JP6433279B2 - Turbocharger impeller - Google Patents

Description

  The present invention relates to a centrifugal impeller fixed to a rotating shaft of a supercharger using a fixture.

  In some superchargers, a centrifugal impeller is fixed to a supercharger rotating shaft using a fixture (for example, Patent Document 1). Such a supercharger includes an impeller body in which blades are formed, a front end portion that protrudes from the impeller body in one axial direction and contacts the fixture, and a supercharger that projects from the impeller body to the other axial direction. And a rear end portion in contact with the flange portion of the shaft, and the outer diameter is the largest on the rear end side of the impeller body.

JP2013-224614A

  In the supercharger as described above, when the supercharger rotating shaft is rotated at a high speed in order to improve the output, the outer peripheral portion of the rear end side of the impeller body having the largest outer diameter is directed radially outward by centrifugal force. Receives a large tensile force. Since there is a concern that such a tensile force may remain as a residual stress, there is a limit to speeding up rotation particularly in a small impeller.

  An object of this invention is to provide the impeller of the supercharger which can be rotated at high speed.

  In order to achieve the above object, an impeller of a supercharger according to the present invention is a centrifugal impeller that is fixed to a rotating shaft of a supercharger inserted through a through hole using a fixing tool, and has blades formed therein. An impeller body that protrudes from the impeller body in one axial direction and contacts the fixture, and a rear end that protrudes from the impeller body in the other axial direction and contacts the flange portion of the rotating shaft. The outer diameter of the end surface of the rear end portion is set larger than the outer diameter of the end surface of the front end portion.

  According to this configuration, since the outer diameter of the end surface of the rear end portion is set to be larger than the outer diameter of the end surface of the front end portion, the strength against the tensile force toward the radially outer side of the rear end portion is improved. Thus, when the rotating shaft of the turbocharger is rotated at a high speed, even if the outer peripheral portion of the rear end side of the impeller body having the largest outer diameter receives a large tensile force toward the radially outer side due to centrifugal force, It is possible to suppress the rear end side of the impeller body from being affected by such a tensile force. Therefore, the impeller can be rotated at high speed.

  In this invention, it is preferable that the outer diameter of the end surface of the said rear-end part is smaller than the outer diameter of the front-end part of the said impeller main body. According to this configuration, it is possible to prevent the rear end portion from becoming large, suppress an increase in centrifugal force, and reduce the weight of the impeller.

  In the present invention, the outer diameter dimension of the rear end portion gradually increases from the end face toward the impeller body, and the outer diameter dimension of the boundary portion between the rear end portion and the impeller body is the same as that of the impeller body. It is preferably larger than ½ of the outer dimension of the base end and smaller than the outer dimension of the tip of the impeller body. According to this configuration, it is possible to reduce the centrifugal force by suppressing an increase in the outer peripheral edge portion on the rear end side of the impeller while suppressing the stress concentration in the boundary portion and increasing the rigidity of the rear end portion.

  In this invention, it is preferable that the protrusion dimension from the said impeller main body of the said rear end part is set more than the difference of the radius of a through-hole, and the radius of the end surface of the said front end part. According to this configuration, the protruding amount of the rear end portion is increased, and it is possible to suppress a decrease in rigidity on the rear end side of the impeller body.

  In this invention, it is preferable that the said rear-end part is facing the seal member arrange | positioned on the radial direction outer side of the said flange part to an axial direction. According to this configuration, since the axial gap between the seal member and the impeller is reduced, it is possible to prevent the lubricating liquid from leaking.

  According to the impeller of the supercharger of the present invention, since the outer diameter Do of the end surface of the rear end portion is set larger than the outer diameter Di of the end surface of the front end portion, the tensile force toward the radially outer side of the rear end portion The strength against is improved. Thus, when the rotating shaft of the turbocharger is rotated at a high speed, even if the outer peripheral portion of the rear end side of the impeller body having the largest outer diameter receives a large tensile force toward the radially outer side due to centrifugal force, It is possible to suppress the rear end side of the impeller body from being affected by such a tensile force. Therefore, the impeller can be rotated at high speed.

1 is a side view showing a motorcycle including an impeller of a supercharger according to a first embodiment of the present invention. It is a horizontal sectional view showing the turbocharger. It is a side view which shows the impeller. It is the front view which looked at the impeller from the suction side. It is a perspective view which shows the impeller. It is a simplified diagram showing the positional relationship between the main blade and splitter blade of the impeller. It is a top view which shows the cutting direction of the blade | wing of the impeller.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. In the present specification, “left side” and “right side” refer to the left and right sides as viewed from the driver who gets on the vehicle.

