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EP-4737751-A1 - FLUID BEARING ARRANGEMENT, MANUFACTURING METHOD THEREFORE AND ELECTRICAL MACHINE COMPRISING A FLUID BEARING ARRANGEMENT

EP4737751A1EP 4737751 A1EP4737751 A1EP 4737751A1EP-4737751-A1

Abstract

A fluid bearing arrangement (9) comprises a first member (10), a second member (20), a pressurized-fluid source connection (31) and a fluid distribution channel network (32). The second member is arranged movable relative to the first member in a predetermined motion direction (40). A first side (11) of the first member have protrusions (13) facing a first side (21) of the second member. A distance (d) between the protrusions and the first side of the second member is smaller than an average distance (D). The first side protrusions encircle a first side first and second area (15, 16). The fluid distribution channel network connects the pressurized-fluid source connection to a respective pocket (42) of the first side first and second areas by means of connection channels (38), comprising a respective flow restriction (34). A mean offset of the first side first and second areas, transverse to the predetermined motion direction.

Inventors

  • HAGNESTÅL, Anders
  • KEIJSER, Mårten
  • HALLBERG, DANIEL
  • Skagerlind, Henrick

Assignees

  • Hagnesia AB

Dates

Publication Date
20260506
Application Date
20241029

Claims (15)

