Key information

Title
Linear Actuator with mechanical shock attenuation
Application number
20240838
Case type
National
Status
15.08.2024 Andre og senere realitetsskriv foreligger
Filed
15.08.2024
Effective date
15.08.2024
Publicly available
16.02.2026
Next annual fee due
31.08.2026
Applicant
EXCESS ENGINEERING AS (NO)
Inventor
Gunnar Herø (NO) et al.
Agent
BRYN AARFLOT AS (NO)

Abstract and drawing

Disclaimer: This text has been machine-scanned and may contain errors – please refer to "Publications" for legally binding content.
The present invention relates to a machine part with a housing 1 with an inner surface with a circular cross-section forming a first integral part of a machine element, and an inner rotary element 3 with an outer surface with a circular cross-section forming a second integral part of the machine element. The machine element includes at least three ball bearings with three or more of outer ball bearing races 9 in the inner surface with a circular cross-section 23, three or more inner ball bearing races 8 in the outer surface with a circular cross-section 24, aligned with the outer ball bearing races 9, a plurality of ball bearing balls 2 between the outer ball bearing races 9 and the inner ball bearing races 8 and at least one slot 10 with a slot-lid 11 in the housing 1, forming a gap in the outer ball bearing races 9 and forming at least point of access for the ball bearing balls, wherein the slot-lid 11 including at least one ball bearing race portion. The invention also concerns machine part as described above forming a part of a linear actuator.

Publications

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Documents

 Expand Download files (21)
Date
 Date Doc. No. Process Case number In/Out Journal description To/from
 04.09.2026 11-02 Saksbehandling 20240838 UT PT report 01:35:54
04.09.2026 11-01 Saksbehandling 20240838 UT Substantive Examination BRYN AARFLOT AS
 02.07.2026 10-01 Saksbehandling 20240838 UT PT Varsel om betaling av første årsavgift (3317) (PT20240838) BRYN AARFLOT AS
 29.06.2025 09-04 Saksbehandling 20240838 INN Response NIPO BRYN AARFLOT AS
 29.06.2025 09-03 Saksbehandling 20240838 INN Amended specification marked copy BRYN AARFLOT AS
 29.06.2025 09-02 Saksbehandling 20240838 INN Amended Specification Clean BRYN AARFLOT AS
 29.06.2025 09-01 Saksbehandling 20240838 INN Korrespondanse (Hovedbrev inn) BRYN AARFLOT AS
 25.03.2025 07-03 Saksbehandling 20240838 UT XXPT 08 Eng- Substantive Examination (Draft)_1970414
25.03.2025 07-02 Saksbehandling 20240838 UT PT report 09:02:51
25.03.2025 07-01 Saksbehandling 20240838 UT General letter patent BRYN AARFLOT AS
 24.03.2025 06-01 Saksbehandling 20240838 UT General letter patent BRYN AARFLOT AS
 21.03.2025 08-02 Saksbehandling 20240838 INN NIPO office action BRYN AARFLOT AS
 21.03.2025 08-01 Saksbehandling 20240838 INN Korrespondanse (Hovedbrev inn) BRYN AARFLOT AS
 15.03.2025 05-02 Saksbehandling 20240838 UT PT report 03:24:24
15.03.2025 05-01 Saksbehandling 20240838 UT Substantive Examination BRYN AARFLOT AS
 22.08.2024 04-02 Saksbehandling 20240838 INN GpOA Excess Engineering - signed BRYN AARFLOT AS
 22.08.2024 04-01 Saksbehandling 20240838 INN Korrespondanse (Hovedbrev inn) BRYN AARFLOT AS
 16.08.2024 03-01 Saksbehandling 20240838 UT Formal Examination 1 BRYN AARFLOT AS
 16.08.2024 02-01 Saksbehandling 20240838 UT Infobrev til oppfinner BRYN AARFLOT AS
 15.08.2024 01-02 Saksbehandling 20240838 INN 144764NO-description-claims-abstract-fig BRYN AARFLOT AS
 15.08.2024 01-01 Saksbehandling 20240838 INN Søknadsskjema Patent BRYN AARFLOT AS

