Actuator housing and actuator

Abstract

The present invention provides an actuator. The actuator includes an actuator housing having an inner surface defining a stator receiving portion and a stator. The stator receiving portion includes a rotor support element and a plurality of stator abutment projections spaced around the rotor support element. The plurality of stator abutment projections are integrally formed with the inner surface. The stator has a plurality of locating grooves that can engage with the plurality of stator abutment projections when the stator is received at the stator receiving portion of the actuator housing to position the stator relative to the actuator housing.

Description

[Technical field]

[0001] The present invention relates to an actuator, in particular but not necessarily limited to a part of an actuator having an electric motor such as a star motor. The present invention also relates to an actuator housing. The present invention also provides a method of assembling an actuator and forming the actuator housing. [Background technology]

[0002] Actuators with brushless DC motors or stepper motors are often manufactured with plastic housings, which allows the motor to be manufactured cheaply and efficiently. Many traditional actuators have DC or tin can style stepper motors, however, some more modern actuators have begun to use star style brushless DC motors.

[0003] The problem with star motors compared to tin can motors is that they are relatively flat, so their width and length are much greater than the height of the motor. The rotor is positioned within the star stator and can then rotate at high speeds. Therefore, precise positioning of the rotor is very important, and the stator should be positioned to allow the rotor to rotate smoothly, thereby reducing noise.

[0004] After the existing actuator housing is assembled with the stator, there is a gap between the stator and the housing due to manufacturing tolerances in the manufacture of the stator and the housing, which causes the stator to shift during use, making the rotor eccentric relative to the stator. This problem is particularly prominent for multi-component stators. An alternative is to provide a stator that is formed as a stack of individual stamped parts, but the insertion of the coils onto the stator laminations is difficult to automate.

[0005] The traditional solution to this problem is to provide a spring or similar biasing element within the housing which pushes the stator into its correct position. While this solves the tolerance problem, it also significantly increases manufacturing costs as the assembly process is more complex and also increases the risk of component failure. [Summary of the invention]

[0006] Based on this, the present invention aims to provide a simple mechanism by which a stator can be fixed in an actuator housing without causing tolerance problems during assembly.

[0007] According to a first aspect of the present invention, there is provided an actuator, comprising: an actuator housing having an inner surface including a stator receiving portion, the stator receiving portion comprising a rotor support element, and a plurality of stator abutment protrusions spaced around the rotor support element, the plurality of stator abutment protrusions being integrally formed with the inner surface; and a stator having a plurality of positioning grooves, the positioning grooves being adjacently engaged with the plurality of stator abutment protrusions when the stator is received at the stator receiving portion of the actuator housing to position the stator relative to the actuator housing.

[0008] A stator with a positioning groove is provided, which can match the stator abutment protrusion, so that the stator is inserted into the actuator housing and the stator is automatically aligned with the stator abutment protrusion relative to the rotor support element.

[0009] Preferably, each of the stator abutment protrusions comprises a central support and a positioning head extending laterally from the head support.

[0010] The structure of the stator abutment projections enables them to fit into the narrow area of ​​a locating groove formed between two adjacent stator elements or parts of the stator.Therefore, a T-shaped or substantially T-shaped stator abutment projection is more preferably able to meet this requirement.

[0011] Preferably, each positioning head is oriented towards the rotor support element.

[0012] Orientation of the locating head towards the rotor support element allows the locating head to contact the inner surface of the locating groove proximate the rotor, whereby the locating head provides a retaining force to the stator in use.

[0013] Preferably, when the stator is received in the stator accommodation portion, a surface of each positioning head facing the rotor contacts an inner surface of the positioning groove close to the rotor.

[0014] The direct contact of the locating head with the locating groove immediately creates a physical holding force from several directions, thereby maintaining alignment with the rotor.

[0015] Preferably, each positioning head has an arcuate or substantially arcuate or trapezoidal profile.

[0016] The substantially arcuate or trapezoidal profile of the locating head may provide a natural support shape which helps to hold the stator in position relative to the rotor support element of the actuator housing.

[0017] Preferably, each locating groove of the stator is formed by a pair of lateral projections extending from the stator.

[0018] The physical lateral projections formed on the sides of the stator portion of the stator provide a simple mechanism by which to form the locating recesses of the present invention, ensuring that the stator is aligned with the stator abutment projections of the actuator housing.

[0019] Preferably, a plurality of said stator abutment projections are equiangularly spaced around said rotor support element.

[0020] In order to provide a uniform holding force on the stator, the stator abutment projections are evenly spaced around the rotor support element.

