JPH0242168A - Intake structure for engine with supercharger - Google Patents

Abstract

PURPOSE:To prevent the intake additive gas from sticking to a secondary supercharger by providing a passage circulating the intake additive gas such as the blow-by gas to the intake passage of an engine and opening its discharge port at the specific position of the intake passage. CONSTITUTION:Two turbines Tp and Ts and blowers Cp and Cs are arranged on two branch exhaust passages 2a and 2b and branch intake passages 3a and 3b of an engine 1 respectively to constitute the primary and secondary turbo superchargers 9 and 10. In this case, a passage 81 circulating the intake additive gas such as the blow-by gas to an intake passage 3 is provided. The discharge port of the circulating passage 81 is opened at the position to have an intake stream not passing the secondary supercharger 10 at the upstream of the primary supercharger 9 and in the non-operational region of the secondary supercharger 10. The intake additive gas is prevented from sticking to the secondary supercharger 10.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an intake structure for a supercharged engine.

(Prior art) In an exhaust turbocharged engine, as shown in Japanese Utility Model Application Publication No. 50-178329, there is a primary side turbocharger and a secondary side turbocharger, which is called a sequential turbo. At low speeds, only the primary turbocharger is operated to achieve the first state with low supercharging capacity, while at high speeds both turbochargers are operated to maintain the supercharging capacity. It has been proposed to have a larger second state. That is, by making the primary side turbocharger that is always operated small-sized, responsiveness at low speeds is ensured. On the other hand, at high speeds, large supercharging capacity can be obtained by operating both turbochargers.

On the other hand, additional intake gases such as blow-by gas and evaporative gas are often recirculated to the engine intake passage. Generally, the discharge port of this recirculation passage for recirculating the intake additional gas is often opened to the intake passage downstream of the throttle valve. In engines equipped with a supercharger, it has been considered to open the discharge port of the recirculation passage in the intake passage upstream of the supercharger in order to more actively recirculate the intake additional gas.

(9!Problem that Ming tries to solve) However, 2
For those equipped with a next-side supercharger, the intake additional gas
1, if the flow is recirculated (discharged) to the intake passage upstream of the turbocharger, a large amount of additional intake gas will adhere to the secondary turbocharger when it is not operating. This causes problems such as malfunction.

Therefore, an object of the present invention is to provide an intake structure for a supercharged engine that can prevent the adverse effects of intake additional gas on the secondary supercharger.

(L stage and operation for solving the problem) In order to achieve the above-mentioned [1], the present invention has the following configuration. In other words, in a supercharged engine that is equipped with a primary side supercharger that operates all the time and a secondary side supercharger that operates only in a specific operating range, the intake air exclusively for blow pie gas and evaporative gas is used. A recirculation passage is provided for recirculating the additional gas to the intake passage of the engine, and a discharge port of the recirculation passage is located in the intake passage of the engine.
It is opened at a position where the intake air flow is -L flow of the primary side turbocharger described in INI and does not pass through the secondary side turbocharger in the non-operating area of the secondary side turbocharger described in 11. The structure is as follows.

With such a configuration, 1 which is always activated
Next side turbocharger - While setting the recirculation effect of the intake additional gas to be preferable by recirculating the intake additional gas to the upstream side, the intake additional gas is increased to 1) with respect to the secondary side turbocharger which is not in operation. A 11 degree situation that would result in adhesion is avoided.

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

In FIG. 1, an exhaust passage 2 for discharging exhaust gas from an engine 1 has two branch exhaust passages 2a and 2b extending independently from the engine 1. In addition, 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 intake air intake. 3
b merges with the intercooler 5 on the upstream side. A throttle valve 6 , a surge tank 7 , and a fuel injection valve 8 are arranged in the intake passage 3 on the downstream side of the intercooler 5 .

A turbine TP rotatably 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 rotation axis is attached to the installed blower CP, P
are connected via. And these turbines TP
, a rotating shaft LP, and a blower CP as main elements, a primary turbo supercharger 9 is constructed. 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 3
A blower CS is disposed at b, and the turbine TP and blower C8 are connected by a rotating shaft LS to form a secondary turbo supercharger 10.

The passage portions of the branched 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 a pressure wave generated in one branch intake passage 3b easily propagates to the other branch intake passage 3a side, easily propagates to the air flow meter 4 side, and hardly propagates to the air flow meter 4 side. There is.

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.
is provided 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
F, the downstream portion 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 the turbines TP and TS via a bypass passage I8 in which a wastegate valve 17 is disposed. The upstream side of the E7 exhaust gate valve 17 of this bypass passage 18 is the leakage passage 1 in which the exhaust leakage valve 13 is disposed.
4, it is connected between the turbine TS and the exhaust cut valve 11 in the branch exhaust passage 2b.

