JP2007132317A - Supercharger - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a supercharger having excellent responsiveness and reliability by reducing the resistances of bearings and solving various problems in lubrication with an engine oil. <P>SOLUTION: This supercharger 1 comprises rolling bearings 6 supporting a rotating shaft 3 and an oil supply unit 10 supplying a lubricating oil to the rolling bearings 6. The oil supply unit 10 comprises a tank 21 storing the lubricating oil, pumps 22 sucking the lubricating oil in the tank 21 and discharging it to the outside, lubricating oil discharge nozzles 23 installed at the discharge ports of the pumps 22 and having the openings facing the insides of the rolling bearings 6, and a drive part 24 driving the pumps 22. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a turbocharger such as a turbocharger.

  The rotating shaft of a supercharger is generally supported by a bearing made of a floating metal because of high-speed rotation and a high temperature environment (Patent Document 1).

  However, from the viewpoint of energy saving and environmental protection, it is a problem to reduce the resistance of the bearing, and it is desired to use a rolling bearing as the bearing.

As shown in FIG. 5, a turbocharger using a rolling bearing has a housing (51), a turbine impeller (53) at one end, and a compressor impeller (54) at the other end. (52) and a pair of rolling bearings (55) and (56) holding a rotating shaft (52) have been proposed (Patent Document 2). The rolling bearings (55) and (56) are lubricated by engine oil, and the housing (51) has a branch passage (58) and (59) leading to the bearing arrangement space (P). An oil outflow passage (61) communicating with the oil discharge port (60) provided in the passage (57) and the bearing arrangement space (P) is provided. The housing (51) is also provided with a cooling jacket (62) at a position that avoids the oil passages (57), (58), (59), and (61) and is close to the turbine impeller (53).
Japanese Patent Laid-Open No. 5-141259 Japanese Patent Laid-Open No. 10-19045

  According to the supercharger of the above-mentioned patent document 2, it has advantages such as reduction of rotation loss and elimination of time lag compared to the case of using the floating metal of patent document 1, but the lubrication increases the amount of engine oil. The engine oil lubrication, such as the problem that the bearing torque increases and the power loss increases with this, and the life of the bearing decreases due to wear caused by foreign matter in the engine oil. There were various problems caused by the problem.

  In view of the above circumstances, an object of the present invention is to provide a turbocharger that is excellent in responsiveness and reliability by reducing the resistance of a bearing and solving various problems caused by engine oil lubrication.

  A turbocharger according to the present invention is a turbocharger having a turbine impeller at one end, a compressor impeller at the other end and a rotating shaft arranged in a housing, as a bearing device for supporting the rotating shaft, A pair of rolling bearings having an inner ring, an outer ring and a plurality of rolling elements are used, and an oil supply unit for supplying lubricating oil to the rolling bearings is provided. A pump that sucks and discharges the lubricating oil, a lubricating oil discharge nozzle that is provided at the discharge port of the pump and has an opening facing the inside of the rolling bearing, and a drive unit that drives the pump. To do.

  A very small amount (for example, 1 mL / h or less) of lubricating oil is supplied from the oil supply unit toward the rolling elements of the rolling bearing or the raceway surface of the inner and outer rings. In conventional turbochargers that use engine oil for lubrication, a large amount of engine oil is supplied to the rolling bearings. However, the place where the lubricating oil is required is a slight part of the contact area between the inner and outer ring raceways and the rolling elements. By supplying the lubricating oil only to the part, and supplying the lubricating oil toward the part, a sufficient lubricating effect can be obtained using a very small amount of lubricating oil.

  As a tank of the oil supply unit, for example, a reservoir tank dedicated to a supercharger is used. However, engine oil filtered by a filter can be supplied to the pump.

  The turbocharger is usually provided with a turbine (turbine impeller) at one end of a rotating shaft and a compressor (compressor impeller) at the other end, and the turbine has a high-temperature exhaust gas (for example, about 600 ° C.). Is supplied. In general turbochargers, there is a problem of turbo lag due to insufficient supercharging pressure (the time lag in the low-speed rotation range is long). To solve this problem, the use of variable nozzles that change the exhaust gas flow area A variable nozzle type that covers the low-speed rotation range by electronically controlling the flow rate of the exhaust gas blown to the turbine wheel, and a two-stage type that covers the low-speed rotation range by using both a small turbo and a large turbo Superchargers such as have been proposed. The configuration of the fueling unit of the present invention can be applied to an improved supercharger such as a variable nozzle type or a two-stage type in addition to a general supercharger. The supercharger may be for a diesel engine or a gasoline engine.

