JPH0640907Y2 - Two-stage turbocharger for internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a two-stage turbocharger for an internal combustion engine, and more particularly to a cooling system for rotary bearings of both turbochargers.

[Conventional technology]

Conventionally, regarding an internal combustion engine provided with a single turbocharger, various techniques for cooling the rotary bearing portion of the turbocharger have been proposed (Japanese Patent Laid-Open No. 53-68309 and Japanese Utility Model Publication No. 62-400).
(See Japanese Patent Publication No. 95).

[Problems to be solved by the device]

However, in a two-stage turbocharger in which two turbochargers are connected in series, a higher supercharging pressure is required, so that the low-pressure turbocharger operates the turbocharger of the conventional one-stage supercharger. Since there is a tendency to operate in a working range that is far beyond the range, it can be said that the cooling technology of the low-pressure stage turbocharger is insufficient only by the conventional cooling technology of the turbocharger rotary bearing section. In particular, it is necessary to consider more effective cooling because the cooling tends to be insufficient at the time of a dead soak in which the engine is immediately stopped after a long period of high load operation.

In view of the above points, it is an object of the present invention to provide a two-stage turbocharger for an internal combustion engine that can obtain better cooling performance by optimally arranging both turbochargers for cooling. It is an issue.

[Means for Solving the Problems]

In order to solve the above problems, according to the present invention, in a two-stage turbocharger for an internal combustion engine in which a small capacity high pressure turbocharger and a large capacity low pressure turbocharger are connected in series, the low pressure turbocharger is used. It is arranged below the high-pressure turbocharger and in the vicinity of the water outlet for cooling the rotary bearing portion of the turbocharger so that the low-pressure turbocharger has a larger water drop than the high-pressure turbocharger. A characteristic feature of the configuration is that the water jacket for cooling the rotary bearing of the turbocharger is connected to the water outlet.

[Action]

Compared to the high-pressure turbocharger, the low-pressure turbocharger is placed further down and closer to the water outlet, so that the water jacket and the water outlet of both turbochargers are placed so that the low-pressure turbocharger has a larger water drop. Since the connection is made, the flow of cooling water for cooling the rotary bearing portion of the low-pressure turbocharger becomes extremely smooth, and steam generated due to high heat easily escapes to the downstream side during dead soak, for example. As a result, natural convection of the cooling water effectively occurs, and particularly a good cooling effect of the low pressure stage turbocharger can be obtained.

〔Example〕

 The present invention will be described below with reference to illustrated embodiments.

FIG. 1 is an overall perspective view of an embodiment of a two-stage supercharging device for an internal combustion engine according to the present invention.

An exhaust manifold 2 that collects exhaust gas discharged from an exhaust port in one place is provided on a side portion of an engine 1 that is vertically arranged with respect to a vehicle body (not shown). On the engine rear side of the exhaust manifold 2, there is provided a first collecting opening opening to the side of the exhaust manifold, and the high pressure exhaust turbine 4 of the small capacity high pressure turbocharger 3 is directly attached to this portion. . Reference numeral 5 denotes a high pressure stage compressor driven by the high pressure stage exhaust turbine 4.

On the other hand, on the front side of the exhaust manifold 2 in the engine direction, a second collecting opening that is similarly opened to the side of the exhaust manifold is provided. A low pressure stage exhaust turbine 7 of a large capacity low pressure stage turbocharger 6 is attached to this portion via an exhaust control conduit 10. Reference numeral 8 is a low pressure stage compressor driven by the low pressure stage exhaust turbine 7.

The exhaust control conduit 10 has an exhaust control valve 30 that shuts off, restricts, or opens the flow of exhaust gas flowing from the exhaust manifold 2 directly into the low pressure stage exhaust turbine 7. This exhaust control valve 30
Is configured as a so-called poppet valve in which a control orifice is formed by a conical valve body called a poppet and a valve seat, which has a characteristic that leakage can be completely stopped when fully closed and the structure is simple. Reference numeral 34 is an exhaust control valve drive device that opens and closes the exhaust control valve 30. This drive 34
Is composed of a general pressure-operated actuator that uses positive pressure such as supercharging pressure, negative pressure from a vacuum tank, or both. The valve is controlled to open. Further, the exhaust control conduit 10 has an exhaust merging portion where the exhaust gas from the high pressure stage exhaust turbine 4 merges.