  1. A fluid bearing arrangement (9), comprising: - a first member (10); and - a second member (20), movable back and/or forth relative to said first member (10) in a predetermined motion direction (40), said predetermined motion direction (40) being a linear or rotating motion direction; - a pressurized-fluid source connection (31); - a fluid distribution channel network (32); wherein a first side (11) of said first member (10) faces a first side (21) of said second member (20); wherein said first side (11) of said first member (10) presents first side protrusions (13) in a direction of said first side (21) of said second member (20) defining a distance (d) between said first side protrusions (13) and said first side (21) of said second member (20) that is smaller than an average distance (D) between said first side (11) of said first member (10) and said first (21) side of said second member (20); wherein said first side protrusions (13) encircle at least a first side first area (15) of said first side (11) of said first member (10) and a first side second area (16) of said first side (11) of said first member (10); wherein said fluid distribution channel network (32) connects said pressurized-fluid source connection (31) to a respective pocket (42) in contact with said first side first area (15) and said first side second area (16), defined by said first side protrusions (13), by means of connection channels (38) from a common channel to a respective said pocket (42); wherein each connection channel (38) of said connection channels (38) comprises a respective flow restriction (34); wherein a mean offset of said first side first area (15), in a direction transverse to said predetermined motion direction (40), from a predetermined motion path along said predetermined motion direction (40), differs from a mean offset of said first side second area (16), in said direction transverse to said predetermined motion direction (40), from said predetermined motion path along said predetermined motion direction (40).
  2. The fluid bearing arrangement according to claim 1, characterized in that said first side protrusions (13) further encircles at least a first side third area (15C) of said first side (11) of said first member (10); wherein said fluid distribution channel network (32) further connects said pressurized-fluid source connection (31) to a respective pocket (42) in contact with said first side third area (15C), defined by said first side protrusions (13), by means of said connection channels (38) from said common channel to said pocket (42) in contact with said first side third area (15C); wherein a center of gravity of said first side third area (15C), differs, in a direction along said predetermined motion direction (40), from a center of gravity of said first side first area (15B).
  3. The fluid bearing arrangement according to claim 1 or 2, characterized in that a second side (12) of said first member (10) faces a second side (22) of said second member (20), opposite to said first side (11); wherein said second side (12) of said first member (10) presents second side protrusions (14) in a direction of said second side (22) of said second member (20) defining a distance (d) between said protrusions(14) and said second side (22) of said second member (20) that is smaller than an average distance (D) between said second side (12) of said first member (10) and said second side (22) of said second member (20); wherein said second side protrusions (14) encircle at least a second side first area (17) of said second side (12) of said first member (10) and a second side second area (18) of said second side (12) of said first member (10); wherein said fluid distribution channel network (32) further connects said pressurized-fluid source connection (31) to a respective pocket (42) in contact with said second side first area (17) and said second side second area (18), defined by said second side protrusions (14), by means of said connection channels (31) from a common channel to a respective said pocket (42); wherein a mean offset of said second side first area (17), in a direction transverse to said predetermined motion direction (40), from a predetermined motion path along said predetermined motion direction (40), differs from a mean offset of said second side second area (18), in said direction transverse to said predetermined motion direction (40), from said predetermined motion path along said predetermined motion direction (40).
  4. The fluid bearing arrangement according to claim 3, characterized in that said second side protrusions (14) further encircles at least a second side third area of said second side (12) of said first member (10); wherein said fluid distribution channel network (32) further connects said pressurized-fluid source connection (31) to a respective pocket (42) in contact with said second side third area, defined by said second side protrusions (14), by means of said connection channels (31) from said common channel to said pocket (42) in contact with said second side third area; wherein a center of gravity of said second side third area, differs, in a direction along said predetermined motion direction, from a center of gravity of said second side first area (17).
  5. The fluid bearing arrangement according to any of the claims 1 to 4, characterized by a pressurized-fluid source (33) connected to said pressurized-fluid source connection (31), wherein said pressurized-fluid source (33) is a pump and said fluid distribution channel network (32) further comprises return channels (35) from positions outside said first side protrusions (13) and said second side protrusion (14) to said pump.
  6. The fluid bearing arrangement according to any of the claims 1 to 5, characterized in that said flow restrictions (34) in said connection channels (38) is within 25-400% of a total restriction for flows past said protrusions (13, 14) for a respective area when first (10) and second (20) members are in intended positions relative to each other.
  7. The fluid bearing arrangement according to any of the claims 1 to 6, characterized in that said connection channels (38) are separate connection channels with separate flow restrictions (34) for each one of said pockets (42) or at least two of said connection channels (38) share a common channel and a common part flow restriction.
  8. The fluid bearing arrangement according to any of the claims 1 to 7, characterized in that said flow restrictions (34) in said connection channels and at least a part of said connection channels (38) are provided in said first member (10).
  9. The fluid bearing arrangement according to claim 8, characterized in that at least parts of said first member (10) forming said pockets (42) are formed by sheets of magnetically highly permeable material attached by adhesive coating.
  10. The fluid bearing arrangement according to any of the claims 1 to 9, characterized in that said first (21) and second (22) sides of said second member (20) are flat.
  11. The fluid bearing arrangement according to any of the claims 1 to 10, characterized by comprising multiple said second members (20) provided with respective air-gaps relative to said first member (10).
  12. An electrical machine (1), characterized by a fluid bearing arrangement (9) according to any of the claims 1 to 12, wherein said first member (10) is a non-moving part of said electrical machine (1) and said second member (20) is a moving part of said electrical machine (1).
  13. The electrical machine according to claim 12, characterized in that said electrical machine (1) is an electrical machine that operates by switching of magnetic flux.
  14. A method for manufacturing of a fluid bearing arrangement (9), comprising the steps of: - forming (S10) a first member (10), a first side (11) of which presenting first side protrusions (13); wherein said first side protrusions (13) encircles at least a first side first area (15) of said first side (11) of said first member (10) and a first side second area (16) of said first side (11) of said first member (10); - forming (S20) a second member (20); - providing (S30) a pressurized-fluid source connection (31); - providing (S40) a fluid distribution channel network (32); - placing (S50) said second member (20) allowing said second member (20) to be movable back and/or forth relative to said first member (10) in a predetermined motion direction (40), said predetermined motion direction (40) being a linear or rotating motion direction; wherein said second member (20) is placed with a first side (11) of said first member (10) facing a first side (21) of said second member (20); wherein said first side protrusions (13) are placed in a direction towards said first side (21) of said second member (20) defining a distance (d) between said protrusions (13) and said first side (21) of said second member (20) that is smaller than an average distance (D) between said first side (11) of said first member (10) and said first side (21) of said second member (20); wherein said providing (S40) of a fluid distribution channel network (32) comprises forming connection channels (38) from a common channel to a respective said pocket (42), thereby making said fluid distribution channel (38) configured to connect said pressurized-fluid source connection (31) to a respective pocket (42) in contact with said first side first area (15) and said first side second area (16), defined by said first side protrusions (13); wherein said providing (S40) of a fluid distribution channel network (32) further comprises forming a respective flow restriction (34) in each connection channel (38) of said connection channels (38); wherein said forming (S10) of a first member (10) comprises forming of said first side protrusions (13) to give a mean offset of said first side first area (15), in a direction transverse to said predetermined motion direction (40), from a predetermined motion path along said predetermined motion direction (40), that differs from a mean offset of said first side second area (16), in said direction transverse to said predetermined motion direction (40), from said predetermined motion path along said predetermined motion direction (40).
  15. The method for manufacturing according to claim 14, characterized in that said step of forming (S10) said first member (10) comprises attaching (S12) sheets of magnetically highly permeable material having adhesive coating to form at least parts of said first member (10) forming said pockets (42).

