JPH02125928A - Exhaust device for engine with exhaust turbo supercharger - Google Patents

Abstract

PURPOSE:To contrive to increase output power by providing the connecting section of a communication passage connecting exhausting passages with each other in the downstream side of plural numbers of superchargers toward a supercharger which operates only in a specified operating range in such a way that the opening of it is directed outward in the radial direction of its scroll in the inner circumferential side of said scroll. CONSTITUTION:An exhaust passage is divided into two branch exhaust passages 2a and 2b, and an air intake passage 3 is concurrently divided into two air intake passages 3a and 3b. Then, the turbines Tp and Ts and the blowers Cp and Cs of a primary and a secondary exhaust turbo supercharger 9 and 10 are arranged to each branch passage. And the upstream side section of the exhaust cut valve 11 of the branch exhaust passage 2b is connected with the upstream side of the turbine Tp of the branch exhaust passage 2a via a communication passage 12. In this case, the connecting section of the communication passage 12 to the branch exhaust passage 2a is arranged in the inner circumferential sid e of a turbine scroll Tp1 in the branch exhaust passage 2a. In addition, the opening 12a of the communication passage 12 at the connecting section is arranged in such a way as to be directed outward to the radial direction of the turbine scroll Tp1.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an improvement in an exhaust system for an engine equipped with an exhaust turbo supercharger.

(Prior Art) Conventionally, an engine with an exhaust turbo supercharger is equipped with two exhaust turbo superchargers, one for low speed and one for high speed, as disclosed in, for example, Japanese Patent Application Laid-open No. 59-160022. Exhaust passages are connected to the exhaust gas inlets of the exhaust turbo supercharger, and the middle parts of the exhaust passages are connected to each other by a communication passage, and the exhaust passages are connected to each other by a communication passage connecting the exhaust passages of the high-speed exhaust turbo supercharger. An exhaust cut valve is provided on the downstream side of the exhaust, and at high speeds and high loads, the exhaust cut valve is opened and exhaust gas from the engine is supplied to the low speed and high speed exhaust turbo superchargers through each exhaust passage, reducing the intake flow rate. At the same time, at low speeds and low loads, the exhaust cut valve is closed and the exhaust gas from the engine is supplied only to the low speed exhaust turbo supercharger via the exhaust passage. A so-called sequential turbo type is known in which the exhaust gas is supplied intensively to the turbine of the turbo supercharger to obtain high supercharging pressure with good start-up.

(Problem to be Solved by the Invention) However, in the conventional system described above, when the exhaust cut valve is closed at low speed and low load, the exhaust gas discharged from the engine to the exhaust passage of the high-speed exhaust turbo supercharger flows into the communication passage. The inflow gas flow from this communication passage reduces the flow velocity of the exhaust gas flowing through the exhaust passage of the low-speed exhaust turbocharger, and the low-speed exhaust turbocharger There is a problem in that the efficiency of the supercharger decreases and the engine output decreases.

The present invention has been made with attention to these points,
The purpose of this is that in a sequential turbo type exhaust turbocharged engine, when the exhaust cut valve is closed at low speed and low load, the inflow gas flow from the communication passage is used to generate a low speed exhaust turbo. The objective is to increase the flow velocity of exhaust gas flowing through the exhaust passage of the supercharger.

(Means for Solving the Problems) In order to achieve the above object, in the present invention, the exhaust gas flow flowing from the communication passage into the exhaust passage of a specific exhaust turbo supercharger is directed toward the inner peripheral side of the turbine scroll of this exhaust passage. radially outward from the turbine scroll.

Specifically, the solution taken by the present invention is to provide a plurality of tJl turbo superchargers that pressurize intake air using the energy of exhaust gas, and to connect an exhaust passage to the exhaust gas inlet of each exhaust turbo supercharger. The intermediate parts of the exhaust passages are connected to each other by a communication passage, and the exhaust downstream side of the communication passage connection part of the exhaust passage of the exhaust turbocharger other than the specific exhaust turbosupercharger is closed in a predetermined operating region. The present invention is based on an exhaust system for an engine equipped with an exhaust turbo supercharger, which supplies exhaust gas only to a specific exhaust turbo supercharger. In contrast, the connecting portion of the communication passage to the exhaust passage of the specified exhaust turbo supercharger is arranged so that the connection part of the communication passage to the exhaust passage of the specific exhaust turbo supercharger is directed toward the inner circumferential side of the tubbin scroll in the exhaust passage, and the opening thereof faces outward in the radial direction of the tabin scroll. The configuration is such that it is provided in

(Function) With the above configuration, in the present invention, in a predetermined operating region, the downstream side of the exhaust passage of the exhaust turbocharger other than the specific exhaust turbocharger is blocked from the communication passage connection part, and the exhaust gas is blocked. Supplied only to specific exhaust turbo superchargers.

