An automotive suspension compressor piston ring profile design method

Abstract

The present invention belongs to the field of automotive suspension air compressors, and discloses a design method for the piston ring profile of an automotive suspension compressor. The connecting rod and the piston of the automotive suspension compressor are of an integral structure, and piston rings are installed on the outer periphery of the piston. The design method for the piston ring profile includes: the design of the radial plane of the piston ring; the design of the axial thickness of the piston ring; the design of the axial curved surface of the piston ring. By optimizing the piston ring profile through the design method of the present invention, the sealing performance of the compression chamber of the automotive suspension compressor can be ensured, and the service life of the piston ring can be increased.

Description

Technical Field

[0001] The present invention belongs to the field of automotive suspension air compressors, and particularly relates to a design method for the piston ring profile of an automotive suspension compressor. Background Art

[0002] With the progress of technology and the increasing attention of countries around the world to environmental issues, new energy vehicles have become the main trend and trend in the development of automobiles in various countries, and have very broad application prospects. For new energy vehicles, the power battery is placed on the vehicle chassis. If the vehicle body is too low or passes over a roadblock, the power battery may be damaged. When driving on a bumpy road, the phenomenon of scraping the bottom may also occur. At the same time, new energy vehicles have a heavy body, making it more difficult to control the chassis.

[0003] The air suspension system is extremely compatible with new energy vehicles. The air suspension can actively adjust the height of the vehicle, thereby protecting the battery module from being damaged due to the vehicle body being too low or passing over a roadblock. When driving on a bumpy road, the vehicle's passability can be improved by lifting the body to avoid scraping the bottom. In response to the problem of the heavy body of new energy vehicles, the air suspension system can effectively improve the vehicle's stability and driving smoothness. At the same time, when the vehicle is driving at high speed, the vehicle body can be lowered to reduce the resistance of the vehicle at high speed and significantly reduce energy consumption. At the same time, the role of the air suspension can be fully exerted through the intelligence of new energy vehicles.

[0004] For automotive suspension air compressors, an important issue lies in lightweight and miniaturization. Generally, oil-free compressors are used. Lightweight can integrate the piston compressor connecting rod and the piston into one body. However, when using the original piston ring with a fixed cross-section, it is difficult to achieve sealing. At this time, the design and sealing of the compressor piston ring have become a major problem. There is an urgent need for a piston ring profile design method suitable for automotive suspension compressors. Summary of the Invention

[0005] The purpose of the present invention is to provide a design method for the piston ring profile of an automotive suspension compressor to solve the problems of poor sealing and short service life of the piston ring of an automotive suspension compressor in the prior art.

[0006] To achieve the above purpose, the present invention adopts the following technical solutions:

[0007] A design method for the piston ring profile of an automotive suspension compressor, wherein the connecting rod and the piston of the automotive suspension compressor are of an integral structure, and a piston ring is installed on the outer circumference of the piston; the piston ring profile design method includes:

[0008] Design of the radial plane of the piston ring;

[0009] Design of the axial thickness of the piston ring;

[0010] Design of the axial curved surface of the piston ring.

[0011] A further improvement of the present invention lies in that the steps of designing the radial plane of the piston ring specifically include:

[0012] The radial reference thickness α of the piston ring is determined by the following formula Standard :

[0013] α Standard = f(σ, T, ω)

[0014] Where: σ is the average distance between the piston and the cylinder; T is the average temperature during the operation of the compressor; ω is the thermal expansion coefficient of the piston ring material.

[0015] A further improvement of the present invention lies in that the steps of designing the radial plane of the piston ring further include:

[0016] The radial reference thickness α of the piston ring is modified by the piston ring radial thickness correction coefficient δ Standard to obtain the piston ring radial design thickness α:

[0017] δ = f(Fn, k)

[0018]

[0019] α = α Standard ·δ

[0020] Where: Fn is the average radial force received by the piston ring; k is the elastic coefficient of the piston ring material; r is the crank rotation radius; l is the piston rod length; is the state of the compressed gas under rated conditions; β is the piston ring radial plane angle, and Φ is the crank angle.

