Twin-spiral turbine and turbocharger

Abstract

A twin-screw turbine is provided with a valve device. The valve device is provided with: a valve rod which extends so as to traverse the communication flow path, and which is provided such that the axis line passes through the lead-out opening; a first opening / closing plate which is attached to the valve stem so as to extend along the axis line, and which opens / closes the communication flow path in accordance with the rotation of the valve stem; and a second opening / closing plate that extends in a direction intersecting the axis line, is attached to the valve stem further toward the outlet than the first opening / closing plate, and opens / closes the bypass flow path in accordance with the rotation of the valve stem.

Description

TECHNICAL FIELD

[0001] The present application relates to a double helical turbine and a turbocharger each of which is formed with two helical flow passages. BACKGROUND

[0002] Conventionally, a double helical turbine is known which is formed with a communication flow passage that communicates two helical flow passages and a bypass flow passage that connects the communication flow passage and an exhaust flow passage. For example, the double helical turbine disclosed in Patent Literature 1 is provided with a flap valve that opens and closes the communication flow passage and the bypass flow passage.

[0003] PRIOR ART DOCUMENTS

[0004] PATENT LITERATURE

[0005] Patent Literature 1: German Patent No. DE 102013002894 SUMMARY

[0006] PROBLEMS TO BE SOLVED BY THE INVENTION

[0007] In the double helical turbine of Patent Literature 1, since a single valve body is used to open and close the communication flow passage and the bypass flow passage, it is likely that the opening and closing of these two flow passages cannot be freely performed. As a specific example, when the valve body opens the communication flow passage, it is likely that the bypass flow passage is also inevitably opened. Therefore, in a case where the valve is opened in order to cause the exhaust gas to flow through the communication flow passage, the exhaust gas also flows through the bypass flow passage, resulting in a decrease in turbine efficiency. As another example, even if the valve body is disposed at a position at which the communication flow passage and the bypass flow passage are closed, it is likely that the communication flow passage is slightly opened.

[0008] An object of the present application is to provide a double helical turbine and a turbocharger that can freely open and close a communication flow passage and a bypass flow passage.

[0009] MEANS FOR SOLVING THE PROBLEMS

[0010] The double helical turbine according to at least one embodiment of the present application is provided with a turbine housing that is formed with two helical flow passages of a double helical type configured to guide exhaust gas to a turbine impeller and a discharge flow passage for discharging the exhaust gas that has passed through the turbine impeller, wherein

[0011] The turbine housing includes:

[0012] a communication flow passage wall that defines a communication flow passage that communicates the two helical flow passages with each other; and

[0013] a bypass flow passage wall that defines a bypass flow passage for guiding the exhaust gas that has flowed through the communication flow passage to the discharge flow passage while bypassing the turbine impeller,

[0014] A guide outlet that guides the exhaust gas flowing through the communication flow path to the bypass flow path is formed in the communication flow path wall,

[0015] The dual-screw turbine further includes a valve device,

[0016] The valve device includes:

[0017] A valve rod that extends across the communication flow path and is disposed with an axis passing through the guide outlet;

[0018] A first opening and closing plate that is mounted on the valve rod so as to extend along the axis and that opens and closes the communication flow path in accordance with rotation of the valve rod; and

[0019] A second opening and closing plate that extends in a direction intersecting the axis and that is mounted on the valve rod on a side closer to the guide outlet than the first opening and closing plate and that opens and closes the bypass flow path in accordance with rotation of the valve rod.

[0020] A turbocharger according to at least one embodiment of the present application includes:

[0021] A rotation shaft;

[0022] The dual-screw turbine includes the turbine impeller coupled to one end portion of the rotation shaft; and

[0023] A compressor including a compressor impeller coupled to the other end portion of the rotation shaft.

[0024] Effects of the Invention

[0025] According to the present application, a dual-screw turbine and a turbocharger that freely open and close a communication flow path and a bypass flow path can be provided. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 is a schematic view of a turbocharger according to one embodiment.

[0027] Figure 2 is a schematic view of a turbine according to one embodiment.

[0028] Figure 3 is a schematic view of a turbine housing according to one embodiment.

[0029] Figure 4 is a schematic view of a valve device according to one embodiment.

[0030] Figure 5 is a schematic view of an opposing plate according to one embodiment.

[0031] Figure 6is a schematic view of an opening process of a communication flow path according to an embodiment.

[0032] Figure 7A is a schematic view of an opening process of a communication flow path according to an embodiment.