In that case, the connection part of the communication passage to the exhaust passage of the specific exhaust turbocharger is provided on the inner peripheral side of the turbine scroll in the exhaust passage, and the opening thereof faces outward in the radial direction of the turbine scroll. Therefore, exhaust gas discharged from the engine into the exhaust passage of an exhaust turbo supercharger other than the specified exhaust turbo supercharger flows into the exhaust passage of the specified exhaust turbo supercharger from the communication passage, and is discharged from the communication passage. The inflowing gas flow is directed from the inner circumferential side of the turbine scroll in the exhaust passage toward the radially outward side of the turbine scroll, and the inflowing gas flow from this communication passage increases the flow velocity of the gas flow flowing on the outer circumferential side of the turbine scroll, resulting in the movement of the gas flow. Energy will increase and engine power will increase.

(Example) Embodiments of the present invention will be described below based on the drawings.

FIG. 1 shows an engine with an exhaust turbo supercharger equipped with an exhaust system according to an embodiment of the present invention. In the figure, an exhaust passage 2 for discharging exhaust gas from an engine 1 has two branch exhaust passages 2a and 2b that extend independently from the engine 1. Further, the intake passage 3 through which the intake air of the engine 1 flows has two branch intake passages 3a and 3b that are branched downstream of the air flow meter 4 that detects the amount of intake air. 3b on the upstream side of the intercooler 5. In the intake passage 3 on the downstream side of the intercooler 5, a throttle valve 6. A surge tank 7 and a fuel injection valve 8 are provided.

A turbine Tp rotationally driven by exhaust gas is disposed in one branch exhaust passage 2a of the two branch exhaust passages 2a and 2b, and the turbine Tp is connected to one branch intake passage 3a. It is connected to the disposed blower Cp via a rotating shaft Lp. And these turbines 191
Rotation axis Lp.

A primary side turbo supercharger 9 is configured with the blower Cp as a main element. Similarly, the other branch exhaust passage 2b is provided with a turbine Ts that is rotationally driven by exhaust gas, and the other branch intake passage 3b is provided with a blower C.
6 is disposed, and these turbines Tp and blowers Cs are connected by a rotating shaft Ls to form a secondary turbo supercharger 10.
It consists of

The passage portions of the branch intake passages 3a and 3b on the upstream side of the blowers Cp and Cs are formed so as to face each other in a straight line at the branch part branching from the intake passage 3. The configuration is such that the generated pressure waves easily propagate to the other branch intake passage 3a side, but are difficult to propagate to the air flow meter 4 side.

An exhaust cut valve 11 is disposed in the secondary side branch exhaust passage 2b on the upstream side of the turbine Ts. This exhaust cut valve 11 operates in this branch exhaust passage 2b in a low rotation range.
This is provided in order to shut off the provision of exhaust gas to the turbine Ts of the secondary side turbocharger 10 and operate only the primary side turbocharger 9.

The exhaust cut valve 11 of the branch exhaust passage 2b on the secondary side
The upstream portion of the exhaust gas is connected to the upstream side of the turbine Tp of the primary side branch exhaust passage 2a via the communication passage 12. The communication passage 12 is connected to the exhaust passage 2 on the downstream side of both turbines Tp and Ts via a bypass passage 18 in which a waste gate valve 17 is disposed. A portion of the bypass passage 18 on the upstream side of the waste gate valve 17 is connected between the turbine Ts and the exhaust cut valve 11 in the branched exhaust passage 2b via the leakage passage 14 in which the exhaust leakage valve 13 is disposed. has been done.

The exhaust leak valve 13 is operated by a diaphragm actuator 16, and the pressure chamber of the actuator 16 is connected to the
It opens into the branch intake passage 3a on the downstream side of the blower Cp of the primary side turbocharger 9. This leak valve 13 is
In the process of increasing the engine speed, the boost pressure P1 on the downstream side of the blower Cp is set to a predetermined value (for example, 500 m+sHg)
When this happens, the exhaust cut valve 11 is opened.
When the bypass passage 14 is closed, a small amount of exhaust gas flows through the bypass passage 14.
It is supplied to the turbine Ts through. Therefore, the turbine Ts starts rotating before the exhaust cut valve 11 opens, thereby improving supercharging response and alleviating torque shock when the exhaust cut valve 11 opens.