  FIG. 1 is a side view of a motorcycle equipped with an engine supercharger according to a first embodiment of the present invention. A body frame FR of the motorcycle has a main frame 1 that forms a front half and a rear frame 2 that forms a rear half. A head pipe 4 is provided at the front end of the main frame 1, and a front fork 8 is pivotally supported on the head pipe 4 via a steering shaft (not shown). A front wheel 10 is attached to the lower end portion of the front fork 8, and a steering handle 6 is fixed to the upper end portion of the front fork 8.

  On the other hand, a swing arm bracket 9 is provided at the rear end portion of the main frame 1 which is the lower center of the vehicle body frame FR. A swing arm 12 is pivotally supported around a pivot shaft 16 attached to the swing arm bracket 9 so as to be swingable up and down. A rear wheel 14 is rotatably supported at the rear end of the swing arm 12. An engine E is attached to the front side of the swing arm bracket 9 at the center lower part of the body frame FR. The engine E drives the rear wheel 14 via the drive chain 11.

  The engine E includes a crankshaft 26 having a rotating shaft extending in the left-right direction (vehicle width direction), a crankcase 28 that supports the crankshaft 26, a cylinder block 30 that protrudes upward from the front upper surface of the crankcase 28, An upper cylinder head 32 and an oil pan 34 provided below the crankcase 28 are provided. In the present embodiment, the crankcase 28 and the cylinder block 30 are integrally formed by molding, and the rear portion of the crankcase 28 also serves as a transmission case. The engine E is a four-cylinder four-cycle engine, but is not limited to this.

  Four exhaust pipes 36 are connected to the front surface of the cylinder head 32. These four exhaust pipes 36 are gathered below the engine E and connected to an exhaust muffler 38 disposed on the right side of the rear wheel 14.

  A fuel tank 15 is disposed above the main frame 1, and a driver's seat 18 and a passenger seat 20 are supported on the rear frame 2. A resin cowling 22 is mounted on the front of the vehicle body. The cowling 22 covers the front of the head pipe 4. An air intake 24 is formed in the cowling 22. The air intake 24 is located at the front end of the cowling 22 and takes in intake air from the outside to the engine E. A transparent windshield 23 is mounted on the cowling 22.

  An intake duct 50 is disposed on the left side of the vehicle body frame FR. The intake duct 50 is supported by the head pipe 4 in such a manner that the front end opening 50 a faces the air intake port 24 of the cowling 22. The air introduced from the front end opening 50a of the intake duct 50 is pressurized by the ram effect. The intake duct 50 passes from the front of the engine E to the left outer side of the cylinder block 30 and the cylinder head 32, and guides the running wind A as intake air I to the engine E.

  An air cleaner 40 and a supercharger 42 for purifying outside air are arranged in the vehicle width direction on the upper surface of the crankcase 28 behind the cylinder block 30. The downstream end 50 b of the intake duct 50 is connected to the suction port 46 of the supercharger 42 via the air cleaner 40. The supercharger 42 is detachably attached to the engine E, pressurizes clean air from the air cleaner 40 and supplies the pressurized air to the engine E.

  An intake chamber 52 is disposed between the discharge port 48 of the supercharger 42 and the intake port 54 of the engine E, and the discharge port 48 of the supercharger 42 and the intake chamber 52 are directly connected. The intake chamber 52 stores the high-pressure intake air I supplied from the discharge port 48 of the supercharger 42. A throttle body 44 is disposed between the intake chamber 52 and the intake port 54. The intake chamber 52 is located above the supercharger 42 and the throttle body 44. The fuel tank 15 is disposed above the intake chamber 52 and the throttle body 44.

  The supercharger 42 is accommodated in the width of the crankcase 28 in the left-right direction above the rear portion of the crankcase 28. In other words, the supercharger 42 is located behind the cylinder block 30 and the cylinder head 32 and above the rear part of the crankcase 28 and below the intake chamber 54 than the both outer ends of the width of the crankcase 28. It is arranged in a limited space inside in the width direction.

  As shown in FIG. 2, the supercharger 42 is a centrifugal type, and includes an impeller 60 fixed to one end portion (left end portion) 44 a of a supercharger rotating shaft 44 extending in the vehicle width direction (left-right direction), and the impeller. An impeller housing 63 covering 60, a supercharger case 66 that rotatably supports the supercharger rotating shaft 44, and a planetary gear that accelerates the rotation of the crankshaft 26 of the engine E and transmits it to the supercharger rotating shaft 44. And a gear device 64. That is, the impeller 60 is fixed to one end 44a of the supercharger rotating shaft 44, and the planetary gear device 64 is connected to the other end 44b.

  As a result of the speed increase, the maximum number of rotations of the supercharger rotating shaft 44 is 100,000 revolutions per minute, or approximately 140,000 revolutions in this embodiment. In the present embodiment, the intake air is compressed at a high temperature by the supercharger, and the intake air temperature at the supercharger outlet reaches about 100 ° C. Furthermore, motorcycles can accelerate and decelerate rapidly. Further, since the maximum permissible rotational speed may be reached in 0.5 seconds from idling operation with no engine load, the centrifugal force applied to the impeller is very large. Details of the impeller 60 will be described later.

