Variable nozzle drive device and variable capacity turbine

Abstract

This variable nozzle drive device comprises: a first annular member; a plurality of vane shafts that support variable nozzle vanes; a plurality of levers each extending from the vane shafts to the outside in the radial direction of the first annular member; a second annular member configured to be rotatable with respect to the first annular member about the center axis of the first annular member and rotatably support the plurality of levers about the center axes of the vane shafts; and a full-opening stopper that can come into contact with one lever when the variable nozzle vanes are fully opened. When the variable nozzle vanes are fully opened, the action direction of the contact force between the full-opening stopper and the levers is directed further to the outside in the radial direction of the first annular member than the tangent line of a virtual circle passing through the contact point between the full-opening stopper and the levers and centered on the center axis of the first annular member.

Description

Variable nozzle drive system and variable geometry turbine

[0001] The present disclosure relates to a variable nozzle drive system and a variable geometry turbine.

[0002] A variable geometry turbocharger equipped with a variable geometry turbine is known as a turbocharger that supercharges the intake air of an internal combustion engine by utilizing the energy of exhaust gas from the engine (see, for example, Patent Document 1). The variable geometry turbine has a plurality of nozzle vanes arranged in the circumferential direction of the turbine wheel in an exhaust gas passage that sends exhaust gas from a scroll passage of the turbine to a turbine wheel, and the blade angle of these nozzle vanes can be changed externally by an actuator to adjust the flow path cross-sectional area of ​​the exhaust gas passage (the flow path between adjacent nozzle vanes). The variable geometry turbine adjusts the flow path cross-sectional area of ​​the exhaust gas passage to change the flow velocity and pressure of the exhaust gas introduced to the turbine wheel, thereby enhancing the supercharging effect.

[0003] Patent No. 5206307

[0004] The variable geometry turbine includes a mechanism for changing the blade angle of the nozzle vanes, which includes a nozzle mount, a drive ring rotatable relative to the nozzle mount, and multiple levers that operate in conjunction with the rotation of the drive ring to change the blade angle of the nozzle vanes. One of the multiple levers abuts against a full-open stopper (stopper pin) when the nozzle vanes are fully open, thereby limiting its movement in the opening direction. In this variable geometry turbine, when the variable nozzle vanes start to close from a fully open state, the lever abutting against the full-open stopper may get caught on the full-open stopper, which could result in an increase in drive torque.

[0005] In view of the above circumstances, at least one embodiment of the present disclosure aims to provide a variable nozzle drive device and a variable geometry turbine that can suppress the variable nozzle vane from getting caught on a full-open stopper when starting a closing operation from a fully open state.

[0006] a second annular member configured to be rotatable relative to the first annular member around the central axis of the first annular member, the second annular member configured to support the plurality of levers rotatably about the central axis of the vane shafts; and a full-open stopper that can abut against one of the plurality of levers when the variable nozzle vanes are fully open, wherein the direction of action of the contact force between the full-open stopper and the lever when the variable nozzle vanes are fully open is configured to be directed radially outward of the first annular member with respect to a tangent to an imaginary circle that is centered on the central axis of the first annular member and passes through a contact point between the full-open stopper and the lever.

[0007] A variable geometry turbine according to at least one embodiment of the present disclosure includes: the variable nozzle drive device; and the plurality of variable nozzle vanes.

[0008] According to at least one embodiment of the present disclosure, there is provided a variable nozzle drive device and a variable geometry turbine that can suppress the variable nozzle vanes from getting caught on the full-open stopper when starting a closing operation from a fully open state.

[0009] FIG. 1 is a schematic diagram of an internal combustion engine system equipped with a variable geometry turbocharger according to an embodiment of the present disclosure; FIG. 2 is a schematic cross-sectional view taken along the axis of a variable geometry turbine equipped in the variable geometry turbocharger according to an embodiment of the present disclosure; FIG. 3 is a schematic diagram of a variable nozzle drive device according to an embodiment of the present disclosure; FIG. 4 is a schematic diagram of a variable nozzle drive device according to a comparative example; FIG. 5 is a schematic diagram of a variable nozzle drive device according to an embodiment of the present disclosure; FIG. 6 is an explanatory diagram for explaining the shape of the abutment surface between a full-open stopper and a lever in a variable nozzle drive device according to an embodiment of the present disclosure; FIG. 7 is an explanatory diagram for explaining the shape of the abutment surface between a full-open stopper and a lever in a variable nozzle drive device according to an embodiment of the present disclosure;

[0010] Hereinafter, several embodiments of the present disclosure will be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of components described as embodiments or shown in the drawings are merely illustrative examples and are not intended to limit the scope of the present disclosure.

[0011] (Turbocharger) FIG. 1 is a schematic diagram of an internal combustion engine system 10 including a turbocharger (variable geometry turbocharger) 100 according to an embodiment of the present disclosure. A variable nozzle drive device 1 according to the present disclosure can be mounted on, for example, a turbine (variable geometry turbine) 102 included in a turbocharger (supercharger) 100 for automobiles, ships, or industrial applications (e.g., land-based power generation). In the following embodiments, the variable nozzle drive device 1 mounted on the turbocharger 100 will be described as an example, but the variable nozzle drive device 1 according to the present disclosure is not limited to being mounted on the turbocharger 100. Furthermore, the working fluid of the turbine 102 does not need to be limited to exhaust gas. That is, the turbine 102 may be configured as a standalone turbine 102 or may be configured in combination with a mechanism or device other than a centrifugal compressor 103 as long as it is capable of converting working fluid energy into mechanical power (e.g., rotational force). Furthermore, the use of the turbine 102 does not need to be limited.

