Crankshaft and roller matching structure, compressor, air conditioner

Abstract

The present invention provides a crankshaft and roller matching structure, a compressor, and an air conditioner. The crankshaft and roller matching structure includes a crankshaft and a roller. The crankshaft has an eccentric portion, and the roller has an inner hole. The eccentric portion is in the inner hole and a first gap m is formed between the two. When the temperature of the matching structure rises, the outer diameter D2 of the eccentric portion after thermal expansion is smaller than the inner hole diameter D1 of the roller after thermal expansion. The present invention provides a crankshaft and roller matching structure, a compressor, and an air conditioner. When the temperature of the compressor rises, the outer diameter of the eccentric portion of the crankshaft after thermal expansion is smaller than the inner hole diameter of the roller after thermal expansion, thereby preventing the crankshaft and the roller from locking or getting stuck during the operation of the compressor.

Description

Technical Field

[0001] The invention belongs to the technical field of air conditioning, and in particular relates to a crankshaft and roller matching structure, a compressor, and an air conditioner. Background Art

[0002] The interior of the rotary compressor housing is mainly composed of two parts: the pump body assembly and the motor assembly. The pump body assembly includes a cylinder, rollers, a crankshaft, a vane, and upper and lower bearing assemblies. Each component cooperates with each other to form a closed suction and exhaust cavity. The motor assembly includes a stator assembly and a rotor assembly. The long axis end of the crankshaft of the pump body assembly is interference fit with the rotor in the motor assembly. The rotary compressor generates a driving force for the pump body to rotate the crankshaft through the electromagnetic force generated between the motor rotor assembly and the stator assembly. Under the driving action of the crankshaft rotation, the volume of the compressor suction and exhaust chambers changes continuously, thereby realizing the compressor's periodic suction, compression and exhaust process. The rotary compressor uses the eccentric part of the crankshaft to realize the periodic compression process of the airflow in the cylinder cavity. Due to the eccentric design of the crankshaft, the eccentric part of the crankshaft and the rollers that cooperate with the eccentric part of the crankshaft together constitute the unbalanced mass of the rotating parts of the compressor pump body, resulting in the imbalance of the compressor pump body structure, and then making the overall rotating part (motor rotor, pump body crankshaft, pump body roller) in an unbalanced state. In order to ensure the stable operation of the compressor, it is usually necessary to arrange main and auxiliary balance blocks with different weights at both ends of the motor rotor core to balance the imbalance of the compressor rotating parts. The larger the unbalanced mass of the rotating part of the pump body, the larger the mass of the main and auxiliary balance blocks that need to be used to balance the unbalanced mass.

[0003] With the development trend of compressor miniaturization and high speed, the compressor needs to ensure that it can maintain performance, noise and reliability at higher frequency operation while reducing series design. Among them, the miniaturization of the compressor means that the cylinder diameter is limited under the same displacement, which will inevitably lead to an increase in cylinder height and the overall height of the pump body-rotor assembly. According to the inertia moment calculation formula F = rmω 2 l. The rotational inertia moment caused by the eccentric mass increases linearly with the increase of the pump body height. According to the rotational inertia force calculation formula F = rmω 2 The high speed of the compressor causes the centrifugal force of the main and auxiliary balance blocks of the motor rotor to increase exponentially, resulting in a significant increase in the deflection of the pump crankshaft when the compressor runs at high frequency. As a result, the noise and vibration of the compressor at high frequency operation increase sharply, and the friction loss increases, resulting in a significant decline in performance, thereby further increasing the risk of many reliability problems such as wear of compressor parts and contact between the outer cylindrical surface of the motor and the inner cylindrical surface of the stator causing motor bore scraping. This has become a bottleneck problem that needs to be urgently solved in the design and development of small and high-speed compressors.

[0004] According to the above-mentioned calculation formulas for inertia force and inertia moment, it can be known that, under the premise of ensuring the high-speed operation of the compressor, when the eccentric rotation radius is constant, reducing the eccentric mass m can effectively reduce the compressor's rotational inertia force and rotational inertia moment, thereby optimizing the compressor balance system, reducing the deflection of the compressor pump crankshaft, and effectively solving or optimizing the performance and noise problems caused by the high-speed operation balance problems of the compressor, as well as compressor reliability problems such as wear of pump body parts and motor bore scraping. This is the current topic of lightweight research.

