JPH0740099Y2 - Bearing structure - Google Patents

Description

[Detailed Description of the Invention] [Industrial field of application] The present invention relates to a radial type rolling bearing that supports a rotating shaft, and in particular, a hybrid (composite) bearing in which the inner ring of the rolling bearing also functions as a sliding bearing with respect to the rotating shaft. Regarding

[Conventional technology]

As a bearing for a high speed rotating shaft such as a turbocharger of an internal combustion engine, a so-called hybrid bearing of a composite type including a rolling bearing and a sliding bearing has been devised. In this hybrid bearing, for example, as shown in FIG. 4, a clearance is provided between an inner ring 2 of a rolling bearing (ball bearing in the example shown in the drawing) having an inner ring 2, a rolling element 3, and an outer ring 4 and a rotating shaft 1. By attaching the inner ring 2 to the shaft, the structure is similar to that of a floating bush bearing. The inner ring 2 which is floatingly attached as described above rotates at a speed lower than that of the rotating shaft 1 during rotation, and
Since the bearing is supported as a slide bearing, it is possible to reduce the rotation speed of the rolling bearing and improve the bearing life. Furthermore, the oil film formed between the inner ring 2 and the shaft 1 can provide the vibration damping effect of the shaft. It has the features that can be done.

As an example of the above hybrid bearing, Japanese Patent Laid-Open No. 272422/1986
Japanese Patent Publication No. 62-22321 and the like.

In the bearing disclosed in JP-A-61-272422, a clearance is provided between the inner ring of the ball bearing and the rotating shaft to float the inner ring, and an oil seal is provided between the outer ring and the inner ring on both end surfaces of the ball bearing. The lubricating oil supplied from the oil supply holes on the outer periphery of the outer ring does not flow out from both end surfaces of the bearing after lubricating the balls, and the inner ring and the rotating shaft slide along the radial oil supply holes provided on the inner ring. The feature is that it is supplied to the moving surface.

The bearing disclosed in Japanese Utility Model Laid-Open No. 62-22321 is characterized in that a rolling bearing inner ring is closely adhered to the outer periphery of a sliding bearing that supports a rotary shaft.

[Problems to be solved by the device]

The above-described hybrid bearing according to the prior art has excellent performance, but has a problem in securing the amount of oil supplied to the sliding bearing portion at high speed rotation. That is, in a normal rolling bearing, as a simple and reliable oil supply method, so-called oil is used to inject the lubricating oil from the nozzle provided in the vicinity of the bearing toward the end surface of the bearing and supply the lubricating oil to the rolling elements through the gap between the outer ring and the inner ring. Although a jet is used, when the oil jet lubrication method is used for the hybrid bearing, the lubricating oil supply amount to the sliding bearing may be insufficient at high speed rotation, and seizure may occur between the shaft and the bearing inner ring. Was there. Since the inner ring of the rolling bearing must function as a sliding bearing for the shaft, the clearance between the rolling bearing and the shaft must be set to a small value suitable for the sliding bearing. This is because only a quantity flows into this clearance portion and is not supplied to the sliding surface. Moreover, when the shaft is rotating at high speed, the lubricating oil ejected from the nozzle and hitting the shaft or the inner ring is scattered by the centrifugal force before flowing into the clearance part, so that the lubricating oil flowing into the clearance part The amount is further reduced, and even if the lubricating oil supply amount can be secured at low speed rotation, it is difficult to secure the supply amount at high speed rotation. In order to solve this problem, it is sufficient to increase the clearance between the inner ring of the rolling bearing and the rotating shaft, but in the conventional hybrid bearing, this clearance cannot be increased for the above-mentioned reason. It was necessary to set in the range of about 10 to 60μ.

The bearing disclosed in JP-A-61-272422 has the structure described above in order to solve this problem, and the lubricating oil supplied to the rolling bearing slips from the oil supply hole provided in the inner ring after lubricating the rolling elements. By supplying the lubricating oil to the bearing, it is possible to secure the amount of lubricating oil supplied to the sliding bearing even at high speed rotation.

However, according to the bearing structure of Japanese Patent Laid-Open No. 61-272422, although the problem of securing the amount of oil supply at high speed rotation can be solved, the lubricating oil supply method becomes complicated, and the ball bearing also has an end face seal and a radial direction oil supply hole. Moreover, there is a problem that the manufacturing cost is increased because a special shape is required. Further, in the above structure, there is a problem that the power loss of the bearing portion becomes large due to the fluid resistance acting on the rolling elements because the ball bearing is operated in a state where the lubricating oil is filled between the inner ring and the outer ring.

