JP3867603B2 - Piping design support system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a piping design support system for determining leakage from a joint portion of piping used at the time of layout design of piping such as a refrigerant hose of a car air conditioner.
[0002]
[Prior art]
Generally, the quick joint attachment of piping does not require screw tightening when attaching to a vehicle, and has an advantage of reducing the assembly cost when mounted on the vehicle. However, on the other hand, there is a concern that the refrigerant of the air conditioner leaks from the attachment portion due to vibrations to the attachment portion. The main factor of the vibration that causes this leakage is the vibration at the start of the engine, which is the vibration of the attachment portion from the compressor through the rubber hose and the metal pipe. Particularly at low temperatures such as in winter, the rubber hose becomes stiff and the effect of damping vibrations is reduced. Therefore, the engine start at a low temperature is a severe condition for causing leakage from the quick joint portion.
[0003]
Conventionally, in order to determine the leak from this quick joint, a prototype was actually made, the actual pipe layout was reproduced at a low-temperature test site, and the vibration from the quick joint was given a vibration equivalent to when the engine was started. Confirming that there is no actual machine. In such a test evaluation, when a leak occurs, the layout of the piping is designed again, which causes problems such as a trial cost for performing the trial evaluation, an increase in test cost, and a long development period.
[0004]
[Problems to be solved by the invention]
The present invention has been made by paying attention to the relationship between the linear distance between the piping restraint part and the joint part and the vibration displacement of the joint part, and the possibility of leakage from the joint part of the pipe. It is to provide a piping design support system that can reduce the trial production cost and test cost for performing the prototype evaluation and shorten the development period of the new model.
[0005]
[Means for Solving the Problems]
The present invention provides, as means for solving the above-mentioned problems, a piping design support system described in the claims.
The piping design support system according to claim 1, wherein a piping layout is created by a three-dimensional CAD program, a calculation model is created from the three-dimensional CAD shape, and vibration is applied to one end of the piping on the vibration source side, Analyze the run-out amount at the other end by computer calculation, and place the clamp part in the middle of the pipe so that the run-out amount falls within the area where it is judged that there is no leakage from the pipe. The layout is designed. Thus, in the past, the prototype was actually prototyped and the layout of the piping was designed while checking for leaks from the joints, but this can be done by computer analysis. Test costs can be greatly reduced, and the layout design development period can be shortened.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a piping design support system according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows the layout of the hose piping of the air conditioner. The air conditioner is composed of components such as a compressor 1, a capacitor 2, an evaporator 3 and a receiver & dryer 4, and these components are connected to a closed circuit by piping. Accordingly, the refrigerant in the refrigeration cycle is compressed by the compressor 1 to become a high-temperature / high-pressure gaseous refrigerant, sent to the condenser 2, cooled, liquefied, and converted into liquid refrigerant and sent to the receiver & dryer 4. It is rapidly expanded by the expansion valve and flows into the evaporator 3 as a low-temperature / low-pressure mist refrigerant, where it takes heat from the surrounding air to evaporate, and is heated to become a gaseous refrigerant. Return. By repeating this, the room is cooled. The compressor 1 is generally driven by an engine in an air conditioner for a vehicle.
[0007]
In this case, as shown in FIG. 1, the compressor 1 and the evaporator 3 are coupled via a rubber hose 10 and a metal pipe 11. A quick joint 12 is employed for the connection between the metal pipe 11 and the evaporator 3.
[0008]
FIG. 2 is a perspective view in which the air conditioner is mounted on the vehicle 12, and is a diagram illustrating displacement in each direction. That is, the front-rear direction that is the traveling direction of the vehicle is the X direction, the left-right direction that is the vehicle body width direction is the Y direction, and the vertical direction that is the vehicle body height direction is the Z direction. Further, as shown in FIG. 2, the YZ plane can be expressed by front view and the XZ plane can be expressed by right view.
[0009]
FIG. 3 shows an actual measurement example of hose piping laid out by the piping design support system of the present invention. In FIG. 3, reference symbol A indicates a point that gives vibration equivalent to when the engine is started, and corresponds to an attachment portion to the compressor 1. Reference sign B indicates a point where the pipe is attached to the vehicle, and corresponds to the bracket 13. Reference numeral C indicates an attachment point of a pipe called a clamp to the bracket 13. Reference numeral D denotes a quick joint portion 12 that couples the pipe of FIG. 1 to the evaporator 3 and swings due to vibration at point A.
[0010]
In the piping design support system according to the embodiment of the present invention, the straight line distance l between the point C where the pipe is clamped to the bracket 13 and the point D of the quick joint unit, and the point D of the quick joint unit. The refrigerant leakage of the quick joint portion 12 is predicted and determined based on the shake amount f on the YZ plane. The vibration given to point A varies depending on the layout of the engine. For horizontal engines, it is given on the XZ plane. For vertical engines, it is given on the YZ plane. Given in.
The shake amount f is obtained by adding the respective maximum values in the left-right direction (Y direction) f ₂ and the up-down direction (Z direction) f ₁ .
[0011]
