A crankshaft bearing arrangement, an internal combustion engine, a hand-held tool and method for producing a bearing seat

Abstract

A crankshaft bearing arrangement (1) for an internal combustion engine (5), said bearing arrangement (1) comprising: a bearing (10A, 10B) adapted to be arranged at a crankshaft (16) of an internal combustion engine (1); a bearing seat (50) adapted to house the bearing (10A, 10B), wherein a surface (13) of the bearing seat (50) facing and supporting the bearing (10A, 10B) is made from a polymeric material; a sealing arrangement (20) for sealing against the crankshaft (16) and the bearing seat (50); and a protecting member (100) arranged to form a layer between at least a portion of the bearing (10A, 10B) and the bearing seat (50).

Description

[0001] A CRANKSHAFT BEARING ARRANGEMENT, AN INTERNAL COMBUSTION ENGINE, A HAND-HELD TOOL AND METHOD FOR PRODUCING A BEARING SEAT

[0002] Technical field

[0003] The present disclosure relates to a crankshaft bearing arrangement, an internal combustion engine comprising such a crankshaft bearing arrangement and a hand-held tool comprising such an internal combustion engine. The present disclosure further relates to method for injection molding a bearing seat of a crankshaft assembly.

[0004] Background

[0005] In the development of combustion engines for motor-driven tools, such as chainsaws, hedge trimmers, grass trimmers etc., bearing sleeves have been used to eliminate the need for after-treatment of bearing seats of crankshaft bearings after the bearing seats have been manufactured.

[0006] Such bearing sleeves are associated with a number of challenges in terms of accommodating the relatively large tolerances of the components involved, reliable sealing of the crankcase and cost-efficiency. Therefore, plastic crankcases have been implemented to address some of these challenges.

[0007] Such plastic crankcases typically include a plastic case member and bearing seat reinforced with metal brackets or reinforcements. Some challenges with existing plastic crankcases and in particular plastic bearing seats has been identified. The plastic material of the bearing seat is to some extent limited in terms of temperature resistance and mechanical load, especially in some more demanding applications, such as for professional use. The present inventors have identified that a more versatile crankcase suitable for more applications is desirable.

[0008] Summary

[0009] According to an aspect, a crankshaft bearing arrangement for an internal combustion engine is provided. The crankshaft bearing arrangement comprises a bearing. The bearing is adapted to be arranged at a crankshaft of the internal combustion engine.

[0010] The crankshaft bearing arrangement comprises a bearing seat. The bearing seat is adapted to house the bearing. A surface of the bearing seat facing and supporting the bearing is made from a polymeric material.

[0011] The crankshaft bearing arrangement comprises a sealing arrangement for sealing against the crankshaft and the bearing seat.

[0012] The crankshaft bearing arrangement comprises a protecting member. The protecting member is arranged to form a layer between at least a portion of the bearing and the bearing seat.

[0013] The crankshaft bearing arrangement as described above is associated with a number of technical benefits. For example, the part of the bearing seat bearing against the bearing is subjected to challenging conditions in terms of temperature, creep and wear. The positioning of the protecting member hence allows for use of another material at the most exposed parts of the bearing arrangement. Further, the protecting member may be chosen in order to adapt the properties of the crankshaft bearing arrangement while maintaining a relatively low weight and production cost as well as material cost due to the polymeric material of the remaining surface of the bearing arrangement.

[0014] In one embodiment, the protecting member is arranged to wrap around at least a portion of the bearing such that there is no direct contact between the bearing seat and at least said portion of the bearing. Thereby, the at least certain parts of the bearing may be arranged to only be in contact with the protecting member, allowing for the protecting member mitigate the risk of the bearing seat being subjected to large mechanical loads or heat loads as a result of being in contact with the bearing.

[0015] Advantageously, the protecting member is made from a more wear-resistant, load-resistant and / or heat resistant material than the surface. This reduces the risk of the bearing loosening from the bearing seat due to such a material providing an increased creep resistance compared to the material of the aforementioned surface.

[0016] In one embodiment, the protecting member is made from a metal material or a reinforced plastic such as carbon fiber-reinforced plastic. Said materials provides an increased creep resistance for the crankshaft bearing arrangement while being relatively cost-efficient and light. Furthermore, the protecting member may form a reinforcement further increasing the strength of the crankshaft bearing arrangement.

[0017] In one embodiment, the protecting member is formed as a resilient and / or non- rigid sheet or plate. This allows for the protecting member to be produced in a more cost-efficient manner due to the resiliency and / or non-rigidity of the protecting member allowing it to be securely fitted to the bearing seat without requiring precise tolerances. This is particularly the case if the protecting member is in-molded into the bearing seat.

[0018] In one embodiment, the bearing seat is injection molded. The protecting member is insert molded onto the bearing seat. The insert molded protecting member allows for fitting of the protecting member to the bearing seat in a simple cost-efficient manner and in a manner that can be achieved with existing injection molding tools. Further, compared to other means of fitting the protecting member to the bearing seat, the risk for leakage between the protecting member and the bearing seat is reduced.

[0019] In one embodiment, the bearing seat may be provided with at least one reinforcement. The reinforcement is arranged in the bearing seat. The bearing seat is arranged to form a layer between protecting member and the reinforcement. The reinforcement may increase the structural strength and rigidity of the crankshaft bearing arrangement.

