Turbosupercharger

Abstract

To prevent leakage of lubricant oil from a turbosupercharger into an air discharge passage.SOLUTION: In a turbosupercharger 1, a turbine wheel and a compressor wheel 3 are connected to opposite ends of a shaft 4, and a first inner space 21 is formed in a housing 6 through which the shaft 4 penetrates. The first inner space 21 includes a first inner wall face 21a for receiving lubricant oil that is ejected from a gap between a first stepped face 4a and one end part 5a in a radial direction of the shaft 4 due to a centrifugal force caused by rotation of the shaft 4. The first inner wall face 21a includes a step 31 that projects toward the shaft 4 on a first seal member 7 side relative to a collision position P of ejected lubricant oil along the first stepped face 4a facing the gap between the first stepped face 4a and the one end part 5a in the radial direction of the shaft 4.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a turbocharger. [Background technology]

[0002] For example, Patent Document 1 discloses an exhaust turbocharger having a rotating shaft having turbine blades fixed to one end thereof, a housing through which the rotating shaft is inserted, a bearing portion that rotatably supports the rotating shaft within the housing, a first seal portion that seals between the housing and the rotating shaft at a position close to the turbine blades, a second seal portion that seals between the housing and the rotating shaft at a position close to the bearing portion, a downward-opening hollow portion that is located between the first seal portion and the second seal portion, and a visor portion that protrudes from an inner surface of the hollow portion that is located on the first seal portion side toward the bearing portion so as to cover the rotating shaft from above. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-190353 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in Patent Document 1, if a large amount of lubricating oil reaches the wall surface on the turbine blade side within the cavity, there is a risk that the lubricating oil will drip from the tip of the eaves onto the rotating shaft and easily reach the first seal portion.

[0005] Therefore, if the amount of lubricating oil that reaches the first seal portion increases, there is a risk that the amount of lubricating oil that passes over the first seal portion and enters the turbine blade side will also increase.

[0006] In other words, there is room for further improvement in preventing leakage of the lubricating oil that lubricates the rotating shaft of the turbocharger to the outside. [Means for solving the problem]

[0007] The turbocharger of the present invention is a turbocharger having wheels connected to both ends of a shaft, and includes a housing that rotatably supports the shaft via bearings, and a seal member that seals an internal space of the housing through which the shaft passes and a space in which the wheels are disposed. The shaft has a stepped surface facing an end of the bearing in a thrust direction. The internal space has an inner wall surface that receives lubricating oil that has spurted out from a gap between the stepped surface and the end. The inner wall surface faces the gap in the radial direction of the shaft and has a step that protrudes toward the shaft, closer to the seal member than a collision position of lubricating oil that spurts out from the gap along the stepped surface. [Effects of the Invention]

[0008] According to the present invention, it is possible to prevent the lubricating oil from flowing along the inner wall surface toward the seal member, and to prevent the lubricating oil in the internal space from leaking toward the space where the wheel is disposed. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a cross-sectional view of a turbocharger according to the present invention. [Figure 2] 1 is an enlarged cross-sectional view showing a main part of a turbocharger according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0010] An embodiment of the present invention will be described in detail below with reference to the drawings.

[0011] A turbocharger 1 according to the present invention will be described with reference to Figures 1 and 2. Figure 1 is a cross-sectional view of the turbocharger 1 according to the present invention. Figure 2 is an enlarged cross-sectional view showing a main part of the turbocharger 1 according to the present invention.

[0012] The turbocharger 1 is used in, for example, an internal combustion engine mounted on a vehicle.

[0013] The turbocharger 1 has a metal turbine wheel 2, a metal compressor wheel 3, a metal shaft 4 that coaxially connects these wheels 2, 3, a metal housing 6 that rotatably supports the shaft 4 via a cylindrical bearing 5, a metal first seal member 7 that seals between an internal space 9 of the housing 6 through which the shaft 4 passes and an exhaust passage 10, and a metal second seal member 8 that seals between the internal space 9 and an intake passage 11. A turbine wheel 2 serving as a wheel is attached to one end of a shaft 4. The turbine wheel 2 is located outside a housing 6 and disposed above an exhaust passage 10 of the internal combustion engine.