[0033] Figure 7B is a schematic view of an opening process of a communication flow path according to an embodiment. Figure 7A is a schematic view of an opening process of a communication flow path according to an embodiment.

[0034] Figure 7C is a schematic view of an opening process of a communication flow path according to an embodiment. Figure 7B is a schematic view of an opening process of a communication flow path according to an embodiment.

[0035] Figure 7D is a schematic view of an opening process of a communication flow path according to an embodiment. Figure 7C is a schematic view of an opening process of a communication flow path according to an embodiment.

[0036] Figure 8A is a schematic view of an opening process of a communication flow path according to an embodiment.

[0037] Figure 8B is a schematic view of an opening process of a communication flow path according to an embodiment. Figure 8A is a schematic view of an opening process of a communication flow path according to an embodiment.

[0038] Figure 8C is a schematic view of an opening process of a communication flow path according to an embodiment. Figure 8B is a schematic view of an opening process of a communication flow path according to an embodiment.

[0039] Figure 8D is a schematic view of an opening process of a communication flow path according to an embodiment. Figure 8C is a schematic view of an opening process of a communication flow path according to an embodiment. DETAILED DESCRIPTION

[0040] Hereinafter, several embodiments of the present application will be described with reference to the accompanying drawings. However, the size, material, shape, relative arrangement, and the like of the constituent components described as the embodiments or shown in the drawings are merely illustrative and are not intended to limit the scope of the present application thereto.

[0041] For example, expressions such as "in a certain direction", "along a certain direction", "parallel", "orthogonal", "center", "concentric", or "coaxial" indicating relative or absolute arrangement not only strictly indicate such arrangement but also indicate a state of relative displacement in an angle or distance with a tolerance or to the extent that the same function can be obtained.

[0042] For example, expressions such as "same", "equal", and "homogeneous" indicating a state of equality of things do not only strictly indicate a state of equality but also indicate a state of difference with a tolerance or to the extent that the same function can be obtained.

[0043] For example, the expression of the shape such as a quadrangular shape and a cylindrical shape indicates not only the shape such as a quadrangular shape and a cylindrical shape in a strict sense of geometry, but also a shape including a concave-convex portion and a chamfered portion and the like within a range in which the same effect can be obtained.

[0044] On the other hand, the expression of "having", "including", or "comprising" one component is not an exclusive expression of the presence of other components.

[0045] In addition, the same symbol is sometimes assigned to the same structure, and the description is omitted.

[0046] <Overall structure of turbocharger 1>

[0047] Figure 1 is a schematic view of a turbocharger 1 according to an embodiment of the present application. The turbocharger 1 of this example is mounted on, for example, an engine 12 applicable to an automobile. The turbocharger 1 has a rotary shaft 3, a twin scroll turbine 5 including a turbine wheel 9 coupled to one end portion 3A of the rotary shaft 3, and a compressor 8 including a compressor wheel 6 coupled to the other end portion 3B of the rotary shaft 3.

[0048] In the following description, the twin scroll turbine 5 is sometimes simply referred to as "turbine 5". Also, the direction in which the central axis C of the rotary shaft 3 extends is sometimes referred to as "turbine axial direction", and the radial direction and the circumferential direction with the central axis C as a reference are sometimes referred to as "turbine radial direction" and "turbine circumferential direction", respectively. The turbine radial direction outside is the direction side away from the central axis C, and the turbine radial direction inside is the direction side close to the central axis C.

[0049] The compressor 8 also includes a compressor casing 7 that houses the compressor wheel 6. Air that has entered from a suction port 101 formed in the compressor casing 7 is compressed by the compressor wheel 6 and is sent out to the engine 12. The turbine 5 also includes a twin scroll type turbine casing 10 that houses the turbine wheel 9. The turbine wheel 9 rotates together with the rotary shaft 3 using exhaust gas discharged from the engine 12 as a working medium. The exhaust gas that has passed through the turbine wheel 9 is discharged from a discharge port 102 formed in the turbine casing 10.

[0050] <Turbine casing 10>

[0051] Figure 2 is a schematic view of the turbine 5 according to an embodiment of the present application. Two spiral flow passages 11 for guiding exhaust gas to the turbine wheel 9 are formed in the turbine casing 10. The two spiral flow passages 11 are arranged in the same range as each other in the turbine axial direction, and are configured to supply exhaust gas to the turbine wheel 9 in different ranges from each other in the turbine circumferential direction. Also, a discharge flow passage 19 (see FIG. 2) for discharging exhaust gas that has passed through the turbine wheel 9 to the outside of the system is formed in the turbine casing 10. Figure 1The exhaust flow path 19 of this example extends in the turbine axial direction, and exhaust gas that has passed through the turbine wheel 9 is discharged from the exhaust port 102 via the exhaust flow path 19.

