Variable nozzle device, turbine and turbocharger

Abstract

Variable nozzle device (20) for a variable geometry turbocharger (1), comprising: a nozzle holder (21); a nozzle plate (22) arranged such that it faces the nozzle holder (21), wherein the nozzle plate (22) forms a nozzle flow channel (4) with an annular shape between the nozzle plate (22) and the nozzle holder (21); and a plurality of variable nozzle vanes (6) arranged at a predetermined interval in a circumferential direction of the nozzle flow channel (4) such that they can be individually rotated about a pivot axis (O2), wherein the nozzle plate (22) comprises a first surface (33) facing the nozzle holder (21), a second surface (35) opposite the first surface (33), and at least one through-hole (36) formed through the first surface (33) and the second surface (35), wherein the at least one through-hole (36) has a first opening (36a) formed on the first surface (33) on an inside of the pivot axis (O2) with respect to a radial direction, and a second opening (36b) formed on the second surface (35) on an outside of the first opening with respect to the radial direction or at the same position as the first opening (36a) with respect to the radial direction, and wherein the at least one through-hole (36) comprises a single annular flow channel extending in the circumferential direction.

Description

TECHNICAL AREA

[0001] The present disclosure relates to a variable nozzle device, a turbine and a turbocharger. STATE OF THE ART

[0002] A radial turbine and a mixed-flow turbine, which include a flow rate control device for exhaust gas to be introduced into a turbine, have a major advantage in that the turbine speed and rotational speed are variable, or that it is possible to ensure a high response to a change in the power output of an engine, for example, and are thus often intended for a turbocharger to be mounted on an automobile engine, an expansion turbine used in a power generation engine, a small-size gas turbine, etc.

[0003] A turbocharger equipped with a radial turbine or a mixed-flow turbine is configured to drive a turbine rotating with exhaust gas (working fluid) from an engine, for example while intake air is compressed by rotating a compressor that is coaxially coupled to the turbine and the compressed intake air is supplied to the engine.

[0004] Meanwhile, a flow rate control device for exhaust gas is arranged in an annular nozzle flow channel defined by a turbine housing on the outer circumferential side of a turbine wheel, and comprises a plurality of nozzle blades arranged in the circumferential direction.

[0005] Furthermore, an exhaust gas flow rate control device can include a variable nozzle device comprising a plurality of variable nozzle blades driven by an actuator to rotate and arranged such that a leading edge of one of the adjacent nozzle blades and a trailing edge of the other of the adjacent nozzle blades overlap to close the flow channel in a closing operation, thereby making the size of the exhaust gas flow channel, i.e., the exhaust gas flow rate, flexibly adjustable in accordance with the degree of rotation of the respective variable nozzle blades.

[0006] A variable geometry turbocharger / turbine incorporating such a variable nozzle device is able to operate in accordance with changes in engine load and exhibits a particularly high responsiveness when the load is low.

[0007] However, it is known that in a variable geometry turbocharger, when the opening degree of the variable nozzles (variable nozzle vanes) is small, the turbine efficiency decreases compared to a peak point, i.e., when the nozzle opening degree is close to the intermediate opening degree range. The turbine efficiency at times when the nozzle opening degree is in the small opening degree range significantly affects the response sensitivity, and therefore it is desirable to improve the turbine efficiency in the small opening degree range.

[0008] When the variable nozzles 6 are in the small opening degree range, exhaust gas (working fluid G) flowing into the turbine rotor blades 13 has a strong turbulence component due to the small nozzle opening degree, but the flow velocity component directed radially inwards is small (see Fig. 11, which represents the state of the art). Thus, as in Fig. As shown in Figure 11, in the case of a typical variable geometry turbocharger (variable nozzle device 100), in the small opening range of the variable nozzles 6, it is likely that exhaust gas G is attracted to the inner surface 31 on the side of the casing (casing section 30) due to a centrifugal force generated by a turbulence component of the exhaust gas G flowing into the turbine rotor blades 13. As the exhaust gas G is attracted to the casing side, it flows closer to the casing side at the outlet of the turbine rotor blades 13, and the flow velocity increases on the casing side and decreases near the inner surface 32 on the side of the hub (turbine hub 12). As a result, the exhaust gas flow spreads out to counteract the imbalance of flow velocity on the downstream side of the rotor blades 13, and a mixing loss is likely to occur.

[0009] In this respect, patent document 1 discloses a turbine and a turbocharger which is provided with a projecting section which extends towards the inner surface on the hub side and is arranged on the inner surface on the casing side in order to suppress a distortion of the exhaust gas flow towards the casing side.

[0010] In the turbine and turbocharger of patent document 1, which are configured to include the aforementioned section, exhaust gas flows along the aforementioned section and is directed towards the inner surface on the hub side. This makes it possible to suppress any deviation of the exhaust gas flow towards the casing side, i.e., exhaust gas drift. Thus, the uneven flow at the turbine rotor blade outlet is reduced, and mixing losses are minimized, thereby improving turbine efficiency. Accordingly, in addition to the advantage described above of ensuring maximum flow rate in the large opening range of the variable nozzles, a further advantage of improved turbine efficiency in the small opening range of the variable nozzles is achieved.Patent document 2 discloses a turbine for an exhaust gas turbocharger, in particular of an internal combustion engine, with a turbine housing which has a receiving space for a turbine wheel, with a bypass device which includes at least one bypass channel by which the turbine wheel is bypassed by exhaust gas flowing through the turbine housing and with at least one adjusting device which is at least partially movable relative to the turbine housing by means of which a variable turbine geometry is provided for variably adjusting flow conditions for the exhaust gas, wherein the amount of exhaust gas flowing through the bypass channel is adjustable by moving the adjusting device.

