A combined piston body for an ultrahigh pressure compressor

Abstract

The utility model relates to a kind of combined piston body for ultrahigh pressure compressor, including first piston body, second piston body, third piston body;First piston body and second piston body, third piston body are fixedly connected by connecting piece, to be combined as a whole piston structure;First piston body and second piston body, third piston body are made of different density materials, and by respectively adjusting the size of first piston body and the size of second piston body, third piston body respectively, the overall piston structure is kept while adjusting overall weight The shape size is fixed.The beneficial effects achieved by the utility model are: effectively and reasonably reduce weight, high structural strength and wear-resistant, and flexible assembly is convenient to use, and can accurately match weight.

Description

Technical Field

[0001] This utility model relates to the field of compressor piston assembly technology, and in particular to a combined piston body for an ultra-high pressure compressor. Background Technology

[0002] In recent years, my country's high-pressure gas compressor market has been booming, while ultra-high pressure compressors are widely used in petroleum refining, chemical production and natural gas liquefaction. With the development and progress of related technologies, ultra-high pressure compressors have also shown potential in emerging fields such as hydrogen energy storage and carbon capture and storage.

[0003] Currently, for high-pressure reciprocating compressors, the piston is the main core component of the compressor's movement. The crankshaft and piston are connected by connecting rods, which converts the circular rotation of the crankshaft into the reciprocating linear motion of the piston, realizing the intake, compression, and exhaust of the cylinder. In large reciprocating compressors with a pressure of 50-70 MPa, multiple stages and rows are required to generate ultra-high pressure exhaust pressure. These compressors have high-pressure stage pistons and low-pressure stage pistons. When designing the pistons, the inertial force of the pistons during reciprocating motion must be considered. In order to ensure the stability and balance of the pistons during the movement of each stage and row, the weight of the pistons in each row of the crankshaft crankshaft must be balanced.

[0004] Currently, some existing piston body structures use cast aluminum or aluminum alloy materials to reduce weight. Aluminum alloy is relatively lightweight, which helps reduce energy consumption during compressor operation, so it is widely used in low-pressure equipment. However, aluminum alloy pistons have a high coefficient of thermal expansion, which easily expands at high temperatures, thus accelerating the wear of the cylinder and piston and reducing the service life of the engine and piston. Therefore, they cannot be used in high-pressure piston bodies. Others use split hollow structure casting or welding piston bodies to improve strength and set weight relief holes on the piston body to reduce weight. However, the weight reduction of weight relief holes is limited, and when applied to symmetrical crankshafts, it is not possible to achieve good weight distribution.

[0005] Therefore, in order to meet the requirements of current ultra-high pressure or high pressure piston compressors, the inventors made further improvements based on the identified defects and shortcomings to overcome the above problems. Utility Model Content

[0006] The purpose of this invention is to overcome the shortcomings of the prior art and provide a combined piston body for ultra-high pressure compressors that is structurally strong and wear-resistant, flexibly assembled and easy to use, and precisely counterweighted.

[0007] The objective of this utility model is achieved through the following technical solution: a combined piston body for an ultra-high pressure compressor, comprising a first piston body, a second piston body, and a third piston body; The first piston body is fixedly connected to the second and third piston bodies through a connector, thereby forming a complete piston structure. The first piston body, the second piston body, and the third piston body are all made of materials with different densities. By adjusting the size of the first piston body, the second piston body, and the third piston body respectively, the weight of the overall piston structure is adjusted while keeping the overall external dimensions of the piston structure fixed.

[0008] As a preferred technical solution of this application, the first piston body has an I-shaped structure.

[0009] As a preferred technical solution of this application, the second piston body and the third piston body are respectively disposed at both ends of the first piston body as counterweights.

[0010] As a preferred technical solution of this application, the connecting member is a positioning pin. The first piston body, the second piston body, and the third piston body are all provided with corresponding pin holes. The three piston bodies are fixed and positioned by multiple positioning pins.

[0011] As a preferred technical solution of this application, O-rings are provided on the contact surfaces of the first piston body, the second piston body, and the third piston body, so as to seal and position the piston structure.

[0012] As a preferred technical solution of this application, the first piston body used in the low-pressure stage is made of a material with a lower density than the second and third piston bodies; while the first piston body used in the high-pressure stage is made of a material with a higher density than the second and third piston bodies.

[0013] As a preferred technical solution of this application, when used in a low-pressure stage, the material of the first piston body is cast aluminum or aluminum alloy, and the materials of the second and third piston bodies are forged steel.

[0014] As a preferred technical solution of this application, when used in a high-pressure stage, the first piston body is made of forged steel, and the second and third piston bodies are made of cast aluminum or aluminum alloy.

