Turbocharger

Abstract

The turbine housing (5) has a vortex portion (12), an outlet pipe (13) and an inlet pipe (14). A bypass passage (21) is formed on the inner peripheral side of the vortex shape from the inlet pipe (14) toward the vortex portion (12) so as to connect the inlet passage (18) with the outlet passage (19). When the turbine housing (5) is viewed in the axial direction, the opening center of the outlet opening (21b) of the bypass passage (21) is located in the quadrant (Q4) where the mounting flange (15) is located, among four quadrants (Q1, Q2, Q3, Q4) divided by a first virtual plane (P1) passing through the rotation center (O) and parallel to a surface (P3) of the mounting flange (15), and a second virtual plane (P2) passing through the rotation center (O) and orthogonal to the first virtual plane (P1).

Description

Technical Field

[0001] The present invention relates to a turbocharger for supercharging an internal combustion engine, and in particular to an improvement of a turbocharger having a bypass passage and a wastegate valve. Background Art

[0002] A turbocharger used for supercharging an internal combustion engine generally has a bypass passage for bypassing a portion of the exhaust gas flow without passing through a turbine in order to control the supercharging pressure, and a waste gas bypass valve corresponding thereto. The waste gas bypass valve generally has the following structure, that is, an actuator arranged outside the housing of the turbocharger drives a valve body to open and close the outlet opening of the bypass passage.

[0003] Patent document 1 discloses a structure in which a bypass passage is provided on the outer peripheral side of the vortex shape from the inlet pipe of the turbine housing toward the vortex portion. Furthermore, the outlet opening of the bypass passage opened and closed by the valve body of the wastegate valve is located at a position separated from the front end of the inlet pipe that serves as the exhaust inlet when the turbine housing is viewed in the axial direction of the turbocharger. Specifically, when a plane parallel to the surface of the mounting flange at the end of the inlet pipe and passing through the rotation center of the turbocharger is assumed, the mounting flange and the outlet opening are located on opposite sides of the assumed plane.

[0004] This arrangement is mainly caused by the restriction that the actuator of the wastegate valve is located outside the turbocharger when the mounting flange of the inlet pipe end is mounted to the internal combustion engine.

[0005] However, with this conventional structure, the bypass passage cannot be shortened to its shortest possible, and the temperature of the exhaust gas flowing through the bypass passage is greatly reduced due to heat exchange at the inner wall surface of the bypass passage. Therefore, there is room for improvement in the catalyst warm-up performance immediately after a cold start, for example.

[0006] Patent Document 1: Japanese Patent Application Publication No. 2014-58894 Summary of the invention

[0007] In the turbocharger according to the present invention,

[0008] The bypass passage is formed so as to connect the inlet passage inside the inlet pipe with the outlet passage inside the outlet pipe on the inner peripheral side of the vortex shape from the inlet pipe toward the vortex portion, and the wastegate valve is arranged in the outlet pipe to open and close the outlet opening of the bypass passage.

[0009] Observing the turbine housing in the axial direction of the turbocharger, the opening center of the above-mentioned outlet opening is located in the quadrant where the above-mentioned mounting flange is located, among the four quadrants divided by a first virtual plane passing through the rotation center of the turbocharger and parallel to the surface of the mounting flange, and a second virtual plane passing through the above-mentioned rotation center and orthogonal to the above-mentioned first virtual plane.

[0010] According to this structure, the passage length of the bypass passage connecting the inlet passage in the inlet pipe and the outlet passage in the outlet pipe is shortened, and the temperature drop of the exhaust gas flow flowing through the bypass passage is suppressed. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 This is a side view of the turbocharger according to the present invention as viewed from the internal combustion engine side.

[0012] Figure 2 This is a front view of a turbocharger mounted on an internal combustion engine as seen from the end on the turbine side.

[0013] Figure 3 It is along Figure 1 Cross-section diagram along line AA.

[0014] Figure 4 It is along Figure 1 Cross-sectional view of line BB.

[0015] Figure 5 It is along Figure 3 Cross-sectional view of the CC line.

