Crankshaft and rotary compressor

Abstract

The present invention provides a crankshaft and a rotary compressor, wherein the crankshaft includes an eccentric portion protruding in the radial direction and eccentrically arranged with respect to its own central axis; the eccentric portion has an oil groove and a groove recessed inwardly in the outer wall along its own radial direction; the crankshaft is used to rotate around its own central axis in a predetermined rotation direction, and the groove is used to extend from the oil groove and along the predetermined rotation direction. The present invention can reduce the contact area between the eccentric portion and the piston by providing the groove as described above, and the groove extends from the oil groove and along the predetermined rotation direction, so that the groove corresponds to the direction of the gas resultant force during the intake stage and the beginning of compression of the rotary compressor, and the groove faces away from the direction of the gas resultant force when the rotary compressor completes gas compression and during the exhaust stage, so that the gap between the eccentric portion and the piston is large enough, thereby reducing the viscous resistance of the oil film and improving the performance of the rotary compressor.

Description

Technical Field

[0001] The present invention relates to the technical field of compressors, and in particular to a crankshaft and a rotary compressor. Background Art

[0002] In the prior art, the outer surface of the eccentric portion of the crankshaft and the inner surface of the piston form a pair of friction pairs. During the operation of the rotary compressor, friction loss will occur between the two, and the magnitude of the friction loss is related to the contact area between the two. In order to reduce the friction loss of the above-mentioned friction pair, it is necessary to reduce the contact area between the eccentric portion and the piston within a reasonable range. When the rotary compressor is in operation, the crankshaft drives the piston to rotate. When the piston rotates through the cylinder, the gas in the closed crescent cavity begins to compress. When the pressure rises, as the crankshaft angle increases, the eccentric portion of the crankshaft undergoes a process from light load (the compressor intake stage and when the gas begins to be compressed) to heavy load (the completion of the gas compression and exhaust stage).

[0003] Therefore, how to reduce the contact area between the eccentric portion of the crankshaft and the piston to reduce the friction loss between the two and improve the performance of the rotary compressor is an urgent problem to be solved. Summary of the Invention

[0004] The object of the present invention is to provide a crankshaft and a rotary compressor to solve the problem in the prior art that there is a large friction loss between the eccentric portion of the crankshaft and the piston, which affects the performance of the compressor.

[0005] In order to solve the above technical problems, based on one aspect of the present invention, the present invention provides a crankshaft, which is applied to a rotary compressor, the crankshaft including an eccentric portion protruding in the radial direction and eccentrically arranged with respect to its own central axis; the eccentric portion has an oil groove and a groove recessed inwardly in the outer wall along its own radial direction, and the groove passes through the eccentric portion along the axial direction of the eccentric portion; the crankshaft is used to rotate around its own central axis in a predetermined rotation direction, and the groove is used to extend from the oil groove and along the predetermined rotation direction.

[0006] Optionally, the groove is connected to the oil tank.

[0007] Optionally, the ratio of the circumferential dimension of the groove along the eccentric portion to the circumferential dimension of the eccentric portion is an opening angle, and the ratio of the opening angle to the eccentricity of the eccentric portion with respect to the crankshaft is between 0.2 and 0.4.

[0008] Optionally, a ratio of a depth of the groove recessed radially inwardly along the eccentric portion to a radial dimension of the eccentric portion is between 0.02 and 0.03.

[0009] Optionally, the ratio of the circumferential dimension of the groove along the eccentric portion to the circumferential dimension of the eccentric portion is an opening angle, and the product of the opening angle and the depth of the groove concave inward along the radial direction of the eccentric portion is between 0.2 and 0.5.

[0010] Optionally, a ratio of a circumferential dimension of the groove along the eccentric portion to a circumferential dimension of the eccentric portion is an opening angle, and the opening angle is between 70° and 90°.

[0011] Optionally, the crankshaft includes two eccentric portions, and the two eccentric portions are arranged at intervals along the axial direction of the crankshaft.