[0020] Preferably, the bearing seat is arranged such that there is no direct contact between the reinforcement and the protecting member. Accordingly, the bearing seat may extend between the reinforcement and the protecting member which mitigates the risk for leakage.

[0021] The above-described surface of the bearing seat may be made from fiber- reinforced plastic. The fiber-reinforced plastic may be capable of withstanding loads and temperature that occur in an internal combustion engine of a hand-held motor- driven tool, such as a chainsaw. A more durable bearing seat may thus be achieved.

[0022] In one embodiment, the bearing seat comprises a first part and a second part. The protecting member may be arranged in the second part.

[0023] In one embodiment, the protecting member may be arranged such that there is no direct contact between the second part and the bearing. In one embodiment, the sealing arrangement is arranged around the crankshaft and against a side of the bearing. The side of the bearing faces away from a crankshaft assembly mounted to the crankshaft. The sealing arrangement is arranged for sealing engagement with the crankshaft and the bearing seat. The sealing arrangement thereby mitigates the risk for leakage.

[0024] In one embodiment, the crankshaft bearing arrangement comprises a first bearing and a second bearing. The first and second bearing are arranged at the crankshaft on opposite sides of a crankshaft assembly mounted to the crankshaft. The protecting member may comprise a first portion arranged to form a layer between the first bearing and the bearing seat. The protecting member may comprise a second portion arranged to form a layer between the second bearing and the bearing seat. The two bearings allows for journaling of the crankshaft at two positions which further mitigates wear and creeping.

[0025] In one embodiment, the protecting member may comprise an intermediate portion. The intermediate portion may interconnect the first portion and the second portion. The intermediate portion allows for mounting of a protecting member to both bearings in one operation. The intermediate portion is particularly advantageous if the protecting member is insert molded onto the bearing seat as the intermediate portion allows for precise positioning of the protecting member relative to the injection mold during the injection molding process.

[0026] The intermediate portion may be provided with one or more through-holes. The through-holes may be adapted to expose an inner surface of the bearing seat. The inner surface of the bearing seat may be arranged to face the crankshaft. The through-hole(s) exposes the bearing seat, which may be in a less-heat conductive material compared to the protecting member. The exposed pockets of the bearing seat are thereby less likely to promote heating of the fuel compared to the surface of the intermediate portion of the protecting member. Hence, the risk for increasing the temperature of the fuel due to heat transfer is mitigated, whereby proper combustion and desirable fuel efficiency may be achieved.

[0027] In one embodiment, the protecting member comprises a first protecting element. The first protecting element is provided with the first portion. The second protecting element is provided with the second portion. As the protecting member is split into two parts, a more space-efficient protecting member may be achieved.

[0028] In one embodiment, the protecting member has a curved surface adapted to wrap around a portion of the bearing. Thereby, a relatively large contact interface between the bearing and the protecting member is achieved, further improving the mechanical and heat resistance of the crankshaft bearing arrangement.

[0029] According to an aspect, an internal combustion engine is provided. The internal combustion engine comprises a crankshaft and at least one crankshaft bearing arrangement according to any of the above described embodiments.

[0030] According to an aspect, a hand-held motor-driven tool is provided. The handheld motor-driven tool comprises an internal combustion engine and has a crankshaft and at least one crankshaft bearing arrangement according to any of the above described embodiments.

[0031] According to an aspect, a method of injection molding a part forming at least a portion of a bearing seat for housing a bearing of crankshaft bearing arrangement is provided. The part comprises a surface for facing and supporting the bearing.

[0032] The method comprises positioning a protecting member in an opened injection mold. The protecting member is intended to be arranged to form a layer between at least a portion of the bearing and the bearing seat.

[0033] The method comprises injecting material into the injection mold to form the part, guiding the material to flow onto the protecting member to press the protecting member against the injection mold prior to the material coming into contact with the injection mold.

[0034] The method further comprises filling the injection mold with the material, thereby forming said part and insert molding the protecting member onto the part.

[0035] The method is associated with a number of technical benefits. With the abovedescribed method, the risk for leakage is mitigated due to the protecting member being embedded into the bearing seat. Further, pressing the protecting member into position in relation to the injection mold allows for a more precise positioning and a tighter connection between the bearing seat and the protecting member. In addition, the insert molding of the protecting member does not require changes in existing injection molding tools or steps of machining or casting etc.

[0036] In one embodiment, the protecting member is positioned adjacent to a material inlet of the injection mold. The protecting member thereby protects the material inlet. This reduces wear on the injection mold in the area of the material inlet which may be particularly important in the case of the material being a fiber-reinforced plastic as such material is associated with a higher degree of wear on the injection mold.

[0037] Advantageously, the protecting member is resilient and / or non-rigid. The material may be guided to press the protecting member against the injection mold to shape the protecting member. This allows for a method which is less susceptible to high tolerances due to the deformation of the protecting member allowing the shape of the protecting member to follow the shape of the injection mold.

[0038] Embodiments of the invention are defined by the appended dependent claims and are further explained in the detailed description section as well as in the drawings.

