A method for calculating the dimension chain of a fuel pipe

Abstract

The present invention discloses a method for calculating the dimension chain of a fuel pipe, which includes obtaining the dimension design parameters at the fuel pipe opening of the vehicle to be measured, and establishing a three-dimensional coordinate system XYZ; finding out all the dimensional tolerances that affect the deviation of the fuel pipe opening, which are equivalent to the motion trajectories of points, making the motion trajectories of each point in the CATIA software, and then projecting the motion trajectories onto the XYZ coordinate system, obtaining the sum of the squares of the projected lengths of each tolerance on the center point of the fuel pipe opening in the XYZ directions, and then performing a root-mean-square calculation to obtain the deviation of the center point of the fuel pipe opening in the XYZ directions; then dividing the sum of the squares of the projected lengths of each tolerance on the center point of the fuel pipe opening in the XYZ directions by the total sum of the squares to obtain the proportion of each tolerance to the center deviation of the fuel pipe opening, thereby guiding the dimension design at the fuel pipe opening of the vehicle to be measured, so as to facilitate the control of the deviation of the fuel pipe by researchers during the design and manufacturing processes.

Description

Technical Field

[0001] The present invention relates to the technical field of the size chain calculation of automobile fuel pipes. Specifically, a method for calculating the size chain of a fuel pipe is disclosed. Background Art

[0002] In the existing automobile market, customers have higher and higher requirements for the appearance of automobiles. For many vehicle models, an interference fit between the fuel pipe and rubber is used to waterproof the fuel filler opening. However, in this structure, since the fuel pipe itself has no limit, the assembly error is large and it is easy to be eccentric. The fit between the fuel pipe and the rubber of the fuel filler box only relies on the interference amount of the rubber itself to prevent water, and there is a possibility of clearance fit. This fit structure is prone to problems such as deviation gaps at the fuel filler opening, thus causing appearance and water leakage problems. To solve these problems, the calculation of the size chain of the fuel pipe assembly and the body fit is particularly important. Summary of the Invention

[0003] The purpose of the present invention is to overcome the defects of the prior art and propose a method for calculating the size chain of a fuel pipe, which is applicable to the structure with rubber fit at the fuel filler opening. By establishing a three-dimensional coordinate system XYZ in space and using the graphical method to find the deviation under the coordinates corresponding to each tolerance, the deviation in the XYZ directions is finally solved by using the root mean square.

[0004] To achieve the above purpose, the present invention provides the following technical solutions:

[0005] A method for calculating the size chain of a fuel pipe includes the following steps:

[0006] Step S1. Obtain the size design parameters at the fuel filler opening of the vehicle model to be measured, and establish an analysis model in the CATIA software. Taking the center point of the fuel filler opening as the origin, establish a three-dimensional coordinate system XYZ;

[0007] Step S2. Find all the dimensional tolerances that affect the deviation of the fuel filler opening;

[0008] Step S3. Equivalent all the dimensional tolerances found in Step S2 that affect the deviation of the fuel filler opening to the movement trajectories of points, make the movement trajectories of each point in the CATIA software, and then project the movement trajectories onto the XYZ coordinate system to obtain the projection lengths of each tolerance on the center point of the fuel filler opening in the XYZ directions;

[0009] Step S4. Calculate the sum of squares of the projection lengths of each tolerance on the center point of the fuel filler opening in the XYZ directions in Step S3 respectively, and then perform root mean square calculation to obtain the deviation of the center point of the fuel filler opening in the XYZ directions;

[0010] Step S5. Calculate the square sum of the projected lengths of each tolerance pair on the center point of the fuel filling pipe orifice in the X, Y, and Z directions, divide it by the total square sum, and obtain the proportion of the center deviation of each tolerance pair of the fuel filling pipe orifice, and accordingly guide the dimension design at the fuel filling pipe orifice of the vehicle to be measured.

[0011] Specifically, all the dimensional tolerances affecting the deviation of the fuel filling pipe orifice described in step S2 include the positional tolerance of the body sheet metal bracket hole, the positional tolerance of the body, the positional tolerance of the fuel filling pipe bracket hole, the profile tolerance of the fuel filling pipe orifice, the positional tolerance of the fuel filling port sheet metal, the design clearance tolerance of the hole and the bolt, and the design tolerance of the bracket hole.