[0005] Using lightweight materials for eccentric parts is one of the important methods to reduce the eccentric mass. However, due to the different physical properties of different materials, such as thermal conductivity, specific heat capacity, thermal expansion coefficient and other thermodynamic parameters, there are great differences in the amount of deformation caused by heat. Thermal conductivity reflects the speed of heat transfer of materials. On the one hand, the inner surface of the roller in the rotary compressor pump assembly continuously absorbs heat due to frictional heat and conducts heat to the inside of the roller and its outer circumferential surface parts. On the other hand, part of its outer surface is in contact with the low-pressure and low-temperature gas in the cylinder suction chamber, and part is in contact with the high-temperature and high-pressure gas in the cylinder compression chamber. There is a temperature gradient, and the heat flow changes with the change of the temperature gradient, which is a non-equilibrium molecular thermodynamic motion process. Specific heat capacity reflects the temperature difference caused by the absorption or release of specific heat by the parts. The larger the specific heat capacity, the smaller the temperature difference. The thermal expansion coefficient reflects the deformation of the parts under a specific temperature difference. When the thermal conductivity of the roller material is very small relative to the crankshaft material that matches it, according to the heat conduction characteristics, the heat generated by the friction pair is conducted faster on the crankshaft material, and relatively slowly on the roller, so that the crankshaft heats up quickly and the roller temperature rises slowly, further resulting in a large temperature difference between the roller-crankshaft friction pair. When the thermal expansion coefficients of the two are relatively close, the thermal expansion deformation of the crankshaft is much greater than the thermal expansion deformation of the roller, thereby causing the eccentric part of the crankshaft and the roller to get stuck. When the thermal conductivity of the roller material is relatively large relative to the crankshaft material that matches it, on the contrary, the clearance between the roller and the eccentric part of the crankshaft is too large. Therefore, simply replacing the material while ignoring the deformation difference caused by its thermodynamic characteristics is very likely to cause abnormal reliability problems of the compressor such as large leakage or poor operation and jamming due to unreasonable clearance. Based on this deficiency in the research process of lightweight, small and high-speed compressor materials, it is necessary to conduct necessary research on the selection basis of the crankshaft, especially the eccentric part of the crankshaft and the roller that matches it, so as to ensure that the two do not get stuck or jammed during the operation of the compressor. Summary of the invention

[0006] Therefore, the technical problem to be solved by the present invention is to provide a crankshaft and roller matching structure, a compressor, and an air conditioner. When the temperature of the compressor rises, the outer diameter of the eccentric part of the crankshaft after thermal expansion is smaller than the inner hole diameter of the roller after thermal expansion, thereby preventing the crankshaft and the roller from locking or getting stuck during the operation of the compressor.

[0007] In order to solve the above problems, the present invention provides a crankshaft and roller matching structure, including a crankshaft and a roller, the crankshaft having an eccentric portion, the roller having an inner hole, the eccentric portion being in the inner hole and forming a first gap m therebetween, when the temperature of the matching structure rises, the outer diameter D2 of the eccentric portion after thermal expansion is smaller than the inner hole diameter D1 of the roller after thermal expansion.

[0008] Preferably, the material of the roller is a first material, the thermal conductivity of the first material is λ1, the specific heat capacity is C1, and the thermal expansion coefficient is ξ1; the material of the eccentric part is a second material, the thermal conductivity of the second material is λ2, the specific heat capacity is C2, and the thermal expansion coefficient is ξ2; the thermodynamic correlation parameter α=(C2λ1ξ1) / (C1λ2ξ2), and the first gap m is related to the α.

[0009] Preferably, when α≥1, 0.01 mm≤m≤0.03 mm.

[0010] Preferably, 0.015 mm ≤ m ≤ 0.025 mm.

[0011] Preferably, when α<1, k(1-αD1 / D2)D2ξ2<m, wherein k is the maximum temperature rise of the eccentric portion.

[0012] Preferably, 20°C≤k≤150°C.

[0013] Preferably, k(1-αD1 / D2)D2ξ2+b>m, wherein b is the upper limit constant of the gap, and the unit is mm.

[0014] Preferably, 0.01 mm ≤ b ≤ 0.03 mm.

[0015] Preferably, the first material is a lightweight material.

[0016] The present invention also provides a compressor, comprising the above-mentioned crankshaft and roller matching structure.

[0017] The present invention also provides an air conditioner, comprising the above-mentioned compressor.