Description, claims and drawings

Disclaimer: This text has been machine-scanned and may contain errors – please refer to "Publications" for legally binding content. Description
Technical Field[0001] The present invention relates to a machine part with roller bearings for cylinders exposed to axial and radial forces. It is applicable in linear actuators for converting rotational motion to linear motion, and vice versa. The present invention is developed to enable compact designs with high performance, high speed, low weight and high load ratings. Furthermore, the present invention is developed to provide higher flexibility when designing rotating parts. The invention is particularly developed for electrical linear actuators substituting hydraulic cylinders on land, submerged and subsea.Background Art[0002] Ball bearings typically include an inner bearing ring with an inner bearing race, an outer bearing ring with an outer bearing race, bearing balls and a cage providing spacings between the bearing balls. The bearing balls are typically in a number that fills half or less of the space between the inner and outer bearing rings to allow assembly. The bearings balls are fed axially in between the inner and outer bearing rings during assembly before installation of the cage holding the bearing balls apart.[0003] Other ball bearings have removable bearing races or bearing cones, allowing the ball bearing balls to be in a number to completely fill the bearing with bearing balls before the removable bearing race is installed. Again, the bearing balls are fed axially into the bearing during assembly and a space between the parts must be present to allow assembly.[0004] A mechanical component with a bearing of the above type must be designed to allow installation of the bearing, and a space between the cylindrical component / shaft/ and a housing surrounding the cylindrical component must be sufficient to allow room for the bearing balls.[0005] Specialty bearings, such as some bicycle wheel bearings, include two bearing races in a wheel hub and two removable cones on a shaft. The bearing races in the wheel hub are accessible axially until the shaft and cones are installed. [0006] In either case, the inner and outer diameter of the bearings dictate the space between the shaft and the housing the shaft is supported in. A bearing with more than two rows of bearing balls with the same diameter is impossible to assemble.[0007] The contact faces of a bearing are typically of hardened and highly wear resistant materials to allow high surface stresses and to increase the lifespan of the bearing. Such materials are however expensive and not necessarily suitable for other applications.[0008] It is an object of the invention to provide a machine part including bearings that overcomes the above disadvantages of existing machine pars.[0009] In particular, it is an object of the invention to provide a machine part that is allowed to have a small clearance between an element with a circular cross-section and a housing.[0010] Furthermore, it is an object of the invention provide a machine part that is easy to design with a high number of ball bearing ball and thus low surface stresses, allowing the use of a greater range of materials.[0011] Furthermore, it is an object of the invention provide a machine part where the outer housing of the bearing is allowed to be loaded in tension.[0012] Furthermore, it is an object of the invention to provide a machine part with a bearing that does not require axial access to the bearing.[0013] Bearings for cylinders and devices providing a reciprocating motion are well known mechanical elements. With a continuous strive towards improved efficiency, reduced environmental impact when performing operations at land, at sea and subsea, is the industry moving towards lighter and more compact machine elements.[0014] An advantage of hydraulic powered actuators is that they may provide high, linear forces in compact configurations, typically in cylinder/piston arrangements. Hydraulic systems however, leak fluid and causes pollution issues no matter how well they are maintained. Electric systems without hydraulics eliminates problems with oil leaks, simplifies digitalization, and have a potential for lower overall power requirements. Many systems have been developed to compete with hydraulic actuators, but high complexity, low mechanical efficiency and large building size have offset the advantages of utilizing electric energy. [0015] The present invention relates to an improved and more compact machine part for supporting and transferring loads with very low friction and losses. The machine part includes an integral, multirow, ball bearing between two elements, forming a part of a larger, load bearing structure.[0016] The compactness is essential in making compact actuators to replace hydraulic actuators within the space limitations. The scalability offered by allowing three or more ball bearings provides a robust design and long service life.[0017] The present invention also relates to an improved and more compact system for converting rotational torque to axial force or vice versa with very low losses while reducing the disadvantages of linear actuators discussed above. The compactness is essential when replacing hydraulic actuators in confined areas.Summary of invention[0018] The present invention concerns a machine part with a housing with an inner surface with a circular cross-section forming a first integral part of a machine element and an inner rotary element with an outer surface with a circular cross-section forming a second integral part of the machine element. The machine part includes at least three ball bearings. The at least three ball bearings include three or more of outer ball bearing races in the inner surface with a circular cross-section, three or more inner ball bearing races in the outer surface with a circular cross-section, aligned with the outer ball bearing races, and a plurality of ball bearing balls between the outer ball bearing races and the inner ball bearing races. At least one slot with a slot-lid is located in the housing and forms a gap in the outer ball bearing races and at least one point of access for the ball bearing balls. The slot-lid includes at least one ball bearing race portion.