JP2701527B2 - Turbocharger bearing structure - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a bearing structure of a turbocharger using an angular ball bearing.

[Conventional technology]

Japanese Utility Model Laid-Open No. 63-9429 discloses a bearing structure of a turbocharger using an angular ball bearing. The angular contact ball bearing receives a radial force between a turbine wheel shaft and a bearing housing and receives a thrust force applied to the turbine wheel shaft. The outer ring of the bearing is pressurized by a spring, and the outer ring is pressed against the bearing ball with a predetermined elastic force (preload) against a thrust force. When a thrust force greater than the preload is applied, the spring is deformed, and the outer ring moves in the axial direction. The movement of the outer ring in the axial direction may cause play or the ball may come off. Therefore, a collar having a stopper portion is provided on the outer ring, and when a thrust force greater than the preload is applied, the stopper portion comes into contact with the bearing housing, so that further movement of the outer ring is prevented.

In Japanese Utility Model Laid-Open No. 1-159132, an oil film damper for controlling oil film is provided outside the outer ring of the bearing, and a spring for applying a pressure is arranged between the oil film dampers.
A stopper member is arranged between the oil damper films.
When a thrust force equal to or greater than the applied pressure is applied, the oil film damper hits the stopper member, and further movement in the thrust direction is prevented.

[Problems to be solved by the invention]

In the case of the prior art, a spring for applying a pressurization and a stopper means for preventing displacement of the outer ring are provided as separate members from the spring. That is, in the prior art, a stopper is required in addition to the spring, and there is a disadvantage that the number of parts is increased.

An object of the present invention is to reduce the number of parts in a turbocharger bearing structure provided with an angular ball bearing, and as a means for solving the problem, a single part has both a stopper function and a pressurizing function.

[Means for solving the problem]

According to the present invention, in a turbocharger in which a turbine wheel shaft is supported on a bearing housing by a pair of angular ball bearings, a slit extending in a direction intersecting with the turbine wheel axis is formed between opposed outer rings of the pair of angular ball bearings. And a bearing structure for a turbocharger, wherein the pressurized spacer is arranged.

[Action]

The slit formed in the pressurized spacer makes the pressurized spacer have elasticity in a direction parallel to the turbine wheel axis, and applies a pressurized force against a thrust applied to the turbine wheel shaft to the bearing outer ring.

When the thrust force increases, the slit closes and the elastic modulus increases, so that the pressurized spacer achieves a stopper function for preventing the outer ring from shifting.

〔Example〕

6, reference numeral 10 denotes a bearing housing of a turbocharger, 12 denotes a turbine wheel shaft, and a turbine wheel 14 is integrally formed at one end, and a compressor wheel 16 is fixed to a nut 18 at the other end. The turbine wheel shaft 12 is supported on the bearing housing 10 by a pair of angular ball bearings 20.

In FIG. 7, the angular ball bearing 20 has an inner ring 22, an outer ring 24, and a bearing ball 26, the inner ring 22 is fitted to the turbine wheel shaft 12, and the outer ring 24 is a shaft hole of the bearing housing 10.
Fitted to 28. A ring 30 is provided on the turbine wheel shaft 12 on the side of the turbine wheel 14 to engage with a shoulder 29 serving as a stopper of the angular ball bearing 20 on the turbine wheel side. An annular shoulder that serves as a stopper for the outer ring 24 of the ball bearing 20 on the turbine wheel side on the inner periphery of the shaft hole 28 of the bearing housing 10.
32 are formed. An end plate 40 is fixed to an end surface of the bearing housing 10 on the side of the compressor wheel 16 by bolts 42 (FIG. 6). The end plate 40 has a portion 44 protruding beyond the inner periphery of the turbine wheel shaft hole 28, and the protruding portion 44 serves as the outer ring 24 of the angular ball bearing 20 on the compressor wheel 16 side.
It becomes a stopper. An annular member 46 is fitted to the turbine wheel shaft 12 and is fixed to the turbine wheel shaft 12 together with the compressor wheel 16 by a nut 18 (FIG. 6). The annular member 46 is an angular contact ball bearing on the compressor wheel 16 side. The inner ring 22 serves as a stopper. Further, a seal 48 is provided in the annular groove 47 on the outer periphery of the annular member 46 and extends to the inner peripheral surface of the end plate 40. The turbine wheel shaft 12 has a large diameter at a connection portion to the turbine wheel, and forms an annular groove 51 for accommodating the seal 50.