[0021] A further improvement of the present invention lies in that the steps of designing the axial thickness of the piston ring specifically include:

[0022] The axial thickness λ of the piston ring is determined by the following formula:

[0023] λ = f(r, l, T, ω)

[0024] Where: r is the crank rotation radius; l is the piston rod length; T is the average temperature of the cylinder during the operation of the compressor; ω is the thermal expansion coefficient of the piston ring material.

[0025] A further improvement of the present invention lies in that the steps of designing the axial curved surface of the piston ring specifically include:

[0026] Design according to the airtightness of the cylinder to obtain the piston ring reference axial curved surface equation

[0027]

[0028] Where: γ is the piston ring angle; β is the piston ring radial plane angle; α is the piston ring radial design thickness; λ is the piston ring axial thickness; θ is the piston rod swing angle; T is the average temperature of the cylinder wall during compressor operation; ω is the thermal expansion coefficient of the piston ring material.

[0029] A further improvement of the present invention lies in that: the steps of the axial curved surface design of the piston ring further include:

[0030] Using the piston ring axial curved surface correction coefficient ξ to correct the piston ring reference axial curved surface equation to obtain the piston ring axial curved surface equation

[0031] ξ = f(Fn, γ, β, k, θ)

[0032]

[0033] Where: Fn is the radial force received by the piston ring; β is the piston ring radial plane angle; k is the elastic coefficient of the piston ring material.

[0034] A further improvement of the present invention lies in that: in the automotive suspension compressor, the piston ring is fixed on the outer periphery of the piston.

[0035] A further improvement of the present invention lies in that: in the automotive suspension compressor, the piston ring is fixed on the outer periphery of the piston through the internal positioning pins; during the movement of the piston ring, it will not rotate relative to the cylinder.

[0036] Compared with the prior art, the present invention has the following beneficial effects: The present invention discloses a design method for the profile of a piston ring of an automotive suspension compressor. The connecting rod and the piston of the automotive suspension compressor are of an integrated structure, and a piston ring is installed on the outer periphery of the piston. The design method for the profile of the piston ring includes: the radial plane design of the piston ring; the axial thickness design of the piston ring; the axial curved surface design of the piston ring. Since the connecting rod and the piston are integrally designed for lightweight, the piston will swing during the operation of the compressor, and a certain angle θ is formed between the piston rod and the cylinder wall surface. This leads to a series of problems such as uneven supporting force of the piston ring by the cylinder wall surface and eccentric wear of the piston ring. In response to this, the profile design of the piston ring of this compressor is proposed, and the profile of the piston ring is designed from three aspects: the radial plane design, the axial thickness design, and the axial plane design of the piston ring. The radial plane design mainly corrects the reference design in terms of the uneven radial force distribution received by the piston ring, force and thermal deformation, elastic coefficient, etc.; the axial thickness design mainly starts from the dimensions of the crank and connecting rod of the compressor, and combines thermal deformation to enable the piston ring to better achieve system sealing; the axial plane design of the piston ring is the final step. This profile determines the meshing degree and sealing effect between the piston ring and the cylinder wall. The specific shape of the curved surface is determined by β, γ and the length r. The standard design of the curved surface is also set through parameters such as radial force, thermal deformation and the inclination angle of the piston rod. Finally, through corrections such as uneven radial force, thermal deformation and elastic coefficient, the design of the piston ring profile is realized. Since the piston ring design is uneven, a piston ring locating pin is used to locate the piston ring to prevent it from rotating. The present invention improves the sealing performance, working life and working efficiency of the piston ring of the automotive suspension compressor, also improves the performance of the system, promotes the application and popularization of the cooling system of the automotive suspension compressor, and makes significant contributions to environmental protection, alleviating the fossil energy crisis, and achieving carbon neutrality and carbon peak. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following briefly introduces the drawings required for use in the description of the embodiments or the prior art; obviously, the following drawings are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0038] Figure 1 is a schematic diagram of the operation of an automotive suspension compressor;

[0039] Figure 2 is the piston pin of the automotive suspension compressor of the present invention;

[0040] Figure 3 is the top view of the piston ring designed by the present invention;

[0041] Figure 4 is the cross-sectional view of the piston ring designed by the present invention. Detailed implementation manners

[0042] The present invention will be further described in detail below with reference to the accompanying drawings:

[0043] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the accompanying drawings. These are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation of the present invention. The terms "first", "second", "third" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance. In addition, unless otherwise clearly specified and limited, the terms "installation", "connection", "connection" should be understood in a broad sense. For example, it can be a fixed connection or a detachable connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0044] Please refer to Figure 1 As shown, the automotive suspension compressor involved in the embodiment of the present invention includes: a compressor housing 1, a compressor cylinder 2, a crank 3, a connecting rod piston 4, and a piston ring 5. The compressor housing 1 is made of a metal material. Among them, in order to achieve lightweight and miniaturized design, the connecting rod and the piston are designed as an integrated connecting rod piston 4. During the compression process, the piston will tilt, and for this, the piston ring profile needs to be designed.