[0011] To improve the turbine's efficiency by preventing exhaust gas separation with respect to variable blades, patent document 3 proposes a compressor comprising a turbine wheel housed in a turbine casing. The turbine casing contains a spiral channel through which an annular gas flow channel extends from the spiral channel to the turbine wheel, and variable blades arranged in relation to the annular gas flow channel. Flow-guiding holes are perforated in a section facing and in contact with the annular gas flow channel of the turbine casing. These flow-guiding holes communicate with the spiral channel and the annular gas flow channel, so that the exhaust gas from the spiral channel is blown along the surfaces of the variable blades.

[0012] Patent document 4 discloses a circular, annular cover plate arranged between a screw, spiral, or roller passage (a spiral casing) and a turbine chamber. The cover plate has a through-opening that extends along an axis of the turbine shaft. A variable nozzle is mounted to the cover plate in an openable / closeable manner by means of a shaft inserted through the through-opening. A gap between the cover plate and a turbine casing, extending along the axis, is divided into: a first chamber connected to an exhaust outlet opposite the through-opening and located upstream of the turbine wheel with respect to the exhaust flow; and a second chamber connected to the spiral passage by a disc spring arranged to surround the turbine wheel.

[0013] To improve the turbine's efficiency by reliably and effectively preventing exhaust gas from escaping from the side of a turbine screw flow channel, patent document 5 proposes providing an annular sealing base part on an outer edge of a casing ring. This base part forms the base of a sealing element and is bonded to the opposite side of a mating surface of the casing ring. A tubular sealing intermediate part, covering a casing section, is integrally formed at an inner edge of the sealing base part and projects laterally beyond a gas outlet opening. An annular sealing upper part is integrally formed at an upper edge of the sealing intermediate part and is radially rolled outwards. The sealing upper part is brought into press contact with an inner circumferential surface of a stage section of a turbine housing. Citation list for patent literature Patent document 1: WO 2016 / 031 017 A1 Patent document 2: DE 10 2011 120 880 A1 Patent document 3: JP 2009-8 013 A Patent document 4: DE 11 2012 004 774 T5 Patent document 5: JP 2013-194 546 A SUMMARY Problems to be solved

[0014] As described above, the turbine and turbocharger disclosed in patent document 1 are provided with the aforementioned section, thus making it possible to suppress exhaust gas drift towards the casing side by directing the exhaust gas flow towards the hub side when the variable nozzles are in the small opening range. However, when the variable nozzles are in the large opening range, the aforementioned section becomes a resistance, causing a loss of fluid energy in the exhaust gas, which can reduce the turbine efficiency. In this respect, there is still room for further improvement.

[0015] In light of the above, it is an object of the present disclosure to provide a variable nozzle device, a turbine and a turbocharger that are capable of reducing fluid energy loss of a working fluid in all ranges including the small opening degree range and the large opening degree range of the variable nozzles, thereby improving the turbine efficiency even more effectively. Problem solving

[0016] According to one aspect of the present disclosure, a variable nozzle device for a variable geometry turbocharger comprises: a nozzle holder; a nozzle plate arranged to face the nozzle holder, the nozzle plate forming an annular nozzle flow channel between the nozzle plate and the nozzle holder; and a plurality of variable nozzle vanes arranged at intervals in a circumferential direction of the nozzle flow channel such that they are individually rotatable about a pivot axis. The nozzle plate comprises a first surface facing the nozzle holder, a second surface opposite the first surface, and at least one through-hole formed through the first and second surfaces.The at least one through-hole has a first opening formed on the first surface on an inside of the pivot axis with respect to a radial direction, and a second opening formed on the second surface on an outside of the first opening with respect to the radial direction or at the same position as the first opening with respect to the radial direction, wherein the at least one through-hole comprises a single annular flow channel extending in the circumferential direction.

[0017] According to one aspect of the present disclosure, a variable nozzle device for a variable geometry turbocharger comprises: a nozzle holder; a nozzle plate arranged to face the nozzle holder, the nozzle plate forming an annular nozzle flow channel between the nozzle plate and the nozzle holder; and a plurality of variable nozzle vanes arranged at intervals in a circumferential direction of the nozzle flow channel such that they are individually rotatable about a pivot axis. The nozzle plate comprises a first surface facing the nozzle holder and a sliding element configured to move forward and backward from the first surface with respect to the nozzle flow channel.The sliding element comprises a first side facing the nozzle flow channel and a second side opposite the first side, wherein the sliding element is configured to move forward or retract in accordance with a pressure difference between a pressure applied to the first side and a pressure applied to the second side.

[0018] According to one aspect of the present disclosure, a turbine comprises: a rotating shaft; a turbine wheel arranged at a first end face of the rotating shaft and the variable nozzle device described above.

[0019] According to one aspect of the present disclosure, a turbocharger comprises the turbine described above. Beneficial effects

[0020] With the variable nozzle device, the turbine and the turbocharger according to one aspect of the present disclosure, it is possible to reduce a fluid energy loss of a working fluid in all areas including the small opening degree range and the large opening degree range of the variable nozzles (variable nozzle blades), thereby improving the turbine efficiency even more effectively. BRIEF DESCRIPTION OF THE DRAWINGS Fig. Figure 1 is a cross-sectional view showing a turbine and a turbocharger according to the first embodiment and the second embodiment. Fig. Figure 2 is a cross-sectional view showing a variable nozzle device, a turbine, and a turbocharger according to the first embodiment, viewed in the axial direction (downstream side in the flow direction of the working fluid). The Fig. The embodiment shown in Figure 2 is not part of the invention. Fig. Figure 3 is a cross-sectional view showing a variable nozzle device according to the first embodiment. Fig. Figure 4 is a cross-sectional view showing a variable nozzle device according to the first embodiment. Fig. Figure 5 is a cross-sectional view showing a modified example of the variable nozzle device, turbine and turbocharger according to the first embodiment, seen in the axial direction (downstream side in the flow direction of the working fluid). Fig. Figure 6 is a cross-sectional view showing the position of a variable nozzle device according to the second embodiment. Fig. Figure 7 is a cross-sectional view showing a variable nozzle device according to the second embodiment. Fig. Figure 8 is a cross-sectional view showing a modified example of a variable nozzle device according to the second embodiment. Fig. Figure 9 is a view showing a modified example of the nozzle plate (nozzle plate body part) of the variable nozzle device according to the second embodiment, seen in the axial direction (downstream side in the flow direction of the working fluid). Fig. Figure 10 is a view showing a modified example of the sliding element of the variable nozzle device according to the second embodiment, seen in the axial direction (downstream side in the flow direction of the working fluid). Fig. Figure 11 is a cross-sectional view showing a typical variable nozzle device (turbine, turbocharger) according to the state of the art. DETAILED DESCRIPTION (First embodiment)

