Supercharger

Abstract

Provided is a supercharger capable of preventing any one of a rotating shaft, a turbine, and an impeller from coming into contact with a peripheral member (for example, an inner surface of a housing that constitutes the supercharger), even if performance degradation occurs in a bearing that rotatably holds the rotating shaft provided with the turbine and the impeller. A supercharger is provided with: a main bearing which is in contact with an oil region of a rotating shaft in which lubricating oil is held, and which rotatably holds the rotating shaft; and a sub-bearing which is in contact with the oil region and rotatably holds the rotating shaft when the main bearing cannot hold the rotating shaft.

Description

Technical Field

[0001] The present invention relates to a supercharger. More specifically, it relates to a supercharger having a rotating shaft provided with a turbine and an impeller. Background Art

[0002] Patent Document 1 discloses a lubrication structure of a rolling bearing that rotatably holds such a rotating shaft. According to this structure, an oil storage portion for storing the lubricating oil supplied through an oil passage is formed around the rolling bearing. Therefore, at the time of startup when the flow rate of the lubricating oil flowing through the oil passage decreases, the lubricating oil is supplied to the rolling bearing from the oil storage portion. As a result, the rolling bearing is also appropriately lubricated at the time of startup.

[0003] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2023-167847

[0004] However, when the performance of the rolling bearing deteriorates, it may become difficult to stably hold the rotating shaft. In this case, the whirling vibration of the rotating shaft increases, and as a result, any one of the rotating shaft, the turbine, and the impeller (hereinafter, also referred to as "rotating body") may come into contact with a peripheral member (for example, the inner surface of the housing constituting the supercharger). Summary of the Invention

[0005] The present invention has been made in view of such circumstances, and an object thereof is to provide a supercharger that can avoid contact between the rotating body and the peripheral member even when the performance of the bearing deteriorates.

[0006] The supercharger according to the first invention of the present invention includes: a rotating shaft provided with a turbine and an impeller; a main bearing that contacts an oil-containing region of the rotating shaft holding lubricating oil and holds the rotating shaft rotatably; and a sub-bearing that contacts the oil-containing region and holds the rotating shaft rotatably when the main bearing cannot hold the rotating shaft.

[0007] In the second invention of the present invention, based on the supercharger according to the first invention, an axial seal for demarcating the oil-containing region is provided, and the sub-bearing is disposed between the main bearing and the axial seal.

[0008] In the third invention of the present invention, based on the supercharger according to the first or second invention, an annular convex portion for peeling the lubricating oil from the rotating shaft is formed on the rotating shaft, and the sub-bearing is disposed between the main bearing and the annular convex portion.

[0009] In the fourth invention of the present invention, based on the supercharger according to the first invention, at least one of the region of the rotating shaft in contact with the sub-bearing and the region of the sub-bearing in contact with the rotating shaft is made of a wear-resistant material.

[0010] In the first invention, when the main bearing deteriorates in performance, the rotating shaft is held rotatable by the sub-bearing. Therefore, contact between the rotating body and the surrounding members is suppressed. In this case, similar to the main bearing, the sub-bearing contacts the region of the rotating shaft where lubricating oil is held (i.e., the region where an oil film is formed), so wear of the sub-bearing is suppressed. Therefore, the state in which the rotating shaft is held rotatable by the sub-bearing can be maintained for a relatively long time. In addition, the formation of an oil film in the region of the rotating shaft facing the sub-bearing also helps to reduce the frictional resistance between the rotating shaft and the sub-bearing.

[0011] In the second invention, the sub-bearing is disposed between the main bearing and the shaft seal that demarcates the region for holding the lubricating oil supplied to the main bearing on the rotating shaft (i.e., the oil-containing region where an oil film is formed). Therefore, the possibility of forming an oil film sufficient to reduce wear of the sub-bearing in the region of the rotating shaft in contact with the sub-bearing becomes high.

