Piston capable of reducing clearance and compressor

Abstract

The invention provides a piston capable of reducing clearance and a compressor, relates to the field of compressors, and aims to solve the problem that the compressor performance is low due to the fact that the clearance of the existing compressor is large, a raised head is in a circular truncated cone shape without partial structures, it can be guaranteed that the raised head has enough proportion in an exhaust hole to reduce the clearance, interference with other piston components can be avoided, and the reliability of the compressor is improved. The ratio of the diameter of the bottom face, corresponding to the circular truncated cone shape, of the protruding head to the diameter of the end face of the top of the piston is 0.2-0.3, and by reasonably setting the ratio, it is guaranteed that the size of the protruding head is large enough to effectively reduce the clearance, and meanwhile the situation that the overall structure and performance of the piston are affected due to the too large diameter of the protruding head is avoided; the draft angle of the raised head is 12-18 degrees, and the large draft angle is beneficial for solving the problems that after the height of the raised head is increased, the end portion is not easy to form, and the edge of the upper end is prone to material shortage.

Description

Technical Field

[0001] The present invention relates to the field of compressors, and particularly to a piston and a compressor for reducing clearance. Background Art

[0002] The clearance of a compressor (also known as clearance volume) refers to the volume of the remaining gas in the cylinder when the piston moves to the top dead center. It has a significant impact on the performance, efficiency, and reliability of the compressor. The high-pressure gas in the clearance will expand during the return stroke of the piston, occupying part of the cylinder volume, resulting in a reduction in the amount of fresh gas inhaled and a decrease in the actual exhaust volume. The clearance gas will consume energy during the expansion and recompression processes, leading to a decrease in effective power and an increase in energy consumption. If the clearance is too large, resulting in insufficient exhaust volume and reduced volumetric efficiency, it is necessary to increase the rotational speed or extend the operating time to meet the demand, indirectly increasing energy consumption. When the clearance of the compressor is too large, the gas pressure fluctuation intensifies, which may cause vibration and noise, affecting the stability of the equipment. The clearance gas absorbs heat when expanding, which may reduce the cylinder temperature. However, if the clearance is too large, repeated compression / expansion will cause local overheating. When the volumetric efficiency decreases, a higher compression ratio is required to reach the target pressure, resulting in an increase in the exhaust temperature and increasing the burden on the cooling system.

[0003] A convex head is provided on the top end face of the compressor piston. When discharging the refrigerant in the cylinder, the convex head can extend into the exhaust hole of the valve plate, reducing the space in the exhaust hole and achieving the effect of reducing the clearance. The convex head of the existing compressor piston is relatively small, especially the height is relatively small. After cooperating with the valve plate, the clearance is relatively large, resulting in low gas transmission efficiency and low performance of the compressor. If the size of the exhaust hole on the valve plate that cooperates with the convex head is directly reduced, the outlet pressure of the valve port will increase, causing a decrease in suction efficiency and performance. Although thinning the valve plate can also reduce the clearance, it will cause a decrease in the strength of the valve plate, resulting in deformation of the exhaust hole and flatness error of the exhaust hole plane, leading to leakage of the compressor.

[0004] In the prior art, there is a method of increasing the size of the piston convex head in equal proportion, so that the height, diameter, and volume of the convex head increase simultaneously, increasing the proportion of the convex head in the exhaust hole to reduce the clearance. After the height of the convex head increases, it is easy to cause the end of the convex head to be difficult to form, and the upper edge of the convex platform is prone to material shortage, resulting in an increase in the clearance, low gas transmission efficiency, and low performance of the compressor. In addition, after the surface lacks material, impurities are easily adsorbed on the surface. During the operation of the compressor, the impurities fall on the valve port, causing the valve sheet of the compressor to break and reducing the reliability of the compressor. Summary of the Invention

[0005] The object of the present invention is to provide a piston and a compressor with reduced clearance to address the defects existing in the prior art. Aiming at the problem that the large clearance of the current compressor leads to low compressor performance, the convex head adopts a truncated cone shape with some structures removed. This can not only ensure that the convex head has a sufficient proportion in the exhaust hole to reduce the clearance, but also avoid interference with other piston components, increase the draft angle, and reduce the occurrence of material shortage phenomenon, thereby ensuring that the clearance will not increase due to material shortage, and improving the gas transmission efficiency and compressor performance.

