JP2656559B2 - Intake structure of supercharged engine - Google Patents

Description

The present invention relates to an intake structure of a supercharged engine.

(Prior art) As a sequential turbo with two superchargers,
As shown in JP-A-59-68521, it is common practice to arrange a primary turbocharger and a secondary turbocharger in parallel. More specifically, a primary-side intake passage and a secondary-side intake passage that are at least partially parallel to each other are formed in an intake passage of an engine, and a primary-side turbocharger is provided in the primary-side intake passage. Blower) is installed in the secondary-side intake passage.
It is assumed that a secondary turbocharger (blower) is provided. Then, the downstream of the primary side intake passage and the secondary side intake passage is finally merged into one common intake passage. Such a parallel arrangement of the superchargers is the same even if the supercharger is of a supercharger type mechanically driven by an engine. Japanese Patent Application Laid-Open No. 61-283725 also discloses a sequential turbo.

By the way, when the secondary-side supercharger is operated only at the time of high speed, that is, when the engine is shifted from the low-speed state to the high-speed state with the increase of the engine speed, the secondary supercharger is activated. At the time of switching to start the operation of the side supercharger, the backflow phenomenon of the intake air from the primary intake passage to the secondary intake passage through the junction with the common intake passage is likely to occur. Such a backflow phenomenon of intake air causes deterioration of supercharging response at the time of switching and causes torque shock.

In order to prevent the above-mentioned intake air backflow, Japanese Patent Application Laid-Open No. Sho 60-219416 discloses that a primary side intake passage and a secondary side intake passage are merged in an intercooler and two out of a secondary side intake passage. A reed valve (return valve) is provided between the secondary turbocharger and the intercooler, and when the pressure in the secondary intake passage becomes larger than the pressure in the primary intake passage by a predetermined amount, the reed valve is not activated. It is disclosed that the valve be opened. In Japanese Patent Application Laid-Open No. 59-68521, an intake cut valve including an open / close valve is provided downstream of a secondary supercharger in a secondary intake passage, and an upstream pressure of the intake cut valve (secondary pressure) is set. An actuator that is operated by receiving a differential pressure between the downstream side pressure (primary side boost pressure) and the downstream side pressure (primary side boost pressure) is provided, and the secondary side boost pressure becomes larger than the primary side boost pressure. There is also disclosed a device in which an intake cut valve is sometimes opened by an actuator.

JP-A-60-219416 and JP-A-59-68521 described above.
As shown in the publication, when the secondary-side supercharging pressure becomes larger than the primary-side supercharging pressure, the secondary-side intake passage and the primary-side intake passage are communicated with each other. Starting the supply of intake air to the engine using the supply pressure prevents the primary-side supercharging pressure from flowing back to the secondary-side intake passage, prevents torque shock, and increases the supercharging. This is preferable for improving the response.

(Problems to be Solved by the Invention) By the way, from the start of operation of the secondary-side supercharger to the generation of a sufficiently large secondary-side supercharging pressure, that is, the same level as the primary-side supercharging pressure. It takes a considerable amount of time to generate the secondary side supercharging pressure. In this case, if the secondary-side intake passage is closed by the reed valve or the intake cut valve while the secondary-side supercharger is started to operate, a small amount of air in the secondary-side intake passage is discharged to the secondary side. Excessive compression by the supercharger causes so-called surging, which is undesirable from the viewpoint of the durability of the secondary supercharger and the like. In particular, if the operation of the secondary supercharger has been started, but the operation state in which the engine speed hardly increases or only slowly increases continues for a long time, the surging time will be long.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an intake structure of a supercharged engine that prevents a backflow phenomenon of intake air and also prevents surging of a secondary supercharger.

