Cylinder head assembly capable of reducing diaphragm stress in starting process and preparation method of cylinder head assembly

Abstract

The invention discloses a cylinder head assembly capable of reducing diaphragm stress in the starting process and a preparation method of the cylinder head assembly. The cylinder cover is located above the cylinder body, a first concave face is formed in the bottom of the cylinder cover, a diaphragm is arranged at the bottom of the cylinder cover, an oil distribution disc provided with an oil hole is arranged between the cylinder cover and the cylinder body, the oil distribution disc is located below the diaphragm, and a second concave face is arranged at the end, opposite to the diaphragm, of the oil distribution disc. And the ratio of the maximum deflection of the diaphragm on the second concave surface to the maximum deflection of the diaphragm on the first concave surface is less than 1.3. The diaphragm has the advantages that by changing the maximum deflection of the diaphragm on the second concave surface and the first concave surface, the limitation of the deflection relation of the diaphragm at the upper dead center and the lower dead center is broken through, and the total stress of the diaphragm during diaphragm beating is reduced; and meanwhile, the diaphragm additional stress of the diaphragm near the oil distribution disc oil hole and the stress at each part of the surface of the diaphragm are more uniformly distributed, so that the service life of the diaphragm is favorably prolonged, and the stable operation of the diaphragm compressor is ensured.

Description

Technical Field

[0001] The present invention relates to the field of diaphragm compressors, and particularly to a cylinder head assembly for reducing the stress of a diaphragm during startup and a preparation method thereof. Background Art

[0002] A diaphragm compressor is a volumetric compressor with a special structure and is the highest-level compression method in the field of gas compression. It has the characteristics of a large compression ratio, good sealing performance, and the compressed gas is not contaminated by lubricating oil and other solid impurities. It is widely used in compressing and transporting various high-purity gases, precious rare gases, toxic and harmful gases, and corrosive gases. As an irreplaceable volumetric compressor, it will have a wider range of applications with the progress and development of science and technology and the continuous improvement of people's living standards.

[0003] A diaphragm compressor usually realizes the pressurization of the compressed gas by the piston rod pushing hydraulic oil. In this process, the piston rod pushes the hydraulic oil in the oil cavity, and the hydraulic oil acts on the diaphragm after passing through the oil distribution disk. The diaphragm swings back and forth in the diaphragm cavity under the action of the hydraulic oil thrust, thus completing the cyclic process of expansion, suction, compression, and exhaust. Therefore, the diaphragm is a key component of the diaphragm compressor, and its service life directly affects the reliability of the diaphragm compressor. Currently, the research on improving the service life of the diaphragm of the diaphragm compressor is relatively extensive. For example, Patent CN218325223U proposes an oil-gas pressure accompanying control device for an adjustable electronic control oil spill valve. In this device, the oil inlet of the adjustable electronic control oil spill valve is connected to the oil inlet pipeline on the oil side of the diaphragm head, the overflow port of the adjustable electronic control oil spill valve unloads, a pressure sensor is connected to the exhaust pipeline on the gas side of the diaphragm head, and the signal line of the pressure sensor is connected to the electronic control terminal of the adjustable electronic control oil spill valve to realize that the oil spill pressure in the oil cavity changes with the exhaust pressure, ensuring that the acting forces at both ends of the diaphragm are stable within a certain range, reducing the risk of diaphragm damage, and improving the diaphragm life. Another patent CN216044330U proposes an oil distribution disk structure for a diaphragm compressor. In the oil distribution disk body, a number of oil channels are formed in a circular array manner with the center of the oil cavity as the base point, and each oil channel is respectively communicated with the oil cavity; a first oil hole communicated with the oil cavity is opened on the surface of the oil distribution disk body, and a number of oil distribution holes are arranged at intervals on each oil channel. This oil distribution disk can effectively distribute the high-pressure oil evenly on the acting surface of the metal diaphragm, and at the same time, through the "cross" - shaped distribution of the oil distribution holes on the oil distribution disk, determine the flow direction distribution of the oil, so as to realize the orderly deformation of the metal diaphragm of the diaphragm compressor, and improve the reliability and life of the metal diaphragm of the diaphragm compressor.

[0004] It can be seen from the above patents that the current research on improving the life of the diaphragm is mainly focused on the pressure caused by oil pressure on the diaphragm. This requires that the oil side pressure must be established. However, in some frequent start-stop conditions, the oil side pressure cannot be established in time, causing the diaphragm to slap the concave surface of the oil distribution plate, which is called "slapping the cylinder". For example, the operating conditions of the diaphragm compressor used in hydrogenation stations are somewhat different from those of the traditional chemical industry. At present, many hydrogenation stations are often in an intermittent hydrogenation state due to the unsaturated number of hydrogenation vehicles. The diaphragm compressor is in a state of frequent start and stop. However, this frequent start and stop condition has a negative impact on the diaphragm life of the diaphragm compressor. Because in addition to the stress caused by deformation, the diaphragm also has a local stress. Therefore, during the operation of the hydrogenation station, the actual service life of the diaphragm compressor diaphragm is often lower than its theoretical service life, and even diaphragm rupture, oil leakage, etc. may occur. Therefore, further research and improvement of the diaphragm compressor is needed to increase the service life of the diaphragm and ensure the stable operation of the diaphragm compressor.

