JPS61237831A - Variable capacity supercharger - Google Patents

Abstract

PURPOSE:To suppress excessive back pressure rise at low loads by equipping a supercharger having movable-nozzle-vane-operated, variable cross-sectional area of turbine exhaust intake port, with a waist gate valve and by regulating the opening of said valve according to specified conditions. CONSTITUTION:To a nozzle vane drive unit 10 abutting on a turbine housing 2, an actuator 17 is connected which drives a nozzle vane equipped in a turbine 4 in multiple steps by means of control signals from a control unit 20. In the above construction, an exhaust passage 7 is equipped with an exhaust relief passage 8 bypassing the turbine 4. In the middle of the passage 8, a waist gate 21 is equipped. The said valve 21, as an example, is so constructed that a valve piece 22 is usually forced with a spring 23 to close said passage 8 and that the opening of the valve piece 22 can be changed in multiple steps through a rod 24 operated with an actuator 25 according to operating conditions of an engine.

Description

Detailed Description of the Invention [Technical Field of the Invention] The present invention relates to a variable displacement supercharger that improves the characteristics of the supercharger by rotating a movable nozzle vane provided in a turbine housing. This invention relates to a variable capacity supercharger that has been improved to further improve its characteristics in a low load range.

[Prior art]

Generally, exhaust gas is used to rotate an exhaust turbine,
A supercharging device uses this power to drive a compressor to increase intake pressure (boost pressure) and increase engine output, but when the engine is running at low speeds, the turbine speed is low and effective boost pressure cannot be obtained. Additionally, superchargers that are provided with an exhaust bypass passage (wastegate) to prevent overspeeding of the turbine when the engine rotates at high speeds have poor fuel efficiency at high speeds.

Therefore, as shown in FIG. 3, a movable nozzle vane 1 is provided in the turbine housing 2 of the supercharger, and when the engine 5 is running at low speeds, the nozzle vane 1 is rotated in the closing direction to reduce the capacity of the turbine 4. rotates well to improve low-speed torque, and when the engine 5 rotates at high speeds, the nozzle vane is rotated in the fully open direction to increase the capacity of the turbine, and the rotation of the turbine wheel 3 is reduced to improve fuel efficiency at high speeds. There is a variable capacity supercharger with

As shown in FIGS. 4(A) and 4(B), this variable capacity supercharger drives a nozzle vane 1 provided in a nozzle portion 2a of a turbine housing 2 by a drive device 10 installed outside the turbine housing 2. By rotating it, the flow velocity of exhaust gas flowing out from the nozzle portion 2a to the turbine wheel 3 can be changed. Inside the casing 10a of the drive device 10, there is a rotating shaft 11 that passes through the turbine housing 2 and connects to the nozzle vane, a control lever 12 fixed to the other end of the rotating shaft 11, and a control lever 12 fixed to the free end 12a. A control ring 13 that engages with a recess 13a provided on the inner circumference and an actuation lever 14 that rotates the control ring 13 are provided. The actuating lever 14 is connected to the actuating link 6 outside the casing 10a by an actuating shaft 15 passing through the casing 10a, and when the actuating link 16 is rotated by an actuator (not shown), the inside of the turbine housing 2 The nozzle vane 1 is designed to rotate.

Ideally, in the movable nozzle vane drive device configured as described above, the operating lever should be rotated continuously according to the operating conditions of the engine, but if the drive device is configured in this way, the cost will be high. , since it is not practical,
The operating lever may be 2 to 4 depending on the engine load and rotation speed.
It is common to switch in stages.

In such a variable capacity supercharger, the rotation speed of the turbine can be changed by adjusting the movable nozzle vane, so unlike a normal supercharger, when the boost pressure exceeds the set value, the exhaust gas is Currently, there is no exhaust pressure control using a wastegate valve, which allows some of the waste to escape without passing through the turbine.

However, controlling the exhaust pressure using movable nozzle vanes in the conventional variable displacement supercharger is good because sufficient boost pressure can be obtained when the engine load is high (high load), but when the engine load is low (low On the other hand, under load), the boost pressure tends to increase too much, which has the disadvantage of increasing losses (bumping loss and friction loss).

[Purpose of the invention]

The purpose of the present invention is to eliminate the drawbacks of the conventional variable displacement supercharger, suppress unnecessary increases in exhaust pressure at low loads,
It can reduce pumping loss and friction and improve the characteristics of the supercharger in the low load range of the engine.
Fuel efficiency can be improved. An object of the present invention is to provide a new variable displacement supercharger equipped with a wastegate valve.

[Structure of the invention]

The variable capacity supercharger of the present invention that achieves the above object is provided with a wastegate valve in the supercharger that changes the exhaust gas inlet area of the turbine using a movable nozzle vane, and the wastegate valve is adjusted according to the engine speed, load, and nozzle vane opening. The feature is that the opening degree of the wastegate valve is determined.