(Means and Actions for Solving the Problems) In order to achieve the above object, the present invention has the following configuration. That is, the intake passage of the engine has a primary-side intake passage and a secondary-side intake passage which are at least partially parallel to each other, and the primary-side supercharger is operated at least at a low speed with respect to the primary-side intake passage. And a secondary-side supercharger, which is activated when the engine speed changes from a low-speed state to a high-speed state with an increase in engine speed, is disposed in the secondary-side intake passage. Each downstream portion of the primary side intake passage and the secondary side intake passage is individually connected to a volume set in the intake upstream side portion of the intercooler, and the primary side intake passage and the secondary side are connected to each other. An intake passage is joined in the intercooler; a downstream intake portion of the intercooler is connected to one downstream common intake passage provided with a throttle valve; Cover between the secondary turbocharger and the intercooler An intake cutoff valve comprising an on-off valve is disposed, and the air in the secondary side intake passage between the secondary side supercharger and the intake cutoff valve is upstream of the secondary side supercharger. A relief passage for relief is provided in the intake passage, a relief valve for opening and closing the relief passage is provided, and the relief valve is opened at least in an operation start state of the secondary supercharger. The intake cut valve is set to be closed with a subsequent increase in the engine speed. The intake cut valve is closed from a low speed state to an operation start region of the secondary side supercharger, and the engine is closed. The relief valve is set to be opened in accordance with an increase in the supercharging pressure downstream of the secondary supercharger after the relief valve is closed as the rotational speed increases. Preferred embodiments of the present invention based on the above configuration are as described in claims 2 and 3 in the claims.

(Effects of the Invention) According to the present invention, the downstreams of the primary-side intake passage and the secondary-side intake passage are merged in the intercooler, particularly in a volume set in the intake upstream portion of the intercooler. Therefore, due to the tamping effect of this volume, 2
This prevents or reduces the phenomenon of backflow of intake air into the secondary intake passage when the secondary supercharger starts operating, that is, torque shock.

Further, since the intake cut valve is opened when the secondary side supercharging pressure is sufficiently increased, the backflow phenomenon of intake air to the secondary side intake passage is more sufficiently prevented or reduced,
Further, this is preferable in terms of improving the supercharging response.

Further, even if the secondary-side supercharger starts to operate, if the secondary-side supercharging pressure is not sufficiently increased, the relief valve is opened and the intake air supercharged by the secondary-side supercharger is reduced by two times. Since the intake passage is relieved to the intake passage upstream of the secondary supercharger, a surging phenomenon can be prevented.

With the configuration as described in claim 2, 2
By pre-rotating the secondary turbocharger in advance, the supercharging responsiveness is dramatically improved, and at the time of this pre-rotation, the relief valve can be opened to prevent the surging phenomenon.

With the configuration as described in claim 3, the valve opening timing of the intake cut valve is appropriately set in consideration of the differential pressure between the primary side supercharging pressure and the secondary side supercharging pressure, This is preferable in that the backflow of intake air to the secondary-side intake passage is more sufficiently prevented.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

Overall System In FIG. 1, an exhaust passage 2 for exhausting exhaust gas of an engine 1 has two branch exhaust passages 2a and 2b extending independently of 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 which are branched on the downstream side of the air flow meter 4 for detecting the intake air amount. Each downstream end with 3b is independently connected to the intercooler 5,
They merge in the intercooler 5. A throttle valve 6, a surge tank 7, and a fuel injection valve 8 are disposed in the intake passage 3 on the downstream side of the intercooler 5.

In one of the two branch exhaust passages 2a and 2b, a turbine TP that is rotationally driven by exhaust gas is disposed in one branch exhaust passage 2a, and the turbine TP is disposed in one branch intake passage 3a. The blower Cp is connected via a rotation axis LP. These turbine TP, rotating shaft LP,
A primary-side turbocharger 9 is configured with the blower Cp as a main element. Similarly, a turbine TS driven by exhaust gas is disposed in the other branch exhaust passage 2b, and a blower CS is disposed in the other branch intake passage 3b. These turbines TP and blower CS Is the rotation axis LS
To form a secondary turbocharger 10.

The passage portions on the upstream side of the blowers Cp and CS of the branch intake passages 3a and 3b are formed so as to face each other at a branch portion branched from the intake passage 3 so as to be linear with each other. The generated pressure wave is applied to the other branch intake passage.
The structure is such that it easily propagates to the 3a side and hardly propagates to the air flow meter 4 side.