[0005] It should be understood that the above statements merely provide background technology related to the present invention and do not necessarily constitute prior art. Summary of the invention

[0006] Based on the aforementioned technical problems, the object of the present invention is to provide a cylinder head assembly and a preparation method thereof that can reduce the diaphragm stress during the startup process. The present invention breaks through the limitation of the deflection relationship of the diaphragm at the upper dead point and the lower dead point by changing the maximum deflection of the diaphragm at the second concave surface and the first concave surface, thereby reducing the total diaphragm stress when the diaphragm hits the cylinder. At the same time, the additional diaphragm stress of the diaphragm near the oil hole of the oil distribution plate and the stress distribution at various locations on the diaphragm surface are more uniform, which helps to increase the life of the diaphragm and ensure the stable operation of the diaphragm compressor.

[0007] In order to achieve the above object, the present invention is implemented by the following technical solutions:

[0008] A cylinder head assembly for reducing diaphragm stress during startup, comprising:

[0009] Cylinder body;

[0010] A cylinder head, which is located above the cylinder body, a first concave surface is formed at the bottom of the cylinder head, a diaphragm is provided at the bottom of the cylinder head, an oil distribution plate is provided between the cylinder head and the cylinder body, an oil distribution plate is provided with oil holes, the oil distribution plate is located below the diaphragm, and the oil distribution plate has a second concave surface at one end opposite to the diaphragm, and the ratio of the maximum deflection of the diaphragm at the second concave surface to the maximum deflection of the diaphragm at the first concave surface is less than 1.3;

[0011] Optionally, the maximum deflection of the diaphragm on the second concave surface is less than or equal to the maximum deflection of the diaphragm on the first concave surface.

[0012] Optionally, an air-side space is formed between the upper surface of the diaphragm and the first concave surface, and an oil-side space is formed between the lower surface of the diaphragm and the second concave surface. The area of the contour surrounded by the edge of the first concave surface is equal to the area of the contour surrounded by the edge of the second concave surface. The volume of the oil-side space is less than or equal to the volume of the air-side space;

[0013] The ratio range of the volume of the oil-side space to the volume of the air-side space is 0.8 to 1;

[0014] The ratio range of the maximum deflection of the diaphragm on the second concave surface to the maximum deflection of the diaphragm on the first concave surface is 0.8 to 1.

[0015] Optionally, the allowable stress [σ] of the material for preparing the diaphragm is greater than the total stress σtotal of the diaphragm in the state of hitting the cylinder. The total stress σtotal of the diaphragm in the state of hitting the cylinder is the sum of the stress σ1 caused by the deformation of the diaphragm and the additional stress σ2 of the diaphragm at the oil hole of the oil distribution plate.

[0016] Optionally, the cross-sectional shape of the second concave surface of the oil distribution plate is a curve composed of two tangent arcs or a single exponential function curve.

[0017] Optionally, the diameter of the oil hole of the oil distribution plate is less than 4 mm.

[0018] Optionally, the cross-sectional shape of the second concave surface of the oil distribution plate is a double exponential function curve or a multi-exponential function curve.

[0019] Optionally, the diameter of the oil hole on the oil distribution plate is greater than or equal to 4 mm and less than 8 mm.

[0020] Optionally, the diaphragm compressor to which the cylinder head assembly belongs is a diaphragm compressor for a hydrogen refueling station.

[0021] Optionally, a method for preparing a cylinder head assembly for reducing the stress of the diaphragm during the starting process, comprising:

[0022] S1. Design the profile of the second concave surface of the oil distribution plate in the existing manner, and keep the ratio of the volume of the oil-side space to the volume of the air-side space greater than 1;

[0023] S2. Based on the oil distribution plate in S1, calculate the stress of the diaphragm, and evaluate the distribution of the stress σ1 caused by the deformation of the diaphragm surface and the additional stress σ2 of the diaphragm near the oil hole of the oil distribution plate during the state of the diaphragm hitting the cylinder during the starting process;

[0024] S3. Superimpose the peak stress σ1 caused by the deformation on the diaphragm surface and the additional stress σ2 of the diaphragm at the oil hole of the oil distribution disc to obtain the total stress σtotal of the diaphragm. Furthermore, obtain the variation curve of the total stress σtotal of the diaphragm with the diaphragm radius, extract the stress amplitude at the critical point during a single startup process, and further calculate the diaphragm life N under the current deflection of the center of the oil distribution disc. f ;

[0025] S4. Judge whether the diaphragm life N calculated in S3 f meets the design requirements, that is, whether it is greater than or equal to the design life. If not, modify the profile of the second concave surface of the oil distribution disc to reduce the maximum deflection of the diaphragm from the center of the oil distribution disc, so that the maximum deflection of the diaphragm on the second concave surface is less than or equal to its maximum deflection on the first concave surface, and then repeat S2 - S3 until the diaphragm life N f meets the design requirements;

[0026] S5. Obtain the variation relationship between the center deflection corresponding to different second concave surfaces of the oil distribution disc and the diaphragm life N f through a test run, and plot the relationship curve between the diaphragm stroke and the diaphragm life N f ;