An inner annular spacer 56 is disposed on the turbine wheel axis between the opposed inner races 22 of the angular ball bearing. Inner annular spacer 56 holds inner race 22 in place on turbine wheel shaft 12.

The pressurizing spacer 60 applies a preload to the outer ring 24 of the angular ball bearing 20, and also prevents the outer ring 24 from shifting when receiving a thrust. The pressurized spacer 60 is shown in FIG.
As shown in the figure, a helical slit 62 that is slightly inclined with respect to the axis is formed so that the fifth slit is formed in the axial direction.
A two-stage preload characteristic as shown in the figure can be exhibited. When the deformation amount δ is small, the slit 62 allows deformation, so a preload is applied to the angular contact ball bearing 20, and in a region where the deformation amount δ is large, the stopper function prevents the outer ring from moving further in the axial direction. To achieve. W _E the width of the axial direction of the outer ring in Figure 6, the length l _P of pressurized spacers 60, when the movable dimensions of the outer ring was l _E, the insertion of the bearing housing length l _B (pressurizing spacer 60 spacing between the projecting portion 44 of the left and right in the inserted state an annular shoulder 32) must satisfy the _{l B ≦ (2 × W E} + l P + l E).

The adoption of the angular contact ball bearing can improve the characteristics of the turbocharger in the transient state. FIG. 9 shows the relationship between the engine speed and the intake pipe pressure. The solid line shows the characteristics of a normal float bearing, and the broken line shows the characteristics of an angular ball bearing. As can be seen from the drawing, the pressure in the intake pipe rises from the low rotation side of the angular ball bearing as compared with the float bearing, and it is understood that it is effective in improving the transient response characteristics of the turbocharger.

In FIG. 6, the bearing housing has a lubricating oil passage 65 communicating with the oil supply port 67, and can lubricate the bearing 20. The lubricating oil after lubrication is collected in the recovery chamber 69. FIG. 7,
As shown in FIG. 8, the outer race 24 of the angular contact ball bearing 20 has an oil introduction hole 80 drilled at intervals in the circumferential direction. An oil supply hole 82 provided in the bearing housing 10 is opened in the annular groove 81. The seal ring 84 is disposed in a seal groove 86 formed in the inner ring 22 of the angular ball bearing 20, and the seal ring 84 extends to the inner peripheral surface of the outer ring 24. Lubricating oil passes through a lubricating oil passage 65 formed in the bearing housing.
Is introduced into the oil supply hole 82, and the lubricating oil is
The oil is guided to the oil introduction hole 80 through the annular groove 81 from the oil passage 82, and lubricates the bearing ball 26. Since the seal ring 84 is provided, the lubricating oil is directed inward as shown by the arrow f, passes through the gaps between the respective parts, and finally the oil recovery chamber of the bearing housing.
Gather at 69. By directing the lubricating oil inward, leakage of the lubricating oil to the turbine side or the compressor side can be minimized. Further, since the leakage of the lubricating oil to the turbine side or the compressor side is small, the oil drain normally provided in the boss portion of the compressor can be eliminated. Further, instead of the oil seal using the seal ring 84, a ball retainer itself of a ball bearing having an oil seal function can be adopted. In this case, the oil introduction holes and grooves are arranged inside the ball.

Thrust is applied to the turbine shaft during operation of the turbocharger. The pressurized spacer 60 is contracted within its elastic limit due to the slit 62, and preloads the bearing. When the movement of the outer ring becomes large due to receiving a thrust equal to or more than a predetermined value, the opposing edges of the slit 62 come into contact with each other, and the pressurized spacer 60 prevents further movement of the outer ring. Therefore, displacement of the outer ring can be prevented. As described above, the pressurized spacer 60 also has a function as a stopper that applies a preload to the bearing and prevents the movement of the bearing when further thrust is applied to the bearing.

