JPS6229723A - Turbosupercharger - Google Patents

Abstract

PURPOSE:To make supercharging pressure at the time of low engine speed ever so better, by letting one side of scroll chambers form a nozzle part as opposed to impeller inlet width of a turbine and the other side form another nozzle part to be opened to the side of an impeller inlet part of the turbine, respectively. CONSTITUTION:At the time of low engine speed, all exhaust gases are concentrated into a scroll chamber 14b. A nozzle part 16b is designed so as to be opposed to the whole width of an inlet of a turbine wheel 11, and the exhaust concentrated in this nozzle part 16 flows toward the turbine wheel 11 as in an X. At the time of high engine speed, exhaust gas flows into scrolls 14a and 14b, flowing into the turbine wheel 11 from both sides of nozzle parts 16a and 16b, thus supercharging pressure is prevented from coming too much. A flow of the exhaust gas at the inlet of the turbine wheel 11 in this state comes to a Y in illustration.

Description

Detailed Description of the Invention [Field of Application of the Invention] The present invention relates to a turbocharger in which a turbine and a compressor are disposed on the same axis, and particularly to a turbocharger equipped with a variable displacement turbine suitable for passenger car engines. It is related to the feeder.

[Background of the invention]

A conventional exhaust turbine supercharger will be described with reference to FIG. 1. An exhaust pipe 3 is connected between a cylinder 2 of an engine 1 and a turbine 5, and the turbine 5 is driven by exhaust gas from the engine 1. A compressor 6 is fixed to the other end of the shaft 7 to which the turbine 5 is fixed, and is driven at the same rotation speed as the turbine 5. The air compressed by the compressor 6 is sent into the intake pipe 4, but the boost pressure at this time is as shown in Figure 3, p c /, and there is sufficient boost pressure in the low and medium speed range of the engine. There was a problem that I couldn't get it.

Therefore, in order to improve this difficulty even a little, it is common to use a turbine scroll having a relatively small flow path area that is suitable for the low speed range of the engine. However, in this case, the supercharging pressure becomes too high when the engine rotates at high speed, so as shown in FIG. The supercharging pressure in the intake pipe 4 is improved as shown in PC in FIG. However, when such exhaust gas control is performed, the turbine inlet pressure is as high as pt when the engine is at high speed, compared to the boost pressure Pc due to the energy lost due to bypass exhaust. In order to improve this problem, a turbocharger equipped with a variable capacity turbine was constructed by dividing the inside of the turbine scroll with a partition wall, and a nozzle section of this divided scroll was developed. There are known configurations in which guide blades are arranged on each side, configurations in which the area of the divided scroll is divided into unequal areas, and configurations in which the scroll is divided into two or more.

For example, U.S. Patent No. 1270,495;
No. 7,549, Utility Model Publication No. 55-88848, No. 53-1
There is No. 15205.

However, with conventionally formed scrolls, if the engine exhaust is guided to only one scroll (depending on the engine operating condition), the exhaust gas will flow into the turbine impeller inlet only from the nozzle part of the scroll chamber divided by the partition wall. As a result, the full width of the impeller inlet cannot be utilized, and the flow of exhaust gas is partially inflowed at the impeller inlet, resulting in increased loss and reduced turbine efficiency. This decrease in turbine efficiency results in a decrease in boost pressure at low engine speeds, which narrows the range in which the turbine's actual capacity can be varied.

[Purpose of the invention]

An object of the present invention is to improve the variable capacity turbine as described above to provide a turbo supercharger that can obtain good boost pressure characteristics over a wide operating range from a low engine speed range to a high engine speed range. It is something.

[Overview of Umoaki]