  The supercharger 42 is driven by the power of the engine E. Specifically, the rotational force of the crankshaft 26 (FIG. 1) is transmitted to the input shaft 65 of the planetary gear unit 64 connected to the supercharger rotating shaft 44 via a chain 74 which is a kind of power transmission member. Has been. More specifically, a sprocket 62 is provided at the right end of the input shaft 65, and a chain 74 is stretched around a gear 62 a of the sprocket 62. That is, the suction port 46 is provided on one side (left side) in the axial direction of the supercharger rotating shaft 44, and the chain (power transmission mechanism) 74 is provided on the other side (right side).

  The supercharger case 66 includes a right input case portion 56 that houses the input shaft 65 and the sprocket 62, and a left gear case portion 58 that houses the planetary gear unit 64. The input case portion 56, the gear case portion 58, and the like. Are connected using bolts (not shown). Further, the impeller housing 63 is coupled to the gear case portion 58 using bolts (not shown).

  The input shaft 65 is a hollow shaft and is rotatably supported by the input case portion 56 via a pair of bearings 72. Spline teeth 67 are formed on the outer peripheral surface of the right end portion 65 b of the input shaft 65. A sprocket 62 is spline-fitted to the spline teeth 67 and connected to the input shaft 65. An internal thread portion is formed on the inner peripheral surface of the right end portion 65b of the input shaft 65, and the sprocket 62 is inserted into the internal shaft surface of the input shaft 65 via a washer 70 by a head of a bolt 68 screwed into the internal thread portion. It is fixed to the right end 65b.

  A right end 44 b that is a base end of the supercharger rotating shaft 44 is connected to a left end 65 a of the input shaft 65 via a planetary gear device 64. The left end portion 65a of the input shaft 65 includes a flange-shaped flange portion 65a. The supercharger rotating shaft 44 is rotatably supported by the gear case portion 58 via a bearing 69. Two bearings 69 are arranged in the axial direction, and these two bearings 69 and 69 are accommodated in a bearing housing 76. External teeth 78 are formed on the right end 44 b of the supercharger rotating shaft 44.

  The planetary gear device 64 is disposed between the input shaft 65 and the supercharger rotating shaft 44 and is supported by the gear case portion 58. A plurality of planetary gears 80 are gear-coupled to the external teeth 78 of the right end 44b of the supercharger rotating shaft 44 side by side in the circumferential direction. That is, the external teeth 78 of the supercharger rotating shaft 44 function as the sun gear of the planetary gear unit 64. The planetary gear 80 is formed with external teeth 81 that mesh with the sun gear (external teeth) 78. For example, three planetary gears 80 are arranged apart from each other in the circumferential direction.

  The planetary gear 80 is gear-connected to a large-diameter internal gear (ring gear) 82 on the radially outer side. Each planetary gear 80 is rotatably supported on the carrier shaft 86 by a bearing 84 attached to the gear case portion 58. That is, the carrier shaft 86 constitutes a support shaft for the planetary gear 80. In this embodiment, needle rollers are used as the bearings 84.

  The carrier shaft 86 is fixed to a disk-shaped fixing member 88, and the fixing member 88 is fixed to the gear case portion 58 with bolts 90. That is, the carrier shaft 86 is fixed and the planetary gear 80 does not revolve. An input gear 92 provided at the left end portion of the input shaft 65 is gear-connected to the internal gear 82. The input gear 92 is an external gear having external teeth formed on the outer periphery of the disc.

  Thus, the internal gear 82 is gear-connected so as to rotate integrally with the input shaft 65 in the same rotational direction, the carrier shaft 86 is fixed, and the planetary gear 80 rotates in the same rotational direction as the internal gear 82. The sun gear (external gear) 78 rotates in the direction opposite to the planetary gear 80.

  Inside the supercharger case 66, a supercharger lubricating liquid passage 94 is formed that introduces the lubricating liquid OL from the outside of the supercharger 42 and guides the lubricating liquid OL to the bearing housing 76. The supercharger lubricating liquid passage 94 is formed simultaneously with the supercharger case 66 by molding. In this embodiment, oil is used as the lubricating liquid OL.

  An oil layer 96 is formed between the supercharger case 66 and the bearing housing 76, and a supercharger lubricating fluid passage 94 is connected to the oil layer 96. Thus, the bearing housing 76 is supported by the supercharger case 66 through the oil layer 96 so as to be movable in the radial direction. The oil layer 96 has a function of relaxing the swing of the supercharger rotating shaft 44. A part of the lubricating liquid OL of the oil layer 96 is supplied to the bearing 69 which is a lubricated part. The oil that has passed through the right bearing 69 is supplied to the external teeth 78 and lubricates the meshed portions of the external teeth 78 and the external teeth 81 of the planetary gear 80.