[0045] One embodiment of the present invention discloses the working process of the above-mentioned automotive suspension compressor: The automotive suspension compressor is a piston compressor, and its working process includes four processes: suction, compression, exhaust, and expansion. Taking Figure 1 the position in as an example, at this time the compressor is in a compression state. Since the piston rod and the piston of this compressor are integrated, the piston will swing as the crank 3 rotates during the working process, and its specific state can be written as a relational expression about the crank 3 rotation angle Φ.

[0046] One embodiment of the present invention discloses the above-mentioned piston ring profile design method for an automotive suspension compressor: Different from traditional piston compressors, an automotive suspension compressor mentioned in the present invention has a certain angle θ between the piston 3 and the cylinder wall surface of the compressor cylinder 2 during the working process. The force between the piston ring and the cylinder wall surface and the system sealing condition are different from those of traditional compressors. First, due to the certain angle θ between the piston and the cylinder wall surface, the contact situation between the piston ring and the cylinder wall surface changes, which has a certain guiding effect on the piston ring design. At the same time, due to the existence of a certain swing acceleration and lateral force of the piston, the lateral force received by the piston ring in the plane of the swing axis of the connecting rod piston is the largest and gradually decreases with the change of the angle. In view of the eccentric wear characteristics of the piston ring, the piston ring is designed in combination with the meshing between the piston ring and the cylinder wall.

[0047] Please refer to Figure 1 As shown, a piston ring profile design method for an automotive suspension compressor proposed by the present invention includes piston ring axial plane design, axial thickness design and piston ring radial plane design; specifically includes the following steps:

[0048] Step 1: Radial plane design of the piston ring of the suspension compressor:

[0049] In the radial plane of the piston ring, due to the certain inclination angle θ between the piston ring 5 and the cylinder wall surface of the compressor cylinder 2, the lateral force is relatively obvious, and because it will swing during its working process, the distance between the piston and the cylinder is relatively large; at the same time, during the compression process, the temperature of the compressed air will rise, and the temperature of the compressor cylinder 2 will also rise, causing a certain thermal deformation of the piston ring 5. Another thing to note is that although the lateral force exists in one plane, due to the certain elasticity of the piston ring 5, the radial force of the surrounding piston rings will increase to a certain extent, as Figure 3 shown. Based on the above principle, the radial plane design of the piston ring 5 profile is as follows:

[0050] α Standard = f(σ, T, ω)

[0051] Where: α Standard is the radial reference thickness of the piston ring; σ is the average distance between the piston and the cylinder; T is the average temperature during the working process of the compressor; ω is the thermal expansion coefficient of the piston ring 5 material;

[0052] When calculating α Standard , its main criterion is to ensure that there is contact between the piston ring and the cylinder wall surface and a certain elastic force during the operation of the compressor.

[0053] The reference radial thickness α of the piston ring standardAfter determination, a certain degree of correction needs to be carried out on the radial thickness reference. The correction is mainly based on the magnitude of the radial force exerted on the piston ring 5, the temperature of the piston ring, and the elastic coefficient of the material used. Since the piston ring 5 is subjected to different radial forces from the cylinder, its wear during operation is also different. When the compressor is working, there is a certain angle between the piston ring 5 and the cylinder wall surface and it is constantly changing. The piston ring is subjected to the maximum radial force from the cylinder in the plane where it swings, and the radial force from the cylinder gradually decreases as it moves away from the plane where it swings, as shown in Figure 3 shown. Therefore, in response to this uneven wear phenomenon, a larger allowance is designed for the piston ring 5 in the place where the radial force is larger during design. While ensuring that the compressor can still operate normally after a certain period of uneven wear, it is also considered that a large radial force on the cylinder will cause large deformation, and a larger radial size of the piston ring can better ensure sealing. The correction is achieved through the radial thickness correction coefficient δ:

[0054] δ = f(Fn, k)

[0055]

[0056] α = α Standard ·δ

[0057] In the formula: δ is the radial thickness correction coefficient of the piston ring 5; Fn is the average radial force exerted on the piston ring; k is the elastic coefficient of the piston ring material; r is the rotation radius of the crank 3; l is the length of the piston rod (the length of the piston rod is the sum of the piston rod and the piston length); is the state of the compressed gas under rated conditions (the pressure and temperature of the compressed gas); β is the angle of the radial plane of the piston ring, as shown in Figure 3 shown; Φ is the crank angle; α is the radial design thickness of the piston ring;

[0058] The relationship of the correction coefficient can be determined through calculation. During calculation, the design is mainly carried out according to the condition that the shapes of all parts of the piston ring remain the same considering the deformation of the piston ring.

[0059] After correction, a certain allowance for uneven wear of the piston ring can be provided for the area with a larger radial force, and at the same time, a certain correction is given for the elastic coefficient and temperature of the material, so that the piston ring can seal better. The calculation of the radial force has been given here and will not be elaborated below. It should be noted that the value of the radial force is not the same at different positions or different times in a working cycle, and the radial force given here corresponds to the average value of the radial force during the process.

[0060] It should be noted that this design requires the use of piston ring pins to position the piston ring to prevent the surplus radial thickness set for uneven wear from rotating to other angles, resulting in abnormal operation of the piston ring and compressor failure.

[0061] Step 2: Design of the axial thickness of the compressor piston ring:

[0062] The automotive suspension compressor proposed by the present invention has an integrated design of the connecting rod and the piston, which is different from the design of the piston rings of conventional piston compressors. It has more explicit and strict design requirements for the axial thickness of the cylinder. It is necessary to consider that the piston rings still have a good sealing effect when the piston is tilted to ensure the normal operation of the compressor. The axial thickness of the piston ring is as Figure 2 shown, denoted as λ, and its calculation is as follows:

[0063] λ = f(r, l, T, ω)

[0064] In the formula: λ is the axial thickness of the piston ring; r is the crank rotation radius; l is the piston rod length; T is the average temperature of the cylinder during the operation of the compressor; ω is the thermal expansion coefficient of the piston ring material;

[0065] The above calculation mainly calculates the maximum swing angle θ max of the suspension compressor through the dimensions of the crank and the piston rod of the compressor, and θ max is the maximum value of θ during the operation of the compressor. Combining with the thermal deformation of the piston ring material, the radial thickness of the piston ring is calculated to ensure that the piston ring can complete the sealing function well for all piston rod swing angles corresponding to the current rotation radius and piston rod length.

[0066] Step 3: Design of the axial surface of the piston ring of the suspension compressor:

[0067] As Figure 1 shown, when the suspension compressor is operating, the angle between the piston plane and the cylinder surface is not 90°, but deviates by a certain θ angle. At this time, the sealing situation of the piston ring is different from that of the conventional piston compressor. It is necessary to design the axial profile of the piston ring according to different connecting rod-piston inclination angles, the force situation of the piston ring and its thermal deformation. In Step 1, the radial thickness of the piston ring has been determined, and in Step 2, the axial thickness of the piston ring has also been determined. Here, the axial surface design of the piston ring is carried out based on the above calculations. The axial surface design of the piston ring is the key to the design and an important part of whether the piston ring can complete the sealing work well. It should be noted that the radial dimensions of the piston ring corresponding to different β angles are different, and a certain margin needs to be considered for the design when carrying out the axial surface design of the piston ring. The first step is mainly to design according to the sealing performance of the cylinder:

[0068]

[0069] In the formula: is the reference axial surface equation of the piston ring; γ is the piston ring angle, as Figure 4 shown; β is the radial plane angle of the piston ring, as Figure 3 shown; α is the radial design thickness of the piston ring; λ is the axial thickness of the piston ring; θ is the swing angle of the piston rod; T is the average temperature of the cylinder wall during the operation of the compressor; ω is the thermal expansion coefficient of the piston ring material;