[0018] The present invention provides a crankshaft and roller matching structure, a compressor, and an air conditioner. When the temperature of the compressor rises, the outer diameter of the eccentric part of the crankshaft after thermal expansion is smaller than the inner hole diameter of the roller after thermal expansion, thereby preventing the crankshaft and the roller from locking or getting stuck during the operation of the compressor. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 A schematic diagram of the internal structure of a compressor according to an embodiment of the present invention;

[0020] Figure 2 for Figure 1A partial enlarged view of the middle A;

[0021] Figure 3 The thermal deformation curves of the inner diameter of the ceramic roller and the outer diameter of the eccentric part of the ductile iron crankshaft according to a specific embodiment of the present invention are shown.

[0022] The reference numerals are as follows:

[0023] 1. Crankshaft; 11. Eccentric part; 2. Roller; 21. Inner hole. DETAILED DESCRIPTION

[0024] See also Figures 1 to 3 As shown, according to an embodiment of the present invention, a crankshaft and roller matching structure is provided, comprising a crankshaft 1 and a roller 2, wherein the crankshaft 1 has an eccentric portion 11, and the roller 2 has an inner hole 21, wherein the eccentric portion 11 is located in the inner hole 21 and a first gap m (in mm) is formed between the two. When the temperature of the matching structure rises, the outer diameter D2 (in mm) of the eccentric portion 11 after thermal expansion is smaller than the diameter D1 (in mm) of the inner hole 21 of the roller 2 after thermal expansion. In this technical solution, when the temperature of the compressor rises, the outer diameter of the eccentric portion of the crankshaft after thermal expansion is smaller than the inner hole diameter of the roller after thermal expansion, thereby preventing the occurrence of locking and jamming of the crankshaft and the roller during the operation of the compressor.

[0025] In order to achieve that the outer diameter of the crankshaft eccentric portion after thermal expansion is smaller than the diameter of the inner hole 21 after thermal expansion of the roller, preferably, the material of the roller 2 is a first material, and the thermal conductivity (unit: W / (m·℃)) of the first material is λ1, the specific heat capacity (unit: J / (kg·℃)) is C1, and the thermal expansion coefficient (unit: 10 -6 / ℃) is ξ1, the material of the eccentric portion 11 is the second material, the thermal conductivity (unit is W / (m·℃)) of the second material is λ2, the specific heat capacity (unit is J / (kg·℃)) is C2, the thermal expansion coefficient (unit is 10 -6 / ℃) is ξ2, the thermodynamic correlation parameter α=(C2λ1ξ1) / (C1λ2ξ2), the first gap m (in mm) is related to the α, and it can be understood that selecting different first materials and second materials for the materials of the roller 2 and the eccentric part 11, respectively, can facilitate the lightweight design of the roller 2. For example, the density of the first material can be selected to be greater than the density of the second material, thereby effectively reducing the rotational inertia force and rotational inertia moment of the compressor, thereby optimizing the compressor balancing system, reducing the deflection of the compressor pump crankshaft, and effectively solving or optimizing the performance and noise problems caused by the balance problem of the compressor high-speed operation, as well as compressor reliability problems such as wear of pump body parts and motor bore sweeping.

[0026] Specifically, to ensure that the roller and the eccentric part of the crankshaft are not stuck, it must satisfy: D1+ΔD1>D2+ΔD2, wherein ΔD1 (in mm) and ΔD2 (in mm) are the deformation of the inner diameter of the roller and the outer diameter of the eccentric part 11, respectively. Furthermore, m=D1-D2>ΔD2-ΔD1.

[0027] Assuming that the maximum temperature rise of roller 2 and crankshaft 1 at the fitting point when the compressor is running is ΔT1 and ΔT2 respectively, according to the thermodynamic calculation formula:

[0028] ΔD1 / ΔD2=(ΔT1D1ξ1) / (ΔT2D2ξ2)=((D1ξ1) / (D2ξ2))·(ΔT1 / ΔT2)

[0029] =((D1ξ1) / (D2ξ2))·(C2λ1) / (C1λ2)

[0030] =((C2λ1ξ1) / (C1λ2ξ2))·(D1 / D2)

[0031] Let α=(C2λ1ξ1) / (C1λ2ξ2),

[0032] Then the ratio of the roller inner diameter deformation to the crankshaft eccentric portion outer diameter deformation is: ΔD1 / ΔD2=αD1 / D2.