[0027] S6. Based on the diaphragm stroke of the oil distribution disc profile obtained in S4, find the corresponding point in the relationship curve between the diaphragm stroke and the diaphragm life N f obtained in S5 to get the corresponding test diaphragm life N f , and compare this test diaphragm life N f with the diaphragm life N f calculated in S3 to verify whether the theoretical value and the actual test value of the diaphragm life N f are consistent. If not, return to the S3 optimization calculation method. If consistent, enter S7;

[0028] S7. Take the diaphragm life N f calculated in S3 as the life threshold, select any point on the relationship curve between the diaphragm stroke and the diaphragm life N f where the test diaphragm life N f is greater than or equal to this life threshold to obtain the corresponding diaphragm stroke, and at the same time check whether the volume of the diaphragm cavity corresponding to this diaphragm stroke meets the minimum diaphragm cavity volume requirement. If it meets the minimum diaphragm cavity volume requirement, calculate the corresponding total stress σtotal of the diaphragm based on this diaphragm stroke;

[0029] S8. Compare the total diaphragm stress σtotal obtained in S7 with the allowable stress [σ] of the diaphragm preparation material. If σtotal < [σ], design and machine the profile of the second concave surface of the oil distribution plate according to the deflection of the center of the oil distribution plate corresponding to the diaphragm stroke at this point. If σtotal ≥ [σ], return to S7 to reselect a point with a smaller deflection of the center of the oil distribution plate.

[0030] S9. Assemble the machined oil distribution plate with the cylinder block, cylinder head, and diaphragm.

[0031] The present invention has the following advantages compared with the prior art:

[0032] In the cylinder head assembly for reducing diaphragm stress during startup and its preparation method of the present invention, the stress problem under the frequent startup and shutdown conditions of the diaphragm compressor is fully considered, so that the maximum deflection of the diaphragm on the second concave surface of the oil distribution plate can be less than or equal to its maximum deflection on the first concave surface of the cylinder head, reducing the deflection of the diaphragm at the bottom dead center during startup, so as to reduce the stress caused by deformation when the diaphragm hits the cylinder and the additional stress of the diaphragm at the oil hole of the oil distribution plate, that is, reducing the total diaphragm stress when the diaphragm hits the cylinder. At the same time, it also makes the additional stress of the diaphragm near the oil hole of the oil distribution plate and the stress distribution on the surface of the diaphragm more uniform, which helps to improve the diaphragm life and ensure the stable operation of the diaphragm compressor. In the prior art, only the diaphragm stress problem during the operation of the diaphragm compressor is considered, and no targeted design method is proposed for the frequent startup and shutdown conditions. Therefore, compared with the prior art, the present invention effectively improves the service life of the diaphragm, helps to improve the stability and reliability of the diaphragm compressor, and makes it more suitable for working conditions that require frequent startup and shutdown, such as the working conditions in hydrogen refueling stations. Because of the good service life of the diaphragm, there is no need to frequently replace the diaphragm, so it can save the maintenance cost for hydrogen refueling stations and reduce the economic losses caused by diaphragm maintenance. Description of the Drawings

[0033] Figure 1 It is a schematic diagram of a diaphragm compressor of the present invention;

[0034] Figure 2 It is a schematic diagram of a cylinder head assembly of the present invention;

[0035] Figure 3 It is a schematic diagram of an existing cylinder head assembly;

[0036] Figure 4 It is a design method of an oil distribution plate of the present invention.

[0037] Description of the Reference Numerals:

[0038] 100: Cylinder head assembly

[0039] 110: Cylinder block

[0040] 111: Cylinder liner

[0041] 120: Cylinder head

[0042] 121: First concave surface

[0043] 130: Diaphragm

[0044] 140: Oil distribution plate

[0045] 141: Second concave surface

[0046] 142: Oil hole

[0047] 200: Piston assembly

[0048] 300: Connecting rod assembly

[0049] 400: Crosshead assembly

[0050] 500: Crankshaft assembly Detailed implementation manners

[0051] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Apparently, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the scope of protection of the present invention. At the same time, the accompanying drawings of the present invention all adopt very simplified forms and all use non-precise ratios, only for the purpose of facilitating and clearly assisting in explaining the objectives of the embodiments of the present invention.

[0052] It should be noted that in this article, the terms "include", "comprise", "have" or any other variant thereof are intended to cover non-exclusive inclusion, so that a process, method, article or terminal device including a series of elements not only includes those elements but also includes other elements not expressly listed, or further includes elements inherent to such process, method, article or terminal device. Without further limitation, the elements defined by the statement "include..." or "comprise..." do not exclude the existence of additional elements in the process, method, article or terminal device including the said elements.

[0053] In the description of the present application, the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first", "second" may explicitly or implicitly include one or more of the said features.

