Patent Grant
11156123
The present disclosure relates to a turbocharger including a bearing housing, a turbine housing, and a uniting member that is fitted to connection sections thereof from the outside.
There has been known a turbocharger in which a turbine wheel is rotatably arranged in an assembly of a turbine housing and a bearing housing (e.g., Patent Document 1). According to the turbocharger, energy exhausted from an engine is utilized as power to rotate the turbine wheel and air is supercharged to the engine with use of the rotation of the turbine wheel. The exhaust gas is supplied toward the turbine wheel after passing through a scroll flow path being a whorl-shaped exhaust gas flow path formed in the turbine housing.
Patent Document 1 discloses a uniting configuration with which the turbine housing and the bearing housing are united by a uniting member fitted from the outside to interpose connection sections of the turbine housing and the bearing housing with a back plate (heat-insulating plate) interposed between the connection sections. The uniting configuration performs sealing to prevent outward leakage of exhaust gas by the back plate being interposed between the turbine housing and the bearing housing.
Patent Document 2 discloses a turbocharger in which a flange portion of a bearing housing is interposed between a flange of a flanged bolt and an inner end face of a turbine housing. The interposing is performed by screwing the flanged bolt into a bolt hole formed on an outer circumferential side of a connection section of the turbine housing in a state that the flange portion of the bearing housing is fitted to a stepped portion arranged on an inner circumferential side of the connection section. Here, the stepped portion has an inner end face concaved in the axial direction from an end face on the outer circumferential side of the connection section. In the turbocharger, ring-shaped space being rectangular in section is formed between the flange portion of the bearing housing and the inner end face of the turbine housing and a sealing ring is arranged in the ring-shaped space. Accordingly, sealing is provided to prevent outward leakage of exhaust gas.
Patent Document 1: JP2013-174129A
Patent Document 2: JP2015-25460A
Recently, temperature of combustion gas of an engine tends to increase for improvement of engine power, and accordingly, temperature of exhaust gas exhausted from an engine tends to increase as well. Since high temperature of exhaust gas causes large thermal expansion and large thermal deformation of a turbine housing and a bearing housing, there arises an increasing fear that clearance is formed between the turbine housing and the bearing housing and exhaust gas leaks outward through the clearance.
For example, in the turbocharger disclosed in Patent Document 1, there is a fear that thermal expansion and thermal deformation of the turbine housing and the bearing housing under high temperature cause reduction of force generated by the turbine housing and the bearing housing to fasten the back plate, and accordingly, cause clearance to appear between the turbine housing and the back plate and exhaust gas to leak outward through the clearance.
Further, in the turbocharger disclosed in Patent Document 2, there is a fear that thermal expansion and thermal deformation of the turbine housing and the bearing housing under high temperature cause the connection section of the turbine housing to be extended in the axial direction, and accordingly, cause reduction of force generated by the flange of the flanged bolt and the inner end face of the turbine housing to fasten the flange portion of the bearing housing. When the force to fasten the flange portion of the bearing housing is reduced, force to press the sealing ring is reduced and sealing function is deteriorated. Accordingly, exhaust gas may leak outward.
In this regard, it is an object of at least one embodiment of the present invention to provide a turbocharger capable of suppressing outward leakage of exhaust gas with a sealing member capable of providing excellent sealing function even when thermal expansion and thermal deformation occur at the turbine housing and the bearing housing.
(1) A turbocharger according to at least one of embodiments of the present invention includes a shaft, a bearing housing accommodating a bearing rotatably supporting the shaft, a turbine housing accommodating a turbine wheel arranged at one end of the shaft in an axial direction, and a uniting member uniting the bearing housing and the turbine housing. Here, the bearing housing includes a first connection section protruded in a radial direction of the shaft, the first connection section having a first face extended in the radial direction, the turbine housing includes a second connection section protruded in the radial direction of the shaft, the second connection section having a second face extended in the radial direction and being faced to the first face, the uniting member interposes the first connection section and the second connection section by being fitted to the first connection section and the second connection section from the outside, and at least one of the first face and the second face includes a ring-shaped concave portion on an inner side in the radial direction of the shaft with a sealing member arranged at the ring-shaped concave portion.
