Patent Application
20180330858
Elevator systems are in widespread use. The mechanism for propelling an elevator car may be hydraulic or traction-based. Modernization efforts have recently focused on replacing round steel ropes in traction-based systems with lighter weight belts, for example, and reducing the size of the machine components.
It has more recently been proposed to change elevator propulsion systems to include a magnetic drive. Linear and rotary magnetic drive arrangements are known in various contexts. It has recently been proposed to include a rotary magnetic arrangement for propelling an elevator car. One such arrangement is described in the United States Patent Application Publication No. US 2015/0307325. While such arrangements have potential benefits and advantages, implementing them on a commercial scale is not without challenges. For example, material and manufacturing costs could become prohibitively expensive. Another issue presented to those skilled in the art is how to realize an arrangement of components to ensure efficient and reliable operation.
An illustrative example embodiment of a method of making a rotary magnetic drive member includes establishing a helical magnet on a rod using an additive manufacturing process.
In an example embodiment having one or more features of the method of the previous paragraph, the additive manufacturing process comprises wire arc additive manufacturing.
In an example embodiment having one or more features of the method of any of the previous paragraphs, the helical magnet comprises a magnetic material and the rod comprises a non-magnetic material.
In an example embodiment having one or more features of the method of any of the previous paragraphs, the magnetic material comprises low carbon steel.
In an example embodiment having one or more features of the method of any of the previous paragraphs, the non-magnetic material comprises stainless steel.
In an example embodiment having one or more features of the method of any of the previous paragraphs, the additive manufacturing process comprises cold spray deposition.
In an example embodiment having one or more features of the method of any of the previous paragraphs, the additive manufacturing process comprises directed energy deposition.
In an example embodiment having one or more features of the method of any of the previous paragraphs, the helical magnet comprises a permanent magnet material.
In an example embodiment having one or more features of the method of any of the previous paragraphs, the helical magnet consists entirely of metal.
An example embodiment having one or more features of the method of any of the previous paragraphs includes establishing a pattern of magnetic poles on segments of the helical magnetic including like magnetic poles in axially adjacent segments of the helical magnet.
In an example embodiment having one or more features of the method of any of the previous paragraphs, establishing the pattern of magnetic poles comprises using an external exciter coil in combination with a capacitive charge that provides a short impulse magnetic field to magnetize in a required direction.
An illustrative example embodiment of a magnetic drive member includes a non-magnetic rod and a helical magnet comprising a plurality of turns supported on the non-magnetic rod with an axial spacing between axially adjacent segments of the helical magnet.
In an example embodiment having one or more features of the magnetic drive member of the previous paragraph, the rod comprises a hollow cylinder.
In an example embodiment having one or more features of the magnetic drive member of any of the previous paragraphs, the helical magnet comprises mild steel and the rod comprises stainless steel.
In an example embodiment having one or more features of the magnetic drive member of any of the previous paragraphs, the helical magnet is continuous and interrupted along a helical path along the rod.
In an example embodiment having one or more features of the magnetic drive member of any of the previous paragraphs, the helical magnet consists entirely of metal applied to the rod during an additive manufacturing process.
An example embodiment having one or more features of the magnetic drive member of any of the previous paragraphs includes a spacer between axially adjacent segments of the helical magnet, the spacer comprising a non-metallic material.
In an example embodiment having one or more features of the magnetic drive member of any of the previous paragraphs, the helical magnet comprises a plurality of segments having a selected magnetic pole pattern and segments with like poles are axially adjacent to each other.
In an example embodiment having one or more features of the magnetic drive member of any of the previous paragraphs, the helical magnet comprises a permanent magnet material.
The various features and advantages of at least one disclosed example embodiment will become apparent to those skilled in the art from the following detailed description. The drawings that accompany the detailed description can be briefly described as follows.
Example embodiments of this invention provide a magnetic screw or drive member for propelling an elevator car. Embodiments of a method of manufacturing such a magnetic drive member provide a cost-effective approach that results in an economical, effective and reliable magnetic drive member that is useful in an elevator system, for example.
A helical magnet 42 is situated on and secured to the rod 40. A helical spacer 44 is situated within spacing between axially adjacent turns of the helical magnet 42.
