outwardly along the port near the port of the mounting seat 8, the annular baffle 73 abuts against the edge of the through port 81 of the mounting seat 8, and the edge of the annular baffle 73 away from the mounting seat 8 has a flange. The cover 9 has an annular wall inserted into the air intake pipe 7 and abutting against the inner wall of the flange. The design of the annular baffle 73 not only enhances the sealing between the air intake pipe 7 and the mounting seat 8, but also provides certain structural support for the air intake pipe 7, ensuring its stability during installation and use. The arrangement of the annular baffle 73 can effectively prevent dust and debris from entering the air intake pipe 7, thereby improving the air intake quality and prolonging the service life of the air intake system. The close cooperation between the annular wall and the flange can achieve good sealing effect and prevent air leakage from the gap between the cover 9 and the air intake pipe 7.

[0034] Specifically, the air intake passage 71 is arranged on the arm of the air intake pipe 7 at the mounting space 6, and the air intake pipe 7 is provided with a supercharger driven by the engine 11. The supercharger adopts a mechanical supercharging structure, which is a prior art and will not be described here. The arrangement of the supercharger can further improve the air intake efficiency. The supercharger is driven by the power of the engine 11 to compress the air entering the air intake pipe 7, increase the amount of air entering the engine cylinder per unit time, and thus improve the power and torque output of the engine 11, so that the motorcycle has stronger power performance under working conditions such as acceleration and climbing. At the same time, the use of the supercharger can also improve the performance of the engine 11 at high altitudes. Because the air is thin at high altitudes, insufficient air intake will limit the power output of the engine 11, and the supercharger can effectively solve this problem, so that the motorcycle can maintain good power performance at different altitudes.

[0035] Specifically, the control rod 74 extends into the air inlet channel 71 and is threadedly connected with the air inlet channel 71. By rotating the position of the control rod 74 in the air inlet channel 71, the air inlet can be connected or disconnected with the air inlet channel 71. This threaded connection makes the adjustment of the control rod 74 more accurate and stable. The rider can adjust the opening degree of the air inlet by rotating the control rod 74 according to the actual driving needs, thereby realizing precise control of the air intake. For example, when driving on urban roads, the air inlet can be partially opened by adjusting the control rod 74 to meet the air intake demand of the engine 11 under low load conditions, thereby reducing fuel consumption. When driving at high speed or needing to accelerate to overtake, the air inlet can be fully opened to allow the engine 11 to obtain sufficient air intake and exert maximum power. This flexible air intake adjustment function not only improves the adaptability and economy of the motorcycle, but also enhances the driving experience.

[0036] Specifically, the air inlet has a trumpet-shaped flared portion 72 extending outward. The design of the trumpet-shaped flared portion 72 can expand the air inlet area, allowing air to flow more smoothly into the air inlet channel 71, reducing resistance during the air intake process, and improving air intake efficiency. At the same time, the trumpet-shaped flared portion 72 can also play a certain flow guiding role, guiding air to flow in the direction of the air inlet channel 71, further optimizing the air intake effect.

[0037] Figures 1 to 4 As shown, the seat cushion frame 4 has two support rods 41 extending to the sides of the support frame 3. The ends of the two support rods 41 are fixed on the corresponding side support frames 3, respectively. The upper ends of the mounting seats 8 are bolted to the bottom sides of the seat cushion frame 4, and the lower ends of the mounting seats 8 are bolted to the ends of the two support rods 41, respectively. This structure design makes the connection between the seat cushion frame 4 and the support frame 3 more firm, and the support rods 41 provide additional support for the seat cushion frame 4, enhancing the stability and load capacity of the seat cushion frame 4, ensuring the comfort and safety of the rider during riding. At the same time, the bolt connection makes it easy to install and disassemble, facilitating the maintenance and replacement of the seat cushion frame 4 and the mounting seat 8, improving the maintainability of the frame.

[0038] Specifically, the outer end of the air inlet channel 71 penetrates to the outside of the side wall of the mounting seat 8, and the outer end of the control rod 74 has an operating handle 75. The provision of the operating handle 75 provides a convenient operating method for the rider, who can easily rotate the control rod 74 by operating the handle 75, thereby adjusting the opening degree of the air inlet. This design makes the adjustment of the air intake more intuitive and convenient, and the rider can complete the operation without leaving the seat, improving the convenience and comfort of driving. At the same time, the operating handle 75 can be designed in different shapes and materials according to actual needs to meet different use requirements and aesthetic requirements.

[0039] As Figure 4As shown, the support frame 3 comprises a main beam pipe 31, the front end of the main beam pipe 31 is provided with a steering pipe 32, the steering pipe 32 is movably connected with the front wheel frame 1, and the movable connection mode enables the motorcycle to be flexibly steered, ensuring the maneuverability and flexibility of driving. The steering pipe 32 is provided with two lower bent pipes 33 located below the main beam pipe 31 and opening towards the main beam pipe 31, the end portions of the two lower bent pipes 33 are provided with a connecting pipe 34, the rear end of the main beam pipe 31 is provided with two upper bent pipes 35 opening towards the two lower bent pipes 33, and the main beam pipe 31, the steering pipe 32, the two lower bent pipes 33, the two upper bent pipes 35 and the connecting pipe 34 are welded to form the mounting position 5. The structure rationally utilizes the space and forms a stable frame structure, which provides reliable support for the installation of the engine 11. At the same time, the structure is also beneficial to the overall strength and stability of the frame and can bear various loads in the driving process of the motorcycle, ensuring the safety and durability of the frame.