Note that 19.20 is a diaphragm actuator that operates the exhaust gas cut valve 11 and the waste gate valve 17, respectively, and the operations of these actuators will be described later.

On the other hand, an intake cut valve 21 is provided in the secondary side branch intake passage 3b on the downstream side of the blower Cp. Further, a passage 22 is provided that bypasses the blower Cs,
A relief valve 23 is provided in this bypass passage 22 . The intake cut valve 21 is operated by a diaphragm actuator 24 as described later. Also,
The relief valve 23 opens the bypass passage 22 until a little before the intake cut valve 21 and the exhaust cut valve 1 open during the process of increasing the engine speed. By the rotation of the blower Cs based on the opening operation of the leakage valve 13, the blower Cs
The blower Cs is provided to prevent pressure from increasing in the branch intake passage 3b between the intake cut valve 21 and the intake cut valve 21, and to facilitate rotation of the blower Cs. Such a relief valve 23
is operated by a diaphragm actuator 25.

The control pressure conduit 26 of the actuator 24 that operates the intake cut valve 21 is a three-way valve 27 made of an electromagnetic solenoid valve.
connected to the output port of the

Also, an actuator 19 that operates the exhaust cut valve 11
The control pressure conduit 28 is connected to the output port of a three-way valve 29, which is also an electromagnetic solenoid valve. Furthermore, the control pressure conduit 30 of the actuator 25 for actuating the relief valve 23 is connected to the output port of a three-way valve 31 similar to that described above.

A control pressure conduit 32 of the actuator 20 that operates the wastegate valve 17 is connected to an output port of a three-way valve 33 consisting of an electromagnetic solenoid valve.

Three-way valve consisting of these electromagnetic solenoid valves 27.29.3
1 and 33 are controlled by a control circuit 35 configured using a microcomputer. This control circuit 35 controls the engine rotation speed Ne.

Each electromagnetic solenoid valve is controlled based on detected values such as the intake air amount Q, the throttle opening TVO, and the boost pressure Pl on the downstream side of the blower Cp of the primary side turbocharger 9.

Among the four electromagnetic solenoid valves, one input port of the three-way valve 29 is open to the atmosphere, and the other input port is connected to the negative pressure tank 43 via a conduit 36. Intake negative pressure Pn downstream of the throttle valve 6 is introduced into the negative pressure tank 43 via the check valve 37.

Further, the three-way valve 27 has one input port connected to the conduit 36.
The other input port is connected to the output port of the differential pressure detection valve 39 via a conduit 38.

As shown in FIG. 2, the differential pressure detection valve 39 has a casing 51 defined into three chambers 54, 55, and 56 by two diaphragms 52, 53, and an input port 54a in the chamber 54 and an input port 54a in the chamber 54. An input port 55a is opened in the chamber 55, and an output port 57 connected to the conduit 38 and an air release boat 58 are opened in the chamber 56. The port 54a is connected to the downstream side of the intake cut valve 21 via the conduit 41,
A supercharging pressure P1 downstream of the primary blower Cp is introduced. Further, the port 55a is connected to the upstream side of the intake cut valve 21 via the conduit 42, and introduces the pressure P2 on the upstream side of the intake cut valve 21 when the intake cut valve 21 is closed. There is. In this differential pressure detection valve 39, when the pressure difference between pressures P1 and P2 is large, a valve body 59 coupled to both diaphragms 52 and 53 opens the port 47 and introduces atmospheric air into the conduit 38. , when the differential pressure P2-Pi falls within a predetermined value ±ΔP, the port 57 is closed by the spring 59. Therefore, three-way valve 27 connects conduit 26 to conduit 3.
8, the differential pressure P2-Pi is within the predetermined value ±Δ
When it becomes larger than P, the atmosphere is introduced into the actuator 24, and the intake cut valve 21 is opened. Further, when the three-way valve 27 connects the conduit 26 to the conduit 36, negative pressure is supplied to the actuator 24 and the intake cut valve 21 is closed.

On the other hand, when the three-way valve 29 connects the conduit 28 to the conduit 36, negative pressure is supplied to the actuator 19 and the exhaust cut valve 11 is closed, and at this time only the primary side turbocharger 9 is operated. state.

Furthermore, when the three-way valve 29 releases the conduit 28 to the atmosphere, the exhaust cut valve 11 is opened and the secondary side turbocharger 10 is operated.

