CN117972930A

CN117972930A - Piston pin design method, device, computer equipment and storage medium

Info

Publication number: CN117972930A
Application number: CN202410147474.2A
Authority: CN
Inventors: 谢琰; 杨武; 曾庆强; 禹慧丽
Original assignee: Chongqing Changan Automobile Co Ltd
Current assignee: Chongqing Changan Automobile Co Ltd
Priority date: 2024-01-31
Filing date: 2024-01-31
Publication date: 2024-05-03

Abstract

The invention relates to the technical field of engines, and discloses a piston pin design method, a device, computer equipment and a storage medium, wherein the piston pin design method comprises the following steps: and evaluating a preset preliminary evaluation item according to the piston parameter, the connecting rod parameter, the engine parameter and the current structural parameter to obtain a first evaluation result, when the first evaluation result does not meet the first design requirement, adjusting the current structural parameter to obtain a next structural parameter, taking the next structural parameter as the current structural parameter, and returning to the step of evaluating the current structural parameter until the first evaluation result meets the first design requirement to obtain the initial structural parameter of the piston pin. The analysis and optimization of the piston pin and the contact pair are completed through one-dimensional calculation, the occupied time is short, and the design efficiency of the piston pin is greatly improved.

Description

Piston pin design method, device, computer equipment and storage medium

Technical Field

The invention relates to the technical field of engines, in particular to a piston pin design method, a piston pin design device, computer equipment and a storage medium.

Background

The piston pin is used as a core part of the engine, the load is the most complex, the working condition is the worst, the running boundary conditions such as mechanical load, temperature load, engine oil lubrication, cooling, motion impact and the like are received in running, the problems such as piston pin clamping stagnation, bluing, fatigue fracture, abnormal sound among small ends of connecting rods, friction and abrasion and the like can be generated due to improper design, and further the development progress of the engine, the oil consumption and the emission characteristics are affected.

The piston pin is used as a core reciprocating part of the engine, the mass of the piston pin influences lubrication and torsional vibration of a crankshaft, particularly, under the background of light weight of a hybrid gasoline engine, the light weight of the piston pin of the core reciprocating part is particularly important, how to rapidly analyze and calculate the strength of the piston pin, so that the optimal design of the piston pin is realized, the related literature is less at present, the piston pin is mainly optimized according to experience and experimental verification design, and when the piston pin is developed in the face of fast-paced and low-cost development, better service projects are often difficult.

Disclosure of Invention

In view of the above, the present invention provides a piston pin design method, apparatus, computer device and storage medium, so as to solve the problem of low development efficiency of piston pins.

In a first aspect, an embodiment of the present invention provides a method for designing a piston pin, including the steps of: acquiring a piston parameter, a connecting rod parameter, an engine parameter and a current structural parameter of a piston pin; evaluating a preset preliminary evaluation item according to the piston parameter, the connecting rod parameter, the engine parameter and the current structure parameter to obtain a first evaluation result; judging whether the first evaluation result meets a preset first design requirement or not; when the first evaluation result does not meet the first design requirement, adjusting the current structural parameter to obtain a next structural parameter, taking the next structural parameter as the current structural parameter, and returning to the step of evaluating the current structural parameter according to the piston parameter, the connecting rod parameter and the engine parameter to obtain the first evaluation result; and when the first evaluation result meets the first design requirement, taking the current structural parameter as the initial structural parameter of the piston pin.

According to the piston pin design method provided by the embodiment of the invention, the analysis and optimization of the piston pin and the contact pair are completed through one-dimensional calculation, the occupied time is short, and the design efficiency of the piston pin is greatly improved.

In an alternative embodiment, the preliminary evaluation items include one or more of the following: the connecting rod small end hole specific pressure, the piston pin seat Kong Biya, the piston pin bending deformation, the piston pin elliptical deformation and the piston pin safety coefficient.

The current structural parameters of the piston pin can thus be evaluated accurately.

In an alternative embodiment, evaluating the preset preliminary evaluation items according to the piston parameter, the connecting rod parameter, the engine parameter and the current structural parameter, and obtaining the first evaluation result includes: calculating a projection area S _up of an upper half hole of a small end of the connecting rod, a projection area S _down of a lower half hole of the small end of the connecting rod, a projection area S '_up of an upper half hole of a piston pin hole, a projection area S' _down of a lower half hole of the piston pin hole, a load F _m of the small end of the middle connecting rod of the piston pin in a first working condition, a load F '_m of two sides of a pin seat of the piston pin in the first working condition, a load F _i of the small end of the middle connecting rod of the piston pin in a second working condition and a load F' _i of two sides of the pin seat of the piston pin in the second working condition respectively according to the current structural parameters, the piston parameters, the connecting rod parameters and the engine parameters; calculating according to F _m and S _down to obtain the first connecting rod small head hole specific pressure in the first working condition, and calculating according to F _i and S _up to obtain the second connecting rod small head hole specific pressure in the second working condition; calculating according to F '_m and S' _up to obtain a first piston pin boss Kong Biya under a first working condition; calculating according to F '_i and S' _down to obtain a second piston pin boss Kong Biya under a second working condition; calculating according to F _m and F' _m to respectively obtain bending deformation of the piston pin and elliptical deformation of the piston pin; and calculating according to the current structural parameters, the piston parameters, the connecting rod parameters and the engine parameters to obtain the safety coefficient of the piston pin.

In an alternative embodiment, calculating the connecting rod small end upper half hole projected area S _up, the connecting rod small end lower half hole projected area S _down, the piston pin hole upper half hole projected area S '_up, and the piston pin hole lower half hole projected area S' _down, respectively, according to the current structural parameters, the piston parameters, the connecting rod parameters, and the engine parameters of the piston pin includes: judging whether the projection pattern comprises an irregular area, wherein the projection pattern comprises a projection pattern of a connecting rod small head upper half hole, a projection pattern of a connecting rod small head lower half hole, a projection pattern of a piston pin hole upper half hole and a projection pattern of a piston pin hole lower half hole; when the projection graph does not contain the irregular area, calculating the area of the projection graph by using an area formula corresponding to the projection graph; when the projection pattern contains an irregular area, dividing the projection pattern into a regular area and an irregular area, calculating a first area of the irregular area by utilizing a calculus, calculating a second area of the regular area by utilizing an area formula corresponding to the regular area, and adding the first area and the second area to obtain the area of the projection pattern.

Therefore, the projection area S _up of the upper half hole of the small end of the connecting rod, the projection area S _down of the lower half hole of the small end of the connecting rod, the projection area S '_up of the upper half hole of the piston pin hole and the projection area S' _down of the lower half hole of the piston pin hole can be accurately calculated.

In an alternative embodiment, when the preliminary evaluation items include a plurality of evaluation items, determining whether the first evaluation result satisfies a preset first design requirement includes: respectively acquiring evaluation standards corresponding to each evaluation item; when all the evaluation items meet the acquired evaluation standards, judging that the first evaluation result meets the first design requirement; when at least one evaluation item does not meet the acquired evaluation criteria, it is determined that the first evaluation result does not meet the first design requirement.

The initial structural parameters of the resulting piston pin can thus be made to meet the first design requirements.

In an alternative embodiment, separately acquiring the evaluation criteria corresponding to each evaluation item includes: when the evaluation item is the connecting rod small end hole specific pressure, the evaluation standard is as follows: the specific pressure of the small end hole of the first connecting rod is smaller than a preset first threshold value, and the specific pressure of the small end hole of the second connecting rod is smaller than the first threshold value; the first threshold is determined according to the material of the small end of the connecting rod; when the evaluation item is the piston pin boss Kong Biya, the evaluation criteria are: the first piston pin boss Kong Biya is less than a preset second threshold value and the first piston pin boss Kong Biya is less than the second threshold value; wherein the second threshold is determined according to the material of the piston pin; when the evaluation item is the bending deformation of the piston pin, the evaluation criterion is: whether the piston pin bending deformation is less than a preset bending deformation allowable value, wherein the bending deformation allowable value is determined according to one or more of the following: the length of the piston pin of the engine, the diameter of the piston pin, the radial thickness of the piston pin and the highest design cylinder pressure of the engine; when the evaluation item is piston pin elliptical deformation, the evaluation criterion is: whether the piston pin elliptical deformation is smaller than a preset elliptical deformation allowable value is determined according to one or more of the following: the length of the piston pin of the engine, the diameter of the piston pin, the radial thickness of the piston pin and the highest design cylinder pressure of the engine; when the evaluation item is the piston pin safety coefficient, the evaluation standard is: and judging whether the safety coefficient of the piston pin is smaller than a preset third threshold value.

Thus, evaluation criteria corresponding to different evaluation items can be obtained. For allowable values of bending deformation and elliptical deformation, factors such as target cylinder pressure (load), length of a piston pin, diameter of the piston pin, radial thickness of the piston pin and the like of an engine are introduced by evaluation factors of a single cylinder diameter of a traditional engine, so that the rationality of an evaluation standard can be improved. In addition, because of the light weight requirements of hybrid engines, short wrist pins are often used, and the cylinder bores do not fully represent the length of the wrist pins, so that the length of the introduced wrist pins is more suitable.

