NL2003653C2 - Lineair actuator, device and method therefor. - Google Patents
Lineair actuator, device and method therefor. Download PDFInfo
- Publication number
- NL2003653C2 NL2003653C2 NL2003653A NL2003653A NL2003653C2 NL 2003653 C2 NL2003653 C2 NL 2003653C2 NL 2003653 A NL2003653 A NL 2003653A NL 2003653 A NL2003653 A NL 2003653A NL 2003653 C2 NL2003653 C2 NL 2003653C2
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- NL
- Netherlands
- Prior art keywords
- linear actuator
- shaft
- stator
- actuator according
- magnets
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02K—DYNAMO-ELECTRIC MACHINES
- H02K41/00—Propulsion systems in which a rigid body is moved along a path due to dynamo-electric interaction between the body and a magnetic field travelling along the path
- H02K41/02—Linear motors; Sectional motors
- H02K41/03—Synchronous motors; Motors moving step by step; Reluctance motors
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- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Electromagnetism (AREA)
- Power Engineering (AREA)
- Linear Motors (AREA)
- Reciprocating, Oscillating Or Vibrating Motors (AREA)
Description
LINEAIR ACTUATOR, DEVICE AND METHOD THEREFOR
The present invention relates to a linear actuator.
Such linear actuators are used in a range of technological 5 fields.
Known linear actuators are capable of driving a shaft in an axial direction to achieve a translating movement of this shaft. For enabling such translating or axial movement, the shaft is often provided with coils and a stator is 10 provided with permanent magnets with alternating polarity. The coils are fed with current to induce a magnetic field with a resulting force capable of moving the shaft relative to the stator. The coils can be provided on the shaft and/or on the stator. The permanent magnets can be used on either 15 one of the stator or the shaft. In practice, to provide current to the coils is controlled using 3-phase amplifiers to change the magnetic field induced by the coils in time such that the movement of the shaft continues. The coils have an electrical resistance and the required power to 20 induce a magnetic field will be used inefficiently, at least partially.
The object of the present invention is to improve the efficiency of linear actuators.
This object is achieved with the linear actuator 25 according to the present invention, the linear actuator comprising: a stator provided with a first set of magnets or electrical windings; a shaft cooperating with the stator, the shaft capable 30 of an axial movement, the shaft provided with a second set of magnets or electrical windings, with at least one of the first and second sets comprising electrical windings; and 2 control means capable of selectively energizing the electrical windings such that an axial force is achieved for axial movement of the shaft, wherein the electrical windings are provided in a radial 5 configuration to the shaft and/or stator.
A linear actuator comprises a stator, and a shaft cooperating with the stator such that a movement of the shaft relative to the stator is possible. The shaft and/or the stator are provided with electrical windings or coils.
10 Preferably, one of the shaft and stator is provided with magnets, for example permanent magnets with a different polarity. Alternatively, both the shaft and the stator are provided with electrical windings.
In use, the control means of the linear actuator 15 selectively energize the electrical windings such that an axial force is achieved for an axial movement of the shaft.
In known linear actuators about half of the length of the electrical windings is oriented in a direction parallel to the centerline of the shaft and the direction of movement 20 thereof. This part of the windings is used inefficiently as current provided to this part of the electrical windings does not contribute to provide an axial force to enable movement of the shaft relative to the stator.
In the linear actuator according to the invention the 25 electrical windings or coils are provided in a radial configuration to the shaft. Providing the electrical windings in a radial configuration to the shaft, or alternatively to the stator, or even further alternatively to both the shaft and the stator, enables the effective use 30 of the entire winding length of the electrical windings of the coils. In particular, the efficiency is improved in relation to the volume of the actuator according to the present invention. This is achieved by preventing the use of 3 parts of electrical windings oriented in a direction parallel to the centerline of the shaft. In fact, the actuator according to the present invention comprises a larger area of induced flux, using a similar diameter, as 5 compared to actuators according to the prior art. This increases the possibilities for a more compact design of the electrical windings or coils with a radial orientation relative to the shaft.
According to the invention several configurations of 10 the stator and/or the shaft are possible. In a presently preferred embodiment the shaft is provided in an opening of the stator. In this configuration the shaft moves along the centreline of the stator, with the stator preferably circumventing the shaft entirely. A configuration with the 15 stator extending along a side of the shaft is also possible. In a further alternative embodiment the stator is provided in an opening of the shaft. In this configuration the shaft is provided on the outside of the stator. Preferably, the stator and the shaft share the same centerline to enable a 20 compact linear actuator.
In a preferred embodiment according to the present invention the actuator comprises one or more modular units, with each unit comprising a first and second set of magnets or windings .
25 By providing a modular unit with a unit comprising at least one set of magnets or electrical windings or a coil, a building block of the linear actuator is achieved. This enables a modular approach for configuring a linear actuator according to the present invention.
