JPH0331893B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a lubricating device for an exhaust turbocharger. FIG. 1 shows a schematic configuration of an internal combustion engine with an exhaust turbocharger. In the figure, a cylinder head 12 and an oil pan 13 are attached to a crankcase 11.

Exhaust gas flowing out from the cylinder head 12 flows into an exhaust turbocharger 15 through an exhaust pipe 14, and then is discharged to the atmosphere. The exhaust turbo supercharger 15 is lubricated by lubricating oil supplied through a lubricating oil pipe 16 from a main gear rally (not shown) provided in the crankcase 11, and the lubricating oil is supplied to the oil pan 13 through a drain pipe 17. be returned.

The internal structure of the exhaust turbo supercharger 15 is shown in FIG. The turbine housing 21 is attached to the bearing housing 22 with a V-clamp 24, and the compressor cover 23 is also attached to the bearing housing 22 with a V-clamp 25. The exhaust turbine blade 31 is fixed to the rotor shaft 32 by precision casting, and the thrust collar 33 and compressor blade 34 are fixed to the rotor shaft 32 by screws 35. The rotor shaft 32 is supported by floating bush type bearings 41 and 42 and a thrust bearing 43 split into two.

Lubricating oil from a lubricating oil pipe (not shown) is supplied from a lubricating oil inlet 51, and is supplied to the bearings 41, 42 and the thrust bearing 43 through a branch pipe provided in the bearing housing 22. Furthermore, the lubricating oil returned from each bearing collects at the drain outlet 52 and flows into the drain pipe 17 shown in FIG.

Note that exhaust gas from the exhaust pipe flows into the turbine casing 21 through the exhaust inlet 61.

Regarding the operation, when the engine is operating at maximum output, the temperature of the exhaust gas flowing in from the exhaust inlet 61 in FIG. 2 is as high as 600 to 700°C. This high-temperature exhaust heats the exhaust turbine blades 31, and the heat is transferred to the bearing 4 via the rotor shaft 32.
1 and 42 and the thrust bearing 43, increasing their temperature.

For this reason, in the exhaust turbocharger, a sufficient amount of lubricating oil is supplied to the bearings 41, 42 and the thrust bearing 43 to cool them and prevent the bearings from seizing or the lubricating oil from carbonizing due to high temperatures. Ensures normal operation.

Furthermore, the temperature of the lubricating oil supplied to the exhaust turbocharger is 80°C, and the kinematic viscosity coefficient ν is about 20cst (centistokes) as shown in Figure 3.
In the bearings 41, 42 and thrust bearing 43 shown in FIG. 2, the lubricating oil is heated to about 140° C. by the exhaust heat transmitted from the rotor shaft 32, as described above.

As a result, as shown in Figure 3, the kinematic viscosity coefficient ν
has decreased to about 5 cst, and bearing 4 of rotor shaft 32
1, 42 and the thrust bearing 43 are reduced to improve mechanical efficiency.

Further, at this time, the temperature of the lubricating oil that collects at the drain outlet 52 is around 140°C.

However, the above method has the following drawbacks.

As the engine slows down to partial load, the exhaust temperature decreases. Therefore, the amount of heat transmitted through the rotor shaft 32 and reaching the bearings 41, 42 and the thrust bearing 43 is reduced.

However, the pressure and temperature of the lubricating oil supplied to the exhaust turbocharger are the same as at the maximum output of the engine.

As a result, the amount of lubricating oil flowing into each bearing becomes almost the same as at the time of maximum output, and the lubricating oil temperature of bearings 41, 42 and thrust bearing 43 drops to about 100°C.

As a result, as shown in Fig. 3, the kinematic viscosity coefficient ν of the lubricating oil increases to approximately 10cst, which is more than twice the maximum output, increasing the friction loss of the bearings 41 and 42 and the thrust bearing 43, and deteriorating mechanical efficiency. This is causing a problem.

Further, at this time, the temperature of the lubricating oil that collects at the drain outlet 52 is around 100°C.

An object of the present invention is to provide a lubricating device for an exhaust turbocharger that can improve the mechanical efficiency of the exhaust turbocharger when the engine is under partial load, and is characterized by: However, in an exhaust turbocharged internal combustion engine, a lubricating oil passage from the engine to the exhaust turbocharger is provided to exchange heat between the exhaust gas of the exhaust turbocharger and the entire amount of lubricating oil flowing through the lubricating oil passage. a lubricating oil heater for heating the lubricating oil, an electric control valve provided in the exhaust gas passage to control the flow rate of the exhaust gas, and a temperature detector for detecting the temperature of the lubricating oil at the exhaust turbocharger outlet. The present invention further includes a controller which receives a detection signal from the temperature detector and transmits a valve opening control signal to the electric control valve.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 4 is an explanatory diagram showing one embodiment of the lubricating device according to the present invention.

