Design method of underwater motor oil cooling system, underwater motor and underwater equipment

Abstract

In order to solve the technical problems that the design of the UUV motor oil stirring cooling system by using the design method of the existing conventional oil stirring cooling system will cause poor cooling effect, design redundancy and even excessive redundancy, and affect the power performance of the UUV, the application provides a design method of an underwater equipment motor oil cooling system and an underwater equipment motor. The design method of the application innovatively introduces the concept of motor equivalent power density or power density strengthening factor, and based on the motor equivalent power density or power density strengthening factor, the scheme of the oil stirring cooling system is selected from the design sample points in combination with the actual working condition, so that the cooling performance and the strict quality requirement can be considered at the same time, the effective cooling of the motor is ensured, unnecessary design redundancy and weight increase are avoided, the motor equivalent power density or power density strengthening factor is maximized, and favorable conditions for the compact design of the underwater motor and the carrying of more functional loads of the underwater equipment are created.

Description

Technical Field

[0001] This invention relates to the field of underwater motor design technology. Background Technology

[0002] Unmanned underwater vehicles (UUVs), as core equipment for ocean exploration and underwater operations, require highly reliable propulsion capabilities in complex environments. Permanent magnet synchronous motors (PMSMs), with their high power density and efficient energy conversion characteristics, have become the core power source for UUV propulsion systems. As the complexity of UUV missions increases, the power density of motors in UUV propulsion systems also grows rapidly. However, the resulting heat accumulation problem is becoming a key bottleneck restricting the reliability of UUV propulsion systems.

[0003] During UUV navigation, the drag experienced is proportional to the square of the speed, while the required motor power is proportional to the cube of the speed. High power density design requirements force the magnetic field density of the motor core and the winding current density to approach material limits, leading to an exponential increase in copper and iron losses. Within the sealed cavity of the UUV, heat cannot be effectively dissipated through air convection, and heat accumulation triggers a vicious cycle. When the winding temperature exceeds the material limits, the insulation layer undergoes thermal decomposition, and the magnets experience high-temperature demagnetization. More seriously, cavitation may occur inside the sealed cavity due to localized hot spots, threatening the safety of the entire propulsion system. Therefore, developing a highly efficient cooling system adapted to the special operating conditions of UUVs has become an essential path for technological upgrades.

[0004] Oil-cooled systems offer advantages such as high heat capacity and good dielectric strength and lubrication. The oil filling the motor directly contacts the heat-generating elements, resulting in effective cooling, and is currently primarily used in electric vehicles. However, the inventors of this invention have discovered that while the oil in an oil-cooled system can effectively cool the motor, excessive oil can lead to frictional losses that weaken the cooling effect and limit motor performance. Therefore, more oil filling the motor is not necessarily better. Furthermore, UUVs have stringent requirements regarding weight and volume. Using an oil-cooled system in the UUV motor increases the motor's weight as the proportion of oil increases, leading to an increase in UUV weight. Excessive weight gain negatively impacts the UUV's power performance, hindering the achievement of long-duration, high-efficiency flight specifications. Existing conventional oil-cooled systems do not consider these factors in their design, particularly the impact of oil volume on UUV weight. If the existing conventional oil churning cooling system design method is used to design the UUV motor oil churning cooling system, the cooling effect of the UUV motor oil churning system will be poor, and the design will have the disadvantage of excessive redundancy, which will ultimately affect the power performance of the UUV. Summary of the Invention

[0005] To address the technical problem that designing an oil cooling system for a UUV motor using existing conventional oil churning cooling system design methods can lead to poor cooling performance and excessive or even excessive design redundancy, thus affecting the power performance of the UUV, this invention proposes a design method for an oil cooling system for an underwater equipment motor and an underwater equipment motor.

[0006] Technical approach and inventive concept of this invention:

[0007] The inventors of this invention have discovered that existing UUV motor oil cooling systems often only qualitatively consider the cooling effect during design, neglecting the adverse effects of unnecessary additional weight on the UUV's power performance. This often leads to redundant design, which has multiple negative consequences: redundant oil adds unnecessary weight to the UUV, affecting its power performance; simultaneously, redundant oil churning design generates additional oil friction losses, limiting motor performance. Adopting a more reasonable oil filling volume can significantly improve the heat dissipation efficiency of the motor oil cooling system. This improved heat dissipation efficiency, in turn, creates favorable conditions for the miniaturization of the motor design.