According to the configuration described above as (1), the bearing housing includes the first connection section protruded in the radial direction of the shaft and the first connection section includes the first face extended in the radial direction. The turbine housing includes the second connection section protruded in the radial direction of the shaft and the second connection section includes the second face extended in the radial direction and faced to the first face of the first connection section. The uniting member interposes the first connection section and the second connection section by being fitted to the first connection section and the second connection section from the outside with the first face of the first connection section and the second face of the second connection section faced to each other.
Thus, since the uniting member is fitted to the first connection section and the second connection section from the outside to interpose the first connection section and the second connection section, the turbine housing and the bearing housing can be extended in the axial direction of the shaft due to thermal expansion and thermal deformation under high temperature. Since the turbine housing is more influenced by heat of exhaust gas than the bearing housing, the turbine housing is extended in the axial direction of the shaft more than the bearing housing. Accordingly, the second connection section becomes close to the first connection section so that clearance between the first face and the second face becomes small or zero. Owing to that the first connection section and the second connection section become close to each other under the thermal influence of exhaust gas, the sealing member arranged at the ring-shaped concave portion on the radially inner side of the first face and/or the second face is urged to be compressed in the axial direction of the shaft by the ring-shaped concave portion, the first face, and/or the second face. Accordingly, since the sealing member is reliably interposed by the ring-shaped concave portion, the first face, and/or the second face, the sealing member can suppress outward leakage of exhaust gas and provide excellent sealing function.
(2) In some embodiments, in the configuration described above as (1), the uniting member includes a first end section locked on a third face of the first connection section, the third face being on an opposite side to the first face in the axial direction of the shaft, a second end section locked on a fourth face of the second connection section, the fourth face being on an opposite side to the second face in the axial direction of the shaft, and a joint section joined to the first end section and the second end section.
According to the configuration described above as (2), since the uniting member includes the first end section locked on the third face of the bearing housing, the second end section locked on the fourth face of the turbine housing, and the joint section joined to the first end section and the second end section, the first connection section and the second connection section are fitted to a fitting concave segment formed by the first end section, the second end section, and the joint section on the inner side thereof in the radial direction of the shaft. Here, since the first end section and the second end section are locked on the third face of the first connection section and the fourth face of the second connection section respectively, the uniting member can prevent the first connection section and the second connection section from being distanced from each other by a predetermined distance or larger in the axial direction of the shaft. Accordingly, the sealing member performing sealing between the first connection section and the second connection section can provide excellent sealing function.
(3) In some embodiments, in the configuration described above as (2), the first connection section includes a taper section formed on the third face so that thickness of the first connection section gradually becomes larger toward the inner side in the radial direction of the shaft from an outer circumferential face, the second connection section includes a taper section formed on the fourth face so that thickness of the second connection section gradually becomes larger toward the inner side in the radial direction of the shaft from an outer circumferential face, and the first end section and the second end section of the uniting member are extended in directions inclined to the radial direction of the shaft so that distal ends thereof are to be more distanced from each other.
According to the configuration described above as (3), the first connection section includes the taper section formed on the third face so that thickness of the first connection section gradually becomes larger toward the inner side in the radial direction of the shaft from the outer circumferential face of the first connection section. Further, the second connection section includes the taper section formed on the fourth face so that thickness of the second connection section gradually becomes larger toward the inner side in the radial direction of the shaft from the outer circumferential face of the second connection section. Further, the first end section and the second end section of the uniting member are extended in the directions inclined to the radial direction of the shaft so that the distal ends thereof are to be more distanced from each other. Accordingly, since the first end section is locked in the taper section formed on the third face and the second end section is locked in the taper section formed on the fourth face, the uniting member can interpose the first connection section and the second connection section in the axial direction of the shaft as well as in the radial direction of the shaft. In a case that the second connection section of the turbine housing is extended outward in the radial direction of the shaft due to thermal expansion and thermal deformation under high temperature, fastening force of the uniting member exerted on the first connection section and the second connection section is increased. Accordingly, since the first connection section and the second connection section are firmly interposed by the uniting member, the sealing member performing sealing between the first connection section and the second connection section can provide excellent sealing function even under high temperature.