[0015] This utility model has the following advantages: (1) The current traditional piston is generally a one-piece structure made of a single material. Its weight and material are fixed and cannot be flexibly adjusted. If the weight difference on the symmetrical crank is too large, changing the weight requires redesign or adding a weight-reducing hole, which is inconvenient and will damage the structural strength of the piston itself. In contrast, the piston body in this solution adopts an I-shaped main structure and a split counterweight block. By changing 2 / 3 of the size of the piston body, the total weight can be adjusted under a fixed shape. It is precise, adjustable and very flexible. (2) Existing pistons made of a single material, such as all-aluminum pistons, are not strong enough, while all-steel pistons are too heavy and have high inertial forces. Therefore, this solution combines cast aluminum / alloy aluminum and cast steel to meet the different needs of high and low pressure machines. In the low-pressure stage, aluminum is used as the main structural material to achieve lightweighting; while in the high-pressure stage, cast steel is used as the main material to ensure strength. (3) The overall weight of the combined piston in this scheme is reduced, making it more stable and rapid when the compressor starts and stops, which helps to improve the response speed and working efficiency; and the lighter piston puts less pressure on the cylinder wall, thereby reducing friction and wear, extending the service life of the piston and cylinder. In addition, the lighter piston allows the compressor to run at a higher speed without worrying about excessive mechanical stress, thus improving the compressor's production capacity. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the high-pressure stage combined piston body of this utility model; Figure 2 This is a schematic diagram of the low-pressure stage combined piston body of this utility model; In the diagram: 1-First piston body, 2-Second piston body, 3-Third piston body, 4-Positioning pin, 5-O-ring seal, 6-Piston rod, 7-Nut. Detailed Implementation

[0017] The present invention will be further described below with reference to the accompanying drawings, but the scope of protection of the present invention is not limited to the following description.

[0018] It should be noted that the orientation or positional relationship indicated by terms such as "left" and "right" is based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship that the product of this invention is usually placed in during use, or the orientation or positional relationship that is commonly understood by those skilled in the art. Such terms are only for the convenience of describing this utility model and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0019] It should be noted that, unless otherwise specified, the embodiments and features and technical solutions in the present invention can be combined with each other.

[0020] It should be noted that the multi-stage and multi-row mentioned in this solution refers to multiple systems consisting of crankshaft-connecting rod-piston mechanisms. Multi-stage refers to the number of times the gas is compressed or expanded in the compressor. Each compression of the gas is considered a stage. Since a single compressor will cause the temperature to rise sharply and the efficiency to drop if the compression ratio is too high, it is necessary to divide the entire compression process into several stages (i.e., multi-stage) and cool the gas between stages to improve efficiency and reliability. Multiple rows refer to the number of cylinders arranged in a row. Each independent cylinder-piston mechanism is called a row. To increase the total displacement or power of the machine, or to balance the forces, multiple cylinders are arranged in parallel. Each row has a piston and connecting rod, but they are connected to different cranks on the same crankshaft.

[0021] Low-pressure stage pistons are mainly used for the initial compression of low-pressure gases. Therefore, in order to draw in a sufficient volume of gas, they require a large cylinder and piston diameter. Because of their large size, low-pressure stage pistons are relatively heavy. High-pressure stage pistons, on the other hand, are mainly used to further compress the initially compressed gas to an extremely high pressure level. Their piston volume is relatively small and their weight is relatively light.

[0022] It should also be noted that the symmetrical cranks in this scheme are two cranks on the crankshaft that are 180 degrees apart. Each crank is connected to a piston-connecting rod mechanism. Two low-pressure stage pistons or two high-pressure stage pistons are connected to this pair of symmetrical cranks. The paired pistons are arranged symmetrically and move in opposite directions, which can effectively balance the inertial force and achieve stable operation of the machine body.

[0023] Therefore, during the design process, in order to ensure the stability and balance of the movement of the low-pressure stage piston assembly or the high-pressure stage piston assembly in each stage and row, the weight of the pistons in each row of crankshaft cranks must be balanced, especially the weight difference of the pistons on symmetrical rows of cranks should not exceed 1kg.

[0024] Therefore, based on the above issues, in order to simultaneously meet the lightweight requirements of the low-pressure stage piston and the high-strength requirements of the high-pressure stage piston, refer to... Figure 1 This utility model proposes a combined piston body for an ultra-high pressure compressor to solve the problem.