[0006] The first object of the present invention is to provide a piston with reduced clearance, adopting the following scheme:

[0007] It includes a convex head located at the top end face of the piston and a skirt located at the bottom end face of the piston. The convex head is in the shape of a truncated cone with some structures removed. The removed part is used to avoid the area where the skirt of another piston distributed coaxially abuts against the top end face of this piston. The ratio of the bottom diameter of the corresponding truncated cone of the convex head to the diameter of the top end face of the piston is 0.2 - 0.3, the draft angle of the convex head is 12° - 18°, the skirt protrudes from the bottom end face of the piston, and the draft angle of the skirt is 6° - 8°. Along the axial direction of the piston, the axial height of the skirt is greater than the axial height of the convex head.

[0008] Furthermore, the convex head is eccentrically arranged on the top end face of the piston, and the removed part is located on the side of the convex head on the top end face of the piston radially close to the outer edge.

[0009] Furthermore, the removed part forms a section surface for avoiding the skirt on one side of the convex head, and the section surface is a plane or a curved surface.

[0010] Furthermore, along the axial direction of the piston, the axial height of the convex head is 1.1 mm - 1.3 mm, and the axial height of the skirt is 1.2 mm - 1.4 mm.

[0011] Furthermore, the axial height of the convex head is 1.2 mm, the axial height of the skirt is 1.3 mm, and the bottom diameter of the corresponding truncated cone of the convex head is 4.5 mm.

[0012] Furthermore, skirts are respectively arranged on both sides of the axis of the bottom end face of the piston, and the skirts are arc-shaped protrusions distributed around the axis of the bottom end face of the piston.

[0013] Furthermore, the width of one end of the skirt connecting the bottom end face of the piston along the radial direction is 1.2 mm - 1.3 mm.

[0014] Furthermore, the draft angle of the skirt is 7°. When the top and bottom of adjacent pistons abut against each other, there is a gap between the skirt and the convex head during the rotation of the skirt around the piston axis.

[0015] The second object of the present invention is to provide a compressor that utilizes the piston with reduced clearance as in the first object.

[0016] Further, it also includes a valve plate, and an exhaust hole for the convex head to penetrate is provided on the valve plate.

[0017] Compared with the prior art, the advantages and positive effects of the present invention are as follows:

[0018] Aiming at the problem that the current compressor has a large clearance volume, resulting in low compressor performance, the convex head is in the shape of a frustum with a part of its structure removed. This can not only ensure that the convex head has a sufficient proportion in the exhaust hole to reduce the clearance volume, but also avoid interference with other piston components. The ratio of the bottom diameter of the frustum corresponding to the convex head to the diameter of the piston top end face is 0.2 - 0.3. By reasonably setting this ratio, while ensuring that the volume of the convex head is large enough to effectively reduce the clearance volume, it also avoids affecting the overall structure and performance of the piston due to an overly large diameter of the convex head. The draft angle of the convex head is 12° - 18°. The relatively large draft angle helps to solve the problems that it is difficult to form the end part after the height of the convex head increases and there is easy material shortage at the upper edge, enabling the convex head to be formed smoothly, reducing the occurrence of material shortage phenomena, thereby ensuring that the clearance volume will not increase due to material shortage, improving the gas transmission efficiency and compressor performance. At the same time, it also reduces the risk of valve plate fracture caused by impurity adsorption due to surface material shortage, improving the reliability of the compressor. Along the piston axis, the axial height of the skirt is greater than the axial height of the convex head. This height design can avoid interference during piston honing. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The specification drawings forming a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention.

[0020] Figure 1 It is a schematic diagram of the clearance volume distribution position of the compressor in one or more embodiments of the present invention.

[0021] Figure 2 It is a schematic diagram of the piston in one or more embodiments of the present invention.

[0022] Figure 3 It is a schematic diagram of the skirt on the piston in one or more embodiments of the present invention.

[0023] Figure 4 It is a schematic diagram of the convex head on the piston in one or more embodiments of the present invention.

[0024] Figure 5 It is a schematic diagram of the skirt and the convex head avoiding each other during honing of two pistons in one or more embodiments of the present invention.

[0025] Among them, 1, clearance volume; 2, convex head; 3, valve plate; 4, piston; 5, skirt; 6, piston top end face; 7, removed part. DETAILED DESCRIPTION OF THE INVENTION

[0026] Embodiment 1

[0027] In a typical embodiment of the present invention, Figures 1-5 As shown, a piston with reduced clearance is provided.

