Expandable bridge chassis, design method thereof and movable lifting working platform

Abstract

The invention discloses a bridge-expandable chassis, which comprises a frame, the axle components comprise a first assembly and a second assembly which are arranged on one side of the frame, the first assembly comprises a first swing leg and a wheel installed at the first end of the first swing leg, the second assembly comprises a second swing leg and a wheel installed at the first end of the second swing leg, and the part between the first end and the second end of the first swing leg is hinged to the frame; the second end of the second swing leg is hinged with the frame; the driving component comprises a first connecting rod, a second connecting rod and a double-end piston rod telescopic cylinder, and the double-end piston rod telescopic cylinder comprises a cylinder barrel fixedly connected with the frame, a piston located in the cylinder barrel and a double-end piston rod which is fixedly connected with the piston and penetrates through the cylinder barrel; the two ends of the first connecting rod are hinged to the second end of the first swing leg and the first end of the double-end piston rod respectively, and the two ends of the second connecting rod are hinged to the part between the first end and the second end of the second swing leg and the second end of the double-end piston rod respectively.

Description

Technical Field

[0001] The present invention relates to the technical field of engineering and special machinery, and particularly relates to an expandable bridge chassis and a mobile elevating work platform. Background Art

[0002] Expandable bridge chassis are used in some construction machinery or special machinery fields. For example, some mobile elevating work platforms with high lifting heights use frames with expandable bridge functions to increase the overall operating stability of the machine. A mobile elevating work platform is a device in high-altitude operation fields such as building construction, indoor and outdoor decoration, and steel structure. During transportation, the mobile elevating work platform can use the expandable bridge chassis to retract the outriggers and reduce the overall width of the vehicle to meet the size limit requirements for road transportation or driving. During operation, the expandable bridge function can be used to expand the outriggers and increase the span of the outriggers, bringing better operating stability to the mobile elevating work platform with a high lifting height. The chassis of the mobile elevating work platform with the known technology of the inventor is as Figure 1 and Figure 2 shown, including a frame 3a, a front axle component 1a, a rear axle component 2a, and four expandable bridge cylinders 4a. The front axle component 1a and the rear axle component 2a each have two outriggers 5a. The four outriggers 5a are respectively hinged to the frame 3a through pins. One end of each of the four expandable bridge cylinders 4a is connected to the frame through a pin, and the other end is connected to the outrigger through a pin. The four outriggers can rotate around the pins connecting the outriggers and the frame through the expansion and contraction of the expandable bridge cylinders, thereby realizing the actions of expanding and retracting the bridge. When the vehicle is in the transportation or road driving state, the expandable bridge cylinders contract, and the axles are retracted as Figure 2 shown. When the vehicle needs to be converted to the operating state, the four expandable bridge cylinders extend synchronously to make the outriggers expand synchronously, so that the vehicle reaches the expandable bridge state as Figure 1 . Summary of the Invention

[0003] The purpose of the present invention is to provide an expandable bridge chassis that can be simple and compact in structure and can reliably realize the expansion and contraction of the axles, a mobile elevating work platform applying the expandable bridge chassis, and a design method for the expandable bridge chassis.

[0004] The first aspect of the present invention discloses an expandable bridge chassis, including:

[0005] A frame;

[0006] One or more axle components, including a first component and a second component provided on one side of the frame. The first component includes a first outrigger and a wheel installed at the first end of the first outrigger. The second component includes a second outrigger and a wheel installed at the first end of the second outrigger. The part between the first end and the second end of the first outrigger is hinged to the frame, and the second end of the second outrigger is hinged to the frame;

[0007] A driving component, comprising a first connecting rod, a second connecting rod and a double-headed piston rod telescopic cylinder. The double-headed piston rod telescopic cylinder includes a cylinder barrel fixedly connected to the vehicle frame, a piston located in the cylinder barrel, and a double-headed piston rod fixedly connected to the piston and passing through the cylinder barrel. Two ends of the first connecting rod are respectively hinged to a second end of the first swing leg and a first end of the double-headed piston rod. Two ends of the second connecting rod are respectively hinged to a part between a first end and a second end of the second swing leg and a second end of the double-headed piston rod.

[0008] In some embodiments, a distance between a hinge point of the double-headed piston rod hinged to the first connecting rod and a hinge point of the double-headed piston rod hinged to the second connecting rod is equal to twice a length of a movement range of the piston moving in the cylinder barrel, and the hinge point of the double-headed piston rod hinged to the first connecting rod and the hinge point of the double-headed piston rod hinged to the second connecting rod are symmetrically distributed relative to the piston.