Exhaust gas from the high-pressure stage exhaust turbine 4 slightly extends along the axial center of the high-pressure stage turbocharger 3 from the discharge port of the high-pressure stage exhaust turbine 4, and passes through the exhaust pipe 9 attached to the exhaust control pipe 10 to the low-pressure stage. It can flow into the exhaust turbine 7. Further, the exhaust gas from the low pressure stage exhaust turbine 7 is released to the atmosphere via the exhaust pipe 11 and an exhaust gas purifying device (not shown).

The atmosphere flowing into the low-pressure compressor 8 of the low-pressure turbocharger 6 via an air cleaner (not shown) is supercharged here, then flows into the high-pressure compressor 5 via the intake conduit 15, and is further supercharged. After the intake conduits 16 and 17
In addition, it is sent to the intake port of the engine 1 via an intercooler (not shown) or the like.

An intake bypass passage 18 is formed so as to branch from the intake conduit 15 and bypass the high-pressure compressor 5, and an intake control valve 19 is provided in the intake bypass passage 18. The intake control valve 19 is configured as a poppet valve of the same type as the exhaust control valve 30 described above. Reference numeral 20 denotes a general pressure-actuated actuator that drives the intake control valve 19 to open and close.The actuator 20 controls the intake control valve 19 so that the intake control valve 19 is fully opened when supercharging is switched. In the front, it is kept in a fully closed state with no leakage.

Here, the operation of the two-stage supercharging device having the above-described configuration will be described first. The cooling relationship of the bearing portion of the turbocharger, which is a feature of the present invention, will be described later.

The exhaust gas amount is generally small in the engine low speed region, and in order to effectively use the energy of this small amount of exhaust gas, a high-pressure stage exhaust turbine 4 having a small capacity is rotated and a high-pressure stage compressor 5 that rotates integrally therewith is used. Supercharging is most effective. Therefore, the exhaust control valve 30 is maintained in the fully closed state. Therefore, the total amount of exhaust gas in the exhaust manifold 2 passes through the first collecting opening, drives the high pressure stage exhaust turbine 4, and then passes through the exhaust conduit 9 and the exhaust control conduit 10 to reach the low pressure stage exhaust turbine 7. Inflow. At this time, since the axial center directions of both turbochargers are aligned with each other and the high-pressure stage turbocharger 3 is offset upward and the low-pressure stage turbocharger 6 is offset downward,
Both turbochargers 3 and 6 can be arranged close to each other, and only one bent portion formed by the exhaust conduit 9 and the exhaust control conduit 10 (the pipe is not bent in the direction of the crankshaft axis) is a high-pressure exhaust turbine. The exhaust gas outlet of No. 4 and the exhaust gas inlet of the low-pressure stage exhaust turbine 7 can be connected to each other in the shortest time, and as a result, the energy of the exhaust gas can be used very effectively without waste.

At this time, similarly, the intake control valve 19 is maintained in the fully closed state. Therefore, the atmosphere sucked into the low-pressure stage compressor 8 is supercharged here, and then flows into the high-pressure stage compressor 5 through the intake pipe 15, and is further supercharged there, and then the intake pipes 16 and 17 are supplied. It is sent through to the intake port of the engine.

