JPH02125922A - Suction system for engine with supercharger - Google Patents

Abstract

PURPOSE:To restrain the influence from the fluctuation of air intake to an air intake cut valve by providing a relief passage in such a way as to go around a supercharger which operates only in a specified operating range out of plural numbers of superchargers provided, and thereby opening a relief valve provided halfway the distance to said passage in an operating range other than the specified operating range. CONSTITUTION:An exhaust passage is divided into two branch exhaust passages, and an air intake passage 3 is concurrently divided into two air intake passages 3a and 3b so that each branch passage is provided with the turbines Tp and Ts and the blowers Cp and Cs of exhaust turbo superchargers 9 and 10 on the primary and secondary sides respectively. And inlet cut valve 21 is provided for the branch air intake passage 3a of the exhaust supercharger on the secondary side which is suspended at a low revolution range so that the reverse flow of intake air is prevented on the downstream side of the blower Cp. Furthermore, in this case' a relief passage 22 going around the blower Os is provided so that a relief valve 23 arranged for the passage 22 is controlled to be opened in an operating range other than a specified operating range (low revolution operating range). In addition, a passage from the relief valve 23 to the air intake cut valve 21 is set to be comparatively great in volumetric capacity.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to an improvement in an intake system for a supercharged engine.

(Prior art) Conventionally, as a supercharged engine, for example, Japanese Patent Application Laid-Open No. 59-1
As disclosed in Japanese Patent No. 60022, it is equipped with exhaust turbo superchargers for low speed and high speed, and the intake passages on the downstream side of the intake of each exhaust turbo supercharger are combined and connected to the engine, and the exhaust turbo supercharger for high speed A so-called sequential turbo type engine is known, which operates the exhaust turbo supercharger only at high speeds and high loads. According to this system, at low speeds and low loads, only the low-speed exhaust turbocharger is operated, and the exhaust gas from the exhaust passage is intensively supplied to the turbine of the low-speed exhaust turbocharger to increase the boost pressure. At the same time, at high speeds and high loads, both the low speed and high speed exhaust turbo superchargers are operated, and the exhaust gas from the exhaust passage is supplied to the turbines of the two exhaust turbo superchargers to increase the intake flow rate. Appropriate boost pressure can be obtained while ensuring the same.

(Problem to be Solved by the Invention) By the way, in such a supercharged engine, there is a high-speed exhaust turbo supercharger that operates only at high speeds and high loads, on the intake downstream side and on the intake upstream side of the above-mentioned gathering part. An intake cut valve that opens at high speed and high load is installed in the intake passage of the engine, and this intake cut valve is closed at times other than high speed and high load to prevent intake air from flowing back from the above-mentioned collecting section to the high speed exhaust turbo supercharger. ing.

Further, in that case, it is conceivable to provide a passage that bypasses the blower of the high-speed exhaust turbo supercharger, and to arrange a relief valve in this relief passage. If the blower of the high-speed exhaust turbo-supercharger is pre-rotated at low speed and low load when the high-speed exhaust turbo-supercharger is stopped, the intake cut valve opens during the process of increasing the engine speed. By opening this relief valve until a little earlier than this, it is possible to prevent the pressure in the branched intake passage between the blower and the intake cut valve from increasing and to make it easier for the blower to rotate.

However, in that case, pressure waves are generated as the relief valve opens and closes, and the intake pulsation caused by this pressure wave acts on the intake cut valve, repeatedly applying a load to the valve stem of the intake cut valve.
A problem arises in that the valve stem becomes loose and the sealing performance of the intake cut valve is impaired.

The present invention has been made with attention to these points,
The purpose of this is to prevent intake pulsation from acting on the intake cut valve by devising the shape of the intake passage around the intake cut valve and relief valve in a sequential turbo type supercharged engine. There is a particular thing.

(Means for Solving the Problems) In order to achieve the above object, the present invention is to attenuate the intake pulsation accompanying the opening and closing of the relief valve in the intake passage, thereby making it difficult to propagate to the intake cut valve.

Specifically, the solution taken by the present invention is that the intake passage is branched into a plurality of midpoints, and each branched intake passage is provided with an exhaust turbo supercharger that pressurizes the intake air using the energy of exhaust gas. The subject matter is an intake system for a supercharged engine that operates at least one exhaust turbo supercharger only in a specific operating range. To deal with this, an intake cup/valve that closes outside the specific operating range is installed in the branch intake passage on the downstream side of the intake of the specific exhaust turbocharger that operates only in the specific operating range, and The branch intake passage on the downstream side of the intake and the branch intake passage on the upstream side of the intake are communicated by a relief passage, and the relief passage is provided with a relief valve that opens in an operating range other than the specific operating range, and a specific exhaust turbo is connected from the relief valve to the branch intake passage on the intake upstream side. The structure is such that the passage volume from the relief valve to the intake cut valve is set larger than the passage volume to the supercharger.

