JPH037541Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a device for preventing lubricating oil from flowing out when an exhaust turbine is damaged in a turbocharger for supercharging an engine.

(Prior art) It is well known that the intake air is supercharged with the aim of increasing the output of an internal combustion engine, but for this purpose there is a turbocharger that uses the exhaust energy of the engine to supercharge (for example, "turbocharger"). (Refer to ``Theory and Practice,'' translated by Ichiro Sakurai, published by Railway Japan Co., Ltd., July 1, 1981).

The structure of this turbocharger will be explained based on FIG. 4.

An exhaust turbine 1 that rotates in response to exhaust gas from an engine has a turbine rotor 3 disposed inside a turbine housing 2, and an impeller 6 of an intake compressor 5 coaxially connected to the turbine rotor 3 via a rotating shaft 4. , an impeller 6 rotates integrally with the turbine rotor 3 inside the compressor housing 7, supercharging air into an engine intake passage (not shown). The rotating shaft 4 is rotatably supported by a bearing housing 8 via float metals 9 and 10, and the float metals 9 and 10 are supplied with engine lubrication via a lubricating oil supply passage 11 formed in the bearing housing 8. Some of the oil is supplied. The oil that has lubricated the float metals 9 and 10 is returned from the outlet 12 of the bearing housing 8 to the oil pan of the engine.

A thrust collar 13 is attached to the intake compressor 5 side of the rotating shaft 4, and contacts a thrust metal 14 fixed to the bearing housing 8 to hold the rotating shaft 4 so that it does not move in the axial direction.

Further, a seal ring 15 is fitted on the exhaust turbine 1 side of the rotary shaft 4 to provide a seal to prevent lubricating oil from flowing out from between the rotary shaft 4 and the inner periphery of the bearing housing 8 to the turbine rotor 3 side.

Note that a heat insulator 16 is attached to the bearing housing 8 at the back surface of the turbine rotor 3 so that the heat of the turbine rotor 3 is not directly transferred to the bearing side.

The rotation of the turbine rotor 3 of the turbocharger increases to tens of thousands of revolutions per minute, depending on the operating conditions of the engine, and therefore a large amount of lubricating oil is supplied to the bearing portion of the rotating shaft 4, that is, the float metals 9 and 10. Normally, a portion of the lubricating oil from the engine is sent from the supply passage 11 to the float metals 9 and 10 to forcibly lubricate the rotating shaft 4 to prevent it from seizing.

(Problems to be solved by the invention) Since the turbine rotor 3 comes into contact with high-temperature exhaust gas, it is common to use a heat-resistant alloy due to the need for heat resistance and high-temperature strength. For the sake of measurement, it has been proposed to manufacture the turbine rotor 3 using ceramics such as silicon nitride and silicon carbide, which are lighter and have better heat resistance than conventional heat-resistant alloys (for example, Japanese Patent Laid-Open No. 57
-Refer to Publication No. 88201).

In this case, a part of the rotating shaft 4 is also connected to the turbine rotor 3.
It is made of ceramics that are integrated with the metal shaft, and a metal shaft is joined in the middle.

However, the turbine rotor 3 made of ceramics has some disadvantages in impact resistance compared to heat-resistant alloys, and in extreme cases, if severe vibration or thermal shock is applied, the turbine rotor 3 or the rotating shaft may be damaged. It is also assumed that part of 4 may be damaged.

In the unlikely event that the turbine rotor 3 is damaged, a large amount of the lubricating oil supplied to the float metal 9 will leak out to the exhaust turbine 1 side, and the engine (prime mover) that shares the lubricating oil with the turbocharger will be lubricated. This causes problems such as oil shortage.

Note that even if a turbine rotor is made of metal material, it may be damaged due to thermal fatigue, for example, although it may not be as severe as that of a ceramic turbine rotor, so the same damage prevention measures as for ceramic turbine rotors should be taken. It is necessary to apply

On the other hand, for example, Japanese Patent Application Laid-Open No. 123719/1983 discloses a system that detects damage to the turbocharger from an abnormal drop in rotation of the turbocharger or a drop in pressure of the lubricating oil, and stops the supply of lubricating oil. The technology has been disclosed. However, since the turbocharger rotation does not decrease until the lack of lubricating oil has progressed to a considerable extent, stopping the supply of lubricating oil after detecting a decrease in rotation cannot reliably prevent engine seizure. In addition, in the case of oil pressure detection, it may not be possible to promptly detect a drop in oil pressure due to clogging of the hydraulic system, etc., and in any case, there is a drawback that it is not reliable as a means of detecting damage to the supercharger. It was hot.