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 PI on the downstream side of the blower Cp reaches a predetermined value (for example, 500 mmHg) or more, the blower Cp is opened, and when the exhaust cut valve 11 is closed, the exhaust gas of insects is 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 and alleviating torque shock when the five exhaust cut valves 11 open.

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 C3.
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. Due to the rotation of the blower C3 based on the opening operation of the leakage valve 13, the blower C3
The blower C3 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 C3. 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 boat.

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 3o of the actuator 25 for actuating the relief valve 23 is connected to the output boat of the three-way valve 31 similar to that described above.

The control pressure conduit 32 of the actuator 20 which operates the wastegate valve 17 is connected to the output port of a three-way valve 33 consisting of an electromagnetic solenoid valve. The three-way valves 27, 29, 3I and 33 made of these electromagnetic sirenoid valves are
Control circuit 3 configured using a microcomputer
Controlled by 5. This control circuit 35 controls each electromagnetic solenoid valve based on detected values such as engine speed Ne, intake air 1Q, throttle opening TVO, and downstream pressure pt of the blower CP of the primary side turbocharger 9. Control.

Among the four electromagnetic solenoid valves, one manual boat of the three-way valve 29 is open to the atmosphere, and the other input boat 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 boat 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 inside of the differential pressure detection valve 39 is defined into three chambers 54, 55, 56 by two diaphragms 52, 53, and an input boat 54a is connected to the chamber 54. An input boat 55a is opened at 55, and an output boat 57 and an air release boat 58 connected to the conduit 38 are opened at the chamber 56. The boat 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 boat 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 2I is closed. There is. When the pressure difference between pressure pt and P2 is large, this differential pressure detection valve 39 detects the valve body 59 connected to both diaphragms 52 and 53.
The boat 47 is opened and atmospheric air is introduced into the conduit 38, but when the differential pressure P2-P1 falls within a predetermined value ±ΔF), the boat 57 is closed by a spring 59. Therefore, the three-way valve 27
When the differential pressure P2-P1 becomes larger than the predetermined value ±△P while the actuator 24 is in communication with the conduit 38, the actuator 24
Atmospheric air is introduced into the air, 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. In addition, the three-way valve 29
8 is released to the atmosphere, the exhaust cut valve 11 is opened,
The secondary side turbocharger IO is activated.

FIG. 3 shows the open/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 boat of the three-way valve 31 is also opened to the atmosphere, and the other input boat 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. However, in the process of increasing the engine speed Ne, as shown in FIG. In this case, the three-way valve 3I 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.

Further, 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 PI 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. 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.

Flowchart (Figures 4A, 4B, 4A, 4
FIG. B shows a flowchart for performing control according to the map in FIG. 3 (S is a step, excluding the exhaust leak valve 13 and waste gate valve 17). In this flowchart, the flow of processing changes depending on which flag is in the range of 1 to 6, and the meaning of this flag is as shown in FIG. That is,
Since each valve 11.21.23 has a hysteresis for opening and closing, two characteristic lines are set for each valve 11.21.23, making a total of six characteristic lines. . stop.

The flag is changed each time this characteristic line is crossed, and when the operating state moves toward the region on the right side of Figure 3 (high rotation, high load region), the flag changes to "2", "4
” or an even number like “6”. Conversely, when the operating state changes to the area on the left side of FIG. 3, the flag is changed to an odd number such as "5", "3", or NJ. Of course, at the start of operation, the flag is set to NJ (initialization) in the low rotation and low load region.

Based on the following premise, the flowchart will be briefly explained.

First, the system is initialized at 31 in FIG. 4A, and the flag is set to 1 at this time. Then, S
In step 2, after the engine speed R and intake air mQ are input, Q, which determines the six characteristic lines mentioned above, is determined.
After 1° S3 in which l-Q6 (intake air information) and R1-16 (engine speed) are read from the map, it is determined in S4 whether the rate of change of the intake air it Q is greater than the set value. 1, this S
If the determination in step 4 is YES, in S5, F, I?
Q1-Q6 and R1-R6 read by LE S3
For each of
(subtraction of ΔR1 to ΔR6) is performed, and then the process moves to S6. Moreover, when the determination in S4 is No, the process proceeds to S6 without passing through S5. The process in S5 above corresponds to a process for expanding the operating range of the secondary side turbocharger 10 to a lower load and lower rotation side during acceleration. .