[0021] Now, with reference to Fig. 1 to Fig. 5 and Fig. 11 a variable nozzle device, a turbine and a turbocharger according to the first embodiment is described. (Turbocharger)

[0022] The turbocharger according to the present embodiment is a turbo device that improves the performance of an engine by utilizing the energy of a working fluid (exhaust gas) emitted by the engine. The turbocharger drives a turbine with exhaust gas emitted from the engine, which in turn drives a compressor, coaxially coupled to the turbine, to compress intake air and supply the compressed intake air to the engine.

[0023] In particular, the turbocharger 1 according to the present embodiment comprises a radial turbine 2 or a mixed-flow turbine (hereinafter referred to as turbine), as in Fig. 1 shown. (Turbine)

[0024] As in Fig. 1 and Fig. As shown in Figure 2, the turbine 2 comprises a turbine wheel 3 rotating about the axis O1 of the turbocharger 1, a turbine housing 5 accommodating the turbine wheel 3 and forming a nozzle flow channel 4 with an annular shape on the outer circumferential side centered on the axis O1 of the turbine wheel 3, and a flow rate adjustment device (flow rate adjustment mechanism of a working fluid (exhaust gas G in the present embodiment)) 7 arranged in the nozzle flow channel 4 on the outer side of the turbine wheel 3 with respect to the radial direction, comprising a plurality of variable nozzle blades 6 arranged at a predetermined interval in the circumferential direction of the turbine wheel 3.

[0025] The turbine wheel 3 comprises, at one end of a rotating shaft 11 rotatably supported by journal bearings 9, 10 which are received in a bearing housing 8, a turbine hub 12 which is arranged on the same axis O1 and is integrally provided such that it has a substantially frustoconical shape, and a plurality of turbine rotor blades 13 which are arranged at a predetermined interval in the circumferential direction centered on the axis O1 on the circumferential surface of the turbine hub 12.

[0026] At the other end of the rotating shaft 11, a compressor hub 14 with a substantially frustoconical shape is integrally arranged, and a plurality of compressor blades 15 are arranged at a predetermined interval in the circumferential direction on the circumferential surface of the compressor hub 14.

[0027] The compressor hub 14 and the compressor blades 15 form a compressor wheel 16. The compressor wheel 16 is rotatably mounted in the compressor housing 17 about the axis O1.

[0028] In the present embodiment, the turbine housing 5 has within it a spiral flow channel 18 which is connected to the nozzle flow channel 4 and is configured to allow the working fluid G, which is introduced from outside the turbine housing 5, to flow to the nozzle flow channel 4, and an exhaust flow channel 19 with a tubular shape which is connected to the nozzle flow channel 4 and extends along the axis O1 and is configured to allow the working fluid G to flow to the outside of the turbine housing 5 after the turbine wheel 3 has been driven. (Variable nozzle device)

[0029] However, according to the present embodiment, the turbocharger 1 is a variable geometry turbocharger and is configured such that the flow rate adjustment device 7 comprises a variable nozzle device 20.

[0030] Similar to the typical variable nozzle device 100, which is in Fig. As shown in Figure 11, the variable nozzle device 20 comprises a nozzle holder 21, a nozzle plate 22 arranged such that it faces the nozzle holder 21 and forms a nozzle flow channel 4 with an annular shape between the nozzle holder 21 and the nozzle plate 22, a plurality of variable nozzle blades 6 arranged at a predetermined interval in the circumferential direction of the nozzle flow channel 4 so that they are individually rotatable about the pivot axis O2, and a nozzle rotation mechanism 23 for rotating the plurality of variable nozzle blades 6.

[0031] The nozzle plate 22 is designed such that, as in Fig. 3 and Fig. 4 (see Fig. 1 and Fig. 11) shown, comprising a nozzle plate body part 34 with a first surface 33 facing the nozzle holder 21 and a jacket part 30 with an inner surface 31 facing the inner surface 32 on the hub side.

[0032] Furthermore, the variable nozzle device 20 according to the present embodiment comprises a first surface 33 of the nozzle plate body part 34, a second surface 35 opposite the first surface 33, and a through-hole 36 formed by the first surface 33 and the second surface 35.

[0033] Furthermore, the through-hole 36 of the present embodiment has a first opening 36a, which is formed on the first surface 33 of the nozzle plate body part 34 on the inside of the pivot axis O2 of the variable nozzle blade 6 with respect to the radial direction, and a second opening 36b, which is formed on the second surface 35 on the outside of the first opening 36a with respect to the radial direction. Accordingly, the through-hole 36 is configured to penetrate obliquely from the second surface 33 towards the first surface 33 of the nozzle plate body part 34.

[0034] Nevertheless, the second opening 36b can be arranged in the same position as the first opening 36a in the radial direction.

[0035] Furthermore, in the Fig. In the embodiment shown in Figure 2, a plurality of through holes 36 are arranged at intervals in the circumferential direction centered on the axis O1. Each plurality of through holes 36 is designed to form a pair with corresponding variable nozzle blades 6 and is arranged at a position on the inside of the corresponding variable nozzle blades 6 with respect to the radial direction. It should be noted that the Fig. The embodiment shown in point 2 does not belong to the invention.

[0036] Furthermore, the through-hole 36 can be designed such that the first opening 36a has a smaller opening area than the second opening 36b.

