Motor

Abstract

An electric machine comprising: a hollow drive shaft for supporting a rotor rotatable relative to a stator, the drive shaft being rotatably supported in a housing about an axis of rotation; and a hydraulic system for circulating a fluid having a supply line leading to the axial bore of the drive shaft.

Description

Technical Field

[0001] The present application relates to an electric motor comprising: a hollow drive shaft for supporting a rotor rotatable relative to a stator, the drive shaft being rotatably supported in a housing around a rotation axis; and a hydraulic system for circulating a fluid inside the housing, the hydraulic system having a supply line leading to an axial hole of the drive shaft. Background Art

[0002] A cooling system for a rotating electric machine used to drive a vehicle is known from US2019 / 0081537A1. The cooling system includes a first pump and a second pump, the first pump being driven as the vehicle travels to supply lubricant to the rotating electric machine, the second pump being driven by a second drive source to supply lubricant to the rotating electric machine. The first pump is configured to supply lubricant to the inside of a rotating shaft of a rotor core of the rotating electric machine through a first passage. The second pump is configured to supply lubricant to a coil of a stator of the rotating electric machine through a second passage.

[0003] WO2015 / 058788A1 discloses a drive assembly for a motor vehicle, the drive assembly having a first gear and a second gear drivingly connected to each other, and a lubricant filling device, which defines a lubricant level in a static built-in state of the drive assembly. A first reservoir is arranged above the lubricant level, which can be filled with lubricant due to the rotation of the first gear. A second reservoir is arranged above the lubricant level, which can be filled with lubricant due to the rotation of the second gear. The first reservoir is used to lubricate a first bearing area, and the second reservoir is used to lubricate a second bearing area of ​​the drive assembly.

[0004] CN111441926A discloses a hybrid transmission drive motor cooling electric oil pump system and control method. The system includes a suction filter, an oil pump, an oil pump motor and an oil pump motor controller, wherein the suction filter is used to suck oil at the bottom of the hybrid transmission; the oil pump is used to pump out the oil sucked by the suction filter; and the oil pump motor is used to provide speed and torque for the oil pump, supply power to the oil pump, and supply oil as a cooling medium to the hybrid transmission.

[0005] CN107565756A discloses an oil pump motor, a gearbox and a vehicle; the oil pump motor includes the following units: a housing having an oil inlet and an oil outlet; a motor and an oil pump, the motor and the oil pump are arranged in the housing, wherein the motor is used to drive the oil pump, the oil pump is provided with an oil inlet chamber and an oil outlet chamber connected to each other, and the oil outlet chamber is connected to the oil outlet; a cooling channel, the cooling channel is arranged in the housing and outside the motor and the oil pump, the cooling channel wall is in contact with the motor and the oil pump, the cooling channel has an inlet and an outlet, the inlet is connected to the oil inlet, and the outlet is connected to the oil inlet chamber. The gearbox oil liquid circulates in the oil pump motor and flows in the cooling channel; the cooling channel wall is in contact with the motor and the oil pump, so the gearbox oil liquid in the cooling channel can cool the motor and the oil pump, thereby providing cooling and heat radiation effects without immersing the oil pump motor in the gearbox oil liquid.

[0006] The performance of electric motors is thermally limited in operation. Intrinsic losses may occur in the copper, iron and magnets of electric motors, where the material properties limit the temperature of the corresponding components and structures. Effective cooling is necessary to achieve adequate performance. However, if the cooling fluid is delivered uniformly independent of the speed or operating point of the motor, the efficiency is negatively affected due to churning losses in the motor and / or the gearbox. Therefore, direct oil cooling solutions for active parts require complex hydraulic circuits to provide sufficient pressure and flow rate of the oil. Summary of the invention

[0007] An object may be to propose an electric machine with an efficient and less complex hydraulic system for cooling the electric machine.

[0008] This object is achieved by an electric machine according to claim 1. Embodiments are described in the dependent claims.

[0009] The motor comprises: a hollow drive shaft for supporting a rotor rotatable relative to a stator, the drive shaft being rotatably supported in a housing about a rotation axis; and a hydraulic system for circulating a fluid, having a supply line leading to an axial hole of the drive shaft. A control valve is arranged in the axial hole for controlling the flow of the fluid entering the drive shaft, the control valve being actuated by centrifugal force.