Next, from the low speed region to the medium / high speed region, the exhaust gas amount increases and the low pressure stage turbocharger 6 gradually begins to perform the original supercharging, so the supercharging pressure by the high pressure stage turbocharger 3 becomes the target supercharging pressure. The exhaust control valve 30 is gradually opened so that the boost pressure can be maintained. Therefore, in addition to the flow of the exhaust gas flowing out through the first collecting opening of the exhaust manifold 2, the exhaust gas flowing directly into the low pressure stage exhaust turbine 7 through the second collecting opening of the exhaust manifold 2. Flow occurs. Since the intake control valve 19 is maintained in the fully closed state even at this time, there is no particular change in the flow of intake air.

When the supercharging pressure by the low-pressure turbocharger 6 reaches this target supercharging pressure, the exhaust control valve 30 is fully opened at once and the substantial supercharging function is transferred from the high-pressure turbocharger 3 to the low-pressure turbocharger 6. Let That is, when the exhaust control valve 30 is fully opened, the exhaust gas in the exhaust manifold 2 bypasses the high pressure stage exhaust turbine 4 and flows more easily.
Almost all of the exhaust gas directly flows into the low pressure stage exhaust turbine 7 through the collecting opening and the exhaust control valve 30. Therefore, the high pressure stage turbocharger 3 is in a non-operating state. At this time, the intake control valve provided in the intake bypass passage 18 that bypasses the high-pressure compressor 5 of the high-pressure turbocharger 3
By fully opening 19, high pressure turbocharger 3
Is completely in the non-supercharging state, and the switching from the second-stage supercharging to the first-stage supercharging is reliably performed. That is, the supercharged air supercharged by the low-pressure compressor 8 bypasses the high-pressure compressor 5, and is sent to the engine via the intake bypass passage 18, the intake control valve 19, and the intake conduit 17 that flow more easily.

After the supercharging is switched, the supercharging pressure is maintained at a predetermined level by a waste gate valve (not shown) in terms of durability of the engine and the turbocharger.

As described above, when the exhaust control valve 30 is fully closed (low engine speed), as described above, the exhaust gas drives the high pressure stage exhaust turbine 4, and then the exhaust conduit 9 having a short and single bent portion is used. And, since it flows through the exhaust control conduit 10 and immediately flows into the low pressure stage exhaust turbine 7 to drive it, the supercharging efficiency is improved.

On the other hand, when the exhaust control valve 30 is fully opened (in the engine / high speed), the exhaust gas immediately flows into the low pressure stage exhaust turbine 7 from the exhaust manifold 2 through an extremely short flow path in the exhaust control conduit 10. Since this is driven, the supercharging efficiency is similarly improved.

In this way, two turbochargers connected in series
In the stage supercharging device, it has become possible to obtain a supercharging that is as high as that of the conventional one-stage supercharging device turbocharger. However, this is nothing but the rigorous use of the turbocharger from the other side, and especially the low-pressure stage turbocharger tends to be driven to rotate at high speeds at high speeds, so its own heat generation is extremely large, and it is more than the conventional one. Furthermore, it is necessary to actively protect the turbocharger from this heat damage.

Hereinafter, a cooling relationship of the turbocharger bearing portion, which is a feature of the present invention for solving the above problem, will be described.

Referring to FIG. 1, reference numeral 101 denotes a radiator provided to prevent the engine from overheating. Water cooled here is sent to a cylinder block side of the engine 1 by a pump (not shown), Enters the cylinder head while absorbing the heat of. And the water that absorbed the heat here is the water outlet 102 attached to the side of the engine.
Return to the upper tank (not shown) of the radiator 101 via.

As described above, the turbocharger becomes extremely hot due to the influence of high-temperature exhaust gas and the like, so that it is necessary to efficiently cool the rotary bearing portion thereof, and particularly to cool the low pressure stage turbocharger 6.

Therefore, the center housing of the low pressure stage turbocharger 6
Cooling water is supplied from the water supply pipe 103 to the water supply port of the center housing 6a via the pipe 104 to cool the rotary bearing portion in the 6a, and a water jacket (not shown) formed in the center housing 6a. The water that has absorbed the heat is sent to the water outlet 102 from the drain port of the center housing 6a through the pipe 105.