[0037] With the variable nozzle device 20, the turbine 2 and the turbocharger 1 according to the present embodiment, it is possible to change, modify and adjust the flow rate of the working fluid G, which is delivered by the engine and supplied to the turbine wheel 3, which flows through the nozzle flow channel 4 from the spiral flow channel 18, by rotating the plurality of variable nozzle blades 6, which are driven by the nozzle rotation mechanism 23, and by changing the nozzle opening degree.

[0038] At this time, the pressure difference between the upstream side (the side of the spiral flow channel 18) with respect to the flow direction of the working fluid G, which is the high-pressure side, and the downstream side with respect to the flow direction of the working fluid G, which is the low-pressure side, is via the variable nozzle blade 6 (see prior art in Fig. 11) the larger the smaller the opening degree of the variable nozzle blade 6 is in the small opening degree range.

[0039] In this respect, the variable nozzle device 20, the turbine 2 and the turbocharger 1 according to the present embodiment are provided with the through-hole 36, which is formed through the first surface 33 and the second surface 35 of the nozzle plate body part 34, and the through-hole 36 has the first opening 36a, which is formed on the first surface 33 on the inside of the pivot axis O2 of the variable nozzle blade 6 with respect to the radial direction, and the second opening 36b, which is formed on the second surface 35 on the outside of the first opening 36a with respect to the radial direction.

[0040] Accordingly, in the variable nozzle device 20, the turbine 2 and the turbocharger 1 according to the present embodiment, as shown in Fig. 4 (see Fig. 11) shown, the working fluid “g” (G) is injected through the through-hole 36 according to the pressure difference between the upstream side (the side of the spiral flow channel 18) with respect to the flow direction of the working fluid G, which is the high-pressure side, and the downstream side with respect to the flow direction of the working fluid G, which is the low-pressure side, and the working fluid “g” (G) in the spiral flow channel 18 is injected into the nozzle flow channel 4 at the inner side of the pivot axis O2 of the variable nozzle blade 6 with respect to the radial direction from the first opening 36a of the through-hole 36.

[0041] When the working fluid “g” injected from the through-hole 36 combines with the working fluid G which flows through the nozzle flow channel 4 towards the turbine wheel 3 from the plurality of variable nozzle blades 6, the flow of the working fluid G is directed towards the inner surface 32 on the hub side, and thereby it is possible to suppress a deviation of the working fluid G towards the casing, that is, to suppress the drift of the working fluid G, without providing a protruding section on the first surface 33 as in the typical variable nozzle device 100.

[0042] Furthermore, the pressure difference between the upstream side (high pressure side) with respect to the flow direction of the working fluid G, and the downstream side (low pressure side) with respect to the flow direction of the working fluid G, is greater the smaller the opening degree of the variable nozzle blades 6 is in the small opening degree range. In other words, the pressure difference is greater in the intermediate opening degree range than in the large opening degree range and in the small opening degree range than in the intermediate opening degree range of the variable nozzle blades 6. Thus, it is possible to increase the injection force (injection velocity) of the working fluid "g", which is injected further from the through-bore 36, when the opening degree of the variable nozzle blades 6 decreases.

[0043] Accordingly, in the small opening range of the variable nozzle blades 6, where a considerable drift of the working fluid G towards the casing side is generated, it is possible to effectively suppress this drift. In the large opening range of the variable nozzle blades 6, where no drift is generated, the working fluid "g" injected from the through-hole 36 does not impede the flow of the working fluid G. Thus, it is possible to suppress the occurrence of fluid energy loss.

[0044] Therefore, with the variable nozzle device 20, the turbine 2 and the turbocharger 1 according to the present embodiment, which has the through-hole 36 formed by the first surface 33 and the second surface 35 of the nozzle plate body part 34, and the through-hole 36 having the first opening 36a on the inside of the pivot axis O2 of the variable nozzle blades 6 with respect to the radial direction, and the second opening 36b formed on the second surface 35 on the outside of the first opening 36a with respect to the radial direction, it is possible to reduce an uneven flow of the working fluid G at the outlet of the turbine rotor blades 13, to reduce mixing losses and to improve the turbine efficiency.

[0045] Accordingly, in addition to the advantage described above of having variable nozzle blades 6 in the large opening range, which ensures the maximum flow rate, it is also possible to reliably achieve the advantage of having variable nozzle blades 6 in the small opening range, which improves turbine efficiency. In other words, it is possible to reduce fluid energy loss of the working fluid G in all ranges, including the small and large opening ranges of the variable nozzle blades 6, thereby improving turbine efficiency even more effectively.

[0046] The same advantageous effect as above can be achieved if the second opening 36b of the through hole 36 is arranged in the same position as the first opening 36a with respect to the radial direction.

[0047] Furthermore, as in Fig. As shown in Figure 2, with the multitude of through-holes 36 arranged at intervals in the circumferential direction centered on the axis O1, and the working fluid “g” injected from the respective through-holes 36, it is possible to completely and effectively suppress any drift of the working fluid G flowing through the turbine wheel 3 in the circumferential direction within the small opening degree range of the variable nozzle blades 6. It should be noted again that the Fig. The embodiment shown in Figure 2 is not part of the invention. Furthermore, with each of the plurality of through holes 36, which are arranged to form a pair with corresponding to the plurality of variable nozzle blades 6 on the inside of the corresponding nozzle blade 6 with respect to the radial direction, it is possible to suppress a drift of the working fluid G flowing through the turbine wheel 3 more effectively in the circumferential direction.

[0048] Furthermore, if the through-hole 36 is designed such that the opening area of ​​the first opening 36a is smaller than that of the second opening 36b, it is possible to increase the injection force (injection velocity) of the working fluid “g” that is injected from the first opening 36a, and it is possible to suppress a drift of the working fluid G that flows through the turbine wheel 3 in the small opening degree range of the variable nozzle blades 6 even more effectively.

[0049] The variable nozzle device, the turbine and the turbocharger according to the first embodiment of the present disclosure have been described.