FIG. 3 shows the open and closed states of the intake cut valve 21 and the exhaust cut valve 11, the exhaust leak valve 13, and the waste gate valve 17.
This control map is shown together with the opening and closing states of the relief valve 23 and is stored in the control circuit 35.

Here, one input port of the three-way valve 31 is also opened to the atmosphere, and the other input port is connected to the negative pressure tank 43, and when the engine is running at low speed, the intake negative pressure Pn is connected to the conduit 30.
is introduced, and the relief valve 25 opens the bypass passage 22, but in the process of increasing the engine speed Ne, before the intake cut valve 21 and the exhaust cut valve 11 open, as shown in FIG. The three-way valve 31 is switched to the atmosphere side by a signal from the control circuit 35, so that the relief valve 25 closes the bypass passage 22.

Furthermore, supercharging pressure P1 is introduced into one input port of the three-way valve 33 through the control pressure conduit 15 of the actuator 16, and the engine rotation speed Ne and throttle opening TVO are set to exceed predetermined values and When the supply pressure P1 exceeds a predetermined value, the control circuit 35 opens the two-way valve 33 and introduces the supercharging pressure P1 into the actuator 20, which causes the est gate valve 17 to open the bypass passage 18. ing. The other input port of the three-way valve 33 is open to the atmosphere, and when the actuator 20 is supplied with the atmosphere, the wastegate valve 17 is closed.

Next, the layout around the turbocharger will be explained based on FIGS. 4 and 5. Exhaust ports (not shown) for each cylinder are opened on one side of the engine 1, and each exhaust port has an exhaust manifold 8 as shown in FIGS. 6 to 8.
1 is installed. And the exhaust manifold 8
Primary side and secondary side turbo superchargers 9, 10 are placed on the side of 1.
are arranged so that their rotational axes are coaxial, and the inlet portions of each of the turbines Tp and Ts are flange-connected to the exhaust manifold 81. In addition, the secondary side turbocharger 1
The branch intake passage 3b extending from the suction port of blower Cs 0 is reversed at the rear side of blower Cs (left side in FIG. 4) and faces forward (right side in FIG. 4). It merges with a branch intake passage 3a extending from the intake port of the blower Cp to form an intake passage 3, and further extends toward the front and upper side of the engine 1.

Further, the branch intake passage 3a extending from the discharge port of the blower Cp of the primary side turbocharger 9 faces rearward, while the branch intake passage 3b extending from the discharge port of the blower Cs of the secondary side turbocharger 10 faces forward. These two branch intake passages 3a
, 3b merge to form the intake passage 3, which extends rearward and upward. Then, an intake cut valve 21 is provided in the branch intake passage 3b immediately upstream of this merging portion.

Furthermore, one end of a bypass passage 22 is connected to the branch intake passage 3b near the discharge port of the blower Cs of the secondary side turbocharger 10, and the other end of the bypass passage 22 is connected to each blower Cp.
, Cs are connected to the intake passage 3 on the upstream side of the intake air. A relief valve 23 is provided at the end of the bypass passage 22 on the side of the blower Cs.

Next, the passage structure in the exhaust manifold 81 is shown in FIGS.
This will be explained based on FIG. 9. The exhaust manifold 81 includes a scroll (
A branch exhaust passage 2a communicating with the spiral chamber Tp+ and a branch exhaust passage 2b communicating with the scroll (volute chamber) Tsl of the turbine Ts of the secondary turbocharger 10 are formed substantially in parallel. Further, a communication passage 12 is formed between the branch exhaust passages 2a and 2b, which has an "upwardly convex arched shape" and connects these two branch exhaust passages 2a and 2b. Furthermore, a bypass passage 18 is formed from the middle of this communication passage 12.

Further, an exhaust cut valve 11 is disposed on the exhaust downstream side of the communication passage connecting portion of the branch exhaust passage 2b.

As shown in FIG. 10, the connecting portion 82 of the communication passage 12 to the branch exhaust passage 2a on the primary turbocharger side is
Turbine scroll Ts1 in the branch exhaust passage 2a
It is provided on the inner circumferential side. , Moreover, the opening 12a of the communication passage 12 in the connecting portion 82 is connected to the turbine scroll Ts.
It is provided so as to face outward in the radial direction of 1.

Therefore, in the above embodiment, by operating only the primary side turbocharger 9 in the low rotation range, the exhaust gas from the exhaust passage 2 is transferred to the turbine T of the primary side turbocharger 9.
The exhaust passage 2 is concentratedly supplied to the exhaust passage 2, and a high supercharging pressure can be obtained with good rise.
Exhaust gas from the engine is supplied to the turbines Tp and Ts of the two turbochargers 9 and 10, and an appropriate boost pressure can be obtained while ensuring the intake flow rate.

