A temperature regulation method for an aero-cylinder pump based on a cycloid gear

Abstract

This invention proposes a temperature control method for aviation plunger pumps based on cycloidal gears to address the temperature rise problem caused by insufficient heat dissipation. This method integrates cycloidal gears within the pump to increase the return oil flow rate, carrying away the high-temperature oil in the housing cavity and reducing the overall temperature of the aviation plunger pump. The invention divides the pump into multiple nodes and establishes temperature analysis models and thermal network equations for the control volume nodes; it establishes a pump energy loss model and analyzes the temperature of each node of the aviation plunger pump under different return oil flow rates using thermal balance equations, thereby determining the design flow rate of the cycloidal gear; it establishes the structural equations of the cycloidal gear and uses theoretical formulas and simulation analysis to analyze the influence of the cycloidal gear structural parameters on its performance; and it determines the cycloidal gear structural parameters based on the pump's size constraints. This invention uses the plunger pump thermal network model established by the lumped parameter method to determine the return oil temperature of the plunger pump under different operating conditions and achieves return oil temperature control of the aviation plunger pump through cycloidal gears.

Description

Technical Field

[0001] This invention relates to the field of heat conduction and temperature control of aerospace plunger pumps, and specifically to a method for temperature regulation of aerospace plunger pumps based on cycloidal gears. Background Technology

[0002] Axial piston pumps are positive displacement hydraulic pumps widely used in aircraft hydraulic systems, offering advantages such as high power density, high output pressure, and high efficiency. However, high-speed relative motion between the pump's internal friction pairs—such as the distributor plate and cylinder block, cylinder block and piston, and slipper and swashplate—generates frictional heat. High-pressure oil leaks through these friction pairs to low-pressure areas, leading to leakage losses and further heat generation. This accumulated oil within the housing cavity causes additional churning losses during the movement of high-speed components like the cylinder block, piston, and slipper. This heat can only be absorbed by the oil within the housing cavity and discharged through the return port or dissipated to the external environment through the housing. Compared to industrial piston pumps, aerospace piston pumps operate under high-speed, high-pressure conditions for extended periods, resulting in significant self-heating. Due to the high power density requirements of aircraft hydraulic systems, aerospace piston pumps also have a highly integrated structure, resulting in a much smaller heat dissipation area compared to industrial piston pumps. Furthermore, aerospace piston pumps operate in a high-altitude, low-pressure environment, further reducing their convective cooling capacity compared to industrial piston pumps. For the reasons mentioned above, the heat dissipation capacity of the aviation plunger pump housing is severely insufficient, and most of the heat can only be carried away by the return oil. However, hydraulic systems often have components such as oil filters and check valves on the return oil lines, which increases the back pressure in the lines and reduces the return oil flow. More heat accumulates in the housing, causing accelerated wear of the plunger pump parts, increased leakage, and a greater risk of performance and lifespan degradation.

[0003] The root cause of overheating in plunger pumps lies in the inability to effectively match the heat dissipation capacity of existing designs with the heat generated during operation. Currently, the main approach is to reduce losses and thus lower the temperature of aerospace plunger pumps by optimizing the friction pair surfaces. However, as the speed and pressure ratings of aerospace plunger pumps increase, simply reducing losses through friction pair optimization is insufficient to fundamentally solve the problem. Therefore, exploring technical solutions to improve the heat dissipation efficiency of aerospace plunger pumps is both a key focus and a challenge in enhancing their design efficiency and performance. Summary of the Invention

[0004] The purpose of this invention is to solve the problems in the prior art and propose a temperature control method for aviation plunger pumps based on cycloidal gears. This method integrates cycloidal gears inside the aviation plunger pump to force an increase in return oil flow, effectively removes heat, thereby reducing the overall temperature of the plunger pump. It also establishes an efficient thermal network model for temperature prediction and design optimization.

[0005] To achieve the above objectives, this invention proposes a method for temperature control of an aviation plunger pump based on a cycloidal gear, comprising the following steps:

[0006] Step (1): Analyze the temperature transfer path of the aircraft plunger pump, decompose the thermodynamic model of the plunger pump into multiple control volume nodes, and establish the thermal network model of the plunger pump. The thermal network model includes the temperature analysis model of each control volume node and the overall thermal network equation.

[0007] Step (2): Establish the energy loss model of the plunger pump and substitute the energy loss model into the temperature analysis model described in step (1) to analyze the temperature changes of each node of the plunger pump under different return oil flow rates.