[0054] Such as Figure 1As shown in the figure, it is a schematic diagram of a diaphragm compressor according to the present invention. The diaphragm compressor includes structural components such as a cylinder head assembly 100, a piston assembly 200, a connecting rod assembly 300, a crosshead assembly 400, and a crankshaft assembly 500. As Figure 2 shown, the cylinder head assembly 100 includes a cylinder block 110 and a cylinder head 120. The cylinder head 120 is located above the cylinder block 110. A first concave surface 121 is provided at the bottom of the cylinder head 120. A diaphragm 130 is provided at the bottom of the cylinder head 120. The diaphragm 130 is usually formed by stacking three diaphragms. An oil chamber is formed between the lower surface of the diaphragm 130 and the upper surface of the cylinder block 110. A cylinder liner 111 is assembled in the cylinder block 110. The cylinder liner 111 is provided with a piston hole. The piston rod of the piston assembly 200 is disposed in the piston hole. The first end of the piston rod is its head, which is its working part. The second end of the piston rod is its bottom, which is connected to the crosshead assembly 400. The crankshaft assembly 500 is connected to the piston rod through the connecting rod assembly 300 and the crosshead assembly 400 to drive the piston rod to perform reciprocating linear motion.

[0055] Furthermore, an oil distribution plate 140 is provided between the cylinder head 120 and the cylinder block 110. The oil distribution plate 140 is located below the diaphragm 130. One end of the oil distribution plate 140 opposite to the diaphragm 130 has a second concave surface 141. And oil holes 142, that is, through holes, are provided on the oil distribution plate 140. These oil holes 142 play a role in guiding the flow direction of the hydraulic oil, so that the oil pressure on the oil side of the diaphragm 130 is evenly distributed. Usually, the volume enclosed by the first concave surface 121 of the cylinder head 120 and the second concave surface 141 of the oil distribution plate 140 is called the diaphragm cavity space. The space enclosed by the upper surface of the diaphragm 130 and the first concave surface 121 is called the gas side space. The space enclosed by the lower surface of the diaphragm 130 and the second concave surface 141 is called the oil side space. The diaphragm compressor usually uses the method of pushing the hydraulic oil by the piston rod to increase the pressure of the compressed gas. During this process, the head of the piston rod pushes the hydraulic oil in the oil chamber. The hydraulic oil acts evenly on the diaphragm 130 after passing through the oil holes 142 of the oil distribution plate 140. The diaphragm 130 swings back and forth in the diaphragm cavity space under the action of the hydraulic oil thrust, thus completing the cyclic process of expansion, suction, compression, and exhaust.

[0056] Usually, the lower dead center of the diaphragm 130 is defined as the maximum position where the diaphragm 130 moves towards the second concave surface 141 of the oil distribution plate 140, and the upper dead center of the diaphragm 130 is defined as the maximum position where the diaphragm 130 moves towards the first concave surface 121 of the cylinder head 120. When designed according to the prior art (please refer to Figure 3), in order to prevent the diaphragm 130 from contacting the second concave surface 141 of the oil distribution plate 140 at the bottom dead center, and to avoid generating a large additional stress on the diaphragm 130 near the oil hole 142, which may cause the diaphragm 130 to be damaged prematurely during operation, the maximum deflection of the second concave surface 141 of the oil distribution plate 140 needs to be larger than the maximum deflection of the first concave surface 121 of the cylinder head 120, that is, the ratio of the volume of the oil side space to the volume of the gas side space needs to be greater than 1, generally about 1.3 to 1.5. However, a diaphragm compressor designed in this way is not suitable for working conditions that require frequent starts and stops (such as diaphragm compressors used in hydrogen filling stations). This is because when the diaphragm compressor is started, the oil side pressure has not yet been established. When the diaphragm 130 is at the bottom dead center, the hydraulic oil cannot reach the oil side space in time, and an "oil cushion" cannot be formed between the diaphragm 130 and the oil distribution plate 140 to protect the diaphragm 130. Therefore, each time the piston rod goes through a working cycle, the diaphragm 130 will hit the second concave surface 141 of the oil distribution plate 140 once, and a "cylinder hitting" phenomenon will occur. There are many oil holes 142 on the oil distribution plate 140. When the cylinder is struck, the oil holes 142 of the oil distribution plate 140 will generate large local additional stress on the diaphragm 130 in contact with it, resulting in the actual service life of the diaphragm 130 being lower than its theoretical service life. In addition, the maximum deflection of the diaphragm 130 in the oil side space is larger than that in the air side space, so the peak stress of the diaphragm 130 is larger. Under the combined effect of the two, the peak stress of the diaphragm 130 surface is large and unevenly distributed, which affects the life of the diaphragm 130.

[0057] Based on the above problems, the present invention improves the deflection of the diaphragm 130 at the bottom dead point during the startup process. Specifically, in the present invention, the ratio of the maximum deflection of the diaphragm 130 at the second concave surface 141 to the maximum deflection of the diaphragm 130 at the first concave surface 121 is less than 1.3. Furthermore, the maximum deflection of the diaphragm 130 at the second concave surface 141 can be less than or equal to the maximum deflection of the diaphragm 130 at the first concave surface 121. Compared with the prior art, the present invention reduces the deflection of the diaphragm 130 at the bottom dead point during the startup process, reduces the stress σ1 caused by the deformation of the diaphragm 130 and the additional stress σ2 of the diaphragm 130 at the oil hole 142 of the oil distribution plate 140, that is, reduces the total stress σtotal of the diaphragm 130 when the diaphragm 130 hits the cylinder, and at the same time makes the additional stress of the diaphragm 130 near the oil hole 142 of the oil distribution plate 140 and the stress distribution of each part of the surface of the diaphragm 130 more uniform, which helps to improve the life of the diaphragm 130 and ensure the stable operation of the diaphragm compressor to which the cylinder head assembly 100 belongs. The diaphragm compressor to which the cylinder head assembly 100 belongs is particularly suitable for working conditions that require frequent start and stop, such as being used in hydrogenation station operations, that is, the diaphragm compressor to which the cylinder head assembly 100 belongs is a diaphragm compressor for hydrogenation stations.