  An oil seal assembly SA is disposed between the bearing 69 and the impeller 60 in the supercharger rotating shaft 44. The oil seal assembly SA prevents oil leakage from the oil layer 96 and the cylindrical collar 75 that is fitted to the turbocharger rotating shaft 44 and is clamped between the impeller 60 and the inner ring of the left bearing 69. And a seal holder 79 that holds the seal member 77.

  The collar 75 is held between the impeller 50 and the inner ring 69a of the bearing assembly BA and is fixed to the supercharger rotating shaft 44. The collar 75 constitutes a flange portion of the supercharger rotating shaft 44. Instead of the collar 75, a flange portion may be formed integrally with the turbocharger rotating shaft 44. The oil seal 77 blocks the radial gap between the collar 75 and the seal holder 79 and prevents oil from flowing to the impeller 60 side. The seal holder 79 holds the oil seal 77 and is supported on the supercharger case 66 by bolts (not shown).

  A male screw portion 95 is formed on the outer peripheral surface of the left end portion (tip portion) of the supercharger rotating shaft 44, and a fixing tool 85 made of a fastening member such as a nut is attached to the male screw portion 95 by screwing. Yes. The fixing tool 85 presses the impeller 60 against the other axial side of the turbocharger rotating shaft 44 (the right side of the motorcycle) to contact the collar 75 of the turbocharger rotating shaft 44, thereby 44.

  The impeller 60 is made of a material having a low stress drop at a high temperature, for example, an aluminum alloy, and includes a hub 73 and blades disposed on the outer periphery thereof. As shown in FIG. 3, the impeller 60 includes an impeller body 100 in which blades are formed, a front end portion 102 that protrudes from the impeller body 100 in one axial direction (left side) and abuts against a fixture 85 (FIG. 2). And a rear end portion 104 that protrudes from the impeller body 100 toward the other side (right side) in the axial direction and abuts against a collar 75 (FIG. 2) that is a flange portion of the turbocharger rotating shaft 44. An end surface 104 a of the rear end portion 104 is orthogonal to the rotation axis AX of the impeller 60.

  Here, the front end and the rear end of the impeller 60 mean one end and the other end of the impeller 60 in the direction of the rotation axis AX. That is, in this embodiment, the front-rear direction of the impeller 60 and the front-rear direction of the motorcycle are different.

  The impeller body 100 includes a plurality of main blades (long blades) 106 that are spaced apart in the circumferential direction and a plurality of splitter blades (half blades) 108 that are disposed between the plurality of main blades 106 in the circumferential direction. I have. The main wing 106 extends rearward from the front end portion 102 of the impeller 60, and the splitter wing 108 extends rearward from a position behind the front end of the main wing 106. In the present embodiment, six main blades 106 and six splitter blades 106 are provided.

  The outer diameter of the circle defined by the front end 112 of the impeller 60, that is, the front edge 112 of the main wing 106 is referred to as the inlet diameter Ii of the impeller 60, and the outer diameter of the rear edge of the impeller 60 is defined as the outlet diameter Io. Called.

  The inlet diameter Ii and the outlet diameter Io of the impeller 60 are set as follows. The inlet diameter Ii of the impeller 60 is determined by the rotational speed of the impeller 60. That is, empirically, it is known that the efficiency is best when the peripheral speed at the inlet-side tip 112 of the main wing 106 is near the sound speed. It is preferable to set the inlet diameter Ii so that the peripheral speed at the side tip 112 becomes the sound speed.

  In addition, the inventor of the present application has found that when the peripheral speed at the inlet end 112 does not greatly exceed the speed of sound, the engine output is less reduced. That is, if the inlet diameter Ii is set so that the peripheral speed at the inlet-side tip 112 when the turbocharger 42 is driven at the maximum allowable engine speed is slightly above the sound speed, the maximum allowable engine speed Without lowering the supercharging efficiency at the time, the peripheral speed at the inlet end 112 can be made close to the sound speed in the region of the rotation speed that is normally used. Here, the “allowable maximum engine speed” refers to the maximum engine speed set by design except for an overrun state of the engine due to an abnormal drop in load.

  Specifically, when the turbocharger 42 is driven at the maximum allowable engine speed, the peripheral speed at the inlet-side tip 112 of the impeller 60 exceeds the sound speed and is 1.3 times or less the sound speed. The inlet diameter Ii of the impeller 60 is preferably set. For example, in a conventional turbocharger in which the peripheral speed at the inlet-side tip 112 is close to the sonic speed, the inlet area is small and a sufficient flow rate cannot be obtained, whereas the inlet-side tip 112 of the present invention is not obtained. Has a large outer diameter, can sufficiently increase the flow rate, and improve the output and efficiency of the supercharger 42.