  The rolling bearing is, for example, an angular ball bearing, but is not limited thereto, and may be a deep groove ball bearing or other rolling bearing. The outer ring of the rolling bearing is attached to the housing by press fitting or the like, and the inner ring is fixed to the rotating shaft by press fitting or the like. The material of the bearing may be either ceramic or metal (such as bearing steel) and is not particularly limited.

  The housing does not require an oil passage for lubrication of the bearing, and accordingly, the degree of freedom in designing the housing is increased, and a housing shape for reducing the size and weight and reducing the temperature of the bearing arrangement space is adopted.

  In the supercharger according to the present invention, it is preferable that the opening direction of the nozzle is inclined in the direction of air flow generated by the rotation.

  The oil supply unit is usually mounted on the fixed side of the housing or the like. In this case, “inclined in the direction of air flow generated by rotation” is inclined in the direction of rotation relative to the direction of the rotation center axis. It means the same.

  Although it depends on the discharge capacity of the pump, the axial length of the nozzle is preferably 50 mm or less so as not to eliminate pulsation. When the nozzle diameter is too thin, it is difficult to discharge the lubricating oil, and when it is too thick, it becomes difficult to control the amount of one drop of oil. Therefore, the inner diameter dimension (diameter) of the nozzle is preferably 0.1 mm to 1 mm.

  The lubricating oil discharge nozzle includes, for example, a main body extending in the horizontal direction and a discharge portion that is bent substantially at right angles to the main body, and the discharge portion is directed in the air flow direction (rotation direction). Here, the direction of the discharge unit is not limited to the horizontal direction (parallel to the air flow direction), and may be inclined downward with respect to the main body. In this case, the angle α between the discharge part and the horizontal is appropriately determined within a range of 0 ° or more (or parallel to the air flow direction) and less than 90 ° (cannot be perpendicular to the air flow direction). The total length including the bent portion (discharge portion) of the nozzle is preferably 70 mm or less so as not to lose pulsation. And the length of the discharge part of a nozzle shall be about 5 to 60% of full length. The installation position of the lubricating oil discharge nozzle and therefore the installation position of the pump are not particularly limited, but are preferably below the tank.

  By tilting the opening direction of the nozzle in the direction of the air flow generated by the rotation, leakage of lubricating oil and movement of oil droplets in the opposite direction are prevented. The nozzle is preferably bent at the tip end side in the rotation direction, and the opening direction of the nozzle is preferably perpendicular to the rotation center axis direction.

  The opening of the nozzle needs to be positioned at least inward in the axial direction from the end face of the rolling bearing, and the opening of the nozzle is preferably positioned inward in the axial direction from the end face of the cage. .

  As the pump, for example, a diaphragm micropump in which a diaphragm, a lubricating oil discharge nozzle, and a lubricating oil suction nozzle are provided in a pump chamber and a piezoelectric element is attached to the diaphragm is suitable. This diaphragm type micro pump uses a piezoelectric element to pulsate the diaphragm and discharge the lubricating oil from the lubricating oil discharge nozzle. In addition to the diaphragm type, various pumps such as an injection pump, a vane pump, a screw pump, and a piezo pump can be used.

  If the nozzle length is too long, the pulsation of the lubricant generated by the pump is attenuated by the lubricant remaining in the nozzle, making it difficult for the lubricant to be discharged. In the vicinity of the rolling bearing. The vicinity means a position where the nozzle length is limited to a range in which the lubricating oil can be discharged by the pulsation of the lubricating oil, and the opening of the nozzle can face the vicinity of the raceway surface of the rolling element or the raceway member.

  The amount of lubricating oil discharged by the pump is controlled by the drive unit.For example, a very small amount of lubricating oil is transferred in a region where the rotational speed of the rotating shaft is low, and a corresponding amount of lubricating oil is transferred in a region where the rotational speed is high. It is discharged to the vicinity of the raceway surface of the moving body and inner and outer rings. In this way, it becomes possible to continuously supply the lubricating oil to the rolling element rolling region of the rolling bearing over a long period without excess or deficiency, thereby contributing to the long-term stabilization of rolling characteristics and the improvement of the service life.