[0019] The machine part may include at least one slot and one slot-lid for each ball bearing.[0020] The slots in the housing may be shifted a distance in a circumferential direction in relation to each other along the inner surface with a circular cross-section.[0021] The slots may be located at equal distances from each other along the circumference of the inner surface with a circular cross-section. [0022] The one or more slot-lids covering said slots may include a plurality of ball bearing races.[0023] The housing may form an integral part of one of a motor housing, a pump housing, a linear actuator housing, a transmission and a gear box.[0024] The inner rotary element may form one of a motor shaft, a pump shaft, a part of a linear actuator, a transmission shaft and a shaft in a gear box.[0025] A difference between an inner diameter of the housing and an outer diameter of the inner rotary element may be equal to or less than a diameter of a ball bearing ball in the ball bearing between the housing and the inner rotary element.[0026] The ball bearing balls may fill the bearing races such that a sum of the diameters of the number of ball bearing balls in one ball bearing equals the length of the circumference of the bearing at the location of the center of the ball bearing balls.[0027] The inner surface of the housing and the outer surface of the inner rotary element may be cylindrical.[0028] The inner surface of the housing and the outer surface of the inner rotary element may be conical.[0029] The at least three ball bearings may have equal diameters.[0030] Furthermore, the invention concerns a machine part as described above forming a powered linear actuator configured to provide a transition between a rotational motion and a linear motion. The outer housing includes a cavity, and the inner rotary element includes an outer drive element surrounding the inner rotary element. An inner leadscrew with a leadscrew outer helical ball race is located inside the inner rotary element is and connected to a linear motion drive rod extending through the outer housing. Bearing balls are located in a helical ball race formed by the leadscrew outer helical ball race and the inner rotary element inner helical ball race. The plurality of housing inner ball bearing races surrounds the housing cavity.[0031] Brief description of the drawings:[0032] Fig. 1 is a cross-section of a first machine part of the invention with an integral, multi row ball bearing; [0033] Fig. 2 is a cross-section of a second machine part of the invention with an integral, multi row ball bearing;[0034] Fig. 3 is a cross-section of a ball screw actuator of the invention with an integral, multi row ball bearing;[0035] Fig. 4 is a perspective view, partly cut through, of a detail of the ball screw actuator of the invention;[0036] Fig. 5 is a schematic representation of an embodiment of a machine part suggesting the location of several slots, allowing insertion of ball bearing balls;[0037] Fig. 6 is a perspective view, partly cut through, according to one aspect of the present invention, and[0038] Fig. 7 is a perspective view, partly cut through, according to one aspect of the present invention.Detailed description of the invention[0039] Fig. 1 is a cross-section of a first machine part of the invention with an integral, multi row ball bearing. The machine part includes a housing 1 forming an integral part of a machine element such as a motor housing, a pump housing, a part of a linear actuator, a transmission housing or a gear box.[0040] Furthermore, the machine part includes an inner rotary element 3 also forming an integral part of the machine element. The inner rotary element 3 forms a mechanical element such as a motor shaft, a pump shaft, a part of a linear actuator, a transmission shaft or a shaft in a gear box. The inner rotary element 3 may be hollow or solid.[0041] The multiple ball bearing races and the ball bearing balls 2 allow rotation of the inner rotary element 3 in relation to the housing 1 while taking up forces in axial and radial directions. Fig.1 shows six annular ball bearing races and the number of ball bearings should be at least three to provide a load carrying capacity in a very slim configuration.[0042] A removable slot-lid 11 is located in a slot 10 in the housing 1 and is secured to the hosing 1 with machine screws. The removable slot-lid 11 includes multiple, outer ball bearing races and the combination of the ball bearing races of the housing 1 and the bearing races of the slot-lid, form the complete outer bearing races for the ball bearing balls 2. A transition between each individual bearing race of the lid and the housing may be offset in relation to an adjacent transition to place the transitions at different locations along the circumference of the outer ball race to distribute the wear and forces on the bearing races. The slot-lid 11 may include integrated or separate ball bearing races allowing exchange of the ball bearing races without exchanging the entire lid. A slot-lid including a separate ball bearing race may also simplify use of dissimilar materials.