[0009] In some embodiments, a distance between a hinge point of the first swing leg hinged to the vehicle frame and a hinge point of the first swing leg hinged to the first connecting rod is equal to a distance between a hinge point of the second swing leg hinged to the vehicle frame and a hinge point of the second swing leg hinged to the second connecting rod.

[0010] In some embodiments, a length of the first connecting rod is equal to a length of the second connecting rod.

[0011] In some embodiments, a midpoint of a connection line between a hinge point of the first swing leg hinged to the vehicle frame and a hinge point of the second swing leg hinged to the vehicle frame is a midpoint of a movement range of the piston in the cylinder barrel.

[0012] In some embodiments, the expandable bridge chassis has a bridge retraction state in which a first swing leg and a second swing leg of the axle component are close to each other and a bridge expansion state in which the first swing leg and the second swing leg of the axle component are away from each other. In the bridge retraction state, the piston is in a first limit position in the cylinder barrel. In the bridge expansion state, the piston is in a second limit position opposite to the first limit position in the cylinder barrel. A connection line between a hinge point of the first swing leg hinged to the first connecting rod and a hinge point of the second swing leg hinged to the second connecting rod is parallel in the bridge retraction state and in the bridge expansion state, and is parallel to a movement track of the piston moving between the first limit position and the second limit position.

[0013] In some embodiments, the expandable bridge chassis includes two relatively arranged axle components, and the two axle components are respectively arranged on a front side and a rear side of the vehicle frame.

[0014] The second aspect of the present invention discloses a mobile lifting work platform, including any one of the expandable bridge chassis described above.

[0015] The third aspect of the present invention discloses a design method for any one of the expandable bridge chassis. The expandable bridge chassis has a bridge retraction state in which the first swing leg and the second swing leg of the axle assembly are close to each other and a bridge expansion state in which the first swing leg and the second swing leg of the axle assembly are far from each other. The hinge point of the first swing leg hinged to the vehicle frame is point O1, and the hinge point of the second swing leg hinged to the vehicle frame is point O2. The design method for the expandable bridge chassis includes:

[0016] Step 100: Determine the size of the radius length R, the position of point O1, and the position of point O2. With point O1 as the center, draw a first circle with a radius length of R. With point O2 as the center, draw a second circle with a radius length of R.

[0017] Step 200: Include method F1 or method F2. Method F1 includes: Take point a and point a' on the first circle as the hinge points of the first swing leg and the first connecting rod in the bridge retraction state and the bridge expansion state respectively; Connect point a and point a' to form line segment aa'; Translate line segment aa' to the second circle so that both endpoints of line segment aa' are on the second circle. The point on the second circle that coincides with the endpoint corresponding to point a of line segment aa' at this time is taken as point b, and the point on the second circle that coincides with the endpoint corresponding to point a' of line segment aa' at this time is taken as point b'. Method F2 includes: Take point b and point b' on the second circle as the hinge points of the second swing leg and the second connecting rod in the bridge retraction state and the bridge expansion state respectively; Connect point b and point b' to form line segment bb'; Translate line segment bb' to the first circle so that both endpoints of line segment bb' are on the first circle. The point on the first circle that coincides with the endpoint corresponding to point b of line segment bb' at this time is taken as point a, and the point on the first circle that coincides with the endpoint corresponding to point b' of line segment bb' at this time is taken as point a'.

[0018] Step 300: Draw a k line segment that is symmetric about the midpoint of the line connecting point O1 and point O2 and parallel to the line connecting point a and point b through the midpoint of the line connecting point O1 and point O2. The two endpoints of the k line segment are used as the first extreme position and the second extreme position of the piston. In the bridge retraction state, the piston is in the first extreme position in the cylinder. In the bridge expansion state, the piston is in the second extreme position opposite to the first extreme position in the cylinder. Take the length of the k line segment as the length of the aa' line segment plus x0. Take two points on the extension lines on both sides of the k line segment at a distance of y from the two endpoints of the k line segment respectively. The point closer to the first circle is point C1, and the point closer to the second circle is point C2.

[0019] Step 400: Use point C1 as the hinge point of the double-headed piston rod and the first connecting rod in the bridge-expanded state, and use point C2 as the hinge point of the double-headed piston rod and the second connecting rod in the bridge-retracted state;

[0020] Step 500: After step 400, correct and determine the length of line segment k.

[0021] In some embodiments, correcting and determining the length of line segment k after step 400 includes:

[0022] Model the bridge-expandable chassis using the data obtained after step 400. Starting from the bridge-retracted state of the bridge-expandable chassis model, move the piston from the second extreme position to the first extreme position, and verify whether the hinge point of the first connecting rod and the double-rod piston rod reaches point a from point a';

[0023] If the hinge point of the first connecting rod and the double-rod piston rod reaches point a, determine the length of line segment k at this time;

[0024] If the hinge point of the first connecting rod and the double-rod piston rod exceeds point a, decrease the value of x0 and continue with step 500;

[0025] If the hinge point of the first connecting rod and the double-rod piston rod does not reach point a, increase the value of x0 and continue with step 500.