(Function) With the above configuration, in the present invention, exhaust gas from the engine is supplied to each exhaust turbo supercharger through each exhaust passage in a specific operating region, and proper supercharging is achieved while ensuring an intake flow rate. While the exhaust gas from the engine is supplied only to the specific exhaust turbo supercharger through the exhaust passage outside the specific operating range, the exhaust gas is concentratedly supplied to the specific exhaust turbo supercharger type. As a result, high boost pressure can be obtained quickly.

Since the intake cut valve closes outside the specific operating range, intake air from other branch intake passages is prevented from flowing back into the branch intake passage in which the specific exhaust turbo supercharger is provided.

In addition, since the relief valve opens outside the specific operating range, if the blower is pre-rotated in an operating range other than the specific operating range where the specific exhaust turbo supercharger is stopped, during the process of increasing the engine speed, By keeping this relief valve open until a little before the intake cut valve opens, pressure in the branched intake passage between the blower and the intake cut valve is prevented from increasing, and the blower rotates more easily. .

In that case, since the passage volume from the relief valve to the intake cut valve is set larger than the passage volume from the relief valve to the specified exhaust turbo supercharger, intake pulsation due to pressure waves generated as the relief valve opens and closes. It becomes easier to propagate to the specific exhaust turbo supercharger, and the intake pulsation that tries to propagate to the intake cut valve is sufficiently attenuated while propagating through the large volume passage up to the intake cut valve. Therefore, this intake pulsation does not act on the intake cut valve, no load is applied to the valve stem of the intake cut valve, and the valve stem functions normally to ensure good sealing performance of the intake cut valve. become.

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

FIG. 1 shows a supercharged engine equipped with an intake 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 this turbine Tp is disposed in one branch intake passage 3a. It is connected to a blower Cp via a rotating shaft Lp. And these turbines Tp1
The primary side turbocharger 9 is configured with the rotating shaft Lp1 and the blower Cp as main elements. Similarly, the other branch exhaust passage 2b has a turbine T driven to rotate by exhaust gas.
s is arranged, and the other branch intake passage 3b
A blower Cs is disposed therein, and the turbine Tp and the blower Cs are connected by a rotating shaft Ls to form a secondary turbo supercharger 10.

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 cup 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 2 in a low rotation range.
b is closed to cut off the supply of exhaust gas to the turbine Ts of the secondary turbocharger 10 and operate only the primary 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 an est 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, when the boost pressure P1 on the downstream side of the blower Cp reaches a predetermined value (for example, 5001 mHg) or more, the blower Cp is opened, and a small amount of exhaust gas is released when the exhaust cut valve 11 is closed. It is supplied to the turbine Ts through the bypass passage 14. Therefore, the turbine Ts starts rotating before the exhaust cut valve 11 opens, thereby improving the supercharging response when the exhaust cut valve 11 opens and alleviating the drastic shock.

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, on the downstream side of the blower Cp, an intake cut valve 21 for preventing backflow of intake air is disposed in the branch intake passage 3b on the secondary side. Further, a relief passage 22 that bypasses the blower Cs is provided, and a relief valve 23 is disposed in this relief passage 22. The intake cut valve 21 is operated by a diaphragm actuator 24 as described later. Further, the relief valve 23 opens the relief 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, and the exhaust cut valve 11 opens.
The pressure in the branch intake passage 3b between the blower Cs and the intake cut valve 21 is prevented from increasing due to the rotation of the blower Cs based on the opening operation of the exhaust leakage valve 13 when the blower Cs is closed, and the blower Cs is It is designed for easy rotation. 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 valves 27, 29.3 consisting of these electromagnetic solenoid valves
1 and 33 are controlled by a control circuit 35 configured using a microcomputer. This control circuit 35 controls each electromagnetic solenoid based on detected values such as engine speed Ne, intake air ff1Q, throttle opening TVO, and boost pressure Pl on the downstream side of the blower Cp of the primary side turbocharger 9. Control the valve.

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-PL 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 relief 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 port passage 35, so that the relief valve 25 closes the relief 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 wastegate valve 17 to open the bypass passage 18. There is. Further, the other manual boat 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 to 6. An exhaust port (not shown) for each cylinder is opened on one side of the engine 1, and an exhaust manifold is attached to the exhaust port. The primary and secondary turbo superchargers 9 and 10 are arranged on the side of the exhaust manifold so that their rotational axes are coaxial, and the inlets of each turbine Tp and Ts are connected to the exhaust manifold. is flange connected to the Further, the branch intake passage 3b extending from the suction port of the blower Cs of the secondary side turbocharger 10 is reversed at the rear side of the blower Cs (left side in Figure 4) and faces forward (right side in Figure 4). , merges with a branched intake passage 3a extending from the intake port of the blower Cp of the primary side turbocharger 10 to form the 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 collectively constitute the intake passage 3, which is connected rearward and upward to the cylinders of the engine. An intake cut valve 21 is provided in the branch intake passage 3b immediately upstream of this gathering portion.

Further, one end of the relief 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 relief passage 22 is connected to each blower Cs.
, cs are connected to the intake passage 3 on the upstream side of the intake air. The relief passage 22 is provided perpendicularly to the branch intake passage 3b. And the relief passage 2
A relief valve 23 is provided at the end of the blower Cs side of the blower Cs. The relief valve 23 is fixed to the blower Cs of the secondary turbocharger 10 outside the branch intake passage 3b.