[0008] Step (3): Establish the internal and external rotor tooth profile equations of the cycloidal gear, as well as the theoretical model of the displacement and flow pulsation of the cycloidal gear;

[0009] Step (4): Establish the CFD (Computational Fluid Dynamics) model of the cycloidal gear, combine it with the theoretical model in step (3), analyze the influence of structural parameters on displacement and flow pulsation, and determine the optimal structural parameters of the cycloidal gear by combining the structural size constraints and heat dissipation flow requirements of the plunger pump.

[0010] Step (5): Complete the machining and testing of the cycloidal gear, and integrate it into the plunger pump for experimental verification to verify the temperature control effect of the cycloidal gear on the plunger pump and the effectiveness of the plunger pump thermal network model.

[0011] Preferably, in step (1), establishing the thermal network model includes:

[0012] Based on the heat transfer path of the plunger pump, its thermodynamic model is divided into fluid nodes including suction nodes, discharge nodes, and return nodes, and solid nodes including distribution plate nodes, cylinder block nodes, plunger nodes, slipper nodes, swashplate nodes, and shell nodes. The corresponding thermal network node equations can be expressed as follows:

[0013]

[0014] In the formula, Indicates the temperature of each node; Indicates the quality of each node; This represents the specific heat capacity of each node; This indicates the thermal resistance between each node. Among the subscripts, in represents the suction node; fc represents the distribution housing node; out represents the discharge node; l represents the return node; vp represents the distribution plate node; cy represents the cylinder block node; p represents the plunger node; s represents the slipper node; sw represents the swashplate node; case represents the housing node; and am represents the ambient node. This indicates leakage losses generated by the distribution pair; This indicates leakage losses caused by the plunger assembly; This indicates leakage losses caused by the slipper pair; This represents the viscous loss generated by the distribution pair; This indicates the viscous loss caused by the plunger assembly; This indicates the viscous loss caused by the slipper pair; This indicates the stirring loss caused by the rotating component. This indicates the proportion of heat generated by leakage and viscous losses in the distribution sub-devices, as expressed by the heat transfer distribution disk nodes. This indicates the proportion of heat generated by leakage and viscous losses in the distribution pair that is transferred to the cylinder block nodes. This indicates the proportion of heat generated due to leakage losses and viscous losses in the distribution pair that is transferred to the return oil node; This indicates the proportion of heat transferred to the cylinder block nodes in the heat generated by leakage and viscous losses from the plunger assembly. This indicates the proportion of heat generated by the plunger joint due to leakage and viscous losses. This indicates the proportion of heat generated due to leakage and viscous losses in the plunger assembly that is transferred to the return oil node. This indicates the proportion of heat generated by leakage and viscous losses in the slipper assembly, at the slipper node. This indicates the proportion of heat transferred to the swashplate node in the total heat generated by leakage and viscous losses from the slipper pair. This indicates the proportion of heat generated by leakage and viscous losses in the slipper pair that is transferred to the return oil node; This indicates the percentage of heat generated by stirring that is transferred to the cylinder nodes; This indicates the proportion of heat lost due to stirring that is transferred to the plunger node; This indicates the proportion of heat lost due to stirring that is transferred to the slipper node. This indicates the proportion of heat lost due to stirring that is transferred back to the oil return node. This indicates the flow rate entering the oil suction node; This indicates the flow rate exiting from the oil discharge point; This indicates the flow rate out of the return oil node; This indicates the flow rate from the discharge point to the return point; This represents the flow rate from the suction node to the return node. It is important to note that: a. A positive sign in the equation indicates energy transfer from the node to the outside, while a negative sign indicates energy transfer from the outside to the node; b. Due to the limited leakage flow of the plunger pump, additional oil needs to be introduced from the suction node to the return node to prevent the cycloidal gear from drawing air into the system.

[0015] Preferably, in step (2), establishing the energy loss model includes: the energy loss includes viscous friction loss and leakage loss occurring in the distribution pair, plunger pair, and slipper pair, as well as stirring loss generated by the rotation of the cylinder block and plunger-slipper assembly within the housing cavity; establishing a calculation equation for the leakage loss based on gap flow theory; establishing a calculation equation for the viscous friction loss based on oil film lubrication theory; and establishing a calculation equation for the stirring loss based on rotating body resistance torque theory. This allows for a comprehensive and theoretically clear quantification of the main heat sources of the plunger pump.