That is, when the maximum engine speed is Nm (rev / min), the speed increase ratio is α, and the sound speed is Vs (mm / s), the following equation (1) is established.
[(Nm × α) / 60] × π × Ii> Vs (1)
In this embodiment, since it is set to 1.3 times the sound speed, the inlet diameter Ii (mm) is set to the following range.
1.3 × Vs> [(Nm × α) / 60] × π × Ii> Vs
[(1.3 Vs × 60) / (Nm × π) ]> Ii > [(Vs × 60) / (Nm × π)]
That is, when the maximum number of rotations of the turbocharger after the speed increase is 140,000 rotations per minute as in this embodiment, the inlet diameter Ii is preferably in the range of more than 45 mm and less than 59 mm. In the present embodiment, the inlet diameter Ii (mm) is set to 52 mm.

  On the other hand, the outlet diameter Io of the impeller 60 is determined by the size of the impeller housing 63 of FIG. In other words, the size of the impeller 60, that is, the size (height size, front-rear direction size) in the direction orthogonal to the axial direction of the impeller 60 is determined by the outlet diameter Io, and the size of the impeller housing 63 is the size of the impeller 60. It is proportional to the depth. In the case of the present embodiment, as described above, the supercharger 42 of FIG. 1 is disposed in a limited space surrounded by the cylinder block 30, the cylinder head 32, the crankcase 28, and the intake chamber 54. The outlet diameter Io of the third impeller 60 is limited. Specifically, the outlet diameter Io of the impeller 60 is required to be 100 mm or less.

  Thus, since the exit diameter Io of the impeller 60 needs to be a size suitable for being mounted on a motorcycle, the size is limited. However, if the outlet diameter Io is made too small, the deflection becomes steep and the efficiency decreases, which is not preferable. In this embodiment, the outlet diameter Io is about 69 mm.

From these conditions, the optimum trim value TR of the impeller 60 is set. The “trim value TR” is a ratio of the inlet diameter Ii to the outlet diameter Io of the impeller 60 and is represented by (Ii) ² / (Io) ² (%). As a result of trial and error, the inventor of the present application has found that the trim value TR of the impeller 60 is preferably set to 50% or more. The trim value TR is more preferably 55% or more and 65% or less, and is about 57% in the present embodiment. At this time, the inlet diameter Ii is about 52 mm, and the peripheral speed of the inlet-side tip 112 is about 380 m / s (about 1.15 × Vs).

  It is known that the height h, which is the axial dimension of the impeller 60, is preferably about 0.3 to 0.4 times the outlet diameter Io. In this embodiment, since the size of the outlet diameter Io is limited due to the installation space, the height h of the impeller 60 is also reduced. As a result, there is a concern that the length of the blades 106 and 108 in the flow direction is shortened. Therefore, the backward angle θ1 of the main blade 106 and the backward angle θ2 of the splitter blade 108 shown in FIG. 4 are set to positive values. Thereby, the length of the wings 106 and 108 is ensured, and high efficiency is realized.

  Here, the “backward angle” refers to the impeller exit angle. Specifically, when the impeller 60 is viewed in the axial direction from the entrance side (front end side), the exit end (rear edge) of the blade is determined. The inclination angle with respect to the radial direction. Further, “the backward angle is a positive value” means that the backward angle is inclined rearward with respect to the rotation direction R of the impeller 60. Each backward angle θ1, θ2 is preferably 30 to 50 °, more preferably 35 to 45 °, and about 40 ° in the present embodiment.

  The outer diameter Do of the end surface 104a of the rear end portion 104 is set larger than the outer diameter Di of the end surface 102a of the front end portion 102 (Do> Di). Further, the outer diameter Do of the end face 104a of the rear end portion 104 is smaller than the inlet diameter Ii of the impeller body 100 (Do <Ii). The front end surface 102 of the impeller 60 constitutes a seat surface with which the fixture 85 abuts, and the outer diameter Di of the front end portion 102 is substantially the same as the diameter of the fixture 85. Thus, by making the outer diameter Di substantially the same as the diameter of the fixture 85, the inlet opening is enlarged to improve the output, and the outer diameter Do of the end face 104a of the rear end 104 is set to the end face 102 of the end. By making it larger than the outer diameter Di and improving the strength, it is possible to rotate at high speed under high temperature conditions, thereby further improving the output.

  The rear end portion 104 has an end surface 104 a that contacts the collar 75 and a reinforcing portion 104 b that gradually increases in outer diameter from the end surface 104 a toward the impeller body 100. Specifically, the outer diameter dimension of the reinforcing portion 104b is formed in a shape in which a plurality of curvature radii that gradually increase toward the impeller body 100 are combined, and the curvature radius on the impeller body 100 side is larger than the curvature radius on the rear end side. Is also big. This avoids stress concentration at the boundary portion between the impeller body 100 and the rear end portion 104, that is, at the root portion of the rear end portion 104. Further, the outer diameter D1 of the boundary portion with the impeller body 100 at the rear end 104 is larger than ½ of the outlet diameter Io of the impeller 60 and smaller than the inlet diameter Ii of the impeller 60 (Ii> D1> Io). / 2).