The present invention divides the interior of the turbine scroll into two scroll chambers using a partition wall, and when the exhaust gas flow rate in the low speed rotation range of the engine is small, the exhaust gas is guided only to one scroll chamber in a concentrated manner, and the engine This is a variable capacity turbine that guides exhaust gas to both scroll chambers in the high-speed rotation range of the turbine. Turbine efficiency is increased by uniformly inflowing over the entire width of the impeller inlet without partial inflow, and high air supply pressure and accompanying high torque are obtained in the engine low speed rotation range. Furthermore, in order to obtain high boost pressure in the low engine speed range, it is necessary to significantly change the capacity ratio of the two scroll chambers, which are divided according to the engine operating conditions as described above.
This is achieved by dividing the inside of the turbine scroll into equal parts using partition walls, and it is necessary to make one of the scrolls, which is used in the low engine speed range, as small as possible. However, when trying to reduce the capacity of the turbine by making the scroll smaller, the flow velocity in the scroll chamber, which has a smaller flow path area, increases, resulting in an increase in friction loss within the scroll chamber, as shown by the broken line in Figure 4. The turbine efficiency decreases as η'. On the other hand, the size of the scroll chamber is fixed to an appropriate size, and the nozzle section from the scroll chamber outlet to the turbine impeller inlet is configured with a bladed nozzle, and this bladed nozzle can be changed to When the capacitance of is changed, η is shown by the solid line in Figure 4.
Even if the turbine capacity is made considerably smaller, there is little decrease in turbine efficiency.

From the above results, it is more preferable to configure the nozzle section from the scroll chamber to the impeller used in the low engine speed range as a vaned nozzle with guide vanes arranged, and the other as a vaneless nozzle.

With this configuration, when the exhaust gas flow rate is low in the engine's low speed rotation range, the exhaust gas is guided intensively to the scroll chamber that has a vaned nozzle, where the bladed nozzle is adapted to the engine's low speed rotation range. By arranging the turbines in such a manner, a large turbine output can be efficiently obtained even with a small exhaust gas flow rate. In addition, in the high-speed rotation range of the engine, if there is a large amount of exhaust gas, the engine exhaust gas is also guided to the other scroll chamber with a bladeless nozzle, increasing the capacity of the turbine and maintaining the efficiency of the turbine. The boost pressure is controlled so that the turbine output does not become excessive, that is, the boost pressure does not become excessive. As mentioned above, by effectively utilizing the advantages of the bladeless nozzle, which has good efficiency over a wide flow rate range, and the bladed nozzle, which has good efficiency within a constant flow rate range, by changing the capacity of the turret, the engine speed can be reduced. This technology has been developed to ensure good supercharging performance over a wide operating range, including high speeds.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to FIGS. 5 to 14. In addition, in the figure, a detailed explanation of the compressor portion of the turbocharger is omitted because it is not a target portion of the present invention. In FIG. 5, a turbine impeller 11 and a compressor impeller (not shown) are fixedly arranged by a shaft 12. In FIG. A bearing casing 13 is disposed around the outer periphery of this shaft 12 and is attached to a turbine scroll 14 .

The inner peripheral surface of the turbine scroll 14 is divided by a partition wall 15 into two scroll chambers 14a and 14b. As a result, the nozzle portions 16a and 16b at the exit of the scroll chamber are also divided into two. The scroll chamber 14b is located directly above the inlet of the turbine impeller 110, and the nozzle portion 16a is disposed opposite to the inlet of the turbine impeller 11 over the entire width thereof. Further, the scroll chamber 14a is located substantially on the side surface of the inlet of the turbine impeller 11, and the nozzle portion 16a is also arranged to face substantially the side surface of the turbine impeller 11.

The partition wall 15 is connected to a partition plate 18 of the turbine population 17 , and a flow path of the turbine population 17 is formed by the partition plate 18 into an open scroll 19 and a closed scroll 20 . Open scroll 19 communicates directly with turbine inlet 17 . Further, the closing scroll 20 has a hole 2 bored in the partition plate 18.
1 communicates with an open scroll 19. A control valve 22 is disposed in this hole 21 to establish and shut off communication between the open scroll 19 and the closed scroll 20.

A valve body 22a of the control valve 22 is configured to be rotatable around a shaft 23, and the shaft 23 is connected to a shaft 25a of an actuator 25 via an arm 24. Actuator 2
5 consists of a spring member 26 that presses the shaft 25af to one side, and a bellows 27 that is arranged to resist the spring member 26.The bellows 27 has a hole 25b that introduces supercharging pressure, etc.
is provided. A hole 28 is bored in the turbine scroll 14 downstream of the control valve 22 and communicates with a bypass passage 29 leading to the turbine outlet. A valve body 30a of an exhaust bypass valve 30 is pressed against the hole 2B by a spring member 31 and is normally closed.