The turns of the magnet 42 are magnetically configured to have alternating pole directions as schematically shown in
With the magnetic poles arranged as schematically shown in
Given that the operation of linear and rotary magnetic drives is generally known, no further explanation need be provided within this description regarding how magnetic flux and rotary motion results in a linear or vertical movement.
In the example of
The spacer 44 in some embodiments is added to or incorporated as part of the rod 40 prior to the helical magnet 42 being formed on the rod 40. In other embodiments the spacer 44 is formed using an additive manufacturing process, which can be completed after the helical magnet 42 is established.
One feature of the additive manufacturing technique included in the example embodiment is that it allows for using a non-magnetic material for the rod 40 and a magnetic material for the helical magnet 42. Additive manufacturing techniques, such as those mentioned above, allow for joining dissimilar materials in a way that results in a sufficiently robust arrangement of the helical magnet 42 on the rod 40 to withstand the forces involved in operating the elevator drive arrangement 30. In an example embodiment, the helical magnet 42 comprises a permanent magnet material, the spacers 44 comprise a mild steel, and the rod 40 comprises a non-magnetic metal, such as stainless steel. Example permanent magnet materials include rare earth permanent magnets such as sintered Nd2Fe14B; sintered SmCo5; sintered Sm(Co,Fe,Cu,Zr)7; bonded Nd2Fe14B; sintered alloys comprising aluminum, nickel and cobalt; or non-rare earth magnets such as Manganese Bismuth, and sintered M-type hexagonal ferrites (e.g., Sr-Ferrite).
The additive manufacturing equipment 62 allows for specific control over the configuration and size of the helical magnet 42. In one example, the rod 40 has a 50 mm or two inch outer diameter. The helical magnet 42 has a height of approximately 15 mm or one-half inch (extending radially outward from the outer surface of the rod 40) with a 25 mm or one inch spacing between axially adjacent turns of the helical magnet 42. Other dimensions are useful for some elevator drive arrangements.
The additive manufacturing used in the illustrated embodiment can be considered metal additive manufacturing because the material of the helical magnet 42 consists of only metal. Additively manufacturing the helical magnet 42 without including any polymer provides a more consistent magnetic path and a stronger magnet. In embodiments that include polymers or other materials within the magnet 42, the magnetic path would be at least partially interrupted by such material and the magnet would have to be larger in size to achieve a corresponding magnetic strength to a smaller sized all-metal magnet.
The helical magnet 42 is continuous and uninterrupted along the length of the helix. This configuration is superior to an arrangement of individual magnets situated next to each other along a helical or spiraled path. Individual magnets introduce leakage flux between adjacent magnets, additional harmonics and losses within the magnetic drive 30 that reduce effective thrust and cause noise and vibration.
The magnet 42 is magnetized in some example embodiments by applying a magnetic field during the additive manufacturing process to align the particles of the magnet material for achieving a configuration of pole orientation like that shown in
In some embodiments, the spacers 44 are not included throughout the gap between all turns of the helical magnet 42. In spaces not occupied by spacers 44, magnetizing hardware configured to fit within the gap facilitates magnetizing the permanent magnet 42. In some examples, after such magnetization, additional spacers 44 are included in gaps that were used for accommodating the magnetizing hardware.
The example disclosed magnetic drive member 32 has increased magnetic efficiency compared to prior arrangements, which allows for using a smaller sized drive member, reducing the cost of the magnetic drive system and reducing the amount of space required within an elevator hoistway for the magnetic drive.
One feature of using a single, continuous helical magnet 42 as included in the illustrated embodiment is that it reduces any requirement for wrapping the magnetic drive member 32 in carbon fiber as would otherwise be needed for retaining individual magnets in place along the helical path occupied by the helical magnet 42. One drawback to using such a wrap in some previous rotary magnetic drive arrangements is the added effective air gap introduced by the wrap, which reduces the magnetic effectiveness of the system and potentially introduces variation of flux levels between magnet segments. Instead, embodiments of this invention include a helical magnet 42 bonded to a rod in a manner that does not require a carbon fiber wrap even for high speed applications. The helical magnet 42 and the spacer 44 establish an improved magnetic circuit even in embodiments that are intended for higher rotational speeds.
The preceding description is exemplary rather than limiting in nature. Variations and modifications to the disclosed examples may become apparent to those skilled in the art that do not necessarily depart from the essence of this invention. The scope of legal protection given to this invention can only be determined by studying the following claims.