[0028] like Figure 1 As shown, the size of the convex head 2 of the piston 4 of the existing compressor is small, especially the height is insufficient. After matching with the valve plate 3, the volume of the clearance 1 is large, which causes the high-pressure gas in the clearance 1 to expand when the piston 4 returns, occupying the cylinder volume, reducing the fresh gas inhaled, and the actual exhaust volume decreases. The gas transmission efficiency is low and the compressor performance is poor. Moreover, if the size of the exhaust hole of the valve plate 3 is directly reduced or the valve plate 3 is thinned to reduce the clearance 1, it will cause problems such as increased valve port outlet pressure, reduced suction efficiency, reduced valve plate 3 strength, deformation of the exhaust hole and flatness error, resulting in compressor leakage. In the prior art, attempts are made to reduce the clearance 1 by increasing the size of the convex head 2 of the piston 4 in equal proportions, but after the height of the convex head 2 is increased, the end is not easy to form, and the upper edge is prone to material shortage, which will not only increase the clearance 1 again, reduce the gas transmission efficiency and compressor performance, but also absorb impurities due to surface material shortage. Impurities fall on the valve port and cause the compressor valve plate to break, reducing the reliability of the compressor. Based on this, this embodiment provides a piston with reduced clearance, which can reduce the clearance 1 of the compressor while meeting the honing requirements by optimizing the size and structure of the boss 2 and the skirt 5, thereby achieving the purpose of improving the compressor performance.

[0029] like Figure 2 As shown, the main body of the piston for reducing the clearance is the piston 4, the end facing the valve plate 3 is the top of the piston 4, and the end facing the crankshaft is the bottom of the piston 4. Correspondingly, the boss 2 is distributed on the top end surface 6 of the piston, and the skirt 5 is distributed on the bottom end surface of the piston 4.

[0030] like Figure 4 As shown, the convex head 2 is in the shape of a truncated cone with the structure of the portion 7 removed. When the piston 4 is honed, a plurality of pistons 4 are arranged in sequence along the axial direction, such as Figure 5 As shown, during the honing process, the piston 4 will rotate. In order to enable each piston 4 to rotate independently, the distribution position of the protrusion 2 is made to avoid the skirt 5 of the adjacent piston 4. Specifically, the removed portion 7 is used to avoid the area where the skirt 5 of another coaxially distributed piston 4 abuts against the top end face 6 of the piston. This can ensure that the protrusion 2 has enough space in the exhaust hole to reduce the clearance 1, and avoid interference with other piston 4 parts.

[0031] The ratio of the bottom diameter of the truncated cone of the protrusion 2 to the diameter of the piston top end face 6 is 0.2-0.3. By setting this ratio reasonably, while ensuring that the volume of the protrusion 2 is large enough to effectively reduce the clearance 1, the overall structure and performance of the piston 4 are not affected by the excessive diameter of the protrusion 2.

[0032] Increase the draft angle. The draft angle of the convex head 2 is 12° - 18°. A larger draft angle helps to solve the problems that the end part is not easy to form after the height of the convex head 2 increases and the upper edge is prone to material shortage, enables the convex head 2 to be formed smoothly, reduces the occurrence of material shortage, thereby ensuring that the clearance 1 will not increase due to material shortage, improving the gas transmission efficiency and the performance of the compressor. At the same time, it also reduces the risk of valve plate fracture caused by impurity adsorption due to surface material shortage, and improves the reliability of the compressor.

[0033] For the skirt 5 structure, as Figure 2 , Figure 3 shown, the skirt 5 protrudes from the bottom end face of the piston 4. The protruding design of the skirt 5 enables it to better cooperate with other components during the movement of the piston 4, ensuring the normal operation of the piston 4. Compared with the 10° draft angle of the traditional skirt 5, in this embodiment, the draft angle of the skirt 5 is reduced to 6° - 8°, ensuring the overall radial thickness of the skirt 5 and facilitating the processing and forming of the skirt 5 while ensuring the strength of the skirt 5.

[0034] Axially along the piston 4, the axial height of the skirt 5 is greater than the axial height of the convex head 2, as Figure 5 shown, to avoid interference during the honing of the piston 4, ensure the smooth processing of the semi-finished product of the piston 4, and enable this structure to be widely applied in part production and compressor assembly in large quantities.

[0035] In this embodiment, by adjusting the parameters of the convex head 2 and the skirt 5 to reduce the clearance 1, improve the gas transmission efficiency and the performance of the compressor. By optimizing the structure and size of the convex head 2 and increasing the proportion of the convex head 2 in the exhaust hole, the volume of the clearance 1 is effectively reduced. The reduction of the clearance 1 reduces the occupation of the cylinder volume by the expansion of the high-pressure gas in the clearance 1, increases the intake of fresh gas, improves the actual exhaust volume, enhances the gas transmission efficiency, and also improves the performance of the compressor.