Also, in addition to the problem of lubricating oil supply, in the hybrid bearing according to the conventional technology, a clearance is provided between the rolling bearing inner ring and the rotating shaft, so that the shaft is supported below the bearing inner ring portion when the rotating shaft is stationary. Therefore, the shaft center moves lower than during rotation.For example, in a turbocharger or the like, it is necessary to take a large amount of this movement into consideration so that the clearance between the impeller tip of the turbine or compressor rotor and the casing must be large. It led to a decline.

In view of the above problems, the present invention does not require a complicated structure and uses the conventional oil jet lubrication method to ensure a sufficient amount of oil supply even at high speed rotation, and further, when the rotating shaft is stationary, the rotating shaft is concentric with the inner ring. It is intended to provide a hybrid bearing that can be retained in

[Means for Solving the Problems]

According to the present invention, an annular gap is provided between the inner ring of the rolling bearing and the rotary shaft, and an elastic plate formed in a tubular shape having a regular polygonal cross section is interposed in the gap, and in a low rotation region of the rotary shaft, ,
Due to its elasticity, the tubular elastic plate is inscribed in the rolling bearing inner ring at each ridge line portion and circumscribes the rotary shaft at each side face portion, and in the high rotation region of the rotary shaft, a centrifugal force acting on the tubular elastic plate. According to the above, there is provided a bearing structure characterized in that the bending rigidity of the elastic plate is set so as to form a gap between each side surface portion of the cylindrical elastic plate and the outer circumference of the rotating shaft.

[Action]

As described above, since the clearance between the rolling bearing inner ring and the rotary shaft is large, the amount of the lubricating oil injected into the bearing end surface by the oil jet lubrication method increases in the amount of oil flowing into the clearance. A sufficient supply amount of lubricating oil is secured even at high speed rotation.

When rotating at a low speed, the inner ring of the bearing and the rotating shaft are connected together by an elastic plate and rotate as a unit, but when the number of rotations increases, the elastic plate bends due to the action of centrifugal force, and the side surface of the cylinder with a polygonal cross section is outside. Since the bearing inner ring and the elastic plate that is inscribed on the inner surface of the bearing can be freely rotated with respect to the rotating shaft as it is expanded from the rotating shaft and separates from the rotating shaft, the sliding bearing can be placed between the elastic plate and the rotating shaft during high-speed rotation. To function as a hybrid bearing.

〔Example〕

FIG. 1 shows an embodiment in which the bearing according to the present invention is used for a high speed rotating shaft such as a turbocharger of an internal combustion engine. In the figure, the rotary shaft 1 is supported by a bearing 7 according to the present invention, and in the case of a turbocharger for an automobile engine or the like, the speed of the rotary shaft 1 reaches tens of thousands rpm. In this embodiment, the lubricating oil is injected and supplied from the lubricating oil passage 8 machined in the casing to the bearing 7 through the two nozzles 5 and 6, the nozzle 5 being a rolling bearing portion and the nozzle 6 being a sliding bearing portion. Lubricating oil is supplied to each.

FIG. 2 is a sectional view showing the structure of the bearing 7 of FIG. The bearing 7 is composed of a ball bearing having an inner ring 2, rolling elements (balls in this embodiment) 3, and an outer ring 4, and a leaf spring 10. The outer ring 4 of the ball bearing is, for example, a bearing box of a turbocharger housing. Fitted and fixed.
Further, a clearance (about 1 to 2 mm) larger than the clearance (about 10 to 60 μ) of the conventional hybrid bearing is provided between the inner ring 2 and the shaft 1, and the inner ring 2 has the leaf spring 10 inserted in this clearance. It is attached to the shaft 1 via.

The leaf spring 10 is formed by forming a flat plate made of an elastic material into a cylindrical shape having a regular polygonal cross section. In this embodiment, a thin metal plate is formed into a regular polygonal cross section (a regular octagonal shape in this embodiment) as shown in FIG. ) Is formed by bending into a tubular shape, and each side surface is provided with a slit 11 for passage of lubricating oil. The leaf spring 11 is inserted between the inner ring 2 and the shaft 1, and is inscribed in the inner ring 2 at the ridge line portion 12 of the cylinder, and in the stationary state of the rotary shaft 1,
Each side surface portion 13 of the cylinder circumscribes the rotating shaft 1, and holds the rotating shaft 1 concentrically with the inner ring 2 as shown in FIG. Therefore, when the shaft 1 is stationary, the shaft does not fall within the clearance between the inner ring and eccentricity.