[0026] In some embodiments, translating the aa' line segment onto the second circle such that both endpoints of the aa' line segment are located on the second circle includes: Translating the aa' line segment onto the part of the second circle that is on the opposite side of the line connecting points O1 and O2 from point a.

[0027] In some embodiments, the value of y is 0.

[0028] Based on the bridge-expandable chassis provided by the present invention, by setting components such as the first connecting rod, the second connecting rod, and the double-headed piston rod telescopic cylinder, only one telescopic cylinder can be used in one axle component to simultaneously control the two swing legs of the axle component to contract or expand simultaneously, with a simple and compact structure and good synchronism.

[0029] Through the following detailed description of the exemplary embodiments of the present invention with reference to the accompanying drawings, other features and advantages of the present invention will become clear. Description of the Drawings

[0030] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of this application. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0031] Figure 1 Structural schematic diagram of a bridge-expandable chassis known to the inventor in the bridge-expanded state;

[0032] Figure 2 For Figure 1 The structural schematic diagram of the expandable bridge chassis in the bridge retracted state as shown;

[0033] Figure 3 The structural schematic diagram of the mobile lifting work platform according to an embodiment of the present invention;

[0034] Figure 4 The structural schematic diagram of the expandable bridge chassis according to an embodiment of the present invention in the bridge retracted state;

[0035] Figure 5 For Figure 4 The structural schematic diagram of the expandable bridge chassis as shown in the bridge expanded state;

[0036] Figure 6 The process schematic diagram of the design method of the expandable bridge chassis according to an embodiment of the present invention;

[0037] Figure 7 The process schematic diagram of the design method of the expandable bridge chassis according to another embodiment of the present invention. Detailed implementation manners

[0038] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and in no way limits the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0039] Unless otherwise specifically stated, the relative arrangements, numerical expressions, and numerical values of the components and steps set forth in these embodiments do not limit the scope of the present invention. At the same time, it should be understood that for the convenience of description, the dimensions of the various parts shown in the drawings are not drawn in actual proportional relationships. Technologies, methods, and devices known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, the technologies, methods, and devices should be regarded as part of the description. In all the examples shown and discussed here, any specific value should be construed as merely exemplary and not as a limitation. Therefore, other examples of the exemplary embodiments may have different values. It should be noted that: like reference numerals and letters denote like items in the following drawings, and therefore, once an item is defined in one drawing, it does not need to be further discussed in subsequent drawings.

[0040] In the description of the present invention, it should be understood that the use of terms such as "first" and "second" to limit components is only for the convenience of distinguishing the corresponding components. Without further statement, the above terms have no special meaning, so it cannot be understood as a limitation on the protection scope of the present invention.

[0041] In the description of the present invention, it should be noted that unless otherwise clearly specified and limited, the terms "mounted", "connected" and "coupled" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected, or indirectly connected through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0042] For the convenience of description, spatial relative terms such as "above", "on top of", "on the upper surface", "upper" etc. can be used here to describe the spatial position relationship between a device or feature shown in the figure and other devices or features. It should be understood that the spatial relative terms are intended to include different orientations in use or operation in addition to the orientation described in the figure of the device. For example, if the device in the drawing is inverted, the device described as "above other devices or structures" or "on top of other devices or structures" will be positioned as "below other devices or structures" or "beneath other devices or structures" afterwards. Thus, the exemplary term "above" can include both the orientations of "above" and "below". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and corresponding interpretations are made for the spatial relative descriptions used here.

[0043] As Figures 3 to 5 shown, the expandable bridge chassis 120 of this embodiment includes a vehicle frame 1, more than one axle component and a driving component.

[0044] Vehicle frame 1;

[0045] The axle components include a first component and a second component provided on one side of the vehicle frame 1. In the embodiments shown in Figure 4 and Figure 5 the expandable bridge chassis includes two axle components, and the two axle components are respectively located at the front side and the rear side of the vehicle frame 1 along the traveling direction of the expandable bridge chassis. The first component includes a first swing leg 21 and a wheel 23 mounted on the first end of the first swing leg 21. The second component includes a second swing leg 22 and a wheel 23 mounted on the first end of the second swing leg 22. The part between the first end and the second end of the first swing leg 21 is hinged to the vehicle frame 1, and the second end of the second swing leg 22 is hinged to the vehicle frame 1. The wheel 23 is rotatably mounted on the swing leg, and the wheel 23 is used for the walking of the expandable bridge chassis. In some embodiments, the wheel 23 is driven to rotate by a motor provided on the swing leg.