[0039] It should be emphasized that the term “comprises / comprising” when used in this specification is taken to specify the presence of stated features, integers, steps, or components, but does not preclude the presence or addition of one or more other features, integers, steps, components, or groups thereof. All terms used in the claims are to be interpreted according to their ordinary meaning in the technical field, unless explicitly defined otherwise herein. All references to "a / an / the [element, device, component, means, step, etc.]" are to be interpreted openly as referring to at least one instance of the element, device, component, means, step, etc., unless explicitly stated otherwise. The steps of any method disclosed herein do not have to be performed in the exact order disclosed, unless explicitly stated.

[0040] Brief description of drawings

[0041] Embodiments of the invention will be described in the following; reference being made appended drawings which illustrate non-limiting examples of how the inventive concept can be reduced into practice. Figure la depicts a cross-section view of a crankshaft bearing arrangement according to an embodiment with the cylinder of the combustion engine not being visible.

[0042] Figure lb depicts a cross-section view of the crankshaft bearing arrangement of Figure 1 with the cylinder of the combustion engine visible.

[0043] Figure 2 depicts a more detailed view of a portion of the crankshaft bearing arrangement of Figure 1.

[0044] Figure 3 depicts a cross-section view of a crankshaft bearing arrangement according to an embodiment.

[0045] Figure 4 depicts a more detailed view of a portion of the crankshaft bearing arrangement of Figure 3.

[0046] Figure 5 depicts a top perspective view of a crankshaft bearing arrangement according to an embodiment.

[0047] Figure 6 depicts a top view of a crankshaft bearing arrangement according to an embodiment.

[0048] Figure 7 depicts a perspective view of a protecting member according to an embodiment.

[0049] Figure 8 depicts a schematic view of an injection mold and a protecting member according to an embodiment prior to placing of the protecting member into the injection mold.

[0050] Figure 9 depicts a schematic view of the injection mold and a protecting member of Figure 8 wherein the protecting member is placed into the injection mold.

[0051] Figure 10 depicts an exploded view of the injection mold and protecting member according to one embodiment.

[0052] Detailed description

[0053] Figure 1 to 7 depicts aspects of a crankshaft bearing arrangement for an internal combustion engine according to one embodiment.

[0054] Referencing Figure la-b, the crankshaft bearing arrangement 1 comprises a bearing 10. The bearing is adapted to be arranged at a crankshaft 16 of an internal combustion engine 1. The crankshaft bearing arrangement 1 further comprises a bearing seat 50. The bearing seat 50 is adapted to house the bearing 10. The bearing seat 50 comprises a surface 13 facing the bearing 10. The surface 13 supports the bearing 10. The surface is made from a polymeric material. The surface 13 may be considered to bear against the bearing 10.

[0055] The crankshaft 16 is rotatable about a rotation axis A. The bearing 10 may be adapted to rotatably support the crankshaft 16 enabling rotation about the rotation axis A. The bearing 10 may be rotatably mounted to the crankshaft 16.

[0056] A crankshaft assembly 14 may be mounted to the crankshaft 16. As the skilled person is well aware the crankshaft assembly may comprise one or more counterweights (not depicted) and a piston rod 17 for connecting to a piston of the combustion engine.

[0057] In addition, the bearing arrangement 1 comprises a sealing arrangement 20 for sealing against the crankshaft 16 and the bearing seat 50. The sealing arrangement 20 may be arranged around the crankshaft 16 and against a side of the bearing 10 facing away from the crankshaft assembly 14 mounted to the crankshaft 16. The sealing arrangement 20 being arranged for sealing engagement with the crankshaft 16 and the bearing seat 50.

[0058] In the embodiments described in the figures, a crankshaft 16 is shown. The crankshaft 16 is journalled in two bearings 10A-B, in the form of ball bearings. Although, other types of bearings might also be used. Between the two bearings 10A-B, and mounted on the crankshaft, is the crankshaft assembly 14. The bearings 10A-B are inserted in a bearing seat 50.

[0059] Accordingly, the bearing arrangement 1 may comprise a first bearing 10A and a second bearing 10B. The first and second bearing 10A-B may be arranged on opposite sides of the crankshaft assembly 14.

[0060] The first bearing 10A and the second bearing 10B may be coaxially arranged along the rotation axis A.

[0061] In Figure lb, the cylinder 8 of the combustion engine 1 is visible. In the depicted embodiment, the bearing seat may comprise at least two parts. The bearing seat may comprise a first part 51 and a second part 52. The first part 51 may be considered an upper part 51 and the second part 52 may be considered a lower part 52. The upper part 51 and lower part 52 may be considered an upper and lower part relative the rotation axis A.

[0062] As depicted in Figure lb, the first part 51 may form a portion, preferably a lower portion, or an entirety of a cylinder 8 of the internal combustion engine 1. In one embodiment, the second part 52 may form a portion or an entirety of a crankcase, i.e. a crankcase of a tool in which the crankshaft bearing arrangement is installed.

[0063] Each bearing 10A-B is supported by the two parts of the bearing seat 50 in such a way that the bearing seat 50 houses the bearings 10A-B. Preferably, the second part 52 and the first part 51 may be in the form of a lower half and an upper half, respectively. The first part 51 and the second part 52 may be arranged on opposite sides of the rotation axis A.

