阅读说明：本技术 用于加压流体环境的电动马达 (Electric motor for pressurized fluid environments ) 是由 马修·艾伦·卡罗尔 李·L.·斯奈德 ***·汗丹-巴拉尼 罗纳德·G.·弗拉纳里 艾伦·邓 于 2018-04-23 设计创作，主要内容包括：一种被构建用于暴露于高压流体的电动马达,包括在转子与定子之间提供流体屏障的整体式金属套筒。二次注塑树脂封装定子绕组并加强套筒,以使套筒在高流体压力下的变形最小化。二次注塑树脂还固定了连接到定子绕组的绝缘位移连接器的位置,从而避免了用于将绝缘位移连接器保持就位的机械支架和紧固件。(An electric motor constructed for exposure to high pressure fluids includes a unitary metal sleeve that provides a fluid barrier between a rotor and a stator. The over-molded resin encapsulates the stator windings and reinforces the sleeve to minimize deformation of the sleeve under high fluid pressure. The over-molded resin also fixes the position of the insulation displacement connector connected to the stator windings, thereby avoiding mechanical brackets and fasteners for holding the insulation displacement connector in place.)

1. An electric motor comprising:

a rotor having an axis of rotation;

a stator surrounding the rotor, the stator comprising a plurality of windings;

a unitary metal sleeve comprising a side portion between the rotor and the stator, wherein the sleeve provides a fluid barrier between the rotor and the stator;

a plurality of insulation displacement connectors connected to respective windings of the stator; and

a resin overmold encapsulating the stator and a portion of each insulation displacement connector, wherein the resin overmold engages a side of the sleeve, and wherein the resin overmold fixes a position of each insulation displacement connector relative to the stator.

2. The electric motor of claim 1, wherein the unitary metal sleeve further includes a flange portion extending radially outward from the side portion, and the resin overmold further engages the flange portion of the sleeve.

3. The electric motor of claim 1, further comprising a unitary metal housing including at least one sidewall defining a cylindrical cavity aligned along the axis of rotation of the rotor, wherein the rotor and the stator are received within the cylindrical cavity of the housing.

4. The electric motor of claim 3, wherein the one-piece metal housing further comprises an end wall adjacent the at least one side wall, wherein the end wall has a plurality of inlets extending therethrough and communicating with the cylindrical cavity, and the plurality of insulation displacement connectors extend through the plurality of inlets.

5. The electric motor of claim 4, wherein the end wall of the housing includes a recess, and the one-piece metal sleeve further includes a closed end that projects into the recess in the end wall of the housing.

6. The electric motor of claim 5, wherein the end of the sleeve and the recess in the end wall of the housing correspond in shape and engage one another face-to-face.

7. The electric motor of claim 6, wherein the end of the sleeve and the recess in the end wall of the housing are ellipsoidal.

8. The electric motor of claim 6, wherein the end of the sleeve and the recess in the end wall of the housing are frustoconical.

9. The electric motor of claim 2, wherein the housing includes an internal annular rib and the flange portion of the sleeve includes a circumferential stepped rim having an axial extension and a radial extension, wherein the radial extension of the stepped rim engages the annular rib of the housing, and further comprising a retaining ring arranged to retain the radial extension of the stepped rim against the annular rib of the housing and an elastomeric O-ring arranged between the retaining ring and an outer diameter of the axial extension of the stepped rim.

10. The electric motor of claim 2, wherein the housing includes an internal annular rib and the flange portion of the sleeve is flat, wherein a peripheral region of the flange portion engages the annular rib of the housing, and wherein the electric motor further comprises a retaining ring arranged to retain the peripheral region of the flange portion against the annular rib of the housing and an elastomeric O-ring arranged between the retaining ring and the flange portion.

11. The electric motor of claim 1, wherein the electric motor further comprises a retaining ring having an outer diameter facing an inner diameter of the unitary metal sleeve and an elastomeric O-ring disposed between the outer diameter of the retaining ring and the inner diameter of the unitary metal sleeve.

12. The electric motor of claim 1, wherein the side portion of the sleeve includes a radially reduced portion that tapers in a direction away from the flange portion.

13. The electric motor of claim 12, wherein the resin overmold engages a radially reduced portion of a side portion of the sleeve.

14. The electric motor of claim 12, wherein the radially reduced portion has a frustoconical shape.

15. The electric motor of claim 1, wherein the housing is a die cast housing.

16. The electric motor of claim 1, wherein the sleeve is drawn from a single piece of sheet material having a thickness in the range of 0.010 inches (0.0254 cm) to 0.020 inches (0.0508 cm).

Technical Field

The present invention relates generally to electric motors, and more particularly to electric motors exposed to high internal fluid pressures.