[0012] 1 , a turbocharger 100 according to some embodiments is configured to compress a fluid (e.g., air) by being driven by the energy of exhaust gas discharged from an internal combustion engine (engine) 101. The turbocharger 100 includes a turbine 102 and a centrifugal compressor 103 configured to be driven by the turbine 102.

[0013] The turbine 102 includes a turbine wheel 104, a turbine housing (first housing) 105, and a bearing housing (second housing) 106 configured to rotatably accommodate the turbine wheel 104 between the turbine housing 105. The centrifugal compressor 103 includes an impeller 107 and a compressor housing 108 configured to rotatably accommodate the impeller 107.

[0014] 1 , the turbocharger 100 includes a rotating shaft 109 to which a turbine wheel 104 is connected on one side and an impeller 107 is connected on the other side, and a bearing 110 configured to rotatably support the rotating shaft 109 between the turbine wheel 104 and the impeller 107. A bearing housing 106 may be configured to accommodate the bearing 110. The bearing housing 106 is disposed between the turbine housing 105 and the compressor housing 108, and is connected to each of the turbine housing 105 and the compressor housing 108 via fastening members (not shown), such as bolts and nuts.

[0015] The turbine 102 of the turbocharger 100 is configured to rotate a turbine wheel 104 using the energy of exhaust gas discharged from the internal combustion engine 101. The impeller 107 is coaxially connected to the turbine wheel 104 via a rotating shaft 109, and is therefore driven to rotate about an axis LA of the turbine 102 in conjunction with the rotation of the turbine wheel 104. The centrifugal compressor 103 of the turbocharger 100 is configured to drive the impeller 107 to rotate about the axis LA, thereby drawing air (gas) into a compressor housing 108, compressing the air, and sending the compressed air to the internal combustion engine 101.

[0016] The compressed air sent from the centrifugal compressor 103 to the internal combustion engine 101 is used for combustion in the internal combustion engine 101. Exhaust gas generated by the combustion in the internal combustion engine 101 is sent from the internal combustion engine 101 to the turbine 102, causing a turbine wheel 104 to rotate.

[0017] 1, the impeller 107 is connected to the other side of the rotary shaft 109 and is therefore rotatable integrally with the rotary shaft 109 around the axis of the impeller 107. The impeller 107 is a centrifugal impeller configured to guide air introduced along the axial direction of the impeller 107 to the outside in the radial direction of the impeller 107. In the illustrated embodiment, the impeller 107 is an open-type impeller that does not include an annular member surrounding the outer periphery of the blades of the impeller 107.

[0018] (Compressor Housing) A gas introduction passage 181 and a scroll passage 182 are formed inside the compressor housing 108. In other words, the compressor housing 108 has the gas introduction passage 181 and the scroll passage 182.

[0019] The gas introduction passage 181 is a passage for taking in air (gas) from outside the compressor housing 108 (centrifugal compressor 103) and guiding the taken-in air to the impeller 107. The gas introduction passage 181 is provided on one side of the impeller 107 in the axial direction of the impeller 107, and extends along the axial direction of the impeller 107. By driving the impeller 107 to rotate, air is taken in from outside the compressor housing 108 into the gas introduction passage 181, and the taken-in air flows through the gas introduction passage 181 toward the impeller 107 and is guided to the impeller 107.

[0020] The scroll passage 182 is provided on the outer periphery of the impeller 107 and is a spiral passage extending along the circumferential direction of the impeller 107. Air that passes through the impeller 107 and is compressed by the impeller 107 is guided to the scroll passage 182. The compressed air that has passed through the scroll passage 182 is guided to the internal combustion engine 101.

[0021] 2 is a schematic cross-sectional view taken along the axis line LA of the variable geometry turbine 102 included in the variable geometry turbocharger 100 according to an embodiment of the present disclosure. Hereinafter, the direction in which the axis line LA of the turbine wheel 104 extends will be referred to as the axial direction of the turbine wheel 104 (turbine 102), the direction perpendicular to the axis line LA will be referred to as the radial direction of the turbine wheel 104 (turbine 102), and the circumferential direction around the axis line LA will be referred to as the circumferential direction of the turbine wheel 104 (turbine 102). Hereinafter, the side on which the turbine housing 105 is located relative to the bearing housing 106 in the axial direction of the turbine wheel 104 (turbine 102) (the right side, the other side in FIG. 2 ) will be defined as a first side, and the side on which the bearing housing 106 is located relative to the turbine housing 105, i.e., the side opposite to the first side (the left side, one side in FIG. 2 ), will be defined as a second side.

[0022] (Turbine Wheel) As shown in Fig. 2, the turbine wheel 104 includes a hub 141 having a substantially truncated cone shape and a plurality of turbine blades 142 provided on the outer peripheral surface of the hub 141. The plurality of turbine blades 142 are arranged at intervals from one another in the circumferential direction around the axis line LA. The hub 141 and the plurality of turbine blades 142 are provided so as to be rotatable integrally with the rotating shaft 109 around the axis line LA. The turbine wheel 104 is configured to guide exhaust gas introduced from the outside in the radial direction of the turbine wheel 104 to the tip side of the turbine wheel 104 along the axial direction of the turbine wheel 104. In the illustrated embodiment, the turbine wheel 104 is an open-type impeller that does not include an annular member surrounding the outer periphery of the turbine blades 142.