[0046] The driving component includes a first connecting rod 31, a second connecting rod 32 and a double-headed piston rod telescopic cylinder. The double-headed piston rod telescopic cylinder includes a cylinder barrel 331 fixedly connected to the vehicle frame 1, a piston located in the cylinder barrel 331, and a double-headed piston rod 332 fixedly connected to the piston and passing through the cylinder barrel 331. The double-headed piston rod refers to a piston rod with both ends extending out of the cylinder barrel. The movement of the piston in the cylinder barrel 331 can drive the double-headed piston rod and the piston to move in the same direction. The double-headed piston rod telescopic cylinder includes a double-headed piston rod oil cylinder or a double-headed piston rod air cylinder. The two ends of the first connecting rod 31 are respectively hinged to the second end of the first swing leg 21 and the first end of the double-headed piston rod 332. The two ends of the second connecting rod 32 are respectively hinged to a part between the first end and the second end of the second swing leg 22 and the second end of the double-headed piston rod 332.

[0047] The bridge-expandable chassis 120 has a bridge-retracted state as shown in Figure 4 and a bridge-expanded state as shown in Figure 5 . In the bridge-retracted state, the first swing leg and the second swing leg of the axle component are close to each other. In the bridge-expanded state, the first swing leg and the second swing leg of the axle component are far from each other. The piston can reciprocate in the cylinder barrel 331. When the piston is driven to move from one end of the cylinder barrel to the other end, the piston can drive the double-headed piston rod to move in one direction. The two ends of the double-headed piston rod respectively drive the first connecting rod 31 and the second connecting rod 32 to act, and respectively drive the first swing leg 21 and the second swing leg to rotate relative to the vehicle frame through the first connecting rod 31 and the second connecting rod 32, so that the first swing leg 21 and the second swing leg 22 are close to each other or far from each other. By reciprocating the piston in the cylinder barrel, the bridge-expandable chassis can be switched between the bridge-retracted state and the bridge-expanded state.

[0048] For the bridge-expandable chassis 120 of this embodiment, by arranging components such as the first connecting rod 31, the second connecting rod 32 and the double-headed piston rod telescopic cylinder, one telescopic cylinder can be used to simultaneously control the two swing legs of the axle component to contract or expand at the same time, with a simple and compact structure and good synchronism.

[0049] In some embodiments, the distance between the hinge point of the double-headed piston rod 332 hinged to the first connecting rod 31 and the hinge point of the double-headed piston rod 332 hinged to the second connecting rod 32 is equal to twice the length of the movement range of the piston moving in the cylinder 331, and the hinge point of the double-headed piston rod 332 hinged to the first connecting rod 31 and the hinge point of the double-headed piston rod 332 hinged to the second connecting rod 32 are symmetrically distributed relative to the piston. The piston moves linearly in the cylinder 331, and its extreme positions of movement are the first extreme position and the second extreme position respectively. The range between the first extreme position and the second extreme position is the movement range of the piston in the cylinder, that is, in this embodiment, the distance between the hinge point of the double-headed piston rod 332 hinged to the first connecting rod 31 and the hinge point of the double-headed piston rod 332 hinged to the second connecting rod 32 is twice the distance between the first extreme position and the second extreme position. The hinge point of the double-headed piston rod 332 hinged to the first connecting rod 31 and the hinge point of the double-headed piston rod 332 hinged to the second connecting rod 32 are symmetrically distributed relative to the piston, that is, the distance from the hinge point of the double-headed piston rod 332 hinged to the first connecting rod 31 to the piston is equal to the distance from the hinge point of the double-headed piston rod 332 hinged to the second connecting rod 32. In some embodiments, in the bridge retracted state, the piston is at the first extreme position in the cylinder 331, and in the bridge extended state, the piston is at the second extreme position opposite to the first extreme position in the cylinder 331. Thus, when the piston moves to the first extreme position, the hinge point of the double-headed piston rod 332 hinged to the first connecting rod 31 is the farthest from the cylinder, and the hinge point of the double-headed piston rod 332 hinged to the second connecting rod 32 reaches the second extreme position. When the piston moves to the second extreme position, the hinge point of the double-headed piston rod 332 hinged to the second connecting rod 32 is the farthest from the cylinder, and the hinge point of the double-headed piston rod 332 hinged to the first connecting rod 31 reaches the first extreme position. That is, the cylinder of this embodiment can be made to have a length close to the distance between the first extreme position and the second extreme position, making the cylinder as short as possible, and at the same time making the length of the double-headed piston rod approximately equal to twice the distance between the first extreme position and the second extreme position, making the length of the double-headed piston rod as short as possible, so as to make the overall structure of the double-headed piston rod telescopic cylinder compact.