[0052] Figure 3 is a schematic view of the turbine housing 10 according to an embodiment of the present application, schematically illustrating the turbine wheel 9. The turbine housing 10 is provided with a communication flow path wall 28 that defines a communication flow path 18 that communicates the two spiral flow paths 11 with each other, and a bypass flow path wall 25 that defines a bypass flow path 15 for guiding exhaust gas that has flowed through the communication flow path 18 to the exhaust flow path 19 while bypassing the turbine wheel 9.

[0053] The both end portions of the communication flow path wall 28 are connected to the communication ports 11A (refer to FIG. 2) formed in the two spiral flow paths 11, respectively. Also, a guide port 41 for guiding exhaust gas that has flowed through the communication flow path 18 to the bypass flow path 15 is formed in the communication flow path wall 28. The guide port 41 is located between the two communication ports 11A, and is located on the exhaust flow path 19 side more than the turbine wheel 9. The guide port 41 of this example penetrates the communication flow path wall 28 in the turbine radial direction. Figure 2

[0054] <Valve device 30>

[0055] As shown in FIG. 4, the turbine 5 is further provided with a valve device 30 configured to open and close the communication flow path 18 and the bypass flow path 15, respectively. The valve device 30 includes a valve shaft 35 that extends across the communication flow path 18, a first opening and closing plate 31 that is installed on the valve shaft 35, and a second opening and closing plate 32 that is installed on the valve shaft 35 on the guide port 41 side more than the first opening and closing plate 31. The first opening and closing plate 31 and the second opening and closing plate 32 are each configured to rotate integrally with the valve shaft 35. Figure 3 The valve shaft 35 of this example has a first end portion 351 that is located on the side opposite the guide port 41 with respect to the communication flow path 18, a second end portion 352 that is located on the guide port 41 side with respect to the communication flow path 18, and an extension portion 353 that extends between the first end portion 351 and the second end portion 352. The first end portion 351 and the second end portion 352 are each disposed on the outside of the communication flow path wall 28. The axis S of the valve shaft 35 thus configured is substantially orthogonal to the communication flow path center line 18A that is the flow path center line of the communication flow path 18, and passes through the communication flow path 18 and the guide port 41.

[0056] The first opening and closing plate 31 that is installed on the extension portion 353 of the valve shaft 35 extends along the axis S. The first opening and closing plate 31 is configured to open and close the communication flow path 18 in conjunction with the rotation of the valve shaft 35. More specifically, the first opening and closing plate 31 is configured to be in a first closed position (refer to FIG. 5) and a first open position (refer to FIG. 6) in conjunction with the rotation of the valve shaft 35.

[0057] Figure 7A Figure 7D ​​​), with the first closed position extending perpendicularly to the communication channel centerline 18A to close the communication channel 18, and the first open position extending parallel to the communication channel centerline 18A to open the communication channel 18. The first opening and closing plate 31 completely closes the communication channel 18 in the first closed position and completely opens the communication channel 18 in the first open position.

[0058] like Figure 3 As shown in FIG. 1 , the second opening and closing plate 32 attached to the second end portion 352 of the valve stem 35 extends so as to intersect the axis S and is formed separately from the first opening and closing plate 31. The second opening and closing plate 32 is configured to open and close the bypass flow path 15 as the valve stem 35 rotates. More specifically, the second opening and closing plate 32 is configured to close the bypass flow path 15 in the closed state (see FIG. 1 ). Figure 8A 、 Figure 8B ) and the open state of the open bypass flow path 15 (reference Figure 8C 、 Figure 8D ) between. The details of the structure of the second opening and closing plate 32 opening and closing the bypass flow path 15 will be described later. In addition, the second opening and closing plate 32 of this example extends in a manner substantially perpendicular to the axis S.

[0059] Because the first and second opening and closing plates 31, 32, which respectively open and close the communication passage 18 and the bypass passage 15, are separate components, the turbine 5 is capable of freely opening and closing the communication passage 18 and the bypass passage 15. In this embodiment, the timing of opening and closing the bypass passage 15 when opening the communication passage 18 can be freely adjusted during the design phase of the turbine 5. Furthermore, the timing of opening the bypass passage 15 and the communication passage 18 can be staggered, thereby preventing unintended leakage of exhaust gas from the bypass passage 15 or the communication passage 18.

