JPH0435542Y2 - - Google Patents

Description

[Detailed description of the invention] [Field of industrial application] The present invention relates to a variable capacity turbocharger, and in particular, in one in which the blade angle of the movable nozzle vane is varied by a ring mechanism, exhaust gas is controlled by the movable nozzle vane. This invention relates to a variable capacity turbocharger that improves reliability by alleviating pressure waves that occur in the narrowest scroll of a turbine housing where the turbine housing is confined.

[Prior Art] As a variable displacement turbocharger, the blade angles of a plurality of nozzle vanes provided in a turbine housing along its nozzle opening can be variably controlled by a link mechanism, and exhaust gas is directed to a turbine rotor. A device in which the inflow speed is adjusted is known. As described in Japanese Utility Model Application No. 59-70032 (see Figs. 4 and 5), the link mechanism generally includes a turbine housing attached to the rotating shaft 2 of each movable nozzle vane 1. One end of the control lever 4 is fixed outside the control lever 3, the other end of the control lever 4 is arranged radially, and the drive ring 5 is engaged with the other end of the control lever 4, and the drive ring 5 is rotated around the circumference. The blade angle of each nozzle vane 1 is uniformly changed by rotating the nozzle vane 1 in the direction shown in FIG.

[Problems to be solved by the invention] However, the exhaust gas pressure applied to each nozzle vane 1a differs depending on the position of each nozzle vane 1a, and in particular, as shown in FIG. Narrowest scroll 7
An excessive force was acting on the nozzle vane 1a located at point a. This is because the pulsation of the exhaust gas introduced into the turbine housing 3 is generated in the scroll as a pressure wave from the exhaust gas introduction side of the turbine housing, and this pressure wave tends to trap the exhaust gas by the movable nozzle vane 1a. This is because they are concentrated on a certain narrowest scroll 7a.

For this reason, the movable nozzle vane 1a located on the narrowest scroll 7a generates a torsional force in the same direction on both ends of the movable nozzle vane 1a centering on its rotation axis 14, resulting in double torsion, driving the nozzle vane 1a and the nozzle vane 1a. This creates a large reaction force in the link mechanism that controls the opening, causing abnormal wear and causing early damage.

[Purpose of the invention] The present invention was devised in consideration of the above circumstances, and its purpose is to reduce the pressure waves of exhaust gas generated in the narrowest scroll and to achieve highly durable and reliable variable displacement turbocharging. The aim is to provide the opportunity.

[Summary of the invention] In order to achieve the above object, the present invention provides a variable capacity turbocharger in which movable nozzle vanes are provided on the outer periphery of the turbine at intervals in the flow direction of exhaust gas. The tongue is extended toward the movable nozzle vane, the tip edge of the tongue is brought close to the movable nozzle vane, and the extending portion is cut off diagonally in the direction connecting the tip edge of the tongue and one end of the base side. The pressure waves acting near the turbine housing are released to the exhaust gas introduction side of the turbine housing.

[Embodiment] A preferred embodiment of the variable capacity turbocharger according to the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1A is a front view of the variable displacement turbocharger of the present invention, and FIG. 1B is a sectional view taken along the line A--A in FIG. 1A.

As shown in the figure, a plurality of movable nozzle vanes 1a are provided within the turbine housing 3 along the circumference of the nozzle opening 12 at appropriate intervals. Each nozzle vane 1a has a turbine housing 3
It is rotatably supported by a rotating shaft 14 that passes through the blade, and its blade angle can be changed arbitrarily. Each rotary shaft 14 is provided at its end outside the turbine housing 3 with a control lever 15 fixed at one end for rotating the shaft to variably control the blade angle of the movable nozzle vane 1a. The other end of the control lever 15 is disposed radially outward of the turbine housing 3 in the radial direction.

A drive ring 16 is provided at the other end of each control lever 15 in order to engage with the control levers 15 and rotate each control lever 15 uniformly around the rotation axis 14. It is adapted to be rotated in the circumferential direction by a driving means 17 such as the like.

Now, the feature of the variable capacity turbocharger of the present invention is that the pressure waves generated in the narrowest scroll 7a are alleviated while maintaining the efficiency of the turbine 8, and the openings of the movable nozzle vane 13 and the movable nozzle vane 1a are controlled as described above. The objective is to prevent damage to the link mechanism described in the conventional example.

Therefore, in the present invention, as shown in FIG. is placed close to the movable nozzle vane 1a, and one side of the extending portion of the tongue portion 9 is cut off diagonally in the direction connecting the tip edge 9a of the tongue portion 9 and one side end 9b on the base side. That is, by extending the tongue portion 9, the narrowest scroll 7a is formed with respect to the turbine housing 3,
By communicating the narrowest screw row 7a and the exhaust gas upstream side 11 through the cut-off portion 10, the efficiency of the turbine 8 is maintained, and pressure is applied to the exhaust gas introduction side of the turbine housing 3 through the cut-off portion 10. I try to let the waves escape. Note that the area of the cut-off portion 10 is set to approximately half the area of the tongue portion 9 in consideration of maintaining the efficiency of the turbine 8.

In this way, the pressure waves concentrated near the tongue portion 9 escape to the exhaust gas introduction side of the turbine housing 3 through the cut-off portion 10, and therefore the pressure of the exhaust gas generated at the narrowest scroll 7a is reduced. Waves (load) can be released to the exhaust gas introduction side, and even if an abnormally high pressure wave occurs, for example, the durability of the movable nozzle vane 1a and the link mechanism can be improved.
Reliability can be improved and stable exhaust flow rate control can be performed.

[Effects of the Invention] As is clear from the above explanation, the variable capacity turbocharger of the present invention can exhibit the following excellent effects.

(1) In a variable capacity turbocharger in which movable nozzle vanes are provided on the outer periphery of the turbine at intervals in the flow direction of exhaust gas, the tongue at the end of the scroll of the turbine housing is extended toward the movable nozzle vane. The tip edge is brought close to the movable nozzle vane, and the extending portion is cut off diagonally in the direction connecting the tongue tip edge and one end of the base side, so that pressure waves are released to the exhaust gas introduction side of the turbine housing. There is no damage to the movable nozzle vane and the link mechanism that drives it, and durability and reliability can be greatly improved.

(2) It can be easily applied to already manufactured units.

[Brief explanation of drawings]

FIG. 1A is a front view of the variable displacement turbocharger according to the present invention, FIG. 1B is a view taken along the line A-A in FIG. FIG. 1 is a schematic configuration diagram of the device and a partial sectional view thereof. In the figure, 1a is a movable nozzle vane, 3 is a turbine housing, 7a is the narrowest scroll, 8 is a turbine, 9 is a tongue, 10 is a cut-off portion, 15 is a control lever, and 16 is a drive ring.

Claims (1)

[Scope of utility model registration request] In a variable capacity turbocharger in which movable nozzle vanes are provided on the outer periphery of the turbine at intervals in the flow direction of exhaust gas, the tongue at the end of the scroll of the turbine housing is extended toward the movable nozzle vane, and the tip of the tongue is A variable displacement turbo supercharger characterized in that its edge is brought close to a movable nozzle vane, and its extending portion is cut off diagonally in the direction connecting the tip edge of its tongue and one side end of its base.