[0008] To minimize the negative impact of design redundancy in UUV motors using oil cooling systems and ensure stable navigation during long-duration, long-range, and high-speed operation, this invention, considering the working environment of UUVs, designs an oil-cooling system (also known as an immersion oil cooling system) that can cool oil without the aid of external components. This system utilizes the rotation of the UUV motor rotor to evenly distribute oil inside the motor, thereby cooling the internal heat-generating components. It also utilizes convection cooling with external seawater to further cool the oil. This eliminates the need for pumps and auxiliary heat dissipation devices such as heat exchangers for cooling the oil, making the motor system more efficient and compact.

[0009] Next, the inventors conducted experiments to verify the application of the churning oil cooling system to UUVs. They found that under different oil filling volumes, the cooling effect of the churning oil cooling system and the power performance of the UUV did not improve with the increase of oil filling volume, but rather showed a non-linear trend. Research and analysis revealed that this non-linear trend is because as the motor speed increases, the oil flow rate inside the motor accelerates, enhancing the convective heat transfer effect, but also increasing the frictional loss of the oil. Simultaneously, as the oil volume increases, the intensity of heat exchange inside the motor increases. When the intensity of convective heat exchange between the external seawater and the motor section is insufficient to cool all the oil, the oil temperature cannot be cooled by the seawater, resulting in a poorer cooling effect. This reaches the design threshold for the oil filling volume of the churning oil cooling system. If the design threshold for oil filling volume is exceeded and the amount of cooling oil inside the motor is further increased, not only will a better cooling effect not be achieved, but it will also have the opposite effect, causing design redundancy in the churning oil cooling system.

[0010] Therefore, starting from the technical goal of UUV long-term and efficient navigation, the inventors of this invention thought of optimizing the motor body and the oil churning and cooling system as a whole motor system. With the maximum power density as the optimization target, the oil volume of the oil churning and cooling system is quantitatively optimized so that the entire motor system can achieve ideal performance in the high-speed variable speed range of the UUV. At the same time, the propulsion performance of the UUV is also taken into consideration from a macro perspective (such as the high maneuverability of underwater equipment, good heat dissipation capacity, and the ability of underwater equipment to achieve higher top speed and faster acceleration).

[0011] Based on the above technical approach and inventive concept, the specific technical solution of the present invention is as follows:

[0012] The design method for an underwater motor oil cooling system is characterized by the fact that the oil cooling system is an oil churning cooling system; the design method includes the following steps:

[0013] Step 1: Obtain motor power characteristic parameters, including the output power of the motor body at different speeds and the motor loss at different output powers, and obtain the heat generation rate of each component in the motor body corresponding to different motor losses;

[0014] Step 2: Set the range of values ​​for the flow field-thermal field coupling simulation parameters, including the range of cooling oil level height for the churning oil cooling system, the speed range of the underwater equipment, and the rotational speed, motor losses, and heat generation rate of each component corresponding to each speed. The motor losses and heat generation rate of each component corresponding to each speed of the underwater equipment are obtained from the motor power characteristic parameters and heat generation rate of each component obtained in Step 1 based on the required rotational speed and output power of the motor body at each speed.

[0015] Step 3: Based on the range of values ​​for the flow field-thermal field coupling simulation parameters set in Step 2, obtain the maximum temperature, torque, and oil friction loss of each component in the motor body at different speeds and oil levels.

[0016] Step 4: Select and retain design sample points that meet the motor design requirements in terms of maximum temperature, torque, and oil friction loss;

[0017] Step 5: Calculate the equivalent power density or power density enhancement factor of the motor for each design sample point retained in Step 4, and store them corresponding to the design sample points retained in Step 4; the equivalent power density of the motor is the equivalent power of the motor per unit weight; the power density enhancement factor is the dimensionless value of the equivalent power density of the motor, which characterizes the intensity of the improvement in equivalent power density.

[0018] Step 6: Based on the underwater equipment operating conditions and the equivalent power density or power density enhancement factor of the motor, select the optimal solution from the retained design sample points to determine the optimal oil level of the cooling oil in the churning oil cooling system.

