CN103223981A - Low-floor total-load bearing type purely electric urban public bus body structure - Google Patents

Abstract

A low-floor fully load-bearing pure electric city bus body structure relates to the field of bus structure design. The middle section of the body is an integral load-bearing double-layer truss composed of an upper frame structure, a lower frame structure, and some columns connecting them and cable-stayed plates. Structure, the distance between the upper and lower frame structures is 140±10mm, and the height of the floor from the ground is 360±10mm, which realizes a step; the intersection of the upper frame structure and the lower frame structure of the transverse and longitudinal members is in the vertical direction Alignment, small-section columns are arranged at the intersection to connect the upper and lower frames, so that the upper and lower rods and columns constitute a quadrilateral frame, and the diagonally-stayed plates are arranged on the diagonal of the quadrilateral frame, and the direction of arrangement is along the The direction in which the diagonals of the quadrilateral frame extend; the present invention adopts a low floor to facilitate passengers to get on and off the vehicle, the low floor lowers the center of gravity of the vehicle, and improves the safety, comfort and stability of the vehicle.

Description

Low-floor fully load-bearing pure electric city bus body structure

technical field

The invention relates to the field of passenger car structure design, in particular to a new full-loaded urban bus body structure.

technical background

In recent years, with the development of the economy, there are more and more private cars in cities, and the resulting road congestion and environmental pollution are becoming more and more serious. The shortage of fuel supply and soaring oil prices caused by the development of the automobile industry have become more and more prominent. At present, the easiest and most economical way to ease the traffic pressure and facilitate the travel of passengers is to vigorously develop public transportation. Compared with other means of transportation, buses have two main advantages: one is low cost; the other is that they can use existing roads, so public transportation has been highly valued in recent years, and with the continuous improvement of the current level of urbanization, Urban public transport has gradually become a hot spot, and people have put forward higher requirements for urban public transport buses.

At present, the body structure of most public transport buses operating in China is basically a multi-step fuel bus, and a small number of relatively new ones are low-entrance hybrid buses with one step.

Compared with traditional buses, low-floor pure electric buses have the following advantages:

1. my country is currently in a period of accelerated population aging, and the travel of the elderly has attracted more and more attention. Compared with ordinary buses, low-floor buses with a lower chassis and one-step distance between the interior floor and the ground are convenient for the elderly, children and disabled people to ride, and passengers get on and off the bus more quickly, which will shorten the stop time at the station , thereby improving the efficiency of bus operation and correspondingly increasing the passenger volume. At the same time, the center of gravity of the whole vehicle is lowered due to the low floor, which also improves the safety, comfort and stability of the vehicle.

2. Because electric vehicles use electric energy as the power source, compared with internal combustion engines of the same power, electric vehicles have smaller motor volume, high energy utilization, low vibration and noise, and easy operation. The station is fixed, which makes it easy to build charging facilities in places where buses are concentrated, which is highly feasible.

Through a large number of investigations and conclusions and theoretical studies, the applicant invented a reasonable low-floor load-bearing pure electric bus body structure based on the idea of full load while meeting people's needs.

Contents of the invention

The purpose of the present invention is to provide a novel low-floor fully load-bearing pure electric bus body structure suitable for market demand.

In conjunction with the accompanying drawings, the description is as follows:

The body structure of a low-floor fully load-bearing pure electric city bus is composed of front, rear, top, left and right sides, and an underframe. The middle section is composed of three parts, and each sub-assembly is a space truss structure composed of small cross-section rods. In this body structure, the passenger door is opened at the front and rear, and the middle section of the body is a complete frame structure. Double-layer truss structure, the distance between the upper and lower frame structures is 140±10mm, the height of the floor from the ground is 360±10mm, and a step is realized; the intersection of the upper frame structure and the lower frame structure of the transverse and longitudinal members is at Aligned in the vertical direction, the small cross-section columns are arranged at the intersection to connect the upper and lower frames, so that the upper and lower rods and columns constitute a quadrilateral frame, and the diagonally-stayed plates are arranged on the diagonal of the quadrilateral frame, and the direction of arrangement is along the The direction in which the diagonals of the quadrilateral frame extend in dangerous conditions; the upper and lower frame structures are composed of small-section transverse members, small-section longitudinal members and small-section diagonal braces.

