A thermal management method and calculation method for a wheel hub electro-hydraulic coupling driving device

Abstract

The application discloses a kind of thermal management methods and calculation methods of wheel hub electro-hydraulic coupling driving device, comprising: the wheel hub electro-hydraulic coupling driving device includes: liquid drive unit and electric drive unit, wherein liquid drive unit includes: pump motor, first oil inlet, first oil outlet, leakage oil port, electric drive unit includes: rotor, stator, inner shell, outer shell, second oil inlet, second oil outlet, inner shell covers liquid drive unit, and second oil inlet and second oil outlet are respectively arranged on outer shell;The thermal management method of the wheel hub electro-hydraulic coupling driving device includes the following steps: based on pump motor, oil liquid sequentially passes through first oil inlet, leakage oil port, inner shell, forms cooling circuit;Based on stator and rotor, oil liquid sequentially passes through first oil outlet, outer shell, second oil inlet, second oil outlet, forms cooling and heat dissipation process.The application increases the driving power of system, solves the heat dissipation problem of coupling driving device, improves the operating efficiency of drive assembly.

Description

Technical Field

[0001] This invention belongs to the field of vehicle electro-hydraulic coupling drive technology, and particularly relates to a thermal management method and calculation method for a wheel hub electro-hydraulic coupling drive device. Background Technology

[0002] Hub drive technology integrates the power unit, transmission unit, and braking unit into the hub, greatly simplifying the mechanical parts of the vehicle. It has the advantages of high integration, small size, and high power density, and represents a new direction in the development of vehicle drive technology.

[0003] Patent ZL2023106136644 proposes a disc-type hub motor for automobiles, which achieves cooling of the stator windings by creating through holes in the stator windings and installing heat dissipation pipes in the through holes. Patent CN2024100713939 proposes an integrated cooler for hub motors, which can achieve more uniform cooling of the entire hub motor. The hub drive assembly of the above solutions uses an external rotor motor drive. Although the connection between the rotor and the hub achieves hub motor cooling, a large amount of space inside the stator is wasted. Patent ZL2022104171742 proposes a hub electro-hydraulic composite drive assembly and control method, which effectively utilizes the internal space of the motor and adds hydraulic drive components without increasing the system volume. This solution has a high degree of space integration, but the feasibility of its cooling and heat dissipation scheme is not demonstrated.

[0004] Preliminary research revealed that there is currently no feasibility study on cooling and heat dissipation solutions for hub electro-hydraulic hybrid drive devices. This means that the effectiveness of relevant hub motor structural designs needs to be verified through temperature rise characteristic calculations before a suitable cooling and heat dissipation solution can be developed and applied to engineering practice. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention proposes a thermal management method and calculation method for a hub electro-hydraulic coupling drive device, thereby resolving the issues present in the prior art.

[0006] To achieve the above objectives, on the one hand, the present invention provides a thermal management method for a hub electro-hydraulic coupling drive device, the hub electro-hydraulic coupling drive device comprising: a hydraulic drive unit and an electric drive unit, wherein the hydraulic drive unit comprises: a pump motor, a first oil inlet, a first oil outlet, and a leakage oil outlet, and the electric drive unit comprises: a rotor, a stator, an inner housing, an outer housing, a second oil inlet, and a second oil outlet, the inner housing covering the hydraulic drive unit, and the second oil inlet and the second oil outlet being respectively provided on the outer housing;

[0007] The thermal management method of the hub electro-hydraulic coupling drive device includes the following steps:

[0008] Based on the pump motor, the oil flows sequentially through the first oil inlet, the oil leakage port, and the inner housing to form a cooling circuit;

[0009] Based on the stator and the rotor, the oil sequentially passes through the first oil outlet, the outer casing, the second oil inlet, and the second oil outlet, forming a cooling and heat dissipation process.

[0010] Preferably, the process of forming a cooling circuit includes:

[0011] Based on the heat generated by the pump motor, oil is drawn from the oil tank through the first oil inlet to obtain the first thermal parameter; the oil flows to the leaking oil port and the first oil outlet respectively to obtain the second thermal parameter and the third thermal parameter respectively; the oil from the leaking oil port flows into the inner shell to cool the inner shell, and the oil flows into the oil tank along with the inner shell.

[0012] Preferably, the cooling and heat dissipation process includes:

[0013] Based on the electromagnetic heating generated by the stator and the rotor, the oil flowing through the first oil outlet into the second oil inlet on the outer casing yields a fourth thermal parameter; the oil in the second oil inlet flows back to the oil tank through the second oil outlet, yielding a fifth thermal parameter, wherein there is convective heat exchange between the outer casing and the air.