〔Example〕

The present invention will be described in detail below using the accompanying drawings.

FIG. 1 shows the configuration of an embodiment of a variable capacity supercharger of the present invention.

In the figure, 5 is an engine, 4 is a turbine, and 6 is a compressor. A nozzle vane drive device 10 as shown in FIGS. 3 and 4 is provided adjacent to the turbine housing 2.

An actuator 17 is connected to this nozzle vane drive device 10, and for example, this actuator 1
Reference numeral 7 assumes that a nozzle vane installed in the turbine 4 can be rotated in four stages according to a control signal from the control unit 20.

Engine operating information such as engine speed and load is input to the control unit 20, and the actuator 17 is controlled according to the four zones ■ to ■ shown in the engine speed to torque characteristics in FIG. It is supposed to send a signal. That is, when the operating state of the engine is within zone ■, the control unit 20 uses the actuator 17 to keep the nozzle vane close to the fully open state, and when it is within zone ■, the control unit 20 moves the nozzle vane so as to close it slightly. When the nozzle vane is in the zone, the nozzle vane opening degree is further reduced, and when the nozzle vane is in the zone ■〉Zone■〉Zone■〉Zone■〉.

Exhaust path 7 of the variable displacement supercharger configured as above
In addition, in this invention, an exhaust gas relief passage 8 is provided that bypasses the turbine 4, and a wastegate valve 21 is installed in the middle of this exhaust gas relief passage 8.

For example, the wastegate valve 21 has a valve body 22 that is normally biased by a spring 23 to close the exhaust relief passage 8, and is operated by an actuator 25 connected to the valve body 22 via a rod 24. The opening degree of the valve body 22 changes in three stages: large, medium, and small.

Here, zone (2) is a region where boost pressure is high but exhaust pressure is also high. However, when the load is large, a high boost pressure is required, but when the load becomes medium or low, the boost pressure is not needed as much. However, the problem is that the exhaust pressure is high even in this state, and as mentioned above, this exhaust pressure is higher in zone ①. Follow. When the zone ■, ■, ■ is reached, the waste gate valve 21 should be made larger in zone ■.
If the zone ■ is opened slightly and a part of the exhaust gas is released through the exhaust relief passage 8, the exhaust pressure will drop and the boost pressure will remain at its desired value, but the exhaust pressure will drop without dropping too much and the friction will be reduced. Become.

Therefore, in this invention, areas A, B, and C (areas where the torque is smaller than the broken line in zones ■, ■, and ■) when the load is small are set in zones ■, ■, and ■. It is stored in the control unit 20. The control unit 20 then increases the opening degree of the wastegate valve 22 when the operating state of the engine enters region A, and
The actuator 25 is operated so that the opening degree of the waste gate valve 22 is set to medium when the area C is entered, and the opening degree of the waste gate valve 22 is made small when the area C is entered.

Therefore, in the variable displacement supercharger of the present invention configured as described above, when the engine is operating in zones ■, ■, and ■, the nozzle vane opening is throttled and the exhaust pressure is high. Even if there is, the load is reduced and the engine operating state is in region A.

When entering B or C, the control unit 20 controls the wastegate valve 22 to open to a large degree in area A.
In region B, the opening degree is medium, and in region C, the opening degree is small, so the exhaust pressure decreases depending on the engine operating condition, so the boost pressure characteristics are adjusted to the appropriate level according to the engine operating condition. This reduces pumping loss and friction loss, improving fuel efficiency in the low and medium load range of the engine.

〔Effect of the invention〕

As explained above, in the variable capacity supercharger of the present invention, a wastegate valve is installed in the supercharger that changes the area of the exhaust gas inlet of the turbine using a movable nozzle vane, and the wastegate valve is adjusted according to the engine speed, load, and nozzle vane opening. By setting the opening degree of the wastegate valve, the unnecessary rise in exhaust pressure (E) at low loads is suppressed, reducing pumping loss and friction and improving the characteristics of the supercharger in the low load range of the engine. This has the effect of improving fuel efficiency in this region.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing the configuration of an embodiment of the variable displacement supercharger of the present invention, FIG. 2 is a diagram showing control characteristics of the nozzle vane and wastegate valve stored in the control unit of FIG. 1, Fig. 3 is a schematic diagram of a conventional variable displacement supercharger having a movable nozzle vane in the turbine housing, and Fig. 4 (A) is a configuration of the movable nozzle vane drive device of the variable displacement supercharger shown in Fig. 1. 4(B) is a cross-sectional view of the main part of the turbine housing for explaining the same as (A).
It is a sectional view taken along the line XX of the figure.

Claims (1)

[Claims] A variable capacity supercharger that uses a movable nozzle vane to vary the area of the turbine's exhaust gas inlet and is equipped with a wastegate valve, and the opening degree of the wastegate valve is determined by the engine speed, load, and nozzle vane opening degree.