[0014] A compressor wheel 3 serving as a wheel is attached to the other end of the shaft 4. The compressor wheel 3 is located outside the housing 6 and disposed above an intake passage 11 of the internal combustion engine.

[0015] The shaft 4 has a stepped cylindrical shape overall, and has step surfaces 4a, 4b that face the thrust direction ends 5a, 5b of the bearing 5. At one end side (left side in FIG. 1) of the shaft 4, a first step surface 4a is formed as a step surface that faces the end face of the one end 5a, which is the thrust direction end of the bearing 5. At the other end side (right side in FIG. 1) of the shaft 4, a second step surface 4b is formed as a step surface that faces the end face of the other end 5b, which is the thrust direction end of the bearing 5.

[0016] The first step surface 4a and the second step surface 4b are aligned with the central axis C of the shaft 4. L It is formed so as to be perpendicular to the

[0017] The shaft 4 has a central portion 12 that is inserted into the bearing 5, a first large diameter portion 13 on the turbine wheel 2 side that is located outside the bearing 5 and has a larger diameter than the central portion 12, and a second large diameter portion 14 on the compressor wheel 3 side that is located outside the bearing 5 and has a larger diameter than the central portion 12.

[0018] The central portion 12 is supported inside (inside) the housing 6 via a bearing 5 .

[0019] The turbine wheel 2 is previously integrated with the first large diameter portion 13 at one end side by welding. The other end side of the first large diameter portion 13 is continuous with the central portion 12. The first large diameter portion 13 is formed so that its outer diameter is larger than that of the bearing 5.

[0020] The central portion 12 is supported by the housing 6 via a bearing 5 .

[0021] The second large diameter portion 14 is composed of a shaft portion 15 that is continuous with the central portion 12, and a cylindrical tubular member 16 that is fitted onto one end of the shaft portion 15. The shaft portion 15 has a smaller diameter than the other end of the central portion 12. The tubular member 16 is fixed to the shaft portion 15 so as to rotate integrally with the shaft portion 15, and is formed so that its outer diameter is larger than that of the bearing 5.

[0022] The compressor wheel 3 is fixed to the other end of the shaft portion 15 so as to rotate integrally with the shaft portion 15. The compressor wheel 3 is fixed to the shaft portion 15 so that, for example, one end of the cylindrical member 16 abuts against a step at the portion where the shaft portion 15 and the central portion 12 are connected.

[0023] The boundary between the first large diameter portion 13 and the central portion 12 of the shaft 4 is stepped around the entire circumference, forming a first step surface 4a. The boundary between the second large diameter portion 14 and the central portion 12 of the shaft 4 is stepped along the axial direction of the shaft 4 around the entire circumference, forming a second step surface 4b. More specifically, the second step surface 4b is formed by an end surface 16a on one end side of a cylindrical member 16 that constitutes the second large diameter portion 14.

[0024] The bearing 5 is, for example, a plain bearing, and is disposed inside the housing 6 and fixed by a fixing member 17. One end 5a of the bearing 5 is an end on the turbine wheel 2 side in the thrust direction. The other end 5b of the bearing 5 is an end on the compressor wheel 3 side in the thrust direction. Lubricating oil is supplied to the sliding surface of the bearing 5 from a lubricating oil supply passage 18 formed in the housing 6. Reference numeral 19 in FIG. 1 denotes a through hole formed in the bearing 5 that can supply lubricating oil to the inner peripheral side of the bearing 5. The lubricating oil supplied to the inner peripheral side of the bearing 5 reaches the first step surface 4a or the second step surface 4b along the axial direction of the shaft 4.

[0025] The housing 6 has an internal space 9 formed therein through which the shaft 4 passes. The internal space 9 has a first internal space 21 formed around the outer periphery of the other end side of the first large diameter portion 13, a second internal space 22 formed around the outer periphery of one end side of the second large diameter portion 14, and a third internal space 23 that is continuous with the first internal space 21 and the second internal space 22 below the shaft 4.

[0026] The first internal space 21 has a first inner wall surface 21a that serves as an inner wall surface that receives lubricating oil that is sprayed radially of the shaft 4 through the gap between the first step surface 4a and one end 5a of the bearing 5 due to centrifugal force caused by the rotation of the shaft 4.