In an alternative embodiment, when the first evaluation result does not meet the first design requirement, adjusting the current structural parameter to obtain the next structural parameter includes: when the first evaluation result does not meet the first design requirement, determining a current structure to be adjusted according to a preset adjustment sequence, and adjusting structural parameters of the current structure to be adjusted to obtain next structural parameters; wherein, the adjustment sequence is from front to back in proper order: only the inner diameter of the piston pin is adjusted; the inner diameter of the piston pin and the outer diameter of the piston pin are adjusted cooperatively; the inner diameter of the piston pin, the outer diameter of the piston pin, the length of the piston pin seat and the width of the small end of the connecting rod are adjusted in a cooperative manner; the inner diameter of the piston pin, the outer diameter of the piston pin, the length of the piston pin seat, the width of the small end of the connecting rod and the length of the piston pin are cooperatively adjusted.

This makes it possible to achieve an improved design with low costs and with ease.

In an alternative embodiment, after taking the current structural parameter as the initial structural parameter of the piston pin, the method further comprises: updating the piston parameters and the connecting rod parameters according to the initial structural parameters of the piston pin; establishing a piston pin strength analysis model according to the updated piston parameters and the updated connecting rod parameters; evaluating the initial structural parameters of the piston pin by using a piston pin strength analysis model to obtain a second evaluation result; wherein the second evaluation result includes: a wrist pin bending deformation value, a wrist pin elliptical deformation value, a stress intensity value and a fatigue safety coefficient value; judging whether a second evaluation result meets a preset second design requirement or not; when the second evaluation result does not meet the second design requirement, adjusting the initial structural parameter to obtain a next structural parameter, taking the next structural parameter as a current structural parameter, and returning to the step of evaluating the current structural parameter according to the piston parameter, the connecting rod parameter and the engine parameter to obtain a first evaluation result; and when the second evaluation result meets the second design requirement, taking the initial structural parameter as the target structural parameter of the piston pin.

That is, on the basis of obtaining the initial structural parameter of the piston pin through one-dimensional design, whether the initial structural parameter meets the second evaluation result is determined through the three-dimensional piston pin strength analysis model, so that the initial structural parameter can meet the production requirement of the piston pin. According to the embodiment of the invention, fatigue tests of the piston pin are replaced by simulation analysis of the finite element model, so that project cost is saved.

In an alternative embodiment, evaluating the initial structural parameters of the wrist pin using the wrist pin strength analysis model to obtain the wrist pin bending deformation value and the wrist pin elliptical deformation value includes: extracting the outer surface profile of the piston pin under a preset working condition in a piston pin strength analysis model; and calculating the bending deformation value and the elliptical deformation value of the piston pin by utilizing Fourier transformation according to the rim of the outer surface of the piston pin.

Therefore, the bending deformation value of the piston pin and the elliptical deformation value of the piston pin can be accurately determined.

In an alternative embodiment, determining whether the second evaluation result meets the preset second design requirement includes: when at least one of the bending deformation value, the elliptical deformation value, the stress intensity value and the fatigue safety coefficient value of the piston pin does not meet the corresponding judging standard, judging that the second evaluation result does not meet the second design requirement; and when the bending deformation value, the elliptical deformation value, the stress intensity value and the fatigue safety coefficient value of the piston pin all meet the corresponding judging standards, judging that the second evaluation result meets the second design requirement.

Therefore, whether the current structural parameter of the piston pin meets the second design requirement can be accurately judged.

In a second aspect, an embodiment of the present invention further provides a wrist pin design apparatus, where the apparatus includes an acquisition module, a first evaluation module, a first reset module, and an initial structural parameter determination module; the acquisition module is used for acquiring the piston parameters, the connecting rod parameters, the engine parameters and the current structural parameters of the piston pin; the first evaluation module is used for evaluating the current structural parameter according to the piston parameter, the connecting rod parameter and the engine parameter to obtain a first evaluation result; the first judging module is used for judging whether the first evaluation result meets a preset first design requirement or not; the first reset module is used for adjusting the current structural parameter to obtain a next structural parameter when the first evaluation result does not meet the first design requirement, taking the next structural parameter as the current structural parameter and returning to the step of evaluating the current structural parameter according to the piston parameter, the connecting rod parameter and the engine parameter to obtain the first evaluation result; and the initial structural parameter determining module is used for taking the current structural parameter as the initial structural parameter of the piston pin when the first evaluation result meets the first design requirement.

In a third aspect, the present invention provides a computer device, including a memory and a processor, where the memory and the processor are communicatively connected to each other, and the memory stores computer instructions, and the processor executes the computer instructions, thereby executing the wrist pin design method according to the first aspect or any one of the embodiments.

In a fourth aspect, the present invention provides a computer-readable storage medium having stored thereon computer instructions for causing a computer to execute the piston pin design method of the first aspect or any one of its corresponding embodiments.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings that are needed in the description of the embodiments or the prior art will be briefly described, and it is obvious that the drawings in the description below are some embodiments of the present invention, and other drawings can be obtained according to the drawings without inventive effort for a person skilled in the art.

FIG. 1 is a flow chart of a method of wrist pin design according to an embodiment of the present invention;

FIG. 2 is a flow chart of another wrist pin design method according to an embodiment of the present invention;

FIG. 3 is a schematic diagram of the assembly of a wrist pin with pin bosses and a small connecting rod head;

FIG. 4 is a schematic view of the projected area of the upper half hole of the small end of the connecting rod;

FIG. 5 is a schematic view of the projected area of the lower half hole of the small end of the connecting rod;

FIG. 6 is a schematic illustration of the projected area of the upper half of the piston pin boss;

FIG. 7 is a schematic view of the projected area of the lower half of the piston pin boss;

FIG. 8 is a flow chart of yet another wrist pin design method according to an embodiment of the present invention;

FIG. 9 is a flowchart of an example of a wrist pin design method according to an embodiment of the present invention;

FIG. 10 is a diagram of a piston pin finite element strength calculation model;

FIG. 11 is a schematic diagram of a wrist pin coordinate system setup;

FIG. 12 is a schematic view of a wrist pin surface grid;

FIG. 13 is a diagram of a piston pin surface for bending deformation displacement;

FIG. 14 is a graph of bending deformation data over the length of a wrist pin;

FIG. 15 is a diagram of piston pin surface for elliptical deformation displacement;

FIG. 16 is a graph of elliptical deformation data over the length of a wrist pin;

FIG. 17 is a block diagram of a wrist pin design apparatus according to an embodiment of the present invention;

FIG. 18 is a schematic diagram of the hardware architecture of a computer device according to an embodiment of the invention;

Wherein, 1, piston pin base; 2. a piston pin; 3. a connecting rod; 31 small-end hole oil grooves of the connecting rod; 32. a connecting rod small end bushing; 33. the upper half hole projects an area pattern; 34. a lower half hole projection area pattern; 11. the upper half hole of the piston pin seat projects an area graph; 12. the lower half hole of the piston pin seat projects an area graph; 21. a piston pin base circle; 22. the outer circle of the central area of the piston pin is deformed; 23. the outer circle of the edge of the end part of the piston pin is deformed; 24. a piston pin base circle; 25. the outer circle of the central area of the piston pin is deformed; 26. the outer circle of the edge of the end part of the piston pin is deformed; b. the distance of the center point of the pin boss; u, maximum distance of contact surface under the pin hole (distance of lower edge of the pin hole); a. the minimum distance of the contact surface on the pin hole (the distance of the upper edge of the pin hole); e. the width of the oil groove or the diameter of the oil hole; h. the width of the upper end of the small-end bearing; c. the width of the lower end of the small-end bearing; g. horizontal width at the center of the small head; g ₁, the horizontal width of the center of the piston pin hole; d _pin, piston pin outer diameter (pin outer diameter); d _pin, piston pin inner diameter (pin inner diameter); alpha, the inclination angle of the pin seat; beta, small head inclination angle (connecting rod small head inclination angle); f. the shortest distance on the bevel intersection (the shortest distance of the small-head side intersection line segment); f ₁, the farthest distance between two sides of the chamfer at the upper part of the pin hole (the nearest distance between intersecting line segments of the inner side surface of the pin boss).

Detailed Description

For the purpose of making the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the technical solutions of 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, and it is apparent that the described embodiments are some embodiments of the present invention, but not all embodiments of the present invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.

In accordance with an embodiment of the present invention, a wrist pin design method embodiment is provided, it being noted that the steps shown in the flowchart of the figures may be performed in a computer system, such as a set of computer executable instructions, and, although a logical sequence is shown in the flowchart, in some cases, the steps shown or described may be performed in a different order than what is shown herein.

In this embodiment, a wrist pin design method is provided, which can be used in a computer device. FIG. 1 is a flow chart of a method of designing a wrist pin according to an embodiment of the present invention, as shown in FIG. 1, the flow including the steps of:

Step S101: the piston parameters, connecting rod parameters, engine parameters (which may also be referred to as engine related parameters) and current structural parameters of the wrist pin are obtained.

Specifically, the piston parameters include: the pin seat inclination angle alpha, the minimum distance a of the upper contact surface of the pin hole, the maximum distance u of the lower contact surface of the pin hole, the distance b of the center point of the pin seat, the farthest distance f ₁ between two sides of the chamfer of the upper part of the pin hole (the closest distance of the intersecting line of the inner side surface of the pin seat), the center horizontal width g ₁ of the piston pin hole, the mass m _pin of the piston pin, the elastic modulus of the piston pin, the tensile strength of the piston pin material, the mass m _pis of the piston and the mass m _ring of the piston ring; the piston parameters can be obtained in a piston model and a piston pin 3D model.