[0012] Specifically, the specific process of step S3 is as follows:

[0013] Take the center point of the position where the component affecting the deviation of the fuel filling pipe orifice is located as the center of a circle, project the circle onto the XOY plane, and an ellipse can be obtained after projection. Further, make tangents perpendicular to the X-axis and the Y-axis on the XOY plane for the ellipse respectively. The distances of the tangents perpendicular to the X-axis and the Y-axis are the influences of the component on the fuel filling pipe orifice in the X and Y directions. Further, project the circle onto the XOZ plane to obtain the tangent distance from the circle to the Z-axis. Record the tangent distances to the X-axis, Y-axis, and Z-axis obtained through the two projections respectively to obtain the projected lengths of the component tolerance on the center point of the fuel filling pipe orifice in the X, Y, and Z directions.

[0014] Specifically, the calculation formula of step S4 is as follows:

[0015] The deviation of the center point O of the fuel filling pipe orifice in the X, Y, and Z directions:

[0016]

[0017] In the above formula, A, B, and C respectively represent three different positions. A is the fuel filling pipe orifice, B is the first fuel filling pipe bracket hole, and C is the second fuel filling pipe bracket hole; n represents the n dimensional tolerances at this position; X An 、Y An 、Z An 、X Bn 、Y Bn 、Z Bn 、X Cn 、Y Cn 、Z Cn respectively represent the projected lengths of the three positions A, B, and C on the center point O of the fuel filling pipe orifice.

[0018] Specifically, the calculation formula for the proportion of the center deviation of each tolerance pair of the fuel filling pipe orifice described in step S5 is: the proportion of the a-th dimensional tolerance to the center of the fuel filling pipe orifice in

[0019] In the above formula, A, B, and C respectively represent three different positions. A is the fuel filling pipe nozzle, B is the first fuel filling pipe support hole, and C is the second fuel filling pipe support hole; n represents the nth dimensional tolerance at this position; a represents the ath dimensional tolerance among the n dimensional tolerances; X Aa , X Ba , X Ca or X An , X Bn , X Cn respectively represent the projected lengths of the ath or nth dimensional tolerance at the three positions of A, B, and C on the X-axis with respect to the center point of the fuel filling pipe nozzle.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0021] 1) By calculating the dimensional chain, the assembly error problem of the fuel filling pipe is improved;

[0022] 2) Through the proportion of each tolerance obtained by calculation, it is convenient for researchers to control the deviation of the fuel filling pipe during the design and manufacturing process;

[0023] 3) A new method for calculating the spatial dimensional chain is provided;

[0024] 4) It can be extended to other assembly dimensional chain calculation schemes. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 is a flowchart of a method for calculating the dimensional chain of a fuel filling pipe according to the present invention;

[0026] Figure 2 is an assembly drawing of the fuel filling pipe nozzle and its support holes in an embodiment of the present invention;

[0027] Figure 3 is a schematic structural diagram of the fuel filling pipe nozzle and its support holes in an embodiment of the present invention;

[0028] Figure 4 is an assembly drawing of two vehicle body fixing support holes in an embodiment of the present invention;

[0029] Figure 5 is Figure 2 a partial enlarged schematic view at A;

[0030] In the figure, A is the fuel filling pipe nozzle; B is the first fuel filling pipe support hole; C is the second fuel filling pipe support hole; D is the first vehicle body fixing support hole; E is the second vehicle body fixing support hole. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0031] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Apparently, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0032] Embodiment: Refer to Figures 1 - 5 .

[0033] As Figure 1 shown, the present invention discloses a method for calculating the dimension chain of a fuel pipe, which includes the following steps:

[0034] Step S1. Obtain the dimension design parameters at the fuel pipe orifice of the vehicle to be tested, and establish an analysis model in the CATIA software. As Figure 5 shown, taking the center point of the fuel pipe orifice as the origin, establish a three-dimensional coordinate system XYZ;

[0035] Step S2. Find out all the dimensional tolerances that affect the deviation of the fuel pipe orifice;

[0036] Step S3. Equivalent all the dimensional tolerances found in Step S2 that affect the deviation of the fuel pipe orifice to the movement trajectories of points, make the movement trajectories of each point in the CATIA software, and then project the movement trajectories onto the XYZ coordinate system to obtain the projected lengths of each tolerance in the XYZ directions of the center point of the fuel pipe orifice;