Background

In some applications, it is desirable to expose the interior of the electric motor to a fluid at high pressure. For example, in the field of shock absorbers, it may be desirable to provide a hydraulic actuator having an electric motor capable of withstanding high fluid pressures at the rotor of up to 1500PSI (10,342kpa) without hydraulic fluid leaking into the stator where the fluid can damage the stator windings, cause electric motor failure, and degrade actuator performance by reducing the amount of hydraulic fluid available to operate the actuator.

It is known to protect electric motor stators from fluid damage by encasing the stator in a over-molded resin. While this solution is generally effective for applications where the fluid is at a relatively low pressure, it is not suitable for applications involving higher fluid pressures because the porosity of the molding resin cannot be completely eliminated and leakage may occur. Furthermore, when the motor is subjected to a wide range of temperature cycles and pressure cycles, the adhesion between the molding resin and the motor outer housing will degrade over time. While it is theoretically possible to use only two shot resin to seal the stator against high pressure fluid ingress, this is highly impractical and expensive for high volume production of electric motors, as the resin must be ensured with a pore-free surface finish and tight dimensional tolerances.

There is a need for an electric motor capable of withstanding high fluid pressures, i.e., pressures up to about 1500PSI (10,342kPa), that can be reliably mass produced at a reasonable cost point.

Disclosure of Invention

The present invention provides an electric motor for use in applications where the motor is exposed to high internal fluid pressures. The motor generally includes a rotor having an axis of rotation, a stator having windings surrounding the rotor, a unitary metal sleeve, a plurality of insulation displacement connectors, and a resin overmold.

The unitary metal sleeve includes a side portion between the rotor and the stator and may include a flange portion extending radially outward from the side portion. The sleeve provides a fluid barrier between the rotor and the stator. The sleeve may also include a closed end.

A plurality of insulation displacement connectors are connected to respective windings of the stator. A resin overmold encapsulates the stator and a portion of each insulation displacement connector, and the resin overmold engages the side portions and the flange portions of the sleeve. The resin overmold reinforces the sleeve to minimize deformation of the sleeve when the sleeve is subjected to high pressures. The resin overmold also fixes the position of each insulation displacement connector relative to the housing.

The motor may further include a unitary metal housing including at least one sidewall defining a cylindrical cavity aligned along the rotational axis of the rotor, wherein the rotor and the stator are received within the cylindrical cavity of the housing. The unitary metal housing may further include an end wall adjacent the at least one side wall, wherein the end wall has a plurality of inlets extending therethrough and communicating with the cylindrical cavity, and the plurality of insulation displacement connectors extend through the plurality of inlets. The end wall of the housing may further comprise a recess and the closed end of the sleeve may be arranged to protrude into the recess of the end wall of the housing.

The motor may further comprise a retaining ring and an elastomeric O-ring arranged to form a fluid tight seal between the region occupied by the rotor and the region occupied by the stator.

Drawings

The nature and mode of operation of the present invention will now be described more fully in the following detailed description of the invention taken in conjunction with the accompanying drawings in which:

FIG. 1 is a cross-sectional perspective view illustrating an electric motor formed in accordance with an embodiment of the present invention;

FIG. 2 is a detailed cross-sectional view of the electric motor shown in FIG. 1;

FIG. 3 is a cross-sectional view of a sleeve of the electric motor shown in FIGS. 1 and 2;

FIG. 4 is a bottom plan view of the electric motor of FIGS. 1 and 2, showing an inlet extending through an end wall of the motor housing;

FIG. 5 is a detailed cross-sectional view of an electric motor formed in accordance with another embodiment of the present invention, wherein the sleeve of the electric motor has a different configuration than the sleeve of the electric motor shown in FIGS. 1 and 2;

FIG. 6 is a cross-sectional view of a sleeve of the electric motor shown in FIG. 5;

FIG. 7 is a detailed cross-sectional view of an electric motor formed in accordance with yet another embodiment of the present invention, wherein the sleeve of the electric motor has a different configuration than the sleeve of the electric motor shown in FIGS. 1, 2 and 5;

FIG. 8 is a cross-sectional view of a sleeve of the electric motor shown in FIG. 7;

FIG. 9 is a detailed cross-sectional view of an electric motor formed in accordance with another embodiment of the present invention wherein the sleeve of the electric motor has no radially extending flange portion; and

fig. 10 is a cross-sectional view of a sleeve of the electric motor shown in fig. 9.

