JPH0335497B2 - - Google Patents

Abstract

PURPOSE:To prevent deterioration of lubricating oil in a bearing part, by introducing a jet stream of high pressure gas to a floating bearing part at stopping of an engine and blowing the lubricating oil accumulated in the bearing part with the jet stream to dry the bearing part. CONSTITUTION:During operation of an engine, a key switch 144 is placed in an ON position and a solenoid 132 is excited. This causes a shut off valve 134 to close. Intake air pressurized by a compressor of a turbocharger is partially accumulated in a surge tank 130 through a supercharge intake pipe 140. When the key switch is turned to an OFF position to stop the engine, an oil pump 108 is also stopped. Action of a delay timer 142 causes the solenoid 132 after opening of the key switch to open after elapsed a prescribed time, and high pressure air in the surge tank is injected toward an oil inlet pipe 112.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a turbocharged internal combustion engine, and more particularly to a device for protecting a turbocharger bearing during hot shutdown of the turbocharger.

In a turbocharger for a vehicle internal combustion engine, the compressor and turbine rotate at high speeds of up to about 100,000 revolutions per minute, so full floating bearings 10, 10, as shown in FIG. 1, are used as shaft bearings. An oil inlet pipe 11 connected to the engine's oil pump is screwed into a pipe connection port 13 provided in the main housing 12 of the turbocharger, and the lubricating oil is distributed to the oil supply hole 15 through the distribution hole 14 to each full-floating bearing. 10,10. As shown in an enlarged view in FIG. 2, the inner hole 16 formed in the main housing and the full floating bearing 1
A minute gap is formed between 0 and the turbocharger shaft 17, and this minute gap is formed during engine operation, and an oil film of lubricating oil is formed in this minute gap during engine operation. It functions to dampen and absorb shaft rotational vibrations. The lubricating oil also serves to cool the bearings, which are heated by the heat propagated from the engine's exhaust system.

When the engine stops, the rotation of the turbocharger stops, and the supply of lubricating oil from the oil pump stops.The lubricating oil in the turbocharger drips due to gravity and returns to the engine-operated oil van, but the fully floating bearing As shown in FIG. 3, lubricating oil remains in minute gaps. If the engine is stopped immediately after high-speed, high-load operation, such as when a vehicle is parked immediately after driving at high speed, the turbocharger rotation and lubricating oil may suddenly change while the exhaust system is heated to a high temperature. supply will be interrupted. This condition is called hot shutdown of the turbocharger. During a hot shutdown, the lubricating oil that remains in the tiny gaps in the fully floating bearing oxidizes due to the heat that gradually propagates from the highly heated exhaust system, turning into sludge or, in extreme cases, carbonizing. . In this specification, such change in quality of lubricating oil due to heat is broadly referred to as deterioration. The deteriorated lubricating oil adheres to or sticks to minute gaps in the bearing, leading to a lack of lubricating oil supply during the next engine operation and causing abnormal wear of the bearing.

An object of the present invention is to provide a bearing protection device that can prevent deterioration of lubricating oil in a fully floating bearing even during hot shutdown of a turbocharger.

In order to achieve the above object, the present invention introduces a high-pressure gas jet into a fully floating bearing when the engine is stopped, blows away the lubricating oil accumulated in the bearing, and dries the bearing. The aim is to prevent deterioration of lubricating oil.

For this reason, the bearing protection device of the present invention includes a pressurized gas source, one end connected to the pressurized gas source, and the other end communicated with the full floating bearing of the turbocharger, and the pressurized gas is transferred from the pressurized gas source to the bearing. A pipe is installed in the pipe and is closed while the engine is running, blocking the flow of pressurized gas.When the engine is stopped, it is opened to allow the pressurized gas to pass through and be ejected to the bearing. The gist of the invention is that it is equipped with a shutoff valve that has become available.

