JPH0196438A - O2 sensor fixing structure for internal combustion engine having turbo-charger - Google Patents

Abstract

PURPOSE:To prevent thermal degradation of an O2 sensor and to improve durability by combining a main path and a waist gate path in front of the output of an exhaust fitting and arranging an O2 sensor fixing section in front of the combined section of the main path. CONSTITUTION:A main path 8 and a waist gate path 9 are combined at a combining section 6a in front of the outlet of an exhaust fitting 6. Since high temperature exhaust gas is bypassed to the waist gate path 9 under high speed heavy load, quantity of exhaust gas colliding against an O2 sensor 1 is reduced to about 60% of conventional level. Exhaust gas in the main path 8 which performed turbine work through a turbine wheel 3 has lower temperature than that of exhaust gas in the waste gate path 9. Consequently, thermal degradation of a detecting element in a shield tube 1a of the O2 sensor 1 is suppressed, and durability of O2 sensor can be improved without sacrifice of function under low speed rotation.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to an internal combustion engine equipped with a turbocharger.
Regarding sensor mounting structure.

(Prior Art) FIG. 2 is a partial sectional view showing a conventional 0□ sensor mounting structure for an internal combustion engine equipped with a turbocharger. 0. The sensor 1 detects the oxygen concentration in the exhaust gas after combustion using a detection element such as a zirconia element in the shield tube la, converts the difference between this oxygen concentration and the oxygen concentration in the atmosphere into an electromotive force, and generates an appropriate air pressure. It controls the fuel flow to the engine to achieve fuel efficiency. 0. In order for the sensor 1 to exhibit good responsiveness, the exhaust gas temperature must be set at a predetermined temperature, for example, approximately 350°C.
It is necessary to maintain the temperature above °C, so 02 sensor 1
The wastegate valve 5 must be installed in a position where the hot exhaust gas is exposed to the earliest possible time when the exhaust gas temperature is low at low rotation speeds. Wastegate actuator (
(not shown), and controls the supercharging pressure of the turbocharger 2 by bypassing the exhaust gas at the turbine inlet to the wastegate. Conventionally, the 0□ sensor is interposed between the turbine housing 4 and the exhaust pipe on the exhaust side of the turbocharger 2, and is attached to an exhaust finch 10 that connects these. The conventional exhaust fitting 10 is located in the wastegate passage 9
is configured as a single passage directly connected to the main passage 8.

(Problem to be Solved by the Invention) However, in the conventional 02 sensor mounting structure of an internal combustion engine equipped with a turbocharger, the exhaust gas shown by the arrow 7 from the exhaust manifold of the engine flows through the turbine wheel 3 and the main passage at low rotation speeds. It only passes through 8 and hits 0□ sensor 1, but the waste pulp 5
When the engine is opened at high speeds and high rotations, hot exhaust gas, which is a mixture of exhaust gas from the main passage 8 and exhaust gas from the wastegate passage 9, flows directly across the 02 sensor 1. Therefore, the 0□ sensor 1 is exposed to a large amount of high-temperature exhaust gas, and there is a problem in that the detection element is severely degraded by heat and its durability is poor.

The present invention has been made in view of the above circumstances, and is intended to prevent thermal deterioration of the 0□ sensor attached to the internal combustion engine equipped with a turbocharger and improve its durability. The purpose is to provide a sensor mounting structure.

(Means for Solving the Problems) In order to achieve the above object, according to the present invention, a main passage for exhaust gas passing through the turbine and a waste gate are provided inside an exhaust fitting coupled to a turbine housing of a turbocharger. Separately into a waste gate passage for exhaust gas passing through, the main passage and the waste gate passage are merged in front of the exit of the exhaust fissuring, and an 02 sensor is installed in front of the merging part of the main passage. □An 02 sensor mounting structure for an internal combustion engine including a turbocharger provided with a sensor mounting portion is provided.

(Function) At high speeds and high loads, the temperature of the exhaust gas in the main passage that passes through the turbine becomes lower than the temperature of the exhaust gas that passes through the wastegate passage by the amount of turbine work, and the temperature of the exhaust gas in the main passage that passes through the wastegate passage becomes lower by the amount of work done by the turbine. Exhaust gas flow rate decreases. The West Kate pulp valve is opened at high speed and high load, but at this time the Ot feedback control is normally stopped and does not affect the fuel supply amount control.