An exhaust cut valve 11 is disposed in the secondary branch exhaust passage 2b on the upstream side of the turbine TS. The exhaust cut valve 11 closes the branch exhaust passage 2b in a low rotation range to cut off the supply of exhaust gas to the turbine TS of the secondary turbocharger 10, and shuts off only the primary turbocharger 9. It is provided for operation.

The upstream portion of the exhaust cut valve 11 in the secondary branch exhaust passage 2b is connected to the turbine branch TP upstream of the primary branch exhaust passage 2a via the communication passage 12. The communication passage 12 is connected to a bypass passage 18 in which a waste gate valve 17 is disposed, with respect to the exhaust passage 2 downstream of the turbines TP and TS.
Connected through. The upstream portion of the wastegate 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 through a leakage passage 14 in which the exhaust leakage valve 13 is provided. Have been.

The exhaust leakage valve 13 is operated by a diaphragm type actuator 16, and a pressure chamber of the actuator 16 is connected to a downstream side of a blower Cp of the primary turbocharger 9 via a control pressure conduit 15. The side is open to the branch intake passage 3a. This leak valve 13 is opened when the supercharging pressure P1 on the downstream side of the blower Cp becomes equal to or higher than a predetermined value (for example, 500 mmHg) in the process of increasing the engine speed,
Thus, a small amount of exhaust gas is supplied to the turbine TS through the bypass passage 14 when the exhaust cut valve 11 is closed. Therefore, the turbine TS starts rotating before the exhaust cut valve 11 opens, thereby improving the supercharging responsiveness when the exhaust cut valve 11 is opened and reducing the torque shock.

Reference numerals 19 and 20 denote diaphragm actuators for operating the exhaust cut valve 11 and the waste gate valve 17, respectively. The operation of these actuators will be described later.

On the other hand, in the secondary branch intake passage 3b, an intake cut valve 21 is disposed downstream of the blower Cs. A passage 22 that bypasses the blower CS is provided in the branch intake passage 3b, and a relief valve 23 is provided in the bypass passage 22. The intake cut valve 21 is operated by a diaphragm type actuator 24 as described later. The relief valve 23 opens the bypass passage 22 just before the intake cut valve 21 and the exhaust cut valve 1 are opened and closes the exhaust cut valve 11 in the process of increasing the engine speed. Exhaust Leak Valve 13
Of the blower CS based on the opening operation of the blower CS
It is provided so that the pressure of the branch intake passage 3b between the intake air cut valve 21 and the intake cut valve 21 is prevented from rising, and the blower CS is easily rotated. Such a relief valve 23 is operated by a diaphragm type actuator 25.

A control pressure conduit 26 of an actuator 24 that operates the intake cut valve 21 is connected to an output port of a three-way valve 27 formed of an electromagnetic solenoid valve. Further, a control pressure conduit 28 of the actuator 19 that operates the exhaust cut valve 11 is connected to an output port of a three-way valve 29 similarly formed of an electromagnetic solenoid valve. Actuator that further operates the relief valve 23
Twenty-five control pressure conduits 30 are connected to the output ports of a three-way valve 31 similar to that described above. The control pressure conduit 32 of the actuator 20 that operates the wastegate valve 17 is connected to the output port of a three-way valve 33 composed of an electromagnetic solenoid valve. Three-way valves 27, 29, 31 comprising these electromagnetic solenoid valves and
33 is controlled by a control circuit 35 configured using a microcomputer. The control circuit 35 controls each electromagnetic solenoid based on detected values such as the engine speed Ne, the intake air amount Q, the throttle opening TVO, and the supercharging pressure P1 downstream of the blower Cp of the primary turbocharger 9. Control the valve.

Of 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 the conduit 36.
An intake negative pressure Pn downstream of the throttle valve 6 is introduced into the negative pressure tank 43 via a check valve 37. The three-way valve 27 has one input port connected to the negative pressure tank 43 via a conduit 36, and the other input port connected to an output port of a differential pressure detection valve 39 via a conduit 38. I have.