The parameters of the connecting rod include: the connecting rod parameters can be obtained in the connecting rod model by the width c of the lower end of the small head bearing, the horizontal width g of the center of the small head, the width h of the upper end of the small head bearing, the inclination angle beta of the small head, the length L ₀ of the connecting rod, the connecting rod ratio and the shortest distance f on the intersection line of the bevel surfaces (the shortest distance of the intersection line of the side surfaces of the small head).

The engine parameters include: cylinder bore D _linr, crank radius R, rated speed n _r, engine maximum cylinder pressure P _M, and corresponding speed n, crankcase pressure P _o.

The current structural parameters of the wrist pin include at least one of: the outer diameter D _pin of the piston pin, the inner diameter D _pin of the piston pin, the total length L of the piston pin and the effective length L ₁ of the piston pin. Wherein the current structural parameters of the piston pin can be obtained in a 3D model of the piston pin.

Step S102: and evaluating a preset preliminary evaluation item according to the piston parameter, the connecting rod parameter, the engine parameter and the current structure parameter to obtain a first evaluation result.

Step S103: and judging whether the first evaluation result meets a preset first design requirement.

Step S104: and when the first evaluation result does not meet the first design requirement, adjusting the current structural parameter to obtain a next structural parameter, taking the next structural parameter as the current structural parameter, and returning to the step S102.

Step S105: and when the first evaluation result meets the first design requirement, taking the current structural parameter as the initial structural parameter of the piston pin.

According to the piston pin design method, analysis and optimization of the piston pin and the contact pair are completed through one-dimensional calculation, the occupied time is short, and the design efficiency of the piston pin is greatly improved.

In this embodiment, a wrist pin design method is provided, which can be used in a computer device. FIG. 2 is a flow chart of another wrist pin design method according to an embodiment of the present invention, as shown in FIG. 2, the flow including the steps of:

Step S201: the piston parameters, connecting rod parameters, engine parameters, and current structural parameters of the wrist pin are obtained. Please refer to step S101 in the embodiment shown in fig. 1 in detail, which is not described herein.

Step S202: and evaluating a preset preliminary evaluation item according to the piston parameter, the connecting rod parameter, the engine parameter and the current structure parameter to obtain a first evaluation result.

In an alternative embodiment, the preliminary evaluation items include one or more of the following: the connecting rod small end hole specific pressure, the piston pin seat Kong Biya, the piston pin bending deformation, the piston pin elliptical deformation and the piston pin safety coefficient. In an alternative embodiment, the method for evaluating the connecting rod small end bore specific pressure according to the piston parameter, the connecting rod parameter, the engine parameter and the current structural parameter to obtain the first connecting rod small end bore specific pressure and the second connecting rod small end specific pressure comprises the following steps: calculating the projection area S _up of the upper half hole of the small end of the connecting rod, the projection area S _down of the lower half hole of the small end of the connecting rod, the load F _m of the small end of the middle connecting rod of the piston pin in the first working condition and the load F _i of the small end of the middle connecting rod of the piston pin in the second working condition according to the current structural parameters, the piston parameters, the connecting rod parameters and the engine parameters; and calculating according to F _m and S _down to obtain the first connecting rod small head hole specific pressure in the first working condition, and calculating according to F _i and S _up to obtain the second connecting rod small head hole specific pressure in the second working condition.

In an alternative embodiment, evaluating the piston pin bosses Kong Biya based on the piston parameters, the connecting rod parameters, the engine parameters, and the current structural parameters to obtain the first piston pin boss Kong Biya and the second piston pin boss bore specific pressures includes the steps of: calculating the projection area S '_up of the upper half hole of the piston pin hole, the projection area S' _down of the lower half hole of the piston pin hole, the load F '_m on two sides of the pin boss of the piston pin in the first working condition and the load F' _i on two sides of the pin boss of the piston pin in the second working condition according to the current structural parameters, the piston parameters, the connecting rod parameters and the engine parameters; the first piston pin boss Kong Biya for the first operating condition is calculated based on F '_m and S' _up, and the second piston pin boss Kong Biya for the second operating condition is calculated based on F '_m and S' _down.

In an alternative embodiment, evaluating the wrist pin bending deformation and the wrist pin elliptical deformation based on the piston parameter, the connecting rod parameter, the engine parameter, and the current structural parameter, the obtaining the wrist pin bending deformation and the wrist pin elliptical deformation comprises: respectively calculating a load F _m at the small end of the middle connecting rod of the piston pin under the first working condition and a load F' _m at two sides of a pin seat of the piston pin under the first working condition according to the current structural parameters, the piston parameters, the connecting rod parameters and the engine parameters; the calculation is performed according to F _m and F' _m to obtain the wrist pin bending deformation and the wrist pin elliptical deformation, respectively.

In an alternative embodiment, evaluating the piston pin safety based on the piston parameter, the connecting rod parameter, the engine parameter, and the current structural parameter, the deriving the piston pin safety factor comprises:

And calculating according to the current structural parameters, the piston parameters, the connecting rod parameters and the engine parameters to obtain the safety coefficient of the piston pin.

The following describes a first evaluation result obtained by evaluating the preliminary evaluation items according to the piston parameters, the connecting rod parameters, the engine parameters and the current structural parameters by taking the evaluation of the preliminary evaluation items including the connecting rod small end hole specific pressure, the piston pin boss Kong Biya, the piston pin bending deformation, the piston pin elliptical deformation and the piston pin safety coefficient as an example, and specifically comprises the following steps:

Step S2021: and respectively calculating the projection area S _up of the upper half hole of the small end of the connecting rod, the projection area S _down of the lower half hole of the small end of the connecting rod, the projection area S '_up of the upper half hole of the piston pin hole, the projection area S' _down of the lower half hole of the piston pin hole, the load F _m of the small end of the connecting rod in the middle of the piston pin in the first working condition, the load F '_m of two sides of the pin seat of the piston pin in the first working condition, the load F _i of the small end of the connecting rod in the middle of the piston pin in the second working condition and the load F' _i of two sides of the pin seat of the piston pin in the second working condition according to the current structural parameters, the piston parameters, the connecting rod parameters and the engine parameters.

The first working condition is the highest cylinder pressure, and the second working condition is the largest inertial force.

In an alternative embodiment, calculating the connecting rod small end upper half hole projected area S _up, the connecting rod small end lower half hole projected area S _down, the piston pin hole upper half hole projected area S '_up, and the piston pin hole lower half hole projected area S' _down, respectively, according to the current structural parameters, the piston parameters, the connecting rod parameters, and the engine parameters of the piston pin includes the steps of:

Step A1: judging whether the projection pattern comprises an irregular area, wherein the projection pattern comprises a projection pattern of a connecting rod small head upper half hole, a projection pattern of a connecting rod small head lower half hole, a projection pattern of a piston pin hole upper half hole and a projection pattern of a piston pin hole lower half hole.

Step A2: when the projected pattern does not include an irregular area, the area of the projected pattern is calculated using an area formula corresponding to the projected pattern.

Step A3: when the projection pattern contains an irregular area, dividing the projection pattern into a regular area and an irregular area, calculating a first area of the irregular area by utilizing a calculus, calculating a second area of the regular area by utilizing an area formula corresponding to the regular area, and adding the first area and the second area to obtain the area of the projection pattern.

FIG. 4 is a schematic view of the projected area of the upper half bore of the connecting rod small end, with the center line being the center axis of the wrist pin. The left side view in fig. 4 is a side view of the small end of the connecting rod, and the direction of the dotted arrow indicates the projection direction of the upper half hole of the small end hole of the connecting rod to the central plane of the connecting rod; the middle diagram in fig. 4 is a schematic front cross-sectional view of the connecting rod small end, which mainly shows the shape of the end face of the piston small end hole; the right hand drawing in fig. 4 is a projected image of the semi-circular surface on the small end hole of the connecting rod on the center horizontal plane of the through axis.

Specifically, as shown in fig. 3 and 4, the edge portion of the projected pattern of the upper half hole of the small end of the connecting rod forms a half ellipse, and therefore, the calculation formula of the projected area S _up of the upper half hole of the small end of the connecting rod is as follows:

Or alternatively

Wherein,The oil groove width is shown in the formula (1), and the oil hole diameter is shown in the formula (2); that is, when the design structure of the piston pin includes an oil groove, the projection area S _up of the upper half hole of the connecting rod small end is calculated according to formula (1); when the design structure of the piston pin comprises the oil hole, the projection area S _up of the upper half hole of the small end of the connecting rod is calculated according to the formula (2).

FIG. 5 is a schematic view of the projected area of the lower half of the connecting rod small end, with the center line being the center axis of the wrist pin. The left hand side view in fig. 5 is a side view of the connecting rod small end, with the direction of the dashed arrow indicating the direction of projection of the lower half of the connecting rod small end bore toward the connecting rod center plane; the middle diagram in fig. 5 is a schematic front cross-sectional view of the connecting rod small end, mainly showing the shape of the end face of the piston small end hole; the right hand drawing in fig. 5 is a projected image of the lower semi-circular surface of the small end hole of the connecting rod on the center horizontal plane of the through axis.