In S6, it is determined whether the flag F is 1 or not.
Initially, the flag F is initialized to l, so this determination is YES. In this case, S7 or S8
If the determination is YES, the flag F is set to 2 in S9, and then the relief valve 23 is closed in Sl0 (negative pressure is supplied to the actuator 25).1. Also,
If both of the determinations in S7 and S8 are NO, the process returns as is.

When the determination in S6 is No, the flag F is set in S11.
It is determined whether or not is twice the fixed fim, that is, whether it is either 2.4 or 61. If the determination of this Sll is YIES, the flag F is set to 2 in SI2.
It can be determined whether or not. This S[2 is determined as YES
When S, YES is determined by either SI3 or SI4.
At this time, after the flag F is set to 4 in S15, the exhaust cut valve 11 is opened in S+6 (atmosphere is supplied to the actuator 19). Further, when both the determinations in S13 and S14 are NO, when the determinations in SX7 and SL8 are both YES, the flag is set to 1 in S19, and then the relief valve 23 is opened in S20 (actuator 25). Also S17 or S1
If any of the determinations in step 8 is No, the process returns.

When the determination in S12 is No, it is determined in S21 whether or not the flag F is 4, and the determination in S21 is YES.
When it is S, the flag F is set to 6 or 3, or the process returns as is. That is, S22, S23
If YES in any of the above determinations, the flag F is set to 6 in S24, and then the intake cut valve 21 is opened in S25 (the actuator 24 is communicated with the conduit 38). Further, when both the determinations in S22 and S23 are NO, and when the determinations in S26 and S27 are both YES, the flag F is set to 3, and then the exhaust cut valve II is closed in S29 (to the actuator 19). negative pressure supply). If the determination in either 826 or S27 is No, the process returns directly.

If the determination in S21 is No, it means that the current flag F is 6. At this time, it is time to set flag F to 5 or simply return. That is, when both determinations in S30 and S31 are YES, S3
After the flag F is set to 5 in step S33, the intake cut valve 21 is closed (negative pressure is supplied to the actuator 24).

Further, if the determination in either S30 or S31 is No, the process returns directly.

When the determination in S11 is No, the process moves to 341 in FIG. 4B. In step 341, it is determined whether the flag F is 3 or not. If this determination is YES, it is time to set flag F to 1 or 4 or to return as is. That is, both determinations in S42 and S43 are YES.
At this time, after the flag F is set to 1 in S44, the relief valve 23 is opened in S45 (negative pressure is supplied to the actuator 25). Further, when either the determination in S42 or S43 is No, and if the determination in S46 or S47 is YES, the flag F is set to 4 in 848, and then the exhaust cut valve 11 is set in S49.
is opened (air supply to actuator 19). Then, if both of the determinations in S46 and S47 are No, the process returns.

If the determination in S41 is No, the current flag F is 5.
It's time. At this time, it is time to set flag F to 3 or 6, or to return as is. That is, when both the determinations in S50 and S51 are YES, the flag F is set to 3 in S52, and then the exhaust cut valve 11 is closed in S53 (the actuator 1
Negative pressure supply to 9). Also, S50. When any of the determinations in S51 is NO, and when any of the 11 determinations in S54 and S55 is YES, the flag F is set to 6 in S56, and then the intake force/soto valve 21 is opened in S57. (Communicating actuator 24 to conduit 38). Then, the determination of the I/X deviation in S54 and S55 is also returned when the result is N'O.

11 Air/additional gas'i1゛Wu1 Now, referring to Figure 5, we will explain the recirculation system for the intake additional gas. It is said to be a low-resolution piston engine.

First, the blow-by gas from inside the engine 1 is passed through the purge passage 7 connected to the intermediate housing.
2, and is discharged into the intake passage 3 directly flowing through the throttle valve 6. A negative pressure operated purge valve 73 is connected to this purge passage 72, and the pressure chamber of this purge valve 73 is communicated via a conduit 74 with the direct flow of the throttle/sottle valve 6 when the valve is closed. . Thereby, when the throttle valve 6 opens, the purge valve 74 opens when it receives the intake negative pressure introduced through the conduit 74, thereby opening the purge passage 72.

On the other hand, the evaporative gas from the gasoline tank 75 is
6, and a reverse IL valve 78 that only allows flow toward the canister 77 is connected to this passage 7.

10, 1; own canister 77 is +if via passage 79
:i is in communication with the purge passage 72, and in this passage 79.

A reverse valve 80 is connected that allows flow only from the canister 77 to the passage 72.

From the passage 79, a recirculation passage 81 is branched from the downstream side of the reversal valve 80, and the tip of this recirculation passage 8, that is, the side that becomes the discharge port, is connected to the blower cp of the primary side turbocharger 9.
It opens into the upstream branch intake passage 3; 1 (see Fig. 1). A reverse 11'' valve 82 is connected to the recirculation passage 81 to allow flow only toward the one-branch intake passage 3a.