[0016] The viscous loss of the distribution pair can be expressed as:

[0017]

[0018] In the formula, This represents the viscous loss generated by the distribution pair; Indicates the dynamic viscosity of the oil; This indicates the clearance between the cylinder block and the distributor plate; z indicates the number of plungers; Indicates the wrap angle of the cylinder block auxiliary support band; Indicates the inner radius of the sealing strip inside the cylinder; Indicates the outer radius of the sealing strip inside the cylinder; Indicates the inner radius of the external sealing strip of the cylinder; Indicates the outer radius of the external sealing strip of the cylinder body; Indicates the inner radius of the cylinder block auxiliary support band; Indicates the outer radius of the cylinder block auxiliary support; This indicates the wrap angle of the waist-shaped groove in the distribution plate.

[0019] The viscous loss of the plunger pair can be expressed as:

[0020]

[0021] In the formula, This indicates the viscous loss caused by the plunger assembly; This indicates the clearance between the plunger and the plunger bore; Indicates the length of the plunger in the plunger bore; R represents the plunger diameter; R represents the cylinder bore pitch radius. This indicates the swashplate tilt angle.

[0022] The viscous loss of the slipper pair can be expressed as:

[0023]

[0024] In the formula, This indicates the viscous loss caused by the slipper pair; This indicates the gap between the skate and the swashplate; Indicates the outer diameter of the sealing strip at the bottom of the slipper; This indicates the inner diameter of the sealing strip at the bottom of the slipper.

[0025] The leakage loss generated by the distribution pair is

[0026]

[0027] The leakage loss caused by the plunger pair is

[0028]

[0029] In the formula, This indicates the relative speed of the piston pump within the cylinder bore; n represents the number of pistons in the aero-pump piston pump.

[0030] The leakage loss caused by the slipper pair is

[0031]

[0032] The churning loss is mainly generated by the rotating parts of the plunger pump, such as the cylinder block and the plunger-slipper assembly, stirring the oil during their movement. The churning loss generated by the rotation of the cylinder block can be expressed by the following formula:

[0033]

[0034] In the formula, This indicates the stirring loss caused by the cylinder block; Indicates the length of the cylinder block; Indicates the cylinder block radius; This indicates the distance between the cylinder block and the inner surface of the housing.

[0035] The stirring loss caused by the rotation of the plunger-slipper assembly can be expressed as:

[0036]

[0037] In the formula, This indicates the stirring loss caused by the plunger-slipper assembly; This represents the reduction factor for multiple plungers; This represents the drag coefficient, which is related to the Reynolds number; This indicates the length of the plunger outside the plunger bore.

[0038] By substituting the established aviation plunger pump loss model into the thermal network node model established in step (1), the temperature changes of each node of the aviation plunger pump can be obtained. Based on this, the return oil flow rate is increased, and the temperature changes of each node of the aviation plunger pump under different return oil flow rates are analyzed.

[0039] Preferably, step (3) includes:

[0040] Step (3.1): Determine the structural parameters of the cycloidal gear, including the number of internal teeth. Number of teeth on the outer rotor eccentricity e, width B, inner rotor pitch circle radius External rotor pitch circle radius Generative circle radius L, generative coefficient k, tooth profile circle radius R, arc diameter coefficient h, and root circle radius of the inner rotor. Tooth tip circle radius Root circle radius of the outer rotor and tooth tip circle radius The relationship between the structural parameters introduces the generation coefficient k and the radius coefficient h as dimensionless structural parameters, corresponding to the radius of the generation circle and the radius of the tooth profile circle, respectively; the relationship is as follows:

[0041] ;

[0042] Step (3.2): Determine its parametric equation based on the forming principle of short-amplitude epicycloids.

[0043] ;

[0044] The tooth profile curve of the inner rotor of the cycloidal gear is an equidistant curve of the short-amplitude epicycloid. The tooth profile curve equation of the inner rotor is obtained by offsetting the parametric equation. Therefore, the parametric equation of the tooth profile curve of the inner rotor can be expressed as follows:

[0045]

[0046] In the formula, θ represents the meshing angle. ;

[0047] Step (3.3): Determine the displacement and flow pulsation of the cycloidal gear based on the structural parameters:

[0048] The volume of a cycloidal gear can be approximately determined by the root circle of the outer rotor teeth, i.e.

[0049]

[0050] The displacement of a cycloidal gear can be calculated using empirical formulas.