[0060] In the following description, the axial direction of the axis S of the valve stem 35 may be simply referred to as the “axial direction.” Furthermore, the radial direction and the circumferential direction based on the axis S may be simply referred to as the “radial direction” and the “circumferential direction,” respectively.

[0061] <Opening and Closing Structure of Bypass Flow Path 15>

[0062] Figure 4 is a schematic diagram of a valve device 30 according to an embodiment of the present invention. Figure 5 is a schematic diagram of an opposing plate 33 according to an embodiment of the present invention. Figure 6 This is a schematic diagram of the second opening and closing plate 32 according to one embodiment of the present invention.

[0063] like Figure 4 、 Figure 5As shown, the turbine 5 further includes an opposing plate 33 that opposes the second opening and closing plate 32 from the upstream side in the flow direction of the bypass flow path 15. The circular opposing plate 33 is configured as a separate body from the turbine housing 10 and is fixed to the inner surface of the turbine housing 10 by, for example, welding. As a more specific example, the outer peripheral surface 339 of the opposing plate 33 is fixed to the inner surface of the communication flow path wall 28 that defines the outlet 41.

[0064] Furthermore, the opposing plate 33 defines a passage 36 for the exhaust gas to pass through. The passage 36 is a hole that is open in the axial direction. Figure 5 In the example, a pair of through-ports 36 are formed as openings on the opposing plate 33. In more detail, the opposing plate 33 includes a pair of main body portions 39 and a pair of connecting portions 34. The pair of main body portions 39 formed symmetrically with respect to the axis S are each in a fan-shaped shape with the axis S as a reference. The connecting portion 34 extends in the circumferential direction and is connected to the radially outer end portions of the pair of main body portions 39. In this structure, the through-ports 36 are defined by the circumferential end surface 391 of the main body portion 39 and the inner circumferential surface 341 of the connecting portion 34. In this example, the pair of through-ports 36 are arranged at equal intervals in the circumferential direction. Each through-port 36 is in a fan-shaped shape centered on the axis S. The valve stem 35 is inserted into the center hole formed in the center portion of the opposing plate 33.

[0065] In another example, a single through-hole 36 (not shown) may be formed in the opposing plate 33 .

[0066] like Figure 6 As shown, the second opening and closing plate 32 has an outer peripheral surface 27 facing radially outward. The outer peripheral surface 27 in this example extends parallel to the circumferential direction, and the second opening and closing plate 32 is in the shape of a fan with the axis S as the center. The diameter of the outer peripheral surface 27 is larger than the diameter of the inner peripheral surface 341 of the opposing plate 33. In this figure, the maximum distance from the axis S of the valve stem 35 to the outer peripheral surface 27 is marked as dimension L1. The second opening and closing plate 32 defines an opening 29. The opening 29 is located in the inner area R1 of the first imaginary circle 91 with the axis S as the center and the dimension L1 as the radius. Figure 6 In the example, the opening 29 is defined by the end surface 321 of the second opening and closing plate 32 in the circumferential direction. In other words, a plurality of second opening and closing plates 32 are arranged across the opening 29 in the circumferential direction. In this example, a pair of second opening and closing plates 32 are arranged, and a pair of openings 29 are arranged at equal intervals in the circumferential direction. Figure 5 、 Figure 6 In the example, the central angle (θ1) of the fan-shaped second opening and closing plate 32 is larger than the central angle (θ2) of the fan-shaped passage opening 36 .

[0067] Further, in other examples, the opening 29 (not shown) can be formed as a through-hole in the single second shutter 32. In this case, the opening 29 is defined by the opening portion of the second shutter 32. Further, the number of openings 29 can be different from the number of through-paths 36, and the numbers can be different from each other.

[0068] The second shutter 32 of the present example is configured to open and close the bypass passage 15 by opening and closing the through-paths 36. The second shutter 32 is configured to rotate between a second closed position (refer to FIG. 2) as one end of the movable range and a second open position (refer to FIG. 3) as the other end of the movable range. In a case where the second shutter 32 is positioned at the second closed position, the through-paths 36 are closed by the second shutter 32, and the openings 29 are positioned at positions offset in the circumferential direction from the through-paths 36. In a short time after the second shutter 32 starts to rotate from the second closed position toward the second open position, the through-paths 36 maintain a state of being closed by the second shutter 32 (refer to FIG. 4). Eventually, the openings 29 and a portion of the through-paths 36 are opposed in the axial direction (refer to FIG. 5), and when the second shutter 32 reaches the second open position, the through-paths 36 are completely opened (refer to FIG. 6). Figure 8A Figure 8D Figure 8B Figure 8C Figure 8D

[0069] According to the above-described structure, the position of the opening 29 defined by the second shutter 32 changes with the rotation of the valve shaft 35, and thus the second shutter 32 can open and close the bypass passage 15. The timing at which the communication passage 18 is opened and closed can be made to coincide with or be different from the timing at which the bypass passage 15 is opened and closed, in accordance with the shape of the second shutter 32 determined at the design stage of the turbine 5. Thus, the communication passage 18 and the bypass passage 15 can be further freely opened and closed.