[0036] Moreover, the convex head 2 adopts a larger draft angle, solving the problems that the end part is not easy to form and the upper edge is prone to material shortage after the height increases. It reduces the material shortage phenomenon, avoids the increase of the clearance 1 and the reduction of the gas transmission efficiency caused by material shortage, and at the same time reduces the possibility of surface impurity adsorption, reduces the risk of impurity falling on the valve port and causing valve plate fracture, and improves the reliability of the compressor.

[0037] The axial height of the skirt 5 is greater than that of the convex head 2, and the draft angle is reasonably set, solving the honing interference problem caused by the increase in size of the convex head 2, enabling the piston 4 to be smoothly processed into semi-finished products, facilitating the large-scale production and application of the piston 4 with this structure, reducing the production cost, and improving the production efficiency.

[0038] Specifically, in this embodiment, the diameter of the piston 4 is 22.5 mm. The structure of the convex head 2 is enlarged compared to the convex head 2 at the end of the traditional piston 4. The ratio of the diameter of the convex head 2 to the diameter of the top end face 6 of the piston is 0.2 - 0.3. The diameter range of the convex head 2 corresponding to the bottom of the frustum is 4.5 mm - 6.75 mm, which is at least 1.5 mm more than the 3 mm diameter of the traditional convex head 2. The draft angle is 15° ± 3°, which is at least 4° more than the 8° draft angle of the traditional convex head 2. Along the axial direction of the piston 4, the height of the convex head 2 is 1.2 mm ± 0.1 mm, which is at least 0.3 mm higher than the 0.8 mm height of the traditional convex head 2, reducing the clearance 1 by 20% - 30%.

[0039] The convex head 2 is eccentrically arranged on the top end face 6 of the piston, and the removed part 7 is located on the side radially close to the outer edge. When multiple pistons 4 are assembled coaxially, the skirt 5 of the adjacent piston 4 needs to abut against the current top end face 6 of the piston. The eccentric arrangement and the removed part 7 on the outer edge side can accurately avoid the abutting area of the skirt 5 of another piston 4, avoiding mechanical interference during assembly. After the convex head 2 is eccentric, its force distribution is more uniform, which can reduce the running vibration of the piston 4 caused by the center of gravity shift, and at the same time avoid the convex head 2 being too close to the center of the piston 4 and affecting the overall strength of the top end face.

[0040] The cut surface formed by the removed part 7 on one side of the convex head 2 can be a plane or a curved surface. The plane cut surface has a simple processing technology, which is convenient for the mold design during powder metallurgy forming, can quickly achieve mass production, and is suitable for scenarios with moderate surface accuracy requirements. The curved surface cut surface can optimize the air flow channel, reduce the resistance of the refrigerant during the exhaust process, and at the same time the curved surface transition can reduce the stress concentration and improve the fatigue resistance of the edge of the convex head 2, which is suitable for compressors operating at high loads.

[0041] The axial height of the convex head 2 is 1.1 mm - 1.3 mm, and the skirt 5 is 1.2 mm - 1.4 mm. Taking the axial height of the convex head 2 as 1.2 mm and the axial height of the skirt 5 as 1.3 mm as an example for analysis:

[0042] The height of the convex head 2 is increased by 50% compared to the prior art (traditional 0.8 mm), which can significantly penetrate into the exhaust hole of the valve plate 3, reducing the clearance 1 by 20% - 30%. And the height of the skirt 5 is only 0.1 mm higher than that of the convex head 2. It can avoid interference through the height difference during honing and will not increase the overall weight of the piston 4 due to the excessive height of the skirt 5, affecting the operating efficiency of the compressor.

[0043] Such as Figure 3As shown, the skirt portion 5 is a circular arc protrusion, and the width of the bottom connection end is 1.2 mm - 1.3 mm, which is 20% - 30% greater than that of the prior art (traditional 1 mm). The circular arc structure can evenly disperse the abutting force during assembly and avoid stress concentration. After the width is increased, the contact area between the skirt portion 5 and the adjacent piston top end face 6 increases, the support stiffness is improved, and the swing of the piston 4 during operation can be effectively suppressed. When the radial width of the bottom surface of the skirt portion 5 is within 1.3 mm, it is not easy to have material shortage during powder metallurgy forming, and it is also convenient to control the accuracy of subsequent honing processing.