[0051]

[0052] The calculation model for flow pulsation of cycloidal gears is as follows

[0053]

[0054] In the formula, This represents the maximum instantaneous flow rate; This represents the minimum instantaneous flow rate; Indicates the angular velocity of the plunger pump; This indicates the distance from the meshing point M to the center point of the internal gear. The meshing radius; This indicates the distance from the meshing point M to the center point of the external gear. The meshing radius.

[0055] Preferably, step (4) includes: step (4.1) designing cycloidal gears with different parameter combinations, determining the structure of the cycloidal gear according to the formula in step (3) and drawing the corresponding three-dimensional model; extracting the fluid domain model of the cycloidal gear for CFD simulation, and analyzing the influence of structural parameters on the hydraulic performance of the cycloidal gear in combination with the established displacement and flow pulsation theoretical model; step (4.2) considering the structural limitations of the aviation plunger pump, eliminating structural parameter combinations that do not meet the size constraints, and selecting structural parameter combinations with lower flow pulsation rate, smaller size and larger displacement; step (4.3) using finite element analysis software such as ANSYS to perform finite element simulation on the aviation plunger pump with integrated cycloidal gear, and analyzing whether its stress concentration points exceed the strength of the selected material; if the requirements are not met, repeat step (4.1) for optimization design until the optimal structural parameters that meet the strength requirements are determined. Through simulation-driven design, the optimality of the cycloidal gear under multiple requirements such as performance, size and strength is ensured.

[0056] Preferably, step (5) includes: step (5.1) completing the machining of the designed cycloidal gear, designing test fixtures to test and determine its output characteristics; after determining that the output characteristics of the cycloidal gear meet the design requirements, integrating it into the aviation plunger pump; step (5.2) conducting a comparative test on the aviation plunger pump with and without the integrated cycloidal gear, changing the working conditions while keeping the inlet conditions unchanged, recording and comparing the temperature data, and verifying the temperature control effect of the cycloidal gear; step (5.3) predicting the temperature change curve based on the thermal network model established in step (1), and comparing it with the test results in step (5.2) to verify the effectiveness of the thermal network model.

[0057] The beneficial effects of this invention are:

[0058] The cycloidal gear structure integrated into the aircraft plunger pump proposed in this invention avoids the need for additional oil pumping equipment on the return oil line, ensuring the high power density requirements of the aircraft hydraulic system. The cycloidal gear forces the high-temperature oil in the plunger pump housing cavity to be discharged, and introduces low-temperature oil from the plunger pump suction port to further reduce the oil temperature in the cavity, thus enhancing the heat dissipation capacity of the aircraft plunger pump. The thermal network model of the aircraft plunger pump proposed in this invention can predict the return oil temperature of the aircraft plunger pump under different speed, flow rate, and pressure conditions, ensuring calculation accuracy while avoiding the high time consumption of finite element simulation and fluid simulation.

[0059] The features and advantages of the present invention will be described in detail through embodiments and in conjunction with the accompanying drawings. Attached Figure Description

[0060] Figure 1 This is a flowchart of a method for temperature control of an aviation plunger pump based on a cycloidal gear according to the present invention.

[0061] Figure 2 This is a schematic diagram of an aviation plunger pump according to the present invention, which is a method for temperature control of an aviation plunger pump based on a cycloidal gear.

[0062] Figure 3 This is a schematic diagram of the thermal network node model of a plunger pump, which is a method for temperature control of an aviation plunger pump based on cycloidal gears according to the present invention.

[0063] Figure 4 This is a schematic diagram of cycloidal gear meshing in an aviation plunger pump temperature control method based on cycloidal gears according to the present invention.

[0064] Figure 5 This is a partially enlarged view of the cycloidal gear meshing schematic diagram of the temperature control method for an aviation plunger pump based on cycloidal gears according to the present invention.

[0065] Figure 6 This is a schematic diagram of the cycloidal gear internal rotor gear structure of an aviation plunger pump temperature control method based on cycloidal gear according to the present invention.

[0066] Figure 7 This is a schematic diagram of the cycloidal gear external rotor gear structure of an aviation plunger pump temperature control method based on cycloidal gear according to the present invention.