  Further, the outer diameter Do of the end face 104a is preferably 0.28 times or more and 0.36 times or less of the outlet diameter Io, more preferably 0.30 times or more and 0.34 times or less. It is 32 times. Further, the outer diameter Di of the end face 102a is preferably 0.24 to 0.28 times the inlet diameter Ii, more preferably 0.25 to 0.27 times. 26 times.

  Furthermore, the root portion 116 a connected to the hub 73 at the front end 116 of the splitter blade 108 is located inside the circular shape of the end surface 104 a of the rear end portion 104 when viewed from the axial direction AX. Thereby, the radial dimension of the rear end portion 104 can be increased to increase the strength of the rear end portion 104 in response to an increase in the mass of the impeller 60 due to the provision of the splitter blade 108.

  The projecting dimension t of the rear end portion 104 from the impeller main body 100 includes a radius r of the through hole 110 through which the supercharger rotating shaft 44 of FIG. 2 is inserted and a radius Di / 2 of the end face 102a of the front end portion 102 of FIG. (T ≧ ((Di / 2) −r)). As shown in FIG. 2, the end surface 104 a of the rear end portion 104 faces the seal member 77 in the axial direction. Further, the outlet diameter Io of the impeller 60 (FIG. 3), that is, the maximum diameter of the impeller 60 is set smaller than the outer diameter P of the planetary gear device 64.

  As shown in FIG. 5, the main blade 106 has a maximum thickness portion 114 having the largest thickness at an intermediate portion in the intake flow direction FD, and the front end 116 of the splitter blade 108 and the maximum thickness portion of the main blade 106. 114 are displaced in the flow direction FD. Specifically, the front end 116 of the splitter blade 108 is located upstream of the maximum thickness portion 114 of the main blade 106.

  More specifically, with respect to the length L along the center line C1 of the cross section of the main blade 106 shown in FIG. 6, the displacement dimension Ld in the flow direction FD between the maximum thickness portion 114 and the splitter blade 108 is Ld = (1/10 to 1/4) L (0.1 L ≦ Ld ≦ 0.25 L). Here, the “cross section of the main wing 106” refers to a cross section of the main wing 106 along the flow direction FD.

  Next, a method for manufacturing the impeller 60 will be described. First, a frustoconical impeller prototype is formed by forging. Next, the general shape of the impeller 60 is formed by lathe processing. At this point, the impeller body 100, the front end portion 102, and the rear end portion 104 are partitioned, but the impeller body 100 is not formed with the wings 106 and 108. Subsequently, rough shapes of the blades 106 and 108 are formed. Roughing is performed using, for example, a large ball mill.

  Finally, the final shape of the blades 106 and 108 is formed by precision machining. Precision machining is performed by cutting using a small end mill. At this time, as shown in FIG. 7, the surfaces of the blades 106 and 108 are cut along the flow direction FD of the intake air. In the precision processing, both the front surface and the back surface are processed simultaneously using a common end mill.

  Next, the operation of the supercharger 42 will be described. When the engine E in FIG. 1 is started, the supercharger 42 is driven in conjunction with the crankshaft 26. As described above, the supercharger rotating shaft 44 of FIG. 2 rotates at a high speed of 140,000 rotations per minute at the maximum. Since it rotates at such a high speed, a large centrifugal force acts on the rear end side portion 118 of the impeller body 100 having the largest outer diameter in the impeller 60. As a result, a large tensile force is generated in the region AR on the rear end side of the impeller 60 toward the outside. As described above, since the intake air temperature reaches about 100 ° C. at the outlet of the supercharger 42, the strength of the material may be lower than that at normal temperature, and the impeller 60 caused by the centrifugal force during high-speed rotation may be reduced. It is necessary to prevent deformation.

  In order to maintain the performance while reducing the size of the impeller 60, it is necessary to increase the speed. However, if the speed is increased, a large centrifugal force is generated as described above. In the above embodiment, since the outer diameter Do of the end surface 104a of the rear end portion 104 is set larger than the outer diameter Di of the end surface 102a of the front end portion 102, the strength against the tensile force of the rear end portion 104 outward in the radial direction is set. Will improve. Therefore, even if the turbocharger rotating shaft 44 rotates at a high speed and a large tensile force is generated on the rear end side of the impeller main body 100 in the radial direction, the rear end side of the impeller main body 100 is affected by such a tensile force. It can suppress receiving. As a result, the impeller 60 can be rotated at a high speed.

  However, the outer diameter Do of the end surface 104 a of the rear end portion 104 shown in FIG. 3 is smaller than the inlet diameter Ii of the impeller 60. As a result, the rear end portion 104 can be prevented from becoming large, an increase in centrifugal force can be suppressed, and the weight of the impeller 60 can be reduced.