[0070] Further, according to the structure in which the opposed plate 33 is provided separately from the turbine housing 10, the shape of the turbine housing 10 can be prevented from being complicated. Further, since the bypass passage 15 can be opened and closed only by whether the opening 29 defined by the second shutter 32 is opposed to the through-paths 36, the structure of the valve device 30 can be simplified.

[0071] Further, according to the structure in which a plurality of through-paths 36 are provided, the positions through which the exhaust gas passes can be dispersed in the opposed plate 33, and excessive temperature rise at a specific portion of the opposed plate 33 can be suppressed. Further, this technical advantage can be obtained in an embodiment in which the plurality of through-paths 36 are disposed at unequal intervals in the circumferential direction.

[0072] ​​​​​Furthermore, due to the configuration in which the plurality of openings 29 are arranged at intervals in the circumferential direction in the same number as the plurality of through-ports 36, the amount of rotation of the second opening and closing plate 32 required to open and close the bypass flow path 15 can be reduced compared to a case in which the number of openings 29 is smaller than the number of through-ports 36. This allows the bypass flow path 15 to be opened and closed quickly.

[0073] <Opening and Closing Timings of the Communication Flow Path 18 and the Bypass Flow Path 15>

[0074] refer to Figures 7A-7D 、 Figures 8A-8D , the respective opening and closing timings of the communication flow path 18 and the bypass flow path 15 will be described. Figures 7A-7D is a schematic diagram showing an opening process of the communication flow path 18 according to one embodiment of the present invention. Figures 8A-8D This is a schematic diagram showing the opening process of the passage port 36 according to one embodiment of the present invention. Figure 7A and Figure 8A represents the state of the valve device 30 at the same time point, Figure 7B and Figure 8B Indicates the state of the valve device 30 at the same time point. Figure 7C and Figure 8C Between and Figure 7D and Figure 8D The same relationship holds true between . Figures 8A-8D In order to facilitate observation of the drawings, the radius of the second opening and closing plate 32 is shown to be larger than the radius of the opposing plate 33, but the second opening and closing plate 32 and the opposing plate 33 may have the same radius.

[0075] like Figure 7A 、 Figure 7B As shown, as the valve stem 35 rotates, the first opening and closing plate 31 rotates from the first open position and begins to open the communication flow path 18. Figure 8A 、 Figure 8B As shown, the second opening and closing plate 32 also rotates from the second open position to the second closed position. However, since the central angle of the second opening and closing plate 32 is larger than the central angle of the through-port 36, the opening 29 is still offset circumferentially from the through-port 36. In other words, the second opening and closing plate 32 remains closed.

[0076] like Figure 7B 、 Figure 7C As shown in FIG. 1 , the first opening and closing plate 31 further rotates to further open the communication flow path 18. That is, the opening of the communication flow path 18 gradually increases. Figure 8B 、 Figure 8C As shown, the opening 29 and a part of the passage 36 are opposed to each other in the axial direction, and the second opening and closing plate 32 is switched from the closed state to the open state.

[0077] likeFigure 7C Figure 7D As shown in FIG. 6, when the first shutter 31 further rotates to reach the first open position, the communication flow path 18 is completely opened. At this time, as shown in FIG. 7, as the second shutter 32 rotates toward the second open position, the opening degree of the through port 36 gradually increases. That is, the opening degree of the bypass flow path 15 gradually increases. When the second shutter 32 reaches the second open position, the opening 29 and the through port 36 are entirely opposed to each other in the axial direction, and the second shutter 32 completely opens the through port 36. That is, the bypass flow path 15 is completely opened. Figure 8C Figure 8D As shown in FIG. 6, when the first shutter 31 further rotates to reach the first open position, the communication flow path 18 is completely opened. At this time, as shown in FIG. 7, as the second shutter 32 rotates toward the second open position, the opening degree of the through port 36 gradually increases. That is, the opening degree of the bypass flow path 15 gradually increases. When the second shutter 32 reaches the second open position, the opening 29 and the through port 36 are entirely opposed to each other in the axial direction, and the second shutter 32 completely opens the through port 36. That is, the bypass flow path 15 is completely opened.

