JPH02125920A - Suction system for engine with supercharger - Google Patents

Abstract

PURPOSE:To prevent erroneous detection by an air flow meter owing to fluctuation in pressure by setting a branch air intake passage to be comparatively great in volumetric capacity at the upstream side of an air intake for an exhaust turbo supercharger operating only in a specified operation range in a device which has the exhaust turbo supercharger installed at each air intake passage. CONSTITUTION:An exhaust passage is divided into two branch exhaust passages, and an air intake passage 3 is concurrently divided into two branch air intake passages 3a and 3b at the downstream side of an air flow meter 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 the supercharger 10 on the secondary side can be suspended by closing an exhaust cut valve in a low revolution range, which is arranged at the branch exhaust passage on the secondary side. In this case, the branch air intake passage 3b extending from the inlet opening of the blower Cp on the secondary side is made to be longer than the branch air intake passage 3a, and a volumetric capacity section 3c is provided halfway so that the branch air intake passage 3b is thereby 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, the midway portion of the intake passage is branched into two, and each branched intake passage is provided with an exhaust turbo supercharger for low speed and high speed, respectively.
A so-called sequential turbo type engine is known, in which a high-speed exhaust turbo supercharger is operated only at high speeds and high loads. According to this, only the low-speed exhaust turbo supercharger is activated at low speeds and low loads;
Exhaust gas from the exhaust passage is intensively supplied to the turbine of the low-speed exhaust turbo supercharger to obtain high boost pressure, while at high speeds and high loads, both the low-speed and high-speed exhaust turbo superchargers are supplied. It is possible to supply the exhaust gas from the exhaust passage to the turbines of the two exhaust turbo superchargers to obtain an appropriate supercharging pressure while ensuring the intake air flow rate.

(Problem to be Solved by the Invention) Incidentally, in such a supercharged engine, an air flow meter for detecting the intake air flow rate is provided in the intake passage upstream of each branch intake passage. The fuel injection amount and the like are controlled based on the detected intake air flow rate.

However, in that case, for example, when moving to a high-speed, high-load area,
Exhaust gas is suddenly supplied to the high-speed exhaust turbo supercharger and the blower suddenly starts operating, so the intake pressure changes suddenly with this blower, and this pressure fluctuation propagates to the air flow meter on the upstream side of the intake, and the intake air A problem arises in that the flow rate is erroneously detected.

The present invention has been made with attention to these points,
The purpose of this is to prevent erroneous detection by an air flow meter in a sequential turbo type supercharged engine by attenuating the pressure fluctuations using a branch intake passage.

(Means for Solving the Problems) In order to achieve the above object, the present invention solves pressure fluctuations generated in an exhaust turbo supercharger that operates only in a specific operating range.
The purpose is to attenuate the intake air in a branched intake passage on the upstream side of the intake air.

Specifically, the solution taken by the present invention is to branch the intake passage into a plurality of midpoints, and provide each branched intake passage with an exhaust turbo supercharger that pressurizes the intake air using the energy of the exhaust gas. The present invention is based on an intake system for a supercharged engine in which at least one exhaust turbo supercharger is operated only in a specific operating range. In contrast, the volume of the branch intake passage on the intake upstream side of the exhaust turbocharger that operates only in a specific operating range is set to be larger than the volume of the branch intake passage on the intake upstream side of other exhaust turbochargers. This configuration is configured to set a large value.

(Function) With the above configuration, in the present invention, for example, when transitioning to a specific operating region, exhaust gas is suddenly supplied to the exhaust turbo supercharger that operates only in the specific operating region, and the blower suddenly starts operating. This blower causes the intake pressure to fluctuate suddenly, and this pressure fluctuation propagates to the intake upstream side.

In that case, the volume of the branch intake passage on the intake upstream side of the exhaust turbocharger that operates only in this specific operating region is set to be larger than the volume of the branch intake passage on the intake upstream side of the other exhaust turbochargers. As a result, the pressure fluctuation is attenuated inside this branch intake passage having a large volume and does not propagate to the air flow meter, thereby preventing erroneous detection by the air flow meter.