[0021] Preferably, the stator is a star-shaped stator.

[0022] The non-standard star motor has a plurality of arms extending radially from a central rotor receiving portion, providing locating recesses that can be located at various locations on the stator.

[0023] In one embodiment, the stator includes a plurality of stator elements and a coil body, and the plurality of stator elements are engageable with the coil body.

[0024] Traditionally, multi-component stators are more prone to tolerance issues and thus more difficult to align with the rotor. From an assembly perspective, a multi-component stator is preferred and the present invention serves to limit the impact of tolerances on the effectiveness of the actuator.

[0025] In one embodiment, each stator element includes a central locating arm insertable into the coil body and a pair of outer stator arms engageable around the coil body, each outer stator arm including a stop for at least partially forming a locating recess.

[0026] The lateral protrusion of the stator element plays a role in positioning the stator into the actuator housing, not only forming a positioning groove that can engage with the stator abutment protrusion, but also being used for coupling with the auxiliary guide element.

[0027] Preferably, each positioning groove is formed at an interface between adjacent stator elements.

[0028] If the positioning groove is formed between the protruding portions of the adjacent stator elements, the formation of the positioning groove is simplified because there is no need to form a dedicated positioning groove in one stator element or part.

[0029] Preferably, the number of stator elements is equal to the number of stator abutment projections.

[0030] Matching the number of stator abutment projections to the number of stator elements ensures that uniformity of retention force is provided to each stator element, thereby making rotor alignment more effective.

[0031] Preferably, the stator receiving portion further comprises a plurality of auxiliary guiding elements for aligning the stator, and the auxiliary guiding elements are arranged as upright stator arm supporting walls.

[0032] The auxiliary guide element improves the ease with which the stator can be positioned in the stator receptacle, in particular by the alignment of the arms of the star motor.

[0033] Preferably, the stator abutment protrusion abuts against an outer surface of the stator.

[0034] The stator abutment projections secure the position of the stator with a retaining or wedging force by abutting against the outer surface of the stator, thereby preventing lateral movement of the stator in use.

[0035] According to a second aspect of the invention, there is provided an actuator housing having an inner surface including a stator housing portion, the stator housing portion comprising a rotor support element, and a plurality of stator abutment projections spaced around the rotor support element, the plurality of stator abutment projections being integrally formed with the inner surface.

[0036] The actuator housing has an integrally formed stator abutment projection adapted to engage the stator so that the stator can be easily inserted without causing alignment difficulties relative to the intended rotor position.

[0037] Preferably, each of the stator abutment protrusions includes a head support and a positioning head extending laterally from the head support.

[0038] Preferably, each positioning head is oriented towards the rotor support element.

[0039] Preferably, each locating head has an arcuate or substantially arcuate profile.

[0040] Preferably, a plurality of said stator abutment projections are equiangularly spaced around said rotor support element.

[0041] Preferably, the stator receiving portion further comprises a plurality of auxiliary guiding elements for aligning the stator.

[0042] Preferably, the auxiliary guide elements are provided as upright stator arm support walls.

[0043] According to a third aspect of the present invention, there is provided a method of forming an actuator housing according to the second aspect of the present invention, the method comprising the step of molding the actuator housing so that the rotor support element and the plurality of stator abutment protrusions are integrally formed.

[0044] By forming the actuator's stator abutment bosses and rotor support elements in a single moulding step, the relative positioning of these components is fixed. This compensates for tolerances in stator manufacturing, which is a greater problem with multi-component stators.

Brief Description of the Drawings

[0045] Figure 1 An exploded perspective view showing some components of an embodiment of an actuator provided by the present invention;

[0046] Figure 2 Shows Figure 1 A top view of an actuator housing of the actuator shown in ;

[0047] Figure 3 Shows Figure 1 A schematic diagram of an actuator shown in , wherein the stator is inserted into a stator receiving portion of the actuator housing;

[0048] Figure 4 Shows Figure 1 A top view of a stator of an actuator shown in ;

[0049] Figure 5 Shows Figure 3 A top view of the actuator shown in ; and

[0050] Figure 6 An exploded perspective view of an embodiment of an actuator provided by the present invention is shown. [Specific implementation method]

[0051] The present invention will be described in more detail below by way of examples in conjunction with the accompanying drawings.

[0052] Figure 1 An actuator, generally designated 10, is shown which is suitable for use with a stepper motor or similar motor, preferably a star-shaped brushless DC motor. The actuator 10 comprises an actuator housing 12 and a stator 14 which is insertable into the actuator housing 12 at a stator receiving portion 16 thereof.