[0070] The above-mentioned reference curve of the piston ring is mainly determined by the average cylinder temperature T based on the lateral force Fn received by the piston ring, the swing angle θ of the piston rod, and the degree of thermal deformation. In addition, since the piston mainly swings within the plane where the crank is located, the forces and sealing requirements corresponding to different β angles are not the same, and special design is required. At the same time, as mentioned above, due to the certain angle between the piston rod and the cylinder wall, the phenomenon of eccentric wear of the piston ring is aggravated. It is necessary to thicken the piston ring at the eccentric wear area to a certain extent to ensure its service life. The axial surface of the piston ring is corrected according to the above-mentioned reference surface equation:

[0071] ξ = f(Fn, γ, β, k, θ)

[0072]

[0073] In the formula: ξ is the correction coefficient of the axial surface of the piston ring; Fn is the radial force received by the piston ring; β is the angle of the radial plane of the piston ring, as Figure 3 shown; k is the elastic coefficient of the piston ring material; is the equation of the axial surface of the piston ring;

[0074] Here, when calculating the correction coefficient, it is mainly corrected according to the design margin. Before correction, it is necessary to first check the wear condition of the piston ring under different added radial forces, fit the correction relationship according to the wear condition of the piston ring under different radial forces and working times, and then correct the profile of the piston ring in different regions.

[0075] It should be noted that the radial force here corresponds to different three-dimensional surfaces, and the piston surface at each point is corrected accordingly. Through the above correction, it can be ensured that the piston ring can better adapt to the increase in lateral force caused by piston swing and the eccentric wear of the piston ring during operation, and still achieve good sealing of the compression cavity, while improving the service life of the piston ring.

[0076] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that: still can modify the specific implementation manners of the present invention or make equivalent replacements, and any modification or equivalent replacement that does not depart from the spirit and scope of the present invention shall be covered by the protection scope of the claims of the present invention.

Claims

1. A design method for the profile of an automotive suspension compressor piston ring, characterized in that, The piston rod and the piston of the automotive suspension compressor are of an integral structure, and piston rings are installed on the outer periphery of the piston; the design method of the piston ring profile includes: Radial plane design of the piston ring; Axial thickness design of the piston ring; Axial curved surface design of the piston ring; The steps of the radial plane design of the piston ring specifically include: The radial reference thickness of the piston ring is determined by the following formula :[[]]END]] Wherein: is the average distance between the piston and the cylinder; is the average temperature during the operation of the compressor; is the coefficient of thermal expansion of the piston ring material; The steps of the radial plane design of the piston ring also include: By the piston ring radial thickness correction coefficient correct the piston ring radial reference thickness to obtain the piston ring radial design thickness : Wherein: is the average radial force received by the piston ring; is the elastic coefficient of the piston ring material; is the crank radius of rotation; is the length of the piston rod; is the state of the compressed gas under the rated working condition; is the radial plane angle of the piston ring, is the crank angle; The steps of the axial thickness design of the piston ring specifically include: Axial thickness of piston ring It is determined by the following formula: Wherein: is the crank radius of rotation; is the piston rod length; is the average temperature of the cylinder during the working process of the compressor; is the coefficient of thermal expansion of the piston ring material; The steps of the axial curved surface design of the piston ring specifically include: Design according to the airtightness of the cylinder to obtain the reference axial surface equation of the piston ring : In the formula: is the piston ring angle; is the piston ring radial plane angle; is the piston ring radial design thickness; is the piston ring axial thickness; is the piston rod swing angle; is the average temperature of the cylinder wall during compressor operation; is the thermal expansion coefficient of the piston ring material; The steps of the axial curved surface design of the piston ring also include: Adopt the piston ring axial surface correction coefficient To correct the piston ring reference axial surface equation And obtain the piston ring axial surface equation : Wherein: is the radial force received by the piston ring; is the piston ring angle; is the piston ring radial plane angle; is the elastic coefficient of the piston ring material; is the swing angle of the piston rod.

2. The method for designing the profile of an automotive suspension compressor piston ring according to claim 1, wherein In the automotive suspension compressor, the piston ring is fixed on the outer periphery of the piston.

3. A design method for the profile of an automotive suspension compressor piston ring according to claim 1, characterized in that, In the automotive suspension compressor, the piston ring is fixed on the outer periphery of the piston through the internal positioning pins; the piston ring will not rotate relative to the cylinder during the movement process.

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