[0050] In some embodiments, the distance between the hinge point where the first swing leg 21 is hinged to the vehicle frame 1 and the hinge point where the first swing leg 21 is hinged to the first connecting rod 31 is equal to the distance between the hinge point where the second swing leg 22 is hinged to the vehicle frame 1 and the hinge point where the second swing leg 22 is hinged to the second connecting rod 32. This helps to make the angles of the first swing leg and the second swing leg relative to the vehicle frame rotation closer or the same.

[0051] In some embodiments, the length of the first connecting rod 31 is equal to the length of the second connecting rod 32. The equal lengths of the first connecting rod and the second connecting rod in this embodiment help to make the angles of the first swing leg and the second swing leg relative to the vehicle frame rotation closer or the same.

[0052] In some embodiments, the midpoint of the line connecting the hinge points where the first swing leg 21 is hinged to the vehicle frame 1 and the hinge points where the second swing leg 22 is hinged to the vehicle frame 1 is the midpoint of the moving range of the piston within the cylinder barrel 331. That is, the center of the cylinder barrel 331 in this embodiment is located at the midpoint of the line connecting the hinge points where the first swing leg 21 is hinged to the vehicle frame 1 and the hinge points where the second swing leg 22 is hinged to the vehicle frame 1.

[0053] In some embodiments, the expandable axle chassis 120 has a bridge-retracted state in which the first swing leg 21 and the second swing leg 22 of the axle components approach each other, and a bridge-expanded state in which the first swing leg 21 and the second swing leg 22 of the axle components move away from each other. In the bridge-retracted state, the piston is at the first extreme position within the cylinder barrel 331. In the bridge-expanded state, the piston is at the second extreme position opposite to the first extreme position within the cylinder barrel 331. The line connecting the hinge points where the first swing leg 21 is hinged to the first link 31 and the hinge points where the second swing leg 22 is hinged to the second link is parallel in the bridge-retracted state and in the bridge-expanded state, and is parallel to the movement trajectory of the piston moving between the first extreme position and the second extreme position. When switching from the bridge-retracted state to the bridge-expanded state in this embodiment, the swing angles of the first swing leg and the second swing leg relative to the vehicle frame are the same, and the expandable axle chassis can support more stably and evenly on the ground.

[0054] In some embodiments, the expandable axle chassis includes two relatively arranged axle components, such as Figure 3 and Figure 5 shown, and the two axle components are respectively arranged on the front side and the rear side of the vehicle frame 1. The front side and the rear side are referenced with the traveling direction when the expandable axle chassis is installed and traveling, the forward direction is the front, and the backward direction is the rear.

[0055] In some embodiments, as Figure 3 shown, a mobile lifting work platform 100 is also disclosed. The mobile lifting work platform 100 includes any of the above-mentioned expandable axle chassis 120. The mobile lifting work platform 100 includes a work platform 110. The work platform 110 is installed on the workbench through a boom 130, and the workbench is installed on the expandable axle chassis 120. When the boom 130 rotates relative to the workbench, the work platform 110 can be raised or lowered, that is, the height of the operator on the work platform 110 can be adjusted. When the expandable axle chassis 120 moves, the entire mobile lifting work platform 10 moves.

[0056] In some embodiments, as Figure 6 and Figure 7Also disclosed is a design method for any of the above expandable bridge chassis 120. The expandable bridge chassis 120 has a bridge retraction state in which the first swing leg 21 and the second swing leg 22 of the axle component are close to each other, and a bridge expansion state in which the first swing leg 21 and the second swing leg 22 of the axle component are far from each other. The hinge point of the first swing leg 21 hinged to the vehicle frame 1 is point O1, and the hinge point of the second swing leg 22 hinged to the vehicle frame 1 is point O2. Figure 6 and Figure 7 In Figure 6 and Figure 7 , the solid-line first swing leg and second swing leg are the first swing leg and second swing leg in the bridge retraction state, and the dashed-line first swing leg and second swing leg are the first swing leg and second swing leg in the bridge expansion state. The design method for the expandable bridge chassis 120 includes:

[0057] Step 100: Determine the size of the radius length R, the position of point O1, and the position of point O2. With point O1 as the center, draw a first circle with a radius length of R. With point O2 as the center, draw a second circle with a radius length of R. The size of the radius length R can be selected as an appropriate value according to parameters such as the structural dimensions of the expandable bridge chassis.