[0012] In the third invention, the sub-bearing is disposed between the main bearing and the annular convex portion for peeling off the lubricating oil supplied to the main bearing from the rotating shaft. For example, if the supercharger also has a shaft seal, the annular convex portion is disposed between the sub-bearing and the shaft seal. According to the third invention, the possibility of forming an oil film sufficient to reduce wear of the sub-bearing in the region of the rotating shaft in contact with the sub-bearing becomes high.

[0013] According to the fourth invention, wear of the sub-bearing and / or the region of the rotating shaft in contact with the sub-bearing is reduced, so the state in which the rotating shaft is held rotatable by the sub-bearing can be maintained for an even longer time. Description of the Drawings

[0014] Figure 1 is a schematic view (cross-sectional view) of the supercharger according to the embodiment.

[0015] Figure 2 is a partially enlarged view (cross-sectional view) of the supercharger.

[0016] Figure 3 is a cross-sectional perspective view of the sub-bearing of the supercharger.

[0017] Description of Reference Numerals

[0018] 1...Supercharger; 10...Main body housing; 11...Exhaust gas flow path; 12...Intake air flow path; 13...Bearing space; 14...Shaft receiving portion; 15...Supply path; 16...Discharge path; 21...Main bearing; 21a...Bearing oil hole; 41...Rotating shaft; 41a...Annular recess; 41b...Annular protrusion; 42...Turbine; 43...Impeller; 44...Shaft seal; 45...Auxiliary bearing; 45a...Oil groove; 51...Oil passage; A...Axial direction; B...Vertical direction; t1 to t5...Length (clearance). Detailed implementation mode

[0019] Refer to Figures 1 to 3 The implementation mode related to the present invention will be described. The same reference numerals (reference numbers) in the description refer to the same elements having the same functions without repeated description. The supercharger 1 related to the present implementation mode is disposed in an internal combustion engine (not shown) mounted on a vehicle as a power source. The supercharger 1 operates by the exhaust gas of the internal combustion engine and compresses the intake air with respect to the internal combustion engine.

[0020] As Figures 1 to 2 shown, the supercharger 1 includes a main body housing 10 and a main bearing 21, a rotating shaft 41, a turbine 42, an impeller 43, a pair of shaft seals 44 and a pair of auxiliary bearings 45 housed in the main body housing 10.

[0021] The main bearing 21 holds the rotating shaft 41 so as to be rotatable (freely rotatable). A turbine 42 is fixed to one end of the rotating shaft 41. An impeller 43 is fixed to the other end of the rotating shaft 41. That is, the turbine 42 and the impeller 43 rotate integrally with the rotating shaft 41 held (supported) by the main bearing 21. The rotating shaft 41, the turbine 42 and the impeller 43 are also collectively referred to as the "rotating body".

[0022] Figures 1 to 2 The single-dot chain line Lc shown represents the axis of the rotating shaft 41 (that is, the rotational center axis of the rotating shaft 41 held by the main bearing 21). Hereinafter, the extending direction of the single-dot chain line Lc is also referred to as the axial direction A. The supercharger 1 related to the present implementation mode is mounted on the above-mentioned vehicle so that the axial direction A is substantially horizontal. In addition, the direction orthogonal to the axial direction A and extending substantially vertically up and down is also referred to as the vertical direction B. The vertical direction B is also one of the radial directions of the rotating shaft 41.

[0023] An exhaust gas flow path 11, an intake air flow path 12, a bearing space 13, a pair of shaft receiving portions 14, a supply path 15 and a discharge path 16 are formed in the main body housing 10. The turbine 42 is housed in the exhaust gas flow path 11. The impeller 43 is housed in the intake air flow path 12.

[0024] The turbine 42 rotates due to the pressure of the exhaust gas discharged from the above-described internal combustion engine and flowing into the exhaust gas flow path 11. That is, the turbine 42 rotates due to the exhaust gas pressure of the internal combustion engine. The exhaust gas that rotates the turbine 42 flows out from the exhaust gas flow path 11. The impeller 43 that rotates together with the turbine 42 compresses the intake air flowing into the intake air flow path 12 and causes the intake air to flow out toward the internal combustion engine. That is, the high-pressure intake air is discharged from the intake air flow path 12.