[0040] Specifically, the front end of the seat frame 4 is fixed on the upper side of the two upper bent pipes 35 on both sides, and the fixed mode makes the connection between the seat frame 4 and the support frame 3 more firm, which can better bear the weight of the rider, and is also beneficial to maintaining the stability and comfort of the seat frame 4. The lower ends of the two support rods 41 are fixed on the lower side of the two upper bent pipes 35, respectively, and the support rods 41 provide additional support for the seat frame 4, enhance the structural strength of the seat frame 4, and further improve the comfort and safety of the rider. The two sides of the flat fork frame 2 are rotatably connected to the lower side of the two upper bent pipes 35 and are located below the connecting pipe 34, and the connection mode enables the flat fork frame 2 to flexibly swing up and down, thereby realizing the suspension function of the motorcycle, buffering the bumps in the driving process, and improving the comfort of riding. At the same time, the overall structure of the frame is more compact and the space utilization is more reasonable, which is beneficial to the overall design and performance optimization of the motorcycle.

[0041] In the description of the present application, it should be explained that the terms "upper", "lower", "front", "rear", "inner", "outer" and the like indicate the orientation or positional relationship shown in the drawings, or the orientation or positional relationship commonly used when the product of the present application is used, which is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the indicated device or element must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation of the present application.

[0042] The above has carried out the detailed introduction to the motorcycle frame of the top air inlet type provided by the utility model, the principle and implementation mode of the utility model are described in this paper by applying specific examples, the above embodiment is only used for helping understanding the utility model and core idea, it should be pointed out that, for ordinary skilled person in the art, on the premise of not departing from the principle of the utility model, the utility model can also be improved and modified in several ways, and these improvements and modifications also fall within the protection scope of the utility model claims.

Claims

1. A top-intake motorcycle frame, comprising a front wheel frame, a swingarm frame, and a support frame, wherein the front end of the support frame is movably connected to the front wheel frame, and the rear end is movably connected to the swingarm frame; a seat frame is fixedly mounted on the support frame above the swingarm frame and inclined upwards at its rear end; and the support frame has a mounting position for mounting an engine. The frame is characterized by: The seat frame has an installation space located at the rear end of the support frame. The installation space contains an air intake pipe and a mounting base fixed to the seat frame. One end of the air intake pipe passes through the mounting base and is fixed to it. The other end passes through the installation space, through the seat frame, and extends from above the support frame to the mounting position to connect with the engine's throttle valve. A cap is provided at the end of the air intake pipe away from the engine. One side of the cap is hinged to the mounting base, and the other side is fixed to the mounting base by a latch. The air intake pipe has an air intake channel extending outward. Multiple air inlets are provided on the side wall of the air intake channel near the front wheel. A control lever is provided at the outer end of the air intake channel to extend into the air intake channel and control the opening amount of the air inlets.

2. A top-charge motorcycle frame according to claim 1, characterized in that: The intake pipe has a downward-opening V-shaped structure. The mounting base has a passage opening. The seat frame has a mounting opening that communicates with the mounting space. One arm of the intake pipe extends from the mounting opening into the mounting space and extends out of the passage opening. The other arm of the intake pipe extends from the top of the support frame into the mounting position and connects to the throttle valve.

3. A top-charge motorcycle frame according to claim 2, characterized in that: The intake pipe has an annular baffle extending outward from the port near the mounting base. The annular baffle abuts against the edge of the through-hole of the mounting base. The edge of the annular baffle away from the mounting base has a flange. The cover has an annular wall that cooperates with the flange, is inserted into the intake pipe, and abuts against the inner wall of the flange.

4. A top-charge motorcycle frame according to claim 2, characterized in that: The air intake passage is located on the wall of the air intake pipe at the installation space, and a turbocharger driven by the engine is installed inside the air intake pipe.

5. A top-charge motorcycle frame according to claim 4, characterized in that: The control lever extends into the air intake channel and is threadedly connected to the air intake channel. By rotating the position of the control lever in the air intake channel, the air intake port can be connected to or disconnected from the air intake channel.

6. A top-charge motorcycle frame according to any one of claims 1 to 5, characterized in that: The air inlet has a flared, outward-extending flare.

7. A top-charge motorcycle frame according to claim 1, characterized in that: The seat cushion frame has support rods extending to the lower sides of the support frame on both sides. The ends of the two support rods are fixed to the corresponding side support frame. The upper sides of the mounting base are fixed to the bottom sides of the seat cushion frame with bolts, and the lower end of the mounting base is fixed to the ends of the two support rods with bolts.

8. A top-charge motorcycle frame according to claim 1, characterized in that: The outer end of the air intake channel extends to the outside of the side wall of the mounting base, and the outer end of the control rod has an operating handle.

9. A top-charge motorcycle frame according to claim 1, characterized in that: The support frame includes a main beam tube, a steering tube at the front end of the main beam tube, the steering tube being movably connected to the front wheel frame, and two downward-curved tubes located below the main beam tube and opening towards the main beam tube on the steering tube, with a connecting tube between the ends of the two downward-curved tubes. The rear end of the main beam tube has two upward-curved tubes opening towards the two downward-curved tubes. The main beam tube, steering tube, two downward-curved tubes, two upward-curved tubes, and connecting tube form the mounting position.

10. A top-charge motorcycle frame according to claim 9, characterized in that: The front sides of the seat frame are fixed to the upper sides of the two upper curved tubes, and the lower ends of the two support rods are fixed to the lower sides of the two upper curved tubes. The two sides of the flat fork frame are rotatably connected to the lower sides of the two upper curved tubes and are located below the connecting rod.

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