In the above configuration, when the intake pressure becomes negative, the intake additional gas such as proby gas and evapo gas,
When the purge valve 73 opens, the air is returned to the intake passage 3 via the purge passage 72. On the other hand, when the primary side turbocharger 9 is sufficiently operated in the supercharging zone, the reverse valve 82 opens and the intake additional gases of blow-by gas and evaporative gas are returned to the branch intake passage 3a. . 1-FIG. 6 shows the recirculation state of the intake additional gas mentioned above depending on the operating state of the engine l, and in this FIG.
1 indicates the region where the purge valve 73 opens, and region IT indicates the region where the reverse IF valve 82 opens.

When the intake additional gas is recirculated to the branch intake passage 3a, 2
Even if the next turbocharger IO is in the 2nd stop+L L state (it may be rotating slightly even when it is not operating),
The intake additional gas passes only through the blower CP of the primary turbocharger 9 without passing through the secondary turbocharger 10 (its blower Cs), and is guided into the combustion chamber of the engine I.

FIG. 7 shows an embodiment in which the engine 1 is of a reciprocating type, and the same components as those in FIG. 5 are given the same reference numerals. In this embodiment, only the evaporative gas is recirculated and controlled by the purge valve 7:3, and the purge passage 91 to which the purge valve 73 is connected is opened to the flow from the throttle valve 6.

On the other hand, the blow-by gas is configured to flow back downstream of the throttle valve 6 and to the aforementioned branch intake passage 3a. That is, a first recirculation passage 92 for blow-by gas extending from the engine 1 is opened to the intake passage 3 downstream of the throttle valve 6, and the i-th recirculation passage 91 is opened when the differential pressure downstream reaches a predetermined value or higher. Purge control valve 93
is connected. Further, a second recirculation passage for blow-by gas extending from the engine 1 is shown as 81',
This second recirculation passage 81' opens into the branch intake passage 3a, similar to the recirculation passage 81 in FIG. 5.

Note that the reflux position of the intake additional gas, that is, the reflux passage 81
．． The opening position of 81' with respect to the intake passage may be on the −L flow side of the arrow X in FIG.
2, it may be located closer to the branch intake passage 3a than the portion indicated by the symbol Y in FIG.

Although the embodiment has been described above, the present invention is not limited to this, and the present invention is not limited to this.
and may be connected in series with each other in the flow direction of the exhaust gas. That is, the intake air supercharged by the primary turbocharger 9 may be further supercharged by the secondary turbocharger IO. Of course, in that case, when the secondary side turbocharger 10 is not operating and is in communication, a bypass path is provided to bypass the secondary side turbocharger 10 and allow intake air to flow. Further, the supercharger may be of a supercharger type driven opportunistically by the engine 1.

(Effects of the Invention) As is clear from the above description, the present invention actively recirculates intake additional gas to the intake passage using the supercharger, and adds a large amount of intake air to the secondary turbocharger. IF can be prevented from causing gas to adhere.

[Brief explanation of the drawing]

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. 1. FIG. 33 is a characteristic diagram showing the switching characteristics of each valve. Fig. 4 Δ, Fig. 4 [Fig. 3 is a flowchart when performing control according to the characteristic diagram of Fig. 3; FIG. 5 is a diagram showing a recirculation system for intake additional gas in a rotary piston engine. FIG. 6 is a diagram showing how the intake additional gas is recirculated depending on the operating state of the engine. FIG. 7 is a diagram showing a recirculation system for intake additional gas in the case of a reciprocating engine. l: Engine 2: Exhaust passage 2a, 2t): Branch exhaust passage 3: Intake passage 3a, 3b: Branch intake passage 9: Primary turbo supercharger 10: Secondary turbo supercharger Tp: Turbine (primary side) Ts: Turbine (secondary side) Cp nib blower (primary side) Cs nib blower (secondary side) 1,,, p: Rotating shaft primary side) Reflux passage No. 5 Fig. 6 Carrot side rotation

Claims (1)

[Claims] (1) In a supercharged engine in which the engine is equipped with a primary side supercharger that operates all the time and a secondary side supercharger that operates only in a specific operating range, blow-by gas, evaporative gas, etc. A recirculation passage is provided for recirculating the intake additional gas to the intake passage of the engine, and a discharge port of the recirculation passage is located in the intake passage of the engine.
It is characterized in that it is opened upstream of the primary supercharger and at a position where the intake air flow does not pass through the secondary supercharger in a non-operating area of the secondary supercharger. Intake structure of a supercharged engine.