JPS6233070Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a turbo supercharger that is driven by engine exhaust gas and supercharges intake air to the engine.

(Prior art) The exhaust pressure of the engine is used to rotate a turbine, and this turbine drives a blower.
Turbochargers that force air into an engine are becoming widely used in vehicles. When equipped with this turbo supercharger, even with the same size (displacement) engine, it is possible to obtain higher output than when not equipped with a turbo supercharger, improving vehicle performance and fuel efficiency per horsepower. It is used for such purposes.

In this case, since both the turbine and the blower are used in a fairly high speed rotation range, sufficient strength is required to withstand high speed rotation. Furthermore, since the turbine section becomes high temperature due to engine exhaust heat, the gap between the turbine and the inner peripheral surface of the turbine casing adjacent to it is designed to take into account the thermal expansion of these (turbine and turbine casing). However, they must be large enough that they do not interfere with each other. However, when the gap is made larger, the amount of exhaust gas passing through the gap and flowing out increases, resulting in a problem that the supercharging efficiency decreases.

On the other hand, since a turbocharger uses engine exhaust gas, the displacement varies depending on the engine rotation speed, and the pressure of the exhaust gas acting on the turbine increases as the displacement increases. Therefore, as the engine rotation increases, the exhaust pressure acting on the turbine also increases.
If the exhaust pressure acting on the turbine becomes too high, the supercharging pressure by the blower will also become higher than necessary, which is unfavorable in terms of engine strength and performance. As shown in the figure, the exhaust bypass passage connecting the main exhaust passage on the upstream side and the downstream side of the turbine is placed close to the main exhaust passage in which the turbine is installed in order to downsize and simplify the turbocharger. An exhaust system that is provided in a single turbine casing together with the main exhaust passage, and in which the exhaust bypass passage senses boost pressure downstream of the blower and opens the exhaust bypass passage when the boost pressure is equal to or higher than a predetermined value. It has been proposed to suppress the exhaust pressure acting on the turbine, in other words, the boost pressure, to a predetermined value or less by providing a bypass valve.

In this case, the vicinity of the exhaust bypass passage tends to become hotter than other parts due to the exhaust gas bypassed through the exhaust bypass passage, and the above-mentioned interference between the turbine and the inner peripheral surface of the turbine casing due to mutual thermal expansion results in the highest temperature. There was a problem that occurred frequently near the exhaust bypass passage.

(Purpose of the invention) In view of the above-mentioned problems, the present invention is designed so that the gap between the turbine and the inner peripheral surface of the turbine casing near the exhaust bypass passage is set according to the maximum thermal expansion, and the gap in other parts is set according to the maximum thermal expansion. The purpose of this invention is to provide a turbo supercharger with good supercharging efficiency by making the gap smaller than this set gap.

(Structure of the Invention) The turbocharger of the present invention is characterized in that the gap between the turbine and the inner peripheral surface of the turbine casing is set to be larger near the exhaust bypass passage than in other parts.

(Effects of the invention) According to the invention, the gap between the turbine and the inner circumferential surface of the turbine casing is large near the exhaust bypass passage where the temperature is highest, and becomes small in other parts where the temperature is lower than that near the exhaust bypass passage. Even if a difference in thermal expansion occurs due to a difference in temperature distribution on the inner circumferential surface of the turbine casing, which is heated during use, the gap between the turbine and the inner circumferential surface of the turbine casing can be set according to the thermal expansion. , the supercharging efficiency can be improved.

(Embodiment) FIG. 1 is a sectional view of a turbocharger according to an embodiment of the present invention.

The inlet port 1a that opens toward the outside in the turbine casing 1 is
The inside communicates with a space 1b formed to surround the outer circumference of the turbine 3, and this space 1b communicates with an outlet port 1c that opens to the outside in the axial direction of the turbine 3 via the turbine 3. A main exhaust passage 1 is formed in the turbine casing 1 from the inlet port 1a, the space 1b, and the outlet port 1c.
d is configured. The inlet port 1a communicates with an exhaust passage (not shown) of the engine, and the exhaust gas of the engine flows from the inlet port 1a into the space 1b and hits the blades of the turbine 3.
After rotating, it is discharged from the outlet port 1c.

In the blower casing 6, an inlet port 6a provided inside the blower 5 and open to the outside in the axial direction of the blower 5 communicates with a space 6b formed so as to surround the outer circumference of the blower 5 via the blower 5. It communicates with the outside through a port 6c that communicates with the space 6b, and the blower casing 6 is connected to the inlet port 6a, the space 6b, and the port 6c.
An intake passage 6d is defined inside.