[0014] Preferably, the outer surface of the stator is provided with grooves, which are filled with cooling oil to enhance the cooling effect.

[0015] On the other hand, the present invention also provides a calculation method for a hub electro-hydraulic coupling drive device, based on the thermal management method of the hub electro-hydraulic coupling drive device, the calculation method comprising:

[0016] Based on the aforementioned hub electro-hydraulic coupling drive device, a lumped parameter thermal resistance network model with several nodes is established.

[0017] Based on the thermodynamic relationships between several nodes, the differential equations of the thermodynamic model for several nodes are obtained;

[0018] Based on the differential equations of the aforementioned nodes, the temperature variation law of the nodes over time is obtained; wherein the aforementioned nodes include: pump motor fluid node, first oil outlet fluid node, leakage oil outlet fluid node, second oil inlet fluid node, and outer casing mass node.

[0019] Preferably, the differential equation of the thermodynamic model of the pump motor fluid node is:

[0020]

[0021] Where, m tWhere D is the mass of oil at the first inlet, and V is the pump displacement. t Let α be the volume of the first inlet oil. p ρ is the coefficient of volumetric expansion of the oil, cp is the density of the oil, υ is the specific heat capacity of the oil at constant pressure, and ω is the specific volume of the oil.

[0022] Preferably, the differential equation of the thermodynamic model of the first oil outlet fluid node is:

[0023]

[0024]

[0025] Where, m p V represents the oil mass at the first outlet. p L represents the volume of oil at the first outlet. p The viscous frictional power loss P of the hydraulic drive unit per revolution v Stirring loss P j and leakage loss P q sum.

[0026] Preferably, the differential equation of the thermodynamic model of the fluid node at the leaking oil port is:

[0027]

[0028] Where, m l For the quality of the oil at the leak point, k fw Let A be the heat transfer coefficient between the oil inside the pump motor housing and the housing itself. fw V represents the heat exchange area between the oil inside the pump motor housing and the housing itself. l The volume of oil at the leak point.

[0029] Preferably, the differential equation of the thermodynamic model for the second inlet fluid node is:

[0030]

[0031]

[0032]

[0033] Where, m j V represents the oil mass at the second inlet. j L represents the volume of oil at the second inlet. t The damping throttling loss P per revolution of the hydraulic drive unit zn L m The electromagnetic heat loss P per revolution of the electric drive unit e .

[0034] Preferably, the differential equation of the thermodynamic model of the outer shell mass node is:

[0035]

[0036] L c =ωD(p p -p t )(1-η′ m ) / η′ m (9)

[0037] Where, m w c represents the oil mass of the outer casing. w K is the specific heat capacity of the outer shell. wa A is the heat transfer coefficient between the outer shell and the environment. wa L is the heat exchange area between the outer casing and the environment. c η′ represents the mechanical loss generated per revolution of the hydraulic drive unit. m This represents the volumetric efficiency of the liquid drive unit.

[0038] Compared with the prior art, the present invention has the following advantages and technical effects:

[0039] This invention simplifies the structural design of the hub electro-hydraulic coupling drive device and saves space by enclosing the hydraulic drive unit within the inner housing of the electric drive unit. Utilizing the advantages of the hydraulic drive unit's high low-speed driving torque and the electric drive unit's high high-speed power, it improves the efficiency and adaptability of the entire drive device, thereby increasing fault tolerance and power density. This invention also incorporates a cooling circuit connecting the hydraulic drive unit's oil outlet to the electric drive unit's housing, proposing a thermal management scheme for the drive device. This allows the hydraulic oil to cool the motor stator and inner housing while driving the hydraulic motor, increasing the drive motor's operating time and driving power without increasing system size, thus improving the overall drive assembly's operating efficiency and solving the heat dissipation problem of the coupling drive device.

[0040] Based on the thermal management scheme of the drive device, this invention also establishes a calculation method for thermal management, which can obtain the temperature field of key nodes. This method can be used to analyze the influence of factors such as rotational speed, lubrication flow rate, and pressure of the proposed electro-hydraulic coupling drive device on thermal equilibrium time and temperature, and provide a theoretical model for the optimized design of the drive device structure and optimal operating conditions. Attached Figure Description

[0041] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. In the drawings:

[0042] Figure 1 This is a schematic diagram of the hub electro-hydraulic coupling drive device according to an embodiment of the present invention;

[0043] Figure 2 This is a flowchart of the thermal management method according to an embodiment of the present invention;

[0044] Figure 3 This is a schematic diagram of the thermal balance characteristics under low-speed operating conditions according to an embodiment of the present invention.