[0058] like Figure 2As shown, in this embodiment, the area of the contour formed by the edges of the first concave surface 121 of the cylinder head 120 is equal to the area of the contour formed by the edges of the second concave surface 141 of the oil distribution plate 140, and the shape dimensions of the contours of the edges of the first concave surface 121 and the second concave surface 141 are the same. To ensure that the exhaust volume remains unchanged and the volume of the gas side space remains unchanged, the maximum deflection of the diaphragm 130 on the first concave surface 121 remains unchanged, that is, the maximum deflection of the diaphragm 130 at the top dead center remains unchanged. In this embodiment, starting from the second concave surface 141 of the oil distribution plate 140, by optimizing the profile design of the second concave surface 141 of the oil distribution plate 140, the maximum deflection of the diaphragm 130 at the bottom dead center position is reduced, so that the maximum deflection of the diaphragm 130 on the second concave surface 141 is less than or equal to its maximum deflection on the first concave surface 121. In this case, when the diaphragm 130 is in the equilibrium position, the volume of the oil side space is less than or equal to the volume of the gas side space. Therefore, by reducing the maximum deflection of the diaphragm 130 on the second concave surface 141 of the oil distribution plate 140, the present invention cancels the ratio limit of the volume of the oil side space to the volume of the gas side space. While ensuring the exhaust volume, the peak stress of the diaphragm 130 during the start-up process of the diaphragm compressor (when the oil side pressure has not been established) is reduced, which helps to improve the service life of the diaphragm 130; on the other hand, this method reduces the volume of the oil side space, thereby reducing the loss of volumetric efficiency (i.e., space utilization rate) caused by the compressibility of the hydraulic oil, which helps to improve the volumetric efficiency of the oil side space.

[0059] Optionally, the ratio range of the maximum deflection of the diaphragm 130 on the second concave surface 141 to its maximum deflection on the first concave surface 121 is 0.8 - 1. Further optionally, the ratio range of the volume of the oil side space to the volume of the gas side space is 0.8 - 1. It can be understood that the ratio range of the maximum deflection of the diaphragm 130 on the second concave surface 141 to its maximum deflection on the first concave surface 121, and the ratio range of the volume of the oil side space to the volume of the gas side space are not limited to the above data. In other embodiments, they can also be other data, as long as the corresponding functions can be achieved, and the present invention does not limit this.

[0060] Furthermore, as Figure 2As shown, in this embodiment, the cross-sectional shape of the second concave surface 141 of the oil distribution disc 140 is a curve composed of two tangent arcs, that is, the second concave surface 141 is a curved surface structure, and the deflection of the diaphragm 130 is the largest at the center position of the second concave surface 141 when the diaphragm 130 beats the cylinder. Since the maximum deflection of the diaphragm 130 on the second concave surface 141 is less than or equal to its maximum deflection on the first concave surface 121, that is, compared with the prior art, the present invention reduces the deflection of the diaphragm 130 at the center position of the second concave surface 141, and the deflection of the diaphragm 130 at each radius on the second concave surface 141 will also decrease accordingly, thereby reducing the stress on the overall surface of the diaphragm 130 and making the stress distribution on the surface of the diaphragm 130 more uniform.

[0061] It can be understood that the cross-sectional shape of the second concave surface 141 of the oil distribution disc 140 is not limited to the above. In other embodiments, it can also be other shapes, and the present invention does not limit this. For example, in another embodiment, the cross-sectional shape of the second concave surface 141 of the oil distribution disc 140 is a single exponential function curve, and at this time, the stress at the center of the diaphragm 130 is relatively large. Another example is that in other embodiments, the cross-sectional shape of the second concave surface 141 of the oil distribution disc 140 can also be a double exponential function curve or a multi-exponential function curve. In practical applications, it can be selected according to requirements or based on a certain criterion. For example, when the diameter of the oil hole 142 of the oil distribution disc 140 is small (for example, when the diameter of the oil hole 142 of the oil distribution disc 140 is less than 4 mm), the additional stress σ2 near the oil hole 142 at the center of the diaphragm 130 is relatively small, and the total stress σtotal is not very large. At this time, a single exponential function curve or a curve composed of two tangent arcs can be preferentially selected. However, when the diameter of the oil hole 142 of the oil distribution disc 140 is large (for example, the diameter of the oil hole 142 of the oil distribution disc 140 can be greater than or equal to 4 mm and less than 8 mm), the additional stress σ2 near the oil hole 142 at the center of the diaphragm 130 is large, and a double exponential function curve or a multi-exponential function curve should be selected because these two types of curves move the highest stress point caused by the deformation of the diaphragm 130 from the center of the diaphragm 130 to other positions.

