JPS61200331A - Multi-turbocharger - Google Patents

Abstract

PURPOSE:To prevent the occurrence of a torque drop at the time of starting a turbocharger at the latter stage, by making a suction system out of a turbocharger at the previous stage selectable to a suction pipe, supercharging an engine directly, and another suction pipe having a resonance supercharger either. CONSTITUTION:At low speed and low load zones, a valve 124 is opened, making a second turbocharger 102 into a nonoperational state, and supercharged air by a compressor 101B of a first turbocharger 101 is directly fed to an engine via a suction selector valve 122 and a suction passage 106. Next, with a rise in rotation, a waste gate valve is started to open, driving the second turbocharger 102, and at that point that supercharging pressure of more than the specified pressure is produced, a check valve 112 is opened. And, at this time, the suction selector valve 122 is selected to a resonance suction system, while a selector valve 25 is closed whereby the supercharging air made by each of these compressors 101B and 102B is fed to the engine via resonant pipes 121A and 121B, and resonant boxes 120A and 120B.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a multi-turbocharger, and more specifically, it includes a plurality of turbochargers, and a part of the exhaust gas supplied to the previous turbocharger is transferred to the rear stage depending on the operating range of the internal combustion engine. This invention relates to a multi-turbocharger that efficiently obtains supercharging pressure by supplying it to a turbocharger.

[Prior art]

In a turbocharger for an internal combustion engine, the supercharging efficiency is maximum at a certain exhaust gas flow rate, and the supercharging efficiency decreases at other exhaust gas flow rates. However, the flow rate at which supercharging efficiency is maximized varies depending on the turbocharger.
In the case of a turbocharger with a small diameter exhaust turbine, the supercharging efficiency is maximized in the low speed range of the engine with a small gas flow rate, and in the case of a turbocharger with a large diameter exhaust turbine, the supercharging efficiency is maximized in the high speed range of the engine with a large gas flow rate. Supercharging efficiency is maximized.

Therefore, as described above, a multi-turbocharger device as shown in FIG. 3 has been proposed in which a plurality of turbochargers are installed to obtain high supercharging efficiency in the front operating region of the engine.

This example is disclosed in Japanese Unexamined Patent Publication No. 59-68521. Here, ■ is a relatively small-capacity first turbocharger, 2 is a second turbocharger with a larger capacity than the first turbocharger in the rear stage, and the first turbocharger 1 is supplied by its exhaust turbine IA from the exhaust passage 4 of the engine 3. The compressor IB is rotated by the exhaust gas, and the coaxial compressor IB is rotated to supercharge the intake air, and the pressurized intake air is supplied to the combustion chamber 3A of the engine 3 through the first branch intake passage 5 and the intake passage 6. do.

7 is an exhaust pressure control type waste gate valve, and the exhaust passage 4
When the engine load is small, such as when the amount of exhaust gas in the exhaust gas is small, the exhaust gas pressure is low, so the wastegate state is maintained and the branch flow to the first bypass passage 8 is cut off. Further, when the engine load increases, the exhaust pressure increases, so the valve body 7A opens S, and the exhaust gas flows through the first bypass passage 8 to the second turbocharger 2.
The exhaust gas is supplied to the exhaust turbine 2A and begins to drive it.

Note that a second bypass passage IO is provided between the first bypass passage 8 and the exhaust passage 9 from the exhaust turbine 2A, and this second bypass passage IO is an intake pressure adjustment type that is controlled by the intake pressure. The opening and closing of the second wastegate valve 11 is controlled by the valve body 11A of the second wastegate valve 11.

12 is a check valve provided in the second branch intake passage 13 from the compressor impeller 2B of the second turbocharger 2;
This check valve 12 is configured so that the intake pressure from the second turbocharger 2 is equal to the intake pressure from the first turbocharger 1 obtained from the side of the first branch intake passage 5, and the spring 12A incorporated in the reverse check valve 12. The valve is opened when the force is overcome, and supercharged air from the second turbocharger 2 is supplied to the engine combustion chamber 3A via the second branch intake passage 13 and the intake passage 6.