[0023] (Scroll passage, exhaust gas discharge passage) A scroll passage 151 for guiding exhaust gas discharged from the internal combustion engine 101 to the turbine wheel 104, and an exhaust gas discharge passage 152 for discharging exhaust gas that has passed through the turbine wheel 104 to the outside of the turbine housing 105 (turbine 102) are formed inside the turbine housing 105. In other words, the turbine housing 105 has the scroll passage 151 and the exhaust gas discharge passage 152. The scroll passage 151 is provided on the outer periphery of the turbine wheel 104 and consists of a spiral passage that extends along the circumferential direction of the turbine wheel 104. The exhaust gas discharge passage 152 extends from the turbine wheel 104 toward the first side along the axial direction of the turbine wheel 104.

[0024] By fastening the turbine housing 105 and the bearing housing 106 together, an internal space 153 is formed between the turbine housing 105 and the bearing housing 106, connecting the scroll passage 151 and the exhaust gas discharge passage 152. The turbine wheel 104 is housed in the internal space 153 so as to be rotatable with respect to the turbine housing 105 and the bearing housing 106. The turbine wheel 104 is provided on the inner peripheral side of the scroll passage 151. The internal space 153 includes a gas passage 153A that runs from the scroll passage 151 toward the turbine wheel 104. The gas passage 153A is part of the internal space 153. The gas passage 153A is formed between the scroll passage 151 and the turbine wheel 104 so as to surround the periphery (radial outer side) of the turbine wheel 104.

[0025] Exhaust gas discharged from the internal combustion engine 101 is guided to the turbine wheel 104 via the scroll passage 151, and drives the turbine wheel 104 to rotate. The exhaust gas that has driven the turbine wheel 104 to rotate is discharged to the outside of the turbine housing 105 (turbine 102) via the exhaust gas discharge passage 152.

[0026] (Variable nozzle drive device) Figure 3 is a schematic diagram of a variable nozzle drive device according to an embodiment of the present disclosure. As shown in Figure 2, the turbine 102 includes a plurality of variable nozzle vanes 2 and a variable nozzle drive device 1 for driving the plurality of variable nozzle vanes 2. The plurality of variable nozzle vanes 2 and the variable nozzle drive device 1 are each housed on the outer circumferential side of the turbine wheel 104 in the above-mentioned internal space 153. The variable nozzle drive device 1 is configured to be able to vary the flow path area of ​​gas supplied to the turbine wheel 104 by driving and rotating the plurality of variable nozzle vanes 2.

[0027] As shown in Fig. 2, the variable nozzle drive device 1 includes a first annular member (nozzle mount) 3, a plurality of vane shafts 4, a plurality of levers 5, a second annular member (drive ring) 6, and a full-open stopper 7. In the illustrated embodiment, the turbine 102 includes at least one (e.g., a plurality of) support members (nozzle supports) 11 as shown in Fig. 2.

[0028] (First Annular Member) The first annular member (nozzle mount) 3 includes an annular first plate portion 31 extending circumferentially around the turbine wheel 104 on the outer circumferential side of the turbine wheel 104. A first flow path surface 32 facing the gas flow path 153A is formed on a first side in the axial direction of the first plate portion 31, and a back surface 33 is formed on a second side in the axial direction of the first plate portion 31, i.e., the side opposite to the first flow path surface 32. In the illustrated embodiment, each of the first flow path surface 32 and the back surface 33 is an annular surface extending circumferentially around the turbine wheel 104. A central axis CA1 of the first annular member 3 extends along the extension direction of the axis line LA, i.e., the axial direction of the turbine wheel 104 (turbine 102).

[0029] In the illustrated embodiment, the turbine 102 includes an annular plate member (nozzle plate) 111 supported by the turbine housing 105. The annular plate member 111 is an annular body extending along the circumferential direction of the turbine wheel 104, and disposed on the second axial side of the turbine housing 105 and on the first axial side of the first annular member 3. An end face of the annular plate member 111 on the first axial side constitutes at least a portion (in the illustrated example, the entirety) of a second flow path surface 154 facing the gas flow path 153A. In other words, the annular plate member 111 has at least a portion of the second flow path surface 154 facing the gas flow path 153A.

[0030] The second flow path surface 154 is provided on the first axial side of the first flow path surface 32 and faces the first flow path surface 32 across the gas flow path 153A. In the embodiment shown in Fig. 2, the first flow path surface 32 and the second flow path surface 154 each comprise an annular surface extending along the circumferential direction of the turbine wheel 104. The gas flow path 153A is formed between the first flow path surface 32 and the second flow path surface 154. The exhaust gas introduced into the turbine 102 passes through the scroll flow path 151 and then the gas flow path 153A before being guided to the turbine wheel 104 and causing the turbine wheel 104 to rotate.

[0031] In the illustrated embodiment, the multiple support members (nozzle supports) 11 are arranged at intervals in the circumferential direction of the turbine wheel 104. Each of the multiple support members 11 is a rod-shaped member extending along the axial direction of the turbine 102. One longitudinal end of each of the multiple support members 11 is supported by the first flow path surface 32, and the other longitudinal end of each of the multiple support members 11 abuts against the second flow path surface 154. The multiple support members 11 maintain a predetermined axial gap between the first flow path surface 32 and the second flow path surface 154. In the illustrated embodiment, the second flow path surface 154 is separate from the turbine housing 105 and is formed on an annular plate member 111 supported by the turbine housing 105. However, part or all of the second flow path surface 154 may be formed on the turbine housing 105. The other longitudinal end of each of the multiple support members 11 may be supported by the second flow path surface 154 formed on the turbine housing 105.

[0032] The bearing housing 106 has an opposed surface 161 that faces the back surface 33 of the first plate portion 31, with a back space 153B (axial gap) sandwiched between the opposed surface 161 and the back surface 33. The back space 153B is part of the internal space 153, and is formed on the axially opposite side (second side) of the first plate portion 31 from the gas flow path 153A.