[0016] Figure 6 This is an explanatory diagram for explaining the position of the outlet opening of the bypass passage. DETAILED DESCRIPTION

[0017] Hereinafter, one embodiment of the present invention will be described in detail based on the drawings.

[0018] Figure 1 and Figure 2 1 is a side view and a front view showing the overall structure of the turbocharger 1 involved in the present invention. Figure 2 As schematically shown, the turbocharger 1 is directly mounted on the side of the internal combustion engine, more specifically, on the side of the cylinder head 2 . Figure 2 The turbocharger 1 is shown in the posture of being mounted on the cylinder head 2 in this manner. Figure 1 This is a diagram showing the entire turbocharger 1 as viewed from the cylinder head 2 side.

[0019] The turbocharger 1 performs supercharging using exhaust energy by rotating a rotating member (not shown) that connects the turbine wheel and the compressor wheel coaxially as is known, and is roughly divided into three parts along the axial direction of the rotating member: a turbine housing 5 at one end, a compressor housing 6 at the other end, and a center housing 7 located between the two, which are assembled into one body. The compressor housing 6 and the center housing 7 are not the main parts of the present invention, so detailed descriptions are omitted.

[0020] The turbine housing 5 is formed of a casting made of a heat-resistant metal material such as stainless steel. Figure 3 to Figure 5 2 is a cross-sectional view of the turbine housing 5. Referring to these cross-sectional views, the following components are cast as one body to form the turbine housing 5: a circular vortex portion 12, which forms a scroll piece 11 surrounding the turbine (see FIG. Figure 5 ); an outlet pipe 13 extending from the center of the vortex portion 12 along the rotation axis of the turbocharger 1; an inlet pipe 14 extending from the vortex portion 12 in the axial direction of the rotation axis and along the tangential direction of the vortex portion 12; and a mounting flange 15 at the end of the inlet pipe 14. The mounting flange 15 is formed so as to Figure 1 The exhaust inlet 16 is formed in a substantially rectangular shape and is surrounded by four through holes 17 for passing bolts for mounting to the cylinder head 2. Figure 2 As shown, the mounting flange 15 is mounted on the side of the cylinder head 2, and in this mounted state, the exhaust outlet opening (not shown) on the cylinder head 2 side is aligned with the exhaust inlet 16. In addition, in the mounted state, the mounting flange 15 is located below the rotation axis of the turbine. The mounting flange 15 has a mounting surface 15a along a plane.

[0021] The inlet pipe 14 forms an inner inlet passage 18 having an approximately rectangular cross-sectional shape. Figure 3 As shown, the inlet passage 18 extends from the mounting flange 15 to the scroll portion 12 while gently curving, and is formed into a scroll shape as a whole. In addition, the passage cross-sectional area of ​​the inlet passage 18 gradually decreases, and merges with the scroll 11 of the scroll portion 12.

[0022] The outlet pipe 13 is formed into a substantially cylindrical shape with a bell-mouth shape whose diameter increases toward the axial outer side, forming an internal outlet passage 19. The outlet passage 19 is configured so that the exhaust gas after operation flows out from the center of the turbine in the axial direction, and the axial end is opened as a circular exhaust outlet 20.

[0023] like Figure 3 to Figure 5 As shown in the cross-sectional view of FIG. 1 , a bypass passage 21 is formed between the inlet passage 18 and the outlet passage 19 in the turbine housing 5 so that the two can communicate with each other. Figure 3As shown in FIG. 1 , when the turbine housing 5 is viewed in the axial direction, the bypass passage 21 is provided on the inner circumference of the vortex shape of the flow path from the inlet pipe 14 toward the scroll portion 12. Specifically, the inlet opening 21a of the bypass passage 21 on the inlet passage 18 side is formed so that the turbocharger 1 is formed Figure 2 , Figure 3 When the mounting posture is such as the above, the inlet opening 21a is opened in the wall surface that becomes the top surface of the inlet passage 18. In addition, the inlet opening 21a is provided at a position immediately behind the mounting flange 15 so as to be located on the upstream side as much as possible in the inlet passage 18.