In the figure, a lubricating oil heater 71 is provided in the middle of a lubricating oil pipe 16 from a main gear rally (not shown), and a heat insulating oil pipe 72 is connected to the exhaust turbo supercharger 1.
Supply lubricating oil to 5.

The lubricating oil heater 71 allows a portion of the exhaust gas discharged from the exhaust turbo supercharger 15 to flow in through the electric control valve 81, and heats the lubricating oil with the heat of the exhaust gas. That is, the electric control valve 81 is provided in the exhaust gas passage from the exhaust turbo supercharger 15 to the lubricating oil heater 71, and controls the flow rate of exhaust gas.
In 1, lubricating oil is heated by heat exchange with exhaust gas.

Further, a temperature detector 82 is installed at the inlet of the drain pipe 17 from the exhaust turbocharger 15, that is, at the outlet of the exhaust turbocharger, and its detection signal 83 is transmitted to the controller 84.

The controller 84 controls the opening degree of the electric control valve 81 using a valve opening degree control signal 85 .

Note that, unlike this device, it is also possible to provide a bypass path in the lubricating oil heater 71, provide an electric control valve in the bypass path, and eliminate the electric control valve in the exhaust system.

The operation in the case of the above configuration will be described.

When the engine is operating at maximum output, the temperature of the lubricating oil at the inlet of the drain pipe 17 of the exhaust turbocharger 15 is approximately 140°C, and this value is detected by the temperature sensor 8.
2, and the detection signal 83 is sent to the controller 8.
4 can be conveyed.

Therefore, a fully closed valve opening control signal 8 is sent from the controller 84.
5 is transmitted to the electric control valve 81, and the electric control valve 81 is fully closed. Therefore, the exhaust gas flowing through the lubricating oil heater 71 disappears, and the lubricating oil in the lubricating oil pipe 16 is supplied to the exhaust turbo supercharger 15 through the heat insulating oil pipe 72 at 80° C. without being heated.

When the engine speed is reduced to partial load, the exhaust temperature decreases, so the temperature of the lubricating oil at the inlet of the drain pipe 17 decreases to around 100°C.

At this time, this 100°C detection signal 83 is transmitted to the controller 84, so a valve opening control signal 85 for opening the valve is transmitted from the controller 84 to the electric control valve 81, and as a result, a portion of the exhaust gas is lubricated. The oil begins to flow through the oil heater 71.

Therefore, the lubricating oil in the lubricating oil pipe 16 is heated to 80° C. or higher and is supplied to the exhaust turbo supercharger 15 through the heat-insulating oil pipe 72. As a result, drain pipe 17
The temperature of the lubricating oil at the inlet increases. As a result, the temperature of the lubricating oil at the inlet of the drain pipe 17 is maintained at a substantially constant level of around 140° C., regardless of the rotational speed and load of the engine. Therefore, the temperature of the lubricating oil in the bearings 41, 42 and the thrust bearing 43 in the exhaust turbocharger 15 shown in FIG. 2 is maintained at 140° C., which is the same as when the engine is at its maximum output.

The above case has the following effects.

When the engine is operating at maximum power, the device according to the invention supplies lubricating oil at 80° C. to the exhaust turbocharger 15 in the same way as in the conventional device, so that the same function as in the conventional device is obtained.

Furthermore, when the engine speed is reduced to a partial load, in the device according to the present invention, lubricating oil heated to 80° C. or higher is supplied to the exhaust turbo supercharger 15, and the bearings 41, 42 and thrust bearing 43 shown in FIG. Since the lubricating oil temperature is kept at 140℃, the kinematic viscosity coefficient is 5cst
This reduces friction loss and improves mechanical efficiency.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram showing the schematic configuration of a conventional exhaust turbocharged engine, Fig. 2 is a sectional view showing the exhaust turbocharger, Fig. 3 is a diagram showing changes in the kinematic viscosity coefficient, and Fig. 4 The figure is an explanatory view showing a lubricating device for an exhaust turbo supercharger according to one embodiment of the present invention. 15... Exhaust turbo supercharger, 16... Lubricating oil pipe, 17... Drain pipe, 81... Electric control valve, 82... Temperature detector, 84... Controller.

Claims (1)

[Claims] 1 In an exhaust turbocharged internal combustion engine, a lubricating oil passage from the engine to an exhaust turbo supercharger is provided, and the exhaust gas of the exhaust turbo supercharger and the entire amount of lubricating oil flowing through the lubricating oil passage are exchanged with each other. A lubricating oil heater that heats the lubricating oil, an electric control valve provided in the exhaust gas passage to control the flow rate of the exhaust gas, and a temperature detector that detects the temperature of the lubricating oil at the outlet of the exhaust turbo supercharger. A lubricating device for an exhaust turbo supercharger, comprising: a controller to which a detection signal from the temperature detector is input and transmits a valve opening control signal to the electric control valve.