[0062] To ensure the service life of the diaphragm 130 used, the present invention fully considers the stress distribution of the diaphragm 130 in the state of beating the cylinder. Optionally, the allowable stress [σ] of the preparation material of the diaphragm 130 is greater than the total stress σtotal of the diaphragm 130 in the state of beating the cylinder. The total stress σtotal of the diaphragm 130 in the state of beating the cylinder is the sum of the stress σ1 caused by the deformation of the diaphragm 130 and the additional stress σ2 of the diaphragm 130 at the oil hole 142 of the oil distribution disc 140.

[0063] Based on the above principles, in the initial design, it can be designed based on the method in Figure 4 Specifically, as Figure 4As shown, a method for preparing a cylinder head assembly for reducing diaphragm stress during startup of the present invention comprises:

[0064] S1. The second concave surface 141 of the oil distribution plate 140 is designed according to a conventional / existing design method, and the ratio of the volume of the oil side space to the volume of the gas side space is kept greater than 1, generally about 1.3 to 1.5.

[0065] S2. Based on the oil distribution plate 140 of S1, the stress of the diaphragm 130 is calculated to evaluate the total stress σtotal of the diaphragm 130 in the "cylinder beating" state during the startup process, that is, the stress σ1 distribution caused by the deformation on the surface of the diaphragm 130 and the additional stress σ2 of the diaphragm 130 near the oil hole 142 of the oil distribution plate 140.

[0066] S3. Superimpose the stress peak σ1 caused by deformation on the surface of the diaphragm 130 and the additional stress σ2 of the diaphragm 130 at the oil hole 142 of the oil distribution plate 140 to obtain the total stress σtotal of the diaphragm 130, and then obtain the variation curve of the total stress σtotal of the diaphragm 130 with the radius of the diaphragm 130, extract the stress amplitude of the point with the maximum total stress σtotal (dangerous point, such as the central area of ​​the diaphragm 130 and the area close to the edge) during a startup process, and further calculate the life N of the diaphragm 130 under the current central deflection of the oil distribution plate 140 f (Calculated based on stress amplitude, etc.).

[0067] S4. Determine the life N of the diaphragm 130 calculated in S3 f Whether it meets the design requirements, that is, whether it is greater than or equal to the design life. If not, modify the second concave surface 141 of the oil distribution plate 140, reduce the maximum deflection of the diaphragm 130 to the center of the oil distribution plate 140, and make the maximum deflection of the diaphragm 130 on the second concave surface 141 less than or equal to its maximum deflection on the first concave surface 121, that is, the oil side space volume can be less than or equal to the gas side space volume, and then repeat S2-S3 until the life of the diaphragm 130 N f Meet the design requirements. Based on the above, an oil distribution plate 140 type line that meets the design requirements can be obtained.

[0068] S5. Obtain the center deflection corresponding to the second concave surface 141 of the different oil distribution plates 140 and the life span N of the diaphragm 130 through a test run. f The relationship between the change of the diaphragm 130 stroke and the diaphragm 130 life N is plotted f The relationship curve of the diaphragm 130 and the life of the diaphragm 130 under different diaphragm 130 strokes is obtained. The diaphragm 130 stroke refers to the moving distance of the center of the diaphragm 130 when the diaphragm 130 deforms from the equilibrium position to the contact with the curved surface of the second concave surface 141 of the oil distribution plate 140, that is, the maximum deflection of the center of the oil distribution plate 140.

[0069] S6, based on the stroke of the diaphragm 130 of the oil distribution plate 140 profile obtained in S4, the stroke of the diaphragm 130 obtained in S5 and the life span N of the diaphragm 130 f Find the corresponding point in the relationship curve and get the corresponding test diaphragm 130 life N f , and compare the life of this test diaphragm 130 N f The diaphragm life of 130 N calculated in S3 f Whether it is consistent, that is, verifying the life of the diaphragm 130 N f Whether the theoretical value is consistent with the actual test value. It can be understood that the consistency here means that the difference between the two is within a preset range, that is, the difference between the two is less than or equal to a first threshold value, and the first threshold value can be set according to actual conditions.

[0070] If the test diaphragm has a life of 130 N f The diaphragm life of 130 N calculated in S3 f If they are not consistent, the calculation methods in S2 and S3 are optimized. If they are consistent, the process proceeds to S7.

[0071] S7, the life span N of the diaphragm 130 calculated in S3 f As the life threshold, the stroke of the diaphragm 130 and the life of the diaphragm 130 N f Select any test diaphragm 130 life N from the relationship curve f A point greater than or equal to the life threshold is obtained, and the stroke of the diaphragm 130 corresponding to the point is obtained, and at the same time, whether the stroke volume of the diaphragm cavity corresponding to the stroke of the diaphragm 130 meets the minimum diaphragm cavity volume requirement (the diaphragm cavity stroke volume can be calculated according to the intake parameters and flow requirements in the design requirements). When the stroke volume of the diaphragm cavity corresponding to the stroke of the diaphragm 130 meets the minimum diaphragm cavity volume requirement, the corresponding total stress σtotal of the diaphragm 130 is calculated based on the stroke of the diaphragm 130. Among them, the stroke volume of the diaphragm cavity is the sum of the volume of the oil side space and the volume of the gas side space.