(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 flush 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. The blower Cp is connected to the rotary shaft tp via a rotating shaft tp. And these turbines Tp1
The primary side turbocharger 9 is configured with the rotating wheel 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 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. The upstream portion of the waste gate valve 17 in the bypass passage 18 is connected between the turbine Ts and the exhaust cut valve 11 in the branch 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+wmHg)
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, 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 passage 22 that bypasses the blower Cs is provided, and a relief valve 23 is disposed in this bypass passage 22. Above intake cut valve 2
1 is a diaphragm actuator 2 as described later.
Operated by 4. Further, the relief valve 23 is
In the process of increasing engine speed, the intake cut valve 21
The bypass passage 22 is opened until a little before the exhaust cut valve 1 is opened, and the blower Cs is rotated based on the opening operation of the exhaust leakage valve 13 when the exhaust cup valve 11 is closed. 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

Further, a control pressure conduit 28 of an actuator 19 that operates the exhaust cut valve 11 is connected to an 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 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 atmosphere release port 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 55g 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 next 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 wastegate valve 17 to open the bypass passage 18. There is. Further, the other manual 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 to 6. Exhaust ports (not shown) for each cylinder are opened on one side of the engine 1, and an exhaust manifold is attached to the exhaust boat. The primary and secondary turbo superchargers 9 and 10 are disposed 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, a branch intake passage 3 extending from the suction port of the blower Cs of the secondary side turbocharger 10
b is a branch intake passage 3a that is reversed at the rear side of the blower Cs (left side in FIG. 4) and faces forward (right side in FIG. 4) and extends from the intake port of the blower Cp of the primary turbo supercharger 9. Together, they form the intake passage 3, which further extends toward the front and upper side of the engine 1.

Further, the inverted portion of the secondary side branch intake passage 3b has a large volume and is formed in the volume portion 3c. That is, the branch intake passage 3b extending from the suction port of the blower Cs of the secondary side turbocharger 10 is the branch intake passage 3a extending from the suction port of the blower Cp of the primary side turbocharger 9.
Due to this and the provision of the volume portion 3C, the volume of the branch intake passage 3b on the secondary side is set larger than the volume of the branch intake passage 3a on the primary side. There is. In addition, a concave portion is formed in the volume portion 3C so that the upper mounting bolt can escape, and the concave portion allows the intake air flowing through the flow path in the volume portion 3C to be lowered relative to the center axis of the flow path. It is offset to the side so that it flows. As a result, the intake air enters the suction port while swirling in the rotational direction of the blower Cs impeller, causing the blower Cs to pre-rotate.

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.

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.

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, so that an appropriate boost pressure can be obtained while ensuring an intake flow rate.

For example, when shifting to a high rotation range, the intake relief valve 23 closes, then the intake cut valve 21 opens, and furthermore, exhaust gas is suddenly supplied to the turbine Ts of the secondary side turbocharger 10, and the blower Cs is suddenly turned on. begins to operate. Due to these, the intake pressure changes suddenly near the blower Cs, and this pressure fluctuation propagates to the intake upstream side.

In that case, the volume of the branch intake passage 3b on the intake upstream side of the secondary turbocharger 10 is set larger than the volume of the branch intake passage 3a on the intake upstream side of the primary turbocharger 9. Therefore, the pressure fluctuation is attenuated inside the branch intake passage 3b having a large volume and does not propagate to the air flow meter 4, thereby preventing erroneous detection by the air flow meter 4.

In addition, not only when transitioning to a high rotation range but also when transitioning to a low rotation range, the intake relief valve 23 is opened, the intake cut valve 21 is closed, and the turbine T of the secondary turbocharger 10 is closed.
When the supply of exhaust gas to Cs is stopped, the intake pressure suddenly fluctuates in the vicinity of the blower Cs, but this pressure fluctuation is also attenuated inside the large-volume branch intake passage 3b and does not propagate to the air flow meter 4. Erroneous detection of the air flow meter 4 will be prevented.

Furthermore, since the branch intake passage 3a on the upstream side of the primary side turbocharger 9, which is always in operation, is set smaller than the branch intake passage 3b on the upstream side of the secondary side turbocharger 10,
Intake air is smoothly guided to the primary side turbocharger 9 with reduced passage resistance, and it is possible to ensure an increase in output due to supercharging of the primary side turbocharger 9.

(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 sections, and each branched intake passage is provided with intake air using the energy of exhaust gas. are provided with exhaust turbo superchargers that pressurize the air, at least one of which operates only in a specific operating range, and a branch on the intake upstream side of the exhaust turbo supercharger that operates only in a specific operating range. Since the volume of the intake passage is set larger than the volume of the branch intake passage on the intake upstream side of the other exhaust turbochargers, the pressure fluctuations that occur in the exhaust turbocharger, which operates only in a specific operating range, are It is attenuated inside the large-volume branch intake passage and does not propagate to the air flow meter, making it possible to prevent erroneous detection by the air flow meter.

[Brief explanation of the drawing]

The drawings illustrate embodiments 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 the switching characteristics of six valves, and Fig. 4. is a 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... Evening supercharger, 21... Intake cut valve, 70... Gathering part...
・Center line. 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. In the intake system of a supercharged engine that operates only in a specific operating range, the volume of the branch intake passage on the intake upstream side of the exhaust turbocharger that operates only in the specific operating range is An intake system for a supercharged engine, characterized in that the volume is set larger than the volume of a branch intake passage on the intake upstream side of a charger.