  According to the supercharger of the present invention, since a rolling bearing is used as the bearing, the resistance of the bearing can be reduced, high-speed rotation is possible, and excellent responsiveness can be achieved. Also, since the rolling bearing is lubricated by the lubrication oil from the lubrication unit, there is no need to form an oil passage in the housing, greatly improving the freedom of housing design and using engine oil as the lubrication oil. In such a case, problems such as a decrease in the life of the bearing, which becomes a problem, can be solved. As the degree of freedom in housing design increases, the housing can be made thinner and a cooling jacket excellent in cooling efficiency can be easily formed, and the housing can be made smaller and lighter and the bearing arrangement space can be lowered. Further, since the amount of lubricating oil used for lubrication is very small, waste oil can be easily treated.

  Embodiments of the present invention will be described below with reference to the drawings. In the following description, the left and right in FIG.

  FIG. 1 shows a first embodiment of a supercharger according to the present invention. A supercharger (1) has a housing (2) and a turbine impeller (turbine) (4) at the left end, and a compressor impeller. (5) at the right end and a rotating shaft (3) disposed in the housing (2) and a pair of left and right supporting the rotating shaft (3) provided on the inner periphery of the housing (2) A rolling bearing (6) and an oil supply unit (10) for supplying lubricating oil to the rolling bearing (6) are provided.

  Each rolling bearing (6) is an angular ball bearing, and includes an inner ring (11) attached to the rotating shaft (3), an outer ring (12) attached to the housing (2), and both wheels (11) (12). It comprises a plurality of balls (13) disposed between them and a cage (14) for holding the balls (13).

  The oil supply unit (10) includes a tank (21) for storing lubricating oil, a pair of left and right pumps (22) that sucks the lubricating oil in the tank (21) and discharges it toward each rolling bearing (6), A lubricating oil discharge nozzle (23) provided at the discharge port of the pump (22) and a drive unit (24) for driving the pair of pumps (22) are provided.

  The tank (21) is a reservoir tank that stores lubricating oil dedicated to the supercharger.

  The pump (22) is a diaphragm pump that sucks the lubricating oil in the tank (21) into the pump chamber and discharges it from the nozzle (23) by reciprocally displacing the diaphragm, which is a driven part, by a piezoelectric element. .

  As shown in FIG. 2, the nozzle (23) has an L-shape consisting of a main body (25) extending in the horizontal direction and a discharge portion (26) bent substantially at right angles to the main body (25). . The opening of the nozzle (23), that is, the tip of the discharge part (26) is positioned inside the rolling bearing (6) so that there is at least a part of the nozzle (23) radially outward of the ball (13). Further, it faces a portion of the cage (14) (an axially inward position from the left and right end surfaces of the cage (14)). In the figure, the arrow indicates the rotation direction of the inner ring (11), and the opening of the discharge section (26) of the nozzle (23) is directed in the rotation direction.

  The drive unit (24) is provided with a power supply battery (or generator), a pump control circuit, and the like, and the pump (22) is driven by the voltage signal from the drive unit (24), and the pump (22) By sucking the lubricating oil from the tank (21), the lubricating oil is discharged from the nozzle (23) toward the ball (13), the raceway surface of the inner ring (11), and the raceway surface of the outer ring (12).

  The lubricating oil discharge amount is, for example, a very small amount of lubricating oil in an area where the rotational speed is low, and an amount of lubricating oil corresponding to that in an area where the rotational speed is high. In addition, a sensor for detecting the lubrication state of the rolling bearing (6) may be provided, and the amount of lubricating oil discharged by the pump may be controlled according to the output of the sensor.

  When the inner ring (11) rotates, a wind flow is generated by the rotation, which hinders proper supply of the lubricating oil. For example, the flow of wind generated by the rotation of the inner ring (11) acts similar to an air curtain, and as a result, when the opening of the nozzle (23) faces the end face of the rolling bearing (6), it drops. This air curtain prevents movement of the lubricating oil in the axial direction. This problem is solved by the opening of the nozzle (23) passing through the air curtain and facing a portion of the retainer (14) (on both end faces of the retainer (14)).