Most of the transverse rods and longitudinal rods of the underframe adopt rectangular steel pipes with a section size of 40-50 mm in height, 40-50 mm in width and 2-4 mm in thickness; Rectangular steel pipe with a width of 40mm, a width of 30-40mm, and a thickness of 1.5-2.5mm; the obliquely-stayed plate in the chassis shall be a parallelogram thin plate with a width of 30-40mm and a thickness of 2-4mm.

The distance between the horizontal weld on the upper part of the inclined-stayed plate and the upper surface of the welded bar is 4-8mm, and the distance between the lower end point of the inclined weld and the lower surface of the welded bar is 4-6mm; the horizontal weld on the lower part of the inclined-stayed plate The distance between the seam and the lower surface of the welded rod is 4-8mm, and the distance between the upper end point of the oblique weld and the upper surface of the welded rod is 4-6mm; the minimum distance between the weld and the small column is 30-42mm.

The rear bridge of the double-layer truss-type underframe structure partially adopts a sloping floor with a slope of about 2° to 3°. 215mm in front of the midpoint, the downhill starts at 215mm behind the midpoint of the rear suspension, ends at 960mm behind the midpoint of the rear suspension, and ends at 215mm in front of the midpoint of the rear suspension to 215mm behind the midpoint of the rear suspension The section floor is flat.

Beneficial effects of the present invention:

The body structure can effectively reduce the non-axial load of each member of the structure, make the force of the whole vehicle more reasonable, and the load distribution more uniform, so as to maximize the potential of the structural components. Compared with similar models, the strength and rigidity of the body are higher. It has been effectively improved. Under the same conditions, the weight of the body structure can be reduced by more than 15%. The design of the weld seam keeps the heat-affected zone of the weld seam away from the high-stress area of the welded beam, thereby improving the load-carrying capacity of the structure. The invention adopts a low floor to facilitate passengers getting on and off the bus, and improves the efficiency of bus operation. It also improves the safety, comfort and stability of the vehicle; using electric energy as the power source, the space occupied by the motor is small, the utilization rate of energy is high, the vibration and noise are small, and the operation is convenient.

Description of drawings:

Figure 1 is a schematic diagram of each sub-assembly of the body structure;

Figure 2 is a schematic diagram of the vehicle;

Fig. 3 is a side view of the underframe and a schematic structural diagram of the upper and lower frames;

Fig. 4 is a side view and some partial views of the chassis;

Figure 5 is a schematic diagram of the layout of the inclined-stayed slab;

Fig. 6 is a partial plan view of the middle section of the underframe and a schematic diagram of the arrangement of the transverse slanted plates of the underframe;

Fig. 7 is a top view of the underframe and a schematic diagram of the layout of the longitudinal slanted plates;

Figure 8 is a schematic diagram of the overall layout of the vehicle;

Among them: 1. Front wall 2, rear wall 3, top cover 4, left wall 5, right wall 6, underframe 7, front door 8, rear door 9, underframe column Ⅰ10, longitudinal slanted plate Ⅰ11, transverse Inclined plate Ⅰ12, lower transverse member Ⅰ13, upper transverse member Ⅰ14, left side column I15, underframe column II16, underframe column III17, transverse inclined plate II18, longitudinal inclined plate II19, longitudinal inclined plate III20 , Longitudinal inclined-stayed plate IV21, longitudinal inclined-stayed plate V22, longitudinal inclined-stayed plate VI23, longitudinal inclined-stayed plate VII24, driver’s seat 25, vehicle controller 26, transmission 27, motor 28, motor controller B, battery

Detailed ways:

Below in conjunction with accompanying drawing and embodiment the present invention will be further described:

The body structure is shown in Figure 1, and consists of a front wall 1, a rear wall 2, a top cover 3, a left wall 4, a right wall 5, and an underframe 6. The underframe is composed of a front suspension, a rear The suspension and the middle section of the chassis are composed of three parts. Each of its sub-assemblies is a space truss structure composed of small-section rods. In this body structure, the passenger door is hung at the front and rear, which ensures the integrity of the load-bearing structure of the middle section of the body, so that the complete truss structure of the middle section of the body has a strong load-bearing capacity as a whole, as shown in Figure 2 (wherein 7 is the front door , 8 is the rear door). The main transmission path of the load on the body structure is: the load is quickly transmitted from the underframe structure to the left and right side panels, and then transmitted from the left and right side panel structures to the front and rear suspension structures.