[0027] The second internal space 22 has a second inner wall surface 22a that serves as an inner wall surface that receives lubricating oil that is sprayed radially of the shaft 4 through the gap between the second step surface 4b and the other end 5b of the bearing 5 due to centrifugal force caused by the rotation of the shaft 4.

[0028] The third internal space 23 joins the lubricating oil ejected into the first internal space 21 and the second internal space 22, and discharges the lubricating oil from below to an oil pan (not shown) via a pipe (not shown).

[0029] The housing 6 has a water jacket (not shown) formed around the first internal space 21. Therefore, the first internal space 21 has a smaller inner diameter in the radial direction of the shaft 4 than the second internal space 22.

[0030] Since the second internal space 22 does not have a water jacket set around it, it is possible to make the inner diameter in the radial direction of the shaft 4 larger than that of the first internal space 21. Therefore, the second internal space 22 can collect the lubricating oil that is sprayed upward from the second internal space 22 so that it does not flow toward the second seal member 8, thereby suppressing the lubricating oil from flowing toward the second seal member 8.

[0031] The first seal member 7 and the second seal member 8 as seal members are, for example, annular seal rings having a gap.

[0032] The first seal member 7 is located between the outer peripheral surface 13a of the first large diameter portion 13 and the inner peripheral surface 25a of the one-end hole 25 of the housing 6 through which the first large diameter portion 13 passes, and provides a seal to prevent lubricating oil from leaking from the first internal space 21 toward the exhaust passage 10. The first seal member 7 is located closer to the exhaust passage than the first internal space 21 in the axial direction of the shaft 4.

[0033] The second seal member 8 is located between the outer peripheral surface 16b of the cylindrical member 16 (second large diameter portion 14) and the inner peripheral surface 26a of the other end side hole 26 of the housing 6, through which the cylindrical member 16 (second large diameter portion 14) passes, and provides a seal to prevent lubricating oil from leaking from the second internal space 22 toward the intake passage 11. The second seal member 8 is located closer to the intake passage than the second internal space 22 in the axial direction of the shaft 4.

[0034] The first inner wall surface 21a has a collision position P at a position facing the gap between the first step surface 4a and one end 5a of the bearing 5 in the radial direction of the shaft 4. The collision position P is a position at which lubricating oil spurting from the gap between the first step surface 4a and one end 5a of the bearing 5 along the first step surface 4a in the radial direction of the shaft 4 collides. As shown by the dashed line in FIG. 2, the collision position P is located on a plane including the first step surface 4a.

[0035] The first inner wall surface 21a has a step 31 that protrudes toward the shaft 4, closer to the first seal member 7 than the collision position P.

[0036] The step 31 is formed by a protrusion 32 that protrudes from the first inner wall surface 21a. The protrusion 32 is formed in the range of the upper half of the first inner wall surface 21a when the vehicle is mounted. The protrusion 32 is a protrusion with a height (amount of protrusion) of, for example, about 0.5 mm. Alternatively, the protrusion 32 may be formed with a height of, for example, 0.5 mm or more.

[0037] Moreover, the first internal space 21 is formed so that there is nothing obstructing the gap between the first step surface 4a and one end 5a of the bearing 5 and the collision position P facing this gap. In other words, the first internal space 21 is formed so that there is nothing obstructing the plane including the first step surface 4a.

[0038] A part of the lubricating oil that collides with the first inner wall surface 21a on the upper side of the first internal space 21 of the turbocharger 1 will head toward the first seal member 7. However, after colliding with the first inner wall surface 21a, the lubricating oil that heads along the first inner wall surface 21a toward the first seal member 7 hits the step 31 and is blocked by this step 31.

[0039] That is, the turbocharger 1 can prevent the lubricating oil from flowing down the first inner wall surface 21a toward the first seal member 7 by forming the step 31 on the first inner wall surface 21a.

[0040] As a result, the turbocharger 1 reduces the amount of lubricating oil that reaches the first seal member 7 from the first internal space 21, thereby preventing the lubricating oil in the first internal space 21 from leaking into the exhaust passage 10.

[0041] The first internal space 21 is configured so that there is nothing obstructing the gap between the first step surface 4a and one end 5a of the bearing 5 and the collision position P opposite this gap.