[0072] S8. Compare the total stress σtotal of the diaphragm 130 obtained in S7 with the allowable stress [σ] of the material of the diaphragm 130. If σtotal < [σ], the oil distribution plate 140 profile can be designed and processed according to the center deflection of the oil distribution plate 140 corresponding to the stroke of the diaphragm 130 at this point. If σtotal ≥ [σ], reselect a point with a smaller center deflection of the oil distribution plate 140. Based on the above, an oil distribution plate 140 that meets the requirements of this application can be designed, and then the processed oil distribution plate 140 is assembled with the cylinder body 110, the cylinder head 120 and the diaphragm 130 (S9). The assembled cylinder head assembly 100 can ensure the service life of the diaphragm 130 under the condition of frequent start-stop.

[0073] In summary, in the cylinder head assembly 100 and its preparation method for reducing the diaphragm stress during the starting process according to the present invention, the limitation of the deflection relationship of the diaphragm 130 at the top dead center and the bottom dead center is broken through, so that the maximum deflection of the diaphragm 130 on the second concave surface 141 is less than or equal to its maximum deflection on the first concave surface 121, that is, the deflection of the diaphragm 130 at the bottom dead center during the starting process is reduced, so as to reduce the stress σ1 caused by deformation when the diaphragm 130 hits the cylinder and the additional stress σ2 of the diaphragm 130 at the oil hole 142 of the oil distribution plate 140, that is, the total stress σtotal of the diaphragm 130 when the diaphragm 130 hits the cylinder is reduced. At the same time, the additional stress of the diaphragm 130 near the oil hole 142 of the oil distribution plate 140 and the stress distribution on the surface of the diaphragm 130 are made more uniform, which helps to improve the service life of the diaphragm 130 and ensure the stable operation of the diaphragm compressor to which the cylinder head assembly 100 belongs.

[0074] Furthermore, the present invention optimizes the profile design of the oil distribution plate 140, reduces the deflection of the diaphragm 130 at the bottom dead center during the starting process, and then changes the ratio of the gas side space to the oil side space of the diaphragm 130 at the equilibrium position. Under the condition of ensuring the exhaust volume, the peak stress when the diaphragm 130 hits the cylinder during the starting process of the diaphragm compressor (when the oil side pressure has not been established) can be reduced, which helps to improve the service life of the diaphragm 130; on the other hand, this method reduces the volume of the oil side space, and then the loss of volumetric efficiency (i.e., space utilization rate) caused by the compressibility of the hydraulic oil can be reduced, which helps to improve the volumetric efficiency of the oil side space.

[0075] Although the content of the present invention has been described in detail through the above preferred embodiments, it should be recognized that the above description should not be considered as a limitation of the present invention. After those skilled in the art read the above content, various modifications and substitutions of the present invention will be obvious. Therefore, the protection scope of the present invention should be defined by the appended claims.

Claims

1. A cylinder head assembly for reducing diaphragm stress during startup, characterized in that: Include: Cylinder body (110); A cylinder head (120) is located above the cylinder body (110), a first concave surface (121) is provided at the bottom of the cylinder head (120), a diaphragm (130) is provided at the bottom of the cylinder head (120), an oil distribution plate (140) is provided between the cylinder head (120) and the cylinder body (110), an oil hole (142) is provided on the oil distribution plate (140), the oil distribution plate (140) is located below the diaphragm (130), and the end of the oil distribution plate (140) opposite to the diaphragm (130) has a second concave surface (141), and the ratio of the maximum deflection of the diaphragm (130) on the second concave surface (141) to the maximum deflection of the diaphragm (130) on the first concave surface (121) is less than 1.

3.

2. The cylinder head assembly for reducing diaphragm stress during startup as claimed in claim 1, characterized in that: The maximum deflection of the diaphragm (130) on the second concave surface (141) is less than or equal to the maximum deflection of the diaphragm (130) on the first concave surface (121).

3. The cylinder head assembly for reducing diaphragm stress during startup as claimed in claim 1, characterized in that: An air side space is formed between the upper surface of the diaphragm (130) and the first concave surface (121), and an oil side space is formed between the lower surface of the diaphragm (130) and the second concave surface (141), the area of ​​the contour enclosed by the edge of the first concave surface (121) is equal to the area of ​​the contour enclosed by the edge of the second concave surface (141), and the volume of the oil side space is less than or equal to the volume of the air side space; The ratio of the volume of the oil side space to the volume of the gas side space is in the range of 0.8 to 1; The ratio of the maximum deflection of the diaphragm (130) on the second concave surface (141) to the maximum deflection of the diaphragm (130) on the first concave surface (121) is in the range of 0.8 to 1.