[0053] In particular, in this embodiment, the actuator 10 is preferably used for a star motor, and therefore the stator 14 is shown as a star. However, it will be appreciated that the present invention may be used with other motor configurations, such as conventional brushless motors, such as stepper motors or BLDC motors.

[0054] exist Figure 2 The actuator housing 12 shown separately in FIG. 1 is formed so that the necessary components of the actuator can be inserted therein. Therefore, the inner surface 18 of the bottom 20 of the actuator housing 12 may have a shape configured to receive the components and have an upright outer wall 22 around it, which defines the scope of the actuator housing 12. Specifically in this embodiment, the inner surface 18 of the bottom 20 of the actuator housing 12 has a stator receiving portion 16 configured to receive the stator 14.

[0055] The stator housing 16 includes a rotor support element 24, such as Figure 1 Shown is a shaft support for the rotor, here shown as a shaft 26 for engaging with the hollow rotor and defining the center position of the stator 14. The shaft 26 is usually provided as a separate element, but can be provided as an integral part of the rotor support element 24 of the housing 12, and thus integrally formed with the housing 12. Although the rotor support element is shown as a shaft support, it can equally be the shaft itself, or indeed a bearing support and / or bearing of the rotor. The rotor support element 24 is used to position the rotor for rotation relative to the stator 14.

[0056] The main positioning mechanism of the stator receiving portion 16 is provided as a plurality of stator abutment protrusions 28, which are formed upright from the inner surface 18 of the actuator housing 12, preferably parallel to the axis 26, and are designed to be engaged with the stator 14 in an abutting manner to hold it in a proper position in the actuator housing 12. Specifically in the present embodiment, there are four stator abutment protrusions 28, which respectively correspond to the four arms of the star-shaped stator 14. Preferably, the number of stator abutment protrusions 28 is equal to the number of arms of the stator 14, and / or the number of stator abutment protrusions 28 is equal to the number of joints between the arms of the stator 14, but it is understandable that a secure engagement can also be achieved with unequal numbers, especially for star-shaped motors with multiple arms.

[0057] Each stator abutment protrusion 28 preferably includes a head support 30 and a positioning head 32 extending laterally from the head support 30. Figure 2 The top view in FIG. 1 shows a generally T-shaped profile. The head support 30 is mainly used for structural support and can be omitted if necessary. The stator abutment protrusion 28 plays a role in supporting the stator 14 once inserted.

[0058] Each locating head 32 may have an arcuate, substantially arcuate, inclined, tapered, concave or trapezoidal profile that is oriented toward the rotor support element 24. In addition to preferably having an inclined or chamfered upper edge to assist stator insertion, each locating head 32 preferably has a rotor-facing surface 32a that contacts the stator 14 when the stator is received in the stator receiving portion 16, and the locating head 32 has an external laterally protruding member such as an arm or wing for fixing the stator 14. It will be understood that the shape of the locating head 32 is determined by the shape of the stator 14. However, the shape of the stator abutment protrusion 28 of the present invention is to facilitate supporting the substantially circular central portion of the stator 14, which surrounds the corresponding rotor.

[0059] The stator receiving portion 16 may include an auxiliary guide element 34, such as a channel or receiving portion for the stator 14, see also Figure 3 and Figure 5 , wherein the stator 14 has been inserted into the stator receiving portion 16, and the shaft 26 extends through the rotor receiving gap 40 of the stator 14. Specifically in this embodiment, the auxiliary guide elements 34 are formed as upright stator arm support walls 36, which are arranged in pairs to form channels for receiving and aligning the arms 38 of the stator 14. Please refer again Figure 1 The space between the auxiliary guide element 34 and the stator abutment protrusion 28 forms a saddle in which the stator 14 can be seated. It can be understood that other auxiliary guide elements 34 can be considered, such as snap-fit ​​elements or shaped moldings.

[0060] Please refer again Figure 3, specifically in this embodiment, additional shafts 42 are also provided, preferably in the form of upright spindles or shafts and used to support the gear train of the actuator, again, these can be formed integrally with the actuator housing 12 or as part of it, although these are shown here as separate components.

[0061] Figure 4 The stator is shown more clearly in Figure 5 The actuator housing and stator are more clearly shown in . The present invention was designed with a multi-component stator in mind, as manufacturing tolerances of each component accumulate in the finished stator 14, exacerbating the problems of centering the stator in use known in the art.