[0012] Optionally, the crankshaft includes a long axis portion and a short axis portion, the eccentric portion is located between the long axis portion and the short axis portion, and the long axis portion and the short axis portion are arranged along the central axis of the crankshaft.

[0013] Optionally, the projections of the outer contour of the long axis portion and the outer contour of the eccentric portion on the same plane along the axial direction of the crankshaft have a first intersection point and a second intersection point, the first intersection point and the second intersection point are adjacent to each other in sequence along the predetermined rotation direction, and the oil groove is located at a position on the outer wall of the eccentric portion corresponding to the second intersection point.

[0014] According to another aspect of the present invention, the present invention further provides a rotary compressor comprising the crankshaft as described above.

[0015] In summary, in the crankshaft and rotary compressor provided by the present invention, the crankshaft includes an eccentric portion that protrudes radially and is eccentrically arranged with respect to its own central axis; the eccentric portion has an oil groove and a groove that are recessed radially inwardly in the outer wall; the crankshaft is used to rotate around its own central axis in a predetermined rotation direction, and the groove is used to extend from the oil groove and along the predetermined rotation direction. The present invention can reduce the contact area between the eccentric portion and the piston by providing the groove as described above, and the groove extends from the oil groove and along the predetermined rotation direction, so that the groove corresponds to the direction of the gas resultant force during the intake stage and the beginning stage of compression of the rotary compressor, and the groove faces away from the direction of the gas resultant force when the rotary compressor completes gas compression and during the exhaust stage, so that the gap between the eccentric portion and the piston is large enough, thereby reducing the viscous resistance of the oil film and improving the performance of the rotary compressor. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Those skilled in the art will appreciate that the accompanying drawings are provided for a better understanding of the present invention and do not constitute any limitation on the scope of the present invention.

[0017] Figure 1 is a schematic diagram of a crankshaft according to an embodiment of the present invention;

[0018] Figure 2 is a bottom view of a crankshaft according to an embodiment of the present invention;

[0019] Figure 3 is a top view of a crankshaft according to an embodiment of the present invention;

[0020] Figure 4 is an axial cross-sectional view of a crankshaft according to an embodiment of the present invention;

[0021] Figure 5 It is a graph showing the relationship between the gas force load on the crankshaft and the crankshaft angle during the crankshaft rotation;

[0022] Figure 6 This is a simulation diagram of a crankshaft lubrication model according to an embodiment of the present invention;

[0023] Figure 7 This is a comparison chart of the refrigeration capacity of the rotary compressor of the present invention and the rotary compressor of the prior art;

[0024] Figure 8 is a comparison chart of the input power of the rotary compressor of the present invention and the rotary compressor of the prior art;

[0025] Figure 9 It is a comparison chart of the performance coefficient of the rotary compressor of the present invention and the rotary compressor of the prior art.

[0026] In the attached figure:

[0027] 10-eccentric portion; 11-oil groove; 12-groove; 20-major axis portion; 30-minor axis portion; α-opening angle; R-radial dimension of the eccentric portion; T-deepness of the recess; e-eccentricity. DETAILED DESCRIPTION

[0028] To make the objects, advantages, and features of the present invention more clearly apparent, the present invention is further described below in conjunction with the accompanying drawings and specific embodiments. It should be noted that the drawings are all in a very simplified form and are not drawn to scale. They are only used to conveniently and clearly assist in illustrating the purposes of the embodiments of the present invention. In addition, the structures shown in the drawings are often part of the actual structure. In particular, different drawings may need to illustrate different focuses and sometimes use different scales.