The turbine casing 1 and the blower casing 6 face each other and sandwich the bearing casing 7, and the turbine casing 1 and the blower casing 6 are bolted to the bearing casing 7 so that the turbine 3, the blower 5, and the bearings 9, 9 are coaxial. It is attached by 8,8,... Furthermore, the shaft 4 supported by bearings 9, 9 in the bearing casing 7 is connected to the turbine 3 at one end and the blower 5 at the other end, and the rotation of the turbine 3 caused by exhaust gas is directly transmitted to the blower 5 by the shaft 4. The blower 5 is then driven. Therefore, air is forcibly sucked in by the blower 5 from the port 6a connected to the upstream side of the intake passage of the engine, and after passing through the space 6b, the air is supplied to the engine from the port 6c connected to the downstream side of the intake passage. Then, the engine is supercharged.

In the bearing casing 7, an internal space 7b communicates with the outside via an inlet port 7a and an outlet port 7c, and the bearing 9 rotates at high speed due to the lubricating oil flowing in from the inlet port 7a.
After the lubricating oil 9 and the shaft 4 have been lubricated, this lubricating oil flows out from the outlet port 7c.

Note that a gap is provided between the blade outer end 3a of the turbine 3 and the turbine casing inner circumferential surface 2 facing the blade outer end 3a in consideration of thermal expansion of each blade.

Fig. 2 is a side view of the turbocharger shown in Fig. 1 as seen from the turbine casing 1 side, and Fig. 3 shows the turbocharger cut along the line - in Fig. 2. FIG.

Exhaust bypass passages 11a and 11b are formed in the turbine casing 1 to communicate the space 1b and the outlet port 1c bypassing the turbine 3, and an exhaust bypass valve ( waste gate valve) 1
0 is provided in the exhaust bypass passages 11a and 11b. For this reason, the exhaust bypass passage 11a,
11b is connected to the upstream passage 1 by the exhaust bypass valve 10.
1a and a downstream passage 11b. The exhaust bypass valve 10 is activated when the supercharging pressure on the downstream side of the blower 5 exceeds a predetermined value, and the valve opens, thereby communicating the space 1b and the outlet port 11c through the exhaust bypass passages 11a and 11b. The boost pressure on the downstream side of the blower 5 becomes high when the engine rotates at high speed and the displacement increases, and at this time the exhaust gas temperature is also high. Therefore, when the engine rotates at high speed, the inner circumferential portion 1d of the turbine casing in the vicinity of the exhaust bypass passages 11a and 11b prevents high-temperature exhaust gas passing through the exhaust bypass passages 11a and 11b from passing through the turbine 3.
It is heated from both sides by high-temperature exhaust gas passing through the turbine casing, making it hotter than the other inner circumferential parts of the turbine casing. That is, the thermal expansion of the inner circumferential portion 1d of the turbine casing near the exhaust bypass passages 11a and 11b is larger than that of the other inner circumferential portions of the turbine casing.

Therefore, the turbine 3 is designed such that the gap C1 between the blade outer end 3a of the turbine 3 and the turbine casing inner circumferential surface 2 near the exhaust bypass passages 11a and 11b is larger than the gap C2 on the opposite side to the rotation center. The turbine 3 is mounted with its center of rotation 3b being eccentric by "E" with respect to the center 2a of the inner circumferential surface 2 of the turbine casing. In this way, when the inner peripheral surface 2 of the turbine casing is heated by exhaust gas and expands, the vicinity of the exhaust bypass passages 11a and 11b becomes hotter than other parts without significantly complicating the workability of the turbine casing 1. Even if the amount of expansion increases, interference between the outer blade end 3a of the turbine 3 and the inner circumferential surface 2 of the turbine casing can be prevented.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a turbocharger showing one embodiment of the present invention, FIG. 2 is a side view of this turbocharger,
FIG. 3 is a sectional view taken along the line - shown in FIG. 2. 1... Turbine casing, 3... Turbine,
4... Shaft, 5... Blower, 6... Blower casing, 7... Bearing casing, 9... Bearing,
10...Exhaust bypass valve, 11a, 11b...Exhaust bypass passage.

Claims (1)

[Scope of utility model registration request] The turbine installed in the main exhaust passage drives the blower installed in the intake passage to supercharge the intake air, and the turbocharging pressure on the downstream side of the blower in the intake passage provided near the main exhaust passage is maintained at a predetermined level. an exhaust bypass passage that causes exhaust gas on the upstream side of the turbine to bypass the turbine and flow to the downstream side of the turbine when the temperature exceeds a certain value, and the main exhaust passage are arranged in a single turbine casing in which the turbine is installed. In the turbo supercharger, the gap between the turbine and an inner circumferential surface of the turbine casing that is close to the turbine is set to be larger in the vicinity of the exhaust bypass passage than in other parts. feeding machine.