The control valve 22 is provided with a knob 32, and when the control valve 22 is sufficiently opened, the knob 32 presses the valve body 30a of the exhaust bypass valve 30 to open it, and the closed scroll 20 and the bypass flow are opened. Route 29 is communicated.

When the control valve 22 closes the hole 21, the exhaust gas from the turbine population 17 passes through the open scroll 19 and concentrates on the nozzle part 16b. The turbine capacity is small because it is concentrated in the chamber 14b.
Since the flow velocity of b can be increased, the turbine output can be increased, and the supercharging pressure in the engine low speed rotation range can be significantly increased from Pc' in FIG. 3 to p c //.

FIGS. 6 and 7 show enlarged views of the scroll section. The nozzle portion 16b is configured to face the entire width of the inlet of the turbine impeller 11.
The flow of the exhaust gas concentrated at b is as shown by arrow X in FIG. 5, and flows smoothly toward the turbine impeller 11.

If the supercharging pressure is introduced into the pressure introduction hole 25b of the bellows 27, when the supercharging pressure increases and becomes higher than a predetermined value,
The force based on the pressure inside the bellows 27 becomes larger than the force of the spring member 26, and presses the shaft 25a of the actuator 25,
The control valve 22 opens the hole 21, and the exhaust gas flows through the nozzle part 16.
Flowing into the turbine impeller 11 from both a and 16b, it is possible to prevent the capacity of the turbine scroll from increasing and the supercharging pressure from becoming excessive. In this state, the flow of exhaust gas at the inlet of the turbine impeller 11 is as shown by arrow Y in FIG. Although the flow is slightly biased, it is a full-width inflow, so the loss is small, and the supercharging pressure in this state is already sufficiently high, so a slight decrease in efficiency is not a problem.

The turbine inlet pressure at this time is as shown in Pt/'' in Figure 3 (
(This is about the same as the boost pressure pc", and is much lower than the turbine inlet pressure pt" when the boost pressure is controlled to Pc" using only the conventional exhaust bypass valve. In addition, as in this embodiment, the partition wall 15 is tilted so that the center of gravity R, b of the passage area of the scroll chamber 14b, which is used in the low speed rotation range of the engine, is aligned with the passage area of the other scroll chamber 14a. If the scroll chamber 14b is arranged so that the center of gravity Ra of the area is as large as possible, the area radius ratio A/R, which is an index of the turbine capacity, is
There is also the advantage that the variable capacity turbine can be made smaller and the variable range of the variable capacity turbine can be expanded.

Note that the area/radius ratio A/R is the typical flow path area A of the scroll.
is the ratio of the distance from the center of the rotating shaft to the center of gravity of the representative flow path area of the scroll, and the capacity of the turbine can be expressed by the value of A/R.

Furthermore, when the engine becomes higher speed and higher load from the state where the control valve 22 is open, the knob 32 attached to the control valve 22 contacts the valve body 30a of the exhaust bypass valve 30 to open it, and the exhaust gas is removed. A portion is discharged into the bypass channel 29. By releasing this exhaust gas into the bypass flow path 29, an increase in supercharging pressure can be suppressed.

FIG. 8, (In FIG. 1, the turbine scroll 14
The partition wall 15 has two scroll chambers 14a.

The scroll chamber 14b is divided into 14b, and a bladed nozzle is disposed in the nozzle portion of the scroll 14b that substantially faces the inlet of the turbine impeller 11, and a bladeless nozzle 16a is provided in the nozzle portion of the other scroll chamber 14a. . Further, the valve body 30a of the bypass valve 30 is configured to be rotatable about a shaft 33, and the shaft 33 is connected to a shaft 35a of an actuator 35 via an arm 34. The actuator 35 consists of a spring member 36 that presses the shaft 35a'i to one side and a bellows 37 that is arranged to resist the spring member 36.The bellows 37 has a hole 35 that introduces supercharging pressure, etc.
b is provided. FIG. 9 is a sectional view taken along the line AA in FIG. 8, and the shape of the bladed nozzle 16C is determined so that it can fit into the inlet of the turbine impeller 11 even with a small flow rate and provide a sufficiently high-speed flow. For this purpose, it is desirable that the exit blade angle of the bladed nozzle be 15 degrees or less with respect to the circumferential direction. With the above-described configuration, this embodiment can further obtain high supercharging pressure from a low engine speed range, thereby further improving the running performance of the vehicle.