[0024] On the other hand, the outlet opening 21b of the bypass passage 21 on the outlet passage 19 side is formed so that the turbocharger 1 is formed Figure 2 , Figure 3 When the turbocharger 1 is in an installation posture such as the bypass passage 21, the bypass passage 21 is opened on the wall surface on the lower surface side of the outlet passage 19. That is, the inlet opening 21a and the outlet opening 21b of the bypass passage 21 are respectively arranged at positions adjacent to each other when the turbocharger 1 is viewed in a three-dimensional manner. Therefore, the passage length of the bypass passage 21 is short. The bypass passage 21 is basically arranged in a manner that is shortest in three-dimensional view. In addition, the bypass passage 21 is formed by using a core when casting the turbine housing 5, similarly to the inlet passage 18 and the like.

[0025] Thus, the bypass passage 21 has a shorter passage length, thereby reducing the heat exchange area of ​​the inner wall surface of the bypass passage 21 and suppressing a decrease in the temperature of the exhaust gas flow flowing through the bypass passage 21. Therefore, for example, the catalyst warm-up performance immediately after a cold start is improved.

[0026] The outlet opening 21b is opened and closed by a disc-shaped valve body 32 of a wastegate valve 31 described later, and opens in a circular shape corresponding to the valve body 32. In particular, after casting, the annular seating surface needs to be machined through the exhaust outlet 20 of the outlet pipe 13, and opens obliquely toward the exhaust outlet 20. In addition, in order to ensure a margin around the outlet opening 21b, the center of the circular exhaust outlet 20 is slightly offset to the outlet opening 21b side relative to the rotation axis of the turbine (see Figure 2 ).

[0027] Here, refer to Figure 6 The illustration of Figure 6The turbine housing 5 is schematically shown by viewing it in the axial direction of the turbocharger 1, so a first virtual plane P1 is drawn which passes through the rotation center O of the turbocharger 1 and is parallel to the surface P3 (mounting surface 15a) of the mounting flange 15, and a second virtual plane P2 is drawn which passes through the rotation center O and is orthogonal to the first virtual plane P1. The opening center of the outlet opening 21b is located in the quadrant Q4 (fourth quadrant) at the lower right in the figure where the mounting flange 15 is located, among the four quadrants Q1, Q2, Q3, and Q4 divided by the two virtual planes P1 and P2.

[0028] As described above, in the current structure, the outlet opening opened and closed by the valve body has its opening center located in the third quadrant Q3 at the lower left in the figure and the second quadrant Q2 at the upper left in the figure. Therefore, the passage length of the bypass passage increases.

[0029] like Figure 4 As shown in FIG. 1 , the wastegate valve 31 for opening and closing the bypass passage 21 includes: an approximately L-shaped shaft 33 having a swing lever 33a at the front end; and a disc-shaped valve body 32 mounted on the front end of the swing lever 33a. The shaft 33 passes through a cylindrical boss portion 34 integrally cast with the outlet pipe 13 and extends to the outside of the outlet pipe 13, and is rotatably supported on the boss portion 34 via a cylindrical metal sleeve 35 as a bearing member. An arm 36 is fixed to the outer end of the shaft 33.

[0030] The boss portion 34 is provided at the connection portion between the inlet pipe 14 and the outlet pipe 13 from the mounting flange 15 toward the vortex portion 12. That is, the boss portion 34 is located at a valley-shaped position between the two. By forming the boss portion 34 at such a position, the inlet pipe 14 and the outlet pipe 13 are connected to each other by the thick wall portion around the boss portion 34, and the overall support rigidity of the turbocharger 1 is improved when the mounting flange 15 is mounted on the internal combustion engine. Therefore, the vibration of the turbocharger 1 caused by the vibration of the internal combustion engine, the vibration during driving, etc. is suppressed.