(4) In some embodiments, the turbocharger described above as any one of (1) to (3) further includes a back plate arranged between the turbine wheel and the bearing housing. Here, the bearing housing includes an end face formed on a side toward the turbine wheel with respect to the first connection section in the axial direction of the shaft and extended in the radial direction of the shaft, the turbine housing includes a back plate supporting section arranged on a side toward the turbine wheel with respect to the second connection section in the axial direction of the shaft and extended radially inward in the radial direction of the shaft, and the back plate is arranged so that an outer circumferential edge section extended in the radial direction of the shaft is interposed between the back plate supporting section and the end face.
According to the configuration described above as (4), compared to the sealing portion for exhaust gas formed by the back plate, the end face of the bearing housing, and the back plate supporting section of the turbine housing, the first connection section and the second connection section are arranged at positions farther in the axial direction of the shaft from the turbine wheel and the exhaust gas flow path through which exhaust gas flows toward the turbine wheel. Therefore, temperature increase due to exhaust gas is small and influences due to thermal expansion and thermal deformation are small as well. Accordingly, the sealing member performing sealing between the first connection section and the second connection section can provide excellent sealing function even under high temperature.
Further, temperature increase due to exhaust gas is also small at the sealing member performing sealing between the first connection section and the second connection section. Therefore, in a case that the sealing member is formed of a metal material, it is not necessary to adopt expensive heat-resistant alloy. Accordingly, it is possible to prevent cost increase of the sealing member and the turbocharger including the sealing member.
(5) In some embodiments, in the configuration described above as any one of (1) to (4), the ring-shaped concave portion is arranged at the second connection section.
According to the configuration described above as (5), since the sealing member arranged at the ring-shaped concave portion formed at the second connection section is interposed by the ring-shaped concave portion and the first face of the first connection section, the sealing member can provide excellent sealing function. Further, since the sealing member is arranged at the ring-shaped concave portion of the second connection section, dropping of the sealing member can be prevented at the time of assembling the bearing housing to the turbine housing and assembling operability can be improved.
(6) In some embodiments, in the configuration described above as any one of (1) to (4), the ring-shaped concave portion is arranged at the first connection section.
According to the configuration described above as (6), since the sealing member arranged at the ring-shaped concave portion formed at the first connection section is interposed by the ring-shaped concave portion and the second face of the second connection section, the sealing member can provide excellent sealing function. Further, since the sealing member is arranged at the ring-shaped concave portion of the first connection section, dropping of the sealing member can be prevented at the time of assembling the turbine housing to the bearing housing and assembling operability can be improved.
(7) In some embodiments, in the configuration described above as any one of (1) to (4), the ring-shaped concave portion is arranged at the second connection section and the first connection section.
According to the configuration described above as (7), since the sealing member is arranged between the ring-shaped concave portion formed at the first connection section and the ring-shaped concave portion formed at the second connection section and interposed by the ring-shaped concave portions, the sealing member can provide excellent sealing function. Further, since the ring-shaped concave portions are formed at both the first connection section and the second connection section, the sealing member can be arranged at the ring-shaped portion of the first connection section at the time when the turbine housing is assembled to the bearing housing and the sealing member can be arranged at the ring-shaped portion of the second connection section at the time when the bearing housing is assembled to the turbine housing. Accordingly, dropping of the sealing member can be prevented and flexibility and operability of assembling operation can be improved.
(8) In some embodiments, in the configuration described above as any one of (1) to (7), the bearing housing further includes a coolant flow path through which coolant flows, the coolant flow path being arranged on a further inner side than the ring-shaped concave portion in the radial direction.
According to the configuration described above as (8), since the coolant flow path through which coolant flows is formed in the bearing housing on the further inner side than the ring-shaped concave portion in the radial direction of the shaft, temperature increase at the first connection section and the second connection section can be suppressed and thermal expansion and thermal deformation at the first connection section, the second connection section, and the sealing member arranged therebetween can be lessened. Accordingly, the sealing member can provide excellent sealing function.
(9) In some embodiments, in the configuration described above as any one of (1) to (8), the sealing member is formed into a ring shape, and in section along the axial direction of the shaft, includes a first section to be in touch with the first connection section, a second section to be in touch with the second connection section, and a curved section having a predetermined curvature to join the first section and the second section.
According to the configuration described above as (9), since the sealing member is formed into a ring-shape, sealing can be ensured between the first connection section and the second connection section all over the circumference. Further, since the sealing member includes the first section, the second section, and the curved section having the curvature to join the first section and the second section, the sealing member is easily compressed in the axial direction of the shaft and a sealing function can be provided with resilience (elastic force) generated by the compression.