[0064] As is evident for the skilled person, the crankshaft 16 may be journalled in a single bearing or in more than two bearings. Hence, the crankshaft 16 may be rotatably mounted to a single bearing or more than two bearings.

[0065] The one or more bearing 10 may be press fitted between the first part 51 and the second part 52. Each of the first part 51 and the second part 52 may comprise an aperture for receiving one of the one or more bearings 10. The aperture may be arranged to face the bearing 10. In one example, the first part 51 may comprise a downward facing aperture and the second part 52 may comprise an upward facing aperture. In one example, the aperture of the first part 51 may be of a smaller dimension than the bearing 10 while the second part 52 may have the same dimensions as the bearing 10. This allows for the bearing 10 to be press fitted against the first part 51.

[0066] Again referencing Figure 1, the bearing arrangement 1 comprises a protecting member 100. The protecting member 100 is arranged to form a layer between at least a portion of the bearing 10 and the bearing seat 50.

[0067] In one embodiment, the protecting member 100 is arranged to form a layer between the entire bearing 10 and the bearing seat 50 such that there is no direct contact between the bearing seat 50 and the bearing 10.

[0068] In one embodiment, the protecting member 100 is arranged to form a layer between a portion of the bearing 10 and the bearing seat 50. Hence, a first portion of the bearing 10 may be in direct contact with the bearing seat 50 while a second portion of the bearing 10 may be in direct contact with the protecting member 100 such that there is no direct contact between the second portion of the bearing 10 and the bearing seat 50.

[0069] The protecting member 100 may be arranged to wrap around at least a portion of the bearing 10 such that there is no direct contact between said at least portion of the bearing seat 50 and the bearing 10.

[0070] In the depicted example, the protecting member 100 is arranged such that a first portion of the bearing 10 is in direct contact with the first part 51 and a second portion of the bearing 10 is in direct contact with the protecting member 100.

[0071] The protecting member 100 may be arranged in the second part 52. The protecting member 100 may be arranged such that there is no direct contact between the second part 52 and the bearing 10.

[0072] To improve the wear resistance of the bearing arrangement, the protecting member 100 may be made from a more wear-resistant, load-resistant and / or heat resistant material than the surface 13.

[0073] In one embodiment, the protecting member 100 is made from a metal material or a reinforced plastic such as a carbon fiber-reinforced plastic.

[0074] Advantageously, the protecting member 100 may be formed as a resilient and / or non-rigid sheet or plate. Preferably, the protecting member 100 may be formed as a metal sheet or plate capable of being elastically deformed as a result of a contact pressure.

[0075] The protecting member 100 may be arranged in the second part 52. The protecting member 100 may form an inner surface of the bearing arrangement 1 arranged to face the crankshaft 16.

[0076] The protecting member 100 may extend substantially parallel to the rotation axis A. Hence, an axially extending surface of the protecting member 100 may be adapted to be in contact with an axially extending surface of the bearing 10. Notably, axially herein refers to a direction parallel to the rotation axis A.

[0077] Preferably, the protecting member 100 may have a thickness of between 0,25 and 3 mm and most preferably about 0,5 mm. Thickness herein refers to the thickness of the layer formed by the protecting member 100 between the bearing 10 and the bearing seat 50.

[0078] In the depicted embodiment, the sealing arrangement 20 comprises two separate sealing parts 20A-B, arranged against a side of each bearing 10A-B, which faces away from the crankshaft assembly 14, both sealing arrangements being arranged around the crankshaft 16. Each sealing part 20 is arranged as one unit to seal against the crankshaft 16 and the bearing seat 50.

[0079] Further referencing Figure lb, the sealing arrangement 20 may comprise a first sealing part 20 A arranged against a side of the first bearing 10A facing away from the crankshaft assembly 14. The sealing arrangement 20 may comprise a second sealing part 20B arranged against a side of the second bearing 10B facing away from the crankshaft assembly 14.

[0080] The sealing part 20A-B may be in the form of a sealing ring. The sealing ring may when arranged on the crankshaft 16, faces the bearing 10A-B.

[0081] Figure 2 depicts the sealing part 20B and section X of Figure la, to enable mounting of the sealing part 20A-B, the sealing part may have a number of protrusions 21 arranged at a certain radius of the ring such that the protrusions 21 bear against an outer ring of the bearing 10B. Due to this measure, the protrusions 21 help to push an outer ring of the bearing 10B in an axial direction of the crankshaft 16, e.g. a direction extending along the rotation axis, towards the crankshaft assembly 14, such that the bearings are pushed into a proper position, which results in a long life for the bearings, the crankshaft assembly and the cylinder. The protrusions 21 preferably form a discontinuous ring bearing against the outer ring of the bearing 10. According to other embodiments, the protrusions might also have other forms, such as a continuous ring.

[0082] The sealing parts 20A-B shown in the embodiment described in the figures is arranged as a sealing ring having a diameter substantially equal to the diameter of the bearing 10.