[0029] As used in the present invention, the singular forms "a", "an", and "the" include plural referents, the term "or" is generally used to include "and / or", the term "several" is generally used to include "at least one", and the term "at least two" is generally used to include "two or more". In addition, the terms "first", "second", and "third" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features specified as "first", "second", and "third" may explicitly or implicitly include one or at least two of the features, "one end" and "the other end" and "proximal end" and "distal end" generally refer to two corresponding parts, which not only include endpoints, and the terms "mounted", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be a communication between two elements or an interaction relationship between two elements. In addition, as used in the present invention, "one element is disposed on another element" generally only indicates that there is a connection, coupling, cooperation, or transmission relationship between the two elements, and the connection, coupling, cooperation, or transmission between the two elements may be direct or indirect through an intermediate element. It should not be understood as indicating or implying a spatial positional relationship between the two elements. That is, one element can be in any orientation, such as inside, outside, above, below, or to one side of another element, unless the content clearly indicates otherwise. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0030] The present invention provides a crankshaft and a rotary compressor to solve the problem in the prior art that the eccentric portion of the crankshaft and the piston have large friction losses, thereby affecting the performance of the compressor.

[0031] The crankshaft of this embodiment will be described below with reference to the accompanying drawings.

[0032] like Figures 1 to 3 As shown, Figure 1 is a schematic diagram of a crankshaft according to an embodiment of the present invention, Figure 2 1 is a bottom view of a crankshaft according to an embodiment of the present invention. Figure 3It is a top view of a crankshaft of an embodiment of the present invention. This embodiment provides a crankshaft, which is applied to a rotary compressor, and the crankshaft includes an eccentric portion 10 that protrudes radially and is eccentrically arranged with respect to its own central axis, that is, the central axis of the eccentric portion 10 has a gap with the central axis of the crankshaft itself; the eccentric portion 10 has an oil groove 11 (that is, a groove for oil transportation in the prior art, which also includes an oil hole) and a groove 12 that are recessed radially inwardly in the outer wall. In this embodiment, the groove 12 can penetrate the eccentric portion 10 along the axial direction of the eccentric portion 10 (that is, the groove 12 penetrates both sides of the eccentric portion 10 along its own axial direction). Of course, the groove 12 can also not penetrate the eccentric portion 10 along the axial direction of the eccentric portion 10, or the groove 12 only penetrates one side of the eccentric portion 10 along its own axial direction; the crankshaft is used to rotate around its own central axis in a predetermined rotation direction, and the groove 12 is used to extend from the oil groove 11 (which can be understood as taking the oil groove 11 as the starting point) and along the predetermined rotation direction. Furthermore, the crankshaft includes a long axis portion 20 and a short axis portion 30, the eccentric portion 10 is located between the long axis portion 20 and the short axis portion 30, and the long axis portion 20 and the short axis portion 30 are arranged along the central axis of the crankshaft. It should be noted that the predetermined rotation direction here is viewed from the long axis to the short axis ( Figure 3 As shown), the crankshaft rotates counterclockwise, and when viewed from the direction of the minor axis to the major axis ( Figure 2 As shown), the crankshaft rotates in a clockwise direction. Optionally, the projections of the outer contour of the long axis portion 20 and the outer contour of the eccentric portion 10 on the same plane along the axial direction of the crankshaft have a first intersection point and a second intersection point, and the first intersection point and the second intersection point are adjacent in sequence along the predetermined rotation direction. The oil groove 11 is located at a position on the outer wall of the eccentric portion 10 corresponding to the second intersection point, which can be understood as a circle formed by the projection of the long axis portion 20 and a circle formed by the projection of the eccentric portion 10. The positional relationship of the two circles is that they intersect, and the second intersection point of the two circles according to the predetermined rotation direction of the crankshaft is the projection position corresponding to the oil groove 11 (in practice, roughly at the position of the second intersection point). It should be noted that Figure 2 The reference numeral 11 in the figure actually refers to the oil hole in the oil tank ( Figure 2 Here, looking upward, the position of the oil groove can be considered to be the position of the oil hole, so the figure numeral 11 can be used to represent the oil groove.

