JP5609217B2 - Turbocharger - Google Patents

Description

  The present invention relates to a supercharger such as a supercharger for a vehicle.

  2. Description of the Related Art Conventionally, a supercharger that supercharges air supplied to an engine using energy of exhaust gas from the engine is known (see, for example, Patent Document 1).

  The turbocharger described in Patent Document 1 includes a bearing housing disposed on the center side, a compressor housing disposed on one side of the bearing housing, and a turbine housing disposed on the other side of the bearing housing. It has. A rotor shaft is rotatably provided in the bearing housing via a bearing. A compressor impeller is connected to one end of the rotor shaft, and a turbine impeller is connected to the other end.

  Here, when the exhaust gas taken into the turbine housing is supplied to the turbine impeller side, the turbine impeller can be rotated by the energy of the exhaust gas, and the compressor impeller can be integrally rotated via the rotor shaft. it can. Thereby, the air suck | inhaled in the compressor housing can be compressed, and the air supplied to an engine can be supercharged.

JP 2002-70570 A

  However, in recent years, the thrust load applied to the rotor shaft tends to increase as the compressor impeller increases in pressure ratio and rotation. When this thrust load becomes large, the temperature of the thrust bearing among the bearings increases, and the durability of the turbocharger may be reduced.

  Accordingly, an object of the present invention is to provide a supercharger that can maintain high durability even when a thrust load applied to the rotor shaft increases with an increase in the pressure ratio and rotation of the compressor impeller. To do.

The present invention relates to a supercharger that supercharges air supplied to the engine using energy of exhaust gas from the engine, and a rotor shaft that is rotatably provided in a bearing housing via a bearing; A compressor impeller provided in a compressor housing on one side of the bearing housing and connected to one end of the rotor shaft; and a turbine housing on the other side of the bearing housing, and connected to the other end of the rotor shaft. A turbine impeller coupled to the bearing, and at least a part of the rotor shaft is formed into a tapered portion whose outer diameter gradually decreases toward the compressor housing, and the bearing is located on the outer peripheral side of the tapered portion. The inner peripheral surface of the bearing is brought into contact with the tapered portion. Formed so the inner diameter becomes gradually smaller toward the suppressor housing side, the central axis of the tapered portion of the rotor shaft, configured to coincide with the center axis of the rotor shaft,
The turbocharger characterized in that the contact portion between the outer peripheral surface of the tapered portion of the rotor shaft and the inner peripheral surface of the bearing is set from the end of the tapered portion on the compressor housing side to the middle portion of the tapered portion. .

  According to the present invention, even if the thrust load applied to the rotor shaft increases as the compressor impeller increases in pressure ratio and rotation, a part of this thrust load is canceled by the reaction force acting on the tapered portion of the rotor shaft. Therefore, it is input to a thrust bearing among the bearings. An increase in thrust load can be suppressed. For this reason, even if the compressor impeller has a high pressure ratio and high rotation, the high durability of the supercharger can be maintained.

It is a sectional side view of the supercharger for vehicles concerning the embodiment of the present invention. It is sectional drawing to which the vicinity of the rotor shaft in FIG. 1 was expanded. It is explanatory drawing which shows the reaction force which the turbine side bearing part of a rotor shaft receives from a 1st bearing.

  An embodiment of the present invention will be described with reference to FIGS. 1 to 3. In the drawings, “F” indicates the forward direction and “R” indicates the backward direction.

  FIG. 1 is a side sectional view of a supercharger for a vehicle according to an embodiment of the present invention.

As shown in FIG. 1, a vehicular supercharger 1 according to an embodiment of the present invention supercharges air supplied to an engine using energy of exhaust gas from an engine (not shown). is there. And the specific structure of the supercharger 1 for vehicles is as follows.

  The vehicle supercharger 1 includes a compressor housing 3 disposed on the front side, a bearing housing 5 disposed on the center side, and a turbine housing 7 disposed on the rear side. That is, the compressor housing 3 is disposed on the front side (one side) of the bearing housing 5, and the turbine housing 7 is disposed on the rear side (the other side).