[0045] Figure 4 This is a schematic diagram of the thermal balance characteristics under high-speed operating conditions according to an embodiment of the present invention;

[0046] Among them, A is the hydraulic drive unit; B is the electric drive unit; C is the mechanical structure unit; 1 is the first oil inlet; 2 is the first oil outlet; 3 is the leakage port; 4 is the inner shell; 5 is the rotor; 6 is the stator; 7 is the outer shell; 8 is the second oil inlet; 9 is the second oil outlet; 10 is the motor power output shaft; and 11 is the pump motor. Detailed Implementation

[0047] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0048] It should be noted that the steps shown in the flowchart in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions, and although a logical order is shown in the flowchart, in some cases the steps shown or described may be executed in a different order than that shown here.

[0049] Example 1

[0050] like Figure 1 As shown, this embodiment provides a hub electro-hydraulic coupling drive device, including: a hydraulic drive unit A, an electric drive unit B, and a mechanical structure unit C.

[0051] The hydraulic drive unit A mainly includes an integrated pump motor 11, a first oil inlet 1, a first oil outlet 2, a leakage oil outlet 3, and a motor power output shaft 10 (connected to the mechanical structure unit C via a spline).

[0052] The electric drive unit B includes an inner housing 4, a rotor 5, a stator 6, and an outer housing 7. The rotor 5 is connected to the rotating component of the mechanical structure unit C. The outer surface of the stator 6 is provided with grooves containing cooling oil. The outer housing 7 has a second oil inlet 8 and a second oil outlet 9 for the cooling oil.

[0053] The liquid drive unit A is enclosed by the inner shell 4 of the electric drive unit B.

[0054] This embodiment proposes a thermal management method for the above-mentioned structural features, such as... Figure 2 As shown, it includes:

[0055] S1, based on the pump motor, the oil sequentially passes through the first oil inlet, the oil leakage port, and the inner shell to form a cooling circuit;

[0056] S2, based on the stator and the rotor, the oil sequentially passes through the first oil outlet, the outer casing, the second oil inlet, and the second oil outlet to form a cooling and heat dissipation process.

[0057] In this embodiment, the process of forming a cooling circuit includes: based on the heat generated by the pump motor, oil is drawn from the oil tank through the first oil inlet to obtain a first thermal parameter; the oil flows to the leaking oil port and the first oil outlet respectively to obtain a second thermal parameter and a third thermal parameter respectively; the oil from the leaking oil port flows into the inner shell to cool the inner shell, and the oil flows into the oil tank along with the inner shell.

[0058] Specifically, the hydraulic drive unit A operates, and the pump motor 11 generates heat. The pump motor 11 draws oil from the oil tank through the first oil inlet 1, with a flow rate of Q. il Oil temperature is T in The motor drives the mechanical structure unit C to work, at which time the temperature of the pump motor 11 is T. t The oil pressure is p t The oil flows to the leak port 3 (oil temperature is T). l The oil pressure is p l The traffic is Q el ) and the first oil outlet 2 (oil temperature is T) p The oil pressure is p p The traffic is Q j The oil from the leak port 3 flows into the inner housing 4 of the electric drive unit B, cooling the inner housing 4; then it flows into the oil tank along with the inner housing 4.

[0059] In this embodiment, the cooling and heat dissipation process includes: based on the electromagnetic heat generation of the stator and the rotor, the oil flowing through the first oil outlet into the second oil inlet on the outer casing to obtain a fourth thermal parameter; the oil in the second oil inlet flowing back into the oil tank through the second oil outlet to obtain a fifth thermal parameter, wherein there is convective heat exchange between the outer casing and the air.

[0060] Specifically, when electric drive unit B operates, the stator and rotor generate electromagnetic heat. Oil from the outlet 2 of hydraulic drive unit A flows into the second inlet 8 of the housing 7 of hydraulic drive unit B (oil temperature T). j Then it flows back to the oil tank from the second outlet 9 (shell temperature T). w The outer casing 7 undergoes convective heat transfer with the air, and the air temperature is T. a .

[0061] Example 2

[0062] This embodiment simplifies the heat transfer components based on the thermal management scheme of an oil-driven electro-hydraulic coupling device and proposes a thermal balance calculation method based on a lumped-parameter thermal resistance network model. The model consists of five nodes, including four fluid nodes and one mass node. (Pump motor 11 fluid node T) t Oil outlet 2 fluid node T p Leaking oil port 3 fluid node T l 8-port fluid node T j 7 mass nodes of the outer shell T w .