[0033] (Variable Nozzle Vane) Each of the multiple variable nozzle vanes 2 is disposed in the gas flow path 153A and supported by the first plate portion 31 of the first annular member 3 so as to be rotatable about its respective rotation axis RC. Each of the multiple variable nozzle vanes 2 includes a blade surface 21 facing the gas flow path 153A, a tip-side end face 22 formed at a first end of the blade surface 21 in the axial direction, and a hub-side end face 23 formed at a second end of the blade surface 21 in the axial direction. The multiple variable nozzle vanes 2 are disposed at intervals in the circumferential direction of the turbine wheel 104. The tip-side end face 22 of each of the multiple variable nozzle vanes 2 faces the second flow path surface 154 via an axial gap, and the hub-side end face 23 faces the first flow path surface 32 via an axial gap.

[0034] (Vane Shaft) Support holes 34, the same number as the variable nozzle vanes 2, are formed in the first plate portion 31 of the first annular member 3, penetrating from the first flow path surface 32 to the back surface 33. Each of the support holes 34 is formed at an interval relative to the other support holes 34 in the circumferential direction of the first annular member 3. The variable nozzle drive device 1 includes vane shafts 4, the same number as the variable nozzle vanes 2. As shown in FIG. 2 , the multiple vane shafts 4 are inserted into the support holes 34 penetrating the first annular member 3, and each supports one variable nozzle vane 2. One end of each of the multiple vane shafts 4 is connected to the hub-side end surface 23 of the variable nozzle vane 2 that it supports, and each extends toward the second side in the axial direction along the rotation axis RC of the variable nozzle vane 2 that it supports.

[0035] (Levers) The variable nozzle drive device 1 includes the same number of levers 5 as the vane shafts 4. The levers 5 are arranged in the rear-side space 153B, and each has a radially inner end (one end) 51 connected to the other end (second end) of the corresponding vane shaft 4. Each of the levers 5 extends from the other end of the vane shaft 4 to the outside in the radial direction of the first annular member 3, and has a radially outer end (other end) 52 connected to the second annular member 6. Each of the levers 5 is configured to be driven in conjunction with the rotation of the second annular member 6 and to change the blade angle of the variable nozzle vanes 2 connected via the vane shaft 4. Each of the levers 5 has a side 53 on the opening direction side in a width direction perpendicular to the longitudinal direction extending from one end 51 to the other end 52 of the lever 5, and a side 54 on the closing direction side in the width direction.

[0036] 3, in the illustrated embodiment, the radially outer end (other end) 52 of each lever 5 includes a fitting portion 52A that fits into a fitting portion 61 formed in the second annular member 6. The fitting portion 61 includes a groove portion 61A formed in the outer peripheral edge portion of the second annular member 6, and the fitting portion 52A is accommodated inside the groove portion 61A and fits loosely into the groove portion 61A.

[0037] (Second Annular Member) The second annular member (drive ring) 6 is disposed in the rear side space 153B, and is configured to be rotatable relative to the first annular member 3 about the central axis CA1 of the first annular member 3 by an external driving force. The second annular member 6 is configured to support each of the multiple levers 5 rotatably about the central axis CA2 of the vane shaft 4 corresponding to each lever 5. The central axis CA2 of each of the multiple vane shafts 4 extends along the rotation axis RC of the variable nozzle vane 2 supported by the vane shaft 4.

[0038] 2 , the turbine 102 further includes a drive mechanism (actuator) 8 configured to transmit a drive force to the second annular member 6 to rotate the second annular member 6 about the central axis CA1 of the first annular member 3, and a control device (controller) 9 configured to control the rotation of the second annular member 6 about the central axis CA1. The drive mechanism 8 includes an electric motor that generates a drive force, an air cylinder that transmits the drive force, and the like.

[0039] In the illustrated embodiment, as shown in Fig. 5, the drive mechanism 8 includes a control arm 81 having a drive-side fitting portion 82 that fits into the drive-side fitting portion 62 formed on the second annular member 6. The drive-side fitting portion 62 includes a drive-side groove 62A formed on the outer periphery of the second annular member 6, and the drive-side fitting portion 82 is housed inside the drive-side groove 62A and fits loosely into the drive-side groove 62A. In the embodiment shown in Fig. 5, the drive-side fitting portion 82 has an outer peripheral surface with a circular cross section that is capable of sliding in contact with the inner surface of the drive-side groove 62A.

[0040] By rotating the control arm 81 of the drive mechanism 8 around the central axis CA1 of the first annular member 3 in the opening direction, which is one side in the circumferential direction of the first annular member 3, the second annular member 6, which has a drive-side fitted portion 62 that fits into the drive-side fitting portion 82, rotates in the opening direction around the central axis CA1 of the first annular member 3 in conjunction with the rotation of the control arm 81. When the drive mechanism 8 rotates the second annular member 6 in the opening direction, the variable nozzle vanes 2, 2 that are adjacent in the circumferential direction rotate around their respective rotation axes RC in directions moving away from each other, and the flow path cross-sectional area of ​​the gas flow path 153A between the variable nozzle vanes 2, 2 increases.

[0041] By rotating the control arm 81 of the drive mechanism 8 around the central axis CA1 of the first annular member 3 to the other side in the circumferential direction of the first annular member 3, i.e., the closing direction side which is the opposite side to the opening direction side, the second annular member 6 having the drive-side fitted portion 62 that fits into the drive-side fitting portion 82 rotates in the closing direction around the central axis CA1 of the first annular member 3 in conjunction with the rotation of the control arm 81. When the drive mechanism 8 rotates the second annular member 6 in the closing direction, the variable nozzle vanes 2, 2 adjacent to each other in the circumferential direction rotate around their respective rotation axes RC in directions in which they approach each other, and the flow path cross-sectional area of ​​the gas flow path 153A between the variable nozzle vanes 2, 2 becomes smaller.