[0043] The inner rotary element 3 and the housing 1 include multiple, aligned ball bearing races. Ball bearing balls 2 are located in the ball bearing races.[0044] The configuration of the present invention removes any risk of bearing rings dislodging from their seat.[0045] Using one or several removable slot-lids 11 allow assembly of the bearing without having to insert the bearing balls in the gap between the housing 1 and the inner rotary element 3, allowing this gap to be almost negligible. The determining design parameter for the gap may then be other consideration such as lubrication and thermal expansion issues. This thus allows for a compact design.[0046] Omitting the limitation in the number of ball races also allows the use of small bearing balls, thus reducing the overall diameter of the design.[0047] Omitting the limitation in the number of ball races may also reduce the surface load in the bearing races, thus increasing the freedom when selecting the materials for the components.[0048] Omitting a cage holding the bearing balls allows the bearing races to be completely filled with bearing balls, and this also contributes to reduce the surface load between the bearing balls and the bearing races.[0049] Fig. 2 is a cross-section of a second machine part of the invention with an integral, multi row ball bearing as disclosed in fig.1. An inner rotary element 3 is rotationally supported in a housing 1 and bearing balls 2 are located in six ball bearing races on the inside of the housing 1 and on the outside of the inner rotary element 3. The housing 1 includes a cylinder clevis attachment 14 allowing the housing to be secured to a component and to form a part of a cylinder arrangement. Again, a removable slot-lid 11 with multiple ball bearing races is located in a slot 10 in the housing 1 such that bearing races of the slot-lid and of the housing form complete outer bearing races for the ball bearing balls 2.[0050] Fig. 3 is an illustration of an inverted ball screw actuator forming a machine part with an inner rotary element 3 with internal helical ball races supported inside a cavity 21 of a housing 1. In the context of this specification is “inverted” intended to describe that is the leadscrew 5, is located inside the inner rotary element 3. This is opposed to a traditional helical ball raced linear actuator where a driven glide nut surrounds a helically, ball raced, rotational screw.[0051] The inner rotary element 3 is supported in the housing by six bearing races for ball bearing balls 2 formed by outer ball bearing races 8 in the inner rotary element 3 and inner ball bearing races in the housing 1.[0052] The inner rotary element 3 is driven in rotation by a motor 20 through a transmission 18, and a gear meshing with a gear rim 19 forms a drive element surrounding the inner rotary element 3. A radial bearing 4, typically a plain bearing or a needle bearing, supports the inner rotary element 3 in the housing 1, and takes up forces from the meshing gears. The drive element provides a drive for the inner rotary element 3. Alternative drive elements include a chain driven sprocket and a rim driven electric motor driving the inner rotary element 3 directly without a transmission.[0053] The gear rim 19 is located close to the centre of the inner rotary element 3 to provide increased torsional stiffness and thus reduced flexibility at the end positions of the drive rod 17. The gear rim 19 may however be located at both the inner and outer end of the housing 1, and increased flexibility at the outer extreme positions of the drive rod can sometimes be advantageous. The ability to locate the gear rim 19 at different locations along the inner rotary element 3 increases the design flexibility and allows flexibility in actuator and motor configurations to suit different needs and space requirements.[0054] The transmission 18 typically includes planetary gears.[0055] The motor is typically an electric motor, but the invention is applicable to other types of motive elements. The linear actuator may be used to convert linear motion to rotating motion and the motor may then for instance be substituted with a generator generating electric power.[0056] The leadscrew 5 is fixed to the drive rod 17 with the rod clevis attachment 13 to transfer the force and to prevent rotation of the leadscrew 5. Rod seals 15 prevent ingress of dirt and fluids into the housing 1. The housing 1 may be filled with fluid for lubrication and to prevent ingress of fluids, typically in submerged applications.[0057] In ball screw and nut designs the balls are recirculated as they roll along the race or course by the relative motion of the screw and nut. A structure to recirculate the balls is thus required. In the present invention, the leadscrew 5 includes an inner leadscrew body having outer helical ball rolling grooves / races and a deflector circuit for re-circulation of the lead screw balls 16.[0058] Fig. 4 shows a detail of fig.3, with the outer ball bearing races 8 of the inner rotary element 3 and the housing inner ball bearing races 9 and a slot 10 in the housing 1 for loading balls into the ball bearing races. The slot 10 allows the balls to be installed or removed during assembly and maintenance. The slot-lid 11 covers the slot 10 and includes lid ball races to provide ball races across the slot 10.[0059] The inner rotary element inner helical ball race 8 and the leadscrew outer helical ball race 7 provide the ball race transferring motion between linear motion and rotating motion. The pathway for recirculation of balls inside the leadscrew 5 is not shown.[0060] An end stop sensor 12 sensing the piston position at the end, is located at the end of the housing 1 and provides a signal to stop or change direction of the rotation of the motor. The drive rod 17 is fixed to the leadscrew 5.