[0083] The polymeric material of the surface of the bearing seat facing and supporting the bearing is preferably any kind of reinforced plastic material, for example a fiber- reinforced plastic such as a carbon fiber reinforced plastic, a glass fiber reinforced plastic or a nano-composite material. The surface may be of any kind of polymeric material that has a high heat distortion temperature. The higher the heat distortion temperature of the material and the thinner the layer of plastic material, the less the plastic material will be deformed. The surface 13 may be made from a fiber-reinforced plastic which can endure high loads and temperatures that may occur in a hand-held motor-driven tool, such as a chainsaw.

[0084] The surface 13 may be arranged to receive and retain the bearing 10. In the depicted example, the surface 13 is provided as surfaces of the first part 51 and the second part 52 facing the bearing 10. Accordingly, the first and second part may each comprise a surface 13.

[0085] Typically, when using an injection casting procedure, the plastic surface 13 will be 1-2 mm. Preferably, the surface 13 will be 1,5 mm thick.

[0086] In one embodiment, the bearing seat 50 may be made from a polymeric material. Hence, the entirety of the bearing seat 50 may be in a polymeric material, not only the surface 13.

[0087] Figure 3 depicts the crankshaft bearing arrangement 1 from another angle.

[0088] As shown in Figure 3, the bearing seat 50 may be provided with at least one reinforcement 12. The reinforcement 12 may be arranged in the bearing seat 50. The bearing seat 50 may be arranged to form a layer between the protecting member 100 and the reinforcement 12. Accordingly, the bearing seat 50 may be arranged between the protecting member 100 and the reinforcement 12.

[0089] Advantageously, the bearing seat 50 may be arranged such that there is no direct contact between the reinforcement 12 and the protecting member 100. The bearing seat 50 may thus be arranged to be in contact with both the reinforcement 12 and the protecting member 100 and form an interface between said reinforcement 12 and the protecting member 100.

[0090] In the depicted embodiment, the surface 13 of the bearing seat 50 may be arranged between the protecting member 100 and the reinforcement 12. In the depicted embodiment, the second part 52 of the bearing seat 50 may have a reinforcement 12 arranged as a layer of metal inside the bearing seat 50 for receiving a pressure force from each bearing. The reinforcement is coated by a plastic material, which provides the surface 13 of the lower part of the bearing seat, which faces the bearing 10 and is in direct contact with the protecting member 100. Therefore, the surface 13 of polymeric material is arranged as a layer between the bearing 10 and the reinforcement layer 12.

[0091] Typically, the reinforcement layer 12 has a thickness of approximately 2-6 mm, depending on, for example, the size of the engine. The surface of plastic material facing and supporting the bearing may be made of the same polymeric material as the rest of the bearing seat. Therefore, the reinforcement will be embedded in the polymeric material of the bearing seat. Accordingly, the surface 13 of the polymeric material may be arranged as a layer between the bearing 10 and the reinforcement 12.

[0092] In the embodiment described in the figures, the second part 52 of the bearing seat 11 has two reinforcements 12A-B, each arranged close to each bearing 10A-B as a metal layer inside the bearing seat 50. Worded differently, the bearing seat 50 is arranged to form a layer between the protecting member 100 and a first reinforcement 12A at the first bearing 10A. Correspondingly, the bearing seat 50 may be arranged to form a layer between the protecting member 100 and a second reinforcement 12B at the second bearing 10B.

[0093] As shown in Figure 3, the second part 52 of the bearing seat 50 may comprise the surface 13 in the polymeric material. The surface 13 faces and supports the bearing 10 and is in direct contact with the protecting member 100. The reinforcement 12 may be arranged in the bearing seat 50 close to the surface 13.

[0094] As depicted, a cylinder 8 is supported by the second part 52 of the bearing seat 50. The second part 52 may have an upper surface supporting the cylinder 8.

[0095] Notably, in the embodiment described, the bearing seat 50 comprises the first part 51 and second part 52, which are connected at an interface extending substantially parallel with the rotation axis of the crankshaft 16. A potential alternative embodiment will now be described below.

[0096] In an alternative embodiment, the crankshaft arrangements may comprise a bearing seat arranged coaxially onto a crankshaft as one integral part housing one bearing. In such arrangements, the internal combustion engine may comprise two bearing seats, one first bearing seat preferably housing a first bearing and one second bearing seat preferably housing a second bearing, arranged in such a way that each bearing seat supports one respective bearing, and one protecting member is arranged as a layer between each bearing and bearing seat. Further, in such an alternative embodiment, the first bearing seat may be integrated in a first crankcase half and the second bearing seat may be integrated in a second crankcase half, wherein the two crankcase halves are connected at a vertical section to form the crankcase. For such arrangements, the whole or part of the surface of the bearing seat may be coated with a plastic material, and correspondingly, the whole or part of the bearing seat may have a reinforcement arranged in the bearing seat. If the reinforcement is arranged in the whole of one bearing seat, it may be arranged as a ring of, e.g., metal, arranged close to the surface of plastic material. Such a ring reinforcement would be easy to manufacture and any after-treatment of a surface supporting the bearing would be unnecessary.

[0097] Figure 4 depicts section Y in Figure 3 in further detail. As shown in said Figure 4, the reinforcement 12A may have an arc-shaped portion. The arc-shaped portion may be arranged to wrap around the surface 13. Since the surface 13 wraps around the protecting element 100 in turn wrapping around the bearing 10 A, the arc-shaped portion of the reinforcement 12A may have a shape corresponding to the outer shape of the bearing 10 A.