[0058] Step 200 includes method F1 or method F2. Method F1 includes: Take point a and point a' on the first circle as the hinge points of the first swing leg 21 and the first link 31 in the bridge retraction state and the bridge expansion state respectively; Connect point a and point a' to form line segment aa'; Translate line segment aa' onto the second circle such that both endpoints of line segment aa' are on the second circle. The point on the second circle that coincides with the endpoint corresponding to point a of line segment aa' at this time is point b, and the point on the second circle that coincides with the endpoint corresponding to point a' of line segment aa at this time is point b'. Method F2 includes: Take point b and point b' on the second circle as the hinge points of the second swing leg 22 and the second link 32 in the bridge retraction state and the bridge expansion state respectively; Connect point b and point b' to form line segment bb'; Translate line segment bb' onto the first circle such that both endpoints of line segment bb' are on the first circle. The point on the first circle that coincides with the endpoint corresponding to point b of line segment bb' at this time is point a, and the point on the first circle that coincides with the endpoint corresponding to point b' of line segment bb' at this time is point a'.

[0059] Step 300: Pass through the midpoint of the line connecting point O1 and point O2 and draw a line parallel to the line connecting point a and point b with respect to the midpoint of the line connecting point O1 and point O2 (such as Figure 6 and Figure 7k line segments symmetric about the point O (shown). The two endpoints of the k line segment are used as the first and second limit positions of the piston. In the bridge retracted state, the piston is at the first limit position within the cylinder 331. In the bridge extended state, the piston is at the second limit position opposite the first limit position within the cylinder 331. Take the length of the k line segment as the length of the aa' line segment plus x0. Take two points on the extension lines on both sides of the k line segment at a distance of y from the two endpoints of the k line segment. The point closer to the first circle is point C1, and the point closer to the second circle is point C2. The value of y can be arbitrarily taken as a smaller value not greater than R according to the positions of the hinge points of the first swing leg and the second swing leg with the vehicle frame.

[0060] Step 400: Use point C1 as the hinge point between the double-headed piston rod 332 and the first connecting rod 31 in the bridge extended state, and use point C2 as the hinge point between the double-headed piston rod 332 and the second connecting rod 32 in the bridge retracted state.

[0061] Step 500: After step 400, correct and determine the length of the k line segment.

[0062] In some embodiments, correcting and determining the length of the k line segment after step 400 includes:

[0063] Use the data obtained after step 400 to model the bridge-expandable chassis 120. Start from the bridge retracted state of the bridge-expandable chassis 120 model, move the piston from the second limit position to the first limit position, and verify whether the hinge point between the first connecting rod 31 and the double-rod piston rod reaches point a' to point a.

[0064] If the hinge point between the first connecting rod 31 and the double-rod piston rod reaches point a, then determine the length of the k line segment at this time.

[0065] If the hinge point between the first connecting rod 31 and the double-rod piston rod exceeds point a, then decrease the value of x0 and continue with step 500.

[0066] If the hinge point between the first connecting rod 31 and the double-rod piston rod does not reach point a, then increase the value of x0 and continue with step 500.

[0067] That is, in this embodiment, it is necessary to determine the length of the k-segment, mainly by correcting the value of x0 to determine the length of the k-segment. The initial value of x0 can be taken as a relatively small arbitrary number. For example, 5% of the length of the aa' segment can be taken as the initial value of x0, so as to obtain the initial value of the length of the k-segment. According to the initial value of x0, combined with the steps of the previous embodiment, the position of the hinge point C1 of the double-headed piston rod 332 and the first connecting rod 31 can be designed when in the bridge-expanding state, that is, when the piston is at the end point of the k-segment close to the second circle, that is, at the second limit position. The a' point is also the position of the hinge point of the first connecting rod 31 and the first swing leg in the bridge-expanding state. According to the initial value of the length of the k-segment, the position and angle of the k-segment, and the position of the O1 point, a model of the double-headed piston rod telescopic cylinder driving the first swing leg to swing through the first connecting rod is established. Initially, the piston is at the end point of the k-segment close to the second circle, that is, the second limit position. At this time, the hinge point of the first connecting rod and the first swing leg is at the a' point. Simulate when the piston moves from the second limit position to the first limit position, that is, the end point position of the k-segment close to the first circle. Whether the double-headed piston rod can drive the hinge point of the first swing leg and the first connecting rod to the a point through the first connecting rod. If the hinge point of the first connecting rod 31 and the double-rod piston rod reaches the a point, it means that the value of x0 is appropriate, and the length of the k-segment at this time is determined. If the hinge point of the first connecting rod 31 and the double-rod piston rod exceeds the a point, it means that the value of x0 is too large, and the value of x0 needs to be reduced. Continue with step 500, that is, verify and determine the length of the k-segment according to the new value of x0. If the hinge point of the first connecting rod 31 and the double-rod piston rod does not reach the a point, it means that the value of x0 is too small, and the value of x0 needs to be increased. Continue with step 500. When the length of the k-segment is verified and determined, the hinge point positions between various components such as the first connecting rod, the second connecting rod, the first swing leg, and the second swing leg can be determined, so that a bridge-expandable chassis with equal swing angles of the first swing leg and the second swing leg when switching between the bridge-retracting state and the bridge-expanding state can be designed.