[0037] Step S4. Respectively calculate the sum of squares of the projected lengths of each tolerance in the XYZ directions of the center point of the fuel pipe orifice in Step S3, and then perform root mean square calculation to obtain the deviation of the center point of the fuel pipe orifice in the XYZ directions;

[0038] Step S5. Divide the sum of squares respectively obtained for the projected lengths of each tolerance in the XYZ directions of the center point of the fuel pipe orifice by the total sum of squares to obtain the proportion of each tolerance to the center deviation of the fuel pipe orifice, and accordingly guide the dimension design at the fuel pipe orifice of the vehicle to be tested.

[0039] Specifically, as Figures 2 - 4 shown, the method for finding the dimensional tolerances that affect the deviation of the fuel pipe orifice is as follows:

[0040] The deviation of the center of the fuel filler neck relative to the vehicle body is the closed loop to be solved. The center position of the fuel filler neck is affected by these dimensions (the positional tolerance of the first fuel pipe support hole B, the positional tolerance of the second fuel pipe support hole C, the positional tolerance of the first vehicle body fixing support hole D, the positional tolerance of the second vehicle body fixing support hole D, the profile tolerance of the vehicle body itself, the clearance between the design clearance hole and the bolt, the flatness tolerance of the vehicle body support, the positional tolerance of the vehicle body fuel filler neck). The tolerance of position A to be solved is the closed loop. The method for judging other increasing and decreasing loops is to first list all possible influencing dimensional tolerances. It can be assumed that other dimensions have zero tolerance first, and only this dimension is changed to determine whether this dimension has an impact on the position of A of the fuel pipe. All related dimensions are judged one by one according to this method. Since the method of the present invention uses the root mean square method, it is not necessary to judge whether the tolerance is an increasing loop or a decreasing loop.

[0041] Specifically, all dimensional tolerances affecting the deviation of the fuel filler neck include the positional tolerance of the vehicle body sheet metal support hole, the positional tolerance of the vehicle body, the positional tolerance of the fuel pipe support hole, the profile tolerance of the fuel filler neck, the positional tolerance of the fuel filler neck sheet metal, the design clearance tolerance of the hole and the bolt, and the design tolerance of the support hole.

[0042] Specifically, the specific process of step S3 is as follows:

[0043] A circle is drawn with the center point of the position where the component affecting the deviation of the fuel filler neck is located as the center, and then the circle is projected onto the XOY plane. After projection, an ellipse can be obtained. Further, tangents perpendicular to the X-axis and the Y-axis are made to the ellipse on the XOY plane respectively. The distances of the tangents perpendicular to the X-axis and the Y-axis are the influences of the component on the fuel filler neck in the X and Y directions. Further, the circle is projected onto the XOZ plane to obtain the tangent distance from the Z-axis. The tangent distances to the X-axis, Y-axis, and Z-axis obtained through the two projections are recorded respectively to obtain the projection lengths of the component tolerance on the center point of the fuel filler neck in the XYZ directions.

[0044] Specifically, the calculation formula of step S4 is as follows:

[0045] The deviation of the center point O of the fuel filler neck in the XYZ directions:

[0046]

[0047] In the above formula, A, B, and C respectively represent three different positions. A is the fuel filler neck, B is the first fuel pipe support hole, and C is the second fuel pipe support hole; n represents the n dimensional tolerances at this position; X An 、Y An 、Z An 、X Bn 、Y Bn 、Z Bn 、XCn , Y Cn , Z Cn respectively represent the projected lengths of the center points of the refueling nozzle at three positions A, B, and C with respect to point O.

[0048] Specifically, the calculation formula for the proportion of each tolerance in the center deviation of the refueling nozzle in step S5 is as follows: The proportion of the a-th dimensional tolerance in the center of the refueling nozzle in

[0049] In the above formula, A, B, and C respectively represent three different positions. A is the refueling nozzle, B is the first refueling pipe support hole, and C is the second refueling pipe support hole; n represents the n-th dimensional tolerance at this position; a represents the a-th dimensional tolerance among the n dimensional tolerances; X Aa , X Ba , X Ca or X An , X Bn , X Cn respectively represent the projected lengths of the a-th or n-th dimensional tolerance at positions A, B, and C on the X-axis with respect to the center point of the refueling nozzle.