In a specific embodiment of the invention, the source of pressurized gas may consist of a storage vessel, such as a surge tank, connected to the discharge side of the compressor of the turbocharger and adapted to store the boost pressure of the turbocharger. . A check valve can be provided between the storage container and the compressor discharge side to prevent the pressurized air in the container from flowing back to the compressor discharge side when the boost pressure decreases.

The other end of the pressure gas pipe may be opened directly into the bearing, but it is preferably connected to the oil inlet pipe of the turbocharger. In order to prevent the pressurized gas from flowing back toward the oil pump when it is ejected, it is preferable to provide the oil inlet pipe with a check valve upstream of the confluence point.

The shutoff valve may be a solenoid type electromagnetic valve connected to the engine key switch. The turbocharger shaft rotates elliptically for a short time even after the engine is stopped, but in order to blow out the lubricating oil only after this elliptical rotation is completed, a delay circuit may be provided between the key switch and the solenoid.

Hereinafter, embodiments of the present invention will be described with reference to the drawings, and the effects of the present invention will also be described.

FIG. 4 is an elevational view of a turbocharger and lubrication system incorporating one embodiment of the bearing protector of the present invention, with the fully floating bearing of turbocharger 100 being schematically indicated by dotted circle 102. The lubrication system for the engine body and the turbocharger is well known, and the lubricating oil in the oil pan 104 is sucked into the oil pump 108 through the suction pipe 106, passes through the filter 110, and is passed through the oil inlet pipe 112 for the turbocharger and the engine body. The oil is fed under pressure toward the oil supply pipe 114. A check valve 116 is installed in the inlet pipe 112. As already explained with reference to FIG. 1, this oil inlet pipe 112 is screwed into an inlet pipe connection port formed in the main housing 118 of the turbocharger 100.
Lubricating oil is supplied to the bearing portion 102 through a distribution hole and an oil supply hole (see FIG. 1) in the main housing. The oil that has lubricated the bearing portion is returned to the oil pan through a return pipe 120. On the other hand, the lubricating oil that has lubricated the bearing portion 122 of the engine body through the oil supply pipe 114 returns to the oil pan through an appropriately formed return pipe 124.

A supercharging air duct 128 is attached to a compressor discharge port 126 of the turbocharger 100, and this supercharging air duct is connected to an intake manifold (not shown) of the engine.

Dedicated surge tank 13 in appropriate parts of the engine
0 is set. This surge tank 130 is connected to the oil inlet pipe 112 by a pressurized air line 136 equipped with an electromagnetic shutoff valve 134 having a solenoid 132. Pressure air piping 13
A supercharging air intake pipe 140 equipped with a check valve 138 is connected between the supercharging air duct 128 and the supercharging air duct 128 .

The solenoid 132 of the electromagnetic shutoff valve 134 is connected to the delay timer 142 and the engine key switch 1.
44 to a power source 146.

Next, to describe the operation of the device of the present invention,
When the engine is operating, key switch 144 is in the ON position and solenoid 132 is energized.
Therefore, the shutoff valve 134 is closed. A portion of the intake air pressurized by the turbocharger compressor is stored in the surge tank 130 via the supercharging air intake pipe 140. Supercharging air intake pipe 140
Since the check valve 138 is provided in the surge tank, the maximum supercharging pressure reached during turbocharge operation is stored in the surge tank. Also, the higher the engine speed, the higher the boost pressure generated.
The more heat the bearing receives during a hot shutdown, the more high pressure air is stored in the surge tank.