[0062] The stator 14 preferably includes a coil body 44 having a central portion, the central portion being the rotor receiving gap 40 mentioned above, and a plurality of radially extending members forming the arms 38 of the stator 14. A coil winding 46 may be wound around each radially extending member. The coil body 44 is preferably formed of an electrically insulating material.

[0063] The stator 14 also includes a plurality of discrete stator elements 48, where the stator elements 48 have three connecting arms: two outer stator arms 50 and a central locating arm 52. One end of each outer stator arm 50 is formed around the radially extending member of the coil body 44. The central locating arm 52 can be received within the radially extending member of the coil body 44.

[0064] The stator 14 has a plurality of locating grooves 54 that can engage with the stator abutment projections 28 when the stator 14 is inserted into the stator receiving portion 16 of the actuator housing 12. The locating grooves 54 are formed by lateral projections 56 that project outwardly from each outer stator arm 50 of the stator element 48, so that once the stator 14 is assembled, the locating grooves 54 are defined between and / or at the interface between two adjacent stator elements 48.

[0065] Preferably, the lateral projections 56 form a constriction or throat inlet 54a between the opposing lateral projections 56. The locating recess 54 with the throat inlet 54a is adapted to axially receive and laterally retain the locating head 32 of the stator abutment projection 28. The stator abutment projection 28 is preferably positioned to hold the stator 14 in place relative to the rotor support element 24. The lateral projections 56 abut against the auxiliary guide element 34 to provide a greater positive lateral locating force for the stator 14, which can more securely hold the stator 14, particularly during use. Therefore, during use, the lateral projections 56 are located in the saddle between the auxiliary guide element 34 and the stator abutment projection 28.

[0066] Therefore, the shape of the surface 32a of the positioning head 32 facing the rotor can be preferably formed to correspond to the inner surface 58 of the positioning groove 54 close to the rotor. Specifically in this embodiment, the positioning head 32 is basically arcuate, and it can be understood that it can also be partially trapezoidal, so that the positioning head 32 can mirror the inner surface 58 close to the positioning groove 54 close to the rotor.

[0067] The inner surface 58 near the rotor can be considered as the surface of the positioning groove 54 until and including the surface extending from the first lateral protrusion 56, along the outer stator arm 50 toward the coil body 44, through the interface between adjacent stator elements 48 or possibly through the coil body 44 if the stator elements 48 are slightly spaced apart from each other, to the outer stator arm 50 of the adjacent second stator element 48, until the second lateral protrusion 56. Therein, the first lateral protrusion 56 forms a first stop on the first stator element 48 and the second lateral protrusion 56 forms a second stop on the second stator element 48.

[0068] The actuator housing 12 comprises at least the stator abutment projection 28 and the rotor support element 24, but preferably also comprises an auxiliary guide element 34. Since the actuator housing 12 is formed as an integral unit in the present embodiment, the manufacturing tolerances of the actuator housing 12 are significantly reduced. The multi-component stator 14 reduces the manufacturing tolerances since the positioning of these components relative to each other is fixed, wherein the stator abutment projection 28 once inserted into the stator receiving portion 16 can better provide a holding force on the stator 14.

[0069] In order to form such an actuator housing 12 , the rotor support member 24 and the plurality of stator abutment protrusions 28 are integrally formed together, for example, by injection molding.

[0070] Figure 6 60 is shown in its entirety. Preferably, the actuator housing 12 is a two-piece housing comprising the previously described base 62, and a cover 64 engageable with the base 62. The shaft 26 is receivable in the rotor support element 24, the shaft 26 being coaxial with a rotor 66, which is received within the rotor receiving void 40. A connector unit 68 is also provided which comprises an electrical connector which can be connected to a power source to allow the coil windings 46 to be energized.

[0071] Specifically in this embodiment, the additional shaft 42 is aligned with various gears 70 of the gear train which transmit drive from the rotor 66 to the output of the actuator 60. The arrangement of the gears 70 is such that a minimum height of the actuator housing 12 is necessary given the large area requirements of the star motor.

[0072] Thus, such an actuator can be assembled by inserting the stator 14 into the stator receiving portion 16 of the actuator housing 12. The plurality of positioning grooves 54 engage with the plurality of stator abutment protrusions 28 to align the stator 14 relative to the rotor support 24. Preferably, the stator abutment protrusions 28 abut against the stator 14 to provide a uniform or relatively uniform retention force at least laterally.

