JPS6363731B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an exhaust turbine supercharger for an automobile, and more particularly to an oil temperature control device for lubricating oil thereof.

Conventional automotive superchargers use engine oil as lubricating oil, and the engine oil is supplied directly to the bearings of the supercharger. Engine oil is used to lubricate and cool high-temperature parts such as piston rings in engine cylinders, and to lubricate rotating parts of the engine, and the viscosity of the oil is relatively high. On the other hand, the drive shaft of a turbo-compressor supercharger that uses an exhaust turbine as its drive source rotates at extremely high speeds, and the rotational speed is particularly high in small-sized superchargers, so that the loss of the bearings accounts for a small proportion of the loss of the entire turbocharger. It's getting bigger. Bearing loss in sliding bearings used in small turbochargers is proportional to the viscosity of the oil, but as shown in Figure 1, the viscosity of the oil changes greatly depending on the oil temperature, especially when starting the engine or when the engine is running low. Under load, the oil temperature was low and bearing loss increased, resulting in a large drop in boost pressure. Also the second
The figure shows the effect of supercharger lubricating oil temperature on engine speed and supercharging pressure. That is, as shown in the figure, the influence of the oil temperature is large when the engine speed is low, and therefore it is desirable to raise the oil temperature as much as possible within the allowable range of the heat resistance of the bearing.

The present invention was invented in view of the above, and aims to keep oil viscosity low, reduce bearing loss, and improve supercharging performance.

In order to achieve the above object, the present invention makes use of the fact that the turbine side wall surface of the bearing casing is heated by engine exhaust gas. The oil is heated through a nearby oil heating chamber and then supplied to the bearing. In addition, when the engine is under high load, the engine oil becomes hot enough to be used as a lubricating oil for the supercharger, and if this high-temperature oil is further heated, the temperature may exceed the heat-resistant temperature of the bearings. The present invention is characterized by a configuration in which lubricating oil is directly supplied to the bearing portion of the supercharger by a valve without passing through the oil heating chamber.

An embodiment of the present invention will be described below with reference to FIGS. 3 and 4. Rotating shaft 1 of exhaust turbine supercharger
is supported by two radial bearings 3a, 3b and a thrust bearing 4 disposed within the bearing casing 2. An impeller 5 of an exhaust turbine serving as a driving source is connected to one end of the rotating shaft 1, and an impeller 6 of a turbo compressor serving as a supercharger is connected to the other end, and both impellers are connected to a bearing casing 2. It is installed inside the turbine casing and compressor casing 8. Engine oil is supplied to the lubricating oil supply hole 9 as lubricating oil for the bearing. A bypass valve 10 is disposed in a passage where the supply hole 9 directly communicates with the bearing portion, and this valve 10 is closed by a thermostat when the oil temperature is low, and opens when the oil temperature becomes high. The valve 10 opens, for example, at 70° C. or higher. Most preferably, it is formed to open at a temperature of 90°C or higher. Further, the supply hole 9 communicates with a heating chamber 12 formed near the wall surface of the turbine casing via a passage 9a. FIG. 4 shows a cross section of the heating chamber 12 perpendicular to the axial direction. This heating chamber 1
2 is formed in a spiral shape, and an inlet hole 13 of the passage 9a is opened at one end of the spiral chamber, and an outlet hole 15 is opened at the other end of the spiral chamber. , 3b and the thrust bearing 4. In addition, an escape hole 19 is opened in the middle (lower part) of the heating chamber 12, and this escape hole 19 communicates with the oil drain passage 18, so that a part of the oil that has flowed into the heating chamber 12 always flows out to the oil drain side. It's getting old. Reference numeral 18 denotes an oil drain passage, which communicates with an oil reservoir (not shown) of the engine.

In the exhaust turbine supercharger having the above structure, engine exhaust gas flows into the exhaust turbine, rotates the impeller 5, transmits this rotation to the impeller 6 of the turbo compressor via the rotating shaft 1, and the impeller rotates the impeller 5. Rotate 6,
Supercharge the engine with combustion air.