[0050] As described above, it is only a preferred embodiment of the present invention, and does not impose any formal restrictions on the structure of the present invention. Any simple modification, equivalent change, and modification made to the above embodiments based on the technical essence of the present invention all fall within the scope of the technical solution of the present invention.

Claims

1. A method for calculating the dimensional chain of a fuel pipe, characterized in that, Including the following steps: Step S1. Obtain the dimensional design parameters at the fuel filling nozzle of the vehicle model to be tested, and establish an analysis model in the CATIA software. Taking the center point of the fuel filling nozzle as the origin, establish a three-dimensional coordinate system XYZ; Step S2. Identify all the dimensional tolerances that affect the deviation of the fuel filling nozzle; All the dimensional tolerances that affect the deviation of the fuel filling nozzle include the positional tolerance of the body sheet metal bracket holes, the positional tolerance of the body, the positional tolerance of the fuel pipe bracket holes, the profile tolerance of the fuel filling nozzle, the positional tolerance of the fuel filling port sheet metal, the design clearance tolerance of the holes and bolts, and the design tolerance of the bracket holes; Step S3. Equivalent all the dimensional tolerances identified in Step S2 that affect the deviation of the fuel filling nozzle to the movement trajectories of points. Make the movement trajectories of each point in the CATIA software, and then project the movement trajectories onto the XYZ coordinate system to obtain the projected lengths of each tolerance on the center point of the fuel filling nozzle in the XYZ directions; Step S4. Calculate the sum of squares of the projected lengths of each tolerance on the center point of the fuel filling nozzle in the XYZ directions respectively, and then perform a root mean square calculation to obtain the deviation of the center point of the fuel filling nozzle in the XYZ directions; Step S5. Divide the sum of squares of the projected lengths of each tolerance on the center point of the fuel filling nozzle in the XYZ directions respectively by the total sum of squares to obtain the proportion of each tolerance to the center deviation of the fuel filling nozzle, and accordingly guide the dimensional design at the fuel filling nozzle of the vehicle model to be tested.

2. The dimension chain calculation method of a fuel pipe according to claim 1, characterized in that The specific process of Step S3 is as follows: Draw a circle with the center point of the position where the component that affects the deviation of the fuel filling nozzle is located as the center, and then project the circle onto the XOY plane. After projection, an ellipse can be obtained. Further, make tangents perpendicular to the X-axis and Y-axis on the XOY plane for the ellipse. The distances of the tangents perpendicular to the X-axis and Y-axis are the influences of the component on the fuel filling nozzle in the X and Y directions. Further, project the circle onto the XOZ plane to obtain the tangent distance from the Z-axis. Record the tangent distances to the X-axis, Y-axis, and Z-axis obtained through the two projections respectively to obtain the projected lengths of the component tolerance on the center point of the fuel filling nozzle in the XYZ directions.

3. A calculation method for the dimensional chain of a fuel pipe according to claim 1, characterized in that, The calculation formula of Step S4 is as follows: Deviation of the center point O of the fuel filling nozzle in the XYZ directions: In the above formula, A, B, and C respectively represent three different positions. A is the fuel filling pipe orifice, B is the first fuel filling pipe support hole, and C is the second fuel filling pipe support hole; n represents the n dimensional tolerances at this position; X An , Y An , Z An , X Bn , Y Bn , Z Bn , X Cn , Y Cn , Z Cn respectively represent the projected lengths of the three positions A, B, and C on the center point O of the fuel filling pipe orifice.

4. A method for calculating the dimension chain of a fuel pipe according to claim 1, characterized in that, The calculation formula for the proportion of each tolerance to the center deviation of the fuel filling nozzle described in Step S5 is: In the above formula, A, B, and C respectively represent three different positions. A is the fuel filling nozzle opening, B is the first fuel filling pipe support hole, and C is the second fuel filling pipe support hole; n represents the nth dimensional tolerance at this position; a represents the ath dimensional tolerance among the n dimensional tolerances; X Aa , X Ba , X Ca or X An , X Bn , X Cn respectively represent the projected lengths of the ath or nth dimensional tolerance at the three positions of A, B, and C on the center point of the fuel filling nozzle opening on the X-axis.

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