[0042] The variable nozzle drive device 1 transmits a driving force from outside the variable nozzle drive device 1 (drive mechanism unit 8) to the multiple variable nozzle vanes 2 via the second annular member 6, the multiple levers 5, and the multiple vane shafts 4, thereby rotating the multiple variable nozzle vanes 2 about their respective rotation axes RC and changing the blade angles of each variable nozzle vane 2. The variable nozzle drive device 1 can adjust the flow path cross-sectional area of ​​the gas flow path 153A by changing the respective blade angles of the multiple variable nozzle vanes 2. The turbine 102 can change the flow velocity and pressure of the exhaust gas guided to the turbine wheel 104 by increasing or decreasing the flow path cross-sectional area of ​​the gas flow path 153A using the variable nozzle drive device 1, thereby controlling the boost pressure of the turbine 102.

[0043] (Full-Open Stopper) The full-open stopper 7 is configured to be able to abut against one lever 5 (5A) of the multiple levers 5 when the variable nozzle vanes 2 are fully open. The lever 5A abuts against the full-open stopper 7 when the variable nozzle vanes 2 are fully open, and after the variable nozzle vanes 2 start closing from the fully open state, it moves away from the full-open stopper 7 in the closing direction. The full-open stopper 7 limits the rotation of the multiple variable nozzle vanes 2 when the variable nozzle vanes 2 are fully open so that adjacent variable nozzle vanes 2, 2 do not rotate excessively in a direction that moves them apart in the circumferential direction. In the embodiment shown in FIG. 3 , the full-open stopper 7 has one end connected to the back surface 33 of the first plate portion 31, and the other end extending along the axial direction of the first annular member 3 beyond the back surface 33 toward the second side in the axial direction. The other end of the full-open stopper 7 is provided in the back surface-side space 153B.

[0044] The first annular member 3 and the full-open stopper 7 do not move in conjunction with the second annular member 6 when the second annular member 6 is rotated around the central axis CA1 of the first annular member 3, i.e., they are configured to be immovable relative to the rotation of the second annular member 6.

[0045] (Variable nozzle drive device according to comparative example) Fig. 4 is a schematic diagram of a variable nozzle drive device 01 according to a comparative example. Fig. 5 is a schematic diagram of a variable nozzle drive device 1 according to an embodiment of the present disclosure. The variable nozzle drive device 01 according to the comparative example, like the variable nozzle drive device 1, includes a first annular member (nozzle mount) 3, a plurality of vane shafts 4, a plurality of levers 5, a second annular member (drive ring) 6, and a full-open stopper 7.

[0046] 4 and 5 , when viewed from one side (second side) in the axial direction of the first annular member 3, the contact point between the full-open stopper 7 and the lever 5 (5A) when the variable nozzle vane 2 is fully open is defined as PC, and the tangent line at the contact point PC to an imaginary circle VC that is centered on the central axis CA1 of the first annular member 3 and passes through the contact point PC is defined as TL. When viewed from one side (second side) in the axial direction of the first annular member 3, the acting direction of a contact force F1 between the full-open stopper 7 and the lever 5 (5A) when the variable nozzle vane 2 is fully open is defined as D1. The contact force F1 is the resultant force of a friction force F2 and a normal force F3 of the lever 5 (5A) against the full-open stopper 7. The acting direction D2 of the friction force F2 is a direction from the contact point PC toward the radially inward side of the first annular member 3 on a common tangent CTL between the full-open stopper 7 and the lever 5 (5A) when the variable nozzle vane 2 is fully open. The acting direction D3 of the normal force F3 is a direction from the contact point PC toward the closing direction side (the other side in the circumferential direction of the first annular member 3) on a common normal CN between the full-open stopper 7 and the lever 5 (5A) when the variable nozzle vane 2 is fully open.

[0047] 4 and 5, the angle between the contact force F1 and the normal force F3 is defined as the friction angle θ. Also, as shown in Fig. 5, the angle between the common tangent CTL and a line SL that extends from the central axis CA1 of the first annular member 3 radially outward of the first annular member 3 and passes through the contact point PC is defined as the contact angle α. The positive direction of the contact angle α is the opening direction described above.

[0048] 4, the variable nozzle drive device 01 according to the comparative example is configured so that when the variable nozzle vane 2 is fully open, the acting direction D1 of the contact force F1 between the full-open stopper 7 and the lever 5A is directed radially inward of the first annular member 3 relative to the tangent line TL of the imaginary circle VC. In this case, the condition that the contact angle α is smaller than the friction angle θ is satisfied.

[0049] In the embodiment shown in Fig. 4, the contact surface 71 that includes the contact point PC of the full-open stopper 7 and contacts the lever 5A is a curved surface, specifically a part of the outer circumferential surface of the full-open stopper 7 having a circular outer contour. The contact surface 55 that includes the contact point PC of the lever 5A and contacts the full-open stopper 7 is a flat surface, specifically a part of the end surface 531 of the side portion 53 on the opening direction side. In the embodiment shown in Fig. 4, the distance from the longitudinal center line CL of the lever 5A of the contact surface 55, which is a part of the end surface 531 of the side portion 53 on the opening direction side of the lever 5A, decreases toward the other end 52 of the lever 5A.