[0078] According to the above-described structure, even when the first shutter 31 slightly opens the communication flow path 18 (refer to FIG. 6), the second shutter 32 can maintain the closed state (refer to FIG. 7). Also, at the time when the first shutter 31 completely opens the communication flow path 18 (refer to FIG. 6), the second shutter 32 can completely open the bypass flow path 15 (refer to FIG. 7). Figure 7B Figure 8B Figure 7D Figure 8D

[0079] <Extension direction of valve rod 35>

[0080] Returning to Figure 3 In several embodiments of the present application, when viewed in the turbine axial direction, the axis S of the valve rod 35 passes through the inner side area R2 of the second imaginary circle 92. Here, the second imaginary circle 92 is a virtual circle having a diameter that is smaller than the outer diameter (diameter) of the turbine impeller 9, with the center axis C as the center. The diameter of the second imaginary circle 92 can be, for example, 10% or more and 75% or less of the outer diameter of the turbine impeller 9, or 10% or more and 50% or less, or 10% or more and 25% or less.

[0081] In the present example, the axis S passes through the center axis C when viewed in the turbine axial direction. Also, in the case where such a structure is employed, the two communication ports 11A (refer to FIG. 5) connected to both end portions of the communication flow path 18 are disposed at mutually different positions in the turbine radial direction. Figure 2 According to the above-described structure, since the discharge port 41 discharges the exhaust gas toward the center axis C of the turbine impeller 9 when viewed in the turbine axial direction, it is possible to shorten the flow path length of the bypass flow path 15 for guiding the exhaust gas to the discharge flow path 19. Therefore, it is possible to simplify the structure of the turbine housing 10.

[0082] <Driving portion of valve device 30>

[0083]

[0084] Returning to Figure 1 ​​​​​​​The valve device 30 further includes an actuator 37 for driving the valve shaft 35 and a link rod 38 linking the actuator 37 and a first end portion 351 (refer to Fig. 6) of the valve shaft 35. The actuator 37 is fixed to the compressor housing 7. The link rod 38 extends in the turbine axial direction and is configured to transmit a driving force of the actuator 37 to the valve shaft 35. By rotating the valve shaft 35 with the driving of the actuator 37, the valve device 30 is capable of opening and closing the communication flow path 18 and the bypass flow path 15, respectively. Figure 3

[0085] According to the above-described structure, since the actuator 37 is disposed at the compressor housing 7 rather than at the turbine housing 10 which is relatively likely to become high temperature, temperature rise of the actuator 37 and the link rod 38 can be avoided. Thus, thermal deformation of the valve shaft 35 can be avoided, and therefore, the axis S of the valve shaft 35 can be prevented from deviating from the desired position.

[0086] <Summary>

[0087] The above-described contents described in the embodiments are grasped as follows, for example.

[0088] 1) The twin-screw turbine 5 according to at least one embodiment of the present application includes a turbine housing 10 formed with two helical flow paths 11 configured to guide exhaust gas to a turbine impeller 9 in a twin-screw type and a discharge flow path 19 for discharging the exhaust gas that has passed through the turbine impeller, wherein

[0089] The turbine housing includes:

[0090] a communication flow path wall 28 that defines a communication flow path 18 that communicates the two helical flow paths with each other; and

[0091] a bypass flow path wall 25 that defines a bypass flow path 15 for guiding the exhaust gas that has flowed through the communication flow path to the discharge flow path while bypassing the turbine impeller,

[0092] a guide outlet 41 that is formed in the communication flow path wall and guides the exhaust gas that has flowed through the communication flow path to the bypass flow path,

[0093] The twin-screw turbine further includes a valve device 30,

[0094] The valve device includes:

[0095] a valve shaft 35 that extends across the communication flow path and is disposed such that an axis S passes through the guide outlet;

[0096] a first opening and closing plate 31 that is installed on the valve shaft in a manner of extending along the axis and is used to open and close the communication flow path with rotation of the valve shaft; and

[0097] ​A second shutter plate 32 extends in a direction intersecting the axis and is installed on the valve shaft on the guide outlet side more than the first shutter plate, and functions to open and close the bypass flow path as the valve shaft rotates.