[0019] Further, step 1 specifically involves establishing a simplified 3D model of the external basin and underwater equipment in 3D modeling software, using electromagnetic analysis software to analyze the electromagnetic field characteristics of the motor body in the 3D model to obtain motor power characteristic parameters and motor losses, and then, based on the obtained motor losses and the underwater equipment in the 3D model, obtaining the heat generation rate of each component of the motor body under different motor losses; the simplified 3D model of the underwater equipment only includes the motor body and the parts of the underwater equipment that are in contact with seawater.

[0020] Furthermore, in step 2, the required rotational speed and output power of the motor body for each speed within the underwater equipment's speed range are obtained based on the relationship between the motor, propeller, and underwater equipment speed.

[0021] Furthermore, in step 3, the maximum temperature, torque, and oil friction loss of each component in the motor body at different speeds and oil levels are obtained by performing thermal-fluid coupling simulation on the simulation model using the external flow domain and a simplified three-dimensional model of the underwater equipment as the simulation model in the simulation software. During the thermal-fluid coupling simulation, the inputs to the simulation model are the speed, the rotational speed of the motor body corresponding to the speed, the motor loss, the heat generation rate of each component, and the oil level.

[0022] Furthermore, in step 5:

[0023] The equivalent power density of the motor is calculated using the following formula:

[0024] ;

[0025] The power density enhancement factor is calculated using the following formula:

[0026] ;

[0027] In the formula,

[0028] For power factor, ;

[0029] For speed v i Total output power of the lower motor body;

[0030] T ij The highest temperature of each component inside the motor body when the underwater equipment is operating at different oil levels and speeds;

[0031] T i1 The highest temperature of each component inside the motor body when the underwater equipment operates at different speeds under natural cooling conditions;

[0032] For underwater motors at different oil levels h jTotal weight under the conditions;

[0033] It is the equivalent power density of the motor under natural cooling conditions.

[0034] Furthermore, step 6 specifically includes:

[0035] If the underwater equipment has a specific speed v s The operating conditions account for 90% or more of the total operating rates of underwater equipment, so only at that specific speed v s Primarily, select that specific speed v s Down or The oil level height corresponding to the largest design sample point is taken as the optimal solution, thereby determining the optimal oil level height;

[0036] If the underwater equipment has multiple speed points and occupies different proportions, it is necessary to first calculate the total equivalent power density of the motor using a weighted average. Alternatively, a weighted calculation of the total power density enhancement factor can be performed. Then, using the total equivalent power density of the motor Or total power density enhancement factor As the selection criterion, the total motor equivalent power density is chosen. Or total power density enhancement factor The largest design sample point is taken as the optimal solution, thereby determining the optimal oil level height;

[0037] At an oil level height of h j Under the condition of, total power density enhancement factor The calculation formula is:

[0038]

[0039] At an oil level height of h j Under the condition of, the total equivalent power density of the motor The calculation formula is:

[0040] ;

[0041] In the formula,

[0042] P sn For speed v sn The corresponding motor output power P sn ;

[0043] t sn For speed v sn The proportion of total navigation time of underwater equipment;

[0044] The oil level is h. jDown, speed v sn The corresponding power density enhancement factor;

[0045] The oil level is h. j Down, speed v sn The corresponding equivalent power density of the motor.

[0046] Furthermore, it also includes step 7:

[0047] In step 6, when selecting the optimal solution, if none of the design sample points retained in step 4 meet the actual working conditions, return to step 3 to refine the oil level height selection step size and redesign until a solution that meets the actual working conditions can be designed.

[0048] This invention also proposes an underwater motor, including a motor body and an oil cooling system; the motor body includes a motor housing; its special feature is that: the oil cooling system is an oil agitation cooling system, including cooling oil filled in the motor housing; the cooling oil is agitated by the rotor assembly of the motor body and splashed onto the components in the motor housing for cooling; the cooling oil falls back to the bottom of the motor housing and exchanges heat with the outside seawater through convection between the motor housing and the outer shell of the underwater equipment, or the cooling oil exchanges heat through auxiliary heat exchange equipment; the oil level / filling volume of the cooling oil is determined according to the above design method.