[0050] If the acting direction D1 of the contact force F1 is directed radially inward of the first annular member 3 with respect to the tangent line TL of the imaginary circle VC, the lever 5A will come into contact with the full-open stopper 7 and then be pushed radially inward by the full-open stopper 7 into the first annular member 3. When the closing operation of the variable nozzle vanes 2 is started from the fully open state of the variable nozzle vanes 2, the above-mentioned friction force F2 acts as a resistance torque in the closing operation of the variable nozzle vanes 2, and there is a risk of a jamming phenomenon occurring which will increase the drive torque of the control arm 81.

[0051] 5, the variable nozzle drive device 1 according to some embodiments is configured such that when the variable nozzle vane 2 is fully open, the acting direction D1 of the contact force F1 between the full-open stopper 7 and the lever 5A is directed radially outward of the first annular member 3 relative to the tangent line TL of the imaginary circle VC. In this case, the condition of contact angle α>friction angle θ is satisfied.

[0052] In the embodiment shown in FIG. 5 , the contact surface 71 that includes the contact point PC of the full-open stopper 7 and contacts the lever 5A is a curved surface, specifically a part of the outer peripheral surface of the full-open stopper 7, which has a circular contour. The contact surface 55 that includes the contact point PC of the lever 5A and contacts the full-open stopper 7 is a flat surface, specifically a part of the end surface 531 of the side portion 53 on the opening direction side. In the embodiment shown in FIG. 5 , the contact surface 55, which is part of the end surface 531 of the side portion 53 on the opening direction side of the lever 5A, is spaced a greater distance from the longitudinal center line CL of the lever 5A toward the other end 52 of the lever 5A. Note that the distance of the contact surface 55 from the longitudinal center line CL of the lever 5A may decrease a greater distance from the longitudinal center line CL of the lever 5A toward the other end 52 of the lever 5A, or the distance from the longitudinal center line CL of the lever 5A may be constant.

[0053] The variable nozzle drive device 1 is configured so that the acting direction D1 of the contact force F1 is directed radially outward of the first annular member 3 relative to the tangent line TL of the imaginary circle VC, thereby making it possible to prevent the lever 5 from coming into contact with the full-open stopper 7 and then being pushed radially inward of the first annular member 3 by the full-open stopper 7 when the variable nozzle vane 2 is fully open. This makes it possible to prevent the lever 5 from getting caught on the full-open stopper 7 when starting the closing operation from the fully open state of the variable nozzle vane 2, and to suppress an increase in drive torque when rotating the variable nozzle vane 2 in the closing direction from the fully open state.

[0054] 6 to 8 are explanatory diagrams illustrating the shape of the contact surface between the full-open stopper 7 and the lever 5A in a variable nozzle drive device 1 according to an embodiment of the present disclosure. In the variable nozzle drive device 1 according to some embodiments, as shown in FIGS. 5 to 8, the lever 5A (5) that contacts the above-mentioned full-open stopper 7 has a convex portion 56 that protrudes toward the opening direction side where the full-open stopper 7 is located. The variable nozzle drive device 1 is configured so that a contact point PC is present on the convex portion 56. In the embodiment shown in FIG. 5, the convex portion 56 that includes at least a part of the contact surface 55 is provided on the side portion 53 of the lever 5A on the opening direction side.

[0055] With the simple structure of providing the lever 5 with the protrusion 56 including the contact point PC, it is possible to configure the direction of action D1 of the contact force F1 to be directed radially outward of the first annular member 3 relative to the tangent line TL of the imaginary circle VC. Note that in some other embodiments, the lever 5 may be configured without providing the protrusion 56.

[0056] As shown in Fig. 5 , the variable nozzle drive device 1 according to some embodiments is configured so that the contact point PC is located radially inward of the apex 561 of the convex portion 56 described above. The apex 561 of the convex portion 56 is the portion of the convex portion 56 that protrudes most toward the opening direction in the width direction perpendicular to the longitudinal direction extending from one end 51 to the other end 52 of the lever 5A. In the embodiment shown in Fig. 5 , the distance from the longitudinal center line CL of the lever 5A to the radially inner side of the apex 561 of the convex portion 56 decreases with increasing distance from the apex 561.

[0057] By configuring the contact point PC to be located radially inward of the vertex 561 of the convex portion 56 of the lever 5, the direction of action D1 of the contact force F1 can be configured to be directed radially outward of the first annular member 3 relative to the tangent TL of the virtual circle VC.

[0058] In the variable nozzle drive device 1 according to some embodiments, as shown in FIG. 6 , the contact surface 71 of the fully-open stopper 7 that contacts the lever 5 is a curved surface 71A. The contact surface 55 of the lever 5 that contacts the fully-open stopper 7 is a flat surface 55A. In the embodiment shown in FIG. 6 , when viewed from one side (second side) in the axial direction of the first annular member 3, the curved contact surface 71A is part of the outer circumferential surface of the fully-open stopper 7 that has a circular outline. When viewed from one side (second side) in the axial direction of the first annular member 3, the flat contact surface 55A is formed in a linear shape extending from the inner side to the outer side in the radial direction of the first annular member 3. Note that, as shown in FIG. 5 , the flat contact surface 55A may be part of a protrusion 56 provided on an end surface 531 of the side portion 53 on the opening direction side of the lever 5A.

[0059] When the variable nozzle vane 2 is fully open, the curved abutment surface 71A of the full-open stopper 7 abuts against the flat abutment surface 55A of the lever 5, making it easy for the lever 5 to slide against the full-open stopper 7, thereby suppressing the increase in driving torque when rotating the variable nozzle vane 2 from the fully open state toward the closing direction.