[0033] When α≥1,

[0034] At this time, since the ratio between the roller inner diameter D1 and the crankshaft eccentric portion outer diameter D2 is D1 / D2>1

[0035] Then ΔD1 / ΔD2>1, that is, the deformation of the inner diameter of the roller>the deformation of the outer diameter of the eccentric part of the crankshaft, and there will definitely be no locking or jamming. At this time, it is only necessary to reasonably design the matching clearance, for example, 0.01mm≤m≤0.03mm. At this time, it can be understood that when α=1, the first material and the second material can be the same material. Of course, at this time, to a certain extent, the roller 2 is not designed to be lightweight in a strict sense. Furthermore, 0.015≤m≤0.025, that is, when α≥1, by controlling the original installation clearance between the roller 2 and the eccentric part 11, it can be ensured that the gap between the two is in a reasonable range after the temperature rise. The aforementioned range can enable the normal operation of the compressor, and the clearance is not too large to cause serious leakage of the pump body and affect the energy efficiency of the compressor.

[0036] When α < 1, the most basic condition to ensure that the inner diameter of the roller and the outer diameter of the eccentric part of the crankshaft are not stuck due to deformation is:

[0037] m>ΔD2-ΔD1=ΔD2-(αD1 / D2)ΔD2=(1-αD1 / D2)ΔD2

[0038] =ΔT2(1-αD1 / D2)D2ξ2

[0039] That is, when m>ΔT2(1-αD1 / D2)D2ξ2, it can be guaranteed not to get stuck.

[0040] In order to ensure that the gap is not too large to cause leakage risk when the compressor is running, the upper limit of the gap is further limited to a certain range. Here, a constant b (in mm) is introduced, that is,

[0041] m<ΔT2(1-αD1 / D2)D2ξ2+b, 0.01≤b≤0.03;

[0042] That is, k(1-αD1 / D2)D2ξ2<m<k(1-αD1 / D2)D2ξ2+b.

[0043] From the previous formula, we can know that k represents the maximum temperature rise ΔT2 of the eccentric part of the crankshaft, which is positively correlated with the exhaust temperature when the compressor is running. The higher the exhaust temperature, the greater the local temperature rise of the friction pair parts. When the compressor is running at high frequency under heavy conditions, the maximum exhaust temperature does not exceed 150°C. Therefore, k is in the range of 20°C≤k≤150°C. When the exhaust temperature is too high, the temperature rise is relatively large, so k takes the upper limit value within the limited value range. In specific applications, for example, the material of roller 2 can be selected and determined first, and its corresponding thermodynamic parameters will be determined. At this time, the material of crankshaft 1 (when the material of eccentric part 11 is different from the material of the main shaft of crankshaft 1, the material of eccentric part 11 shall prevail) is selected and its thermodynamic parameters are determined accordingly. At this time, the size relationship between α and 1 is calculated, and then the value range of m corresponding to α≥1 and α<1 can be adopted.

[0044] Preferably, the first material is a lightweight material, and the lightweight material preferably has a density lower than that of the roller material FC300 in the prior art, such as zirconium oxide ZrO2 ceramics, aluminum oxide Al2O3, aluminum alloy, etc. Furthermore, in order to better optimize the wear characteristics of the roller-crankshaft friction pair, the crankshaft material can be made of steel material with relatively high hardness, such as 40Cr, 20Cr, etc. While improving the wear resistance of the compressor, the stiffness of the steel material is greater than that of the ductile iron (ductile iron) in the prior art, which can further reduce the high-frequency deflection of the crankshaft.

[0045] As a specific implementation method, Figure 3As shown in the figure, when ceramic roller parts are used, they are matched with conventional ductile iron crankshafts. The thermal conductivity and linear expansion coefficient of the two are shown in Table 1. From the thermal conductivity parameters of the two, it can be seen that the thermal conductivity of ceramic is much smaller than that of ductile iron, which is only 6.7% of the thermal conductivity of ductile iron. According to the thermal conduction characteristics, the heat generated by the friction pair is conducted faster on the crankshaft material, while the conduction on the roller is relatively slow, so that the crankshaft heats up quickly and the roller temperature rises slowly, which further leads to a large temperature difference between the roller and crankshaft friction pair. When the thermal expansion coefficients of the two are relatively close, the thermal expansion deformation of the crankshaft is much larger than the thermal expansion deformation of the roller. If the clearance between the roller and the crankshaft is not designed reasonably, it is very easy to cause the eccentric part of the crankshaft and the roller to get stuck.