The bearing according to the present invention operates as follows. When the rotary shaft 1 is stationary, the rotary shaft 1 is held by the inner ring via the leaf spring 10 as described above. However, even if the rotary shaft 1 starts to rotate, the leaf spring 10 keeps the inner ring 2 and the rotary shaft while the rotation speed is low. 1, and the inner ring 2 rotates together with the rotating shaft 1. Therefore, the rotating shaft 1
There is no speed difference between the inner ring 1 and the inner ring 1, and the bearing functions only as a ball bearing.

However, the centrifugal force acting on the leaf spring 10 increases as the number of revolutions increases, and when the speed exceeds a certain speed, the side surface portion of the leaf spring 10
13 (FIG. 3) expands outward, the leaf spring 10 separates from the rotating shaft 1, and rotates together with the inner ring 2 to cause a slip between the rotating shaft 1 and the leaf spring 10. When the number of revolutions further increases, the leaf spring 10 and the inner ring 2 rotate at a lower number of revolutions than the speed of the rotary shaft 1, and the side surface portion 13 of the leaf spring 10 flexes outward in an arc shape by the centrifugal force to support the rotary shaft 1. Functions as a multi-circle bearing.
Even in this state, since the clearance between the rotating shaft 1 and the inner ring 2 at the bearing end surface is large, a sufficient amount of lubricating oil is generated by the oil jet ejected from the nozzle toward the bearing end surface.
It is supplied between 10 and the rotary shaft 1.

Further, the speed difference between the rotary shaft 1 and the leaf spring 10 in the above-mentioned rotating state, that is, the rotation speed of the ball bearing inner ring 2 is determined by the amount of clearance between the rotary shaft 1 and the leaf spring 10 caused by the deflection of the leaf spring 10. However, the amount of deflection of the leaf spring 10 can be changed by adjusting the bending rigidity of the leaf spring 10 and the biasing force when the leaf spring 10 is first mounted on the shaft 1, and the ball bearing at the rated rotation. The number of rotations can be set arbitrarily.

Although the embodiment using the ball bearing has been described above, it goes without saying that the present invention is applicable not only to the ball bearing but also to other rolling bearings.

[Effect of device]

In the bearing according to the present invention, a large annular clearance is provided between the inner ring of the rolling bearing and the rotary shaft, and a leaf spring is interposed between the inner ring and the rotary shaft to form the bearing. It is possible to secure the supply of the lubricating oil to the sliding bearing portion at the time of high speed rotation by a simple method while using the oil supply system and the normal standard type rolling bearing.

Further, in the bearing according to the present invention, the rotating shaft is held concentric with the inner ring by the elastic plate even when the rotating shaft is stationary, and the rotating shaft does not become eccentric within the bearing clearance when stationary as in the conventional hybrid bearing. The clearance of each part can be set small, and particularly when used for a turbocharger or the like, the turbocharger efficiency can be improved by reducing the clearance between the casing and the impeller tip.

Further, since the elastic plate and the lubricating oil around it provide a strong vibration damping effect on the shaft vibration, it is not necessary to separately provide a special vibration damping means.

Further, this vibration damping effect reduces the impact applied to the rolling bearing, which improves the durability of the rolling bearing.

Further, in the bearing according to the present invention, the rotational speed of the rolling bearing can be set arbitrarily by adjusting the bending rigidity of the elastic body, etc., so that the degree of freedom of selecting the rolling bearing can be expanded and the manufacturing cost can be reduced as compared with the conventional hybrid bearing. Is.

[Brief description of drawings]

1 is a sectional view of an embodiment of the bearing of the present invention, FIG. 2 is an enlarged view of the bearing of the above embodiment, FIG. 3 is a perspective view of the leaf spring 10 of FIG. 2, and FIG. It is a partial cross section figure which shows a hybrid bearing. DESCRIPTION OF SYMBOLS 1 ... Rotating shaft, 2 ... Inner ring, 3 ... Rolling element, 4 ... Outer ring, 5 ... Nozzle, 6 ... Nozzle, 7 ... Bearing, 8 ... Lubricating oil passage, 10 ... Leaf spring, 11 ... Slit, 12 ... Ridge portion, 13 ... Side part.

Claims (1)

[Scope of utility model registration request] 1. An annular gap is provided between an inner ring of a rolling bearing and a rotary shaft, and an elastic plate formed in a tubular shape having a regular polygonal cross section is interposed in the gap, and in a low rotation region of the rotary shaft, Due to its elasticity, the tubular elastic plate is inscribed in the rolling bearing inner ring at each ridge line portion and circumscribes the rotary shaft at each side face portion, and in the high rotation region of the rotary shaft, a centrifugal force acting on the tubular elastic plate. The bending rigidity of the elastic plate is set so that a gap is formed between each side surface portion of the cylindrical elastic plate and the outer circumference of the rotating shaft.