[0067] Figure 2 In the middle: 1-oil return port, 2-oil suction port, 3-oil discharge port, 4-distributor plate, 5-cylinder block, 6-plunger, 7-slipper, 8-swashplate, 9-main shaft, 10-cycloidal gear oil suction cover plate, 11-cycloidal gear outer rotor, 12-cycloidal gear inner rotor, 13-cycloidal gear oil discharge end cover;

[0068] Figure 3 In the diagram, each solid dot represents a different node in the thermal network, corresponding from left to right and top to bottom as follows: inlet flow channel node, manifold shell node, outlet flow channel node, distribution plate node, shell node, environment node, distribution pair loss node, cylinder block node, plunger pair loss node, shell cavity node, plunger node, stirring loss node, slipper node, slipper pair loss node, and swashplate node. The solid lines connecting the nodes represent heat transfer paths, and the rectangles and the labels R1 to R19 represent the thermal resistance along each path. Detailed Implementation

[0069] See Figures 1-7The present invention discloses a method for temperature control of an aviation plunger pump based on a cycloidal gear, the specific implementation of which is as follows:

[0070] 1. Establish temperature analysis models for each control element of the aircraft plunger pump and a thermal balance model for the aircraft plunger pump:

[0071] Analyzing the temperature transfer path of an aviation plunger pump, the plunger pump draws in low-temperature, low-pressure oil from the suction port. After the reciprocating motion of the plunger and slipper assembly, the high-pressure oil is discharged from the discharge port. At the same time, there are leakage losses and viscous losses in the plunger pump distribution pair, plunger pair, and slipper pair, as well as rotational losses generated by the rotating components such as the plunger and slipper during operation. These energy losses are converted into heat and enter the oil. The high-temperature oil is finally discharged through the return port, carrying away the heat. Meanwhile, the high-temperature oil exchanges heat with the environment through the casing to dissipate heat.

[0072] Based on the heat transfer path of the plunger pump, the thermodynamic model of the plunger pump is divided into fluid nodes such as suction node, discharge node, and return node, as well as distribution plate node, cylinder block node, plunger node, slipper node, swashplate node, and outer shell solid node. The corresponding thermal network node equations can be expressed as:

[0073]

[0074] In the formula, Indicates the temperature of each node; Indicates the quality of each node; This represents the specific heat capacity of each node; This indicates the thermal resistance between each node. Among the subscripts, in represents the suction node; fc represents the distribution housing node; out represents the discharge node; l represents the return node; vp represents the distribution plate node; cy represents the cylinder block node; p represents the plunger node; s represents the slipper node; sw represents the swashplate node; case represents the housing node; and am represents the ambient node. This indicates leakage losses generated by the distribution pair; This indicates leakage losses caused by the plunger assembly; This indicates leakage losses caused by the slipper pair; This represents the viscous loss generated by the distribution pair; This indicates the viscous loss caused by the plunger assembly; This indicates the viscous loss caused by the slipper pair; This indicates the stirring loss caused by the rotating component. This indicates the proportion of heat generated by leakage and viscous losses in the distribution sub-devices, as expressed by the heat transfer distribution disk nodes. This indicates the proportion of heat generated by leakage and viscous losses in the distribution pair that is transferred to the cylinder block nodes. This indicates the proportion of heat generated due to leakage losses and viscous losses in the distribution pair that is transferred to the return oil node; This indicates the proportion of heat transferred to the cylinder block nodes in the heat generated by leakage and viscous losses from the plunger assembly. This indicates the proportion of heat generated by the plunger joint due to leakage and viscous losses. This indicates the proportion of heat generated due to leakage and viscous losses in the plunger assembly that is transferred to the return oil node. This indicates the proportion of heat generated by leakage and viscous losses in the slipper assembly, at the slipper node. This indicates the proportion of heat transferred to the swashplate node in the total heat generated by leakage and viscous losses from the slipper pair. This indicates the proportion of heat generated by leakage and viscous losses in the slipper pair that is transferred to the return oil node; This indicates the percentage of heat generated by stirring that is transferred to the cylinder nodes; This indicates the proportion of heat lost due to stirring that is transferred to the plunger node; This indicates the proportion of heat lost due to stirring that is transferred to the slipper node. This indicates the proportion of heat lost due to stirring that is transferred back to the oil return node. This indicates the flow rate entering the oil suction node; This indicates the flow rate exiting from the oil discharge point; This indicates the flow rate out of the return oil node; This indicates the flow rate from the discharge point to the return point; This represents the flow rate from the suction node to the return node. It is important to note that: a. A positive sign in the equation indicates energy transfer from the node to the outside, and a negative sign indicates energy transfer from the outside to the node; b. Due to the limited leakage flow of the plunger pump, to prevent the cycloidal gear from drawing in cavitation fluid, additional oil needs to be introduced from the suction node to the return node. Therefore, compared to a traditional plunger pump, the heat network node established in this patent requires an additional heat transfer path between the suction and return nodes.