[0033] When the rotary compressor is running, the crankshaft drives the piston to rotate. When the piston rotates through the cylinder, the gas in the crescent cavity of the closed cylinder begins to be compressed, and the pressure gradually increases. As the crankshaft angle increases, the eccentric part 10 of the crankshaft experiences a process from light load (compressor suction stage and start of gas compression) to heavy load (completion of gas compression and exhaust stage). For details, please refer to Figure 5 , Figure 5This is a relationship diagram between the gas force load on the crankshaft and the crankshaft angle during crankshaft rotation. As the crankshaft angle increases, after rotating to 120°, the gas resultant force (gas force load) on the eccentric part 10 of the crankshaft will gradually increase. When the crankshaft angle is about 220°, the gas force load on the eccentric part 10 reaches its maximum, and then gradually decreases with the increase of the crankshaft angle. When it reaches 360°, the crankshaft rotates one circle. According to the state of the eccentric part 10 of the crankshaft during operation and the force analysis of the crankshaft (light load stage and heavy load stage), by configuring the crankshaft as above, when the compressor is working during rotation, the eccentric part 10 drives the piston matched with its bearing to rotate. During the intake stage and the beginning of compression of the rotary compressor (collectively referred to as the light load stage, which can be understood as the 0°~120° stage in the figure), the groove 12 corresponds to the direction of the resultant force of the gas. When the rotary compressor completes gas compression and the exhaust stage (collectively referred to as the heavy load stage, which can be understood as the 120° to 360° stage in the figure), the groove 12 is away from the direction of the resultant force of the gas, so that the gap between the eccentric part 10 and the piston is large enough, thereby reducing the viscous resistance of the oil film and improving the performance of the rotary compressor.

[0034] In this embodiment, the groove 12 is connected to the oil groove 11. Of course, in other embodiments, the groove 12 and the oil groove 11 may not be connected, but the groove 12 is as close to the oil groove 11 as possible. In addition, the oil groove 11 can be crescent-shaped, elliptical, or square, and the present invention is not limited to this.

[0035] Optionally, the ratio of the circumferential dimension of the groove 12 along the eccentric portion 10 to the circumferential dimension of the eccentric portion 10 is an opening angle α, and the opening angle α is between 70° and 90°, that is, the opening angle α is the degree of the fan formed by the groove 12 and the center of the eccentric portion 10.

[0036] like Figure 6 As shown, Figure 6 This is a simulation diagram of the shaft lubrication model of the crankshaft according to an embodiment of the present invention. The applicant obtained the calculation results shown in Table 1 after performing shaft lubrication model simulation calculation on the crankshaft according to this embodiment.

[0037] Table 1 Simulation calculation results of crankshaft lubrication model

[0038]

[0039] In Table 1, "mass production" refers to the crankshaft in the prior art (i.e., the crankshaft that does not adopt the groove 12 scheme). Figure 6It can be seen that when the opening angle α (the difference between the end angle and the starting angle) is 80°, the minimum oil film thickness is reduced to 1.4 μm, and the combined roughness of the crankshaft eccentric portion 10 and the piston inner surface is approximately Ra = 0.25 μm. In other words, the minimum oil film thickness is greater than 4 times the combined roughness. According to the principle of the Stribeck curve, the eccentric portion 10 is in the hydrodynamic lubrication stage at this time, and it can be considered that the lubrication state at this time still meets practical requirements. Therefore, the preferred opening angle α in this embodiment is 80°.

[0040] Optionally, the ratio of the circumferential dimension of the groove 12 along the eccentric portion 10 (the length of the groove 12 along the circumference of the eccentric portion 10) to the circumferential dimension of the eccentric portion 10 (the circumference of the eccentric portion 10) is an opening angle α, and the ratio of the opening angle α to the eccentricity e of the eccentric portion 10 with respect to the crankshaft is between 0.2 and 0.4 (i.e., not less than 0.2 and not more than 0.4). Figure 4 As shown, Figure 4 This is an axial cross-sectional view of a crankshaft according to an embodiment of the present invention. The eccentricity e of the crankshaft is defined as the distance between the central axis of the eccentric portion 10 and the central axis of the crankshaft. It should be noted that the ratios herein omit the units, retaining only the numerical values. In practice, the eccentricity e is expressed in mm, and the angle α is converted to radians (e.g., if the angle α is 80°, it is converted to 4π / 9).

