JPS63117124A - Twin scroll turbocharged engine - Google Patents

Abstract

PURPOSE:To improve the output of an engine without the occurrence of exhaust interference by providing a directional control valve which separates one passage from another one in the range of a small exhaust flow rate, and causes both said passages to communicate with each other in the range of a large exhaust flow rate between both said passages. CONSTITUTION:In a low speed rotation range, exhaust gas discharged from cylinder chambers 1a, 1d flows into a passage 4b on a hub side through a connecting passage 16b from a passage 2b, and the exhaust gas discharged from cylinder chambers 1b, 1c flows into a passage 4a on a shroud side through a connecting passage 16a from a passage 2a to cause a turbine rotor 5 to rotate. In a high speed rotation range, the flow rate of the exhaust gas increases to cause an actuator 19 to function, and a directional control valve 17 is thereby opened to cause said connecting passages 16a, 16b to communicate with each other. Thus the exhaust gas separately flowing through said passages 2a, 2b joins, and flows through both said passage 4a on the shroud side and said passage 4b on the hub side to rotate said turbine rotor 5.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a twin-scroll turbocharged engine that can effectively supercharge the engine in both small and large displacement ranges without increasing exhaust resistance. .

[Conventional technology] Conventionally, as shown in FIG. 4, cylinder chambers 1a and 1b.

1c, 1d, the cylinder chambers 1a, lb, lc,
An exhaust manifold 2 is installed that joins the exhaust gas from the ld at the outlet, and a vortex is installed at the outlet of the exhaust manifold 2, which is divided by a partition wall 3 into two flow paths, a shroud side flow path 4a and a hub side flow path 4b. Connect the twin scroll 4 of
At the center of the twin scroll 4, a turbine wheel 5 that drives a compressor (not shown) and performs supercharging is concentrically disposed, and an exhaust flow that discharges exhaust gas after rotating the turbine and performing supercharging. A passage 6 is provided in the axial direction of the turbine wheel 5, and a bypass passage 7 is provided near the inlet of the twin scroll 4 to communicate with the exhaust passage 6 in order to control supercharging pressure. There was an engine 10 with a turbocharger provided with a wastegate valve 8 that opens and closes a flow path 7 depending on boost pressure, and an actuator 9 that controls the opening and closing operation of the wastegate valve 8.

Further, as shown in FIG. 5, the exhaust manifold 2 is connected to a flow path 2b where exhaust gas from the cylinder chambers 1a and ld join together,
Flow path 2 where exhaust gases from the cylinder chambers 1b and lc join together
The flow path 2a is connected to the shroud side flow path 4a of the twin scroll 4, and the flow path 2b is connected to the hub side flow path 4b. Side flow path 4a and hub side flow path 4b
Bypass passages 7 and 11 communicating with the exhaust passage 6 are provided, respectively, and waste gate valves 8 and 12 open and close the bypass passages 7 and 11, respectively, in accordance with boost pressure, and the waste gate valve 8 , 12, and actuators 9 and 13 for controlling the opening and closing operations of the turbocharged engine 1.
There were also 4.

The exhaust order of the cylinder chambers 1a to 1d is 1a-1c→
The order is ld→1b. .

[Problems to be Solved by the Invention] However, in the turbocharged engine 1O, since the outlet portion of the exhaust manifold 2 is not divided but is grouped together, the In this case, the exhaust gases coming out of the cylinder chambers 1a, 1b, lc, and 1d merge at the outlet of the exhaust manifold 2 and flow into the shroud side flow path 4a and hub side flow path 4b of the twin scroll 4.
Flows evenly in both directions, making full use of the effective cross-sectional area of the twin scroll 4, reducing exhaust resistance.
Engine output can be efficiently increased with less energy loss, but on the other hand, in low-speed rotation ranges, the total exhaust gas flow rate decreases, and the exhaust gases discharged from each cylinder chamber interfere with each other. As a result, the energy loss of the exhaust gas was large, and this was not effectively reflected in the increase in engine output.