As shown in fig. 3 and 5, the lower half hole projection pattern of the small end of the connecting rod is an irregular solid line pattern, the dotted line is a projection of the edge line of the pin hole on the complete chamfer, because the chamfer of the small end has an intersection line with the vertical end surface below, the elliptical edge in the projection area is truncated (the dotted lines at the two ends of the X axis direction of the pattern) and the intersection line of the chamfer is generally below the center of the small end of the connecting rod, therefore, the projection area formula is as follows:

Wherein,

The coordinate system is established on the projection center of the bevel hole of the small head, the x axis is the length direction of the connecting rod, the y axis is the axial direction of the hole of the small head,And f is more than or equal to 0 and less than or equal to D _pin, when f=0, the lower half part of the small head hole is all the chamfer surface, no vertical surface exists, the projection comprises an outside dotted line, and when f=D _pin, the lower half part of the small head hole is all the vertical surface, and no chamfer surface exists.

FIG. 6 is a schematic view of the projected area of the upper half of the piston pin boss, with the center line being the center axis of the piston pin. The left hand drawing in fig. 6 is a piston pin and piston pin boss part connection drawing; the upper right hand view in FIG. 6 is a partial view of the piston pin bore side view with the dashed arrow indicating the direction of projection of the upper pin bore half bore toward the pin bore center plane; the lower right view in fig. 6 is a projected pattern of the upper semi-circular surface of the piston pin bore on the center horizontal plane passing through the pin bore axis.

As shown in fig. 3 and 6, the formula of the upper half hole projection area S' _up of the piston pin hole is as follows, in the same manner as the connecting rod small end:

FIG. 7 is a schematic view of the projected area of the lower half of the piston pin boss, with the center line being the center axis of the piston pin. The left hand drawing in fig. 7 is a piston pin and piston pin boss part connection drawing; the upper right hand view in fig. 7 is a partial view of the piston pin bore side view with the dashed arrow indicating the direction of projection of the lower half of the pin bore toward the pin bore center plane; the lower right drawing in fig. 7 is a projected pattern of the lower half-circle surface of the piston pin bore on the center horizontal plane passing through the pin bore axis.

As shown in fig. 3 and 7, the formula of the piston pin bore lower half bore projected area S' _down is as follows:

in the formula (4) and the formula (5), wherein L ₁ is the effective length of the wrist pin.

The coordinate system is established on the projection center of the inclined surface hole of the pin boss, the length direction of the x-axis connecting rod is the axial direction of the pin hole,And 0 is less than or equal to f ₁≤D_pin, when f=0, the upper half part of the pin seat hole is all the chamfer surface, no vertical surface exists, the projection comprises an outside dotted line, and when f=D _pin, the upper half part of the inner side surface of the pin seat is all the vertical surface, and no chamfer surface exists.

In an alternative embodiment, the load F _m =in-cylinder pressure- (piston assembly inertial force+piston pin inertial force) at the small end of the intermediate connecting rod of the piston pin at the first operating condition is calculated using the following formula:

Wherein F _M is the maximum detonation pressure load, m _pis is the mass sum of piston, piston ring and snap ring, m _pin is the piston pin mass, R is the crank radius, n is the rotational speed corresponding to the highest cylinder pressure of the engine, λ is the connecting rod ratio, and connecting rod ratio = connecting rod length/crank radius.

In an alternative embodiment, the load F' _m across the piston pin boss during the first operating condition = in-cylinder pressure-inertial force of the piston assembly is calculated using the following equation:

Wherein F _M is the maximum detonation pressure load, m _pis is the mass sum of piston, piston ring and snap ring, R is the crank radius, n is the rotational speed corresponding to the highest cylinder pressure of the engine, λ is the connecting rod ratio, and connecting rod ratio = connecting rod length/crank radius. The load F' _m on both sides of the pin boss of the piston pin is downward in the first working condition.

It should be noted that the formula (6) and the formula (7) can pass through at F _M Calculated, where P _M is the maximum burst pressure in the cylinder, P ₀ is the crankcase pressure, and typically P ₀＝1bar,D_linr is the cylinder diameter.

In an alternative embodiment, the load at the small end of the connecting rod in the middle of the piston pin F _i = (piston assembly inertia force + piston pin inertia force) -in-cylinder pressure at the second operating condition is calculated by the following formula:

Where n _r is the rated rotational speed, F _I＝0、m_pis is the sum of the masses of piston + piston ring + snap ring, m _pin is the piston pin mass, R is the crank radius, λ is the connecting rod ratio, and connecting rod ratio = connecting rod length/crank radius. And in the second working condition, the load F _i at the small end of the middle connecting rod of the piston pin is upward.

In an alternative embodiment, the load F' _i across the piston pin boss during the second operating mode = inertial force of the piston assembly-in-cylinder pressure, calculated by the following equation:

Where m _pis is the sum of the masses of piston + piston ring + snap ring, R is the crank radius, n _r is the rated rotational speed, λ is the connecting rod ratio, and connecting rod ratio = connecting rod length/crank radius. And in the second working condition, the load F' _i on the two sides of the pin seat of the piston pin is upward.

In equations (8) and (9), F _I is the piston pressure load at the point of maximum inertial force at rated operating exhaust top dead center, where the piston pressure is approximately 0 because the exhaust end cylinder pressure and crankcase pressure are close.

Step S2022: and calculating to obtain the first connecting rod small end hole specific pressure in the first working condition according to the load F _m at the middle connecting rod small end of the piston pin and the projection area S _down of the lower half hole of the connecting rod small end in the first working condition, and calculating to obtain the second connecting rod small end hole specific pressure in the second working condition according to the load F _i at the two sides of the pin seat of the piston pin in the second working condition and the projection area S _up of the upper half hole of the connecting rod small end.

In an alternative embodiment, the first link small-end hole specific pressure P _cond calculated according to F _m and S _down under the first working condition may use the following formula:

In an alternative embodiment, the second connecting rod small end hole specific pressure P' _cond calculated according to F _i and S _up under the second working condition may be represented by the following formula:

Step S2023: calculating to obtain a first piston pin boss Kong Biya under the first working condition according to the loads F '_m on two sides of the piston pin boss and the projection area S' _up of the upper half hole of the piston pin hole under the first working condition; and calculating according to the load F '_i on two sides of the piston pin boss and the projection area S' _down of the lower half hole of the piston pin hole under the second working condition to obtain the second piston pin boss Kong Biya under the second working condition.

In an alternative embodiment, the first piston pin boss Kong Biya P _pis for the first operating condition calculated from F '_m and S' _up may be given by:

In an alternative embodiment, the second piston pin boss Kong Biya P ' _pis for the second operating condition calculated from F ' _i and S ' _down may be expressed as follows:

Step S2024: and calculating according to the load F _m at the small end of the middle connecting rod of the piston pin under the first working condition and the load F' _m at the two sides of the pin seat of the piston pin under the first working condition to respectively obtain the bending deformation of the piston pin and the elliptical deformation of the piston pin.

In an alternative embodiment, the wrist pin bending deformation calculated from F _m and F' _m may be calculated using the following formula:

where δ is the wrist pin bending deformation, max (F _m,F′_m) is the maximum load of the wrist pin, usually calculated by taking the maximum load introduction at the two ends of the wrist pin and the middle section of the wrist pin, and E is the elastic modulus of the wrist pin material.

In an alternative embodiment, the piston pin elliptical deformation calculated from F _m and F' _m may be calculated using the following formula:

Where Δd is the piston pin elliptical deformation, max (F _m,F′_m) is the maximum load of the piston pin, usually calculated by taking the maximum load introduction at both ends and in the middle of the piston pin, and E is the elastic modulus of the piston pin.

Step S2025: and calculating according to the current structural parameters, the piston parameters, the connecting rod parameters and the engine parameters to obtain the safety coefficient of the piston pin.

In an alternative embodiment, the piston pin safety factor may be calculated using the following formula:

Calculating longitudinal bending stress of the piston pin:

and (5) calculating transverse bending stress of the piston pin:

and (3) calculating the total stress of the piston pin:

and (3) calculating the stress fatigue limit of the piston pin:

σ_-1＝kσ_b (19)

The piston pin is a forged steel part and is carburized, wherein sigma _b is the tensile strength of the piston pin material, and the coefficient k=0.5-0.8.

And (3) calculating a piston pin safety coefficient:

step S203: and judging whether the first evaluation result meets a preset first design requirement.

Specifically, the respectively acquiring the evaluation criteria corresponding to each evaluation item includes:

When the evaluation item is the connecting rod small end hole specific pressure, the evaluation standard is as follows: the specific pressure of the small end hole of the first connecting rod is smaller than a preset first threshold value, and the specific pressure of the small end hole of the second connecting rod is smaller than the first threshold value; the first threshold is determined according to the material of the small end of the connecting rod. In the specific implementation process, a larger value can be selected from the first connecting rod small head specific pressure and the second connecting rod small head specific pressure, and whether the selected larger value is smaller than a first threshold value or not is judged. Illustratively, the first threshold is equal to the specific pressure that the material of the connecting rod small end can withstand.