[0075] The convective heat transfer thermal resistance between the solid and liquid nodes can be calculated as follows:

[0076]

[0077] In the formula, represents the thermal resistance of the node; h represents the convective heat transfer coefficient between nodes; A represents the heat transfer area.

[0078] The thermal resistance between solids can be calculated as follows:

[0079]

[0080] In the formula, Indicates the thermal resistance between solids and solid nodes; Indicates the solid thickness at the heat exchange node; This indicates the heat exchange area.

[0081] The convective heat transfer thermal resistance between the shell and the environment can be expressed as:

[0082]

[0083] In the formula, This indicates the effective heat transfer area of ​​the outer surface of the shell; t represents the heat transfer area of ​​the shell; t represents the shell thickness. Indicates the thermal conductivity of the shell material; It represents the convective heat transfer coefficient between the outer surface of the shell and the environment. It represents the radiation equivalent heat transfer coefficient from the outer surface of the shell to the environment.

[0084]

[0085] In the formula, σ represents the surface emissivity; σ represents the Stefan-Boltzmann constant. .

[0086] 2. Establish an energy loss model for aircraft plunger pumps:

[0087] Energy losses in a plunger pump include viscous losses occurring in the friction pairs. Leakage loss And stirring losses from rotating components such as the cylinder block and plunger-slipper assembly. wait.

[0088] First, viscous friction loss mainly occurs due to relative motion in the distribution pair, plunger pair, and slipper pair. The viscous loss generated in the distribution pair can be expressed as:

[0089]

[0090] In the formula, This represents the viscous loss generated by the distribution pair; Indicates the dynamic viscosity of the oil; This indicates the clearance between the cylinder block and the distributor plate; z indicates the number of plungers; Indicates the wrap angle of the cylinder block auxiliary support band; Indicates the inner radius of the sealing strip inside the cylinder; Indicates the outer radius of the sealing strip inside the cylinder; Indicates the inner radius of the external sealing strip of the cylinder; Indicates the outer radius of the external sealing strip of the cylinder body; Indicates the inner radius of the cylinder block auxiliary support band; Indicates the outer radius of the cylinder block auxiliary support; This indicates the wrap angle of the waist-shaped groove in the distribution plate.

[0091] The viscous loss generated in the plunger assembly can be expressed as:

[0092]

[0093] In the formula, This indicates the viscous loss caused by the plunger assembly; This indicates the clearance between the plunger and the plunger bore; Indicates the length of the plunger in the plunger bore; R represents the plunger diameter; R represents the cylinder bore pitch radius. This indicates the swashplate tilt angle.

[0094] The viscous loss generated in the slipper pair can be expressed as:

[0095]

[0096] In the formula, This indicates the viscous loss caused by the slipper pair; This indicates the gap between the skate and the swashplate; Indicates the outer diameter of the sealing strip at the bottom of the slipper; This indicates the inner diameter of the sealing strip at the bottom of the slipper.

[0097] Secondly, leakage losses mainly occur in the distribution pair, plunger pair, and slipper pair due to leakage. The leakage losses in the distribution pair are as follows:

[0098]

[0099] The leakage loss generated in the plunger assembly is

[0100]

[0101] In the formula, This indicates the relative speed of the piston pump within the cylinder bore; n represents the number of pistons in the aero-pump piston pump.

[0102] The leakage loss generated in the slipper pair is

[0103]

[0104] Furthermore, the churning loss is mainly generated by the rotating components of the plunger pump, such as the cylinder block and the plunger-slipper assembly, churning the oil during their movement. The churning loss generated by the rotation of the cylinder block can be expressed by the following formula:

[0105]

[0106] In the formula, This indicates the stirring loss caused by the cylinder block; Indicates the length of the cylinder block; Indicates the cylinder block radius; This indicates the distance between the cylinder block and the inner surface of the housing.

[0107] The stirring loss caused by the rotation of the plunger-slipper assembly can be expressed as:

[0108]

[0109] In the formula, This indicates the stirring loss caused by the plunger-slipper assembly; This represents the reduction factor for multiple plungers; This represents the drag coefficient, which is related to the Reynolds number; This indicates the length of the plunger outside the plunger bore.