Description

TECHNICAL FIELD The present technology relates in general to fluid bearing arrangements and manufacturing thereof and in particular to fluid bearing arrangements suitable for electrical machines. BACKGROUND The concept of electrical machines is well known and the first types of electrical machines such as the induction machine and the synchronous machine that were invented in the late 19:th century are still very important in the industry today. Electric machines generally comprise one movable part, typically but not restricted to a rotor or a translator, and an opposite part, typically a stator. These parts are separated by an air-gap, which separates the movable part and the opposite part. At least one of the parts, typically the stator, also has an electric winding which can carry an electric current. In most electrical machines, there are magnetic attraction forces between the movable part and the opposite part, typically a stator. Thereby, means of securing the position of the movable part relative to the opposite part is required for safe operation of the electrical machine, otherwise the movable part may come in contact with the opposite part causing damage, friction and wear. To provide such means, most electrical machines, especially rotating machines, have a movable part that is attached to a shaft which in turn is supported by two bearings. This is a simple and robust solution, that works well for stiff constructions that are manufactured with sufficient precision to maintain the air-gap distance between the opposite part and the movable part. Also other bearing configurations are possible for both rotating and linear machines, where many of them still rely on having stiff structures to maintain the air-gap distance. There are also machines that have bearings within the air-gap itself. Thereby, the magnetic attraction forces between the movable part and the opposite part are counteracted more locally within the mechanical structure. This reduces the stiffness requirements on the opposite part and the movable part to maintain the separation of them at the air-gap, which in turn allows for thinner mechanical structures. It may also increase the mechanical resonance frequency, which may reduce vibration problems in the machine. The bearings can be of several different types. A particularly suitable solution for having bearings in the air-gap is to have a fluid bearing that provides a stabilizing pressure over a large part of the air-gap area. The magnetic attraction stress in the air-gap, or rather the "fluid gap", is then counteracted by a stress from a fluid pressure that have a similar distribution as the magnetic stress. This further reduces the stiffness requirements on the movable part and the stator. If the fluid is a liquid, the fluid bearing also provides good cooling to both the stator and the movable part. A suitable fluid bearing type to have in the air-gap is a hydrostatic or aerostatic bearing. Such bearings have a pump that provides bearing pressures even when the electrical machine is at standstill. Thereby, they always separate the moving part from the opposite part at the air-gap, which avoids wear. A problem with the current solutions having hydrostatic or aerostatic fluid bearings at the air-gap is that although they reduce the stiffness requirements of the mechanical parts to some degree, they do not provide stability in all degrees of freedom. Thereby, stiffness towards twisting, buckling and warping at the air-gap must still be provided by the mechanical structure. SUMMARY A general object of the presented technology is therefore to provide a fluid bearing suitable for being applied in the air-gap of electrical machines, where the stability of the fluid bearing enables more flexible and thinner structures in electrical machines. The above object is achieved by methods and devices according to the independent claims. Preferred embodiments are defined in dependent claims. In general words, in a first aspect, a fluid bearing arrangement comprises a first member, a second member, a pressurized-fluid source connection and a fluid distribution channel network. The second member is arranged movable back and/or forth relative to the first member in a predetermined motion direction. The predetermined motion direction is a linear or rotating motion direction. A first side of the first member faces a first side of the second member. The first side of the first member presents first side protrusions in a direction of the first side of the second member defining a distance between the protrusions and the first side of the second member that is smaller than an average distance between the first side of the first member and the first side of the second member. The first side protrusions encircle at least a first side first area of the first side of the first member and a first side second area of the first side of the first member. The fluid distribution channel network connects the pressuri