When the evaluation item is the piston pin boss Kong Biya, the evaluation criteria are: the first piston pin boss Kong Biya is less than a preset second threshold value and the first piston pin boss Kong Biya is less than the second threshold value; wherein the second threshold is determined according to the material of the piston pin. In the specific implementation process, a larger value can be selected from the specific pressures of the first piston pin boss Kong Biya and the second piston pin boss hole, and whether the selected larger value is smaller than a second threshold value is judged. By way of example, the second threshold is equal to 115% of the specific pressure that the material of the piston pin can withstand.

When the evaluation item is the bending deformation of the piston pin, the evaluation criterion is: whether the piston pin bending deformation is less than a preset bending deformation allowable value, wherein the bending deformation allowable value is determined according to one or more of the following: the length of the piston pin of the engine, the diameter of the piston pin, the radial thickness of the piston pin and the highest design cylinder pressure of the engine.

When the evaluation item is piston pin elliptical deformation, the evaluation criterion is: whether the piston pin elliptical deformation is smaller than a preset elliptical deformation allowable value is determined according to one or more of the following: the length of the piston pin of the engine, the diameter of the piston pin, the radial thickness of the piston pin and the highest design cylinder pressure of the engine.

When the evaluation item is the piston pin safety coefficient, the evaluation standard is: and judging whether the safety coefficient of the piston pin is smaller than a preset third threshold value.

By way of example, the allowable bending deformation value can be calculated by the following equation:

δ₀＝k₁P_{highest to}+k₂L+k₃D_pin+k₄(D_pin-d_pin) (21)

Where δ ₀ is a bending deformation allowable paper, k ₁＝0.0005～0.0006,k₂＝0.0005～0.0006,k₃＝0.00055,k₄ =0.000275, and the bending deformation allowable value considers the influence of the engine piston pin length L, the piston pin diameter D _pin, the radial thickness of the piston pin (D _pin-d_pin)/2, and the engine maximum design cylinder pressure P _{highest to}.

By way of example, the allowable value of elliptical deformation can be calculated by the following equation:

Δd₀＝k₅P_{highest to}+k₆L+k₇D_liner+k₈(D_pin-d_pin) (22)

where Δd ₀ is an allowable elliptical deformation value, k ₅＝0.0003～0.0004,k₆＝0.0003～0.0004,k₇＝0.00035,k₈ =0.00035, which considers the effects of the engine piston pin length L, the piston pin diameter D _pin, the radial thickness of the piston pin (D _pin-d_pin)/2, and the engine maximum design cylinder pressure P _{highest to}.

For allowable values of bending deformation and elliptical deformation, factors such as target cylinder pressure (load), length of a piston pin, diameter of the piston pin, radial thickness of the piston pin and the like of an engine are introduced by evaluation factors of a single cylinder diameter of a traditional engine, so that the rationality of an evaluation standard can be improved. In addition, because of the light weight requirements of hybrid engines, short wrist pins are often used, and the cylinder bores do not fully represent the length of the wrist pins, so that the length of the introduced wrist pins is more suitable.

Step S204: and when the first evaluation result does not meet the first design requirement, adjusting the current structural parameter to obtain a next structural parameter, taking the next structural parameter as the current structural parameter, and returning to the step S202.

In an alternative embodiment, when the first evaluation result does not meet the first design requirement, the adjusting the current structural parameter to obtain the next structural parameter includes the following steps: when the first evaluation result does not meet the first design requirement, determining a current structure to be adjusted according to a preset adjustment sequence, and adjusting structural parameters of the current structure to be adjusted to obtain next structural parameters; wherein, the adjustment sequence is from front to back in proper order: only the inner diameter of the piston pin is adjusted; the inner diameter of the piston pin and the outer diameter of the piston pin are adjusted cooperatively; the inner diameter of the piston pin, the outer diameter of the piston pin, the length of the piston pin seat and the width of the small end of the connecting rod are adjusted in a cooperative manner; the inner diameter of the piston pin, the outer diameter of the piston pin, the length of the piston pin seat, the width of the small end of the connecting rod and the length of the piston pin are cooperatively adjusted.

That is, the adjustment sequence for each parameter is: ① ) The inner diameter of the piston pin, the outer diameter of the ② piston pin, the length of a ③ piston pin seat and the width of a connecting rod small end, and the length of the ④ piston pin. Specific operations such as, for example, when ① has been adjusted to meet the first design requirement, the optimization ends, otherwise ② is adjusted on the basis of ① adjustment, including ①② coordinated optimization, the main purpose being to bring the dimensions of ①+② to a reasonably coordinated state, if so, the optimization ends, otherwise ③ is optimized on the basis of ①+②, similarly, including ①+②+③ coordinated optimization, if so, the optimization ends, and so on, i.e., the optimization order can be reduced to ：①→①+②→①+②+③→①+②+③+④.

The method for determining the next structural parameter (namely the method for optimizing the structural parameter) is performed in sequence according to the principle that the parts with optimized sizes are concentrated on one part as much as possible, so that the optimization design is low in improvement cost and easy to realize.

Step S205: and when the first evaluation result meets the first design requirement, taking the current structural parameter as the initial structural parameter of the piston pin.

By way of example, by utilizing the editing and computing functions of EXCEL, the compiling and sorting of the piston pin optimization analysis work is completed according to the above theory based on the EXCEL environment, and an electronic computing file as shown in fig. 8 is formed, and the electronic file is stored in a computer. In a computer, input data and calculation results of one-dimensional calculation optimization analysis of the piston pin are output, and parameters such as the inner diameter and the outer diameter of the piston pin, the axial length of a piston pin hole, the axial length of a connecting rod small end hole and the like can be dynamically optimized in real time, so that the strength calculation and optimization efficiency of the piston pin can be greatly improved.

Further, the results can be automatically displayed in the computer.

In this embodiment, a wrist pin design method is provided, which can be used in a computer device. Fig. 8 is a flowchart of still another piston pin design method according to an embodiment of the present invention, and fig. 9 is a flowchart of an example of a piston pin design method according to an embodiment of the present invention, as shown in fig. 8 and 9, the flowchart including the steps of:

step S801: the piston parameters, connecting rod parameters, engine parameters, and current structural parameters of the wrist pin are obtained.

Step S802: and evaluating a preset preliminary evaluation item according to the piston parameter, the connecting rod parameter, the engine parameter and the current structure parameter to obtain a first evaluation result.

Step S803: and judging whether the first evaluation result meets a preset first design requirement.

Step S804: and when the first evaluation result does not meet the first design requirement, adjusting the current structural parameter to obtain a next structural parameter, taking the next structural parameter as the current structural parameter, and returning to the step S802.

Step S805: and when the first evaluation result meets the first design requirement, obtaining the initial structural parameter of the piston pin.

Step S806: updating the piston parameters and the connecting rod parameters according to the initial structural parameters of the piston pin; and establishing a piston pin strength analysis model according to the updated piston parameters and the updated connecting rod parameters.

Specifically, a piston pin strength analysis model is established using HYPERMESH based on the updated piston parameters and the updated connecting rod parameters. By way of example, FIG. 10 is a diagram of a piston pin finite element strength calculation model.

Step S807: evaluating the initial structural parameters of the piston pin by using a piston pin strength analysis model to obtain a second evaluation result; wherein the second evaluation result includes: the values of the bending deformation, the elliptical deformation, the stress intensity and the fatigue safety coefficient of the piston pin.

In an alternative embodiment, the method for evaluating the initial structural parameters of the piston pin by using the piston pin strength analysis model to obtain the bending deformation value of the piston pin and the elliptical deformation value of the piston pin comprises the following steps: extracting the outer surface profile of the piston pin under a preset working condition in a piston pin strength analysis model; and calculating the bending deformation value and the elliptical deformation value of the piston pin by utilizing Fourier transformation according to the rim of the outer surface of the piston pin.

Specifically, the selection of the wrist pin fatigue calculation rotation speed point is as follows: the explosion pressure point and the top dead center maximum inertia force point of the rated working condition, and the explosion pressure point and the top dead center maximum inertia force point under the maximum explosion pressure working condition meet the fatigue endurance requirement time of the engine under the two groups of circulation.

Specifically, the piston pin profile is represented by fourier transform to evaluate the bending deformation and elliptical deformation of the piston pin, and the elliptical deformation of the outer circular surface of the piston pin is calculated by fourier transform to calculate the deformation of different orders, as follows:

in the method, in the process of the invention, A _k and B _k are fourier coefficients; k is the order, k=1, …, i, θ is the phase angle.

And (3) sorting the data of each order, removing the deformation of 1 order representing translation, keeping the amplitude and phase information of the rest orders unchanged, and recovering the elliptic characteristic by inverse Fourier transform.

And calculating bending deformation and ellipticity deformation of the piston pin, importing an obd file of a calculation result of ABAQUS software into SimLab as an input file, establishing a cylindrical coordinate system, and selecting a coordinate system based on the center of the edge of the end face, wherein fig. 11 is a diagram of the vertical and piston pin axes. Fig. 12 is a schematic view of a wrist pin surface mesh, in which the wrist pin outer surface data is extracted in the coordinate system of fig. 11, the number of wrist pin outer surface meshes is defined, 90 points are taken in the circumferential direction circle (pin circumferential direction), and 50 points are taken in the Axial direction Axial (pin length direction).