[0049] Furthermore, the motor housing is the outer casing of the underwater equipment; the cooling oil falls back to the bottom of the outer casing of the underwater equipment and exchanges heat with the outside seawater through convection.

[0050] The present invention also proposes an underwater device, which is special in that it uses the above-mentioned underwater motor as its power system.

[0051] The advantages of this invention are:

[0052] 1. The design method of this invention is ingenious and the optimization means are simple. It requires minimal modification to the underwater motor's oil churning and cooling system and the motor structure, resulting in low implementation costs. By simply optimizing the amount of oil inside the motor body, the power density of the underwater equipment motor can be increased, and design redundancy in the oil churning and cooling system can be avoided, thereby improving the utilization rate of the oil churning and cooling system. In particular, avoiding design redundancy can prevent unnecessary weight gain in underwater equipment, achieving weight reduction and improving the power performance of underwater equipment, thus better achieving the goals of long endurance and long range for underwater equipment.

[0053] 2. Conventional oil-cooling system design methods for electric motors often focus on cooling performance, i.e., temperature improvement. Furthermore, those skilled in the art generally hold the traditional view that "more coolant equals better cooling." In this context, applying conventional oil-cooling system design methods can easily lead to systems that, while meeting the motor's heat dissipation requirements, introduce unnecessary additional weight, failing to meet the stringent quality requirements of underwater equipment and even negatively impacting its power performance. This invention innovatively introduces the concept of equivalent power density or power density enhancement factor for electric motors. Based on this factor, and considering actual operating conditions, the optimal oil-cooling system design is selected from design sample points. This approach simultaneously considers cooling performance and stringent quality requirements, ensuring effective motor cooling without unnecessary weight increase. It maximizes the equivalent power density or power density enhancement factor, creating favorable conditions for compact underwater motor design and enabling underwater equipment to carry more functional payloads. The power density enhancement factor also facilitates technicians in assessing the degree of improvement in the equivalent power density of the design scheme.

[0054] 3. The design method of the present invention is universal and can be applied to underwater motors of different structural types. The designed underwater motor can be used in underwater vehicles, underwater pre-positioned unmanned mobile platforms, underwater biomimetic submersibles, and underwater gliders and other underwater equipment.

[0055] 4. The design method of the present invention has good scalability and can also be applied to the calculation of oil churning cooling of other installation structures of underwater equipment motors. The situations include: 1. The motor in the oil churning cooling system adopts other installation structures, such as: the motor is not placed against the shell (connected / established through the motor installation structure) and there are no other external cooling auxiliary devices. The optimization steps are not changed and it is still applicable. 2. (1) The oil churning cooling system contains auxiliary cooling devices. If the auxiliary cooling devices directly cool the oil, the temperature of the coolant inside the simulation is defined in step 3. For example, for the oil churning cooling system of a certain underwater equipment, at a speed of 15kn, the temperature of the coolant inside the motor after passing through the auxiliary cooling device is 330K, and at a speed of 50kn, the temperature of the coolant after passing through the auxiliary cooling device is 360K; (2) If the auxiliary cooling device cools the motor shell, the temperature of the cooled motor wall surface is defined. For example, the temperature on both sides of the motor end cover under the auxiliary cooling device is defined as 300K.

[0056] 5. The underwater motor of the present invention uses an oil-cooling system for heat dissipation and cooling. Considering the working environment characteristics of underwater equipment, the motor housing is in contact with the underwater equipment housing during installation, and heat exchange can be carried out by seawater and cooling oil. There is no need to set up additional auxiliary heat exchange equipment for cooling oil, which simplifies the structure of the underwater motor and reduces its weight. At the same time, the oil-cooling system is designed using the design method of the present invention, so that the equivalent power density of the underwater motor of the present invention is maximized, without bringing unnecessary additional weight to the underwater equipment. Attached Figure Description

[0057] Figure 1 This is a flowchart of the design method for the oil churning and cooling system of the present invention.

[0058] Figure 2 This is a schematic diagram of the overall working principle of the oil churning and cooling system. Detailed Implementation

[0059] The present invention will be further described in detail below with reference to the accompanying drawings.