[0025] See Figures 1-2 The present embodiment proposes a combined piston body for an ultra-high pressure compressor, comprising a first piston body 1, a second piston body 2, and a third piston body 3, and a connecting member; Among them, see Figure 1 and Figure 2The first piston body 1 has a piston rod 6 mounting hole at its center for inserting and mounting the piston rod 6. The first piston body 1 has an I-shaped structure. The first piston body 1 is fixedly connected to the second piston body 2 and the third piston body 3 by connectors and is combined into an integral piston structure (i.e., the first piston body 1 is the main piston body, and the second piston body 2 and the third piston body 3 are counterweights of the first piston body 1). The three piston bodies are made of materials with different densities. In the low-pressure stage piston, the first piston body 1 is made of a material with a lower density than the second piston body 2 and the third piston body 3. In the high-pressure stage piston, the first piston body 1 is made of a material with a higher density than the second piston body 2 and the third piston body 3.

[0026] Currently, even pistons manufactured in the same batch can have varying actual weights. To ensure the stability and balance of the movement of low-pressure or high-pressure piston assemblies across their respective stages and columns, the weight of pistons in each column of the crankshaft crank must be balanced. In particular, the weight difference between pistons on symmetrical cranks should not exceed 1 kg. Therefore, for paired low-pressure or high-pressure piston assemblies, weight adjustment is necessary. However, weight reduction methods such as "weight removal holes" can compromise structural strength and have limited adjustment range. Therefore, this solution proposes a combined piston body for ultra-high-pressure compressors. By using a split-type combined piston body structure and different density materials for each piston part to work together, and given a fixed overall piston dimension, the total weight of the piston can be precisely controlled by adjusting the dimensions of each component, thus meeting the balance requirements of symmetrical cranks.

[0027] In this embodiment, see Figure 2 The low-pressure stage combined piston includes a first piston body 1, a second piston body 2, and a third piston body 3. The first piston body 1 has an I-shaped structure, while the second and third piston bodies 2 and 3 are symmetrical block-shaped components, respectively tightly fitted into the I-shaped recesses of the first piston body 1. The first piston body 1 is made of cast aluminum / alloy aluminum, while the second and third piston bodies 2 and 3 are made of forged steel. The density of forged steel is higher than that of cast aluminum / alloy aluminum. The outer surfaces of these three piston bodies together form the working surface of the complete low-pressure stage combined piston. With the overall dimensions of the low-pressure stage pistons arranged at corresponding symmetrical cranks fixed, the weight difference between the second and third piston bodies 3 is adjusted to ensure it does not exceed 1 kg. When one of the symmetrically arranged low-pressure stage combined pistons is lighter, the thickness of the second and third piston bodies 2 and 3 is increased, while the thickness of the first piston body 1 is decreased; conversely, the thickness of the second and third piston bodies 2 and 3 is decreased, i.e., the thickness of the first piston body 1 is increased. Thus, the weight difference is balanced while maintaining the overall dimensions.

[0028] In this embodiment, see Figure 1The high-pressure stage combined piston includes a first piston body 1, a second piston body 2, and a third piston body 3. The first piston body 1 has an I-shaped structure, while the second and third piston bodies 3 are symmetrical block-shaped components, tightly fitted into the I-shaped recesses of the first piston body 1. The first piston body 1 is made of forged steel to withstand the enormous gas pressure and load within the high-pressure stage cylinder, ensuring the rigidity of the piston body and a low coefficient of thermal expansion. The second and third piston bodies 2 and 3 are made of cast aluminum / alloy aluminum. The density of forged steel is higher than that of cast aluminum / alloy aluminum (i.e., the density of the first piston body 1 in the high-pressure stage is greater than that of the second and third piston bodies 3). The density of the three piston bodies (2, 3, and 4) together forms the working surface of the complete high-pressure stage combined piston. The high-pressure stage pistons, positioned at corresponding symmetrical cranks, have their overall dimensions fixed. The weight difference is adjusted by changing the dimensions of the second and third piston bodies 3 to ensure it does not exceed 1 kg. When one of the symmetrically positioned high-pressure stage combined pistons is lighter, the thickness of the second piston body 2 and the third piston body 3 is reduced, while the thickness of the first piston body 1 is increased (to increase the proportion of steel material). Conversely, the thickness of the second piston body 2 and the third piston body 3 is increased. Thus, based on the premise of unchanged overall dimensions and ensuring the strength of the high-pressure stage pistons, the weight difference is balanced.

[0029] Furthermore, in the high-pressure stage and the low-pressure stage, the mating surfaces of the first piston body 1, the second piston body 2 and the third piston body 3 are connected by positioning pins 4. Corresponding pin holes are provided on the mating surfaces of each piston body. The positioning pins 4 are fitted and assembled through the pin holes, thereby ensuring the precise positioning and fixation of the three components to each other, and effectively preventing relative movement of the combined piston during operation.