[0046] Table 1 Thermodynamic properties of ceramic and ductile iron materials

[0047]

[0048] like Figure 3 As shown in Table 1, according to the linear expansion coefficients of ceramic and ductile iron materials, the temperature rise curves of the inner diameter of the ceramic roller and the outer diameter of the eccentric part of the ductile iron crankshaft are plotted. It can be seen that in addition to the slow temperature rise, the inner diameter of the ceramic roller increases slowly with the temperature rise (the linear expansion coefficient of ceramic is smaller than that of ductile iron). Figure 3 The three horizontal equal diameter lines shown represent the temperature corresponding to each part when the outer diameter of the crankshaft is equal to the inner diameter of the roller. It can be seen that when the local temperature of the friction surface of the ceramic roller rises to 30°C and the local temperature of the eccentric part of the crankshaft rises to about 75°C, the inner diameter of the roller will be basically close to the outer diameter of the eccentric part of the crankshaft, and there is a risk of jamming. When the local temperature of the eccentric part of the crankshaft rises to more than 80°C, it will inevitably cause the inner diameter of the roller to be larger than the outer diameter of the eccentric part of the crankshaft, causing the compressor pump body to jam. According to the inventor's theoretical calculation and experimental verification, preferably, when one of the rollers of the compressor pump body parts adopts a ceramic roller, the design gap is 28μm≤m≤55μm, and optimally, 35μm≤m≤45μm. It can be understood that the value range of the aforementioned m adopts k(1-αD1 / D2)D2ξ2<m<k(1-αD1 / D2)D2ξ2+b, and the k and b values ​​are reasonably selected.

[0049] On the one hand, the hardness of the ceramic roller is much higher than that of the existing roller material (FC300) structure, which can reduce roller wear and friction loss. On the other hand, the thermal conductivity of the ceramic roller is about 2.2W / (m.℃), which is much smaller than the thermal conductivity of the existing roller material FC300 (about 47.5mm). It has a significant thermal insulation effect, which is beneficial to improve the indication efficiency of the compressor pump body and further improve the energy efficiency of the compressor.

[0050] According to an embodiment of the present invention, there is further provided a compressor, comprising the above-mentioned crankshaft and roller matching structure, wherein the compressor may be, for example, a single-cylinder rotor compressor, or a dual-cylinder or multi-cylinder rotor compressor.

[0051] According to an embodiment of the present invention, there is also provided an air conditioner, comprising the above-mentioned compressor.

[0052] It is easy for those skilled in the art to understand that, under the premise of no conflict, the above-mentioned advantageous methods can be freely combined and superimposed.

[0053] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention shall be included in the protection scope of the present invention. The above are only preferred embodiments of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and variations can be made without departing from the technical principles of the present invention, and these improvements and variations should also be regarded as the protection scope of the present invention.

Claims

1. A crankshaft and roller matching structure, characterized in that: The invention comprises a crankshaft (1) and a roller (2), wherein the crankshaft (1) has an eccentric portion (11), and the roller (2) has an inner hole (21), the eccentric portion (11) is located in the inner hole (21) and a first gap m is formed between the two, and when the temperature of the matching structure rises, the outer diameter D2 of the eccentric portion (11) after thermal expansion is smaller than the diameter D1 of the inner hole (21) of the roller (2) after thermal expansion; the material of the roller (2) is a first material, the thermal conductivity of the first material is λ1, the specific heat capacity is C1, and the thermal expansion coefficient is ξ1, the material of the eccentric portion (11) is a second material, the thermal conductivity of the second material is λ2, the specific heat capacity is C2, and the thermal expansion coefficient is ξ2, and the thermodynamic correlation parameter α= (C2λ1ξ1) / ( C1λ2ξ2), the first gap m is related to the α; when α≥1, 0.01mm≤m≤0.03mm; when α<1, k(1-αD1 / D2)D2ξ2<m, where k is the maximum temperature rise of the eccentric part (11).

2. The matching structure according to claim 1, characterized in that: 0.015mm≤m≤0.025mm.

3. The matching structure according to claim 1, characterized in that: 20℃≤k≤150℃。 4. The matching structure according to claim 1, characterized in that: k(1-αD1 / D2)D2ξ2+b>m, where b is the upper limit constant of the gap, the unit is mm.

5. The matching structure according to claim 4, characterized in that: 0.01mm≤b≤0.03mm.

6. The matching structure according to claim 4, characterized in that: The first material is a lightweight material.

7. A compressor, comprising a crankshaft and a roller matching structure, characterized in that: The crankshaft and roller matching structure is the crankshaft and roller matching structure according to any one of claims 1 to 6.

8. An air conditioner, comprising a compressor, characterized in that: The compressor is the compressor according to claim 7.

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