  In addition, since the outer diameter of the rear end portion 104 gradually increases toward the impeller body 100, stress concentration at the boundary portion between the rear end portion 104 and the impeller body 100 is suppressed. Further, the outer diameter of the boundary portion is larger than ½ of the outlet diameter Io of the impeller body 100 and smaller than the inlet diameter Ii of the impeller body. Thereby, it is possible to suppress the centrifugal force by suppressing the outer shape of the rear end side portion 118 of the impeller body 100 from being increased while increasing the rigidity of the rear end portion 104.

  The projecting dimension t of the rear end portion 104 from the impeller body 100 is set to be equal to or greater than the difference between the radius r of the through hole 110 and the radius Di / 2 of the end surface 102a of the front end portion 102 (t> (Di / 2 ) -R). Thereby, the protrusion amount of the rear-end part 104 becomes large, and it can suppress that the rigidity of area | region AR (FIG. 2) of the rear-end side of the impeller main body 100 falls.

  As shown in FIG. 2, the end surface 104 a of the rear end portion 104 faces the seal member 77 in the axial direction. Thereby, since the axial gap between the seal member 77 and the impeller 60 is reduced, it is possible to prevent the lubricating liquid from leaking.

  In the above configuration, when the turbocharger 42 is driven at the maximum allowable engine speed, the peripheral speed at the inlet-side tip 112 of the impeller 60 is set to exceed the sound speed. The peripheral speed in the normal operation area can be made close to the sound speed. As a result, the supercharging efficiency in the normal operation region is increased, and the engine output is improved. Further, the radial dimension of the inlet-side tip 112 of the impeller 60 is increased so that the peripheral speed thereof exceeds the sound speed to increase the flow rate, and the outlet diameter Io of the impeller 60, that is, the radial dimension of the supercharger 42. Can be suppressed. Therefore, since the supercharger 42 is not increased in size, the supercharger 42 can be arranged in a limited installation space of the motorcycle.

  Further, the inlet diameter Ii of the impeller 60 is set so that the peripheral speed at the inlet-side tip 112 at the maximum allowable engine speed is 1.3 times or less than the sound speed. Thereby, since it rotates at the peripheral speed close | similar to a sound speed also at the time of allowable maximum engine speed, the output fall at the time of allowable maximum engine speed can be suppressed. As a result, good engine output can be obtained over a wide range.

  Furthermore, since the trim value is set to 50% or more and the outlet diameter Io is reduced, the supercharger 42 can be easily mounted even in a motorcycle with limited space. Further, since the height h (dimension in the vehicle width direction) of the impeller 60 is determined by the outlet diameter Io (about h = 0.3 to 0.4 × Io), the height h decreases as the outlet diameter Io decreases. In the present embodiment, the turbocharger 42 in FIG. 1 is accommodated within the width of the crankcase 28, and further, a suction port 46 is provided on the left side of the vehicle body, and a power transmission mechanism 74 (FIG. 2) is provided on the right side. The space in the vehicle width direction is also limited. However, since the height h of the impeller 60 is reduced, the supercharger 42 becomes more compact. Therefore, the supercharger 42 can be mounted in a limited space in the vehicle width direction.

  Further, the backward angles θ1 and θ2 of the main blade 106 and the splitter blade 108 in FIG. 4 are set to positive values. If the impeller 60 is reduced in size for mounting on a motorcycle, the blade length tends to be shortened. However, by setting the backward angles θ1 and θ2 to positive values, the blade length can be earned. As a result, it is possible to suppress the efficiency of the supercharger 42 from being lowered while downsizing the impeller 60.

  The outlet diameter Io of the impeller 60 is set smaller than the outer diameter of the planetary gear device 64 of FIG. Even when the outlet diameter Io and the height h of the impeller are limited, by setting the backward angles θ1 and θ2 to positive values, the efficiency of the supercharger 42 is reduced while the impeller 60 is downsized. Can be suppressed.

  As shown in FIG. 6, the front end 116 of the splitter blade 108 and the maximum thickness portion 114 of the main blade 106 are arranged so as to be shifted in the intake flow direction FD. Thereby, it is possible to prevent the flow path from being suddenly narrowed due to the presence of the splitter blade 108 and improve the supercharging efficiency.

  As shown in FIG. 7, the surfaces of the blades 106 and 108 are formed by cutting along the intake air flow direction FD. Thereby, since intake air flows along the processing groove formed by cutting, flow path resistance is reduced and, as a result, efficiency improves.

  In the above embodiment, the rotation of the engine E is increased through the planetary gear device 64 and transmitted to the impeller 60. Thereby, the flow rate can be earned without increasing the inlet diameter Ii. Further, in addition to the planetary gear unit 64, the inlet diameter Ii can be further reduced by increasing the speed by gear connection in the power transmission path. In other words, by setting the speed increasing ratio so that the inlet diameter Ii and the outlet diameter Io are smaller than the outer diameter P of the planetary gear device 64, the turbocharger 42 can be prevented from being increased in size and increased in speed. It is possible to prevent the ratio from becoming excessive.