[0050] As in Fig. As shown in Figure 5, the through-hole 36 is designed according to the invention to comprise a single annular flow channel extending along the circumferential direction. In this case, the working fluid “g” is injected from the first opening 36a, which extends completely in the circumferential direction, and it is thus possible to effectively suppress any drift of the working fluid G flowing through the turbine wheel 3 in the small opening degree range of the variable nozzle blades 6 in the circumferential direction.

[0051] Furthermore, the configuration and modification examples of the first embodiment can be combined with the configuration and modification examples of the second embodiment, which are described below, to achieve, for example, a beneficial synergistic effect. (Second embodiment)

[0052] Next, with reference to Fig. 1, Fig. 6 to Fig. 10 and Fig. 11. A variable nozzle device, a turbine, and a turbocharger according to the second embodiment are described. The variable nozzle device, turbine, and turbocharger according to the present embodiment differ from those according to the first embodiment in the configuration of the variable nozzle device, but are otherwise identical. Thus, in the present embodiment, the same components as those in the first embodiment are assigned, for example, the same reference numerals and are not described in detail. (Variable nozzle device)

[0053] The variable nozzle device 40 according to the present embodiment comprises, as shown in Fig. 6 and Fig. 7 (see Fig. 1 and Fig. 11) shown, a nozzle holder 21, a nozzle plate 22 comprising a nozzle plate body part 34 and a jacket part 30, and a plurality of variable nozzle vanes 6, similar to the first embodiment.

[0054] On the other hand, the variable nozzle device 40 includes a sliding element 42 at a point defined by the S-section in Fig. 6 is displayed, in contrast to the first embodiment.

[0055] In particular, the variable nozzle device 40 according to the present embodiment comprises, as shown in Fig. Figure 7 shows the nozzle plate body part 34 of the nozzle plate 22, the first surface 33 facing the nozzle holder 21, and the sliding element 42, which is configured to move forward and retract from the first surface 33 with respect to the nozzle flow channel 4. Furthermore, the sliding element 42 comprises a first side 42a facing the nozzle flow channel 4 and a second side 42b opposite the first side 42a, and is configured to move forward or retract in accordance with the pressure difference between a pressure applied to the first side 42a and a pressure applied to the second side 42b.

[0056] Furthermore, the variable nozzle device 40 according to the present embodiment has a communication chamber 44, which is provided for the nozzle plate body part 34 between the sliding element 42 and the second surface 35. The communication chamber 44 is connected to the spiral flow channel 18 on the side of the second surface 35 via the through-hole 43, which has an opening on the second surface 35. A preloading element 45, such as a spring element, is arranged in the communication chamber 44. The preloading element 45 has a first end that is connected to a stationary element 41, such as the nozzle plate body part 34, and a second end that is connected to the second side 42b of the sliding element 42, and preloads the sliding element 42 towards the inside of the communication chamber 44, i.e., towards the second surface 35 of the nozzle plate body part 34.

[0057] Accordingly, in the variable nozzle device 40 according to the present embodiment, as in Fig. 7 (see Fig. 11 of the prior art), the pressure on the upstream side in the flow direction of the working fluid G (the side of the spiral flow passage 18), which is the high-pressure side, is transmitted via the through-hole 43 to the communication chamber 44 and applied to the second side 42b of the sliding element 42, and the pressure on the downstream side in the flow direction of the working fluid G (the side of the nozzle flow passage 4), which is the low-pressure side, is applied to the first side 42a of the sliding element 42. Furthermore, a preload force of the preload element 45 is applied to the sliding element 42.

[0058] Furthermore, according to the present embodiment, the sliding element 42 slides (moves forward) in accordance with the pressure difference between the pressure exerted on the first side 42a and the pressure exerted on the second side 42b. In the small opening range of the variable nozzle vanes 6, where the pressure difference is large, the first side 42a projects into the nozzle flow channel 4 with a protrusion corresponding to the magnitude of the pressure difference.

[0059] That is, the sliding element 42 according to the present embodiment is configured such that, for example, in the intermediate opening degree range and in the large opening degree range of the variable nozzle blades 6, where the pressure difference between the first surface 33 and the second surface 35 of the nozzle plate body part 34 is somewhat small, the first side 42a is positioned close to the first surface 33 (including the flush position) in response to the action of the preload force of the preload element 45 and is held in this retracted state.

[0060] Thus, when the variable nozzle blades 6 are in the intermediate opening degree range or in the large opening degree range, the sliding element 42 does not protrude beyond the first surface 33, and it is therefore possible to prevent the sliding element 42 from becoming a resistance that causes a loss of fluid energy and a deterioration of the turbine efficiency, as described in the preceding section of the typical variable nozzle device 100.

[0061] On the other hand, in the small opening degree range of the variable nozzle blades 6, the pressure difference is large, and thus the pressure within the communication space 44 increases and the force that pushes the second side 42b of the sliding element 42 increases relatively, and as a result, the sliding element 42 slides (is pushed forward) and the first side 42a of it protrudes beyond the first surface 33 of the nozzle plate body part 34 into the nozzle flow channel 4.

[0062] Accordingly, in the small opening range of the variable nozzle blades 6, the working fluid G flows along the first side 42a of the projecting sliding element 42, and the flow of the working fluid G is directed towards the hub. This suppresses the drift of the working fluid G towards the casing side, which makes it possible to reduce the uneven flow at the outlet of the turbine rotor blades 13 and to decrease mixing losses, thereby improving the turbine efficiency.

[0063] Therefore, with the variable nozzle device 40, the turbine 2, and the turbocharger 1 according to the present embodiment, in addition to the advantage described above of ensuring the maximum flow rate in the large opening range of the variable nozzle blades 6, it is possible to reliably achieve the advantage of improving the turbine efficiency in the small opening range of the variable nozzle blades 6. Furthermore, it is possible to suitably reduce the fluid energy loss of the working fluid G in either the small or large opening range of the variable nozzle blades 6 and effectively improve the turbine efficiency.