Further, in the turbocharged engine 14, the internal flow path of the exhaust manifold 2 is divided into two parts: cylinder chambers 1a, ld and cylinder chambers 1b, lc, where exhaust is performed in the order of la-1cm1d-1b. In the low speed rotation range of the engine, that is, in the low exhaust gas flow rate range, it is possible to prevent exhaust interference between cylinder chambers within the exhaust manifold 2.
While it is possible to increase engine output smoothly even at low speeds, at high speeds the effective cross-sectional area of the exhaust gas flow path is halved, which increases exhaust resistance and reduces engine output. Furthermore, from a structural point of view, two sets of wastegate valves and actuators are required in the twin scroll 4 part, which does not have much space.
The air piping that operates the actuator also had to be taken into account, which posed many design difficulties.

[Means for Solving the Problems] The present invention has been made with the aim of solving the above-mentioned problems of the conventional art. are formed independently, one flow path is connected to the shroud side flow path of the twin scroll, the other flow path is connected to the hub side flow path, and a waste gate valve is provided in either side of the flow path. The twin-scroll turbocharged engine is characterized in that a switching valve is provided between the two flow paths, which partitions one flow path and the other flow path in a small exhaust flow rate range and allows them to communicate in a large exhaust flow rate range. That is.

[Operation] In the small displacement range, the exhaust gas flowing through one flow path of the exhaust manifold flows into the shroud side flow path of the twin scroll because the connecting pipe is separated by a switching valve, and the exhaust gas flows through the other flow path. Exhaust gas flowing through the passage flows into the hub side passage.

In addition, in the large exhaust flow rate range, one flow path and the other flow path are communicated with each other by the switching valve, so the exhaust gas flowing in both flow paths joins, and both the shroud side flow path and the hub side flow path are connected. flows into.

[Example] Hereinafter, the present invention will be described in detail with reference to the drawings.

As shown in FIG. 1, the turbocharged engine 1
A connecting pipe is provided between an exhaust manifold 2 partitioned into flow passages 2a and 2b used for the turbocharged engine IO, and a twin scroll 4 having a shroud side flow passage 4a and a hub side flow passage 4b used for the turbocharged engine IO. 15 interposed therein, and in the connecting pipe 15, a switching valve 17 defining the connecting channels lea and i6b is connected to the connecting channel 16a using a pin 18 disposed on the upstream side on the same plane as the partition wall 3 as a fulcrum. rotate to the side,
Provided so that it can be tilted. Connect one end of the pin 18 to the connecting pipe 1
5, and connect an actuator 19 to the protruding end of the pin 18 via a lever 20.

Note that other symbols in FIG. 1 are the same as in FIG. 4.

Next, the operation of the embodiment of the present invention will be explained.

Figure 2 is an engine performance curve diagram, Figure 3 is a turbocharger boost pressure characteristic diagram, and solid line A is the switching valve 17.
The broken line B shows the torque and supercharging pressure with respect to the engine speed when operating with the switching valve 17 closed and the switching valve 17 open. In this embodiment, the solid line A and the broken line The switching valve 17 is closed up to the intersection Y of B, that is, in the low speed rotation range, and after the intersection Y, in the high speed rotation range, the switching valve 17 is closed.
open.

Regarding the opening degree of the switching valve 17, when the exhaust gas on the flow path 2b side flows to the flow path 2a side, the speed of the exhaust gas and the flow path 2a
The opening direction of the switching valve 17 is tilted toward the flow path side where the wastegate valve 8 is provided by matching the speed of the exhaust gas flowing on the side.