The bending deformation was calculated as: the wrist pin bending deformation= (displacement of 0 ° to displacement of 180 °)/2-translational displacement, plot Bore Distortion is selected in the calculation interface, the deformation type circle distorsion is defined as Original, in deriving Original data, for clarity of presentation, as shown in fig. 13, only the wrist pin base circle shown at 21, the wrist pin center area outer circle shown at 22, and the wrist pin end edge outer circle deformation shown at 23 are reserved, wherein translational displacement is displacement of the wrist pin center, as shown in fig. 13, 22,0 ° is displacement of the highest point of the wrist pin cross section, and 180 ° is displacement of the lowest point of a certain cross section of the wrist pin.

Fig. 14 is a diagram of bending deformation data of the length of the wrist pin, that is, bending deformation of the wrist pin surface in the axial direction, in fig. 14, bending deformation of the wrist pin extracts data of 90 cross-sectional points in the entire length direction, and the finite element strength displacement, physical deformation of the wrist pin, and bending deformation calculation results are comprehensively shown, wherein the bending deformation should satisfy allowable values.

The elliptical deformation is calculated as: elliptic deformation= [ (0 degree deformation+180 degree deformation) + (90 degree deformation+270 degree deformation) ]/2, select Plot Bore Distorion in the calculation interface, define deformation type Circle, define deformation disfiguration as True (Expansion AND ECCENTRICITY removed), derive True disfiguration data, form the deformation result of piston pin excircle, for clarity of presentation, only keep three of the elliptic deformations as shown in fig. 15, wherein the piston pin base Circle shown at 24, the piston pin center region excircle shown at 25, the piston pin end edge excircle shown at 26, wherein 24 is displacement of piston pin cross section center, 0 ° is piston pin upper side, 180 ° is piston pin lower side. Calculation of ovality deformation of wrist pin cross-sectional deformation in the wrist pin length direction is shown in fig. 14.

Fig. 16 is a graph of elliptical deformation data over the length of the wrist pin, i.e., a graph of deformation of the ovality of each section of the wrist pin in the axial direction, as shown in fig. 16, the elliptical deformation is extracted by 50 points in the circumferential direction, 90 points are extracted in the entire length direction, and the entire wrist pin surface is included, wherein the elliptical deformation should satisfy allowable values.

After the strength of the piston pin is calculated by ABAQUS, the fatigue safety coefficient is calculated by FEMAAT software, wherein the stress of the piston pin is less than the yield strength limit, and the safety coefficient is more than 1.1.

Step S808: and judging whether the second evaluation result meets a preset second design requirement.

Step S809: and when the second evaluation result does not meet the second design requirement, adjusting the initial structural parameter to obtain a next structural parameter, taking the next structural parameter as the current structural parameter, and returning to the step S802.

Step S810: and when the second evaluation result meets the second design requirement, taking the initial structural parameter as the target structural parameter of the piston pin.

That is, according to the piston pin design method provided by the embodiment of the invention, the parameters such as the diameter of the inner hole and the outer hole of the piston pin are rapidly determined by carrying out parameterization calculation analysis on the piston pin according to the basic parameters of the engine, the structural parameters of the piston model, the structural parameters of the small end model of the connecting rod and the like, and then the piston pin structure is finally determined through finite element calculation verification.

It should be noted that, in the conventional design of the piston, there are three general approaches to evaluating the piston pin contact pair after the design is completed.

First, the evaluation is performed by a wrist pin fatigue endurance test, a contact pair test, or the like, and the evaluation may be performed by a wrist pin fatigue test for a large displacement engine. However, this method is used for a relatively small amount of time, a relatively high test cost, and the like, and is more used for technical research.

Secondly, the finite element model of the piston pin is adopted for evaluation, and in general, 5 days are required for the fatigue strength finite element analysis (modeling and calculation) of the piston pin; the first round of optimization needs 4 days (mainly 1 day for improvement of the geometric model of the piston pin, the piston and the connecting rod, and 2 days for modeling of the corresponding finite element model, and 1 day for calculation and result extraction discussion), so the contact pair size of the piston pin and the optimization of the size of the piston pin need at least 4 days, usually both the reliability of the piston pin needs to be ensured, and due to the purpose of ensuring light weight, at least 2 rounds of optimization and 1 round of confirmation (less estimated 2 days for confirming the model change) generally need 15 days in total.

Thirdly, the contact pair was evaluated by kinetics and the intensity by finite elements, taking a total of 54 days. Wherein dynamic modeling (piston, connecting rod, wrist pin, cylinder, etc. involve thermal deformation, model reduction and model of the power itself) requires conservatively 30 days, calculation and analysis and debugging take 3 to 5 days, optimization one round only requires 3 to 5 days, thus modeling and calculation take 33 to 35 days, and generally 2 rounds of optimization are required, because the contact pair involves the change of the piston, wrist pin and connecting rod finite element model, wherein the update finite element model and model reduction are involved, conservation estimation works for 8 days, and thus, the time generally reaches 49 to 51 days, and thus, the method has high theoretical research value, but the current design of the fast-paced hybrid engine is difficult to implement, and in addition, fatigue strength analysis (modeling and calculation) of the wrist pin also requires calculation and analysis for 5 days, so the wrist pin total optimization time is about 54 to 56 days.

According to the piston pin setting method provided by the embodiment of the invention, the analysis and optimization of the piston pin and the contact pair are completed through one-dimensional calculation, the calculation almost does not need time, mainly the design and discussion of the size of the contact pair are presented, the optimization cost is the minimum, the optimization size parts are concentrated on one part as much as possible, so that the optimization design and improvement cost is low, and only 1 day is needed. Fatigue strength analysis (modeling and calculation) verification of the wrist pin takes 5 days to complete for a total of 6 days. Therefore, the design efficiency is greatly improved. Finally, the fatigue test of the piston pin is replaced by the simulation analysis of the finite element model, so that project cost is saved.

In this embodiment, a piston pin design device is further provided, and the device is used to implement the foregoing embodiments and preferred embodiments, and is not described herein. As used below, the term "module" may be a combination of software and/or hardware that implements a predetermined function. While the means described in the following embodiments are preferably implemented in software, implementation in hardware, or a combination of software and hardware, is also possible and contemplated.

The present embodiment provides a piston pin design apparatus, as shown in fig. 17, including:

An acquisition module 1701 is configured to acquire a piston parameter, a connecting rod parameter, an engine parameter, and a current structural parameter of the wrist pin.

The first evaluation module 1702 is configured to evaluate a preset preliminary evaluation item according to a piston parameter, a connecting rod parameter, an engine parameter and a current structural parameter, so as to obtain a first evaluation result.

The first judging module 1703 is configured to judge whether the first evaluation result meets a preset first design requirement.

The first resetting module 1704 is configured to adjust the current structural parameter to obtain a next structural parameter when the first evaluation result does not meet the first design requirement, and return the next structural parameter to the first evaluation module 1702 as the current structural parameter;

the initial structural parameter determining module 1705 is configured to take the current structural parameter as an initial structural parameter of the piston pin when the first evaluation result meets the first design requirement.

In an alternative embodiment, the preliminary evaluation items include: the connecting rod small end hole specific pressure, the piston pin seat Kong Biya, the piston pin bending deformation, the piston pin elliptical deformation and the piston pin safety coefficient.

In an alternative embodiment, the first evaluation module 1702 is specifically configured to: calculating a projection area S _up of an upper half hole of a small end of the connecting rod, a projection area S _down of a lower half hole of the small end of the connecting rod, a projection area S '_up of an upper half hole of a piston pin hole, a projection area S' _down of a lower half hole of the piston pin hole, a load F _m of the small end of the middle connecting rod of the piston pin in a first working condition, a load F '_m of two sides of a pin seat of the piston pin in the first working condition, a load F _i of the small end of the middle connecting rod of the piston pin in a second working condition and a load F' _i of two sides of the pin seat of the piston pin in the second working condition respectively according to the current structural parameters, the piston parameters, the connecting rod parameters and the engine parameters; calculating according to F _m and S _down to obtain the first connecting rod small head hole specific pressure in the first working condition, and calculating according to F _i and S _up to obtain the second connecting rod small head hole specific pressure in the second working condition; calculating according to F '_m and S' _up to obtain a first piston pin boss Kong Biya under a first working condition; calculating according to F '_i and S' _down to obtain a second piston pin boss Kong Biya under a second working condition; calculating according to F _m and F' _m to respectively obtain bending deformation of the piston pin and elliptical deformation of the piston pin; and calculating according to the current structural parameters, the piston parameters, the connecting rod parameters and the engine parameters to obtain the safety coefficient of the piston pin.

In an alternative embodiment, the data preprocessing unit is specifically configured to: judging whether the projection pattern comprises an irregular area, wherein the projection pattern comprises a projection pattern of a connecting rod small head upper half hole, a projection pattern of a connecting rod small head lower half hole, a projection pattern of a piston pin hole upper half hole and a projection pattern of a piston pin hole lower half hole; when the projection graph does not contain the irregular area, calculating the area of the projection graph by using an area formula corresponding to the projection graph; when the projection pattern contains an irregular area, dividing the projection pattern into a regular area and an irregular area, calculating a first area of the irregular area by utilizing a calculus, calculating a second area of the regular area by utilizing an area formula corresponding to the regular area, and adding the first area and the second area to obtain the area of the projection pattern.