[0064] Furthermore, in the variable nozzle device 40, the turbine 2 and the turbocharger 1 according to the present embodiment, as described in Fig. Figure 7 shows, preferably that the first side 42a of the sliding element 42 has a tapered surface 42c configured to have a distance to the nozzle holder that decreases inwards in the radial direction.

[0065] In this case, in the small opening degree range of the variable nozzle blades 6, it is possible to allow the working fluid G to flow uniformly along the tapered surface 42c of the first side 42a of the protruding sliding element 42 and to suppress the occurrence of a fluid energy loss due to a disturbance of the flow of the working fluid G by the protruding sliding element 42.

[0066] Furthermore, in the variable nozzle device 40, the turbine 2, and the turbocharger 1 according to the present embodiment, the preload element 45 is provided to apply a preload force to the sliding element 42. In this way, it is possible to protrude the sliding element 42 by a protrusion amount corresponding to the pressure difference and to enable the sliding element 42 to retract appropriately and automatically with the preload force of the preload element 45 when the pressure difference decreases.

[0067] The variable nozzle device, the turbine and the turbocharger according to the second embodiment of the present disclosure have been described.

[0068] For example, the configuration and modification examples of the first and second embodiments can be selected and combined as needed. In this case, it is possible to achieve the desired effect of improving the rotor blade inlet characteristics and, in some cases, even more effectively or synergistically improving the turbine efficiency.

[0069] Furthermore, for example, as in Fig. 8 to Fig. Figure 10 shows that the nozzle plate 22 (nozzle plate body part 34) and the sliding element 42 comprise an engagement section 46 (engagement projection section 46a, engagement recess section 46b). The engagement sections 46 interlock and support the sliding element 42, enabling it to slide relative to the nozzle plate 22 and to move forward and backward relative to the first surface 33 of the nozzle plate 22.

[0070] In this case, the pressure on the side of the first surface 33, which is the low-pressure side, and the pressure on the side of the second surface 35, which is the high-pressure side, are applied directly to the first side 42a and the second side 42b of the sliding element 42, respectively. It is possible to make the sliding element 42 slide automatically in accordance with the pressure difference of the aforementioned pressures. Accordingly, it is possible to achieve the same advantageous effects as in the present embodiment and to improve the rotor blade penetration characteristics and the turbine efficiency.

[0071] Furthermore, in this case, by forming the engagement section 46 so that it has, for example, a T-shape, it is possible to prevent the sliding element 42 from moving forward and backward in the radial and circumferential directions around the axis O1.

[0072] Furthermore, by providing the stop 47, it is possible to limit the forward amount and the retraction amount of the sliding element 42, that is, the forward / retraction amount of the sliding element 42, and thus it is possible to appropriately control the position of the sliding element 42.

[0073] Furthermore, in the variable nozzle device 40 according to the present embodiment, if P1 is the first pressure on the side of the first surface 33 of the nozzle plate body part 34, that is, the first pressure on the low-pressure side of a section of the variable nozzle blade 6 on the inside of the pivot axis O2 with respect to the radial direction, P2 is the second pressure on the high-pressure side on the side of the second surface 35, and P3 is a predetermined threshold of the pressure difference between the first pressure P1 and the second pressure P2, the sliding element 42 can be configured to project beyond the first surface 33 in the direction of the nozzle holder 21 (nozzle flow channel 4) when a condition P2 - P1 > P3 is met, and retract to be accommodated between the first surface 33 and the second surface 35 when a condition P2 - P1 ≤ P3 is met.

[0074] That is to say, as long as it is possible to improve the rotor blade incidence characteristics and the turbine efficiency, the configuration according to the invention may not necessarily be limited to the present embodiment, as long as it remains within the scope of the attached claims.

[0075] Finally, the contents described in the above respective embodiments can be understood, for example, as follows. (1) According to one aspect, a variable nozzle device (the variable nozzle device 20 of the first embodiment) is a variable nozzle device for a variable geometry turbocharger (the turbocharger 1 of the first embodiment) and comprises: a nozzle holder (the nozzle holder 21 of the first embodiment); a nozzle plate (the nozzle plate 22 of the first embodiment) arranged such that it faces the nozzle holder, the nozzle plate forming a nozzle flow channel (nozzle flow channel 4 of the first embodiment) having an annular shape between the nozzle plate and the nozzle holder; and a plurality of variable nozzle vanes (variable nozzle vanes 6 of the first embodiment) arranged at a predetermined interval in a circumferential direction of the nozzle flow channel such that they are individually rotatable about a pivot axis (pivot axis O2 of the first embodiment).The nozzle plate comprises a first surface (the first surface 33 of the first embodiment) facing the nozzle holder, a second surface (the second surface 35 of the first embodiment) opposite the first surface, and at least one through-hole (through-hole 36 of the first embodiment) formed through the first and second surfaces. The at least one through-hole has a first opening (the first opening 36a of the first embodiment) formed on the first surface on an inside side of the pivot axis with respect to a radial direction, and a second opening (the second opening 36b of the first embodiment) formed on the second surface on an outside side of the first opening with respect to the radial direction, or at the same position as the first opening with respect to the radial direction.

[0076] With the variable nozzle device according to the present disclosure, when the working fluid injected from the through-hole combines with the working fluid flowing through the nozzle flow channel towards the turbine wheel from the several variable nozzle blades, the flow of the working fluid is directed towards the inner surface on the hub side, and thereby it is possible to suppress a deviation of the flow of the working fluid towards the casing, that is, to suppress the drift of the working fluid.

[0077] Furthermore, the pressure difference between the upstream side (high pressure side, relative to the flow direction of the working fluid) and the downstream side (low pressure side, relative to the flow direction of the working fluid) is greater the smaller the opening degree of the variable nozzle vanes is in the small opening degree range. In other words, the pressure difference is greater in the intermediate opening degree range than in the large opening degree range, and greater in the small opening degree range than in the intermediate opening degree range of the variable nozzle vanes. Thus, it is possible to further increase the injection force (injection velocity) of the working fluid injected from the through-hole when the opening degree of the variable nozzle vanes decreases.