Then, from the relief valve 23 to the secondary turbo supercharger 1
The passage volume from the relief valve 23 to the intake cut valve 21 is set larger than the passage volume from the relief valve 23 to the intake cut valve 21. That is, the passage length of the branch intake passage 3b from the relief valve 23 to the intake cut valve 21 is set longer than the passage length of the branch intake passage 3b from the relief valve 23 to the secondary side turbocharger 10.

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.
While a high supercharging pressure can be obtained with a high start-up by being concentratedly supplied to the exhaust passage 2
Exhaust gas from the engine is supplied to the turbines Tp and Ts of the two turbochargers 9 and 10, so that an appropriate boost pressure can be obtained while ensuring an intake flow rate.

Since the intake cut valve 21 closes in the low rotation range,
Branch intake passage 3b in which the secondary side turbocharger 10 is provided
This prevents intake air from flowing backward from other branch intake passages 3a.

In addition, since the relief valve 23 opens in the low speed range, if the blower Cs is pre-rotated in the low speed range where the secondary side turbocharger 10 is stopped, the intake air By keeping this relief valve 23 open until a little before the cut valve 21 opens, the pressure in the branch intake passage 3b between the blower Cs and the intake cut valve 21 is prevented from increasing, and the pressure in the branch intake passage 3b between the blower Cs and the intake cut valve 21 is prevented from increasing. ] 9 It becomes easier to rotate.

In that case, since the passage volume from the relief valve 23 to the intake cut valve 21 is set larger than the passage volume from the relief valve 23 to the secondary side turbocharger 10,
Intake pulsations caused by pressure waves that occur as the relief valve 23 opens and closes propagate to the secondary side turbocharger 10 and become unstable, and the intake pulsations that try to propagate to the intake cut valve 21 reach the intake cut valve 21. The air is sufficiently attenuated while propagating through the large-volume branch intake passage 3b. Therefore, this intake pulsation does not act on the intake cut valve 21, no load is applied to the valve stem of the intake cut valve 21, and the valve stem functions normally, ensuring good sealing performance of the intake cut valve 21. will be done.

Further, since the relief passage 22 is provided perpendicularly to the branch intake passage 3b, the intake pulsation due to the pressure wave generated from the relief valve 23 collides with the inner wall of the branch intake passage 3b and is attenuated. This also means that intake pulsation can be prevented from acting on the intake cut valve 21.

(Effects of the Invention) As explained above, according to the intake system for a supercharged engine of the present invention, the midway portion of the intake passage is branched into a plurality of parts, and an exhaust turbo supercharger is installed in each of the branched intake passages. At least one of the exhaust turbo superchargers is set to operate only in a specific operating range, and a branch intake passage on the downstream side of the intake of the specific exhaust turbo supercharger that operates only in the specific operating range is provided with a specific operating range. An intake cut valve is provided that closes outside the specified operating range, and a relief passage connects the branch intake passage on the downstream side of the intake and the branch intake passage on the upstream side of the intake of the specified exhaust turbo supercharger, and the relief passage is connected to the A relief valve that opens in the operating range is provided, and the passage volume from the relief valve to the intake cut valve is set larger than the passage volume from the relief valve to the specific exhaust turbo supercharger, ensuring intake flow rate in the specific operating range. While obtaining the basic effect of obtaining a high boost pressure with good start-up outside the specific operating range, the branch intake passage where the specific exhaust turbo supercharger is installed is connected to other branch intake passages. It is possible to prevent intake air from flowing backward from the passage, and also to prevent pressure rise in the branched intake passage between the blower of the specified exhaust turbo supercharger and the intake cut valve, and to prevent pressure waves generated when the relief valve opens and closes. It is possible to prevent the intake pulsation from acting on the intake cut valve, reduce the load on the valve stem of the intake cut valve, maintain the function of the valve stem, and ensure good sealing performance of the intake cut valve.

[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, and FIG. 6 is a sectional view of the branched intake passage. 3a, 3b... Branch intake passage, 9, 10... Turbo supercharger, 21... Intake cut valve, 22... Relief passage, 23... Relief valve. Patent applicant Mazda Corporation

Claims (1)

[Claims] (1) The midway part of the intake passage is branched into a plurality of branches, each branched intake passage is provided with an exhaust turbo supercharger that pressurizes the intake air using the energy of the exhaust gas, and at least one of the exhaust turbo superchargers is installed in each branch intake passage. This is an intake system for a supercharged engine that is designed to operate only in a specific operating range, and is installed in a branch intake passage on the downstream side of the intake of a specific exhaust turbo supercharger that operates only in the specific operating range. An intake cut valve that closes is provided, and the branch intake passage on the downstream side of the intake and the branch intake passage on the upstream side of the intake of the specified exhaust turbo supercharger are communicated with each other by a relief passage, and the relief passage is connected to the An intake system for a supercharged engine, characterized in that a relief valve that opens is provided, and the passage volume from the relief valve to the intake cut valve is set larger than the passage volume from the relief valve to the specified exhaust turbo supercharger. .