  However, when the nozzle is straight, there is a problem that the lubricating oil cannot be supplied to an appropriate location, particularly when used at a high speed. FIGS. 3 and 4 show an oil supply unit (30) using a nozzle (33) that is straight and whose opening direction is not inclined in the direction of air flow generated by rotation (FIG. 3 (a)), Compared with the oil supply unit (10) using the nozzle (23) (FIG. 3 (b)) of the first embodiment, the negative pressure at the tips of the nozzles (23) and (33) is shown in FIG. In addition, the straight shape (indicated by symbol (a)) significantly increases as the rotational speed increases, whereas that in the first embodiment (indicated by symbol (b)). The increase rate is extremely small, which proves useful particularly when used at high speed rotation. Further, as shown in FIG. 3A, in the case of a straight shape, the oil droplet (D) discharged from the nozzle (33) whose axial direction is orthogonal to the rotation direction indicated by the arrow is the nozzle (33 In the first embodiment, as shown in FIG. 3B, the nozzle (23) with respect to the rotation direction indicated by the arrow is observed. The axial direction of the discharge part (26) is directed in the same direction, and oil droplets (D) are held at the tip of the discharge part (26) of the nozzle (23) by the wind generated by the rotation. Done.

  Thus, according to this supercharger (1), it becomes possible to continuously supply the lubricating oil to the rolling region of the ball (13) of the rolling bearing (6) over a long period of time without excess or deficiency. Stabilization and lifetime improvement are achieved.

  The housing (2) is provided with a cooling jacket (7) which is concentric with the rotating shaft (3) and has a substantially the same axial length. The cooling jacket (7) is supplied with engine coolant (long life coolant).

  According to this turbocharger (1), as is clear from the comparison with the conventional turbocharger shown in FIG. 5, the housing (2) is not provided with an oil passage. ) Has a small thickness and a very simple shape, and a cooling jacket (7) is provided so that the entire bearing arrangement space can be cooled. Therefore, the cooling efficiency of the bearing arrangement space is extremely high, and the operating environment of each rolling bearing (6) is kept at a low temperature even though high temperature exhaust gas is supplied to the turbine (4). It is.

  The installation positions of the tank (21) and the pump (22) are not limited to the illustrated positions, and can be provided at any position on the inner periphery of the housing (2). The tanks (21) may be paired so as to correspond to the pair of pumps (22), respectively, or may be provided outside the housing (2). The tank (21) may be supplied with engine oil passed through a filter instead of storing lubricating oil dedicated to the supercharger. Since the amount of the lubricating oil used for the lubrication is very small, it can be easily treated by, for example, discharging it to an engine oil pan. Further, the description of the configuration of each rolling bearing (6) and the configuration of the springs and spacers arranged between the rolling bearings (6) is omitted, but various known configurations may be changed as they are or as appropriate. Can be used.

FIG. 1 is a longitudinal sectional view schematically showing one embodiment of a supercharger according to the present invention. FIG. 2 is a view of the main part of the present invention as viewed from the inside in the radial direction. FIG. 3 is a perspective view showing a comparison between a conventional oil supply unit (FIG. 1A) and an oil supply unit of the rolling bearing device according to the present invention (FIG. 3B). FIG. 4 is a graph comparing the magnitudes of negative pressure for two types of nozzle shapes. FIG. 5 is a longitudinal sectional view schematically showing a conventional supercharger.

Explanation of symbols

(1) Turbocharger
(2) Housing
(3) Rotating shaft
(4) Turbine impeller (turbine)
(6) Rolling bearing
(10) Lubrication unit
(11) Inner ring
(12) Outer ring
(13) Ball (rolling element)
(14) Cage
(21) Tank
(22) Pump
(23) Lubricating oil discharge nozzle
(24) Drive unit

Claims (3)

  In a supercharger having a turbine impeller at one end and a compressor impeller at the other end and having a rotating shaft disposed in a housing, an inner ring, an outer ring, and a plurality of rolling elements are used as bearing devices for supporting the rotating shaft. A pair of rolling bearings having a bearing is used, and an oil supply unit for supplying lubricating oil to the rolling bearings is provided. The oil supply unit sucks and discharges the lubricating oil in the tank for storing the lubricating oil. And a lubricating oil discharge nozzle provided at a discharge port of the pump and having an opening facing the inside of the rolling bearing, and a drive unit for driving the pump.   2. The supercharger according to claim 1, wherein each rolling bearing further includes a cage that holds a plurality of rolling elements, and the opening of the nozzle is positioned inward in the axial direction from the end surface of the cage.   The supercharger according to claim 1 or 2, wherein an opening direction of the nozzle is inclined in a flow direction of air generated by rotation.

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