[0010] The centrifugal force acting on the control valve inside the rotating drive shaft will advantageously open and close the valve depending on the rotational speed of the drive shaft. The control valve is a low complexity mechanical component that allows for effective control of the flow of fluid entering the drive shaft. At low rotational speeds, the closed control valve reduces the flow rate, thereby reducing the churning losses of the motor. At high rotational speeds, the control valve opens and increases the flow rate, which can further result in a reduction in the fluid level in the gearbox, potentially reducing the churning losses of the gears at high speeds. The drive shaft includes radial holes connecting the axial holes to the rotor.

[0011] According to an embodiment, the control valve has a plurality of cantilever beams arranged circumferentially around the axis of rotation and connected to a ring fitted into the axial hole, the cantilever beams being axially biased inwards. The centrifugal force pushes the cantilever beams radially outwards. The cantilever beams may form a nozzle having an orifice for the flow of a fluid, wherein the area of ​​the orifice depends on the respective position of the cantilever beams. The area of ​​the orifice increases with increasing rotational speed of the drive shaft.

[0012] According to a further embodiment, at a rotational speed of the drive shaft of 0 RPM, the oil flow rate through the control valve is between 0% and 20% of a reference oil flow rate through the axial hole without the control valve. For example, the oil flow rate through the control valve at 0 RPM is 10% of the reference oil flow rate. The reference oil flow rate is the flow rate through the axial hole without the control valve that occurs when all other parameters (such as pressure, density or temperature) are the same. The rotational speed of the drive shaft may also be the same, although it does not affect the reference oil flow rate. A person skilled in the art knows that at low rotational speeds of the drive shaft, the oil flow rate is significantly reduced. For example, at a rotational speed of the drive shaft of 20% of the maximum rotational speed, the oil flow rate through the control valve may be between 15% and 25% of the reference oil flow rate. At the maximum rotational speed of the drive shaft, the oil flow rate through the control valve is greater than 75%, for example about 80%, of the reference oil flow rate through the axial hole (18) without the control valve.

[0013] According to another embodiment, the area of ​​the orifice is composed of a radial orifice area and a longitudinal orifice area. The area of ​​the orifice at a rotational speed of the drive shaft of 0 revolutions per minute (RPM) may be between 0% and 2% of the cross-sectional area of ​​the axial hole. The area of ​​the orifice at the maximum rotational speed of the drive shaft may be greater than 5%, in particular greater than 10%, of the cross-sectional area of ​​the axial hole. The radial orifice area is a circular opening formed at the free end of the cantilever beam in a plane perpendicular to the axis of rotation. The longitudinal orifice area is formed by a tapered groove between the cantilever beams. The diameter of the radial orifice area can be increased by 15% to 25% of the axial length of the cantilever beam from 0 RPM to the maximum rotational speed of the drive shaft. A longer cantilever beam provides an increase in the total area of ​​the orifice.

[0014] According to a further embodiment, each of the cantilever beams comprises a balancing weight at the terminal end. In particular, the cantilever beams may each have a resilient section formed from a flat material and connected to the ring, and a head section forming the balancing weight. The head section may have a higher mass than the resilient section, in particular at least 1.5 times the mass of the resilient section.

[0015] According to a further embodiment, the resilient section has a neck portion, wherein the flat material of the neck portion is wavy, having at least one S-shape. The crests and troughs of the wavy waveform or S-shape extend circumferentially relative to the axial direction. The flat material of the neck portion may have a plurality of S-shapes in series. The higher the number of S-shapes, the lower the stress and the larger the resulting area of ​​the orifice.