  The compressor housing 3 is formed with an air inlet 9 that opens toward the front side, and the air inlet 9 communicates with a compressor scroll passage 13 via a diffuser passage 11. The air inlet 9 can be connected to an air cleaner (not shown). The diffuser channel 11 is formed between the bearing housing 5 and the compressor housing 3, and pressurizes compressed air. The compressor scroll passage 13 is formed in a ring shape in the compressor housing 15 so as to surround the compressor impeller 15 from the outer periphery. The compressor impeller 15 is disposed inside the opening of the air suction port 9 and is fastened to a rotor shaft 21 disposed in the bearing housing 5 via a thin mounting shaft 17 and a nut 19. . The compressor impeller 15 is formed by integrally forming a compressor wheel 23 attached to the attachment shaft 17 and a compressor blade 25 disposed on the outer peripheral side of the compressor wheel 23.

  The bearing housing 5 is formed with an oil supply passage 27 for supplying lubricating oil to a plurality of bearings, and the inside of the bearing housing 5 is controlled to a predetermined temperature or lower. A discharge hole 73 for discharging the lubricating oil to the outside of the vehicle supercharger 1 is formed at the lower end of the bearing housing 5. The flow of the lubricating oil will be described later.

  Further, an insertion hole 29 extending in the front-rear direction is formed inside the bearing housing 5, and the rotor shaft 21 is inserted into the insertion hole 29 via the first to third bearings 31, 33, and 35. It is inserted so that it can rotate. A thrust collar 37 is provided between the second bearing 33 and the third bearing 35.

  The turbine housing 7 is formed with a gas intake (not shown) for taking in exhaust gas, and this gas intake can be connected to an exhaust manifold (not shown) of the engine. A turbine scroll passage 39 is formed in an annular shape inside the turbine housing 7 so as to surround the turbine impeller 41, and the turbine scroll passage 39 communicates with the gas intake. Further, a gas exhaust port 43 for exhaust gas exhaust is formed in the turbine housing 7 toward the rear side, and this gas exhaust port 43 communicates with the turbine scroll flow path 39 to provide an exhaust catalyst (not shown). (Omitted) can be connected. The turbine impeller 41 is formed by integrally forming a turbine wheel 45 and a turbine blade 47 disposed on the outer peripheral side of the turbine wheel 45. The rotor shaft 21 is integrally formed with the turbine wheel 45 and extends forward from the front end portion of the turbine wheel 45. The turbine wheel 45 and the turbine blade 47 are disposed inside the opening of the gas discharge port 43, and the rotor shaft 21 is disposed in the bearing housing 5.

  FIG. 2 is an enlarged cross-sectional view of the vicinity of the rotor shaft in FIG.

  As shown in FIG. 2, the outer diameter of the outer peripheral surface 49 a gradually decreases toward the front side (compressor housing 3 side) at the rear end portion (the root portion of the turbine wheel 45) of the rotor shaft 21. A substantially frustoconical turbine side bearing portion (tapered portion) 49 is formed. Thus, the turbine side bearing portion 49 is disposed in the vicinity of the turbine wheel 45 in the rotor shaft 21. In addition, a cylindrical compressor-side bearing 51 having an outer diameter that is the same in the front-rear direction is provided at the front end of the rotor shaft 21. A turbine-side bearing portion 49 and a connecting portion 53 having a smaller diameter than the compressor-side bearing portion 51 are provided. The turbine-side bearing portion 49, the connecting portion 53, and the compressor-side bearing portion 51 are integrally formed. Has been. Note that oil drain holes 71 and 72 for discharging the lubricating oil to the outside of the vehicle supercharger 1 are formed in the lower portion of the bearing housing 5. A tool escape portion 74, an oil slinger 75, and an oil slinger groove 76 are formed on the rear side (turbine wheel 45 side) of the turbine side bearing portion 49.