(Example) Hereinafter, an example of the present invention will be described in detail based on the accompanying drawings.

FIG. 1 shows the 0.0. FIG. 2 is a partial cross-sectional view showing an example of a sensor mounting structure. In an engine equipped with a turbocharger 2, the exhaust fitting 6 downstream of the turbine is
As shown in the figure, the main passage 8 is a passage for exhaust gas that has passed through the turbine wheel 3, and the waste gate passage 9 is a bypass passage for exhaust gas when the waste gate valve 5 is opened. The passage 8 and the waste gate passage 9 are joined at a joining part 6a in front of the exit of the exhaust fitting 6.

The 0□ sensor 1 is screwed and attached to the 02 sensor attachment part 6b provided in front of the merging part 6a in the main passage 8. Arrow 7 from the engine exhaust manifold
Exhaust gas shown by always flows in the main passage 8 from low rotation to high rotation, and flows in the waste gate passage 9 only during high load and high rotation.

Even at low engine speeds when exhaust gas does not flow into the waste gate 9, exhaust gas flows through the main passage 8, so the function of the 0□ sensor 1 is not impaired.

In addition, during the exhaust gas measurement mode, the 02 feedback control is set to an open loop, so the wastegate pulp 5 does not open, and this does not adversely affect the conditions for air-fuel ratio control by the 02 sensor 1, which is necessary for exhaust gas purification. do not have.

When the wastegate valve 5 is fully open, the ratio of the amount of exhaust gas flowing through the main passage 8 and the amount of exhaust gas flowing through the wastegate passage 9 is approximately 6:4. For this reason, conventionally, when the waste pulp 5 was fully opened, high-temperature exhaust gas from both the main passage 8 and the waste gate 9 directly hit the sensor 1, but in the present invention, at high speeds and high loads, high-temperature exhaust gas Since the exhaust gas is bypassed to the wastegate passage 9, the amount of exhaust gas hitting the 0□ sensor 1 is reduced to about 60% of the conventional exhaust gas. Furthermore, the temperature of the exhaust gas in the main passage 8 that has passed through the turbine wheel 3 and performed turbine work is lower than that of the exhaust gas in the wastegate passage 9. Therefore,
0□ Thermal deterioration of the detection element within the shield tube 1a of the sensor 1 is reduced, and the durability of the O2 sensor 1 is improved without impairing the function of the O2 sensor 1 during low rotation. In particular, in the case of low-power engines, the 02 sensor 1 should be kept as free as possible from the high-temperature exhaust gas at high speeds and high loads.
It is necessary that the z-sensor l has durability.

(Effects of the Invention) As described above, according to the present invention, the inside of the exhaust fitting coupled to the turbine housing of the turbocharger is connected to the main passage for the exhaust gas passing through the turbine and for the exhaust gas passing through the wastegate. A 0□ sensor mounting section that separates the main passage and the wastegate passage into a wastegate passage before the exit of the exhaust finch, and mounts a 0□ sensor in front of the merging part of the main passage. By providing 0□
It is possible to reduce the amount of high-temperature exhaust gas when the engine that corresponds to the sensor is at high speed and under high load, thereby reducing thermal deterioration of the detection element of the 02 sensor.

[Brief explanation of the drawing]

FIG. 1 is a partial sectional view showing an embodiment of the 02 sensor mounting structure for an internal combustion engine equipped with a turbocharger according to the present invention;
FIG. 2 is a partial sectional view showing a conventional 02 sensor mounting structure for an internal combustion engine equipped with a turbocharger. 1...O2 sensor, 2...turbocharger, 3...
... Turbine wheel, 4... Turbine housing,
5... Waste gate pulp, 6... Exhaust fitting, 6a... Merging section, 8... Main passage, 9... Waste gate passage. Applicant Mitsubishi Motors Corporation Agent Patent Attorney Kanji Nagado

Claims (1)

[Claims] The interior of the exhaust fitting coupled to the turbine housing of the turbocharger is separated into a main passage for exhaust gas passing through the turbine and a wastegate passage for exhaust gas passing through the wastegate, the main passage and the wastegate passage. An O_2 sensor mounting structure for an internal combustion engine equipped with a turbocharger, characterized in that the O_2 sensor mounting portion for mounting the O_2 sensor is provided before the merging portion of the main passage, and the O_2 sensor mounting portion is provided before the merging portion of the main passage.