[0016] According to a further embodiment, the hydraulic system has a fluid reservoir, and the supply line hydraulically connects the fluid reservoir and the axial bore. The fluid reservoir can provide a constant fluid pressure, which can be maintained by a pump. The fluid reservoir can be located at a higher position than the axial bore relative to the direction of gravity, thereby allowing the fluid to be passively delivered to the axial bore. In particular, the fluid can be delivered to the fluid reservoir via a rotating element of the motor, in particular from an oil tank to the fluid reservoir via a gear of a transmission connected to the drive shaft. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Embodiments of the electric machine will be illustrated with reference to the accompanying drawings, in which:

[0018] Figure 1 An embodiment of the electric machine is shown in longitudinal section with the control valve in the closed position;

[0019] Figure 2 Show Figure 1 Details of B;

[0020] Figure 3 Shown from different perspectives Figure 1 Details of B;

[0021] Figure 4 Show Figure 1 An embodiment wherein the control valve is in an open position;

[0022] Figure 5 Show Figure 4 Details of C;

[0023] Figure 6 Shown from different perspectives Figure 4 Details of C;

[0024] Figure 7 A further embodiment of an electric machine is shown in longitudinal section;

[0025] Figure 8 Show Figure 7 Details of D;

[0026] Fig. 9 A further embodiment of an electric machine is shown in longitudinal section;

[0027] Fig.10 A further embodiment of an electric machine is shown in longitudinal section;

[0028] Fig.11 A further embodiment of the electric machine is shown in a cross-sectional perspective view;

[0029] Fig.12 The control valve is shown in three different positions. DETAILED DESCRIPTION

[0030] exist Figure 1 , an embodiment of an electric machine is depicted in a longitudinal section. The electric machine comprises a hollow drive shaft 11 for supporting a rotor 10 rotatable relative to a stator 17, the drive shaft 11 being rotatably supported in a housing 1 about an axis of rotation A. The rotor 10 is fixed to the drive shaft 11 and rotates inside the stator 17 connected to the housing 1. The hydraulic system for circulating a fluid has a supply line 14 leading to an axial bore 18 of the drive shaft 11. Inside the axial bore 18, a control valve 12 is arranged, which controls the flow of the fluid entering the drive shaft 11. The fluid flows from the axial bore 18 through the radial bores 16 to the rotor 10. The control valve 12 is actuated by centrifugal force.

[0031] The control valve 12 is in the closed position. Figure 2 and Figure 3 Detail B of a control valve 12 in a closed position is schematically illustrated in different views. The control valve 12 has a plurality of cantilever beams 2 which are arranged circumferentially around the axis of rotation A and connected to a ring 8 which fits into an axial bore 18. The cantilever beams 2 are axially biased inwardly towards the closed position, which Figure 2 and Figure 3 Shown in.

[0032] exist Figure 4 In Figure 1 In the embodiment of the invention, the control valve 12 is in the open position. Figure 5 and Figure 6 Detail C of a control valve 12 in an open position is schematically illustrated in different views. The centrifugal force pushes the cantilever beam 2 radially outwards, thereby gradually opening the control valve 12. The cantilever beam 2 substantially forms a nozzle with an orifice for the flow of a fluid, wherein the area of ​​the orifice depends on the respective position of the cantilever beam 2. The area of ​​the orifice consists of a radial orifice area 3 and a longitudinal orifice area 4. The radial orifice area 3 is a circular opening in a plane perpendicular to the axis of rotation formed at the free end of the cantilever beam 2. The longitudinal orifice area 4 is formed as a tapered groove between the cantilever beams 2. As the rotation speed of the drive shaft 11 increases, the area of ​​the orifice increases from 0.04 to 0.06. Figure 2 and Figure 3 The closed position of the cantilever beam 2 is continuously increased to the open position of the cantilever beam 2, such as Figure 5 and Figure 6. The illustration of the control valve 12 is schematic. In the closed position of the cantilever beam 2, i.e. at a rotational speed of the drive shaft of 0 RPM, the area of ​​the orifice may be between 0% and 2% of the cross-sectional area of ​​the axial bore 18. In the maximum open position of the cantilever beam 2, i.e. at the maximum rotational speed of the drive shaft, the area of ​​the orifice may be greater than 5%, in particular greater than 10%, of the cross-sectional area of ​​the axial bore 18. Depending on the control valve design, up to 20% of the cross-sectional area of ​​the axial bore 18 is feasible.