The underframe of the vehicle body is shown in Figure 3. It is an integral load-bearing double-layer truss structure composed of the upper frame structure, the lower frame structure and some connecting columns and cable-stayed plates. The distance between the upper and lower frame structures is 140±10mm. The height from the ground is 360±10mm, realizing one step. Both the upper frame structure and the lower frame structure are composed of small cross-section transverse members, small cross-section longitudinal members and small cross-section diagonal braces. In order to ensure that the stress can be well transmitted at each junction of the underframe members, the stress concentration is not obvious , so that the stress on each member is reasonable, and the maximum potential of the members is exerted. The diagonal braces of the upper frame structure and the diagonal braces of the lower frame structure are distributed in a cross pattern in the direction of the top view. As shown in Figure 6, the diagonal braces of the upper frame structure and the The specific layout of the diagonal braces of the lower frame structure is shown in the partial diagram in Figure 3. At the same time, in order to ensure that the body structure has good rigidity and good stress conduction, the intersection points of the upper frame structure and the lower frame structure of the transverse members and longitudinal members are aligned in the vertical direction, and small cross-section columns are arranged at the intersection points to connect the upper and lower layers frame. In this way, the upper and lower rods and small cross-section columns constitute a quadrilateral frame. The quadrilateral frame is unstable and has a weak bearing capacity, and the distance between the upper and lower layers of the chassis is too small. Welding operation, so the double-layer same-direction inclined-stayed plate is used instead of the diagonal brace. Compared with diagonal braces, inclined-stayed slabs can only bear tension but not compression. The present invention judges the direction of tension through pre-analyzed deformation contours under dangerous working conditions, so that all inclined-stayed slabs are reasonably arranged on opposite sides of the quadrilateral frame. In the direction of the elongation of the corner line.

The body rods are mainly subjected to vertical loads to produce bending deformation. In this way, the upper and lower surfaces of the beam are subjected to relatively large bending stress, which is a high-stress area, and the heat-affected zone of the weld will affect the mechanical properties of the material. In view of the above reasons, the design of the position and size of the weld should not only ensure the welding strength, but also keep the heat-affected zone of the weld away from the high-stress area of the welded beam, so as to improve the bearing capacity of the structure. The position and size of the weld seam are as follows: the distance between the horizontal weld on the upper part of the inclined-stayed plate and the upper surface of the welded rod is 4-8mm, and the distance between the lower end point of the oblique weld and the lower surface of the welded rod is 4-6mm; The distance between the horizontal weld at the lower part of the inclined-stayed plate and the lower surface of the welded bar is 4-8mm, and the distance between the upper end point of the oblique weld and the upper surface of the welded bar is 4-6mm; the minimum distance between the weld and the small column is 30 ~42mm.

Most of the transverse rods and longitudinal rods constituting the double-layer chassis adopt rectangular steel pipes with a cross-sectional size of 40-50 mm high, 40-50 mm wide and 2-4 mm thick; the small columns adopt a cross-sectional size of 30-40 mm long and wide 30-40mm, 1.5-2.5mm thick rectangular steel pipe; diagonal bracing adopts rectangular steel pipe with section size of 30-40mm long, 30-40mm wide, and 1.5-2.5mm thick; cable-stayed plate adopts 30-40mm wide, 2-2mm thick 4mm parallelogram sheet.

The vehicle body structure of the present invention is a low floor, passengers get on and off without steps, the plane on the floor is only 360mm away from the ground, the underframe is a double-layer truss structure and the distance between the upper and lower floors is 140mm, as shown in Figure 4 between the thickness of the bottom plate and the distance between the floor and the ground As shown in the schematic diagram. In order to ensure that the installation of the axle and the movement of components do not interfere, the floor near the rear axle is designed to have a slope of about 2°~3°. 215mm in front of the midpoint of the rear suspension, the downhill starts at a distance of 215mm behind the midpoint of the rear suspension, ends at a distance of 960mm behind the midpoint of the rear suspension, 215mm in front of the midpoint of the rear suspension, and ends at a distance of 215mm behind the midpoint of the rear suspension This section of the floor is flat, as shown in the partial enlarged view of the sloping floor in Figure 4.