(10) In some embodiments, in the configuration described above as (9), the sealing member has a predetermined springback characteristic under conditions that a sectional width L satisfies L=(DO−DI)/2, a ratio between height and plate thickness H/T satisfies “8.0≤H/T≤25.0”, a ratio between the height and curvature H/R satisfies “2.0≤H/R≤6.0”, and a ratio between height and sectional width H/L satisfies “0.5≤H/L≤3.5”, while the turbine wheel has a wheel diameter of 20 or more and 70 mm or less, coefficients of thermal expansion of the bearing housing and the turbine housing are the same, and regarding the sealing member, DO denotes an outer diameter, DI denotes an inner diameter, H denotes the height, T denotes the plate thickness, and R denotes the curvature of the curved section.
According to the configuration described above as (10), the turbine wheel has a wheel diameter of 20 mm or more and 70 mm or less. Such turbine wheel is preferable for the turbocharger for automobile use. Further, the coefficients of thermal expansion of the bearing housing and the turbine housing are the same. According to findings of the inventors, excellent sealing function can be provided by the sealing member satisfying the predetermined springback characteristic. Owing to that the sealing member satisfies the abovementioned conditions, the predetermined springback characteristic can be satisfied in the turbocharger for automobile use and excellent sealing function can be provided.
At least one embodiment of the present invention provides a turbocharger capable of suppressing outward leakage of exhaust gas with a sealing member capable of providing excellent sealing function even when thermal expansion and thermal deformation occur at the turbine housing and the bearing housing.
Embodiments of the present invention will now be described in detail with reference to the accompanying drawings. It is intended, however, that unless particularly identified, dimensions, materials, shapes, relative positions and the like of components described in the embodiments shall be interpreted as illustrative only and not intended to limit the scope of the present invention.
For example, an expression of relative or absolute arrangement such as “in a direction”, “in a direction”, “parallel”, “orthogonal”, “centered”, “concentric” and “coaxial” shall not be construed as indicating only the arrangement in a strict literal sense, but also includes a state where the arrangement is relatively displaced by a tolerance, or by an angle or a distance whereby it is possible to achieve the same function.
For example, an expression of an equal state such as “same”, “equal” and “uniform” shall not be construed as indicating only the state in which the feature is strictly equal, but also includes a state in which there is a tolerance or a difference that can still achieve the same function.
Further, for example, an expression of a shape such as a rectangular shape or a cylindrical shape shall not be construed as only the geometrically strict shape, but also includes a shape with unevenness or chamfered corners within the range in which the same effect can be achieved.
On the other hand, an expression such as “comprise”, “include”, “have”, “contain” and “constitute” are not intended to be exclusive of other components.
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As described above, the turbocharger 1 according to some embodiments includes the shaft 7, the bearing housing 2, the turbine housing 4, the uniting member 6, and the sealing member 8, as illustrated in
According to the above configuration, as illustrated in
Thus, since the uniting member 6 is fitted to the first connection section 21 and the second connection section 41 from the outside to interpose the first connection section 21 and the second connection section 41, the turbine housing 4 and the bearing housing 2 can be extended in the axial direction of the shaft 7 due to thermal expansion and thermal deformation under high temperature. Since the turbine housing 4 is more influenced by heat of exhaust gas than the bearing housing 2, the turbine housing 4 is extended in the axial direction of the shaft 7 more than the bearing housing 2. Accordingly, the second connection section 41 becomes close to the first connection section 21 so that clearance between the first face 22 and the second face 42 becomes small or zero. Owing to that the first connection section 21 and the second connection section 41 become close to each other under the thermal influence of exhaust gas, the sealing member 8 arranged at the ring-shaped concave portion 23, 43 on the radially inner side of the first face 22 and/or the second face 42 is urged to be compressed in the axial direction of the shaft 7 by the ring-shaped concave portion 23, 43, the first face 22, and/or the second face 42. Accordingly, since the sealing member 8 is reliably interposed by the ring-shaped concave portion 23, 43, the first face 22, and/or the second face 42, the sealing member 8 can suppress outward leakage of exhaust gas and provide excellent sealing function.