Detailed Description

Referring to fig. 1 and 2, an electric motor 10 formed in accordance with a first embodiment of the present invention is shown. The motor 10 comprises a rotor 12, which rotor 12 rotates about a rotation axis 13 relative to a surrounding stator 14. As shown in fig. 2, the stator 14 includes a plurality of windings 22. The motor 10 may be used in applications where the rotor 12 is exposed to high pressure fluid up to about 1500PSI (10,342 kPa). For example, the electric motor 10 may drive a hydraulic actuator in which the rotor 12 is exposed to hydraulic fluid intermittently at high fluid pressures up to about 1500PSI (10,342 kPa). As will be described in detail below, the stator 14 is protected from the ingress of pressurized fluid, yet the motor 10 is cost-effective to manufacture in large quantities and meets applicable performance requirements.

In addition to the rotor 12 and stator 14, the motor 10 also includes an integral metal sleeve 24, shown separately in fig. 3, that provides a fluid barrier between the rotor 12 and stator 14 for preventing pressurized fluid from leaking into the stator 14. As used herein, the term "monolithic" refers to being formed entirely from a single piece of material, as a single piece molding or casting, or as a single piece by additive manufacturing.

The sleeve 24 includes a side portion 24A between the rotor 12 and the stator 14, and a flange portion 24C extending radially outward from the side portion 24A. In the depicted embodiment, side 24A is cylindrical over its entire extent. As shown in fig. 1-3, the flange portion 24C may include a circumferentially stepped rim 27, the circumferentially stepped rim 27 having an axially extending portion 27A that transitions to a radially extending portion 27B. The sleeve 24 may also include a closed end 24B. Alternatively, the end of the sleeve 24 opposite the flange portion 24C may be open.

The motor 10 also includes a plurality of insulation displacement connectors 26 connected to respective windings 22 of the stator 14. For example, the motor 10 may have a wye winding configuration and six insulation displacement connectors 26, one at the beginning of each of the three phases and one at the end of each of the three phases.

In addition to the structural elements described above, the motor 10 includes a resin overmold 28 that encapsulates the stator 14 and a portion of each insulation displacement connector 26. The resin overmold 28 engages the side portion 24A and the flange portion 24C of the sleeve 24, thereby stabilizing and reinforcing the sleeve 24 against pressurized fluid.

The resin overmold 28 also encapsulates a portion of each insulation displacement connector 26, thereby fixing the position of each insulation displacement connector 26 relative to the stator 14. By locating the insulation displacement connector 26 with the resin overmold 28, mechanical fasteners and standoffs are avoided, and the positional accuracy of the insulation displacement connector 26 can be precisely controlled at very low cost. As a result, a very economical and reliable connection of the stator winding 22 to a printed circuit board (not shown) can be achieved.

The motor 10 may also include a unitary metal housing 16 including at least one sidewall 16A surrounding the rotor 12 and stator 14. The housing 16 may also include an end wall 16B. It can be seen that the one or more side walls 16A and the end wall 16B cooperate to define an open end 18 of the housing 16 opposite the end wall 16B and define a cylindrical cavity 20 aligned along the axis of rotation 13. The end wall 16B has a plurality of inlets 21, shown in fig. 2 and 4, which extend through the end wall and communicate with the cylindrical cavity 20. Housing 16 may further include an internal annular ridge 19 adjacent open end 18. The housing 16 may be made as a die cast unit formed, for example, from aluminum or another suitable metal.

If the motor 10 is provided with a unitary metal housing 16, the insulation displacement connectors 26 may be arranged to extend through the plurality of inlets 21. If the sleeve 24 has a closed end 24B, the closed end 24B may be arranged to engage the end wall 16B of the housing 16. For example, as shown in fig. 2, the closed end 24B may be shaped as a convex ellipsoid that is received in mating face-to-face engagement within a correspondingly shaped internal recess 17 in the end wall 16B of the housing 16. A resin overmold 28 may engage the inner surface of each housing sidewall 16A and housing end wall 16B. The resin overmold 28 may also fill the space within the inlet 21 as it encapsulates a portion of each insulation displacement connector 26, thereby fixing the position of each insulation displacement connector 26 relative to the housing 16 and the stator 14. Mechanical fasteners and brackets are avoided and a very economical and reliable connection of the stator winding 22 to a printed circuit board (not shown) located outside the housing 16 can be achieved.

Fig. 5-10 show an alternative embodiment in which the shape of the sleeve 24 is changed. In an alternative embodiment shown in fig. 5 and 6, the shape of the end portion 24B is frustoconical instead of ellipsoidal, and the shape of the recess 17 is modified to correspond to the frustoconical shape of the end portion 24B. The shapes of the end portion 24B and the recess 17 are not limited to those shown in the drawings. The end 24B and the recess 17 may take other shapes, such as a cylindrical shape with a reduced radius relative to the side 24A.