[0031] like Figure 1 As shown, the turbocharger 1 has a direct-acting electric actuator 41 as an actuator for the wastegate valve 31. The electric actuator 41 has an electric motor and a ball screw mechanism in a cylindrical housing, and has a rod 42 that moves forward and backward in the axial direction. The front end of the rod 42 is connected and engaged with the end of the arm 36 via a relay rod 43. The following relationship is formed, that is, if the rod 42 moves in the protruding direction, the valve body 32 opens, and if the rod 42 moves backward, the valve body 32 closes, and the intermediate opening degree can also be controlled.

[0032] Here, the electric actuator 41 is supported by a rectangular wall-shaped actuator mounting flange 45 formed integrally with the compressor housing 6, and the rod 42 and the relay rod 43 extend through the vicinity of the outer side surface of the center housing 7 and the turbine housing 5. Figure 2 As shown in FIG. 1 , the electric actuator 41 is configured such that, when the turbocharger 1 is mounted on the internal combustion engine, the electric actuator 41 is located in a narrow space between the compressor housing 6 of the turbocharger 1 and the side surface of the cylinder head 2. In other words, the electric actuator 41 is configured to be smaller than the turbocharger 1. Figure 6 The first virtual plane P1 shown is closer to the mounting flange 15 side ( Figure 6 The first quadrant Q1 or the fourth quadrant Q4).

[0033] Likewise, the boss portion 34 of the wastegate valve 31 is also Figure 2 As shown in FIG. 1 , the internal combustion engine is disposed on the side facing the internal combustion engine. Figure 6 , the boss portion 34 is located in the fourth quadrant Q4 at the lower right.

[0034] According to the arrangement of the electric actuator 41, in addition to being suitable for the structure of the bypass passage 21, the actual occupied space of the entire turbocharger 1 including the electric actuator 41 installed in the internal combustion engine is reduced. That is, compared with the structure in which the electric actuator 41 is located on the opposite side of the internal combustion engine across the first virtual plane P1, the turbocharger 1 is substantially miniaturized.

Claims

1. A turbocharger comprising a turbine housing and a compressor housing, wherein a bypass passage and a wastegate valve are provided in the turbine housing, and an actuator for driving the wastegate valve to open and close is provided, wherein: The turbine housing is formed by integrally casting the following components: an annular vortex portion, which forms a vortex member surrounding the turbine; an outlet pipe, which extends from the center of the vortex portion along the rotation axis of the turbocharger; and an inlet pipe, which changes from the vortex portion in the axial direction of the rotation axis and extends in the tangential direction of the vortex portion, and has a mounting flange at the end. The bypass passage is formed so as to connect the inlet passage inside the inlet pipe with the outlet passage inside the outlet pipe on the inner peripheral side of the vortex shape from the inlet pipe toward the vortex portion, and the wastegate valve is arranged in the outlet pipe to open and close the outlet opening of the bypass passage. When the turbine housing is observed in the axial direction of the turbocharger, the opening center of the outlet opening is located in the quadrant where the mounting flange is located, among four quadrants divided by a first virtual plane passing through the rotation center of the turbocharger and parallel to the surface of the mounting flange, and a second virtual plane passing through the rotation center and orthogonal to the first virtual plane. The wastegate valve comprises: a cylindrical boss portion formed integrally with the outlet pipe; an approximately L-shaped shaft rotatably supported on the inner circumference of the boss portion via a bearing member and having a swing lever at the front end; and a disc-shaped valve body mounted on the front end of the swing lever. The boss portion is located in the quadrant where the mounting flange is located among the four quadrants. When the mounting flange is mounted on the side of the cylinder head of the exhaust port opening of the internal combustion engine, the actuator is located between the turbocharger and the cylinder head, and the main body of the actuator is located in the first quadrant adjacent to the fourth quadrant across the second virtual plane, and the relay rod connected and engaged with the shaft crosses between the turbine housing and the cylinder head.

2. The turbocharger according to claim 1, wherein: The boss portion is provided at a connection portion between an inlet pipe extending from the mounting flange toward the scroll portion and the outlet pipe.

3. The turbocharger according to claim 1 or 2, wherein: The bypass passage is formed from a position of the inlet passage immediately behind the mounting flange toward the outlet passage.

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