Further, until such a state is reached, the check valve 12 is held in place by the spring 12.
It is kept in a closed state by the spring force of A, and prevents supercharged air from the first turbocharger 1 from flowing back to the first turbocharger side. Note that 14 is an air intake passage.

In the multi-turbocharger configured in this way, the first turbocharger l is first driven by the exhaust gas from the engine 3, but when the load is low, the gas pressure of the exhaust gas is also low, so the wastegate valve 7 is closed. The supercharged air from the first turbocharger 1 is supplied to the engine 3 via the first branch intake passage 5 and the intake passage 6 while maintaining the above state.

Furthermore, when the load on the engine 3 increases, the gas pressure in the exhaust passage 4 increases as the exhaust gas increases, and the wastegate valve 7 is opened, allowing a portion of the gas to pass through the first bypass passage 8 and pass through the exhaust passage 4. 2 turbocharger exhaust turbine 2A
supplied to As the rotation of the turbine 2A increases, the boost pressure in the second branch intake passage 13 increases. 12A, the check valve 12 is opened and supercharging pressure from the second turbocharger 2 begins to be supplied to the engine 3.

Furthermore, when the supercharging pressure from the second turbocharger 2 becomes higher than a predetermined pressure, a portion of the intake air is released to the exhaust passage 9 via the second bypass passage 10 due to the opening operation of the second waste gate valve 11. In this way, it is possible to maintain high supercharging efficiency in almost the entire operating range of the engine 3.

However, in such a conventional multi-turbocharger, the wastegate valve 7 of the first turbocharger 1 is opened and the second turbocharger 2 begins to be driven at the stage of transition from the desired low load region to the high load region. The configuration is such that only the supercharging pressure from the first turbocharger 1 is supplied to the engine 3 until the supercharging pressure obtained from the second turbocharger 2 reaches the supercharging pressure from the first turbocharger l. There was a problem in that the required air flow rate of the engine could not be met, the boost pressure decreased, and the torque of the engine 3 decreased.

〔the purpose〕

The purpose of the present invention is to focus on such problems,
In order to solve this problem, it is an object of the present invention to provide a multi-turbocharger that prevents a drop in torque at the stage when a part of the exhaust gas supplied to the front-stage turbocharger starts to be diverted to the rear-stage turbocharger.

〔composition〕

In order to achieve such an object, the present invention allows the intake system from the front-stage turbocharger to be switched between an intake pipe that directly supercharges the engine and an intake pipe that has a resonance supercharging device. , when the engine is in a low load range, while the wastegate valve for the front turbocharger installed in the engine exhaust passage is not opened, and when sufficient boost pressure is obtained from the rear turbocharger. Supercharging is performed through the intake pipe that supplies air directly to the engine, and the resonance supercharging device is operated until sufficient supercharging pressure is obtained from the rear turbocharger after the wastegate valve starts opening. The intake system can be switched to

〔Example〕

Embodiments of the present invention will be described in detail and specifically below based on the drawings.

FIG. 1 shows an embodiment of the present invention. In this embodiment, the cylinders of a multi-cylinder engine 113 are divided into two groups whose intake air does not overlap with each other, and the intake pipes 113A are arranged.

113B to resonance boxes 120A and 12, respectively.
0B is provided, and resonance tubes 121A and 121B are further connected to these resonance boxes 12OA and 120B to form resonance tube 1.
The supercharged air outlet side of the first compressor 101B of the first turbocharger is connected to 21A and 121B via the intake switching valve 122.

Furthermore, 106 is an intake passage for directly supplying supercharged air from the first turbocharger 101 and the second turbocharger 102 to the engine 113, and the supercharged air from the first turbocharger 101 is transferred to a resonance pipe by an intake switching valve 122. The intake path can be switched between the 121A and 121B sides and the intake passage 106 side.