In some embodiments, as illustrated in
According to the above configuration, as illustrated in
In some embodiments, as illustrated in
According to the above configuration, as illustrated in
In some embodiments, as illustrated in
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According to the above configuration, as illustrated in
Further, temperature increase due to exhaust gas is also small at the sealing member 8 performing sealing between the first connection section 21 and the second connection section 41. Therefore, in a case that the sealing member 8 is formed of a metal material, it is not necessary to adopt expensive heat-resistant alloy. Accordingly, it is possible to prevent cost increase of the sealing member 8 and the turbocharger 1 including the sealing member 8.
In some embodiments, as illustrated in
According to the above configuration, as illustrated in
In some embodiments, as illustrated in
According to the above configuration, as illustrated in
In some embodiments, as illustrated in
According to the above configuration, since the sealing member 8 is arranged between the ring-shaped concave portion 23 and the ring-shaped concave portion 43 and interposed by the ring-shaped concave portions 23, 43, the sealing member 8 can provide excellent sealing function.
Further, since both the ring-shaped concave portion 23 and the ring-shaped concave portion 43 are formed, the sealing member 8 can be arranged at the ring-shaped concave portion 23 of the first connection section 21 at the time when the turbine housing 4 is assembled to the bearing housing 2 and the sealing member 8 can be arranged at the ring-shaped concave portion 43 of the second connection section 41 at the time when the bearing housing 2 is assembled to the turbine housing 4. Accordingly, dropping of the sealing member 8 can be prevented and flexibility and operability of assembling operation can be improved.
Here, in a case that the turbine housing 4 is formed of, for example, heat-resistant alloy and the bearing housing 2 is formed of a material such as case iron being less expensive and superior in cutting workability than heat-resistance alloy in consideration of the thermal influence difference between the bearing housing 2 and the turbine housing 4, the ring-shaped concave portion 23 is easier to be formed than the ring-shaped concave portion 43.
In some embodiments, as illustrated in
In some embodiments, as illustrated in
According to the above configuration, as illustrated in
Here, compared to the sealing member 8A, the sealing member 8B is easier to be compressed in the axial direction of the shaft 7 to be capable of providing sealing function with resilience (elastic force) generated by the compression.
(Springback Characteristic)
According to findings of the inventors through their studies, excellent sealing function can be provided by the sealing member 8 satisfying a predetermined springback characteristic. The springback characteristic required for the sealing member 8 is calculated through unsteady thermal deformation analysis for the turbocharger 1 with the turbine wheel 5 having a wheel diameter of 20 mm or more and 70 mm or less. In the unsteady thermal deformation analysis, coefficients of thermal expansion of materials for the bearing housing 2 and the turbine housing 4 are assumed to be the same. Here, “the same” does not mean only a case that the coefficients of thermal expansion of the materials for the bearing housing 2 and the turbine housing 4 are completely matched but includes a case that there is a difference between the coefficients of thermal expansion as long as height variance between the first face 22 and the second face 42 due to thermal expansion and thermal deformation of the bearing housing 2 and the turbine housing 4 stays within a range equal to or smaller than a predetermined amount (e.g., 4% or lower of initial height). In the current unsteady thermal deformation analysis, the coefficients of thermal expansion of the bearing housing 2 and the turbine housing 4 are the same as being 8×10−6˜22×10−6 mm/mm/° C.
As illustrated in
As illustrated in
According to the above configuration, the turbine wheel 5 has a wheel diameter of 20 mm or more and 70 mm or less. Such turbine wheel 5 is preferable for the turbocharger 1 for automobile use. Further, the coefficients of thermal expansion of the bearing housing 2 and the turbine housing 4 are the same. According to findings of the inventors, excellent sealing function can be provided by the sealing member 8A satisfying the predetermined springback characteristic. Owing to that the sealing member 8A satisfies the abovementioned conditions, the predetermined springback characteristic can be satisfied in the turbocharger 1 for automobile use and excellent sealing function can be provided.
Not limited to the embodiments described above, the present invention includes various amendments and modifications of the embodiments and appropriate combinations thereof.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2017/039072 | 10/30/2017 | WO | 00 |
| Publishing Document | Publishing Date | Country | Kind |
|---|---|---|---|
| WO2019/087231 | 5/9/2019 | WO | A |
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| Number | Date | Country | |
|---|---|---|---|
| 20200056505 A1 | Feb 2020 | US |