On the other hand, to supply oil to each bearing of the exhaust turbine supercharger, engine oil is supplied to the supply hole 9 as lubricating oil. If the temperature of this supplied oil is low, e.g.
When the temperature is below 70°C, the valve 10 is closed, so the supplied oil flows through the passage 9a and into the heating chamber 12 from the inlet hole 13, and this heating chamber 12 is formed near the wall of the exhaust turbine chamber. The inflowing oil is heated by the exhaust gas while flowing into the heating chamber 12 as shown by the arrow 14, and the heated oil passes from the outlet hole 15 through the passage 15a to the radial bearings 3a, 3b and The thrust bearing 4 is supplied with oil. The drained oil that lubricates each of the bearings 3a, 3b, and 4 drips due to its own weight, and is returned to the oil reservoir of the engine via the oil drain passage 18. In addition, if the temperature of the oil supplied to the supply hole 9 is sufficiently high, for example, 70
℃ or above, the valve 10 is opened, and the supplied oil is directly supplied to the radial bearings 3a, 3b and the thrust bearing 4 as shown by the arrow 17 through this valve passage without passing through the heating chamber 12. In addition, since the heating chamber has an escape hole 19 in the middle, a part of the oil always flows out to the oil drain side.
The oil flowing out from the escape hole 19 cools the bearing casing 2 appropriately, and prevents the temperature of the turbine side wall surface of the bearing casing 2 from becoming too high due to exhaust gas. By appropriately setting the diameter of the escape hole 19 so that the flow rate of the spilled oil is appropriate, the oil in the heating chamber 12 can be prevented from overheating and carbonized, and lubricating oil at an appropriate temperature can be supplied to each bearing part. Along with supplying
When the valve 10 is opened, the flow of oil in the heating chamber 12 is stagnated, thereby preventing the oil in the heating chamber 12 from being carbonized.

In addition, in the above explanation, the valve 10 has an oil temperature of
Although the circuit opened when the temperature was 70℃ or higher, the most desirable oil temperature was
Formed so that it opens when the temperature is 90℃ or higher.

As explained above, according to the present invention, the valve of the oil passage is automatically controlled according to the temperature of the lubricating oil supplied to the exhaust turbine supercharger, and when the oil temperature is low, the oil is directed to the vicinity of the turbine chamber wall surface. After being guided into a heating chamber installed in the oil tank and heated by exhaust gas, the oil is supplied to each bearing.If the oil temperature is high, the oil is automatically controlled by the valve mentioned above and is supplied directly to each bearing, bypassing the heating chamber. lubricating oil of appropriate viscosity is always supplied to each bearing. Therefore, it is possible to prevent an increase in bearing loss and improve the supercharging performance of the supercharger even when the engine is started or when the engine load is low. Also, according to an embodiment in which an oil relief hole is opened in the middle part of the heating chamber,
The oil does not get too hot in the heating chamber and carbonize, so the equipment always operates reliably and the reliability of the equipment is improved.

[Brief explanation of drawings]

Figure 1 is a diagram showing the relationship between lubricating oil temperature and viscosity, Figure 2 is a diagram showing the relationship between lubricating oil temperature and supercharging performance, and Figure 3 is an exhaust diagram showing an embodiment of the present invention. FIG. 4 is a vertical cross-sectional view of the turbine supercharger, and is an axis-perpendicular cross-sectional view of the turbine side wall surface of the bearing casing in FIG. 3. 1...Rotating shaft, 2...Bearing casing, 3a,
3b...Radial bearing, 4...Thrust bearing, 5
... Turbine impeller, 6 ... Compressor impeller, 9 ... Supply hole, 9a ... Passage, 10 ... Valve, 12 ... Heating chamber, 13 ... Inlet hole, 15 ...
Exit hole, 15a...passage, 18...exhaust passage, 1
9...Escape hole.

Claims (1)

[Scope of Claims] 1. In a supercharger in which an exhaust turbine is connected to one side of a rotating shaft supported by a bearing and a supercharging compressor is connected to the other side, (a) an oil heating chamber is provided near the wall surface of the turbine chamber, and (b) A valve that connects and communicates the oil heating chamber between a supply hole that supplies lubricating oil to each bearing of the supercharger and the bearing, and (c) bypasses the oil heating chamber. (d) The above valve opens when the oil temperature is high,
A lubricating oil control device for an exhaust turbine supercharger, characterized by having a structure that closes the valve when the oil temperature is low. 2. Claims characterized in that the heating chamber is provided with an escape port that communicates with the oil drain side at an intermediate location between the lubricating oil inlet hole and the lubricating oil outlet hole of the heating chamber. The lubricating oil control device for an exhaust turbine supercharger according to item 1.