[0078] Accordingly, in the small opening range of the variable nozzle blades, where a considerable drift of the working fluid towards the outer surface is generated, it is possible to effectively suppress this drift. In the large opening range of the variable nozzle blades, where drift is not generated (a significant drift is not generated), the working fluid injected from the through-hole does not impede the flow of the working fluid, and thus it is possible to suppress the occurrence of fluid energy loss.

[0079] Thus, it is possible to reduce the fluid energy loss of a working fluid in all areas, including the small opening degree range and the large opening degree range of the variable nozzle blades, and to improve the turbine efficiency even more effectively.

[0080] (2) The variable nozzle device according to a further aspect is the variable nozzle device according to (1) above, and the at least one through-hole comprises a plurality of through-holes arranged at intervals in the circumferential direction. Such an arrangement is not part of the claimed invention.

[0081] With the variable nozzle device according to this non-inventive disclosure, a plurality of through-holes are arranged at intervals in the circumferential direction, and the working fluid is injected from the respective through-holes. Accordingly, it is possible to completely and effectively suppress any drift of the working fluid flowing through the turbine wheel in the small opening degree range of the variable nozzle blades in the circumferential direction.

[0082] (3) The variable nozzle device according to a further aspect of the first embodiment according to the invention is the variable nozzle device according to (1) above, and the at least one through-hole comprises a single annular flow channel extending in the circumferential direction.

[0083] With the variable nozzle device according to the present disclosure, the at least one through-hole comprises a single annular flow channel extending along the circumferential direction, and thus the working fluid is injected from the first opening extending in the circumferential direction. This makes it possible to completely suppress any drift of the working fluid flowing through the turbine wheel in the small opening degree range of the variable nozzle blades in the circumferential direction.

[0084] (4) The variable nozzle device according to a further aspect is the variable nozzle device according to one of the above (1) to (3), wherein only the above aspect (3) has all the features relevant to the invention of the first embodiment, and the at least one through-hole is designed such that the first opening of the nozzle plate has a smaller opening area than the second opening of the nozzle plate.

[0085] With the variable nozzle device according to the present disclosure, the through-hole is designed such that the opening area of ​​the first opening is smaller than that of the second opening, and it is thus possible to increase the injection force (injection velocity) of the working fluid injected from the first opening, and it is possible to suppress a drift of the working fluid flowing through the turbine wheel in the small opening degree range of the variable nozzle blades even more effectively.

[0086] (5) According to one aspect, a variable nozzle device (the variable nozzle device 40 of the second embodiment) is a variable nozzle device for a variable geometry turbocharger (the turbocharger 1 of the second embodiment) and comprises: a nozzle holder (the nozzle holder 21 of the second embodiment); a nozzle plate (the nozzle plate 22 of the second embodiment) arranged facing the nozzle holder, the nozzle plate forming an annular nozzle flow channel (nozzle flow channel 4 of the second embodiment) between the nozzle plate and the nozzle holder; and a plurality of variable nozzle vanes (variable nozzle vanes 6 of the second embodiment) arranged at a predetermined interval in a circumferential direction of the nozzle flow channel such that they are individually rotatable about a pivot axis (pivot axis O2 of the second embodiment).The nozzle plate comprises a first surface (the first surface 33 of the second embodiment) facing the nozzle holder, and a sliding element (the sliding element 42 of the second embodiment) configured to move forward and retract from the first surface relative to the nozzle flow channel. The sliding element comprises a first side (the first side 42a of the second embodiment) facing the nozzle flow channel and a second side (the second side 42b of the second embodiment) opposite the first side, the sliding element being configured to move forward or retract in accordance with a pressure differential between a pressure applied to the first side and a pressure applied to the second side.

[0087] With the variable nozzle device according to the present disclosure, in the intermediate and large opening ranges of the variable nozzle blades, where the pressure difference between the first surface and the second surface is somewhat small, the first side of the sliding element is positioned close to the first surface (including the flush position) and held in this retracted state. Accordingly, in the intermediate and large opening ranges of the variable nozzle blades, the sliding element does not protrude beyond the first surface, and thus it is possible to prevent the sliding element from becoming a resistance that causes fluid energy loss and a deterioration of the turbine efficiency.

[0088] On the other hand, in the small opening range of the variable nozzle blades, the pressure differential is large, and the force pushing the second side of the sliding element increases relatively. Thus, the sliding element slides (moves forward), and the first side of the sliding element protrudes beyond the first side into the nozzle flow channel. Accordingly, in the small opening range of the variable nozzle blades, the working fluid flows along the first side of the protruding sliding element, and the flow of the working fluid is directed towards the hub. This suppresses the drift of the working fluid towards the casing side, which makes it possible to reduce uneven flow at the turbine rotor blade outlet and decrease mixing losses, thereby improving turbine efficiency.

[0089] Therefore, in the small opening range of the variable nozzle blades, where a considerable drift of the working fluid towards the outer surface is generated, it is possible to effectively suppress this drift. In the large opening range of the variable nozzle blades, where drift is not generated (a significant drift is not generated), the working fluid injected from the through-hole does not impede the flow of the working fluid, and thus it is possible to suppress the occurrence of fluid energy loss.

[0090] This makes it possible to reduce fluid energy loss of the working fluid in all areas, including the small opening degree range and the large opening degree range of the variable nozzle blades, and thereby improve the turbine efficiency even more effectively.

[0091] (6) The variable nozzle device according to another aspect is the variable nozzle device according to (5) above and the first side of the sliding element has a tapered surface (tapered surface 42c of the second embodiment) configured such that a distance to the nozzle holder decreases inwards in the radial direction.