  On the other hand, a first bearing 31 formed in a cylindrical shape and extending in the front-rear direction is disposed on the outer peripheral side of the rotor shaft 21. The first bearing 31 is made of copper and is supported by the bearing housing 5 through a bolt 55 so as not to rotate. A rear contact portion 57 that engages with the turbine side bearing portion 49 of the rotor shaft 21 is formed at the rear end portion of the first bearing 31, and the compressor side bearing portion 51 of the rotor shaft 21 is formed at the front end portion. A front contact portion 59 to be engaged is formed. An intermediate portion 61 is formed between the rear contact portion 57 and the front contact portion 59. The inner peripheral surface of the intermediate portion 61 and the outer peripheral surface of the connecting portion 53 of the rotor shaft 21 are formed. A predetermined gap is formed in the radial direction of the rotor shaft 21. Further, the inner peripheral surface 57a of the rear contact portion 57 of the first bearing 31 has an inner diameter that gradually decreases toward the front side, and can be brought into contact with the turbine side bearing portion 49 of the rotor shaft 21. Has been.

  Further, the inner peripheral surface 59 a of the front contact portion 59 of the first bearing 31 has the same inner diameter along the front-rear direction and is configured to be able to contact the compressor-side bearing portion 51 of the rotor shaft 21. ing. This functions as a radial bearing that receives a radial load applied in the radial direction (radial direction) of the rotor shaft 21.

  The second bearing 33 and the third bearing 35 function as a thrust bearing that receives a thrust load applied in the axial direction (thrust direction) of the rotor shaft 21.

  Here, the flow of the lubricating oil will be described.

  First, the lubricating oil is supplied to the bearings 31, 33, and 35 through the oil supply passage 27 described above.

  The lubricating oil supplied to the bearings 33 and 35 is discharged to the outside of the vehicle supercharger 1 through the oil discharge hole 72 and the discharge hole 73.

  Most of the lubricating oil supplied to the turbine side bearing portion 49 is discharged to the outside of the vehicle supercharger 1 through the oil drain hole 71, but the remaining lubricating oil is passed through the oil slinger 75. Then, after flowing into the oil slinger groove 76, the oil is discharged from the discharge hole 73 to the outside of the vehicle supercharger 1.

  FIG. 3 is an explanatory diagram illustrating a reaction force that the turbine-side bearing portion of the rotor shaft receives from the first bearing.

  The turbine side bearing portion 49 of the rotor shaft 21 is formed at a taper angle θ, and the outer peripheral surface 49 a of the turbine side bearing portion 49 of the rotor shaft 21 and the inner peripheral surface of the rear contact portion 57 of the first bearing 31. An oil film of lubricating oil is formed between 57a and 57a. Thus, the rotor shaft 21 according to the present embodiment is configured as a so-called semi-float type.

  Here, as shown in FIG. 1, the air pressure at the air inlet 9 in the compressor housing 3 is P1 of atmospheric pressure, and the air pressure in the compressor scroll flow path 13 is P2. Since P2 is boosted from P1, P2> P1. Therefore, a load Tc is applied to the compressor impeller 15 in the thrust direction toward the front. On the other hand, the air pressure at the gas discharge port 43 in the turbine housing 7 is P3 of atmospheric pressure, and the air pressure in the turbine scroll passage 39 is P4. Since P4 is boosted more than P3, P4> P3. Therefore, a load Tt is applied to the turbine impeller 41 in the thrust direction toward the rear. Since the load Tc is larger than the load Tt, a thrust load Tr is applied to the rotor shaft 21 toward the front side (compressor housing 3 side). The thrust load Tr is a difference between Tc and tr: (Tc−Tt).

  Then, as shown in FIGS. 2 and 3, the outer peripheral surface 49 a of the turbine side bearing portion 49 of the rotor shaft 21 reacts with the reaction force from the inner peripheral surface 57 a of the rear contact portion 57 of the first bearing 31 via the oil film. Receive P. This reaction force P acts in a direction perpendicular to the outer peripheral surface 49 a of the turbine side bearing portion 49. The reaction force P is a resultant force of a thrust direction (axial direction) component of the rotor shaft 21: P · sin θ and a radial direction (radial inner side) component of the rotor shaft 21: P · cos θ. Among these components, the thrust direction (axial direction) component: P · sin θ shares and receives a part of the thrust load Tr received by the rotor shaft 21. As the taper angle θ increases, the thrust direction (axial direction) component: P · sin θ of the rotor shaft 21 also increases.