Due to the thin chassis of low-floor buses and the small space, it is difficult to arrange large components such as motors, batteries, and controllers. Considering the floor space and load distribution comprehensively, in order to make the load distribution and axle load distribution of the whole vehicle more reasonable. The seat space can be used to arrange the vehicle controller, battery, motor controller, etc. in the middle of the car body, while the motor and transmission are arranged in the rear of the car body. For example, the battery is placed under the seat in the passenger compartment in the middle of the car body. In order to facilitate the layout of the low-floor body structure, a row of bosses with a length of about 2040mm, a width of about 756mm, and a height of about 550mm are longitudinally arranged on the left side of the rear suspension, and the motor and transmission are arranged in the floor space under the bosses. Seats can be installed on it, as shown in the partial enlarged view where the motor and transmission are arranged in Figure 4. In this way, the front and rear axle loads of the vehicle are balanced, and the carrying capacity of the middle section is fully utilized. At the same time, considering the large size and vibration of the motor and transmission, a row of raised seats is arranged longitudinally at the rear suspension to increase the floor space. The layout of the vehicle is as follows: Figure 8 shows.

The top cover, front wall and rear wall of the body structure can be flexibly designed according to specific conditions.

The body structure established based on the above method can effectively reduce the non-axial load of each member of the structure, make the force of the whole vehicle more reasonable, and the load distribution more uniform so as to maximize the potential of the structural components. Compared with similar models, the body The strength and rigidity of the vehicle have been effectively improved. Under the same conditions, the weight of the body structure can be reduced by more than 15%.

Because the distance between the upper and lower floors of the low-floor chassis is too small, the diagonal braces are not easy to arrange, and the manufacturability is not good, which is not convenient for welding operations, so double-layer cable-stayed plates are used to replace the diagonal braces. Compared with the diagonal brace, the inclined-stayed slab can only bear the tension but not the compression. The invention judges the direction of tension by loading the pre-analyzed deformation contour, so that the inclined-stayed slab is reasonably arranged in the tension direction of the structure. The obliquely-stayed plates (including transverse and longitudinal) between the upper and lower layers of the underframe adopt parallelogram thin plates, as shown in Figure 5, the lower transverse member I12, the upper transverse member I13, and the left surrounding column are known from the pre-loading analysis. Ⅰ14. The diagonal line M-N of the quadrilateral formed by the column of the chassis Ⅱ15 is under tension, so the inclined-stayed plate is arranged in the direction of the diagonal line M-N. Parallel, and 4-8mm away from A1; the other end b2-c2 of the diagonally-stayed plate is parallel to the upper surface A2 of the upper transverse member I13, and 4-8mm away from A2. The specific welding positions of the inclined-stayed slab and the beam to be welded are as follows: the end b1-c1 and the end b2-c2 are all welded, and the end point a1 of the side weld a1-b1 of the inclined-stayed slab adjacent to the end is at a distance from the lower transverse bar The upper surface B1 of piece I12 is 4-6 mm, and the distance between the end point d1 of the side weld c1-d1 and the upper surface B1 of the lower transverse member I12 is 4-6 mm, and the distance between the end point a2 of the side weld a2-b2 and the upper transverse bar The lower surface B2 of the member I13 is 4-6 mm, and the distance between the end point d2 of the side weld c2-d2 and the lower surface B2 of the upper transverse member I13 is 4-6 mm. The end point c1 of the cable-stayed plate is 30-42 mm from the left side column I14, and the distance b2 from the end point b2 of the cable-stayed plate is 30-42 mm from the column II15 of the chassis.

The layout of the transverse slanted plates of the chassis is roughly the same, and one of the cross-sections is taken as an example to illustrate, as shown in Fig. Supported by the column III16, the transverse inclined-stayed plate I11 and the transverse inclined-stayed plate II17 are arranged on the outside of the base frame column II15 and the base frame column III16, and no inclined-stayed plate is arranged between the base frame column II15 and the base frame column III16, and the transverse inclined-stayed plate Ⅰ11 and transverse slanted plate Ⅱ17 connect the lower transverse member Ⅰ12 and the upper transverse member Ⅰ13; the longitudinal direction of the chassis is the arrangement of the slanted plate between the upper and lower longitudinal members of the underframe in the middle section of the vehicle body, as shown in Figure 7, the longitudinal slant The tension plate II18, the longitudinal oblique tension plate III19, and the longitudinal oblique tension plate IV20 are substantially parallel to each other; The inclined-stayed plate III19, the longitudinal inclined-stayed plate IV20 and the longitudinal inclined-stayed plate V21, the longitudinal inclined-stayed plate VI22, and the longitudinal inclined-stayed plate VII23 are generally symmetrical about the column II15 of the chassis, and the distribution at A on the other side is the same.