[0061] Fig. 5 is a schematic representation of an embodiment of a machine part suggesting the location of several slots 10 for ball bearing balls in the housing 1. Fig. 5 suggests six ball bearings and one slot 10 for each bearing. Clearly the six ball bearings and the six slots are not located in the same plane, and the drawing is thus not an actual drawing through a cross-section of the machine part. The six slots 10 are located 120° apart along the circumference to distribute the loads and wear. The distance between the slots may ensure that no ball bearing balls pass a transition between a slot and an outer ball race in the housing 1 simultaneously to ensure smooth operation and even wear. Fig.5 could also illustrate three ball bearings with two slots 10 for each bearing. Using two slots 10 for each ball bearing will facilitate removal of ball bearing balls for maintenance.[0062] Ball bearing diameter in the present disclosure describes the diameter of the ball bearing at the center of the ball bearing balls.[0063] Characteristics and advantages of the present disclosure and additional features and benefits will be readily apparent to those skilled in the art upon consideration of the following detailed description of exemplary embodiments of the present disclosure and referring to the accompanying figures. The description herein and appended drawings, being of example embodiments, are not intended to limit the claims of this patent application, any patent granted hereon or any patent or patent application claiming priority hereto. On the contrary, the intention is to cover all modifications, equivalents and alternatives falling within the spirit and scope of the claims. Many changes may be made to the embodiments and details disclosed herein without departing from such spirit and scope. The objects, advantages, and features of the invention will become more apparent by reference to the drawings which are appended hereto and wherein like numerals indicate like parts and wherein an illustrative embodiment of the invention is shown.
Claims
CLAIMS1. A machine part comprising a housing (1) with an inner surface with a circular cross-section forming a first integral part of a machine element, and an inner rotary element (3) with an outer surface with a circular cross-section forming a second integral part of the machine element;at least three ball bearings including:-three or more of outer ball bearing races (9) in the inner surface with a circular cross-section (23);-three or more inner ball bearing races (8) in the outer surface with a circular crosssection (24), aligned with the outer ball bearing races (9);-a plurality of ball bearing balls (2) between the outer ball bearing races (9) and the inner ball bearing races (8); andat least one slot (10) with a slot-lid (11) in the housing (1) forming a gap in the outer ball bearing races (9) and forming at least one point of access for the ball bearing balls, wherein the slot-lid (11) including at least one ball bearing race portion.2. The machine part of claim 1, including at least one slot (10) and one slot-lid (11) for each ball bearing.3. The machine part of claim 2, wherein the slots (1) in the housing (1) are shifted a distance in a circumferential direction in relation to each other along the inner surface with a circular cross-section.4. The machine part of claim 3, wherein the slots (1) are located at equal distances from each other along the circumference of the inner surface with a circular crosssection.5. The machine part of claim 1, wherein the slot-lid (11) covering said slot (10), includes at least three of ball bearing races.6. The machine part of one of the claims 1-4, wherein the housing (1) forms an integral part of one of a motor housing, a pump housing, a linear actuator housing, a transmission and a gear box.7. The machine part of one of the claims 1-6 wherein the inner rotary element (3) is one of a motor shaft, a pump shaft, a part of a linear actuator, a transmission shaft and a shaft in a gear box.8. The machine part of one of the claims 1-7, wherein a difference between the inner diameter of the housing (1) and the outer diameter of the inner rotary element (3) is equal to or less than a diameter of a ball bearing ball (2) in the ball bearing between the housing (1) and the inner rotary element (3).9. The machine part of one of the claims 1-8, wherein the ball bearing balls fill bearing races such that a sum of the diameters of the number of ball bearing balls equals the length of the circumference of the bearing at the location of the center of the ball bearing balls.10. The machine part of one of the claims 1-9, wherein the inner surface of the housing (1) and the outer surface of the inner rotary element (3) are cylindrical.11. The machine part of one of the claims 1-10, wherein the at least three ball bearings have equal diameters.12. A machine part of claim 1, forming a powered linear actuator configured to provide a transition between a rotational motion and a linear motion, wherein the outer housing (1) includes a cavity (21);the inner rotary element (3) includes an outer drive element surrounding the inner rotary element (3);an inner leadscrew (5) with a leadscrew outer helical ball race (6) inside the inner rotary element (3) and connected to a linear motion drive rod (17) extending through the outer housing (1);bearing balls in a helical ball race formed by the leadscrew outer helical ball race (6) and the inner rotary element inner helical ball race (7); andwherein the plurality of housing inner ball bearing races (9) surround the housing cavity (21).
Drawings