The present invention has been made in view of the above-mentioned conventional problems, and is aimed at reliably preventing leakage of lubricating oil when a turbine rotor is damaged.

(Means for Solving the Problems) The present invention includes: an exhaust turbine driven by engine exhaust gas; an intake compressor connected to the exhaust turbine via a rotating shaft for supercharging intake air;
A turbocharger comprising a supply passage for supplying a portion of engine lubricating oil to a bearing of the rotating shaft,
means for detecting the temperature of the bearing section of the exhaust turbine; supply passage blocking means for cutting off the supply of lubricating oil to the bearing; and supply passage blocking means when the temperature of the bearing section rises to a value equivalent to the exhaust temperature. and control means for driving the means to cut off the supply of lubricating oil to the bearing.

(Function) When the turbine rotor of the exhaust turbine is damaged, the bearing portion is exposed to the exhaust gas, so the temperature of the bearing portion rapidly rises to a value equivalent to the exhaust temperature, which exceeds the maximum temperature of the bearing portion during normal operation. Therefore, based on the above configuration, when the turbine rotor is damaged, the control means detects this from the temperature rise and immediately shuts off the lubricating oil supply passage. This quickly prevents a large amount of lubricating oil from leaking to the exhaust turbine side, and at least prevents the engine's lubrication system from running out of lubricating oil, thereby preventing engine seizure. .

(Example) Examples of the present invention will be described below based on the drawings. Note that the same parts as in FIG. 4 are designated by the same reference numerals.

In FIG. 1, exhaust gas from an engine main body 20 flows into the exhaust turbine 1 through an exhaust passage 21 and drives the exhaust turbine 1 to rotate. The intake compressor 5 is rotated by the exhaust turbine 1 and feeds pressurized air into the engine body 20 via the intake passage 22.

A first electromagnetic valve 24 is interposed in the middle of the passage 23 that supplies lubricating oil from the engine body 20 to the supply passage 11 of the bearing housing 8 as a means for shutting off the lubricating oil. A second solenoid valve 26 is also interposed in the passage 25 that returns lubricating oil from the section 12 to the engine body 20, and these solenoid valves 24, 26 are connected to the control circuit 27 which functions as the above-mentioned control means when the turbine rotor 3 is damaged. In response to this signal, the valve is closed to block the passages 23 and 25.

In order to detect damage to the turbine rotor 3, a temperature sensor 29 is provided to detect the temperature near the float metal 9 on the exhaust turbine 1 side of the bearing housing 8. Furthermore, in this embodiment, as auxiliary means for detecting damage, a pressure sensor 28 for detecting the supercharging pressure in the intake passage 22 and a rotation speed sensor 30 for detecting the engine speed are provided. A signal is input to the control circuit 27.

In the control circuit 27, the relationship between the boost pressure corresponding to the engine speed and the temperature of the bearing section at that time are set in advance, and the boost pressure is low compared to the engine speed.
On the other hand, if the temperature of the bearing section is high, it is determined that the turbine rotor 3 or the like is damaged, and a signal is output to close the electromagnetic valves 24 and 26.

The temperature that serves as the criterion for damage to the bearing described above is the equivalent value of the exhaust temperature, but this is specifically set to a higher value since the maximum temperature of the bearing during normal operation is approximately 120°C. Just do it.
Taking a gasoline engine as an example, the exhaust temperature is generally around 250℃ even immediately after a complete explosion, and when idling.
250~300℃, reaching around 900℃ at full load,
It becomes possible to reliably determine whether there is an abnormality in the turbine by comparing the temperature with the normal temperature of the bearing.

The device is configured as described above, and its operation will be explained next.

If the turbine rotor 3 of the exhaust turbine 1 is damaged during engine operation and the damage extends to the root or rotating shaft 4, the boost pressure will drop rapidly and the exhaust gas will flow from the damaged part to the bearing housing 8. It also flows into the interior, causing the temperature near the float metal 9 to rise significantly.

Then, the control circuit 27 detects a decrease in boost pressure compared to the engine speed and an increase in the temperature of the bearing portion, determines that the turbine rotor 3 is damaged, and closes the electromagnetic valves 24 and 26 to resume lubrication. It cuts off the oil supply and prevents exhaust gas from flowing back into the oil pan of the engine body 20.