The body manufacturing adopts the full-load manufacturing process, that is, the overall assembly of the body structure skeleton is completed first, and then the suspension, motor and other components are installed. It can not only ensure that the performance and stress of the actual structure are consistent with the design analysis conditions, but also facilitate the overall anti-corrosion treatment of the body frame.

The applicant has designed a 12-meter low-floor load-bearing pure electric bus according to the present invention. The CAE analysis results of the body structure performance are as follows:

Body bending stiffness: K=9.33×10 ⁶ N/m

The reference value of similar models: (5.99～10.41)×10 ⁶ N/m

The torsional rigidity of the body is: K=6.44×10 ⁴ N·M/deg

The reference value of similar models: (2.93～4.12)×10 ⁴ N·M/deg

The first-order bending vibration modal frequency of the car body is: 12.79HZ

The reference value of similar models: 8.2～14.1HZ

The first-order torsional vibration mode frequency of the car body is: 6.14HZ

The reference value of similar models: 5.8～9.1HZ

The maximum stress of the body under full-load bending conditions is: 287MPa

Material (16Mn) yield limit: 345MPa

The maximum stress of the left wheel suspension condition of the body is: 319MPa

Material (16Mn) yield limit: 345MPa

The maximum stress of the suspension condition of the right wheel of the body is: 307MPa

Material (16Mn) yield limit: 345MPa

The above analysis results show that the car's performance indicators are between or better than similar models, and the weight of the body structure is about 15% lighter than similar models.

Claims (4)

1. the pure electronic urban bus body structure of low floor full-bearing type is by preceding, back wall, top cover, a left side, enclose on the right side and branch unit such as underframe is formed, wherein underframe is again by front overhang, rear overhang and underframe stage casing three parts constitute, the space truss structure that its each branch unit all is made up of the small bore rod member, this body structure opens passenger door preceding, rear overhang, body center portion is complete framed structure, it is characterized in that: body center portion is by last story frame structure, following story frame structure and some connect their column and the double-deck truss structure of an integrated carrying-type of oblique arm-tie composition, the spacing of levels framed structure is 140 ± 10mm, the floor terrain clearance is 360 ± 10mm, has realized that one-level marks time; Its at the middle and upper levels framed structure and following story frame structure transverse bar member and vertically the intersection point of rod member align in vertical direction, the small bore column is arranged in the intersection point place and connects the levels framework, levels rod member and column have constituted quadrilateral frame like this, tiltedly arm-tie is arranged on the diagonal line of quadrilateral frame, and the direction of layout is the direction along quadrilateral frame diagonal line elongation when the dangerous operating mode; Upper and lower story frame structure all is made up of small bore transverse bar member, the vertical rod member of small bore and small bore diagonal brace.

2. the pure electronic urban bus body structure of a kind of low floor full-bearing type according to claim 1 is characterized in that: the most of employing of underframe transverse bar member and vertical rod member sectional dimension is the rectangular steel pipe of high 40～50mm, wide 40～50mm, thick 2～4mm; The column in underframe stage casing and diagonal brace adopt the rectangular steel pipe of sectional dimension for long 30～40mm, wide 30～40mm, thick 1.5～2.5mm; Oblique arm-tie in the underframe adopts the parallelogram thin plate of wide 30～40mm, thick 2～4mm.

3. the pure electronic urban bus body structure of a kind of low floor full-bearing type according to claim 1, it is characterized in that: the horizontal weld on the oblique arm-tie top of being adopted and the upper surface of soldered rod member are at a distance of 4～8mm, and the lower extreme point of inclined weld and the lower surface of soldered rod member are at a distance of 4～6mm; Tiltedly the lower surface of the horizontal weld of arm-tie bottom and soldered rod member is at a distance of 4～8mm, and the upper extreme point of inclined weld and the upper surface of soldered rod member are at a distance of 4～6mm; The minimum spacing of weld seam and post is 30～42mm.

4. the pure electronic urban bus body structure of a kind of low floor full-bearing type according to claim 1, it is characterized in that: the local hillside fields plate that adopts in the back axle place of described double-deck truss-like Undercarriage structure, the gradient is approximately 2 °～3 °, this hillside fields plate goes up a slope and originates in apart from 2460mm place, rear overhang mid point the place ahead, end at apart from 215mm place, rear overhang mid point the place ahead, descending originates in apart from 215mm place, rear overhang mid point rear, ending at apart from 960mm place, rear overhang mid point rear, is flat apart from 215mm place, rear overhang mid point the place ahead to this section floor apart from 215mm place, rear overhang mid point rear.

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