[0060] Reference Figure 1 This invention proposes a design method for an underwater motor oil cooling system, wherein the oil cooling system is an oil churning cooling system, and the design method includes the following steps:

[0061] Step 1: Establish a three-dimensional model of the underwater equipment and the external basin, and obtain the power characteristic parameters of the motor and the heat generation rate of each component;

[0062] First, a simplified 3D model of the external basin and underwater equipment was created using 3D modeling software. The simplified underwater equipment 3D model only includes the motor body and the parts of the underwater equipment that come into contact with seawater (such as the hull, flow deflector, etc.). Here, the motor body refers to the underwater motor without a cooling system.

[0063] Secondly, electromagnetic field characteristics of the motor body in the 3D model are analyzed using electromagnetic analysis software (such as Ansys Electronics Desktop, Motor CAD, etc.) to obtain motor power characteristic parameters, including the output power of the motor body at different speeds and the motor loss corresponding to different output powers.

[0064] Finally, based on the obtained motor losses and combined with a simplified three-dimensional model of the underwater equipment, the heat generation rate of each component in the motor body corresponding to different motor losses can be obtained.

[0065] Step 2: Set the range of values ​​for the flow-thermal field coupling simulation parameters;

[0066] The flow-thermal field coupling simulation parameters include the cooling oil level, the underwater equipment speed and the corresponding motor speed, motor losses and the heat generation rate of each component;

[0067] For the coolant level, set the coolant level height h. j The value range is 0 to D, where D is the outer diameter of the stator of the motor body; when the oil level is 0, it means that the motor body is not filled with cooling oil; when the oil level is D, it means that the stator is completely immersed in cooling oil.

[0068] For the equipment's speed and the corresponding motor speed, motor losses, and heat generation rate of each component, select various speeds v within the underwater equipment's speed range. i Based on the known relationship between motors, propellers, and underwater equipment speeds within the industry, the underwater equipment speeds at different v are determined. i The required motor speed and output power And based on output power By analyzing the motor power characteristics parameters obtained in step 1 and finding the motor loss corresponding to the speed, it is possible to determine the heat generation rate of each component in the motor body corresponding to the speed based on the heat generation rate of each component corresponding to different motor losses obtained in step 1.

[0069] Speed ​​v i The step size is determined according to the actual operating conditions of the underwater equipment. The step size should be such that the selected speed can cover the common speed of the underwater equipment. For example, if the common speed of a certain underwater equipment is 50kn, 40kn and 10kn, the step size can be 5kn; if the common speed of a certain underwater equipment is 10kn, 5kn and 3kn, the step size can be 1kn.

[0070] Step 3: Based on the range of values ​​for the flow-thermal field coupling simulation parameters set in Step 2, obtain the maximum temperature and torque M of each component within the motor body at different speeds and oil levels. ij Oil friction loss Q oilij ;

[0071] First, different oil level heights are selected from the range of oil level height values ​​using a set step size; preferably, the oil level height h... j The selection step size is .

[0072] Next, import the three-dimensional model of the external basin and simplified underwater equipment established in step 1 into simulation software (such as Comsol, Fluent, etc.), or use simulation software to call the three-dimensional model of the external basin and simplified underwater equipment established in step 1 to obtain the simulation model of the external basin and simplified underwater equipment.

[0073] Then, for each selected speed v i (At this point, there must be a corresponding motor operating condition.) A simulation model is used to simulate the thermal-fluid coupling, with the simulation time based on the ship's speed v.i (As the external flow velocity), and the sailing speed v i The corresponding motor speed, motor losses, heat generation rate of each component, and oil level h are as follows: j As input parameters to the simulation model, different flight speeds v are obtained through simulation. i Below (i.e., different motor power) (Below), the motor body is filled with oil at different levels h. j When cooling oil is applied, the highest temperature T of each component inside the motor body is... ij Torque M ij Oil friction loss Q oilij ; i takes the values ​​1, 2, 3, ..., m; j takes the values ​​1, 2, 3, ..., n; m and n represent the number of different speeds and the number of different fuel levels, respectively; when j=1, T ij = T i1 This refers to the highest temperature of each component within the underwater motor body when it operates at different speeds underwater, under un-oiled conditions (i.e., natural cooling); when j=n+1, T ij = T in+1 This refers to the highest temperature of each component inside the underwater motor when it operates at different speeds under fully oil-immersed conditions.