30 Preferably, the modular units comprise a stator that is rotational symmetric and is provided with permanent magnets. Further, the modular rings or units comprise electrical windings provided in a radial configuration and the modular 4 rings or units are provided on a shaft of the linear actuator. The amount of units or rings is determined by the force required and/or the desired moving distance of the shaft relative to the stator.
5 In a preferred embodiment according to the present invention the linear actuator comprises coupling means for coupling the linear actuator with a rotation motor for enabling a rotational movement of the shaft.
By coupling a linear actuator with a rotation motor a 10 translation-rotation motor is achieved. As compared to a known hydraulic actuator capable of rotating and translation movement, the actuator according to the present invention is more cost-efficient and requires less energy. In addition, the production of noise is limited.
15 Preferably, the linear actuator and the rotation motor comprise a separate drive for the axial and rotational movement of the shaft relative to the stator. Preferably, this drive comprises a 3-phase amplifier, one for both the actuator and the motor, thereby enabling a decoupled 20 control. The decoupled control simplifies the control of the actuator and the motor requiring less complex control software as compared to so-called checker-board configurations. This improves the efficiency and applicability of the actuator according to the invention.
25 In a presently preferred embodiment according to the invention the rotation motor, in use, directly acts on the shaft of the actuator. Such configuration is achieved by placing the rotation motor on an extension of the shaft in series with the linear actuator.
30 In an alternative embodiment according to the present invention the rotation motor is configured around the linear actuator in a radial configuration. Although the diameter of such configuration is increased, the length of this 5 translational-rotational actuator stays relatively small. This results in a relatively compact embodiment that can be used efficiently.
In a further preferred embodiment according to the 5 present invention the linear actuator is provided with a cogging compensation distance between adjacent sets of electrical windings.
Cogging in an actuator comprising permanent magnets is an undesired effect. By the introduction of a cogging 10 compensation distance the effect of cogging can be minimized using a periodic shift. Preferably, a cogging compensation distance is provided every three sets of electrical windings or coils. In a preferred embodiment according to the present invention the cogging distance is achieved by shifting three 15 so-called M2R3 actuators by a phase shift of about 4/3 it , so every three winding poles.
Preferably, material that is not magnetically conductive is provided in the cogging compensation distance to further reduce the cogging effect. Also preferably, the 20 cogging compensation distance depends on the number of magnets or winding poles as is mentioned above.
In a further preferred embodiment according to the present invention the linear actuator comprises a cogging reduction distance, preferably in the range of 0-1 mm, more 25 preferably 0-0.1 mm and most preferably 0-0.01 mm.
It was found that applying a relatively small cogging reduction distance had a significant reducing effect on the cogging. This is especially relevant for translational movements. Preferably, in this relatively small cogging 30 reduction distance non-magnetic conductive material is provided to further reduce this cogging effect.
In a further preferred embodiment according to the present invention the linear actuator comprises a ratio 6 between the number of stator poles and the number of rotor poles such that a change of flux during movement occurs at different moments for adjacent poles.
The number of stable preferred positions in a magnetic 5 system is determined by the number of stator and rotor, or translator, poles. Movement of the rotor requires energy. By increasing the number of poles, preferably by using a prime for the number of one of the types of poles such as the number of stator poles, the moment of change of flux during 10 movement is different for adjacent poles. This increases the number of stable positions, thereby minimizing the cogging effect, although energy may be used less efficiently. However, this efficiency can be improved using free commutation by controlling the current through a winding in 15 time. For example, a so-called M7R12 (7 magnets (M) and 12 winding poles (R)) configuration showed a significant reduction in the cogging effect.
The cogging compensation distance, cogging reduction distance, and the above ratio can be provided in any 20 combination in the linear actuator according to the present invention to minimize the cogging effect.
The present invention also relates to a device comprising a linear actuator as described above. Such device provides the same effects and advantages as those stated 25 with reference to the linear actuator. Examples of such devices can be found in electrical discharge machining that is performed for the production of razorblades, positioning systems for fuel injection and positioning systems in a CD drive, pick and place robots, as well as applications of 30 rotary/spindle driven linear actuators.
The present invention further also relates to a method for moving a shaft comprising the step of providing and driving a linear actuator as described above. Such method 7 provides the same effects and advantages as those stated with reference to the linear actuator.
Further advantages, features and details of the invention are elucidated on the preferred embodiments 5 thereof, wherein reference is made to the accompanying drawings, wherein:
Figure 1 illustrates a linear actuator according to the prior art; - Figure 2 illustrates a different view of the actuator 10 according to the prior art of figure 1;
Figure 3A and B illustrates a linear actuator according to the invention; - Figure 4 illustrates the coils and magnet configuration of the linear actuator of figure 3; 15 - Figure 5A illustrates a different view of the actuator of figure 4;
Figure 5B and C show an illustration of a realized field of the actuator of 5A;
Figure 6 illustrates a linear actuator coupled to a 20 rotation motor according to the present invention; and
Figure 7 illustrates an actuator provided with a cogging compensation distance;
Figure 8 illustrates an alternative embodiment to the actuator of figure 7; and 25 - Figure 9 illustrates an alternative embodiment to the linear actuator of figure 3.