[0068] In some embodiments, the modeling can be carried out through 3D software such as UG, CATIA, CAD, etc.

[0069] In some embodiments, after step 400, the correction and determination of the length of the k-segment can also be calculated by means of geometric construction.

[0070] In some embodiments, translating the aa' segment onto the second circle such that both end points of the aa' segment are on the second circle includes: translating the aa' segment onto the part of the second circle that is on the opposite side of the line connecting O1 and O2 from the a point on the first circle. That is, the b point and the b' point obtained on the second circle are on the opposite side of the line connecting O1 and O2 from the a point and the a' point on the first circle.

[0071] In some embodiments, the value of y is 0. The cylinder barrel of this embodiment can be made to have a length close to the distance between the first limit position and the second limit position, making the cylinder barrel as short as possible. At the same time, the length of the double-headed piston rod is approximately equal to twice the distance between the first limit position and the second limit position, making the length of the double-headed piston rod as short as possible, so that the overall structure of the double-headed piston rod telescopic cylinder is compact.

[0072] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them; although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that: it is still possible to modify the specific implementation manners of the present invention or perform equivalent replacements for some technical features; without departing from the spirit of the technical solutions of the present invention, they should all be covered within the scope of the technical solutions claimed by the present invention.

Claims

1. An expandable bridge chassis (120), characterized in that, it includes: a vehicle frame (1); more than one axle component, including a first component and a second component provided on one side of the vehicle frame (1), the first component includes a first swing leg (21) and a wheel (23) installed at the first end of the first swing leg (21), the second component includes a second swing leg (22) and a wheel (23) installed at the first end of the second swing leg (22), the part between the first end and the second end of the first swing leg (21) is hinged to the vehicle frame (1), and the second end of the second swing leg (22) is hinged to the vehicle frame (1); a driving component, including a first connecting rod (31), a second connecting rod (32) and a double-headed piston rod telescopic cylinder, the double-headed piston rod telescopic cylinder includes a cylinder barrel (331) fixedly connected to the vehicle frame (1), a piston located in the cylinder barrel (331), and a double-headed piston rod (332) fixedly connected to the piston and passing through the cylinder barrel (331), both ends of the first connecting rod (31) are respectively hinged to the second end of the first swing leg (21) and the first end of the double-headed piston rod (332), and both ends of the second connecting rod (32) are respectively hinged to the part between the first end and the second end of the second swing leg (22) and the second end of the double-headed piston rod (332).

2. The expandable bridge chassis (120) according to claim 1, characterized in that, the distance between the hinge point of the double-headed piston rod (332) hinged to the first connecting rod (31) and the hinge point of the double-headed piston rod (332) hinged to the second connecting rod (32) is equal to twice the length of the movement range of the piston in the cylinder barrel (331), and the hinge point of the double-headed piston rod (332) hinged to the first connecting rod (31) and the hinge point of the double-headed piston rod (332) hinged to the second connecting rod (32) are symmetrically distributed relative to the piston.

3. The expandable bridge chassis (120) according to claim 1, characterized in that, the distance between the hinge point where the first swing leg (21) is hinged to the vehicle frame (1) and the hinge point where the first swing leg (21) is hinged to the first connecting rod (31) is equal to the distance between the hinge point where the second swing leg (22) is hinged to the vehicle frame (1) and the hinge point where the second swing leg (22) is hinged to the second connecting rod (32).

4. The expandable bridge chassis (120) according to claim 3, characterized in that, the length of the first connecting rod (31) is equal to the length of the second connecting rod (32).

5. The expandable bridge chassis (120) according to claim 1, characterized in that, the midpoint of the line connecting the hinge point where the first swing leg (21) is hinged to the vehicle frame (1) and the hinge point where the second swing leg (22) is hinged to the vehicle frame (1) is the midpoint of the movement range of the piston in the cylinder barrel (331).

6. The expandable bridge chassis (120) according to claim 5, characterized in that, The expandable bridge chassis (120) has a retracted bridge state in which the first swing leg (21) and the second swing leg (22) of the axle components are close to each other and an expanded bridge state in which the first swing leg (21) and the second swing leg (22) of the axle components are far from each other. In the retracted bridge state, the piston is in a first extreme position within the cylinder barrel (331). In the expanded bridge state, the piston is in a second extreme position opposite to the first extreme position within the cylinder barrel (331). The connecting line between the hinge point where the first swing leg (21) is hinged to the first connecting rod (31) and the hinge point where the second swing leg (22) is hinged to the second connecting rod is parallel in the retracted bridge state and in the expanded bridge state, and is parallel to the movement track of the piston moving between the first extreme position and the second extreme position.