As shown in FIG. 2, the casing 51 of the differential pressure detecting valve 39 is divided into three chambers 54, 55, 56 by two diaphragms 52, 53, and the chamber 54 has an input port 54a and a chamber 54. Five
5, an input port 55a is opened, and an output port 57 and an atmosphere opening port 58 are connected to the chamber 56. The port 54a is connected to the downstream side of the intake cut valve 21 via the conduit 41 so as to introduce the supercharging pressure P1 downstream of the primary side blower Cp. Port 55a is connected to conduit 42
Is connected upstream of the intake cut valve 21 to introduce a pressure P2 upstream of the intake cut valve 21 when the intake cut valve 21 is closed. When the pressure difference between the pressures P1 and P2 is large, the differential pressure detection valve 39 opens the port 57 with the valve body 59 connected to the two diaphragms 52 and 53 to introduce the atmosphere into the conduit 38. However, when the differential pressure P2-P1 falls within a predetermined value ± ΔP, the port 57 is closed by the spring 59. Therefore, with the three-way valve 27 communicating the conduit 26 with the conduit 38, the differential pressure P2
When −P1 becomes larger than the predetermined value ± ΔP, the air is introduced into the actuator 24, and the intake cut valve 21 is opened.
Also, when the three-way valve 27 allows the conduit 26 to communicate with the conduit 36,
A negative pressure is supplied to the actuator 24, and the intake cut valve 21 is closed. The above-described differential pressure detection valve 39, solenoid valve 27, and control circuit 35 constitute opening / closing control means for the on-off valve 21.

On the other hand, when the three-way valve 29 connects the conduit 28 to the conduit 36,
The negative pressure is supplied to the actuator 19, and the exhaust cut valve 11 is closed. At this time, only the primary side turbocharger 9 is operated. When the three-way valve 29 releases the conduit 28 to the atmosphere, the exhaust cut valve 11 is opened, and the secondary turbocharger 10 is operated.

FIG. 3 is a control map showing the open / closed state of the intake cut valve 21 and the exhaust cut valve 11 together with the open / closed state of the exhaust leak valve 13, the wastegate valve 17 and the relief valve 23. This control map is stored in the control circuit 35. Is stored.

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

Further, a boost pressure P1 is introduced into one input port of the three-way valve 33 through the control pressure conduit 15 of the actuator 16, so that the engine speed Ne and the throttle opening TVO are equal to or higher than predetermined values and are excessive. When the supply pressure P1 exceeds a predetermined value, the control circuit 35 opens the two-way valve 33 and introduces the supercharge pressure P1 to the actuator 20, whereby the wastegate valve
17 opens the bypass passage 18. Further, the other input port of the three-way valve 33 is open to the atmosphere, and when the atmosphere is supplied to the actuator 20, the wastegate valve 17 is closed.

Flowcharts (FIGS. 4A and 4B) FIGS. 4A and 4B show flowcharts for performing control in accordance with the map of FIG. 3 (S is a step, and the exhaust leakage valve 13, the wastegate valve Except for 17). In this flowchart, the flow of the processing changes depending on the flag in one of the ranges from 1 to 6, and the meaning of this flag is as shown in FIG.
That is, since the valves 11, 21, and 23 are each provided with a hysteresis for opening and closing, two characteristic lines are set for each of the valves 11, 21, and 23, and a total of six characteristic lines are set. Having. Then, the flag is changed every time the characteristic line is crossed, and when the operating state is displaced in a direction approaching the region on the right side in FIG. 3 (region on the high rotation and high load side), the flag is set to “2”, It is changed by an even number such as “4” or “6”. Conversely, when the operating state changes to the left area in FIG. 3, the flag is changed with an odd number such as "5", "3", or "1". Of course, at the start of the operation, the flag is set to "1" in the low rotation and low load region (initialization).

Based on the above, the flowchart will be briefly described.

First, the system is initialized at S1 in FIG. 4A, and the flag is set to 1 at this time. Next, in S2, after the engine speed R and the intake air amount Q are inputted, data Q1 to Q6 which determine the above-mentioned six characteristic lines are obtained.
(Intake air amount) and R1 to 16 (engine speed) are read from the map.