[0098] According to the structure of the above 1), since the first shutter plate and the second shutter plate for opening and closing the communication flow path and the bypass flow path, respectively, are configured to be separate from each other, a double spiral turbine in which the opening and closing degrees of freedom of the communication flow path and the bypass flow path are improved is realized. In such a double spiral turbine, whether or not the bypass flow path is opened and closed at the time of opening the communication flow path can be freely adjusted at the design stage of the double spiral turbine. Also, it is possible to make the opening time of the bypass flow path different from the opening time of the communication flow path, and it is also possible to suppress accidental leakage of exhaust gas in the bypass flow path or the communication flow path.

[0099] 2) In some embodiments, the double spiral turbine according to the above 1), wherein

[0100] The second shutter plate defines an opening 29 in an inner side area R1 of a first imaginary circle 91 centered on the axis and having a maximum distance from the axis to an outer peripheral surface 27 of the second shutter plate as a radius,

[0101] The second shutter plate is configured to switch as the valve shaft rotates between an open state in which the communication flow path and the bypass flow path are communicated via the opening, and a closed state in which the bypass flow path is closed.

[0102] According to the structure of the above 2), the position of the opening defined by the second shutter plate changes as the valve shaft rotates, so that the second shutter plate can open and close the bypass flow path. The timing of opening and closing the communication flow path can be made to coincide with or differ from the timing of opening and closing the bypass flow path, freely, according to the shape of the second shutter plate determined at the design stage of the double spiral turbine. Thus, the communication flow path and the bypass flow path can be further freely opened and closed.

[0103] 3) In some embodiments, the double spiral turbine according to the above 2), further comprising:

[0104] An opposing plate 33 opposed to the second shutter plate from the upstream side in the flow direction of the bypass flow path, and defining a passage 36 for the exhaust gas to pass through,

[0105] The second shutter plate is configured to open the bypass flow path by opposing the opening to the passage, and to close the bypass flow path by staggering the opening and the passage.

[0106] According to the structure of the above 3), by providing the opposing plate separate from the turbine housing, it is possible to avoid the complication of the shape of the turbine housing.

[0107] Further, since the bypass passage is opened and closed only by whether the opening defined by the second opening and closing plate opposes the through port, it is possible to simplify the structure of the valve device.

[0108] 4) In some embodiments, the dual-screw turbine according to the above 3), wherein,

[0109] The through ports are provided at intervals in the circumferential direction with reference to the axis.

[0110] According to the structure of the above 4), since the through ports are provided, it is possible to disperse the positions through which the exhaust gas passes in the opposing plate, and it is possible to suppress excessive temperature rise in a specific portion of the opposing plate.

[0111] 5) In some embodiments, the dual-screw turbine according to the above 4), wherein,

[0112] The through ports are provided at intervals in the circumferential direction with reference to the axis.

[0113] The opening defined by the second opening and closing plate is provided at intervals in the circumferential direction with the same number of intervals as the through ports.

[0114] According to the structure of the above 5), compared to the case where the number of openings is less than the number of through ports, it is possible to reduce the amount of rotation of the second opening and closing plate required to open and close the bypass passage.

[0115] Thereby, it is possible to quickly open and close the bypass passage.

[0116] 6) In some embodiments, the dual-screw turbine according to any one of the above 1) to 5), wherein,

[0117] When viewed in the axial direction of the turbine impeller (turbine axial direction), the axis of the valve rod passes through the inside region R2 of the second imaginary circle 92 whose diameter is below the outer diameter of the turbine impeller, with the center axis C of the turbine impeller as the center.

[0118] According to the structure of the above 6), since the exhaust port discharges the exhaust gas toward the center axis of the turbine impeller when viewed in the axial direction, it is possible to shorten the flow path length of the bypass passage. Therefore, it is possible to simplify the structure of the turbine housing.

[0119] 7) The turbocharger 1 according to at least one embodiment of the present application includes:

[0120] a rotating shaft 3;

[0121] The twin-screw turbo 5 according to any one of the above 1) to 5), includes the turbine impeller 9 coupled to one end portion 3A of the rotary shaft; and

[0122] The compressor 8 includes the compressor impeller 6 coupled to the other end portion 3B of the rotary shaft.

[0123] According to the structure of the above 7), the same technical advantages as the above 1) can be obtained.

[0124] 8) In several embodiments, the twin-screw turbo according to the above 7), wherein,

[0125] The compressor further includes a compressor casing 7 that houses the compressor impeller,

[0126] The valve device further includes:

[0127] An actuator 37 for driving the valve rod; and

[0128] A coupling rod 38 coupled to the actuator and the valve rod, and configured to transmit the driving force of the actuator to the valve rod,

[0129] The actuator is disposed in the compressor casing.