In addition, a first turbocharger 101 is provided in the intake passage 10B.
A check valve 112 is inserted to prevent the supercharged air from flowing back toward the compressor 102B of the second turbocharger 102 when supercharging is performed. Furthermore, 114 is an air intake passage to both compressors 101B and 102B, 104 is an exhaust passage that guides exhaust gas from the engine 113 to the first exhaust turbine 10IA and the second exhaust turbine 102A, and 10? is a wastegate valve for the first turbocharger 101, and 108 is its first bypass passage. Further, a valve 124 is provided in the middle of a branch exhaust passage 123 that guides gas to the turbine 102A of the second turbocharger 102, and is closed in a low load range of the engine 113.

125 is a switching valve that is opened to directly connect the resonance boxes 12OA and 120B, and while the resonance supercharging system is in use, this switching valve 125 is kept closed;
No intake air is supplied to either resonance box 120A or 120B.

The supercharging operation by the multi-turbocharger configured in this way will be described below. First, in the low rotation and low load region, the valve 124 disposed in the branch exhaust passage 123 is kept closed, and the exhaust gas from the engine 113 exclusively drives the turbine 10IA of the first turbocharger 101.

At this time, the compressor 10 of the first turbocharger 101
The intake side outlet of 1B is switched to the intake passage 106 side by an intake switching valve 122, and when the switching valve 125 is open, supercharging air is supplied to both cylinder groups, and the small capacity turbocharger is used. A normal type of overmatch is made.

Next, when the rotation increases from the low load range, the waste gate valve 107 begins to open and the second exhaust turbine 102A begins to rotate as the amount and pressure of the exhaust gas increases. Note that the valve 124 is closed at this time. Thus, in the second turbocharger 102, supercharging air begins to be generated by the second compressor 1'02B, but the check valve 112 is configured similarly to the check valve 12 in FIG. 3, and the second compressor 102B The check valve 112 will not be opened unless the boost pressure generated by the first compressor 101B exceeds the boost pressure generated by the first
There is no supercharging from compressor 102B.

However, in this example, at the same time as the Westgate valve 107 starts to open, the intake switching valve 122 is switched to the resonant intake system, and one switching valve 125 is closed, and the first compressor 1
The supercharged air from 01B is sent to resonance pipes 121A and 121B.
are led to the resonance boxes 12OA and 120B, where a resonance supercharging effect can be obtained.

In other words, a resonant supercharging device attempts to increase the charging efficiency of the intake air by matching the pulsation of the intake air with the natural vibration of the intake system to generate a resonance phenomenon. The supercharging air at a constant pressure is vibrated through a resonant supercharging system, and the opening timing of the intake valve is adjusted when the pressure wave peaks higher than the original pressure, thereby increasing the supercharging pressure. can be further enhanced.

Therefore, in such resonance supercharging, a larger amplitude can be obtained as the source supercharging pressure is higher, and when the waste gate valve 107 is opened as in this example, the resonance supercharging effect is most efficiently achieved. It can be said that favorable conditions are in place for obtaining this. Thus, in this example, the first turbocharger 101
When the torque decreases when switching from to the second turbocharger 102, the resonant supercharging effect can be used to compensate for the drop. At the beginning of supercharging, the base pressure is still almost maintained, so there is less difference in amplitude due to switching of intake air to the resonant supercharging system.

Further, as the load range of the engine 113 shifts to a higher side, the supercharging pressure from the second turbocharger 102 gradually increases and catches up with the supercharging pressure from the first turbocharger 101, and the check valve 112 closes. At the same time as the valves are opened, the intake switching valve 122 and the switching valve 125 are also switched, the valve 124 provided in the branch exhaust passage 123 is opened, and the supply of supercharged air by the second turbocharger 102 is started. Note that here, the switching valve 125 is switched so that the resonance box 1
By integrating 20A and 120B, adverse effects from the resonance supercharging system are prevented.