[0060] In the variable nozzle drive device 1 according to some embodiments, as shown in Fig. 7 , the contact surface 71 of the fully-open stopper 7 that contacts the lever 5 is a flat surface 71B. The contact surface 55 of the lever 5 that contacts the fully-open stopper 7 is a curved surface 55B. In the embodiment shown in Fig. 7 , when viewed from one side (second side) in the axial direction of the first annular member 3, the flat contact surface 71B is formed in a linear shape extending from the inside to the outside in the radial direction of the first annular member 3. When viewed from one side (second side) in the axial direction of the first annular member 3, the curved contact surface 55B is formed in an arc shape having a predetermined curvature that protrudes toward the opening direction.

[0061] When the variable nozzle vane 2 is fully open, the flat abutment surface 71B of the full-open stopper 7 abuts against the curved abutment surface 55B of the lever 5, making it easy for the lever 5 to slide against the full-open stopper 7, thereby suppressing the increase in driving torque when rotating the variable nozzle vane 2 from the fully open state toward the closing direction.

[0062] In the variable nozzle drive device 1 according to some embodiments, as shown in Fig. 8 , the contact surface 71 of the fully-open stopper 7 that contacts the lever 5 is a curved surface 71A. The contact surface 55 of the lever 5 that contacts the fully-open stopper 7 is a curved surface 55B. In the embodiment shown in Fig. 8 , when viewed from one side (second side) in the axial direction of the first annular member 3, the curved contact surface 71A is part of the outer circumferential surface of the fully-open stopper 7 that has a circular outer contour. When viewed from one side (second side) in the axial direction of the first annular member 3, the curved contact surface 55B is formed in a convex arc shape with a predetermined curvature that protrudes toward the opening direction.

[0063] When the variable nozzle vane 2 is fully open, the curved abutment surface 71A of the full-open stopper 7 abuts against the curved abutment surface 55B of the lever 5, making it easy for the lever 5 to slide against the full-open stopper 7, thereby suppressing the increase in driving torque when rotating the variable nozzle vane 2 from the fully open state toward the closing direction.

[0064] 2 and 3, a variable geometry turbine 102 according to some embodiments includes the above-described variable nozzle drive device 1 and the above-described plurality of variable nozzle vanes 2. In this case, the variable nozzle drive device 1 can suppress an increase in drive torque when rotating the variable nozzle vanes 2 from a fully open state toward the closing direction.

[0065] In this specification, expressions expressing relative or absolute arrangements, such as "in a certain direction," "along a certain direction," "parallel," "orthogonal," "center," "concentric," or "coaxial," not only strictly express such arrangements, but also express a state in which there is a relative displacement with a tolerance or an angle or distance to the extent that the same function is obtained. For example, expressions expressing that things are in an equal state, such as "identical," "equal," and "homogeneous," not only express a state in which there is a strict equivalence, but also express a state in which there is a tolerance or a difference to the extent that the same function is obtained. Furthermore, in this specification, expressions expressing shapes such as a rectangular shape or a cylindrical shape not only express shapes such as a rectangular shape or a cylindrical shape in the strict geometric sense, but also express shapes including concave and convex portions, chamfered portions, etc., to the extent that the same effect is obtained. Furthermore, in this specification, the expressions "comprise," "include," or "have" a component are not exclusive expressions that exclude the presence of other components.

[0066] The present disclosure is not limited to the above-described embodiments, but also includes modifications to the above-described embodiments and appropriate combinations of these modifications.

[0067] The contents of the above-described embodiments can be understood, for example, as follows.

[0068] 1) A variable nozzle drive device (1) according to at least one embodiment of the present disclosure is a variable nozzle drive device (1) for driving a plurality of variable nozzle vanes (2) of a variable geometry turbine (102), comprising: a first annular member (3); a plurality of vane shafts (4) inserted into support holes (34) penetrating the first annular member (3) and each supporting one of the variable nozzle vanes (2); a plurality of levers (5) extending from the vane shafts (4) radially outward of the first annular member (3); a second annular member (6) configured to be rotatable relative to the first annular member (3) around a central axis (CA1) of the first annular member (3), the second annular member (6) configured to support the plurality of levers (5) rotatably around a central axis (CA2) of the vane shaft (4); and a full-open stopper (7) capable of contacting one of the plurality of levers (5) when the variable nozzle vanes (2) are fully open. When the variable nozzle vane (2) is fully open, the acting direction (D1) of the contact force (F1) between the full-open stopper (7) and the lever (5) is configured to be directed radially outward of the first annular member (3) relative to a tangent (TL) to an imaginary circle (VC) that is centered on the central axis (CA1) of the first annular member (3) and passes through a contact point (PC) between the full-open stopper (7) and the lever (5).

[0069] According to the configuration 1), the variable nozzle drive device (1) is configured so that the acting direction (D1) of the contact force (F1) is directed radially outward of the first annular member (3) relative to the tangent (TL) to the imaginary circle (VC), thereby making it possible to prevent the lever (5) from coming into contact with the full-open stopper (7) and then being pushed radially inward of the first annular member (3) by the full-open stopper (7) when the variable nozzle vane (2) is fully open. This makes it possible to prevent the lever (5) from getting caught on the full-open stopper (7) when starting a closing operation from the fully open state of the variable nozzle vane (2), and to suppress an increase in drive torque when rotating the variable nozzle vane (2) in the closing direction from the fully open state.

[0070] 2) In some embodiments, in the variable nozzle drive device (1) described in 1) above, the lever (5) that abuts against the full-open stopper (7) has a convex portion (56) that protrudes toward the opening direction where the full-open stopper (7) is located, and the variable nozzle drive device (1) is configured so that the contact point (PC) is located on the convex portion (56).

[0071] According to the above configuration 2), with a simple structure in which a convex portion (56) including a contact point (PC) is provided on the lever (5), the acting direction (D1) of the contact force (F1) can be configured to be directed radially outward of the first annular member (3) relative to the tangent (TL) of the virtual circle (VC).