[0025] Figures 1 to 2 In [description], the turbine 42 and the impeller 43 are indicated by a double-dashed line (housing line). More specifically, the set of positions (points) of the turbine 42 and the impeller 43 that are farthest from the single-dashed line Lc is indicated by a double-dashed line.

[0026] The minimum value of the length (gap, clearance) from the inner surface of the main body housing 10 that forms the exhaust gas flow path 11 to the turbine 42 is the length t1 (refer to Figure 1 ). Similarly, the minimum value of the length from the inner surface of the main body housing 10 that forms the intake air flow path 12 to the impeller 43 is the length t2. Since a gap is formed between the turbine 42 and the inner surface of the main body housing 10 and between the impeller 43 and the inner surface of the main body housing 10, contact (interference) between the turbine 42 and the impeller 43 and the inner surface of the main body housing 10 is avoided when the rotating body rotates.

[0027] The main bearing 21 is housed in the bearing space 13. The main bearing 21 has a substantially cylindrical shape, and the rotating shaft 41 is inserted through the main bearing 21. The main bearing 21 is a semi-floating type sliding bearing and is disposed between the inner wall surface of the main body housing 10 that forms the bearing space 13 and the outer peripheral surface of the rotating shaft 41 and holds (supports) the rotating shaft 41 so that it can rotate.

[0028] (Oil passage)

[0029] Figure 2 In [description], an example of the distribution pattern of the lubricating oil in the supercharger 1 is shown by a pattern. Lubricating oil is supplied from an oil pump (not shown) to the supply path 15. The lubricating oil supplied to the supply path 15 flows into the bearing space 13, and an oil film is formed between the inner wall surface of the bearing space 13 and the outer peripheral surface of the main bearing 21. In addition, an oil film is also formed between the inner peripheral surface of the main bearing 21 and the outer peripheral surface of the rotating shaft 41. That is, the main bearing 21 comes into contact with the region where the lubricating oil is held on the rotating shaft 41. More specifically, a plurality of bearing oil holes 21a are formed at substantially the central portion in the axial direction A of the main bearing 21. Each of the bearing oil holes 21a extends in the radial direction (that is, the direction orthogonal to the axial direction A). A part of the lubricating oil flowing into the bearing space 13 passes through the bearing oil holes 21a (in particular, the bearing oil holes 21a located above the rotating shaft 41) and the both end portions of the main bearing 21 (that is, Figure 2flows into the space between the inner peripheral surface of the main bearing 21 and the outer peripheral surface of the rotating shaft 41 from the outside of the left and right end portions of the shown main bearing 21.

[0030] The lubricating oil flowing into the bearing space 13 is discharged from the supercharger 1 via the discharge path 16. The lubricating oil forming the oil film between the inner peripheral surface of the main bearing 21 and the outer peripheral surface of the rotating shaft 41 reaches the discharge path 16 via the bearing oil hole 21a (specifically, the bearing oil hole 21a located below the rotating shaft 41). In addition, the lubricating oil supplied to the supercharger 1 does not necessarily need to specifically function as lubrication (i.e., friction reduction), and can also be an oil type having functions such as a sealing function and a cooling function.

[0031] (Shaft seal of lubricating oil)

[0032] The situation where the lubricating oil in the oil passage 51 reaches the turbine 42 and / or the impeller 43 is suppressed. Therefore, a labyrinth structure including the shaft seal 44 is formed in each of the shaft housing portions 14. More specifically described, the shaft seal 44 is fixed to the inner side surface of the main body housing 10 that forms the shaft housing portion 14. The shaft seal 44 has an annular shape, and the rotating shaft 41 is inserted through the shaft seal 44.

[0033] On the one hand, the inner peripheral surface of the shaft seal 44 protrudes toward the rotating shaft 41. On the other hand, an annular recess 41a corresponding to the shaft seal 44 is formed on the rotating shaft 41 (refer to Figure 2 ). Through the combination between the annular recess 41a of the rotating shaft 41 and the shaft seal 44 (i.e., the labyrinth structure), the movement of the fluid in the axial direction A is suppressed.