[0110] Finally, by substituting the established loss model of the aviation plunger pump into the established thermal network node model, the temperature changes of each node of the aviation plunger pump can be obtained. Based on this, the return oil flow rate is increased, and the temperature changes of each node of the aviation plunger pump under different return oil flow rates are analyzed.

[0111] 3. Establish the equations for the inner and outer rotor tooth profiles of the cycloidal gear, as well as the calculation models for displacement and flow rate pulsation:

[0112] (1) Number of internal teeth Number of teeth on the outer rotor eccentricity e, width B, inner rotor pitch circle radius External rotor pitch circle radius Generative circle radius L, generative coefficient k, tooth profile circle radius R, arc diameter coefficient h, and root circle radius of the inner rotor. Tooth tip circle radius Radius of the tooth root circle of the outer rotor and tooth tip circle radius The parameters that affect the structure of the cycloidal gear have the following relationships:

[0113]

[0114] (2) Based on the forming principle of short-amplitude epicycloids, the parametric equation of short-amplitude epicycloids can be determined as follows:

[0115]

[0116] (3) Since the tooth profile curve of the inner rotor of the cycloidal gear is an equidistant curve of a short-amplitude epicycloid, the parametric equation of the tooth profile curve of the inner rotor can be expressed as:

[0117]

[0118] In the formula, θ is the meshing angle. .

[0119] (4) The volume of the cycloidal gear can be approximately determined by the root circle of the outer rotor teeth, i.e.

[0120]

[0121] (5) The displacement of cycloidal gears can be calculated using empirical formulas.

[0122]

[0123] (6) The calculation model for flow pulsation of cycloidal gears is as follows:

[0124]

[0125] In the formula, This represents the maximum instantaneous flow rate; This represents the minimum instantaneous flow rate; Indicates the angular velocity of the plunger pump; This indicates the distance from the meshing point M to the center point of the internal gear. The meshing radius; This indicates the distance from the meshing point M to the center point of the external gear. The meshing radius.

[0126] 4. Analyze the influence of cycloidal gear structural parameters on oil return flow and heat dissipation capacity, and determine the optimal structural parameters of the cycloidal gear:

[0127] (1) Design cycloidal gears with different parameter combinations, according to equation (23). (31) Determine the structure of the cycloidal gear. Draw its three-dimensional model. Extract the fluid domain model of the cycloidal gear, perform CFD simulation, and combine it with equation (32). (34) Analyze the influence of structural parameters on the hydraulic performance of cycloidal gears;

[0128] (2) Considering the structural limitations of the aviation plunger pump, we exclude structural parameter combinations that do not meet the size constraints and select structural parameter combinations with lower flow pulsation rate, smaller size and larger displacement.

[0129] (3) Use ANSYS software to perform finite element simulation on the aerospace plunger pump with integrated cycloidal gear, and analyze whether its stress concentration point exceeds the strength of the selected material. If it does not meet the requirements, repeat steps (1) to (3) to optimize the design of the cycloidal gear structure, and finally obtain the cycloidal gear structure parameters that meet the strength requirements.

[0130] 5. Complete the machining and testing of the cycloidal gear, and verify the effect of the designed cycloidal gear on the temperature control of the aerospace plunger pump and the effectiveness of the plunger pump thermal network model:

[0131] (1) Complete the machining of the designed cycloidal gear, and design experimental fixtures to test and determine its output characteristics. Once it is determined that the output characteristics of the cycloidal gear meet the design requirements, integrate it into the aviation plunger pump;

[0132] (2) Tests were conducted on aviation plunger pumps with and without integrated cycloidal gears. With the inlet pressure and inlet oil temperature constant, only the rotational speed or outlet pressure was changed under a single operating condition, and the changes in outlet and return oil temperatures of the aviation plunger pumps were recorded. The results were compared to verify the effectiveness of the designed cycloidal gear in temperature control of the aviation plunger pump.

[0133] Combined formula (1) (14) Determine the temperature change curves of the oil discharge temperature, oil return temperature and shell temperature of the aviation plunger pump with integrated cycloidal gear under different speed and load pressure conditions, and compare them with the results of step (2) to verify the effectiveness of the established aviation plunger pump thermal balance model.

[0134] The above embodiments are illustrative of the present invention and are not intended to limit the present invention. Any simple modifications to the present invention are within the scope of protection of the present invention.