As shown in fig. 7 and 8, side 24A of sleeve 24 may include a radially reduced portion 25 that tapers toward sleeve end 24B. For example, the side portion 24A may be cylindrical from the flange portion 24C, and the radially reduced portion 25 may have a frustoconical shape from the initial cylindrical portion. Regardless of the shape of end 24B, a radially reduced portion may be provided in side 24A. It will be appreciated that where the sleeve 24 includes a radially reduced portion 25 as shown in figures 7 and 8, the space between the stator 12 and the sleeve 24 is filled with resin to provide stable reinforcement to the sleeve 24, even though the resin occupying the space need not encapsulate the stator windings 22.

Fig. 9 and 10 show another embodiment in which the radially extending flange portion 24C is omitted from the sleeve 24.

For all embodiments, the sleeve 24 may be made from a single thin sheet of metal formed by a metal drawing process. In this way, tight tolerances can be achieved while avoiding subtractive machining operations and seams in the material. By way of non-limiting example, the sleeve 24 may be drawn from a titanium sheet having a thickness in the range of 0.010 inches (0.0254 cm) to 0.020 inches (0.0508 cm). Burrs and sharp edges can be removed from the drawn sleeve, and the surface finish of the drawn sleeve can be prepared according to ASTM A-967-Olel using citric acid passivation. Two important considerations in selecting the material for the sleeve 24 are mechanical strength and magnetic properties. Mechanical strength is important to maintain shape under high pressure loads. The magnetic properties are important to the motor performance. The material needs to be non-magnetic and should have low eddy currents when exposed to a changing magnetic field.

The electric motor 10 may further include a retaining ring 30 and an elastomeric O-ring 32, the retaining ring 30 and the elastomeric O-ring 32 being arranged to form a fluid-tight seal between the area occupied by the rotor 12 and the area occupied by the stator 14.

In the embodiment shown in fig. 1-8, retaining ring 30 and elastomeric O-ring 32 are arranged and configured to seal flange portion 24C of sleeve 24 against annular rib 19 of housing 16. For example, the outer diameter of retaining ring 30 may be sized to have an interference fit with the inner diameter of housing 16 adjacent fins 19, and retaining ring 30 may be press-fit or swaged into housing 16 to engage the flange portion 24C and the surrounding area of O-ring 32 to form a secure fluid-tight seal. As shown in fig. 1-6, the axially extending portion 27A of the stepped rim 27 may be engaged by the inner diameter of the retaining ring 30, and the radially extending portion 27B of the stepped rim 27 may be secured by the end face of the retaining ring 30 against the annular rib 19 of the housing 16. Alternatively, as shown in fig. 7-8, the flange portion 24C may be a flat, radially enlarged flange, the peripheral edge region of which is held against the annular rib 19 of the housing 16 by the end face of the retaining ring 30. The flat configuration of the flange portion 24C may be used in the previous embodiment shown in fig. 1-6 and the stepped configuration of the flange portion 24C may be used in the embodiment of fig. 7 and 8.

In the embodiment shown in fig. 9 and 10, a portion of the retaining ring 30 has an outer diameter 31 facing the inner diameter 29 of the unitary metal sleeve 24, and an elastomeric O-ring 32 is disposed between the outer diameter 31 and the inner diameter 29.

The motor 10 may be assembled by performing the following steps. First, the stator 14 is assembled by insulating the laminate stack, for example by attaching a snap-in plastic insulation or a over-molded insulation over the stack. The insulated stack is inserted into a winder to apply the stator winding 22 to the stack, and the wound stack is rolled into a circle to form the stator 14. The insulation displacement connectors 26 are inserted into receiving structures (pockets) in the stacked insulation and attached to the respective windings 22 to electrically connect with the windings. As mentioned above, a total of six insulation displacement connectors 26 may be provided, one at the beginning of each phase and one at the end of each phase. Any additional wires from the windings 22 extend beyond the respective insulation displacement connectors 26. A neutral printed circuit board is mounted to connect the three phase terminals together to form a neutral position (neutral) for the wye motor winding configuration. If a separate housing 16 is used, the stator 14 is installed into the housing 16 by preheating the housing 16 and guiding the housing onto the stator 14 to form a tight mechanical fit. The unitary metal sleeve 24 is then inserted into the central open area of the stator 14 and the assembly is over-molded to provide a protective and structurally supportive resin over-molded part 28. The assembly is then ready to receive the rotor 12 within the sleeve 24.

Although the present invention has been described in connection with exemplary embodiments, the detailed description is not intended to limit the scope of the invention to the particular form set forth. The invention is intended to cover such alternatives, modifications and equivalents of the described embodiments, which may be included within the scope of the claims.