[0034] In the labyrinth structure, the length (i.e., the clearance) from the inner side surface of the main body housing 10 that forms the shaft housing portion 14 to the outer side surface of the rotating shaft 41 is relatively small. For the shaft housing portion 14 on the side of the turbine 42, the minimum value of the clearance from the rotating shaft 41 is the length t3 (refer to Figure 2 ). Similarly, for the shaft housing portion 14 on the side of the impeller 43, the minimum value of the clearance from the rotating shaft 41 is the length t4. The length t3 and the length t4 in the present embodiment are substantially equal to each other. In addition, the length t3 and the length t4 are respectively smaller than the length t1 and the length t2.

[0035] Moreover, in order to strip the lubricating oil on the rotating shaft 41 before it reaches the shaft seal 44, on the one hand, annular protrusions 41b are respectively formed in the intervals between the main bearing 21 and the shaft seal 44 on the rotating shaft 41 (refer to Figure 2)。On the other hand, the inner diameter of the shaft receiving portion 14 in the section facing the annular convex portion 41b becomes larger. That is, a concave portion corresponding to the annular convex portion 41b is formed on the inner side surface of the main body housing 10. The shaft receiving portion 14 is connected to the discharge path 16. In other words, the shaft receiving portion 14 connected to the discharge path 16 forms a discharge path for lubricating oil (i.e., an oil drain port).

[0036] When the supercharger 1 operates (i.e., when the rotating shaft 41 rotates), most of the lubricating oil flowing from the oil passage 51 toward the shaft seal 44 on the surface of the rotating shaft 41 leaves the rotating shaft 41 at the top of the annular convex portion 41b due to centrifugal force and flows into the shaft receiving portion 14. That is, at the position where the radius of the rotating shaft 41 is the largest in the section where the annular convex portion 41b is formed, the lubricating oil on the rotating shaft 41 peels off and flows into the shaft receiving portion 14. The lubricating oil flowing into the shaft receiving portion 14 is discharged via the discharge path 16.

[0037] (Auxiliary bearing)

[0038] The auxiliary bearings 45 are each fixed to the inner side surface of the main body housing 10 forming the shaft receiving portion 14 and at a position between the main bearing 21 and the annular convex portion 41b. That is, the auxiliary bearings 45 are arranged in the axial direction of the rotating shaft between the main bearing and the shaft seal. The auxiliary bearings 45 have an annular shape, and the rotating shaft 41 is inserted through the auxiliary bearings 45. The gap between the outer peripheral surface of the rotating shaft 41 held by the main bearing 21 and the inner peripheral surface of the auxiliary bearing 45 is a length t5 (refer to Figure 2 ). That is, the radius of the cylindrical through-hole formed by the inner peripheral surface of the auxiliary bearing 45 is larger than the radius of the section of the rotating shaft 41 facing the auxiliary bearing 45 by a length t5. The length t5 is smaller than each of the lengths t1 to t4.

[0039] More specifically, the vibration deviation of the main bearing 21 is smaller than the length t5. In other words, the whirling vibration of the rotating shaft 41 rotatably held by the main bearing 21 is smaller than the length t5, so that no contact (interference) occurs between the rotating shaft 41 and the auxiliary bearing 45. That is, a gap (space) is formed between the outer peripheral surface of the rotating shaft 41 and the inner peripheral surface of the auxiliary bearing 45.

[0040] However, as the vibration deviation of the main bearing 21 becomes larger due to breakage and damage, etc., the gap between the rotating shaft 41 and the auxiliary bearing 45 becomes smaller. If the vibration deviation of the main bearing 21 is relatively large (i.e., the main bearing 21 deteriorates in performance), one or both of the rotating shaft 41 and the auxiliary bearing 45 come into contact. In other words, when the main bearing 21 cannot hold the rotating shaft 41 rotatably, the rotating shaft 41 is held rotatably by the auxiliary bearing 45.