[0098] As seen in Figure 4, the protecting member 100 is in contact with the bearing 10A, while the surface 13 is in contact with the protecting member 100. In the depicted embodiment, the reinforcement 12A is embedded into the bearing seat 50, thereby delimiting the surface 13 relative an outer portion of the bearing seat 50 on the opposite side of the reinforcement 12 A.

[0099] In the depicted embodiment, the reinforcement 12A is arranged in the second part 52 of the bearing seat 50.

[0100] Further referencing Figure 5, the second part 52 may be attached to the first part 51 of the bearing seat 50 by means of one or more fastening members 122. Each fastening member 122 may extend through a hole in the first part 51 and the second part 52. In one example, the one or more fastening member 122 may extend through the reinforcement 12 A, thereby securing the reinforcement 12A to the first part 51.

[0101] Figure 5-7 depicts the protecting member 100 and the positioning of the protecting member 100 relative to the bearing seat 50 according to an embodiment. The protecting member 100 may have a curved surface. The curved surface may be adapted to wrap around a portion of the bearing 10. In one embodiment, the curved surface may be arranged coaxially with the rotation axis of the crankshaft. Preferably, the protecting member 100 may have a semi-circular cross-section, whereby an outer surface of the protecting member 100 forms the curved surface.

[0102] In the depicted embodiment, the protecting member 100 is adapted for a bearing arrangement 1 with at least two bearings. The protecting member 100 may comprise a first portion 120A and a second portion 120B.

[0103] The first portion 120 A may be arranged to form a layer between the first bearing 10A and the bearing seat 50. The second portion 120B may be arranged to form a layer between the second bearing 10B and the bearing seat 50.

[0104] Each of the first portion 120A and the second portion 120B may comprise a curved surface adapted to wrap around the first bearing and the second bearing, respectively.

[0105] In the depicted embodiment, the protecting member 100 is formed as one interconnected element. The protecting member 100 comprises an intermediate portion 110. The intermediate portion 110 interconnects the first portion 120A and the second portion 120B.

[0106] The intermediate portion 110 may be provided with one or more through -holes 115. The through-holes 115 may be adapted to expose an inner surface of the bearing seat 50. Said inner surface may be arranged to face the crankshaft.

[0107] In the depicted embodiment, the intermediate portion 110 is provided with an even pattern of through-holes 115. It may however be envisioned that the intermediate portion 110 is provided with a single through-hole 115 for example in the form of an aperture.

[0108] The intermediate portion 110 may comprise a curved surface. The curved surface may align with the curved inner surface of the bearing seat arranged to face the crankshaft. The curved surface may hence be provided the through-holes 115.

[0109] In the depicted embodiment, the protecting member 100 is made from metal, for example steel. As the protective member 100 is formed as one interconnected element and steel has high thermal conductivity, it will improve the heat transfer away from the bearings 10A, 10B during operation, as the heat from the bearing will dissipate through the protective member into the crankcase.

[0110] In an alternative embodiment, the protecting member 100 may be formed as multiple separate parts. The protecting member 100 comprises a first protecting element and a second protecting element. The first protecting element comprises the first portion 120A. The second protecting element comprises the second portion 120B.

[0111] The bearing seat 50 and / or at least part of the bearing seat 50 may be injection molded. The protecting member 100 may be insert molded onto the bearing seat 50 and / or at least said part. Figure 8-10 depicts aspects of the process of the injection molding of the bearing seat 50 and / or at least said part.

[0112] Accordingly, figure 8-10 depicts aspects method of injection molding a part forming at least a portion of the bearing seat 50. The entire bearing seat 50 may be injection molded according to the process depicted or only a part of the bearing seat 50 may be injection molded according to the process depicted.

[0113] A part forming at least a portion of the bearing seat 50 may be injection molded. The protecting member 100 is intended to be arranged to form a layer between at least a portion of the bearing 10 and the bearing seat 50. The protecting member 100 may be insert molded onto the part.

[0114] In the depicted example, said part is in the form of the second part 52 (previously described with reference to Figure 1-6). As aforementioned, it may also be envisioned that the entire bearing seat is injection molded in one operation.

[0115] As the skilled person is well-aware of, components may be insert molded in an injection molding process. Insert molding is an injection molding process that conventionally involves placing pre-formed components or inserts, such as metal pins or threaded inserts, into the mold before injecting molten polymeric material such as plastic. The polymeric material then encapsulates and bonds with the inserts during the molding process, creating a single integrated part. Insert molding is commonly used to enhance the structural integrity, functionality, or aesthetics of a product by incorporating multiple materials or components into a single molded part, reducing assembly steps and improving overall product durability and performance. Accordingly, the protecting member 100 may be pre-formed and inserted into the injection mold before the molding process takes place. After the molding process, the protecting member 100 may be bonded to the bearing seat 50.

[0116] Figure 8-10 depicts the potential steps of such a process.

[0117] In Figure 8, the protecting member 100 is positioned in an opened injection mold 200. The protecting member 100 is intended to be arranged to form a layer between the bearing and the bearing seat 50.