[0130] According to the structure of the above 8), since the actuator is disposed in the compressor casing instead of the turbine casing which relatively easily becomes high temperature, temperature rise of the actuator and the coupling rod can be avoided. Thus, since thermal deformation of the valve rod can be avoided, the axis of the valve rod can be prevented from deviating from the desired position.

[0131] Symbol explanation

[0132] 1 - turbocharger, 3 - rotary shaft, 3A - one end portion, 3B - other end portion, 5 - twin-screw turbo (turbine), 6 - compressor impeller, 7 - compressor casing, 8 - compressor, 9 - turbine impeller, 10 - turbine casing, 11 - spiral flow path, 15 - bypass flow path, 18 - communication flow path, 18A - communication flow path center line, 19 - discharge flow path, 25 - bypass flow path wall, 27 - outer peripheral surface, 28 - communication flow path wall, 29 - opening, 30 - valve device, 31 - first opening and closing plate, 32 - second opening and closing plate, 33 - opposing plate, 34 - coupling portion, 35 - valve rod, 36 - passage, 37 - actuator, 38 - coupling rod, 39 - main body portion, 41 - guide outlet, 91 - first imaginary circle, 92 - second imaginary circle, 339 - outer peripheral surface, 351 - first end portion, 352 - second end portion, 353 - extension portion, C - center axis, L1 - dimension, R1, R2 - inner side region.

Claims

1. A twin-screw turbine comprising a turbine housing, wherein the turbine housing is formed with two spiral flow paths of a twin-screw type for guiding exhaust gas to a turbine impeller, and a discharge flow path for discharging the exhaust gas having passed through the turbine impeller, wherein: The turbine housing comprises: a connecting flow path wall defining a connecting flow path that connects the two spiral flow paths to each other; and a bypass flow path wall defining a bypass flow path for guiding the exhaust gas flowing through the communication flow path to the exhaust flow path so as to bypass the turbine impeller. A guide port for guiding the exhaust gas flowing through the communicating flow path to the bypass flow path is formed on the communicating flow path wall. The twin-screw turbine further comprises a valve device, The valve device comprises: a valve stem extending across the communication flow path and arranged with its axis passing through the guide port; a first opening and closing plate mounted on the valve stem so as to extend along the axis and configured to open and close the communication flow path as the valve stem rotates; and The second opening and closing plate extends in a direction intersecting the axis, is attached to the valve stem on the outlet side relative to the first opening and closing plate, and opens and closes the bypass flow path as the valve stem rotates.

2. The twin-screw turbine according to claim 1, wherein: The second opening and closing plate defines an opening, and the opening is located inside a first imaginary circle having the axis as its center and a maximum distance from the axis to the outer peripheral surface of the second opening and closing plate as its radius. The second opening and closing plate is configured to switch between an open state and a closed state as the valve stem rotates. The open state is a state in which the communication flow path and the bypass flow path are connected via the opening, and the closed state is a state in which the bypass flow path is closed.

3. The twin-screw turbine according to claim 2, further comprising: an opposing plate that opposes the second opening and closing plate from the upstream side in the flow direction of the bypass flow path and defines a passage opening for the exhaust gas to pass through; The second opening and closing plate is configured to open the bypass flow path by making the opening face the passage port, and to close the bypass flow path by shifting the opening from the passage port.

4. The twin-screw turbine according to claim 3, wherein: A plurality of the through openings are arranged at intervals in a circumferential direction with respect to the axis.

5. The twin-screw turbine according to claim 4, wherein: The plurality of passage openings are arranged at equal intervals in the circumferential direction, The openings defined by the second opening and closing plate are arranged at equal intervals in the circumferential direction at intervals equal to the number of the plurality of passage openings.

6. The twin-screw turbine according to any one of claims 1 to 3, wherein: When viewed in the axial direction of the turbine impeller, the axis of the valve stem passes through an inner region of a second imaginary circle centered on the central axis of the turbine impeller and having a diameter equal to or smaller than an outer diameter of the turbine impeller.

7. A turbocharger comprising: Rotation axis; The twin-screw turbine according to any one of claims 1 to 3, comprising the turbine wheel connected to one end of the rotating shaft; and The compressor includes a compressor impeller connected to the other end portion of the rotating shaft.

8. The turbocharger according to claim 7, wherein: The compressor further comprises a compressor housing accommodating the compressor impeller, The valve device further comprises: an actuator for driving the valve stem; and a connecting rod connected to the actuator and the valve stem and configured to transmit the driving force of the actuator to the valve stem; The actuator is disposed on the compressor housing.

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