[0041] When the rotary shaft 41 is rotatably held by the auxiliary bearing 45, the whirling vibration of the rotary shaft 41 (i.e., the vibration deviation of the rotary shaft 41 held by the auxiliary bearing 45) is smaller than each of the lengths t1 to t4. In other words, compared with the case where the rotary shaft 41 is held by the main bearing 21, the whirling vibration of the rotary shaft 41 becomes larger when the rotary shaft 41 is rotatably held by the auxiliary bearing 45. However, the length t5 is adjusted so that the rotating body does not contact the surrounding members (specifically, the main body housing 10 and the shaft seal 44) even when the rotary shaft 41 is rotatably held by the auxiliary bearing 45.

[0042] As Figure 3 shown, an oil groove 45a is formed in the auxiliary bearing 45. More specifically, the oil groove 45a is a recess extending in the axial direction A on the inner peripheral surface of the auxiliary bearing 45 (i.e., the surface facing the outer peripheral surface of the rotary shaft 41). The oil grooves 45a are provided at 120° intervals with respect to the center of the auxiliary bearing 45 having an annular shape. That is, three oil grooves 45a are formed in the auxiliary bearing 45. Figure 3 Two of the oil grooves 45a are shown.

[0043] The auxiliary bearing 45 of the present embodiment is made of phosphor bronze, which is one of the wear-resistant materials. Therefore, the auxiliary bearing 45 has excellent wear resistance, and even when the rotary shafts 41 held by the respective auxiliary bearings 45 rotate, wear of the auxiliary bearing 45 (i.e., change in shape and further increase in the whirling vibration of the rotary shaft 41 held by the auxiliary bearing 45) is suppressed. As the wear-resistant material constituting the auxiliary bearing 45, a copper-based alloy (e.g., copper-lead alloy) or an aluminum alloy (e.g., aluminum-tin alloy) can also be used. As an example, the auxiliary bearing 45 is formed to have an inner diameter (i.e., the diameter of the through hole through which the rotary shaft 41 is inserted) of about 10 mm and a thickness (i.e., the length in the axial direction A) of 3 to 5 mm. In addition, the rotary shaft 41 is also made of a wear-resistant material.

[0044] As described above, according to the supercharger 1, when the main bearing 21 cannot hold the rotary shaft 41 rotatably, the rotary shaft 41 is rotatably held by the auxiliary bearing 45. That is, even when performance deterioration occurs in the main bearing 21, the rotating body (i.e., the rotary shaft 41, the turbine 42, and the impeller B) is held (supported) rotatably without interfering with the surrounding members, and thus the supercharger 1 can continue to operate.

[0045] As described above, the lengths t3 and t4 are smaller than the lengths t1 and t2, respectively. Therefore, assuming that the auxiliary bearing 45 is not provided in the supercharger 1 and the main bearing 21 cannot keep the rotating shaft 41 rotatable, the rotating body contacts the inner side surface of the shaft seal 44 and the inner side surface of the main body housing 10 in the region near the shaft seal 44 (not the inner side surfaces of the exhaust gas flow path 11 and the intake air flow path 12). That is, in this case, the rotation of the rotating body is hindered and the operation of the supercharger 1 is difficult to continue.

[0046] In addition, when the auxiliary bearing 45 holds the rotating shaft 41, the auxiliary bearing 45 abuts against the region where an oil film is formed on the rotating shaft 41 (that is, the region where lubricating oil is held and is also referred to as the "oil region"). Therefore, the generation of wear on the auxiliary bearing 45 and / or the rotating shaft 41 can be suppressed. That is, the state in which the auxiliary bearing 45 keeps the rotating shaft 41 rotatable can be maintained for a relatively long time. In addition, the formation of an oil film in the region of the rotating shaft 41 facing the auxiliary bearing 45 also helps to reduce the frictional resistance between the rotating shaft 41 and the auxiliary bearing 45.