When the key switch is turned to the OFF position to stop the engine, the oil pump 108 also stops, and the lubricating oil pressure in the lubrication system disappears. Further, the compressor and turbine of the turbocharger rotate inertia for a short time after the engine stops, and then eventually stop. Due to the action of the delay timer 142, the solenoid 132 is opened a predetermined time after the key switch is opened, and the high pressure air in the surge tank is blown out toward the oil inlet pipe 112. Since a check valve 116 is provided on the upstream side of the oil inlet pipe, the jet of air passes through the inlet pipe connection port, distribution hole, and oil supply hole and is blown onto the fully floating bearing without flowing back to the oil pump side. It will be done. As a result, the lubricating oil adhering to the gap in the bearing portion is blown off as shown in FIG. Therefore, even if heat is transferred from the exhaust system to the bearing during a hot shutdown, the lubricating oil will not remain in the bearing, causing problems such as sticking, sludge, or carbonization of the lubricating oil. There is no. Note that the larger the amount of heat received in the bearing, the lower the viscosity of the lubricating oil, so the effect of blowing off the lubricating oil by the air jet is greater. Furthermore, an air cooling effect can be expected by blowing air onto the bearing portion.

As described above, according to the device of the present invention, deteriorated lubricating oil is prevented from staying in the fully floating bearing portion during hot shutdown, and roughening and abnormal wear of the bearing are avoided. In addition, since this device automatically operates when the engine is stopped, there is no need to take troublesome driving precautions such as "after high-speed, high-load operation, the engine should be idled for a while and then stopped."

[Brief explanation of the drawing]

Figure 1 is a reference diagram showing a vertical cross section of the turbocharger, Figure 2 is a cross-sectional view of the bearing showing the lubrication state when the engine is running, Figure 3 is a cross-sectional view of the bearing when the engine is stopped, and Figure 4 is the main FIG. 5, which is an elevational view of the device of the invention, is a sectional view of the bearing portion illustrating a state in which lubricating oil from the bearing portion is blown off. 100...Turbo charger, 102...Full floating bearing, 112...Oil inlet pipe, 116...Check valve, 126...Compressor discharge port, 128...Supercharging air duct, 130...Surge tank, 132...Solenoid of electromagnetic shutoff valve , 13
4...Solenoid shutoff valve, 136...Pressure air piping, 13
8...Check valve, 140...Supercharging air intake pipe, 142...
Delay timer, 144...Engine key switch.

Claims (1)

[Scope of Claims] 1. A pressure gas source, one end connected to the pressure gas source and the other end communicating with the full floating bearing of the turbocharger so as to guide the pressure gas from the pressure gas source to the full floating bearing. The piping is interposed in the piping and is closed while the engine is running, blocking the flow of pressurized gas, but when the engine is stopped, it is opened to allow the pressurized gas to pass through and eject into the fully floating bearing. When the engine is stopped, the lubricating oil that remains in the full-floating bearing is blown away by a jet of pressurized gas, thereby preventing lubrication in the full-floating bearing during hot shutdown of the turbocharger. A full floating bearing protection device for a turbocharger, characterized in that it is capable of preventing oil deterioration. 2. The pressure gas source consists of a storage container connected to the discharge side of the compressor of the turbocharger so as to be able to accumulate the supercharging pressure of the turbocharger, and the supercharging pressure is reduced between the storage container and the compressor discharge side. 2. The bearing protection device according to claim 1, further comprising a check valve for preventing the pressurized air accumulated in the container from flowing back to the compressor discharge side when the compressor is compressed. 3 The other end of the piping is connected to the oil inlet pipe of the turbocharger, and this oil inlet pipe is provided with a check valve upstream from the confluence with the piping to prevent the pressurized air from blowing out. 3. The bearing protection device according to claim 2, wherein the bearing protection device is configured to prevent backflow toward the upstream side. 4 The above-mentioned shutoff valve is an electromagnetic shutoff valve having a solenoid, and the solenoid is energized to close the shutoff valve when the key switch of the engine is turned on, and demagnetized to open the shutoff valve when the key switch is turned off. 4. The bearing protection device according to claim 3, wherein the bearing protection device has a curved shape. 5. A delay circuit is inserted between the engine key switch and the solenoid, so that the shutoff valve opens after a predetermined time has elapsed after the engine is stopped, and pressurized air can be ejected. A bearing protection device according to claim 4.