[0030] Furthermore, O-rings 5 ​​are provided on the contact surfaces of the first piston body 1, the second piston body 3, and the third piston body 3 to seal and position the combined piston body. Sealing ring mounting grooves are provided on the inner contact surfaces of the second piston body 2, the third piston body 3 and the first piston body 1, and O-rings 5 ​​are installed in the mounting grooves to ensure the sealing of the tiny gaps inside the combined piston body and prevent high-pressure gas leakage.

[0031] It should be noted that the piston rod 6 is installed in the piston rod 6 mounting hole inside the first piston body 1, and is fastened at one end of the first piston body 1 by the connecting piston rod nut 7. The nut 7 cooperates with the stepped surface of the end of the first piston body 1 to ensure the accurate axial positioning of the piston rod 6.

[0032] In large reciprocating compressors, ultra-high pressure exhaust is generated through multiple stages and rows. Therefore, the piston design must consider the inertial forces of its reciprocating motion to ensure stability and balance during movement across each stage and row. This prevents skewing due to uneven piston weight, especially since the weight difference between pistons on symmetrical crankshafts cannot exceed 1 kg. While some existing piston bodies use weight-reducing holes, this is unsuitable for symmetrical crankshafts; the weight reduction is limited but affects strength and fails to provide proper weight distribution. Therefore, this design proposes a composite piston body. In the low-pressure stage, cast aluminum or aluminum alloy is used as the main piston body, and high-density forged steel is used for the... The counterweight ensures the dynamic balance of the piston while achieving weight reduction in the low-pressure stage. In the high-pressure stage, higher-strength forged steel is used as the main load-bearing I-beam structure (main piston body), while lighter cast aluminum or alloy aluminum is used as the counterweight to offset the weight of the steel, thus achieving weight reduction. The combined piston structure in this solution organically combines materials of different densities, and is positioned by locating pin 4 and sealed by O-rings to form a whole piston. The overall weight is reduced, and its overall strength and hardness are improved due to the addition of cast steel, resulting in a larger coefficient of thermal expansion, extended service life, and adaptability to different working conditions. Under high load and high speed conditions, it can also avoid impact and wear.

[0033] Finally, it should be noted that the above description is merely a preferred embodiment of this utility model and is not intended to limit the utility model. Although the utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. A combined piston body for an ultra-high pressure compressor, characterized in that: It includes a first piston body (1), a second piston body (2), and a third piston body (3); The first piston body (1) is fixedly connected to the second piston body (2) and the third piston body (3) through a connector, thereby forming an integral piston structure; The first piston body (1), the second piston body (2), and the third piston body (3) are all made of materials with different densities. By adjusting the size of the first piston body (1), the size of the second piston body (2), and the size of the third piston body (3) are adjusted respectively, the weight of the overall piston structure is adjusted while keeping the overall piston structure's external dimensions fixed.

2. A combined piston body for an ultra-high pressure compressor according to claim 1, characterized in that: The first piston body (1) has an I-shaped structure.

3. A combined piston body for an ultra-high pressure compressor according to claim 1, characterized in that: The second piston body (2) and the third piston body (3) are respectively disposed at both ends of the first piston body (1) as counterweights.

4. A combined piston body for an ultra-high pressure compressor according to claim 1, characterized in that: The connecting component is a positioning pin (4). The first piston body (1), the second piston body (2), and the third piston body (3) are all provided with corresponding pin holes. The three piston bodies are fixed and positioned by multiple positioning pins (4).

5. A combined piston body for an ultra-high pressure compressor according to claim 2, characterized in that: The contact surfaces of the first piston body (1) with the second piston body (2) and the third piston body (3) are provided with O-ring seals (5), which are used to seal and position the piston structure.

6. A combined piston body for an ultra-high pressure compressor according to claim 5, characterized in that: The first piston body (1) used in the low-pressure stage is made of a material with a lower density than the second piston body (2) and the third piston body (3); while the first piston body (1) used in the high-pressure stage is made of a material with a higher density than the second piston body (2) and the third piston body (3).

7. A combined piston body for an ultra-high pressure compressor according to claim 6, characterized in that: When used in low-pressure stages, the first piston body (1) is made of cast aluminum or aluminum alloy, and the second piston body (2) and the third piston body (3) are made of forged steel.

8. A combined piston body for an ultra-high pressure compressor according to claim 6, characterized in that: When used in high-pressure stages, the first piston body (1) is made of forged steel, and the second piston body (2) and the third piston body (3) are made of cast aluminum or aluminum alloy.

Images