[0047] More specifically, lubricating oil is supplied to the bearing space 13 via the supply path 15, so an oil film is formed between the main bearing 21 and the rotating shaft 41. Even if the lubricating oil supplied to the rotating shaft 41 flows toward the turbine 42 and / or the impeller 43, most of the lubricating oil is peeled off from the rotating shaft 41 by the annular convex portion 41b. Moreover, the shaft seal 44 suppresses the lubricating oil from reaching the turbine 42 and / or the impeller 43. That is, the shaft seal 44 demarcates the oil region. Therefore, it is very likely that an oil film sufficient to reduce the wear of the auxiliary bearing 45 is formed in the region between the main bearing 21 and the annular convex portion 41b on the rotating shaft 41. In other words, the lubricating oil flowing into the supercharger 1 via the supply path 15 is sufficiently supplied to the main bearing 21 and the auxiliary bearing 45.

[0048] In addition, the rotating shaft 41 being made of a wear-resistant material is more helpful for reducing the wear of the auxiliary bearing 45. On the other hand, even when the rotating shaft 41 is kept rotatable by the auxiliary bearing 45, the rotating shaft 41 does not contact the shaft seal 44, so it is not necessary to make the shaft seal 44 of a wear-resistant material.

[0049] Moreover, an oil groove 45a is formed in the auxiliary bearing 45 to promote the uniform distribution of the oil film formed in the region of the rotating shaft 41 facing the auxiliary bearing 45. That is, the oil groove 45a helps to reduce the wear of the auxiliary bearing 45 and the frictional resistance between the rotating shaft 41 and the auxiliary bearing 45.

[0050] As described above, embodiments of the present invention have been described with reference to the above configuration, but various substitutions, improvements, and changes can be made without departing from the object of the present invention. Therefore, the embodiments of the present invention may include all substitutions, improvements, and changes that do not depart from the spirit and object of the appended claims. The embodiments of the present invention are not limited to the above specific configuration, and for example, changes can be made as follows.

[0051] The main bearing 21 is a sliding bearing. Alternatively, the main bearing 21 may be constituted by a rolling bearing (i.e., a ball bearing including rolling elements) that holds the rotating shaft 41 rotatably. Even in this case, the main bearing 21 holds the rotating shaft 41 rotatably, and when the main bearing 21 cannot hold the rotating shaft 41 rotatably, the rotating shaft 41 is held rotatably by the sub-bearing 45. In addition, the rolling bearing (particularly, the rolling elements included in the rolling bearing) also contacts the rotating shaft 41 via an oil film (i.e., lubricating oil supplied through the oil passage 51 and held on the rotating shaft 41).

[0052] The sub-bearing 45 is made of a wear-resistant material. Alternatively, the sub-bearing 45 may be made of a known iron-based material, and a plating process using a wear-resistant material may be performed on the inner circumferential surface of the sub-bearing 45 (i.e., the region in contact with the rotating shaft 41). In other words, the entire sub-bearing 45 may not be made of a wear-resistant material. Or, a plating process using a wear-resistant material may be performed on the region of the rotating shaft 41 facing the sub-bearing 45. At least the section of the rotating shaft 41 facing the sub-bearing 45 may also be made of a wear-resistant material.

[0053] The turbine 42 and the impeller 43 are fixed to the rotating shaft 41. Alternatively, the turbine 42, the impeller 43, and the rotating shaft 41 (i.e., the rotating body) may be integrally formed.

Claims

1. A supercharger, characterized in that, comprising: a rotating shaft provided with a turbine and an impeller; a main bearing that contacts an oil-containing region of the rotating shaft holding lubricating oil and holds the rotating shaft rotatably; and a sub-bearing that contacts the oil-containing region and holds the rotating shaft rotatably when the main bearing fails to hold the rotating shaft.

2. The supercharger according to claim 1, characterized in that it has a shaft seal for demarcating the oil-containing region, in the axial direction of the rotating shaft, the sub-bearing is disposed between the main bearing and the shaft seal.

3. The supercharger according to claim 1 or 2, characterized in that a ring-shaped convex portion for peeling the lubricating oil from the rotating shaft is formed on the rotating shaft, the sub-bearing is disposed between the main bearing and the ring-shaped convex portion.

4. The supercharger according to claim 1, characterized in that at least one of a region of the rotating shaft that contacts the sub-bearing and a region of the sub-bearing that contacts the rotating shaft is made of a wear-resistant material.

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