[0044] The draft angle of the skirt portion 5 is set to 7°, which is smaller than 15° of the convex head 2. The reason is that the skirt portion 5 is a support structure at the bottom of the piston 4, and a smaller draft angle can ensure its wall thickness. For example, when the bottom width is 1.2 mm, the top width corresponding to a 7° draft angle is about 1.18 mm, and the wall thickness difference is only 0.02 mm, avoiding the upper part being narrow and the lower part being wide of the skirt portion 5 due to too large an angle and affecting the overall strength.

[0045] Moreover, the draft angle of the skirt portion 5 can also be used to form an assembly clearance control. When the adjacent pistons 4 are in contact at the top and bottom, there is a clearance between the skirt portion 5 and the convex head 2 during the rotation of the skirt portion 5 around the axis of the piston 4. Specifically, when the adjacent pistons 4 are in contact, a gradually changing clearance will be formed between the skirt portion 5 with a 7° draft angle and the convex head 2, which can prevent frictional interference.

[0046] In this embodiment, the axial height of the convex head 2 is 1.2 mm, the axial height of the skirt portion 5 is 1.3 mm, the bottom diameter of the convex head 2 corresponding to the frustum shape is 4.5 mm, the draft angle of the skirt portion 5 is 7°, the axial height of the skirt portion 5 is 1.3 mm, and the draft angle of the skirt portion 5 is 7°. This reduces the clearance 1 by 20% - 30%.

[0047] Embodiment 2

[0048] In another typical embodiment of the present invention, as Figures 1-5 shown, a compressor is given, which uses the piston for reducing the clearance as in Embodiment 1.

[0049] A compressor, the core of which is to use the piston for reducing the clearance as in Embodiment 1, further includes a valve plate 3. An exhaust hole for the convex head 2 to penetrate is opened on the valve plate 3, which reduces the clearance 1 by 20% - 30% and improves the compressor efficiency.

[0050] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A piston for reducing clearance, characterized in that, It includes a convex head located at the top end face of the piston and a skirt located at the bottom end face of the piston. The convex head is a truncated cone shape with some structures removed. The removed part is used to avoid the area where the skirt of another piston distributed coaxially abuts against the top end face of this piston. The ratio of the bottom diameter of the truncated cone corresponding to the convex head to the diameter of the top end face of the piston is 0.2 - 0.3, and the draft angle of the convex head is 12° - 18°. The skirt protrudes from the bottom end face of the piston, and the draft angle of the skirt is 6° - 8°. Along the axial direction of the piston, the axial height of the skirt is greater than the axial height of the convex head.

2. The piston for reducing the clearance according to claim 1, characterized in that, The convex head is eccentrically arranged on the top end face of the piston, and the removed part is located on the side of the top end face of the piston where the convex head is radially close to the outer edge.

3. The piston for reducing the clearance according to claim 2, characterized in that, The removed part forms a cut surface for avoiding the skirt on one side of the convex head, and the cut surface is a plane or a curved surface.

4. The piston for reducing the clearance according to claim 1, characterized in that, Along the axial direction of the piston, the axial height of the convex head is 1.1 mm - 1.3 mm, and the axial height of the skirt is 1.2 mm - 1.4 mm.

5. The piston for reducing the clearance according to claim 4, characterized in that, The axial height of the convex head is 1.2 mm, the axial height of the skirt is 1.3 mm, and the bottom diameter of the truncated cone corresponding to the convex head is 4.5 mm.

6. The piston for reducing clearance according to claim 1, characterized in that, Skirts are respectively arranged on both sides of the axis of the bottom end face of the piston, and the skirts are arc-shaped protrusions distributed around the axis of the bottom end face of the piston.

7. The piston for reducing the clearance according to claim 6, wherein The width along the radial direction of one end of the skirt connecting the bottom end face of the piston is 1.2 mm - 1.3 mm.

8. The piston with reduced clearance as claimed in claim 7, wherein The draft angle of the skirt is 7°. When the top and bottom of adjacent pistons abut against each other, there is a gap between the skirt and the convex head during the rotation of the skirt around the axis of the piston.

9. A compressor, characterized in that, Use the piston for reducing the clearance as described in any one of claims 1 - 8.

10. The compressor according to claim 9, wherein, It further includes a valve plate, and an exhaust hole for the convex head to penetrate is provided on the valve plate.

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