As a result, in the low speed rotation range, the cylinder chamber 1a,
Exhaust gas discharged from Ld flows from the flow path 2b through the connecting flow path 16b into the hub side flow path 4b, and similarly, exhaust gas discharged from the cylinder chambers 1b and 1c flows from the flow path 2a into the connecting flow path 4b. The liquid flows into the shroud side flow passage 4a through the passage lea, and rotates the turbine impeller 5, respectively.

At this time, the exhaust gas whose flow path is divided into two does not cause exhaust interference, and furthermore, since the effective cross-sectional area of each flow path is halved, the exhaust flow rate increases and energy loss is minimized. It can be seen that the torque and supercharging pressure are the values shown by the solid line A, and a higher output can be obtained compared to the broken line B.

In addition, in the high speed rotation range, the exhaust gas flow rate increases and the actuator 19 operates to open the switching valve 17 and connect the connecting channels 16a and 16b.
The exhaust gases flowing through the respective channels merge into the shroud side flow path 4.
a and the hub side flow path 4b, causing the turbine impeller 5 to rotate.

When the boost pressure exceeds the maximum allowable value, the actuator 9 operates according to the boost pressure and adjusts the opening degree of the wastegate valve 8, but since the connecting channels tea and 16b are in communication, The flow path 2b together with the exhaust gas flowing through the flow path 2a side.
A part of the exhaust gas flowing on the side also flows into the shroud side flow path 4a, passes through the bypass 7, and detours to the exhaust passage 6.

That is, the effective flow passage cross-sectional area of the twin scroll 4 can be fully utilized, the exhaust resistance can be reduced, and the torque and boost pressure become the values shown by the broken line B, so that the engine output can be improved.

Also, in terms of structure, it is only necessary to provide one set of waste gate valve 8 and actuator 9 in the twin scroll 4 section, and the connecting pipe equipped with the switching valve 17 and actuator 19 is integrated into a unit, which is different from conventional It can be installed relatively easily on other devices.

It should be noted that the present invention is not limited to the above-mentioned embodiment, and that the connecting pipe 15 may be integrally provided at the outlet of the exhaust manifold 2.
The fact that it may be established as an integral part so as to extend from the Population Department, etc.
Of course, various changes can be made without departing from the gist of the invention.

[Effects of the Invention] As described above, according to the present invention, in the small exhaust flow rate region,
Engine output can be improved by allowing exhaust gas to flow through the two divided flow paths without causing exhaust interference or reducing exhaust flow velocity, and in large exhaust flow areas, both flow paths of the exhaust manifold can be communicated. As a result, the effective cross-sectional area of the twin scroll can be fully utilized, making it possible to reduce exhaust resistance and exhibit excellent effects such as being able to efficiently increase engine output.

[Brief explanation of the drawing]

Fig. 1 is a vertical cross-sectional view showing an embodiment of the present invention, Fig. 2 is an engine performance curve diagram depending on the opening and closing of the switching valve, Fig. 3 is a turbocharger boost pressure characteristic curve depending on the opening and closing of the switching valve, and Fig. 4 ．．
FIG. 5 is a vertical sectional view showing each conventional example. 2 is an exhaust manifold, 2a and 2b are flow paths, 4 is a twin scroll, 4a is a shroud side flow path, 4b is a hub side flow path, 5 is a turbine impeller, 6 is an exhaust flow path, 7 is a bypass flow path, 8 is the wastegate valve, 9 is the actuator, 15
7 indicates a communication pipe, 7 indicates a switching valve, and 19 indicates an actuator.

Claims (1)

[Claims] 1) Form independent passages in the exhaust manifold that bring together cylinders that do not cause exhaust interference with each other; one passage is placed on the shroud side of the twin scroll, and the other passage is placed on the hub side. Connect each one and either one
In a twin-scroll turbocharged engine with a wastegate valve installed in the flow path on one side, one flow path and the other flow path are partitioned between the two flow paths in a small exhaust flow rate range, and a large exhaust flow rate is achieved. This engine is equipped with a twin-scroll turbocharger and features a switching valve for communication in the area.