Claims

1. A method for temperature control of an aircraft plunger pump based on a cycloidal gear, characterized in that, Includes the following steps: Step (1): Analyze the temperature transfer path of the aircraft plunger pump, decompose the thermodynamic model of the plunger pump into multiple control volume nodes, and establish the thermal network model of the plunger pump. The thermal network model includes the temperature analysis model of each control volume node and the overall thermal network equation. The establishment of the thermal network model includes: based on the heat transfer path of the plunger pump, dividing its thermodynamic model into fluid nodes including suction nodes, discharge nodes, and return nodes, and solid nodes including distribution plate nodes, cylinder block nodes, plunger nodes, slipper nodes, swashplate nodes, and shell nodes; establishing thermal network node equations according to the heat transfer direction between each node; wherein, the thermal network node equations additionally include the heat transfer path from the suction node to the return node; Step (2): Establish the energy loss model of the plunger pump and substitute the energy loss model into the temperature analysis model described in step (1) to analyze the temperature changes of each node of the plunger pump under different return oil flow rates. Step (3): Establish the internal and external rotor tooth profile equations of the cycloidal gear, as well as the theoretical model of the displacement and flow pulsation of the cycloidal gear; Step (4): Establish the CFD model of the cycloidal gear, combine it with the theoretical model in step (3), analyze the influence of structural parameters on displacement and flow pulsation, and combine the structural size constraints and heat dissipation flow requirements of the plunger pump to determine the optimal structural parameters of the cycloidal gear. Step (5): Complete the machining and testing of the cycloidal gear, and integrate it into the plunger pump for experimental verification to verify the temperature control effect of the cycloidal gear on the plunger pump and the effectiveness of the plunger pump thermal network model.

2. The method according to claim 1, characterized in that, In step (2), establishing the energy loss model includes: The energy loss includes viscous friction loss and leakage loss that occur in the distribution pair, plunger pair and slipper pair, as well as stirring loss caused by the rotation of the cylinder block and plunger-slipper assembly within the housing cavity; The calculation equation for the leakage loss is established based on the gap flow theory; The calculation equation for the viscous friction loss is established based on the oil film lubrication theory; The calculation equation for the stirring loss is established based on the theory of rotating body resistance torque.

3. The method according to claim 1, characterized in that, Step (3) includes: Step (3.1): Determine the structural parameters of the cycloidal gear, including the number of internal teeth, the number of external rotor teeth, the eccentricity, the width, the pitch circle radius, the generative circle radius, and the tooth profile circle radius. Based on the gear meshing relationship, determine the relationship between the root circle radius and the tip circle radius of the internal and external rotors and the structural parameters. Introduce the generative coefficient and the arc radius coefficient as dimensionless structural parameters, which correspond to the generative circle radius and the tooth profile circle radius, respectively. Step (3.2): Determine its parametric equation based on the forming principle of the short-amplitude epicycloid. The inner rotor tooth profile curve of the cycloid gear is the equidistant curve of the short-amplitude epicycloid. Obtain the tooth profile curve equation of the inner rotor by offsetting the parametric equation. Step (3.3): Determine the displacement and flow pulsation of the cycloidal gear based on the structural parameters.

4. The method according to claim 1, characterized in that, Step (4) includes: Step (4.1): Design cycloidal gears with multiple parameter combinations, perform CFD simulation, and analyze the influence of structural parameters on hydraulic performance by combining the theoretical models of displacement and flow pulsation. Step (4.2): Based on the structural dimensional constraints of the plunger pump, select the parameter combinations that meet the requirements; Step (4.3): Perform finite element simulation analysis on the aviation plunger pump integrating the cycloidal gear. If the structural strength does not meet the requirements, return to step (4.1) for optimization until the optimal structural parameters that meet the strength requirements are determined.

5. The method according to claim 1, characterized in that, Step (5) includes: Step (5.1): Machining the cycloidal gear and testing its output characteristics, and integrating it into the plunger pump after confirming that it meets the requirements; Step (5.2): Conduct a comparative test on the aviation plunger pumps with and without the cycloidal gear. Change the operating conditions while keeping the inlet conditions unchanged, record and compare the temperature data, and verify the temperature control effect of the cycloidal gear. Step (5.3): Based on the thermal network model established in step (1), predict the temperature change curve and compare it with the experimental results in step (5.2) to verify the effectiveness of the thermal network model.

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