[0074] Step 4: Select and retain sample points that meet the motor design requirements;

[0075] Based on the highest temperature T of the underwater motor under different speeds and fuel levels obtained in step 3. ij Torque M ij Oil friction loss Q oilij Determine T ij M ij and Q oilij To determine if all design samples meet the motor design requirements (which are known quantities), discard those that do not meet the requirements and retain only those that do. Each design sample includes the motor output power and torque M at different speeds. ij The oil level of the cooling oil should match the motor design requirements, and the oil friction loss caused by oil filling should also be considered.

[0076] Step 5: Calculate the equivalent power density of each design sample point retained in Step 4. or power density enhancement factor The corresponding design sample points are stored in step 4.

[0077] Motor equivalent power density Calculate using the following formula:

[0078]

[0079] Power density enhancement factor Calculate using the following formula:

[0080]

[0081] In the formula, For speed v i The coolant level is h. j The equivalent power density of the motor at that time is the equivalent power of the motor per unit weight. This equivalent power of the motor is a design reference value, which is convenient for quantifying the power density of the motor at various speeds and oil levels for design and comparison. By doing so, the design sample point corresponding to the maximum equivalent power density of the motor can be determined, thereby avoiding redundant design of the oil churning and cooling system. For underwater motors at different oil levels h j Total weight under the conditions, , This refers to the weight of the motor itself. To determine the quality of the cooling oil added to the motor body, The mass can be calculated by measuring the physical mass of the motor body and motor system, or it can be calculated by software. For power factor, Since the power density of the motor body cannot be accurately obtained in fluid simulation software, this invention introduces... To determine the ratio of the motor output power after oil filling to the motor output power before oil filling; For speed v i Total output power of the lower motor body; The dimensionless power density enhancement factor characterizes the strength of the power density increase achieved by the motor relative to natural cooling at a corresponding speed. It is obtained by making the equivalent power density of the motor dimensionless. It is possible to determine the oil level height corresponding to the maximum power density design sample point, thereby avoiding redundant design of the oil churning cooling system. It is the equivalent power density of the motor under natural cooling conditions.

[0082] Step 6: Based on actual operating conditions and the equivalent power of the motor calculated in Step 5 or power density enhancement factor Select the optimal design scheme from the design sample points retained in step 4;

[0083] The optimal design scheme will be selected based on the actual working conditions.

[0084] Scenario 1: If the underwater equipment has a specific speed v s The operating conditions account for 90% or more of the total operating rates of underwater equipment, so only at that specific speed v sPrimarily, select that specific speed v s down (v) s There must be a specific motor output power (Ps) for this. or The oil level height corresponding to the largest design sample point is taken as the optimal solution, thereby determining the optimal oil level height;

[0085] Scenario 2: If the underwater equipment has multiple speed points and occupies different proportions, it is necessary to first calculate the total equivalent power density of the motor using a weighted average. Alternatively, a weighted calculation of the total power density enhancement factor can be performed. Then, using the total equivalent power density of the motor Or total power density enhancement factor As the selection criterion, the total motor equivalent power density is chosen. Or total power density enhancement factor The largest design sample point is taken as the optimal solution, thereby determining the optimal oil level height;

[0086] Total power density enhancement factor Calculate using the following method:

[0087] Remember v s1 For common operating condition point 1 of underwater equipment, the corresponding motor output power is P. s1 v sn Let n be the commonly used operating point, and P be the corresponding motor output power. sn . t sn This represents the proportion of operating point n to the total navigation time of the underwater equipment. At an oil level height of h... j Under the condition of, total power density enhancement factor The calculation formula is:

[0088]

[0089] In the formula, The oil level is h. j Down, speed v sn The corresponding power density enhancement factor.

[0090] Similarly, when the oil level is h j Under the condition of, the total equivalent power density of the motor The calculation formula is:

[0091] .

[0092] In the formula, The oil level is h. j Down, speed v sn The corresponding equivalent power density of the motor.

[0093] Considering that in practice, the oil level height selection step may be too large, resulting in the inability to find a design sample point that meets the requirements when selecting the optimal scheme in step 6, this invention uses the following step 7 to overcome this defect.