After S3, in S4, it is determined whether or not the changing speed of the intake air amount Q is larger than the set value A. In this determination of S4
If YES, in S5, Q1-Q6 read out in S3 above
For each of R1 and R1 to R6, a predetermined amount of decrease correction (ΔQ1
To ΔQ6 and subtraction of ΔR1 to ΔR6), and then the process proceeds to S6. If the determination in S4 is NO, the process proceeds to S6 without going through S5. The process in S5 corresponds to a process for expanding the operating region of the secondary turbocharger 10 to a lower load and a lower rotation speed during acceleration. In S6, it is determined whether the flag F is 1 or not.
Initially, the flag F is initialized to 1, so this determination is YES. At this time, if the determination of S7 or S8 is YES, after the flag F is set to 2 in S9, the relief valve 23 is closed in S10 (negative pressure supply to the actuator 25). If the determinations in S7 and S8 are both NO, the process returns.

If the determination in S6 is NO, in S11, it is determined whether or not the flag F is twice the integer m, that is, whether it is 2, 4, or 6. If the determination in S11 is YES, it is determined in S12 whether the flag F is 2. If the determination in S12 is YES, and if the determination in S13 or S14 is YES, the flag F is set to 4 in S15, and then the exhaust cut valve 11 is opened in S16 (the air is cut off to the actuator 19). Supply). When both the determinations of S13 and S14 are NO, the determinations of S17 and S18 are both YES.
, After the flag is set to 1 in S19, S
At 20, the relief valve 23 is opened (negative pressure is supplied to the actuator 25). If the determination in S17 or S18 is NO, the process is returned.

If the determination in S12 is NO, it is determined whether or not the flag F is 4 in S21. If the determination in S21 is YES,
This is when the flag F is set to 6 or 3, or the process is returned as it is. That is, in either of S22 and S23,
If YES, after the flag F is set to 6 in S24, the intake cut valve 21 is opened in S25 (the actuator 24 is connected to the conduit 38). If the determinations in S22 and S23 are both NO, when the determinations in S26 and S27 are both YES, the flag F is set to 3 in S28, and then in S29
, The exhaust cut valve 11 is closed (supply of negative pressure to the actuator 19). If the determination in any of S26 and S27 is NO, the process returns.

When the determination in S21 is NO, the current flag F is 6. This is the time when the flag F is set to 5 or the process returns. That is, S30 and S
If both the determinations 31 are YES, the flag F is set to 5 in S32, and then the intake cut valve 21 is closed in S33 (a negative pressure is supplied to the actuator 24). If NO in either of S30 and S31, the process returns.

If the determination in S11 is NO, the process shifts to S41 in FIG. 4B. In this S41, it is determined whether or not the flag F is 3. When the determination is YES, the flag F is set to 1 or 4, or the process returns. That is, when both the determinations of S42 and S43 are YES, the flag F is set to 1 in S44, and then the relief valve 23 is opened in S45 (a negative pressure is supplied to the actuator 25). Further, if any of the determinations of S42 and S43 is NO, S46 and S47
Is YES, the flag F is set in S48.
Is set to 4, the exhaust cut valve 11 is opened in S49 (atmospheric supply to the actuator 19). And S4
Returned when both determinations of 6, S47 are NO.

If the determination in S41 is NO, the current flag F is 5. At this time, the flag F is set to 3 or 6, or the process returns. That is, when both the determinations of S50 and S51 are YES, after the flag F is set to 3 in S52, the exhaust cut valve 11 is closed in S53 (negative pressure supply to the actuator 19). Further, if any one of S50 and S51 is NO, S54, S55
When either of the determinations is YES, the flag F is set in S56.
Is set to 6, the intake cut valve 21 is opened in S57 (the actuator 24 is connected to the conduit 38). Then, when both the determinations of S54 and S55 are NO, the process is returned.

Here, the two branch intake passages 3a and 3b are
Are joined. Therefore, when the intake cut valve 21 is opened, the damping action of the intercooler 5
This prevents or reduces the situation in which the intake air flows backward from the primary branch intake passage 3a to the secondary branch intake passage 3b.