[0033] exist Figure 7 , a further embodiment of an electric machine is shown in longitudinal section. The electric machine is partially depicted through a housing 1 and a portion of a hollow drive shaft 11. The rotor and the stator have been omitted. Figure 8 Detail D is shown in FIG, which shows a closed control valve 12 inside the axial bore 18, which controls the flow of fluid from the supply line 14. Each of the cantilever beams 2 comprises a balancing weight 5 at the terminal end 6. Furthermore, each of the cantilever beams 2 has a resilient section 7 formed of a flat material and connected to the ring 8. The head section 9 forms the balancing weight 5. The head section 9 may have a higher mass than the resilient section 7, in particular at least 1.5 times the mass of the resilient section 7. The resilient section 7 has a neck portion 19, wherein the flat material of the neck portion 19 has a wave shape or S-shape that facilitates the opening of the control valve 12.

[0034] exist Fig. 9 , a further embodiment of the motor is shown in longitudinal section. The motor is partially depicted by the hollow drive shaft 11. A control valve 12 inside the axial bore 18 controls the flow of fluid from the supply line 14. The hydraulic system has a fluid reservoir 15, which is hydraulically connected to the axial bore 18 via the supply line 14.

[0035] exist Fig.10 , a further embodiment of the motor is shown in longitudinal section. The motor is partially depicted through a portion of the housing 1 and the hollow drive shaft 11. A control valve 12 inside the axial bore 18 controls the flow of fluid from the supply line 14. A fluid reservoir 15 is located outside the housing 1, in a position higher than the axial bore 18 relative to the direction of gravity, to passively deliver the fluid.

[0036] exist Fig.11 , a further embodiment of the motor is shown in a cross-sectional perspective view. The motor is partially depicted by a portion of the housing 1 and the hollow drive shaft 11. A control valve 12 inside the axial bore 18 controls the flow of fluid from the supply line 14. A fluid reservoir 15 is integrated into the housing 1 in a position higher than the axial bore 18 relative to the direction of gravity to passively convey the fluid. The fluid can be conveyed to the fluid reservoir 15 by a rotating element of the motor, in particular from an oil tank to the fluid reservoir 15 through a gear of a transmission connected to the drive shaft 11.

[0037] exist Fig.12 , an exemplary embodiment of a control valve 12 is depicted in three different positions about its orifice opening, each position being shown in two side views. Position I is the maximum closed position, in which the control valve 12 has the lowest possible orifice opening formed by the radial orifice area 3 and the longitudinal orifice area 4. When the motor is stationary, the control valve 12 actuated by centrifugal force is in position I. The radius at the terminal end 6 is 8.3 mm. The radial orifice area 3 has a diameter of 2.2 mm, corresponding to a diameter of 3.8 mm. 2 The longitudinal orifice region 4 consists of eight slots and has an area comparable to the radial orifice region 3. The area of ​​the orifice in the closed position I of the cantilever beam 2 is about 1% of the cross-sectional area of ​​the axial bore 18 of the drive shaft 11, not depicted. At a rotational speed of the drive shaft of 0 RPM, under other identical parameters such as pressure, density or temperature, the oil flow rate through the control valve 12 may be 10% of the reference oil flow rate through the axial bore 18 without the control valve 12.

[0038] Position II is a slightly more open position in which the centrifugal force of about 3,000 RPM acting on the cantilever beam 2 is balanced by the biasing force pushing the cantilever beam 2 inwardly toward position I. The radius at the distal end 6 is 0.65 mm higher than the 8.3 mm of position I. The radial aperture region 3 has a diameter of 3.4 mm, corresponding to a radius of 9.1 mm. 2 At a rotational speed of the drive shaft of 3,000 RPM, which may be 20% of the maximum rotational speed, the oil flow rate through the control valve 12 may be 20% of a reference oil flow rate that is not affected by the rotational speed.

[0039] Position III is a significantly more open position in which the centrifugal force of about 15,000 RPM acting on the cantilever beam 2 is balanced by the biasing force pushing the cantilever beam 2 inward toward position I. The radius at the distal end 6 is 3.4 mm higher than the 8.3 mm of position I. The radius at the distal end 6 increases linearly with the rotational speed of the drive shaft 11. The radial aperture region 3 has a diameter of 8.4 mm, corresponding to a 55.4 mm 2 The diameter of the radial orifice region 3 has increased by 6.2 mm from position I at 0 RPM to position III at the maximum rotational speed of 15,000 RPM, which is 20% of the axial length of the cantilever beam 2 of 30 mm in this embodiment. The longitudinal orifice region 4 consists of eight tapered grooves and has an area comparable to the radial orifice region 3. The area of ​​the orifice in the open position III of the cantilever beam 2 is about 12% of the cross-sectional area of ​​the axial hole 18 of the drive shaft 11, not depicted. At the maximum rotational speed, the oil flow rate through the control valve is about 80% of the reference oil flow rate.