Further, in this embodiment, since the actuator 25 of the control valve 22 and the actuator 35 of the exhaust bypass valve 30 are provided separately, it is possible to control the two valves in a complex manner.For example, the pressure of the actuator 35 of the exhaust bypass valve 30 is Introduction hole 3
5b, the supercharging pressure is introduced into the pressure inlet hole 2 of the actuator 25 of the control valve 22 depending on the operating condition of the engine.
Even if atmospheric pressure or high pressure is switched and applied to 5b to turn the control valve 22 on and off, the supercharging pressure can be controlled by the exhaust bypass valve as shown in the PCI shown in FIG. 3. Further, by introducing supercharging pressure into both pressure introduction holes 25b and 35b and adjusting each spring member 26, 36, the exhaust bypass valve 30 can be opened after the control valve 22 is completely opened. Note that it is of course possible to replace these actuators with electromagnetic actuators.

FIGS. 10 and 11 show other embodiments of the present invention, and are enlarged sectional views of essential parts of the scroll portion.

In FIG. 10, the scroll portion is tilted in the opposite direction to that of the embodiments shown in FIGS. 5 to 7, and a bladed nozzle 16c is further attached. It has the same effect and effect as.

FIG. 11 shows a case in which the scroll portion is not tilted, that is, the partition wall 15 is arranged perpendicularly to the shaft 12. In this case, the same effect as in the previous embodiment is obtained.

be effective.

In addition, the bladed nozzle 16C is attached to the scroll 1 as shown in FIG.
It may be constructed by assembling it separately from the scroll 14, but it may also be constructed integrally with the scroll 14 by a precision casting method or the like.

Instead of the bladed nozzle 16C shown in FIGS. 8 to 11, guide vanes 16C' and 16C" may be provided on both side walls of the nozzle part 16 as shown in FIGS. 12 and 13 to obtain the same effect. Further, as shown in FIG. 14, the guide vanes 16C may extend from one side of the wall surface.

〔Effect of the invention〕

As explained above, according to the present invention, the inside of the turbine scroll is divided into two scroll chambers by the partition wall,
The exhaust gas flowing through the scroll chamber is controlled according to the operating condition of the engine, and in particular, only one scroll chamber is used in the low engine speed range, and exhaust gas flows partially from the nozzle of the scroll toward the inlet of the turbine impeller. The design allows for high boost pressure, that is, high torque, from low engine speeds, improving the engine's low-speed torque characteristics and responsiveness during sudden acceleration. By using a vaned nozzle, it is possible to reduce the decrease in turbine efficiency and further reduce the capacity t, so that good running performance and improved fuel efficiency can be achieved over a wide operating range of the engine.

[Brief explanation of drawings]

Figures 1 and 2 are system diagrams of conventional turbochargers, Figure 3 is a line diagram showing engine speed, turbine inlet pressure, and boost pressure, and Figure 4 shows turbine capacity and turbine efficiency. 5 is a cross-sectional view of essential parts showing one embodiment of the present invention, and FIG.
7 is an enlarged sectional view of the turbine scroll shown in FIG. 5, FIG. 8 is a sectional view of a main part of a turbocharger showing another embodiment of the present invention, and FIG. 9 is an enlarged sectional view of the turbine scroll shown in FIG. A sectional view, 1st θ diagram,
11, 12, and 14 are sectional views of a turbocharger showing still other embodiments of the present invention, and FIG.
It is a BB sectional view of the figure. 11... Turbine impeller, 14... Turbine flow arm, 14a, 14b... Scroll chamber,
15... Partition wall, 15a, 16b... Nozzle part, 16
C... Vane nozzle, 22... Control valve, 30...
Exhaust bypass valve, 25°35...actuator.

Claims (1)

[Claims] 1. In a turbocharger in which a turbine and a compressor are fixedly arranged on the same axis, the inside of the scroll of the turbine is divided into two scroll chambers by a partition, and one of the scroll chambers divided by the partition is connected to the blades of the turbine. A bladed nozzle portion is formed substantially opposite to the car inlet width, and the other side of the scroll chamber is formed with a nozzle portion opening substantially on a side surface of the impeller inlet portion of the turbine. A turbo supercharger characterized by comprising means for controlling the flow rate of a scroll chamber communicating with a nozzle portion on a side surface.