A linear actuator 2 according to the prior art (figure 1) is provided with a set of permanent magnets 4 on the stator and a set of coils or windings 6 on the shaft. In the 30 illustrated embodiment magnets 4 (figure 2) are provided on the stator 8 with both a North polarity N 10 and a South polarity S 12 with the two different polarities placed alternately. The windings or coils 6 are provided on the 8 shaft 14 and more specifically on extensions 16 in a radial direction thereof. The coils or electrical windings 6 are configured around extension 16. The extensions 16 are provided with three different phases 16A,16B and 16C. By 5 switching the three phases 1,2,3 of the currents through the windings or coils 6 by control means (not shown) shaft 14 can be translated relative to stator 8, along centerline 18.
A linear actuator 20 (figure 3A and B) according to the present invention, comprises permanent magnets 22 (figure 4) 10 and electrical windings or coils 24. Permanent magnets 22 are provided in two different polarities (figure 5A), a north polarity N 26 and a south polarity S 28 that are alternately placed on stator 30 of actuator 20. Windings 24 are provided in a type of grooves 32 that are provided on 15 shaft 34. Windings or coils 24 are configured in a radial configuration around centerline 36. Grooves 32 separate the surface of shaft 34 in a type of radial rings 38 A, B and C. A cogging reduction distance 37 is provided in which a material is provided that is not magnetically conductive.
20 The resulting magnetic field of the actuator 20 (illustrated in figure 5B and C) can be calculated. From the results can be concluded that the windings are used effectively.
An alternative linear actuator 40 (figure 6) comprises a linear actuator 42 for translation and a rotation motor 44 25 for rotation of a shaft. Actuator 42 is provided with radial shaped magnets 46 on stator 48. Modular rings or units 50 are provided on the shaft around a centreline 52. Rotation motor 44 is provided with magnets 54 on stator part 48 and a rotor part 56 for rotation of the shaft around central 30 access line 52.
In the illustrated embodiment the actuator has the following specifications: 9
Stroke (mm) : 100
Motor constant translation (N/A) : 24
Motor constant rotation (Vs/rad) : 0.3
Volume of translation stator 5 Diameter (mm) : 60
Height (mm) : 36
Volume of rotation stator:
Diameter (mm) : 60
Height (mm) : 25 10 Both actuators 42, 44 can be designed with different configurations of magnets (M) and winding poles (R), like M1R3, M2R3, M4R3, M2R6 etc.
In the illustrated embodiment a so-called M2R3 configuration is shown. To compensate for the cogging effect 15 that may occur the three M2R3 actuators are shifted by a phase shift of 4/3 pi (figure 7). In another embodiment actuator 60 (figure 8) modular units or rings 62 are provided with single coil windings 62 with the stator being provided with magnets 66.
20 In an alternative embodiment of a linear actuator 68 (figure 9) according to the invention a stator 70 for axial movement cooperates with magnets 72 for translation. Backing iron 74 is provided around magnets 72. On the outer side of backing iron 74 the magnets 76 for rotation are provided.
25 Magnets 76 cooperate with the stator 78 for rotation. This configuration 68 provides a relatively compact design.
Actuators 20, 40, 60, 68 can be applied in different devices including electrical discharge machining for razor blades. In such application, the actuators 20, 40, 60, 68 30 are configured to realize a stroke of at least 50 mm, resolution 0.1 mm, absolute axial accuracy 2.5 mm, axial speed larger than 100 m/s, axial acceleration larger than 20m/s2' rotation speed larger than 1000 RPM action force 100N, 10 a torque of 3Nm, an axial bandwidth of 70Hz and an overshoot on a step of 80 pm of less than 0.2 pm.
For moving a shaft in an axial direction a 3-phase amplifier steers a current through the coils or electrical 5 windings thereby generating a magnetic field and an axial force. In case of a translational-rotational actuator, a so-called phi-z actuator, in addition thereto a rotation motor is driven by a second 3-phase amplifier. This decouples translation from rotation of the shaft.
10 The present invention is by no means limited to the above described embodiments thereof. The rights sought are defined by the following claims within the scope of which many modifications can be envisaged. In the illustrated embodiments the shaft is shown as movable within the stator. 15 It will be understood that this configuration can be reversed so that the stator is positioned within the shaft. Furthermore, in the illustrated embodiments the permanent magnets are provided on the stator and the electrical windings on the shaft. This configuration can also be 20 reversed so that the magnets are provided on the shaft and the electrical windings are provided on the stator part.