FIG. 2 shows another embodiment of the invention. In this example, the resonance system is made variable so that the resonance supercharging effect can be obtained over a wide rotation range, and in other words, the difference in capacity between the first turbocharger and the second turbocharger is relatively large. This is a suitable example in this case.

In this example, the resonance boxes 12 of the resonance tubes 131A and 131B are
Movable tubes 132A and 132B with variable protrusion lengths are disposed at the connecting portions with 0A and 120B, respectively, and the resonance point is changed by moving the movable tubes 132A and 132B in the direction of the arrow. Note that the other configurations are the same as in FIG. 1.

In the multi-turbocharger configured in this manner, as described above, by moving the movable tubes 132A and 132B at the stage when the supercharging operation is expanded from the first turbocharger 101 to the second turbocharger 102, a wide resonance supercharging effect can be achieved. can be obtained.

In addition, although the above embodiment was a case of a multi-turbocharger configured with two turbochargers, the application of the present invention is not limited to the case where the number of turbochargers to be combined is two. Needless to say, the same configuration can be applied even when the charger is driven sequentially depending on the load range of the engine.

In such a case, until the supercharging pressure from the next stage turbocharger becomes the supercharging pressure from the previous stage turbocharger, switching to a resonant supercharging system as explained in the example of FIG. 1 or FIG. By arranging related valves, etc., the above-mentioned effects can be obtained one after another.

〔effect〕

As described above, according to the present invention, in a multi-turbocharger including a plurality of turbochargers and in which the next-stage turbochargers are sequentially driven according to the load range of the engine, the first-stage turbocharger is The intake system downstream from the compressor of the charger can be freely switched between an intake path that sends supercharged air directly to the engine and a path that sends supercharged air to the engine via resonance supercharging means, and When the wastegate valve is opened and the next stage turbocharger starts to be driven, the supercharging air from the previous stage turbocharger is switched and supplied to the resonance supercharging means side, and the supercharging pressure from the next stage turbocharger is increased. The above supply state is maintained until the turbocharger reaches the supercharging pressure from the previous stage turbocharger. A drop in torque can be prevented, and good supercharging efficiency can be maintained over a wide engine load range.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an example of the configuration of a multi-turbocharger according to the present invention, FIG. 2 is a schematic diagram showing a configuration of another embodiment of the invention, and FIG. 3 is a configuration diagram showing an example of a conventional multi-turbocharger. It is a diagram. 1, 101...first turbocharger, 2.202
...Second turbocharger, IA, l0IA...
・First exhaust turbine, I B , l0IB... First compressor, 2 A, 202A... Second exhaust turbine, 2
B, 202B...second compressor, 3.113...
Engine, 3A... Combustion chamber, 4.104... Exhaust passage, 5.13... Branch intake passage, 6.108... Intake passage, 7.107... Waste gate valve, 7A, IIA ...Valve body, 8.10.108...Bypass passage, 9, IO9...
・Discharge passage, 11... Waste gate valve, 12.122... Check valve, 12A... Spring, 14.114... Air intake passage, 12OA, 120B... Resonance box, 121A, 121B... Resonance pipe, 122... Intake switching valve, 123... Branch exhaust passage, 124... Valve, 125... Switching valve, 131A, 131B... Resonance pipe, 132A, 132B...・Movable tube.

Claims (1)

[Claims] In a multi-turbocharger having a plurality of turbochargers, the rear turbocharger is driven by the exhaust gas supplied through the waste gate valve of the front turbocharger according to the engine load condition. The intake system downstream of the turbocharger includes a first intake system that can directly supercharge the engine, a second intake system that supercharges the engine via resonance supercharging means, and a second intake system that supercharges the engine via resonance supercharging means, and a second intake system that supercharges the engine through resonance supercharging means. switching means for switching supercharging to the first intake system or the second intake system, and when the exhaust gas starts to be supplied to the rear turbocharger via the wastegate valve, the switching means switches the turbocharger to the front turbocharger. A multi-turbocharger characterized in that supercharging from a charger is switched from the first intake system to the second intake system and supplied to the engine.