[0041] Please continue reading Figure 2 and Figure 3 Optionally, the ratio of the depth of the groove 12 recessed radially inwardly along the eccentric portion 10 (hereinafter referred to as the recess depth T) to the radial dimension R of the eccentric portion is between 0.02 and 0.03 (i.e., not less than 0.02 and not more than 0.03). It is understood that the radial dimension here refers to the distance from the center to the outer periphery of the eccentric portion 10. When the eccentric portion 10 is circular, the radial dimension is the radius of the eccentric portion 10.

[0042] Optionally, the ratio of the circumferential dimension of the groove 12 along the eccentric portion 10 to the circumferential dimension of the eccentric portion 10 is an opening angle α, and the product of the opening angle α and the depth of the radial inward depression of the groove 12 along the eccentric portion 10 (depression depth T) is between 0.2 and 0.5 (i.e., not less than 0.2 and not more than 0.5). It should be noted that the ratio here also omits the unit, retaining only the numerical value. In practice, the unit of the eccentricity e is "mm", and the unit of the opening angle α is converted to radians (for example, if the opening angle α is 80°, it is converted to 4π / 9).

[0043] At the same time, the applicant has discovered that if the recessed depth T of the groove 12 is too small, the effect of reducing the viscous resistance of the oil film will be affected. If the recessed depth T of the groove 12 is too large, the eccentric portion 10 will require more pumping oil to meet the demand. Generally speaking, the recessed depth T of the groove 12 is not less than 0.2 mm, which can reduce the viscous resistance of the oil film to a relatively optimal value, thereby improving the performance of the compressor. At the same time, considering the rigidity of the crankshaft, the recessed depth T of the groove 12 should not exceed 0.3 mm. Therefore, in this embodiment, the recessed depth T of the groove 12 is between 0.2 mm and 0.3 mm.

[0044] Optionally, the crankshaft may include two eccentric portions 10, which are spaced apart along the axial direction of the crankshaft. The crankshaft of this embodiment may be provided with two eccentric portions 10 for use in a rotary compressor with dual-pressure cylinders.

[0045] Based on the above crankshaft, this embodiment further provides a rotary compressor, which includes the above crankshaft. It is understandable that since the rotary compressor includes the above crankshaft, the rotary compressor also has the beneficial effects brought by the crankshaft. This embodiment focuses on explaining the technical effects brought by the crankshaft to the rotary compressor, and does not further explain the working principle and other structural components of the rotary compressor. Those skilled in the art can learn about them based on the existing technology.

[0046] Further, see Figures 7 to 9 ,in, Figure 7 This is a comparison chart of the refrigeration capacity of the rotary compressor of the present invention and the rotary compressor of the prior art. Figure 8 This is a comparison chart of the input power of the rotary compressor of the present invention and the rotary compressor of the prior art. Figure 9 This is a comparison chart of the performance coefficients of the rotary compressor of the present invention and the rotary compressor of the prior art. The applicant has found through experiments that the cooling capacity, required input power and performance of the first rotary compressor (defined in this embodiment as a rotary compressor that does not use a crankshaft with grooves 12, which can be considered as a rotary compressor of the prior art, i.e., the "base" in the figure) and the second rotary compressor (defined in this article as a rotary compressor that uses a crankshaft with grooves 12, i.e., the "groove solution" in the figure) under the same working conditions are significantly different. Specifically, please refer to Figure 7 , for the comparison of cooling power (i.e., cooling capacity) between the first rotary compressor and the second rotary compressor, under working condition 1 or working condition 2, the cooling capacity of the second rotary compressor is significantly higher than that of the first rotary compressor; please refer to Figure 8, with respect to the input power comparison between the first rotary compressor and the second rotary compressor (i.e., the required input power comparison), under working condition 1 or working condition 2, the input power required by the second rotary compressor mechanism is significantly lower than that required by the first rotary compressor; please refer to Figure 9 Comparing the COP (COP represents the coefficient of performance of compressor refrigeration, which is equal to the ratio of cooling capacity to input power, which can be considered as the ratio of "cooling power" to "input power") of the first rotary compressor and the second rotary compressor, the refrigeration performance of the second rotary compressor is significantly improved compared with the refrigeration performance of the first rotary compressor.