[0094] Step 7 specifically includes:

[0095] If none of the design sample points retained in step 4 meet the actual working conditions, return to step 3 to refine the oil level height selection step size and redesign until a solution that meets the actual working conditions can be designed.

[0096] The present invention also proposes an underwater motor, including a motor body and an oil churning and cooling system.

[0097] The motor body can be any existing, publicly disclosed underwater propulsion motor, such as a single-shaft underwater propulsion motor or an underwater counter-rotating propulsion motor. The motor body includes a motor housing and a rotor assembly. In use, the motor housing is installed inside the outer shell of the underwater equipment and contacts the inner wall of the underwater equipment's outer shell. Alternatively, the motor body can share a housing with the underwater equipment, meaning the motor housing of the motor body serves as the outer shell of the underwater equipment.

[0098] The oil churning cooling system includes cooling oil filled inside the motor housing. When the motor body is running, its rotor assembly rotates, which can churn the cooling oil and throw the oil onto the components inside the motor housing. This transfers the heat from the heat-generating components inside the motor housing to the cooling oil through convection heat transfer. Afterward, the cooling oil falls back to the bottom of the motor housing and is cooled by convection heat transfer between the motor housing and the outer shell of the underwater equipment and the external seawater.

[0099] like Figure 2 As shown, taking a single-shaft underwater propulsion motor applied to an underwater vehicle as an example, the motor body shares a shell with the underwater vehicle, including a rotor and a stator. The rotor includes magnets and a yoke, while the stator includes a stator core and windings. The cooling oil in the churning oil cooling system is agitated by the rotor and thrown onto the motor components, such as the stator core, windings, magnets, and yoke, for convective heat transfer. The cooling oil then flows to the edge of the underwater vehicle's shell and exchanges heat with the surrounding seawater, cooling the oil. As the motor body operates, the cooling oil at the bottom of the underwater vehicle's shell continuously repeats the process of agitation-throwing-heat exchange-falling back-cooling, thereby continuously dissipating heat and cooling the components within the motor body.

[0100] The design method of the oil churning cooling system, namely the amount of cooling oil filled into the motor body, is optimized according to the design method proposed in this invention, and will not be elaborated here.

[0101] The present invention also proposes an underwater device that uses the underwater motor proposed in the present invention as a power system.

Claims

1. A design method for an underwater motor oil cooling system, characterized in that, The oil cooling system is an oil-stirring cooling system; the design method includes the following steps: Step 1: Obtain motor power characteristic parameters, including the output power of the motor body at different speeds and the motor loss at different output powers, and obtain the heat generation rate of each component in the motor body corresponding to different motor losses; Step 2: Set the range of values ​​for the flow field-thermal field coupling simulation parameters, including the range of cooling oil level height for the churning oil cooling system, the speed range of the underwater equipment, and the rotational speed, motor losses, and heat generation rate of each component corresponding to each speed. The motor losses and heat generation rate of each component corresponding to each speed of the underwater equipment are obtained from the motor power characteristic parameters and heat generation rate of each component obtained in Step 1 based on the required rotational speed and output power of the motor body at each speed. Step 3: Based on the range of values ​​for the flow field-thermal field coupling simulation parameters set in Step 2, obtain the maximum temperature, torque, and oil friction loss of each component in the motor body at different speeds and oil levels. Step 4: Select and retain design sample points that meet the motor design requirements in terms of maximum temperature, torque, and oil friction loss; Step 5: Calculate the equivalent power density or power density enhancement factor of the motor for each design sample point retained in Step 4, and store them corresponding to the design sample points retained in Step 4; the equivalent power density of the motor is the equivalent power of the motor per unit weight; the power density enhancement factor is the dimensionless value of the equivalent power density of the motor, which characterizes the intensity of the improvement in equivalent power density. Step 6: Based on the underwater equipment operating conditions and the equivalent power density or power density enhancement factor of the motor, select the optimal solution from the retained design sample points to determine the optimal oil level of the cooling oil in the churning oil cooling system.

2. The design method of the underwater motor oil cooling system according to claim 1, characterized in that, Step 1 involves creating a simplified 3D model of the outer basin and underwater equipment in 3D modeling software. Electromagnetic analysis software is used to analyze the electromagnetic field characteristics of the motor body in the 3D model to obtain the motor power characteristic parameters and motor losses. Then, based on the obtained motor losses and the underwater equipment in the 3D model, the heat generation rate of each component of the motor body under different motor losses is obtained. The simplified 3D model of the underwater equipment only includes the motor body and the parts of the underwater equipment that are in contact with seawater.