In that case, the connection part 82 of the communication passage 12 to the branch exhaust passage 2a of the primary side turbocharger 9 is on the inner peripheral side of the turbine scroll Tp in the branch exhaust passage 2a, and the opening 12a is on the turbine scroll Since the exhaust cut valve 11 is provided so as to face outward in the radial direction of the engine, in the low rotation range where the exhaust cut valve 11 is closed, the
Exhaust gas discharged to the branch exhaust passage 2b is connected to the communication passage 1.
2 flows into the branch exhaust passage 2a of the primary side turbocharger 9, and the inflow gas flow from this communication passage 12 flows into the branch exhaust passage 2a of the primary side turbocharger 9.
This communication passage 1 faces outward in the radial direction of the turbine scroll TI)l from the inner peripheral side of the turbine scroll TI)I of a.
The flow rate of the gas flow flowing on the outer peripheral side of the turbine scroll Tpl is increased by the inflow gas flow from the turbine scroll Tpl, the kinetic energy of the gas flow increases, and the engine output increases.

(Effects of the Invention) As explained above, according to the exhaust system for an engine with an exhaust turbo supercharger of the present invention, a plurality of exhaust turbo superchargers that pressurize intake air using the energy of exhaust gas are provided, and each exhaust turbo Exhaust passages are connected to the exhaust gas inlets of the turbochargers, and the midpoints of the exhaust passages are connected to each other by a communication passage, and the communication passages of the exhaust passages of exhaust turbo superchargers other than a specific exhaust turbo supercharger are connected to each other. The downstream side of the exhaust gas from the connection part is closed in a predetermined operating region to supply exhaust gas only to a specific exhaust turbo supercharger, and the connection part of the communication path to the exhaust passage of the specific exhaust turbo supercharger is Since the exhaust passage is provided on the inner circumferential side of the turbine scroll with its opening facing outward in the radial direction of the turbine scroll, in a predetermined operating range, exhaust turbo superchargers other than the specified exhaust turbo supercharger can be removed from the engine. Exhaust gas is discharged into the exhaust passage of the exhaust passage and flows into the exhaust passage of the specific exhaust turbo supercharger from the communication passage, and the exhaust gas is directed from the inner circumferential side of the turbine scroll in the exhaust passage to the outside in the radial direction of the turbine scroll. The gas flow increases the flow velocity of the gas flow flowing on the outer circumferential side of the turbine scroll, increasing the kinetic energy of the gas flow, and making it possible to increase the engine output.

[Brief explanation of the drawing]

The drawings illustrate an embodiment of the present invention, in which Fig. 1 is an overall system diagram of the engine, Fig. 2 is a sectional view of the differential pressure detection valve, Fig. 3 is a characteristic diagram showing switching characteristics of the response valve, and Fig. 4 is a diagram showing the switching characteristics of the response valve. side view of the engine,
Fig. 5 is a front view of the engine, Fig. 6 is a plan view of the exhaust manifold, Fig. 7 is a side view of the same, Fig. 8 is a rear view of the same, and Fig. 9 is a plan view of the exhaust manifold.
The figure is an explanatory diagram showing the passage structure in the exhaust manifold.
FIG. 0 is a longitudinal sectional side view of the vicinity of the turbine of the primary side turbocharger. 2a, 2b... Branch exhaust passage, 9.10... Turbo supercharger, 12... Communication passage, 12a... Opening, 82...
... Connection part, TD+ ... Turbine scroll.

Claims (1)

[Claims] (1) A plurality of exhaust turbo superchargers that pressurize intake air using the energy of exhaust gas are provided, an exhaust passage is connected to the exhaust gas inlet of each exhaust turbo supercharger, and a midway part of the exhaust passage is connected to a communication passage. At the same time, the downstream side of the exhaust passage of the exhaust passages of the exhaust turbochargers other than the specific exhaust turbocharger is closed in a predetermined operation region to connect the exhaust gas to the specific exhaust turbocharger. In an exhaust system for an engine with an exhaust turbo supercharger, which is configured to supply exhaust gas only to an engine, the connecting portion of the communication passage to the exhaust passage of the specific exhaust turbo supercharger is connected to the inner peripheral side of the turbine scroll in the exhaust passage,
1. An exhaust system for an engine with an exhaust turbo supercharger, characterized in that the opening faces outward in the radial direction of the turbine scroll.