FIGS. 3 and 4 show another embodiment of the pressurized spacer 60 in which the slit 70 shifts the phase in the circumferential direction of the pressurized spacer 60 along a plane perpendicular to its axis. A plurality of staggered patterns are alternately arranged. The preload applying function and the shift prevention function of the pressurizing spacer 60 are not different from those of the first embodiment.

10 and 11 show another embodiment of the lubricating oil supply structure in the bearing structure of the present invention. An annular projection 88 for draining oil is formed on the inner spacer 56 near the left and right angular ball bearings 20. The annular projection 88 has a function as an oil drain. That is, the flow of the lubricating oil as indicated by the arrow f is received, and the flow is dispersed by the centrifugal force generated by the rotation of the turbine wheel shaft 12. The lubricating oil is received in the oil recovery chamber 69. That is, it is possible to eliminate the possibility that the lubricating oil is transmitted through the turbine wheel shaft 12 and leaks to the compressor side or the turbine side due to oil drainage.

FIGS. 12 and 13 show another embodiment of the lubricating oil supply structure, which differs from the embodiment of FIGS. 10 and 11 in that the outer periphery of the outer ring 24 of the angular contact ball bearing 20 and the shaft hole 28 of the bearing housing 10 are different from those of FIGS. A cylindrical damper 90 is arranged between the inner periphery of the cylindrical damper 90. The cylindrical damper 90 is made of a material such as foamed silicone rubber in order to facilitate deformation and in consideration of durability. The cylindrical damper 90 has a hole 94 that opens to the oil supply hole 82, and supplies oil to the angular ball bearing 20 via the groove 81 of the outer ring 24 and the oil hole 80. The cylindrical damper 90 can prevent an overload from being generated between the bearing and the shaft due to running vibration or engine vibration, and can prevent damage to the turbine wheel.

[Effect of the invention]

According to this invention, since the pressurizing spacer serves both to apply pressurizing to the angular ball bearing and to prevent the outer ring from shifting, the number of parts can be reduced accordingly.

[Brief description of the drawings]

FIG. 1 is a side view of a pressurized spacer. FIG. 2 is a front view of the pressurized spacer of FIG. FIG. 3 is a side view of another embodiment of the pressurized spacer. FIG. 4 is a side view of the pressurized spacer of FIG. FIG. 5 is a load-deformation characteristic diagram of the pressurized spacer. FIG. 6 is a sectional view of a bearing housing of the turbocharger. FIG. 7 is an enlarged view of a portion of the angular ball bearing of FIG. FIG. 8 is a schematic perspective view of a portion of the angular ball bearing of FIG. FIG. 9 is a diagram showing a relationship between an engine rotation speed and an intake pipe pressure in an angular ball bearing and a float bearing. 10 and 11 are diagrams similar to FIGS. 7 and 8 in another embodiment. FIG. 12 and FIG. 13 show FIGS. 7 and 8 in still another embodiment.
FIG. 10 ... bearing housing, 12 ... turbine wheel shaft, 14 ... turbine wheel, 16 ... compressor wheel, 20 ... angular contact ball bearing, 22 ... inner ring, 24 ... outer ring, 26 ... ball, 40 ... End plate, 46 ... Annular member, 50 ... Seal, 56 ... Inner spacer, 60 ... Pressurized spacer, 62 ... Slit, 67 ... Refueling port, 69 ... Recovery chamber, 70 ... Slit, 80: Oil introduction hole, 81: Annular groove, 82: Oil supply hole, 88: Annular projection, 90: Annular damper.

Claims (1)

(57) [Claims] In a turbocharger in which a turbine wheel shaft is supported by a bearing housing by a pair of angular ball bearings, a slit extending in a direction intersecting the turbine wheel axis is formed between opposed outer rings of the pair of angular ball bearings. A bearing structure for a turbocharger, comprising a pressurized spacer.