  Even if the trim value is relatively small and the radial dimension of the wing becomes small, by setting the backward angle to be positive, the radial dimension of the wing is extended and the air guide surface by the wing is increased. be able to. Thereby, the fall of the supercharging efficiency by a trim value becoming small can be suppressed. Even when the height h of the impeller 60 is small and the axial dimension of the wing becomes small, the wing length along the center line of the cross section of the wing is extended by making the backward angle positive. Thus, the air guide surface by the wing can be increased. Thereby, the fall of the supercharging efficiency by the height h of the impeller 60 becoming small can be suppressed.

  In order to reduce the size of the supercharger 42 of the above embodiment, it is preferable to reduce the height h (dimension in the vehicle width direction) of the impeller 60. That is, in the supercharger 42 of the above embodiment, the supercharger case 66 is disposed on the right side of the impeller housing 63 and the air cleaner 40 is disposed on the left side. The impeller housing 63, the supercharger case 66, and the air cleaner 40 are It is contained within the width of the crankcase 28. Further, since the intake duct 50 extending in the front-rear direction is curved in the vehicle width direction and connected to the air cleaner 40, the space in the vehicle width direction is further compressed. Thus, even when it is required to reduce the height h of the impeller 60, the reduction in supercharging efficiency can be suppressed by making the backward angle positive as described above.

  In other words, the outlet diameter Io is set to be smaller than the outer diameter P of the planetary gear device 64, and the inlet diameter Ii is set so that the peripheral speed is equal to or higher than the sound speed, and the speed increasing ratio is set so as to satisfy these. By setting, it is possible to improve the engine output while preventing the turbocharger 42 from becoming large, and to improve the mountability to a motorcycle.

  When the peripheral speed of the inlet-side tip 112 exceeds the sound speed, the engine output decrease width is small if the sound speed exceeds the sound speed, and if the predetermined speed is exceeded, the engine output decrease width increases. In the present invention, at the maximum allowable number of rotations, the peripheral speed of the inlet-side tip 112 is set to exceed the sound speed and within a predetermined range. This predetermined range can be obtained by experiment or simulation.

  The present invention is not limited to the above-described embodiment, and various additions, modifications, or deletions can be made without departing from the gist of the present invention. For example, the impeller 60 of the above embodiment has the main blade 106 and the splitter blade 108, but the splitter blade 108 may not be provided. Therefore, such a thing is also included in the scope of the present invention.

42 Supercharger 44 Supercharger rotating shaft 60 Impeller 75 Collar (flange)
77 Seal member 85 Fixing tool 100 Impeller body 102 Front end portion 102a Front end portion end surface 104 Rear end portion 104a Rear end portion end surface 110 Through hole Di Front end end surface outer diameter Do Rear end end surface outer diameter
Ii impeller inlet diameter (outer diameter of front end of impeller body)
Io impeller outlet diameter (outer diameter of the rear end of the impeller body)
r Radius t of the through hole Projection dimension of the rear end

Claims (4)

A centrifugal impeller that is fixed to a rotating shaft of a supercharger inserted through a through hole using a fixing tool,
An impeller body on which wings are formed;
A front end protruding from the impeller body in one axial direction and contacting the fixture;
A rear end portion that protrudes from the impeller body in the other axial direction and contacts the flange portion of the rotating shaft, and
The outer diameter of the end surface of the rear end portion is set larger than the outer diameter of the end surface of the front end portion,
The outer diameter of the rear end portion gradually increases from the end surface toward the impeller body,
The outer diameter dimension of the boundary portion with the impeller body at the rear end is larger than 1/2 of the outer dimension of the base end of the impeller body, and is smaller than the outer dimension of the tip of the impeller body . Centrifugal impeller. A centrifugal impeller that is fixed to a rotating shaft of a supercharger inserted through a through hole using a fixing tool,
An impeller body on which wings are formed;
A front end protruding from the impeller body in one axial direction and contacting the fixture;
A rear end portion that protrudes from the impeller body in the other axial direction and contacts the flange portion of the rotating shaft, and
The outer diameter of the end surface of the rear end portion is set larger than the outer diameter of the end surface of the front end portion,
The centrifugal impeller of a supercharger, wherein a projecting dimension of the rear end portion from the impeller body is set to be equal to or larger than a difference between a radius of a through hole and a radius of an end face of the front end portion. The centrifugal impeller according to claim 1 or 2 , wherein an outer diameter of an end surface of the rear end portion is smaller than an outer diameter of a front end portion of the impeller body. The centrifugal impeller according to any one of claims 1 to 3 , wherein the rear end portion is a centrifugal portion of a supercharger that is opposed to a seal member disposed radially outside the flange portion in the axial direction. Formula impeller.

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