[0118] The injection mold 200 may be formed by a plurality of parts. The plurality of parts may together form the mold cavity forming the shape of the bearing seat. In the depicted embodiment, the protecting member 100 is positioned on a first mold part 210 of the injection mold 200. The first mold part 210 may be a bottom mold part 210 of the injection mold. When the injection mold 200 is opened, access is provided to the first mold part 210 of the injection mold 200, whereby the protecting member 100 may be positioned on said first mold part 210 of the injection mold 200. In the depicted example, the injection mold 200 is adapted to form a second part 52 of the bearing seat 50 as described with reference to any of Figures 1-6.

[0119] In Figure 9, the protecting member 100 is positioned on the first mold part 210 of the injection mold. The first mold part 210 comprises a receiving surface 220. The receiving surface 220 is adapted to receive the protecting member 100. As the protecting member 100 preferably is resilient and / or non-rigid, the receiving surface 220 may form a protrusion adapted to cause deformation of the protecting member 100 to its desired shape. Accordingly, the receiving surface 220 may form a rounded positive protrusion to accommodate the curved surface(s) of the protecting member 100.

[0120] The material may be guided to press the protecting member 100 against the injection mold 200 to shape the protecting member 100. The material which may be in the form of molten polymeric material such as molten plastic, may hence be guided by means of a material inlet to flow on top of the protecting member 100 and thereafter flow along the protecting member 100 onto the injection mold 200, e.g. the first mold part 210 of the injection mold 200.

[0121] Figure 10 depicts an exploded view of the injection tool and the bearing arrangement. Upon positioning of the protecting member 100 in the opened injection mold 200 and closing of the injection mold, material is injected into the injection mold 200 to form the part forming at least a portion of the bearing seat. The closing of the injection mold 200 forms the mold cavity defining the shape of the part.

[0122] The material may be injected via the material inlet 230 of the injection mold 200. The protecting member 100 may be positioned adjacent to the material inlet 230 of the injection mold 200.

[0123] The material may be guided to flow onto the protecting member 100 to press the protecting member 100 against the injection mold 200 prior to the material coming into contact with the injection mold 200.

[0124] The material may then fill the injection mold 200, e.g. the mold cavity formed by the injection mold 200, thereby forming the part forming at least a portion of the bearing seat 50 and insert molding the protecting member 100 onto the part.

[0125] In the depicted embodiment, the injection mold 200 comprises a second mold part 215. The second mold part 220 may be an upper mold part 215 of the injection mold 200. The second mold part 215 may be provided with one or more of the material inlets 230. In the depicted embodiment, the first mold part 210 of the injection mold 200 comprises a first section 211, a second section 212 and a third section 213 which may be interconnected in order to form the first mold part 210.

[0126] In the depicted example, the second mold part 220 is fix and the first mold 210 is mountable to said second mold part 220 to close the injection mold 200. It may however be envisioned that first mold part 210 is fix and the second mold part 220 is mountable to said second mold part 210 to close the injection mold 200.

[0127] When the first mold part 210 is mounted to the second mold part 220, the injection mold is closed and the mold cavity is formed. Hence, material may be injected into said cavity to form the part and insert mold the protecting member 100 onto the part.

[0128] According to an aspect, an internal combustion engine is provided. The internal combustion engine comprises the crankshaft 16 and at least one crankshaft bearing arrangement 1 according to any of the herein described embodiments. According to an aspect, a hand-held motor-driven tool is provided. The tool comprises the internal combustion engine having a crankshaft 16 and at least one crankshaft bearing arrangement according to any of the herein described embodiments.

[0129] According to an aspect, a method of injection molding the part 52 forming at least a portion of the bearing seat 50 is provided. The part 52 comprises a surface for facing and supporting the bearing 10A-B. The method comprises positioning the protecting member 100 in the opened injection mold 200. The protecting member is intended to be arranged to form a layer between at least a portion of the bearing 10A-B and the bearing seat 50.

[0130] The method further comprises injecting material into the injection mold 200 to form the part 52 and guiding the material to flow onto the protecting member 100 to press the protecting member 100 against the injection mold 200 prior to the material coming into contact with the injection mold.

[0131] The method further comprises filling the injection mold 200 with the material, thereby forming the part 52 and insert molding the protecting member 100 onto the part 52.

[0132] In one embodiment, the protecting member 100 is positioned adjacent to the material inlet 230 of the injection mold 200.

[0133] In one embodiment, the protecting member 100 is in a resilient and / or non- rigid material. The material is guided to press the protecting member 100 against the injection mold 200 to shape the protecting member 100.

[0134] It should be appreciated that even though numerous characteristics and advantages of the present invention have been set forth in the foregoing description, together with details of the structure and function of the invention, the description is only illustrative, and changes may be made in detail, especially in matters of shape, size and arrangement of parts within the scope of the invention to the full extent indicated by the appended claims.

Claims

CLAIMS1. A crankshaft bearing arrangement (1) for an internal combustion engine (5), said crankshaft bearing arrangement (1) comprising: a bearing (10A, 10B) adapted to be arranged at a crankshaft (16) of the internal combustion engine (1); a bearing seat (50) adapted to house the bearing (10A, 10B), wherein a surface (13) of the bearing seat (50) facing and supporting the bearing (10A, 10B) is made from a polymeric material; a sealing arrangement (20) for sealing against the crankshaft (16) and the bearing seat (50); and a protecting member (100) arranged to form a layer between at least a portion of the bearing (10 A, 10B) and the bearing seat (50).