[0042] Therefore, in the turbocharger 1, the lubricating oil spurting out from the gap between the first step surface 4a and one end 5a of the bearing 5 collides forcefully with the first inner wall surface 21a at the collision position P. Then, the lubricating oil that has collided with the first inner wall surface 21a and is moving toward the step 31 along the first inner wall surface 21a also collides forcefully with the step 31.

[0043] As a result, the lubricating oil that collides with the step 31 turns around and changes direction with great force, thereby efficiently suppressing the flow of lubricating oil toward the first seal member 7. In other words, the lubricating oil that collides with the step 31 turns around and changes direction with great force, thereby preventing the lubricating oil from being forced toward the first seal member 7.

[0044] The step 31 is formed by a protrusion 32 formed to protrude from the first inner wall surface 21a.

[0045] Therefore, in the turbocharger 1, the lubricating oil is more likely to drip from the tip portion of the ridge 32 due to gravity, and the lubricating oil can be further prevented from flowing along the first inner wall surface 21a toward the first seal member 7 side.

[0046] The step 31 is formed in the range of the upper half of the first inner wall surface 21a.

[0047] The lubricating oil that runs down the first inner wall surface 21a below the first seal member 7 flows downward due to gravity regardless of whether or not there is a step 31, and therefore does not easily flow toward the first seal member 7.

[0048] On the other hand, the lubricating oil running down the first inner wall surface 21a above the first seal member 7 may reach the first seal member 7 along the way if it flows downward due to gravity.

[0049] Therefore, by providing the step 31 at a necessary portion, the turbocharger 1 can efficiently prevent the lubricating oil from flowing down the first inner wall surface 21a toward the first seal member 7 side.

[0050] Furthermore, by providing the step 31 in the first internal space 21, even if the inner diameter in the radial direction of the shaft 4 is set smaller than that of the second internal space 22, it is possible to make it difficult for the lubricating oil to flow toward the first seal member 7, thereby improving the design freedom of the water jacket formed around the first internal space 21 in the housing 6. In the turbocharger 1, if the water jacket formed around the first internal space 21 can be made larger, the cooling performance of the turbine wheel 2 can be improved, and the heat resistance performance can be improved.

[0051] Although specific embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the invention.

[0052] For example, in the turbocharger 1, the step 31 provided in the first internal space 21 of the housing 6 may be provided not by the protrusion 32 but by forming the first inner wall surface 21 a in a stepped shape along the axial direction of the shaft 4, as shown by the dashed line Q in Figure 2.

[0053] Furthermore, the turbocharger 1 may have a step similar to the step 31 on the first inner wall surface 21a formed on the second inner wall surface 22a of the second internal space 22. The step on the second inner wall surface 22a may be formed closer to the second seal member 8 than the collision position that faces the gap between the second stepped surface 4b and the other end 5b of the bearing 5 in the radial direction of the shaft 4. [Explanation of symbols]

[0054] 1...Turbocharger 2...Turbine wheel 3...Compressor wheel 4...Shaft 4a…1st step surface 4b…Second step surface 5...Bearing 5a...One end 5b...Other end 6. Housing 7...First seal member 8...Second seal member 9...Interior space 10...Exhaust passage 11...Intake passage 13...First large diameter section 13a...Outer surface 14...Second large diameter section 15...Shaft 16...Cylindrical member 16a...end face 16b…Outer surface 21...First internal space 21a...First inner wall surface 22…Second internal space 22a...Second inner wall surface 31...Step 32...projection

Claims

1. A turbocharger having wheels connected to both ends of a shaft, a housing that rotatably supports the shaft via a bearing; a seal member that seals between an internal space of the housing through which the shaft passes and a space in which the wheel is disposed, the shaft has a stepped surface facing an end of the bearing in a thrust direction, the internal space has an inner wall surface that receives lubricating oil spurting out from a gap between the step surface and the end portion, the inner wall surface has a step that faces the gap in the radial direction of the shaft and protrudes toward the shaft on the seal member side of a collision position of lubricating oil sprayed from the gap along the step surface.

2. 2. The turbocharger according to claim 1, wherein the internal space is formed so that there is nothing between the gap and the collision position of the inner wall surface facing the gap.

3. The turbocharger according to claim 1, wherein the step is formed by a protrusion formed on the inner wall surface.

4. 2. The turbocharger according to claim 1, wherein, when the turbocharger is mounted on a vehicle, the step is formed in an upper half of the inner wall surface.

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