Priority

No priority

Patent classes

IPC classesF16H 25/22F16H 25/08F16H 25/12CPC classesF16H 25/2204F16H 25/08F16H 25/12B62D 5/0448

Citations

US 2017/0268641 A1 (A1)US 2023/0228320 A1 (A1)US 11835116 B1 (B1)CN 210661254 U (U)JP 7177871 B2 (B2)CN 117515294 A (A )US 3148922 A (A )US 2015/0308503 A1 (A1)WO 01/71217 A1 (A1)US 2010/0275710 A1 (A1 )US 2017/0268641 A1 (A1)US 2023/0228320 A1 (A1)

Applicants, owners and inventors

Applicants
EXCESS ENGINEERING AS
Strandgata 151 4307 SANDNES NO (SANDNES Municipality, Rogaland county)Org. number: 996941817Inventors
Gunnar Herø
Butterudveien 3 1339 VØYENENGA NO (BÆRUM Municipality, Akershus county)
Geir Ståle Kleppe
Nordengveien 69 0755 OSLO NO (OSLO Municipality, Oslo county)
Ove Kalvatn
Gamle Eikesetveien 21 4032 STAVANGER NO (STAVANGER Municipality, Rogaland county)

Agent

BRYN AARFLOT AS
BRYN AARFLOT AS

Org. number: 979993269

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Open in The Brønnøysund Register Centre
Stortingsgata 8 0161 OSLO NO (OSLO Municipality, Oslo county)
Org. number: 979993269
Reference: 144764NO

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