FIG. 4 is a graph showing the measurement results of the actual measurement example. In this graph, the horizontal axis indicates the linear distance l between the point C, which is the clamp point of the pipe to the vehicle, and the point D of the quick joint, and the vertical axis indicates the amount of deflection of the point D, which is the quick joint. f is shown. In addition, plots ● and X in the graph indicate whether or not the refrigerant actually leaked when the quick joint 12 was actually attached, the refrigerant was sealed, and vibration was applied at point A in FIG. Represent. A plot ● indicates a case where there is no refrigerant leakage from the quick joint portion 12, and a plot × indicates a case where there is a refrigerant leakage from the quick joint portion 12.
[0012]
Also, the thick solid line in the graph of FIG. 4 is a reference line for determining refrigerant leakage from the distance l and the shake amount f, and was determined so as to cover the piping layout that actually caused the refrigerant leakage in the experiment.
Furthermore, it is divided into a region (a) where it is determined that refrigerant leakage does not occur, a region (b) where it is determined that refrigerant leakage occurs, and a region (c) that requires confirmation in the actual machine, taking into account calculation errors and measurement errors. .
[0013]
FIG. 5 shows a calculation flow in the piping design support system according to the embodiment of the present invention. First, in step S1, a hose piping layout is created using a three-dimensional CAD program. Next, in the shape creation for calculation in step S2, a calculation model for calculation by the finite element method is automatically created from the three-dimensional CAD shape based on the center line. Next, in the setting of the calculation conditions in step S3, physical property values (density, Young's modulus, etc.) necessary for the calculation are automatically input by selecting a component from a database stored for each component. In step S4, the deflection (vertical displacement f ₁ and lateral displacement f ₂ ) at point D due to vibration at point A is obtained by calculation using a finite element method. In step S5, the calculation result is read to determine the presence or absence of refrigerant leakage.
[0014]
FIG. 6 is a graph showing a comparison between a calculation result and an actual measurement regarding the displacement of the quick joint portion when the vehicle is viewed from the front. In this graph, the horizontal axis indicates the left-right displacement f ₂ that is the vehicle width direction (Y direction), and the vertical axis indicates the vertical displacement f ₁ that is the vehicle height direction (Z direction). . Moreover, the ellipse in the graph indicates the result of calculation, and the rectangle indicates the result of experiment. This experimental result shows the maximum width in a rectangle. Thereby, it turns out that the calculation result and the experimental result are in good agreement.
[0015]
(A) of FIG. 7 is the figure which showed the model of the piping layout before the countermeasure of this invention by the vehicle front view (YZ plane) and vehicle right side view (XZ plane) of FIG. 2, (b) The quick joint displacement in the model before this countermeasure is shown in front view of the vehicle. In this case, both the horizontal displacement f ₂ and the vertical displacement f ₁ caused a large shake of the quick joint portion, and refrigerant leakage occurred.
(C) shows the model of the piping layout after the countermeasure according to the present invention in the vehicle front view (YZ plane) and the vehicle right side view (XZ plane) as before. Specifically, the clamp part C is added to the quick joint part 12 side (indicated by C ₁ in the figure), and measures against refrigerant leakage are implemented. (D) shows the quick joint part displacement in the model after this countermeasure in front view of the vehicle. Consequently, lateral displacement f ₂ and vertical displacement f ₁ both become small deflection Quick joint, occurrence of refrigerant leakage could be prevented.
In the graphs (b) and (d), it can be seen that the experimental results represented by rectangles and the calculation results represented by ellipses are in good agreement.
[0016]
In the above description, the layout of the refrigerant piping of the air conditioner is described as an example, but the piping design support system of the present invention is naturally applicable to the layout of other piping systems. .
As described above, in the present invention, by performing calculation analysis by the finite element method at the stage of hose pipe layout design, refrigerant leakage can be predicted and the layout design can be corrected. Compared to the fact that the pipe layout is prototyped and the actual machine layout is reproduced to check for leaks, the prototype and test costs can be significantly reduced, and the development period can be shortened.
[Brief description of the drawings]
FIG. 1 is a diagram showing a layout of hose piping of an air conditioner.
FIG. 2 is a perspective view of an air conditioner mounted on a vehicle.
FIG. 3 shows an actual measurement example of hose piping laid out by the piping support system of the present invention.
FIG. 4 is a graph showing measurement results of an actual measurement example.
FIG. 5 shows a calculation flow in the piping support system according to the embodiment of the present invention.
FIG. 6 is a graph showing a comparison between a calculation result and an actual measurement regarding the displacement of the quick joint portion when the vehicle is viewed from the front.
FIGS. 7A and 7B show graphs (b) and (d) showing the shake amount of a quick joint portion with (a) a pipe layout model before countermeasures and (c) a pipe layout model after countermeasures of the present invention, respectively. ing.
[Explanation of symbols]
1 ... compressor 3 ... evaporator 10 ... rubber hose 11 ... metal pipe 12 ... Quick joint 13 ... Bracket A ... attachment point C to point B ... vehicle applying vibration, C ₁ ... clamping point (pipe restraining portion)
D ... Quick joint

Claims (1)

A piping design support system for determining leakage from piping, which is used at the time of piping layout design.
A piping layout having a clamp part that restrains the piping in the middle of piping is created by a three-dimensional CAD program, a calculation model is created from the three-dimensional CAD shape, and at one end on the vibration source side of the piping layout. Apply vibration and analyze the amount of shake at the joint, which is the other end, by calculation using a computer, and place the amount of shake at the other end within a region where it is determined that leakage from the pipe does not occur. A piping design support system, wherein piping is laid out so as to provide the clamp portion.

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