In an alternative embodiment, the first judgment module 1703 includes an evaluation criterion determination unit and a judgment unit. Wherein the evaluation criterion determining unit is used for respectively acquiring the evaluation criterion corresponding to each evaluation item; the judging unit is used for: when all the evaluation items meet the acquired evaluation standards, judging that the first evaluation result meets the first design requirement; when at least one evaluation item does not meet the acquired evaluation criteria, it is determined that the first evaluation result does not meet the first design requirement.

In an alternative embodiment, the evaluation criterion determination unit is configured to: when the evaluation item is the connecting rod small end hole specific pressure, the evaluation standard is as follows: the specific pressure of the small end hole of the first connecting rod is smaller than a preset first threshold value, and the specific pressure of the small end hole of the second connecting rod is smaller than the first threshold value; the first threshold is determined according to the material of the small end of the connecting rod; when the evaluation item is the piston pin boss Kong Biya, the evaluation criteria are: the first piston pin boss Kong Biya is less than a preset second threshold value and the first piston pin boss Kong Biya is less than the second threshold value; wherein the second threshold is determined according to the material of the piston pin; when the evaluation item is the bending deformation of the piston pin, the evaluation criterion is: whether the piston pin bending deformation is less than a preset bending deformation allowable value, wherein the bending deformation allowable value is determined according to one or more of the following: the length of the piston pin of the engine, the diameter of the piston pin, the radial thickness of the piston pin and the highest design cylinder pressure of the engine; when the evaluation item is piston pin elliptical deformation, the evaluation criterion is: whether the piston pin elliptical deformation is smaller than a preset elliptical deformation allowable value is determined according to one or more of the following: the length of the piston pin of the engine, the diameter of the piston pin, the radial thickness of the piston pin and the highest design cylinder pressure of the engine; when the evaluation item is the piston pin safety coefficient, the evaluation standard is: and judging whether the safety coefficient of the piston pin is smaller than a preset third threshold value.

In an alternative embodiment, the first reset module 1704 includes a reset unit and a circulation unit; wherein the reset unit is specifically configured to: when the first evaluation result does not meet the first design requirement, determining a current structure to be adjusted according to a preset adjustment sequence, and adjusting structural parameters of the current structure to be adjusted to obtain next structural parameters; wherein, the adjustment sequence is from front to back in proper order: only the inner diameter of the piston pin is adjusted; the inner diameter of the piston pin and the outer diameter of the piston pin are adjusted cooperatively; the inner diameter of the piston pin, the outer diameter of the piston pin, the length of the piston pin seat and the width of the small end of the connecting rod are adjusted in a cooperative manner; the inner diameter of the piston pin, the outer diameter of the piston pin, the length of the piston pin seat, the width of the small end of the connecting rod and the length of the piston pin are cooperatively adjusted. The circulation unit is used for: the next structural parameter is taken as the current structural parameter and returned to the first evaluation module 1702.

In an alternative embodiment, the piston pin design device comprises a piston pin strength analysis model construction module, a second evaluation module, a second judgment module, a second reset module and a target structure parameter determination module; the piston pin strength analysis model construction module is used for updating the piston parameters and the connecting rod parameters according to the initial structural parameters of the piston pin; establishing a piston pin strength analysis model according to the updated piston parameters and the updated connecting rod parameters; the second evaluation module is used for evaluating the initial structural parameters of the piston pin by using the piston pin strength analysis model to obtain a second evaluation result; wherein the second evaluation result includes: a wrist pin bending deformation value, a wrist pin elliptical deformation value, a stress intensity value and a fatigue safety coefficient value; the second judging module is used for judging whether a second evaluation result meets a preset second design requirement or not; the second resetting module is used for adjusting the initial structural parameter to obtain a next structural parameter when the second evaluation result does not meet the second design requirement, taking the next structural parameter as the current structural parameter and returning to the step of evaluating the current structural parameter according to the piston parameter, the connecting rod parameter and the engine parameter to obtain a first evaluation result; and the target structural parameter determining module is used for taking the initial structural parameter as the target structural parameter of the piston pin when the second evaluation result meets the second design requirement.

In an alternative embodiment, the second evaluation module comprises a deformation evaluation unit, a stress intensity evaluation unit and a safety evaluation unit. Wherein, deformation evaluation unit is used for: extracting the outer surface profile of the piston pin under a preset working condition in a piston pin strength analysis model; and calculating the bending deformation value and the elliptical deformation value of the piston pin by utilizing Fourier transformation according to the rim of the outer surface of the piston pin.

In an alternative embodiment, the second judging module is specifically configured to: when at least one of the bending deformation value, the elliptical deformation value, the stress intensity value and the fatigue safety coefficient value of the piston pin does not meet the corresponding judging standard, judging that the second evaluation result does not meet the second design requirement; and when the bending deformation value, the elliptical deformation value, the stress intensity value and the fatigue safety coefficient value of the piston pin all meet the corresponding judging standards, judging that the second evaluation result meets the second design requirement.

The wrist pin design device in this embodiment is presented in the form of a functional unit, where the unit refers to an ASIC circuit, a processor and memory executing one or more software or fixed programs, and/or other means that can provide the above-described functionality.

Further functional descriptions of the above respective modules and units are the same as those of the above corresponding embodiments, and are not repeated here.

The embodiment of the invention also provides computer equipment, which is provided with the piston pin setting device shown in the figure 17.

Referring to fig. 18, fig. 18 is a schematic structural diagram of a computer device according to an alternative embodiment of the present invention, as shown in fig. 18, the computer device includes: one or more processors 10, memory 20, and interfaces for connecting the various components, including high-speed interfaces and low-speed interfaces. The various components are communicatively coupled to each other using different buses and may be mounted on a common motherboard or in other manners as desired. The processor may process instructions executing within the computer device, including instructions stored in or on memory to display graphical information of the GUI on an external input/output device, such as a display device coupled to the interface. In some alternative embodiments, multiple processors and/or multiple buses may be used, if desired, along with multiple memories and multiple memories. Also, multiple computer devices may be connected, each providing a portion of the necessary operations (e.g., as a server array, a set of blade servers, or a multiprocessor system). One processor 10 is illustrated in fig. 18.

The processor 10 may be a central processor, a network processor, or a combination thereof. The processor 10 may further include a hardware chip, among others. The hardware chip may be an application specific integrated circuit, a programmable logic device, or a combination thereof. The programmable logic device may be a complex programmable logic device, a field programmable gate array, a general-purpose array logic, or any combination thereof.

Wherein the memory 20 stores instructions executable by the at least one processor 10 to cause the at least one processor 10 to perform a method for implementing the embodiments described above.

The memory 20 may include a storage program area that may store an operating system, at least one application program required for functions, and a storage data area; the storage data area may store data created from the use of the computer device of the presentation of a sort of applet landing page, and the like. In addition, the memory 20 may include high-speed random access memory, and may also include non-transitory memory, such as at least one magnetic disk storage device, flash memory device, or other non-transitory solid-state storage device. In some alternative embodiments, memory 20 may optionally include memory located remotely from processor 10, which may be connected to the computer device via a network. Examples of such networks include, but are not limited to, the internet, intranets, local area networks, mobile communication networks, and combinations thereof.

Memory 20 may include volatile memory, such as random access memory; the memory may also include non-volatile memory, such as flash memory, hard disk, or solid state disk; the memory 20 may also comprise a combination of the above types of memories.

The computer device further comprises input means 30 and output means 40. The processor 10, memory 20, input device 30, and output device 40 may be connected by a bus or other means, for example in fig. 18.

The input device 30 may receive input numeric or character information and generate key signal inputs related to user settings and function control of the computer apparatus, such as a touch screen, a keypad, a mouse, a trackpad, a touchpad, a pointer stick, one or more mouse buttons, a trackball, a joystick, and the like. The output means 40 may include a display device, an auxiliary lighting means (e.g., LD), a haptic feedback means (e.g., vibration motor), and the like. Such display devices include, but are not limited to, liquid crystal displays, light emitting diodes, displays and plasma displays. In some alternative implementations, the display device may be a touch screen.

The embodiments of the present invention also provide a computer readable storage medium, and the method according to the embodiments of the present invention described above may be implemented in hardware, firmware, or as a computer code which may be recorded on a storage medium, or as original stored in a remote storage medium or a non-transitory machine readable storage medium downloaded through a network and to be stored in a local storage medium, so that the method described herein may be stored on such software process on a storage medium using a general purpose computer, a special purpose processor, or programmable or special purpose hardware. The storage medium can be a magnetic disk, an optical disk, a read-only memory, a random access memory, a flash memory, a hard disk, a solid state disk or the like; further, the storage medium may also comprise a combination of memories of the kind described above. It will be appreciated that a computer, processor, microprocessor controller or programmable hardware includes a storage element that can store or receive software or computer code that, when accessed and executed by the computer, processor or hardware, implements the methods illustrated by the above embodiments.

Although embodiments of the present invention have been described in connection with the accompanying drawings, various modifications and variations may be made by those skilled in the art without departing from the spirit and scope of the invention, and such modifications and variations fall within the scope of the invention as defined by the appended claims.