[0063] Thermodynamic model differential equation for first oil inlet 1:

[0064]

[0065] In the formula, m t Let D be the mass of oil at the first inlet 1, D be the pump displacement, and V be the displacement of the pump. t Let α be the volume of oil at the first oil inlet 1. p ρ is the coefficient of volumetric expansion of the oil, cp is the density of the oil, υ is the specific heat capacity of the oil at constant pressure, and ω is the specific volume of the oil.

[0066] The differential equation for the thermodynamic model of the first oil outlet 2 is:

[0067]

[0068] In the formula, m p V represents the mass of the oil at the first oil outlet 2. p L represents the volume of oil at the first oil outlet 2. p The viscous frictional power loss P of the hydraulic drive unit per revolution v Stirring loss P j and leakage loss P q sum:

[0069]

[0070] The thermodynamic differential equation for leak port 3 is:

[0071]

[0072] In the formula, m l For the oil mass at leak port 3, k fw Let A be the heat transfer coefficient between the oil inside the pump motor housing and the housing itself. fw V represents the heat exchange area between the oil inside the pump motor housing and the housing itself. l The volume of oil at the leak port 3.

[0073] The thermodynamic differential equation for the second oil inlet 8 is:

[0074]

[0075] In the formula, m j V represents the oil mass at the second oil inlet 8. j The volume of oil at the second oil inlet 8 is L. t The damping throttling loss P per revolution of the hydraulic drive unit zn L m The electromagnetic heat loss P per revolution of the electric drive unit e :

[0076]

[0077]

[0078] The differential equation of the thermodynamic model of the outer shell 7 is:

[0079]

[0080] In the formula, m w c is the mass of the oil in the outer casing 7. w The specific heat capacity of the outer shell 7, k wa A is the heat transfer coefficient between the outer casing 7 and the environment. wa L represents the heat exchange area between the outer casing 7 and the environment. c Mechanical losses per revolution of the hydraulic drive unit:

[0081] L c =ωD(p p -p t )(1-η′ m ) / η′ m (9)

[0082] In the formula, η′ m Volumetric efficiency of the hydraulic drive unit

[0083] Solve the simultaneous equations (1-9) to find the fluid node T of the pump motor 11. t First oil outlet 2 fluid node T p Leaking oil port 3 fluid node T l Second oil inlet 8 fluid node T j 7 mass nodes of the outer shell T w Thus, the changing pattern of the above nodes over time was obtained.

[0084] In this embodiment, the parameter values ​​are: cp = 1870 J / (kg·℃); c w =460J / (kg·℃); ρ=820kg / m3; α p=0.00035; D=35.6·10-6; L t =3000W; L m =450W; L c =200W; k fw =500W / (m2·℃); k wa =350W / (m2·℃); A fw =0.5m2; A wa =2m2;T a =T in =22℃.

[0085] 1. When the output speed of mechanical structure unit C is 50 rpm, the corresponding speeds of hydraulic drive unit A and electric drive unit B are 537 rpm and 194 rpm, respectively, and their thermal balance characteristics are as follows: Figure 3 As shown. The drive unit needs to work for about 700 seconds to reach equilibrium. The oil equilibrium temperatures of the pump motor 11, the first oil outlet 2, and the leakage oil outlet 3 are 23.97℃, 25.65℃, and 36.22℃, respectively; the equilibrium temperatures of the second oil inlet 8 and the outer casing 7 are 42.75℃ and 36.12℃, respectively.

[0086] 2. When the output speed of mechanical structure unit C is 200 rpm, the corresponding speeds of the hydraulic drive unit and the electric drive unit are 2148 rpm and 775 rpm, respectively, and their thermal balance characteristics are as follows: Figure 4 As shown. The temperature of each node reaches equilibrium after about 200 seconds of operation. The oil equilibrium temperatures of pump motor 11, first oil outlet 2, and leakage oil outlet 3 are 24℃, 26.19℃, and 78.69℃, respectively; the equilibrium temperatures of second oil inlet 8 and outer casing 7 are 78.42℃ and 81.82℃, respectively.

[0087] The above are merely preferred embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A thermal management method for a hub electro-hydraulic coupling drive device, characterized in that, The hub electro-hydraulic coupling drive device includes a hydraulic drive unit and an electric drive unit. The hydraulic drive unit includes a pump motor, a first oil inlet, a first oil outlet, and a leakage oil outlet. The electric drive unit includes a rotor, a stator, an inner housing, an outer housing, a second oil inlet, and a second oil outlet. The inner housing covers the hydraulic drive unit, and the second oil inlet and the second oil outlet are respectively provided on the outer housing. The thermal management method of the hub electro-hydraulic coupling drive device includes the following steps: Based on the pump motor, the oil flows sequentially through the first oil inlet, the oil leakage port, and the inner housing to form a cooling circuit; Based on the stator and the rotor, the oil sequentially passes through the first oil outlet, the outer casing, the second oil inlet, and the second oil outlet, forming a cooling and heat dissipation process.

