Secondary Development of Blades Parametric Design of Hydraulic Torque Converter Based on CATIA Peng Guan/Junchao Dong/Liguang Wu State Key Laboratory of Automobile Dynamic Simulation, Jilin University ADSL, JLU Changchun, China E-mail:
[email protected]/
[email protected] [email protected]
Abstract—Using VB 6.0 and CATIA software, this paper illustrates a method to generate the parameters and three dimensional shapes of the hydraulic torque converter blade automatically, in order to cut the development cycle. Finally, as an example of this methodology, a particular parametric design of a hydraulic torque converter blade is presented to verify the validity of the method by establishing a VB 6.0 program, which can generate the blade parameters and the three dimensional shape of the specific hydraulic torque converter blade. Keywords-CATIA; secondary development; computer aided design; hydraulic torque converter blade
I. INTRODUCTION Hydraulic torque converter, a kind of hydraulic, mechanical coupling complex turbomachinery, is a key component of a vehicle power train system. Its main function is to transfer the power from engine to drive system smoothly. A vehicle with a hydraulic torque converter, whose quality can influence the durability of a vehicle, can start and accelerate smoothly. And the shape of blades determines the performance of hydraulic torque converter directly. This is due to a high speed hydraulic torque converter with thin, excessive forward-swept or back-swept blades will generate centrifugal force and uniform flow field, which will cause the change of blades’ lift and be prone to resonance. Meanwhile, the blades can be fatigue broken down early by the fluid-structure interaction. So a well design of blades is quite important to a hydraulic torque converter. Blades are determined by these parameters, such as the shape of the flow path of impeller axial plane, the inlet and outlet blade angle of intermediate flow lines and the number of blades. In order to cut the development cycle and save costs, one problem-how to generate the three dimensional shape of blades automatically-needs to be solved. This is because that the shape of blades of a hydraulic torque converter could be modified frequently during the design cycle. This paper provides a feasible solution to the problem mentioned above. This paper illustrates a method of parametric design of hydraulic torque converter blades using VB 6.0 and CATIA software. CATIA software has many advantages, such as firstly, it is widely used in automotive industry, three dimensional models generated by CATIA can be adopted
directly by all departments. Secondly, it has a quite powerful surface generation function, which can avoid the repeated programming tasks. Generally, there are two methods of blade design, one is curved right triangle method, the other is circulation design method. The former one is based on drawing by hands, which is determined by experiences, and it is quite time consuming. The latter one is suitable for computer aided design, for this reason, this paper uses this method to design blades of hydraulic torque converter. This paper introduces the general steps of secondary development based on CATIA, in the environment of VB 6.0 software. Then a parametric design of blades of hydraulic torque converter is discussed. Finally, a specific example is presented to verify the feasibility of the method. II.
SECONDARY DEVELOPMENT BASED ON CATIA AND VB 6.0 There are two methods to achieve the secondary development using CATIA, the first one is the so-called CAA technology, which is more complicated and does not fit to automatic drawing. The second one is CATIA Automation, which is based on the OLE (object linking and embedding) of COM (component object model). It is relatively simple and it not only can save time by discarding the initialization and data type conversion, but also is suitable for automatic drawing. Obtain Application Object
Obtain Documents Object Document Object
Obtain Bodies Entity Set
Add()
Add Body Object
Obtain Part Object
Obtain ShapeFactor
Obtain OriginElements Object
Obtain Models
Figure 1. Steps of Manipulating the PartDocument
TB represents the torque of the impeller, represents the fluid density, Q represents quantity of flow, vuB1 , vuB 2 represents the tangential velocity at inlet and outlet of a blade respectively, rB1 , rB 2 represents the radius In (1)
at inlet and outlet of a blade respectively.
Figure 2. Points of Division for Flow Line of Impeller on Axial Plane
The secondary development using CATIA Automation discussed in this paper is based on Visual Basic integrated development environment, which provides a good interactive user interface. And also the codes of VBScript can be achieved by recording macros in CATIA environment. So the development cycle can be shorten due to these script codes achieve in CATIA can be used in VB after modifying them slightly. General steps of secondary development in VB and CATIA environment can be defined as, firstly, connect the COM interface of CATIA using GetObject or CreateObject. Secondly, open or create an Application Object. Thirdly, establish the data management by adding Document Object to Application Object, Fig. 1 shows detail steps of manipulating the PartDocument. And then the reference plane and point of views should be set before drawing geometric shapes. Next, Document Object and Viewer Object should be updated in order to show the geometric shapes clearly. Finally, close the Application Object, release COM resources. III.
PARAMETRIC DESIGN OF HYDRAULIC TORQUE CONVERTER BLADES The theoretical basis of circulation design theory, whose advantages have been discussed before, is beam theory. In other words, in condition of a specific design speed ratio, if the intermediate flow line of circulation circle adds some arc length, the liquid flow will increase the same value moment of momentum correspondingly in order to ensure the good flow condition in the flow channel. In this section, this paper illustrates the detail steps of circulation design. A. Divide the Circulation Circle Divide the intermediate flow lines of circulation circle plane into equal parts, and then passing the points of division draw perpendicular lines of the design construction lines, which are presented in Fig. 2. B. Radial Velocity Calculation The changes of moment of momentum at inlet and outlet of the impeller can be achieved by using Equation (1). And then the radial velocity can be obtained too.