[0047] In summary, in the crankshaft and rotary compressor provided by the present invention, the crankshaft includes an eccentric portion that protrudes radially and is eccentrically arranged with respect to its own central axis; the eccentric portion has an oil groove and a groove that are recessed radially inwardly in the outer wall; the crankshaft is used to rotate around its own central axis in a predetermined rotation direction, and the groove is used to extend from the oil groove and along the predetermined rotation direction. The present invention can reduce the contact area between the eccentric portion and the piston by providing the groove as described above, and the groove extends from the oil groove and along the predetermined rotation direction, so that the groove corresponds to the direction of the gas resultant force during the intake stage and the beginning stage of compression of the rotary compressor, and the groove faces away from the direction of the gas resultant force when the rotary compressor completes gas compression and during the exhaust stage, so that the gap between the eccentric portion and the piston is large enough, thereby reducing the viscous resistance of the oil film and improving the performance of the rotary compressor.

[0048] The above description is only a description of the preferred embodiment of the present invention and does not limit the scope of the present invention. Any changes and modifications made by ordinary technicians in the field of the present invention based on the above disclosure are within the scope of protection of the technical solution of the present invention.

Claims

1. A crankshaft, used in a rotary compressor, characterized in that: The crankshaft includes an eccentric portion protruding in the radial direction and eccentrically disposed with respect to its central axis; the eccentric portion has an oil groove and a groove recessed radially inwardly into an outer wall thereof; the crankshaft is configured to rotate about its central axis in a predetermined rotational direction, and the groove is configured to extend from the oil groove in the predetermined rotational direction; In which, the ratio of the circumferential dimension of the groove along the eccentric portion to the circumferential dimension of the eccentric portion is an opening angle, the ratio of the opening angle to the eccentricity of the eccentric portion with respect to the crankshaft is between 0.2 and 0.4, the product of the opening angle and the depth of the radial inward depression of the groove along the eccentric portion is between 0.2 and 0.5, and the ratio of the depth of the radial inward depression of the groove along the eccentric portion to the radial dimension of the eccentric portion is between 0.02 and 0.03; the unit of the eccentricity is millimeter, the unit of the depth of the groove is millimeter, the opening angle is between 70° and 90°, and the unit of the opening angle is converted into radians.

2. The crankshaft according to claim 1, characterized in that The groove is communicated with the oil groove.

3. The crankshaft according to claim 1, characterized in that The groove is recessed radially inwardly of the eccentric portion to a depth between 0.2 mm and 0.3 mm.

4. The crankshaft according to claim 1, characterized in that The crankshaft includes two eccentric portions, which are arranged at intervals along the axial direction of the crankshaft.

5. The crankshaft according to claim 1, characterized in that The crankshaft includes a long axis portion and a short axis portion, the eccentric portion is located between the long axis portion and the short axis portion, and the long axis portion and the short axis portion are arranged along the central axis of the crankshaft.

6. The crankshaft according to claim 5, characterized in that The projections of the outer contour of the long axis portion and the outer contour of the eccentric portion on the same plane along the axial direction of the crankshaft have a first intersection point and a second intersection point, the first intersection point and the second intersection point are adjacent to each other in sequence along the predetermined rotation direction, and the oil groove is located at a position on the outer wall of the eccentric portion corresponding to the second intersection point.

7. A rotary compressor, characterized in that: Comprising the crankshaft according to any one of claims 1 to 6.

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