7. The expandable bridge chassis (120) according to claim 1, characterized in that, it includes two relatively arranged axle components, and the two axle components are respectively arranged on the front side and the rear side of the vehicle frame (1).

8. A mobile lifting work platform (100), characterized in that, it includes the expandable bridge chassis (120) according to any one of claims 1 to 7.

9. A design method for an expandable bridge chassis (120) according to any one of claims 1 to 7, the expandable bridge chassis (120) having a retracted bridge state in which the first swing leg (21) and the second swing leg (22) of the axle components are close to each other and an expanded bridge state in which the first swing leg (21) and the second swing leg (22) of the axle components are far from each other. The hinge point where the first swing leg (21) is hinged to the vehicle frame (1) is point O1, and the hinge point where the second swing leg (22) is hinged to the vehicle frame (1) is point O2. characterized in that, the design method for the expandable bridge chassis (120) includes: Step 100, determining the size of the radius length R, the position of point O1, and the position of point O2, making a first circle with point O1 as the center and a radius length of R, and making a second circle with point O2 as the center and a radius length of R; Step 200 includes method F1 or method F2. Method F1 includes: taking point a and point a' on the first circle as the hinge points of the first swing leg (21) and the first connecting rod (31) in the bridge retracted state and the bridge extended state respectively; connecting point a and point a' to form line segment aa'; translating line segment aa' onto the second circle such that both endpoints of line segment aa' are on the second circle, taking the point on the second circle that coincides with the endpoint of line segment aa' corresponding to point a at this time as point b, and taking the point on the second circle that coincides with the endpoint of line segment aa' corresponding to point a' at this time as point b'; Method F2 includes: taking point b and point b' on the second circle as the hinge points of the second swing leg (22) and the second connecting rod (32) in the bridge retracted state and the bridge extended state respectively; connecting point b and point b' to form line segment bb'; translating line segment bb' onto the first circle such that both endpoints of line segment bb' are on the first circle, taking the point on the first circle that coincides with the endpoint of line segment bb' corresponding to point b at this time as point a, and taking the point on the first circle that coincides with the endpoint of line segment bb' corresponding to point b' at this time as point a'. Step 300, draw a k line segment that is symmetric about the midpoint of the line connecting O1 and O2 and parallel to the line connecting point a and point b through the midpoint of the line connecting O1 and O2. Take the two endpoints of the k line segment as the first limit position and the second limit position of the piston. In the bridge retracted state, the piston is at the first limit position in the cylinder (331). In the bridge extended state, the piston is at the second limit position opposite to the first limit position in the cylinder (331). Take the length of the k line segment as the length of the aa' line segment plus x0. Take two points at a distance of y from the two endpoints of the k line segment on the extension lines on both sides of the k line segment. The point closer to the first circle is point C1, and the point closer to the second circle is point C2. Step 400, take point C1 as the hinge point of the double-headed piston rod (332) and the first connecting rod (31) in the bridge extended state, and take point C2 as the hinge point of the double-headed piston rod (332) and the second connecting rod (32) in the bridge retracted state. Step 500, after step 400, correct and determine the length of the k line segment.

10. The design method of the expandable bridge chassis (120) as described in claim 9, characterized in that correcting and determining the length of the k line segment after step 400 includes: using the data obtained after step 400 to model the expandable bridge chassis (120), starting from the bridge retracted state of the expandable bridge chassis (120) model, moving the piston from the second limit position to the first limit position, and verifying whether the hinge point of the first connecting rod (31) and the double-rod piston rod reaches point a from point a'; if the hinge point of the first connecting rod (31) and the double-rod piston rod reaches point a, then determine the length of the k line segment at this time; if the hinge point of the first connecting rod (31) and the double-rod piston rod exceeds point a, then decrease the value of x0 and continue with step 500; if the hinge point of the first connecting rod (31) and the double-rod piston rod does not reach point a, then increase the value of x0 and continue with step 500.

11. The design method of the expandable bridge chassis (120) as claimed in claim 9, characterized in that, the translation of the line segment aa' onto the second circle such that both endpoints of the line segment aa' are located on the second circle includes: translating the line segment aa' onto the part of the second circle that is on the different side of the line connecting the points O1 and O2 from the point a.

12. The design method of the expandable bridge chassis (120) as claimed in claim 9, characterized in that, the value of y is 0.

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