Rear door hinge structure design scheme_hinge knowledge

1

The wide-body light passenger project is a project that is driven by data and fully designed with a forward-thinking approach. Throughout the project, the digital model seamlessly connects the shape and structure, capitalizing on the benefits of accurate digital data, quick modifications, and seamless integration with structural design. It incorporates and interacts with the modeling design and progressively introduces structural feasibility analysis in stages, ultimately achieving the goal of structural feasibility and satisfactory modeling. The final result is directly released in the form of data. It is evident that the inspection of the appearance Checklist at each stage is of utmost importance. This article aims to delve into the details of the rear door hinge open check process.

2 Rear door hinge axis arrangement

The hinge axis layout and hinge structure determination are the focal points of the motion analysis of the rear door opening. According to the vehicle definition, the rear door needs to open 270 degrees. Considering the shape requirements, the outer surface of the hinge must align with the CAS surface, and the inclination angle of the hinge axis should not be too large.

The steps for analyzing the hinge axis layout are as follows:

a. Determine the Z-direction position of the lower hinge (refer to Figure 1). This decision primarily considers the space required for the arrangement of the reinforcement plate of the lower hinge of the rear door. This space needs to account for two factors: the size needed for ensuring strength and the size required for the welding process (mainly the welding tongs channel space) and the final assembly process (assembly space).

b. Position the main section of the hinge at the determined Z-direction position of the lower hinge. When positioning the section, the hinge installation process should be initially taken into consideration. Determine the positions of the four links through the main section, and parameterize the lengths of the four links (refer to Figure 2).

c. Based on the four determined axes in step 2, establish the four axes with reference to the benchmark car's hinge axis inclination angle. Use the conic intersection method to parameterize the values of the axis inclination and forward inclination (refer to Figure 3). Both the axis inclination and inclination must be independently parameterized for fine-tuning in subsequent steps.

d. Determine the position of the upper hinge by referencing the distance between the upper and lower hinges of the benchmark car. The distance between the upper and lower hinges must be parameterized, and the normal planes of the hinge axes are established at the positions of the upper and lower hinges (refer to Figure 4).

e. Meticulously arrange the main sections of the upper and lower hinges on the determined normal plane of the upper and lower hinges (refer to Figure 5). During the layout process, the inclination angle of the axis can be adjusted to ensure the outer surface of the upper hinge is flush with the CAS surface. Detailed consideration must also be given to the hinge's installation manufacturability, fit clearance, and structural space of the four-bar linkage mechanism (it is unnecessary to design the hinge structure in detail at this stage).

f. Conduct DMU movement analysis using the four determined axes to analyze the movement of the back door and verify the safety distance after opening. The safety distance curve during the opening process is generated through the DMU module of GATIA (refer to Figure 6). This safety distance curve determines whether the minimum safety distance during the rear door opening process meets the defined requirements.

g. Perform parametric adjustments by tuning the three sets of parameters: hinge axis inclination angle, forward inclination angle, connecting rod length, and distance between the upper and lower hinges (the parameter adjustments must be within a reasonable range). Analyze the feasibility of the rear door opening process (including safety distance during the opening process and at the limit position). If the rear door cannot open properly even after adjusting the three parameter groups, the CAS surface needs to be modified.

The hinge axis layout requires multiple rounds of iterative adjustments and checks to fully meet the requirements. It must be emphasized that the hinge axis is directly related to all subsequent layout processes. Once the axis is adjusted, the subsequent layout must be comprehensively readjusted. Therefore, the axis layout must undergo thorough analysis and precise layout calibration. After finalizing the hinge axis, the detailed hinge structure design phase begins.

3 Rear door hinge design options

The rear door hinge employs a four-bar linkage mechanism. Due to the significant adjustments in shape compared to the benchmark car, the hinge structure requires relatively large modifications. It is challenging to implement the recessed structure design when considering several factors. Therefore, three design options for the hinge structure are proposed.

3.1 Option 1

Design idea: Ensure that the upper and lower hinges align as closely as possible with the CAS surface and that the hinge side matches the part line. Hinge axis: Inward tilt of 1.55 degrees and forward tilt of 1.1 degrees (refer to Figure 7).

Appearance disadvantages: To ensure a safe distance between the door and the side wall during the door opening process, there is a significant difference between the hinge's matching position and the door's position when closed.

Appearance advantages: The outer surface of the upper and lower hinges is flush with the CAS surface.

Structural risks:

a. The inward tilt of the hinge axis (24 degrees inward and 9 degrees forward) is significantly adjusted compared to the benchmark car, and it may affect the effectiveness of automatic door closure.

b. To ensure a safe distance between the fully open rear door and the side wall, the inner and outer connecting rods of the hinge need to be 20nm longer than the benchmark car, which may cause the door to sag due to insufficient hinge strength.

c. The side wall of the upper hinge is divided into blocks, making welding difficult and posing a risk of water leakage in the later stages.

d. Poor hinge installation process.

3.2 Option 2

Design idea: Both the upper and lower hinges protrude outwards to ensure no gap between the hinges and the rear door in the X direction. Hinge axis: 20 degrees inward and 1.5 degrees forward (refer to Figure 8).

Appearance disadvantages: The upper and lower hinges protrude more outwardly.

Appearance advantages: No fit gap between the hinge and the door in the X direction.

Structural risk: To ensure commonality between the upper and lower hinges, the size of the lower hinge is slightly adjusted compared to the benchmark car sample, but the risk is minimal.

Structural advantages:

a. All four hinges are common, resulting in cost savings.

b. Good door linkage assembly process.

3.3 Option 3

Design idea: Match the outer surface of the upper and lower hinges with the CAS surface and match the door linkage with the door. Hinge axis: 1.0 degrees inward and 1.3 degrees forward (refer to Figure 9).

Appearance advantages: The outer surface of the hinge fits better with the outer surface of the CAS surface.

Appearance disadvantages: There is a significant gap between the hinged door linkage and the outer linkage.

Structural risks:

a. The hinge structure undergoes significant adjustments, posing a greater risk.

b. Poor hinge installation process.

3.4 Comparative analysis and confirmation of options

The three hinge structure design options and a comparative analysis with the benchmark vehicles are summarized in Table 1. After discussions with the modeling engineer and considering structural and modeling factors, it is confirmed that the "third option" is the optimal solution.

4 Summary

The design of the hinge structure necessitates the comprehensive consideration of factors such as structure and shape, often making it challenging to optimize all aspects. As the project predominantly adopts a forward design approach, during the CAS design stage, meeting structural requirements while maximizing the appearance modeling effect is of utmost importance. The third option strives to minimize changes to the outer surface, ensuring modeling consistency. Therefore, the modeling designer leans towards this option. The quality of AOSITE Hardware's Metal Drawer System is highly affirmed, demonstrating the effectiveness of their management system.