[0040] Reference numerals 1 Shell 2 Cantilever beam 3 Radial orifice area 4Longitudinal orifice area 5. Balance weight 6 End 7 Resilience Zone 8 rings 9Head section 10 rotors 11 Drive shaft 12 Control valve 14 Supply pipeline 15 Storage 16 radial holes 17 Stator 18 axial hole 19 Neck A. Axis of rotation.

Claims

1. Motor, including: a hollow drive shaft (11) for supporting a rotor (10) rotatable relative to a stator (17), the drive shaft (11) being rotatably supported in the housing (1) about a rotation axis (A), and a hydraulic system for circulating a fluid, having a supply line (14) leading to an axial bore (18) of the drive shaft (11), and A control valve (12) is arranged in the axial hole (18) for controlling the flow of fluid entering the drive shaft (11), the control valve (12) being actuated by centrifugal force.

2. The motor according to claim 1, characterized in that The control valve (12) has a plurality of cantilever beams (2) arranged circumferentially around the rotation axis (A) and connected to a ring (2) fitted into the axial bore (18), the cantilever beams (2) being axially biased inwardly.

3. The motor according to claim 2, characterized in that The centrifugal force pushes the cantilever beam (2) radially outward.

4. An electric machine according to any one of the preceding claims 2 or 3, characterized in that The cantilever beam (2) forms a nozzle having an orifice for the fluid to flow through, wherein the area of ​​the orifice depends on the respective position of the cantilever beam (2), and wherein the area of ​​the orifice increases with increasing rotational speed of the drive shaft (11).

5. The motor according to claim 4, characterized in that The area of ​​the orifice is composed of a radial orifice area (3) and a longitudinal orifice area (4).

6. An electric machine according to any one of the preceding claims, characterized in that At a rotational speed of the drive shaft (11) of 0 RPM, the oil flow rate through the control valve (12) is between 0% and 20% of a reference oil flow rate through the axial hole (18) in the absence of the control valve.

7. An electric machine according to any one of the preceding claims, characterized in that At the maximum rotational speed of the drive shaft (11), the oil flow rate through the control valve (12) is greater than 75% of the reference oil flow rate through the axial hole (18) in the absence of the control valve.

8. An electric machine according to any one of the preceding claims 2 to 7, characterized in that Each of the cantilever beams (2) comprises a balancing weight (5) at a terminal end (6).

9. The motor according to claim 8, characterized in that Each of the cantilever beams (2) has a resilient section (7) formed of a flat material and connected to the ring (8); and a head section (9) forming the balancing weight (5).

10. An electric machine according to any one of the preceding claims 8 or 9, characterized in that The head section (9) has a higher mass than the resilient section (7), in particular at least 1.5 times the mass of the resilient section (7).

11. An electric machine according to any one of the preceding claims 8 to 10, characterized in that The resilient section (7) has a neck portion (19), wherein the flat material of the neck portion is corrugated having at least one S-shape.

12. An electric machine according to any one of the preceding claims 8 to 11, characterized in that The head section (9) and the resilient section (7) are made of one or more of a metal material, a metal matrix composite material, a plastic material and a plastic matrix composite material.

13. An electric machine according to any one of the preceding claims, characterized in that The hydraulic system has a fluid reservoir (15), and the supply line (14) hydraulically connects the fluid reservoir and the axial bore (18).

14. The motor according to claim 13, characterized in that The fluid reservoir (15) is located in a position higher than the axial hole (18) with respect to the direction of gravity.

15. An electric machine according to any one of the preceding claims 13 or 14, characterized in that The fluid is delivered to the fluid reservoir (15) by a rotating element of the electric motor, in particular from an oil sump to the fluid reservoir (15) via a gear of a transmission connected to the drive shaft.

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