[0073] To improve the axial retention of the stator 14, one or more of the stator abutment projections may include an axial retention element, such as a detent, catch, latch or hook. For example, a cantilever hook protruding outwardly, such as a protruding finger with an inclined outer surface, is provided to allow the stator to slide onto the stator abutment projection at the locating groove 54, the cantilever hook flexing as the stator is pushed onto it, and then returning to the upper edge of the stator body, for example, at or near the inner surface 58 of the rotor. Thus, the stator 14 is more resiliently held in place when subjected to axial forces (such as vibration or shaking during use).

[0074] For a multi-component stator 14, assembly before insertion into the stator housing 16 may be achieved by providing the coil body 44 with a star-shaped structure and engaging the plurality of stator elements 48 with the arms of the coil body 44. Then, each positioning groove 54 is formed at an interface between adjacent stator elements 48.

[0075] The present invention provides a stator having a positioning groove into which a stator abutment protrusion of an actuator housing can be inserted to align and position the stator in situ. It is understood that a protrusion extending from the stator and insertable into a corresponding groove of the actuator housing can also be provided.

[0076] The present invention provides an actuator in which a stator can be positioned directly and easily within an actuator housing. The actuator housing is provided with a plurality of stator abutment projections which can interengage with stator grooves, and the positioning grooves can be located on the stator. Since the stator abutment projections are formed integrally with the actuator housing and are fixed relative to the axis of the rotor of the actuator, the position of the stator will also be fixed. This is particularly advantageous for multi-component stator configurations, which typically have larger manufacturing tolerances than single stators. This enables the production of a cost-effective stator as the stator does not require offset components, while also significantly reducing the risk of component failure.

[0077] The present invention also provides a method for manufacturing an actuator housing, the method comprising the step of molding the actuator housing so that a rotor support element and a plurality of stator abutting protrusions are integrally formed.

[0078] When used herein with reference to the present invention, the words “comprises / includes / having” are used to specify the presence of stated features, integers, steps or components, but do not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof.

[0079] It should be understood that, for the sake of clarity, certain features of the present invention described in the context of separate embodiments may also be provided in combination in a single embodiment. On the contrary, for the sake of brevity, the various features of the present invention described in the context of a single embodiment may also be provided separately or in any suitable sub-combination.

[0080] The embodiments described above are provided by way of example only, and various other modifications will be apparent to those skilled in the art without departing from the scope of the invention as defined herein.

Claims

1. An actuator, characterized in that: include: an actuator housing having an inner surface including a stator receiving portion, the stator receiving portion including a rotor support element, and a plurality of stator abutment projections spaced about the rotor support element, the plurality of stator abutment projections being integrally formed with the inner surface; and A stator having a plurality of positioning grooves, when the stator is received at the stator receiving portion of the actuator housing to position the stator relative to the actuator housing, the positioning grooves are adjacently engaged with a plurality of stator abutment protrusions, each of the stator abutment protrusions includes a head support and a positioning head extending laterally from the head support, each of the positioning heads is oriented toward the rotor support element, and when the stator is received in the stator receiving portion, a surface of each positioning head facing the rotor contacts an inner surface of the positioning groove close to the rotor.

2. The actuator according to claim 1, characterized in that The head support is located radially outward of the positioning head relative to the rotor support element.

3. The actuator according to any one of claims 1 to 2, characterized in that: Each of the positioning heads has an arcuate or substantially arcuate or trapezoidal profile.

4. The actuator according to any one of claims 1 to 2, characterized in that: Each of the locating grooves of the stator is formed by a pair of lateral protrusions extending from the stator.

5. The actuator according to any one of claims 1 to 2, characterized in that: A plurality of the stator abutment protrusions are equiangularly spaced around the rotor support element.

6. The actuator according to any one of claims 1 to 2, characterized in that: The stator is a star-shaped stator including a plurality of stator elements and a coil body, the plurality of stator elements being engageable with the coil body.

7. The actuator according to claim 6, characterized in that Each of the stator elements comprises a central locating arm insertable into the coil body and a pair of outer stator arms engageable around the coil body, each of the outer stator arms comprising a stopper for the at least partially formed locating groove.

8. The actuator according to claim 6, characterized in that Each of the positioning grooves is formed at an interface between adjacent stator elements.

9. The actuator according to claim 6, characterized in that The plurality of stator elements is equal to the number of the stator abutment protrusions.

10. The actuator according to claim 1, characterized in that The stator receiving portion further comprises a plurality of auxiliary guide elements for aligning the stator, wherein the auxiliary guide elements are arranged as upright stator arm support walls.

11. The actuator according to claim 1, characterized in that The stator abutting protrusion abuts against the outer surface of the stator.

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