[0092] With the variable nozzle device according to the present disclosure, it is possible in the small opening degree range of the variable nozzle blades to allow the working fluid to flow uniformly along the tapered surface of the first side of the protruding sliding element and to suppress the occurrence of a fluid energy loss due to a disturbance of the flow of the working fluid through the protruding sliding element.

[0093] (7) The variable nozzle device according to another aspect is the variable nozzle device according to (5) or (6) above and further comprises a spring element (preload element 45 of the second embodiment) with a first end side attached to the second side of the sliding element and a second end side attached to a stationary element (the stationary element 41 (turbine housing 5, nozzle plate 22) of the second embodiment).

[0094] With the variable nozzle device according to the present disclosure, the spring element is provided in such a way that a preload force is applied to the sliding element, and thus it is possible to protrude the sliding element with a protruding amount corresponding to the pressure difference and to enable the sliding element to retract suitably and automatically with the preload force of the spring element when the pressure difference decreases.

[0095] (8) The variable nozzle device according to another aspect is the variable nozzle device according to any of the above (5) to (7) and further comprises a stop (the stop of the second embodiment) which limits a feed-withdrawal amount of the sliding element.

[0096] With the variable nozzle device according to the present embodiment, it is possible to limit the forward and retraction amounts of the sliding element by providing the stop, i.e., the forward and retraction amounts of the sliding element, and thus it is possible to control the position of the sliding element appropriately.

[0097] (9) According to one aspect, a turbine (turbine 2 according to the first embodiment and the second embodiment) comprises: a rotating shaft; (rotating shaft 11 of the first embodiment and the second embodiment); a turbine wheel (turbine wheel 3 according to the first embodiment and the second embodiment) arranged at a first end side of the rotating shaft; and the variable nozzle device according to any one of the above (1) to (8).

[0098] With the turbine according to the present disclosure it is possible to provide a turbine which has the advantageous effects of the variable nozzle device according to any one of the above (1) to (8).

[0099] (10) According to one aspect, a turbocharger (turbocharger 1 of the first embodiment and of the second embodiment) comprises the turbine according to the above (9).

[0100] With the turbocharger according to the present disclosure it is possible to provide a turbocharger which has the advantageous effects of the turbine and the variable nozzle device according to (9) above. Reference symbol list 1 turbocharger 2 Turbine 3 Turbine wheel 4 nozzle flow channel 5 Turbine housings (stationary element) 6 Variable nozzle blade 11. Rotary shaft 12 Turbine hub 13 Turbine rotor blades 20 Variable nozzle device 21 Nozzle holder 22 Nozzle plate 30 Coat section 33 First surface 34 Nozzle plate body part 35 Second surface 36 Through hole 36a First opening 36b Second opening 40 Variable nozzle device 41 Stationary element 42 Sliding element 42a First page 42b Second page 42c Tapered surface 43 Through hole 44 Communication room 45 Preload element (spring element) 100 Typical variable nozzle devices G, g Working fluid (exhaust gas) O1 axis O2 swivel axis

Claims

[1] Variable nozzle device (20) for a variable geometry turbocharger (1), comprising: a nozzle holder (21); a nozzle plate (22) arranged such that it faces the nozzle holder (21), wherein the nozzle plate (22) forms a nozzle flow channel (4) with an annular shape between the nozzle plate (22) and the nozzle holder (21); and a plurality of variable nozzle vanes (6) arranged at a predetermined interval in a circumferential direction of the nozzle flow channel (4) such that they can be individually rotated about a pivot axis (O2), wherein the nozzle plate (22) comprises a first surface (33) facing the nozzle holder (21), a second surface (35) opposite the first surface (33), and at least one through-hole (36) formed through the first surface (33) and the second surface (35), wherein the at least one through-hole (36) has a first opening (36a) formed on the first surface (33) on an inside of the pivot axis (O2) with respect to a radial direction, and a second opening (36b) formed on the second surface (35) on an outside of the first opening with respect to the radial direction or at the same position as the first opening (36a) with respect to the radial direction, and wherein the at least one through-hole (36) comprises a single annular flow channel extending in the circumferential direction. [2] Variable nozzle device (20) according to claim 1, wherein the at least one through-hole (36) is designed such that the first opening (36a) of the nozzle plate (22) has a smaller opening area than the second opening (36b) of the nozzle plate (22). [3] Variable nozzle device (20) for a variable geometry turbocharger (1), comprising: a nozzle holder (21); a nozzle plate (22) arranged such that it faces the nozzle holder (21), wherein the nozzle plate (22) forms a nozzle flow channel (4) with an annular shape between the nozzle plate (22) and the nozzle holder (21); and a plurality of variable nozzle vanes (6) arranged at a predetermined interval in a circumferential direction of the nozzle flow channel (4) such that they can be individually rotated about a pivot axis (O2), wherein the nozzle plate (22) comprises a first surface (33) facing the nozzle holder (21) and a sliding element (42) configured to be able to move forward and backward from the first surface (33) with respect to the nozzle flow channel (4), and wherein the sliding element (42) comprises a first side (42a) facing the nozzle flow channel (4) and a second side (42b) opposite the first side (42a), wherein the sliding element (42) is configured to move forward or retract in accordance with a pressure difference between a pressure applied to the first side (42a) and a pressure applied to the second side (42b). [4] Variable nozzle device (20) according to claim 3, wherein the first side (42a) of the sliding element (42) has a tapered surface (42c) configured such that the distance to the nozzle holder (21) decreases inwards in the radial direction. [5] Variable nozzle device (20) according to claim 3 or 4, further comprising a spring element (45) with a first end side which is attached to the second side (42b) of the sliding element (42) and a second end side which is attached to a stationary element (41). [6] Variable nozzle device (20) according to one of claims 4 to 5, further comprising a stop that limits a feed retraction amount of the sliding element (42). [7] Turbine (2), comprising: a rotating shaft (11); a turbine wheel (3) arranged at a first end face of the rotating shaft (11); and the variable nozzle device (20) according to one of claims 1 to 6. [8] Turbocharger (1) comprising the turbine (2) according to claim 7.

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