Claims

1. A method of designing a wrist pin, the method comprising:

Acquiring a piston parameter, a connecting rod parameter, an engine parameter and a current structural parameter of a piston pin;

Evaluating a preset preliminary evaluation item according to the piston parameter, the connecting rod parameter, the engine parameter and the current structure parameter to obtain a first evaluation result;

Judging whether the first evaluation result meets a preset first design requirement or not;

When the first evaluation result does not meet the first design requirement, adjusting the current structural parameter to obtain a next structural parameter, taking the next structural parameter as the current structural parameter, and returning to the step of evaluating the current structural parameter according to the piston parameter, the connecting rod parameter and the engine parameter to obtain a first evaluation result;

and when the first evaluation result meets the first design requirement, taking the current structural parameter as an initial structural parameter of the piston pin.

2. The method of claim 1, wherein the preliminary evaluation item comprises: the connecting rod small end hole specific pressure, the piston pin seat Kong Biya, the piston pin bending deformation, the piston pin elliptical deformation and the piston pin safety coefficient.

3. The method of claim 2, wherein evaluating the pre-set preliminary evaluation item according to the piston parameter, the connecting rod parameter, the engine parameter, and the current structural parameter, the obtaining a first evaluation result comprises:

Calculating a projection area S _up of an upper half hole of a small end of a connecting rod, a projection area S _down of a lower half hole of the small end of the connecting rod, a projection area S _u′_p of an upper half hole of a piston pin hole, a projection area S _d′_own of a lower half hole of the piston pin hole, a load F _m of a small end of a middle connecting rod of the piston pin in a first working condition, a load F _m 'of two sides of a pin seat of the piston pin in the first working condition, a load F _i of the small end of the middle connecting rod of the piston pin in a second working condition and a load F _i' of two sides of the pin seat of the piston pin in the second working condition respectively according to the current structural parameters, the piston parameters, the connecting rod parameters and the engine parameters;

Calculating to obtain a first connecting rod small head hole specific pressure under the first working condition according to the F _m and the S _down, and calculating to obtain a second connecting rod small head hole specific pressure under the second working condition according to the F _i and the S _up;

Calculating to obtain a first piston pin boss Kong Biya under the first working condition according to the F _m' and the S _u′_p; calculating to obtain a second piston pin boss Kong Biya under the second working condition according to the F _i' and the S _d′_own;

Calculating according to the F _m and the F _m' to respectively obtain bending deformation of the piston pin and elliptical deformation of the piston pin;

4. The method of claim 3, wherein calculating the connecting rod small head upper half bore projected area S _up, the connecting rod small head lower half bore projected area S _down, the piston pin bore upper half bore projected area S _u′_p, and the piston pin bore lower half bore projected area S _d′_own, respectively, based on the current structural parameters of the piston pin, the piston parameters, the connecting rod parameters, and the engine parameters comprises:

Judging whether the projection pattern comprises an irregular area, wherein the projection pattern comprises a projection pattern of a connecting rod small head upper half hole, a projection pattern of a connecting rod small head lower half hole, a projection pattern of a piston pin hole upper half hole and a projection pattern of a piston pin hole lower half hole;

When the projection graph does not contain the irregular area, calculating the area of the projection graph by using an area formula corresponding to the projection graph;

When the projection graph comprises the irregular area, dividing the projection graph into a regular area and an irregular area, calculating a first area of the irregular area by utilizing a calculus, calculating a second area of the regular area by utilizing an area formula corresponding to the regular area, and adding the first area and the second area to obtain the area of the projection graph.

5. The method of claim 2, wherein when the preliminary evaluation item includes a plurality of evaluation items, the determining whether the first evaluation result satisfies a preset first design requirement includes:

respectively acquiring evaluation standards corresponding to each evaluation item;

when all the evaluation items meet the acquired evaluation standards, judging that the first evaluation result meets the first design requirement;

And when at least one evaluation item does not meet the acquired evaluation standard, judging that the first evaluation result does not meet the first design requirement.

6. The method of claim 5, wherein the separately obtaining the evaluation criteria corresponding to each evaluation item comprises:

When the evaluation item is the connecting rod small end hole specific pressure, the evaluation standard is as follows: the specific pressure of the small end hole of the first connecting rod is smaller than a preset first threshold value, and the specific pressure of the small end hole of the second connecting rod is smaller than the first threshold value; the first threshold is determined according to the material of the small end of the connecting rod;

When the evaluation item is a piston pin boss Kong Biya, the evaluation criterion is: the first piston pin boss Kong Biya is less than a preset second threshold value and the first piston pin boss Kong Biya is less than the second threshold value; wherein the second threshold is determined according to the material of the piston pin;

When the evaluation item is a wrist pin bending deformation, the evaluation criterion is: whether the piston pin bending deformation is less than a preset bending deformation allowable value, wherein the bending deformation allowable value is determined according to one or more of the following: the length of the piston pin of the engine, the diameter of the piston pin, the radial thickness of the piston pin and the highest design cylinder pressure of the engine;

when the evaluation item is a piston pin elliptical deformation, the evaluation criterion is: whether the piston pin elliptical deformation is smaller than a preset elliptical deformation allowable value or not is determined according to one or more of the following: the length of the piston pin of the engine, the diameter of the piston pin, the radial thickness of the piston pin and the highest design cylinder pressure of the engine;

when the evaluation item is a piston pin safety factor, the evaluation criterion is: and judging whether the safety coefficient of the piston pin is smaller than a preset third threshold value.

7. The method of claim 1, wherein when the first evaluation result does not meet the first design requirement, adjusting the current structural parameter to obtain the next structural parameter comprises:

When the first evaluation result does not meet the first design requirement, determining a current structure to be adjusted according to a preset adjustment sequence, and adjusting structural parameters of the current structure to be adjusted to obtain the next structural parameters;

Wherein, the adjustment sequence is from front to back in turn: only the inner diameter of the piston pin is adjusted; the inner diameter of the piston pin and the outer diameter of the piston pin are adjusted cooperatively; the inner diameter of the piston pin, the outer diameter of the piston pin, the length of a piston pin seat and the width of a small end of a connecting rod are adjusted in a cooperative manner; and the inner diameter of the piston pin, the outer diameter of the piston pin, the length of the piston pin seat, the width of the small end of the connecting rod and the length of the piston pin are cooperatively adjusted.

8. The method of claim 1, further comprising, after taking the current structural parameter as an initial structural parameter of the wrist pin:

Updating the piston parameters and the connecting rod parameters according to the initial structural parameters of the piston pin; establishing a piston pin strength analysis model according to the updated piston parameters and the updated connecting rod parameters;

Evaluating the initial structural parameters of the piston pin by using the piston pin strength analysis model to obtain a second evaluation result; wherein the second evaluation result includes: a wrist pin bending deformation value, a wrist pin elliptical deformation value, a stress intensity value and a fatigue safety coefficient value;

judging whether the second evaluation result meets a preset second design requirement or not;

when the second evaluation result does not meet the second design requirement, adjusting the initial structural parameter to obtain a next structural parameter, taking the next structural parameter as the current structural parameter, and returning to the step of evaluating the current structural parameter according to the piston parameter, the connecting rod parameter and the engine parameter to obtain a first evaluation result;

and when the second evaluation result meets the second design requirement, taking the initial structural parameter as a target structural parameter of the piston pin.

9. The method of claim 8, wherein evaluating the initial structural parameters of the wrist pin using the wrist pin strength analysis model to obtain the wrist pin bending deformation value and the wrist pin elliptical deformation value comprises:

Extracting the outer surface profile of the piston pin under a preset working condition from the piston pin strength analysis model;

and calculating the bending deformation value of the piston pin and the elliptical deformation value of the piston pin by utilizing Fourier transformation according to the rim on the outer surface of the piston pin.

10. The method of claim 8, wherein the determining whether the second evaluation result meets a preset second design requirement comprises:

when at least one of the piston pin bending deformation value, the piston pin elliptical deformation value, the stress intensity value and the fatigue safety coefficient value does not meet the corresponding judgment standard, judging that the second evaluation result does not meet the second design requirement;

and when the bending deformation value of the piston pin, the elliptical deformation value of the piston pin, the stress intensity value and the fatigue safety coefficient value all meet corresponding judging standards, judging that the second evaluation result meets the second design requirement.

11. A wrist pin design apparatus, the apparatus comprising:

the acquisition module is used for acquiring the piston parameters, the connecting rod parameters, the engine parameters and the current structural parameters of the piston pin;

the first evaluation module evaluates a preset preliminary evaluation item according to the piston parameter, the connecting rod parameter, the engine parameter and the current structure parameter to obtain a first evaluation result;

The first judging module is used for judging whether the first evaluation result meets a preset first design requirement or not;

The first resetting module is used for adjusting the current structural parameter to obtain a next structural parameter when the first evaluation result does not meet the first design requirement, taking the next structural parameter as the current structural parameter and returning to the step of evaluating the current structural parameter according to the piston parameter, the connecting rod parameter and the engine parameter to obtain a first evaluation result;

and the initial structural parameter determining module is used for taking the current structural parameter as the initial structural parameter of the piston pin when the first evaluation result meets the first design requirement.

12. A computer device, comprising:

A memory and a processor in communication with each other, the memory having stored therein computer instructions which, upon execution, perform the wrist pin design method of any one of claims 1 to 10.

13. A computer-readable storage medium, characterized in that the computer-readable storage medium has stored thereon computer instructions for causing a computer to execute the piston pin design method according to any one of claims 1 to 10.