3. The design method for the underwater motor oil cooling system according to claim 1, characterized in that, In step 2, the required rotational speed and output power of the motor body for each speed within the range of underwater equipment speed are obtained based on the relationship between the motor, propeller and underwater equipment speed.

4. The design method of the underwater motor oil cooling system according to claim 2, characterized in that, In step 3, the maximum temperature, torque, and oil friction loss of each component in the motor body at different speeds and oil levels are obtained by performing thermal-fluid coupling simulation on the simulation model using the external flow domain and a simplified three-dimensional model of the underwater equipment in the simulation software. During the thermal-fluid coupling simulation, the inputs to the simulation model are the speed, the rotational speed of the motor body corresponding to the speed, the motor loss, the heat generation rate of each component, and the oil level.

5. The design method of the underwater motor oil cooling system according to any one of claims 1-4, characterized in that, In step 5: The equivalent power density of the motor is calculated using the following formula: ； The power density enhancement factor is calculated using the following formula: ； In the formula, For power factor, ; For speed v i Total output power of the lower motor body; T ij The highest temperature of each component inside the motor body when the underwater equipment is operating at different oil levels and speeds; T i1 The highest temperature of each component inside the motor body when the underwater equipment operates at different speeds under natural cooling conditions; For underwater motors at different oil levels h j Total weight under the conditions; It is the equivalent power density of the motor under natural cooling conditions.

6. The design method for the underwater motor oil cooling system according to claim 5, characterized in that, Step 6 specifically involves: If the underwater equipment has a specific speed v s The operating conditions account for 90% or more of the total operating rates of underwater equipment, so only at that specific speed v s Primarily, select that specific speed v s Down or The oil level height corresponding to the largest design sample point is taken as the optimal solution, thereby determining the optimal oil level height; If the underwater equipment has multiple speed points and occupies different proportions, it is necessary to first calculate the total equivalent power density of the motor using a weighted average. Alternatively, a weighted calculation of the total power density enhancement factor can be performed. Then, using the total equivalent power density of the motor Or total power density enhancement factor As the selection criterion, the total motor equivalent power density is chosen. Or total power density enhancement factor The largest design sample point is taken as the optimal solution, thereby determining the optimal oil level height; At an oil level height of h j Under the condition of, total power density enhancement factor The calculation formula is: At an oil level height of h j Under the condition of, the total equivalent power density of the motor The calculation formula is: ； In the formula, P sn For speed v sn The corresponding motor output power P sn ; t sn For speed v sn The proportion of total navigation time of underwater equipment; The oil level is h. j Down, speed v sn The corresponding power density enhancement factor; The oil level is h. j Down, speed v sn The corresponding equivalent power density of the motor.

7. The design method for the underwater motor oil cooling system according to claim 6, characterized in that, It also includes step 7: In step 6, when selecting the optimal solution, if none of the design sample points retained in step 4 meet the actual working conditions, return to step 3 to refine the oil level height selection step size and redesign until a solution that meets the actual working conditions can be designed.

8. An underwater motor, comprising a motor body and an oil cooling system; the motor body includes a motor housing; characterized in that: The oil cooling system is an oil agitation cooling system, comprising cooling oil filled in the motor housing; the cooling oil is agitated by the rotor assembly of the motor body and splashed onto the components in the motor housing for cooling; the cooling oil falls back to the bottom of the motor housing and exchanges heat with the outside seawater through convection between the motor housing and the outer shell of the underwater equipment, or the cooling oil undergoes convection heat exchange through auxiliary heat exchange equipment; the oil level / filling volume of the cooling oil is determined according to any one of the design methods described in claims 1-7.

9. The underwater motor according to claim 8, characterized in that: The motor housing is the outer shell of the underwater equipment; the cooling oil falls back to the bottom of the outer shell of the underwater equipment and exchanges heat with the outside seawater through the outer shell of the underwater equipment.

10. Underwater equipment, characterized in that: The underwater motor described in claim 8 or 9 is used as its power system.

Images