On the other hand, the center housing 3a of the high-pressure turbocharger 3
Similarly, in order to cool the rotary bearing portion therein, cooling water is supplied from the water supply pipe 103 to the water supply port of the center housing 3a through the pipe 106, and a water jacket (not shown) formed in the center housing 3a. The water that has absorbed the heat in (1) is sent to the water outlet 102 from the drain port of the center housing 3a through the pipe 107.

Since the low-pressure turbocharger 6 should be cooled more efficiently as described above, it is arranged below the high-pressure turbocharger 3 and near the water outlet 102 as shown in the figure. That is, in the positional relationship between the water outlet 102 and the water supply / drainage ports of both turbochargers, the low pressure stage turbocharger 6 has a larger difference A (A> B) than the high pressure stage turbocharger 3.
And are located at a distance A ′ (A ′ <B ′) closer to the water outlet 102.

Therefore, for example, if the engine is stopped immediately after high-load operation (during a dead soak), the water pump will stop and the forced circulation of cooling water will stop. Although it may be carbonized due to heat and the bearing performance may be extremely deteriorated, by arranging both turbochargers as in this embodiment, even if there is such a dead soak, cooling by the natural convection effect of the cooling water is possible. You can do it. That is, at the time of dead soak, steam is generated by the heat generated by the turbocharger and flows out to the water outlet 102 side very smoothly, so that natural convection of cooling water occurs. The direction of this flow is opposite to the cooling water flow direction in the engine operating state, and in the low pressure stage turbocharger 6, the cooling water flows backward from the pipe 105 to the center housing 6a and then to the pipe 104. become. The same applies to the high-pressure turbocharger 3. As a result, in the low-pressure stage turbocharger 6, which is in a particularly severe thermal condition, the natural convection effect allows extremely effective cooling.

In addition, the engine 1 and the auxiliary machinery are arranged in a narrow space in the engine room, and the empty space is generally extremely small. However, the lower side of the exhaust manifold 2 is the original because of heat radiation from the engine 1 and vibration of the engine 1. It is a place where there is some space to come, and it can be said that disposing the large-scale low-pressure stage turbocharger 6 below the exhaust manifold 2 as shown in the figure makes good use of the empty space in the engine room. it can.

Further, since the large-sized low-pressure stage turbocharger 6 is arranged on the vehicle front side (engine front side), the turbocharger can be effectively cooled by the traveling wind.

[Effect of device]

As described above, according to the present invention, by optimally arranging the two turbochargers for cooling, extremely excellent cooling performance of the turbocharger can be obtained and durability of the turbocharger can be improved.

[Brief description of drawings]

FIG. 1 is an overall perspective view of an embodiment of a two-stage supercharging device for an internal combustion engine according to the present invention. 1 ... Engine, 2 ... Exhaust manifold, 3 ... High pressure turbocharger, 6 ... Low pressure turbocharger, 19 ... Intake control valve, 20 ... Actuator, 30 ... Exhaust control valve, 34 ... Exhaust Control valve drive, 101 …… radiator, 102 …… water outlet, 103 …… water supply pipe, 104,105 …… pipe, 106,107 …… pipe, 3a …… center housing, 6a …… center housing.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-60-224939 (JP, A) Actual opening 59-86316 (JP, U) Actual opening 59-7231 (JP, U) Actual opening Flat 2- 85830 (JP, U) Actual flat 2-78731 (JP, U) Actual public Sho 62-14346 (JP, Y2)

Claims (1)

[Scope of utility model registration request] 1. A two-stage turbocharger for an internal combustion engine, comprising a small capacity high pressure turbocharger and a large capacity low pressure turbocharger connected in series, wherein the low pressure turbocharger is located below the high pressure turbocharger. And is arranged near the water outlet, and connects the water jackets for cooling the rotary bearings of both turbochargers to the water outlet so that the low-pressure turbocharger has a larger water drop than the high-pressure turbocharger. A two-stage supercharging device for an internal combustion engine, characterized in that