2. The crankshaft bearing arrangement (1) according to claim 1, wherein the protecting member (100) is arranged to wrap around at least a portion of the bearing (10A, 10B) such that there is no direct contact between at least said portion of the bearing seat (50) and the bearing (10A, 10B).

3. The crankshaft bearing arrangement (1) according to claim 1 or 2, wherein the protecting member (100) is made from a more wear-resistant, load-resistant and / or heat resistant material than the surface (13).

4. The crankshaft bearing arrangement (1) according to any of the preceding claims, wherein the protecting member (100) is made from a metal material or a reinforced plastic such as carbon fiber-reinforced plastic.

5. The crankshaft bearing arrangement (1) according to any of the preceding claims, wherein the protecting member (100) is formed as a resilient and / or non-rigid sheet or plate.

6. The crankshaft bearing arrangement (1) according to any of the preceding claims, wherein the bearing seat (50) is injection molded and the protecting member (100) is insert molded onto said bearing seat (50).

7. The crankshaft bearing arrangement (1) according to any of the preceding claims, wherein the bearing seat (50) is provided with at least one reinforcement (12) arranged in the bearing seat (50) and the bearing seat (50) is arranged to form a layer between the protecting member (100) and the reinforcement (12).

8. The crankshaft bearing arrangement (1) according to claim 7, wherein the bearing seat (50) is arranged such that there is no direct contact between the reinforcement (12A, 12B) and the protecting member (100).

9. The crankshaft bearing arrangement (1) according to any of the preceding claims, wherein the surface (13) is made from fiber-reinforced plastic capable of withstanding loads and temperatures that occur in an internal combustion engine of a hand-held motor-driven tool, such as a chainsaw.

10. The crankshaft bearing arrangement (1) according to any of the preceding claims, wherein the bearing seat (50) comprises a first part (51) and a second part (52), and wherein the protecting member (100) is arranged in the second part (52), wherein the protecting member (100) preferably is arranged such that there is no direct contact between the second part (52) and the bearing (10A, 10B).

11. The crankshaft bearing arrangement (1) according to any of the preceding claims, wherein the sealing arrangement (20) is arranged around the crankshaft (16) and against a side of the bearing (10A, 10B), said side facing away from a crankshaft assembly (14) mounted to the crankshaft (16), the sealing arrangement (20) being arranged for sealing engagement with the crankshaft (16) and the bearing seat (50).

12. The crankshaft bearing arrangement (1) according to any of the preceding claims, further comprising a first bearing (10A) and second bearing (10B) arranged at the crankshaft (16) on opposite sides of a crankshaft assembly (14) mounted to the crankshaft (16), wherein the protecting member (100) comprises a first portion (120A) arranged to form a layer between the first bearing (10A) and the bearing seat (50) and a second portion (120B) arranged to form a layer between the second bearing (10B) and the bearing seat (50).

13. The crankshaft bearing arrangement (1) according to claim 12, wherein the protecting member (100) comprises an intermediate portion (110) interconnecting the first portion (120A) and the second portion (120B).

14. The crankshaft bearing arrangement (1) according to claim 13, wherein the intermediate portion (110) is provided with one or more through-holes (115) adapted to expose an inner surface of the bearing seat (50) arranged to face the crankshaft (16).

15. The crankshaft bearing arrangement (1) according to claim 12, wherein the protecting member (100) comprises a first protecting element provided with the first portion (120 A) and a second protecting element provided with the second portion (120B).

16. The crankshaft bearing arrangement (1) according to any of the preceding claims, wherein the protecting member (100) has a curved surface adapted to wrap around a portion of the bearing (10A, 10B).

17. An internal combustion engine comprising a crankshaft (16) and at least one crankshaft bearing arrangement (1) according to any of claims 1-16.

18. A hand-held motor-driven tool comprising an internal combustion engine having a crankshaft (16) and at least one crankshaft bearing arrangement according to any of claims 1-16.

19. Method of injection molding a part (52) forming at least a portion of a bearing seat (50) for housing a bearing (10A, 10B) of a crankshaft bearing arrangement, said part (52) comprising a surface for facing and supporting the bearing (10A, 10B), the method comprising: positioning a protecting member (100) in an opened injection mold (200), the protecting member (100) being intended to be arranged to form a layer between at least a portion of the bearing (10A, 10B) and the bearing seat (50); injecting material into the injection mold (200) to form the part (52); guiding the material to flow onto the protecting member (100) to press the protecting member (100) against the injection mold (200) prior to the material coming into contact with the injection mold (200); and filling the injection mold (200) with the material, thereby forming the part (52) and insert molding the protecting member (100) onto the part (52).

20. Method according to claim 19, wherein the protecting member (100) is positioned adjacent to a material inlet (230) of the injection mold (200).

21. Method according to claim 19 or 20, wherein the protecting member (100) is resilient and / or non-rigid and the material is guided to press the protecting member (100) against the injection mold (200) to shape the protecting member (100).

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