4. The cylinder head assembly for reducing diaphragm stress during startup as claimed in claim 1, characterized in that: The allowable stress [σ] of the material used to make the diaphragm (130) is greater than the total stress σtotal of the diaphragm (130) in the cylinder-slapping state. The total stress σtotal of the diaphragm (130) in the cylinder-slapping state is the sum of the stress σ1 of the diaphragm (130) caused by deformation and the additional stress σ2 of the diaphragm (130) at the oil hole (142) of the oil distribution plate (140).

5. The cylinder head assembly for reducing diaphragm stress during startup as claimed in claim 1, characterized in that: The cross-sectional shape of the second concave surface (141) of the oil distribution plate (140) is a curve composed of two tangent circular arcs or a single exponential function line.

6. The cylinder head assembly for reducing diaphragm stress during startup as claimed in claim 5, characterized in that: The diameter of the oil hole (142) of the oil distribution plate (140) is less than 4 mm.

7. The cylinder head assembly for reducing diaphragm stress during startup as claimed in claim 1, characterized in that: The cross-sectional shape of the second concave surface (141) of the oil distribution plate (140) is a double exponential function line or a multi-exponential function line.

8. The cylinder head assembly for reducing diaphragm stress during startup as claimed in claim 7, characterized in that: The diameter of the oil hole (142) on the oil distribution plate (140) is greater than or equal to 4 mm and less than 8 mm.

9. The cylinder head assembly for reducing diaphragm stress during startup as claimed in claim 1, characterized in that: The diaphragm compressor to which the cylinder head assembly (100) belongs is a diaphragm compressor for a hydrogen refueling station.

10. A method for preparing a cylinder head assembly for reducing diaphragm stress during startup as claimed in any one of claims 1 to 9, characterized in that: Include: S1. Designing the profile of the second concave surface (141) of the oil distribution plate (140) in the existing manner, so as to maintain the ratio of the volume of the oil side space to the volume of the gas side space to be greater than 1; S2, based on the oil distribution plate (140) of S1, the stress calculation of the diaphragm (130) is performed to evaluate the distribution of stress σ1 caused by deformation on the surface of the diaphragm (130) when the diaphragm (130) is in a state of hitting the cylinder during the startup process, and the additional stress σ2 of the diaphragm (130) near the oil hole (142) of the oil distribution plate (140); S3, superimposing the stress peak value σ1 caused by deformation on the surface of the diaphragm (130) and the additional stress σ2 of the diaphragm (130) at the oil hole (142) of the oil distribution plate (140), obtaining the total stress σtotal of the diaphragm (130), and then obtaining the variation curve of the total stress σtotal of the diaphragm (130) with the radius of the diaphragm (130), extracting the stress amplitude of the dangerous point during a startup process, and further calculating the life N of the diaphragm (130) under the current central deflection of the oil distribution plate (140). f ; S4. Determine the life N of the diaphragm (130) calculated in S3 f whether it meets the design requirements, that is, whether it is greater than or equal to the design life; if not, modify the second concave surface (141) of the oil distribution plate (140) to reduce the maximum deflection from the diaphragm (130) to the center of the oil distribution plate (140), so that the maximum deflection of the diaphragm (130) on the second concave surface (141) is less than or equal to its maximum deflection on the first concave surface (121), and then repeat S2-S3 until the life of the diaphragm (130) is N. f Meet design requirements; S5. Obtain the center deflection corresponding to the second concave surface (141) of different oil distribution plates (140) and the life span N of the diaphragm (130) through a test run f The relationship between the change of the diaphragm (130) and the life of the diaphragm (130) is plotted. f The relationship curve of S6, based on the stroke of the diaphragm (130) of the oil distribution plate (140) profile obtained in S4, the stroke of the diaphragm (130) obtained in S5 and the life span N of the diaphragm (130) f Find the corresponding point in the relationship curve and obtain the corresponding test diaphragm (130) life N f , and compare the life of the test diaphragm (130) N f The life span N of the diaphragm (130) calculated in S3 f Whether they are consistent, to verify the life of the diaphragm (130) N f Whether the theoretical value is consistent with the actual test value; If they are not consistent, then return to S3 to optimize the calculation method; if they are consistent, then enter S7; S7, the life span N of the diaphragm (130) calculated in S3 f As the life threshold, when the diaphragm (130) stroke and the diaphragm (130) life N f Select any test diaphragm (130) from the relationship curve and calculate the life span N f A point greater than or equal to the life threshold is obtained, and the corresponding diaphragm (130) stroke is obtained, and at the same time, whether the diaphragm cavity stroke volume corresponding to the diaphragm (130) stroke meets the minimum diaphragm cavity volume requirement; if the minimum diaphragm cavity volume requirement is met, the corresponding diaphragm (130) total stress σtotal is calculated based on the diaphragm (130) stroke; S8, comparing the total stress σtotal of the diaphragm (130) obtained in S7 with the allowable stress [σ] of the material of the diaphragm (130); if σtotal < [σ], designing the profile of the second concave surface (141) of the oil distribution plate (140) according to the central deflection of the oil distribution plate (140) corresponding to the stroke of the diaphragm (130) at this point and performing processing; if σtotal ≥ [σ], returning to S7 and reselecting a point with a smaller central deflection of the oil distribution plate (140); S9, assembling the processed oil distribution plate (140) with the cylinder body (110), the cylinder head (120) and the diaphragm (130).

Images