TB Q(vuB2 rB 2 vuB1rB1 )
C. Calculate Angles of Corresponding Equal Division Points The angles of corresponding equal division points on the intermediate flow lines can be achieved by using Equation (2) and Equation (3).
vu ds 2 r vu vu u vm ctg
D. Determine the blade angle on the Internal and external circulation line The blade angle on the Internal and external circulation line can be determined by using anti-potential flow theory, Equation (4).
ctg c ctg ctg s rc r rs In (4) c represents the blade angle at the point of intersection between internal circulation line and the construction line, represents the blade angle at the point of intersection between design flow line and the construction line, s represents the blade angle at the point of intersection between external circulation line and the construction line, rc represents the radius at the point of intersection between internal circulation line and the construction line, r represents the radius at the point of intersection between design flow line and the construction line, and rs represents the radius at the point of intersection between external circulation line and the construction line. E. Determine the Shape of the Blade According to the internal radius, external radius and the offset, the shape of the blade can be achieved by using Equation (5). k
xk rk sin( y i 0
Ji ) ri
Figure 3. The Program of Blade Design
J i e cot
Figure 4.
In (5) J i can be presented in Equation (6), rk represents the radius at the point of intersection between design flow line and the construction line, y represents the angle between the axial plane where the starting point of the construction line locates on and the radial reference plane, xk represents the offset. In (6) e represents the arc length between two adjacent points on the design flow line. Computer aided calculation is needed for that the calculation workload of the blade design, as this paper mentioned above, is quite huge. The parameters can be calculated by using VB software according to the number of blades, the inlet angle, the outlet angle and the design speed. And then two dimensional pictures can be drawn by using MATLAB software. Fig. 3 presents the program of hydraulic torque converter blade design. IV.
DESIGN OF A SPECIFIC HYDRAULIC TORQUE CONVERTER In this section, this paper demonstrates a specific hydraulic torque converter blades design, W305, based on secondary development using CATIA.
Results of the Program of Hydraulic Torque Converter Blade Design
B. Macro Recording If the CATIA software is open, close all the active CATIA documents, if not, open the CATIA. And then active the dialog box of macro recording by selecting the commands in orderly: “Tools-Macro-Start Recording”. Before recording a macro directory, in which the macros will be stored, needs to be defined. Recording will be started by pressing “Start”, stopped by pressing “Stop Recording”. The macro of blades can be achieved by starting recording before establishing the model and stopping recording after finishing the model. C. Establish the Blade Model Establish the blade model and the corresponding flow field in CATIA software by using the coordinates points of construction line on internal and external circulation circle achieved before. Fig. 5 presents the corresponding points in CATIA. The splines of the blade can be achieved according to these coordinates points, the following figure (Fig. 6) presents the splines.
A. Design Parameters Calculation Using VB 6.0 The following table (TABLE Ⅰ ) shows the design parameters of W305 hydraulic torque converter. The parameters can be achieved after entering the parameters in TABLE Ⅰ as inputs of the computing program presented in Fig. 3. And then press “Compute”, the following figure (Fig.4) presents the results. TABLE I.
DESIGN PARAMETER OF W305
Design Speed r/min
Number of Vans
Inlet Angle (º)
Outlet Angle (º)
2000
21
133
95
Figure 5. Coordinates of Flow Line Points
Figure 6. Splines of the Blade
The surface of the impeller and the entity model can be generated by dealing with the splins, presented in Fig. 7. The flow field entity model, presented in Fig. 8, can be achieved by rotating the working surface of the impeller along the rotation direction for (2 360 / Z B ) , the nonworking surface along the opposite direction for (2 360 / Z B ) .
Figure 7. Entity Model of the Blade
Figure 8. Flow Field Model in the Impeller
D. Parametric Design Using VB 6.0 The VB program, presented in Fig. 3, can be composed by using the recorded macro. The parametric design of the blade three dimensional model can be established using the coordinates of the points on the flow line. The parameters and coordinates of the blade design can be achieved by pressing the “Compute” button, and three dimensional model of the blade can be established automatically in CATIA by pressing the “Establish the 3-D Model” button. So the parametric design of the hydraulic torque converter blade is achieved. V. CONCLUSION Almost all the CATIA functions achieved by hands can be achieved with secondary development technology, too. It is due to that CATIA provides diverse secondary development interfaces, almost cover all the functions in every module, for Automation. And CATIA has prominent performance on surface generation in geometric modeling. Meanwhile, the programming language has powerful functions and great freedom. This paper illustrates a parametric modeling method of generating the blade model of hydraulic torque converter rapidly. Finally this paper achieves a complete visualization of the calculation process based on VB 6.0, on whose interface the parameters of the blade and its three dimensional model can be generated. Thereby the development cycle of hydraulic torque converter blade can be reduced by using this method. REFERENCES [1]
Wu Ting, Wu Lijun, “Basis of Secondary Development Technology Based on CATIA,” Beijing, Publishing House of Electronics Industry, 2006.
[2]
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Xie Yue-feng, Yu Xiong-qing, “Parametric design of aircraft configuration using API in CATIA,” Computer Engineering and Design, July, 2008. Li Zisheng, Zhu Ying, Xiang Zhongfan, “Secondary Development Technology Based on CATIA,” Journal of Sichuan University of Science and Technology, 2002. Wang Jian, Ge An-lin, Lei Yu-long, Tian Hua, “Three-dimensional design for hydraulic torque converter blades and its performance
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analysis,” Journal of Jilin University (Engineering and Technology Edition), Jan. 2007. Wang Jian, Ge An-lin, Lei Yu-long, Tian Hua, Yang Jian-hua, “Design flow of torque converter based on three dimensional flow theory,” Journal of Jilin University (Engineering and Technology Edition), May 2006.