In addition, the pressure of the intercooler 5
The fluctuation range of P1 is suppressed as small as possible, and the differential pressure detection valve 39
Can be accurately operated as predetermined. This is even more advantageous in preventing backflow of intake air from the primary-side branch intake passage 3a to the secondary-side branch intake passage 3b. From such a viewpoint, the opening position of the conduit 41 with respect to the intake passage may be set as close to the intercooler 5 as possible (may be inside the intercooler 5).

Although the embodiments have been described above, the present invention is not limited to this, and the supercharger may be a supercharger type mechanically driven by an engine.

[Brief description of the drawings]

FIG. 1 is an overall system diagram showing one embodiment of the present invention. FIG. 2 is a sectional view of the voltage detection valve shown in FIG. FIG. 3 is a characteristic diagram showing switching characteristics of each valve. 4A and 4B are flowcharts when performing control according to the characteristic diagram of FIG. 1: Engine 2: Exhaust passage 2a, 2b: Branch exhaust passage 3: Intake passage 3a: Branch intake passage (primary intake passage) 3b: Branch intake passage (secondary intake passage) 5: Intercooler 7: Surge tank 9: Primary turbocharger 10: Secondary turbocharger Tp: Turbine (primary side) Ts: Turbine (secondary side) Cp: Blower (primary side) Cs: Blower (secondary side) Lp: Rotary shaft (primary side) Ls: Rotary shaft (secondary side) 21: Intake cut valve (open / close valve)

 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroshi Sasaki 3-1 Shinchi, Fuchu-cho, Aki-gun, Hiroshima Prefecture Inside Mazda Co., Ltd. (56) References JP-A-60-219416 (JP, A) JP-A Sho-56 JP-A-41417 (JP, A) JP-A-61-182421 (JP, A) JP-A-61-190121 (JP, A) JP-A-1-285619 (JP, A) JP-A-60-166716 (JP, A) )

Claims (3)

(57) [Claims] An intake passage of an engine has a primary intake passage and a secondary intake passage which are at least partially parallel to each other, and a primary operated at least at a low speed with respect to the primary intake passage. A side-side supercharger is provided, and a secondary-side supercharger that is started to operate when a transition from a low-speed state to a high-speed state with an increase in engine speed is provided in the secondary-side intake passage. Each downstream portion of the primary side intake passage and the secondary side intake passage is individually connected to a volume set in the intake upstream side portion of the intercooler, and is connected to the primary side intake passage and the secondary side intake passage. A downstream side intake passage is joined in the intercooler; a downstream portion of the intake of the intercooler is connected to one downstream common intake passage provided with a throttle valve; Between the secondary supercharger and the intercooler Intake cut valve consisting off valve is disposed, the between the intake cut valve and the secondary side supercharger 2
A relief passage for relieving air in a secondary intake passage to an intake passage upstream of the secondary supercharger; a relief valve for opening and closing the relief passage; and a relief valve Is set to open at least in an operation start state of the secondary-side supercharger, and to be closed with a subsequent increase in the engine speed. The supercharging pressure rises downstream of the secondary supercharger after the relief valve is closed as the engine speed increases while the valve is closed to the operation start area of the secondary supercharger. The intake structure of a supercharged engine, characterized in that the intake structure is set so as to be opened with the valve. 2. The turbocharger according to claim 1, wherein the primary-side supercharger and the secondary-side supercharger are each an exhaust turbocharger. Is slightly supplied to the secondary-side supercharger, the secondary-side supercharger is brought into a pre-rotation state. When the secondary-side supercharger is in the pre-rotation state, the intake cut valve is closed. The intake structure of a supercharged engine, wherein the intake valve is opened and the relief valve is opened. 3. The secondary supercharger and the intake cut valve according to claim 2, wherein the intake cut valve is provided when the relief valve is closed and the intake cut valve is closed. Between the downstream side of the intake cut valve and the volume of the intercooler and the downstream side of the primary side supercharger from the downstream side of the intake cut valve. The pressure applied to the intake passage 1
The turbocharged engine is configured to be opened and closed according to the differential pressure from the secondary supercharging pressure and to be opened as the secondary supercharging pressure increases. Intake structure.