  Next, the function and effect of this embodiment will be described.

(1) A supercharger 1 for a vehicle according to the present embodiment includes a first turbocharger 1 in a bearing housing 5 in the supercharger 1 that supercharges air supplied to the engine using energy of exhaust gas from the engine. A rotor shaft 21 rotatably provided via a bearing 31 (bearing), and a compressor housing 3 on the front side (one side) of the bearing housing 5, and a front end portion (one end) of the rotor shaft 21. ) And a turbine impeller provided in the turbine housing 7 on the rear side (the other side) of the bearing housing 5 and connected to the rear end portion (the other end portion) of the rotor shaft 21. 41, and the outer diameter of at least a part of the rotor shaft 21 gradually decreases toward the compressor housing 3 side. The first bearing 31 is formed on the bin-side bearing portion (tapered portion) 49 and is positioned on the outer peripheral side of the turbine-side bearing portion 49 so that the first bearing 31 contacts the turbine-side bearing portion 49. The inner circumferential surface is formed so that the inner diameter gradually decreases as it goes toward the compressor housing 3 side.

  Since the thrust load Tr toward the compressor housing 3 is applied to the rotor shaft 21, a reaction force P · sin θ toward the turbine housing 7 acts on the turbine side bearing portion 49 of the rotor shaft 21. Therefore, even if the thrust load Tr of the rotor shaft 21 increases as the compressor impeller 15 increases in pressure ratio and rotation, a part of the thrust load Tr acts on the turbine side bearing portion 49 of the rotor shaft 21. Since it is canceled out by the reaction force P · sin θ, an increase in the thrust load input to the thrust bearing can be suppressed. For this reason, since it suppresses that the temperature inside the supercharger 1 rises and the high temperature corrosion of each component accompanying temperature rise is also suppressed, even if the compressor impeller 15 becomes a high pressure ratio and high rotation, The durability of the supercharger 1 can be maintained.

(2) Further, since the turbine side bearing portion (tapered portion) 49 is disposed in the vicinity of the turbine impeller 41 in the rotor shaft 21, the rotation of the turbine impeller 41 can be stabilized.

  In addition, this invention is not restricted to description of the above-mentioned embodiment, It can implement in a various aspect. Further, the scope of rights encompassed by the present invention is not limited to these embodiments.

1 Vehicle turbocharger (supercharger)
3 Compressor housing 5 Bearing housing 7 Turbine housing 15 Compressor impeller 21 Rotor shaft 31 First bearing (bearing)
41 Turbine impeller 49 Turbine side bearing (taper)

Claims (2)

In the supercharger that supercharges the air supplied to the engine using the energy of the exhaust gas from the engine,
A rotor shaft rotatably provided via a bearing in the bearing housing;
A compressor impeller provided in a compressor housing on one side of the bearing housing and connected to one end of the rotor shaft;
A turbine impeller provided in the turbine housing on the other side of the bearing housing and connected to the other end of the rotor shaft,
At least a part of the rotor shaft is formed as a tapered portion whose outer diameter gradually decreases toward the compressor housing, and a bearing located on the outer peripheral side of the tapered portion is in contact with the tapered portion. The inner peripheral surface of the bearing is formed so that the inner diameter gradually decreases toward the compressor housing side, and the central axis of the tapered portion of the rotor shaft is configured to coincide with the central axis of the rotor shaft ,
The turbocharger characterized in that the contact portion between the outer peripheral surface of the tapered portion of the rotor shaft and the inner peripheral surface of the bearing is set from the end of the tapered portion on the compressor housing side to the middle portion of the tapered portion. .   The supercharger according to claim 1, wherein the tapered portion is disposed in the vicinity of a turbine impeller on the rotor shaft.

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