[0072] 3) In some embodiments, the variable nozzle drive device (1) described in 2) above is configured such that the contact point (PC) of the convex portion (56) is located radially inward of the apex (561) of the convex portion (56).

[0073] According to the configuration of 3) above, by configuring the contact point (PC) to be located radially inward of the apex (561) of the convex portion (56) of the lever (5), the acting direction (D1) of the contact force (F1) can be configured to be directed radially outward of the first annular member (3) relative to the tangent (TL) of the virtual circle (VC).

[0074] 4) In some embodiments, in the variable nozzle drive device (1) described in any one of 1) to 3) above, the abutment surface (71) of the full-open stopper (7) that abuts against the lever (5) is a curved surface (71A), and the abutment surface (55) of the lever (5) that abuts against the full-open stopper (7) is a flat surface (55A).

[0075] According to the configuration of 4) above, when the variable nozzle vane (2) is fully open, the curved abutment surface (71A) of the full-open stopper (7) abuts against the flat abutment surface (55A) of the lever (5), making it easy for the lever (5) to slide relative to the full-open stopper (7), thereby suppressing an increase in drive torque when rotating the variable nozzle vane (2) from the fully open state toward the closing direction.

[0076] 5) In some embodiments, in the variable nozzle drive device (1) described in any one of 1) to 3) above, the abutment surface (71) of the full-open stopper (7) that abuts against the lever (5) is a flat surface (71B), and the abutment surface (55) of the lever (5) that abuts against the full-open stopper (7) is a curved surface (55B).

[0077] According to the configuration of 5) above, when the variable nozzle vane (2) is fully open, the flat abutment surface (71B) of the full-open stopper (7) abuts against the curved abutment surface (55B) of the lever (5), making it easy for the lever (5) to slide relative to the full-open stopper (7), thereby suppressing an increase in drive torque when rotating the variable nozzle vane (2) from the fully open state toward the closing direction.

[0078] 6) In some embodiments, in the variable nozzle drive device (1) described in any one of 1) to 3) above, the abutment surface (71) of the full-open stopper (7) that abuts against the lever (5) is a curved surface (71A), and the abutment surface (55) of the lever (5) that abuts against the full-open stopper (7) is a curved surface (55B).

[0079] According to the configuration of 6) above, when the variable nozzle vane (2) is fully open, the curved abutment surface (71A) of the full-open stopper (7) abuts against the curved abutment surface (55B) of the lever (5), making it easy for the lever (5) to slide relative to the full-open stopper (7), thereby suppressing an increase in drive torque when rotating the variable nozzle vane (2) from the fully open state toward the closing direction.

[0080] 7) A variable geometry turbine (102) according to at least one embodiment of the present disclosure comprises: the variable nozzle drive device (1) described in any one of 1) to 6) above; and the plurality of variable nozzle vanes (2).

[0081] According to the configuration of 7) above, it is possible to suppress an increase in the drive torque when rotating the variable nozzle vane (2) from the fully open state to the closing direction.

[0082] REFERENCE SIGNS LIST 1 variable nozzle drive device 2 variable nozzle vane 3 first annular member 4 vane shaft 5 lever 6 second annular member 7 full-open stopper 8 drive mechanism 9 control device 10 internal combustion engine system 11 support member 51 one end 52 other end 53 side portion on opening direction side 54 side portion on closing direction side 55, 71 abutment surface 56 convex portion 100 turbocharger 101 internal combustion engine 102 turbine 103 centrifugal compressor 104 turbine wheel 105 turbine housing 106 bearing housing 107 impeller 108 compressor housing 109 rotating shaft 110 bearing

Claims

1. A variable nozzle drive device for driving a plurality of variable nozzle vanes of a variable geometry turbine, comprising: a first annular member; a plurality of vane shafts each inserted into support holes that pass through the first annular member and each supporting one of the variable nozzle vanes; a plurality of levers each extending from the vane shaft outward in the radial direction of the first annular member; a second annular member configured to be rotatable relative to the first annular member around the central axis of the first annular member, the second annular member configured to support the plurality of levers rotatably about the central axis of the vane shaft; and a full-open stopper that can abut against one of the plurality of levers when the variable nozzle vanes are fully open, wherein the variable nozzle drive device is configured such that when the variable nozzle vanes are fully open, the direction of action of the contact force between the full-open stopper and the lever is directed radially outward of the first annular member relative to a tangent to an imaginary circle that is centered on the central axis of the first annular member and passes through the contact point between the full-open stopper and the lever.

2. The variable nozzle drive device according to claim 1, wherein the lever that contacts the full-open stopper has a convex portion that protrudes toward the opening direction where the full-open stopper is located, and the variable nozzle drive device is configured so that the contact point is located on the convex portion.

3. The variable nozzle drive device according to claim 2, wherein the variable nozzle drive device is configured so that the contact point is located radially inward of the apex of the convex portion.

4. A variable nozzle drive device according to any one of claims 1 to 3, wherein the contact surface of the full-open stopper that contacts the lever is curved, and the contact surface of the lever that contacts the full-open stopper is flat.

5. A variable nozzle drive device according to any one of claims 1 to 3, wherein the contact surface of the full-open stopper that contacts the lever is flat, and the contact surface of the lever that contacts the full-open stopper is curved.

6. The variable nozzle drive device according to any one of claims 1 to 3, wherein the contact surface of the full-open stopper that contacts the lever is a curved surface, and the contact surface of the lever that contacts the full-open stopper is a curved surface.

7. A variable geometry turbine comprising: the variable nozzle drive device according to any one of claims 1 to 3; and a plurality of variable nozzle vanes.

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