As a result, a large amount of lubricating oil from the engine body 20 is prevented from flowing out from the exhaust turbine 1 to the exhaust system, and a situation where the lubricating oil in the engine body 20 is insufficient is avoided, thereby preventing the engine from seizing up. prevent.

It also prevents deterioration of lubricating oil and engine misfires due to backflow of exhaust gas into the oil pan.

By the way, in this embodiment, damage to the turbine rotor 3 is basically detected by monitoring the supercharging pressure and the temperature rise of the bearing portion in relation to the engine speed, but this idea also has the following effects: As explained above, it is possible to detect damage to the turbine rotor 3 only from the temperature rise in the bearing portion. However, if the supercharging pressure is detected as described below, more precise control can be performed depending on the state of damage to the turbine rotor 3.

In other words, if the damage to the turbine rotor 3 is minor, the damage may be limited to only the blades of the turbine rotor 3, and the exhaust turbine 1 may continue to rotate, but in this case, the supply of lubricating oil may It is not preferable to stop the rotating shaft 4 because it may cause seizure of the rotating shaft 4. In such a state, although the boost pressure decreases compared to the engine speed, the temperature of the bearing portion of the bearing housing 8 does not particularly rise, and therefore the control circuit 27
determines the output of the temperature sensor 29 and operates the solenoid valve 24,
26 is held in an open state to continue supplying lubricating oil to prevent seizure of the rotating shaft 4.

In this case, since the supercharging pressure does not increase compared to the engine speed, an abnormality in the turbocharger may be determined and notified to the driver.

FIGS. 2 and 3 show other embodiments of the present invention.
In this embodiment, a means for detecting damage to the turbine rotor 3 based on the temperature of the bearing portion on the exhaust turbine 1 side and a means for cutting off lubricating oil at the time of this detection are mechanically linked.

A cutoff valve 34 is interposed in the lubricating oil supply passage 11 near the float metal 9 on the exhaust turbine 1 side, and a coil spring 36 made of a shape memory alloy is provided in conjunction with the spool 35 of the cutoff valve 34. The other end of 36 is connected to an adjustment screw 37 screwed into the bearing housing 8.

The coil spring 36 is normally extended as shown in FIG. 3A, and the spool 35 is connected to the supply passage 11.
However, when the turbine rotor 3 is damaged, high-temperature exhaust gas flows backward and the temperature near the float metal 9 rises. This is sensed and the coil spring 36 contracts as shown in FIG. 3B. A spool 35 is adapted to close the supply passage 11. In this way, when the turbine rotor 3 is damaged, lubricating oil can be prevented from leaking to the float metal 9 on the exhaust turbine 1 side.

(Effects of the invention) As described above, according to the invention, when the turbine rotor is damaged, this is detected from the rise in temperature of the bearing and the lubricating oil supply passage is immediately shut off. It is possible to quickly prevent a large amount of engine lubricating oil from flowing out into the exhaust system from the bearing portion into which the lubricating oil is fed, and it is possible to prevent the engine from running out of lubricating oil or seizing.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of one embodiment of the present invention, Fig. 2 is a sectional view of another embodiment, and Figs. 3A and 3B respectively show the AA cross section of Fig. 2 in different operating states. FIG. FIG. 4 is a sectional view of a conventional example. 1...Exhaust turbine, 3...Turbine rotor,
4...Rotating shaft, 5...Intake compressor, 6...
Impeller, 8...Bearing housing, 9,1
0...Float metal, 11...Supply passage, 20
... Engine body, 21 ... Exhaust passage, 22 ... Intake passage, 23, 25 ... Passage, 24, 26 ... Solenoid valve, 27 ... Control circuit, 28 ... Pressure sensor, 2
9... Temperature sensor, 30... Rotation speed sensor.

Claims (1)

[Scope of utility model registration request] An exhaust turbine driven by engine exhaust gas, an intake compressor connected to the exhaust turbine via a rotating shaft for supercharging intake air, and a supply passage supplying a portion of engine lubricating oil to the bearing of the rotating shaft. a turbocharger comprising: means for detecting the temperature of a bearing of the exhaust turbine; supply passage blocking means for cutting off the supply of lubricating oil to the bearing; A lubricating oil spill prevention device for a turbocharger, comprising: control means for occasionally driving the supply passage blocking means to cut off the supply of lubricating oil to the bearing.