11
Clauses 1. Linear actuator comprising: a stator provided with a first set of magnets or 5 electrical windings; a shaft cooperating with the stator, the shaft capable of an axial movement, the shaft provided with a second set of magnets or electrical windings, with at least one of the first and 10 second sets comprising electrical windings; and control means capable of selectively energizing the electrical windings such that an axial force is achieved for axial movement of the shaft, wherein the electrical windings are provided in a 15 radial configuration to the shaft and/or stator.
2. Linear actuator according to clause 1, wherein the shaft is provided in an opening of the stator.
20 3. Linear actuator according to clause 1, wherein the stator is provided in an opening of the shaft.
4. Linear actuator according to clause 1, 2 or 3, further comprising one or more modular units, the unit 25 comprising a first and/or a second set of magnets or electrical windings.
5. Linear actuator according to any of the clauses 1-4, comprising coupling means for coupling the linear 30 actuator with a rotation motor for enabling a rotational movement of the shaft.
12 6. Linear actuator according to clause 5, the linear actuator and the rotation motor comprising one separate drive for decoupled control of the axial and rotational movement of the shaft.
5 7. Linear actuator according to clause 5 or 6, wherein the rotation motor is configured around the stator and shaft of the actuator.
10 8. Linear actuator according to clause 5 or 6, wherein the rotation motor in use acts on the stator of the actuator .
9. Linear actuator according to any of clause 1-8, wherein 15 a cogging compensation distance is provided between adjacent set of electrical windings.
10. Linear actuator according to clause 9, wherein the cogging compensation distance depends on the number 20 of magnets and/or winding poles.
11. Linear actuator according to any of clauses 1-9, wherein a cogging reduction distance is provided, preferably in the range of 0-1 mm, more preferably 0- 25 0.1 mm, and most preferably 0-0.01 mm.
12. Linear actuator according to clause 9, 10 or 11, wherein material that is not magnetically conductive is provided in the cogging compensation distance and/or 30 cogging reduction distance.
13 13. Linear actuator according to any of clauses 1-12, wherein the ratio between the number of stator poles and the number of rotor poles is such that a change of 5 flux during movement occurs at different moments for adjacent poles.
14. Device comprising a linear actuator according to any of clauses 1-13.
10 15. Method for moving a shaft comprising the step of providing and driving a linear actuator according to any of clauses 1-13.
Claims (15)
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
NL2003653A NL2003653C2 (en) | 2009-10-16 | 2009-10-16 | Lineair actuator, device and method therefor. |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
NL2003653 | 2009-10-16 | ||
NL2003653A NL2003653C2 (en) | 2009-10-16 | 2009-10-16 | Lineair actuator, device and method therefor. |
Publications (1)
Publication Number | Publication Date |
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NL2003653C2 true NL2003653C2 (en) | 2011-04-19 |
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Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
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NL2003653A NL2003653C2 (en) | 2009-10-16 | 2009-10-16 | Lineair actuator, device and method therefor. |
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NL (1) | NL2003653C2 (en) |
Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2003169456A (en) * | 2001-11-30 | 2003-06-13 | Matsushita Electric Ind Co Ltd | Actuator |
DE10163626A1 (en) * | 2001-12-21 | 2003-07-17 | Bob Bobolowski Gmbh | Electric motor combination for simultaneous rotary and linear movement, has 2 separate primary parts acting as stators and common rotor |
WO2004082103A1 (en) * | 2003-03-10 | 2004-09-23 | Höganäs Ab | Stator core for linear motor |
US20050023905A1 (en) * | 2003-07-31 | 2005-02-03 | Japan Servo Co., Ltd. | Toroidal-coil linear stepping motor, toroidal-coil linear reciprocating motor, cylinder compressor and cylinder pump using these motors |
-
2009
- 2009-10-16 NL NL2003653A patent/NL2003653C2/en not_active IP Right Cessation
Patent Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2003169456A (en) * | 2001-11-30 | 2003-06-13 | Matsushita Electric Ind Co Ltd | Actuator |
DE10163626A1 (en) * | 2001-12-21 | 2003-07-17 | Bob Bobolowski Gmbh | Electric motor combination for simultaneous rotary and linear movement, has 2 separate primary parts acting as stators and common rotor |
WO2004082103A1 (en) * | 2003-03-10 | 2004-09-23 | Höganäs Ab | Stator core for linear motor |
US20050023905A1 (en) * | 2003-07-31 | 2005-02-03 | Japan Servo Co., Ltd. | Toroidal-coil linear stepping motor, toroidal-coil linear reciprocating motor, cylinder compressor and cylinder pump using these motors |
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V1 | Lapsed because of non-payment of the annual fee |
Effective date: 20130501 |