2. The thermal management method for the hub electro-hydraulic coupling drive device according to claim 1, characterized in that, The process of forming a cooling circuit includes: Based on the heat generated by the pump motor, oil is drawn from the oil tank through the first oil inlet to obtain the first thermal parameter; the oil flows to the leaking oil port and the first oil outlet respectively to obtain the second thermal parameter and the third thermal parameter respectively; the oil from the leaking oil port flows into the inner shell to cool the inner shell, and the oil flows into the oil tank along with the inner shell; The first thermal parameter includes flow rate. Oil temperature The pump motor temperature is The oil pressure is The second thermal parameter includes oil temperature. Hydraulic ,flow The third thermal parameter includes oil temperature. The oil pressure is Traffic volume .

3. The thermal management method for the hub electro-hydraulic coupling drive device according to claim 1, characterized in that, The cooling and heat dissipation process includes: Based on the electromagnetic heating of the stator and the rotor, the oil flowing through the first oil outlet into the second oil inlet on the outer casing yields a fourth thermal parameter; the oil in the second oil inlet flows back to the oil tank through the second oil outlet, yielding a fifth thermal parameter, wherein there is convective heat exchange between the outer casing and the air. The fourth thermal parameter is oil temperature. The fifth thermal parameter is the shell temperature. .

4. The thermal management method for the hub electro-hydraulic coupling drive device according to claim 1, characterized in that, The outer surface of the stator is provided with grooves, which are filled with cooling oil to enhance the cooling effect.

5. A calculation method for a hub electro-hydraulic coupling drive device, characterized in that, The thermal management method for the hub electro-hydraulic coupling drive device according to any one of claims 1-4 includes the following calculation method: Based on the aforementioned hub electro-hydraulic coupling drive device, a lumped parameter thermal resistance network model with several nodes is established. Based on the thermodynamic relationships between several nodes, the differential equations of the thermodynamic model for several nodes are obtained; Based on the differential equations of the aforementioned nodes, the temperature change law of the aforementioned nodes over time is obtained; wherein the aforementioned nodes include: pump motor fluid node, first oil outlet fluid node, leakage oil outlet fluid node, second oil inlet fluid node, and outer casing mass node.

6. The calculation method for the hub electro-hydraulic coupling drive device according to claim 5, characterized in that, The differential equation for the thermodynamic model of the pump motor fluid node is: （1） in, Where is the mass of oil at the first inlet, and D is the pump displacement. The volume of oil at the first inlet. ρ is the volumetric expansion coefficient of the oil, cp is the oil density, cp is the specific heat capacity of the oil at constant pressure, υ is the specific volume of the oil, and ω is the rotational speed of the hydraulic drive unit.

7. The calculation method for the hub electro-hydraulic coupling drive device according to claim 5, characterized in that, The thermodynamic model differential equation for the first oil outlet fluid node is: (2) (3) in, The quality of the oil at the first outlet. The volume of oil at the first outlet. Viscous frictional power loss per revolution of the hydraulic drive unit Stirring loss and leakage losses sum.

8. The calculation method for the hub electro-hydraulic coupling drive device according to claim 5, characterized in that, The differential equation for the thermodynamic model of the fluid node at the leaking oil port is: (4) in, For the quality of the oil at the leaking port, The heat transfer coefficient between the oil inside the pump motor housing and the housing itself. This refers to the heat exchange area between the oil inside the pump motor housing and the housing itself. The volume of oil at the leak point.

9. The calculation method for the hub electro-hydraulic coupling drive device according to claim 5, characterized in that, The differential equation of the thermodynamic model for the second inlet fluid node is: (5) (6) (7) in, The quality of the oil at the second inlet. The volume of oil at the second inlet. Damping throttling loss per revolution of the hydraulic drive unit , Electromagnetic heat loss per revolution of the electric drive unit .

10. The calculation method for the hub electro-hydraulic coupling drive device according to claim 5, characterized in that, The differential equation for the thermodynamic model of the outer shell mass node is: (8) (9) in, For the oil mass of the outer shell, The specific heat capacity of the outer shell. The heat transfer coefficient between the outer shell and the environment. This refers to the heat exchange area between the outer casing and the environment. This refers to the mechanical losses generated per revolution of the hydraulic drive unit. This represents the volumetric efficiency of the liquid drive unit.

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